Method for recovery of nickel from nickel matte in sulfide form

Abstract

A nickel recovery method according to an embodiment of the present invention is a method for recovering nickel from a nickel matte in sulfide form, the method comprising: a step for pressure-leaching the nickel matte at a pressure higher than atmospheric pressure; a step for neutralizing the pressure-leached liquid produced in the pressure-leaching step; a first solvent extraction step for producing a first extracted liquid containing nickel from the neutralized liquid produced in the neutralization step; and a second solvent extraction step for producing a second extracted liquid containing nickel from the first extracted liquid.

Description

Method for recovering nickel from nickel matte in the form of sulfide

[0001] The present invention relates to a method for recovering nickel, and more particularly, to a method for recovering nickel from nickel matte in the form of sulfide.

[0002] Nickel (Ni) is an essential metal in various industries, playing a crucial role in the manufacture of electric vehicle batteries, stainless steel, and electronic devices. Nickel matte, a nickel raw material that exists in the form of a sulfide, is a constant demand for technologies to efficiently process it and recover high-purity nickel.

[0003] A representative method for recovering nickel from nickel matte is the atmospheric leaching process using an acid solution. However, this atmospheric leaching process has limitations, such as low production efficiency, as it requires prolonged operation (e.g., more than 16 hours) to increase leaching efficiency. Furthermore, the increased consumption of gas or steam, coupled with the high cost of hydrogen peroxide (H2O2) as an oxidizing agent, reduces economic feasibility. To overcome these issues, active research is being conducted on methods for recovering nickel from nickel matte.

[0004] The present invention provides a method for recovering nickel from a nickel matte in the form of sulfide by performing a pressure leaching process and a solvent extraction process.

[0005] A nickel recovery method according to one aspect of the present invention is a method for recovering nickel from a nickel matte in the form of a sulfide, comprising: a step of pressurizing and leaching the nickel matte at a pressure higher than atmospheric pressure; a step of neutralizing a pressurized leaching solution produced in the pressurized leaching process; a first solvent extraction process for producing a first extraction solution containing nickel from the neutralized leaching solution produced in the neutralization process; and a second solvent extraction process for producing a second extraction solution containing nickel from the first extraction solution.

[0006] According to one aspect of the present invention, the pressurized leaching process includes supplying oxygen at a pressure higher than the atmospheric pressure, and the pressure higher than the atmospheric pressure may be 2 bar to 10 bar.

[0007] According to one aspect of the present invention, the pressurized leaching process can be performed at a temperature of 130°C to 180°C.

[0008] According to one aspect of the present invention, the pressurized leaching process can be performed for 3 to 10 hours.

[0009] According to one aspect of the present invention, a nickel-containing by-product is generated in the first solvent extraction process or the second solvent extraction process, and the nickel-containing by-product can be recycled in the neutralization process.

[0010] According to one aspect of the present invention, in the first solvent extraction process, an organic extractant is further produced after the first extraction, and the nickel recovery method may further include a process of recovering a first valuable metal from the organic extractant after the first extraction.

[0011] According to one aspect of the present invention, the first valuable metal may include at least one selected from the group consisting of Cu, Mn, and Zn.

[0012] According to one aspect of the present invention, an organic phase is obtained in the first valuable metal recovery process, and the organic phase can be recycled in the first solvent extraction process.

[0013] According to one aspect of the present invention, in the second solvent extraction process, an organic extractant is further produced after the second extraction, and the nickel recovery method may further include a process of recovering a second valuable metal from the organic extractant after the second extraction.

[0014] According to one aspect of the present invention, the second valuable metal may include at least one selected from the group consisting of Co and Mg.

[0015] According to one aspect of the present invention, the nickel mat on which the pressure leaching process is performed is a first nickel mat, and in the neutralization process, a second nickel mat is introduced to react the second nickel mat with the pressure leaching liquid generated from the first nickel mat to generate the neutralization liquid and the neutralization residue.

[0016] According to one aspect of the present invention, the pressurized leaching liquid contains an acid, and the second nickel mat can be added in an amount of 2 to 10 equivalents relative to the acid in the pressurized leaching liquid.

[0017] According to one aspect of the present invention, in the neutralization process, additional acid is added, and the amount of the additional acid added can be adjusted so that the amount of the second nickel matte added is 2 to 5 equivalents relative to the total acid of the pressurized leaching liquid and the additional acid.

[0018] According to one aspect of the present invention, the pressurized leaching liquid and the neutralized leaching liquid contain acid, and the acid concentration of the pressurized leaching liquid before the neutralization process is 20 g / L to 30 g / L, and the acid concentration of the neutralized leaching liquid after the neutralization process is lower than the acid concentration of the pressurized leaching liquid and may be 20 g / L or less.

[0019] According to one aspect of the present invention, the nickel recovery method may further include a step of pressurizing and leaching the neutralized residue and another first nickel mat; and a step of neutralizing the pressurized leaching liquid generated in the pressurized leaching process for the other first nickel mat.

[0020] A nickel recovery method according to one aspect of the present invention is a method for recovering nickel from a nickel matte in the form of a sulfide, the method comprising: a step of neutralizing a pressurized leachate produced by pressurizing a first nickel matte at a pressure higher than atmospheric pressure; a first solvent extraction step of generating a first extraction liquid containing nickel from the neutralized liquid produced in the neutralization step; and a second solvent extraction step of generating a second extraction liquid containing nickel from the first extraction liquid. In the neutralization step, a second nickel matte may be introduced to react the second nickel matte with the pressurized leachate produced from the first nickel matte to generate the neutralized liquid and the neutralized residue.

[0021] According to the present invention, the leaching rate of nickel components from nickel matte can be improved through a pressurized leaching process. Furthermore, the purity of nickel components can be improved through a solvent extraction process, and byproducts generated during this process can be recycled in a nickel recovery process, ultimately improving production efficiency. Furthermore, after the solvent extraction process, valuable metals present in the organic extractant can be recovered from the nickel matte through a process for recovering valuable metals other than nickel.

