Metal powder production device and metal powder production method

Abstract

This metal powder production device for precipitating a metal from an electrolytic solution containing metal ions by electrolysis and recovering the metal in the form of metal powder comprises: an electrolytic bath; a first electrode structure that is disposed in the electrolytic bath and that is three-dimensionally formed by a plurality of first electrodes and has gaps between the first electrodes or is three-dimensionally formed by one first electrode, the one first electrode having a gap open to the outside; and a second electrode that is disposed in at least a portion in the gap in the first electrode structure so as not to contact a first electrode. One of the first electrode or the second electrode is an anode electrode, and the other is a cathode electrode.

Description

Apparatus for manufacturing metal powder, and method for manufacturing metal powder

[0001] This disclosure relates to an apparatus for manufacturing metal powder and a method for manufacturing metal powder.

[0002] Conventionally, various electrolytic deposition methods have been attempted to recover metal powder by electrolysis, which involves depositing metal from an electrolyte containing metal ions.

[0003] For example, Patent Document 1 discloses a method for producing copper powder, in which copper particles aggregate on the cathode to form a dendritic shape with multiple branches by electrolytic treatment using an electrolyte containing copper ions, wherein the electrolytic treatment is performed by PC pulse electrolysis, in which the on and off of the current supplied to the electrode is switched at a predetermined period, or PR pulse electrolysis, in which the direction of the current supplied to the electrode is switched between the forward and reverse directions at a predetermined period.

[0004] Patent Document 2 also discloses a metal recovery method comprising: (a) treating fumes using aqueous solutions of ammonium chloride and sodium chloride to dissolve zinc, cadmium and copper as ammine complex salts and lead as a chloro complex salt; (b) separating the resulting solution from the solid residue; (c) treating the solution obtained in (b) with zinc powder to precipitate metals nobler than zinc by substitution in an electrochemical series; (d) separating the solution from the precipitate obtained in (c); (e) in an electrolytic cell, attaching zinc to the cathode and generating oxygen at the anode to electrolytically collect zinc from the solution obtained in (d); (f) further treating the fumes from the electric furnace with the zinc loss solution obtained in (e); and (g) recirculating the residue from (b) into the electric furnace to reduce iron oxide and fumigate the zinc contained in the residue as ferrite zinc.

[0005] Furthermore, Patent Document 3 describes how to use ferroscraps containing galvanized steel in the presence of ammonia and ammonium salts [e.g., (NH4)]. ４ ) ２ CO ３ or (NH ４ ) ２ SO ４Step 1 involves treating the scrap with an aqueous solution containing [amount] to dissolve the zinc in the scrap as an amminezinc complex, and then separating the scrap from the aqueous solution. Step 2 involves heating the aqueous solution obtained in Step 1 to evaporate the ammonia, and then the precipitated zinc salt (ZnCO2) ３ ) can be recovered, or the dissolved zinc salt (ZnSO4) can be recovered. ４ A method for separating and recovering zinc from ferroscraps is disclosed, comprising step 2 of electrolyzing an aqueous solution containing ) to recover metallic zinc electrodeposited on the cathode.

[0006] Furthermore, Patent Document 4 discloses an apparatus for generating metal powder by electrolysis in a once-through electrolytic cell, comprising at least one once-through electrolytic cell including at least one once-through anode, at least one once-through cathode, and an electrolyte flow system. The anode / cathode spacing in the electrolytic cell, that is, the distance from the center line of the anode suspension rod to the center line of the adjacent cathode suspension rod, is preferably about 0.5 inches to about 4 inches, preferably less than about 2 inches. More preferably, the configured electrolytic cell has an anode / cathode spacing of about 1.5 inches or less.

[0007] Furthermore, Patent Document 5 discloses an apparatus and method for peeling off copper plates deposited on the surface of a cathode electrode using a wedge member.

[0008] JP 2019-218590, JP 5-255772, JP 5-271820, Special table 2008-507625, JP 2009-215598

[0009] Incidentally, in Patent Document 4, due to the flow in the electrolytic cell and the weight of the electrodeposition deposited on the cathode electrode, the electrode structure is structurally weak and easily deformed, and because the surfaces of the cathode electrode and the anode electrode are parallel and close together, the electrodes are prone to contact and there is a high risk of short circuits. Therefore, it is thought that the distance between the cathode and anode could not be made any smaller. Also, in Patent Document 5, when the deposited copper plate is peeled off by the wedge member, the cathode electrode may deform, and although this deformation can be corrected to some extent by mechanical force, the deformation often remains. For this reason, the distance between the cathode electrode surface and the anode electrode surface is often set to approximately 25 mm to 50 mm.

[0010] Conventionally, when recovering metal powder by electrolysis from an electrolyte containing metal ions, methods such as placing plate-shaped anode and cathode electrodes in the electrolyte and depositing the metal powder on the surface of the cathode electrode are used. However, there is a need to increase the deposition rate of metal powder per unit volume of the electrode.

[0011] Therefore, the present disclosure aims to provide a metal powder manufacturing apparatus and a metal powder manufacturing method that have a high deposition rate of metal powder per unit volume of the electrode portion.

[0012] The gist of this disclosure is as follows: <1> A metal powder manufacturing apparatus for depositing metal from an electrolyte containing metal ions by electrolysis and recovering it as metal powder, comprising: an electrolytic cell; a first electrode structure disposed in the electrolytic cell and three-dimensionally composed of a plurality of first electrodes with gaps between each of the first electrodes, or three-dimensionally composed of a single first electrode with a gap in which the single first electrode is open to the outside; and a second electrode disposed such that at least a portion of the gap in the first electrode structure is not in contact with the first electrode, wherein one of the first electrode and the second electrode is an anode electrode and the other is a cathode electrode. <2> The metal powder manufacturing apparatus according to <1>, further comprising a mechanism for peeling off the metal powder deposited on the surface of the cathode electrode from the cathode electrode. <3> The metal powder manufacturing apparatus according to <1> or <2>, wherein the first electrode structure is a first electrode structure that is three-dimensionally composed of the plurality of first electrodes and has a gap between each of the first electrodes, and the first electrode structure has a plurality of grid-like planar electrode bodies in which the plurality of first electrodes are arranged in a planar manner, and the plurality of grid-like planar electrode bodies are stacked with space between them, or has a grid-like three-dimensional structure in which the plurality of first electrodes are arranged in a planar manner, and the plurality of grid-like planar electrode bodies are stacked with space between them, and the grid-like planar electrode bodies are connected to each other. <4> The metal powder manufacturing apparatus according to <3>, wherein the shape of the second electrode is wire-like or rod-like, and the second electrode is arranged in the gap of the first electrode structure. <5> The metal powder manufacturing apparatus according to any one of <1> to <4>, wherein the first electrode structure comprises a plurality of first electrodes arranged in parallel with each other, each being wire-shaped or rod-shaped and with a gap between them, and a plurality of second electrodes arranged in the gap in the first electrode structure in a direction perpendicular or oblique to the plurality of first electrodes, and each of the plurality of second electrodes arranged is wire-shaped or rod-shaped and arranged parallel to each other.<6> The metal powder manufacturing apparatus according to any one of <1> to <5>, wherein the first electrode structure and the second electrode are fixed to a support which is an insulator. <7> The metal powder manufacturing apparatus according to any one of <1> to <6>, wherein at least one of the first electrode structure and the second electrode has a surface that is in contact with the liquid surface of the electrolyte covered with an insulator. <8> The metal powder manufacturing apparatus according to any one of <1> to <8>, wherein the distance of the second electrode to the nearest first electrode is in the range of 1 mm to 50 mm. <9> The metal powder manufacturing apparatus according to <8>, wherein the distance of the second electrode to the nearest first electrode is in the range of 1 mm to 20 mm. <10> The metal powder manufacturing apparatus according to <9>, wherein the distance of the second electrode to the nearest first electrode is in the range of 2 mm to 10 mm. <11> The metal powder manufacturing apparatus according to <10>, wherein the distance of the second electrode to the nearest first electrode is in the range of 2 mm to 5 mm. <12> The metal powder manufacturing apparatus according to <2>, wherein the peeling mechanism is at least one selected from the group consisting of a device for generating ultrasonic waves and a device for applying impact to the cathode electrode. <13> A method for manufacturing metal powder using the metal powder manufacturing apparatus according to any one of <1> to <12>, wherein the metal powder contains at least one of copper and zinc, and the electrolyte is an acidic electrolyte with a pH of 1.0 to 5.0, a strongly alkaline electrolyte with a pH of 13.0 to 14.5, or an ammonia-containing alkaline electrolyte with a pH of 7.0 to 12.0 containing ammonia. <14> A method for processing iron scrap, comprising: a leaching step of leaching at least one of copper and zinc into a leaching solution; and an electrodeposition step of electrodepositing at least one of the leached copper and zinc, and separating at least one of the copper and zinc from the leaching solution, wherein in the electrodeposition step, a metal powder manufacturing apparatus described in any one of <1> to <12> is used, an ammonia-containing alkaline leaching solution is used as the leaching solution, the leaching solution from which at least one of the copper and zinc has been leached is used as the electrolyte, and at least one of the copper and zinc is electrodeposited from the electrolyte.<15> The method for processing iron scrap according to <14>, further comprising a heat treatment step of heat-treating the iron scrap before the leaching step. <16> The method for processing iron scrap according to <14> or <15>, further comprising a quality improvement step of improving the quality of the iron scrap after the leaching step. <17> The method for processing iron scrap according to <15>, further comprising a sorting step of sorting the iron scrap before the heat treatment step. <18> The method for processing iron scrap according to any one of <14> to <17>, wherein the electrodeposition step is a multi-stage electrodeposition step, and the voltages applied to the first electrode and the second electrode in the metal powder manufacturing apparatus installed in each electrodeposition step are controlled to be different voltages. <19> The method for processing iron scrap according to <15>, wherein in the heat treatment step, the heating temperature of the iron scrap is 350°C to 800°C. <20> The method for processing iron scrap according to <15>, wherein in the heat treatment step, the heating temperature of the iron scrap is 400°C to 600°C. <21> The method for processing iron scrap according to any one of <15> to <19>, wherein in the heat treatment step, the iron scrap is subjected to heat treatment while being rolled. <22> A method for recovering metallic zinc from dust, comprising leaching at least the zinc component from dust containing zinc oxide using a leachate, and recovering metallic zinc by electrolytic extraction from the obtained leachate containing zinc ions, wherein the leachate is an acidic leachate with a pH of 1.0 to 5.0, a strongly alkaline leachate with a pH of 13.0 to 14.5, or an ammonia-containing alkaline leachate with a pH of 7.0 to 12.0 containing ammonia, and a metal powder manufacturing apparatus described in any one of <1> to <12> is used as the apparatus for electrolytic extraction, the leachate from which the zinc component has been leached is used as the electrolyte, and at least the metallic zinc is electrodeposited from the electrolyte, a method for recovering metallic zinc from dust.<23> The dust containing zinc oxide is added to 1 L of an ammonium sulfate aqueous solution adjusted to pH 9.5 to 11.5 with an aqueous sodium hydroxide solution, with a concentration of 185 g / L, in an amount such that the zinc content is 4 g of the dust containing zinc oxide into a sealed container, and shaken in the sealed container for 24 hours to leach zinc into the leaching solution. The zinc content rate and iron content rate in the dust containing zinc oxide before and after leaching are measured, and the zinc oxide rate of the dust containing zinc oxide calculated from the following formula is 40% or more. A method for recovering metallic zinc from the dust according to <22>. Zinc oxide rate of dust containing zinc oxide = { (Zn content rate before leaching / Fe content rate before leaching) - (Zn content rate after leaching / Fe content rate after leaching)} ÷ (Zn content rate before leaching / Fe content rate before leaching) × 100 <24> The dust containing zinc oxide is electric furnace dust generated from an arc discharge type electric furnace for steel manufacturing, and the (H ２ +CO) / (H ２ O + CO ２ ) is a molar ratio of 2.0 × 10 －２ or more. A method for recovering metallic zinc from the dust according to <23>. <25> By adjusting the amount of at least one of the gas containing hydrogen and the organic compound introduced into the electric furnace, the (H ２ +CO) / (H ２ O + CO ２ ) is a molar ratio of 2.0 × 10 －２A method for recovering metallic zinc from dust according to <24>, wherein the electric furnace is operated in such manner. <26> A method for recovering metallic zinc from dust according to any one of <22> to <25>, wherein the dust containing zinc oxide is magnetically separated into magnetic and non-magnetic materials, the non-magnetic materials after separation are immersed in the leachate to extract zinc components, and metallic zinc is precipitated from the obtained leachate containing zinc ions by electrolytic extraction to recover metallic zinc. <27> A method for recovering metallic zinc from dust according to any one of <22> to <26>, wherein metallic zinc is further added to the leachate containing zinc ions to precipitate elements with a lower ionization tendency than zinc from the leachate containing zinc ions, and metallic zinc is precipitated from the intermediate leachate containing zinc ions after separating the precipitates by electrolytic extraction to recover metallic zinc. <28> A method for recovering metallic zinc from dust according to any one of <22> to <27>, wherein, after removing the leachate attached to the metallic zinc precipitated and recovered by electrolytic extraction, the metallic zinc is melted and the molten metallic zinc is recovered.

[0013] According to this disclosure, a manufacturing apparatus and a method for manufacturing metal powder are provided, which have a high deposition rate of metal powder per unit volume of the electrode portion.

[0014] This is a schematic top view showing a calculation area for verifying the current density based on the distance between the anode and cathode electrodes. This is a graph showing the relationship between the distance between the anode and cathode electrodes and the current density. This is a graph showing the relationship between the width of the wire connected to the cathode electrode and the current density. This is a graph showing the relationship between the number of wires connected to the cathode electrode and the current density. This is a schematic perspective view showing a calculation area for verifying the effect of the distance between the anode and cathode electrodes on the current density. This is a graph showing the relationship between the shortest distance between the anode and cathode electrodes and the current per unit volume of the electrode section. This is a graph showing an enlarged portion of Figure 6. This is a graph showing the relationship between the spacing between cathode electrodes and the current per unit volume of the electrode section. This is a schematic side view showing a metal powder manufacturing apparatus according to the first embodiment. This is a schematic side view showing the X'-X' cross section in Figure 9. This is a schematic top view showing a metal powder manufacturing apparatus according to the second embodiment. This is a schematic front view showing a metal powder manufacturing apparatus according to the second embodiment. This is a schematic side view showing a metal powder manufacturing apparatus according to the second embodiment. This is a schematic front view showing a metal powder manufacturing apparatus according to the third embodiment. This is a schematic top view showing the cathode electrode and anode electrode in a metal powder manufacturing apparatus according to the third embodiment. This is a schematic front view showing the electrode unit of a metal powder manufacturing apparatus according to the fourth embodiment. This is a schematic cross-sectional view showing the A-A section in Figure 16. This is a schematic front view showing a metal powder manufacturing apparatus according to the fourth embodiment, which is unitized by having the electrode unit installed alongside it. This is an image showing an example of welded wire mesh. This is an image showing an example of expanded metal. This is an image showing an example of metal mesh. This is an image showing an example of metal wool. This is an image showing an example of metal wire. This is a schematic side view showing a metal powder manufacturing apparatus having a diaphragm between a first electrode and a second electrode. This is a schematic side view showing a metal powder manufacturing apparatus having a first electrode structure in which a plurality of linearly extending first electrodes are arranged in parallel. This is a schematic cross-sectional view showing the A-A section in Figure 25. This is a schematic side view showing a metal powder manufacturing apparatus having a first electrode structure in which a plurality of linearly extending first electrodes are arranged in parallel and a second electrode structure in which a plurality of linearly extending second electrodes are arranged in parallel in the same direction as the first electrodes. This is a schematic cross-sectional view showing the A-A section in Figure 27. Figure 27 is a schematic side view showing an electrode equipped with a spacer to prevent short circuits.This is a schematic diagram showing an example of processing steps for implementing the iron scrap processing method of this disclosure. This is a schematic diagram showing an example of the configuration of an arc discharge type electric furnace (arc furnace) and a dust collection system for recovering electric furnace dust. This is a schematic diagram showing an example of the configuration of a metallic zinc recovery device for implementing the metallic zinc recovery method from dust of this disclosure. This is a schematic cross-sectional view showing the section A-A in Figure 32. This is a schematic side view showing an embodiment in which the electrodes shown in Figure 32 are equipped with spacers for preventing short circuits. This shows the exhaust gas temperature at the electric furnace outlet and the molar ratio (H) in the exhaust gas. ２ +CO) / (H ２ O+CO ２ This is a graph showing an example of the relationship between ( ) and the zinc oxide content in electric furnace dust. This is a schematic front view showing an example of the configuration of an electroanalytic emission test apparatus. This is a schematic cross-sectional view showing the A-A section in Figure 36. This is a schematic front view showing an example of the configuration of an electroanalytic emission test apparatus. This is a schematic top view showing the cathode electrode and anode electrode in the electroanalytic emission test apparatus shown in Figure 38.

[0015] An example of an embodiment of this disclosure is described in detail below.

