All-in-one nickel smelting process for recovering nickel metal from nickel-containing raw materials

Abstract

The present invention provides a nickel smelting method, comprising: (A-i) a reduction heat treatment step of heat-treating a first feedstock containing nickel and lithium; (B) a first leaching step of leaching a heat-treated product produced by the reduction heat treatment step; (A-ii) a roasting step of heat-treating a second feedstock containing nickel and sulfur; (C) a second leaching step of leaching the first leach residue produced by the first leaching step and the roasted ore produced by the roasting step; (D) a neutralization step of neutralizing the second leach solution produced by the second leaching step; (E) a purification step of removing impurities contained in the neutralized solution produced by the neutralization step; and (F) a reduction step of subjecting the purified solution produced by the purification step to a hydrogen reduction method in order to recover nickel from the purified solution.

Description

[Technical Field]

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

[0002] Nickel can be recovered using a variety of raw materials, such as nickel metal, nickel matte, nickel concentrate, and nickel-containing process by-products. Nickel sulfate, one of the various forms of nickel recovery, is known to have a nickel sulfate content of 99% or more and other impurity contents of several hundred ppm or less.

[0003] In order to produce such nickel sulfate, conventionally, a high-purity aqueous solution of nickel sulfate is produced by leaching at normal pressure using an inorganic acid, neutralizing with sodium hydroxide or sodium carbonate, etc., and removing impurities, and then crystallizing this to produce nickel sulfate hexahydrate.

[0004] However, in the conventional method, raw materials that are soluble in specific inorganic acids are limited, and in order to remove substances (e.g., Na) added as a neutralizing agent, a method of removing Na by washing with water after sludge filtration was used. However, this method has the disadvantages of increasing the amount of wastewater and requiring a long process time, resulting in a decrease in production volume and an increase in wastewater treatment costs. Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention aims to provide an all-in-one process that is a hybrid process that combines pyrometallurgy and hydrometallurgy to recover high-purity nickel from a nickel-containing composite raw material, which is flexible even when various nickel-containing raw materials are used, and can obtain nickel in a desired form by appropriately applying subsequent processes.

[0006] The present invention aims to provide an environmentally friendly process that allows for recycling of process by-products.

[0007] The present invention aims to provide an economical and environmentally friendly nickel smelting process that can be applied to complex raw materials in a single process by combining a recycling hydrometallurgical process that enables selective separation of lithium and conversion of complex compounds into single compounds through pretreatment using a pyrometallurgical process, and recovery of inorganic acids from harmful gases, and minimizes the inflow of sodium impurities. [Means for solving the problem]

[0008] One aspect of the present invention relates to a nickel smelting method, comprising: (A-i) a reduction heat treatment step of heat-treating a first feedstock containing nickel and lithium; (B) a first leaching step of leaching a heat-treated product produced by the reduction heat treatment step; (A-ii) a roasting step of heat-treating a second feedstock containing nickel and sulfur; (C) a second leaching step of leaching a first leach residue produced by the first leaching step and roasted ore produced by the roasting step; (D) a neutralization step of neutralizing a second leach solution produced by the second leaching step; (E) a purification step of removing impurities contained in the neutralized solution produced by the neutralization step; and (F) a reduction step of subjecting the purified solution produced by the purification step to a hydrogen reduction method to recover nickel from the purified solution.

[0009] An embodiment of the present invention may provide a method for smelting nickel, wherein the first and second raw materials each independently include at least one selected from the group consisting of oxide, hydroxide, sulfide, and sulfur oxide, and the oxide, hydroxide, sulfide, and sulfur oxide each independently include ore, matte, black mass (BM), black powder (BP), mixed hydroxide precipitate (MHP), mixed carbonate precipitate (MCP), mixed sulfide precipitate (MSP), or a mixture thereof.

[0010] An embodiment of the present invention may provide a method for smelting nickel, wherein the first raw material contains nickel in the form of nickel oxide or nickel metal composite oxide.

[0011] An embodiment of the present invention may provide a method for smelting nickel, wherein the second raw material contains nickel in the form of nickel sulfide.

[0012] In one embodiment of the present invention, there is provided a method for smelting nickel, wherein the reduction heat treatment process is carried out at a temperature of 650 to 950°C by feeding the first raw material into a heat treatment device and injecting nitrogen gas.

[0013] One embodiment of the present invention may provide a method for smelting nickel, wherein the first leaching step is carried out using a first leaching agent including an inorganic acid, water, or a mixture thereof.

[0014] In one embodiment of the present invention, there is provided a method for smelting nickel, wherein the first leach solution obtained in the first leaching step contains lithium, and the first leach residue contains nickel.

[0015] In one embodiment of the present invention, there is provided a method for smelting nickel, wherein the roasting step is carried out at a temperature of 650 to 950°C by feeding the second raw material into a heat treatment device and injecting oxygen gas.

[0016] In one embodiment of the present invention, there is provided a method for smelting nickel, wherein in the second leaching step, the first leaching residue is leached in an atmospheric pressure reactor, and the roasted ore is leached in a high-temperature, high-pressure reactor.