[0022] According to the present invention, by introducing nickel matte in the neutralization process, the pressurized leaching process and the neutralization process can be efficiently repeated, and as a result, the leaching rate of nickel in the nickel matte can be maximized.

[0023] Figure 1 is a flowchart exemplarily showing a nickel recovery method according to one embodiment of the present invention.

[0024] FIG. 2 is a flowchart exemplarily showing a first solvent extraction process and a second solvent extraction process according to one embodiment of the present invention.

[0025] Figure 3 is a flowchart exemplarily showing a nickel recovery method according to one embodiment of the present invention.

[0026] In describing the present invention, if it is judged that the detailed description of related known functions that are obvious to those skilled in the art and may unnecessarily obscure the gist of the present invention, will be omitted.

[0027] Figure 1 is a flowchart exemplarily showing a nickel recovery method according to one embodiment of the present invention.

[0028] Referring to Fig. 1, a method for recovering nickel from a nickel matte in the form of a sulfide may include a pressure leaching process (S10), a neutralization process (S20), a first solvent extraction process (S30), a second solvent extraction process (S40), and an evaporation and concentration process (S50). As an example, the nickel recovery method may further include a first valuable metal recovery process (S60) and a second valuable metal recovery process (S70).

[0029] Nickel matte is an intermediate product produced by refining oxide ore and sulfide ore. Nickel matte may contain at least nickel, cobalt, copper, and iron. For example, nickel matte may contain at least 70 wt% nickel. The nickel content in nickel matte may be higher than that of other elements. For example, nickel may be included in the nickel matte in the form of sulfides. For example, the nickel content in the nickel matte in the form of sulfides may include at least one selected from the group consisting of Ni3S2, NiS, and Ni3S4. For example, nickel may be included in the nickel matte in the form of nickel metal. Additionally, some of the nickel content may be included in the nickel matte in the form of oxides.

[0030] The nickel matte may be in a pulverized state. For example, a method for recovering nickel from a nickel matte in the form of a sulfide may further include a raw material crushing process prior to the pressure leaching process (S10). The nickel matte raw material may be crushed in the raw material crushing process. The raw material crushing process may be performed in a wet or dry crusher, and may be performed in a crusher such as a ball mill, a rod mill, a bead mill, or an attrition mill. Through the raw material crushing process, the efficiency of the pressure leaching process for the nickel matte is improved.

[0031] Pressure leaching process (S10)

[0032] A pressure leaching process (S10) can be performed on a nickel matte. The pressure leaching process (S10) can be performed under a pressure higher than atmospheric pressure. The pressure can be atmospheric pressure, for example, 0.1 MPa or 1.0 bar. The pressure leaching process (S10) can be performed under a pressure of 2 to 10 bar higher than atmospheric pressure. For example, the pressure leaching process (S10) can include supplying oxygen gas (O2 gas) at a pressure of 2 to 10 bar. In describing a numerical range herein, the expression "A to B" should be understood to include not only the values ​​between A and B, but also the values ​​A and B. Oxygen gas can be used as an oxidizing agent.

[0033] The pressure leaching process (S10) may be performed in a pressurized device. For example, the pressurized device may be an autoclave facility.

[0034] The pressure leaching process (S10) may include introducing nickel matte into a pressurized device together with an acid solution, followed by supplying high-pressure oxygen. For example, the acid solution may be a sulfuric acid solution. The pressure leaching process (S10) may produce an acid solution, which may then be used in a subsequent pressure leaching process (S10). This reduces the cost of introducing the acid in the pressure leaching process (S10).

[0035] The solid density of the nickel matte introduced into the pressure leaching process (S10) may be 100 g / L to 200 g / L. The solid density of the nickel matte is the ratio of the mass of the nickel matte to the volume of the liquid in the pressurized device in which the pressure leaching process (S10) is performed. If the solid density of the nickel matte is less than 100 g / L, the operating efficiency may decrease compared to the raw material input amount, which may increase the unit cost of the process. If the solid density of the nickel matte is greater than 200 g / L, the efficiency of the leaching process may decrease, and mixing of the liquid and solid may not be easy.

[0036] The pressure leaching process (S10) may be performed at a temperature of 130°C to 180°C. If the pressure leaching process (S10) is performed at a temperature lower than 130°C, the nickel leaching rate may decrease, and the resulting nickel loss may result in a decrease in profit. If the pressure leaching process (S10) is performed at a temperature higher than 180°C, the steam and electricity usage may increase, which may increase the process cost.

[0037] The pressure leaching process (S10) can be performed for 3 to 10 hours. If the pressure leaching process (S10) is performed for less than 3 hours, the nickel leaching rate may decrease, resulting in nickel loss. If the pressure leaching process (S10) is performed for longer than 10 hours, the amount of oxygen and steam injected may increase, which may increase the unit cost of the process.

[0038] In the pressure leaching process (S10), for example, when a sulfuric acid solution is used as the acid solution, the reaction in which nickel is leached can be represented by [Reaction Formula 1] to [Reaction Formula 4] below.

[0039] [Reaction Formula 1]

[0040] Ni3S2+ H2SO4+ 1 / 2O2→ NiSO4+ 2NiS + H2O

[0041] [Reaction Formula 2]

[0042] 4NiS + H2SO4+ 1 / 2O2→ NiSO4+ Ni3S4+ H2O

[0043] [Reaction Formula 3]

[0044] NiS + 2O2→ NiSO4

[0045] [Reaction Formula 4]

[0046] Ni3S4+ H2O + 15 / 2O2→ 3NiSO4+ H2SO4

[0047] Through the above [Reaction Formula 1] to [Reaction Formula 4], the nickel component of the nickel mat can be leached, and for example, can be leached in the form of nickel sulfate.

