Reaction tank, nickel carbonate manufacturing method, and nickel smelting method

Abstract

To provide a reaction tank capable of producing nickel carbonate having a large particle diameter.SOLUTION: There is provided a reaction tank 1 which has a tank body 10, a stirring shaft 11 provided in the tank body 10, a vertical turbine blade 12 provided on the upper section of the stirring shaft 11, an inclined paddle blade 13 provided on the lower section of the stirring shaft 11, a drive unit 14 for rotating the stirring shaft 11 and a nickel solution supply pipe 15 for supplying a nickel solution to the tank body 10, a sodium carbonate supply pipe 16 for supplying sodium carbonate to the tank body 10. The discharge port of the nickel solution supply pipe 15 is arranged below the intermediate height between the vertical turbine blade 12 and the inclined paddle blade 13. The discharge port of the sodium carbonate supply pipe 16 is arranged above the vertical turbine blade 12.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a reaction vessel, a method for producing nickel carbonate, and a nickel smelting method. More specifically, the present invention relates to a reaction vessel for producing nickel carbonate by reacting an aqueous nickel solution with sodium carbonate, a method for producing nickel carbonate by reacting an aqueous nickel solution with sodium carbonate, and a nickel smelting method for smelting a nickel raw material and recovering nickel. [Background technology]

[0002] A known hydrometallurgical process for recovering nickel involves leaching a nickel raw material using the oxidizing power of chlorine, then going through a purification process to remove impurities from the resulting leachate, followed by an electrolysis process to recover electrolytic nickel.

[0003] In the electrolysis process, an aqueous solution of nickel chloride is fed to an electrolytic cell and electrowinning is carried out to produce electrolytic nickel. A portion of the electrolytic wastewater discharged from the electrolytic cell is used to produce nickel carbonate.

[0004] Patent Document 1 discloses that electrolytic wastewater (nickel chloride aqueous solution) and sodium carbonate are supplied to an agitation tank to produce nickel carbonate, and the slurry discharged from the agitation tank is subjected to solid-liquid separation into nickel carbonate and wastewater. Nickel carbonate is used as a neutralizing agent in the solution purification step of a hydrometallurgical process. Meanwhile, the wastewater is discharged outside the system. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Japanese Patent Application Laid-Open No. 2018-83747 Summary of the Invention [Problem to be solved by the invention]

[0006] The main component of nickel raw materials used in hydrometallurgical processes is nickel sulfide. However, depending on the source of the raw materials, nickel sulfate (NiSO4) may be present. When this type of nickel raw material is used, sulfate ions (SO4 2- ) increases, the following problems may occur in electrowinning carried out in a chloride bath: 1) There is an increased risk of appearance defects (pinholes) occurring in the electrolytic nickel. 2) The insoluble anode electrode deteriorates. 3) The electrolysis voltage increases, increasing power consumption.

[0007] Therefore, when the sulfate ion concentration in the electrolyte increases, the amount of sulfate ions discharged outside the system is increased to reduce the sulfate ion concentration in the electrolyte. Specifically, the amount of nickel carbonate produced using the electrolytic wastewater is increased to increase the amount of wastewater discharged. Since sulfate ions are discharged outside the system together with the wastewater, an increase in the amount of wastewater discharged also increases the amount of sulfate ions discharged outside the system.

[0008] However, nickel carbonate should essentially only be produced in the amount required as a neutralizing agent used in the hydrometallurgical process. Producing more nickel carbonate than necessary to increase the amount of sulfate ions discharged outside the system would result in an unnecessary increase in material costs (the cost of sodium carbonate and the cost of hydrochloric acid required to neutralize nickel carbonate).

[0009] Even if the slurry is subjected to solid-liquid separation in the nickel carbonate production process, moisture inevitably adheres to the nickel carbonate. If the dehydration efficiency of nickel carbonate can be improved, it is possible to increase the amount of wastewater discharged, i.e., the amount of sulfate ions discharged outside the system, while maintaining the production volume of nickel carbonate. One possible way to improve the dehydration efficiency of nickel carbonate is to increase the particle size of the nickel carbonate.

