Nickel sulfate manufacturing method

Abstract

A method for producing nickel sulfate according to an exemplary embodiment may include providing a nickel-containing raw material. Nickel may be selectively leached from the nickel-containing raw material using an oxidizing agent to produce a first leachate. Residual metals may be separated from the first leachate to produce a second leachate. Nickel sulfate may then be obtained from the second leachate. This may eliminate a separate nickel extraction step and reduce unwanted by-products.

Description

[Technical Field]

[0001] The present disclosure relates to a method for producing nickel sulfate, and more particularly to a method for producing nickel sulfate from a nickel-containing raw material. [Background technology]

[0002] Nickel is used in various fields, such as alloys for magnets and filaments, plating for corrosion prevention, catalysts, adhesive carbides, and cathode materials for secondary batteries. In particular, nickel is actively used as a transition metal contained in the cathode active material of lithium secondary batteries.

[0003] Since the cathode active material contains expensive valuable metals, including nickel, the production of the cathode material accounts for more than 20% of the production cost. In addition, with growing interest in environmental protection in recent years, research into methods for recycling cathode active materials is underway.

[0004] For example, nickel can be recovered in the form of nickel sulfate by leaching waste positive electrode active material in a strong acid, and the recovered nickel sulfate can be used to manufacture positive electrode active material again.

[0005] However, recovered nickel sulfate may contain impurities such as manganese and other transition metals, and the sodium hydroxide used in nickel extraction can increase the amount of unwanted by-products produced.

[0006] Therefore, there is a need for a method for producing a high-purity nickel compound that can increase the yield of nickel while reducing the amount of by-products produced.

[0007] For example, Korean Patent No. 10-1623930 discloses a process for leaching Ni, Co and Mn from the positive electrode material of waste lithium ion batteries. Summary of the Invention [Problem to be solved by the invention]

[0008] One object of the present disclosure is to provide a method for producing nickel sulfate with improved productivity and purity. [Means for solving the problem]

[0009] In a method for producing nickel sulfate according to an exemplary embodiment of the present disclosure, a nickel-containing raw material can be prepared. Nickel can be selectively leached from the nickel-containing raw material using an oxidizing agent to produce a first leachate. Residual metals can be separated from the first leachate to produce a second leachate. Nickel sulfate can be obtained from the second leachate.

[0010] In some embodiments, the nickel-containing source can include a nickel (Ni)-mixed hydroxide precipitate (MHP).

[0011] In some embodiments, the Ni-MHP can further contain cobalt and manganese.

[0012] In some embodiments, when producing the first leach solution, only nickel can be leached out of the nickel, cobalt, and manganese contained in the Ni-MHP.

[0013] In some embodiments, the oxidizing agent can include a metal persulfate.

[0014] In some embodiments, the first leachate can be produced using an acidic solution containing an oxidizing agent under conditions of pH 2 or higher.

[0015] In some embodiments, a fluoride precipitant may be used to precipitate at least one of calcium and magnesium when separating the residual metals to produce the second leach solution.

[0016] In some embodiments, zinc may be precipitated or extracted when separating the residual metals to produce the second leach solution.

[0017] In some embodiments, zinc precipitation can be carried out using a sulfide precipitant.

[0018] In some embodiments, zinc extraction can be performed using a phosphoric acid-based extractant.

[0019] In some embodiments, the nickel-containing raw material may be washed prior to producing the first leach solution.

[0020] In some embodiments, washing the nickel-containing raw material can partially remove calcium or magnesium contained in the nickel-containing raw material.

[0021] In some embodiments, the nickel-containing raw material can be washed using water at 40°C to 100°C.

[0022] In some embodiments, the nickel sulfate can be obtained by crystallizing nickel sulfate hydrate. [Effects of the Invention]

[0023] According to an exemplary embodiment of the present disclosure, nickel can be selectively extracted by introducing an acid solution and a metal salt oxidizing agent into the nickel-containing mixed hydroxide precipitate, thereby removing cobalt, manganese, etc. as residues and reducing the amount of acid solution and hydroxide used to separately extract cobalt and manganese.