[0016] In this specification, numerical ranges expressed using "~" mean a range that includes the numbers before and after "~" as the lower and upper limits, unless otherwise specified. However, if there is a notation such as "greater than" or "less than", it means that the numbers before and after "~" are not included as at least one of the lower and upper limits. In numerical ranges described in steps, the upper or lower limit stated in one numerical range may be replaced with the upper or lower limit of another numerical range described in steps. In numerical ranges, the upper or lower limit stated in one numerical range may be replaced with the value shown in the example. The terms "process" or "step" are included not only in the sense of an independent process or step, but also in the sense that a process or step cannot be clearly distinguished from other processes or steps, as long as the intended purpose of the process or step is achieved. "Wire-shaped or rod-shaped electrode" refers, for example, to an electrode with a maximum diameter (maximum diameter if the cross-sectional shape is circular) of 20 mm or less (preferably 2 mm or more and 10 mm or less).

[0017] <Apparatus for Manufacturing Metal Powder> An apparatus for manufacturing metal powder according to an embodiment of the present disclosure (hereinafter also simply referred to as "the apparatus for manufacturing metal powder of the present disclosure") is an apparatus for depositing metal from an electrolyte containing metal ions by electrolysis and recovering it as metal powder. The apparatus for manufacturing metal powder comprises an electrolytic cell, a first electrode structure, and a second electrode. The first electrode structure is disposed in the electrolytic cell. The first electrode structure is three-dimensionally composed of a plurality of first electrodes with gaps between each of the first electrodes, or is three-dimensionally composed of a single first electrode with a gap in which the single first electrode is open to the outside. The second electrode is disposed such that it is not in contact with the first electrode in at least a portion of the gap in the first electrode structure. One of the first electrode and the second electrode is the anode electrode, and the other is the cathode electrode. Here, "electrode structure," including the first electrode structure and the second electrode structure described later, refers to a structure in which multiple electrodes are arranged spaced apart from each other, or in which one electrode is bent or curved, and which has a gap (i.e., a gap formed between electrodes) that is open to the electrolyte and into which the electrolyte can flow. Furthermore, "the second electrode is arranged so as to be in non-contact with the first electrode in at least a portion of the gap in the first electrode structure" means that the second electrode is arranged so as not to cause an electrical short circuit with the first electrode during electrolysis.

[0018] Conventionally, when recovering metal powder by electrolysis from an electrolyte containing metal ions, methods such as placing plate-shaped anode and cathode electrodes in the electrolyte and depositing metal powder on the surface of the cathode electrode, or through-flow methods, have been employed. However, in these conventional methods, the distance between the anode and cathode electrodes is large, resulting in high resistance in the electrolyte, and the electrode surface area per unit volume cannot be increased. As a result, the current per unit volume of the electrode is small, and when the current efficiency is constant, the deposition rate of metal powder per unit volume of the electrode is small. Therefore, in order to produce a large amount of metal powder, it is necessary to increase the electrode area, which leads to larger manufacturing equipment. In particular, in electrolytic reactions that generate gases that need to be recovered (e.g., ammonia gas), the equipment must be sealed, so if the manufacturing equipment is large, the cost increases significantly. Therefore, it is necessary to increase the current per unit volume of the electrode in the electrolytic reaction and increase the deposition rate of metal powder per unit volume of the electrode. One way to increase the current per unit volume of the electrode is to reduce the distance between the anode and cathode electrodes. However, with conventional methods such as arranging plate-shaped anode and cathode electrodes as described above, it was difficult to reduce the distance between the cathode electrode and the anode electrode due to factors such as the molding precision of the electrode plates and the support that fixes them.

[0019] In contrast, the metal powder manufacturing apparatus of the present disclosure comprises a first electrode structure which is three-dimensionally composed of a plurality of first electrodes with gaps between each of the first electrodes, or a first electrode which is three-dimensionally composed of a single first electrode with a gap that is open to the outside, and a second electrode which is arranged so as to be non-contact with the first electrode in at least a part of the gap in the first electrode structure. One of the first electrode and the second electrode is an anode electrode, and the other is a cathode electrode. By arranging the second electrode in the gap of the first electrode structure which is three-dimensionally composed of one or more first electrodes in this way, the distance between the anode electrode and the cathode electrode can be reduced. As a result, in the metal powder manufacturing apparatus of the present disclosure, the current per unit volume of the electrode section can be increased, and the deposition rate of metal powder per unit volume of the electrode section can be increased.

[0020] Furthermore, even when producing large quantities of metal powder, the size of the manufacturing equipment is kept to a minimum. Therefore, even when the equipment needs to be enclosed (for example, in the case of electrolytic reactions that generate gases that need to be recovered, such as ammonia gas), the size of the manufacturing equipment is kept to a minimum, and costs are reduced.

[0021] In electrolysis, electrons are removed by an oxidation reaction on the surface of the anode electrode, and these removed electrons are consumed by a reduction reaction on the surface of the cathode electrode, resulting in the deposition of metal powder on the cathode electrode surface. Since electrons hardly move through the electrolyte, while metal ions move through it, it can be considered that a pseudo-current flows through the electrolyte. Therefore, we investigated a metal powder manufacturing apparatus that can increase the current per unit volume of the electrode and thus increase the deposition rate of metal powder per unit volume of the electrode, by assuming that a current flows through the electrolyte.

[0022] In electrolytic deposition, the voltage drop from the power source to both electrodes (anode or cathode) is usually designed to be negligible and therefore negligible. Furthermore, the voltage drop associated with the reaction at the electrode surfaces is largely determined by the electrode material, elementary reaction, and overpotential, and the voltage drop in the electrolyte, described later, is often larger. On the other hand, the conductivity of the electrolyte is usually 100 S / m or less, which is about four to five orders of magnitude lower than that of a conductor. Therefore, as the distance between the two electrodes increases, the voltage drop becomes very large. For this reason, the distance between the anode and cathode electrodes is important in order to increase the deposition rate of metal powder per unit volume of the electrode area.

[0023] Therefore, we investigated the current density with respect to the distance between the anode and cathode electrodes. Figure 1 is a schematic top view showing the calculation area for investigating the current density with respect to the distance between the anode and cathode electrodes.

[0024] In the calculation area 110 (300 mm square, 10 mm thick) shown in Figure 1, an anode electrode 104 with a potential of 1 V and a cathode electrode 102 (width 100 mm) with a potential of 0 V were installed. A wire 102A (width t mm, thickness 10 mm) was connected to the cathode electrode 102. The calculation area 110 was filled with electrolyte 112. In the calculation, the voltage and current in the calculation area 110 were calculated by changing the wire width (t), the distance between the wire and the anode (d), and the number of wires. From the current from the anode electrode 104, the current density per unit area from the anode area (100 × 10 mm) was calculated. The conductivity of the electrolyte 112 was 14 S / m (equivalent to an electrolyte containing ammine complex copper), and the conductivity of the wire 102A was 1.4 × 10⁻⁶. ６ The value is S / m (equivalent to stainless steel). The results are shown in Figure 2.

[0025] As shown in Figure 2, the distance d between wire 102A and anode electrode 104 has an effect, and it can be said that the current density at anode electrode 104 increases rapidly as the distance decreases. A similar trend is observed in actual tests.

[0026] Next, Figure 3 shows the relationship between the width t of wire 102A and the current density. As shown in Figure 3, it can be said that as the width t of wire 102A increases, the current density at the anode electrode 104 increases slightly.

[0027] Next, Figure 4 shows the relationship between the increase or decrease in the number of wires 102A of the same width and the current density. As shown in Figure 4, the current density at the anode electrode 104 increases significantly when the number of wires 102A increases, but the rate of increase in current density slows down as the distance d increases.

[0028] From the above, it can be seen that the current between the wire and the anode electrode flows concentrated at the tip of the wire. This is thought to be because the conductivity of the electrolyte is about 5 orders of magnitude lower than the conductivity of the wire, and the current flows through the path with the lowest electrical resistance.

[0029] Therefore, it can be seen that the distance between the cathode electrode (the wire connected to the cathode electrode in this verification example) and the anode electrode can be reduced, and furthermore, by adopting a configuration that increases the number of cathode electrodes (the wire connected to the cathode electrode in this verification example), the current density can be increased, and the deposition rate of metal powder per unit volume of the electrode can be increased. In conventional electrolytic deposition, where the electrode shape is plate-shaped, the anode electrode and cathode electrode are installed in parallel, and the electrode tips are not fixed, resulting in poor molding accuracy of the electrode plate. Furthermore, it is easily deformed by the flow of the electrolyte and the mass of the electrode precipitate deposited on the surface of the cathode electrode. For this reason, it was difficult to reduce the distance between the electrodes in order to prevent electrical short circuits caused by contact between the electrode tips. In contrast, in the metal powder manufacturing apparatus described later, as shown in Figure 5 below, cathode electrodes, which are grid-shaped planar electrodes, are stacked with gaps in between, and the anode electrode is installed in the grid-shaped portion (gap portion) of the grid-shaped planar electrode which is the cathode electrode. Furthermore, by positioning the cathode electrode in a direction that makes it prone to deformation, the risk of short circuits between electrodes can be reduced, and the distance between the anode electrode and the cathode electrode can be reduced. Alternatively, by positioning the second electrode in the gap of a first electrode structure, which is three-dimensionally formed by one or more first electrodes, the first electrode structure can be made less prone to bending, resulting in a structure that is less susceptible to deformation due to electrolyte flow or electrodeposit mass. In addition, the precision of electrode placement can be increased. For these reasons, the distance between the anode electrode and the cathode electrode can be reduced.

[0030] Based on the above findings, the current per unit volume of the electrode portion was calculated in an electrode system consisting of a grid-like cathode electrode 202 and a rod-shaped anode electrode 204, as shown in Figure 5. Specifically, the grid opening (length W1 in Figure 5) of the cathode electrode 202 (using wire mesh) was set to 3 mm to 101 mm, the distance (shortest distance) between all cathode electrodes 202 and the anode electrode 204 closest to each cathode electrode 202 was set to 1 mm to 50 mm, and the spacing between cathode electrodes 202 (wire mesh spacing, (length d in Figure 5)) was set to 1 mm to 50 mm. The current flowing between the anode electrode 204 with a potential of 1 V and the cathode electrode 202 with a potential of 0 V was calculated. From the calculation result, the value was calculated by dividing by the occupied volume of the electrodes to determine the current per unit volume of the electrode portion. The cross-section of the wires of the cathode electrode 202 and anode electrode 204 is a 1 mm square. Furthermore, the conductivity of the electrolyte and wire is 14 S / m (equivalent to the electrolyte containing ammine complex copper) and 1.4 × 10⁻⁶, respectively. ６ The current was set to S / m (equivalent to stainless steel). The current per unit volume of the electrode section is the value obtained by dividing the current flowing between the anode electrode 204 and the cathode electrode 202 by the anode electrode area. The anode electrode area is the volume of the electrically effective electrode section, and in Figure 5, it is represented as length L × width W2 × height H.

[0031] Figures 6 and 7 show the effect of the shortest distance between the anode electrode 204 and the cathode electrode 202. Figure 7 is an enlarged graph of a portion of Figure 6. As shown in Figure 6, reducing the shortest distance between the anode electrode 204 and the cathode electrode 202 reduces the resistance of the electrolyte between the electrodes, and the current value increases significantly. Furthermore, when the potential difference between the two electrodes is increased from 1V to 10V, the current per unit volume of the electrode section increases by approximately 10 times, and as shown in Figure 7, even when the shortest distance between the cathode electrode 202 and the anode electrode 204 is 50 mm, the current is approximately 18 kA / m ３This allows for the flow of a large current. When metal powder is deposited on the surface of the cathode electrode 202, the distance between the two electrodes decreases, so the current per unit volume of the electrode increases, allowing for the flow of an even larger current. Reducing the shortest distance between the anode electrode 204 and the cathode electrode 202 reduces the resistance of the electrolyte and increases the current per unit volume of the electrode, but also increases the risk of short circuits between the two electrodes. It is preferable to determine the shortest distance between the anode electrode 204 and the cathode electrode 202 by considering the installation accuracy and manufacturing accuracy of the electrodes, as well as the reduction in the distance between the two electrodes due to electrolytic defects.

[0032] Next, Figure 8 shows the effect of the distance d between the cathode electrodes 202. As shown in Figure 8, if the distance d between the cathode electrodes 202 is in the range of 9 mm to 50 mm, the current per unit volume of the electrode area increases as the distance d between the cathode electrodes 202 decreases. If the distance d between the cathode electrodes 202 is less than 9 mm, the current per unit volume of the electrode area does not increase significantly even if the distance d between the cathode electrodes 202 decreases.

[0033] Next, as shown in Figure 5, we will explain the relationship between the potential difference between the cathode electrode and the anode electrode (hereinafter referred to as "potential difference") and the flow of current in an electrode system consisting of a grid-shaped cathode electrode 202 and a rod-shaped anode electrode 204. When the potential difference is small, no current flows between the cathode electrode and the anode electrode. However, as the potential difference increases, current flows mainly at the point where the cathode electrode and the anode electrode are closest together. In other words, current flows around the shortest distance between the cathode electrode and the anode electrode. As the potential difference increases further, current begins to flow even in the electrode portion that is farther away from the point where the cathode electrode and the anode electrode are closest together, and current flows throughout the entire electrode. Furthermore, on the surface of the cathode electrode through which current flows, metal ions are reduced and metal is deposited.

[0034] Preferred embodiments of the metal powder manufacturing apparatus of this disclosure will be described below.

[0035] Figure 9, the first embodiment, is a schematic side view showing a metal powder manufacturing apparatus according to the first embodiment. Figure 10 is a schematic side view showing the X'-X' cross-section in Figure 9.

[0036] The manufacturing apparatus 100A shown in Figures 9 and 10 has two electrolytic reactors 1000A and 1000B within an electrolytic cell 60. Both electrolytic reactors 1000A and 1000B have a cathode electrode structure (corresponding to the first electrode structure) which is three-dimensionally lattice-shaped, with multiple grid-like cathode electrodes 2A and 2B (corresponding to the first electrode) stacked vertically (vertically in the direction of gravity) with gaps between them, and the grid-like cathode electrodes 2A and 2B are connected to each other vertically. The cathode electrode structure is connected to busbars 20A and 20B. The cathode electrodes 2A and 2B are fixed to insulating supports 10A and 10B.

[0037] Both electrolytic reactors 1000A and 1000B have multiple anode electrodes 4A and 4B. The anode electrodes 4A and 4B are rod-shaped. A preferred shape for the anode electrodes 4A and 4B is also a wire shape. The multiple anode electrodes 4A and 4B are connected to busbars 40A and 40B. The rod-shaped anode electrodes 4A and 4B extend vertically downward from the busbars 40A and 40B to the supports 10A and 10B. The anode electrodes 4A and 4B are fixed to the insulating supports 10A and 10B.

[0038] As shown in Figures 9 and 10, the anode electrodes 4A and 4B are positioned in the gaps between the cathode electrodes 2A and 2B, which constitute the cathode electrode structure, a lattice-like three-dimensional structure. The anode electrodes 4A and 4B are positioned so as to be non-contact with the cathode electrodes 2A and 2B. By making the cathode electrode structure a lattice-like three-dimensional structure that is resistant to bending, deformation due to electrolyte flow and electrodeposit mass is less likely to occur, thereby reducing the risk of short circuits between electrodes and allowing the distance between the anode and cathode electrodes to be reduced.

[0039] Busbars 20A and 40A are connected to the same power supply (not shown), and busbars 20B and 40B are connected to the same power supply (not shown). As shown in Figure 10, busbars 20A and 20B have thickened corners to allow large currents to flow (to reduce resistance). Electrolyte 12 is poured into the electrolytic cell 60. The electrolyte 12 is injected into the electrolytic cell 60 from the location indicated by arrow A, and any excess electrolyte 12 is discharged from the electrolytic cell 60 from the location indicated by arrow B. By passing current from the power supply to the cathode electrodes 2A and 2B and the anode electrodes 4A and 4B through busbars 20A and 20B and busbars 40A and 40B, metal ions contained in the electrolyte 12 are deposited as metal powder on the surface of the cathode electrodes 2A and 2B.

[0040] Thus, by creating a three-dimensional structure in which multiple grid-like first electrodes (cathode electrodes 2A and 2B in Figures 9 and 10) are stacked vertically (vertically in the direction of gravity) with gaps between them, and the grid-like first electrodes are vertically connected to each other, the metal powder deposited on the surface of the cathode electrode can easily pass between the electrodes when it is removed by the metal powder removal mechanism described later. In addition, because there are many voids, fluid movement by ultrasound or agitation is more likely to occur in the metal powder removal mechanism described later. Furthermore, gases generated on the surface of the anode electrode (e.g., oxygen gas) can also easily pass between the electrodes. Furthermore, if the shape of the second electrode (anode electrodes 4A and 4B in Figures 9 and 10) is wire-like or rod-like, and the second electrode is placed in the gap of the first electrode which constitutes the lattice-like three-dimensional structure of the first electrode, it is possible to create a structure in which the anode electrode and cathode electrode intersect three-dimensionally, thereby increasing the deposition rate of metal powder per unit volume of the electrode portion.

