Method for electrolytic recovery of manganese using post-second-stage nickel-cobalt precipitation liquid in laterite-nickel ore hydrometallurgy

Abstract

A method for electrolytic recovery of manganese using a post-second-stage nickel-cobalt precipitation liquid in laterite-nickel ore hydrometallurgy, comprising the following steps: using an alkaline neutralizer to adjust the pH value of a post-second-stage nickel-cobalt precipitation liquid in laterite-nickel ore hydrometallurgy to 7.8-8.2, then introducing air or oxygen for oxidation, and performing solid-liquid separation to obtain a manganese residue and a filtrate; using sulfuric acid to perform acid leaching on the manganese residue, and performing solid-liquid separation to obtain a manganese-containing leachate and a filter residue; using the alkaline neutralizer to adjust the pH value of the manganese-containing leachate to 6.0-6.5, carrying out primary impurity removal, and performing solid-liquid separation to obtain an iron-aluminum residue and a post-primary impurity removal liquid; adding a soluble sulfide into the post-primary impurity removal liquid, carrying out secondary impurity removal, and performing solid-liquid separation to obtain a nickel-cobalt-containing residue and a manganese-containing purified liquid; and electrolyzing the manganese-containing purified liquid so as to obtain manganese simple substance and a post-electrolysis liquid. The method recovers manganese from an originally waste post-second-stage nickel-cobalt precipitation liquid, thus achieving high economic value and benefits while reducing resource waste and environmental pollution.

Description

Method for recovering manganese by electrolysis of liquid after two-stage nickel and cobalt precipitation in laterite nickel ore hydrometallurgy Technical Field

[0001] The present invention belongs to the technical field of metal recovery, and in particular relates to a method for recovering manganese by electrolyzing the liquid after two-stage nickel and cobalt precipitation in laterite nickel ore hydrometallurgy. Background Art

[0002] The high-pressure acid leaching process for laterite nickel ore is becoming increasingly popular, and the nickel intermediates produced are expected to become a major source for the production of battery-grade nickel sulfate. Typically, low-grade laterite nickel ore containing less than 1.3% nickel contains a nickel-cobalt-manganese ratio of 10:(0.6-1.5):(1.0-9.0). However, existing smelting technologies focus solely on nickel extraction or nickel-cobalt extraction, without considering the simultaneous extraction of nickel, cobalt, and manganese, resulting in a significant waste of resources.

[0003] For example, patent CN108913883A discloses a method for producing nickel cobalt hydroxide by wet smelting of laterite nickel ore, comprising the following steps: S1 pressure leaching or atmospheric leaching of laterite nickel ore to obtain a leached slurry; S2 pre-neutralizing the leached slurry to control the endpoint pH value to 1.1-1.8; S3 removing iron and aluminum from the pre-neutralized slurry to control the endpoint pH value to 3.5-4.2, and introducing compressed air during the process; S4 CCD washing the slurry after iron and aluminum removal; S5 deep impurity removal of the overflow after the CCD washing to control the endpoint pH value to 4.8-5.2, and introducing compressed air during the process; and S6 precipitating the overflow after deep impurity removal with lime milk to obtain a gypsum-nickel cobalt hydroxide mixture, separating the gypsum-nickel cobalt hydroxide mixture, and obtaining a nickel cobalt hydroxide product.

[0004] The above technology only focuses on the extraction of nickel and part of cobalt, and lacks a means to recover manganese in the liquid after the second stage of nickel and cobalt precipitation, which is a waste of current laterite nickel ore resources.

[0005] Summary of the Invention

[0006] In response to the current problem of resource waste in the hydrometallurgical process of laterite nickel ore, the purpose of the present invention is to provide a method for recovering manganese by electrolyzing the liquid after the second stage of nickel and cobalt precipitation in the hydrometallurgical process of laterite nickel ore, so as to maximize the recovery and utilization of valuable metals in the laterite nickel ore while reducing resource waste and environmental pollution.

