ALL-IN-ONE NICKEL RECOVERY METHOD FOR RECOVERING METALLIC NICKEL FROM NICKEL-CONTAINING RAW MATERIALS

Abstract

A nickel recovery method is provided 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 roasting process for heat treating a second raw material containing nickel and sulfur; (C) a second leaching process for leaching the first leach residue produced by the first leaching process and calcine produced by the roasting process; (D) a neutralization process for neutralizing the second leachate produced by the second leaching process; (E) a purification process for removing impurities contained in the neutralized solution produced by the neutralization process;and (F) a reduction process for performing a hydrogen reduction method on the purified solution produced by the purification process to recover nickel from the purified solution.;

Description

All-in-one nickel refining method for recovering nickel metal from nickel-containing raw materials

[0001] The present invention relates to a nickel smelting method and a method for producing a nickel aqueous solution using the same. More specifically, the present invention relates to a method for smelting nickel from a raw material and recovering high-purity nickel in the form of nickel metal.

[0002] Nickel can be recovered from various raw materials such as nickel metal, nickel matte, nickel concentrate, and nickel-containing process byproducts. Nickel sulfate, one of the various forms of nickel recovery, is known to be desirable when the nickel sulfate content is typically 99% or higher and the other impurity content is less than several hundred ppm.

[0003] In order to manufacture such nickel sulfate, a high-purity nickel sulfate aqueous solution was made through leaching at atmospheric pressure using an inorganic acid, neutralization using sodium hydroxide or sodium carbonate, and removal of impurities, and this was then crystallized to manufacture nickel sulfate hexahydrate.

[0004] However, the conventional method has a limited number of raw materials that are soluble in specific inorganic acids, and a method of removing Na through sludge filtration and then washing to remove the material (e.g., Na) added as a neutralizing agent has been used, but this method has the disadvantage of increasing the amount of wastewater and requiring a lot of process time, which has led to problems such as a decrease in production volume and an increase in wastewater treatment costs.

[0005] The present invention aims to provide an all-in-one process that is capable of flexibly responding to various nickel-containing raw materials by combining dry refining and wet refining technologies to recover high-purity nickel from nickel-containing composite raw materials, and that can obtain nickel in a desired form by appropriately applying subsequent processes.

[0006] The purpose of the present invention is to provide an environmentally friendly process capable of recycling process by-products.

[0007] The present invention aims to provide an economical and environmentally friendly nickel refining process that can be applied to composite raw materials as a single process by combining a dry refining method pretreatment with a recycling wet refining method that enables selective separation of lithium, conversion of a composite compound into a single compound, and recovery of inorganic acid from a hazardous gas, and minimizing the inflow of Na impurities.

[0008] One aspect of the present invention relates to a nickel smelting 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 a heat treatment product produced by the reduction heat treatment process; (A-ii) a roasting 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 roasted ore produced by the roasting process; (D) a neutralization process for neutralizing a second leaching liquid produced by the second leaching process; (E) a purification process for removing impurities contained in the neutralized liquid produced by the neutralization process; and (F) a reduction process for performing a hydrogen reduction method on the purified liquid produced by the purification process to recover nickel from the purified liquid.

[0009] One embodiment of the present invention can provide a nickel smelting method, wherein the first raw material and the second raw material independently include at least one selected from the group consisting of oxides, hydroxides, sulfides, and sulfur oxides, and the oxides, hydroxides, sulfides, and sulfur oxides independently include ore, matte, black mass (BM), black powder (BP), mixed hydroxide precipitate (MHP), mixed carbonate precipitate (MCP), mixed sulfide precipitate (MSP), or mixtures thereof.

[0010] One embodiment of the present invention can provide a nickel smelting method, wherein the first raw material includes nickel in the form of nickel oxide or nickel metal composite oxide.

[0011] One embodiment of the present invention can provide a nickel smelting method, wherein the second raw material includes nickel in the form of nickel sulfide.

[0012] One embodiment of the present invention can provide a nickel smelting method, wherein the reduction heat treatment process is performed at a temperature of 650 to 950°C by introducing a first raw material into a heat treatment device and injecting nitrogen gas.

[0013] One embodiment of the present invention can provide a nickel refining method, wherein the first leaching process is performed using a first leaching agent including an inorganic acid, water, or a mixture thereof.

[0014] One embodiment of the present invention can provide a nickel smelting method, wherein the first leaching liquid obtained by the first leaching process contains lithium, and the first leaching residue contains nickel.

[0015] One embodiment of the present invention can provide a nickel smelting method, wherein the smelting process is performed at a temperature of 650 to 950°C by introducing a second raw material into a heat treatment device and injecting oxygen gas.

[0016] One embodiment of the present invention can provide a nickel smelting method, wherein, in the second leaching process, the first leaching residue is leached in a normal pressure reactor, and the slag ore is leached in a high temperature and high pressure reactor.

[0017] One embodiment of the present invention can provide a nickel refining method, wherein the second leaching process is performed using a second leaching agent including an inorganic acid, water, or a mixture thereof.

[0018] One embodiment of the present invention can provide a nickel smelting method, wherein the second leaching process is performed at a temperature of 150 to 250°C and a pressure of 800 to 4,300 kPa.

[0019] One embodiment of the present invention can provide a nickel smelting method, wherein the second leaching process is performed in an atmosphere having an acidity of 100 to 200 g / L.

[0020] One embodiment of the present invention can provide a nickel refining method, wherein the neutralization process is performed 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 a mixture thereof.

[0021] One embodiment of the present invention can provide a nickel smelting method, wherein the neutralization process is performed at 80°C under conditions of pH 2 to 4.5.

