Method for preparing nickel sulfate aqueous solution from nickel-containing raw material

Abstract

This document provides a method for preparing an aqueous solution of nickel sulfate, comprising: (Ai) a reduction heat treatment process for heat-treating a first raw material containing nickel and lithium; (B) a first leaching process for leaching the heat-treated product produced by the reduction heat treatment process; (A-ii) a calcination process for heat-treating a second raw material containing nickel and sulfur; (C) a second leaching process for leaching a first leaching residue produced by the first leaching process and a calcined material produced by the calcination process; (D) a neutralization process for neutralizing a second leaching solution produced by the second leaching process; and (E) a solvent extraction process for refining nickel in the neutralized solution produced by the neutralization process.

Description

Technical Field

[0001] This disclosure relates to a method for preparing an aqueous nickel sulfate solution from a nickel-containing raw material. More particularly, this disclosure relates to a method for preparing a high-purity aqueous nickel sulfate solution from a nickel-containing raw material, wherein the high-purity aqueous nickel sulfate solution can be applied in a variety of different fields (especially as a precursor material for positive electrode active materials in lithium batteries). [ ] Prior Technology

[0002] Nickel can be recovered from a variety of raw materials such as metallic nickel, nickel matte, nickel concentrate, and nickel-containing process byproducts. Generally, it is known that among various forms of recovered nickel, aqueous solutions of nickel sulfate preferably contain 110 g / L or higher of nickel, while impurities may be present in amounts of several hundred mg / L or less.

[0003] Conventionally, a high-purity nickel sulfate aqueous solution is produced by leaching with an inorganic acid under atmospheric pressure, neutralizing with sodium hydroxide or sodium carbonate, and removing impurities.

[0004] However, this conventional method is disadvantageous because only a limited number of raw materials dissolve in a specific inorganic acid. In the conventional method, after sludge filtration, substances used as neutralizing agents (such as sodium) are removed by washing with water. This sodium removal method increases wastewater volume and requires significant processing time, leading to reduced productivity and increased wastewater treatment costs. [ ] [ ] Summary of the Invention

[0005] This disclosure aims to provide a comprehensive method for preparing a high-purity nickel sulfate aqueous solution from nickel-containing composite raw materials, which is a hybrid process combining dry metallurgy and wet metallurgy techniques, wherein the reaction can be appropriately carried out according to the nickel-containing raw materials.

[0006] This disclosure also provides an economical and environmentally friendly method for recycling process byproducts.

[0007] Furthermore, this disclosure aims to provide an environmentally friendly method that selectively segregates lithium, converts complex compounds into single compounds, and recovers inorganic acids from harmful gases through dry metallurgical-type pretreatment.

[0008] Furthermore, this disclosure aims to provide an economical and environmentally friendly method that minimizes the inflow of impurities from precipitants or secondary raw materials, reduces additional wastewater treatment costs by using wet metallurgical processes including solvent extraction, and reduces the consumption of auxiliary materials through recycling the process solution.

[0009] The various specific examples disclosed herein relate to a method for preparing an aqueous solution of nickel sulfate, comprising: (Ai) a reduction heat treatment process for heat-treating a first raw material containing nickel and lithium; (B) a first leaching process for leaching the heat-treated product produced by the reduction heat treatment process; (A-ii) a calcination process for heat-treating a second raw material containing nickel and sulfur; (C) a second leaching process for leaching the first leaching residue produced by the first leaching process and the calcined material produced by the calcination process; (D) neutralization for neutralizing the second leaching solution (leached solution) produced by the second leaching process; and (E) a solvent extraction process for refining nickel in the neutralized solution produced by the neutralization process.

[0010] In the method for preparing an aqueous nickel sulfate solution according to a specific example of this disclosure, the first raw material and the second raw material may each independently contain at least one of the group consisting of oxides, hydroxides, sulfides and sulfur oxides, wherein the oxides, hydroxides, sulfides and sulfur oxides each independently contain ore, matte, black mass (BM), black powder (BP), mixed hydroxide precipitate (MHP), mixed carbonate precipitate (MCP), mixed sulfide precipitate (MSP), or a mixture thereof.

[0011] In a specific example of the method for preparing an aqueous solution of nickel sulfate according to the present disclosure, the first raw material may contain nickel in the form of nickel oxide or a nickel metal composite oxide.

[0012] In a specific example of the method for preparing an aqueous solution of nickel sulfate according to this disclosure, the second raw material may comprise nickel in the form of nickel sulfide.

[0013] In the method for preparing an aqueous nickel sulfate solution according to a specific example of this disclosure, the reduction heat treatment process can be carried out at 650 to 950°C by introducing the first raw material into a heat treatment apparatus and injecting nitrogen gas.

[0014] In a specific example of the method for preparing an aqueous solution of nickel sulfate according to the present disclosure, a first leaching process may be performed using a first leaching agent comprising an inorganic acid, water, or a mixture thereof.

[0015] In a specific example of the method for preparing an aqueous solution of nickel sulfate according to the present disclosure, the solution obtained by the first leaching process contains lithium, and the first leaching residue may contain nickel.

[0016] In the method for preparing an aqueous nickel sulfate solution according to a specific example of this disclosure, the roasting process can be carried out at 650 to 950°C by introducing a second raw material into a heat treatment apparatus and injecting oxygen.

[0017] In the method for preparing an aqueous nickel sulfate solution according to a specific example of this disclosure, in the second leaching process, the first leaching residue and the calcined material can be leached separately in an atmospheric pressure reactor and a high-temperature and high-pressure reactor.

[0018] In a method for preparing an aqueous solution of nickel sulfate according to a specific example of this disclosure, a second leaching process may be performed using a second leaching agent comprising an inorganic acid, or a mixture of an inorganic acid and water.

[0019] In the method for preparing an aqueous nickel sulfate solution according to a specific example of this disclosure, a second leaching process can be carried out at a temperature of 150 to 250°C and a pressure of 800 to 4300 kPa.

[0020] In the method for preparing an aqueous solution of nickel sulfate according to a specific example of this disclosure, a second leaching process can be carried out in an environment with an acidity of 100 to 200 g / L.

[0021] In the method for preparing an aqueous solution of nickel sulfate according to a specific example of this disclosure, a neutralization process may be carried out using a neutralizing agent including MHP, MCP, nickel hydroxide (Ni(OH)2), nickel carbonate (NiCO3), sodium hydroxide (NaOH), sodium carbonate (Na2CO3), calcium hydroxide (Ca(OH)2), magnesium hydroxide (Mg(OH)2), calcium oxide (CaO), magnesium oxide (MgO), or mixtures thereof.

[0022] In the method for preparing an aqueous solution of nickel sulfate according to a specific example of this disclosure, the neutralization process can be carried out at 80°C and a pH of 2 to 4.5.

[0023] In the method for preparing an aqueous nickel sulfate solution according to a specific example of this disclosure, the neutralization can be carried out for 2 hours or longer, and the neutralized solution produced by the neutralization process has a residual acidity of 10 g / L or less.

