Method for producing nickel or cobalt aqueous solution

Abstract

The present invention provides a method for producing an aqueous nickel or cobalt solution, comprising: (A) a leaching step including a first atmospheric pressure warming leaching step and a second atmospheric pressure warming leaching step for producing a leachate containing nickel, cobalt, and impurities by atmospheric pressure warming leaching; (B) a first extraction step of adding a first solvent extractant to the leachate and separating it into a first residual liquid containing nickel and impurities, and a first organic layer containing cobalt and impurities; (Ci) a precipitation removal step of adding a precipitating agent to the first residual liquid and precipitating and removing impurities including magnesium, calcium or a mixture thereof; and (Di) a target precipitation step of adding a neutralizing agent to the first residual liquid from which the impurities have been precipitated and removed, to selectively precipitate a nickel cake containing nickel.

Description

[Technical field]

[0001] The present invention relates to a method for producing an aqueous nickel or cobalt solution. More particularly, the present invention relates to a method for producing an aqueous nickel or cobalt solution that can be used to produce a positive electrode active material for a lithium ion secondary battery after recovering nickel and cobalt from raw materials. [Background technology]

[0002] To ionize nickel and cobalt from the raw material mixed hydroxide precipitate (MHP) cake containing nickel and cobalt mixed hydroxides, a one-stage atmospheric pressure heating reaction leaching process or a two-stage leaching process consisting of an atmospheric pressure heating reaction and a pressurized heating reaction has mainly been used.

[0003] However, in the case of the one-stage atmospheric heating reaction leaching process, there is a problem of a decrease in the recovery rate of Ni and Co. In the case of the two-stage leaching process consisting of atmospheric heating reaction and pressurized heating reaction, there are problems such as a reduction in the range of material choices due to erosion, corrosion and damage to the materials of the piping and reactor, as well as a decrease in competitiveness due to the required energy costs.

[0004] In addition, nickel and cobalt have been selectively recovered from ionized nickel and cobalt aqueous solutions using solvent extractants such as Ionquest 801, Cyanex 272, Versatic Acid 10, and LIX 84I. However, there is a risk of fire and explosion due to the use of organic solvents in the solvent extraction process, and the high unit price of the solvent extractant increases the production cost of high-purity nickel sulfate and cobalt sulfate, resulting in poor price competitiveness. Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention aims to recover nickel and cobalt from a raw material MHP cake containing nickel and cobalt mixed hydroxides to produce a high purity aqueous solution.

[0006] Another object of the present invention is to improve the recovery rate of nickel and cobalt by ionizing nickel and cobalt using a two-stage atmospheric warm leaching process, thereby reducing energy consumption.

[0007] In addition, the present invention aims to separate magnesium and calcium using sodium fluoride (NaF), a precipitant, in the process of producing a high-purity nickel aqueous solution, separate magnesium and manganese through the difference in solubility using sodium hydrogen sulfide (NaSH) in the process of producing a high-purity cobalt aqueous solution, and further separate impurities such as copper, magnesium, and manganese through the use of sodium hydrogen sulfide (NaSH) and sodium fluoride (NaF), etc., thereby reducing the solvent extraction process.

[0008] Since the solvent extraction process has the risk of fire and explosion due to the use of organic solvents, the present invention aims to minimize the solvent extraction process, thereby making it suitable for the operating environment as well as reducing the manufacturing costs of the final product. [Means for solving the problem]

[0009] One aspect of the present invention includes a method for producing a leachate containing nickel, cobalt, and impurities, comprising: (A) a leaching step including a first atmospheric pressure leaching step and a second atmospheric pressure leaching step, in which a raw material is leached at atmospheric pressure to produce a leachate containing nickel, cobalt, and impurities; (B) a first extraction step in which a first solvent extractant is added to the leachate to separate the leachate into a first residual liquid containing nickel and impurities, and a first organic layer containing cobalt and impurities; (Ci) a precipitation removal step in which a precipitating agent is added to the first residual liquid to precipitate and remove impurities containing magnesium, calcium, or a mixture thereof; and (Di) a target precipitation step in which a neutralizing agent is added to the first residual liquid from which the impurities have been precipitated and removed, to selectively precipitate a nickel cake containing nickel. The first atmospheric pressure heating leaching step is carried out at a temperature in the range of 50°C to 70°C, and the second atmospheric pressure heating leaching step is carried out at a temperature in the range of 80°C to 100°C. The present invention relates to a method for producing an aqueous nickel or cobalt solution.

[0010] Another aspect of the present invention is a method for producing a leaching solution containing nickel, cobalt, and impurities, comprising: (A) a leaching step including a first atmospheric pressure warming leaching step and a second atmospheric pressure warming leaching step for producing a leachate containing nickel, cobalt, and impurities by atmospheric pressure warming leaching of a raw material; (B) a first extraction step for adding a first solvent extractant to the leachate to separate the leachate into a first residual liquid containing nickel and impurities and a first organic layer containing cobalt and impurities; and (C-ii) a purification step for purifying impurities containing magnesium, manganese, zinc, copper, or a mixture thereof by adding a sulfuric acid solution to the first organic layer to produce a second residual liquid, and adding a sulfide to the second residual liquid to precipitate and recover a cobalt precipitate. The first atmospheric pressure heating leaching step is carried out at a temperature in the range of 50°C to 70°C, and the second atmospheric pressure heating leaching step is carried out at a temperature in the range of 80°C to 100°C. The present invention relates to a method for producing an aqueous nickel or cobalt solution.

