Method for producing an aqueous solution containing nickel, cobalt and manganese

Abstract

The present invention provides a method for producing an aqueous solution containing nickel, cobalt and manganese, comprising: a leaching step including a pressure leaching step of pressure leaching a raw material to produce a leachate containing nickel, cobalt, manganese and impurities; an impurity removal step of removing the impurities from the leachate; a target precipitation step of adding a neutralizing agent to the filtrate from which the impurities have been removed to precipitate a mixed hydroxide precipitate containing nickel, cobalt and manganese; and a dissolution step of dissolving the mixed hydroxide precipitate in an acid, wherein the pressure leaching step includes a one-stage pressure leaching step and a two-stage pressure leaching step of pressure leaching a residue of the one-stage pressure leaching step with an acidity higher than that of the one-stage pressure leaching step, and the impurity removal step includes a one-stage solvent extraction step of selectively extracting zinc from the impurities by adding a first solvent extractant and a two-stage solvent extraction step of selectively extracting magnesium from the impurities by adding a second solvent extractant.

Description

[Technical field]

[0001] The present invention relates to a method for producing an aqueous solution containing nickel, cobalt and manganese. More specifically, the present invention relates to a method for producing an aqueous solution containing nickel, cobalt and manganese that can be used for producing a positive electrode active material for a lithium ion secondary battery after recovering nickel, cobalt and manganese from raw materials. [Background technology]

[0002] Valuable metals such as nickel, cobalt, and manganese are mainly recovered by dissolving raw materials such as low-grade ores in acid and then using a solvent extraction method. Solvent extraction uses the principle that metal ions are extracted from an aqueous solution with an organic solvent. The organic solvent used in the solvent extraction method reduces the stability of operations because it poses the risk of fire and explosion. In addition, since the unit price of organic solvents is high, costs increase in order to increase the recovery efficiency of valuable metals using the solvent extraction method. In addition, since the solvent extraction method uses a scrubbing process and a stripping process from the solvent extraction process, when a specific component is separated using the solvent extraction method, multiple process steps are required for each component, making the operation complicated.

[0003] On the other hand, a leaching process is carried out in which the raw material is reacted with acid to recover valuable metals. Atmospheric leaching is generally used in the leaching process. However, when leaching concentrate using atmospheric leaching, the reaction time must be maintained for 30 hours or more to increase the leaching efficiency, which reduces production efficiency. In addition, when atmospheric leaching is used, iron (Fe), an impurity, is also leached, so atmospheric leaching is not suitable for selective leaching.

[0004] Meanwhile, magnesium (Mg), an impurity contained in the raw material, is removed using a remover such as sodium fluoride (NaF). However, if all of the magnesium is removed using a remover, a large amount of impurity residue will be generated, increasing waste landfill costs, and additional costs will be incurred as the amount of remover used increases. Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention aims to recover valuable metals such as nickel, cobalt, and manganese from raw materials using a pressure leaching process, an impurity removal process, and a target product precipitation process, and to provide a stable operating environment by reducing the use of solvent extractants, improve productivity, and reduce production costs. [Means for solving the problem]

[0006] One embodiment of the present invention comprises: Inject oxygen into the pressurized device. Raw materials In acid solution a leaching step including a pressure leaching step of generating a leachate containing nickel, cobalt, manganese, and impurities by pressure leaching; an impurity removal step of removing the impurities from the leachate; a target precipitation step of precipitating a mixed hydroxide precipitate containing nickel, cobalt, and manganese by adding a neutralizing agent to the filtrate from which the impurities have been removed; and a dissolving step of dissolving the mixed hydroxide precipitate in an acid, wherein the pressure leaching step includes a one-stage pressure leaching step and a two-stage pressure leaching step of pressure leaching a residue of the one-stage pressure leaching step with an acidity higher than that of the one-stage pressure leaching step, and the impurity removal step includes a one-stage solvent extraction step of selectively extracting zinc from the impurities by adding a first solvent extractant, and a two-stage solvent extraction step of selectively extracting magnesium from the impurities by adding a second solvent extractant.

[0007] One embodiment of the present invention may provide a method for producing an aqueous solution containing nickel, cobalt and manganese, wherein a filtrate from the two-stage pressure leaching process is sent to the one-stage pressure leaching process.

[0008] In one embodiment of the present invention, the pressure leaching step is carried out at a temperature of 150° C. to 2 5 There can be provided a method for producing an aqueous solution containing nickel, cobalt and manganese, which is carried out under temperature conditions in the range of 0° C. and pressure conditions in the range of 8 barg to 43 barg.

[0009] According to an embodiment of the present invention, there is provided a method for producing an aqueous solution containing nickel, cobalt and manganese, wherein the acidity of the filtrate from the one-stage pressure leaching process is 10 g / L or less, and the acidity of the filtrate from the two-stage pressure leaching process is 50 g / L or more.

[0010] In one embodiment of the present invention, the oxygen pressure in the pressure leaching step is in the range of 2 barg to 8 barg. The above A method for producing an aqueous solution containing nickel, cobalt and manganese, which is introduced into a pressurized device, may be provided.

[0011] According to an embodiment of the present invention, there may be provided a method for preparing an aqueous solution containing nickel, cobalt and manganese, wherein the leaching step further includes a neutralization step of adjusting pH by introducing the mixed hydroxide precipitate.

[0012] According to an embodiment of the present invention, there is provided a method for producing an aqueous solution containing nickel, cobalt and manganese, wherein the iron in the filtrate of the neutralization step is precipitated in the form of an iron oxide compound.

[0013] According to an embodiment of the present invention, there is provided a method for preparing an aqueous solution containing nickel, cobalt and manganese, wherein the pH is adjusted to 2.5 to 4.0 in the neutralization process, and the iron concentration is 100 mg / L or less.

[0014] In one embodiment of the present invention, a residue generated in the neutralization step is input into the one-stage pressure leaching step, thereby providing a method for producing an aqueous solution containing nickel, cobalt and manganese.

[0015] One embodiment of the present invention may provide a method for preparing an aqueous solution containing nickel, cobalt, and manganese, wherein the first solvent extractant and the second solvent extractant are D2EHPA (Di-(2-ethylhexyl)phosphoric acid).

