Method and device for recovering zinc from zinc residue by wet process

Abstract

The application provides a method and device for recovering metal zinc from zinc hydrometallurgy residue, and belongs to the field of metal production or refining. The method uses one or more of N2+CH4, CO, CO2 and carbon powder in plasma state as active substances to act on the powdered zinc hydrometallurgy residue in the form of side blowing, so as to efficiently obtain metal zinc. The method can realize the recovery of metal zinc from the zinc hydrometallurgy residue in 20-60 min, and the recovery rate of the metal zinc is as high as 97.4%. The process flow is simple, the carbon emission can be greatly reduced, and the application prospect is wide. The corresponding device mainly comprises a molten pool smelting furnace and a plasma generating device arranged on the side wall of the molten pool smelting furnace. The inner wall of the flue close to one end of the hearth is provided with a porous carbon material, so as to ensure the strong reducing atmosphere condition and inhibit the oxidation of zinc vapor. The device has a simple structure, can efficiently and batch-process the powdered zinc hydrometallurgy residue, and recover the metal zinc in the powdered zinc hydrometallurgy residue.

Description

Technical Field

[0001] This invention belongs to the field of metal production or refining, and particularly relates to a method and apparatus for recovering metallic zinc from hydrometallurgical zinc slag. Background Technology

[0002] How to treat the slag produced in the hydrometallurgical zinc smelting process has always been a technical challenge in the industry. Currently, the mainstream pyrometallurgical treatment processes for hydrometallurgical zinc slag are rotary kiln volatilization and fuming furnace methods. These methods use high-temperature reduction to volatilize and concentrate metals such as zinc and lead in the flue dust, achieving a recovery rate of about 90%. Among these, the rotary kiln volatilization method is more widely used in China due to its mature technology and strong adaptability to raw materials.

[0003] However, pyrometallurgical processes exhibit the following limitations in industrial applications: While rotary kiln volatilization can volatilize and enrich metals such as zinc and lead in flue gas through high-temperature reduction, the utilization rate of coke or pulverized coal is generally low during the process. The reducing agent, due to density differences, struggles to fully contact the metal oxides within the melt, resulting in actual carbon consumption as high as 40-50% of the mass of the material entering the kiln, leading to resource waste. Furthermore, pyrometallurgical processes have long reaction times. For example, rotary kiln volatilization requires multiple stages (drying-pre-calcination-reduction-volatilization), with a single processing cycle lasting 3-4 hours, and the furnace temperature must be maintained at 1100-1300℃, resulting in high energy costs. In terms of environmental protection, the reaction of large amounts of coal coke with sulfides generates gases such as CO and SO2, requiring complex tail gas treatment facilities, further increasing operating costs. Summary of the Invention

[0004] The main objective of this invention is to provide a method and apparatus for recovering metallic zinc from hydrometallurgical zinc slag, aiming to solve the problems of complex process flow, high carbon consumption, and environmental unfriendliness in the recovery of metallic zinc from hydrometallurgical zinc slag using existing technologies.

[0005] To achieve the above objectives, the present invention provides a method for recovering metallic zinc from hydrometallurgical zinc slag, comprising the following steps:

[0006] We provide powdered zinc slag from wet zinc smelting.

[0007] The wet zinc slag powder is fed into a molten pool furnace, and plasma-active substances are blown from both sides of the furnace into the furnace to react and obtain zinc-containing vapor; wherein the sources of the plasma-active substances include N2, and one or more of CH4, CO, CO2 and carbon powder.

[0008] The zinc-containing vapor is captured and recovered to obtain metallic zinc.

[0009] Furthermore, the plasma-state active material is a plasma torch generated by a plasma generator; and the power of the plasma torch is 300-500kW.

[0010] Furthermore, the reaction time of the side-blown plasma active material step is 20–60 min.

[0011] Furthermore, the particle size range of the wet zinc slag powder is 47–5000 μm.

[0012] Furthermore, the wet zinc slag powder material comprises the following components by mass percentage: zinc 5-30 wt%, lead 1-10 wt%, iron 10-40 wt%, silicon 5-20 wt%, copper 0-3 wt%, sulfur 1-10 wt%, and calcium 0-5%.

[0013] Furthermore, the sources of the wet zinc smelting slag powder include one or more of the following: intermediate leaching slag, acid leaching slag, goethite slag, iron alum slag, and lead-silver slag.

[0014] Furthermore, in the side-blown plasma active material step, the required side-blown gas flow rate is 10-100 L / min per kilogram of the wet zinc smelting slag powder.