[0048] NiS can be leached from a nickel matte according to [Reaction Formula 1]. The NiS is a stable substance at atmospheric pressure. Therefore, if NiS reacts with a sulfuric acid solution at atmospheric pressure, the nickel component may not be leached. In an embodiment of the present invention, the nickel component can be leached by reacting NiS with oxygen gas and a sulfuric acid solution according to [Reaction Formula 2] to [Reaction Formula 4] at high pressure through a pressure leaching process (S10). That is, since the nickel component of NiS is also leached, the leaching rate of the nickel component can be further increased. In addition, when the pressure leaching process (S10) is performed, the leaching time can be shortened compared to the atmospheric pressure leaching process, thereby improving production efficiency.

[0049] When performing the pressure leaching process (S10), the iron component is extracted through the oxygen supplied. 2+can be leached in the form of Fe 2+ The iron component in the form of Fe is oxidized by oxygen. 3+ It can be oxidized into the form shown in [Reaction Scheme 5] and [Reaction Scheme 6] below.

[0050] [Reaction Formula 5]

[0051] FeS + H2SO4+1 / 2O2→ FeSO4+ H2O + S

[0052] [Reaction Formula 6]

[0053] 2Fe 2+ + 2H + +1 / 2O2→ 2Fe 3+ + H2O

[0054] And according to [Reaction Formula 7] below, Fe 3+ Iron components oxidized in the form of hematite (Fe2O3) can be precipitated.

[0055] [Reaction Formula 7]

[0056] Fe2(SO4)3+ 4H2O → Fe2O3+ 3H2SO4+ H2O

[0057] The pressure leaching liquid produced in the pressure leaching process (S10) may contain an acid solution. For example, the acid solution may be a sulfuric acid solution produced in the pressure leaching process (S10) (see [Reaction Formulas 4] to 7] above). This may reduce the amount of sulfuric acid solution required for the pressure leaching process (S10), thereby reducing process costs.

[0058] The acid concentration in the pressurized leaching liquid produced in the pressurized leaching process (S10) can be controlled through the acid concentration introduced into the pressurized leaching process (S10). The acid concentration in the pressurized leaching liquid may be the concentration of the acid solution (e.g., sulfuric acid solution) included in the pressurized leaching liquid. For example, the acid concentration in the pressurized leaching liquid may be 20 g / L to 30 g / L. When the acid concentration is maintained at 20 g / L to 30 g / L, the nickel leaching rate may be 99% or higher, and the iron removal rate through precipitation may be 90% or higher. In addition, the amount of auxiliary materials used for iron removal in the subsequent neutralization process (S20) may be reduced, resulting in a reduction in process procedures and costs.

[0059] For example, after the pressure leaching process (S10), a repulping process may be further performed. In the repulping process, the pressure leaching residue of the nickel matte after the pressure leaching process (S10) may be stirred with water. The repulping process may be a process for recovering water-soluble nickel components remaining in the pressure leaching residue. By performing the repulping process, the amount of recovered nickel components can be maximized.

[0060] The repulping process can take between one and two hours. Preferably, the repulping process can take one hour. If the repulping process takes less than one hour, it may be difficult to completely dissolve the nickel component. If the repulping process takes more than two hours, the unit cost of the process may increase.

[0061] As the repulping process is performed, a repulping liquor may be generated. The repulping liquor may contain nickel components recovered from the pressure leaching residue. For example, the repulping liquor may be reintroduced into the pressure leaching process (S10). This can maximize the nickel recovery rate from the nickel matte.

[0062] Neutralization process (S20)

[0063] A neutralization process (S20) can be performed on the pressurized leachate produced from the pressurized leachate process (S10). In the neutralization process (S20), the acid in the pressurized leachate can be neutralized, and the pH of the pressurized leachate can be increased. In this process, impurities such as iron and aluminum in the pressurized leachate can be removed, and the remaining pressurized leachate is called a neutralized leachate. For example, in the neutralization process (S20), the iron component can be removed by precipitating in the form of goethite (FeOOH), and the iron component can remain in the neutralized leachate at 1 mg / L or less.

[0064] In the neutralization process (S20), a neutralizing agent may be added to the pressurized leachate. The neutralizing agent in the neutralization process (S20) may include at least one selected from the group consisting of sodium hydroxide (NaOH), calcium carbonate (CaCO3), nickel matte, and nickel hydroxide (Ni(OH)2). For example, nickel hydroxide may be used as the neutralizing agent in the neutralization process (S20), and the nickel hydroxide may be a nickel-containing byproduct formed in at least one selected from the group consisting of the subsequent first solvent extraction process (S30) and the second solvent extraction process (S40). That is, by adding nickel hydroxide generated during the nickel recovery process back to the nickel recovery process, additional neutralizing agents such as sodium hydroxide and calcium carbonate may not be added, or the addition of additional neutralizing agents may be reduced. As a result, the process cost may be reduced.

[0065] For example, nickel matte may be added to the pressurized leaching solution in the neutralization process (S20). This will be described with reference to FIG. 3 below.

[0066] First solvent extraction process (S30)

[0067] A first solvent extraction process (S30) can be performed on the neutralization liquid generated from the neutralization process (S20). Through the first solvent extraction process (S30), a first post-extraction organic extractant and a first post-extraction liquid can be generated from the neutralization liquid.

[0068] The first post-extraction organic extractant may include the first valuable metal and the second valuable metal purified in the first solvent extraction process (S30). For example, the first valuable metal and the second valuable metal included in the first post-extraction organic extractant may be derived from the nickel matte through the above processes. To recover the first valuable metal, the first valuable metal recovery process (S60) described below may be performed on the first post-extraction organic extractant. The first post-extraction liquid may include nickel and the second valuable metal. For example, the first post-extraction liquid may include nickel having a higher purity than the neutralization liquid. For example, the first valuable metal may include at least one selected from the group consisting of Cu, Mn, and Zn. For example, the second valuable metal may include at least one selected from the group consisting of Co and Mg.

[0069] Second solvent extraction process (S40)

[0070] A second solvent extraction process (S40) can be performed on the first post-extraction liquid. Through the second solvent extraction process (S40), a second post-extraction organic extractant and a second post-extraction liquid can be produced from the first post-extraction liquid.