[0017] One embodiment of the present invention may provide a method for smelting nickel, wherein the second leaching step is carried out using a second leaching agent including an inorganic acid, water, or a mixture thereof.

[0018] In one embodiment of the present invention, there is provided a method for smelting nickel, wherein the second leaching step is carried out at a temperature of 150 to 250° C. and a pressure of 800 to 4,300 kPa.

[0019] One embodiment of the present invention provides a method for smelting nickel, wherein the second leaching step is carried out in an atmosphere having an acidity of 100 to 200 g / L.

[0020] One embodiment of the present invention provides a method for smelting nickel, wherein the neutralization step is performed using a neutralizing agent including MHP, MCP, nickel hydroxide (Ni(OH)), nickel carbonate (NiCO), sodium hydroxide (NaOH), sodium carbonate (NaCO), calcium hydroxide (Ca(OH)), magnesium hydroxide (Mg(OH)), calcium oxide (CaO), magnesium oxide (MgO), or a mixture thereof.

[0021] In one embodiment of the present invention, there is provided a method for smelting nickel, wherein the neutralization step is carried out under conditions of 80° C. and pH 2 to 4.5.

[0022] One embodiment of the present invention can provide a nickel smelting method, wherein the purification step includes: (E-i) a first purification step of removing impurities contained in the neutralized solution produced by the neutralization step; (E-ii) a second purification step of removing impurities contained in the first purified solution produced by the first purification step; and (E-iii) a third purification step of removing impurities contained in the second purified solution produced by the second purification step.

[0023] In one embodiment of the present invention, there is provided a method for smelting nickel, wherein the first purification step utilizes a precipitation method to remove impurities including copper, iron, aluminum, silicon, zinc, cobalt, magnesium, or a combination thereof.

[0024] In one embodiment of the present invention, there is provided a method for refining nickel, wherein the first purification step is carried out by (i) a sulfurization precipitation step of adding a sulfide precipitant to the neutralized solution in an amount of 1.0 to 2.5 equivalents of the copper content in the neutralized solution, (ii) a hydroxide precipitation step of adding a hydroxide precipitant to the neutralized solution in an amount of 0.8 to 1.5 equivalents of the impurity content in the neutralized solution, or a combination of (i) and (ii).

[0025] In one embodiment of the present invention, there is provided a method for refining nickel, wherein the second refining step utilizes a solvent extraction method to remove impurities including zinc, magnesium, manganese, or a combination thereof.

[0026] In one embodiment of the present invention, there is provided a method for refining nickel, wherein the second refining step includes (i) a loading step of adding a first solvent extractant to the first refined solution to extract impurities including zinc, magnesium, or a combination thereof into an organic phase, and (ii) a stripping step 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.

[0027] In one embodiment of the present invention, there is provided a method for refining nickel, wherein the third refining step uses solvent extraction to remove impurities including cobalt.

[0028] In one embodiment of the present invention, there is provided a method for refining nickel, wherein the third purification step includes (i) a loading step of adding a second solvent extractant to the second purified solution to extract impurities containing cobalt into an organic phase, and (ii) a stripping step of adding an inorganic acid to the organic phase to extract impurities containing cobalt contained in the organic phase into an aqueous phase.

[0029] In one embodiment of the present invention, there is provided a method for refining nickel, wherein the reduction step includes: (i) an ammonium precipitation step of adding an ammonium precipitant in an amount of 2 to 2.5 equivalents of the nickel content in the refined solution; (ii) a hydrogen reduction step of adding hydrogen gas to the refined solution at a flow rate of 30 to 60 NL / hr; (iii) a growth step of growing nickel metal powder particles by mixing nickel metal powder seeds produced in the hydrogen reduction step with the refined solution; or a combination of (i) to (iii).

[0030] One embodiment of the present invention may provide a method for smelting nickel, wherein the reduction step is carried out using an additive including iron sulfate, aluminum sulfate, polyacrylic acid, or a combination thereof.

[0031] In one embodiment of the present invention, there is provided a method for refining nickel, wherein the reduction step is carried out under conditions of 160 to 200° C. and pH 8.0 to 9.0. [Effects of the Invention]

[0032] According to the present invention, it is possible to selectively leach and recover lithium by heat treating a raw material containing lithium in a strongly chemically bonded form using a reduction heat treatment process.

[0033] According to the present invention, nickel-containing raw materials having various chemical bond forms are converted into a single phase using a roasting process, thereby ensuring the uniformity of subsequent processes and improving the usability of the entire process to enable flexible response to the rapidly changing nickel raw material market. [Brief explanation of the drawings]

[0034] [Figure 1] FIG. 1 is a diagram illustrating an overall process for smelting nickel and producing nickel metal according to one embodiment of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0035] The examples of the present invention are provided for the purpose of explaining the technical concept of the present invention, and the scope of the invention is not limited to the examples presented below or the specific descriptions of these examples.

[0036] In this specification, "%" is understood to be measured on a weight (wt) basis unless otherwise specified.

[0037] The present invention will now be described with reference to the drawings.

[0038] FIG. 1 is a diagram illustrating an overall process for smelting nickel and producing nickel metal according to one embodiment of the present invention.