[0010] In view of the above circumstances, an object of the present invention is to provide a reaction vessel capable of producing nickel carbonate having a large particle size and a method for producing nickel carbonate. Another object of the present invention is to provide a nickel smelting method that is less likely to cause problems caused by sulfate ions during electrowinning even when using a nickel raw material containing nickel sulfate. [Means for solving the problem]

[0011] The reaction tank of the first invention is a reaction tank for producing nickel carbonate by reacting an aqueous nickel solution with sodium carbonate, and is characterized in that it comprises a tank body, an agitator shaft provided in the tank body, vertical turbine impellers provided on an upper section of the agitator shaft, inclined paddle impellers provided on a lower section of the agitator shaft, a drive unit for rotating the agitator shaft, a nickel aqueous solution supply pipe for supplying the nickel aqueous solution to the tank body, and a sodium carbonate supply pipe for supplying the sodium carbonate to the tank body, wherein the outlet of the nickel aqueous solution supply pipe is located below the midpoint between the vertical turbine impeller and the inclined paddle impeller, and the outlet of the sodium carbonate supply pipe is located above the vertical turbine impeller. The reaction vessel of the second invention is characterized in that, in the first invention, the outlet of the aqueous nickel solution supply pipe is disposed at the same height as the inclined paddle impeller. A method for producing nickel carbonate according to a third aspect of the present invention is characterized in that the nickel aqueous solution is reacted with the sodium carbonate using the reaction vessel according to the first or second aspect of the present invention to produce the nickel carbonate. A nickel smelting method of a fourth invention comprises: a leaching step of obtaining a crude nickel chloride aqueous solution by leaching a nickel raw material containing nickel sulfate; an oxidation neutralization step of removing impurities contained in the crude nickel chloride aqueous solution as a precipitate by an oxidation neutralization method; an electrolysis step of producing electrolytic nickel by electrowinning using, as an electrolyte, an aqueous nickel chloride solution obtained by purifying the crude nickel chloride aqueous solution; and a nickel carbonate production step of producing the nickel carbonate by the method of the third invention by reacting the electrolytic waste liquid discharged from the electrolysis step with the sodium carbonate, wherein in the nickel carbonate production step, a slurry containing the nickel carbonate is subjected to solid-liquid separation into the nickel carbonate and wastewater, the nickel carbonate is used as a neutralizing agent in the oxidation neutralization step, and the wastewater is discharged to the outside of the system. [Effects of the Invention]

[0012] According to the first invention, the liquid flow in the reaction vessel is separated into upper and lower parts with the vertical turbine blades as the boundary. Since the sodium carbonate supplied to the upper part of the flow and the aqueous nickel solution supplied to the lower part of the flow are mixed slowly, the generation of nickel carbonate nuclei is suppressed and the growth of particles is promoted. Therefore, nickel carbonate with a large particle size can be produced. According to the second invention, the nickel aqueous solution can be quickly diffused, thereby reducing the high concentration region of the nickel aqueous solution and further suppressing the generation of nickel carbonate nuclei. As a result, nickel carbonate with larger particle size can be produced. According to the third invention, nickel carbonate having a large particle size can be produced. According to the fourth aspect of the present invention, the amount of sulfate ions discharged to the outside of the system together with the wastewater can be increased, so the sulfate ion concentration in the electrolyte can be reduced, and problems caused by sulfate ions are less likely to occur in the electrolysis step. [Brief explanation of the drawings]

[0013] [Figure 1] 1 is an overall process diagram of a nickel smelting method. [Figure 2] FIG. 1 is an explanatory diagram of a nickel carbonate manufacturing facility. [Figure 3] FIG. 2 is a vertical cross-sectional view of a reaction tank. [Figure 4] Figure (A) shows the reactor configuration used in the simulation. Figure (B) shows the streamlines obtained by the simulation. Figure (C) shows the flow field obtained by the simulation. DETAILED DESCRIPTION OF THE INVENTION

[0014] Next, an embodiment of the present invention will be described with reference to the drawings. (Nickel smelting method) First, a nickel smelting method according to one embodiment of the present invention will be described with reference to FIG. The main component of nickel raw materials used in nickel smelting is nickel sulfide. 0 ) may be included. The nickel raw material may also include nickel sulfate (NiSO4). Nickel matte, nickel-cobalt mixed sulfide (MS: mixed sulfide), and sulfide raw material containing nickel sulfate can be used as the nickel raw material.