[0071] The organic extractant after the second extraction may contain the second valuable metal purified in the second solvent extraction process (S40). To recover the second valuable metal, the second valuable metal recovery process (S70) described below may be performed on the organic extractant after the second extraction. The second extraction liquid may contain nickel. For example, the second extraction liquid may contain nickel of higher purity than the first extraction liquid.

[0072] Evaporation concentration process (S50)

[0073] An evaporation concentration process (S50) can be performed on the second extraction liquid. The second extraction liquid can contain a high-purity nickel component by undergoing the first solvent extraction process (S30) and the second solvent extraction process (S40), and can contain, for example, high-purity nickel sulfate. For example, through the evaporation concentration process (S50), a high-purity nickel component (for example, nickel sulfate) can be obtained in the form of a hydrate.

[0074] FIG. 2 is a flowchart exemplarily showing a first solvent extraction process and a second solvent extraction process according to one embodiment of the present invention.

[0075] Referring to FIG. 2, the first solvent extraction process (S30) may include a first loading process (S32) and a first extraction process (S34). For example, after performing the first loading process (S32), the first extraction process (S34) may be performed. The second solvent extraction process (S40) may include a second loading process (S42) and a second extraction process (S44). For example, after performing the second loading process (S42), the second extraction process (S44) may be performed.

[0076] Hereinafter, the first solvent extraction process (S30) and the second solvent extraction process (S40) will be described in more detail with reference to FIG. 2.

[0077] First, the first solvent extraction process (S30) will be described in detail.

[0078] First loading process (S32)

[0079] A first loading process (S32) can be performed on the first organic extractant. Specifically, the first loading process (S32) is a process of loading nickel into the first organic extractant from a nickel-containing solution. Through the first loading process (S32), nickel in the nickel-containing solution can be extracted by the first organic extractant, and thus, the first organic extractant after the first loading process (S32) can contain nickel. The first organic extractant containing nickel after the first loading process (S32) is referred to as a first post-loading organic extractant. The first extraction process (S34) described below can be performed on the first post-loading organic extractant.

[0080] The first organic extractant may include 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.

[0081] The nickel-containing solution after performing the first loading process (S32) is referred to as the first post-loading solution. The first post-loading solution may contain a smaller amount of nickel compared to the nickel-containing solution before performing the first loading process (S32).

[0082] An additional process (e.g., a leaching process) may be performed on the first loading liquid, thereby recovering a nickel-containing byproduct from the first loading liquid. The nickel-containing byproduct may be recycled in the neutralization process (S20). For example, the nickel-containing byproduct may include nickel hydroxide, and the nickel hydroxide may be recycled as a neutralizing agent in the neutralization process (S20).

[0083] In the first loading process (S32), the pH of the water (e.g., nickel-containing solution) can be adjusted to 4.0 to 5.2.

[0084] To control the pH, at least one selected from the group consisting of sodium hydroxide (NaOH), calcium carbonate (CaCO3), and sodium carbonate (Na2CO3) may be added.

[0085] In the first loading process (S32), the ratio of the organic phase (e.g., the first organic extractant) to the aqueous phase may be 3:1 to 8:1 by volume. If the ratio of the organic phase is lower than 3:1, the extraction rate of the nickel component may decrease, thereby reducing process efficiency. If the ratio of the organic phase is higher than 8:1, the amount of organic phase used may increase excessively, which may lead to an increase in the unit cost of the process.

[0086] First extraction process (S34)

[0087] A first extraction process (S34) may be performed on the organic extractant after the first loading. In the first extraction process (S34), a neutralized solution may be supplied to the organic extractant after the first loading.

[0088] In the first extraction process (S34), an organic phase (e.g., an organic extractant after the first loading) and an aqueous phase (e.g., a neutralization post-liquid) may be mixed. At this time, a nickel component in the organic phase may be extracted into the aqueous phase, and a valuable metal component in the aqueous phase may be extracted into the organic phase. After performing the first extraction process (S34), the aqueous phase containing the nickel component is referred to as the first post-extraction liquid, and the organic phase containing the valuable metal component is referred to as the first post-extraction organic extractant. The first post-extraction liquid may include a nickel component and a second valuable metal. The first post-extraction organic extractant may include impurities (e.g., the first valuable metal and the second valuable metal).

[0089] In the first extraction process (S34), the pH of the water phase can be adjusted to 3.8 to 4.5. To adjust the pH, at least one selected from the group consisting of sodium hydroxide (NaOH), calcium carbonate (CaCO3), and sodium carbonate (Na2CO3) can be added.

[0090] In the first extraction process (S34), the ratio of the organic phase to the aqueous phase may be 3:1 to 8:1 by volume. If the ratio of the organic phase is lower than 3:1, the extraction rate of nickel components may decrease, thereby reducing process efficiency. If the ratio of the organic phase is higher than 8:1, the amount of organic phase used may increase excessively, which may lead to an increase in the unit cost of the process.

[0091] Thereafter, a second solvent extraction process (S40) (e.g., a second extraction process (S44)) may be performed on the first post-extraction liquid, and a first valuable metal recovery process (S60) (e.g., a purification process (S62)) may be performed on the first post-extraction organic extractant.

[0092] And, the second solvent extraction process (S40) is described in detail.

[0093] Second loading process (S42)

[0094] A second loading process (S42) may be performed on the second organic extractant. Specifically, the second loading process (S42) is a process of loading nickel into the second organic extractant from the nickel-containing solution. Through the second loading process (S42), nickel in the nickel-containing solution may be extracted by the second organic extractant, and thus, the second organic extractant after the second loading process (S42) may contain nickel. The second organic extractant containing nickel after the second loading process (S42) is referred to as a second post-loading organic extractant. The second extraction process (S44) described below may be performed on the second post-loading organic extractant.

[0095] The second organic extractant may include 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.

[0096] The nickel-containing solution after performing the second loading process (S42) is referred to as the second post-loading solution. The second post-loading solution may contain a smaller amount of nickel compared to the nickel-containing solution before performing the second loading process (S42).