[0016] In one embodiment of the present invention, the impurity removing step further includes a copper removing step, an aluminum removing step, and a magnesium removing step.

[0017] In one embodiment of the present invention, there may be provided a method for preparing an aqueous solution containing nickel, cobalt, and manganese, wherein the copper removing step includes a step of precipitating copper by introducing sodium hydrosulfide (NaSH), and the aluminum removing step includes a step of precipitating aluminum by introducing sodium hydroxide (NaOH).

[0018] In one embodiment of the present invention, the magnesium removing step may include a step of adding sodium fluoride (NaF) to further remove magnesium after the two-stage solvent extraction step.

[0019] According to an embodiment of the present invention, there is provided a method for preparing an aqueous solution containing nickel, cobalt and manganese, wherein the sodium fluoride is added in an amount of 1.4 equivalents (eq) or more.

[0020] According to an embodiment of the present invention, there is provided a method for preparing an aqueous solution containing nickel, cobalt and manganese, wherein the pH of the aqueous solution is adjusted to a range of 9.0 to 10.0 by adding a neutralizing agent in the target precipitation step.

[0021] An embodiment of the present invention may provide a method for producing an aqueous solution containing nickel, cobalt and manganese, further comprising a raw material preparation step of preparing the raw material prior to the leaching step, the raw material preparation step including a roasting step of producing nickel oxide ore from nickel sulfide ore.

[0022] According to an embodiment of the present invention, there is provided a method for producing an aqueous solution containing nickel, cobalt and manganese, wherein sulfuric acid is produced using the sulfur dioxide produced in the roasting process, and the sulfuric acid is used as a mother liquor in the leaching process. Effect of the Invention

[0023] According to an embodiment of the present invention, the amount of expensive organic solvents that may cause explosion and fire can be reduced, improving operational stability and productivity and reducing manufacturing costs.

[0024] According to an embodiment of the present invention, the amount of organic solvent used can be reduced while the purification process for separating impurities can be efficiently performed, so that the productivity of operations can be improved. [Brief description of the drawings]

[0025] [Figure 1] 1 is a diagram showing a roasting process and a leaching process for producing an aqueous solution containing nickel, cobalt, and manganese according to an embodiment of the present invention. [Diagram 2] 2 is a diagram showing an impurity removing process and a target product precipitating process for producing an aqueous solution containing nickel, cobalt, and manganese according to an embodiment of the present invention. [Diagram 3] 2 is a diagram showing a dissolution process and a subsequent impurity removal process for producing an aqueous solution containing nickel, cobalt, and manganese according to an embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0026] The embodiments of the present invention are illustrated for the purpose of explaining the technical idea of ​​the present invention, and the scope of the invention is not limited to the embodiments presented below or the specific descriptions of these embodiments.

[0027] The present invention will now be described with reference to the drawings.

[0028] Fig. 1 is a diagram showing a roasting process (S10) and a leaching process (S20) for producing an aqueous solution containing nickel, cobalt and manganese according to an embodiment of the present invention. Fig. 2 is a diagram showing an impurity removing process (S30) and a target product precipitating process (S40) for producing an aqueous solution containing nickel, cobalt and manganese according to an embodiment of the present invention. Fig. 3 is a diagram showing a dissolving process (S50) and a post-stage impurity removing process (S60) for producing an aqueous solution containing nickel, cobalt and manganese according to an embodiment of the present invention.

[0029] 1 to 3, a method for producing an aqueous solution containing nickel, cobalt, and manganese that can be used to produce a positive electrode active material for a lithium ion secondary battery from a concentrate (nickel sulfide ore) through a series of steps can be provided. According to this method, it is possible to improve the stability and productivity of operations and reduce production costs. Each step will be described in detail below with reference to each of the drawings.

[0030] First, referring to FIG. 1, a roasting process (S10) for converting concentrate (nickel sulfide ore) into cinder (nickel oxide ore) and a leaching process (S20) for dissolving the cinder in acid to leach valuable metals can be carried out.

[0031] [Roasting process (S10)] The roasting step (S10) is a step in which nickel sulfide ore is converted into oxide using heat and oxygen, thereby producing nickel oxide ore. The roasting step (S10) can be carried out at a temperature of 600°C or higher, preferably 700°C or higher.

[0032] When nickel sulfide ore is leached with a sulfuric acid solution, the toxic substance hydrogen sulfide (H2S) is generated as shown in the following [Reaction Scheme 1], but when nickel oxide ore is leached with a sulfuric acid solution, water (H2O) is generated as shown in the following [Reaction Scheme 2]. Therefore, if nickel oxide ore is produced from nickel sulfide ore through the roasting process (S10) and then the leaching process (S20) is performed using the nickel oxide ore, the generation of toxic substances can be reduced. In addition, the Gibbs free energy (ΔG) of [Reaction Scheme 1] is -8.4 kcal, while the Gibbs free energy (ΔG) of [Reaction Scheme 2] is -22 kcal, making [Reaction Scheme 2] more thermodynamically stable than [Reaction Scheme 1].

[0033] [Reaction Scheme 1] NiS+H2SO4=NiSO4+H2S [Reaction Scheme 2] NiO+H2SO4=NiSO4+H2O

[0034] In one embodiment, sulfur dioxide (SO2) may be produced from nickel sulfide ore in the roasting process (S10), and the sulfur dioxide may be oxidized to produce sulfur trioxide (SO3), which may then be dissolved in water to produce sulfuric acid (H2SO4). The produced sulfuric acid may be used as the mother liquor in the leaching process (S20), thereby reducing production costs.

[0035] In one embodiment, the roasting step (S10) can be omitted and the nickel sulfide ore can be directly added to the leaching step (S20).

[0036] [Leaching process (S20)] The leaching step (S20) is a step in which the cinder produced in the roasting step (S10) is dissolved in an acid solution such as sulfuric acid to produce a leachate. The leaching step (S20) may include a pressure leaching step and a neutralization step (S26). The pressure leaching step is a step in which an acid solution is prepared in a pressure device, and raw materials and oxygen are introduced into the pressure device to pressure leach valuable metals. The raw materials introduced here may be nickel oxide ore or nickel sulfide ore.

