A method for selective leaching and impurity removal of nickel and cobalt hydroxide

Abstract

The present invention provides a method for selectively leaching and removing impurities from nickel and cobalt hydroxide. The method comprises: slurrying nickel and cobalt hydroxide raw materials, then sequentially adding acid and nickel and cobalt hydroxide to adjust the pH value, and obtaining a pre-leached liquid and a pre-leached residue after leaching; slurrying the pre-leached residue, then sequentially adding acid, a reducing agent, and nickel and cobalt hydroxide to obtain a first leachate and a first leach residue after leaching; slurrying the first leach residue, then adding acid, and obtaining a second leachate and a second leach residue after leaching; wherein the second leachate contains copper ions, iron ions, and aluminum ions; mixing the second leachate with a pH adjusting agent, and obtaining a third leachate and a third leach residue after leaching; wherein the third leach residue contains iron and aluminum elements; mixing the third leachate with acid, then adding a copper reducing agent to carry out a reduction reaction, and obtaining a fourth leachate and a fourth leach residue after leaching. This method can improve efficiency and save costs.

Description

Technical Field

[0001] The invention belongs to the technical field of hydrometallurgy, and in particular relates to a method for selectively leaching and removing impurities from nickel and cobalt hydroxide. Background Art

[0002] With the rapid development of the national economy, the demand for nickel and cobalt is increasing. The rapid development of new energy vehicles in recent years has led to the rapid development of ternary lithium-ion batteries, which has also greatly increased the demand for nickel sulfate and cobalt sulfate. Leaching nickel cobalt hydroxide, an intermediate product from laterite nickel ore smelting, to produce battery-grade nickel sulfate and cobalt sulfate will become one of the main methods.

[0003] Currently, the process for leaching and removing impurities from nickel and cobalt hydroxide mainly includes acid leaching, copper removal, iron and aluminum removal, and other steps. For example, patent CN112210679A discloses a method for preparing nickel sulfate from nickel and cobalt hydroxide. The method comprises: S1, subjecting nickel and cobalt hydroxide to acid leaching under the action of sulfuric acid and a reducing agent to obtain a leachate; S2, adding a catalyst, an oxidizing agent, and a neutralizing agent to the leachate to simultaneously perform a catalytic oxidation reaction and a neutralization reaction to obtain a first impurity-removing solution; S3, extracting and removing impurities from the first impurity-removing solution, and evaporating and crystallizing to obtain nickel sulfate. However, this method has obvious drawbacks: the metal content in the slag is high, a large amount of oxidizing and reducing agents are required, the cost is high, and the process flow is long.

[0004] Therefore, there is an urgent need to design a low-cost nickel cobalt hydroxide leaching and impurity removal method, which can not only shorten the production process and improve production efficiency, but also reduce metal loss in solid waste residue and increase metal recovery rate. Summary of the Invention

[0005] In view of the shortcomings of the prior art, the purpose of the present invention is to provide a method for selective leaching and impurity removal of nickel and cobalt hydroxide. The method provided by the present invention can directly extract nickel and cobalt by mixing the pre-leaching solution and the first leachate, which not only shortens the production process and improves production efficiency, but also reduces energy consumption and saves production costs; moreover, the method reduces metal loss in solid waste residue and improves metal recovery rate. At the same time, the fourth leachate can be refluxed into the pre-leaching residue, effectively reducing the amount of reducing agent used and saving production costs. In summary, this method has good development potential.

[0006] In order to achieve the purpose of the invention, the present invention adopts the following technical solutions:

[0007] The present invention provides a method for selectively leaching and removing impurities from nickel and cobalt hydroxide, the method comprising the following steps:

[0008] (1) preparing a slurry of nickel cobalt hydroxide raw material, then sequentially adding an acid solution and nickel cobalt hydroxide to adjust the pH value, and obtaining a pre-leaching solution and a pre-leaching residue after leaching;

[0009] (2) slurrying the pre-leached residue, and then sequentially adding an acid solution, a reducing agent, and nickel cobalt hydroxide to obtain a first leachate and a first leach residue after leaching;

[0010] (3) pulping the first leached residue, adding acid solution, and leaching to obtain a second leaching solution and a second leached residue;

[0011] Wherein, the second leachate contains copper ions, iron ions and aluminum ions;

[0012] (4) mixing the second leachate and a pH regulator, and leaching to obtain a third leachate and a third leach residue;

[0013] Wherein, the third leaching residue contains iron and aluminum elements;

[0014] (5) The third leachate and the acid solution are mixed, and then a copper reducing agent is added to carry out a reduction reaction, and a fourth leachate and a fourth leach residue are obtained after leaching.

[0015] The method provided by the present invention can directly extract nickel and cobalt by mixing the pre-leaching solution and the first leachate, which not only shortens the production process and improves production efficiency, but also reduces energy consumption and saves production costs. In addition, this method reduces metal loss in solid waste residue and improves metal recovery rate. At the same time, the fourth leachate can be refluxed into the pre-leaching residue, effectively reducing the amount of reducing agent used and saving production costs. In summary, this method has good development potential.

[0016] Preferably, the acid solution in step (1) comprises sulfuric acid.

[0017] It should be noted that the present invention does not limit the concentration of sulfuric acid, and it can be, for example, 200 g / L, 250 g / L, or 300 g / L, etc. The same applies to the following sulfuric acid.

[0018] Preferably, after the acid solution is added in step (1), the pH value of the slurry is 1-1.5, for example, it can be 1, 1.1, 1.2, 1.3, 1.4 or 1.5.

[0019] In the present invention, after the acid solution is added in step (1), the pH value of the slurry is adjusted to 1-1.5, which is beneficial to improving the leaching rate of valuable metals in nickel and cobalt hydroxide.