[0011] According to an embodiment of the present invention, there is provided a method for producing a nickel or cobalt aqueous solution, wherein a pH of the residue of the second atmospheric pressure heating leaching step is lower than a pH of the residue of the first atmospheric pressure heating leaching step.

[0012] One embodiment of the present invention can provide a method for producing an aqueous nickel or cobalt solution, wherein a residual solution from the second atmospheric pressure warming leaching step is sent to the first atmospheric pressure warming leaching step.

[0013] In one embodiment of the present invention, there is provided a method for preparing a nickel or cobalt aqueous solution, wherein the first solvent extractant is Bis(2,4,4-trimethylpentyl)phosphinic acid.

[0014] In one embodiment of the present invention, there is provided a method for producing an aqueous nickel or cobalt solution, wherein the first extraction step is carried out at 40° C. under conditions of a pH greater than 5.0 and less than 5.4.

[0015] In one embodiment of the present invention, there is provided a method for preparing an aqueous nickel or cobalt solution, wherein the precipitant is sodium fluoride.

[0016] In one embodiment of the present invention, there is provided a method for producing an aqueous nickel or cobalt solution, wherein the precipitant is added in an amount of more than 2.0 equivalents and less than 2.4 equivalents of magnesium, calcium, or a mixture thereof.

[0017] In one embodiment of the present invention, there is provided a method for producing a nickel or cobalt aqueous solution, wherein the neutralizing agent is a basic substance containing sodium.

[0018] According to an embodiment of the present invention, there is provided a method for preparing an aqueous nickel or cobalt solution, wherein the pH of the first residual solution is 8 or more at 85° C. after the neutralizing agent is added.

[0019] According to an embodiment of the present invention, there may be provided a method for producing a nickel or cobalt aqueous solution, further comprising (Ei) a water washing step of washing the nickel cake with pure water.

[0020] In one embodiment of the present invention, there is provided a method for producing a nickel or cobalt aqueous solution, wherein the sulfide is sodium hydrosulfide (NaSH).

[0021] In one embodiment of the present invention, there may be provided a method for producing an aqueous nickel or cobalt solution, wherein the sulfide is added in an amount of more than 1.0 equivalent and less than 1.6 equivalents of cobalt and zinc.

[0022] According to an embodiment of the present invention, there may be provided a method for producing a nickel or cobalt aqueous solution, further comprising the step of (D-ii) removing copper after dissolving the cobalt precipitate in a sulfuric acid solution.

[0023] In one embodiment of the present invention, there is provided a method for producing a nickel or cobalt aqueous solution, wherein the copper removing step is performed by adding sodium hydrosulfide (NaSH) in an amount of more than 4.5 equivalents and less than 5.5 equivalents of copper.

[0024] According to an embodiment of the present invention, there may be provided a method for producing a nickel or cobalt aqueous solution, further comprising (E-ii) a second extraction step of adding a second solvent extractant to the aqueous solution from which copper has been removed to separate the aqueous solution into a third residual liquid containing cobalt and impurities and a second organic layer containing zinc and impurities.

[0025] In one embodiment of the present invention, there is provided a method for producing a nickel or cobalt aqueous solution, wherein the second solvent extractant is D2EHPA (Di-(2-ethylhexyl)phosphoric acid).

[0026] In one embodiment of the present invention, there is provided a method for producing an aqueous nickel or cobalt solution, wherein the second extraction step is carried out at 40° C. under conditions of pH greater than 2.4 and less than 3.2.

[0027] According to an embodiment of the present invention, there is provided a method for producing a nickel or cobalt aqueous solution, further comprising: (F) a precipitation removal step of introducing a precipitant into the third residual solution to precipitate and remove impurities including magnesium.

[0028] According to an embodiment of the present invention, there is provided a method for producing a nickel or cobalt aqueous solution, the method including: (G) adding a neutralizing agent to the third residual liquid from which the impurities have been precipitated and removed, thereby selectively precipitating a cobalt cake containing cobalt.

[0029] According to an embodiment of the present invention, there is provided a method for preparing an aqueous nickel or cobalt solution, wherein the pH of the third residual solution after the neutralizing agent is added is 8 or more at 85° C.

[0030] One embodiment of the present invention may provide a method for producing a nickel or cobalt aqueous solution, further comprising (H) a water washing step of washing the cobalt cake with pure water. Effect of the Invention

[0031] According to the present invention, the recovery rate of nickel and cobalt can be improved while reducing the amount of energy used by using a two-stage atmospheric pressure heating process.