[0037] In one embodiment, the pressure leaching process may use a two-stage leaching method. The pressure leaching process may be a warm pressure leaching process. For example, the pressure leaching process may include a one-stage pressure leaching process (S22) and a two-stage pressure leaching process (S24). The one-stage pressure leaching process (S22) and the two-stage pressure leaching process (S24) may each be performed in a pressure device configured with two stages, or may be performed in a single pressure device with only different process conditions (e.g., temperature, pressure, or acidity). Each of the one-stage pressure leaching process (S22) and the two-stage pressure leaching process (S24) may be performed by introducing oxygen into the pressure device.

[0038] Valuable metals may be leached from the raw material through the one-stage pressure leaching step (S22). For example, valuable metals such as nickel, cobalt, and manganese may be leached from the raw material. Other elements such as iron, copper, aluminum, zinc, and magnesium may also be leached from the raw material. The one-stage pressure leaching step (S22) may be performed under temperature conditions ranging from 150°C to 250°C and pressure conditions ranging from 8 barg to 43 barg. Under the pressure conditions, the natural steam pressure according to the temperature may be in the range of 3 barg to 38 barg. Under the pressure conditions, the oxygen supply pressure may be in the range of 2 barg to 8 barg, or preferably in the range of 4 barg to 6 barg. In one embodiment, under the pressure conditions, the oxygen supply pressure may be 5 barg. If the oxygen supply pressure is lower than the range, the leaching rate of valuable metals may be reduced.

[0039] By adjusting the acidity of the filtrate in the one-stage pressure leaching process (S22) to 10 g / L or less, it is possible to prevent excessive leaching of iron (Fe), an impurity contained in the raw material. Therefore, a separate iron removal process in a subsequent step may not be necessary. For example, the iron (Fe) concentration in the liquid in the one-stage pressure leaching process (S22) may range from 1 g / L to 3 g / L. The filtrate in the one-stage pressure leaching process (S22) may be input to the neutralization process (S26), and the residue may be subsequently treated in the two-stage pressure leaching process (S24). Since the one-stage pressure leaching process (S22) is a process for lowering the acidity in the liquid prior to the neutralization process (S26), it is possible to reduce the amount of neutralizing agent input in the neutralization process (S26).

[0040] In the two-stage pressure leaching step (S24), leaching may be performed on the leaching residue from the single-stage pressure leaching step (S22) at a temperature in the range of 150°C to 250°C and a pressure in the range of 8 barg to 43 barg. The natural steam pressure and oxygen introduction pressure conditions in the two-stage pressure leaching step (S24) may be the same as the natural steam pressure and oxygen introduction pressure conditions in the single-stage pressure leaching step (S22).

[0041] The acidity of the filtrate from the two-stage pressure leaching step (S24) may be higher than the acidity of the filtrate from the one-stage pressure leaching step (S22). For example, the pressure leaching rate can be increased by adjusting the acidity of the filtrate to 50 g / L or more in the two-stage pressure leaching step (S24). This allows all of the valuable metals contained in the raw material to be leached. For example, nickel, cobalt, manganese, iron, copper, aluminum, zinc, magnesium, etc. contained in the raw material can be leached in their entirety.

[0042] In addition, in the two-stage pressure leaching step (S24), the leaching rate of iron increases due to the increase in acidity, so the iron (Fe) concentration in the solution increases to about 5 g / L. However, by increasing the acidity to 50 g / L or more, it is possible to selectively separate the iron component. In this case, iron (Fe) precipitates in the form of an iron oxide compound and is removed as a residue. For example, oxygen is used as an oxidizing agent in the acidic atmosphere of the two-stage pressure leaching step (S24), and the iron in the solution is converted to Fe 2+ From Fe 3+ and precipitates in the form of jarosite or iron oxide.

[0043] In one embodiment, the filtrate produced in the two-stage pressure leaching process (S24) can be fed back to the one-stage pressure leaching process (S22) as shown in Figure 1. In this case, the liquor with a lowered acidity through the one-stage pressure leaching process (S22) is sent to the subsequent neutralization process (S26), so that the amount of mixed hydroxide precipitate (MHP) used as a neutralizing agent in the neutralization process (S26) can be reduced, thereby reducing process costs.

[0044] In the case of the commonly used atmospheric leaching method, the reaction time must be maintained for 18 hours or more to increase the leaching rate of valuable metals. In this case, additional costs are incurred due to increased fuel and steam usage, and the productivity is low because the amount of raw material processed per day is small. In addition, when using the atmospheric leaching method, iron components are also leached, requiring an additional iron component removal process in the latter stage. However, according to one embodiment of the present invention, the leaching efficiency of valuable metals is improved by using a two-stage pressure leaching method, and the latter stage process can be omitted through selective precipitation of iron components. Therefore, production costs can be reduced and productivity can be improved.

[0045] In one embodiment, the pressurizing device may be an autoclave. The raw material may be injected into the autoclave through an injection port of the autoclave, and the pressurized leachate after the reaction may be discharged to the outside of the autoclave through an outlet port. The pressurized leachate may be sent to the neutralization step (S26).

[0046] In one embodiment, the solid density of the raw material fed into the pressurizing device may be 200 g / L or more. For example, the solid density of the raw material may be in the range of 200 g / L to 300 g / L. In this case, the solid density is defined as the ratio of the mass of the raw material fed into the pressurizing device to the volume of the acid solution fed into the pressurizing device in advance. In other words, the solid density may be the ratio of the mass of the raw material fed per unit solvent, or the mass of the raw material per 1 L of solvent.