[0024] In a specific example of the method for preparing an aqueous solution of nickel sulfate according to the present disclosure, the solvent extraction process may include: (Ei) a first solvent extraction process for refining nickel from a neutralized solution produced by a neutralization process; and (Eii) a second solvent extraction process for refining nickel from a first extracted solution produced by the first solvent extraction process.

[0025] In a method for preparing an aqueous solution of nickel sulfate according to a specific example of the present disclosure, the first solvent extraction procedure may be performed by the following steps: (i) a first loading procedure for loading nickel into an organic phase by adding a first organic extractant to the aqueous solution of nickel sulfate; (ii) a first extraction procedure for back-extracting nickel into an aqueous phase by adding the first loaded organic extractant to a neutralized solution; (iii) a first washing procedure for recovering cobalt into an aqueous phase by adding an inorganic extractant to the first extracted organic extractant; (iv) a first stripping procedure for recovering copper into an aqueous phase by adding an inorganic extractant to the first washed organic extractant; or a combination thereof.

[0026] In a method for preparing an aqueous nickel sulfate solution according to a specific example of this disclosure, the aqueous nickel sulfate solution may be prepared using a first organic extractant in a first filling process at a volume ratio of 3.5 to 6.5.

[0027] In the method for preparing an aqueous solution of nickel sulfate according to a specific example of this disclosure, after the solution produced by the first filling process can be precipitated, the precipitated nickel-containing byproduct can be used as a neutralizing agent in the neutralization process.

[0028] In the method for preparing an aqueous nickel sulfate solution according to a specific example of this disclosure, an organic extractant at a volume ratio of 1.5 to 4.5 after the first filling can be used on the neutralized solution in the first extraction process.

[0029] In the method for preparing an aqueous nickel sulfate solution according to a specific example of this disclosure, the volume ratio of the inorganic extractant to the organic extractant in the first washing procedure and the first stripping procedure can each be in the range of 9.5 to 12.5.

[0030] In the method for preparing an aqueous solution of nickel sulfate according to a specific example of this disclosure, a first washing procedure may be performed at a pH of 2 to 3.

[0031] In the method for preparing an aqueous solution of nickel sulfate according to a specific example of this disclosure, the first stripping procedure may be carried out at a pH of 0.5 to 1.5.

[0032] In the method for preparing an aqueous solution of nickel sulfate according to a specific example of this disclosure, the first stripped organic extractant may be used as the first organic extractant.

[0033] In a specific example of the method for preparing an aqueous nickel sulfate solution according to the present disclosure, the method may further include a first precipitation process for recovering cobalt by adding a first precipitant to a first washed solution produced by a first washing process.

[0034] In a specific example of the method for preparing an aqueous solution of nickel sulfate according to the present disclosure, the method may further include a second precipitation process for recovering copper by adding a second precipitant to a first stripped solution produced by the first stripping process.

[0035] In a method for preparing an aqueous solution of nickel sulfate according to a specific example of the present disclosure, the second solvent extraction procedure may be performed by the following steps: (i) a second loading procedure for loading nickel into the organic phase by adding a second organic extractant to the aqueous solution of nickel sulfate; (ii) a second extraction procedure for back-extracting nickel into the aqueous phase by adding the second loaded organic extractant to the solution after the first extraction; (iii) a second stripping procedure for recovering impurities into the aqueous phase by adding an inorganic extractant to the second extracted organic extractant; or a combination thereof.

[0036] In the method for preparing an aqueous nickel sulfate solution according to a specific example of this disclosure, a second organic extractant with a volume ratio of 4.5 to 8.5 may be used for the aqueous nickel sulfate solution in the second filling process.

[0037] In the method for preparing an aqueous solution of nickel sulfate according to a specific example of this disclosure, after precipitating the second-filled solution produced by the second filling process, the precipitated nickel-containing byproduct can be used as a neutralizing agent in the neutralization process.

[0038] In the method for preparing an aqueous nickel sulfate solution according to a specific example of this disclosure, in the second extraction process, a second loaded organic extractant at a volume ratio of 0.3 to 1.5 may be used on the solution after the first extraction.

[0039] In the method for preparing an aqueous nickel sulfate solution according to a specific example of this disclosure, in the second stripping process, an organic extractant with a volume ratio of 3.5 to 7.5 can be used for the inorganic extractant.

[0040] In the method for preparing an aqueous nickel sulfate solution according to a specific example of this disclosure, a second stripping procedure may be performed at a pH of 0.25 to 1.5.

[0041] In the method for preparing an aqueous solution of nickel sulfate according to a specific example of this disclosure, a second stripped organic extractant may be used as a second organic extractant.

[0042] According to this disclosure, high-purity nickel sulfate aqueous solutions can be prepared from a variety of different nickel-containing raw materials.

[0043] According to this disclosure, heat treatment in a reduction heat treatment process enables the selective leaching and recovery of lithium from lithium-containing raw materials with strong chemical bonds therein.

[0044] According to this disclosure, by using a roasting process, various nickel-containing raw materials with different forms of chemical bonding are transformed into a single phase, ensuring uniformity in subsequent processes. This allows the process to be flexibly adapted to the rapidly changing nickel raw material market, thus improving the applicability of the entire process.

[0045] According to this disclosure, process byproducts can be used as neutralizing agents in neutralization processes to prevent the inflow of impurities from commonly used neutralizing agents or precipitants, thereby increasing the concentration of the target metallic nickel.

[0046] According to this disclosure, nickel sulfate can be appropriately used as a precursor material for positive electrode active materials in lithium secondary batteries. Simple Explanation of the Diagram

[0047] [Figure 1] is a diagram illustrating the entire procedure for preparing an aqueous solution of nickel sulfate according to a specific example of this disclosure.

[0048] [Figure 2] is a diagram illustrating the first solvent extraction procedure between the various procedures for preparing an aqueous solution of nickel sulfate according to a specific example.

[0049] [Figure 3] is a diagram illustrating the second solvent extraction process between the various procedures for preparing an aqueous solution of nickel sulfate according to a specific example. Implementation

[0050] The specific examples in this disclosure are provided to illustrate the technical concepts disclosed herein. The scope of the claims under this disclosure is not limited to the specific examples presented below or their detailed descriptions.

[0051] The specific examples in this disclosure are provided to illustrate the technical concepts disclosed herein. The scope of the claims under this disclosure is not limited to the specific examples presented below or their detailed descriptions.

[0052] In this document, unless otherwise specified, "%" is understood to be based on weight (wt).

[0053] The following diagrams illustrate this disclosure.

[0054] Figure 1 is a diagram showing the entire procedure for preparing an aqueous nickel sulfate solution according to a specific example of the present disclosure. Figures 2 and 3 are diagrams illustrating the first and second solvent extraction procedures between the procedures for preparing an aqueous nickel sulfate solution according to the specific example.

[0055] Referring to Figures 1 to 3, a method can be provided for recovering high-purity nickel through a series of processes and for producing an aqueous nickel solution using, for example, smelted nickel. This method can enhance the versatility, operational stability, and purity of various raw materials and products, while reducing manufacturing costs. Each process will be described in detail below with reference to the figures.