[0015] Nickel matte is obtained by pyrometallurgy. Specifically, nickel matte is obtained by smelting pyrite. The main components of nickel matte are trinickel disulfide (Ni3S2) and metallic nickel (Ni 0 )

[0016] Nickel-cobalt mixed sulfides are obtained by hydrometallurgy. Specifically, nickel oxide ores such as low-grade laterite ore and limonite ore are subjected to high-pressure acid leaching (HPAL). After impurities such as iron are removed from the leachate, hydrogen sulfide gas is blown into the leachate to produce nickel-cobalt mixed sulfides through a sulfurization reaction. The main component of nickel-cobalt mixed sulfides is nickel sulfide (NiS).

[0017] Nickel sulfate-containing sulfide raw materials include a mixture of nickel trisulfide (Ni3S4) and nickel sulfate (NiSO4 and its hydrates).

[0018] First, a slurry consisting of a portion of the nickel-cobalt mixed sulfide and the cementation residue described below is supplied to the chlorine leaching process where it is leached. In the chlorine leaching process, the oxidizing power of the chlorine gas blown into the leaching tank leaches virtually all of the metals contained in the solids in the slurry into the liquid. The slurry discharged from the chlorine leaching process is separated into a leachate and a leach residue. The leachate is a nickel chloride aqueous solution containing impurities (crude nickel chloride aqueous solution).

[0019] The nickel matte is crushed in the crushing process, then repulped to form matte slurry, which is then fed to the cementation process. The remainder of the nickel-cobalt mixed sulfide and the nickel sulfate-containing sulfide raw material are also fed to the cementation process. The leachate obtained in the chlorine leaching process is also fed to the cementation process. In addition to the target metals, nickel and cobalt, the leachate contains impurities such as copper, iron, lead, manganese, zinc, arsenic, and chromium.

[0020] The leachate contains divalent copper chloro complex ions. In the cementation process, the leachate is brought into contact with nickel matte, nickel-cobalt mixed sulfide, and nickel sulfate-containing sulfide raw material to cause a substitution reaction between copper and nickel. As a result, the nickel in the nickel matte, nickel-cobalt mixed sulfide, and nickel sulfate-containing sulfide raw material is leached into the solution, and the copper ions in the leachate are converted into copper sulfide (CuS) or metallic copper (Cu 0 The cementation residue obtained by solid-liquid separation is fed to the chlorine leaching process.

[0021] The chlorine leaching step and the cementation step correspond to the "leaching step" described in the claims.

[0022] The cementation end solution obtained from the cementation process is supplied to the iron removal process. In the iron removal process, an oxidizing agent and a neutralizing agent are added to the cementation end solution (crude nickel chloride aqueous solution) to cause an oxidation-neutralization reaction, immobilizing iron as hydroxide, which is then removed by solid-liquid separation using a filter. Here, chlorine gas, for example, is used as the oxidizing agent, and nickel carbonate slurry is used as the neutralizing agent. In the iron removal process, impurities contained in the cementation end solution, such as iron, arsenic, and chromium, are removed as precipitates.

[0023] The iron-removed final solution obtained from the iron removal step is supplied as an extraction starting solution to the solvent extraction step, where the cobalt contained in the extraction starting solution is separated by solvent extraction to obtain a crude nickel chloride aqueous solution (extraction residue) and a crude cobalt chloride aqueous solution.

[0024] The crude cobalt chloride solution undergoes a purification process to remove impurities and become a high-purity cobalt chloride solution. Electrolytic cobalt is produced by electrowinning using the high-purity cobalt chloride solution as the electrolyte.

[0025] The extraction residue is supplied to a deleading process, where the impurity lead is removed. In the deleading process, an oxidizing agent and a neutralizing agent are added to the extraction residue to cause an oxidation-neutralization reaction, immobilizing the lead as a precipitate and removing it by solid-liquid separation using a filter. Here, chlorine gas, for example, is used as the oxidizing agent. Nickel carbonate slurry is also used as the neutralizing agent. In the deleading process, impurities contained in the crude nickel chloride aqueous solution, such as lead, cobalt, iron, and copper, are removed as a precipitate. Note that under conditions that immobilize trace amounts of lead as a precipitate, nickel also easily precipitates. Therefore, the deleaded precipitate obtained in the deleading process is recycled as a nickel raw material.