[0047] In the neutralization step (S26), mixed hydroxide precipitate (MHP) and oxygen may be added to adjust the pH of the pressurized leachate. The mixed hydroxide precipitate (MHP) may be generated in the target product precipitation step (S40) described below. In the neutralization step (S26), iron may be precipitated in the form of iron oxide. In the neutralization step (S26), the pH may be adjusted to 2.5 to 4.0, and the iron (Fe) concentration in the filtrate may be adjusted to 100 mg / L or less. The neutralization step (S26) may be performed at a temperature of 70°C to 90°C for 3 hours or more. If the pH is less than 2.5 in the neutralization step (S26), the precipitation rate of iron may decrease, and the amount of mixed hydroxide precipitate (MHP) added may increase due to the increase in pH, which may increase the process cost.

[0048] Since the acid in the pressure leaching solution and the mixed hydroxide precipitate (MHP) have excellent reactivity, the neutralization step (S26) can be carried out in a short reaction time and at a low temperature even when using the atmospheric leaching method.

[0049] The residue generated in the neutralization process (S26) has a high content of valuable metals such as nickel, cobalt, and manganese, so the residue can be fed back into the pressurizing device used in the one-stage pressure leaching process (S22) as shown in Figure 1. This reduces the loss rate of valuable metals. In addition, since the leachate with a slightly increased pH through the neutralization process (S26) is sent to the subsequent process, the amount of auxiliary materials fed to adjust the pH in the subsequent process can be reduced. The leachate, which is the filtrate from the neutralization process (S26), is sent to the impurity removal process (S30).

[0050] Next, referring to FIG. 2, an impurity removal step (S30) for removing impurities from the leachate and a target product precipitation step (S40) for precipitating a mixed hydroxide precipitate (MHP) can be performed.

[0051] [Impurity removal process (S30)] The impurity removal step (S30) is a step of removing impurities other than valuable metals from the leachate. The impurity removal step (S30) may be carried out through various steps. For example, the impurity removal step (S30) may include at least one of a copper removal step (S31), an aluminum removal step (S32), a zinc extraction step (S33), a magnesium extraction step (S34), and a magnesium removal step (S35), which are carried out in sequence. However, the order of the various steps in the impurity removal step (S30) may vary depending on the embodiment and is not limited to the order shown in the drawings.

[0052] The copper removal step (S31) is a step of removing copper (Cu) from the liquid by adding sodium hydrogen sulfide (NaSH) to the liquid. Copper can be precipitated as a copper sulfide (CuS) compound through a reaction such as [Reaction Scheme 3]. After the copper removal step (S31), the filtrate can be sent to the aluminum removal step (S32). Copper sulfide (CuS) can be precipitated at a pH of 1.0 or more. For this reason, the pH of the liquid can be maintained at 1.0 to 2.5 in the copper removal step (S31). In one embodiment, the pH of the liquid can be maintained at 2.0 to 2.5 in the copper removal step (S31). If the pH of the liquid is less than 1.0 or 2.0, it is difficult to remove copper from the liquid to 20 mg / L or less, and if the pH is more than 2.5, the solubility of nickel in sulfuric acid is low, which may result in nickel loss. According to the examples, when the pH of the solution was maintained at 2.5 in the copper removal step (S31), the copper in the solution was removed to 20 mg / L or less while minimizing the loss of nickel.

[0053] On the other hand, sodium hydrogen sulfide (NaSH) can be added slowly so as not to cause a sudden change in the pH of the solution. For example, sodium hydrogen sulfide (NaSH) can be added over 1 to 2 hours while stirring the leachate. This can prevent a sudden increase in pH in a certain area of ​​the solution, which would increase the nickel loss rate.

[0054] In one embodiment, sodium hydrogen sulfide (NaSH) may be added at 1.0 equivalent (eq) to 1.5 equivalent (eq). When the amount of sodium hydrogen sulfide (NaSH) added is less than 1.0 equivalent (eq), the copper removal rate is 98% or less, making it difficult to sufficiently remove copper from the solution. When the amount of sodium hydrogen sulfide (NaSH) added is more than 1.5 equivalents (eq), the nickel removal rate is 4% or more, resulting in a low nickel recovery rate, which is not suitable for the process of manufacturing secondary battery materials. On the other hand, according to the embodiment, when the amount of sodium hydrogen sulfide (NaSH) added in the copper removal process (S31) was 1.4 equivalents (eq), it was possible to remove copper in the solution to 20 mg / L or less while minimizing the loss of nickel.

[0055] The copper removal step (S31) is carried out at a reaction temperature in the range of 60°C to 80°C for 3 hours or more to reduce nickel precipitation in the filtrate and separate only copper through selective precipitation. Sodium hydrogen sulfide can be used as a product having a concentration of 30wt.% to 70wt.%.

[0056] [Reaction Scheme 3] 2CuSO4+2NaSH=2CuS+Na2SO4+H2SO4

[0057] The aluminum removal step (S32) is a step of removing aluminum (Al) from the liquid by adding sodium hydroxide (NaOH) to the liquid. Aluminum can be precipitated as aluminum hydroxide (Al(OH)3) compound through a reaction such as [Reaction Scheme 4]. After the aluminum removal step (S32), the filtrate can be sent to the zinc extraction step (S33). If the pH is 6.0 or higher, nickel (Ni) in the liquid precipitates as nickel hydroxide (Ni(OH)2) compound and the nickel loss rate increases, so it is preferable to maintain the pH of the liquid below 6.0 or below 4.0 in the aluminum removal step (S32). The aluminum removal step (S32) can be performed for 8 hours or less at a reaction temperature in the range of 80°C to 90°C to reduce the precipitation of nickel in the filtrate and separate only aluminum through selective precipitation. The sodium hydroxide (NaOH) added can have a concentration in the range of 100g / L to 150g / L. If the concentration of sodium hydroxide (NaOH) is less than 100g / L, the increase in the amount of liquid reduces the efficiency of the process and increases the amount of liquid in the entire process, which increases the scale of the equipment. In this case, the initial investment increases, which is undesirable in terms of process efficiency and economy.