[0039] Referring to Figure 1, a method for smelting nickel to high purity through a series of steps and producing nickel metal using such nickel can be provided. This method can improve versatility for a variety of raw materials and products, operational stability, and purity, and reduce production costs. Each step will be described in detail below with reference to each drawing.

[0040] raw material

[0041] The first and second raw materials, which are starting materials of the present invention, are composite raw materials mainly containing nickel and may each independently include at least one selected from the group consisting of oxide, hydroxide, sulfide, and sulfur oxide. For example, the oxide, hydroxide, sulfide, and sulfur oxide may each independently include ore, matte, black mass (BM), black powder (BP), mixed hydroxide precipitate (MHP), mixed carbonate precipitate (MCP), mixed sulfide precipitate (MSP), or a mixture 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 contain impurities such as iron (Fe), cobalt (Co), copper (Cu), zinc (Zn), magnesium (Mg), sodium (Na), silicon (Si), or a combination thereof, in addition to nickel (Ni) and lithium (Li). For example, the composition of the first raw material may be as shown in Table 1 below. For example, the first raw material may contain nickel in the form of nickel oxide (NiO) or a nickel-metal composite oxide mixed with other metals.

[0043] (unit: wt%) [Table 1]

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

[0046] Reduction heat treatment step (S10)

[0047] As a pre-treatment process of the first raw material, a reduction heat treatment process (S10) may be performed.

[0048] In the reduction heat treatment step (S10), a first raw material containing nickel and lithium in the form of a composite oxide capable of bonding with various metals may be subjected to a heat treatment in a reducing atmosphere to cause a phase change to an oxide and / or carbonate, thereby converting the lithium-containing compound into a substance that is highly soluble in water or an inorganic acid.

[0049] In this way, by converting the compound form of the lithium-containing first raw material through the reduction heat treatment step (S10) before performing the first leaching step (S20) of leaching / extracting lithium, which will be described later, the leaching efficiency in the first leaching step (S20) of leaching / extracting lithium can be improved.

[0050] For example, the reduction heat treatment step (S10) can be carried out using heat treatment equipment such as an electric furnace (for example, a box furnace), a rotary kiln, or the like.

[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 introducing the first raw material into a heat treatment device and injecting nitrogen gas. For example, a certain amount of the first raw material may be introduced into the heat treatment device, and nitrogen gas (N2 gas) may be injected sufficiently to maintain a reducing atmosphere, and the reduction heat treatment may be performed at a temperature of 650 to 950°C. During this process, not only lithium but also other metals may react, causing a phase change according to the following [Reaction Scheme 1]. Additionally, additional reactions may occur according to the following [Reaction Scheme 2] and [Reaction Scheme 3].

[0052] [Reaction Scheme 1]

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

[0054] [Reaction Scheme 2]

[0055] 4MnO2+C→2Mn2O3+CO2(g)

[0056] [Reaction Scheme 3]

[0057] Li2O+CO2(g) → Li2CO3

[0058] 1st leaching process (S20)

[0059] In the first leaching step (S20), the nickel and lithium-containing raw material that has undergone a phase change due to the reduction heat treatment step (S10) can be leached.

[0060] 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 mill. The wet mill may be a ball mill, rod mill, bead mill, attrition mill, etc. The first leaching step 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 (HSO), hydrochloric acid (HCl), and nitric acid (HNO), or an inorganic acid diluted with water may be used. Alternatively, sulfuric acid produced by collecting sulfur dioxide gas generated in the subsequent roasting step (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 lithium hydroxide (LiOH) according to the following [Reaction Scheme 4] to produce a first leaching solution. The first leaching solution may contain lithium.

[0063] [Reaction 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 step can be about 0.1 to 8.5 g / L, which can be processed into lithium hydroxide (LiOH·H2O), lithium carbonate (Li2CO3), lithium phosphate (Li3PO4), etc. through commonly known precipitation and crystallization methods to be used as a raw material for the cathode of lithium-ion batteries.

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

[0067] Roasting process (S30)

[0068] As a pre-treatment process of the second raw material, a roasting process (S30) may be performed.

[0069] In the roasting process (S30), the phase change of the nickel-containing raw material combined with various compounds can occur, and inorganic acid can be produced by recycling sulfur dioxide gas (SO2 gas) generated during the heat treatment process.

[0070] Before the roasting step (S30), the nickel-containing second raw material may be in the form of sulfide, which may be converted to oxide through the roasting step (S30). If the nickel-containing second raw material is leached in the sulfide state, hydrogen sulfide gas (HS gas) is generated, resulting in a metal reprecipitation reaction and a low leaching rate. Therefore, by converting the compound form of the nickel-containing second raw material through the roasting step (S30) before performing the second leaching step (S40), the leaching efficiency in the second leaching step (S40) can be improved. Here, the roasting step (S30) may be performed using heat treatment equipment such as an electric furnace (box furnace) or a rotary kiln.