[0097] An additional process (e.g., a leaching process) may be performed on the second loading liquid, thereby recovering a nickel-containing byproduct from the second loading liquid. The nickel-containing byproduct may be recycled in the neutralization process (S20). For example, the nickel-containing byproduct may include nickel hydroxide, which may be recycled as a neutralizing agent in the neutralization process (S20).

[0098] In the second loading process (S42), the pH of the aqueous solution (e.g., nickel-containing solution) can be adjusted to 5.0 to 7.0. To adjust the pH, at least one selected from the group consisting of sodium hydroxide (NaOH), calcium carbonate (CaCO3), and sodium carbonate (Na2CO3) can be added.

[0099] In the second loading process (S42), the ratio of the organic phase (e.g., the second organic extractant) to the aqueous phase may be 3:1 to 8:1 by volume. If the ratio of the organic phase is lower than 3:1, the extraction rate of nickel components may decrease, thereby reducing process efficiency. If the ratio of the organic phase is higher than 8:1, the amount of organic phase used may increase excessively, which may lead to an increase in the unit cost of the process.

[0100] Second extraction process (S44)

[0101] A second extraction process (S44) may be performed on the organic extractant after the second loading. In the second extraction process (S44), the first post-extraction liquid may be supplied to the organic extractant after the second loading.

[0102] In the second extraction process (S44), an organic phase (e.g., an organic extractant after the second loading) and an aqueous phase (e.g., a first post-extraction liquid) may be mixed. At this time, a nickel component in the organic phase may be extracted into the aqueous phase, and a valuable metal component in the aqueous phase may be extracted into the organic phase. After performing the second extraction process (S44), the aqueous phase containing the nickel component is named the second post-extraction liquid, and the organic phase containing the valuable metal component is named the second post-extraction organic extractant. The second post-extraction liquid may contain a nickel component. The second post-extraction organic extractant may contain impurities (e.g., a second valuable metal).

[0103] In the second extraction process (S44), the pH of the water can be adjusted to 4.5 to 5.5.

[0104] In the second extraction process (S44), the ratio of the organic phase to the aqueous phase may be 3:1 to 8:1 by volume. If the ratio of the organic phase is lower than 3:1, the extraction rate of nickel components may decrease, thereby reducing process efficiency. If the ratio of the organic phase is higher than 8:1, the amount of organic phase used may increase excessively, which may lead to an increase in the unit cost of the process.

[0105] An evaporation concentration process (S50) may be performed on the second extraction liquid, and a second valuable metal recovery process (S70) (e.g., a second stripping process (S74)) may be performed on the second extraction organic extractant.

[0106] Hereinafter, the first valuable metal recovery process (S60) will be described with reference to FIG. 2.

[0107] After the first extraction, a first valuable metal recovery process (S60) may be performed on the organic extractant. The first valuable metal recovery process (S60) may include a purification process (S62) and a first stripping process (S64). For example, when performing the first valuable metal recovery process (S60), the purification process (S62) and the first stripping process (S64) may be performed sequentially.

[0108] Purification process (S62)

[0109] A purification process (S62) may be performed on the organic extractant after the first extraction. In the purification process (S62), an inorganic acid may be supplied to the organic extractant after the first extraction. For example, the organic extractant after the first extraction and the inorganic acid may be mixed, and the second valuable metal contained in the organic extractant after the first extraction may be recovered using the inorganic acid. For example, the inorganic acid may include at least one selected from the group consisting of sulfuric acid and hydrochloric acid.

[0110] After the purification process (S62), the first post-extraction organic extractant from which the second valuable metal has been removed is called a post-purification organic extractant, and the inorganic acid containing the second valuable metal is called a post-purification liquid. The first stripping process (S64), described below, may be performed on the post-purification organic extractant. The post-purification organic extractant may contain the first valuable metal.

[0111] In the purification process (S62), the pH of the aqueous phase (e.g., inorganic acid) can be adjusted to 1.5 to 3.5. For example, additional acid may be added to adjust the pH. By adjusting the pH range, the second valuable metal can be recovered as an inorganic acid.

[0112] In the purification process (S62), the ratio of the organic phase (e.g., the organic extractant after the first extraction) to the aqueous phase may be 3:1 to 8:1 by volume. If the ratio of the organic phase is lower than 3:1, the recovery rate of the second valuable metal may decrease, thereby reducing process efficiency. If the ratio of the organic phase is higher than 8:1, the amount of organic phase used may increase excessively, which may lead to an increase in the unit cost of the process.

[0113] First stripping process (S64)

[0114] After the purification process (S62), a first stripping process (S64) may be performed on the post-purification organic extractant. In the first stripping process (S64), an inorganic acid may be supplied to the post-purification organic extractant. For example, the post-purification organic extractant and the inorganic acid may be mixed, and the first valuable metal contained in the post-purification organic extractant may be recovered using the inorganic acid.

[0115] After the first stripping process (S64), the post-purification organic extractant from which the first valuable metal has been removed is referred to as the first organic phase and can be recycled in the first loading process (S32). For example, the first organic phase can be recycled as the first organic extractant in the first loading process (S32).

[0116] In the first stripping process (S64), the pH of the aqueous phase (e.g., inorganic acid) can be adjusted to 1.0 to 2.0. For example, additional acid can be added to adjust the pH. By adjusting the pH range, the first valuable metal can be recovered as an inorganic acid.

[0117] In the first stripping process (S64), the ratio of the organic phase (e.g., the organic extractant after purification) to the aqueous phase may be 3:1 to 8:1 by volume. If the ratio of the organic phase is lower than 3:1, the recovery rate of the first valuable metal may decrease, thereby reducing process efficiency. If the ratio of the organic phase is higher than 8:1, the amount of organic phase used may increase excessively, which may lead to an increase in the unit cost of the process.