[0015] The required mass of side-blown carbon powder per kilogram of the aforementioned wet zinc smelting slag powder is 0.15–0.25 kg.

[0016] Furthermore, the collection and recovery method is liquid zinc rain spray collection; wherein, the temperature of the liquid zinc rain is 500-700℃.

[0017] The present invention also provides an apparatus for recovering metallic zinc from hydrometallurgical zinc slag, for implementing the method for recovering metallic zinc from hydrometallurgical zinc slag as described in any of the preceding claims. The apparatus for recovering metallic zinc from hydrometallurgical zinc slag includes a molten pool furnace, a plasma generating device, and a zinc condensing device; the plasma generating device is disposed on the side wall of the molten pool furnace; and the zinc condensing device is connected to the top of the molten pool furnace.

[0018] The molten pool smelting furnace includes a furnace chamber, a sealed charging port, a recovery flue, and a slag discharge port; the sealed charging port and the recovery flue are respectively located at both ends of the top of the molten pool smelting furnace, and both the sealed charging port and the recovery flue are connected to the furnace chamber; the slag discharge port is located near the bottom of the molten pool smelting furnace.

[0019] The inner wall of the recovery flue near the furnace is provided with porous carbon material; the pore size of the porous carbon material is 20-100 mm; the height of the porous carbon material is 1-5 m; the end of the recovery flue away from the furnace is connected to the zinc condensation device.

[0020] The number of plasma generating devices is no less than two; and the plasma-state active material generated by the plasma generating devices is ejected in a direction that is aimed at the bottom of the furnace.

[0021] Furthermore, the sidewall material of the molten pool furnace includes refractory bricks.

[0022] The beneficial effects achieved by this invention are as follows:

[0023] This invention provides a method for recovering metallic zinc from hydrometallurgical zinc slag. This method involves applying a plasma-state active substance (one or more of N2+CH4, CO, CO2, and carbon powder) to the powdery hydrometallurgical zinc slag via side blowing to efficiently obtain metallic zinc. Using this method, the recovery of metallic zinc from hydrometallurgical zinc slag can be achieved within 20–60 minutes, with a recovery rate as high as 97.4%. The process is simple, and the ultra-high temperature and reducing active groups generated by the plasma-state active substance can significantly improve the efficiency of the reduction reaction while substantially reducing carbon emissions, demonstrating broad application prospects.

[0024] The apparatus for simultaneously recovering lead and zinc from lead-zinc oxides provided by this invention is designed in accordance with the method for recovering metallic zinc from hydrometallurgical zinc slag provided by this invention. It mainly consists of a molten pool furnace and a plasma generator mounted on its sidewall. The top of the molten pool furnace is equipped with a recovery flue. The inner wall of the recovery flue near the furnace end is lined with porous carbon material (pore size 20-100 mm, height 1-5 m), which can convert all CO2 in the atmosphere into CO, ensuring a strong reducing atmosphere to suppress the oxidation of zinc vapor. This allows for direct recovery of elemental zinc without returning it to the hydrometallurgical process. This apparatus has a simple structure and can efficiently process powdery hydrometallurgical zinc slag in batches to recover metallic zinc. Attached Figure Description

[0025] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0026] Figure 1 This is a schematic diagram of a possible embodiment of the present invention for recovering metallic zinc from wet zinc smelting slag;

[0027] Figure 2 This is a scanning electron microscope (SEM) image of the slag phase in Example 1 of the present invention;

[0028] Figure 3The image shown is the energy-dispersive X-ray spectroscopy (EDS) image corresponding to the scanning electron microscope (SEM) image of the slag phase in Embodiment 1 of the present invention.

[0029] Figure 4 This is a scanning electron microscope (SEM) image of the slag phase in Example 2 of the present invention;

[0030] Figure 5 The image shown is the energy-dispersive X-ray spectroscopy (EDS) image corresponding to the scanning electron microscope (SEM) image of the slag phase in Embodiment 2 of the present invention.

[0031] Figure 6 This is a scanning electron microscope (SEM) image of the slag phase in Example 3 of the present invention;

[0032] Figure 7 The image shown is the energy-dispersive X-ray spectroscopy (EDS) image corresponding to the scanning electron microscope (SEM) image of the slag phase in Embodiment 3 of the present invention.

[0033] Figure 8 This is a scanning electron microscope (SEM) image of the slag phase in Example 4 of the present invention;

[0034] Figure 9 The image shown is the energy-dispersive X-ray spectroscopy (EDS) image corresponding to the scanning electron microscope (SEM) image of the slag phase in Embodiment 4 of the present invention.

[0035] Figure 10 The image shows the X-ray diffraction (XRD) pattern of the slag phase in Comparative Example 1 of this invention.