[0026] The deleaded end solution obtained from the deleading step is supplied to the dezincing step, where trace amounts of zinc remaining in the deleaded end solution are removed by adsorption onto an anion exchange resin.

[0027] The high-purity nickel chloride aqueous solution obtained from the dezincification process is supplied as an electrolytic feed solution to the nickel electrolysis process, where electrolytic nickel is produced by electrowinning.

[0028] The electrolytic waste liquid (also called anolyte) discharged from the electrolytic cell in the nickel electrolysis process is an aqueous nickel chloride solution with a reduced nickel concentration. A portion of the electrolytic waste liquid is supplied to the nickel carbonate production process. The remainder of the electrolytic waste liquid is concentrated and then recycled to the electrolytic cell as an electrolytic feed liquid.

[0029] In the nickel carbonate manufacturing process, electrolytic wastewater (nickel chloride aqueous solution) is reacted with sodium carbonate to produce nickel carbonate. The slurry containing nickel carbonate is separated into nickel carbonate and wastewater. After repulping, the nickel carbonate is used as a neutralizing agent in the iron removal and lead removal processes. The wastewater is discharged outside the system.

[0030] The iron removal step and the lead removal step both correspond to the "oxidation neutralization step" described in the claims.

[0031] (Nickel carbonate manufacturing process) Next, the nickel carbonate manufacturing process will be described in detail. The nickel carbonate production process is carried out using nickel carbonate production equipment AA shown in Figure 2. The production equipment AA has a reaction vessel 1, a solid-liquid separator 2, and a thickener 3.

[0032] The nickel chloride aqueous solution and sodium carbonate are supplied to the reaction tank 1 and stirred. This causes the nickel chloride aqueous solution and sodium carbonate to react to produce nickel carbonate. The nickel chloride aqueous solution is the electrolytic wastewater from the nickel electrolysis process. Sodium carbonate may be supplied to the reaction tank 1 in powder form, but it is preferable to add a sodium carbonate aqueous solution prepared in advance. This improves the accuracy of addition and reaction control. The number of reaction tanks 1 may be one or more. Multiple reaction tanks 1 may be connected in series or in parallel.

[0033] The amount of sodium carbonate supplied to the reaction vessel 1 is adjusted so that the pH of the liquid phase of the slurry is 6 to 9, preferably 7. This is because nickel carbonate is stable as a solid in this pH range, and nickel carbonate can be produced efficiently.

[0034] The slurry discharged from the reaction vessel 1 is supplied to a solid-liquid separator 2. In the solid-liquid separator 2, the slurry is separated into nickel carbonate and a filtrate. Nickel carbonate is thereby obtained. The solid-liquid separator 2 is not particularly limited, but may be a centrifugal separator such as a decanter, a vacuum dehydrator such as an Oliver filter, or a pressure dehydrator such as a filter press.

[0035] The filtrate discharged from the solid-liquid separator 2 is supplied to the thickener 3. In the thickener 3, the nickel carbonate fine particles contained in the filtrate are allowed to settle. The underflow of the thickener 3 is supplied to the reaction vessel 1. The underflow contains nickel carbonate fine particles, and these fine particles are supplied to the reaction vessel 1.

[0036] The overflow from the thickener 3 is treated as wastewater. That is, the wastewater is treated and then discharged outside the system. The wastewater contains sulfate ions. Therefore, the sulfate ions can be discharged outside the system together with the discharge of the wastewater.

[0037] (Reaction tank) As shown in Figure 3, the reaction vessel 1 has a vessel body 10. The shape of the vessel body 10 is not particularly limited, but may be, for example, a vertical cylindrical shape. An agitator shaft 11 is provided along the central axis of the vessel body 10. A vertical turbine impeller 12 is provided on the upper section of the agitator shaft 11, and an inclined paddle impeller 13 is provided on the lower section. In other words, both the vertical turbine impeller 12 and the inclined paddle impeller 13 are provided on one agitator shaft 11. The vertical turbine impeller 12 is attached midway along the agitator shaft 11, and the inclined paddle impeller 13 is attached at the lower end of the agitator shaft 11.