[0118] After the first stripping process (S64), the inorganic acid containing the first valuable metal is referred to as the first stripping liquid. A subsequent process may be performed on the first stripping liquid, through which the first valuable metal may be recovered. For example, a first precipitation process may be performed on the first stripping liquid, and at least one selected from the group consisting of sodium sulfate (Na2S), sodium hydroxide (NaSH), ammonium hydrogen sulfide (NH4HS), and hydrogen sulfide (H2S) may be used as a precipitating agent. Here, the precipitated first valuable metals may be separated from the liquid phase through solid-liquid separation, and finally, the first valuable metal may be recovered.

[0119] Hereinafter, the second valuable metal recovery process (S70) will be described with reference to FIG. 2.

[0120] A second valuable metal recovery process (S70) may be performed on the organic extractant after the second extraction. The second valuable metal recovery process (S70) may include a second stripping process (S74).

[0121] Second stripping process (S74)

[0122] A second stripping process (S74) may be performed on the organic extractant after the second extraction. In the second stripping process (S74), an inorganic acid may be supplied to the organic extractant after the second extraction. For example, the organic extractant after the second extraction and the inorganic acid may be mixed, and the second valuable metal contained in the organic extractant after the second extraction may be recovered using the inorganic acid.

[0123] After the second stripping process (S74), the second organic extractant from which the second valuable metal has been removed is referred to as the second organic phase and can be recycled in the second loading process (S42). For example, the second organic phase can be recycled as the second organic extractant in the second loading process (S42).

[0124] In the second stripping process (S74), the pH of the aqueous phase (e.g., inorganic acid) can be adjusted to a range of 1.0 to 3.0. For example, additional acid may be added to adjust the pH. By adjusting the pH range, the second valuable metal can be recovered as an inorganic acid.

[0125] In the second stripping process (S74), the ratio of the organic phase (e.g., the organic extractant after the second extraction) to the aqueous phase may be 3:1 to 8:1 by volume. If the ratio of the organic phase is lower than 3:1, the recovery rate of the second valuable metal may decrease, thereby reducing the process efficiency. If the ratio of the organic phase is higher than 8:1, the amount of organic phase used may increase excessively, which may lead to an increase in the unit cost of the process.

[0126] After the second stripping process (S74), the inorganic acid containing the second valuable metal is referred to as the second stripping liquid. A subsequent process may be performed on the second stripping liquid, through which the second valuable metal may be recovered. For example, the subsequent process may be performed together on the purification liquid containing the second valuable metal. For example, a second precipitation process may be performed on the second stripping liquid and the purification liquid, and at least one selected from the group consisting of sodium sulfate (Na2S), sodium hydroxide (NaSH), ammonium hydrogen sulfide (NH4HS), and hydrogen sulfide (H2S) may be used as the precipitating agent.

[0127] The second valuable metals precipitated here can be separated from the liquid phase through solid-liquid separation, and the second valuable metals can ultimately be recovered.

[0128] Hereinafter, the process and results of performing a nickel recovery method according to an embodiment of the present invention will be described.

[0129] First, for Examples 1 to 7, nickel matte containing 73.4 wt% nickel (Ni), 0.49 wt% cobalt (Co), 0.18 wt% copper (Cu), and 3.61 wt% iron (Fe) was used as the raw material. When the pressure leaching process was performed, an autoclave facility was used, and the solid density of the introduced raw material was set to 150 g / L and the reaction was performed for 5 hours. The reaction temperature and pressure were controlled to 150°C and 9.0 bar.

[0130] A sulfuric acid solution was used as the acid solution, but the initial sulfuric acid concentration was adjusted differently so that the concentration of the acid solution in the pressurized leaching solution of each example was different. The sulfuric acid concentration, nickel leaching rate, and iron precipitation rate in the pressurized leaching solution according to the initial sulfuric acid concentration in Examples 1 to 7 are as shown in [Table 1] below.

[0131] Initial sulfuric acid concentration (g / L) Sulfuric acid concentration of pressurized leaching solution (g / L) Nickel leaching rate (%) Iron precipitation rate (%) Example 1 11 10 10 99.89 3.4 Example 2 1 20 20 99.99 0.4 Example 3 1 30 30 99.98 9.3 Example 4 1 40 40 99.93 0.1 Example 5 1 80 80 61.44 20 Example 6 1 90 90 60.82 18 Example 7 2 00 100 61.22 11

[0132] Referring to Table 1, when the initial sulfuric acid concentration of the pressure-leached liquid was adjusted to 10 g / L to 30 g / L, as in Examples 1 to 3, the nickel leaching rate was 99% or more, and about 90% or more of the iron components contained in the nickel mat and leached during pressure leaching were precipitated. When the initial sulfuric acid concentration of the pressure-leached liquid was adjusted to 40 g / L, as in Example 4, the nickel leaching rate was excellent at 99%, but the iron precipitation rate was reduced to about 30.1%. In addition, when the initial sulfuric acid concentration of the pressure-leached liquid was adjusted to 80 g / L or more, as in Examples 5 to 7, it was confirmed that the nickel leaching rate was also reduced to about 60%, and the iron precipitation rate was also reduced to about 4%.

[0133] Through the above Examples 1 to 3, it was confirmed that when a pressure leaching process is performed, nickel components can be effectively leached from NiS, which is a stable substance, according to [Reaction Scheme 2] to [Reaction Scheme 4]. However, as in Examples 4 to 7, when the concentration of sulfuric acid in the solution becomes excessively high, [Reaction Scheme 2] in which sulfuric acid acts as a reactant becomes predominant, and accordingly, a large amount of Ni3S4, which is a product of [Reaction Scheme 2], is generated, resulting in a decrease in the dissolution rate of the nickel components.

[0134] [Table 2] below shows the extraction rate of each component into the organic phase according to the pH value in the first extraction process in Examples 8 to 10 after performing the first solvent extraction process.