[0036] Figure 11 The image shows an X-ray diffraction (XRD) pattern of furnace wall dust in Comparative Example 2 of this invention.

[0037] Figure 12 This is a scanning electron microscope (SEM) image of the slag phase of Comparative Example 3 of the present invention.

[0038] Figure 13 The image shown is the energy-dispersive X-ray spectroscopy (EDS) image corresponding to the scanning electron microscope (SEM) image of the slag phase of Comparative Example 3 of this invention.

[0039] The realization of the objective, functional characteristics and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0040] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] It should be noted that, unless otherwise specified, the following embodiments and features can be combined with each other. It should also be understood that the terminology used in the embodiments of this invention is for describing specific implementations and not for limiting the scope of protection of this invention.

[0042] Unless otherwise defined, all technical and scientific terms used in this invention, as well as the prior art known to those skilled in the art and the description of this invention, can be applied to implement this invention using any prior art methods, equipment, and materials similar to or equivalent to those described, used, or made in the embodiments of this invention. When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in this invention, both endpoints of each numerical range, as well as any value between the two endpoints, may be used. Test methods in the following embodiments that do not specify specific conditions are generally performed under conventional conditions or as recommended by the respective manufacturers. Materials or reagents required in the following embodiments are commercially available unless otherwise specified.

[0043] To address the problems of complex processes, high carbon consumption, and environmental unfriendliness in recovering metallic zinc from hydrometallurgical slag using existing technologies, this invention provides a method for recovering metallic zinc from hydrometallurgical slag, comprising the following steps:

[0044] We provide wet zinc smelting slag powder. Specifically, the wet zinc smelting slag is subjected to drying, crushing, and grinding processes in sequence to obtain the wet zinc smelting slag powder.

[0045] Powdered zinc slag from the wet zinc smelting process is fed into a molten pool furnace, and plasma-state active materials are blown into the furnace from both sides to react and produce zinc-containing vapor. The sources of the plasma-state active materials include N2, and one or more of CH4, CO, CO2, and carbon powder. Preferably, the volume ratio of N2 to one or more of CH4, CO, and CO2 is 10:1 to 3. Experiments showed that when all plasma-state active materials are gases, the zinc recovery rate is highest and can be consistently above 90% when the volume ratio of nitrogen (N2) to other gases (CH4, CO, and CO2) is 10:1 to 3.

[0046] Zinc vapor is captured and recovered to obtain metallic zinc.

[0047] This invention provides a method for recovering metallic zinc from hydrometallurgical zinc slag. This method involves applying a plasma-state active substance (one or more of N2+CH4, CO, CO2, and carbon powder) to the powdery hydrometallurgical zinc slag via side blowing to efficiently obtain metallic zinc. Using this method, the recovery of metallic zinc from hydrometallurgical zinc slag can be achieved within 20–60 minutes, with a recovery rate as high as 97.4%. The process is simple, and the ultra-high temperature and reducing active groups generated by the plasma-state active substance can significantly improve the efficiency of the reduction reaction while substantially reducing carbon emissions, demonstrating broad application prospects.

[0048] Furthermore, the plasma-state active material is a plasma torch generated by plasma generator 1; and the power of the plasma torch is 300-500 kW. Specifically, the plasma torch with a power of 300-500 kW has high-temperature energy, which can meet the temperature energy consumption requirements of the entire process of recovering metallic zinc from wet zinc smelting slag in this invention, without the need for additional external energy sources such as sulfide ore or coke. After the plasma torch with a power of 300-500 kW is side-blown into the molten pool smelting furnace, the following reaction will occur:

[0049] The main components of wet zinc smelting slag are metal oxides (MeO) and metal sulfates (MeSO4):

[0050] 2MeO + C· = 2Me + CO2(g)

[0051] MeO+CO - =Me + CO2(g)

[0052] MeSO4 + 2C = Me + S 2- +2CO2(g)

[0053] MeSO4+4CO - =Me+S 2- +4CO2(g)

[0054] Furthermore, the reaction time for the side-blown plasma active material step is 20–60 min. Specifically, when the reaction time for the side-blown plasma active material step is 20–60 min, the final zinc recovery rate stabilizes at over 90%.

[0055] Furthermore, the particle size range of the wet zinc smelting slag powder is 47–5000 μm. Specifically, during the experiment, it was found that in order for the side-blown plasma active material to react effectively with the wet zinc smelting slag, the wet zinc smelting slag needs to be crushed and ground to a particle size range of 47–5000 μm (300 mesh–5 mm) to form a wet zinc smelting slag powder. If the particle size after crushing and grinding is too small, less than 300 mesh, the material will be blown onto the furnace wall during the plasma injection process, reducing the reduction effect; if the particle size is greater than 5 mm, the internal reaction of the material particles will not be complete within a short time during the reaction process.