[0071] According to one embodiment of the present invention, the roasting step (S30) involves charging a certain amount of nickel-containing raw material into an electric furnace, injecting sufficient oxygen (O2) to convert it into nickel oxide, and roasting at 650-950°C. During this process, not only nickel but also other impurities react with each other, causing a phase change according to the following reaction formula (Reaction 5). In addition, sulfur dioxide gas generated during the roasting step (S30) can be mixed with water through a separate collection facility to produce sulfuric acid (H2SO4), which can then be used in the subsequent leaching step.

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

[0073] 2nd leaching process (S40)

[0074] In the second leaching step (S40), the first leaching residue remaining in the residue from the first leaching step (S20) can be leached together with the roasted residue (roaster) that has undergone a phase change in the roasting step (S30). The second leaching step (S40) can be performed after the roasting step (S30) and the first leaching step. In the second leaching step, the roasted residue can be leached in a high-temperature, high-pressure reactor, and the first leaching residue can be leached in an atmospheric pressure reactor. In the second leaching step (S40), leaching can be performed using a second leaching agent (e.g., an inorganic acid, water, or a mixture thereof). In one embodiment, the second leaching step (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 (HSO), hydrochloric acid (HCl), and nitric acid (HNO), or an inorganic acid diluted with water may be used. Alternatively, sulfuric acid produced by capturing sulfur dioxide gas generated in the previous roasting step (S30) may be used.

[0075] In one embodiment, sulfuric acid may be used as the second leaching agent. In this case, nickel may be leached from the nickel-containing first leach residue and the roasted residue in the form of nickel sulfate (NiSO4) to produce a second leach solution according to the following [Reaction Scheme 6]:

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

[0077] The second leaching step (S40) can be carried out at a temperature of about 150-250°C and a pressure of 800-4,300 kPa. As the reaction temperature increases, a constant pressure is maintained due to the saturated water vapor pressure, and additional pressure can be applied to ensure complete reaction.

[0078] For example, the second leaching step (S40) may be carried out in an atmosphere with an acidity of 100 to 200 g / L. After the second leaching step (S40) is carried out in an acidic atmosphere with a low pH to obtain a sufficient amount of second leaching solution, the subsequent neutralization step (S50) may be carried out.

[0079] In one embodiment, other impurities may be co-leached with nickel, for example, iron (Fe), cobalt (Co), copper (Cu), zinc (Zn), etc. may be co-leached with nickel and included in the second leach solution.

[0080] The nickel concentration of the second leaching solution obtained in the second leaching step (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 step (S50), the second post-leaching solution produced in the second leaching step (S40) may be neutralized. The neutralization step (S50) may be carried out after the second leaching step (S40).

[0083] If the second post-leaching solution is produced in an atmosphere with a high pH, ​​less second post-leaching solution may be produced.

[0084] In one embodiment, the second leaching step (S40) is carried out in an acidic atmosphere with a low pH to ensure sufficient second leaching solution, after which the neutralization step (S50) can be carried out.

[0085] In the neutralization step (S50), a neutralizing agent may be added to increase the pH of the second leaching solution produced in the second leaching step (S40), and the addition of the neutralizing agent may also be for the purpose of a subsequent purification step.

[0086] In one embodiment, the neutralizing agent may be at least one selected from the group consisting of nickel-containing by-products (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] Although MHP and MCP are used as raw materials, they are also used as neutralizers because hydroxides and carbonates generally have high solubility in acids without roasting, eliminating the need for high-temperature, high-pressure leaching conditions, which are costly to process. Furthermore, the acid (H2SO4) remaining after the second leaching step (S40) is consumed, providing an advantage in advance for the refining step (S60), which is carried out in a high pH range.

[0088] In one embodiment, the neutralization step (S50) may be performed using a nickel-containing by-product in the form of a cake containing moisture as a neutralizing agent. When the nickel-containing by-product is used, the amount of neutralizing agent added separately can be reduced, thereby saving costs. In addition, the inflow of additional impurities can be prevented, and the nickel concentration in the neutralized solution can be increased.

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

[0090] Purification process (S60)

[0091] In the purification step (S60), impurities contained in the neutralized solution produced in the neutralization step (S50) are removed, and the neutralized solution can be purified. The purification step (S60) can be performed after the neutralization step (S50).

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

[0093] 1st purification step (S61)

[0094] In the first purification step (S61), the neutralized solution produced in the neutralization step (S50) can be purified. The neutralized solution can be a neutralized leaching solution. The first purification step (S61) is a step for removing impurities from the neutralized solution after the neutralization step (S50).

[0095] The first purification step (S61) may be a step of removing impurities using a precipitation method. In the first purification step (S61), at least one precipitant selected from the group consisting of sodium sulfide (NaS), sodium hydrosulfide (NaSH), ammonium hydrogen sulfide (NHHS), and hydrogen sulfide (HS) may be used to remove impurities using sulfurization precipitation. This allows for the recovery of a precipitate containing copper sulfide (CuS) as a main component and impurities such as zinc, lead, and cadmium. This can then be purified into copper metal through purification processes such as solvent extraction and substitution.