[0056] [raw material]

[0057] As starting materials, the first and second raw materials may each consist primarily of a nickel-containing composite material. The starting materials may each independently include at least one material selected from the group consisting of oxides, hydroxides, sulfides, and sulfates. For example, these oxides, hydroxides, sulfides, and sulfates may independently include concentrates, ore, black matter (BM), black powder (BP), mixed hydroxide precipitates (MHP), mixed carbonate precipitates (MCP), mixed sulfide precipitates (MSP), or mixtures thereof.

[0058] For example, the first raw material may include black substance (BM), black powder (BP), mixed hydroxide precipitate (MHP), mixed carbonate precipitate (MCP), or mixtures thereof. In addition to containing nickel (Ni) and lithium (Li), the first raw material may also contain impurities such as iron (Fe), cobalt (Co), copper (Cu), zinc (Zn), magnesium (Mg), sodium (Na), silicon (Si), or combinations thereof. For example, the composition of the first raw material as shown in Table 1 can be provided. The first raw material may contain nickel in the form of nickel oxide (NiO) or a nickel metal composite oxide mixture of nickel and other metals.

[0059] Table 1

[0060] (Unit: wt%) [ ] [ ]

[0061] The second raw material may include concentrate, ore, mixed sulfide precipitates, or a mixture thereof. For example, in addition to nickel (Ni) and sulfides (S), the second raw material may also contain impurities such as iron (Fe), cobalt (Co), copper (Cu), zinc (Zn), magnesium (Mg), sodium (Na), silicon (Si), or combinations thereof. For instance, the composition of the second raw material may be as shown in Table 2. The second raw material may contain nickel in the form of nickel sulfide (NiS).

[0062] Table 2

[0063] (unit: wt%)

[0064] [Reduction Heat Treatment Procedure] [(S10)] [ ]

[0065] A reduction heat treatment process (S10) can be performed as a pre-processing step for the first raw material.

[0066] In the reduction heat treatment process (S10), a first raw material containing nickel and lithium in the form of a complex oxide that can combine with various metals can be heat-treated in a reducing environment. This treatment can cause a phase transformation into oxides and / or carbonates, transforming the lithium-containing compound into a substance with high solubility in water or inorganic acids.

[0067] Thus, before proceeding to the first leaching process (S20) for leaching / extracting lithium, which will be described later, the leaching efficiency of the first leaching process (S20) for leaching / extracting lithium can be improved by changing the compound form of the first raw material containing lithium through the reduction heat treatment process (S10).

[0068] For example, heat treatment equipment such as an electric furnace (e.g., a box furnace) or a rotary kiln can be used to perform a reduction heat treatment process (S10).

[0069] According to one specific example of this disclosure, a reduction heat treatment process (S10) can be performed by introducing a first raw material into a heat treatment apparatus and injecting nitrogen gas at a temperature of 650 to 950°C. For example, a specific amount of the first raw material can be loaded into the heat treatment apparatus, and sufficient nitrogen gas (N2 gas) can be injected simultaneously to maintain a reducing environment, allowing reduction heat treatment to be performed at 650 to 950°C. In this process, not only lithium but other metals can react, undergoing a phase transformation according to [Reaction Formula 1]. Furthermore, further reactions occur through [Reaction Formula 2] and [Reaction Formula 3].

[0070] [Reaction Formula 1]

[0071] 9LiNi1 / 3Co1 / 3Mn1 / 3O2 + 0.25C → 3NiO+3MnO2 + Co3O4 + 4.5Li2O + 0.25CO2(g)

[0072] [Reaction 2]

[0073] 4MnO2 + C → 2Mn2O3 + CO2(g)

[0074] [Reaction 3]

[0075] Li₂O + CO₂(g) → Li₂CO₃

[0076] [First filtration process] [(S20)]

[0077] In the first leaching process (S20), nickel- and lithium-containing raw materials can be leached, which have undergone phase transformation by the reduction heat treatment process (S10).

[0078] Following the reduction heat treatment process (S10), a first leaching process (S20) may be performed. For example, the first leaching process (S20) may be performed in a wet mill. The wet mill may be a ball mill, rod mill, bead mill, friction mill, etc. The first leaching process may use a first leaching agent (e.g., inorganic acid, water, or a mixture thereof) to selectively leach the treated lithium.

[0079] In one specific example, the inorganic acid may be at least one selected from the group consisting of sulfuric acid (H2SO4), hydrochloric acid (HCl), and nitric acid (HNO3). An inorganic acid diluted with water may be used. Sulfuric acid produced by capturing sulfur dioxide gas generated in a subsequent roasting process (S30) may be used.

[0080] In one specific example, water can be used as the first leaching agent. In this case, the first leaching solution can be prepared by leaching lithium from the lithium-containing raw material into lithium hydroxide (LiOH) form via [Reaction 4]. The first leaching solution may contain lithium.

[0081] [Reaction 4] Li₂CO₃ + 2H₂O → 2LiOH + H₂O + CO₂

[0082] In one specific example, non-lithium metals may be retained in the residue. For example, metals such as nickel (Ni), cobalt (Co), and manganese (Mn) may be retained in the residue and included in the first leaching residue.

[0083] The lithium concentration in the first leaching solution obtained from the first leaching process can be approximately 0.1 to 8.5 g / L. This leaching solution can be processed into lithium hydroxide monohydrate (LiOH·H2O), lithium carbonate (Li2CO3), lithium phosphate (Li3PO4), etc., through known precipitation and crystallization methods, for use as raw materials in the positive electrode of lithium-ion batteries.

[0084] MHP and MCP (which contain Ni, Co, Mn, and possibly Li) produced in the lithium-ion battery recycling process can be used as the first raw material for the first leaching process.

[0085] [Roasting Process] [(S30)]

[0086] A roasting process (S30) can be performed as a pre-processing step for the second raw material.

[0087] In the roasting process (S30), a phase transition can occur in nickel-containing raw materials bonded in various compounds, accompanied by the recycling of sulfur dioxide gas (SO2 gas) generated during the heat treatment process for the manufacture of inorganic acids.

[0088] Prior to the roasting process (S30), the nickel-containing second raw material may be in sulfide form, which can be converted into oxide by the roasting process (S30). Directly leaching the nickel-containing second raw material in its sulfide state results in low leaching efficiency due to the generation of hydrogen sulfide gas (H2S gas) and metal redeposition reactions. Therefore, converting the nickel-containing second raw material into a compound form through the roasting process (S30) prior to the second leaching process (S40) can improve the leaching efficiency in the second leaching process (S40). For this purpose, heat treatment equipment such as an electric furnace (box furnace) or a rotary kiln can be used for the roasting process (S30).

[0089] According to a specific example disclosed herein, the roasting process (S30) may include loading a specific amount of nickel-containing raw material into an electric furnace, injecting sufficient oxygen (O2) for conversion into nickel oxide, and roasting at 650 to 950°C. During the process, not only nickel but also other impurities may react, undergoing phase transformation through the reaction described in [Reaction Formula 5] below. Furthermore, the sulfur dioxide gas generated during the roasting process (S30) may be captured by various collection facilities and converted into sulfuric acid (H2SO4) by mixing with water, which can then be used in a subsequent leaching process.