[0020] Preferably, after the pH value is adjusted by adding acid solution and nickel cobalt hydroxide in step (1), the pH value of the slurry is 5.5-6.5, for example, it can be 5.5, 5.7, 5.9, 6, 6.1, 6.3 or 6.5.

[0021] In the present invention, the pH value of the slurry is 5.5-6.5, which is conducive to precipitating the impurity metals Cu / Fe / Al in the solution, realizing solid-liquid separation of valuable metals and impurity metals, that is, realizing selective leaching of nickel, cobalt and manganese.

[0022] Preferably, the reaction occurs during the pH adjustment process in step (1), and the reaction time is 0.5-5 h, for example, 0.5 h, 1 h, 2 h, 3 h, 4 h or 5 h.

[0023] Preferably, the acid solution in step (2) comprises sulfuric acid.

[0024] Preferably, after the acid solution is added in step (2), the pH value of the slurry is 1-1.5, for example, it can be 1, 1.1, 1.2, 1.3, 1.4 or 1.5.

[0025] In the present invention, after the acid solution is added in step (2), the pH value of the slurry is adjusted to 1-1.5, which is beneficial to improving the leaching rate of valuable metals in the prepreg residue and providing an acidic atmosphere for the redox reaction.

[0026] Preferably, the reducing agent in step (2) includes any one of hydrogen peroxide, sodium sulfite, sodium bisulfite, sodium thiosulfate or iron powder, or a combination of at least two thereof.

[0027] In the present invention, the function of adding the reducing agent is to reduce high-valent Ni / Co / Mn to low-valent Ni / Co / Mn, thereby increasing the leaching rate of valuable metals.

[0028] Preferably, the amount of the reducing agent added in step (2) is 1-1.5 times the theoretical amount, for example, it can be 1 time, 1.1 times, 1.2 times, 1.3 times, 1.4 times or 1.5 times, etc.

[0029] It should be noted that the theoretical dosage refers to the amount required for the complete reaction of the reducing agent with the Ni / Co / Mn in the pre-leached slag after acid addition.

[0030] Preferably, after the nickel cobalt hydroxide is added in step (2), the pH value of the slurry is 5.5-6.5, for example, it can be 5.5, 5.7, 5.9, 6, 6.1, 6.3 or 6.5.

[0031] In the present invention, the pH value of the slurry is 5.5-6.5, which is conducive to precipitating the impurity metals Cu / Fe / Al in the solution and realizing solid-liquid separation of valuable metals and impurity metals, that is, realizing selective leaching of nickel, cobalt and manganese.

[0032] Preferably, in the first leachate of step (2), the total concentration of nickel ions, cobalt ions and manganese ions is 120-150 g / L, for example, 120 g / L, 130 g / L, 140 g / L or 150 g / L.

[0033] In the first leachate of the present invention, the total concentration of nickel ions, cobalt ions and manganese ions is 120-150 g / L, which can improve production efficiency, reduce production water consumption, and reduce the loss of organic solvent in the back-end extraction. If the total concentration of nickel ions, cobalt ions and manganese ions exceeds the maximum limit, crystallization may occur, causing pipeline blockage and other problems.

[0034] Preferably, the pre-leaching solution of step (1) and the first leaching solution of step (2) are mixed and used in the nickel-cobalt extraction process.

[0035] In the present invention, the pre-leaching liquid and the first leaching liquid directly enter the extraction process, which can shorten the production process, improve production efficiency, reduce energy consumption, and save production costs.

[0036] Preferably, the total mass proportion of copper, iron and aluminum elements in the nickel cobalt hydroxide raw material in step (1) is recorded as M1, and the total mass proportion of copper, iron and aluminum elements in the first leaching residue in step (2) is recorded as M2, and the ratio of M2 to M1 is ≥20, for example, it can be 50, 70 or 100, etc.

[0037] In the present invention, the ratio of M2 to M1 is ≥20, indicating that the valuable metals have been selectively leached and the impurity elements have been enriched.

[0038] Preferably, the acid solution in step (3) comprises sulfuric acid.

[0039] Preferably, after the acid solution is added in step (3), the pH value of the slurry is 1-2, for example, it can be 1, 1.1, 1.2, 1.3, 1.4, 1.5, 1.6, 1.7, 1.8, 1.9 or 2.

[0040] In the present invention, after the acid solution is added in step (3), the pH value of the slurry is adjusted to 1-2, which is conducive to the selective leaching of the impurity elements Cu / Fe / Al in the first leaching residue.

[0041] Preferably, the pH adjuster in step (4) comprises any one of alkali solution, carbonate or alkaline oxide, or a combination of at least two thereof.

[0042] In the present invention, the addition of the above-mentioned pH adjuster is beneficial to increase the pH value, promote the hydrolysis of Fe and Al in the solution, and generate ferric hydroxide and aluminum hydroxide precipitation.

[0043] Preferably, the alkali solution comprises sodium hydroxide solution.

[0044] Preferably, the carbonate includes any one of sodium carbonate, calcium carbonate, nickel carbonate, cobalt carbonate or manganese carbonate, or a combination of at least two thereof.

[0045] Preferably, the carbonate further comprises basic carbonate.

[0046] Preferably, the basic carbonate includes any one of nickel carbonate hydroxide, cobalt carbonate hydroxide or manganese carbonate hydroxide, or a combination of at least two thereof.

[0047] Preferably, the basic oxide comprises calcium oxide and / or magnesium oxide.

[0048] Preferably, the mixing temperature in step (4) is 60-95°C, for example, it can be 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C or 95°C.

[0049] In the present invention, if the mixing temperature in step (4) is too low, selective leaching becomes difficult; if the mixing temperature in step (4) is too high, the solution boils, resulting in energy waste and increased costs.