[0041] In the electrolyte 12 of the electrolytic cell 60, for example, an ultrasonic generator 80 is placed as a mechanism to detach metal powder deposited on the surfaces of the cathode electrodes 2A and 2B from the cathode electrodes 2A and 2B. However, the mechanism for detaching the metal powder from the cathode electrodes 2A and 2B is an arbitrary mechanism. In other words, the metal powder deposited on the surfaces of the cathode electrodes 2A and 2B may be detached from the cathode electrodes 2A and 2B by a mechanism outside the metal powder manufacturing apparatus. In addition, a device that applies impact to the cathode electrodes 2A and 2B (for example, a device that applies impact by physical blow) can also be applied as a mechanism for detaching the metal powder from the cathode electrodes 2A and 2B. After metal powder is deposited on the surfaces of the cathode electrodes 2A and 2B by the electrolytic reaction, the metal powder can be detached from the surfaces of the cathode electrodes 2A and 2B by generating ultrasonic waves with the ultrasonic generator 80. Furthermore, ultrasonic shielding plates 82A, 82B, 82C, and 82D are provided in the electrolyte 12 of the electrolytic cell 60 on the side and bottom sides of the electrolytic reaction devices 1000A and 1000B to shield against ultrasonic waves.

[0042] The electrolytic cell 60 has funnel-shaped (i.e., conical) funnel sections 62A and 62B at the lower part (downward in the vertical direction) of the electrolytic reaction apparatus 1000A and 1000B for collecting metal powders 120A and 120B that have been detached from the surfaces of the cathode electrodes 2A and 2B. Furthermore, a cylinder (not shown) for collecting the metal powders 120A and 120B is provided at the tip of the funnel sections 62A and 62B in the electrolytic cell 60. The metal powders 120A and 120B that have been detached from the surfaces of the cathode electrodes 2A and 2B settle downward in the vertical direction and are collected through the funnel sections 62A and 62B and the cylinder (not shown).

[0043] In conventional electrolytic devices, for example, a plate-shaped cathode electrode and an anode electrode are installed in parallel. In this electrolytic device, in order to remove metal powder, for example, the electrolytic reaction is temporarily stopped, the cathode electrode on which metal powder has been deposited is removed from the electrolytic cell, and a wedge is driven between the cathode electrode and the deposited metal powder phase to remove the metal powder. After that, the cathode electrode is returned to the electrolytic cell and the electrolytic reaction is performed again. In contrast, the device shown in the first embodiment has a first electrode structure (e.g., cathode electrode structure) which is three-dimensionally composed of a plurality of first electrodes (e.g., cathode electrodes) and has a gap between each of the first electrodes, and a second electrode (e.g., anode electrode) which is arranged in the gap in the first electrode structure so as to not be in contact with the first electrodes. Furthermore, as a mechanism for removing metal powder deposited on the surface of the cathode electrode, it has at least one selected from the group consisting of a device that generates ultrasonic waves and a device that applies impact to the cathode electrode. Therefore, it is not necessary to temporarily stop the electrolytic reaction and remove the cathode electrode with the deposited metal powder from the electrolytic cell. In other words, the metal powder can be continuously collected while the electrolytic reaction continues. From this perspective, the rate of metal powder deposition per unit volume of the electrode can be further increased. However, if the amount of metal powder generated on the cathode electrode becomes too large, a short circuit will occur between the electrodes, reducing the efficiency of metal powder production. Therefore, to prevent short circuits between the electrodes, it is preferable to remove the metal powder deposited on the surface of the cathode electrode at regular time intervals or when the current value increases.

[0044] • Second aspect: With the recent development of metal 3D printers, the degree of freedom in designing electrode structures has increased. For example, both the anode and cathode electrodes can be made into a grid. In other words, an electrolytic reaction apparatus can be constructed by incorporating the grid portion of one electrode into the grid portion of the other electrode.

[0045] Figure 11 is a schematic top view showing a metal powder manufacturing apparatus according to the second embodiment. Figure 12 is a schematic front view showing a metal powder manufacturing apparatus according to the second embodiment. Figure 13 is a schematic side view showing a metal powder manufacturing apparatus according to the second embodiment. Note that in the manufacturing apparatus 100C shown in Figures 11 to 13, the electrolytic cell, electrolyte, and metal powder detachment mechanism are omitted from the description.

[0046] The manufacturing apparatus 100C shown in Figures 11 to 13 has a cathode electrode structure (corresponding to the first electrode structure) which is three-dimensionally lattice-shaped, with multiple grid-like cathode electrodes 2C (corresponding to the first electrode) stacked vertically (vertically in the direction of gravity) with gaps between them, and the grid-like cathode electrodes 2C connected to each other vertically. The cathode electrode structure has air gaps between the cathode electrodes 2C. The cathode electrode structure is connected to a busbar (not shown). The cathode electrodes 2C are fixed to a support 10C which is an insulator.

[0047] The manufacturing apparatus 100C has an anode electrode structure that is three-dimensionally lattice-shaped, with multiple grid-like anode electrodes 4C (corresponding to the second electrode) stacked vertically (vertically in the direction of gravity) with gaps between them, and the grid-like anode electrodes 4C connected to each other vertically. The anode electrode structure has air gaps between the anode electrodes 4C. The anode electrode structure is connected to a busbar (not shown). The anode electrodes 4C are fixed to a support 10C which is an insulator.

[0048] Furthermore, the cathode electrode structure is formed by stacking multiple grid-like cathode electrodes vertically (in the direction of gravity) with gaps between them, and connecting the grid-like cathode electrodes vertically; and the anode electrode structure is formed by stacking multiple grid-like anode electrodes vertically (in the direction of gravity) with gaps between them, and connecting the grid-like anode electrodes vertically; in this configuration, the grid-like portion of one electrode is incorporated into the grid-like portion of the other electrode.

[0049] The anode electrode 4C is positioned within the voids in the cathode electrode structure, specifically within the voids of the lattice-like cathode electrode 2C in the cathode electrode structure. The anode electrode 4C is positioned so as to be in non-contact with the cathode electrode 2C.

[0050] By passing an electric current from a power source (not shown) through the cathode electrode 2C and the anode electrode 4C, metal ions contained in the electrolyte are deposited as metal powder on the surface of the cathode electrode 2C. According to the manufacturing apparatus of the second embodiment, the second electrode (anode electrode 4C in Figures 11 to 13) is placed in the gaps of the lattice-shaped first electrode (cathode electrode 2C in Figures 11 to 13) in the first electrode structure (cathode electrode structure in Figures 11 to 13), thereby creating a structure in which the anode electrode and the cathode electrode intersect three-dimensionally, and increasing the deposition rate of metal powder per unit volume of the electrode portion.

[0051] Figure 14, of the third embodiment, is a schematic front view showing a metal powder manufacturing apparatus according to the third embodiment. Figure 15 is a schematic top view showing the cathode electrode and anode electrode in the metal powder manufacturing apparatus according to the third embodiment.

[0052] The metal powder manufacturing apparatus shown in Figures 14 and 15 has a three-dimensional cathode electrode structure (corresponding to the first electrode structure) in which multiple rectangular cathode electrodes 302 (corresponding to the first electrode) are stacked vertically (vertically in the direction of gravity) with gaps between them within an electrolytic cell 360, and the rectangular cathode electrodes 302 are vertically connected to each other. The cathode electrode structure has air gaps between the cathode electrodes 302. The cathode electrodes 302 are fixed to insulating supports 310A and 310B.

[0053] The metal powder manufacturing apparatus according to the third embodiment has one anode electrode 304. The anode electrode 304 is rod-shaped (i.e., rod-shaped). A wire shape is also a preferred shape for the anode electrode 304. The rod-shaped anode electrode 304 extends vertically downward from support 310A to support 310B. The anode electrode 304 is fixed to the insulator supports 310A and 310B. The anode electrode 304 is positioned perpendicular to the multiple rectangular cathode electrodes 302 in a three-dimensional cathode electrode structure in which multiple electrodes are stacked vertically and connected to each other vertically (i.e., in Figures 14 and 15, the anode electrode 304 is positioned vertically, and each of the multiple cathode electrodes 302 is positioned horizontally). Although Figures 14 and 15 show an example in which the anode electrode 304 is positioned perpendicular to the multiple cathode electrodes 302, the embodiment is not limited to this. For example, the anode electrode may be positioned obliquely to the cathode electrode (i.e., the anode electrode and cathode electrode may be positioned in a non-orthogonal relationship).

[0054] As shown in Figures 14 and 15, the anode electrode 304 is positioned in the gaps between multiple rectangular cathode electrodes 302 in a three-dimensional cathode electrode structure in which multiple electrodes are stacked vertically and connected to each other vertically. The anode electrode 304 is positioned in a direction perpendicular to the multiple cathode electrodes 302. The anode electrode 304 is positioned so as to be non-contact with the cathode electrodes 302.

[0055] The cathode electrode 302 and the anode electrode 304 are connected to the same power supply (not shown). Electrolyte 312 is poured into the electrolytic cell 360. By passing current from the power supply to the cathode electrode 302 and the anode electrode 304, metal ions contained in the electrolyte 312 are deposited as metal powder on the surface of the cathode electrode 302.

[0056] Thus, by making the first electrode structure (cathode electrode structure in Figures 14 and 15) a three-dimensional structure in which multiple square-shaped first electrodes (cathode electrodes 302 in Figures 14 and 15) are stacked vertically (vertically in the direction of gravity) with gaps between them, and the square-shaped first electrodes are vertically connected to each other, when metal powder deposited on the surface of the cathode electrode is peeled off by the metal powder peeling mechanism described later, the peeled metal powder can easily pass between the electrodes. In addition, because there are many voids, fluid movement by ultrasound or agitation is likely to occur in the metal powder peeling mechanism described later. Also, gases generated on the surface of the anode electrode (for example, oxygen gas) can easily pass between the electrodes. Furthermore, if the shape of the second electrode (anode electrode 304 in Figures 14 and 15) is wire-like or rod-like, and the second electrode is placed in the gap of the first electrode which constitutes the three-dimensional structure of the first electrode, it is possible to create a structure in which the anode electrode and cathode electrode intersect three-dimensionally, thereby increasing the deposition rate of metal powder per unit volume of the electrode portion.

[0057] A shielding plate 382 is placed around the electrolytic cell 360, and the electrolytic cell 360 and the shielding plate 382 are installed inside the water tank 362. The water tank 362 is filled with water 316, and an ultrasonic generator 380 is placed so as to be submerged in the water 316 as a mechanism to detach metal powder deposited on the surface of the cathode electrode 302 from the cathode electrode 302. After metal powder is deposited on the surface of the cathode electrode 302 by the electrolytic reaction, the ultrasonic generator 380 generates ultrasonic waves, which can detach the metal powder from the surface of the cathode electrode 302.

[0058] The apparatus in the third embodiment includes a first electrode structure (e.g., a cathode electrode structure) which is three-dimensionally composed of a plurality of first electrodes (e.g., cathode electrodes) with gaps between each of the first electrodes, and a second electrode (e.g., an anode electrode) which is positioned in the gaps in the first electrode structure so as not to be in contact with the first electrodes. It also has a mechanism for removing metal powder deposited on the surface of the cathode electrode. Therefore, it is not necessary to stop the electrolytic reaction and remove the cathode electrode with the deposited metal powder from the electrolytic cell. In other words, metal powder can be continuously recovered while the electrolytic reaction continues. From this viewpoint, the rate of metal powder deposition per unit volume of the electrode can be further increased.

[0059] Figure 16, of the fourth embodiment, is a schematic front view showing the electrode unit of the metal powder manufacturing apparatus according to the fourth embodiment. Figure 17 is a cross-sectional view taken along line A-A of the electrode unit of the metal powder manufacturing apparatus according to the fourth embodiment shown in Figure 16. Figure 18 is a diagram showing a metal powder manufacturing apparatus formed by combining four of the electrode units shown in Figures 16 and 17.

[0060] The electrode unit 400 of the metal powder manufacturing apparatus shown in Figures 16 and 17 has a three-dimensional cathode electrode structure (corresponding to the first electrode structure) in which multiple grid-shaped cathode electrodes 402 (corresponding to the first electrode) are stacked horizontally (in a direction perpendicular to the vertical direction in the direction of gravity) with gaps between them, and the grid-shaped cathode electrodes 402 are connected to each other horizontally. The cathode electrode structure has voids between the multiple cathode electrodes 402. The cathode electrodes 402 are connected by conductive connecting materials 410A and 410B.

[0061] In addition, in the electrode unit 400, metal powder is deposited on the surfaces of the connecting materials 410A and 410B, similar to the cathode electrode 402. Expanded metal is used for the cathode electrode 402, and the area around the cathode electrode 402 is reinforced with a reinforcing frame 412 as shown in Figure 17.

[0062] The electrode unit 400 of the metal powder manufacturing apparatus according to the fourth embodiment has a plurality of anode electrodes 404. The anode electrodes 404 are rod-shaped (i.e., rod-shaped). A preferred shape for the anode electrodes 404 is also a wire shape. The plurality of rod-shaped anode electrodes 404 are connected by conductive connecting members 420A and 420B. The plurality of anode electrodes 404 are stacked vertically and connected horizontally from the connecting member 420A to the connecting member 420B. The plurality of anode electrodes 404 are arranged in a direction perpendicular to the plurality of grid-shaped cathode electrodes 402 (i.e., in Figures 16 and 17, the anode electrodes 404 are arranged horizontally, and each of the plurality of cathode electrodes 402 is arranged vertically). Although Figures 16 and 17 show an example in which the anode electrodes 404 are arranged in a direction perpendicular to the plurality of cathode electrodes 402, the embodiment is not limited to this. For example, the anode electrode may be positioned obliquely to the cathode electrode (i.e., the anode electrode and cathode electrode may be positioned in a non-orthogonal relationship).

[0063] For the connecting materials 420A and 420B that link the anode electrode 404, perforated metal or the like is used to allow the electrolyte to pass through easily. In the conductive connecting materials 420A and 420B, an anodic reaction occurs in the same way as in the anode electrode 404.

[0064] The connecting members 410A and 410B that connect the cathode electrode 402 and the connecting members 420A and 420B that connect the anode electrode 404 are connected by a double electrode connecting member 430 (insulator) that connects both electrodes.

[0065] The connecting members 420A and 420B that connect the anode electrode 404 are installed partially parallel to the cathode electrode 402. Thus, in the metal powder manufacturing apparatus of this disclosure, the anode electrode and the cathode electrode may be installed parallel to each other in at least a part.

[0066] As shown in Figures 16 and 17, the anode electrode 404 is positioned in the gaps between multiple grid-like cathode electrodes 402 in a vertically stacked, three-dimensional cathode electrode structure. The anode electrode 404 is positioned in a direction perpendicular to the multiple cathode electrodes 402. The anode electrode 404 is positioned so as to be non-contact with the cathode electrodes 402.

[0067] The cathode electrode 402 and the anode electrode 404 are connected to the same power supply (not shown). By passing current from the power supply to the cathode electrode 402 and the anode electrode 404, metal ions contained in the electrolyte (not shown) are deposited as metal powder on the surface of the cathode electrode 402.

[0068] Thus, by creating a three-dimensional structure in which multiple grid-like first electrodes (cathode electrode structure in Figures 16 and 17) are stacked horizontally (in a direction perpendicular to the vertical direction in the direction of gravity) with gaps between them, and the grid-like first electrodes are connected to each other, the metal powder deposited on the surface of the cathode electrode can easily pass between the electrodes when it is peeled off by the metal powder peeling mechanism described later. In addition, because there are many voids, fluid movement by ultrasound or agitation is more likely to occur in the metal powder peeling mechanism described later. Furthermore, gases generated on the surface of the anode electrode (for example, oxygen gas) can also easily pass between the electrodes. Furthermore, if the shape of the second electrode (anode electrode 404 in Figures 16 and 17) is wire-like or rod-like, and the second electrode is placed in the gap of the first electrode which constitutes the three-dimensional structure of the first electrode, it is possible to create a structure in which the anode electrode and cathode electrode intersect three-dimensionally, thereby increasing the deposition rate of metal powder per unit volume of the electrode portion.

[0069] As a mechanism for detaching metal powder deposited on the surface of the cathode electrode 402 from the cathode electrode 402, for example, an ultrasonic generator can be used. After metal powder is deposited on the surface of the cathode electrode 402 by an electrolytic reaction, the metal powder can be detached from the surface of the cathode electrode 402 by generating ultrasonic waves with an ultrasonic generator.

[0070] The apparatus shown in the fourth embodiment includes a first electrode structure (e.g., a cathode electrode structure) which is three-dimensionally composed of a plurality of first electrodes (e.g., cathode electrodes) with gaps between each of the first electrodes, and a second electrode (e.g., an anode electrode) which is positioned in the gaps in the first electrode structure so as not to be in contact with the first electrodes. It also has a mechanism for removing metal powder deposited on the surface of the cathode electrode. Therefore, it is not necessary to stop the electrolytic reaction and remove the cathode electrode with the deposited metal powder from the electrolytic cell. In other words, metal powder can be continuously recovered while the electrolytic reaction continues. From this viewpoint, the rate of metal powder deposition per unit volume of the electrode can be further increased.