[0090] [Reaction 5] 2NiS + 3O2 → 2NiO + 2SO2

[0091] [Second filtration process] [(S40)] [ ]

[0092] In the second leaching process (S40), the calcined residue (calcined material) that has undergone phase transformation through the calcination process (S30) can be leached, along with the first leaching residue retained in the residue from the first leaching process (S20). The second leaching process (S40) can be performed after both the calcination process (S30) and the first leaching process. In the second leaching process, the calcined residue can be leached in a high-temperature, high-pressure reactor, while the first leaching residue can be leached in an atmospheric pressure reactor. In the second leaching process (S40), a second leaching agent (e.g., an inorganic acid, or a mixture of an inorganic acid and water) can be used to complete the leaching. In one specific example, an inorganic acid can be used for the second leaching process (S40). For example, at least one inorganic acid may be used, which is selected from the group consisting of sulfuric acid (H2SO4), hydrochloric acid (HCl), and nitric acid (HNO3), inorganic acids diluted with water, or sulfuric acid produced by capturing sulfur dioxide gas generated in the previous roasting process (S30).

[0093] In one specific example, sulfuric acid can be used as the second leaching agent. At this point, nickel can be leached from the first leaching residue and the roasted residue containing nickel in the form of nickel sulfate (NiSO4) to produce a second leaching solution according to [Reaction 6].

[0094] [Reaction 6] NiO + H2SO4 → NiSO4 + H2O

[0095] The second leaching process (S40) can be carried out at a temperature of approximately 150 to 250°C and a pressure of 800 to 4300 kPa. The saturated vapor pressure caused by the high reaction temperature can lead to the maintenance of a certain level of pressure, and additional pressure can be applied for complete reaction.

[0096] For example, the second leaching process (S40) can be carried out in an environment with an acidity of 100 to 200 g / L. The second leaching process (S40) is carried out in an acidic environment with a low pH to ensure sufficient second leaching solution, followed by a subsequent neutralization process (S50).

[0097] In one specific example, not only nickel can be leached, but other impurities can also be leached together. For example, impurities such as iron (Fe), cobalt (Co), copper (Cu), and zinc (Zn) can be leached along with nickel and included in the second filtrate.

[0098] The nickel concentration in the second leaching solution obtained from the second leaching process (S40) may be about 45 to 105 g / L, and the residual acidity may be 10 to 80 g / L.

[0099] [Neutralization Procedure] [(S50)]

[0100] In the neutralization process (S50), the second filtrate produced by the second leaching process (S40) can be neutralized. After the second leaching process (S40), the neutralization process (S50) can be performed.

[0101] If the second leachate is produced in a high pH environment, the volume of the second leachate produced can be reduced.

[0102] In one specific example, after a second leaching process (S40) is carried out in an acidic environment with low pH to ensure sufficient second leaching liquid, a neutralization process (S50) can be performed.

[0103] In the neutralization process (S50), a neutralizing agent may be introduced to increase the pH of the second filtrate produced in the second leaching process (S40). A neutralizing agent may also be added in preparation for a subsequent solvent extraction process.

[0104] In one specific example, the neutralizing agent may be at least one selected from the group consisting of nickel-containing byproducts (MHP, MCP), nickel hydroxide (Ni(OH)2), nickel carbonate (NiCO3), sodium hydroxide (NaOH), sodium carbonate (Na2CO3), calcium hydroxide (Ca(OH)2), magnesium hydroxide (Mg(OH)2), calcium oxide (CaO), and magnesium oxide (MgO).

[0105] The reason for using MHP and MCP as raw materials and neutralizing agents is that hydroxides and carbonates generally have high solubility in acid even without calcination, thus eliminating the need for processing under expensive high-temperature and high-pressure leaching conditions. They can also consume the acid (H2SO4) remaining after the second leaching process (S40), thus preparing them in advance for purification processes (S60) that occur in the high pH range.

[0106] In one specific example, the neutralization process (S50) can use a nickel-containing byproduct in the form of a wet cake as a neutralizing agent. When using a nickel-containing byproduct, the amount of neutralizing agent that needs to be added separately can be reduced, thus saving costs, since the byproduct is generated in the process. In addition, the introduction of additional impurities can be prevented, and the nickel concentration in the neutralized solution can be increased.

[0107] In one specific example, a neutralization process (S50) can be carried out at 80°C and a pH of approximately 2 to 4.5. During the process, some impurities, including iron (Fe) and aluminum (Al), can be removed by precipitation.

[0108] In one specific example, the neutralization process (S50) can be carried out for at least 2 hours, and the residual acidity of the neutralized solution produced by this process can be 10 g / L or lower. For example, the neutralization process (S50) can be carried out for up to 10 hours.

[0109] [Solvent Extraction Procedure] [(S60)]

[0110] In the solvent extraction process (S60), nickel can be refined from the neutralized solution produced by the neutralization process (S50). The solvent extraction process (S60) can be performed after the neutralization process (S50).

[0111] In one specific example, the solvent extraction process (S60) may include a first solvent extraction process (S70) for refining nickel from the neutralized solution produced by the neutralization process (S50); and a second solvent extraction process for refining nickel from the first extracted solution produced by the first solvent extraction process.

[0112] [First Solvent Extraction Procedure] [(S70)]

[0113] In the first solvent extraction process (S70), nickel can be refined from the neutralized solution produced by the neutralization process (S50). The neutralized solution can be a neutralized leaching solution. The first solvent extraction process (S70) can be a process for refining nickel by removing impurities from the neutralized solution produced in the neutralization process (S50), wherein an organic extractant (first organic extractant) can be used.

[0114] The first solvent extraction process (S70) may include a first loading process (S71), a first extraction process (S72), a first washing process (S73), and a first stripping process (S74). The organic extractant may be at least one selected from the group consisting of di-2-ethylhexyl phosphate, mono-2-ethylhexyl (ethylhexyl) phosphate, and bis(2,4,4-trimethylpentyl) phosphinic acid.

[0115] [First loading procedure] [(S71)]

[0116] The first loading procedure (S71) may be a procedure for increasing the nickel concentration in the organic phase. The first loading procedure (S71) may involve using an aqueous nickel sulfate solution and a first organic extractant to load the nickel contained in the aqueous nickel sulfate (NiSO4) solution into the first organic extractant, thereby transferring the nickel to the organic phase.

[0117] In the first filling process (S71), the volume ratio of the first organic extractant (organic phase) to the aqueous nickel sulfate solution (aqueous phase) can be 3.5 to 6.5. If the volume ratio of the organic phase to the aqueous phase in the first filling process (S71) is less than 3.5, the binding of the target metal (nickel) and the organic extractant may be incomplete, resulting in a low extraction ratio (e.g., 85% or less). If the volume ratio of the organic phase to the aqueous phase in the first filling process (S71) exceeds 6.5, the cost of the process may increase due to excessive use of the first organic extractant.

[0118] The first filling procedure (S71) can be carried out in a pH range of 4.5 to 6.0, and at least one of the group consisting of sodium hydroxide (NaOH) and sodium carbonate (Na2CO3) can be used to adjust the pH range.