[0050] Preferably, the pH of the mixed solution obtained by mixing the second leachate and the pH regulator in step (4) is 3.8-4.5, for example, it can be 3.8, 4, 4.1, 4.3 or 4.5.

[0051] In the present invention, the pH of the mixed solution obtained by mixing the second leachate and the pH regulator is 3.8-4.5, and within this range, iron and aluminum elements can be effectively precipitated.

[0052] Preferably, the reaction occurs during the mixing process in step (4), and the reaction time is 0.5-5 h, for example, 0.5 h, 1 h, 2 h, 3 h, 4 h or 5 h.

[0053] Preferably, the acid solution in step (5) comprises sulfuric acid.

[0054] Preferably, after the third leachate and the acid solution are mixed in step (5), the pH value of the obtained solution is 1-2, for example, it can be 1, 1.2, 1.4, 1.6, 1.8 or 2.

[0055] In the present invention, after the third leaching solution and the acid solution are mixed, the pH value of the obtained solution is 1-2. This pH value range is conducive to the reaction between the copper reducing agent and the Cu 2+ Reaction to produce sponge copper.

[0056] Preferably, the copper reducing agent in step (5) comprises iron powder.

[0057] In the method provided by the present invention, iron and aluminum are removed first, and then copper is removed, which can effectively avoid the reaction between iron powder and trivalent iron ions in the third leachate and reduce the amount of iron powder used.

[0058] Preferably, the amount of the copper reducing agent in step (5) is 1-1.5 times the theoretical amount, for example, 1 time, 1.1 times, 1.2 times, 1.3 times, 1.4 times or 1.5 times, etc.

[0059] It should be noted that the theoretical dosage refers to the dosage required for the complete reaction of the copper reducing agent with the copper ions in the third leachate.

[0060] Preferably, the reduction reaction time in step (5) is 1-5 h, for example, 1 h, 2 h, 3 h, 4 h or 5 h.

[0061] In the present invention, the reduction reaction time is 1-5 hours, which can fully precipitate and remove the copper ions in the third leachate.

[0062] Preferably, the fourth leachate in step (5) is refluxed into the pre-leached residue in step (2) for slurrying.

[0063] In the present invention, the fourth leachate is refluxed, which can reduce the amount of reducing agent used in step (2), save production costs, and improve the recovery rate of valuable metals.

[0064] Preferably, the method comprises the following steps:

[0065] (1) Selective leaching of nickel and cobalt:

[0066] a) mixing a nickel cobalt hydroxide raw material and water in a mass volume ratio of 1 g: (2.5-5) mL (for example, 1 g: 2.5 mL, 1 g: 3 mL, 1 g: 3.5 mL, 1 g: 4 mL, 1 g: 4.5 mL or 1 g: 5 mL, etc.) to prepare a slurry, then adding an acid solution to adjust the pH value of the slurry to 1-1.5, reacting for 0.5-5 h, then adding nickel cobalt hydroxide to adjust the pH value of the slurry to 5.5-6.5, reacting for 0.5-5 h, and filtering to obtain a preleaching solution and a preleaching residue;

[0067] b) mixing the pre-leached residue and water in a mass volume ratio of 1 g:(2.5-5) mL (for example, 1 g:2.5 mL, 1 g:3 mL, 1 g:3.5 mL, 1 g:4 mL, 1 g:4.5 mL, or 1 g:5 mL, etc.) to prepare a slurry, then adding an acid solution to adjust the pH value of the slurry to 1-1.5, reacting for 0.5-5 h, then adding a reducing agent, and then adding nickel cobalt hydroxide to adjust the pH value of the slurry to 5.5-6.5, reacting for 0.5-5 h, and filtering to obtain a first leachate and a first leach residue;

[0068] The total concentration of nickel ions, cobalt ions and manganese ions in the first leachate is 120-150 g / L, and the pre-leachate and the first leachate are mixed for the nickel and cobalt extraction process;

[0069] (2) Selective leaching of copper, iron and aluminum:

[0070] The first leach residue and water are mixed in a mass volume ratio of 1 g: (2.5-5) mL (for example, 1 g: 2.5 mL, 1 g: 3 mL, 1 g: 3.5 mL, 1 g: 4 mL, 1 g: 4.5 mL, or 1 g: 5 mL, etc.) to prepare a slurry, and then an acid solution is added to adjust the pH value of the slurry to 1-2, reacting for 0.5-5 h, and filtering to obtain a second leachate and a second leach residue;

[0071] Wherein, the second leachate contains copper ions, iron ions and aluminum ions;

[0072] (3) Selective precipitation of iron and aluminum:

[0073] The second leachate is heated to 60-95° C., and an alkali solution is added to adjust the pH value of the second leachate to 3.8-4.5, reacting for 1-5 hours, and filter pressing to obtain a third leachate and a third leach residue;

[0074] Wherein, the third leaching residue contains iron and aluminum elements;

[0075] (4) Selective precipitation of copper:

[0076] adding acid to the third leachate to adjust the pH value of the third leachate to 1-2, adding iron powder to carry out a reduction reaction for 1-5 hours, and filtering to obtain a fourth leachate and a fourth leach residue;

[0077] The fourth leachate is returned to the pre-leached residue and pulped according to a mass volume ratio of 1g:(2.5-5)mL (for example, 1g:2.5mL, 1g:3mL, 1g:3.5mL, 1g:4mL, 1g:4.5mL or 1g:5mL, etc.).

[0078] The numerical range described in the present invention includes not only the point values ​​listed above, but also any point values ​​between the above numerical ranges that are not listed. Due to space limitations and for the sake of simplicity, the present invention no longer exhaustively lists the specific point values ​​included in the range.