[0007] To achieve the above object, the present invention is implemented through the following technical solutions:

[0008] A method for recovering manganese by electrolyzing the liquid after the second stage nickel and cobalt precipitation in laterite nickel ore hydrometallurgy, comprising the following steps:

[0009] (1) using an alkaline neutralizer to adjust the pH of the solution after the second stage nickel and cobalt precipitation of laterite nickel ore hydrometallurgy to 7.8-8.2, then introducing air or oxygen for oxidation, and obtaining manganese slag and filtrate after solid-liquid separation;

[0010] (2) acid leaching the manganese slag with sulfuric acid, and obtaining a manganese-containing leachate and a filter residue after solid-liquid separation;

[0011] (3) using an alkaline neutralizer to adjust the pH of the manganese-containing leachate to 6.0-6.5, performing a primary impurity removal, and obtaining iron-aluminum slag and a primary impurity-removed liquid after solid-liquid separation;

[0012] (4) adding soluble sulfide to the liquid after the primary impurity removal to perform secondary impurity removal, and obtaining nickel-cobalt slag and manganese-containing purified liquid after solid-liquid separation;

[0013] (5) electrolyzing the manganese-containing purified liquid to obtain manganese element and electrolyzed liquid.

[0014] Preferably, the alkaline neutralizing agent in step (1) is lime milk or sodium hydroxide.

[0015] Preferably, step (2) further comprises adding a reducing agent to the manganese slag so that the redox potential during the leaching process is lower than 0.7V.

[0016] Preferably, the reducing agent is hydrogen peroxide.

[0017] Preferably, the alkaline neutralizing agent in step (3) is aqueous ammonia.

[0018] Preferably, the soluble sulfide in step (4) is sodium dimethyldithiocarbamate or sodium sulfide.

[0019] Preferably, the amount of the soluble sulfide added is 1.2 to 1.8 times the stoichiometric amount required for precipitating nickel and cobalt in the liquid after the primary impurity removal.

[0020] Preferably, the average current density of the electrolysis in step (5) is 200 to 500 A / m 2 , the electrolysis time is 12 to 24 hours.

[0021] Preferably, in the electrolysis of step (5), the anode used is a titanium plate and the cathode is an aluminum plate.

[0022] Preferably, the above method further comprises recycling the post-electrolysis solution obtained in step (5) to acid-leach the manganese slag in step (2).

[0023] The beneficial effects of the present invention are:

[0024] The present invention utilizes electrolytic manganese to recycle the waste secondary nickel-cobalt precipitation solution from laterite nickel ore hydrometallurgy, demonstrating excellent economic value. For a long time, the raw materials for electrolytic manganese have come from rhodochrosite (mainly manganese carbonate) and pyrolusite (mainly manganese dioxide), with the electrolytic cost of each ton of manganese metal being between 3,000 and 4,000 yuan. The present invention proposes recycling the waste secondary nickel-cobalt precipitation solution using a relatively inexpensive alkaline neutralizer, such as lime milk, and air oxidation to precipitate manganese. This method demonstrates excellent economic value, maximizing the recovery of valuable metals from laterite nickel ore while reducing resource waste and environmental pollution.

[0025] The present invention also recycles the nickel-cobalt slag obtained after the secondary impurity removal, and reuses the post-electrolysis liquid generated by electrolysis in the leaching process of the manganese slag, thereby further reducing resource waste and environmental pollution. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings of the embodiments are briefly introduced below.

[0027] FIG1 is a flow chart of a method for recovering manganese by electrolysis of a solution after two-stage nickel and cobalt precipitation by hydrometallurgy of laterite nickel ore according to the present invention. DETAILED DESCRIPTION

[0028] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0029] Referring to FIG1 , the present invention provides a method for recovering manganese by electrolyzing the liquid after the second stage nickel and cobalt precipitation of laterite nickel ore hydrometallurgy, comprising the following steps:

[0030] (1) The pH of the solution after the second stage nickel and cobalt precipitation of laterite nickel ore hydrometallurgy is adjusted to 7.8-8.2 using lime milk or sodium hydroxide, and then air or oxygen is introduced for oxidation. After solid-liquid separation, manganese slag and filtrate are obtained; the main components of the manganese slag are manganese oxide and calcium sulfate, and the main component of the filtrate is magnesium sulfate.

[0031] (2) The manganese slag is acid-leached with sulfuric acid, and a reducing agent, hydrogen peroxide, is added to make the redox potential during the leaching process lower than 0.7 V, thereby promoting the dissolution of manganese. After solid-liquid separation, a manganese-containing leachate and a filter residue are obtained, wherein the main component of the filter residue is calcium sulfate.

