A method for recovering cobalt from cadmium-poor solution in zinc hydrometallurgy

Abstract

The invention discloses a method for recovering cobalt from cadmium-poor solution in zinc hydrometallurgy, belonging to the technical field of non-ferrous metal metallurgy. The method comprises the following steps: oxidizing and precipitating cobalt and manganese in the cadmium-poor solution with manganate, returning the solution after cobalt precipitation to the zinc system, washing the cobalt-manganese slag with weak acid, and returning the pickling water to the zinc smelting process; mixing the washed cobalt-manganese slag with alkali and performing oxidative roasting, leaching the roasted product with weak alkali to separate cobalt and manganate, returning the solution to oxidize and precipitate cobalt and manganese in the cadmium-poor solution or using it as an oxidant in the iron removal process of zinc smelting, washing the slag with water and returning the alkali washing water to the weak alkali leaching of the roasted product, and the slag is the cobalt slag. The invention solves the problems of high cost of cobalt precipitation with zinc powder, low grade of cobalt slag, difficulty in realizing the value of cobalt; recovering cobalt with organic reagents, introducing organic substances into the zinc smelting system, and long process for continuously preparing cobalt products from the subsequent cobalt slag.

Description

Technical Field

[0001] The present invention belongs to the technical field of chemical engineering, and particularly relates to a method for recovering cobalt from cadmium-poor solution in zinc hydrometallurgy. Background Art

[0002] Cobalt is an important national strategic resource and plays a key role in fields such as aerospace, national defense industry, medical and health, and new energy. With the promotion of the national new energy strategy, the battery industry has witnessed rapid development. As a part of the raw materials for lithium batteries, the demand for cobalt materials has increased rapidly. The cobalt resources in China have low grades and complex occurrence states, and the resource volume is relatively scarce, mainly relying on imports. Therefore, recovering cobalt from cadmium-poor solution in zinc hydrometallurgy can, on the one hand, reduce the cost of cobalt removal, and on the other hand, increase the source of cobalt raw materials, which has high economic value and social benefits for both the zinc and cobalt smelting industries. Therefore, it is very necessary to develop a method to solve the above technical problems. Summary of the Invention

[0003] The technical problem to be solved by the present invention is how to realize the harmless resource utilization of cobalt in cadmium-poor solution at low cost and with less impact on the zinc smelting system. To solve this problem, a method for recovering cobalt from cadmium-poor solution in zinc hydrometallurgy is developed, which solves the problems of high cost of cobalt precipitation with zinc powder, low grade of cobalt slag, difficulty in realizing the value of cobalt; recovering cobalt with organic reagents, introducing organic substances into the zinc smelting system, and the long process for subsequent preparation of cobalt products from cobalt slag.

[0004] The purpose of the present invention is to provide a method for recovering cobalt from cadmium-poor solution in zinc hydrometallurgy.

[0005] The purpose of the present invention is achieved as follows. The method for recovering cobalt from cadmium-poor solution in zinc hydrometallurgy includes steps of oxidation precipitation, oxidative roasting, weak alkaline leaching and post-treatment, specifically including:

[0006] A. Oxidation precipitation: Adding manganate to cadmium-poor solution in zinc hydrometallurgy for oxidation precipitation under weakly acidic conditions to obtain cobalt-manganese slag a and cobalt-precipitated solution b; the cobalt-precipitated solution b is returned to the zinc smelting process;

[0007] B. Oxidative roasting:

[0008] 1) Washing cobalt-manganese slag a with weak acid to obtain washed cobalt-manganese slag c and washing water d; the washing water d is incorporated into the cobalt-precipitated solution b and returned to the zinc smelting process;

[0009] 2) Adding alkali to the washed cobalt-manganese slag c, mixing, and then performing oxidative roasting to obtain roasted product e;

[0010] C. Weak alkaline leaching: Performing weak alkaline leaching on the roasted product to obtain leaching solution f and leaching residue g, and the leaching solution f is returned to the oxidation precipitation step;

[0011] D. Post-treatment: The leaching residue g is washed with water to obtain cobalt residue h and washing water i, and the washing water i is returned to the weak alkaline leaching step.

