Integrated nickel smelting method for recovering nickel hydroxide from nickel-containing raw material

Abstract

Provided is a nickel smelting method comprising: (A-i) a reduction heat treatment step for heat-treating a first raw material containing nickel and lithium; (B) a first leaching step for leaching a heat-treated product generated in the reduction heat treatment step; (A-ii) a roasting step for heat-treating a second starting material containing nickel and sulfur; (C) a second leaching step for leaching a first leaching residue generated in the first leaching step and a calcined material generated in the roasting step; (D) a neutralization step for neutralizing a second post-leaching solution generated in the second leaching step; (E) a purification step for removing impurities contained in the post-neutralization liquid generated in the neutralization step; and (F) a precipitation step in which a precipitation method is performed to recover nickel from the purified liquid generated in the purification step, and nickel hydroxide is recovered according to the precipitation step.

Description

Technical Field

[0001] The present invention relates to a nickel smelting method and a method for producing a nickel solution using the same. More particularly, the present invention relates to a method for smelting nickel from a raw material to recover high-purity nickel in the form of nickel hydroxide. Background Art

[0002] Nickel can be recovered from various raw materials such as nickel metal, nickel matte, nickel concentrate and nickel-containing process by-products. Among the various forms of nickel recovered, it is known that the content of nickel sulfate is generally 99% or higher, with impurities reaching hundreds of ppm or less.

[0003] Such nickel sulfate is generally produced by leaching with an inorganic acid under normal pressure, neutralizing with sodium hydroxide or sodium carbonate, and removing impurities to prepare a high-purity nickel sulfate solution, and then crystallizing the solution into nickel sulfate hexahydrate.

[0004] However, a drawback of these existing methods is the limited amount of raw materials soluble in a particular inorganic acid. In existing methods, neutralizing agents (e.g., sodium (Na)) are removed by washing with water after sludge filtration. This sodium (Na) removal method increases wastewater volume and requires a considerable amount of time, resulting in reduced productivity and increased wastewater treatment costs. Summary of the Invention

[0005] Technical issues

[0006] The object of the present invention is to provide an integrated process for recovering high-purity nickel from nickel-containing composite raw materials, which is a hybrid process combining dry metallurgical smelting and wet metallurgical smelting techniques, wherein, even when various nickel-containing raw materials are used, appropriate reactions can be carried out and then appropriate subsequent processes can be carried out to obtain the nickel in the desired form.

[0007] An object of the present invention is to provide an environmentally friendly process capable of recycling process by-products.

[0008] The present invention aims to provide an economical and environmentally friendly nickel smelting process that can selectively separate lithium, convert complex compounds into single compounds, and recover inorganic acids from harmful gases through pretreatment using a dry smelting method, and is combined with a recycling wet smelting method that minimizes the influx of sodium (Na) impurities, so that it can be applied to complex raw materials even through a single process.

[0009] Technical Solution

[0010] One embodiment of the present invention relates to a nickel smelting method, comprising: (Ai) a reduction heat treatment step for heat-treating a first raw material containing nickel and lithium; (B) a first leaching step for leaching a heat-treated product generated by the reduction heat treatment step; (A-ii) a roasting step for heat-treating a second raw material containing nickel and sulfur; (C) a second leaching step for leaching a first leaching residue generated by the first leaching step and a calcined material generated by the roasting step; (D) a neutralization step for neutralizing a second leached liquid generated by the second leaching step; (E) a purification step for removing impurities contained in the neutralized liquid generated by the neutralization step; and (F) a precipitation step for performing a precipitation method to recover nickel from the purified liquid generated by the purification step, and recovering nickel hydroxide according to the precipitation step.

[0011] In a nickel smelting method according to an embodiment of the present invention, the first raw material and the second raw material may each independently include at least one selected from the group consisting of oxides, hydroxides, sulfides and oxysulfides, and the above-mentioned oxides, hydroxides, sulfides and oxysulfides each independently contain concentrate (ore), matte, black mass (BM), black powder (BP), mixed hydroxide precipitate (MHP), mixed carbonate precipitate (MCP), mixed sulfide precipitate (MSP) or a mixture thereof.

[0012] In the nickel smelting method according to an embodiment of the present invention, the first raw material may include nickel in the form of nickel oxide or nickel metal composite oxide.

[0013] In the nickel smelting method according to an embodiment of the present invention, the second raw material may include nickel in the form of nickel sulfide.

[0014] In the nickel smelting method according to an embodiment of the present invention, a reduction heat treatment process may be performed at a temperature of 650° C. to 950° C. by introducing the first raw material into a heat treatment device and injecting nitrogen.

[0015] In the nickel smelting method according to an embodiment of the present invention, the first leaching process may be performed using a first leaching agent including an inorganic acid, water, or a mixture thereof.

[0016] In the nickel smelting method according to an embodiment of the present invention, the first leached liquid obtained in the first leaching step may contain lithium, and the first leaching residue may contain nickel.

[0017] In the nickel smelting method according to an embodiment of the present invention, the roasting process may be performed at a temperature of 650° C. to 950° C. by introducing the second raw material into a heat treatment device and injecting oxygen.

[0018] In the nickel smelting method according to an embodiment of the present invention, in the second leaching step, the first leaching residue may be leached in a normal pressure reactor, and the calcined material may be leached in a high temperature and high pressure reactor.

[0019] In the nickel smelting method according to an embodiment of the present invention, the second leaching process may be performed using a second leaching agent including an inorganic acid or a mixture of an inorganic acid and water.