[0032] In addition, by minimizing the solvent extraction process, which is one of the impurity refining processes and has the risk of fire and explosion due to the use of organic solvents, the operating environment is not only improved, but the manufacturing costs of the final product can also be reduced. [Brief description of the drawings]

[0033] [Figure 1] 1 is a diagram showing a two-stage leaching process and a first extraction process for producing an aqueous nickel or cobalt solution according to one embodiment of the present invention. [Diagram 2] 2 is a diagram showing a precipitation removal process and a target precipitation process for producing a nickel aqueous solution according to an embodiment of the present invention. [Diagram 3] 2 is a diagram showing an impurity purification process, a copper removal process, a second extraction process, a precipitation removal process, and a target product precipitation process for producing an aqueous cobalt solution according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0034] The embodiments of the present invention are illustrated for the purpose of explaining the technical idea of ​​the present invention, and the scope of the invention is not limited to the embodiments or the specific descriptions of the embodiments presented below.

[0035] The present invention will now be described with reference to the drawings.

[0036] Fig. 1 is a diagram showing a two-stage leaching process (S10) and a first extraction process (S20) for producing a nickel or cobalt aqueous solution according to an embodiment of the present invention. Fig. 2 is a diagram showing a precipitation removal process (S31) and a target product precipitation process (S32) for producing a nickel aqueous solution according to an embodiment of the present invention. Fig. 3 is a diagram showing an impurity purification process (S32, S42), a copper removal process (S62), a second extraction process (S72), a precipitation removal process (S82), and a target product precipitation process (S92) for producing a cobalt aqueous solution according to an embodiment of the present invention.

[0037] 1 to 3, a method for producing a nickel or cobalt aqueous solution that can be used to produce a positive electrode active material for a lithium secondary battery from a mixed hydroxide precipitate (MHP cake) through a series of steps can be provided. According to this method, it is possible to improve the operation stability and purity and reduce the production cost. Hereinafter, each step will be described in detail with reference to each drawing.

[0038] First, referring to FIG. 1, a leaching step (S10) can be performed in which a two-stage atmospheric heating leaching process is performed on an MHP cake to produce a leachate, and a first extraction step (S20) can be performed in which the leachate is separated into a first residual liquid containing nickel and impurities and a first organic layer containing cobalt and impurities.

[0039] <Leaching process (S10)> The leaching step (S10) is a step in which hydroxide-form MHP cake is dissolved in an acid solution such as sulfuric acid to ionize it and generate a leachate. The leaching step (S10) includes a first atmospheric pressure warming leaching step (S11) and a second atmospheric pressure warming leaching step (S12). The atmospheric pressure warming leaching step is a step in which an acid solution is prepared in an open reactor at a temperature of 100°C or less, raw materials are introduced into the reactor, and valuable metals are leached by the reaction according to the following reaction formula 1. The raw materials introduced here may be hydroxide-form MHP cake containing 40% by weight of nickel.

[0040] [Reaction Scheme 1] M(OH)2+H2SO4→MSO4+2H2O (M=metals such as Ni, Co, Mg)

[0041] The first atmospheric pressure heating leaching step (S11) and the second atmospheric pressure heating leaching step (S12) can be carried out in a two-stage apparatus, respectively, or can be carried out in a single pressurized apparatus by changing only the process conditions (e.g., temperature, pressure, or acidity).

[0042] Valuable metals can be leached from the raw material through the first atmospheric pressure heating leaching step (S11). For example, valuable metals such as nickel, cobalt, and manganese can be leached from the raw material. In addition, elements such as iron, copper, aluminum, zinc, and magnesium can be leached from the raw material. The first atmospheric pressure heating leaching step (S11) can be carried out for about 2 hours under temperature conditions ranging from 50°C to 70°C and pH conditions ranging from 2.7 to 3.3. By satisfying the temperature and pH ranges, high leaching efficiency can be obtained under optimal conditions.

[0043] The solid density of the raw material fed into the reactor in the first atmospheric pressure warm leaching step (S11) may be 100 g / L or more. For example, the solid density of the raw material may be in the range of 100 g / L to 200 g / L. In this case, the solid density is defined as the mass ratio of the raw material fed into the pressurizing device to the volume of the acid solution previously fed into the reactor. In other words, the solid density may be the mass ratio of the raw material fed per unit solvent, or the mass of the raw material per 1 L of solvent.

[0044] In the first atmospheric pressure warm leaching step (S11), the residual liquid is input to the first extraction step (S20), and the residue can be subjected to subsequent treatment in the second atmospheric pressure warm leaching step (S12).

[0045] In the second atmospheric pressure leaching step (S12), the leaching residue from the first atmospheric pressure leaching step (S11) can be leached for about 3 hours at a temperature in the range of 80° C. to 100° C. Other conditions for the second atmospheric pressure leaching step (S12) can be the same as those for the first atmospheric pressure leaching step (S11).

[0046] The pH of the residual liquid from the second atmospheric pressure heating leaching step (S12) may be lower than the pH of the residual liquid from the first atmospheric pressure heating leaching step (S11). By adjusting the pH, the leaching rate in each atmospheric pressure heating step can be increased. This allows the entire amount of valuable metals contained in the raw material to be leached. For example, nickel, cobalt, manganese, iron, copper, aluminum, zinc, magnesium, etc. contained in the raw material can be leached in their entirety.

[0047] In one embodiment, the residual liquor produced in the second atmospheric pressure warm leaching step (S12) can be sent to the first atmospheric pressure warm leaching step (S11) as shown in FIG.