[0012] The specific operations are as follows:

[0013] (1) Oxidatively precipitate cobalt and manganese in the cadmium-poor solution with manganate;

[0014] (2) Directly return the solution after oxidative precipitation of cobalt and manganese in step (1) to the zinc smelting process;

[0015] (3) Wash the cobalt and manganese slag produced in step (1) with weak acid, and the washing water is incorporated into the solution after cobalt and manganese precipitation and returned to the zinc smelting process;

[0016] (4) Mix the washed cobalt and manganese slag produced in step (3) with alkali and perform oxidative roasting;

[0017] (5) Perform weak alkaline leaching on the roasted product produced in step (4);

[0018] (6) Return the alkaline leaching solution produced in step (5) to step (1) for oxidative precipitation of cobalt and manganese or send it as an oxidant to the iron removal process in zinc smelting;

[0019] (7) Wash the leaching residue produced in step (5) with water, and the washing water is returned to step (5) for weak alkaline leaching of the roasted product. The residue is the cobalt residue.

[0020] In the method for recovering cobalt from the cadmium-poor solution in zinc hydrometallurgy described above, in step (1), when oxidatively precipitating cobalt and manganese in the cadmium-poor solution with manganate, the strong oxidizing property of manganate under weak acidic conditions is used to oxidatively precipitate cobalt and manganese in the solution. The oxidation process controls the temperature at 30 - 90 °C, preferably at 60 - 80 °C; the oxidation time is 1 - 6 h, preferably 2 - 4 h; the pH is controlled at 2.0 - 5.0, preferably at 3.0 - 4.0; the dosage of manganate is 1.0 - 1.8 times the theoretical amount, and the preferred dosage is 1.2 - 1.5 times.

[0021] In the method for recovering cobalt from the cadmium-poor solution in zinc hydrometallurgy described above, in step (4), when mixing the cobalt and manganese slag with alkali and performing oxidative roasting, the alkalis used are NaOH, KOH, Na2CO3, K2CO3, etc., and preferably NaOH because its price is lower than that of KOH and its melting point is lower than those of Na2CO3 and K2CO3, which is beneficial to the oxidation of manganese in the cobalt and manganese slag to manganate; the ratio of slag to alkali is 1:1 - 8, preferably 1:2 - 4; the oxidative roasting temperature is 100 - 600 °C, preferably 200 - 400 °C; the roasting time is 1 - 5 h, preferably 2 - 3 h; the oxidant is air or oxygen.

[0022] In the method for recovering cobalt from the cadmium - poor solution in zinc hydrometallurgy described above, in step (5), the calcination product is subjected to weak - alkaline leaching. The liquid - to - solid ratio of the leaching solution is 3 - 8:1, preferably 3 - 5:1; the temperature is 30 - 80 °C, preferably 30 - 60 °C; and the time is 1 - 4 h, preferably 2 - 4 h.

[0023] In the method for recovering cobalt from the cadmium - poor solution in zinc hydrometallurgy described above, in step (6), the leaching residue is washed with water, and the washing water is a weak - alkaline solution. After controlling or supplementing an appropriate amount of water, it can be returned to step (5) for the weak - alkaline leaching of the calcination product.

[0024] In the method for recovering cobalt from the cadmium - poor solution in zinc hydrometallurgy described above, in step (7), the washed leaching residue is the cobalt residue. By using this method to recover cobalt from the cadmium - poor solution in zinc hydrometallurgy, problems such as high cost of cobalt precipitation with zinc powder, low grade of cobalt residue, recovery of cobalt with organic reagents, introduction of organic substances into the zinc smelting system, and long process flow for subsequent preparation of cobalt products from cobalt residue are solved.