[0020] In the nickel smelting method according to an embodiment of the present invention, the second leaching process may be performed at a temperature of 150° C. to 250° C. and a pressure of 800 kPa to 4300 kPa.

[0021] In the nickel smelting method according to an embodiment of the present invention, the second leaching step may be performed in an environment with an acidity of 100 g / L to 200 g / L.

[0022] In the nickel smelting method according to one embodiment of the present invention, the neutralization process can be carried out using a neutralizer, and the neutralizer includes 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.

[0023] In the nickel smelting method according to an embodiment of the present invention, the neutralization process may be performed at a temperature of 80° C. and a pH of 2 to 4.5.

[0024] In a nickel smelting method according to one embodiment of the present invention, the purification process may include: (Ei) a first purification process for removing impurities contained in the neutralized liquid generated by the neutralization process; (E-ii) a second purification process for removing impurities contained in the first purified liquid generated by the first purification process; and (E-iii) a third purification process for removing impurities contained in the second purified liquid generated by the second purification process.

[0025] In the nickel smelting method according to an embodiment of the present invention, the first purification step may use a precipitation method to remove impurities including copper, iron, aluminum, silicon, zinc, cobalt, magnesium, or a combination thereof.

[0026] In the nickel smelting method according to one embodiment of the present invention, the first purification step can be performed by (i) adding a sulfide precipitating agent to the sulfide precipitation step of the neutralized liquid in an amount of 1.0 to 2.5 equivalents of the copper content in the neutralized liquid, (ii) adding a hydroxide precipitating agent to the hydroxide precipitation step of 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).

[0027] In the nickel smelting method according to an embodiment of the present invention, the second purification process may use a solvent extraction method to remove impurities including zinc, magnesium, manganese or a combination thereof.

[0028] In the nickel smelting method according to one embodiment of the present invention, the second purification process may include: (i) a loading process of adding a first solvent extractant to the first purified liquid to extract impurities including zinc, magnesium, or a combination thereof into an organic phase; and (ii) a removal process of adding an inorganic acid to the organic phase to extract impurities including zinc, manganese, or a combination thereof contained in the organic phase into an aqueous phase.

[0029] In the nickel smelting method according to an embodiment of the present invention, the third purification process may use a solvent extraction method to remove impurities including cobalt.

[0030] In the nickel smelting method according to one embodiment of the present invention, the third purification process may include (i) a loading process of adding a second solvent extractant to the second purified liquid to extract impurities including cobalt into an organic phase; and (ii) a removal process of adding an inorganic acid to the organic phase to extract impurities including cobalt contained in the organic phase into an aqueous phase.

[0031] In a nickel smelting method according to one embodiment of the present invention, the precipitation process may be carried out using a precipitant including sodium hydroxide (NaOH), calcium hydroxide (Ca(OH)2), magnesium hydroxide (Mg(OH)2), calcium oxide (CaO), magnesium oxide (MgO) or a mixture thereof.

[0032] In the nickel smelting method according to an embodiment of the present invention, the precipitation process may be performed at a temperature of 85° C. and a pH of 6.5 to 10.0.

[0033] Effects of the Invention

[0034] According to the present invention, the reduction heat treatment step enables leaching and recovery of lithium from a raw material containing lithium forming a strong chemical bond through heat treatment.

[0035] According to the present invention, a roasting process is utilized to convert various nickel-containing raw materials having various chemical bond forms into a single phase, thereby ensuring uniformity in subsequent processes. The above process can thus be flexibly adapted to the rapidly changing nickel raw material market, thereby contributing to the applicability of the entire process. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 FIG. 1 is a diagram illustrating the entire process of smelting nickel and producing nickel hydroxide according to an embodiment of the present invention. DETAILED DESCRIPTION

[0037] The embodiments of the present invention are illustrated for the purpose of explaining the technical concept of the present invention. The scope of protection of the present invention is not limited to the embodiments presented below or the detailed description of these embodiments.

[0038] Unless otherwise specified, "%" in the present invention should be understood as being based on weight.

[0039] Hereinafter, a description of the present invention will be provided with reference to the accompanying drawings.

[0040] Figure 1 FIG. 1 is a diagram illustrating the entire process of smelting nickel and producing nickel hydroxide according to an embodiment of the present invention.

[0041] refer to Figure 1 A method for smelting nickel to high purity through a series of steps, and for producing nickel hydroxide using the smelted nickel, is provided. This method improves the versatility, operational stability, and purity of various raw materials and products, while simultaneously reducing manufacturing costs. Each step is described in detail below with reference to individual figures.

[0042] raw material

[0043] The first and second starting materials are primarily composed of a nickel-containing composite raw material. The starting materials may each independently include at least one selected from the group consisting of oxides, hydroxides, sulfides, and oxysulfides. For example, the oxides, hydroxides, sulfides, and sulfates may 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.

[0044] For example, the first raw material may include black matter (BM), black powder (BP), mixed hydroxide precipitate (MHP), mixed carbonate precipitate (MCP), or a mixture thereof. In addition to nickel (Ni) and lithium (Li), the first raw material may contain impurities such as iron (Fe), cobalt (Co), copper (Cu), zinc (Zn), magnesium (Mg), sodium (Na), silicon (Si), or a combination thereof. For example, the composition of the first raw material may be as shown in Table 1. The first raw material may contain nickel in the form of nickel oxide (NiO) or a nickel-metal composite oxide mixed with other metals.