[0022] One embodiment of the present invention provides a nickel smelting method, wherein the purification process comprises: (Ei) a first purification process for removing impurities contained in a neutralization liquid produced by the neutralization process; (E-ii) a second purification process for removing impurities contained in a first purified liquid produced by the first purification process; and (E-iii) a third purification process for removing impurities contained in a second purified liquid produced by the second purification process.

[0023] One embodiment of the present invention can provide a nickel refining method, wherein the first purification process uses a precipitation method to remove impurities including copper, iron, aluminum, silicon, zinc, cobalt, magnesium, or a combination thereof.

[0024] One embodiment of the present invention provides a nickel refining method, wherein the first purification process is performed by (i) a sulfide precipitation process in which a sulfide precipitant is added to the neutralization liquid in an amount of 1.0 to 2.5 equivalents of the copper content in the neutralization liquid, (ii) a hydroxide precipitation process in which a hydroxide precipitant is added to the neutralization liquid in an amount of 0.8 to 1.5 equivalents of the impurity content in the neutralization liquid, or a combination of (i) and (ii).

[0025] One embodiment of the present invention can provide a nickel refining method in which the second purification process removes impurities including zinc, magnesium, manganese, or a combination thereof using a solvent extraction method.

[0026] One embodiment of the present invention provides a nickel smelting method, wherein the second purification process includes (i) a loading process in which a first solvent extractant is added to the first purification liquid to extract impurities including zinc, magnesium, or a combination thereof into an organic phase, and (ii) a stripping process in which an inorganic acid is added to the organic phase to extract impurities including zinc, manganese, or a combination thereof contained in the organic phase into an aqueous phase.

[0027] One embodiment of the present invention can provide a nickel refining method in which the third purification process removes impurities including cobalt using a solvent extraction method.

[0028] One embodiment of the present invention can provide a nickel smelting method, wherein the third purification process includes (i) a loading process in which a second solvent extractant is added to the second purification liquid to extract impurities including cobalt into an organic phase, and (ii) a stripping process in which an inorganic acid is added to the organic phase to extract impurities including cobalt contained in the organic phase into an aqueous phase.

[0029] One embodiment of the present invention provides a nickel smelting method, wherein the reduction process comprises (i) an ammonium precipitation process in which an ammonium precipitant is added in an amount of 2 to 2.5 equivalents of the nickel content in the purified liquid, (ii) a hydrogen reduction process in which hydrogen gas is added to the purified liquid at a flow rate of 30 to 60 NL / hr, (iii) a growth process in which nickel metal powder particles are grown by mixing a seed of nickel metal powder produced by the hydrogen reduction process with the purified liquid, or a combination of (i) to (iii).

[0030] One embodiment of the present invention can provide a nickel smelting method, wherein the reduction process is performed using an additive including iron sulfate, aluminum sulfate, polyacrylic acid, or a combination thereof.

[0031] One embodiment of the present invention can provide a nickel smelting method, wherein the reduction process is performed under conditions of pH 8.0 to 9.0 at 160 to 200°C.

[0032] According to the present invention, selective leaching and recovery of lithium can be achieved through heat treatment of a raw material containing lithium in a strong chemical bond using a reduction heat treatment process.

[0033] According to the present invention, nickel-containing raw materials having various chemical bonding forms are phase-changed into a single phase using a firing process, thereby ensuring uniformity in subsequent processes, thereby improving the usability of the entire process as a process capable of flexibly responding to the rapidly changing nickel raw material market.

[0034] FIG. 1 is a drawing showing an overall process for smelting nickel and manufacturing nickel metal according to one embodiment of the present invention.

[0035] The embodiments of the present invention are provided for the purpose of illustrating the technical concept of the present invention. The scope of the rights of the present invention is not limited to the embodiments presented below or the specific descriptions of these embodiments.

[0036] In this specification, “%” is understood to be measured based on weight (wt) unless otherwise specified.

[0037] Hereinafter, the present invention will be described with reference to the drawings.

[0038] Figure 1 is a drawing showing the overall process for smelting nickel and manufacturing nickel metal according to one embodiment of the present invention.

[0039] Referring to Figure 1, a method for refining nickel to a high purity through a series of processes and using this nickel to manufacture nickel metal can be provided. This method can improve versatility for various raw materials and products, operational stability, and purity, and reduce manufacturing costs. Below, each process will be described in detail with reference to the respective drawings.

[0040] raw material

[0041] The first and second raw materials, which are the starting materials of the present invention, are composite raw materials mainly containing nickel, and may independently include at least one selected from the group consisting of oxides, hydroxides, sulfides, and sulfur oxides. For example, the oxides, hydroxides, sulfides, and sulfur oxides may independently include ore concentrate (ore), matte, black mass (BM), black powder (BP), mixed hydroxide precipitate (MHP), mixed carbonate precipitate (MCP), mixed sulfide precipitate (MSP), or mixtures thereof.

[0042] For example, the first raw material may include black mass (BM), black powder (BP), mixed hydroxide precipitate (MHP), mixed carbonate precipitate (MCP), or a mixture thereof. For example, the first raw material may include, in addition to nickel (Ni) and lithium (Li), iron (Fe), cobalt (Co), copper (Cu), zinc (Zn), magnesium (Mg), sodium (Na), silicon (Si), or a combination thereof as impurities. For example, the composition of the first raw material may be as shown in Table 1 below. For example, the first raw material may include nickel in the form of nickel oxide (NiO), or a nickel metal composite oxide mixed with other metals.