[0096] In addition, in the first purification step (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) can be used to remove impurities using hydroxide precipitation. This allows impurities such as aluminum (Al), iron (Fe), chromium (Cr), silicon (Si), etc. to be precipitated and removed. When sodium hydrosulfide is used as the precipitant, the reaction formula is as shown in Reaction Scheme 7 below, and when sodium hydroxide is used as the precipitant, the reaction formula is as shown in Reaction Scheme 8 below.

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

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

[0099] In the first purification step (S61), the precipitant used in the sulfide precipitation process can be added 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 added at an equivalent ratio of less than 1.0 relative to the copper, the copper precipitation rate may be less than 83%, and the reaction may not be complete. If the sulfide precipitant is added at an equivalent ratio of more than 2.5 relative to the copper, excessive impurities from the precipitant may be introduced, negatively affecting the process, and the recovery rate may decrease due to nickel coprecipitation. The pH range in which the reaction occurs can be 0.8 to 2.5 at 70°C.

[0100] In the hydroxide precipitation purification process, the precipitant is 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 will be less than 85%, and the reaction may not be complete. If the hydroxide precipitant is added at an equivalent ratio of more than 1.5 relative to the heavy metals, excessive impurities from the precipitant will flow in, negatively impacting the process, and the recovery rate will decrease due to nickel coprecipitation. The pH range in which the reaction occurs is 2.5 to 4.5 at 60°C.

[0101] After the first purification step (S61), the contents of copper, iron, aluminum, and silicon contained in the first purified solution may be reduced to 5 mg / L or less, and the contents of zinc, cobalt, and magnesium contained in the first purified solution may be reduced to 20 mg / L or less.

[0102] 2nd purification step (S62)

[0103] In the second purification step (S62), the first purified solution produced in the first purification step (S61) may be further purified. The second purification step (S62) may be performed after the first purification step (S61). The second purification step (S62) may be a step of removing impurities using a solvent extraction method.

[0104] In the second purification step (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 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 Phosphoric Acid, Mono-2-ethylhexyl (2-Ethylhexyl) phosphonate, and Bis (2,4,4-Trimethylpentyl) Phosphinic Acid.

[0106] The loading step may be a step of extracting impurities, including zinc, magnesium, or a combination thereof, contained in the first post-purification solution into an organic phase. The loading step may be a step of extracting zinc, magnesium, and manganese contained in the first post-purification solution into an organic phase after the first purification step (S61) 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 target metal will not bond completely with the organic extractant, resulting in an extraction rate of less than 90%. If the volume ratio of the organic phase to the aqueous phase in the loading process exceeds 3, excessive use of the organic extractant will increase the process cost. 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. The reaction temperature may be 30 to 40°C.

[0108] When the aqueous and organic phases are mixed and zinc, magnesium, and manganese are extracted into the organic phase, phase separation occurs due to the difference in specific gravity between the organic and aqueous phases. This phase separation produces a second purified solution, which is a nickel-containing aqueous solution from which zinc and magnesium have been removed, and the nickel content may be 50-100g / L.

[0109] The organic phase containing zinc and magnesium may be subjected to a stripping process. In the stripping process, an inorganic acid may be added to the organic phase after the loading process to remove impurities contained in the organic phase. The stripping process may be a process of back-extracting zinc, magnesium, and manganese contained in the organic phase into the aqueous phase.

[0110] The volume ratio of the organic phase to the aqueous phase in the stripping step may be about 5 to 10. If the volume ratio of the organic phase to the aqueous phase in the stripping step 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 step is more than 10, the efficiency of stripping of impurities may decrease. The pH range of the stripping step may be about 0.5 to 1.5. Sulfuric acid (H2SO4) may be used to adjust the pH range of the stripping step to about 0.5 to 1.5. The reaction temperature may be 30 to 40°C.

[0111] Third purification step (S63)

[0112] In the third purification step (S63), the second purified solution produced in the second purification step (S62) may be further purified. The third purification step (S63) may be performed after the second purification step (S62). The third purification step (S63) may be a step of removing impurities using a solvent extraction method. 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 stripping 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.

[0113] The loading step may be a step of extracting impurities, including cobalt, contained in the second post-purification solution into an organic phase. The loading step may be a step of extracting cobalt contained in the second post-purification solution into an organic phase after the second purification step (S62) using an organic extractant.

[0114] The volume ratio of the organic phase to the aqueous phase in the loading step can be about 1 to 3. If the volume ratio of the organic phase to the aqueous phase in the loading step is less than 1, the target metal may not be fully combined with the organic extractant, resulting in an extraction rate of less than 90%. If the volume ratio of the organic phase to the aqueous phase in the loading step is greater than 3, excessive use of the organic extractant may increase process costs. To adjust the pH range of the loading step to 4 to 5, at least one selected from the group consisting of sodium hydroxide (NaOH) and sodium carbonate (Na2CO3) may be used. The reaction temperature may be 30 to 40°C.

[0115] When the aqueous and organic phases are mixed and cobalt is extracted into the organic phase, phase separation occurs due to the difference in specific gravity between the organic and aqueous phases. This phase separation produces a third purified solution, which is a nickel-containing aqueous solution from which cobalt has been removed and may have a nickel content of 65 to 125 g / L.