[0045] Table 1 (Unit: wt%)

[0046]

[0047] The second raw material may include concentrate, ice ore, mixed sulfide precipitate (MSP), or a mixture thereof. For example, in addition to nickel (Ni) and sulfide (S), the second raw material may contain impurities such as iron (Fe), cobalt (Co), copper (Cu), zinc (Zn), magnesium (Mg), sodium (Na), silicon (Si), or a combination thereof. For example, 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).

[0048] Table 2 (Unit: wt%)

[0049] Ni Fe Co Cu Zn Mn Mg Al Si content 6-30 5-45 0.1-1.0 0.1-5.0 0.01-1.0 0.01-1.0 0.3-15 0.1-1.0 10-30

[0050] Reduction heat treatment step S10

[0051] The reduction heat treatment step S10 may be performed as a pretreatment step of the first raw material.

[0052] In the reduction heat treatment step S10, the first raw material containing nickel and lithium in the form of a composite oxide capable of bonding with various metals is heat-treated in a reducing atmosphere. This treatment causes a phase transformation into oxides and / or carbonates, converting the lithium-containing compound into a substance with high solubility in water or inorganic acids.

[0053] As such, by converting the compound form of the lithium-containing first raw material through the reduction heat treatment step S10 before proceeding to the first leaching step S20 for leaching / extracting lithium described later, the leaching efficiency in the first leaching step S20 for leaching / extracting lithium can be improved.

[0054] For example, the reduction heat treatment step S10 may be performed using a heat treatment apparatus such as an electric furnace (eg, a box furnace) or a rotary kiln.

[0055] According to one embodiment of the present invention, the reduction heat treatment process S10 can be performed at a temperature of 650°C to 950°C by introducing the first raw material into a heat treatment device and injecting nitrogen gas. For example, a certain amount of the first raw material can be loaded into the heat treatment device, and sufficient nitrogen gas (N2 gas) can be injected to maintain a reducing atmosphere. The reduction heat treatment can be performed at a temperature of 650°C to 950°C. In the above process, lithium and other metals can react and undergo phase transformation through the reaction according to [Reaction Formula 1]. In addition, other reactions can occur through [Reaction Formula 2] and [Reaction Formula 3].

[0056] [Reaction formula 1]

[0057] 9LiNi 1 / 3 Co 1 / 3 Mn 1 / 3 O2+0.25C→3NiO+3MnO2+Co3O4+4.5Li2O+0.25CO2(g)

[0058] [Reaction formula 2]

[0059] 4MnO2+C→2Mn2O3+CO2(g)

[0060] [Reaction formula 3]

[0061] Li2O+CO2(g)→Li2CO3

[0062] First leaching step S20

[0063] In the first leaching step S20 , the raw material containing nickel and lithium that has undergone phase transformation due to the reduction heat treatment step S10 may be leached.

[0064] The first leaching step S20 may be performed after the reduction heat treatment step S10. For example, the first leaching step S20 may be performed in a wet grinder. The wet grinder may be a ball mill, a rod mill, a bead mill, an attrition mill, or the like. The first leaching step may use a first leaching agent (e.g., a mineral acid, water, or a mixture thereof) to selectively leach the heat-treated lithium.

[0065] 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). The inorganic acid may be diluted with water, or sulfuric acid generated by capturing sulfur dioxide gas generated in the subsequent roasting step S30 may be used.

[0066] In one embodiment, water can be used as the first leaching agent. In this case, lithium in the form of lithium hydroxide (LiOH) can be leached from the lithium-containing raw material according to [Reaction Equation 4] to produce a first leached solution. The first leached solution can contain lithium.

[0067] [Reaction 4]Li2CO3+2H2O→2LiOH+H2O+CO2

[0068] 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 leaching residue.

[0069] The lithium concentration in the first leached solution obtained from the first leaching step can range from approximately 0.1 g / L to 8.5 g / L. This leached solution can be processed through well-known precipitation and crystallization methods to produce lithium hydroxide monohydrate (LiOH·H2O), lithium carbonate (Li2CO3), lithium phosphate (Li3PO4), and other materials for use as raw materials for lithium-ion battery cathode materials.

[0070] MHP and MCP generated in the lithium-ion battery recycling process, which may contain Li in addition to Ni, Co, and Mn, can be used as the first raw material for performing the first leaching process.

[0071] Calcination step S30

[0072] The calcination step S30 may be performed as a pretreatment step of the second raw material.

[0073] In the roasting process S30, the nickel-containing raw materials combined in various compounds undergo phase transformation, accompanied by recycling sulfur dioxide gas (SO2 gas) generated during the heat treatment process for producing the inorganic acid.

[0074] Before the roasting step S30 is performed, the nickel-containing second raw material may be in the form of a sulfide, which can be converted into an oxide according to the roasting step S30. Directly leaching the nickel-containing second raw material in the sulfide state will result in low leaching efficiency due to the generation of hydrogen sulfide gas (H2S gas) and metal reprecipitation reaction. Therefore, by converting the nickel-containing second raw material into a compound form through the roasting step S30 before performing the second leaching step S40, the leaching efficiency in the second leaching step S40 can be improved. In this regard, the roasting step S30 can be performed using heat treatment equipment such as an electric furnace (box furnace) or a rotary kiln.

[0075] According to one embodiment of the present invention, the roasting process S30 may include loading a certain amount of nickel-containing raw material into an electric furnace, injecting sufficient oxygen (O2) to convert it into nickel oxide, and roasting it at a temperature of 650°C to 950°C. During the above process, nickel and other impurities may react and undergo a phase transformation through the reaction described in the following [Reaction Formula 5]. In addition, sulfur dioxide gas generated during the roasting process S30 can be captured according to a separate collection facility and converted into sulfuric acid (H2SO4) by mixing with water, which can then be used in a subsequent leaching process.