[0056] Furthermore, the wet zinc slag powder material comprises the following components by mass percentage: zinc 5–30 wt%, lead 1–10 wt%, iron 10–40 wt%, silicon 5–20 wt%, copper 0–3 wt%, sulfur 1–10 wt%, and calcium 0–5%. Specifically, the reduction reaction of ZnFe2O4 and metal sulfate components in the traditional pyrometallurgical treatment of wet zinc slag consumes a large amount of heat, has low reaction efficiency, and the generated ZnS is difficult to further reduce. This method efficiently reduces ZnFe2O4 to elemental zinc and iron oxide while avoiding the formation of ZnS.

[0057] Furthermore, the sources of wet zinc smelting slag powder include one or more of the following: intermediate leaching slag, acid leaching slag, goethite slag, iron alum slag, and lead-silver slag.

[0058] Furthermore, in the side-blown plasma active material step, the required side-blown gas flow rate is 10–100 L / min per kilogram of wet zinc smelting slag powder. Specifically, when the gas flow rate is less than 10 L / min, the number of active groups generated is small, and the reduction reaction is incomplete; when the gas flow rate is greater than 100 L / min, the excessive gas flow rate can easily disperse the material particles, reducing the reduction effect, and at the same time, the excessive active groups result in waste.

[0059] The required side-blown carbon powder mass per kilogram of wet zinc smelting slag powder is 0.15–0.25 kg. Specifically, when the carbon powder mass is less than 0.15 kg, the reduction is insufficient and the reduction rate is low; when the carbon powder mass is greater than 0.25 kg, the carbon powder is excessive, the reduction effect is not significantly improved, and the excess carbon powder is wasted.

[0060] Furthermore, the collection and recovery method is liquid zinc rain spray collection; wherein, the temperature of the liquid zinc rain is 500-700℃. Specifically, at temperatures below 500℃, liquid zinc easily solidifies into a solid; at temperatures above 700℃, the zinc vapor condensation effect decreases, and some zinc vapor is not completely condensed.

[0061] Reference Figure 1The present invention also provides an apparatus for recovering metallic zinc from hydrometallurgical zinc slag, for implementing the method for recovering metallic zinc from hydrometallurgical zinc slag as described in any of the preceding claims. The apparatus for recovering metallic zinc from hydrometallurgical zinc slag includes a molten pool furnace, a plasma generating device 1, and a zinc condensing device 7. The plasma generating device 1 is disposed on the side wall of the molten pool furnace. The zinc condensing device 7 is connected to the top of the molten pool furnace.

[0062] The molten pool smelting furnace includes a furnace chamber, a sealed charging port 2, a recovery flue 6, and a slag discharge port 4. The sealed charging port 2 and the recovery flue 6 are respectively located at opposite ends of the top of the molten pool smelting furnace, and both are connected to the furnace chamber. The slag discharge port 4 is located near the bottom of the molten pool smelting furnace. Specifically, the location of the slag discharge port 4 near the bottom of the molten pool smelting furnace facilitates the recovery of the iron-containing molten slag after the reaction.

[0063] The inner wall of the recovery flue 6 near the furnace is provided with porous carbon material 3; the pore size of the porous carbon material 3 is 20-100 mm; the height of the porous carbon material 3 is 1-5 m; the end of the recovery flue 6 away from the furnace is connected to the zinc condensation device 7. Specifically, in the molten pool smelting furnace, the wet zinc slag powder material in the furnace reacts instantaneously with the plasma active material injected from the side of the plasma generator 1, causing the gaseous volatile components (including zinc vapor) reduced from the wet zinc slag powder material to escape rapidly. However, CO2 is also present in the gaseous volatile components, which will decompose into CO and O2 at high temperature, leading to an increase in oxygen potential, which easily oxidizes the zinc vapor, thereby interfering with the subsequent recovery of metallic zinc. Therefore, to address this technical problem, based on multiple experiments and adjustments, a porous carbon material 3 with a pore size of 20-100 mm and a height of 1-5 m was installed on the inner wall of the end of the recovery flue 6 near the furnace. Through the Bourdon reaction, CO2 + C = 2CO, all CO2 is converted into CO. Maintaining a reducing atmosphere of CO can prevent the oxidation of zinc vapor, further improving the zinc recovery rate of the metallic zinc captured by the final zinc condensation device 7.