[0043]

[0044] For example, the second raw material may include a concentrate, a matte, a mixed sulfide precipitate (MSP), or a mixture thereof. For example, the second raw material may include, in addition to nickel (Ni) and sulfur (S), iron (Fe), cobalt (Co), copper (Cu), zinc (Zn), magnesium (Mg), sodium (Na), silicon (Si), or a combination thereof as impurities. For example, the composition of the second raw material may be as shown in Table 2 below. For example, the second raw material may include nickel in the form of nickel sulfide (NiS).

[0045]

[0046] Reduction heat treatment process (S10)

[0047] A reduction heat treatment process (S10) can be performed as a pretreatment process of the first raw material.

[0048] In the reduction heat treatment process (S10), a heat treatment can be performed on a first raw material containing nickel and lithium in the form of a complex oxide that can be combined with various metals, to cause a phase change into an oxide and / or carbonate through heat treatment in a reducing atmosphere, thereby converting the lithium-containing compound into a substance having high solubility in water or an inorganic acid.

[0049] In this way, by converting the compound form of the first raw material containing lithium through a reduction heat treatment process (S10) before performing the first leaching process (S20) for leaching / extracting lithium described below, the leaching efficiency in the first leaching process (S20) for leaching / extracting lithium can be increased.

[0050] For example, the reduction heat treatment process (S10) can be performed using a heat treatment device such as an electric furnace (e.g., a box furnace), a rotary kiln, etc.

[0051] According to one embodiment of the present invention, the reduction heat treatment process (S10) may be performed at a temperature of 650 to 950°C by charging a first raw material into a heat treatment device and injecting nitrogen gas. For example, a predetermined amount of the first raw material may be charged into the heat treatment device, and a reduction heat treatment may be performed at 650 to 950°C while sufficiently injecting nitrogen gas (N2gas) to maintain a reducing atmosphere. In this process, not only lithium but also other metals may react together, and a phase change may occur through a reaction according to [Reaction Scheme 1] below. In addition, additional reactions may occur through the reaction schemes of [Reaction Scheme 2] and [Reaction Scheme 3] below.

[0052] [Reaction Formula 1]

[0053] 9LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2+ 0.25C → 3NiO + 3MnO2+ Co3O4+ 4.5Li2O + 0.25CO2(g)

[0054] [Reaction Formula 2]

[0055] 4MnO2+ C → 2Mn2O3+ CO2(g)

[0056] [Reaction Formula 3]

[0057] Li2O + CO2(g) → Li2CO3

[0058] First leaching process (S20)

[0059] In the first leaching process (S20), nickel and lithium-containing raw materials that have undergone a phase change through the reduction heat treatment process (S10) can be leached.

[0060] The first leaching process (S20) may be performed after the reduction heat treatment process (S10). For example, the first leaching process (S20) may be performed in a wet mill. The wet mill may be a ball mill, a rod mill, a bead mill, an attrition mill, etc. The first leaching process may selectively leach the heat-treated lithium using a first leaching agent (e.g., an inorganic acid, water, or a mixture thereof).

[0061] In one embodiment, 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, and sulfuric acid produced through capturing sulfurous acid gas generated in a subsequent roasting process (S30) may be used.

[0062] In one embodiment, water may be used as the first leaching agent. In this case, lithium may be leached from the lithium-containing raw material in the form of nickel hydroxide (LiOH) through the following reaction scheme 4, thereby producing a first leaching solution. The first leaching solution may contain lithium.

[0063] [Reaction Formula 4] Li2CO3+2H2O → 2LiOH + H2O + CO2

[0064] In one embodiment, metals other than lithium may remain in the residue. For example, metals such as nickel (Ni), cobalt (Co), manganese (Mn), etc. may remain in the residue and be included in the first leach residue.

[0065] The lithium concentration of the first leaching solution obtained in the first leaching process may be approximately 0.1 to 8.5 g / L. In order to use this as a raw material for a lithium-ion battery cathode material, it can be manufactured into lithium hydroxide (LiOH·H2O), lithium carbonate (Li2CO3), lithium phosphate (Li3PO4), etc. through generally known precipitation and crystallization processes.

[0066] In the case of MHP and MCP generated in the lithium-ion battery recycling process, they can contain Li in addition to Ni, Co, and Mn, and can be used as the first raw material for performing the first leaching process.

[0067] Distribution process (S30)

[0068] As a pretreatment process of the above second raw material, a roasting process (S30) can be performed.

[0069] In the firing process (S30), inorganic acid production can be performed through recycling of sulfur dioxide gas (SO2gas) generated during the heat treatment process, along with a phase change of nickel-containing raw materials combined with various compounds.

[0070] Before the roasting process (S30) is performed, the second raw material containing nickel may be in the form of sulfide, and may be converted into an oxide by the roasting process (S30). If the second raw material containing nickel is leached as it is in the form of sulfide, the leaching rate may be lowered due to a re-precipitation reaction of the metal caused by the generation of hydrogen sulfide gas (H2S gas). Accordingly, by converting the compound form of the second raw material containing nickel through the roasting process (S30) before performing the second leaching process (S40), the leaching efficiency in the second leaching process (S40) can be improved. Here, the roasting process (S30) may be performed using a heat treatment device such as an electric furnace (Box Furnace) or a tube furnace (Rotary Kiln).

[0071] According to one embodiment of the present invention, the roasting process (S30) may be performed by charging a certain amount of nickel-containing raw material into an electric furnace, sufficiently injecting oxygen (O2) for conversion into nickel oxide, and performing roasting at 650 to 950°C. During this process, not only nickel but also other impurities may react, causing a phase change through the reaction formula of [Reaction Formula 5] below. In addition, the sulfur dioxide gas generated in the roasting process (S30) may be produced into sulfuric acid (H2SO4) by mixing with water through a separate capture facility, and used for subsequent leaching.