[0071] As shown in Figure 18, a metal powder manufacturing apparatus may also be constructed by arranging multiple electrode units 400 together to form a unitized apparatus. By combining multiple electrode units 400, the metal powder manufacturing apparatus can be easily scaled up. In a unitized metal powder manufacturing apparatus, the anode electrodes and cathode electrodes of other electrode units 400 can be electrically connected to each other. In a metal powder manufacturing apparatus composed of multiple electrode units 400, the electrode system of each electrode unit 400 is connected to a busbar (not shown) for use.

[0072] ・Aspects of the grid-like electrode structure The first electrode structure (cathode electrode structure in Figures 9 and 10) is a structure in which multiple grid-like first electrodes (cathode electrodes 2A, 2B in Figures 9 and 10) are stacked vertically (vertically in the direction of gravity) with gaps between them, and the grid-like first electrodes are connected vertically to each other. The same aspects as described below can also be used when the second electrode (anode electrode 4C in Figures 11 to 13) is a structure in which multiple grid-like second electrodes are stacked vertically (vertically in the direction of gravity) with gaps between them, and the grid-like second electrodes are connected vertically to each other (hereinafter also referred to as the "second electrode structure").

[0073] The shape of the grid constituting the first and second electrode structures is not limited to a quadrilateral (rhombic in Figures 16 and 17) as shown in Figures 9 to 13 and 16 to 17. For example, polygons such as triangles and pentagons, or circles, can also be used. Furthermore, the orientation of the grid planes is not limited to planes perpendicular to the vertical direction, but can also be vertical or oblique to the vertical direction. This increases the structural strength of the first and second electrode structures, allowing for larger structures.

[0074] Furthermore, as the grid-like electrodes in the first and second electrode structures, wire mesh (including both welded wire mesh (see Figure 19) and unwelded wire mesh), expanded metal (see Figure 20), perforated metal, and metal mesh (see Figure 21) can be used. The grid-like electrodes can also be fabricated using a 3D printer.

[0075] Expanded metal refers to a metal sheet that has been expanded using an expansion machine, which cuts it in a staggered pattern and then shaped the cuts into a mesh-like structure such as a diamond or hexagon. Metal mesh refers to a metal product made by weaving metal wires together to form a net. Welded wire mesh refers to a wire mesh made by arranging metal wires perpendicularly and electrically resistance welding the intersections to form a grid; it is also called wire mesh. Compared to woven wire mesh, it is less prone to collapsing and has higher strength.

[0076] - Electrode arrangement The second electrode (anode electrodes 4A, 4B in Figures 9 and 10) can be placed as close as possible to the nearest first electrode (cathode electrodes 2A, 2B in Figures 9 and 10) to reduce the resistance of the electrolyte and allow a large current to flow. As the first electrode structure, which is three-dimensionally composed of multiple first electrodes and has air gaps between each first electrode, metal brushes, metal wool (see Figure 22), metal wire (see Figure 23), metal coils, and lattice-shaped metal can be used. For example, a first electrode structure made of metal wool can be configured with wire-shaped or rod-shaped second electrodes placed in the air gaps so as not to contact the first electrodes.

[0077] Furthermore, if the first electrode and the second electrode are positioned in contact with each other, a diaphragm may be installed between the first electrode and the second electrode to prevent short circuits. As the diaphragm, insulating materials such as nonwoven fabric and porous materials can be used.

[0078] Here, we will explain with reference to a diagram a configuration in which the first electrode structure includes, for example, a cathode electrode structure made of metal wool, and a void open to the outside by a diaphragm placed within the structure, with a wire-shaped anode electrode, which is the second electrode, placed in the void open to the outside.

[0079] The manufacturing apparatus 100E shown in Figure 24 has a cathode electrode structure (corresponding to the first electrode structure) three-dimensionally formed by a cathode electrode 2E (corresponding to the first electrode) within the electrolytic cell 60. The cathode electrode structure is made of metal wool and has air gaps between the layers. The cathode electrode 2E is connected to a busbar 20E.

[0080] The manufacturing apparatus 100E has a plurality of anode electrodes 4E. The anode electrodes 4E are wire-shaped. The plurality of anode electrodes 4E are connected to a busbar 40E. The wire-shaped anode electrodes 4E extend vertically downward from the busbar 40E.

[0081] The presence of a diaphragm 22E between the cathode electrode 2E and the anode electrode 4E causes the cathode electrode 2E to have an open gap to the outside. The two electrodes are positioned in this open gap so that they are not in contact with each other, and the anode electrode 4E prevents short circuits with the cathode electrode 2E. Since the electrolyte 12 can pass through the diaphragm 22E, the electrolyte 12 is present on the surfaces of the anode electrode 4E and the cathode electrode 2E.

[0082] Busbars 20E and 40E are connected to the same power supply 14E. Electrolyte 12 is poured into the electrolytic cell 60. By passing current from the power supply 14E to the cathode electrode 2E and anode electrode 4E through busbars 20E and 40E, metal ions contained in the electrolyte 12 are deposited as metal powder on the surface of the cathode electrode 2E.

[0083] - Non-lattice-shaped electrode structure: The first electrode structure may also be a non-lattice-shaped structure. In that case, the second electrode may also be a non-lattice-shaped structure.

[0084] An example of a first electrode structure that is not lattice-shaped is a structure in which multiple first electrodes (specifically, wire-shaped or rod-shaped first electrodes) extending in a straight line are arranged in parallel.

[0085] Here, we will explain, using a diagram, a configuration in which the first electrode structure has a structure in which multiple first electrodes extending in a straight line are arranged in parallel.

[0086] Figure 25 is a schematic side view showing a metal powder manufacturing apparatus having a first electrode structure in which multiple linearly extending first electrodes are arranged in parallel. Figure 26 is a schematic cross-sectional view showing the section A-A in Figure 25.

[0087] The manufacturing apparatus 100F shown in Figures 25 and 26 has a cathode electrode structure (corresponding to the first electrode structure) three-dimensionally formed by cathode electrodes 2F (corresponding to the first electrode) within the electrolytic cell 60. The cathode electrode structure is a structure in which multiple linearly extending cathode electrodes 2F (wire-shaped cathode electrodes) are arranged in parallel, with gaps between the cathode electrodes 2F. The cathode electrodes 2F are connected to the busbar 20F.

[0088] The manufacturing apparatus 100F has a plurality of anode electrodes 4F. The anode electrodes 4F are structures in which a plurality of linearly extending anode electrodes 4F (wire-shaped anode electrodes) are arranged in parallel, with gaps between the anode electrodes 4F. The anode electrodes 4F are connected to a busbar 40F. The anode electrodes 4F and the cathode electrodes 2F are arranged so as to intersect each other and not be in contact.

[0089] Busbars 20F and 40F are connected to the same power supply 14F. Electrolyte 12 is poured into the electrolytic cell 60. By passing current from the power supply 14F to the cathode electrode 2F and anode electrode 4F through busbars 20F and 40F, metal ions contained in the electrolyte 12 are deposited as metal powder on the surface of the cathode electrode 2F.

[0090] Furthermore, another configuration having a structure in which multiple linearly extending first electrodes are arranged in parallel will be explained with reference to a diagram.

[0091] Figure 27 is a schematic side view showing a metal powder manufacturing apparatus having a first electrode structure in which a plurality of linearly extending first electrodes are arranged in parallel, and a second electrode structure in which a plurality of linearly extending second electrodes are arranged in parallel in the same direction as the first electrodes. Figure 28 is a schematic cross-sectional view showing the section A-A in Figure 27. Figure 29 is a schematic side view showing an embodiment in which the electrodes shown in Figure 27 are equipped with spacers for preventing short circuits.

[0092] The manufacturing apparatus 100G shown in Figures 27 and 28 has a cathode electrode structure (corresponding to the first electrode structure) three-dimensionally composed of cathode electrodes 2G (corresponding to the first electrode) within the electrolytic cell 60. The cathode electrode structure is a structure in which multiple cathode electrodes 2G (wire-shaped cathode electrodes) extending linearly from top to bottom in Figure 27 are arranged in parallel. The cathode electrode structure has air gaps between each cathode electrode 2G. The cathode electrodes 2G are connected to the busbar 20G on the upper side in Figure 27.

[0093] The manufacturing apparatus 100G has multiple anode electrodes 4G in the electrolytic cell 60. The anode electrodes 4G are a structure in which multiple anode electrodes 4G (wire-shaped anode electrodes) are arranged in parallel, extending linearly from top to bottom in Figure 27. The anode electrodes 4G extend linearly in the same direction as the cathode electrodes 2G. The structure of the anode electrodes 4G has gaps between each anode electrode 4G. The anode electrodes 4G are connected to the busbar 40G on the upper side in Figure 27. The anode electrodes 4G and the cathode electrodes 2G are arranged alternately and non-contact, as shown in Figure 28.

[0094] Busbars 20G and 40G are connected to the same power supply 14G. Electrolyte 12 is poured into the electrolytic cell 60. By passing current from the power supply 14G to the cathode electrode 2G and anode electrode 4G through busbars 20G and 40G, metal ions contained in the electrolyte 12 are deposited as metal powder on the surface of the cathode electrode 2G.

[0095] Furthermore, in order to prevent a short circuit between the anode electrode 4G and the cathode electrode 2G, a short-circuit prevention spacer 90 may be installed on at least one (preferably both) of the anode electrode 4G and the cathode electrode 2G, as shown in Figure 29. The short-circuit prevention spacer 90 is an insulator and is made of, for example, ceramic, glass, or Teflon. By installing the short-circuit prevention spacer 90 on at least one (preferably both) of the anode electrode 4G and the cathode electrode 2G, contact between the anode electrode 4G and the cathode electrode 2G is prevented, and the occurrence of a short circuit is suppressed.

[0096] - If the metal powder generated by the insulator-coated cathode electrode becomes too large, it can cause a short circuit between the electrodes, reducing the efficiency of metal powder production. Therefore, the metal powder peeling mechanism described later is important to prevent short circuits. However, when aggregated metal powder precipitates on the surface of the cathode electrode, gases such as hydrogen generated at the cathode electrode may mix with the aggregated metal powder, causing its apparent specific gravity to become lower than that of the electrolyte. After the peeling operation, the aggregated metal powder may float to the surface of the electrolyte, accumulate, and deposit. The floating aggregated metal powder is a conductor, and if it accumulates between the two electrodes, it can cause a short circuit. To prevent this short circuit between the two electrodes caused by the floating aggregated metal powder, it is preferable that the surface of the region in contact with the electrolyte surface of at least one (preferably both) of the first electrode structure and the second electrode is coated with an insulator. Examples of insulators include resin. By coating with an insulator, it is possible to prevent a short circuit between the two electrodes caused by the floating aggregated metal powder. Here, "the region in contact with the electrolyte surface" refers to the area within a range of 50 mm above and below the liquid surface.

[0097] Furthermore, in at least one (preferably both) of the first electrode structure and the second electrode, the number of elements in the region in contact with the electrolyte surface may be reduced, and the distance between the first and second electrodes may be increased to prevent short circuits between the two electrodes caused by floating aggregated metal powder.

[0098] Because the floating aggregated metal powder has a large porosity, the gas within the aggregated metal powder can be expelled by collecting the aggregated metal powder from the surface layer of the electrolyte and then stirring the electrolyte containing the aggregated metal powder. Alternatively, the gas inside the aggregated metal powder can be expelled by crushing it.

[0099] • Metal Powder Detachment Mechanism One mechanism for detaching metal powder is one that applies vibration to the metal powder. One method involves vibrating the cathode electrode using a vibrating device. However, if the electrode itself is vibrated too much, it can cause distortion and potentially short-circuit, so a method that does not directly vibrate the electrode is preferable. Specifically, examples include ultrasonic generators, shock wave generators using underwater discharge, bubble generators, and pulsed fluid systems using agitation. There are also electrode impact systems that vibrate the electrode. These detachment mechanisms allow metal powder to be detached from the electrode surface without removing the electrode from the electrolytic cell or changing the distance between the electrodes.

[0100] Furthermore, since it is preferable that the precipitated metal is not irradiated with ultrasound, it is preferable to provide a shielding plate (for example, 82C or 82D in Figure 9) that blocks ultrasound in the part where the precipitated metal is recovered (for example, the funnel part 62A or 62B in Figure 9). The shielding plate is preferably made of a material that easily reflects ultrasound, such as metal. When the precipitated metal is irradiated with ultrasound, the boundary film formed between the precipitated metal and the electrolyte becomes thinner, making it easier for the precipitated metal to redissolve in the electrolyte. Therefore, it is preferable to install a shielding plate that blocks ultrasound to suppress the redissolution of the precipitated metal.

[0101] In the event of a short circuit caused by metal deposits between electrodes, in addition to the metal powder detachment mechanism described above, the following methods can be used to resolve the short circuit: During detachment, detachment particles with a specific gravity greater than that of the electrolyte are temporarily introduced into the gap between the anode and cathode electrodes to detach the metal powder electrodeposited on the cathode electrode surface, and the detachment particles and metal powder are discharged from the bottom of the electrolytic device. By releasing the voltage applied between the electrodes and allowing the device to stand, the metal deposits deposited on the electrode surface can be redissolved in the electrolyte, thereby resolving the short circuit. Furthermore, irradiating the metal deposits with ultrasound increases the rate of redissolution in the electrolyte, allowing the short circuit to be resolved more quickly. Additionally, temporarily switching the potentials of the anode and cathode electrodes, that is, changing the positive and negative sides of the power supply, allows the metal deposits initially deposited on the cathode electrode to be actively redissolved in the electrolyte, thereby resolving the short circuit. In this process, irradiating the metal precipitates with ultrasound increases the rate of redissolution into the electrolyte, allowing the short circuit to be resolved more quickly.

[0102] • Method for recovering metal powder: The metal powder detached from the cathode electrode has a higher true specific gravity than the electrolyte. Therefore, one method for recovering the detached metal powder is to install a collection section at the bottom of the electrode so that the settled metal powder can be collected, and then extract the settled metal powder from the collection section and recover the metal powder by solid-liquid separation operations such as centrifugal dehydration or filtration. Alternatively, the electrolyte can be directly extracted and the metal powder can be recovered by solid-liquid separation operations such as centrifugal dehydration or filtration without going through the collection section.

[0103] - Distance between electrodes The smaller the distance between the first electrode and the second electrode, the higher the current per unit volume of the electrode area can be, and the higher the deposition rate of metal powder per unit volume of the electrode area can be. For this reason, the distance of the second electrode to the nearest first electrode is preferably in the range of 1 mm to 50 mm, more preferably in the range of 1 mm to 20 mm, even more preferably in the range of 2 mm to 10 mm, and particularly preferably in the range of 2 mm to 5 mm. Note that the distance referred to here means that the distance to the nearest first electrode for all second electrodes is within the above range. The distance between the second electrode and the first electrode refers to the distance between the surfaces of the electrodes.

[0104] - At the material anode electrode, the reaction described in equation 1 below proceeds, extracting electrons from water and generating oxygen from the anode electrode surface. The anode electrode can be made of titanium (Ti), tantalum (Ta), zirconium (Zr), or niobium (Nb), nickel (Ni), stainless steel (e.g., type 316, type 316L, type 317, type 310, etc.), or metal alloy (e.g., nickel-chromium alloy). Optionally, any electrochemically active coating may be included. Typical coatings include those made from platinum, ruthenium, iridium, or other group VIII metals, group VIII metal oxides, or compounds containing group VIII metals, as well as oxides and compounds of titanium, molybdenum, and tantalum, and mixtures and combinations thereof.

[0105] At the cathode electrode, the following two reactions proceed, donating electrons to metal ions in the electrolyte, reducing the metal ions, and depositing them on the cathode electrode surface. Depending on the potential of the cathode electrode, hydrogen gas may also be generated. The cathode electrode can be formed from copper, copper alloys, stainless steel, titanium, aluminum, or any other metal or combination of metals and other materials. Anode reaction: H ２ O → 1 / 2O ２ +2H ＋ +2e － (Equation 1) Cathode reaction: Me ｎ＋ +ne － →Me (2 types)

[0106] <Method for Manufacturing Metal Powder> The method for manufacturing metal powder according to the embodiment of the present disclosure uses the metal powder manufacturing apparatus of the present disclosure described above, wherein the metal powder contains at least one of copper and zinc, and the electrolyte is an acidic electrolyte with a pH of 1.0 to 5.0, a strongly alkaline electrolyte with a pH of 13.0 to 14.5, or an ammonia-containing alkaline electrolyte with a pH of 7.0 to 12.0 containing ammonia.

[0107] The method for manufacturing metal powder according to the embodiment of this disclosure, by using the metal powder manufacturing apparatus of this disclosure, can increase the current per unit volume of the electrode and increase the deposition rate of metal powder per unit volume of the electrode.