[0119] In the process of mixing an aqueous phase and an organic phase to extract nickel into the organic phase, phase separation can be achieved by the difference in specific gravity between the organic and aqueous phases. Through phase separation, a first-fill solution (aqueous phase) can be obtained. The first-fill solution can be a nickel-containing aqueous solution in which most of the nickel has been extracted, having a nickel content of 0.1 to 4.5 g / L.

[0120] After the solution is precipitated following the first filling, the precipitated nickel-containing byproduct can be used as a neutralizing agent in the neutralization process (S50). For example, precipitating agents such as sodium hydroxide (NaOH) and sodium carbonate (Na2CO3) can be used to precipitate nickel-containing byproducts such as nickel hydroxide (Ni(OH)2) and nickel carbonate (NiCO3).

[0121] [First Extraction Procedure] [(S72)] [ ]

[0122] In the first extraction process (S72), mixing the neutralized solution with the nickel-containing first-filled organic extractant removes impurities contained in the neutralized solution, while simultaneously enriching nickel in the neutralized solution. The first extraction process (S72) can be performed after the first filling process (S71). In the first extraction process (S72), the first-filled organic extractant can be used to remove impurities.

[0123] In the first extraction process (S72), the volume ratio of the first loaded organic extractant (organic phase) to the neutralized solution (aqueous phase) can be in the range of 1.5 to 4.5. If the volume ratio of the organic phase to the aqueous phase is less than 1.5 in the first extraction process (S72), the extraction efficiency of impurities may decrease (e.g., less than 75%). If the volume ratio of the organic phase to the aqueous phase exceeds 4.5 in the first extraction process (S72), the residual nickel in the organic phase may increase, thus reducing the process efficiency. The pH range of the first extraction process (S72) can be approximately 3.5 to 5.0.

[0124] When nickel is back-extracted into the aqueous phase by mixing the aqueous and organic phases, phase separation can be achieved by the difference in specific gravity between the organic and aqueous phases. Through phase separation, a solution (aqueous phase) after the first extraction can be obtained. The solution after the first extraction can be an aqueous solution containing nickel as the main component, wherein the nickel content is in the range of 75 to 110 g / L.

[0125] [First Washing Program] [(S73)] [ ]

[0126] In the first washing process (S73), by mixing the organic and inorganic extractants after the first extraction, cobalt (Co), magnesium (Mg), manganese (Mn), and other impurities contained in the organic extractant after the first extraction can be recovered into the aqueous phase. After the first extraction process (S72), the first washing process (S73) can be performed.

[0127] Inorganic extractants can be inorganic acids, water, or mixtures thereof.

[0128] In the first washing process (S73), the volume ratio of the organic extractant (organic phase) to the inorganic extractant (aqueous phase) after the first extraction can be between 9.5 and 12.5. If the volume ratio of the organic phase to the aqueous phase exceeds 12.5 in the first washing process (S73), the cobalt recovery rate may decrease (e.g., less than 65%). If the volume ratio of the organic phase to the aqueous phase is less than 9.5 in the first washing process (S73), the cobalt recovery rate may increase, but the process cost may increase due to the unnecessary use of the inorganic extractant. The pH range of the first washing process (S73) can be approximately 2.0 to 3.0.

[0129] When impurities (including cobalt) are back-extracted into the aqueous phase by mixing the aqueous and organic phases, phase separation is achieved by the difference in specific gravity between the organic and aqueous phases. Through phase separation, a solution (aqueous phase) after the first washing is obtained. The solution after the first washing can be an aqueous solution containing cobalt as the main component, wherein the cobalt content is in the range of 3.5 to 8.5 g / L.

[0130] [First Stripping Procedure] [(S74)] [ ]

[0131] In the first stripping process (S74), by mixing the organic and inorganic extractants after the first extraction, the copper contained in the organic extractant after the first extraction can be recovered into the aqueous phase, along with the recovery of pure organic extractant. After the first washing process (S73), the first stripping process (S74) can be performed.

[0132] Inorganic extractants can be inorganic acids, water, or mixtures thereof.

[0133] In the first stripping process (S74), the volume ratio of the organic extractant (organic phase) to the inorganic extractant (aqueous phase) after the first extraction can be from 9.5 to 12.5. If the volume ratio of the organic phase to the aqueous phase exceeds 12.5 in the first stripping process (S74), the copper recovery rate may decrease (e.g., less than 90%). If the volume ratio of the organic phase to the aqueous phase is less than 9.5 in the first stripping process (S74), the copper recovery rate may be increased, but the process cost may increase due to the unnecessary use of the inorganic extractant. The pH range of the first stripping process (S74) can be from about 0.5 to 1.5.

[0134] During the back-extraction of copper into the aqueous phase by mixing the aqueous and organic phases, phase separation is achieved due to the difference in specific gravity between the organic and aqueous phases. Through phase separation, a first stripped solution (aqueous phase) and a first stripped organic extractant (organic phase) are obtained. The first stripped solution can be an aqueous solution containing copper as the main component, with a copper content in the range of 40 to 50 g / L. The first stripped organic extractant can then be used as the first organic extractant in the first loading procedure (S71) (see Figure 2).

[0135] [Second Solvent Extraction Procedure] [(S80)] [ ]

[0136] In the second solvent extraction process (S80), nickel can be refined from the solution obtained after the first extraction process (S70). The second solvent extraction process (S80) can be performed after the first solvent extraction process (S70). The second solvent extraction process (S80) can be a process for refining nickel by removing impurities from the solution obtained after the first extraction using an organic extractant (a second organic extractant).

[0137] The second solvent extraction process (S80) may include a second filling process (S81), a second extraction process (S82), and a second stripping process (S84). The organic extractant may be at least one selected from the group consisting of di-2-ethylhexylphosphine, mono-2-ethylhexyl (ethylhexyl) phosphate, and bis(2,4,4-trimethylpentyl) isoxaphosphine.

[0138] [Second loading procedure] [(S81)] [ ]

[0139] The second loading procedure (S81) may be a procedure for enriching nickel in an organic phase. The second loading procedure (S81) may involve using the aqueous nickel sulfate solution and the second organic extractant to load the nickel contained in the aqueous nickel sulfate (NiSO4) solution into the second organic extractant, thereby transferring the nickel to the organic phase.

[0140] In the second filling procedure (S81), the volume ratio of the second organic extractant (organic phase) to the nickel sulfate aqueous solution (aqueous phase) can be from 4.5 to 8.5. If the volume ratio of the organic phase to the aqueous phase is less than 4.5 in the second filling procedure (S81), the target metal (nickel) is not fully bonded to the organic extractant, resulting in a low extraction rate (e.g., 90% or less). If the volume ratio of the organic phase to the aqueous phase exceeds 8.5 in the second filling procedure (S81), the process cost may increase due to excessive use of the second organic extractant.

[0141] A second filling procedure (S81) can be performed in the pH range of 5.5 to 6.5, using at least one of the groups selected from sodium hydroxide (NaOH) and sodium carbonate (Na2CO3) to adjust to this pH range.

[0142] After mixing the aqueous and organic phases to extract nickel into the organic phase, phase separation is achieved by utilizing the density difference between the organic and aqueous phases. This phase separation yields a second-filled solution (aqueous phase). This second-filled solution can be a nickel-containing aqueous solution in which most of the nickel has been extracted, with a nickel content ranging from 0.1 to 9.5 g / L.