[0072] [Reaction Formula 5] 2NiS + 3O2 → 2NiO + 2SO2

[0073] Second leaching process (S40)

[0074] In the second leaching process (S40), the first leaching residue remaining in the residue from the first leaching process (S20) can be leached together with the post-roasting residue (roasting light) that has undergone a phase change by the roasting process (S30). The second leaching process (S40) can be performed after the roasting process (S30) and the first leaching process. In the second leaching process, the post-roasting residue can be leached in a high-temperature and high-pressure reactor, and the first leaching residue can be leached in an atmospheric pressure reactor. In the second leaching process (S40), leaching can be performed using a second leaching agent (for example, an inorganic acid, water, or a mixture thereof). In one embodiment, the second leaching process (S40) can be performed using an inorganic acid. For 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, and sulfuric acid produced by capturing sulfurous acid gas generated in the preceding roasting process (S30) may be used.

[0075] In one embodiment, sulfuric acid may be used as a second leaching agent. In this case, nickel may be leached from the first leaching residue and the post-smelting residue containing nickel in the form of nickel sulfate (NiSO4) through the following reaction scheme 6, thereby generating a second leaching solution.

[0076] [Reaction Formula 6] NiO + H2SO4 → NiSO4 + H2O

[0077] The second leaching process (S40) can be performed at a temperature of approximately 150 to 250°C and a pressure of 800 to 4,300 kPa. As the reaction temperature increases, a certain level of pressure is maintained by the saturated vapor pressure, and additional pressure can be applied to ensure complete reaction.

[0078] For example, the second leaching process (S40) may be performed in an atmosphere with an acidity of 100 to 200 g / L. After performing the second leaching process (S40) in an acidic atmosphere with a low pH to secure a sufficient second leaching solution, the subsequent neutralization process (S50) may be performed.

[0079] In one embodiment, not only nickel, but also other impurities may be leached together. For example, impurities such as iron (Fe), cobalt (Co), copper (Cu), zinc (Zn), etc. may be leached together with nickel and included in the second leaching solution.

[0080] The nickel concentration of the second leaching liquid obtained in the second leaching process (S40) may be about 45 to 105 g / L, and the residual acidity may be 10 to 80 g / L.

[0081] Neutralization process (S50)

[0082] In the neutralization process (S50), the second leaching liquid produced by the second leaching process (S40) can be neutralized. The neutralization process (S50) can be performed after the second leaching process (S40).

[0083] When the second leaching solution is produced in an atmosphere with high pH, ​​less of the second leaching solution may be produced.

[0084] In one embodiment, a second leaching process (S40) may be performed in an acidic atmosphere with low pH to secure sufficient second leaching liquid, and then a neutralization process (S50) may be performed.

[0085] In the neutralization process (S50), a neutralizing agent may be added to increase the pH of the second leaching solution generated in the second leaching process (S40). Additionally, the addition of the neutralizing agent may be for a purification process to be performed in the future.

[0086] In one embodiment, 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).

[0087] The reason why MHP and MCP are used as raw materials and neutralizers is that hydroxides and carbonates generally have high solubility in acids even without roasting, so there is no need to process them under high temperature and high pressure leaching conditions with high processing costs, and there is an effect of preparing in advance the purification process (S60) that is carried out in a high pH range by consuming the acid (H2SO4) remaining after the second leaching process (S40).

[0088] In one embodiment, the neutralization process (S50) may be performed using a nickel-containing byproduct in the form of a moist cake as the neutralizing agent. Using a nickel-containing byproduct can reduce the amount of neutralizing agent added separately, thereby reducing costs. Furthermore, the influx of additional impurities can be prevented, and the nickel concentration in the neutralized solution can be increased.

[0089] In one embodiment, the neutralization process (S50) may be performed at a temperature of 80°C and a pH of about 2 to 4.5. During this process, some impurities, including iron (Fe) and aluminum (Al), may be precipitated and removed.

[0090] Refining process (S60)

[0091] In the purification process (S60), impurities contained in the neutralization liquid generated by the neutralization process (S50) are removed, so that the neutralization liquid can be purified. The purification process (S60) can be performed after the neutralization process (S50).

[0092] In one embodiment, the purification process (S60) may include a first purification process (S61) for removing impurities contained in the neutralization liquid produced by the neutralization process (S50); a second purification process (S62) for removing impurities contained in the first purified liquid produced by the first purification process (S61); and a third purification process (S63) for removing impurities contained in the second purified liquid produced by the second purification process (S62).

[0093] First purification process (S61)

[0094] In the first purification process (S61), the neutralized liquid produced by the neutralization process (S50) can be purified. The neutralized liquid may be a neutralized leaching liquid. The first purification process (S61) is a process for removing impurities within the neutralized liquid after the neutralization process (S50).

[0095] The first purification process (S61) may be a process for removing impurities using a precipitation method. In the first purification process (S61), at least one selected from the group consisting of sodium sulfate (Na2S), sodium hydroxide (NaSH), ammonium hydrogen sulfide (NH4HS), and hydrogen sulfide (H2S) may be used as a precipitant to remove impurities using a sulfide precipitation method, thereby recovering a precipitate containing copper sulfide (CuS) as a main component and impurities such as zinc, lead, and cadmium. This can be manufactured into copper metal through a purification process such as solvent extraction and substitution.

[0096] In addition, in the first purification process (S61), at least one selected from the group consisting of sodium hydroxide (NaOH), sodium carbonate (Na2CO3), calcium hydroxide (Ca(OH)2), magnesium hydroxide (Mg(OH)2), calcium oxide (CaO), and magnesium oxide (MgO) may be used to remove impurities using a hydroxide precipitation method. Through this, impurities such as aluminum (Al), iron (Fe), chromium (Cr), silicon (Si), etc. can be precipitated and removed. When sodium hydroxide is used as a precipitant, the reaction formula is as shown in [Reaction Formula 7] below, and when sodium hydroxide is used as a precipitant, the reaction formula is as shown in [Reaction Formula 8] below.