[0024] In some embodiments, the first leachate from which nickel has been leached can be depleted or reduced in residual metals such as magnesium, calcium, and zinc to form a second leachate, which can then be crystallized to obtain high purity nickel sulfate. [Brief explanation of the drawings]

[0025] [Figure 1] FIG. 1 is a schematic flow chart illustrating a method for producing high purity nickel sulfate according to an exemplary embodiment. [Figure 2] FIG. 2 is a schematic flow chart illustrating a method for producing nickel sulfate according to a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0026] Exemplary embodiments of the present disclosure provide methods for producing nickel sulfate from nickel-containing raw materials. For example, exemplary embodiments of the present disclosure may include methods for purifying nickel from nickel-containing products.

[0027] Hereinafter, embodiments of the present disclosure will be described in more detail with reference to the drawings. However, these embodiments are merely illustrative of the present disclosure and are not intended to limit the present disclosure.

[0028] FIG. 1 is a schematic flow chart illustrating a method for producing nickel sulfate according to an exemplary embodiment.

[0029] Referring to FIG. 1, a nickel (Ni)-containing raw material can be prepared (eg, step S10).

[0030] In some embodiments, the nickel-containing raw material may be an ore-derived nickel (Ni)-mixed hydroxide precipitate (MHP). For example, the nickel-containing raw material may comprise a by-product of the hydrometallurgy of Ni oxide ore. The Ni-MHP may further comprise additional metals other than nickel, such as calcium (Ca), magnesium (Mg), cobalt (Co), manganese (Mn), aluminum (Al), iron (Fe), or zinc (Zn).

[0031] In some embodiments, the nickel-containing raw materials may also be collected from nickel-containing electrical / chemical products, such as waste batteries.

[0032] In some embodiments, the nickel-containing raw material can be washed (e.g., step S15). For example, the nickel-containing raw material can be washed with water.

[0033] For example, the washing can be performed using water at 40°C or higher (e.g., 40°C to 100°C) or 60°C or higher (e.g., 60°C to 100°C). In one embodiment, the washing can be performed using water at 60°C to 80°C.

[0034] By using high-temperature water in the above temperature range, it is possible to wash and partially remove Ca and / or Mg from the nickel-containing raw material. As described above, by using high-temperature water having a temperature of 40°C or higher or 60°C or higher, it is possible to wash and remove Mg components (e.g., MgSO4) and Ca components (e.g., CaSO4) with sufficient solubility.

[0035] In some embodiments, the ratio of the weight of water used in the washing step to the weight of the nickel-containing raw material may be 2 to 5, or 2.5 to 5. Within this ratio range, a nickel-containing raw material in a slurry state for a subsequent step can be easily produced, and partial removal of Ca and Mg can be substantially achieved.

[0036] For example, in step S20, nickel can be leached from the nickel-containing raw material using an oxidizing agent that has selective extraction selectivity for nickel.

[0037] According to an exemplary embodiment, the oxidant may include a metal persulfate. For example, the oxidant may include sodium persulfate (NaSO). A sulfuric acid solution may be supplied to the nickel-containing raw material together with the oxidant to selectively leach nickel and obtain a first leachate.

[0038] In some embodiments, the leaching process may produce a residue, for example in solid form, which may include Co, Mn, Al, Fe, etc.

[0039] For example, the residue can be removed or separated by a first solid-liquid separation (e.g., step S25) to produce the first leachate from which Co, Mn, Al, and Fe have been at least partially removed. In some embodiments, the first solid-liquid separation can be performed by a filter press or centrifugation.

[0040] In some embodiments, the amount of oxidizing agent used in the Ni leaching step may be 1.5 wt.% to 7 wt.% based on the weight of the nickel-containing raw material (e.g., the washed nickel-containing raw material). For example, 1.5 g to 7 g of the oxidizing agent may be used for 100 g of nickel-containing raw material.

[0041] Within this range, the leaching rate of Ni can be increased while the separation efficiency of Co, Mn, Al, and Fe can be improved.

[0042] In one embodiment, the amount of the oxidizing agent may be 2 wt % to 7 wt %, or 4 wt % to 6 wt %, based on the weight of the nickel-containing raw material.