[0116] The cobalt-laden organic phase may be subjected to a stripping step.

[0117] In the stripping process, after the loading process, an inorganic acid may be added to the organic phase to remove cobalt contained in the organic phase. The stripping process may be a process of back-extracting the 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 step may be about 3 to 10. If the volume ratio of the organic phase to the aqueous phase in the stripping step is less than 3, 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 step is more than 10, the efficiency of cobalt stripping may decrease. The pH range of the stripping step may be about 0.5 to 1.5. Sulfuric acid (H2SO4) may be used to adjust the pH range of the stripping step to about 0.5 to 1.5. The reaction temperature may be 30 to 40°C.

[0119] When the aqueous and organic phases are mixed and cobalt is extracted into the organic phase, phase separation is possible due to the difference in specific gravity between the organic and aqueous phases. Through phase separation, a process solution containing cobalt can be produced, which can be further refined through precipitation and crystallization to produce high-purity cobalt sulfate.

[0120] Reduction step (S70)

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

[0122] The reduction step (S70) may be a step of reducing nickel to metal powder using a hydrogen reduction method. The reduction step (S70) may be carried out by (i) an ammonium precipitation step of adding an ammonium precipitant in an amount of 2 to 2.5 equivalents of the nickel content in the purified solution to form a nickel complex salt, (ii) a hydrogen reduction step of adding hydrogen gas to the purified solution at a flow rate of 30 to 60 NL / hr, (iii) a growth step of growing nickel metal powder particles by mixing nickel metal powder seeds produced in the hydrogen reduction step with the purified solution, or a combination of (i), (ii), and (iii).

[0123] For example, the reduction step (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 reduction step (S70) can be carried out via the chain reactions of (i), (ii), and (iii).

[0125] For example, the purified solution (iii) may be one into which an ammonium precipitant having a content of (i) and hydrogen gas having a flow rate of (ii) have been added.

[0126] The reduction step (S70) may be carried out using additives including iron sulfate, aluminum sulfate, polyacrylic acid, or a combination thereof to effectively carry out the hydrogen reduction reaction.

[0127] In the reduction process, a precipitant is added in the first reaction to generate nickel metal powder seeds, and then a new purified solution is repeatedly mixed with the nickel powder seeds generated in the first reaction to grow the size of the single particles of the nickel metal powder, thereby improving the density of the nickel metal powder and reducing the amount of precipitant added in the early stages 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 precipitating agent, and hydrogen gas (H2gas) can be used to reduce the nickel complex salt to nickel metal.

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

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

[0131] When hydrogen gas is used to reduce the complex salt produced here, the reaction formula is as shown below [Reaction Formula 10].

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

[0133] The reduction step (S70) can be carried out at 160-200°C and a pH of 8.0-9.0. If the pH is less than 8.0, the nickel recovery rate will be less than 80%. If the pH is greater than 9.0, excessive impurities from the precipitant will flow in, negatively affecting the process and reducing economic efficiency due to the use of excessive precipitant.

[0134] The nickel metal powder prepared according to the present invention can be used as nickel metal in powder form after drying, and can be further processed to be made into briquettes, which can be mixed with iron to form alloys or used as a precursor nickel material for the positive electrode active material of lithium secondary batteries.

[0135] Experimental Example

[0136] [Raw materials]

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

[0138] (unit: wt%) [Table 3]

[0139] *In addition to the above metal ions, the weight ratio is 100 through the sum of ions including sulfur (S), oxygen (O), and hydrogen (H).

[0140] A second raw material containing the elements shown in Table 4 below was prepared.

[0141] (unit: wt%) [Table 4]

[0142] In addition to the above metal ions, the weight ratio is 100 through the sum of ions including oxygen (O) and hydrogen (H).

[0143] [Reduction heat treatment process]

[0144] A reduction heat treatment was carried out on the first raw material containing nickel, lithium, etc. Specifically, 2.0 kg of the raw material was charged into a tubular furnace, and then the raw material was subjected to a reduction heat treatment at 850°C for 3 hours while maintaining a reducing atmosphere using N2 gas, thereby obtaining a residue after the reduction heat treatment that was converted from the form of lithium oxide (Li2O) to the form of lithium carbonate (Li2CO3).

[0145] [First leaching process]

[0146] After the reduction heat treatment, lithium was recovered from the residue through water leaching. Specifically, 100g of the raw material was placed in a ball mill and crushed with 2.5L of water (HO) for 2 hours. After water leaching, solid-liquid separation was performed using vacuum filtration to obtain the first leaching residue containing the elements listed in Table 5 below and the first leaching solution containing the elements listed in Table 6 below.

[0147] (unit: wt%) [Table 5]

[0148] In addition to the above metal ions, the weight ratio is 100 through the sum of ions including oxygen (O) and hydrogen (H).

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

[0150] [Roasting process]

[0151] A roasting process was carried out on the second raw material containing nickel, sulfur, etc. Specifically, 2 kg of raw material was charged into a tubular furnace, and then sufficiently oxygen (O2) was injected and roasted at 850°C for 3 hours to obtain a roasting residue (roasted ore) that had been converted from nickel sulfide (NiS) to nickel oxide (NiO).