[0076] [Reaction 5] 2NiS + 3O2 → 2NiO + 2SO2

[0077] Second leaching step S40

[0078] In the second leaching step S40, the calcined residue (calcined material) that has undergone a phase transformation according to the calcining step S30 and the first leaching residue remaining in the residue from the first leaching step S20 can be leached. The second leaching step S40 can be performed after both the calcining step S30 and the first leaching step. In the second leaching step, the calcined residue can be leached in a high-temperature, high-pressure reactor, while the first leaching residue can be leached in a normal-pressure reactor. The second leaching step S40 can use a second leaching agent (e.g., an inorganic acid or a mixture of an inorganic acid and water). In one embodiment, the second leaching step S40 can be performed using an inorganic acid. For example, at least one inorganic acid selected from the group consisting of sulfuric acid (H2SO4), hydrochloric acid (HCl), and nitric acid (HNO3), a water-diluted inorganic acid, or sulfuric acid generated by capturing sulfur dioxide gas generated in the previous calcining step S30 can be used.

[0079] In one embodiment, sulfuric acid may be used as the second leaching agent. In this regard, according to [Reaction Formula 6], nickel in the form of nickel sulfate (NiSO4) may be leached from the first leaching residue and the nickel-containing roasting residue to produce a second post-leaching solution.

[0080] [Reaction 6]NiO+H2SO4→NiSO4+H2O

[0081] The second leaching process S40 may be performed at a temperature of approximately 150 to 250° C. and a pressure of 800 to 4300 kPa. Saturated vapor pressure due to the high reaction temperature may result in maintaining a certain level of pressure, and additional pressure may be applied to complete the reaction.

[0082] For example, the second leaching step S40 can be performed in an environment with an acidity of 100 g / L to 200 g / L. The second leaching step S40 can be performed in a low pH acidic environment to obtain sufficient second leached liquid, and then the subsequent neutralization step S50 can be performed.

[0083] In one embodiment, nickel and 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 post-leaching solution.

[0084] The nickel concentration in the second leached solution obtained from the second leaching step S40 may be approximately 45 to 105 g / L, and the residual acidity may be 10 to 80 g / L.

[0085] Neutralization process S50

[0086] In the neutralization step S50, the second leached liquid generated in the second leaching step S40 may be neutralized. The neutralization step S50 may be performed after the second leaching step S40.

[0087] If the second post-leaching solution is processed in a high pH environment, the volume of the generated second post-leaching solution will be reduced.

[0088] In one embodiment, after the second leaching step S40 is performed in a low pH acidic environment to ensure sufficient second leached liquid, the neutralization step S50 may be performed.

[0089] In the neutralization step S50, a neutralizing agent may be introduced to increase the pH of the second leached solution generated in the second leaching step S40. Adding the neutralizing agent may also prepare for the subsequent purification step.

[0090] 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).

[0091] The reason for using MHP and MCP as raw materials and also as neutralizing agents may be because hydroxides and carbonates generally have high solubility in acid even without roasting, which eliminates the need for treatment under expensive high temperature and high pressure leaching conditions, and also consumes the acid (H2SO4) remaining after the second leaching step S40, thereby preparing in advance for the purification step S60 that occurs in the high pH range.

[0092] In one embodiment, in the neutralization step S50 , the nickel-containing byproduct can be used as a neutralizing agent in the form of a wet cake. Using the nickel-containing byproduct can reduce the amount of neutralizing agent added separately, thereby saving costs. Furthermore, the introduction of other impurities can be prevented, and the nickel concentration in the neutralized solution can be increased.

[0093] In one embodiment, the neutralization process S50 may be performed at a temperature of 80° C. and a pH of approximately 2 to 4.5. During the process, impurities including iron (Fe) and aluminum (Al) may be precipitated and removed.

[0094] Purification step S60

[0095] In the purification step S60 , impurities contained in the neutralized liquid generated in the neutralization step S50 can be removed, thereby purifying the neutralized liquid. The purification step S60 can be performed after the neutralization step S50 .

[0096] In one embodiment, the purification process S60 may include a first purification process S61 for removing impurities contained in the neutralized liquid generated by the neutralization process S50; a second purification process S62 for removing impurities contained in the first purified liquid generated by the first purification process S61; and a third purification process S63 for removing impurities contained in the second purified liquid generated by the second purification process S62.

[0097] First purification step S61

[0098] In the first purification step S61, the neutralized liquid generated in the neutralization step S50 can be purified. The neutralized liquid can be the neutralized leaching liquid. The first purification step S61 can be a step for removing impurities from the neutralized liquid after the neutralization step S50.

[0099] The first purification step S61 can be a precipitation method for removing impurities. In the first purification step S61, impurities can be removed using a sulfide precipitation method using at least one precipitant selected from the group consisting of sodium sulfide (Na2S), sodium hydrosulfide (NaSH), ammonium hydrosulfide (NH4HS), and hydrogen sulfide (H2S). This process recovers a precipitate primarily composed of copper sulfide (CuS) and containing impurities such as zinc, lead, and cadmium. The precipitate can then be processed into metallic copper through solvent extraction and substitution, or other purification steps.