[0032] (3) adjusting the pH of the manganese-containing leachate to 6.0-6.5 with aqueous ammonia, performing a primary impurity removal, and obtaining iron-aluminum slag and a primary impurity-removed liquid after solid-liquid separation;

[0033] (4) adding a soluble sulfide, sodium dimethyldithiocarbamate or sodium sulfide, to the liquid after the primary impurity removal, wherein the amount of the soluble sulfide added is 1.2 to 1.8 times the stoichiometric amount required for precipitating nickel and cobalt in the liquid after the primary impurity removal, and performing secondary impurity removal, and obtaining recyclable nickel-cobalt slag and manganese-containing purified liquid after solid-liquid separation;

[0034] (5) electrolyzing the manganese-containing purified liquid to obtain manganese element and electrolyzed liquid, and returning the electrolyzed liquid to the manganese slag acid leaching process in step (2) for cyclic leaching. The average current density of the electrolysis is 200-500A / m 2 The electrolysis time is 12 to 24 hours; the anode used is a titanium plate and the cathode is an aluminum plate.

[0035] To make the objectives, technical solutions and advantages of the present invention more clear, the embodiments of the present invention will be described in further detail below.

[0036] The components of the liquid after the second stage nickel and cobalt precipitation of laterite nickel ore hydrometallurgy used in the following examples are shown in Table 1:

[0037] Table 1 Composition of the liquid after the second stage nickel and cobalt precipitation of laterite nickel ore hydrometallurgy

[0038] Example 1

[0039] S1: The liquid after the second stage of nickel and cobalt precipitation in laterite nickel ore hydrometallurgy is first adjusted to pH 7.8 by lime milk, and compressed air is added at the same time to maintain an alkaline environment to allow Mn 2+ It is oxidized into manganese oxide precipitate, and after filtration, a filter residue and a filtrate with manganese oxide and calcium sulfate as the main components are obtained. The filtrate is tested to contain 40 mg / L of manganese; the filter residue contains 17.5% manganese, 16.5% calcium, and a small amount of nickel, cobalt, iron and aluminum;

[0040] S2: Add sulfuric acid and hydrogen peroxide to the manganese slag so that the redox potential during the leaching process is lower than 0.7V. The potential is measured as the redox potential of the solution relative to a saturated calomel electrode and is achieved by controlling the amount of hydrogen peroxide added. The manganese slag is leached with sulfuric acid and a reducing agent, hydrogen peroxide, and filtered to obtain a manganese-containing leachate and calcium sulfate slag. According to the test, the manganese-containing leachate contains 50g / L manganese, about 0.6g / L calcium, 0.45g / L nickel, 0.42g / L cobalt, 0.06g / L iron, and 0.18g / L aluminum.

[0041] S3: adding ammonia water to the manganese-containing leachate to adjust the pH to 6.0, and performing the first neutralization and impurity removal to remove impurities such as iron and aluminum. After testing, the iron content in the liquid after the first impurity removal was 0.2 mg / L and the aluminum content was 0.4 mg / L;

[0042] S4: Add sodium fumarate to the liquid after the first impurity removal, with the added amount being 1.2 times the stoichiometric amount required to precipitate nickel and cobalt in the liquid after the first impurity removal, and perform a second impurity removal, filtering to remove metallic impurities such as nickel and cobalt. Testing of the liquid after the second impurity removal revealed a nickel content of 0.6 mg / L and a cobalt content of 0.8 mg / L, resulting in a qualified electrolytic solution and recyclable nickel and cobalt slags.

[0043] S5: Use titanium plate as anode and aluminum plate as cathode to electrolyze the qualified solution. The current density of electrolysis is 350A / m 2 , electrolyze for 24 hours to obtain a manganese element product and a post-electrolysis liquid. After testing, the purity of the manganese element is 99.78%, the post-electrolysis liquid contains 20g / L manganese and 45g / L residual acid. The post-electrolysis liquid is used for cyclic leaching in the manganese slag leaching process of step S2.