[0143] After the solution is precipitated following the second filling, the precipitated nickel-containing byproducts can be used as neutralizing agents in the neutralization process (S50). For example, precipitating agents such as sodium hydroxide (NaOH) and sodium carbonate (Na2CO3) can be used to precipitate nickel-containing byproducts such as nickel hydroxide (Ni(OH)2) and nickel carbonate (NiCO3).

[0144] [Second Extraction Procedure] [(S82)] [ ]

[0145] In the second extraction process (S82), the solution following the first extraction from the first solvent extraction process (S70) can be mixed with a nickel-containing second-filled organic extractant to remove impurities contained in the first-extraction solution, thereby enriching the nickel in the first-extraction solution. The second extraction process (S82) can be performed after the second filling process (S81). The second-filled organic extractant can be used to remove impurities in the second extraction process (S82).

[0146] In the second extraction process (S82), the volume ratio of the second loaded organic extractant (organic phase) to the solution (aqueous phase) after the first extraction can be from 0.3 to 1.5. If the volume ratio of the organic phase to the aqueous phase is less than 0.3 in the second extraction process (S82), the extraction efficiency of impurities can be reduced (e.g., less than 90%). If the volume ratio of the organic phase to the aqueous phase exceeds 1.5 in the second extraction process (S82), the residual nickel in the organic phase can be increased, thus reducing the process efficiency. The pH range of the second extraction process (S82) can be from approximately 4.5 to 5.5.

[0147] During the back-extraction of nickel into the aqueous phase by mixing the aqueous and organic phases, phase separation is achieved due to the difference in specific gravity between the organic and aqueous phases. This phase separation allows for the preparation of a second extraction solution (aqueous phase). This second extraction solution can be an aqueous solution containing nickel as the main component, with a nickel content ranging from 85 to 125 g / L. This second extraction solution can be used as a precursor material for the positive electrode active material in lithium-ion batteries.

[0148] [Second stripping procedure] [(S84)] [ ]

[0149] In the second stripping process (S84), by mixing the organic and inorganic extractants after the second extraction, impurities in the organic extractant after the second extraction can be recovered into the aqueous phase, and pure organic extractant can also be recovered. The second stripping process (S84) can be performed after the second extraction process (S82).

[0150] Inorganic extractants can be inorganic acids, water, or mixtures thereof.

[0151] In the second stripping process (S84), the volume ratio of the organic extractant (organic phase) to the inorganic extractant (aqueous phase) after the second extraction can be 3.5 to 7.5. If the volume ratio of the organic phase to the aqueous phase exceeds 7.5 in the second stripping process (S84), the impurity removal rate may decrease (e.g., less than 85%). If the volume ratio of the organic phase to the aqueous phase is less than 3.5 in the second stripping process (S84), the impurity removal rate may increase, but the process cost may increase due to the unnecessary use of the inorganic extractant. The pH range of the second stripping process (S84) can be approximately 0.25 to 1.5.

[0152] When impurities are back-extracted into the aqueous phase by mixing the aqueous and organic phases, phase separation is achieved by utilizing the specific gravity difference between the organic and aqueous phases. Through phase separation, the second stripped organic extractant (organic phase) is obtained. The second stripped organic extractant can then be used as the second organic extractant in the second filling process (S81) (see Figure 3).

[0153] [First Precipitation Procedure] [(S90)] [ ]

[0154] In the first precipitation process (S90), the solution obtained after the first washing process (S73) in the first solvent extraction process (S70) can be purified. After the first washing process (S73), the first precipitation process (S90) can be performed. The first precipitation process (S90) can be a process for removing magnesium from the solution obtained after the first washing and recovering cobalt.

[0155] In one specific example, a first precipitant can be used in the first precipitation process (S90) to remove magnesium. The first precipitant can be at least one selected from the group consisting of sodium fluoride (NaF), oxalic acid (C2H2O4), sodium oxalate (Na2C2O4), sodium hydroxide (NaOH), and sodium carbonate (Na2CO3). For example, if sodium fluoride is used as the first precipitant, the reaction can be carried out as illustrated in the following reaction formula 7:

[0156] [Reaction 7] MgSO4 + 2NaF → MgF2↓ + Na2SO4

[0157] In the first precipitation process (S90), a first precipitant can be added at a ratio of approximately 1.0 to 3.0 equivalents relative to the magnesium contained in the solution after the first wash. If a first precipitant with a ratio of less than 1.0 equivalents relative to magnesium is added, the precipitation rate of magnesium may be 80% or less, resulting in incomplete reaction. If a first precipitant with a ratio of more than 3.0 equivalents relative to magnesium is added, excess impurities from the first precipitant may adversely affect the entire process. The pH range of the first precipitation process (S90) can be approximately 4.5 to 5.5.

[0158] When the precipitation reaction in the first precipitation process (S90) is completed, solid-liquid separation can be achieved through a conventional solid-liquid separation process. Through solid-liquid separation, a solution after the first precipitation is obtained. This solution can be a cobalt-containing aqueous solution with most impurities removed, wherein the cobalt content is in the range of 20 to 45 g / L. Through further purification, the solution after the first precipitation can be used as a precursor material for the positive electrode active material of lithium secondary batteries.

[0159] [Second Precipitation Procedure] [(S100)]

[0160] In the second precipitation process (S100), the first stripped solution produced in the first solvent extraction process (S70) via the first stripping process (S74) can be purified. After the first stripping process (S74), the second precipitation process (S100) can be performed. The second precipitation process (S100) can be a process for recovering copper from the first stripped solution.

[0161] In one specific example, a second precipitant can be used in the second precipitation process (S100) to remove copper. The second precipitant can be at least one selected from the group consisting of sodium sulfide (Na2S), sodium hydrosulfide (NaSH), ammonium hydrogen sulfide (NH4HS), hydrogen sulfide (H2S), and sodium sulfide (Na2S). For example, if sodium hydrosulfide is used as the second precipitant, the reaction can be carried out as illustrated in the following chemical formula 8:

[0162] [Chemical Formula 8] 2CuSO4 + 2NaSH → Na2SO4 + H2SO4 + 2CuS↓

[0163] In the second precipitation process (S100), a second precipitant can be added at an equivalent ratio of approximately 0.8 to 2.0 relative to the copper contained in the solution after the first stripping. If a second precipitant with an equivalent ratio of less than 0.8 relative to the copper is added, the copper recovery rate may be 80% or less, resulting in incomplete reaction. If a second precipitant with an equivalent ratio of more than 2.0 relative to the copper is added, excess impurities from the second precipitant may adversely affect the entire process. The pH range of the second precipitation process (S100) can be approximately 2.0 to 3.0.

[0164] When the precipitation reaction in the second precipitation process (S100) is completed, solid-liquid separation can be achieved through a conventional solid-liquid separation process. Through solid-liquid separation, the residue after the second precipitation can be obtained. The residue after the second precipitation can be a copper-containing precipitate, and the copper content can be 45 to 55 wt%. Through further purification, the solution after the first precipitation can be used as a precursor material for the positive electrode active material of lithium secondary batteries.