[0079] Compared with the prior art, the present invention has the following beneficial effects:

[0080] The method provided by the present invention can directly extract nickel and cobalt by mixing the pre-leaching solution and the first leachate, which not only shortens the production process and improves production efficiency, but also reduces energy consumption and saves production costs. In addition, this method reduces metal loss in solid waste residue and improves metal recovery rate. At the same time, the fourth leachate can be refluxed into the pre-leaching residue, effectively reducing the amount of reducing agent used and saving production costs. In summary, this method has good development potential. BRIEF DESCRIPTION OF THE DRAWINGS

[0081] Figure 1 This is a process flow chart for selective leaching and impurity removal of nickel and cobalt hydroxide in Example 1 of the present invention. DETAILED DESCRIPTION

[0082] The technical solution of the present invention is further described below by way of specific embodiments. It should be understood by those skilled in the art that the embodiments are merely to help understand the present invention and should not be regarded as specific limitations of the present invention.

[0083] It should be noted that the nickel cobalt hydroxide raw material used in the following embodiments includes the following components in terms of mass fraction:

[0084] Nickel: 23.26%, Cobalt: 1.95%, Manganese: 3.14%, Copper: 0.51%, Iron: 0.14%, Aluminum: 0.03%.

[0085] Example 1

[0086] This embodiment provides a method for selectively leaching and removing impurities from nickel and cobalt hydroxide, and its process flow chart is as follows: Figure 1 As shown, the method includes the following steps:

[0087] (1) Selective leaching of nickel and cobalt:

[0088] a) 10 tons of nickel cobalt hydroxide raw material and water were mixed in a mass volume ratio of 1 g: 5 mL to prepare a slurry, and then sulfuric acid with a concentration of 250 g / L was added to adjust the pH value of the slurry to 1, and the mixture was allowed to stand for 2 hours. Then, nickel cobalt hydroxide was added to adjust the pH value of the slurry to 5.5, and the mixture was allowed to stand for 2 hours. The mixture was filtered to obtain a pre-leached solution and a pre-leached residue;

[0089] b) mixing the pre-leached residue and water in a mass volume ratio of 1 g:5 mL to prepare a slurry, then adding sulfuric acid having a concentration of 250 g / L to adjust the pH value of the slurry to 1, letting it stand for 2 hours, then adding hydrogen peroxide, and then adding nickel cobalt hydroxide to adjust the pH value of the slurry to 5.5, letting it stand for 2 hours, and filter pressing to obtain a first leachate and a first leach residue;

[0090] The total concentration of nickel ions, cobalt ions, and manganese ions in the first leachate is 148.39 g / L. The pre-leachate and the first leachate are mixed for the nickel-cobalt extraction process. The amount of hydrogen peroxide added is 1.5 times the theoretical amount. The total mass proportion of copper, iron, and aluminum in the nickel-cobalt hydroxide raw material is recorded as M1. The total mass proportion of copper, iron, and aluminum in the first leaching residue is recorded as M2. The ratio of M2 to M1 is 35.41.

[0091] (2) Selective leaching of copper, iron and aluminum:

[0092] The first leach residue and water were mixed in a mass volume ratio of 1 g:5 mL to prepare a slurry, and then sulfuric acid with a concentration of 250 g / L was added to adjust the pH value of the slurry to 1, reacted for 2 hours, and filtered to obtain a second leachate and a second leach residue;

[0093] Wherein, the second leachate contains copper ions, iron ions and aluminum ions;

[0094] (3) Selective precipitation of iron and aluminum:

[0095] The second leachate was heated to 60° C., and calcium carbonate was added to adjust the pH value of the second leachate to 3.8, and the mixture was allowed to stand for 2 hours and filtered to obtain a third leachate and a third leach residue;

[0096] Wherein, the third leaching residue contains iron and aluminum elements;

[0097] (4) Selective precipitation of copper:

[0098] adding 250 g / L sulfuric acid to the third leachate at 60° C., adjusting the pH value of the third leachate to 1, adding 1 times the theoretical amount of iron powder for a reduction reaction for 2 hours, and filtering to obtain a fourth leachate and a fourth leach residue;

[0099] The fourth leachate is returned to the pre-leached residue to prepare a slurry in a mass-to-volume ratio of 1 g:5 mL.

[0100] Example 2

[0101] This embodiment provides a method for selectively leaching and removing impurities from nickel and cobalt hydroxide, the method comprising the following steps:

[0102] (1) Selective leaching of nickel and cobalt:

[0103] a) mixing 10 tons of nickel cobalt hydroxide raw material and water in a mass volume ratio of 1 g:5 mL to prepare a slurry, then adding sulfuric acid with a concentration of 260 g / L to adjust the pH value of the slurry to 1.1, reacting for 2 hours, then adding nickel cobalt hydroxide to adjust the pH value of the slurry to 6, reacting for 2 hours, and filter pressing to obtain a preleaching solution and a preleaching residue;

[0104] b) mixing the pre-leached residue and water in a mass volume ratio of 1 g:5 mL to prepare a slurry, then adding sulfuric acid having a concentration of 260 g / L to adjust the pH value of the slurry to 1.1, reacting for 2 h, then adding hydrogen peroxide, and then adding nickel cobalt hydroxide to adjust the pH value of the slurry to 6, reacting for 2 h, and filtering to obtain a first leachate and a first leach residue;

[0105] The total concentration of nickel ions, cobalt ions, and manganese ions in the first leachate is 138.54 g / L. The pre-leachate and the first leachate are mixed for the nickel-cobalt extraction process. The amount of hydrogen peroxide added is 1.3 times the theoretical amount. The total mass proportion of copper, iron, and aluminum in the nickel-cobalt hydroxide raw material is recorded as M1. The total mass proportion of copper, iron, and aluminum in the first leaching residue is recorded as M2. The ratio of M2 to M1 is 30.93.