[0108] The electrolyte is an leachate obtained by leaching at least one metal ion of copper and zinc, the target of electrodeposition, into an acidic leachate with a pH of 1.0 to 5.0, a strongly alkaline leachate with a pH of 13.0 to 14.5, or an ammonia-containing alkaline leachate with a pH of 7.0 to 12.0 containing ammonia. Examples of acidic leachates include aqueous solutions with a pH of 1.0 to 5.0 containing sulfuric acid and hydrochloric acid. Examples of strongly alkaline leachates include aqueous solutions with a pH of 13.0 to 14.5 containing sodium hydroxide and potassium hydroxide. Examples of ammonia-containing alkaline leachates include aqueous solutions with a pH of 7.0 to 12.0 containing ammonia.

[0109] Examples of electrolytes include those containing at least one of copper ions and zinc ions extracted from iron scrap. Iron scrap includes painted zinc-nickel plated steel sheets, painted zinc-plated steel sheets, and scrap containing other materials such as enamel-coated copper wire and copper cables. The surface layer of the steel sheets may be surface-treated with zinc plating or zinc-nickel plating and painted. In addition, motor cores and cables that could not be separated by pre-treatment such as magnetic separation may be mixed into the scrap. The copper and zinc contained in the scrap often exist as metals.

[0110] Examples of ammonia-containing alkaline electrolytes include electrolytes containing zinc ions extracted from steelmaking dust. Steelmaking dust includes dust generated during the refining process in furnaces (blast furnaces, converters, electric arc furnaces, etc.) used in the steelmaking process (blast furnace dust, converter dust, electric arc furnace dust, etc.). The furnace operating temperature is 1000°C or higher, and while iron does not volatilize, some is scattered from the furnace. On the other hand, elements such as zinc volatilize and are discharged as dust along with the scattered iron. Blast furnace dust discharged from blast furnaces and converter dust discharged from converters contain 1% to 5% by mass of zinc. Electric arc furnace dust discharged from electric arc furnaces contains 5% to 25% by mass of zinc. Zinc exists in various forms, including zinc oxide and zinc ferrite (ZnFe). ２ O ４ ) is the majority.

[0111] Regarding the leaching of copper and zinc, metallic zinc and zinc compounds such as zinc oxide, zinc hydroxide, zinc chloride, and zinc ferrite (ZnFe) ２ O ４ Of these, zinc ferrite does not dissolve when mixed with an ammonia-containing alkaline leachate because it does not form an ammine complex. However, metallic zinc, zinc oxide, zinc hydroxide, and zinc chloride dissolve in an ammonia-containing alkaline leachate because they form an ammine complex. Metallic copper, and copper compounds such as copper oxide, copper hydroxide, copper chloride, and copper ferrite (CuFe) ２ O ４Of these, copper ferrite does not dissolve when mixed with an ammonia-containing alkaline leaching solution because it does not form an ammine complex. However, metallic copper, copper oxide, copper hydroxide, and copper chloride dissolve in an ammonia-containing alkaline leaching solution because they form ammine complexes. On the other hand, metallic iron and iron oxide hardly form ammine complexes and therefore do not dissolve in an ammonia-containing alkaline leaching solution. For this reason, when using an ammonia-containing alkaline leaching solution, copper and zinc in iron scrap dissolve, while iron does not, so it can be used to leach copper and zinc from iron scrap. The pH range in which ammine complexes are formed is pH 7.5 to pH 14.0, but since leaching on the strongly alkaline side generates a large amount of ammonia gas, leaching is often performed at a pH of around 8.5 to pH 10. When using an acidic leaching solution, for example, a sulfuric acid leaching solution, many metallic zinc and zinc compounds dissolve, and many metallic copper and copper compounds dissolve. On the other hand, metallic iron and iron oxide also dissolve, so it is not appropriate to use an acidic leaching solution to leach copper and zinc from iron scrap. When using a strongly alkaline leachate, such as an aqueous sodium hydroxide solution, many metallic zinc and zinc compounds dissolve, but many metallic copper and copper compounds hardly dissolve. On the other hand, metallic iron and iron oxide do not dissolve, so zinc can be leached from iron scrap, but copper hardly leaches out. Therefore, using a strongly alkaline leachate is not appropriate.

[0112] Furthermore, metallic zinc and metallic copper consume oxidizing agents such as oxygen to form ammine complexes after oxidation. In other words, by continuously measuring the oxygen concentration in the leachate or gas phase within the leaching tank during the leaching process, the oxygen treatment rate can be determined, and it can be determined whether the leaching process is complete.

[0113] • Method for recovering metallic copper and metallic zinc from leachate by electrolytic extraction: The leachate obtained by leaching iron scrap or steelmaking dust with an ammonia-containing alkaline leachate can be used as the electrolyte. When an anode electrode and a cathode electrode are placed in this electrolyte and a voltage is applied between the anode electrode and the cathode electrode using a DC power supply, oxygen is generated from the anode side, and metals including at least one of copper and zinc are deposited from the cathode side, and hydrogen gas is generated depending on the voltage. Chlorine gas may be generated in the strong acid range (pH 3 or less), but in the weak acid to alkaline range, chloride ions are Cl － From ClO ４－ It changes to this, and chlorine gas is often not produced.

[0114] <Method for Processing Iron Scrap> The method for processing iron scrap according to the embodiment of this disclosure (hereinafter also simply referred to as "the method for processing iron scrap of this disclosure") comprises a leaching step of leaching at least one of copper and zinc from iron scrap into a leaching solution, and an electrodeposition step of electrodepositing at least one of the leached copper and zinc and separating at least one of copper and zinc from the leaching solution. In the electrodeposition step, the metal powder manufacturing apparatus of this disclosure described above is used, and an ammonia-containing alkaline leaching solution is used as the leaching solution, the leaching solution from which at least one of copper and zinc has leached is used as the electrolyte, and at least one of copper and zinc is electrodeposited from the electrolyte.

[0115] According to the iron scrap processing method of this disclosure, by using the metal powder manufacturing apparatus of this disclosure in which an ammonia-containing alkaline leachate is applied as the leachate in the electrodeposition step, at least one of copper and zinc can be efficiently electrodeposited and separated from the leachate (i.e., electrolyte) containing at least one of copper and zinc.

[0116] The iron scrap processing method of this disclosure may include one or more of the following steps in addition to the leaching step and the electrodeposition step: • Pre-treatment step: A pre-treatment step to obtain iron scrap to be processed from waste material (e.g., manual sorting step, shredding step, magnetic separation step) • Heat treatment step: A heat treatment step to heat-treat the iron scrap before the leaching step • Sorting step: A sorting step to sort the iron scrap before the heat treatment step • Quality improvement step: A quality improvement step to improve the quality of the iron scrap after the leaching step • Washing and drying step: A washing and drying step to wash and dry the iron scrap after the leaching step and before the quality improvement step

[0117] Specifically, as shown in Figure 30, for example, the iron scrap processing method of this disclosure includes: a pre-treatment step 10S for obtaining iron scrap to be processed (manual sorting step 10AS, shredder step 10BS, and magnetic separation step 10CS); a sorting step 12S for sorting the iron scrap; a heat treatment step 14S for heat-treating the iron scrap; a leaching step 16S for leaching at least one of copper and zinc from the iron scrap into a leachate; an electrodeposition step 18S (Cu electrodeposition step 18S, and Zn electrodeposition step 18S) for electrodepositing at least one of the leached copper and zinc and separating at least one of copper and zinc from the leaching solution; a washing and drying step 20S for washing and drying the iron scrap after leaching; and a quality improvement step 22S for improving the quality of the iron scrap after leaching. In Figure 30, 24S indicates an electric furnace.

[0118] The following describes each step in detail. Note that symbols are omitted, and each step is described in detail.

[0119] (Pre-processing step) The pre-processing step is a step to obtain iron scrap to be processed from waste material. The pre-processing step includes, for example, a manual sorting step, a shredder step, and a magnetic separation step.

[0120] The manual sorting step is a step in which non-metallic materials (e.g., electronic circuit boards, glass, rubber, plastic, etc.) are manually separated from waste materials (e.g., scrapped automobiles, etc.). In the manual sorting step, non-metallic materials are removed from the waste materials by sorting them.

[0121] The shredder step is, for example, the step of shredding the waste material after the removal of non-metallic materials. In the shredder step, the waste material is crushed by a shredder in order to obtain iron scrap that will allow the leaching step to be carried out efficiently.

[0122] The magnetic separation step is, for example, a step in which magnetic materials are separated from non-magnetic materials, and non-magnetic materials (electronic circuit boards, glass, rubber, plastics, stainless steel, etc.) are selected from the waste material. In the magnetic separation step, non-magnetic materials are removed from the waste material in order to obtain iron scrap that can be efficiently processed in the leaching step.

[0123] Through the above pre-processing steps, the iron scrap to be processed (for example, iron scrap including steel materials (high-strength steel plates, galvanized steel plates, etc.), cables, motor cores, etc.) is obtained from the waste material.

[0124] (Sorting Step) The sorting step is the step of sorting the iron scrap. In the sorting step, high-quality iron scrap that contains little to no impurities such as copper wire, copper pipes, and nichrome wire (for example, iron scrap containing steel materials such as high-strength steel plates, painted galvanized nickel steel plates, and painted galvanized steel plates) and low-quality iron scrap that contains impurities such as copper wire, copper pipes, and nichrome wire (for example, iron scrap containing cables, motor cores, etc., or iron scrap containing these materials intertwined) are identified, and the low-quality iron scrap is sorted out, and a heat treatment step and a leaching step are performed on the low-quality iron scrap. Meanwhile, the high-quality iron scrap that has been removed is supplied as raw material for the electric furnace.

[0125] Thus, the sorting step is, for example, a step in which low-quality iron scrap to be processed in the leaching step is sorted from the iron scrap. High-quality iron scrap is preferably iron scrap containing 90% by mass or more (preferably 95% by mass or more) of steel material. On the other hand, low-quality iron scrap is preferably iron scrap containing 20% ​​by mass or more (preferably 40% by mass or more) of metal waste materials other than steel material (such as the copper wire, copper pipes, and nichrome wire mentioned above).

[0126] Specifically, in the sorting step, for example, high-quality and low-quality iron scrap are identified by image processing of the iron scrap. Then, the identified low-quality iron scrap is sorted out from the iron scrap. Sorting methods include, for example, using high-speed air sprayed from an air nozzle to blow away the low-quality iron scrap, or using a method that magnetically separates only the low-quality iron scrap.

[0127] Here, for image processing, we will use, for example, the following techniques. However, in the following techniques, the object of image processing will be replaced with high-quality iron scrap and low-quality iron scrap. - Japanese Patent Publication No. 07-280747: "1) A conveying means for continuously conveying a group of crushed iron scraps; 2) An imaging means for capturing a color image of the group of iron scraps being conveyed; 3) An identification processing means for receiving the color image and the time of imaging from the imaging means, recognizing each individual scrap in the image from the brightness (I) signal of the color image and determining the total area St, i.e., the total number of pixels, of each scrap; determining whether each pixel is copper from the hue angle (H) signal and saturation (S) signal of the color image and determining the copper area, i.e., the number of pixels determined to be copper, of each scrap and determining whether it is copper-containing scrap from the ratio R = SCu / St of the copper area SCu of each scrap to the total area St; outputting the position (X, Y) information of all copper-containing scraps in the image and the time of imaging of the image; 4) A separation means connected to the conveying means and having a mechanism for separating copper-containing scrap and iron scrap; 5) An identification processing means for receiving the color image and the time of imaging from the identification processing means A copper-containing scrap identification and separation apparatus characterized by comprising: receiving position (X, Y) information and image acquisition time of copper-containing scrap in an image; calculating the time delay for the transport of individual copper-containing scrap to the separation means from the position (X, Y) information and image acquisition time, and a separation apparatus control means for driving the separation means when the copper-containing scrap reaches the separation means; an image processing technology utilizing the above, described in Japanese Patent Application Publication No. 2022-91278, which comprises: a transport unit that transports a group of objects to be identified, including metal scrap containing an aluminum alloy and a specific substance different from the metal scrap; an imaging unit that acquires an image of the group of objects to be identified while they are being transported; a discrimination unit that identifies the specific substance from the group of objects to be identified while they are being transported, using the image and a discrimination model using information on the color and shape of the specific substance; and a projection unit that projects a preset projection image onto the identified specific substance.

[0128] In the sorting step, the sorted low-quality iron scrap (e.g., iron scrap including cables, motor cores, etc.) further contains one or more of the following in addition to copper and zinc: for example, chromium, nickel, tin, and molybdenum.

[0129] (Heat Treatment Step) The heat treatment step is a step in which iron scrap (low-quality iron scrap after the sorting step described above) is heat-treated. In the heat treatment step, organic matter contained in the iron scrap, such as cable insulation, motor core insulation, and paint on the surface of steel plates, is carbonized. This allows the "iron scrap containing at least one of copper and zinc" in the iron scrap to come into efficient contact with the leachate, improving the leaching efficiency. In the heat treatment step, it is preferable to heat-treat the iron scrap while rolling it in order to efficiently remove the carbonized organic matter from the iron scrap. Examples of equipment for heat-treating iron scrap while rolling include a stoker furnace (rotary bed furnace) and a rotary kiln. However, in the heat treatment step, the iron scrap may be rolled using a wire mesh drum or the like after the heat treatment.

[0130] In the heat treatment step, the heating temperature of the iron scrap is preferably 350°C to 800°C, and more preferably 400°C to 600°C. When the heating temperature is within the above range, the organic matter can be efficiently carbonized while suppressing oxidation (i.e., rust) of the iron scrap.

[0131] (Leaching Step) The leaching step is a step of leaching at least one of copper and zinc from iron scrap into a leaching solution. In the leaching step, for example, a wire mesh drum containing iron scrap is immersed in the leaching solution, and the wire mesh drum is rotated, causing the iron scrap to roll while at least one of copper and zinc is leached from the iron scrap into the leaching solution. This yields a leaching solution containing at least one of the leached copper and zinc. Here, as the leaching solution, an ammonia-containing alkaline electrolyte (preferably an ammonia-containing alkaline leaching solution with a pH of 7.0 to 12.0 containing ammonia) as described in the metal powder manufacturing apparatus of the present disclosure is used.

[0132] (Electrodeposition Step) The electrodeposition step is a step of electrodepositing at least one of the leached copper and zinc and separating at least one of the copper and zinc from the leachate. The electrodeposition step uses the metal powder manufacturing apparatus of the present disclosure. In other words, the method for manufacturing metal powder using the metal powder manufacturing apparatus of the present disclosure is used. In the electrodeposition step, as the leachate, an ammonia-containing alkaline leachate (preferably an ammonia-containing alkaline leachate with a pH of 7.0 to 12.0) from which at least one of copper and zinc has leached from iron scrap is placed in the electrolytic cell of the metal powder manufacturing apparatus of the present disclosure. Then, at least one of copper and zinc is electrodeposited from the leachate using the metal powder manufacturing apparatus of the present disclosure, and a metal powder containing at least one of copper and zinc is deposited.

[0133] In the electrodeposition step, for example, the electrodeposition step may be a multi-stage electrodeposition step, and the voltage applied to the first electrode and the second electrode in the metal powder manufacturing apparatus of the present disclosure installed in each electrodeposition step may be controlled to different voltages. For example, if the leaching solution contains copper and zinc, a metal powder manufacturing apparatus for Cu electrodeposition and a metal powder manufacturing apparatus for Zn electrodeposition may be installed in series, and the Cu electrodeposition step may be performed by the metal powder manufacturing apparatus for Cu electrodeposition and the Zn electrodeposition step by the metal powder manufacturing apparatus for Zn electrodeposition. In this case, the voltage applied to the first electrode and the second electrode in the metal powder manufacturing apparatus is controlled to different voltages for Cu electrodeposition and Zn electrodeposition so that the target metal is deposited. Specifically, by controlling the voltage applied to the first electrode and the second electrode in the preceding Cu electrodeposition step to a low level, a copper-based metal can be electrodeposited, and the copper ion concentration decreases while the zinc ion concentration in the electrolyte hardly changes. By introducing the electrolyte from the preceding Cu electrodeposition step into the subsequent Zn electrodeposition step, and increasing the voltage applied to the first and second electrodes in the subsequent Zn electrodeposition step, a zinc-based metal can be electrodeposited.

[0134] In the electrodeposition step, the Cu electrodeposition step itself may be a multi-stage Cu electrodeposition step, and the Zn electrodeposition step itself may be a multi-stage Zn electrodeposition step.

[0135] In the electrodeposition step, the metal powder containing at least one of copper and zinc that has been electrodeposited is detached from the cathode electrode and recovered by the "mechanism for detaching metal powder from the cathode electrode" of the metal powder manufacturing apparatus of the present disclosure. Specifically, for example, in the Cu electrodeposition step, Cu-containing metal powder is recovered, and in the Zn electrodeposition step, Zn-containing metal powder is recovered. On the other hand, the post-deposition solution is reused as a leachate in the leaching step.