[0048] In the case of the commonly used atmospheric leaching method, the reaction time must be maintained for 18 hours or more to increase the leaching rate of valuable metals. In this case, additional costs are incurred due to increased fuel and steam usage, and the productivity is low because the amount of raw material that can be processed per day is small. However, according to one embodiment of the present invention, by using an atmospheric warm leaching method consisting of two stages, it is possible to improve the recovery rate of nickel and cobalt while reducing energy usage. Therefore, production costs are reduced and productivity is improved.

[0049] The residue generated in the second atmospheric warming leaching step (S12) can be discarded, as shown in FIG.

[0050] <1st extraction step (S20)> The first extraction step (S20) is a step of selectively separating or extracting nickel from the leachate of an aqueous solution of nickel and cobalt ionized through the two-stage atmospheric pressure heating leaching step using a first solvent extractant.

[0051] Here, the first solvent extractant is not particularly limited as long as it has a low nickel loading rate, and may be, for example, Bis(2,4,4-trimethylpentyl)phosphinic acid (Cyanex272).

[0052] When the first solvent extractant is added to the leachate, nickel is not loaded into the first solvent extractant but distributed into the first raffinate, and cobalt and other impurities (Mg, Mn, Zn, etc.) are distributed into the organic layer together with the first solvent extractant and can be separated or extracted. Such separation or extraction can occur according to the reactions shown in the following Reactions 2 and 3. Here, the reaction shown in Reaction 3 is a reaction for neutralizing H2SO4 generated by Reaction 2 to maintain the pH.

[0053] [Reaction Scheme 2] 2HR(org)+MSO4(aq)→MR2(org.)+H2SO4(aq.) (R=Ni, etc., M=Co, Mg, Mn, etc.) [Reaction Scheme 3] H2SO4+Na2CO3→Na2SO4+H2O+CO2

[0054] The first extraction step can be carried out under conditions of more than 5.0 and less than 5.4 at 40° C. By satisfying the pH range under the above temperature conditions, the loading rate of cobalt and impurities can be increased, and nickel can be efficiently separated into the residual liquid.

[0055] In one embodiment, the ratio of the first solvent extractant (O) to the aqueous solution (A) can be adjusted according to the concentration of the extracted components in the liquid. For example, the ratio of the first solvent extractant (O) to the aqueous solution (A) (O:A) can be in the range of 0.5:1 to 2:1. For example, O:A can be 1.5:1.

[0056] Next, referring to FIG. 2, a precipitation removal step (S31) for precipitating and removing impurities from the first residual liquid after the first extraction step (S11), a target precipitation step (S41) for selectively precipitating a nickel cake containing high-purity nickel, and a final leaching step for producing a high-purity nickel aqueous solution can be carried out.

[0057] <Precipitation removal step (S31)> The precipitation removal step (S31) can be performed to remove impurities such as magnesium, calcium, or a mixture thereof remaining in the first residual liquid. After the precipitation removal step (S31), the first residual liquid can be sent to a target precipitation step (S41).

[0058] For example, in the precipitation removal step (S31), a remover can be added to the liquid. The remover is not particularly limited as long as it can react with magnesium or calcium to form a precipitate, and may be, for example, sodium fluoride (NaF).

[0059] For example, magnesium and calcium can be precipitated as magnesium fluoride or calcium fluoride through a reaction such as that shown in Reaction Scheme 4 below.

[0060] For example, the precipitation removal step (S31) is carried out at a reaction temperature in the range of 50° C. to 70° C. for about 2 hours or more, whereby only magnesium and calcium can be separated through selective precipitation while reducing nickel precipitation in the residual liquid.

[0061] [Reaction Scheme 4] MSO4+2NaF=MF2+Na2SO4(M=Mg, Ca)

[0062] In one embodiment, sodium fluoride may be dosed at greater than 2.0 equivalents (eq) of the magnesium, calcium, or mixture thereof content, while in another embodiment, sodium fluoride may be dosed at less than 2.4 equivalents (eq) of the magnesium, calcium, or mixture thereof content.

[0063] <Target product precipitation step (S41)> In the target product precipitating step (S41), a neutralizing agent can be added to the first residual liquid after the precipitate removing step (S31).

[0064] For example, the neutralizing agent may be a basic substance that contains sodium. For example, the neutralizing agent may be sodium carbonate (Na2CO3).

[0065] After removing impurities such as magnesium and calcium, in the target precipitation step (S41), nickel can be precipitated in the form of a cake through the reaction shown in Reaction Scheme 5 below.

[0066] [Reaction Scheme 5] 3NiSO4+3Na2CO3+2H2O=NiCO3·2Ni(OH)2+3Na2SO4+3CO2

[0067] The target product precipitation step (S41) may be carried out under conditions of a pH of 8 or higher and a temperature in the range of 80° C. to 90° C. for 4 hours or longer.

[0068] Since nickel can be recovered through the target precipitation process (S41), the amount of expensive organic solvents that pose a risk of explosion and fire can be reduced, thereby improving operational stability and productivity and reducing production costs.

[0069] Although not specifically shown in the drawing, sodium components may be present in the precipitated nickel cake, so the water-soluble sodium components can be removed by a subsequent washing process using pure water. The sodium components removed here can be reused to produce sodium carbonate (Na2CO3), a neutralizing agent, thereby reducing production costs.