[0106] (2) Selective leaching of copper, iron and aluminum:

[0107] The first leach residue and water were mixed in a mass volume ratio of 1 g:5 mL to prepare a slurry, and then sulfuric acid with a concentration of 270 g / L was added to adjust the pH value of the slurry to 1.2, reacted for 2 hours, and filtered to obtain a second leachate and a second leach residue;

[0108] Wherein, the second leachate contains copper ions, iron ions and aluminum ions;

[0109] (3) Selective precipitation of iron and aluminum:

[0110] The second leachate was heated to 60° C., and calcium carbonate was added to adjust the pH value of the second leachate to 4.0, reacted for 2 hours, and filtered to obtain a third leachate and a third leach residue;

[0111] Wherein, the third leaching residue contains iron and aluminum elements;

[0112] (4) Selective precipitation of copper:

[0113] adding sulfuric acid to the third leachate at 60° C. to adjust the pH value of the third leachate to 1.2, adding iron powder in an amount 1.2 times the theoretical amount to carry out a reduction reaction for 2 hours, and filtering to obtain a fourth leachate and a fourth leach residue;

[0114] The fourth leachate is returned to the pre-leached residue to prepare a slurry in a mass-to-volume ratio of 1 g:5 mL.

[0115] Example 3

[0116] This embodiment provides a method for selectively leaching and removing impurities from nickel and cobalt hydroxide, the method comprising the following steps:

[0117] (1) Selective leaching of nickel and cobalt:

[0118] a) 10 tons of nickel cobalt hydroxide raw material and water were mixed in a mass volume ratio of 1 g: 5 mL to prepare a slurry, and then sulfuric acid with a concentration of 270 g / L was added to adjust the pH value of the slurry to 1.2, and the reaction was carried out for 2 hours. Then, nickel cobalt hydroxide was added to adjust the pH value of the slurry to 6, and the reaction was carried out for 2 hours. The mixture was filtered to obtain a pre-leached solution and a pre-leached residue;

[0119] b) mixing the pre-leached residue and water in a mass volume ratio of 1 g:5 mL to prepare a slurry, then adding sulfuric acid to adjust the pH value of the slurry to 1.2, reacting for 2 h, then adding hydrogen peroxide, and then adding nickel cobalt hydroxide to adjust the pH value of the slurry to 6, standing for 2 h, and filter pressing to obtain a first leachate and a first leach residue;

[0120] The total concentration of nickel ions, cobalt ions, and manganese ions in the first leachate is 133.29 g / L. The pre-leachate and the first leachate are mixed for the nickel-cobalt extraction process. The amount of hydrogen peroxide added is 1.2 times the theoretical amount. The total mass proportion of copper, iron, and aluminum in the nickel-cobalt hydroxide raw material is recorded as M1. The total mass proportion of copper, iron, and aluminum in the first leaching residue is recorded as M2. The ratio of M2 to M1 is 27.25.

[0121] (2) Selective leaching of copper, iron and aluminum:

[0122] The first leach residue and water were mixed in a mass volume ratio of 1 g:5 mL to prepare a slurry, and then sulfuric acid with a concentration of 300 g / L was added to adjust the pH value of the slurry to 1.4, reacted for 2 hours, and filtered to obtain a second leachate and a second leach residue;

[0123] Wherein, the second leachate contains copper ions, iron ions and aluminum ions;

[0124] (3) Selective precipitation of iron and aluminum:

[0125] The second leachate was heated to 60° C., and calcium carbonate was added to adjust the pH value of the second leachate to 4, reacted for 2 hours, and filtered to obtain a third leachate and a third leach residue;

[0126] Wherein, the third leaching residue contains iron and aluminum elements;

[0127] (4) Selective precipitation of copper:

[0128] adding sulfuric acid to the third leachate at 60° C. to adjust the pH value of the third leachate to 1.4, adding iron powder in an amount 1.3 times the theoretical amount to carry out a reduction reaction for 2 hours, and filtering to obtain a fourth leachate and a fourth leach residue;

[0129] The fourth leachate is returned to the pre-leached residue to prepare a slurry in a mass-to-volume ratio of 1 g:5 mL.

[0130] Example 4

[0131] This embodiment provides a method for selectively leaching and removing impurities from nickel and cobalt hydroxide, the method comprising the following steps:

[0132] (1) Selective leaching of nickel and cobalt:

[0133] a) mixing 10 tons of nickel cobalt hydroxide raw material and water in a mass volume ratio of 1 g:5 mL to prepare a slurry, then adding sulfuric acid with a concentration of 285 g / L to adjust the pH value of the slurry to 1.3, reacting for 2 hours, then adding nickel cobalt hydroxide to adjust the pH value of the slurry to 6.5, reacting for 2 hours, and filter pressing to obtain a preleaching solution and a preleaching residue;

[0134] b) mixing the pre-leached residue and water in a mass volume ratio of 1 g:5 mL to prepare a slurry, then adding sulfuric acid having a concentration of 285 g / L to adjust the pH value of the slurry to 1.3, reacting for 2 h, then adding hydrogen peroxide, and then adding nickel cobalt hydroxide to adjust the pH value of the slurry to 6.5, reacting for 2 h, and filter pressing to obtain a first leachate and a first leach residue;

[0135] The total concentration of nickel ions, cobalt ions, and manganese ions in the first leachate is 125.58 g / L. The pre-leachate and the first leachate are mixed for the nickel-cobalt extraction process. The amount of hydrogen peroxide added is 1.1 times the theoretical amount. The total mass proportion of copper, iron, and aluminum in the nickel-cobalt hydroxide raw material is recorded as M1. The total mass proportion of copper, iron, and aluminum in the first leaching residue is recorded as M2. The ratio of M2 to M1 is 25.28.