[0058] [Reaction Scheme 4] Al2(SO4)3+6NaOH=2Al(OH)3+3Na2SO4

[0059] The zinc extraction step (S33), which is a first-stage solvent extraction step, is a step of adding a solvent extractant D2EHPA (Di-(2-ethylhexyl)phosphoric acid) at pH 2.0, and the magnesium extraction step (S34), which is a second-stage solvent extraction step, is a step of adding a solvent extractant (D2EHPA) at pH 3.5. The aqueous solution produced in the first-stage solvent extraction step can be added to the second-stage solvent extraction step. Zinc and magnesium can be selectively separated with an organic solvent through a reaction such as [Reaction Scheme 5]. The zinc extraction step (S33) and the magnesium extraction step (S34) can each be performed at a temperature in the range of 30°C to 50°C for 20 minutes or more.

[0060] In the first-stage solvent extraction process, all of the zinc is extracted, and about 63% of the manganese is also extracted. The aqueous solution from the first-stage solvent extraction process is fed into the second-stage solvent extraction process. In the second-stage solvent extraction process, more than 40% of the magnesium is extracted, and more than 90% of the manganese is extracted. The aqueous solution from the second-stage solvent extraction process contains nickel, cobalt, and magnesium, and small amounts of manganese.

[0061] The desired pH range for extracting zinc in the one-stage solvent extraction process may be 1.5 to 2.5. The desired pH range for extracting magnesium in the two-stage solvent extraction process may be 3.0 to 4.0. If the pH is less than 3.0 in the two-stage solvent extraction process, the magnesium extraction rate may decrease, and the amount of sodium fluoride (NaF) added in the subsequent process to additionally remove magnesium may increase. If the pH is greater than 4.0 in the two-stage solvent extraction process, the nickel and cobalt extraction rates may increase, and the nickel and cobalt loss rates may increase.

[0062] [Reaction Scheme 5] 2HR(org.)+MeSO4(aq.)=MeR2(org.)+H2SO4(aq.)(R=organic solvent,Me=Zn or Mg)

[0063] After the extraction of the first solvent extraction process, a scrubbing process and a stripping process may be sequentially performed on the first organic solvent.

[0064] In the scrubbing process, zinc leachate may be introduced to recover nickel and cobalt. The zinc leachate may be a solution produced in a zinc smelting process. For example, the zinc leachate may be a solution obtained by leaching cinders with sulfuric acid in a zinc smelting process. Since zinc is more reactive with D2EHPA than nickel, cobalt, magnesium, copper, and manganese, nickel and cobalt can be recovered in the aqueous solution by performing a scrubbing process. The aqueous solution containing nickel and cobalt thus recovered may be introduced again into a pressurizing device in which a leaching process (S20), for example, a one-stage pressure leaching process (S22), is performed. This reduces the loss rate of nickel and cobalt. The aqueous solution thus recovered may also contain magnesium, copper, and manganese.

[0065] In the stripping process, sulfuric acid is added to separate zinc from D2EHPA in the first organic solvent, and the regenerated and recovered D2EHPA can be used again in the first and second stage solvent extraction processes. Therefore, D2EHPA can be recycled, reducing process costs. The stripping process is a process in which sulfuric acid and the loaded first organic solvent are reacted to load hydrogen ions into the organic solvent, and the loaded impurities such as zinc are recovered in an aqueous solution.

[0066] After the extraction of the two-stage solvent extraction process, a stripping process may be performed on the second organic solvent. The stripping process on the second organic solvent may include a step of introducing sulfuric acid to separate nickel from D2EHPA in the second organic solvent into an aqueous solution, and a step of performing a selective nickel leaching process to leach the nickel separated into the aqueous solution. The selective nickel leaching process may be a step of introducing a neutralizing agent to increase the pH to 7.5 to precipitate nickel in the form of nickel hydroxide (Ni(OH)2). The residue of the selective nickel leaching process may be introduced into the leaching process (S20). Thus, the loss rate of nickel can be reduced.

[0067] On the other hand, when the solvent extraction process is carried out in only one stage, zinc, magnesium, and a small amount of nickel are distributed in the stripping solution. If a selective nickel leaching process is carried out, zinc and nickel are precipitated together. Therefore, unless a separate process for selectively removing zinc is carried out, zinc continues to accumulate, making it difficult to efficiently recover nickel. In other words, when the solvent extraction process is carried out in two stages, zinc and magnesium can be selectively removed more than when it is carried out in one stage, and thus the efficiency of nickel recovery can be improved.

[0068] In one embodiment, the ratio of the organic solvent (O) to the aqueous solution (A) can be adjusted according to the concentration of the component to be extracted in the liquid. For example, the ratio (O:A) of the organic solvent (O) to the aqueous solution (A) can be in the range of 0.5:1 to 2:1. For example, O:A can be 1:1. In this case, the zinc concentration in the liquid can be removed to 2 mg / L.

[0069] In one embodiment, the two-stage solvent extraction process can selectively separate zinc, 40% or more of magnesium, and 90% or more of manganese.

[0070] In one embodiment, D2EHPA may have a concentration of 30 wt.% to 40 wt.%, with the remaining 60 wt.% to 70 wt.% being kerosene, such as kerosine or Escaid 110. If the concentration of D2EHPA is more than 40 wt.%, the viscosity of the organic solvent is high and reduces the fluidity of the liquid, which may make piping, delivery of the aqueous solution, and liquid stirring difficult.

[0071] The magnesium removal step (S35) may be performed to remove additional magnesium remaining in the liquid after the magnesium extraction step (S34). After the magnesium removal step (S35), the filtrate may be sent to the target product precipitation step (S40). About half of the magnesium present in the aqueous solution is removed in the previous magnesium extraction step (S34), but about half of the remaining magnesium needs to be removed through an additional step. For example, the magnesium removal step (S35) is a step of removing magnesium remaining in the liquid by adding sodium fluoride (NaF) to the liquid. In the magnesium removal step (S35), sodium carbonate (Na2CO3) may be added to increase the pH. Magnesium may be precipitated as magnesium fluoride through a reaction such as [Reaction Scheme 6]. In the magnesium removal step (S35), magnesium in the liquid may be removed up to 2 mg / L. In the magnesium removal step (S35), the pH of the liquid may be adjusted to 5.2 to 6.2. By carrying out the magnesium removal step (S35) at a reaction temperature in the range of 50°C to 70°C for more than 3 hours, the precipitation of nickel in the filtrate is reduced and only magnesium can be separated through selective precipitation.