[0064] The number of plasma generating devices 1 is not less than two; and the direction of the plasma active material ejected by the plasma generating devices 1 is directed towards the bottom of the furnace. Preferably, the plasma generating device 1 includes a first generator and a second generator; the first generator is used to spray N2, and the second generator is used to spray one or more of CH4, CO, CO2, and carbon powder. In an optional embodiment, the first generator and the second generator are started first; then, wet zinc slag powder is added to the molten pool furnace through the sealed feeding port 2, and the sealed feeding port 2 is closed; the vent valve of the first generator of the plasma generating device 1 is opened to perform N2 purging; then the vent valve of the second generator of the plasma generating device 1 is opened, and one or more of CH4, CO, CO2, and carbon powder are side-blown into the molten pool furnace. When the substances carried in the second generator are all gases, the volume ratio of the gas injected by the first generator to the gas injected by the second generator is 10:1 to 3. In another optional embodiment, the plasma generator 1 has a mixing module, under the control of the mixing module, the substances entering the plasma generator 1 can be mixed into a mixture in a specified ratio and sprayed at a specified flow rate; wherein, when the substances entering the plasma generator 1 are all gases, the volume ratio of N2 in the mixture to other gases (one or more of CH4, CO and CO2) is 10:1 to 3.

[0065] Furthermore, the sidewall material of the molten pool smelting furnace includes refractory bricks 5. Specifically, refractory bricks 5 can withstand high temperatures and melt corrosion, protecting the furnace metal structure; and refractory bricks 5 have a low thermal conductivity, which can reduce heat loss from the furnace and improve thermal efficiency.

[0066] The apparatus for simultaneously recovering lead and zinc from lead-zinc oxides provided by this invention is designed in accordance with the method for recovering metallic zinc from hydrometallurgical zinc slag provided by this invention. It mainly consists of a molten pool furnace and a plasma generator mounted on its sidewall. The top of the molten pool furnace is equipped with a recovery flue. The inner wall of the recovery flue near the furnace end is lined with porous carbon material (pore size 20-100 mm, height 1-5 m), which can convert all CO2 in the atmosphere into CO, ensuring a strong reducing atmosphere to suppress the oxidation of zinc vapor. This allows for direct recovery of elemental zinc without returning it to the hydrometallurgical process. This apparatus has a simple structure and can efficiently process powdery hydrometallurgical zinc slag in batches to recover metallic zinc.

[0067] To further illustrate the present invention, the following examples are provided:

[0068] Example 1

[0069] (1) First, the zinc leaching slag sample was dried, crushed, ground into powder and sieved through a 100-mesh (150μm) sieve to obtain 100g of wet zinc smelting slag powder with the main components being Zn, Fe, Pb, S, Si, Ca, and Cu of 18.3%, 25.3%, 5.53%, 4.9%, 7.3%, 1.9%, and 0.6% (wt.%), and the remainder being other oxide impurities. The mixture was added to the molten pool furnace through the sealed feeding port 2.

[0070] (2) Turn on the plasma generator 1, adjust the power of the plasma torch to 350kW, and control the flow rate of the side-blown gas to 60L / min. The side-blown gas is a mixture of N2 and CO in a volume ratio of 10:1. The plasma torch is used to carry out plasma reaction on the wet zinc slag powder material fed into the molten pool smelting furnace.

[0071] (3) The reaction time was 25 min, and the gaseous volatile components were obtained. The main components of the gaseous volatile components were Pb and Zn. The zinc-containing vapor was collected through a recovery flue 6 with porous carbon material 3 (pore size 80 mm, height 1 m) on the inner wall and sent to a zinc condenser 7 (zinc rain temperature 700℃) to obtain metallic zinc. The zinc recovery rate was 95.7%.

[0072] The slag phase collected from slag outlet 4 was tested and found to be mainly composed of silicate oxides formed by calcium, iron and silicon, with some iron reduced from the molten iron. The zinc content in the slag phase was 1.14% and the lead content was 1.11% (Table 1).

[0073] Table 1. Surface scan total spectrum of slag phase in Example 1

[0074]

[0075]

[0076] The slag phase was analyzed by energy-dispersive X-ray spectroscopy (EDS), and the scanning electron microscopy (SEM) results are as follows: Figure 2 As shown, the SEM image of this slag phase ( Figure 2 The corresponding EDS detection results are as follows: Figure 3 As shown. Combined with Figure 2 and Figure 3 It can be seen that the slag phase mainly consists of iron oxides, metallic iron phase, and metal sulfides.