[0097] [Reaction Formula 7] 2CuSO4+ 2NaSH → Na2SO4+ H2SO4+ 2CuS↓

[0098] [Reaction Formula 8] MSO4+ 2NaOH → Na2SO4+M(OH)2↓ (M=Al, Fe, Cr, Si)

[0099] In the purification process by the sulfide precipitation method in the first purification process (S61), the precipitant may be added at an equivalent ratio of about 1.0 to 2.5 relative to the copper contained in the neutralization solution. If the sulfide precipitant is added at an equivalent ratio of less than 1.0 relative to copper, the copper precipitation rate may be 83% or less, and complete reaction may not occur. If the sulfide precipitant is added at an equivalent ratio of more than 2.5 relative to copper, impurities originating from the precipitant may be excessively introduced, negatively affecting the process and reducing the recovery rate due to nickel co-precipitation. The pH range in which the reaction is performed at this time may be 0.8 to 2.5 at 70°C.

[0100] In the purification process using the hydroxide precipitation method, the precipitant can be added at an equivalent ratio of approximately 0.8 to 1.5 relative to the impurities contained in the neutralized solution. If the hydroxide precipitant is added at an equivalent ratio of less than 0.8 relative to the impurities, the impurity removal rate may be less than 85%, and the reaction may not occur completely. If the hydroxide precipitant is added at an equivalent ratio of more than 1.5 relative to the heavy metal, the impurities originating from the precipitant may be excessively introduced, negatively affecting the process and reducing the recovery rate due to nickel co-precipitation. The pH range in which the reaction is performed at this time may be 2.5 to 4.5 at 60°C.

[0101] After the first purification process (S61), the contents of copper, iron, aluminum, and silicon contained in the first purified liquid can be lowered to 5 mg / L or less, and the contents of zinc, cobalt, and magnesium contained in the first purified liquid can be lowered to 20 mg / L or less, respectively.

[0102] Second purification process (S62)

[0103] In the second purification process (S62), the first purified liquid produced by the first purification process (S61) may be further purified. The second purification process (S62) may be performed after the first purification process (S61). The second purification process (S62) may be a process for removing impurities using a solvent extraction method.

[0104] In the second purification process (S62), an organic extractant may be used to remove impurities such as zinc (Zn), magnesium (Mg), and manganese (Mn).

[0105] In one embodiment, the second purification process (S62) may include a loading process and a stripping process. As the organic extractant, at least one selected from the group consisting of Di-2-Ethylhexyl Phosphoric Acid, Mono-2-ethylhexyl (2-Ethylhexyl)phosphonate, and Bis (2,4,4-Trimethylpentyl) Phosphinic Acid may be used.

[0106] The loading process may be a process for extracting impurities including zinc, magnesium, or a combination thereof contained in the first purified liquid into an organic phase. The loading process may be a process for extracting zinc, magnesium, and manganese contained in the first purified liquid after the first purification process (S61) into an organic phase using an organic extractant.

[0107] The volume ratio of the organic phase to the aqueous phase in the loading process may be about 1 to 3. If the volume ratio of the organic phase to the aqueous phase in the loading process is less than 1, the binding of the target metal and the organic extractant may not be complete, resulting in an extraction rate of 90% or less. If the volume ratio of the organic phase to the aqueous phase in the loading process exceeds 3, the process cost may increase due to excessive use of the organic extractant. In order to adjust the pH range of the loading process to 2.0 to 4.0, at least one selected from the group consisting of sodium hydroxide (NaOH) and sodium carbonate (Na2CO3) may be used. In addition, the reaction temperature at this time may be 30 to 40°C.

[0108] When zinc, magnesium, and manganese are extracted into the organic phase by mixing the aqueous and aqueous phases, phase separation is possible based on the difference in specific gravity between the organic and aqueous phases. This phase separation can produce a second purified solution. The second purified solution is a nickel-containing aqueous solution from which zinc and magnesium have been removed, and the nickel content may range from 50 to 100 g / L.

[0109] The organic phase containing zinc and magnesium can undergo a stripping process. In the stripping process, an inorganic acid is added to the organic phase after the loading process to remove impurities contained therein. The stripping process can be a process for extracting zinc, magnesium, and manganese contained in the organic phase back into the aqueous phase.

[0110] The volume ratio of the organic phase to the aqueous phase in the stripping process may be about 5 to 10. If the volume ratio of the organic phase to the aqueous phase in the stripping process is less than 5, complete extraction of impurities is possible, but the amount of water used may increase. If the volume ratio of the organic phase to the aqueous phase in the stripping process exceeds 10, the efficiency of reverse extraction of impurities may decrease. The pH range of the stripping process may be about 0.5 to 1.5. Sulfuric acid (H2SO4) may be used to adjust the pH range of the stripping process to about 0.5 to 1.5. In addition, the reaction temperature at this time may be 30 to 40°C.

[0111] Third refining process (S63)

[0112] In the third purification process (S63), the second purified liquid produced by the second purification process (S62) may be further purified. The third purification process (S63) may be performed after the second purification process (S62). The third purification process (S63) may be a process for removing impurities using a solvent extraction method. An organic extractant may be used to remove impurities including cobalt in the third purification process (S63). In one embodiment, the third purification process (S63) may include a loading process and a stripping process. As the organic extractant, at least one selected from the group consisting of Di-2-Ethylhexyl Phosphoric Acid, Mono-2-ethylhexyl (2-Ethylhexyl)phosphonate, and Bis (2,4,4-Trimethylpentyl) Phosphinic Acid may be used.