[0025] The technical solution of the present invention is mainly based on the following principle: In the cadmium - poor solution in zinc hydrometallurgy, in addition to cobalt, there are also manganese ions with a much higher concentration than cobalt ions. When using the oxidation method for cobalt precipitation, the consumption of oxidants is large, and the cost saved in cobalt removal and the benefit of cobalt recovery still cannot meet the benefit requirements of cobalt recovery by oxidation. Moreover, the process of separating and recovering cobalt from cobalt - manganese slag is long and the process is complex. Therefore, cobalt - manganese slag is subjected to alkaline calcination to prepare manganate, and the calcination product is leached with weak - alkali to separate cobalt and manganese. Cobalt is enriched in the slag to obtain cobalt concentrate, and manganate ions enter the solution and are returned to oxidize cobalt and manganese; manganate ions can disproportionate into permanganate ions and manganese dioxide under acidic conditions, which have strong oxidizing properties and can oxidize and precipitate cobalt, manganese and other ions in the cadmium - poor solution, realizing the removal of cobalt in the cadmium - poor solution. The solution after cobalt removal is directly returned to the zinc smelting system to recover zinc; the manganese in cobalt - manganese slag mainly exists in the form of manganese dioxide. After adding NaOH and then performing oxidative calcination, it can be converted into sodium manganate: 4NaOH + 2MnO2+O2 = 2Na2MnO4 + 2H2O. Cobalt will not change during this process. When the calcination product is leached with weak - alkali, the manganate and unreacted alkali in the material will dissolve into the liquid phase and be returned to oxidize cobalt and manganese, while cobalt remains in the leaching residue, realizing the recovery of cobalt.

[0026] Compared with the prior art, the advantages of the present invention are as follows:

[0027] (1) Compared with the cobalt precipitation process with zinc powder, the cost is significantly reduced and the valuable recovery of cobalt is realized;

[0028] (2) Compared with the cobalt recovery process with organic reagents, the introduction of organic substances into the zinc smelting system is avoided, and the process of recovering cobalt from cobalt residue is shorter;

[0029] (3) Compared with the oxidation method for cobalt precipitation, the reagent cost is significantly reduced, and the process of recovering cobalt from cobalt residue is shorter. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is the process flow chart of the present invention. Specific embodiments

[0031] The present invention will be further described below in conjunction with embodiments, but the present invention is not limited in any way. Any transformation or substitution based on the teachings of the present invention falls within the protection scope of the present invention.

[0032] The method for recovering cobalt from the cadmium-poor solution in zinc hydrometallurgy according to the present invention includes steps of oxidation precipitation, oxidative roasting, weak alkaline leaching and post-treatment, specifically including:

[0033] A. Oxidation precipitation: Adding manganate to the cadmium-poor solution in zinc hydrometallurgy to carry out oxidation precipitation under weakly acidic conditions to obtain cobalt-manganese slag a and cobalt-depleted solution b; the cobalt-depleted solution b is returned to the zinc smelting process;

[0034] B. Oxidative roasting:

[0035] 1) Washing the cobalt-manganese slag a with weak acid to obtain washed cobalt-manganese slag c and washing water d; the washing water d is incorporated into the cobalt-depleted solution b and returned to the zinc smelting process;

[0036] 2) Adding alkali to the washed cobalt-manganese slag c, mixing and then carrying out oxidative roasting to obtain roasted product e;

[0037] C. Weak alkaline leaching: Carrying out weak alkaline leaching on the roasted product to obtain leaching solution f and leaching residue g, and the leaching solution f is returned to the oxidation precipitation step;

[0038] D. Post-treatment: Washing the leaching residue g to obtain cobalt slag h and washing water i, and the washing water i is returned to the weak alkaline leaching step.

[0039] The temperature of oxidation precipitation in step A is 30 - 90 °C.

[0040] The time of oxidation precipitation in step A is 1 - 6 h.

[0041] The pH value of oxidation precipitation in step A is controlled at 2.0 - 5.0.

[0042] The alkali described in step B 2) is sodium hydroxide, potassium hydroxide, sodium carbonate or potassium carbonate.

[0043] The alkali is sodium hydroxide.

[0044] The addition amount of the alkali is 1 - 8 times the mass of the washed cobalt-manganese slag c.

[0045] The oxidant for oxidative roasting described in step B 2) is air or oxygen.

[0046] In step B (2), the temperature of the oxidative roasting is 100~600°C, and the time of the oxidative roasting is 1~5h.

[0047] In step C, the pH value of the weak alkaline leaching is controlled at 8~10.