[0070] <Final leaching process (S51)> The final leaching step (S51) is a step in which components such as sodium in the produced nickel cake are washed away with water, and then the cake is dissolved in a sulfuric acid solution to produce a high-purity nickel aqueous solution.

[0071] In the final leaching step (S51), the nickel cake can be put into a solution in which sulfuric acid is mixed with pure water at an acidity of 150 g / L to 200 g / L. Nickel, cobalt and trace impurities contained in the nickel cake can be dissolved in the sulfuric acid solution. The nickel cake is reacted with the aqueous sulfuric acid solution until the pH becomes 2.0. In one embodiment, the reaction can be carried out for 4 hours or more in the final leaching step (S51) at a pH in the range of 1.0 to 3.0 and at a temperature in the range of 50°C to 70°C.

[0072] Next, referring to FIG. 3, the following steps may be performed: a second residual liquid production step (S32) of adding a sulfuric acid solution to the first organic layer that has been subjected to the first extraction step (S11); a purification step (S42) of precipitating and recovering the cobalt precipitate in the second residual liquid to purify the impurities; a step (S52) of dissolving the recovered cobalt precipitate again in the sulfuric acid solution; a copper removal step (S62) of removing copper by adding sodium hydrogen sulfide; a second extraction step (S72) of separating the aqueous solution from which copper has been removed into a third residual liquid containing cobalt and impurities, and a second organic layer containing zinc and impurities; a precipitation removal step (S82) of precipitating and removing impurities in the third residual liquid; a target precipitation step (S92) of selectively precipitating a cobalt cake containing high-purity cobalt; and a final leaching step (S102) of producing a high-purity aqueous cobalt solution.

[0073] <Second residual liquid production process (S32)> The second residual liquid producing step (S32) is a step of introducing a sulfuric acid solution into the first organic layer containing cobalt and impurities to strip the cobalt into the sulfuric acid solution.

[0074] Stripping is a process in which sulfuric acid and the loaded cobalt are reacted to produce a stripping residue containing cobalt, and the loaded impurities are recovered in an aqueous solution.

[0075] <Purification process (S42)> The purification step (S32) is a step for selectively recovering only cobalt from the second residual liquid obtained by stripping. S31) is that the target cobalt can be recovered in the form of a precipitate in the purification step (S32).

[0076] For example, the purification step (S32) may involve introducing a sulfide into the liquid to produce a cobalt precipitate. For example, the sulfide may be sodium hydrogen sulfide (NaSH), and cobalt may be precipitated and recovered in the form of sulfide by the reactions shown in Reactions 6 and 7 below.

[0077] [Reaction Scheme 6] CoSO4+2NaSH→2CoS+Na2SO4+H2SO4 [Reaction Scheme 7] H2SO4+Na2CO3→Na2SO4+H2O+CO2

[0078] For example, the purification step (S32) can be carried out at a reaction temperature in the range of 70° C. to 90° C. while maintaining a pH of 4.5 to 5.0 for about 3 hours or more.

[0079] In the above pH range, the solubility of CoS and ZnS is very low at 0.1 mg / L or less, and the solubility of MgS and MnS is very low. Therefore, by adjusting the pH range, it is possible to separate only cobalt and zinc through selective precipitation, and refine magnesium and manganese.

[0080] In one embodiment, the sulfide may be introduced at a content of greater than 1.0 equivalent and less than 1.6 equivalents of cobalt and zinc content.

[0081] <Sulfuric acid solution manufacturing process (S52)> In the sulfuric acid solution preparation step (S52), a precipitate containing cobalt is dissolved in a sulfuric acid solution to prepare an aqueous solution.

[0082] For example, the sulfuric acid solution preparation step (S52) can be carried out according to the reaction shown in Reaction Scheme 8 below.

[0083] [Reaction Scheme 8] CoS+H2SO4+1 / 2O2→CoSO4+H2O+S

[0084] For example, in the sulfuric acid solution producing step (S52), the solid density (S / D) of the precipitate in the sulfuric acid solution during the production of the aqueous solution may be 100 g / L or more.

[0085] For example, the sulfuric acid solution producing step (S52) can be carried out at a reaction temperature in the range of 80° C. to 100° C. for about 20 hours or more.

[0086] <Copper removal process (S62)> The copper removal process (S62) is a process in which sodium hydrogen sulfide (NaSH) is added to the liquid to remove copper (Cu) from the liquid. Copper can be precipitated as copper sulfide (CuS) through the following reaction in Reaction Scheme 9.

[0087] [Reaction Scheme 9] 2CuSO4+2NaSH=2CuS+Na2SO4+H2SO4

[0088] Copper sulfide (CuS) can precipitate at a pH of 1.0 or higher. For this reason, the pH of the solution in the copper removal step (S62) can be maintained at 1.0 to 2.5. In one embodiment, the pH of the solution in the copper removal step (S62) can be maintained at 1.0 to 1.5. If the pH of the solution is less than 1.0, it is difficult to remove copper in the solution to 20 mg / L or less, and if the pH is more than 2.5, the solubility of cobalt in sulfuric acid decreases, which can result in a loss of cobalt.