[0100] Furthermore, in the first purification step S61, impurities can be removed using a hydroxide precipitation method using at least one selected from the group consisting of sodium hydroxide (NaOH), sodium carbonate (NaCO), calcium hydroxide (Ca(OH)), magnesium hydroxide (Mg(OH)), calcium oxide (CaO), and magnesium oxide (MgO). This process allows for the precipitation and removal of impurities such as aluminum (Al), iron (Fe), chromium (Cr), and silicon (Si). When sodium hydrosulfide is used as the precipitant, the reaction can be as shown in [Reaction Equation 7], and when sodium hydroxide is used, as shown in [Reaction Equation 8].

[0101] [Reaction 7] 2CuSO4 + 2NaSH → Na2SO4 + H2SO4 + 2CuS↓

[0102] [Reaction 8]MSO4+2NaOH→Na2SO4+M(OH)2↓(M=Al,Fe,Cr,Si)

[0103] During the sulfide precipitation process in the first purification step S61, the precipitant can be introduced at an equivalent ratio of approximately 1.0 to 2.5 relative to the copper contained in the neutralized solution. If the sulfide precipitant is introduced at an equivalent ratio of less than 1.0 relative to copper, the copper precipitation rate may be 83% or lower, indicating an incomplete reaction. If the sulfide precipitant is introduced at an equivalent ratio exceeding 2.5, impurities derived from the precipitant may excessively enter and negatively impact the process, potentially reducing the recovery rate due to co-precipitation of nickel. The above reaction can be carried out at a temperature of 70°C and a pH of 0.8 to 2.5.

[0104] In the purified hydroxide precipitation method, the precipitant can be introduced 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 introduced at an equivalent ratio of less than 0.8 relative to the impurities, the impurity removal rate may be 85% or less, indicating an incomplete reaction. When the precipitant is introduced at an equivalent ratio exceeding 1.5, excessive impurities from the precipitant may enter and negatively impact the process, potentially reducing the recovery rate due to nickel co-precipitation. The above reaction can be carried out at a temperature of 60°C and a pH of 2.5 to 4.5.

[0105] In the first purification step S61 , the contents of copper, iron, aluminum, and silicon in the first purified liquid can be reduced to 5 mg / L or less, respectively, and the contents of zinc, cobalt, and magnesium can be reduced to 20 mg / L or less, respectively.

[0106] Second purification step S62

[0107] The second purification step S62 may further purify the first purified liquid generated by the first purification step S61. The second purification step S62 may be performed after the first purification step S61 and may be a step of removing impurities by solvent extraction.

[0108] In the second purification process S62 , an organic extractant may be used to remove impurities such as zinc (Zn), magnesium (Mg), and manganese (Mn).

[0109] In one embodiment, the second purification step S62 may include a loading step and a stripping step. The organic extractant may be at least one selected from the group consisting of di-2-ethylhexyl phosphate, mono-2-ethylhexyl (2-ethylhexyl) phosphonate, and bis(2,4,4-trimethylpentyl)phosphinic acid.

[0110] The loading step may be a step for extracting impurities such as zinc, magnesium, manganese, or a combination thereof contained in the first purified liquid into an organic phase. The loading step may be a step for extracting zinc, magnesium, and manganese contained in the first purified liquid after the first purification step ( S61 ) into an organic phase using an organic extractant.

[0111] The volume ratio of the organic phase to the aqueous phase in the loading process can be approximately 1 to 3. When the volume ratio of the organic phase to the aqueous phase is less than 1, the extraction efficiency may decrease by 90% or less due to incomplete binding of the target metal and the organic extractant. An organic phase to aqueous phase volume ratio exceeding 3 increases process costs due to excessive use of the organic extractant. The pH range of the loading process can be controlled to 2.0 to 4.0 using at least one selected from the group consisting of sodium hydroxide (NaOH) or sodium carbonate (NaCO). Furthermore, the reaction temperature can be set to 30 to 40°C.

[0112] Once zinc, magnesium, and manganese are extracted into the organic phase by combining the aqueous and organic phases, phase separation due to the density difference between the organic and aqueous phases can result in the formation of a second purified stream. The second purified stream, now free of zinc and magnesium, can contain nickel at a concentration of 50 to 100 g / L.

[0113] The organic phase containing zinc and magnesium may undergo a stripping step. In this stripping step, a mineral acid may be added to the organic phase after the loading step to remove impurities. This stripping step may be a stripping step to extract the zinc, magnesium, and manganese contained in the organic phase back into the aqueous phase.

[0114] The volume ratio of the organic phase to the aqueous phase in the stripping process can be approximately 5 to 10. When the volume ratio of the organic phase to the aqueous phase in the stripping process is less than 5, water consumption may increase while simultaneously completely extracting impurities. When the volume ratio of the organic phase to the aqueous phase in the stripping process is greater than 10, the efficiency of impurity stripping may decrease. The pH range of the loading process can be approximately 0.5 to 1.5. In the stripping process, sulfuric acid (H2SO4) can be used to control the pH range to approximately 0.5 to 1.5. In addition, the reaction temperature can be set to 30 to 40°C.

[0115] Third purification step S63

[0116] The third purification step S63 further purifies the second purified liquid generated by the second purification step S62. The third purification step S63 may be performed after the second purification step S62. The third purification step S63 may be a step that removes impurities using solvent extraction techniques. In the third purification step S63, an organic extractant may be used to remove impurities including cobalt. In one embodiment, the third purification step S63 may include a loading step and a removal step. The organic extractant may be 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.

[0117] In the loading process, cobalt-containing impurities may be extracted from the second purified liquid into an organic phase. The loading process may be a process in which an organic extractant is used to extract cobalt from the second purified liquid after the second purification process S62 into an organic phase.