[0136] (Washing and Drying Step) The washing and drying step is a step in which the iron scrap after leaching is washed and dried. In the washing and drying step, for example, the iron scrap is placed in a wire mesh drum for liquid removal, and the wire mesh drum for liquid removal is rotated to roll the iron scrap, thereby removing the leaching liquid. Next, for example, the iron scrap is placed in a wire mesh drum for washing, and while washing water is applied, the wire mesh drum for washing is rotated to roll the iron scrap, thereby washing the iron scrap. Next, for example, the washed iron scrap is dried in a yard.

[0137] (Quality Improvement Step) The quality improvement step is a step to improve the quality of iron scrap after leaching. In the quality improvement step, for example, high-quality iron scrap with a trump element content (total amount of copper, chromium, tin, nickel, and molybdenum) at a target value (e.g., 0.3 mass% or less) is selected from the iron scrap. Then, the high-quality iron scrap is reused as raw material for electric furnaces.

[0138] Specifically, in the quality improvement step, for example, elemental analysis of iron scrap is performed using LIBS (Laser-Induced Breakdown Spectroscopy) to identify high-quality iron scrap from other iron scrap and separate them. Next, for example, elemental analysis of the other iron scrap is performed using XRF (X-ray Fluorescence Analysis) to identify trump element residues with trump element content (total amount of copper, chromium, tin, nickel, and molybdenum) exceeding the target value (e.g., 0.3 mass%) from stainless steel and separate them. The trump element residues are then reprocessed in the leaching step.

[0139] As described above, the iron scrap processing method of this disclosure efficiently yields high-quality iron scrap with a trump element content (total amount of copper, chromium, tin, nickel, and molybdenum) at a target value (e.g., 0.3 mass% or less).

[0140] <Method for recovering metallic zinc from dust> The method for recovering metallic zinc from dust according to the embodiment of this disclosure (hereinafter also simply referred to as "the metallic zinc recovery method of this disclosure") is a method for recovering metallic zinc from dust, in which at least the zinc component is leached from dust containing zinc oxide using a leachate, and metallic zinc is deposited from the obtained leachate containing zinc ions by electrolytic extraction. The leachate is an acidic leachate with a pH of 1.0 to 5.0, a strongly alkaline leachate with a pH of 13.0 to 14.5, or an ammonia-containing alkaline leachate with a pH of 7.0 to 12.0 containing ammonia. The metal powder manufacturing apparatus of this disclosure described above is used as the apparatus for electrolytic extraction, the leachate from which metallic zinc has been leached is used as the electrolyte, and at least metallic zinc is electrodeposited from the electrolyte.

[0141] The metal powder recovery method of this disclosure can efficiently recover metallic zinc from dust by applying the metal powder manufacturing apparatus of this disclosure described above as the apparatus used for electrolytic extraction.

[0142] The method for recovering metallic zinc according to this disclosure may include a method of separating dust into magnetic and non-magnetic materials by magnetic separation, a method of further adding metallic zinc to a leachate containing zinc ions, or a method of melting metallic zinc.

[0143] (Dust) In the method for recovering metallic zinc according to the present disclosure, the dust containing zinc oxide is electric furnace dust generated from an arc discharge type electric furnace for steel manufacturing, and (H) in the exhaust gas at the outlet of the electric furnace during arc discharge. ２ +CO) / (H ２ O+CO ２ ) is 2.0 × 10 in molar ratio －２ It is preferable that the electric furnace dust is obtained by operating in such a manner as described above.

[0144] ((Forms and Formation Process of Zinc in Dust)) Zinc in electric furnace dust mainly exists as zinc oxide and zinc ferrite. This section explains the behavior of zinc, which is included in the raw materials fed into the electric furnace and becomes an impurity in the steel produced, and the formation process of zinc oxide and zinc ferrite. In scrap containing zinc fed into the electric furnace, when the scrap is melted, the metallic zinc in the galvanized part of the scrap surface volatilizes. The volatilized zinc vapor oxidizes in the exhaust gas to become zinc oxide (boiling point 1975°C) and precipitates in the gas phase. Some of the scrap oxidizes in the electric furnace to become iron oxide with a hematite phase and peels off from the scrap. It is thought that zinc ferrite is formed on the particle surface by the interdiffusion of cations when the hematite phase of zinc oxide particles and iron oxide particles come into contact in the exhaust gas.

[0145] ((Forms of zinc and copper that can be leached)) Zinc oxide in electric furnace dust can be dissolved in a leaching solution below 40°C consisting of an ammonia-containing alkaline leaching solution, an acidic solution, or a strongly alkaline solution (pH 14.5 or less). Metallic zinc can then be obtained by electrolytic leaching using this leaching solution as an electrolyte. On the other hand, zinc ferrite is hardly soluble in any leaching solution below 40°C. Therefore, by understanding the process of zinc ferrite formation in electric furnace dust, and by recovering the dust with a high ratio of zinc oxide using a method that prevents zinc ferrite formation or suppresses zinc ferrite formation, the zinc oxide in the dust can be leached out using a leaching solution, and metallic zinc can be efficiently recovered by electrolytic refining of the zinc-containing leaching solution.

[0146] Furthermore, the copper component contained in the raw material scrap hardly volatilizes in the electric furnace and is therefore hardly present in the electric furnace dust. However, some of the raw material may scatter and be present in trace amounts in the dust. When copper exists in the dust as copper oxide or metallic copper, it dissolves in ammonia-containing alkaline leaching solutions or some acidic solutions, but hardly dissolves in strongly alkaline leaching solutions (pH 14.5 or lower).

[0147] (Suppression of zinc ferrite formation and increase of zinc oxide ratio by controlling exhaust gas components at the electric furnace outlet) Zinc oxide and hematite phase in electric furnace dust come into contact, forming zinc ferrite. If the formation of zinc ferrite can be suppressed, the proportion of zinc oxide that can easily leach into the leachate will increase. The conditions for suppressing the formation of zinc ferrite will be explained below.

[0148] Although the temperature inside the electric furnace fluctuates greatly, the exhaust gas temperature at the outlet of the electric furnace where arc discharge is performed is approximately 900 to 1300°C, and the zinc concentration in the electric furnace dust is 15 to 30% by mass, and iron is Fe ２ O ３ It contains approximately 40-60% by mass. Higher electric furnace outlet temperatures facilitate the formation of zinc ferrite.

[0149] Therefore, in addition to the plastics mixed in with the scrap and other raw materials fed into the electric furnace, reducing gas (H ２ CO, CH ４ By blowing substances that generate reducing gas (such as plastics or other carbon-containing organic materials) into the electric furnace, the molar ratio (H) of the exhaust gas at the outlet of the electric furnace during arc discharge is reduced. ２ +CO) / (H ２ O+CO ２ ) is 2.0 x 10 －２ It was found that by operating in the manner described above, the conditions inside the electric furnace could be made slightly reducing, thereby suppressing the formation of zinc ferrite.

[0150] ((Electric Arc Furnace Exhaust Gas Treatment Process)) Figure 31 schematically shows an example of the configuration of an arc discharge type electric arc furnace (arc furnace) and a dust collection system for recovering electric arc furnace dust. In Figure 31, 10T is the electric arc furnace, 12T is the furnace lid, 14T is the electrode, 16T is the molten steel, 18T is the electric arc furnace outlet (gas analysis measurement area), 20T is the combustion chamber, 22T is the cooling chamber, 24T is the dust collector, 26T is the fan, and 28T is the exhaust duct. In addition, a blowing device is provided for blowing a substance that generates reducing gas into the electric arc furnace 10T. The blowing device consists of a storage silo 2T, a blower 4T, piping 6T, and a blowing port 8T. The exhaust gas from the outlet 18T of the electric arc furnace 10T is introduced into the combustion chamber 20T, where it undergoes complete combustion and heat rise, is rapidly cooled with a water spray in the cooling chamber 22T, and then the dust is removed by the dust collector 24T. This dust is electric furnace dust DT.

[0151] In such a device configuration, which includes an electric furnace 10T and a dust collection system 24T, the molar ratio (H) of the exhaust gas at the electric furnace outlet 18T during arc discharge is ２ +CO) / (H ２ O+CO ２ ) is 2.0 x 10 －２ By operating the electric furnace to achieve a concentration of (mol / mol) or higher, the formation of zinc ferrite is suppressed, increasing the zinc oxide content in the electric furnace dust, which can be stably maintained at 40% or higher. Preferably, when arc discharge is performed in the electric furnace, reducing gas (H ２ CO, CH ４ The amount of substances that generate reducing gases (such as plastics or other organic compounds) fed into the electric furnace (supply amount) is adjusted by feedback control. Furthermore, the molar ratio (H) of the exhaust gas at the electric furnace outlet 18T is adjusted. ２ +CO) / (H ２ O+CO ２ ) is 5.0 x 10 －２It is more preferable to operate the electric furnace so that the concentration is (mol / mol) or higher. In electric furnace operation, the scrap material is fed into the electric furnace 10T from the top by opening the furnace lid 12T. Therefore, any plastics mixed in the scrap enter the furnace along with the raw materials. On the other hand, a substance (such as plastic) that generates reducing gas to control the exhaust gas components at the electric furnace outlet 18T is fed in from the inlet 8T using a blowing device. The blowing device shown in Figure 31 is configured for powder blowing, but it is not limited to this configuration, and a configuration that supplies reducing gas or a solid other than powder that generates reducing gas into the electric furnace 10T is also possible.

[0152] When the zinc oxide content in electric furnace dust exceeds 40%, the zinc leaching rate from the electric furnace dust, as described later, also exceeds 40%, resulting in less than 60% of the zinc being returned to the blast furnace or rotary hearth reduction furnace in the steelmaking process, thus reducing the zinc load. A lower zinc load makes it less likely for operational problems in the blast furnace or quality problems such as a decrease in the dezincification rate in the rotary hearth to occur. For this reason, it is preferable to have a zinc oxide content of 40% or more in electric furnace dust, and even more preferable to have a content of 60% or more.

[0153] Furthermore, (H ２ +CO) / (H ２ O+CO ２ Increasing the ) can increase the zinc oxide content, but to do so, reducing gas (H) ２ CO, CH ４ It is necessary to increase the amount of (H) injected into the electric furnace that generates reducing gas (such as plastics or other carbon-containing organic materials), which increases costs. ２ +CO) / (H ２ O+CO ２ The upper limit of ) is preferably 0.3 (mol / mol).

[0154] ((Method for measuring exhaust gas components)) The exhaust gas temperature at the electric furnace outlet 18T can be measured using a thermocouple. ２ , H ２ O, CO, CO ２This can be measured, for example, using the method shown in Table 1 below. One or more sensors are used to continuously measure the exhaust gas components at the electric furnace outlet 18T.

[0155]

[0156] The exhaust gas temperature at the electric furnace outlet 18T was measured using a thermocouple, and the CO in the exhaust gas was measured. ２ CO, H ２ , H ２ The oxygen concentration can be measured by mass spectrometry. This disclosure is not limited to the electric furnace configuration shown in Figure 31, but is applicable to any electric furnace that uses an arc discharge method, can collect exhaust gas at the outlet, and can recover electric furnace dust.

[0157] ((Method for Measuring Zinc Oxide Content)) The method for measuring the zinc oxide content in electric furnace dust is described below. At room temperature (temperatures in the range of 23±2℃), zinc oxide dissolves in ammonia-containing aqueous solutions, but zinc ferrite and iron, which have a spinel structure, do not dissolve. Specifically, the recovered electric furnace dust containing 4g of zinc is placed in a sealed container with 1L of ammonium sulfate aqueous solution (185g / L) adjusted to pH 9.5-11.5 with sodium hydroxide aqueous solution. The container is then shaken at room temperature for 24 hours at a rate of 100 times / min and an amplitude of 200mm to leach the zinc into the leachate. The zinc and iron content in the electric furnace dust are measured before and after leaching, and the zinc oxide content in the electric furnace dust is calculated using the following formula (A). According to the electric furnace operation method described above, it is possible to make the zinc oxide content in the electric furnace dust calculated from the following formula (A) 40% by mass or more.

[0158] Zinc oxide rate (mass %) = {(Zn content before leaching (mass %) / Fe content before leaching (mass %)) - (Zn content after leaching (mass %) / Fe content after leaching (mass %))} ÷ (Zn content before leaching (mass %) / Fe content before leaching (mass %)) × 100 Formula (A)

[0159] The Zn and Fe content in the dust before or after leaching is measured as follows: The material is dissolved in hydrochloric acid and then separated into leachate and residue. The residue is decomposed by alkaline fusion and then dissolved in hydrochloric acid. The leachate and acid solution are mixed, and the Zn and Fe concentrations are measured by ICP-AES (inductively coupled plasma emission spectrometry). The Zn and Fe content are calculated from the volume of the liquid, and the Zn and Fe content is determined from the volume of the material.

[0160] Zinc forms a zinc ammine complex (Zn(NH)) in an aqueous ammonium sulfate solution. ３ ) ４ SO ４ ) forms and dissolves. NH in zinc ammine complex ３ / Zn = 4 (mol / mol), but to dissolve all of the zinc oxide in the dust, more free ammonia (f-NH) is needed. ３ ) is necessary. f-NH ３ If the Zn content is 25 (mol / mol) or higher, the entire amount of zinc oxide in the dust can be dissolved. Therefore, T-NH in 185 g of ammonium sulfate ３ The amount is 2.80 mol, and the zinc content of 4 g is 0.061 mol. At pH 9.5, the ratio of free ammonia to total ammonia (f-NH) ３ / T-NH ３ ) is 0.55, f-NH ３ / Zn = (2.80 * 0.55) / (0.061) = 1.54 mol-f-NH ３ / 0.061 mol - Zn = 25.2 (mol / mol) > 25 (mol / mol). Note that f-NH at pH 11.5 ３ / T-NH ３ Since it becomes 0.98, f-NH ３ The Zn concentration is 45.0 (mol / mol), which is 25 (mol / mol) or more. The reason for setting the zinc content at 4g is that the zinc content in dust is usually about 20%, and in this case the amount of dust is 20g, which is easy to disperse in 1L of ammonium sulfate aqueous solution. If the zinc content is low and the amount of dust becomes too large, the zinc content may be reduced to less than 4g.

[0161] The formation region of the zinc ammine complex is pH 7 to 11.5. When the pH is less than 9.5, f-NH ３ / T-NH ３ becomes smaller, and it becomes difficult to make f-NH ３ / Zn 25 (mol / mol) or more. When the pH exceeds 11.5, zinc oxide becomes difficult to dissolve. Therefore, pH 9.5 to 11.5 is preferable.

[0162] ((Method for recovering metallic zinc from electric furnace dust)) In the method for recovering metallic zinc of the present disclosure, the zinc oxide rate in the electric furnace dust is increased by controlling the exhaust gas components at the above-described electric furnace outlet, zinc is leached from the recovered dust, and metallic zinc is recovered by electrolytic extraction from the leachate containing zinc ions, whereby metallic zinc can be recovered from the electric furnace dust with a high yield.

[0163] (Leaching for non-magnetic separation products) In the method for recovering metallic zinc of the present disclosure, it is preferable to apply a method of magnetic separation of dust containing zinc oxide into magnetic adherents and non-magnetic adherents. When this method is applied, the concentration of zinc oxide in the non-magnetic adherents after magnetic separation is utilized. Specifically, after the dust is slurried, it is separated into magnetic adherents and non-magnetic adherents by magnetic separation, and the non-magnetic adherents after separation are immersed in a leachate to leach zinc, and metallic zinc is precipitated by electrolytic extraction from the obtained leachate containing zinc ions, and metallic zinc is recovered. By performing the leaching operation on the non-magnetic adherents after magnetic separation in this way, the amount of the object of the leaching operation can be reduced, so that the leaching apparatus can be made smaller.

[0164] (Improving the purity of the recovered metallic zinc by adding metallic zinc to the leachate) In the method for recovering metallic zinc of the present disclosure, metallic zinc may be further added to the leachate containing zinc ions, an element having a lower ionization tendency than zinc is precipitated from the leachate containing zinc ions, and metallic zinc is precipitated by electrolytic extraction from the intermediate leachate containing zinc ions after separating the precipitate, and metallic zinc is recovered. By adding granular metallic zinc, among the metal ions eluted in the leachate, an element (such as copper ions) having a smaller ionization tendency than zinc (in the case of copper ions, Cu ２＋ +Zn ⇒ Cu+Zn ２＋The intermediate leachate is obtained by separating the precipitate through filtration or other means. The purity of the recovered metallic zinc is improved by electrolytic refining of the intermediate leachate in a subsequent step.

[0165] (Compact electrolysis by high-speed electrodeposition) In the method for recovering metallic zinc according to the present disclosure, if an electrolytic method is adopted in which the metallic zinc deposition rate per unit volume of the electrode is large, metallic zinc can be recovered efficiently. For this reason, in the method for recovering metallic zinc according to the present disclosure, the metal powder manufacturing apparatus described above is used as the apparatus for electrolytic extraction. Here, Figure 32 schematically shows an example of the configuration of a metallic zinc recovery apparatus for implementing the method for recovering metallic zinc from dust according to the present disclosure. The metallic zinc recovery apparatus shown in Figure 32 comprises a first stirring device 30T, a second stirring device 40T, and an electrolytic device 50T. The electrolytic device 50T corresponds to an example of the metal powder manufacturing apparatus described above.