[0043] In some embodiments, the molar ratio of sulfuric acid (H2SO4) to the number of moles of Ni contained in the nickel-containing raw material may be 0.5 to 1. Within this range, the amounts of Co, Mn, Al, and Fe can be sufficiently removed from the nickel-containing raw material. In one embodiment, the molar ratio of sulfuric acid to the number of moles of Ni contained in the nickel-containing raw material may be 0.7 to 0.9, or 0.7 to 0.8.

[0044] In some embodiments, the Ni leaching step may not require the use of an oxidizing agent (e.g., hydrogen peroxide) other than the metal persulfate, which can increase the Ni selectivity.

[0045] In the Ni leaching step, the dosage of sulfuric acid and oxidizing agent (metal persulfate) can be adjusted so that the pH of the first leach solution is 2 or greater, 2.5 or greater, or 3 or greater. In one embodiment, the dosage of sulfuric acid and oxidizing agent can be adjusted so that the pH of the first leach solution is 4 or greater.

[0046] This pH range can promote selective extraction of Ni. In some embodiments, the pH of the first leachate can be adjusted so that it does not exceed 6. In one embodiment, the pH of the first leachate can be adjusted so that it does not exceed 5. For example, the pH of the first leachate can be 2-6, 3-6, 4-6, or 4-5.

[0047] Thereafter, residual metals other than Ni contained in the first leachate can be further separated or removed.

[0048] For example, in step S30, Ca and / or Mg can be at least partially removed from the first leachate by a first precipitation step.

[0049] According to exemplary embodiments, a first precipitant can be added to the first leachate to precipitate Ca and / or Mg. In some embodiments, the first precipitant can include a metal fluoride. For example, the metal fluoride can include an alkali metal fluoride (e.g., NaF).

[0050] This allows Ca and Mg to precipitate from the first leachate in the form of calcium fluoride (CaF) and magnesium fluoride (MgF). The precipitated calcium fluoride and magnesium fluoride can be separated or removed by a second solid-liquid separation (e.g., step S35). The second solid-liquid separation can be performed by a filter press or centrifugation.

[0051] The second solid-liquid separation can provide a second leachate from the first leachate in which the amount of Ca and / or Mg has been reduced or removed. For example, by using the first leachate from which Ca and / or Mg has been partially removed by the washing step, a second leachate from which Ca and / or Mg has been substantially removed can be obtained.

[0052] According to an exemplary embodiment, a further step of reducing / removing additional residual metals from the second leachate can be carried out, for example, a step of separating zinc (Zn) contained in the second leachate can be carried out.

[0053] In some embodiments, in step S40-1, Zn can be at least partially removed from the first leachate by a second precipitation step.

[0054] According to exemplary embodiments, a second precipitant can be added to the first leach solution to precipitate Zn. In some embodiments, the second precipitant can include a metal sulfide and / or a non-metal sulfide. For example, the metal sulfide can include an alkali metal sulfide (e.g., NaS), and the non-metal sulfide can include hydrogen sulfide (HS).

[0055] This allows Zn to precipitate from the first leachate in the form of zinc sulfide (ZnS). The precipitated zinc sulfide can be separated or removed by a third solid-liquid separation (e.g., step S45-1). The third solid-liquid separation can be carried out by a filter press or centrifugation.

[0056] By the third solid-liquid separation, a second leachate in which the amount of Zn has been reduced or removed from the first leachate can be obtained.

[0057] In some embodiments, in step S40-2, Zn can be at least partially removed from the first leachate by an extraction step.

[0058] According to exemplary embodiments, an extractant can be added to the first leachate to extract Zn. In some embodiments, the extractant can include a phosphoric acid extractant. For example, the phosphoric acid extractant can include di-2-ethylhexyl phosphoric acid or 2-ethylhexyl phosphoric acid mono-2-ethylhexyl ester.

[0059] This allows Zn to be extracted from the first leachate in the form of zinc sulfate (ZnSO4). The extracted zinc sulfate can be separated or removed by liquid-liquid separation (e.g., S45-2). The liquid-liquid separation can be carried out by mixed sedimentation or centrifugal extraction.

[0060] By the liquid-liquid separation, a second leachate in which the amount of Zn has been reduced or removed can be obtained from the first leachate.