[0118] The volume ratio of the organic phase to the aqueous phase in the loading process can be approximately 1 to 3. When the volume ratio of the organic phase to the aqueous phase is less than 1, the target metal is not fully bound to the organic extractant, resulting in an extraction rate of 90% or less. An organic phase to aqueous phase volume ratio exceeding 3 results in excessive use of the organic extractant, increasing process costs. At least one of sodium hydroxide (NaOH) or sodium carbonate (NaCO) can be used to control the pH range of the loading process to 4 to 5. Furthermore, the reaction temperature can be maintained at 30°C to 40°C.

[0119] Once the cobalt is extracted into the organic phase by combining the aqueous and organic phases, the difference in specific gravity between the organic and aqueous phases allows for phase separation. This phase separation produces a third purified solution, which is a cobalt-depleted nickel-containing aqueous solution having a nickel content of 65 to 125 g / L.

[0120] The organic phase containing cobalt may be subjected to a removal step.

[0121] In the removal process after the loading process, a mineral acid may be added to the organic phase to remove the cobalt contained in the organic phase. The removal process may be a stripping process for pulling the cobalt from the organic phase back into the aqueous phase.

[0122] The volume ratio of the organic phase to the aqueous phase in the stripping process can be approximately 3 to 10. When the volume ratio of the organic phase to the aqueous phase in the stripping process is less than 3, water consumption may increase while simultaneously completely extracting impurities. When the volume ratio of the organic phase to the aqueous phase in the stripping process is greater than 10, the efficiency of impurity stripping may decrease. The pH range of the loading process can be approximately 0.5 to 1.5. In the stripping process, sulfuric acid (H2SO4) can be used to control the pH range to approximately 0.5 to 1.5. In addition, the reaction temperature can be set to 30 to 40°C.

[0123] Once the cobalt is extracted into the organic phase by combining the aqueous and organic phases, the difference in specific gravity between the organic and aqueous phases allows for phase separation. This phase separation produces a cobalt-containing solution that can be further purified by precipitation and crystallization to provide high-purity cobalt sulfate.

[0124] Precipitation step S70

[0125] The precipitation step S70 may be performed to precipitate the purified liquid (eg, the third purified liquid) generated by the purification step S60 (eg, the third purification step S63). The precipitation step S70 may be performed after the third purification step S63.

[0126] Precipitation step S70 may be a step in which nickel is precipitated using a precipitation method to remove impurities. In precipitation step S70, at least one selected from the group consisting of sodium hydroxide (NaOH), calcium hydroxide (Ca(OH)2), magnesium hydroxide (Mg(OH)2), calcium oxide (CaO), and magnesium oxide (MgO) may be used as a precipitant for precipitating nickel.

[0127] When sodium hydroxide is used as the precipitant, the reaction can be represented by the following reaction formula 9.

[0128] [Reaction 9]NiSO4+2NaOH+xH2O→Ni(OH)2+Na2SO4+xH2O(x≥0)

[0129] The precipitation step S70 can be performed at a temperature of 75 to 85° C. and a pH of 6.5 to 10.0. A pH below 6.5 results in a nickel recovery rate of less than 80%. When the pH exceeds 10.0, impurities caused by the precipitant are increased and introduced, negatively impacting the process and reducing cost-effectiveness due to excessive use of the precipitant.

[0130] Impurities including sodium (Na) and potassium (K) can be partially removed in the precipitation step S70. For example, after the precipitation reaction, the steps of recovering the nickel-containing precipitate by solid-liquid separation and washing with dilute acid and water can remove at least a portion of the impurities.

[0131] The nickel-containing precipitation residue produced by the present invention can be dried to be used as a nickel compound in the form of a powder, and can be further processed to be used as a precursor nickel raw material for a positive active material of a lithium-ion battery.

[0132] Experimental example

[0133] [raw material]

[0134] As shown in Table 3 below, the elements in Table 3 were mixed at predetermined ratios to prepare first raw materials A to C.

[0135] Table 3 (Unit: wt%)

[0136] Ni Li Co Cu Fe Zn Mg Al Mn A 26.0 4.5 5.0 0.7 0.01 0.005 0.004 0.5 4.5 B 12.0 0.001 0.3 2.7 34.0 0.02 2.0 0.4 0.02 C 35.0 0.1 3.0 0.01 0.05 0.5 3.0 0.06 6.0

[0137] *In addition to the above metal ions, the first raw material contains sulfur (S), oxygen (O) and hydrogen (H) ions to form 100 weight percent.

[0138] The second raw material was prepared to contain the elements shown in Table 4 below.

[0139] Table 4 (Unit: wt%)

[0140] Ni Fe Co Cu Zn Mn Mg Al S 13.6 32.8 0.3 2.0 0.02 0.02 2.5 0.4 25.7

[0141] *In addition to the above metal ions, the second raw material contains oxygen (O) and hydrogen (H) ions to form 100 weight percent.

[0142] [Reduction heat treatment process]

[0143] A reduction heat treatment is performed on the first raw material containing nickel, lithium, etc. Specifically, 2.0 kg of the raw material is loaded into a rotary kiln and then subjected to a reduction heat treatment at 850° C. for 3 hours while maintaining a reducing atmosphere using N2 gas to provide a residue after the reduction heat treatment in which lithium oxide (Li2O) is converted into lithium carbonate (Li2CO3).