[0113] The loading process may be a process for extracting impurities including cobalt contained in the second purified liquid into an organic phase. The loading process may be a process for extracting cobalt contained in the second purified liquid after the second purification process (S62) into an organic phase using an organic extractant.

[0114] The volume ratio of the organic phase to the aqueous phase in the loading process may be about 1 to 3. If the volume ratio of the organic phase to the aqueous phase in the loading process is less than 1, the binding of the target metal and the organic extractant may not be complete, resulting in an extraction rate of 90% or less. If the volume ratio of the organic phase to the aqueous phase in the loading process exceeds 3, the process cost may increase due to excessive use of the organic extractant. In order to adjust the pH range of the loading process to 4 to 5, at least one selected from the group consisting of sodium hydroxide (NaOH) and sodium carbonate (Na2CO3) may be used. In addition, the reaction temperature at this time may be 30 to 40°C.

[0115] Once cobalt is extracted into the organic phase by mixing the aqueous and aqueous phases, phase separation is possible due to the difference in specific gravity between the organic and aqueous phases. This phase separation can produce a third purified solution. The third purified solution is a nickel-containing aqueous solution from which cobalt has been removed, and its nickel content can range from 65 to 125 g / L.

[0116] Organic phases containing cobalt can undergo a stripping process.

[0117] In the stripping process, cobalt contained in the organic phase can be removed by adding an inorganic acid to the organic phase after the loading process. The stripping process may be a process for back-extracting cobalt contained in the organic phase into the aqueous phase.

[0118] The volume ratio of the organic phase to the aqueous phase in the stripping process may be about 3 to 10. If the volume ratio of the organic phase to the aqueous phase in the stripping process is less than 3, complete extraction of impurities is possible, but water usage may increase. If the volume ratio of the organic phase to the aqueous phase in the stripping process is more than 10, the reverse extraction efficiency of cobalt may decrease. The pH range of the stripping process may be about 0.5 to 1.5. Sulfuric acid (H2SO4) may be used to adjust the pH range of the stripping process to about 0.5 to 1.5. In addition, the reaction temperature at this time may be 30 to 40°C.

[0119] Once cobalt is extracted into the organic phase by mixing the aqueous and aqueous phases, phase separation is possible due to the difference in specific gravity between the organic and aqueous phases. This phase separation produces a process solution containing cobalt, which can be further purified through precipitation and crystallization to produce high-purity cobalt sulfate.

[0120] Reduction process (S70)

[0121] In the reduction process (S70), nickel can be reduced and recovered as metal from the purified liquid (e.g., the third purified liquid produced by the third purification process (S63)) produced by the purification process (S60) (e.g., the third purification process (S63)). The reduction process (S70) can be performed after the third purification process (S63).

[0122] The reduction process (S70) may be a process for reducing nickel into metal powder using a hydrogen reduction method. The reduction process (S70) may be performed by (i) an ammonium precipitation process in which an ammonium precipitant is added in an amount of 2 to 2.5 equivalents of the nickel content in the post-purification liquid to form a nickel complex, (ii) a hydrogen reduction process in which hydrogen gas is added to the post-purification liquid at a flow rate of 30 to 60 NL / hr, (iii) a growth process in which nickel metal powder particles are grown by mixing the seed of the nickel metal powder produced by the hydrogen reduction process with the post-purification liquid, or a combination of (i), (ii), and (iii).

[0123] For example, the above reduction process (S70) may include all of (i), (ii), and (iii), and the order of (i), (ii), and (iii) is not particularly limited.

[0124] For example, the above reduction process (S70) can be performed through the chain reactions of (i), (ii), and (iii).

[0125] For example, the purified liquid of the above (iii) may be one in which an ammonium precipitant of the content of (i) and hydrogen gas of the flow rate of (ii) are injected.

[0126] The reduction process (S70) can be performed using an additive including iron sulfate, aluminum sulfate, polyacrylic acid, or a combination thereof to effectively perform the hydrogen reduction reaction.

[0127] The above reduction process generates nickel metal powder seeds by adding a precipitant in the first reaction, and then repeatedly mixes a new purified solution with the nickel powder seeds generated in the first reaction to increase the single particle size of the nickel metal powder, thereby improving the density of the nickel metal powder and reducing the amount of precipitant used in the initial stage of the reaction.

[0128] At least one selected from the group consisting of ammonium hydroxide (NH4OH), ammonium sulfate ((NH4)2SO4), and ammonium hydrogen sulfate ((NH4)HSO4) can be used as a precipitant, and hydrogen gas (H2gas) can be used for reduction of the nickel complex salt to nickel metal.

[0129] When ammonium hydroxide is used as a precipitant, the reaction equation is as shown in [Reaction Equation 9] below.

[0130] [Reaction Formula 9] NiSO4+2NH4OH → Ni(NH3)2SO4+ 2H2O

[0131] When hydrogen gas is used for the reduction of the complex formed here, the reaction equation is as shown in [Reaction Equation 10] below.

[0132] [Reaction Scheme 10] Ni(NH3)2SO4+ H2→ Ni +(NH4)2SO4

[0133] The reduction process (S70) can be performed at a temperature of 160 to 200°C and a pH of 8.0 to 9.0. If the pH is below 8.0, nickel recovery may be less than 80%. If the pH exceeds 9.0, excessive impurities from the precipitant are introduced, negatively impacting the process and reducing economic feasibility due to excessive precipitant use.