[0072] [Reaction Scheme 6] MgSO4+2NaF=MgF2+Na2SO4

[0073] In one embodiment, sodium fluoride can be added in an amount of 1.4 equivalents (eq) or more. According to the embodiment, when sodium fluoride is added in an amount of 1 equivalent (eq), it is difficult to remove magnesium to 2 mg / L or less, but when 1.4 equivalents (eq) are added, magnesium can be removed to 2 mg / L or less. That is, when there is no two-stage solvent extraction process, it is necessary to add at least 2.0 equivalents (eq) of sodium fluoride to remove all the magnesium, but according to the embodiment, magnesium in the liquid can be reduced to 1.7 mg / L by adding 1.4 equivalents (eq). In one embodiment, the amount of sodium fluoride added in the magnesium removal step (S35) is less than 2.0 equivalents (eq), and may be in the range of 1.0 equivalents (eq) to 1.5 equivalents (eq).

[0074] [Target product precipitation step (S40)] In the target product precipitation step (S40), sodium carbonate (Na2CO3) may be added as a neutralizing agent to the filtrate after the impurity removal step (S30). After the impurity removal, nickel, cobalt, and manganese are precipitated as a mixed hydroxide precipitate in the target product precipitation step (S40), so there is no need to use a solvent extractant used to selectively extract nickel, cobalt, and manganese. Nickel, cobalt, and manganese may be precipitated as a mixed hydroxide precipitate through a reaction such as [Reaction Scheme 7]. The target product precipitation step (S40) may be performed for 4 hours or more under conditions of a pH in the range of 9.0 to 10.0 and a temperature in the range of 80°C to 90°C.

[0075] Since nickel, cobalt and manganese can be recovered through the target product precipitation process (S40), the amount of expensive organic solvents that may cause explosions and fires can be reduced, improving operational stability and productivity and reducing production costs.

[0076] [Reaction Scheme 7] 3MeSO4+3Na2CO3+2H2O=MeCO32Me(OH)2+3Na2SO4+3CO2(Me=Ni, Co, or Mn)

[0077] Meanwhile, since a small amount of sodium (Na) exists in the mixed hydroxide precipitate, it can be removed by a two-stage washing process using pure water in the latter stage. Here, the filtrate generated in the two-stage washing process is reused to produce sodium carbonate (Na2CO3), which is a neutralizing agent, thereby reducing production costs.

[0078] Next, referring to FIG. 3, a dissolution step (S50) of dissolving the mixed hydroxide precipitate (MHP) in acid and a subsequent impurity removal step (S60) of removing trace impurities may be performed.

[0079] [Dissolution process (S50)] In the dissolving step (S50), the mixed hydroxide precipitate (MHP) may be added to a solution in which sulfuric acid with an acidity of 150 g / L to 200 g / L is mixed with pure water. Nickel, cobalt, manganese, and trace impurities contained in the mixed hydroxide precipitate may be dissolved in the sulfuric acid solution. The mixed hydroxide precipitate (MHP) is reacted with the aqueous sulfuric acid solution until the pH becomes 2.0. In one embodiment, hydrogen peroxide (H2O2) may be added in the dissolving step (S50) to improve the dissolution rate. In the dissolving step (S50), the reaction may be carried out for 4 hours or more under conditions of a pH in the range of 1.0 to 3.0 and a temperature in the range of 50°C to 70°C.

[0080] [Late stage impurity removal process (S60)] The filtrate from the dissolution step (S50) is a high-grade aqueous solution of nickel, cobalt, and manganese, but contains a small amount of impurities in the range of 1 mg / L to 20 mg / L. Therefore, in order to remove these impurities, a subsequent impurity removal step (S60) may be additionally performed in addition to the previous impurity removal step (S30). For example, the subsequent impurity removal step (S60) may include a copper removal step (S62) and an aluminum / iron removal step (S64). The copper removal step (S62) is a step of adding sodium hydrogen sulfide (NaSH) at pH 2.0. The aluminum / iron removal step (S64) is a step of adding sodium hydroxide (NaOH) at pH 5.0. In one embodiment, silicon (Si) in the liquid may also be removed by adding sodium hydroxide. Through the subsequent impurity removal process (S60), a nickel, cobalt, and manganese aqueous solution from which impurities have been removed may be finally prepared, and the prepared nickel, cobalt, and manganese aqueous solution may be used in a precursor plant for preparing a positive electrode active material for a secondary battery.

[0081] [Experimental Example] (1) Grade of nickel concentrate used in the experiment [Table 1] JPEG0007612175000001.jpg58162

[0082] (2) Comparison of leaching rates between nickel sulfide ore and nickel oxide ore under normal pressure conditions In order to compare the leaching rates of nickel sulfide ore and nickel oxide ore under normal pressure conditions, concentrates A to D in [Table 1] were mixed and roasted, and the nickel sulfide ore and nickel oxide ore were each leached in a sulfuric acid solution. The results are shown in [Table 2] and [Table 3]. [Table 2] shows the leaching rate (%) of each component when the initial acidity is 150g / L, and [Table 3] shows the leaching rate (%) of each component when the initial acidity is 200g / L.

[0083] The reaction time was 18 hours, the temperature was maintained at 95°C to 98°C, and the solid density of the input concentrate was maintained at 150g / L.

[0084] Concentrate E in [Table 1] has a sulfur (S) content of 11.2%, so it is difficult to carry out the roasting process, and even if the roasting process is carried out, it is difficult to obtain a secondary raw material that can be used to produce sulfuric acid, like concentrates A to D, so it was not suitable for this experiment.

[0085] In addition, reaction efficiency was compared depending on whether or not oxygen was added during leaching. The initial acidity in the following experimental examples may correspond to the acidity in the one-stage pressure leaching step (S22) in one embodiment of the present invention. On the other hand, referring to the experimental examples in [Tables 2] and [Table 3], it is difficult to improve the leaching rate compared to the leaching rate under pressurized conditions (see [Tables 4], [Tables 5], and [Table 6] below) even if the initial acidity is further increased under normal pressure conditions.