[0077] Example 2

[0078] (1) First, the zinc leaching slag sample was dried, crushed, ground into powder and sieved through a 200-mesh (74μm) sieve to obtain 100g of wet zinc smelting slag powder with the main components being Zn, Fe, Pb, S, Si, Ca, and Cu of 18.3%, 25.3%, 5.53%, 4.9%, 7.3%, 1.9%, and 0.6% (wt.%), and the remainder being other oxide impurities. The mixture was added to the molten pool furnace through the sealed feeding port 2.

[0079] (2) Turn on the plasma generator 1, adjust the power of the plasma torch to 400kW, and control the flow rate of the side-blown gas to 65L / min. The side-blown gas is a mixture of N2 and CH4 in a volume ratio of 10:3. The plasma torch is used to carry out plasma reaction on the wet zinc slag powder material fed into the molten pool smelting furnace.

[0080] (3) The reaction time was 35 min, and the gaseous volatile components were obtained. The main components of the gaseous volatile components were Pb and Zn. The zinc-containing vapor was collected through a recovery flue 6 with porous carbon material 3 (pore size 20 mm, height 5 m) on the inner wall and sent to a zinc condenser 7 (zinc rain temperature 500℃) to obtain metallic zinc. The zinc recovery rate was 97.4%.

[0081] The slag phase collected from slag outlet 4 is shown in the scanning electron microscope (SEM) results as follows: Figure 4 As shown, the SEM image of this slag phase ( Figure 4 The corresponding EDS detection results are as follows: Figure 5 As shown. Combined with Figure 4 and Figure 5 It can be seen that the main components of the slag phase are silicate oxides formed by calcium and silicon and iron phase. The zinc content in the slag phase is 0.63% and the lead content is 1.2% (Table 2).

[0082] Table 2. Surface scan total spectrum of slag phase in Example 2

[0083]

[0084]

[0085] Example 3

[0086] (1) First, the zinc leaching slag sample was dried, crushed, ground into powder and sieved through a 300-mesh (50μm) sieve to obtain 100g of wet zinc smelting slag powder with the main components being Zn, Fe, Pb, S, Si, Ca, and Cu of 18.3%, 25.3%, 5.53%, 4.9%, 7.3%, 1.9%, and 0.6% (wt.%), and the remainder being other oxide impurities. The mixture was added to the molten pool furnace through the sealed feeding port 2.

[0087] (2) Turn on the plasma generator 1, adjust the power of the plasma torch to 500kW, and control the flow rate of the side-blown gas to 100L / min. The side-blown gas is a mixture of N2:CO2:CH4 in a volume ratio of 10:1:2. The plasma torch is used to carry out plasma reaction on the wet zinc slag powder material fed into the molten pool smelting furnace.

[0088] (3) The reaction time was 30 min, and the gaseous volatile components were obtained. The main components of the gaseous volatile components were Pb and Zn. The zinc-containing vapor was collected through a recovery flue 6 with porous carbon material 3 (pore size 60 mm, height 3 m) on the inner wall and sent to a zinc condenser 7 (zinc rain temperature 600℃) to obtain metallic zinc. The zinc recovery rate was 93.2%.

[0089] The slag phase collected from slag outlet 4 is shown in the scanning electron microscope (SEM) results as follows: Figure 6 As shown, the SEM image of this slag phase ( Figure 6 The corresponding EDS detection results are as follows: Figure 7 As shown. Combined with Figure 6 and Figure 7 It can be seen that the main components of the slag phase are calcium, silicon and iron, silicate oxides formed by silicon, and a certain amount of iron is reduced from the molten iron. The precipitated metal phase is mainly iron phase. The zinc content in the slag phase is 1.81% and the lead content is 1.48% (Table 3).

[0090] Table 3. Surface scan total spectrum of slag phase in Example 3

[0091]

[0092] Example 4

[0093] (1) First, the zinc leaching slag sample was dried, crushed, ground into powder and sieved through a 10-mesh (2000μm) sieve to obtain 100g of wet zinc smelting slag powder containing Zn, Fe, Pb, S, Si, Ca and Cu of 18.3%, 25.3%, 5.53%, 4.9%, 7.3%, 1.9% and 0.6% (wt.%), with the remainder being other oxide impurities. The mixture was added to the molten pool furnace through the sealed feeding port 2.

[0094] (2) Turn on plasma generator 1, adjust the power of plasma torch to 300kW, control the side-blown gas flow rate to 55L / min, the side-blown gas is N2, and simultaneously spray carbon powder at a rate of 1.2g / min.

[0095] The plasma torch is used to perform a plasma reaction on the wet zinc slag powder material fed into the molten pool smelting furnace.