[0048] The following further illustrates the present invention with specific implementation cases:

[0049] Example 1

[0050] The components of the cadmium-poor solution in this example are shown in Table 1:

[0051] Table 1 Components of the cadmium-poor solution

[0052]

[0053] Take 3000 mL of the cadmium-poor solution, the reaction temperature is 80°C, the dosage of manganate is 1.2 times the theoretical amount, the dosage of the acidic solution is 520.2 mL, the reaction time is 2 h, the pH is controlled at 4.0. After oxidative precipitation, cobalt-manganese slag and cobalt-deposited solution after oxidation are obtained; the components of the cobalt-manganese slag are shown in Table 2, and the components of the cobalt-deposited solution after oxidation are shown in Table 3:

[0054] Table 2 Components of the cobalt-manganese slag

[0055]

[0056] Table 3 Solution of cobalt deposition by manganate oxidation

[0057]

[0058] Take 105.78 g of wet cobalt-manganese slag (equivalent to 50 g of dry slag), add 100 g of NaOH, mix well and put it into an atmosphere furnace for oxidative roasting at a temperature of 300°C, introduce oxygen, and the roasting time is 2 h; use 5 g / L NaOH solution at a liquid-solid ratio of 3:1, leach at a temperature of 50°C for 3 h, the leachate is 400 mL (435 mL considering the water content in the slag), and the alkali washing water is 300 mL. The components of the washed slag are shown in Table 4:

[0059] Table 4 Components of the cobalt slag

[0060] .

Claims

1. A method for recovering cobalt from cadmium-poor solution in zinc hydrometallurgy, characterized in that, The method for recovering cobalt from cadmium - poor solution in zinc hydrometallurgy includes oxidation precipitation, oxidative roasting, weak - alkaline leaching and post - treatment steps, specifically including: A. Oxidation precipitation: Adding manganate to the cadmium - poor solution in zinc hydrometallurgy for oxidation precipitation under weak - acidic conditions to obtain cobalt - manganese slag a and cobalt - precipitated solution b; the cobalt - precipitated solution b is returned to the zinc smelting process; B. Oxidative roasting: 1) Washing the cobalt - manganese slag a with weak acid to obtain washed cobalt - manganese slag c and washing water d; the washing water d is incorporated into the cobalt - precipitated solution b and returned to the zinc smelting process; 2) Adding alkali to the washed cobalt - manganese slag c and then carrying out oxidative roasting. The oxidant for oxidative roasting is air or oxygen, the temperature of oxidative roasting is 100 - 600 °C, and the time of oxidative roasting is 1 - 5 h to obtain roasted product e; C. Weak - alkaline leaching: Carrying out weak - alkaline leaching on the roasted product, controlling the pH value of leaching at 8 - 10 to obtain leaching solution f and leaching residue g, and the leaching solution f is returned to the oxidation precipitation step; D. Post - treatment: After washing the leaching residue g with water, cobalt slag h and washing water i are obtained, and the washing water i is returned to the weak - alkaline leaching step.

2. The method for recovering cobalt from cadmium-poor solution in zinc hydrometallurgy according to claim 1, characterized in that, In step A, the temperature of oxidation precipitation is 30 - 90 °C.

3. The method for recovering cobalt from cadmium-poor solution in zinc hydrometallurgy according to claim 1, characterized in that, In step A, the time of oxidation precipitation is 1 - 6 h.

4. The method for recovering cobalt from cadmium-poor solution in zinc hydrometallurgy according to claim 1, characterized in that, In step A, the pH value of oxidation precipitation is controlled at 2.0 - 5.

0.

5. The method for recovering cobalt from cadmium-poor solution in zinc hydrometallurgy according to claim 1, characterized in that, In step B2), the alkali is sodium hydroxide, potassium hydroxide, sodium carbonate or potassium carbonate.

6. The method for recovering cobalt from cadmium-poor solution in zinc hydrometallurgy according to claim 1 or 5, characterized in that, The alkali is sodium hydroxide.

7. The method for recovering cobalt from cadmium-poor solution in zinc hydrometallurgy according to claim 1 or 5, characterized in that, The addition amount of the alkali is 1 - 8 times the mass of the washed cobalt - manganese slag c.

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