[0038] A drive unit 14 is provided at the upper end of the agitation shaft 11. The agitation shaft 11 is rotated by the drive unit 14. The agitation shaft 11, vertical turbine blades 12, inclined paddle blades 13, and drive unit 14 constitute an agitator.

[0039] The reaction vessel 1 has a nickel aqueous solution supply pipe 15. The nickel aqueous solution supply pipe 15 is a pipe that supplies an aqueous nickel chloride solution to the inside of the vessel body 10. The outlet of the nickel aqueous solution supply pipe 15 is located below the intermediate height H between the vertical turbine blades 12 and the inclined paddle blades 13. Here, the height H is 1 / 2 of the height of the vertical turbine blades 12 with the inclined paddle blades 13 as the reference.

[0040] The reaction tank 1 has a sodium carbonate supply pipe 16. The sodium carbonate supply pipe 16 is a pipe that supplies sodium carbonate to the inside of the tank body 10. The outlet of the sodium carbonate supply pipe 16 is disposed above the vertical turbine impeller 12. The outlet of the sodium carbonate supply pipe 16 may be disposed above the liquid level. Alternatively, the outlet of the sodium carbonate supply pipe 16 may be disposed below the liquid level.

[0041] The reaction vessel 1 has a discharge pipe 17. The discharge pipe 17 is a pipe for discharging the nickel carbonate-containing slurry from the vessel body 10. The position of the discharge pipe 17 is not particularly limited. As shown in FIG. 3, the discharge pipe 17 may be attached to the lower part of the vessel body 10. The discharge pipe 17 may also be installed at the height of the liquid surface, allowing the slurry to be discharged by overflow. In this case, it is preferable to enclose the connection part of the discharge pipe 17 to the vessel body 10 with a hydrostatic tube. The hydrostatic tube is a cylindrical member that extends vertically along the inner wall surface of the vessel body 10 from the lower part of the vessel to above the liquid surface. The slurry flows into the hydrostatic tube from the lower end and is discharged from the discharge pipe 17. The presence of the hydrostatic tube can prevent short-pass discharge, in which the nickel chloride aqueous solution and sodium carbonate are discharged from the discharge pipe 17 in a short time while remaining unreacted or without nickel carbonate fine particles growing.

[0042] In Figure 3, the flow of liquid within the reaction vessel 1 is indicated by dashed arrows. The vertical turbine impeller 12 is a blade with multiple blades attached vertically to the edge of a horizontal disk. Therefore, the vertical turbine impeller 12 sucks in liquid from near the rotation axis and discharges it radially outward, forming a radial flow. On the other hand, the inclined paddle impeller 13 is a blade with multiple blades attached at an angle. The inclined paddle impeller 13 sucks in liquid from above and discharges it downward, forming a vertical convection current as well as a circumferential swirling flow.

[0043] When liquid is stirred by a mixer with vertical turbine impellers 12 on the upper level and inclined paddle impellers 13 on the lower level, the liquid flow in the reaction vessel 1 is separated into upper and lower sections with the vertical turbine impellers 12 as the boundary. This is because the vertical convection current formed by the inclined paddle impellers 13 on the lower level is blocked by the radial current formed by the vertical turbine impellers 12.

[0044] Sodium carbonate is supplied to the upper flow above the vertical turbine blades 12, and the nickel chloride aqueous solution is supplied to the lower flow below the vertical turbine blades 12. Since the mixing of the sodium carbonate supplied to the upper flow and the nickel chloride aqueous solution supplied to the lower flow proceeds slowly, the generation of nickel carbonate nuclei is suppressed and particle growth is promoted. As a result, nickel carbonate with a large particle size can be produced.