[0096] (3) The reaction time was 20 min, and the gaseous volatile components were obtained. The main components of the gaseous volatile components were Pb and Zn. The zinc-containing vapor was collected through a recovery flue 6 with porous carbon material 3 (pore size 80 mm, height 4 m) on the inner wall and sent to a zinc condenser 7 (zinc rain temperature 500℃) to obtain metallic zinc. The zinc recovery rate was 96.1%.

[0097] The slag phase collected from slag outlet 4 is shown in the scanning electron microscope (SEM) results as follows: Figure 8 As shown, the SEM image of this slag phase ( Figure 8 The corresponding EDS detection results are as follows: Figure 9 As shown. Combined with Figure 8 and Figure 9 It can be seen that the main components of the slag phase are silicate oxides formed by calcium, iron and silicon, with a certain amount of iron molten metal reduced. The precipitated metal phase is mainly iron phase, with zinc content of 1.57% and lead content of 0.87% in the slag phase (Table 4).

[0098] Table 4. Surface scan total spectrum of slag phase in Example 4

[0099]

[0100] Comparative Example 1

[0101] (1) First, the obtained zinc leaching slag sample was dried, crushed, ground into powder, and sieved through a 100-mesh (150μm) sieve to obtain 100g of wet zinc smelting slag powder containing Zn, Fe, Pb, S, Si, Ca, and Cu of 18.3%, 25.3%, 5.53%, 4.9%, 7.3%, 1.9%, and 0.6% (wt.%), with the remainder being other oxide impurities. An electromagnetic induction heating device was used to control the temperature inside the furnace tube at 1250±50℃, and N2 and O2 (7:3) were introduced into the furnace at a flow rate of 100mL / min.

[0102] (2) The wet zinc slag powder was mixed with 35% (wt.%) of coke and then fed into a high-temperature horizontal furnace through a sealed feeding port. After reduction for 90 minutes, the product was taken out and the zinc and lead content in the product was determined using an inductively coupled plasma-optical emission spectrometer (ICP-OES).

[0103] (3) The residual lead content in the slag phase after roasting was 1.3%, the zinc content was 2.16%, and the zinc recovery rate was 89.7%. X-ray diffraction (XRD) was performed on the slag phase, and the results are as follows: Figure 10 As shown. Figure 10 This indicates that the zinc- and lead-containing phases in the slag are ZnS and Pb, while the iron-containing phases are Fe2SiO4, FeO, FeS, and Fe.

[0104] Comparative Example 2

[0105] Compared to Example 1, only the particle size of the reactants in step (1) was changed, while the rest of the steps were the same as in Example 1. The zinc leaching slag sample was dried, crushed, ground into powder and sieved through a 400-mesh (38μm) sieve to obtain 100g of wet zinc smelting slag powder containing Zn, Fe, Pb, S, Si, Ca, and Cu of 18.3%, 25.3%, 5.53%, 4.9%, 7.3%, 1.9%, and 0.6% (wt.%), respectively. The remainder consisted of other oxide impurities. The mixture was added to the smelting furnace through a sealed feeding port 2.

[0106] Unreacted zinc leaching slag powder was collected from the side wall of the furnace. X-ray diffraction (XRD) analysis was performed on the powder, and the results are as follows: Figure 11 As shown; the main component of the powder is ZnFe2O4.

[0107] Due to the excessively fine particle size of the material, some unreacted zinc leaching slag particles were blown onto the furnace sidewall. After mixing and crushing the slag phase inside the furnace and the unreacted material particles on the furnace sidewall, the total zinc recovery rate was determined by ICP-OES to be 74.5%.

[0108] Comparative Example 3

[0109] Compared to Example 1, only the particle size of the reactants in step (1) was changed, while the rest of the steps were the same as in Example 1. The zinc leaching slag sample was dried and crushed to 8 mm to obtain 100 g of wet zinc smelting slag powder containing Zn, Fe, Pb, S, Si, Ca, and Cu of 18.3%, 25.3%, 5.53%, 4.9%, 7.3%, 1.9%, and 0.6% (wt.%), respectively, with the remainder being other oxide impurities. The mixture was added to the smelting furnace through the sealed feeding port 2.

[0110] The final zinc recovery rate was 53.7%. Slag phase was collected from slag outlet 4. After analysis, the main components of the slag phase were silicate oxides formed by unreacted ZnFe2O4 and Ca and Si. The zinc content in the slag phase was 11.3% and the lead content was 1.8% (Table 5).