[0136] (2) Selective leaching of copper, iron and aluminum:

[0137] The first leach residue and water were mixed in a mass volume ratio of 1 g:5 mL to prepare a slurry, and then sulfuric acid with a concentration of 330 g / L was added to adjust the pH value of the slurry to 1.6, reacted for 2 hours, and filtered to obtain a second leachate and a second leach residue;

[0138] Wherein, the second leachate contains copper ions, iron ions and aluminum ions;

[0139] (3) Selective precipitation of iron and aluminum:

[0140] The second leachate was heated to 60° C., and calcium carbonate was added to adjust the pH value of the second leachate to 4.5, reacted for 2 hours, and filtered to obtain a third leachate and a third leach residue;

[0141] Wherein, the third leaching residue contains iron and aluminum elements;

[0142] (4) Selective precipitation of copper:

[0143] adding sulfuric acid to the third leachate at 60° C. to adjust the pH value of the third leachate to 1.6, adding iron powder in an amount 1.4 times the theoretical amount to carry out a reduction reaction for 2 hours, and filtering to obtain a fourth leachate and a fourth leach residue;

[0144] The fourth leachate is returned to the pre-leached residue to prepare a slurry in a mass-to-volume ratio of 1 g:5 mL.

[0145] Example 5

[0146] This embodiment provides a method for selectively leaching and removing impurities from nickel and cobalt hydroxide, the method comprising the following steps:

[0147] (1) Selective leaching of nickel and cobalt:

[0148] a) 10 tons of nickel cobalt hydroxide raw material and water were mixed in a mass volume ratio of 1 g: 2.5 mL to prepare a slurry, and then sulfuric acid with a concentration of 280 g / L was added to adjust the pH value of the slurry to 1.5, and the mixture was reacted for 5 h. Then, nickel cobalt hydroxide was added to adjust the pH value of the slurry to 6.5, and the mixture was reacted for 5 h. The mixture was filtered to obtain a pre-leached solution and a pre-leached residue;

[0149] b) mixing the pre-leached residue and water in a mass volume ratio of 1 g:2.5 mL to prepare a slurry, then adding sulfuric acid with a concentration of 280 g / L to adjust the pH value of the slurry to 1.5, reacting for 5 hours, then adding hydrogen peroxide, and then adding nickel cobalt hydroxide to adjust the pH value of the slurry to 6.5, reacting for 5 hours, and filtering to obtain a first leachate and a first leach residue;

[0150] The total concentration of nickel ions, cobalt ions, and manganese ions in the first leachate is 120.19 g / L. The pre-leachate and the first leachate are mixed for the nickel-cobalt extraction process. The amount of hydrogen peroxide added is 1.0 times the theoretical amount. The total mass proportion of copper, iron, and aluminum in the nickel-cobalt hydroxide raw material is recorded as M1. The total mass proportion of copper, iron, and aluminum in the first leaching residue is recorded as M2. The ratio of M2 to M1 is 22.94.

[0151] (2) Selective leaching of copper, iron and aluminum:

[0152] The first leach residue and water were mixed in a mass volume ratio of 1 g:2.5 mL to prepare a slurry, and then sulfuric acid with a concentration of 350 g / L was added to adjust the pH value of the slurry to 2.0, reacted for 5 hours, and filtered to obtain a second leachate and a second leach residue;

[0153] Wherein, the second leachate contains copper ions, iron ions and aluminum ions;

[0154] (3) Selective precipitation of iron and aluminum:

[0155] The second leachate was heated to 90° C., and calcium carbonate was added to adjust the pH value of the second leachate to 4.5, reacted for 5 hours, and filtered to obtain a third leachate and a third leach residue;

[0156] Wherein, the third leaching residue contains iron and aluminum elements;

[0157] (4) Selective precipitation of copper:

[0158] adding sulfuric acid to the third leachate at 60° C. to adjust the pH value of the third leachate to 2.0, adding iron powder in an amount 1.5 times the theoretical amount to carry out a reduction reaction for 5 hours, and filtering to obtain a fourth leachate and a fourth leach residue;

[0159] The fourth leachate is returned to the pre-leached residue to prepare a slurry in a mass-to-volume ratio of 1 g:2.5 mL.

[0160] Example 6

[0161] The difference between this embodiment and embodiment 1 is that sulfuric acid is added in step (a) to adjust the pH value of the slurry to 2.

[0162] The rest of the preparation methods and parameters remained the same as in Example 1.

[0163] Example 7

[0164] The difference between this embodiment and embodiment 1 is that nickel cobalt hydroxide is added in step (a) to adjust the pH value of the slurry to 5.

[0165] The rest of the preparation methods and parameters remained the same as in Example 1.

[0166] Example 8

[0167] The difference between this embodiment and embodiment 1 is that nickel cobalt hydroxide is added in step (a) to adjust the pH value of the slurry to 7.

[0168] The rest of the preparation methods and parameters remained the same as in Example 1.

[0169] Example 9

[0170] The difference between this embodiment and embodiment 1 is that sulfuric acid is added in step (b) to adjust the pH value of the slurry to 2.

[0171] The rest of the preparation methods and parameters remained the same as in Example 1.

[0172] Example 10

[0173] The difference between this embodiment and embodiment 1 is that nickel cobalt hydroxide is added in step (b) to adjust the pH value of the slurry to 5.

[0174] The rest of the preparation methods and parameters remained the same as in Example 1.

[0175] Example 11

[0176] The difference between this embodiment and embodiment 1 is that nickel cobalt hydroxide is added in step (b) to adjust the pH value of the slurry to 7.