[0061] Thereafter, for example, in step S50, nickel sulfate hydrate can be obtained from the second leachate by a concentration and / or crystallization step.

[0062] For example, the second leachate can be concentrated by partially evaporating the water, cooled, and then the nickel sulfate in the second leachate can be crystallized and precipitated in the form of nickel sulfate hydrate (e.g., NiSO4 6H2O). The precipitated nickel sulfate hydrate can be separated by a fourth solid-liquid separation, leaving Na. The fourth solid-liquid separation can be performed using a filter press or a centrifuge.

[0063] By the fourth solid-liquid separation, nickel sulfate hydrate can be obtained which has been crystallized from the second leachate.

[0064] Figure 2 is a schematic flow chart illustrating a comparative example of a method for producing nickel sulfate. The comparative example described below with reference to Figure 2 is provided to more specifically explain the effect of the process concept of Figure 1 and is not intended to exclude it from the scope of the present invention. For example, the steps / processes included in Figure 2 may also be included in exemplary embodiments of the present invention.

[0065] Referring to FIG. 2, a nickel (Ni)-containing feedstock can be provided.

[0066] The nickel-containing raw material can be leached using sulfuric acid to extract the metal, thereby obtaining a leachate.

[0067] Sodium hydroxide (NaOH) can be added to the leachate to precipitate Al and / or Fe. This allows Al and Fe to precipitate from the leachate in the form of aluminum hydroxide (Al(OH)3) and iron hydroxide (Fe(OH)3). The precipitated aluminum hydroxide and iron hydroxide can be separated or removed by solid-liquid separation to obtain a first solution in which the amount of Al and / or Fe has been reduced or removed.

[0068] An alkali metal fluoride (e.g., NaF) can be added to the first solution to precipitate Ca and / or Mg. This allows Ca and Mg to precipitate from the first solution in the form of calcium fluoride (CaF) and magnesium fluoride (MgF). The precipitated calcium fluoride and magnesium fluoride can be separated or removed by solid-liquid separation to obtain a second solution in which the amount of Ca and / or Mg has been reduced or removed.

[0069] Zn, Mn, and / or Ca can be extracted from the second solution using a phosphoric acid extractant. Zn, Mn, and Ca can be extracted from the second solution in the form of zinc sulfate (ZnSO4), manganese sulfate (MnSO4), and calcium sulfate (CaSO4) using an alkaline compound such as sodium hydroxide for saponification of the phosphoric acid extractant and sulfuric acid.

[0070] The extracted zinc sulfate, manganese sulfate, and calcium sulfate can be separated or removed by liquid-liquid separation to obtain a third solution having reduced or removed amounts of Zn, Mn, and / or Ca.

[0071] Co can be extracted by adding the above-mentioned phosphoric acid extractant, sodium hydroxide, and sulfuric acid to the third solution.

[0072] This allows Co to be extracted from the leachate in the form of cobalt sulfate (CoSO4). The extracted cobalt sulfate is separated or removed by liquid-liquid separation to obtain a fourth solution in which the amount of Co is reduced or removed.

[0073] Ni can be extracted by adding an acidic extractant, sodium hydroxide, and sulfuric acid to the fourth solution, and the acidic extractant can include a phosphoric acid extractant or a carboxylic acid extractant.

[0074] This allows Ni to be extracted from the leachate in the form of nickel sulfate (NiSO4). The extracted nickel sulfate is separated by liquid-liquid separation to obtain an aqueous nickel sulfate solution containing nickel sulfate.

[0075] By partially concentrating and crystallizing the aqueous nickel sulfate solution, nickel sulfate can be obtained in the form of nickel sulfate hydrate.

[0076] As mentioned above, the comparative example uses sodium hydroxide to prevent a decrease in pH. Therefore, sodium from the sodium hydroxide is concentrated. This results in the production of unwanted by-products (e.g., Na2SO4). Furthermore, different types of acidic extractants are used for the continuous / sequential extraction of different metals, and multiple extraction steps are included to separate different metals, such as Mn, Co, and Ni.