[0165] [Experimental Examples]

[0166] [[] [raw material] [] ] [ ]

[0167] As shown in Table 3 below, elements are mixed in predetermined ratios to prepare the first raw materials A to C.

[0168] Table 3

[0169] (unit: wt%)

[0170] * In addition to containing these metal ions, the first raw material contains sulfur (S), oxygen (O), and hydrogen (H) ions to form 100 by weight.

[0171] Prepare a second raw material containing the elements specified in Table 4 below.

[0172] Table 4

[0173] (unit: wt%)

[0174] * In addition to the metal ions, the second raw material contains oxygen (O) and hydrogen (H) ions to form 100 by weight.

[0175] [[] [Reduction Heat Treatment Procedure] [] ] [ ]

[0176] The first raw material containing nickel, lithium, etc., is subjected to reduction heat treatment. Specifically, 2.0 kg of raw material is loaded into a rotary kiln and then subjected to reduction heat treatment at 850°C for 3 hours. At the same time, nitrogen (N2) gas is used to maintain the reduction environment to provide the residue after reduction heat treatment, which is converted from lithium oxide (Li2O) to lithium carbonate (Li2CO3).

[0177] [[] [First filtration process] [] ] [ ]

[0178] Following the reduction heat treatment, lithium was recovered through water leaching of the residue. Specifically, 100g of the residue was loaded into a ball mill, ground, and leached with 2.5L of water (H2O) for 2 hours. Subsequently, solid-liquid separation using vacuum filtration was performed to produce a first leached residue containing the elements shown in Table 5, and a first leached liquid containing the elements shown in Table 6 was obtained.

[0179] Table 5

[0180] (unit: wt%)

[0181] * In addition to containing these metal ions, it also contains oxygen (O) and hydrogen (H) ions to form 100 by weight.

[0182] Table 6

[0183] (Unit: g / L)

[0184] [[] [Roasting Process] [] ] [ ]

[0185] A roasting process is performed on a second raw material containing nickel and sulfur. In short, 2 kg of the raw material is loaded into a rotary kiln and roasted at 850°C for 3 hours, while sufficient oxygen (O2) is injected to obtain the roasted residue (calcined material), which is converted from nickel sulfide (NiS) to nickel oxide (NiO).

[0186] [[] [Second filtration process] [] ] [ ]

[0187] The raw materials (in which the residue after reduction heat treatment and the residue after roasting are mixed in a weight ratio of 2:8) are subjected to high-temperature and high-pressure leaching.

[0188] In an autoclave, 450 g of the mixture of the mixed raw material and 3 L of water is maintained at an initial acidity of 120 g / L, a temperature of 240 °C, and a pressure of 3500 kPa for 3 hours to provide a second leaching solution with a nickel leaching rate of 95% and a nickel concentration of 60 g / L.

[0189] [[] [Neutralization Procedure] [] ] [ ]

[0190] The neutralization process is carried out using the nickel-containing byproducts in the second leaching solution.

[0191] The pH of the second leaching solution was adjusted to 2.5 by adding nickel-containing byproducts and maintained at 80°C for 3 hours to ensure a neutralized solution with a nickel concentration of 82 g / L.

[0192] [[] [First Solvent Extraction Procedure] [] ] [ ]

[0193] The first solvent extraction process is performed to refine the nickel contained in the neutralized solution.

[0194] The first loading procedure is a process in which di-ethylhexylphosphoric acid is used as an extractant to extract nickel contained in an aqueous nickel sulfate solution to produce a nickel-containing organic extractant. A mixture of 500 mL of an aqueous nickel sulfate solution containing 100 g / L nickel and 2000 mL of the organic extractant is stirred at pH 5.0 for 10 minutes, followed by phase separation based on the specific gravity difference to back-extract 95% of the nickel.

[0195] Next, the first extraction procedure is performed to extract impurities contained in the neutralized solution into the organic phase, while simultaneously back-extracting nickel contained in the first-filled organic extractant into the aqueous phase. A mixture of 500 mL of the neutralized solution and 1500 mL of the first-filled organic extractant is stirred at pH 4.0 for 10 minutes, followed by phase separation based on gravity difference to obtain a first-extraction solution with a nickel concentration of 105 g / L.

[0196] Subsequently, the first washing procedure is performed to extract the cobalt contained in the organic extractant after the first extraction into the aqueous phase. A mixture of 1000 mL of the organic extractant after the first extraction and 100 mL of distilled water is stirred at pH 2.5 for 10 minutes, followed by phase separation based on the specific gravity difference, with back-extraction to obtain 95% cobalt.

[0197] Finally, the first stripping procedure is performed to extract the copper contained in the organic extractant after the first wash into the aqueous phase. A mixture of 1000 mL of the organic extractant after the first wash and 100 mL of distilled water is stirred at pH 1.0 for 10 minutes, followed by phase separation based on the specific gravity difference to back-extract 95% of the copper.

[0198] [[] [Second Solvent Extraction Procedure] [] ] [ ]

[0199] The second solvent extraction process is performed to further refine the nickel contained in the solution after the first extraction from the first solvent extraction process.

[0200] In this second loading procedure, bis(2,4,4-trimethylpentyl)isophosphoric acid is used as the extractant to extract nickel contained in an aqueous nickel sulfate solution to prepare a nickel-containing organic extractant. Specifically, 1000 mL of an aqueous nickel sulfate solution containing 110 g / L of nickel is mixed with 5500 mL of the organic extractant and stirred at pH 6.5 for 10 minutes. Phase separation is then performed based on the difference in specific gravity to extract 95% of the nickel.

[0201] Next, the second extraction procedure is performed to extract impurities contained in the solution after the first extraction into the organic phase, while simultaneously back-extracting the organic extractant after the second loading into the aqueous phase. A mixture of 1000 mL of the neutralized solution and 500 mL of the organic extractant after the first loading is stirred at pH 5.0 for 10 minutes, followed by phase separation based on gravity difference to obtain a second-extraction solution with a nickel concentration of 115 g / L.

[0202] Finally, a second stripping procedure is performed to extract the impurities contained in the organic extractant after the second extraction into the aqueous phase. For this, 500 mL of the organic extractant after the second extraction is mixed with 50 mL of distilled water, and the mixture is stirred at pH 1.0 for 10 minutes. Phase separation is then performed based on the specific gravity difference to back-extract 95% of the impurities.

[0203] [[] [First Precipitation Procedure] [] ] [ ]

[0204] The first precipitation process is performed to remove magnesium contained in the solution after the first washing, following the first solvent extraction process.

[0205] Magnesium was removed by maintaining 1 L of the first wash solution at pH 5.5 for 2 hours using sodium fluoride and sodium carbonate to produce a first precipitate solution with a cobalt concentration of 27 g / L.

[0206] [[] [Second Precipitation Procedure] [] ] [ ]

[0207] The second precipitation process is performed to recover copper contained in the solution after the first stripping, following the first solvent extraction process.

[0208] Sodium hydrosulfide was used to maintain one liter of the first stripped solution at pH 2.5 for 2 hours. Solid-liquid separation was then performed using vacuum filtration, followed by washing with 1 L of distilled water (DIW) to obtain a residue containing 51% copper as a second precipitate.