[0135] pHNi (%)Co (%)Mg (%)Mn (%)Cu (%)Zn (%)Example 82.8-3.21-210-1515-2585-9570-8095-100Example 93.8-4.55-850-7050-7099-10090-10099-100Example 104.5-4.720-2570-8070-8099-10095-10099-100

[0136] In Example 8, the extraction rates of Mn, Cu, Zn, Co, and Mg were lower than those of Examples 9 and 10, and in particular, a significant amount of Co and Mg was not extracted into the organic phase. However, the extraction rate of Ni was low at 1-2%, and therefore, the aqueous phase contained a relatively large amount of nickel compared to other examples. In Example 9, the pH was adjusted to 3.8-4.5, and most of Mn, Cu, and Zn were extracted into the organic phase, and more than half of Co and Mg were also extracted into the organic phase. In contrast, Ni was extracted in a lower amount of 5-8% than the other components, resulting in the production of a high-purity nickel solution.

[0137] In Example 10, the extraction rates of Mn, Cu, Zn, Co, and Mg were high, but Ni was also extracted in large amounts, at 20-25%. That is, the nickel solution produced according to Example 10 was not suitable for producing a high-purity nickel solution, as only a small amount of nickel was leached out.

[0138] [Table 3] below shows the extraction rates of each component into the organic phase according to the pH value in the second extraction process in Examples 11 and 12 after performing the second solvent extraction process.

[0139] pHNi (%)Co (%)Mg (%)Mn (%)Cu (%)Zn (%)Example 114.5-5.51-395-10095-10099-10099-10099-10099-100Example 125.5-5.85-898-10098-10099-10099-10099-100

[0140] In Example 11, the pH was adjusted to 4.5-5.5. It was confirmed that the extraction rate of Ni was low, but the extraction rates of other components were high, so that most impurities could be removed. In Example 12, the pH was adjusted to 5.5-5.8. Although the extraction rate of Ni was higher than in Example 11, the extraction rates of other components were also higher than in Example 11, so that most impurities could be removed.

[0141] Figure 3 is a flowchart exemplarily showing a nickel recovery method according to one embodiment of the present invention.

[0142] Referring to FIG. 3, a leaching process and a neutralization process are performed on a nickel mat. For example, a pressure leaching process (S10') and a neutralization process (S20') may be sequentially performed on the nickel mat. Except for differences that may or may not be described below and that can be understood by a person skilled in the art, the pressure leaching process (S10') and the neutralization process (S20') may be similar processes to the pressure leaching process (S10) and the neutralization process (S20), respectively, described with reference to FIG. 1. For convenience, in describing the embodiment of FIG. 3, the nickel mat that is the target of the pressure leaching process (S10') and the neutralization process (S20') is referred to as a first nickel mat.

[0143] A neutralization process (S20') is performed on the pressurized leaching liquid generated in the pressurized leaching process (S10'), and a nickel matte is introduced as a neutralizing agent in the neutralization process (S20'). For convenience, in describing the embodiment of FIG. 3, the nickel matte introduced into the neutralization process (S20') without the pressurized leaching process (S10') being performed is referred to as a second nickel matte. In the neutralization process (S20'), the second nickel matte and the acid solution (e.g., sulfuric acid solution) included in the pressurized leaching liquid may react with each other, thereby allowing the nickel component of the second nickel matte to be leached. For example, the nickel component of the second nickel matte may be leached according to the above-described [Reaction Formula 1] and [Reaction Formula 2].

[0144] The second nickel matte can neutralize the acid in the pressurized leachate. For example, in the neutralization process (S20'), the second nickel matte can be added in an amount of 2 to 10 equivalents relative to the acid in the pressurized leachate.

[0145] If the second nickel matte is introduced in too small a quantity (for example, less than 2 equivalents compared to the acid in the pressurized leachate), the amount of the second nickel matte introduced in one neutralization process (S20') is too small, making it difficult to increase productivity. If the second nickel matte is introduced in too large a quantity (for example, more than 10 equivalents compared to the acid in the pressurized leachate), the amount of the second nickel matte that does not participate in the reaction and remains undissolved increases, and the pH also increases more than necessary (for example, the pH increases to more than 6.5), resulting in a decrease in the nickel recovery rate.

[0146] For example, additional acid may be added together with the second nickel matte in the neutralization process (S20'). This prevents the pH of the pressurized leachate from becoming excessively high and maximizes the amount of the second nickel matte participating in the reaction. The amount of additional acid added may be adjusted so that the amount of the second nickel matte is 2 to 5 equivalents relative to the total acid of the pressurized leachate and the additional acid, thereby controlling the pH of the mixture to be 4.5 to 5.0.

[0147] For example, the acid concentration of the pressurized leaching liquid before the neutralization process (S20') may be 20 g / L to 30 g / L. The acid concentration of the pressurized leaching liquid may be reduced through the neutralization process (S20'), and for example, the acid concentration of the pressurized leaching liquid (e.g., the neutralized leaching liquid described below) after the neutralization process (S20') may be lower than the acid concentration of the pressurized leaching liquid before the neutralization process (S20'), and may be 20 g / L or less.

[0148] The pressurized leaching solution after the neutralization process (S20') can be separated into a liquid neutralization solution and a solid neutralization residue. For example, the neutralization solution and the neutralization residue may each contain nickel.

[0149] Subsequent solvent extraction processes, such as the first solvent extraction process (S30) and the second solvent extraction process (S40) described with reference to FIG. 1, may be performed on the neutralized liquid. Subsequently, through an evaporation and concentration process, a high-purity nickel component (e.g., nickel sulfate) may be obtained in the form of a hydrate. In addition, as the solvent extraction process for the neutralized liquid is performed, a valuable metal recovery process, such as the first valuable metal recovery process (S60) and the second valuable metal recovery process (S70) described with reference to FIG. 1 or 2, may be further performed.

[0150] The neutralized residue can be fed into a pressure leaching process (S10') together with a nickel mat (e.g., a new first nickel mat), and during this process, nickel in the neutralized residue can be leached into the pressure leaching liquid together with nickel in the new first nickel mat. Thereafter, a neutralization process (S20') can be performed by feeding a nickel mat (e.g., a new second nickel mat) to the pressure leaching liquid, and a new neutralized liquid and a neutralized residue can be obtained. The pressure leaching process (S10') and the neutralization process (S20') can be performed again for the new neutralized residue, and these processes can be performed repeatedly.