[0044] Example 2

[0045] S1: The liquid after the second stage of nickel and cobalt precipitation in laterite nickel ore hydrometallurgy is first adjusted to pH 8.2 by lime milk, and compressed air is added at the same time to maintain an alkaline environment to allow Mn 2+ It is oxidized into manganese oxide precipitate, and after filtration, a filter residue with manganese oxide and calcium sulfate as the main components and a filtrate are obtained. The manganese content of the filtrate is 30 mg / L after testing; the filter residue contains 18.5% manganese, 17.8% calcium, and small amounts of nickel, cobalt, iron and aluminum;

[0046] S2: Add sulfuric acid and hydrogen peroxide to the manganese slag so that the redox potential during the leaching process is lower than 0.7V. The potential is measured as the redox potential of the solution relative to a saturated calomel electrode and is achieved by controlling the amount of hydrogen peroxide added. The manganese slag is leached with sulfuric acid and a reducing agent, hydrogen peroxide, and filtered to obtain a manganese-containing leachate and calcium sulfate slag. According to the test, the manganese-containing leachate contains 55g / L manganese, about 0.6g / L calcium, 0.46g / L nickel, 0.41g / L cobalt, 0.07g / L iron, and 0.17g / L aluminum.

[0047] S3: Add ammonia water to the manganese-containing leachate to adjust the pH to 6.3, and perform the first neutralization and impurity removal to remove impurities such as iron and aluminum. After testing, the iron content in the liquid after the first impurity removal is 0.2 mg / L and the aluminum content is 0.3 mg / L;

[0048] S4: Add sodium fumarate to the liquid after the first impurity removal, with the amount added being 1.8 times the stoichiometric amount required to precipitate nickel and cobalt in the liquid after the first impurity removal, and perform a second impurity removal. Filter and remove metallic impurities such as nickel and cobalt. Testing of the second impurity removal liquid revealed a nickel content of 0.52 mg / L and a cobalt content of 0.63 mg / L, yielding a qualified electrolytic solution and recyclable nickel and cobalt slag.

[0049] S5: Use titanium plate as anode and aluminum plate as cathode to electrolyze the qualified solution. The current density of electrolysis is 400A / m 2 , electrolysis for 12 hours to obtain electrolytic manganese element product and post-electrolysis liquid. After testing, the purity of manganese element is 99.75%, the post-electrolysis liquid contains 15g / L manganese and 48g / L residual acid. The post-electrolysis liquid is used for cyclic leaching in the manganese slag leaching process of step S2.

[0050] Example 3

[0051] S1: The liquid after the second stage of nickel and cobalt precipitation in laterite nickel ore hydrometallurgy is first adjusted to pH 8.0 by lime milk, and compressed air is added at the same time to maintain an alkaline environment to allow Mn 2+ It is oxidized into manganese oxide precipitate, and after filtration, a filter residue with manganese oxide and calcium sulfate as the main components and a filtrate are obtained. The manganese content of the filtrate is 26 mg / L after testing; the filter residue contains 18.1% manganese, 17.3% calcium, and small amounts of nickel, cobalt, iron and aluminum;

[0052] S2: Add sulfuric acid and hydrogen peroxide to the manganese slag so that the redox potential during the leaching process is lower than 0.7V. The potential is measured as the redox potential of the solution relative to a saturated calomel electrode and is achieved by controlling the amount of hydrogen peroxide added. The manganese slag is leached with sulfuric acid and a reducing agent, hydrogen peroxide, and filtered to obtain a manganese-containing leachate and calcium sulfate slag. According to the test, the manganese-containing leachate contains 52g / L manganese, about 0.6g / L calcium, 0.44g / L nickel, 0.42g / L cobalt, 0.05g / L iron, and 0.16g / L aluminum.

[0053] S3: adding ammonia water to the manganese-containing leachate to adjust the pH to 6.5, and performing the first neutralization and impurity removal to remove impurities such as iron and aluminum. After testing, the iron content in the liquid after the first impurity removal was 0.35 mg / L and the aluminum content was 0.54 mg / L;

[0054] S4: Add sodium sulfide to the liquid after the first impurity removal, with the amount added being 1.5 times the stoichiometric amount required to precipitate nickel and cobalt in the liquid after the first impurity removal, and perform a second impurity removal. Filter and remove metallic impurities such as nickel and cobalt. Testing shows that the nickel content of the liquid after the second impurity removal is 0.4 mg / L and the cobalt content is 0.35 mg / L, resulting in a qualified electrolytic solution and recyclable nickel and cobalt slag.