[0089] On the other hand, sodium hydrosulfide (NaSH) can be added slowly to avoid a sudden change in the pH of the solution. For example, the leachate can be stirred and sodium hydrosulfide (NaSH) added over a period of about 3 hours. This prevents a sudden increase in pH in some areas of the solution, which would increase the rate of cobalt loss.

[0090] In one embodiment, sodium hydrosulfide (NaSH) can be added at more than 4.5 equivalents (eq) and less than 5.5 equivalents (eq) of copper content. If the amount of sodium hydrosulfide (NaSH) added is 4.5 equivalents (eq) or less, the copper removal rate is 95% or less, making it difficult to sufficiently remove copper from the solution. If the amount of sodium hydrosulfide (NaSH) added is 5.5 equivalents (eq) or more, the cobalt removal rate is 0.05% or more, so the cobalt recovery rate may be low.

[0091] The copper removal process (S62) is carried out at a reaction temperature of 50°C to 70°C for 3 hours or more to reduce the amount of cobalt precipitate in the residual liquid, and only copper can be separated through selective precipitation. Sodium hydrogen sulfide products with concentrations of 30wt% to 70wt% can be used.

[0092] <Second extraction step (S72)> The second extraction step (S72) is a step in which a second solvent extractant is added to the liquid to separate it into a third residual liquid containing cobalt and impurities, and a second organic layer containing zinc and impurities.

[0093] Here, the second solvent extractant is not particularly limited as long as it has a low cobalt loading rate, and may be, for example, D2EHPA (Di-(2-ethylhexyl)phosphoric acid).

[0094] When the second solvent extractant is added to the liquid, cobalt is not loaded into the second solvent extractant but distributed to the third residual liquid (raffinate), and zinc, magnesium, manganese, etc. are distributed to the organic layer together with the second solvent extractant and can be separated or extracted. Such separation or extraction can occur according to the reaction shown in Reaction Scheme 10 below.

[0095] [Reaction Scheme 10] 2HR(org.)+ZnSO4(aq.)→ZnR2(org.)+H2SO4(aq.)(R=Co etc.)

[0096] The second extraction step (S72) may be carried out at 40° C. for about 10 minutes or more under conditions of a pH greater than 2.4 and less than 3.2. By satisfying the pH range under the above temperature conditions, the loading rate of impurities such as zinc is increased and the loading rate of cobalt is decreased, so that cobalt can be efficiently separated into the residual liquid.

[0097] In one embodiment, the ratio of the second solvent extractant (O) to the aqueous solution (A) can be adjusted according to the concentration of the component to be extracted in the liquid. For example, the ratio of the second solvent extractant (O) to the aqueous solution (A) (O:A) can be in the range of 0.5:1 to 2:1. For example, O:A can be 1.5:1.

[0098] <Precipitation removal step (S82)> The precipitation removal step (S82) can be carried out to remove impurities such as magnesium remaining in the third residual liquid. S After step S82), the third residual liquid can be sent to the target product precipitation step (S92).

[0099] Details regarding the precipitation removal step (S82) can be understood by referring to the contents explained above regarding the precipitation removal step (S31).

[0100] <Target product precipitation step (S92)> In the target product precipitating step (S92), a neutralizing agent can be added to the third residual liquid after the precipitate removing step (S82).

[0101] For example, the neutralizing agent may be a basic substance that contains sodium. For example, the neutralizing agent may be sodium carbonate (Na2CO3).

[0102] After removing impurities such as magnesium, in the target precipitation step (S41), nickel can be precipitated in the form of a cake through the reaction shown in Reaction Scheme 11 below.

[0103] [Reaction Scheme 11] 3CoSO4+3Na2CO3+2H2O=CoCO3·2Co(OH)2+3Na2SO4+3CO2

[0104] The target product precipitation step (S92) may be carried out under conditions of a pH of 8 or more and a temperature in the range of 80° C. to 90° C. for 4 hours or more.

[0105] Since cobalt can be recovered through the target precipitation process (S92), the amount of expensive organic solvents that pose a risk of explosion and fire can be reduced, thereby improving operational stability and productivity and reducing production costs.

[0106] Although not specifically shown in the drawing, sodium components may be present in the precipitated cobalt cake, and the sodium components, which are water-soluble, can be removed by a subsequent washing step using pure water. The removed sodium components can be reused to produce sodium carbonate (Na2CO3), a neutralizing agent, thereby reducing production costs.

[0107] <Final leaching process (S102)> The final leaching step (S102) is a step in which components such as sodium in the produced cobalt cake are washed away with water, and then the cake is dissolved in a sulfuric acid solution to produce a high-purity aqueous cobalt solution.

[0108] Details regarding the final leaching step (S102) can be understood by referring to the description of the final leaching step (S51) above.

[0109] <Experimental Example> (1) Quality of the MHP cake raw material used in the experiment [Table 1] *Contents not shown in the table are impurities (mostly present with hydroxyl groups attached)

[0110] (2) Metal content of the leachate after a leaching process including a two-stage atmospheric heating leaching process [Table 2]

[0111] Comparing Tables 1 and 2, it was confirmed that the nickel and cobalt contents of the leachate after the two-stage atmospheric heating leaching process were increased. (3) Comparison of cobalt content in the organic layer depending on pH conditions during the extraction process

[0112] To determine the optimal pH conditions for loading cobalt and impurities (Mg, Mn, Zn, etc.) into the organic layer using Cyanex272 (30%) and separating nickel into the raffinate, an aqueous solution, the loading rates of each component in the organic layer were compared at pH 5.0, 5.2, and 5.4. The reaction was carried out at 40°C for 10 minutes, with an organic layer to aqueous solution ratio of 1.5:1. The loading rates were expressed as the relative ratio of the content in the organic layer to the content in the leachate for each component.