[0166] The details of each step in the metallic zinc recovery method of this disclosure, using the metallic zinc recovery apparatus shown in Figure 32, will be described below.

[0167] (Leaching Process) In the leaching process, for example, electric furnace dust recovered by increasing the zinc oxide content in the electric furnace dust through the control of exhaust gas components at the electric furnace outlet as described above is added to the first stirring device 30T containing the leaching liquid 32T and stirred to leach zinc into the leaching liquid. Alternatively, the dust may be magnetically separated and the non-magnetic material after separation may be added to the first stirring device 30T.

[0168] As the leachate 32T, a leachate capable of dissolving zinc oxide contained in the dust is applied. Specifically, as the leachate 32T, an acidic leachate with a pH of 1.0 to 5.0, a strongly alkaline leachate with a pH of 13.0 to 14.5, or an ammonia-containing alkaline leachate with a pH of 7.0 to 12.0 containing ammonia is applied.

[0169] (Impurity Removal Process) After the leaching process, the residue (mainly iron oxide) is removed, and the leached solution 42T containing zinc ions is put into the second stirring device 40T, and metallic zinc powder (Zn powder) is added. By adding granular (powdered) metallic zinc to the leached solution 42T containing zinc ions, impurities contained in the leached solution 42T, i.e., elements with a lower ionization tendency than zinc (such as copper ions), are precipitated on the surface of the metallic zinc powder. By separating the precipitates through filtration or other means, an intermediate leached solution 44T with reduced impurities is obtained.

[0170] (Electrolytic Extraction Process) In the electrolytic extraction process, the metal powder manufacturing apparatus described above is used as the apparatus for electrolytic extraction. Specifically, for example, the electrolytic apparatus 50T shown in Figure 32 is used. With such a configuration, metallic zinc can be recovered by compact electrolysis using high-speed electrodeposition.

[0171] In the electrolytic apparatus 50T shown in Figure 32, 52T is the power supply, 54T is the cathode, 56T is the anode, 60T is the ultrasonic generator, and 62T is the ultrasonic shielding plate. Figure 33 is a schematic cross-sectional view showing the A-A section in Figure 32. Figure 34 is a schematic side view showing an configuration in which each electrode shown in Figure 32 is equipped with a spacer 57T for preventing short circuits. The intermediate leachate 44T after the impurity removal process is put into the electrolytic cell 58T of the electrolytic apparatus 50T as the electrolyte, and electrolytic refining is performed.

[0172] The electrolytic device 50T has a cathode electrode structure (corresponding to an example of a first electrode structure) three-dimensionally composed of cathode electrodes 54T (corresponding to an example of a first electrode) within the electrolytic cell 58T. The cathode electrode structure is a structure in which multiple cathode electrodes 54T (wire-shaped cathode electrodes) extending linearly from top to bottom are arranged in parallel. The cathode electrode structure has air gaps between each cathode electrode 54T. The cathode electrodes 54T are connected to a busbar 53T on the upper side.

[0173] The electrolytic device 50T has multiple anode electrodes 56T (corresponding to an example of a second electrode) in the electrolytic cell 58T. The anode electrode 56T is a structure in which multiple anode electrodes 56T (wire-shaped anode electrodes) extending linearly from top to bottom are arranged in parallel. The anode electrodes 56T extend linearly in the same direction as the cathode electrode 54T. The structure of the anode electrode 56T has air gaps between each anode electrode 56T. The anode electrodes 56T are connected to the busbar 55T on the upper side. The anode electrodes 56T and cathode electrodes 54T are arranged alternately and non-contactively, as shown in Figure 33.

[0174] Busbars 53T and 55T are connected to the same power supply 52. ​​Electrolyte 64T, which serves as leachate, is poured into the electrolytic cell 58. By passing current from the power supply 52T to the cathode electrode 54T and anode electrode 56T through busbars 53T and 55T, zinc ions contained in the electrolyte 64T are deposited as metallic zinc powder on the surface of the cathode electrode 54T.

[0175] Furthermore, in order to prevent a short circuit between the anode electrode 56T and the cathode electrode 54T, a short-circuit prevention spacer 57T may be installed on at least one (preferably both) of the anode electrode 56T and the cathode electrode 54T, as shown in Figure 34. The short-circuit prevention spacer 57T is an insulator and is made of, for example, ceramic, glass, or fluororesin. By installing the short-circuit prevention spacer 57T on at least one (preferably both) of the anode electrode 56T and the cathode electrode 54T, contact between the anode electrode 56T and the cathode electrode 54T is prevented, and the occurrence of a short circuit is suppressed.

[0176] (Improving the purity of recovered metallic zinc by recovering molten zinc) After removing the leachate adhering to the metallic zinc precipitated and recovered by electrolytic extraction, the metallic zinc may be melted and the molten metallic zinc recovered may be recovered. Since trace amounts of leachate are mixed in the electrodeposited material recovered by electrolytic refining, the concentration of metallic zinc in the electrodeposited material after electrolytic refining is about 99.3 to 99.7%. Ions such as Ca, Al, and Si are dissolved in the leachate. Therefore, in order to separate these elements, the electrodeposited material is melted and the floating dross is separated, thereby improving the purity of zinc to 99.9% or higher.

[0177] The present disclosure will be described in more detail below with reference to examples, but the present disclosure is not limited to these examples.

[0178] [Example 1] Thin sheet iron scrap containing enamel-coated copper wire and painted galvanized steel sheets was placed in an open electric furnace and heated at 500°C for 30 minutes to remove the enamel coating and painted parts. 500g of the heated iron scrap was treated with an alkaline leaching solution (50g-NH₄). ３ The iron scrap was leached for 5 hours in a sealed container containing 1 L of (controlled to 10 mg / L, pH 9.1, and DO (dissolved oxygen concentration) 10 mg / L). After leaching, the iron scrap residue was removed by magnetic attraction. The remaining leachate in the sealed container was filtered to remove solid matter, and the post-leaching solution (electrolyte) was obtained.

[0179] Next, the metal was recovered from the electrolyte using the electrolytic emission test apparatus shown in Figures 14 and 15. Figure 14 is a schematic front view showing the electrolytic emission test apparatus used in Example 1 and Example 2, and Figure 15 is a schematic top view showing the cathode electrode and anode electrode in the electrolytic emission test apparatus shown in Figure 14. The anode electrode 304 (iridium oxide calcined electrode, base material: titanium) and the cathode electrode 302 (SUS304) (shortest distance between electrodes: 10 mm) were connected by insulating supports 310A and 310B (both made of rubber), and the areas near the liquid surface of both electrodes and the lower part of the cathode electrode 302 were insulated with insulating materials 314A and 314B (both made of paint). The length of one side of the cathode electrode 302 (see Figure 15) is 27 mm. Furthermore, the depth of the region of the cathode electrode 302 that is immersed in the electrolyte 312 but is not insulated by the insulating materials 314A and 314B (both paints) is 37 mm. The anode electrode 304 and cathode electrode 302, which are connected by supports 310A and 310B and covered with insulating materials 314A and 314B, were placed in an electrolytic cell 360 (tall beaker). In addition, the lower part of the electrolytic cell 360 was placed inside a shielding plate 382 (specifically a shielding container) for ultrasonic shielding. Furthermore, the electrolytic cell 360 and the shielding plate 382 were placed inside a water tank 362, the water tank 362 was filled with water 316, and an ultrasonic generator 380 was placed so as to be submerged in the water 316. The iridium oxide calcined electrode was used because it has the effect of reducing oxygen overpotential at the anode electrode.

[0180] 110 ml of the leached solution (electrolyte 312) was placed in the electrolytic cell 360, and a power cable (not shown) was connected to the anode electrode 304 and the cathode electrode 302. Electrolysis was performed for 30 minutes. The power supply voltage was 3.5 V. The current was initially 0.75 A and gradually increased to 1.2 A. This was because metal was deposited on the surface of the cathode electrode 302, reducing the effective distance between the electrodes. The current per unit volume of the electrode section was 33 kA / m³. ３ The calculations showed that the metal components of the electrolyte 312 changed as shown in Table 1, with a decrease in the metal concentrations of copper and zinc. From this, it can be said that 0.48 g of copper and zinc were electrodeposited onto the surface of the cathode electrode 302. The current efficiency was approximately 91%.

[0181] Next, after disconnecting the power cable, ultrasonic waves were generated for 15 seconds from the ultrasonic generator 380 installed on the outside of the electrolytic cell 360. After ultrasonic irradiation, the electrodes were washed with pure water and then dried. The mass of the electrodes was measured. Based on the increase from the initial mass of the electrodes, the residual electrodeposition was 0.02 g. From this, it can be considered that approximately 96% of the electrodeposition had detached from the cathode electrode 302. The electrodeposition accumulated at the bottom of the electrolytic cell 360 was filtered through filter paper 5A, and the electrodeposition was recovered and analyzed for its components, which showed that it consisted of 64.1% copper and 35.0% zinc. The deposition rate of metal powder per unit volume of the electrode was 33.2 kg / m³. ３ The deposition rate of metal powder per unit volume of the electrode part using conventional electrode plates was (7-13 kg / m³). ３ It can be said that this is sufficiently large compared to ( / h). In Example 1, the shortest distance between electrodes is 10 mm, but by making the shortest distance between electrodes smaller, the current per unit volume of the electrode part increases, and the deposition rate of metal powder per unit volume of the electrode part also increases.

[0182]

[0183] [Example 2] 150 g of electric furnace dust (Zn content: 25.3% by mass) was stirred in 1 L of ammonia-containing leachate (ammonium sulfate: 206 g / L, pH 8.7) for 1 day to leach, and then filtered through filter paper 5A to obtain the leachate. Next, the metal was recovered from the electrolyte using the electrolytic emission test apparatus shown in Figures 14 and 15. The configuration of the electrolytic emission test apparatus was the same as that described in Example 1.

[0184] 110 ml of leached solution (electrolyte 312) was placed in the electrolytic cell 360, and a power cable (not shown) was connected to the anode electrode 304 and cathode electrode 302. Electrolysis was performed for 60 minutes. The power supply voltage was 3.5 V. The current ranged from 0.5 A to 0.52 A. The current per unit volume of the electrode section was 19 kA / m³. ３ The calculations showed that the metal components of the electrolyte 312 changed as shown in Table 2, with a decrease in the zinc metal concentration. From this, it can be said that 0.53 g of zinc was electrodeposited onto the surface of the cathode electrode 302. The current efficiency was approximately 86%.

[0185] Next, after removing the power cable, ultrasonic waves were generated for 15 seconds from the ultrasonic generator 380 installed outside the electrolytic cell 360. After ultrasonic irradiation, the electrodes were washed with pure water and then dried, and the mass of the dried electrodes was measured. From the increase in mass from the initial mass of the electrodes, the remaining electrodeposit was 0.2 g. From this, it can be considered that about 48% of the electrodeposit was peeled off from the cathode electrode 302. The electrodeposit contained dendritic deposits and film-like deposits. The dendritic deposits could be easily peeled off, but the film-like deposits could not be peeled off. The electrodeposit accumulated at the bottom of the electrolytic cell 360 was filtered with filter paper 5A, and the electrodeposit was collected and subjected to component analysis, and it was found to be 98.0% zinc. The deposition rate of the metal powder per unit volume of the electrode part was 19.6 kg / m ３ / h. Compared with the deposition rate of the metal powder per unit volume of the electrode part (7 - 13 kg / m ３ / h) by the conventional electrode plate, it can be said that it is sufficiently large. The shortest distance between the electrodes in Example 2 is 10 mm. However, by making the shortest distance between the electrodes smaller, the current per unit volume of the electrode part increases, and the deposition rate of the metal powder per unit volume of the electrode part also increases.

[0186]

[0187] [Example 3] Using the post-leaching solution obtained in the same manner as in Example 2 and changing the cathode electrode 302 to an electrode made of titanium, the electro-deposition test apparatus shown in FIGS. 14 and 15 was used to recover the metal from the electrolytic solution. The electro-deposition time was set to 20 minutes, and other conditions were the same as in Example 2. The deposits deposited on the surface of the cathode electrode were dendritic, and almost no film-like deposits could be confirmed. Since the dendritic deposits became large and the possibility of short-circuiting with the anode electrode increased, the electro-deposition time was shortened to 20 minutes. The current efficiency during electro-deposition was about 89%, and about 99% of the electro-deposit was peeled off from the cathode electrode 302 by ultrasonic irradiation. The electro-deposit was collected and subjected to component analysis, and it was found to be 98.5% zinc. The deposition rate of the metal powder per unit volume of the electrode part was 20.9 kg / m ３ / h. Compared with the deposition rate of the metal powder per unit volume of the electrode part (7 - 13 kg / m ３ / h) by the conventional electrode plate, it can be said that it is sufficiently large.

[0188] [Example 101] - Recovery of electric furnace dust - In an electric furnace 10T having the configuration shown in Figure 31 and into which iron scrap is fed, the gas temperature at the furnace outlet 18T during arc discharge was measured using a B-type thermocouple sensor, the exhaust gas composition was measured by mass spectrometry using infiTOF-DUO (manufactured by KANOMAX), and the dust DT was recovered by the dust collector 24T of the exhaust gas treatment equipment, and the zinc oxide content in the dust was measured using the method described above. Amount of air fed into the electric furnace 10T, amount of gas containing CO, H ２ The amount of gas containing [the substance] or the amount of plastic powder added was varied, and the exhaust gas temperature and exhaust gas composition at the furnace outlet 18T were measured.

[0189] Exhaust gas temperature at electric furnace outlet 18T and (H) in the exhaust gas ２ +CO) / (H ２ O+CO ２ The relationship between the molar ratio (H) in the exhaust gas (mol / mol) and the zinc oxide content was obtained (Figure 35). ２ +CO) / (H ２ O+CO ２ As the molar ratio (H) increases, the zinc oxide content in the dust increases, and the formation of zinc ferrite is suppressed. In Figure 35, the line where the zinc oxide content is 40% is shown as a dotted line. According to this, preferably the molar ratio (H) in the exhaust gas is ２ +CO) / (H ２ O+CO ２ ) is 2.0 x 10 －２ By operating in the manner described above, the zinc oxide content in electric furnace dust can be said to be approximately 40% or more. The molar ratio (H) in the exhaust gas... ２ +CO) / (H ２ O+CO ２ ) is 5.0 x 10 －２ The above is preferable.

[0190] Meanwhile, in the electric furnace, CO and H ２ When the furnace was operated without adding any plastic powder, the exhaust gas composition at outlet 18T and the zinc oxide content in the dust were measured, and the exhaust gas contained CO and H ２ It was not present, and the zinc oxide content in the dust varied widely, ranging from 0% to less than 20%.

[0191] - Recovery of metallic zinc - Plastic powder is blown into the electric furnace during arc discharge to remove exhaust gas components (H ２ +CO) / (H ２ O+CO ２ ) (mol / mol) is 2.0 × 10 －２ ~2.0 x 10 －１ The amount of plastic powder blown in was adjusted using feedback control, and the electric furnace dust was recovered. The zinc content in the recovered electric furnace dust was 21.6% by mass, and the zinc oxide content was 53.0% by mass. The gas temperature at the furnace outlet 18 during arc discharge was measured using a Type B thermocouple sensor, and the gas composition was measured by mass spectrometry using an infiTOF-DUO (manufactured by KANOMAX).

[0192] As the leachate, an ammonia-containing solution (NH ３ A solution with a concentration of 50 g / L and pH 9, a strongly alkaline solution (pH 13.8) with pH adjusted with sodium hydroxide, and an acidic solution (pH 1) with pH adjusted with sulfuric acid were used. 100 g of electric furnace dust and 1 L of each leachate were placed in a sealed container and shaken in a shaker for one day to leach zinc. After shaking, the mixture was filtered through filter paper 5A to obtain the filtrate (leachate). In Examples 101-1 to 101-3, the leachate was used as the electrolyte, and the metal was recovered using the electrolytic emission test apparatus 300 shown in Figures 36 and 37. Figure 36 is a schematic front view, and Figure 37 is a schematic top view showing the frame-shaped cathode electrode 312T and the rod-shaped anode electrode 314T in the electrolytic emission test apparatus 300T shown in Figure 36. The anode electrode 314T (iridium oxide calcined electrode, base material: titanium) and the cathode electrode 312T (SUS304) (shortest distance between electrodes: 10 mm) were connected by insulating supports 318T and 319T (both made of rubber), and the areas near the liquid surface and the lower parts of both electrodes were insulated with insulating materials 326T and 327T (both made of paint). The length of one side of the cathode electrode 312T is 27 mm (see Figure 37).

[0193] Furthermore, the depth of the region of the cathode electrode 312T that is immersed in the electrolyte 224T but is not insulated by the insulating materials 326T and 327T (both paints) is 37 mm. The anode electrode 314T and cathode electrode 312T, which are connected by supports 318T and 319T and covered with insulating materials 326T and 327T, were placed in an electrolytic cell 216T (tall beaker). Furthermore, the lower part of the electrolytic cell 216T was placed inside a shielding plate 222T (specifically a shielding container) for ultrasonic shielding. Furthermore, the electrolytic cell 216T and shielding plate 222T were placed inside a water tank 210T, the water tank 210T was filled with water 220T, and an ultrasonic generator 230T was placed so as to be submerged in the water 220T. Incidentally, an iridium oxide calcined electrode was used because it has the effect of reducing oxygen overpotential at the anode electrode.