[0151] When a substance other than nickel matte is used as a neutralizing agent, since the neutralized residue contains components derived from the substance, new process conditions for the pressure leaching process (S10') may need to be set or a separate pretreatment process may be required to introduce the neutralized residue into the pressure leaching process (S10'). However, as in this embodiment, by using nickel matte as a neutralizing agent, unnecessary substances for performing the pressure leaching process (S10') can be minimized in the neutralized residue, and thus the pressure leaching process (S10') and the neutralization process (S20') can be efficiently repeated. As a result, even nickel that is not leached and remains in the neutralized residue is introduced into the pressure leaching process (S10'), so that the leaching rate of nickel in the nickel matte can be maximized.

[0152] While the present invention has been described in connection with certain embodiments herein, it should be understood that various modifications and variations can be made without departing from the spirit and scope of the invention, as understood by those skilled in the art. Furthermore, such modifications and variations are intended to fall within the scope of the claims appended to this specification.

Claims

A method for recovering nickel from nickel matte in the form of sulfide, A process for pressurizing and leaching the nickel matte at a pressure higher than atmospheric pressure; A process for neutralizing the pressurized leaching liquid produced in the above pressurized leaching process; A first solvent extraction process for producing a first extraction liquid containing nickel from the neutralization liquid produced in the neutralization process; and A nickel recovery method comprising a second solvent extraction process for producing a second extraction liquid containing nickel from the first extraction liquid. In the first paragraph, A nickel recovery method, wherein the pressurized leaching process comprises supplying oxygen at a pressure higher than the atmospheric pressure, wherein the pressure higher than the atmospheric pressure is 2 bar to 10 bar. In the first paragraph, A nickel recovery method wherein the above pressure leaching process is performed at a temperature of 130°C to 180°C. In the first paragraph, A nickel recovery method wherein the above pressure leaching process is performed for 3 to 10 hours. In the first paragraph, A nickel-containing by-product is generated in the first solvent extraction process or the second solvent extraction process, A nickel recovery method wherein the nickel-containing by-product is recycled in the neutralization process. In the first paragraph, In the first solvent extraction process, an organic extractant is further generated after the first extraction, A nickel recovery method further comprising a process of recovering a first valuable metal from an organic extractant after the first extraction. In paragraph 6, A nickel recovery method, wherein the first valuable metal comprises at least one selected from the group consisting of Cu, Mn, and Zn. In paragraph 6, In the above first valuable metal recovery process, an organic phase is obtained, A nickel recovery method wherein the organic phase is recycled in the first solvent extraction process. In the first paragraph, In the second solvent extraction process, an organic extractant is further generated after the second extraction, A nickel recovery method further comprising a process for recovering a second valuable metal from an organic extractant after the second extraction. In paragraph 9, A nickel recovery method, wherein the second valuable metal comprises at least one selected from the group consisting of Co and Mg. In the first paragraph, The nickel mat on which the above pressure leaching process is performed is a first nickel mat, A nickel recovery method in which, in the neutralization process, a second nickel mat is introduced and the second nickel mat is reacted with the pressurized leaching liquid generated from the first nickel mat to generate the neutralization liquid and the neutralization residue. In Article 11, The above pressurized leaching liquid contains acid, A nickel recovery method, wherein the second nickel mat is added in an amount of 2 to 10 equivalents relative to the acid in the pressurized leaching solution. In Article 12, In the above neutralization process, additional acid is added, A nickel recovery method, wherein the amount of the additional acid input is adjusted so that the amount of the second nickel mat input is 2 to 5 equivalents relative to the total acid of the pressurized leaching liquid and the additional acid. In Article 11, The above pressurized leaching solution and the above neutralization solution contain acid, The acid concentration of the pressurized leaching solution before the neutralization process is 20 g / L to 30 g / L, A nickel recovery method, wherein the acid concentration of the neutralized solution after the neutralization process is lower than the acid concentration of the pressurized leaching solution and is 20 g / L or less. In Article 11, The above nickel recovery method is: A process for pressurizing and leaching the residue and other first nickel mattes after neutralization; and A nickel recovery method further comprising a process of neutralizing the pressurized leaching liquid generated in the pressurized leaching process for the other first nickel mat. A method for recovering nickel from nickel matte in the form of sulfide, A process for neutralizing the pressure leaching solution produced by pressurizing a first nickel matte at a pressure higher than atmospheric pressure; A first solvent extraction process for producing a first extraction liquid containing nickel from the neutralization liquid produced in the neutralization process; and A second solvent extraction process for producing a second extraction liquid containing nickel from the first extraction liquid is included. A nickel recovery method in which, in the neutralization process, a second nickel mat is introduced and the second nickel mat is reacted with the pressurized leaching liquid generated from the first nickel mat to generate the neutralization liquid and the neutralization residue. In Article 16, The above pressurized leaching liquid contains acid, A nickel recovery method, wherein the second nickel mat is added in an amount of 2 to 10 equivalents relative to the acid in the pressurized leaching solution. In Article 17, In the above neutralization process, additional acid is added, A nickel recovery method, wherein the amount of the additional acid input is adjusted so that the amount of the second nickel mat input is 2 to 5 equivalents relative to the total acid of the pressurized leaching liquid and the additional acid. In Article 16, The above pressurized leaching solution and the above neutralization solution contain acid, The acid concentration of the pressurized leaching solution before the neutralization process is 20 g / L to 30 g / L, A nickel recovery method, wherein the acid concentration of the neutralized solution after the neutralization process is lower than the acid concentration of the pressurized leaching solution and is 20 g / L or less. In Article 16, The above nickel recovery method is: A process for pressurizing and leaching the residue and other first nickel mattes after neutralization; and A nickel recovery method further comprising a process of neutralizing the pressurized leaching liquid generated in the pressurized leaching process for the other first nickel mat.

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