[0134] The nickel metal powder produced by the present invention can be utilized as nickel metal in powder form after drying, and can be manufactured into briquettes through further processing. This can be suitably used as a nickel raw material for a precursor among the raw materials for cathode active materials in lithium secondary batteries, or in the form of an alloy when mixed with iron.

[0135] Experimental example

[0136] [raw material]

[0137] A first raw material was prepared by mixing A to C, each containing the elements in Table 3 below, in a predetermined ratio.

[0138]

[0139] A second raw material containing the elements in Table 4 below was prepared.

[0140]

[0141] [Reduction heat treatment process]

[0142] A reduction heat treatment of the first raw material containing nickel, lithium, etc. was performed. Specifically, after charging 2.0 kg of the raw material in a tube furnace, a reduction heat treatment was performed at 850°C for 3 hours while maintaining a reduction atmosphere using N2 gas, thereby securing a residue after reduction heat treatment that was converted from a lithium oxide (Li2O) form to a lithium carbonate (Li2CO3) form.

[0143] [First leaching process]

[0144] Lithium recovery was performed through water leaching of the residue after reduction heat treatment. Specifically, 100 g of raw material was placed in a ball mill, crushed and water-leached with 2.5 L of water (H2O) for 2 hours, and then solid-liquid separation using reduced pressure filtration was performed to obtain a first leaching residue containing the elements listed in Table 5 below and a first leaching solution containing the elements listed in Table 6 below.

[0145]

[0146]

[0147] [Batch Process]

[0148] A roasting process of a second raw material containing nickel, sulfur, etc. was performed. Specifically, after charging 2 kg of raw material in a tube furnace, the raw material was roasted at 850°C for 3 hours while sufficiently injecting oxygen (O2), thereby obtaining a roasted residue (roasted ore) converted from nickel sulfide (NiS) to nickel oxide (NiO).

[0149] [Second Leaching Process]

[0150] The raw material, which was a mixture of the residue after the reduction heat treatment and the residue after the roasting at a weight ratio of 2:8, was subjected to high-temperature and high-pressure leaching.

[0151] In an autoclave, 450 g of mixed raw materials and 3 L of water were mixed and maintained at 240°C and 3,500 kPa for 3 hours at an initial acidity of 120 g / L, resulting in a second leaching solution having a nickel concentration of 60 g / L and a nickel leaching rate of 95%.

[0152] [Neutralization process]

[0153] A neutralization process was performed using nickel-containing by-products from the second leaching solution.

[0154] The pH of 2 L of the second leaching solution was maintained at 80°C for 3 hours at 2.5 by adding nickel-containing byproducts, and a neutralized solution with a nickel concentration of 82 g / L was obtained.

[0155] [First Purification Process]

[0156] The first purification process was performed to remove impurities contained in the neutralized solution using the precipitation method.

[0157] When 1.3 equivalents (eq) of sodium bisulfide (NaSH) were added based on the copper (Cu) equivalent ratio contained in the neutralization solution and the pH was maintained at 2.5 for 2 hours at 70°C, 99.8% of copper was removed. In addition, to remove aluminum, iron, and silicon contained in the neutralization solution, nickel-containing byproducts and sodium hydroxide (NaOH) were used to maintain the pH at 4.5 for 2 hours, and as a result, a first purified solution was secured from which more than 99.5% of the above-mentioned impurities were removed.

[0158] [Second Purification Process]

[0159] A second purification process was performed to remove impurities contained in the first purified liquid using a solvent extraction method.

[0160] In order to load impurities including zinc and magnesium into the extractant, 500 mL of the first purified solution and 1,000 mL of Di-2-Ethylhexyl Phosphoric Acid extractant diluted to 25% were mixed, stirred at pH 3.5 and 40°C for 10 minutes, and 99% of zinc and 43% of magnesium were extracted through phase separation by specific gravity difference. Complete extraction of impurities was possible through countercurrent exchange in a mixer settler.

[0161] [Third Purification Process]

[0162] A third purification process was performed to remove cobalt contained in the second purified liquid using a solvent extraction method.

[0163] 500 mL of the second purified solution containing cobalt and 1,000 mL of Bis (2,4,4-TRIMETHYLPENTYL) Phosphinic Acid extractant diluted to 25% were mixed and stirred at 40°C at pH 5.0 for 10 minutes, and approximately 55% of cobalt was extracted through phase separation by specific gravity difference. Complete extraction of impurities was possible through countercurrent exchange in a mixer settler.

[0164] Through this, cobalt was purified to less than 3 mg / L, and a third purified liquid containing the elements in Table 7 below was secured.

[0165]

[0166] [Reduction process]

[0167] A reduction process was performed to recover nickel contained in the third purified liquid in the form of metal powder using the hydrogen reduction method.

[0168] In an autoclave, 1 L of the third purified liquid containing 42 g / L of nickel was maintained at pH 8.5 at 180°C for 4 hours using ammonium hydroxide (NH4OH), and then 99% hydrogen gas was injected at 50 NL / hr to create a reducing atmosphere. 1.7 g of iron sulfate, 1 g of aluminum sulfate, and 0.1 g of polyacrylic acid were each injected as catalysts, and the reaction was carried out for 4 hours to separate solid and liquid using reduced pressure filtration, and after washing with 1 L of distilled water (DIW), nickel metal powder containing the elements shown in Table 8 below was obtained.

[0169]

[0170] Although the embodiments of the present invention have been described with reference to the attached drawings, those skilled in the art will understand that the present invention can be implemented in other specific forms without changing the technical idea or essential features thereof.

[0171] Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims rather than the detailed description above, and all modifications or variations derived from the meaning and scope of the claims and their equivalents should be construed as being included within the scope of the present invention.