[0111] Table 5. Surface scan total spectrum of the slag phase in Comparative Example 3

[0112]

[0113]

[0114] The slag phase was examined using a scanning electron microscope (SEM), and the results are as follows: Figure 12 As shown; SEM image of the slag phase ( Figure 12 The corresponding energy-dispersive X-ray spectroscopy (EDS) detection results are as follows: Figure 13 As shown. Combined with Figure 12 and Figure 13 It can be seen that the slag phase mainly consists of ZnFe2O4 and silicates.

[0115] Comparative Example 1 was a laboratory-simulated molten pool smelting reduction, with 35% coke added. After a reaction time of 90 minutes, the zinc recovery rate was 89.7%, and the generated ZnS was difficult to volatilize further. Comparative Example 2 involved grinding zinc leaching slag powder to 38 μm and then using CO plasma for injection reduction. During the reaction, due to the excessively fine particle size, some powder was blown to the side wall of the furnace and did not react completely, resulting in a decrease in the total zinc recovery rate. Comparative Example 3 involved crushing zinc leaching slag particles to 8 mm and then using CO plasma for injection reduction. During the reaction, due to the larger particle size, the particles were not completely reduced within the same reaction time, reducing the total zinc recovery rate.

[0116] In summary, the above-described technical solutions of the present invention are merely preferred embodiments of the present invention and do not limit the patent scope of the present invention. All equivalent structural transformations made using the contents of the present invention's specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A method for recovering metallic zinc from hydrometallurgical zinc slag, characterized in that, The process includes the following steps: providing wet zinc slag powder; feeding the wet zinc slag powder into a molten pool furnace, and blowing plasma-containing active substances from both sides of the molten pool furnace into the furnace to react and obtain zinc-containing vapor; wherein the source of the plasma-containing active substances includes N2, and one or more of CH4, CO, CO2 and carbon powder; capturing and recovering the zinc-containing vapor to obtain metallic zinc. The particle size range of the wet zinc slag powder is 47–5000 μm; The apparatus for recovering metallic zinc from hydrometallurgical zinc slag includes a molten pool furnace, a plasma generator, and a zinc condenser. The plasma generator is mounted on the side wall of the molten pool furnace; the zinc condenser is connected to the top of the molten pool furnace. The molten pool smelting furnace includes a furnace chamber, a sealed charging port, a recovery flue, and a slag discharge port; The sealed charging port and the recovery flue are respectively located at both ends of the top of the molten pool smelting furnace, and both the sealed charging port and the recovery flue are connected to the furnace chamber; The slag discharge port is located near the bottom of the molten pool furnace; The inner wall of the recovery flue near the furnace is provided with porous carbon material; the pore size of the porous carbon material is 20-100 mm; the height of the porous carbon material is 1-5 m; the end of the recovery flue away from the furnace is connected to the zinc condensation device; the number of plasma generating devices is not less than two; and the plasma-state active substances generated by the plasma generating devices are all ejected in the direction of being directed towards the bottom of the furnace.

2. The method for recovering metallic zinc from hydrometallurgical zinc slag according to claim 1, characterized in that, The plasma-state active material is a plasma torch generated by a plasma generator; and the power of the plasma torch is 300-500kW.

3. The method for recovering metallic zinc from wet zinc smelting slag according to claim 1, wherein the reaction time of the side-blown plasma active material step is 20-60 min.

4. The method for recovering metallic zinc from hydrometallurgical zinc slag according to claim 1, characterized in that, The wet zinc slag powder material comprises the following components by weight percentage: zinc 5-30 wt%, lead 1-10 wt%, iron 10-40 wt%, silicon 5-20 wt%, copper 0-3 wt%, sulfur 1-10 wt%, and calcium 0-5 wt%.

5. The method for recovering metallic zinc from hydrometallurgical zinc slag according to claim 1, characterized in that, The sources of the wet zinc slag powder include one or more of the following: intermediate leaching slag, acid leaching slag, goethite slag, iron alum slag, and lead-silver slag.

6. The method for recovering metallic zinc from hydrometallurgical zinc slag according to claim 1, characterized in that, In the side-blown plasma active material step, the side-blown gas flow rate required per kilogram of the wet zinc smelting slag powder is 10-100 L / min; the side-blown carbon powder required per kilogram of the wet zinc smelting slag powder is 0.15-0.25 kg.

7. The method for recovering metallic zinc from hydrometallurgical zinc slag according to claim 1, characterized in that, The collection and recovery method is liquid zinc rain spray collection; wherein, the temperature of the liquid zinc rain is 500-700℃.

8. The apparatus for recovering metallic zinc from hydrometallurgical zinc slag according to claim 1, characterized in that, The sidewall material of the molten pool furnace includes refractory bricks.

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