[0194] 110 ml of the leachate (electrolyte 224T) used in Example 102 was placed in the electrolytic cell 216T, and a power cable (not shown) was connected to the anode electrode 314T and the cathode electrode 312T, and electrodeposition was performed for 15 minutes. The power supply current was 0.5 A. The current per unit volume of the electrode was calculated from the current value during electrodeposition and the volume of the electrode. The volume of the electrode was 27.0 cm³, which is the volume of the area surrounded by the electrically active electrodes in the electrolyte 224T (dotted line portion in Figure 36). ３ Furthermore, the amount of metallic zinc electrodeposited was calculated from the change in zinc concentration of electrolyte 224T, and the current efficiency was calculated from the amount of current that flowed through the electrodeposition.

[0195] Next, after disconnecting the power cable, ultrasonic waves were generated for 15 seconds from the ultrasonic generator 230T installed outside the electrolytic cell 216T. After ultrasonic irradiation, the electrodes were washed with pure water and then dried, and their mass was measured. The amount of residual electrodeposition was calculated from the increase in mass from the initial electrode mass. The ratio of the amount of electrodeposition detached from the cathode electrode 312T was calculated from the amount of electrodeposited metallic zinc and the amount of residual electrodeposition.

[0196] In Example 101, which used a grid-like electrode, the current efficiency was 84-91%, the zinc content of the electrodeposited material was high at 95.2-98.1%, and the current per unit volume of the electrode was 18.6 kA / m². ３The deposition rate of metallic zinc per unit volume of the electrode section is 19.0 to 20.6 kg / m³. ３ The result was / h. On the other hand, the peeling rate of the electrodeposition was 57-63% by mass. The test conditions and results for Example 101 are shown in Table 4.

[0197]

[0198] [Example 102] Recovery of metallic zinc The same leachate used in Example 101 was used. In Examples 102-1 to 102-3, the leachate was used as the electrolyte, and the metal was recovered using the electrolytic emission test apparatus 400T shown in Figures 38 and 39. Figure 38 is a schematic front view, and Figure 39 is a cross-sectional view taken along line A-A in Figure 38, and is a schematic top view showing the cathode electrode 412T and anode electrode 414T in the electrolytic emission test apparatus 400T.

[0199] A rod-shaped anode electrode 414T (2 mmΦ x 8 pieces, wetted portion 80 mm, iridium oxide calcined electrode, base material: titanium) and a rod-shaped cathode electrode 412T (2 mmΦ x 8 pieces, wetted portion 80 mm, titanium) are connected by an insulating rubber-like support 418T (shortest distance between electrode surfaces: 5 mm), and the electrolyte surface is covered with an insulating material 426T. The anode electrode 414T and cathode electrode 412T are installed in an electrolytic cell 216T (tall beaker). A gas venting tube 432T is provided in the rubber-like support 418T. Furthermore, the lower part of the electrolytic cell 216T is placed inside a shielding plate 222T (specifically, a shielding container) for ultrasonic shielding. Furthermore, the electrolytic cell 216T and the shielding plate 222T were installed inside the water tank 210T, the water tank 210T was filled with water 220T, and the ultrasonic generator 230T was installed so as to be submerged in the water 220T.

[0200] 200 ml of the leached solution (electrolyte 224T) was placed in the electrolytic cell 216T, and the power cable 416T was connected to the anode electrode 414T and the cathode electrode 412T, and electrodeposition was performed for 15 minutes. The current of the power supply 52T was 2.4 A. The current per unit volume of the electrode section was calculated from the current value during electrodeposition and the volume of the electrode section. The volume of the electrode section is the volume of the area enclosed by the electrically active electrodes 412T and 414T in the electrolyte 224T (dotted line portion in Figure 38), which is 42.3 cm³. ３Furthermore, the amount of metallic zinc electrodeposited was calculated from the change in zinc concentration of electrolyte 224T, and the current efficiency was calculated from the amount of current that flowed through the electrodeposition.

[0201] Next, after disconnecting the power cable 416T, ultrasonic waves were generated for 15 seconds from the ultrasonic generator 230T installed outside the electrolytic cell 216T. After ultrasonic irradiation, the electrodes were washed with pure water and then dried, and their mass was measured. The amount of residual electrodeposition was calculated from the increase in mass from the initial electrode mass. The ratio of the amount of electrodeposition detached from the cathode electrode 412T was calculated from the amount of electrodeposited metallic zinc and the amount of residual electrodeposition.

[0202] In Example 102, which used a rod-shaped electrode, the current efficiency was 86-92%, the zinc content of the electrodeposited material was high at 95.5-98.3%, and the current per unit volume of the electrode was 57 kA / m². ３ The deposition rate of metallic zinc per unit volume of the electrode section is 59.8–64.0 kg / m³. ３ The result was / h. On the other hand, the peeling rate of the electrodeposition was 85-97% by mass. The test conditions and results for Example 102 are shown in Table 5.

[0203]

[0204] [Example 103] - Recovery of metallic zinc - The leachate obtained in Example 102-1 contained trace amounts of copper ions, and the leachate was light blue in color. The copper ion concentration in the leachate was measured by absorbance at a wavelength of 600 nm and was found to be 0.05 g / L. This was because the dust contained trace amounts of copper (0.11 mass%), and the copper leached out in the ammonia-containing solution. Therefore, metallic zinc powder was added to the leachate to precipitate elements with a lower ionization tendency than metallic zinc, such as copper, remaining in the leachate. After confirming that the copper ion concentration was 0.01 g / L or less, filtration was performed to obtain an intermediate leachate that was substantially free of copper ions.

[0205] Next, the intermediate leachate was used as the electrolyte, and the metal was recovered using an electrolytic deposition apparatus with rod-shaped electrodes as shown in Figures 38 and 39, which was used in Example 103. 200 ml of the leachate (electrolyte 224T) was placed in the electrolytic cell 216T, and electrolytic deposition was performed for 15 minutes. The power supply current was 2.4 A. Similar to Example 102, the zinc content of the electrodeposited material was measured, and the current per unit volume of the electrode, the current efficiency, and the electrodeposited material peeling rate were calculated. The current efficiency was 91%, the zinc content of the electrodeposited material was high at 99.4%, and the current per unit volume of the electrode was 57 kA / m². ３ The deposition rate of metallic zinc per unit volume of the electrode section is 63.3 kg / m³. ３ The result was / h. On the other hand, the delamination rate of the electrodeposit was 96% by mass.

[0206] The explanation of the symbols is as follows: 2A, 2B, 2C, 2E, 2F, 2G, 102, 202, 302, 402 Cathode electrode 4A, 4B, 4C, 4E, 4F, 4G, 104, 204, 304, 404 Anode electrode 10A, 10B, 10C, 310A, 310B Support body 12, 112, 312 Electrolyte 14E, 14F, 14G Power supply 20A, 20B, 20E, 20F, 20G, 40A, 40B, 40E, 40F, 40G Bus bar 22E Diaphragm 60, 360 Electrolytic cell 62A, 62B Funnel part 80, 380 Ultrasonic generator 82A, 82B, 82C, 82D, 382 Ultrasonic shielding plate 90 Spacer for short circuit prevention 100A, 100C, 100E, 100F Manufacturing equipment 102A Wire 110 Calculation area 120A, 120B Metal powder 314A, 314B Insulating material 400 Electrode unit 410A, 410B Connecting material 412 Frame 420A, 420B Connecting material 430 Double electrode connecting material 1000A, 1000B Electrolytic reaction apparatus 2T Storage silo 4T Blower 6T Piping 8T Inlet 10T Electric furnace (arc furnace) 12T Furnace lid 14T Electrode 16T Molten steel 18T Electric furnace outlet (gas analysis measurement area) 20T Combustion chamber 22T Cooling chamber 24T Dust collector 26T Fan 28T Exhaust duct 30T First stirring device 32T Leachate 40T Second stirring device 42T Leachate 44T Intermediate leachate 50T Electrolytic device 52T Power supply 54T Cathode 57T Short-circuit prevention spacer 56T Anode 58T Electrolytic cell 60T Ultrasonic generator 62T Ultrasonic shielding plate 64T Electrolyte 70T Metallic zinc powder 300T Electrolysis output test device 312T Cathode electrode 314T Anode electrode 318T Support (rubber) 319T Support (rubber) 326T Insulating material (paint) 327T Insulating material (paint) 400T Electrolysis output test device 412T Cathode electrode 414T Anode electrode 416T Power cable 428T Electrode volume calculation area 432T Gas vent tube

[0207] Furthermore, the disclosure of Japanese Patent Application No. 2025-012470 is incorporated herein by reference in its entirety. All documents, patent applications, and technical standards described herein are incorporated herein by reference to the same extent as if each individual document, patent application, and technical standard were specifically and individually noted as being incorporated by reference.

Claims

1. A metal powder manufacturing apparatus for depositing metal from an electrolyte containing metal ions by electrolysis and recovering it as metal powder, comprising: an electrolytic cell; a first electrode structure disposed in the electrolytic cell and three-dimensionally composed of a plurality of first electrodes with gaps between each of the first electrodes, or three-dimensionally composed of a single first electrode with a gap in which the single first electrode is open to the outside; and a second electrode disposed such that at least a portion of the gap in the first electrode structure is not in contact with the first electrode, wherein one of the first electrode and the second electrode is an anode electrode and the other is a cathode electrode.

2. The metal powder manufacturing apparatus according to claim 1, further comprising a mechanism for detaching the metal powder deposited on the surface of the cathode electrode from the cathode electrode.

3. The metal powder manufacturing apparatus according to claim 1, wherein the first electrode structure is a first electrode structure that is three-dimensionally composed of the plurality of first electrodes and has gaps between each of the first electrodes, and the first electrode structure is a structure having a plurality of grid-like planar electrode bodies in which the plurality of first electrodes are arranged in a planar manner, and the plurality of grid-like planar electrode bodies are stacked with gaps between them, or a structure having a grid-like three-dimensional structure in which the plurality of first electrodes are arranged in a planar manner, and the plurality of grid-like planar electrode bodies are stacked with gaps between them, and the grid-like planar electrode bodies are connected to each other.

4. The metal powder manufacturing apparatus according to claim 3, wherein the shape of the second electrode is wire-like or rod-like, and the second electrode is disposed in the gap of the first electrode structure.

5. The metal powder manufacturing apparatus according to claim 1, wherein the first electrode structure comprises a plurality of first electrodes, each wire-shaped or rod-shaped and arranged parallel to each other with a gap between them, and a plurality of second electrodes are arranged in the gap in the first electrode structure in a direction perpendicular or oblique to the plurality of first electrodes, and the plurality of second electrodes are each wire-shaped or rod-shaped and arranged parallel to each other.

6. The metal powder manufacturing apparatus according to claim 1, wherein the first electrode structure and the second electrode are fixed to a support that is an insulator.

7. The metal powder manufacturing apparatus according to claim 1, wherein at least one of the first electrode structure and the second electrode has a surface that is in contact with the liquid surface of the electrolyte covered with an insulator.

8. The metal powder manufacturing apparatus according to claim 1, wherein the distance of the second electrode to the nearest first electrode is in the range of 1 mm to 50 mm.

9. The metal powder manufacturing apparatus according to claim 8, wherein the distance of the second electrode to the nearest first electrode is in the range of 1 mm to 20 mm.

10. The metal powder manufacturing apparatus according to claim 9, wherein the distance of the second electrode to the nearest first electrode is in the range of 2 mm to 10 mm.

11. The metal powder manufacturing apparatus according to claim 10, wherein the distance of the second electrode to the nearest first electrode is in the range of 2 mm to 5 mm.

12. The metal powder manufacturing apparatus according to claim 2, wherein the peeling mechanism is at least one selected from the group consisting of a device for generating ultrasonic waves and a device for applying impact to the cathode electrode.

13. A method for producing metal powder, using the metal powder production apparatus described in any one of claims 1 to 12, wherein the metal powder contains at least one of copper and zinc, and the electrolyte is an acidic electrolyte with a pH of 1.0 to 5.0, a strongly alkaline electrolyte with a pH of 13.0 to 14.5, or an ammonia-containing alkaline electrolyte with a pH of 7.0 to 12.0 containing ammonia.

14. A method for processing iron scrap, comprising: a leaching step of leaching at least one of copper and zinc from iron scrap into a leaching solution; and an electrodeposition step of electrodepositing at least one of the leached copper and zinc, and separating at least one of the copper and zinc from the leaching solution, wherein in the electrodeposition step, a metal powder manufacturing apparatus according to any one of claims 1 to 12 is used, an ammonia-containing alkaline leaching solution is used as the leaching solution, the leaching solution from which at least one of the copper and zinc has been leached is used as the electrolyte, and at least one of the copper and zinc is electrodeposited from the electrolyte.

15. The method for processing iron scrap according to claim 14, further comprising a heat treatment step of heat-treating the iron scrap before the leaching step.

16. The method for processing iron scrap according to claim 14, further comprising a quality improvement step after the leaching step to improve the quality of the iron scrap.

17. The method for processing iron scrap according to claim 15, further comprising a sorting step of sorting the iron scrap before the heat treatment step.

18. The method for processing iron scrap according to claim 14, wherein the electrodeposition step is a multi-stage electrodeposition step, and the voltages applied to the first electrode and the second electrode in the metal powder manufacturing apparatus installed in each electrodeposition step are controlled to be different voltages.

19. The method for processing iron scrap according to claim 15, wherein in the heat treatment step, the heating temperature of the iron scrap is 350°C to 800°C.

20. The method for processing iron scrap according to claim 15, wherein in the heat treatment step, the heating temperature of the iron scrap is 400°C to 600°C.

21. The method for processing iron scrap according to claim 15, wherein the iron scrap is subjected to heat treatment while being rolled during the heat treatment step.

22. A method for recovering metallic zinc from dust, comprising leaching at least the zinc component from dust containing zinc oxide using a leachate, and recovering metallic zinc by electrolytic deposition from the obtained leachate containing zinc ions, wherein the leachate is an acidic leachate with a pH of 1.0 to 5.0, a strongly alkaline leachate with a pH of 13.0 to 14.5, or an ammonia-containing alkaline leachate with a pH of 7.0 to 12.0 containing ammonia, and the apparatus used for electrolytic deposition is a metal powder manufacturing apparatus according to any one of claims 1 to 12, the leachate from which the zinc component has been leached is used as the electrolyte, and at least the metallic zinc is electrodeposited from the electrolyte.

23. The method for recovering metallic zinc from dust according to claim 22, wherein the zinc oxide-containing dust is obtained by placing an amount of the zinc oxide-containing dust such that the zinc content is 4 g in a leachate of 1 L of 185 g / L aqueous solution of ammonium sulfate adjusted to pH 9.5 to 11.5 with an aqueous sodium hydroxide solution, shaking the sealed container for 24 hours to leach the zinc into the leachate, measuring the zinc content and iron content in the zinc oxide-containing dust before and after leaching, and determining that the zinc oxide content of the zinc oxide-containing dust is 40% or more, calculated using the following formula: Zinc oxide content of zinc oxide-containing dust = {(Zn content before leaching / Fe content before leaching) - (Zn content after leaching / Fe content after leaching)} ÷ (Zn content before leaching / Fe content before leaching) × 100 24. The dust containing zinc oxide is electric furnace dust generated from an arc discharge type electric furnace for steel manufacturing, and the exhaust gas at the outlet of the electric furnace during arc discharge contains (H ２ +CO) / (H ２ O+CO ２ ) is 2.0 × 10 in molar ratio －２ The method for recovering metallic zinc from electric furnace dust according to claim 23, wherein the dust is obtained by operating in such manner.

25. Adjust the amount of at least one of the hydrogen-containing gas and organic compound to be introduced into the electric furnace, and the (H ２ +CO) / (H ２ O+CO ２ ) is 2.0 × 10 in molar ratio －２ The method for recovering metallic zinc from dust according to claim 24, wherein the electric furnace is operated in such manner.

26. A method for recovering metallic zinc from dust according to claim 22, comprising: separating the dust containing zinc oxide into magnetically attached and non-magnetic materials by magnetic separation; immersing the separated non-magnetic materials in the leachate to extract the zinc component; and recovering metallic zinc by electrolytic extraction from the resulting leachate containing zinc ions.

27. A method for recovering metallic zinc from dust according to claim 22, further comprising adding metallic zinc to the leachate containing zinc ions, precipitating elements with a lower ionization tendency than zinc from the leachate containing zinc ions, and recovering metallic zinc by precipitating it from the intermediate leachate containing zinc ions after separating the precipitates by electrolytic extraction.

28. The method for recovering metallic zinc from dust according to claim 22, wherein, after removing the leachate adhering to the metallic zinc precipitated and recovered by electrolytic extraction, the metallic zinc is melted and the molten metallic zinc is recovered.

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