[0144] [First leaching step]

[0145] Lithium recovery was performed by water leaching the residue after the reduction heat treatment. Specifically, 100 g of the raw material was loaded into a ball mill, then ground with 2.5 L of water (HO) and water leached for 2 hours. Solid-liquid separation using vacuum filtration then produced a first leaching residue containing the elements listed in Table 5, and a first post-leaching solution containing the elements listed in Table 6.

[0146] Table 5 (Unit: wt%)

[0147] Ni Co Fe Mg Al Cu Mn Zn 36.0 7.0 0.02 0.001 0.6 0.9 6.5 0.007

[0148] *In addition to the above metal ions, it also contains oxygen (O) and hydrogen (H) ions to form 100 weight percent.

[0149] Table 6 (unit: g / L)

[0150] Li Na Co Fe Mg Al Cu Mn Zn 1.8 24.0 0.1 0.02 0.01 0.05 0.1 0.05 0.01

[0151] [Baking process]

[0152] The second raw material containing nickel and sulfur was subjected to a roasting process. Briefly, 2 kg of the raw material was loaded into a rotary kiln and roasted at 850° C. for 3 hours while fully injecting oxygen (O 2 ) to obtain a roasting residue (calcined material) in which nickel sulfide (NiS) was converted into nickel oxide (NiO).

[0153] [Second leaching step]

[0154] The raw materials in which the residue after the reduction heat treatment and the residue after the roasting are mixed in a weight ratio of 2:8 are subjected to high temperature and high pressure leaching.

[0155] In an autoclave, a mixture of 450 g of the mixed raw material and 3 L of water was maintained at an initial acidity of 120 g / L and a temperature of 240° C. at 3500 kPa for 3 hours to provide a second post-leaching solution having a nickel leaching rate of 95% and a nickel concentration of 60 g / L.

[0156] [Neutralization process]

[0157] The neutralization process is carried out using the nickel-containing by-products in the second leaching solution.

[0158] The pH of 2 L of the second leached solution was controlled at 2.5 by adding the nickel-containing by-product, and simultaneously maintained at 80° C. for 3 hours, to obtain a neutralized solution having a nickel concentration of 82 g / L.

[0159] [First purification step]

[0160] The first purification step is performed using a precipitation method to remove impurities contained in the neutralized liquid.

[0161] By adding 1.3 equivalents (eq) of sodium hydrosulfide (NaSH) to the copper (Cu) content in the neutralized solution and maintaining the pH at 2.5 at 70° C. for 2 hours, 99.8% of copper was removed. Furthermore, by maintaining the pH of the neutralized solution at 4.5 for 2 hours using a nickel-containing byproduct and sodium hydroxide (NaOH), a first purified solution was provided in which 99.5% or more of impurities including aluminum, iron, and silicon were removed.

[0162] [Second purification step]

[0163] The second purification step is performed using a solvent extraction method to remove impurities contained in the first purified liquid.

[0164] Impurities including zinc and magnesium were removed by extraction. In this regard, 500 mL of the first purified liquid was mixed with 1,000 mL of 25% diluted di-2-ethylhexylphosphoric acid as an extractant, and the mixture was agitated at 40°C and pH 3.5 for 10 minutes. Phase separation based on specific gravity differences enabled extraction of 99% of zinc and 43% of magnesium. Using a countercurrent exchange method in a mixer-settler, the impurities were completely extracted.

[0165] [Third purification step]

[0166] The third purification step is performed using a solvent extraction method to remove cobalt contained in the second purified liquid.

[0167] A mixture of 500 mL of the cobalt-containing second purified liquid and 1,000 mL of 25% diluted bis(2,4,4-trimethylpentyl)phosphinic acid as an extractant was stirred at 40°C and pH 5.0 for 10 minutes. Phase separation due to specific gravity differences allowed the extraction of approximately 55% of the cobalt. Using a countercurrent exchange method in a mixer-settler, impurities were completely extracted.

[0168] The above-described procedure enables the removal of cobalt to a level of 3 mg / L or less to provide a third purified solution containing the elements given in Table 7 below.

[0169] Table 7 (Unit: mg / L)

[0170] Ni Co Fe Mg Al Cu Mn Zn 58g / L 2.5 0.01 0.2 0.01 0.01 0.05 0.001

[0171] [Precipitation process]

[0172] The precipitation step is performed to recover nickel contained in the third purified liquid in the form of a precipitate.

[0173] 1 L of the third purified solution containing 42 g / L nickel was maintained at 85° C. and pH 8.0 for 2 hours using sodium hydroxide (NaOH). Solid-liquid separation was performed using vacuum filtration, and then rinsed with 1 L of distilled water (DIW) to provide a precipitate residue containing the elements shown in Table 8.

[0174] Table 8 (Unit: wt%)

[0175] Ni Co Fe Mg Al Cu Mn Zn 43 0.01 0.01 5.0 0.01 0.01 0.7 0.01

[0176] Although the embodiments of the present invention have been described with reference to the accompanying drawings, it will be understood by those skilled in the art that the above-described embodiments may be implemented in other specific forms without changing the technical spirit and essential features of the present invention.

[0177] Therefore, it should be understood that the above embodiments are illustrative and non-restrictive in all respects. The scope of the present invention is defined by the scope of the invention claims rather than the detailed description. It should be understood that all changes and modifications derived from the meaning and scope of the invention claims and their equivalents are included within the scope of the present invention.