[0077] In contrast, according to the exemplary embodiment described with reference to Figure 1, Co, Mn, etc. can be removed or separated as residues in the leaching step (e.g., S20 step). This reduces, for example, sodium from sodium hydroxide, making it possible to omit an additional Ni extraction step, and also reduces the amount of unwanted by-products (e.g., Na2SO4) produced.

[0078] Specific examples are presented below to aid in understanding the present disclosure, but these examples are merely illustrative of the present disclosure and do not limit the scope of the appended claims. It will be apparent to those skilled in the art that various changes and modifications to the examples are possible within the scope and technical spirit of the present disclosure, and it is natural that such changes and modifications also fall within the scope of the appended claims.

[0079] Example 1 150 g of water at 80° C. was added to 50 g of Ni-MHP and washed for 4 hours to obtain a nickel-containing mixed hydroxide precipitate containing metals in the amounts shown in Table 1 below. The washed nickel-containing mixed hydroxide precipitate was added with 15 g of 2M sulfuric acid and 2.9 g of sodium persulfate (Na2S2O8) as an oxidizing agent, and leached at 80°C for 6 hours to obtain a first leachate.

[0080] Example 2 A first leachate was obtained in the same manner as in Example 1, except that the amount of oxidizing agent used was adjusted as shown in Table 2.

[0081] Example 3 A first leachate was obtained in the same manner as in Example 1, except that the amount of sulfuric acid used was adjusted as shown in Table 2.

[0082] Example 4 A first leachate was obtained in the same manner as in Example 1, except that the amount of sulfuric acid used was adjusted as shown in Table 2.

[0083] Example 5 A first leachate was obtained in the same manner as in Example 1, except that the amount of sulfuric acid used was adjusted as shown in Table 2.

[0084] Example 6 A first leachate was obtained in the same manner as in Example 1, except that the amounts of sulfuric acid and oxidizing agent used were adjusted as shown in Table 2.

[0085] Comparative Example 1 A first leachate was obtained in the same manner as in Example 1, except that the amount of sulfuric acid used was adjusted as shown in Table 2 and no oxidizing agent was added.

[0086] Comparative Example 2 The first leachate was obtained in the same manner as in Example 1, except that the amount of sulfuric acid used was adjusted as shown in Table 2 and 2.25 g of hydrogen peroxide (H2O2) was added instead of adding an oxidizing agent (sodium persulfate).

[0087] [Table 1]

[0088] [Table 2]

[0089] Experimental Example 1 (1) Measurement of calcium and magnesium content after washing process The Ca and Mg contents in the liquid product after the washing step were confirmed by inductively coupled plasma (ICP) analysis and were found to be 280 wt ppm and 780 wt ppm, respectively, which were 46 wt% and 23 wt% of the Ca and Mg levels in the nickel-containing mixed hydroxide precipitate before the washing step.

[0090] (2) Measurement of impurity extraction rate from leachate The weights of Co, Mn, Mg, Fe, Zn, Ca, and Al in the nickel-containing mixed hydroxide precipitate and the weights of Co, Mn, Mg, Fe, Zn, Ca, and Al in the first leachate were measured, and the weight of the metal in the first leachate relative to the weight of the metal in the nickel-containing mixed hydroxide precipitate was calculated as wt % for each metal.

[0091] (3) Measurement of metal concentration and pH in the first leachate The concentrations of Co, Mn, Mg, Fe, Zn, Ca, Al and Na in the first leachate were calculated as the weight of the metal in the first leachate relative to the weight of the first leachate, expressed as wt% of each metal. The pH of the first infusion was also measured. The results of the measurements are shown in Tables 3 and 4 below.

[0092] [Table 3]

[0093] [Table 4]

[0094] Referring to Tables 3 and 4, when an oxidizing agent was used in leaching a nickel-containing hydroxide precipitate, a first leachate was obtained in which the leaching rates of Co, Mn, Fe, and Al were reduced. According to the Examples, when the pH of the first leachate was adjusted to 3 or more and less than 5, the leaching rates of Co, Mn, Fe, and Al in the first leachate were 3 wt% or less. Therefore, selective nickel leaching was possible without requiring an additional process for removing cobalt and manganese.