[0152] [Second leaching process]

[0153] After the reduction heat treatment, the residue and the residue after roasting were mixed in a weight ratio of 2:8, and the mixture was subjected to high-temperature and high-pressure leaching.

[0154] 450g of the mixed raw material was mixed with 3L of water in an autoclave, and the mixture was maintained at 240℃ and 3,500kPa for 3 hours with an initial acidity of 120g / L. As a result, a second leaching solution with a nickel concentration of 60g / L and a nickel leaching rate of 95% was obtained.

[0155] [Neutralization process]

[0156] A neutralization step was carried out using nickel-containing by-products from the second leaching solution.

[0157] The pH of 2 L of the second leaching solution was maintained at 2.5 for 3 hours at 80°C by adding nickel-containing by-products, resulting in a neutralized solution with a nickel concentration of 82 g / L.

[0158] [First purification step]

[0159] A first purification step was carried out using a precipitation method to remove impurities contained in the neutralized solution.

[0160] After adding 1.3 equivalents (eq) of sodium hydrogen sulfide (NaSH) based on the copper (Cu) contained in the neutralized solution and maintaining the pH at 2.5 for 2 hours at 70°C, 99.8% of the copper was removed. Furthermore, to remove aluminum, iron, and silicon contained in the neutralized solution, nickel-containing by-products and sodium hydroxide (NaOH) were added and the pH was maintained at 4.5 for 2 hours, resulting in a first refined solution in which over 99.5% of the above-mentioned impurities had been removed.

[0161] [Second purification process]

[0162] A second purification step was carried out using solvent extraction to remove impurities contained in the solution after the first purification step.

[0163] In order to load impurities containing zinc and magnesium with the extractant, 500mL of the first purified liquid was mixed with 1,000mL of 25% diluted Di-2-Ethylhexyl Phosphoric Acid extractant, and the mixture was stirred at 40℃ for 10 minutes at a pH of 3.5. Through phase separation due to differences in specific gravity, 99% of zinc and 43% of magnesium were extracted, and this was then used in a mixer settler using the countercurrent method, allowing for complete extraction of the impurities.

[0164] [Third purification step]

[0165] A third purification step was carried out using solvent extraction to remove cobalt contained in the solution after the second purification step.

[0166] 500mL of the second refined solution containing cobalt was mixed with 1,000mL of 25% diluted Bis (2,4,4-TRIMETHYLPENTYL) Phosphinic Acid extractant and stirred at pH 5.0 and 40℃ for 10 minutes. Approximately 55% of the cobalt was extracted through phase separation due to the difference in specific gravity, and impurities were completely extracted using the countercurrent method in a mixer settler.

[0167] Through this, the cobalt was refined to 3 mg / L or less, and the third refined solution containing the elements in Table 7 below was obtained.

[0168] (unit: mg / L) [Table 7]

[0169] [Reduction process]

[0170] A reduction step was carried out using hydrogen reduction to recover nickel contained in the third refined solution in the form of metal powder.

[0171] In an autoclave, 1 L of the third refined solution containing 42 g / L of nickel was treated with ammonium hydroxide (NH4OH) at 180°C for 4 hours to maintain a pH of 8.5. 99% hydrogen gas was then introduced at 50 NL / hr to form a reducing atmosphere, and 1.7 g of iron sulfate, 1 g of aluminum sulfate, and 0.1 g of polyacrylic acid were added as catalysts. The mixture was reacted for 4 hours, and then subjected to solid-liquid separation using vacuum filtration. After washing with 1 L of distilled water (DIW), nickel metal powder containing the elements shown in Table 8 below was obtained.

[0172] (unit: wt%) [Table 8]

[0173] Although the embodiments of the present invention have been described above with reference to the accompanying drawings, it will be understood by those skilled in the art that the present invention may be embodied in other specific forms without changing the technical concept or essential characteristics thereof.

[0174] Therefore, the above-described embodiments should be understood to be illustrative in all respects and not restrictive. The scope of the present invention is defined by the claims rather than the above detailed description, and all modifications and variations that fall within the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention.

Claims

1. (A-i) a reduction heat treatment step of heat treating a first raw material containing nickel and lithium; (B) a first leaching step of leaching the heat-treated product produced by the reduction heat treatment step; (A-ii) a roasting step of heat-treating a second raw material containing nickel and sulfur; (C) a second leaching step in which the first leaching residue produced in the first leaching step and the roasted ore produced in the roasting step are leached; (D) a neutralization step of neutralizing the second post-leaching solution produced in the second leaching step; (E) a purification step for removing impurities contained in the neutralized solution produced by the neutralization step; and (F) A nickel smelting method including a reduction step of subjecting the refined liquid produced by the refinement step to a hydrogen reduction method in order to recover nickel from the refined liquid.

2. The first raw material and the second raw material each independently comprise at least one selected from the group consisting of oxides, hydroxides, sulfides, and sulfur oxides; 2. The nickel smelting method of claim 1, wherein the oxides, hydroxides, sulfides, and sulfur oxides each independently comprise 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.