[0055] S5: Using titanium plate as anode and aluminum plate as cathode, the qualified solution is electrolyzed at a current density of 380A / m 2 , electrolysis for 20 hours to obtain an electrolytic manganese element product and a post-electrolysis liquid. After testing, the purity of the manganese element is 99.76%, the post-electrolysis liquid contains 13g / L manganese and 50g / L residual acid. The post-electrolysis liquid is used for cyclic leaching in the manganese slag leaching process of step S2.

[0056] It should be noted that the above embodiments all belong to the same inventive concept, and the description of each embodiment has its own focus. For any details not described in individual embodiments, reference may be made to the description in other embodiments.

[0057] The above-described embodiments merely illustrate the implementation methods of the present invention. While the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the patent. It should be noted that a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the patent for this invention shall be determined by the appended claims.

Claims

1. A method for recovering manganese by electrolysis of the liquid after the second stage of nickel and cobalt precipitation by hydrometallurgical process of laterite nickel ore, It is characterized in that The following steps are involved: (1) using an alkaline neutralizer to adjust the pH of the solution after the second stage nickel and cobalt precipitation of laterite nickel ore hydrometallurgical process to 7.8-8.2, then introducing air or oxygen for oxidation, and obtaining manganese slag and filtrate after solid-liquid separation; (2) acid leaching the manganese slag with sulfuric acid to obtain a manganese-containing leaching solution and a filter residue after solid-liquid separation; (3) adjusting the pH of the manganese-containing leaching solution to 6.0-6.5 by using an alkaline neutralizer, performing a primary impurity removal, and obtaining iron-aluminum slag and a primary impurity-removed liquid after solid-liquid separation; (4) adding soluble sulfide to the liquid after the primary impurity removal to perform secondary impurity removal, and obtaining nickel-cobalt slag and manganese-containing purified liquid after solid-liquid separation; (5) electrolyzing the manganese-containing purified liquid to obtain manganese element and a post-electrolysis liquid.

2. The method for recovering manganese by electrolysis of the liquid after the second stage nickel and cobalt precipitation by hydrometallurgical process of laterite nickel ore according to claim 1, It is characterized in that The alkaline neutralizing agent in step (1) is lime milk or sodium hydroxide.

3. The method for recovering manganese by electrolysis of the liquid after the second stage nickel and cobalt precipitation by hydrometallurgical process of laterite nickel ore according to claim 1, It is characterized in that Step (2) also includes adding a reducing agent to the manganese slag so that the redox potential during the leaching process is lower than 0.7V.

4. The method for recovering manganese by electrolysis of the liquid after the second stage nickel and cobalt precipitation by hydrometallurgical process of laterite nickel ore according to claim 3, It is characterized in that The reducing agent is hydrogen peroxide.

5. The method for recovering manganese by electrolysis of the liquid after the second stage nickel and cobalt precipitation by hydrometallurgical process of laterite nickel ore according to claim 1, It is characterized in that The alkaline neutralizing agent in step (3) is aqueous ammonia.

6. The method for recovering manganese by electrolysis of the liquid after the second stage nickel and cobalt precipitation by hydrometallurgical process of laterite nickel ore according to claim 1, It is characterized in that The soluble sulfide in step (4) is sodium dimethyldithiocarbamate or sodium sulfide.

7. The method for recovering manganese by electrolysis of the liquid after two-stage nickel and cobalt precipitation by hydrometallurgical process of laterite nickel ore according to claim 1, It is characterized in that The amount of the soluble sulfide added is 1.2 to 1.8 times the stoichiometric amount required for precipitating nickel and cobalt in the liquid after the first impurity removal.

8. The method for recovering manganese by electrolysis of the liquid after two-stage nickel and cobalt precipitation by hydrometallurgical process of laterite nickel ore according to claim 1, It is characterized in that The average current density of the electrolysis in step (5) is 200 to 500 A / m 2 The electrolysis time is 12 to 24 hours.

9. The method for recovering manganese by electrolysis of the liquid after two-stage nickel and cobalt precipitation by hydrometallurgical process of laterite nickel ore according to claim 1, It is characterized in that In the electrolysis of step (5), the anode used is a titanium plate and the cathode is an aluminum plate.

10. The method for recovering manganese by electrolysis of the liquid after two-stage nickel and cobalt precipitation by hydrometallurgical process of laterite nickel ore according to claim 1, It is characterized in that The method also includes recycling the post-electrolysis liquid obtained in step (5) to acid-leach the manganese slag in step (2).

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