Claims

1. (Ai) A reduction heat treatment process for heat treating a first raw material containing nickel and lithium; (B) A first leaching process for leaching a heat treatment product produced by the above reduction heat treatment process; (A-ii) A roasting 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 leaching ore produced by the leaching process; (D) A neutralization process for neutralizing the second leaching liquid produced by the second leaching process; (E) a purification process for removing impurities contained in the neutralized liquid produced by the neutralization process; and (F) A nickel refining method, comprising a reduction process for performing a hydrogen reduction method to recover nickel from the purified liquid produced by the above purification process.

2. In paragraph 1, The first raw material and the second raw material independently contain at least one selected from the group consisting of oxides, hydroxides, sulfides, and sulfur oxides, A nickel smelting method, wherein the oxides, hydroxides, sulfides and sulfides are independently selected from the group consisting of ore, matte, black mass (BM), black powder (BP), mixed hydroxide precipitate (MHP), mixed carbonate precipitate (MCP), mixed sulfide precipitate (MSP) or a mixture thereof.

3. In paragraph 1, A nickel smelting method, wherein the first raw material comprises nickel in the form of nickel oxide or nickel metal composite oxide.

4. In paragraph 1, A nickel smelting method, wherein the second raw material comprises nickel in the form of nickel sulfide.

5. In paragraph 1, A nickel smelting method in which the above reduction heat treatment process is performed at a temperature of 650 to 950°C by putting the first raw material into a heat treatment device and injecting nitrogen gas.

6. In paragraph 1, A nickel refining method, wherein the first leaching process is performed using a first leaching agent comprising an inorganic acid, water or a mixture thereof.

7. In paragraph 1, A nickel smelting method, wherein the first leaching liquid obtained by the first leaching process contains lithium, and the first leaching residue contains nickel.

8. In paragraph 1, A nickel smelting method in which the above-mentioned firing process is performed at a temperature of 650 to 950°C by putting a second raw material into a heat treatment device and injecting oxygen gas.

9. In paragraph 1, A nickel smelting method, wherein in the second leaching process, the first leaching residue is leached in a normal pressure reactor, and the slag ore is leached in a high temperature and high pressure reactor.

10. In paragraph 1, A nickel refining method, wherein the second leaching process is performed using a second leaching agent comprising an inorganic acid, water or a mixture thereof.

11. In paragraph 1, A nickel smelting method, wherein the second leaching process is performed at a temperature of 150 to 250°C and a pressure of 800 to 4,300 kPa.

12. In paragraph 1, A nickel smelting method, wherein the second leaching process is performed in an atmosphere having an acidity of 100 to 200 g / L.

13. In paragraph 1, A nickel refining method, wherein the neutralization process is performed 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 a mixture thereof.

14. In paragraph 1, A nickel smelting method, wherein the above neutralization process is performed at 80°C under conditions of pH 2 to 4.

5.

15. In paragraph 1, The above purification process is, (Ei) A first purification process for removing impurities contained in the neutralized liquid produced by the neutralization process; (E-ii) a second purification process for removing impurities contained in the first purified liquid produced by the first purification process; and (E-iii) A nickel refining method comprising a third purification process for removing impurities contained in the second purified liquid produced by the second purification process.

16. In paragraph 15, The above first purification process is a nickel smelting method that removes impurities including copper, iron, aluminum, silicon, zinc, cobalt, magnesium, or a combination thereof using a precipitation method.

17. In paragraph 15, A nickel smelting method, wherein the first purification process is performed by (i) a sulfide precipitation process in which a sulfide precipitant is added to the neutralized liquid in an amount of 1.0 to 2.5 equivalents of the copper content in the neutralized liquid, (ii) a hydroxide precipitation process in which a hydroxide precipitant is added to the neutralized liquid in an amount of 0.8 to 1.5 equivalents of the impurity content in the neutralized liquid, or a combination of (i) and (ii).

18. In paragraph 15, The second purification process is a nickel smelting method that removes impurities including zinc, magnesium, manganese, or a combination thereof using a solvent extraction method.

19. In paragraph 15, A nickel smelting method, wherein the second purification process comprises (i) a loading process in which a first solvent extractant is added to the first purification liquid to extract impurities including zinc, magnesium, manganese or a combination thereof into an organic phase, and (ii) a stripping process in which an inorganic acid is added to the organic phase to extract impurities including zinc, magnesium, manganese or a combination thereof contained in the organic phase into an aqueous phase.

20. In paragraph 15, The third refining process is a nickel refining method that removes impurities including cobalt using a solvent extraction method.

21. In paragraph 15, A nickel smelting method, wherein the third purification process comprises (i) a loading process in which a second solvent extractant is added to the second purification liquid to extract impurities including cobalt into an organic phase, and (ii) a stripping process in which an inorganic acid is added to the organic phase to extract impurities including cobalt contained in the organic phase into an aqueous phase.

22. In paragraph 1, A nickel smelting method, wherein the reduction process comprises (i) an ammonium precipitation process in which an ammonium precipitant is added in an amount of 2 to 2.5 equivalents of the nickel content in the post-purification liquid, (ii) a hydrogen reduction process in which hydrogen gas is added to the post-purification liquid at a flow rate of 30 to 60 NL / hr, (iii) a growth process in which nickel metal powder particles are grown by mixing a seed of nickel metal powder produced by the hydrogen reduction process with the post-purification liquid, or a combination of (i) to (iii).

23. In paragraph 1, A nickel smelting method, wherein the above reduction process is performed using an additive including iron sulfate, aluminum sulfate, polyacrylic acid, or a combination thereof.

24. In paragraph 1, A nickel smelting method, wherein the above reduction process is performed at a temperature of 160 to 200°C and a pH of 8.0 to 9.0.