[0113] [Table 3]

[0114] Referring to Table 3 above, it was found that the difference between the Co content and Ni content loaded in the organic layer was the largest under the condition of pH 5.2, and separation of Co and Ni occurred most frequently.

[0115] It was confirmed that at pH 5.0, the Ni content loaded in the organic layer was low, but the Co loading was relatively poor, and at pH 5.4, the Co loading was excellent, but the Ni separation was relatively poor.

[0116] (4) Comparison of impurity (Mg, Ca) content in residual liquid depending on the amount of sodium fluoride added in the precipitation removal process

[0117] In order to determine the optimal amount of sodium fluoride (NaF) to be added to precipitate and remove impurities (Mg, Ca) from the residual liquid, 2.0, 2.2, and 2.4 equivalents of Mg and Ca were added to the residual liquid to compare the impurity (Mg, Ca) contents. The reaction was carried out at 60°C for 2 hours.

[0118] [Table 4]

[0119] Referring to Table 4, it was confirmed that the total content of Mg and Ca in the residual liquid was the smallest when 2.2 equivalents were added.

[0120] (5) Comparison of metal (Co, Cu, Zn, Mn, Mg) content in cobalt cake depending on the amount of sodium hydrogen sulfide (NaSH) added in the impurity purification process The cobalt loaded in the organic layer by Cyanex272 was stripped with a sulfuric acid solution, and to determine the optimal conditions for precipitating and recovering cobalt in the form of sulfide using sodium hydrogen sulfide (NaSH), the amount of NaSH added was 1.0, 1.3, and 1.6 equivalents of cobalt and zinc, and the contents of the precipitated cake were compared. The reaction was carried out for 3 hours at 85℃ and pH 4.5~5.0.

[0121] [Table 5]

[0122] Referring to Table 5, it can be seen that when 1.3 equivalents of NaSH were added, the cobalt content in the cake was high, and even if more than 1.3 equivalents of NaSH were added, the cobalt content did not increase any further.

[0123] (6) Comparison of copper removal rates depending on the amount of sodium hydrogen sulfide (NaSH) added in the copper removal process Cobalt precipitate was dissolved in sulfuric acid solution, and then NaSH was added to the cobalt aqueous solution to determine the optimal conditions for precipitating and removing copper in the form of CuS. NaSH was added in amounts of 4.5, 5.0, and 5.5 equivalents of copper content, and the copper removal rates were compared. The reaction was carried out for 3 hours at 60℃ and pH 1.0. The removal rates were shown by comparing the content of each component in the aqueous solution before and after the addition of NaSH.

[0124] [Table 6]

[0125] Referring to Table 6, it was confirmed that the Cu removal rate was highest when NaSH was added at 5.0 equivalents.

[0126] (7) Comparison of cobalt content in the organic layer depending on pH conditions during the extraction process To determine the optimal pH conditions for loading and separating zinc from an aqueous solution of cobalt, from which cobalt had been precipitated, into an organic layer using the solvent extractant D2EHPA (30%), the loading rates of the components were compared at pH 2.4, 2.8, and 3.2. The reaction was carried out at 40°C for 10 minutes with a ratio of organic layer to aqueous solution of 1.5:1.

[0127] [Table 7]

[0128] Referring to Table 7, it was shown that the difference between the Zn content and the Co content loaded in the organic layer was the largest under the condition of pH 2.8, and it was confirmed that separation of Co and Zn occurred most frequently.

[0129] It was confirmed that at pH 2.4, the Co loading content in the organic layer was low, but the Zn loading was relatively poor, and at pH 3.2, the Zn loading was excellent, but the Co separation was relatively poor.

[0130] (8) Metal content of nickel and cobalt aqueous solution after final water washing process to remove impurities [Table 8]

[0131] [Table 9]

[0132] By comparing Table 2 with Tables 8 and 9, it can be confirmed that the purity of the aqueous nickel and cobalt solutions that have been subjected to the process of the present invention is increased. Although the embodiments of the present invention have been described above with reference to the accompanying drawings, it should be understood by those skilled in the art to which the present invention pertains that the present invention may be embodied in other specific forms without changing the technical concept or essential characteristics thereof.

[0133] Therefore, it should be understood that the above-described embodiments are illustrative in all respects and are not limiting. The scope of the present invention is defined by the claims rather than the detailed description, and all modifications and alterations derived from the meaning and scope of the claims and their equivalents should be interpreted as being included in the scope of the present invention.