[0086] [Table 2] JPEG0007612175000002.jpg41159

[0087] [Table 3] JPEG0007612175000003.jpg43162

[0088] (3) Comparison of leaching rates between nickel sulfide and nickel oxide ores under pressurized conditions Table 4 shows the results of comparing the leaching rates when nickel sulfide ore and nickel oxide ore were fed into the autoclave under pressurized conditions. The reaction time was 3 hours, the temperature was 200°C, and the solid density of the fed concentrate was maintained at 150g / L. The initial acidity was 200g / L. The reaction efficiency was also compared depending on whether or not oxygen was fed during leaching.

[0089] Referring to the experimental example in [Table 4], when oxygen was added to nickel oxide ore, the iron leaching rate was significantly lower than when oxygen was not added. It can be seen that the iron was not leached into the liquid because iron precipitated in the form of jarosite and iron oxide under high temperature and pressure conditions due to the addition of oxygen, and therefore the iron leaching rate was measured to be low.

[0090] [Table 4] JPEG0007612175000004.jpg46164

[0091] (4) Comparison of leaching rate depending on initial acidity, pressure, and temperature under pressurized conditions Nickel oxide ore was used for leaching under pressurized conditions, and the results of pressure leaching under different initial acidity, pressure, and temperature conditions are shown in Tables 5 and 6. Table 5 shows the leaching rate of each component according to the initial acidity at a temperature of 220°C and a pressure of 22barg+5barg (O2). Table 6 shows the leaching rate of each component according to the initial acidity at a temperature of 240°C and a pressure of 32barg+5barg (O2). Oxygen was fed into the pressurizing device at an input pressure of 5barg. The acidity of the final liquid was adjusted to 50g / L-60g / L.

[0092] Referring to the experimental examples in Tables 5 and 6, the leaching rates according to the initial acidity under different pressure conditions were compared, and it can be seen that the leaching rate of each component increases when the pressure is higher. On the other hand, when the initial acidity is higher, the leaching rate of iron as well as nickel, cobalt, etc. also increases, and therefore a separate process for removing iron may be required in the later stage, so the initial acidity should be appropriately adjusted.

[0093] [Table 5] JPEG0007612175000005.jpg35165

[0094] [Table 6] JPEG0007612175000006.jpg35164

[0095] (5) Comparison of reaction efficiency depending on the type of neutralizing agent added in the neutralization process The results of neutral leaching, a neutralization process in which oxygen was introduced at 60NL / hr at a temperature of 85°C, are shown in Tables 7 and 8. Table 7 shows the leaching rate and acidity of each component as a function of reaction time when nickel oxide ore is used as the neutralizing agent. Table 8 shows the leaching rate and acidity of each component as a function of reaction time when mixed hydroxide precipitate is used as the neutralizing agent. Nickel oxide ore or mixed hydroxide precipitate (MHP) was used as the neutralizing agent. The acidity and pH of the filtrate were measured to examine the suitability of the neutralizing agent.

[0096] Referring to the experimental examples in [Table 7] and [Table 8], when mixed hydroxide precipitate (MHP) was used as a neutralizing agent, the neutralization process time could be shortened and iron could be removed more effectively than when nickel oxide ore was used.

[0097] In Table 8, negative values ​​for iron leaching rate mean that iron precipitates.

[0098] [Table 7] JPEG0007612175000007.jpg33162

[0099] [Table 8] JPEG0007612175000008.jpg34159

[0100] (6) Removal rates (%) of nickel, cobalt, and copper according to the sodium hydrogen sulfide (NaSH) input equivalent (eq)

[0101] In order to determine the optimum condition for the amount of sodium hydrogen sulfide (NaSH) added, the copper removal rates were compared when 1.2eq, 1.3eq, and 1.5eq were added in relation to the copper concentration in the liquid, and the results are shown in [Table 9]. In addition, the results of comparing the copper removal rate and nickel loss rate according to pH are shown in [Table 10]. [Table 9] shows the removal rates (%) of nickel, cobalt, and copper according to the equivalent amount (eq) of sodium hydrogen sulfide (NaSH) added. [Table 8] shows the removal rates (%) of nickel, cobalt, copper, and magnesium in the liquid according to pH. The reaction was carried out at 70°C for 3 hours.

[0102] Referring to the experimental examples in Tables 9 and 10, it can be seen that the copper removal rate increases as the amount of sodium hydrosulfide (NaSH) added and the pH increase. According to the examples, when the amount of sodium hydrosulfide (NaSH) added was 1.4 equivalents (eq) at pH 2.5, copper in the solution was removed to 20 mg / L or less while minimizing nickel loss.

[0103] [Table 9] JPEG0007612175000009.jpg33160

[0104] [Table 10] JPEG0007612175000010.jpg34166

[0105] (7) Comparison of optimal pH for zinc extraction using D2EHPA The results of comparing the impurity removal rates at pH 1.6, 1.8, and 2.0 are shown in Table 11. The reaction was carried out at 40°C for 20 minutes, and after stirring the organic solvent and aqueous solution, the aqueous solution was separated without stirring for 20 minutes, and the impurity loading rate in the liquid was compared.

[0106] Referring to the experimental examples in [Table 11], when D2EHPA was added, the zinc loading rate was 99.6% or more in the pH range of 1.6 to 2.0. According to the examples, when the ratio of organic solvent (O) to aqueous solution (A) was 1:1 under conditions of pH 2.0, the zinc concentration in the liquid could be removed down to 2 mg / L.

[0107] [Table 11] JPEG0007612175000011.jpg42163

[0108] (8) Comparison of optimal pH for magnesium extraction using D2EHPA The results of comparing the impurity removal rates at pH 3.0, 3.5, and 3.8 are shown in Table 12. The reaction was carried out at 40°C for 20 minutes, and after stirring the organic solvent and aqueous solution, the aqueous solution was separated without stirring for 20 minutes, and the impurity loading rate in the liquid was compared.

[0109] Referring to the experimental example in [Table 12], when D2EHPA was added, the magnesium loading rate was 40% or more in the pH range of 3.0 to 3.8.