3. 2. The nickel smelting method according to claim 1, wherein the first raw material contains nickel in the form of nickel oxide or nickel metal composite oxide.

4. 2. The nickel smelting method of claim 1, wherein the second feedstock comprises nickel in the form of nickel sulfide.

5. 2. The nickel smelting method according to claim 1, wherein the reduction heat treatment step is carried out at a temperature of 650 to 950° C. by feeding the first raw material into a heat treatment device and injecting nitrogen gas.

6. 2. The nickel smelting method according to claim 1, wherein the first leaching step is carried out using a first leaching agent comprising an inorganic acid, water, or a mixture thereof.

7. 2. The nickel smelting method according to claim 1, wherein the first leaching solution obtained in the first leaching step contains lithium, and the first leaching residue contains nickel.

8. 2. The method of claim 1, wherein the roasting step is carried out at a temperature of 650 to 950° C. by feeding the second raw material into a heat treatment device and injecting oxygen gas.

9. 2. The nickel smelting method according to claim 1, wherein in the second leaching step, the first leaching residue is leached in an atmospheric pressure reactor, and the roasted ore is leached in a high-temperature, high-pressure reactor.

10. 2. The nickel smelting method according to claim 1, wherein the second leaching step is carried out using a second leaching agent comprising an inorganic acid, water, or a mixture thereof.

11. 2. The nickel smelting method according to claim 1, wherein the second leaching step is carried out at a temperature of 150 to 250°C and a pressure of 800 to 4,300 kPa.

12. 2. The nickel smelting method according to claim 1, wherein the second leaching step is carried out in an atmosphere having an acidity of 100 to 200 g / L.

13. The neutralization step involves the use of MHP, MCP, and nickel hydroxide (Ni(OH) ２ ), nickel carbonate (NiCO ３ ), sodium hydroxide (NaOH), sodium carbonate (Na ２ CO ３ ), calcium hydroxide (Ca(OH) ２ ), magnesium hydroxide (Mg(OH) ２ 2. The nickel smelting process of claim 1, wherein the process is carried out using a neutralizing agent comprising calcium oxide (CaO), magnesium oxide (MgO), or a mixture thereof.

14. 2. The nickel smelting method according to claim 1, wherein the neutralization step is carried out under conditions of 80°C and pH 2 to 4.

5.

15. The purification step comprises: (E-i) a first purification step of removing impurities contained in the neutralized solution produced by the neutralization step; (E-ii) a second purification step for removing impurities contained in the first purified solution produced by the first purification step; and (E-iii) A nickel smelting method according to claim 1, further comprising a third purification step of removing impurities contained in the second purified liquid produced by the second purification step.

16. 16. The nickel smelting process of claim 15, wherein the first purification step utilizes a precipitation process to remove impurities including copper, iron, aluminum, silicon, zinc, cobalt, magnesium, or combinations thereof.

17. The nickel smelting method according to claim 15, wherein the first purification step is carried out by (i) a sulfide precipitation step of adding a sulfide precipitant to the neutralized solution in an amount of 1.0 to 2.5 equivalents of the copper content in the neutralized solution, (ii) a hydroxide precipitation step of adding a hydroxide precipitant to the neutralized solution in an amount of 0.8 to 1.5 equivalents of the impurity content in the neutralized solution, or a combination of (i) and (ii).

18. 16. The nickel smelting process of claim 15, wherein the second refining step utilizes solvent extraction to remove impurities including zinc, magnesium, manganese, or combinations thereof.

19. 16. The nickel smelting method according to claim 15, wherein the second purification step includes: (i) a loading step of adding a first solvent extractant to the first purified solution to extract impurities including zinc, magnesium, manganese, or a combination thereof into an organic phase; and (ii) a stripping 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 an aqueous phase.

20. 16. The nickel smelting method according to claim 15, wherein the third purification step utilizes solvent extraction to remove impurities including cobalt.

21. 16. The nickel smelting method according to claim 15, wherein the third purification step includes: (i) a loading step of adding a second solvent extractant to the second purified solution to extract impurities containing cobalt into an organic phase; and (ii) a stripping step of adding an inorganic acid to the organic phase to extract impurities containing cobalt contained in the organic phase into an aqueous phase.

22. 2. The nickel smelting method according to claim 1, wherein the reduction step comprises: (i) an ammonium precipitation step of introducing an ammonium precipitant in an amount of 2 to 2.5 equivalents of the nickel content in the refined solution; (ii) a hydrogen reduction step of introducing hydrogen gas into the refined solution at a flow rate of 30 to 60 NL / hr; (iii) a growth step of growing nickel metal powder particles by mixing nickel metal powder seeds produced in the hydrogen reduction step with the refined solution; or a combination of (i) to (iii).

23. 2. The nickel smelting method of claim 1, wherein the reduction step is carried out using an additive comprising iron sulfate, aluminum sulfate, polyacrylic acid, or a combination thereof.

24. 2. The nickel smelting method according to claim 1, wherein the reduction step is carried out under conditions of 160 to 200°C and pH 8.0 to 9.0.

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