[0209] Although specific examples of this disclosure have been illustrated with reference to the accompanying drawings, those skilled in the art will understand that such specific examples may be implemented in other particular forms without altering the technical spirit or essential characteristics of this disclosure.

[0210] Therefore, it should be understood that the specific examples described above are illustrative rather than restrictive in all respects. The scope of this disclosure is defined by the claims and not by the detailed description. It should be understood that the scope of this disclosure includes all changes or modifications derived from the meaning and scope of the claims and their equivalents.

[0211] S10: Reduction Heat Treatment Procedure S20: First filtration process S30: Calcination process S40: Second filtration process S50: Neutralization Procedure S60: Solvent Extraction Program S70: First Solvent Extraction Procedure S71: First loading procedure S72: First Extraction Procedure S73: First Washing Program S74: First stripping procedure S80: Second solvent extraction procedure S81: Second loading procedure S82: Second Extraction Procedure S84: Second stripping procedure S90: First Precipitation Process S100: Second Precipitation Process

Claims

1. A method for preparing an aqueous nickel sulfate solution, the method comprising: (Ai) a reduction heat treatment process for heat-treating a first raw material containing nickel and lithium; (B) a first leaching process for leaching the heat-treated product produced by the reduction heat treatment process with a first leaching agent; (A-ii) a calcination process for heat-treating a second raw material containing nickel and sulfur; (C) a second leaching process for leaching a first leaching residue produced by the first leaching process and a calcined material produced by the calcination process with a second leaching agent; (D) a neutralization process for neutralizing the second leached solution produced by the second leaching process with a neutralizing agent; and (E) a solvent extraction process for refining nickel in the neutralized solution produced by the neutralization process to prepare the aqueous nickel sulfate solution, wherein the solvent extraction process comprises: (Ei) a first solvent extraction process for refining nickel from the neutralized solution produced by the neutralization process; and (E-ii) A second solvent extraction process is used to refine nickel from a first extracted solution produced by the first solvent extraction process; wherein the first raw material contains black powder (BP), mixed hydroxide precipitate (MHP), mixed carbonate precipitate (MCP), or a mixture thereof; wherein the second raw material contains concentrate, matte, mixed sulfide precipitate (MSP), or a mixture thereof; wherein the first and second leaching agents include inorganic acids, water, or a mixture thereof; wherein the neutralizing agent includes mixed hydroxide precipitate, mixed carbonate precipitate, nickel hydroxide (Ni(OH)2), nickel carbonate (NiCO3), sodium hydroxide (NaOH), sodium carbonate (Na2CO3), calcium hydroxide (Ca(OH)2), magnesium hydroxide (Mg(OH)2), calcium oxide (CaO), and magnesium oxide (MgO), or a mixture thereof.

2. The method of claim 1, wherein the first raw material comprises nickel in the form of nickel oxide or nickel metal composite oxide.

3. The method of claim 1, wherein the second raw material comprises nickel in the form of nickel sulfide.

4. The method of claim 1, wherein the reduction heat treatment process is carried out at 650 to 950°C by introducing the first raw material into a heat treatment apparatus and injecting nitrogen.

5. The method of claim 1, wherein the first leaching solution obtained by the first leaching process contains lithium, and the first leaching residue contains nickel.

6. The method of claim 1, wherein the roasting process is carried out at 650 to 950°C by introducing the second raw material into a heat treatment apparatus and injecting oxygen.

7. The method of claim 1, wherein in the second leaching process, the first leaching residue and the calcined material are leached in an atmospheric pressure reactor and a high-temperature and high-pressure reactor, respectively.

8. The method of claim 1, wherein the neutralization procedure is carried out at 80°C and a pH between 2 and 4.

5.

9. The method of claim 1, wherein the neutralization is carried out for 2 hours or longer, and the neutralized solution produced by the neutralization process has a residual acidity of 10 g / L or less.

10. The method of claim 1, wherein the first solvent extraction procedure is performed by means of the following steps: (i) a first loading procedure for loading nickel into an organic phase by adding a first organic extractant to an aqueous nickel sulfate solution; (ii) a first extraction procedure for back-extracting nickel into an aqueous phase by adding the first loaded organic extractant to the neutralized solution; (iii) a first washing procedure for recovering cobalt into an aqueous phase by adding an inorganic extractant to the first extracted organic extractant; (iv) a first stripping procedure for recovering copper into an aqueous phase by adding an inorganic extractant to the first washed organic extractant; or a combination of the above steps, as shown below: (i) and (ii); (i), (ii) and (iii); or (i), (ii), (iii) and (iv).

11. The method of claim 10, wherein the first organic extractant in the first filling process is used in the aqueous nickel sulfate solution at a volume ratio of 3.5 to 6.

5.

12. The method of claim 10, wherein after precipitating the first-filled solution produced by the first filling process, the precipitated nickel-containing byproduct is used as a neutralizing agent in the neutralization process.

13. The method of claim 10, wherein the first-filled organic extractant is used in the neutralized solution in the first extraction process at a volume ratio of 1.5 to 4.

5.

14. The method of claim 10, wherein in the first washing procedure and the first stripping procedure, the volume ratio of the inorganic extractant to the organic extractant is in the range of 9.5 to 12.5 respectively.

15. The method of claim 10, wherein the first washing procedure is performed at a pH of 2 to 3.

16. The method of claim 10, wherein the first stripping procedure is performed at a pH of 0.5 to 1.

5.

17. The method of claim 10, wherein the first stripped organic extractant is used again as the first organic extractant.

18. The method of claim 10, further comprising a first precipitation process for recovering cobalt by adding a first precipitant to a first washed solution produced by the first washing process.

19. The method of claim 10, further comprising a second precipitation process for recovering copper by adding a second precipitant to the first stripped solution produced by the first stripping process.

20. The method of claim 1, wherein the second solvent extraction procedure is performed by means of the following steps: (i) a second loading procedure for loading nickel into the organic phase by adding a second organic extractant to an aqueous solution of nickel sulfate; (ii) a second extraction procedure for back-extracting nickel into the aqueous phase by adding the second loaded organic extractant to the solution after the first extraction; (iii) a second stripping procedure for recovering impurities into the aqueous phase by adding an inorganic extractant to the second extracted organic extractant; or a combination of the above steps, as shown below: (i) and (ii); or (i), (ii) and (iii).

21. The method of claim 20, wherein in the second filling procedure, the second organic extractant is used in the aqueous nickel sulfate solution at a volume ratio of 4.5 to 8.

5.

22. The method of claim 20, wherein after precipitating the second-filled solution produced by the second filling process, the precipitated nickel-containing byproduct is used as a neutralizing agent in the neutralization process.

23. The method of claim 20, wherein in the second extraction procedure, the second loaded organic extractant is used on the solution after the first extraction at a volume ratio of 0.3 to 1.

5.

24. The method of claim 20, wherein in the second stripping process, the organic extractant is used at a volume ratio of 3.5 to 7.5 to the inorganic extractant.

25. The method of claim 20, wherein the second stripping procedure is performed at a pH of 0.25 to 1.

5.

26. The method of claim 20, wherein the second stripped organic extractant is used again as the second organic extractant.

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