Claims

1. (A) a leaching step including a first atmospheric pressure warming leaching step and a second atmospheric pressure warming leaching step for leaching a raw material at atmospheric pressure to produce a leachate containing nickel, cobalt, and impurities; (B) a first extraction step of adding a first solvent extractant to the leaching solution to separate the leaching solution into a first residual solution containing nickel and impurities and a first organic layer containing cobalt and impurities; (C-i) a precipitation removal step of introducing a precipitant into the first residual liquid to precipitate and remove impurities including magnesium, calcium, or a mixture thereof; and (D-i) a target precipitation step of selectively precipitating a nickel cake containing nickel by adding a neutralizing agent to the first residual liquid from which the impurities have been precipitated and removed; The first atmospheric warming leaching step is carried out at a temperature in the range of 50°C to 70°C, The method for producing an aqueous nickel or cobalt solution, wherein the second atmospheric warming leaching step is carried out at a temperature in the range of 80°C to 100°C.

2. (A) a leaching step including a first atmospheric pressure warming leaching step and a second atmospheric pressure warming leaching step for leaching a raw material at atmospheric pressure to produce a leachate containing nickel, cobalt, and impurities; (B) a first extraction step in which a first solvent extractant is added to the leachate to separate it into a first residual liquid containing nickel and impurities and a first organic layer containing cobalt and impurities; and (C-ii) a purification step of purifying impurities including magnesium, manganese, zinc, copper, or a mixture thereof by introducing a sulfuric acid solution into the first organic layer to produce a second residual liquid, and introducing a sulfide into the second residual liquid to precipitate and recover a cobalt precipitate; The first atmospheric warming leaching step is carried out at a temperature in the range of 50°C to 70°C, The method for producing an aqueous nickel or cobalt solution, wherein the second atmospheric warming leaching step is carried out at a temperature in the range of 80°C to 100°C.

3. 3. The method for producing a nickel or cobalt aqueous solution according to claim 1, wherein the pH of the effluent from the second atmospheric pressure heating leaching step is lower than the pH of the effluent from the first atmospheric pressure heating leaching step.

4. 3. The method for producing a nickel or cobalt aqueous solution according to claim 1, wherein a residual solution from the second atmospheric pressure heating leaching step is sent to the first atmospheric pressure heating leaching step.

5. The method for producing a nickel or cobalt aqueous solution according to claim 1 or 2, wherein the first solvent extractant is bis(2,4,4-trimethylpentyl)phosphinic acid.

6. The method for producing an aqueous nickel or cobalt solution according to claim 1 or 2, wherein the first extraction step is carried out at 40° C. and at a pH of more than 5.0 and less than 5.

4.

7. The method for producing an aqueous nickel or cobalt solution according to claim 1, wherein the precipitating agent is sodium fluoride.

8. The method for producing an aqueous nickel or cobalt solution according to claim 1, wherein the precipitant is added in an amount of more than 2.0 equivalents and less than 2.4 equivalents of magnesium, calcium or a mixture thereof.

9. The method for producing an aqueous nickel or cobalt solution according to claim 1 , wherein the neutralizing agent is a basic substance containing sodium.

10. 2. The method for producing a nickel or cobalt aqueous solution according to claim 1, wherein the pH of the first residual solution is 8 or more at 85° C. after the neutralizing agent is added.

11. The method for producing an aqueous nickel or cobalt solution according to claim 1, further comprising (E-i) a water washing step of washing the nickel cake with pure water.

12. The method for producing a nickel or cobalt aqueous solution according to claim 2, wherein the sulfide is sodium hydrogen sulfide (NaSH).

13. The method for producing an aqueous nickel or cobalt solution according to claim 2, wherein the sulfide is added at a content of more than 1.0 equivalent and less than 1.6 equivalent of cobalt and zinc content.

14. The method for producing a nickel or cobalt aqueous solution according to claim 2, further comprising the step of (D-ii) removing copper after dissolving the cobalt precipitate in a sulfuric acid solution.

15. The method for producing a nickel or cobalt aqueous solution according to claim 13, wherein the copper removing step is carried out by adding sodium hydrogen sulfide (NaSH) in an amount of more than 4.5 equivalents and less than 5.5 equivalents of copper.

16. (E-ii) A second extraction step of adding a second solvent extractant to the aqueous solution from which copper has been removed, and separating the aqueous solution into a third residual liquid containing cobalt and impurities and a second organic layer containing zinc and impurities. The method for producing the nickel or cobalt aqueous solution according to claim 14.

17. The method for producing a nickel or cobalt aqueous solution according to claim 16, wherein the second solvent extractant is D2EHPA (Di-(2-ethylhexyl) phosphoric acid).

18. The method for producing an aqueous nickel or cobalt solution according to claim 16, wherein the second extraction step is carried out at 40°C under conditions of a pH greater than 2.4 and less than 3.

2.

19. The method for producing a nickel or cobalt aqueous solution according to claim 16, further comprising: (F) a precipitation and removal step of introducing a precipitant into the third residual liquid to precipitate and remove impurities including magnesium.

20. 20. The method for producing a nickel or cobalt aqueous solution according to claim 19, further comprising: (G) adding a neutralizing agent to the third residual liquid from which the impurities have been precipitated and removed, thereby selectively precipitating a cobalt cake containing cobalt.

21. The method for producing a nickel or cobalt aqueous solution according to claim 20, wherein the pH of the third residual solution is 8 or more at 85° C. after the neutralizing agent is added.

22. The method for producing a nickel or cobalt aqueous solution according to claim 20, further comprising: (H) a water washing step of washing the cobalt cake with pure water.

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