[0095] In Example 3, where the pH of the first leachate was less than 3, the leaching rate of Al increased relatively.

[0096] In Example 4, where the pH of the first leachate was 5 or higher, the leaching rates of Ni and Zn were relatively reduced.

[0097] In Example 5, where the pH of the first leachate was less than 2, the leaching rates of Co, Fe, and Al increased relatively.

[0098] In Example 6, in which the pH of the first leachate was less than 3 and the amount of oxidizing agent added was reduced, the leaching rates of Co, Mn, and Al increased relatively.

[0099] In Comparative Example 1, in which the pH of the first leachate was less than 1 and no oxidizing agent was added, the leaching rates of Co, Mn, Fe and Al all increased compared to the Examples.

[0100] In Comparative Example 2, in which the pH of the first leachate was less than 1 and hydrogen peroxide (H2O2) was added without adding sodium persulfate, the leaching rates of Co, Mn, Fe, and Al all increased compared to the Examples.

[0101] Experimental Example 2: Measurement of Ca, Mg concentrations and pH in leachate Example 7 50 g of unwashed nickel-containing hydroxide precipitate (Ni-MHP) was added to 15 g of 2 M sulfuric acid and 2.9 g of sodium persulfate (NaSO) as an oxidizing agent, and leached at 80°C for 6 hours to obtain a first leachate. The first leachate was precipitated for 4 hours using 1.15 g of sodium fluoride (NaF) as a precipitant to obtain a second leachate.

[0102] Example 8 A second leachate was obtained in the same manner as in Example 7, except that 1.4 g of sodium fluoride was used. The concentrations of Mg and Ca in the second leachate of Examples 7 and 8 were calculated in wt ppm, and the pH of the leachate was also measured. The measurement results are shown in Table 5 below.

[0103] [Table 5]

[0104] Referring to Table 5, when the Ca and Mg in the first leachate of nickel-containing hydroxide precipitate, in which nickel had been selectively leached, were precipitated using sodium fluoride (NaF), a second leachate was obtained in which the Ca and Mg had been removed by 90 wt% or more compared to the first leachate.

Claims

1. providing a nickel-containing feedstock; selectively leaching nickel from the nickel-containing raw material using an oxidizing agent to produce a first leachate; separating residual metals from the first leachate to produce a second leachate; obtaining nickel sulfate from the second leachate.

2. 2. The method for producing nickel sulfate according to claim 1, wherein the nickel-containing raw material comprises nickel (Ni)-mixed hydroxide precipitate (MHP).

3. The method for producing nickel sulfate according to claim 2, wherein the Ni-MHP further contains cobalt and manganese.

4. 4. The method for producing nickel sulfate according to claim 3, wherein the step of producing the first leachate includes leaching only nickel out of nickel, cobalt, and manganese contained in the Ni-MHP.

5. The method of claim 1 , wherein the oxidizing agent comprises a metal persulfate.

6. 2. The method for producing nickel sulfate according to claim 1, wherein the step of producing the first leachate is performed using an acidic solution containing the oxidizing agent under a condition of pH 2 or higher.

7. 2. The method of claim 1, wherein the step of separating the residual metals to produce the second leach solution includes precipitating at least one of calcium and magnesium using a fluoride precipitant.

8. 8. The method of claim 7, wherein the step of separating the residual metals to produce the second leach solution further comprises precipitating or extracting zinc.

9. 9. The method for producing nickel sulfate according to claim 8, wherein precipitating the zinc is carried out using a sulfide precipitant.

10. The method for producing nickel sulfate according to claim 8, wherein the zinc is extracted using a phosphoric acid-based extractant.

11. 2. The method of claim 1, further comprising washing the nickel-containing raw material prior to producing the first leach solution.

12. 12. The method for producing nickel sulfate according to claim 11, wherein the step of washing the nickel-containing raw material includes partially removing calcium or magnesium contained in the nickel-containing raw material.

13. 12. The method for producing nickel sulfate according to claim 11, wherein the step of washing the nickel-containing raw material is carried out using water at 40°C to 100°C.

14. 2. The method of claim 1, wherein the step of obtaining nickel sulfate comprises crystallizing nickel sulfate hydrate.

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