[0045] The outlet of the nickel aqueous solution supply pipe 15 is preferably positioned at the same height as the inclined paddle blades 13. In this case, it is also preferable that the outlet of the nickel aqueous solution supply pipe 15 is directed toward the inclined paddle blades 13. The vicinity of the inclined paddle blades 13 is a region where the liquid flow is fast. When the nickel chloride aqueous solution is supplied to this region, the nickel chloride aqueous solution is quickly diffused, and the high concentration region of the nickel chloride aqueous solution can be reduced. This makes it possible to further suppress the generation of nickel carbonate nuclei and produce nickel carbonate with larger particle sizes.

[0046] The underflow of the thickener 3 may be supplied to any position in the reaction vessel 1. That is, the underflow of the thickener 3 may be supplied to the flow above the vertical turbine impeller 12 or to the flow below it.

[0047] As the particle size of the nickel carbonate increases, the dehydration efficiency of the nickel carbonate by the solid-liquid separator 2 and the thickener 3 improves. Therefore, it is possible to increase the amount of wastewater discharged, i.e., the amount of sulfate ions discharged outside the system, while maintaining the production volume of nickel carbonate. Since the amount of sulfate ions discharged outside the system together with the wastewater can be increased, the sulfate ion concentration in the electrolyte can be reduced. Therefore, problems caused by sulfate ions are less likely to occur in the nickel electrolysis process.

[0048] From the viewpoint of producing nickel carbonate with large particle size, nickel carbonate may be produced using not only an aqueous solution of nickel chloride but also an aqueous solution of nickel such as nickel sulfate. [Example]

[0049] A mathematical analysis was used to simulate the flow of liquid inside a reactor. Figure 4(A) shows the configuration of the reactor used in the simulation. A six-blade vertical turbine impeller is installed on the upper level of the agitator shaft, and a six-blade inclined paddle impeller is installed on the lower level. The streamlines obtained by the simulation are shown in Figure 4(B), and the flow field is shown in Figure 4(C). As can be seen from the streamlines and flow field, the liquid flow inside the reactor is separated into upper and lower sections at the boundary of the vertical turbine impeller. [Explanation of symbols]

[0050] 1 Reaction vessel 10 Tank body 11 Agitator shaft 12 Vertical turbine blades 13 Inclined paddle blade 14 Drive unit 15 Nickel aqueous solution supply pipe 16 Sodium carbonate supply pipe 17 Discharge pipe

Claims

1. A reaction vessel for producing nickel carbonate by reacting an aqueous nickel solution with sodium carbonate, A tank body, a stirring shaft provided in the tank body; A vertical turbine blade provided on the upper stage of the stirring shaft; An inclined paddle blade provided at a lower stage of the stirring shaft; A drive unit that rotates the stirring shaft; a nickel aqueous solution supply pipe for supplying the nickel aqueous solution to the tank body; a sodium carbonate supply pipe for supplying the sodium carbonate to the tank body, an outlet of the nickel aqueous solution supply pipe is located below an intermediate height between the vertical turbine blades and the inclined paddle blades; The outlet of the sodium carbonate supply pipe is located above the vertical turbine blades. A reaction vessel characterized by:

2. The outlet of the nickel aqueous solution supply pipe is disposed at the same height as the inclined paddle blade.

2. The reaction vessel according to claim 1.

3. The nickel carbonate is produced by reacting the aqueous nickel solution with the sodium carbonate using the reaction vessel according to claim 1 or 2. A method for producing nickel carbonate, comprising:

4. a leaching step of leaching a nickel raw material containing nickel sulfate to obtain a crude nickel chloride aqueous solution; an oxidation neutralization step of removing impurities contained in the crude nickel chloride aqueous solution as a precipitate by an oxidation neutralization method; an electrolysis step of producing electrolytic nickel by electrowinning using an aqueous nickel chloride solution obtained by purifying the crude nickel chloride aqueous solution as an electrolyte; a nickel carbonate production step of producing the nickel carbonate by reacting the electrolytic waste solution discharged from the electrolysis step with the sodium carbonate by the method according to claim 3, In the nickel carbonate production step, a slurry containing the nickel carbonate is subjected to solid-liquid separation into the nickel carbonate and wastewater, The nickel carbonate is used as a neutralizing agent in the oxidation neutralization step, Discharge the wastewater outside the system A nickel smelting method characterized by the above.

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