[0110] [Table 12] JPEG0007612175000012.jpg42166

[0111] (9) Impurity removal rate (%) according to the amount of sodium fluoride (NaF) added To determine the optimal amount of sodium fluoride (NaF) to be added, the component removal rate was compared according to the amount of sodium fluoride added relative to magnesium, and the results are shown in Table 13. The reaction was carried out at pH 5.2 and 60°C for 3 hours.

[0112] Referring to the experimental example in [Table 13], it can be seen that the optimum amount of sodium fluoride (NaF) to be added is 1.5 equivalents (eq).

[0113] [Table 13] JPEG0007612175000013.jpg34160

[0114] (10) Component removal rate (%) according to pH when 1.5 equivalents (eq) of sodium fluoride (NaF) are added

[0115] To investigate the optimum pH condition for sodium fluoride, the results of the component removal rate according to the pH condition of the liquid are shown in [Table 14]. The reaction was carried out at 60°C for 3 hours at pH 4.2, 5.2, and 6.2.

[0116] Referring to the experimental example in [Table 14], it can be seen that when 1.5 equivalents (eq) of sodium fluoride (NaF) is added, the optimum pH is in the range of 5.2 to 6.2.

[0117] [Table 14] JPEG0007612175000014.jpg35160

[0118] Although the embodiments of the present invention have been described above with reference to the accompanying drawings, it should 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 of the present invention.

[0119] Therefore, it should be understood that the above-described embodiments are illustrative in all respects and are not limiting. The scope of the present invention is defined by the claims rather than the detailed description, and all modifications and alterations derived from the meaning and scope of the claims and their equivalent concepts should be interpreted as being included in the scope of the present invention.

Claims

1. A leaching process including a pressure leaching step in which oxygen is introduced into a pressure device to pressure leach the raw material with an acid solution to produce a leachate containing nickel, cobalt, manganese, and impurities; an impurity removing step of removing the impurities in the leachate; A target precipitation step of precipitating a mixed hydroxide precipitate containing nickel, cobalt and manganese by adding a neutralizing agent to the filtrate from which the impurities have been removed; and A dissolving step of dissolving the mixed hydroxide precipitate in an acid, the pressure leaching step comprises a one-stage pressure leaching step and a two-stage pressure leaching step of pressure leaching a residue of the one-stage pressure leaching step at an acidity higher than the acidity of the one-stage pressure leaching step; The impurity removal step includes a one-stage solvent extraction step of selectively extracting zinc from the impurities by introducing a first solvent extractant, and a two-stage solvent extraction step of selectively extracting magnesium from the impurities by introducing a second solvent extractant.

2. 2. The method for producing an aqueous solution containing nickel, cobalt and manganese according to claim 1, wherein the filtrate from the two-stage pressure leaching step is sent to the one-stage pressure leaching step.

3. 2. The method for producing an aqueous solution containing nickel, cobalt and manganese according to claim 1, wherein the pressure leaching step is carried out at a temperature in the range of 150° C. to 250° C. and a pressure in the range of 8 barg to 43 barg.

4. The acidity of the filtrate from the first pressure leaching step is 10 g / L or less; 2. The method for producing an aqueous solution containing nickel, cobalt and manganese according to claim 1, wherein the acidity of the filtrate from the two-stage pressure leaching step is 50 g / L or more.

5. 2. The method for producing an aqueous solution containing nickel, cobalt and manganese according to claim 1, wherein oxygen is introduced into the pressure device in the pressure leaching step so as to have a pressure in the range of 2 barg to 8 barg.

6. The method for producing an aqueous solution containing nickel, cobalt and manganese according to any one of claims 1 to 5, wherein the leaching step further includes a neutralization step of introducing the mixed hydroxide precipitate to adjust the pH.

7. 7. The method for producing an aqueous solution containing nickel, cobalt and manganese according to claim 6, wherein the iron in the filtrate from the neutralization step is precipitated in the form of an iron oxide compound.

8. 7. The method for producing an aqueous solution containing nickel, cobalt and manganese according to claim 6, wherein the pH is adjusted to 2.5 to 4.0 in the neutralization step, and the iron concentration is 100 mg / L or less.

9. 7. The method for producing an aqueous solution containing nickel, cobalt and manganese according to claim 6, wherein a residue generated in the neutralization step is input to the one-stage pressure leaching step.

10. 2. The method for producing an aqueous solution containing nickel, cobalt and manganese according to claim 1, wherein the first solvent extractant and the second solvent extractant are di-(2-ethylhexyl) phosphoric acid (D2EHPA).

11. 2. The method for producing an aqueous solution containing nickel, cobalt and manganese according to claim 1, wherein the impurity removing step further includes a copper removing step, an aluminum removing step, and a magnesium removing step.

12. The copper removal process includes a step of precipitating copper by adding sodium hydrogen sulfide (NaSH); 12. The method for preparing an aqueous solution containing nickel, cobalt and manganese according to claim 11, wherein the aluminum removing step includes a step of introducing sodium hydroxide (NaOH) to precipitate aluminum.

13. 12. The method of claim 11, wherein the magnesium removing step comprises adding sodium fluoride (NaF) to further remove magnesium after the two-stage solvent extraction step.

14. The method for preparing an aqueous solution containing nickel, cobalt and manganese according to claim 13, wherein the sodium fluoride is added in an amount of 1.4 equivalents (eq) or more.

15. 2. The method for producing an aqueous solution containing nickel, cobalt and manganese according to claim 1, wherein in the target product precipitation step, the pH is adjusted to a range of 9.0 to 10.0 by adding a neutralizing agent.

16. The method further includes a raw material preparation step of preparing the raw material prior to the leaching step, 2. The method for producing an aqueous solution containing nickel, cobalt and manganese according to claim 1, wherein the raw material preparation step includes a roasting step of producing nickel oxide ore from nickel sulfide ore.

17. 17. The method for producing an aqueous solution containing nickel, cobalt and manganese according to claim 16, wherein sulfuric acid is produced using the sulfur dioxide produced in the roasting step, and the sulfuric acid is used as a mother liquor in the leaching step.

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