[0177] The rest of the preparation methods and parameters remained the same as in Example 1.

[0178] Example 12

[0179] The difference between this embodiment and embodiment 1 is that sulfuric acid is added in step (2) to adjust the pH value of the slurry to 3.

[0180] The rest of the preparation methods and parameters remained the same as in Example 1.

[0181] Example 13

[0182] The difference between this embodiment and embodiment 1 is that calcium carbonate is added in step (3) to adjust the pH value of the second leachate to 3.5.

[0183] The rest of the preparation methods and parameters remained the same as in Example 1.

[0184] Example 14

[0185] The difference between this embodiment and embodiment 1 is that calcium carbonate is added in step (3) to adjust the pH value of the second leachate to 5.

[0186] The rest of the preparation methods and parameters remained the same as in Example 1.

[0187] Comparative Example 1

[0188] This comparative example provides a method for selectively leaching and removing impurities from nickel and cobalt hydroxide, the method comprising the following steps:

[0189] (1) 10 tons of nickel cobalt hydroxide raw material and water were slurried at a mass volume ratio of 1g:5mL, and then sulfuric acid was added to adjust the pH to 1.2. 0.65 tons of hydrogen peroxide (1.5 times the theoretical amount) was added, and after reacting for 2 hours, the leaching residue and leachate were filtered;

[0190] (2) heating the leachate to 60° C., adding 0.08 tons of iron powder as a reducing agent (1.1 times the theoretical amount), performing a reduction reaction for 2 hours, and filtering to obtain a copper-removed liquid and sponge copper;

[0191] (3) The copper-removed liquid is heated to 60° C., 0.23 tons of hydrogen peroxide (1.3 times the theoretical amount) is added, and then sodium hydroxide solution is added to adjust the pH value to 4. The iron- and aluminum-removed liquid and iron-aluminum slag are obtained by filtration.

[0192] Performance Testing

[0193] 1. The component contents of the mixed leachate obtained by mixing the pre-leachate and the first leachate in the method provided in the above embodiment are statistically analyzed, as shown in Table 1.

[0194] Table 1

[0195]

[0196]

[0197] 2. The contents of the components of the second leachate in the method provided in the above embodiment and the contents of the components of the copper-removed solution in the above comparative example were statistically analyzed, as shown in Table 2.

[0198] Table 2

[0199]

[0200]

[0201] 3. The contents of each component of the third leaching residue in the method provided in the above embodiment and the contents of each component of the iron-aluminum slag in the above comparative example were statistically analyzed, as shown in Table 3.

[0202] Table 3

[0203]

[0204]

[0205] Note: Impurity removal rate refers to the ratio of the iron / aluminum content in the third leaching residue to the iron / aluminum content in the nickel-cobalt hydroxide raw material.

[0206] 4. The mass of the pre-leached residue and the impurity content of the first leached residue in the method provided in the above embodiment were statistically analyzed, as shown in Table 4.

[0207] Table 4

[0208]

[0209]

[0210] analyze:

[0211] The method provided by the present invention can shorten the production process, improve production efficiency, and save production costs. As shown in Tables 1-3, this method reduces metal loss in solid waste residue, thereby increasing metal recovery. Furthermore, the fourth leachate can be refluxed into the pre-leached residue, effectively reducing the amount of reducing agent used and increasing the recovery rate of valuable metals. In summary, this method has great development potential.

[0212] It can be seen from Examples 1 and 6 that if the pH value of the slurry is adjusted too high by adding sulfuric acid in step (a), the acidity will be too weak, resulting in too low a metal concentration in the mixed leachate, affecting the extraction production process.

[0213] It can be seen from Example 1 and Examples 7-8 that if the pH value of the slurry adjusted by adding nickel cobalt hydroxide in step (a) is too small, the acidity is too strong, which will cause the content of impurity element Cu in the mixed leachate to be too high, affecting the quality of the product at the extraction end; if the pH value of the slurry adjusted by adding nickel cobalt hydroxide in step (a) is too large, that is, the acidity of the slurry is too weak, the amount of pre-leaching slag will be too large, affecting production efficiency.

[0214] As can be seen from Examples 1 and 9, if the pH value of the slurry is adjusted too high by adding sulfuric acid in step (b), the acidity will be too weak, which will lead to a reduced leaching rate of valuable metals and a low concentration of the mixed leachate, affecting the back-end extraction process.

[0215] It can be seen from Example 1 and Examples 10-11 that if the pH value of the slurry adjusted by adding nickel cobalt hydroxide in step (b) is too low, the acidity is too strong, resulting in too high a content of impurity element Cu in the mixed leachate, affecting the quality of the product at the extraction end; if the pH value of the slurry adjusted by adding nickel cobalt hydroxide in step (b) is too high, that is, the acidity of the slurry is too weak, it will cause precipitation of nickel, cobalt and manganese ions and a low concentration of the mixed leachate.

[0216] It can be seen from Examples 1 and 12 that if the pH value of the slurry adjusted by adding sulfuric acid in step (2) is too large, that is, the acidity is too weak, the Fe selective leaching is small, which will lead to a small content of Fe ions in the second leachate, resulting in a small content of impurity metal Fe in the third leach residue and a reduced removal rate.

[0217] It can be seen from Example 1 and Examples 13-14 that if the pH value of the second leachate adjusted by adding calcium carbonate in step (3) is too low, that is, the acidity is too strong, the removal rate of the impurity metal Al will be reduced, the content of Al in the third leaching residue is small, and the Al is enriched in the third leachate and cannot be removed; if the pH value of the second leachate adjusted by adding calcium carbonate in step (3) is too high, that is, the acidity is too weak, the valuable metal content in the third leaching residue will increase, and the valuable metal recovery rate will be reduced.