Claims

1. A nickel smelting method, characterized in that: include: (Ai) a reduction heat treatment step for heat-treating the first raw material containing nickel and lithium; (B) a first leaching step for leaching the heat-treated product generated by the reduction heat treatment step; (A-ii) a roasting step for heat-treating the second raw material containing nickel and sulfur; (C) a second leaching step for leaching the first leaching residue produced in the first leaching step and the calcined material produced in the roasting step; (D) a neutralization step for neutralizing the second leached liquid generated in the second leaching step; (E) a purification step for removing impurities contained in the neutralized liquid generated in the neutralization step; and (F) a precipitation step of recovering nickel from the purified solution produced by the purification step. Nickel hydroxide is recovered according to the above-mentioned precipitation process.

2. The nickel smelting method according to claim 1, characterized in that The above-mentioned first raw material and the above-mentioned second raw material each independently contain at least one selected from the group consisting of oxides, hydroxides, sulfides and sulfur oxides, and the above-mentioned oxides, hydroxides, sulfides and sulfur oxides each independently contain concentrates, ice ores, black substances, black powders, mixed hydroxide precipitates, mixed carbonate precipitates, mixed sulfide precipitates or mixtures thereof.

3. The nickel smelting method according to claim 1, characterized in that: The first raw material includes nickel in the form of nickel oxide or nickel metal composite oxide.

4. The nickel smelting method according to claim 1, characterized in that: The second raw material includes nickel in the form of nickel sulfide.

5. The nickel smelting method according to claim 1, characterized in that: The reduction heat treatment step is performed at a temperature of 650° C. to 950° C. by introducing the first raw material into a heat treatment device and injecting nitrogen.

6. The nickel smelting method according to claim 1, characterized in that: The first leaching step is performed using a first leaching agent comprising an inorganic acid, water or a mixture thereof.

7. The nickel smelting method according to claim 1, characterized in that: The first leached liquid obtained from the first leaching step contains lithium, and the first leaching residue contains nickel.

8. The nickel smelting method according to claim 1, characterized in that: The calcination process is performed by introducing the second raw material into a heat treatment device at a temperature of 650° C. to 950° C. and injecting oxygen.

9. The nickel smelting method according to claim 1, characterized in that: In the second leaching step, the first leaching residue is leached in a normal pressure reactor, and the calcined material is leached in a high temperature and high pressure reactor.

10. The nickel smelting method according to claim 1, characterized in that: The second leaching process is performed using a second leaching agent comprising an inorganic acid, water or a mixture thereof.

11. The nickel smelting method according to claim 1, characterized in that: The second leaching step is performed at a temperature of 150° C. to 250° C. and a pressure of 800 kPa to 4300 kPa.

12. The nickel smelting method according to claim 1, characterized in that: The second leaching step is carried out in an environment with an acidity of 100 g / L to 200 g / L.

13. The nickel smelting method according to claim 1, characterized in that: The neutralization step is performed using a neutralizing agent, which includes a mixed hydroxide precipitate, a mixed carbonate precipitate, nickel hydroxide, nickel carbonate, sodium hydroxide, sodium carbonate, calcium hydroxide, magnesium hydroxide, calcium oxide, magnesium oxide or a mixture thereof.

14. The nickel smelting method according to claim 1, characterized in that: The neutralization step is performed at a temperature of 80° C. and a pH of 2 to 4.

5.

15. The nickel smelting method according to claim 1, characterized in that: The above purification process includes: (Ei) a first purification step for removing impurities contained in the neutralized liquid generated in the neutralization step; (E-ii) a second purification step for removing impurities contained in the first purified liquid produced in the first purification step; and (E-iii) A third purification step for removing impurities contained in the second purified liquid generated in the second purification step.

16. The nickel smelting method according to claim 15, characterized in that: The first purification step uses a precipitation method to remove impurities including copper, iron, aluminum, silicon, zinc, cobalt, magnesium or a combination thereof.

17. The nickel smelting method according to claim 15, characterized in that: The first purification step is performed by (i) adding a sulfide precipitating agent in an amount of 1.0 to 2.5 equivalents of the copper content in the neutralized liquid to the sulfide precipitation step of the neutralized liquid, (ii) adding a hydroxide precipitating agent in an amount of 0.8 to 1.5 equivalents of the impurity content in the neutralized liquid to the hydroxide precipitation step of the neutralized liquid, or a combination of (i) and (ii).

18. The nickel smelting method according to claim 15, characterized in that: The second purification step uses a solvent extraction method to remove impurities including zinc, magnesium, manganese or a combination thereof.

19. The nickel smelting method according to claim 15, characterized in that: The second purification step includes: (i) a loading step of adding a first solvent extractant to the first purified liquid to extract impurities including zinc, magnesium, manganese or a combination thereof into an organic phase; and (ii) a removal step of adding an inorganic acid to the organic phase to extract impurities including zinc, magnesium, manganese or a combination thereof contained in the organic phase into the aqueous phase.

20. The nickel smelting method according to claim 15, characterized in that: The third purification step uses a solvent extraction method to remove impurities including cobalt.

21. The nickel smelting method according to claim 15, characterized in that: The third purification step includes: (i) a loading step of adding a second solvent extractant to the second purified liquid to extract impurities including cobalt into an organic phase; and (ii) A removal step of adding an inorganic acid to the organic phase to extract impurities including cobalt contained in the organic phase into the aqueous phase.

22. The nickel smelting method according to claim 1, characterized in that: The precipitation step is carried out using a precipitant comprising sodium hydroxide, calcium hydroxide, magnesium hydroxide, calcium oxide, magnesium oxide or a mixture thereof.

23. The nickel smelting method according to claim 1, characterized in that: The precipitation step is performed at a temperature of 85° C. and a pH of 6.5 to 10.0.

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