[0218] It can be seen from Example 1 and Comparative Example 1 that if the method described in Comparative Example 1 is adopted, a large amount of valuable metal loss will result in the iron and aluminum removal process, thereby reducing the recovery rate of valuable metals.

[0219] The applicant states that while the above-described embodiments illustrate the process of the present invention, the present invention is not limited to the above-described process steps, nor does it imply that the present invention must rely on the above-described process steps for implementation. Those skilled in the art will appreciate that any improvements to the present invention, equivalent substitutions for the raw materials used, additions of auxiliary components, and selection of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A method for selective leaching and impurity removal of nickel cobalt hydroxide, characterized in that: The method comprises the following steps: (1) preparing a slurry of nickel cobalt hydroxide raw material, then adding an acid solution to adjust the pH value of the slurry to 1-1.5, then adding nickel cobalt hydroxide to adjust the pH value of the slurry to 5.5-6.5, and obtaining a pre-leaching solution and a pre-leaching residue after leaching; (2) slurrying the pre-leached residue, then adding an acid solution to adjust the pH value of the slurry to 1-1.5, then adding a reducing agent, and then adding nickel cobalt hydroxide to adjust the pH value of the slurry to 5.5-6.5, and obtaining a first leachate and a first leach residue after leaching; In the first leachate, the total concentration of nickel ions, cobalt ions and manganese ions is 120-150 g / L; (3) slurrying the first leaching residue, then adding acid to adjust the pH value of the slurry to 1-2, and obtaining a second leachate and a second leaching residue after leaching; Wherein, the second leachate contains copper ions, iron ions and aluminum ions; (4) mixing the second leachate and a pH regulator, and leaching to obtain a third leachate and a third leach residue; Wherein, the third leaching residue contains iron and aluminum elements; (5) The third leachate and the acid solution are mixed, and then a copper reducing agent is added to carry out a reduction reaction, and a fourth leachate and a fourth leach residue are obtained after leaching.

2. The method according to claim 1, characterized in that The reducing agent in step (2) includes any one of hydrogen peroxide, sodium sulfite, sodium bisulfite, sodium thiosulfate or iron powder, or a combination of at least two of them.

3. The method according to claim 1, characterized in that The pre-leaching solution of step (1) and the first leaching solution of step (2) are mixed and used in the nickel-cobalt extraction process.

4. The method according to claim 1, wherein The total mass proportion of copper, iron and aluminum in the nickel cobalt hydroxide raw material in step (1) is recorded as M1, and the total mass proportion of copper, iron and aluminum in the first leaching residue in step (2) is recorded as M2, and the ratio of M2 to M1 is ≥20.

5. The method according to claim 1, characterized in that The pH regulator in step (4) includes any one of alkali solution, carbonate or alkaline oxide, or a combination of at least two of them.

6. The method according to claim 1, wherein The mixing temperature in step (4) is 60-95°C.

7. The method according to claim 1, characterized in that In step (4), the pH of the mixed solution obtained by mixing the second leachate and the pH regulator is 3.8-4.

5.

8. The method according to claim 1, characterized in that After the third leachate and the acid solution are mixed in step (5), the pH value of the obtained solution is 1-2.

9. The method according to claim 1, characterized in that The copper reducing agent in step (5) includes iron powder.

10. The method according to claim 1, characterized in that The reduction reaction time in step (5) is 1-5 hours.

11. The method according to claim 1, characterized in that The fourth leachate in step (5) is returned to the pre-leached residue in step (2) for slurrying.

12. The method according to claim 1, characterized in that The method comprises the following steps: (1) Selective leaching of nickel and cobalt: a) mixing nickel cobalt hydroxide raw material and water in a mass volume ratio of 1 g: (2.5-5) mL to prepare a slurry, then adding an acid solution to adjust the pH value of the slurry to 1-1.5, reacting for 0.5-5 hours, then adding nickel cobalt hydroxide to adjust the pH value of the slurry to 5.5-6.5, reacting for 0.5-5 hours, and filtering to obtain a preleaching solution and a preleaching residue; b) mixing the pre-leached residue and water in a mass volume ratio of 1 g:(2.5-5) mL to prepare a slurry, then adding an acid solution to adjust the pH value of the slurry to 1-1.5, reacting for 0.5-5 hours, then adding a reducing agent, and then adding nickel cobalt hydroxide to adjust the pH value of the slurry to 5.5-6.5, reacting for 0.5-5 hours, and filtering to obtain a first leachate and a first leach residue; The total concentration of nickel ions, cobalt ions and manganese ions in the first leachate is 120-150 g / L, and the pre-leachate and the first leachate are mixed for the nickel and cobalt extraction process; (2) Selective leaching of copper, iron and aluminum: The first leach residue and water are mixed in a mass volume ratio of 1 g: (2.5-5) mL to prepare a slurry, and then an acid solution is added to adjust the pH value of the slurry to 1-2, react for 0.5-5 hours, and filter press to obtain a second leachate and a second leach residue; Wherein, the second leachate contains copper ions, iron ions and aluminum ions; (3) Selective precipitation of iron and aluminum: The second leachate is heated to 60-95° C., and an alkali solution is added to adjust the pH value of the second leachate to 3.8-4.5, reacting for 1-5 hours, and filter pressing to obtain a third leachate and a third leach residue; Wherein, the third leaching residue contains iron and aluminum elements; (4) Selective precipitation of copper: adding acid to the third leachate to adjust the pH value of the third leachate to 1-2, adding iron powder to carry out a reduction reaction for 1-5 hours, and filtering to obtain a fourth leachate and a fourth leach residue; The fourth leachate is returned to the pre-leached residue to prepare pulp according to a mass volume ratio of 1 g: (2.5-5) mL.

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