Process for preparing cobalt carbonate from high-cobalt slag

Abstract

In the first step, the leaching rates of zinc and cobalt in the high-cobalt slag are both higher than 99.0%, the cobalt concentration in leachate is 10-12 g / L, the Co / Mn ratio of the solution is higher than 10000, and the metal recovery rate is high; in the step 2, the removal rate of iron reaches 99%, the residual quantity of iron reaches 0.1 mg / L, the loss rate of zinc reaches 3.6%, the loss rate of cobalt reaches 2.5%, the removal rate of iron is increased, the loss of cobalt ions is small, the impurity removal efficiency is high, and the loss is small; the primary separation rate of zinc in the primary zinc removal process in the step 3 reaches 88%, the zinc residual quantity reaches 26 mg / L after secondary zinc removal in the step 4, and the purity of the cobalt carbonate product obtained through the method is larger than 98%.

Description

Technical Field

[0001] The invention belongs to the field of resource recycling, and in particular relates to a process for preparing cobalt carbonate from high-cobalt slag. Background Art

[0002] With the rapid development of new energy vehicles, aerospace and other industries, the demand for metals such as cobalt is increasing. As one of the important sources of cobalt, the recycling and reuse of high-cobalt slag is of great significance to meeting market demand and ensuring the stability of the industrial chain. In order to promote the development of the circular economy and the conservation and utilization of resources, the state has introduced a series of relevant policies to support the recycling and reuse of renewable resources. These policies provide a good policy environment and market opportunities for the recycling and reuse of high-cobalt slag.

[0003] High-cobalt slag is a cobalt-containing material produced in processes such as hydrometallurgy, which contains a considerable amount of valuable metals, such as cobalt, zinc, and manganese. These metals have a wide range of application values ​​in industrial production. Therefore, recycling and reusing high-cobalt slag can achieve the recovery and reuse of these valuable metals and improve resource utilization efficiency. High-cobalt slag has a complex composition. If it is not handled properly, it is easy to cause heavy metal pollution to the soil and water, causing serious impacts on the environment. With the continuous strengthening of environmental protection policies and the improvement of public environmental awareness, the recycling and reuse of high-cobalt slag has become an important way to alleviate environmental pressure and achieve sustainable development. At present, the process flow and process conditions for producing cobalt carbonate using cobalt-containing materials still have room for improvement in the purity of cobalt carbonate.

[0004] The low purity of the existing process is mainly reflected in: ① Control of reaction conditions: During the preparation process, the control of reaction temperature, pressure, time and other conditions has an important influence on the purity of cobalt carbonate. If the conditions are not properly controlled, it may lead to incomplete reaction or the generation of by-products, thereby reducing the purity of cobalt carbonate. ② Precipitation process: During the precipitation process of cobalt carbonate, if the amount of sodium carbonate added, the addition rate or the pH value of the reaction system is not properly controlled, it may lead to uneven distribution of the crystal form and particle size of cobalt carbonate, and even the generation of other forms of cobalt compounds (such as cobalt hydroxide), thereby affecting the purity of cobalt carbonate. ③ Washing and drying: After the precipitation is generated, the washing and drying process is also a key link affecting the purity of cobalt carbonate. If the washing is not sufficient, some impurities may remain; and improper drying conditions may cause cobalt carbonate to decompose or react with other substances, reducing the purity.

[0005] Table 1 Chemical composition of high cobalt materials

[0006]

[0007] After analysis, the phase composition of the raw material high cobalt slag is as shown in Table 2:

[0008] Table 2 High cobalt slag phase composition table

[0009]

[0010] Summary of the invention

[0011] (1) The object of the present invention is to provide a process for preparing cobalt carbonate from high-cobalt slag which can improve the purity of the product.

[0012] (2) The technical solution adopted by the present invention is as follows: A process for preparing cobalt carbonate from high-cobalt slag comprises the following steps:

[0013] Step 1: zinc-cobalt leaching solution: controlled potential leaching, taking 100g of high-cobalt slag, using 15% sulfuric acid solution as leaching solution, using leaching solution-solid ratio of 4:1, leaching temperature of 85°C, reaction time of 2.0h, using ammonium persulfate as oxidant, keeping the solution potential at about 1.20V during the leaching process, filtering to obtain zinc-cobalt leaching solution A, the zinc and cobalt leaching rates in the high-cobalt slag are both higher than 99.0%; the cobalt concentration in the leaching solution is 10-12g / L, the solution Co / Mn ratio is higher than 10000, and the purpose of selective leaching can be achieved; starting the timing after the potential is stable, and taking samples and analyzing the solution and solid components at regular intervals;

[0014] Step 2: Neutralization and impurity removal: In zinc-cobalt leaching solution A, sodium carbonate is added to adjust the pH value, and hydrogen peroxide is added to heat and ventilate to remove iron. After a period of reaction, the steam is turned off, and zinc powder is added to remove copper and cadmium when the temperature drops to 50-55°C. After a period of reaction, the filtrate and the filter residue are analyzed. The initial pH value of the iron removal process is 2.0, the end pH value is 4.0, the temperature is 95°C, and the reaction time is 120min. In this way, the iron removal rate reaches 99%, the residual iron reaches 0.1mg / L, the zinc loss rate is 3.6%, and the cobalt loss rate is 2.5%, which is conducive to improving the iron removal rate, and the loss of cobalt ions is not large; in the process of zinc powder replacement for copper and cadmium removal, the amount of zinc powder added is 4.5g / L, the temperature is between 50-55°C, the reaction is 30min, and then the impurity removal liquid B is obtained by filtration, which can achieve a better effect of replacement for copper and cadmium removal;

[0015] Step 3: In the primary zinc removal process, NaOH is added to a beaker, and then the impurity removal liquid B is added. After heating and reacting for a period of time, the filter is filtered. The filter residue is crude cobalt. The filtrate is oxidized and filtered with hydrogen peroxide. Under the conditions of NaOH concentration of 5 mol / L, reaction temperature of 85°C, reaction time of 2 h, and liquid-solid ratio of 5:1, the primary separation rate of zinc reaches 88%;

[0016] Step 4: Secondary zinc removal process, add water to the crude cobalt, then slowly add sulfuric acid to stir the reaction, control the initial pH at 3.0-4.0, reaction temperature 60°C, then slowly add zinc removal reagent B, react for a period of time and filter, when the dosage of zinc removal reagent B is 9.0g / L, the zinc residue reaches 26mg / L;

[0017] Step 5: Cobalt precipitation: After zinc removal, sodium carbonate solution is added to the liquid, and the temperature and pH are controlled. The product is cobalt carbonate. The reaction temperature of the sodium carbonate precipitation process of cobalt carbonate is 85°C and the pH value is 8.0. The cobalt carbonate product meets the requirements and the product purity is greater than 98%.

[0018] (3) Due to the adoption of the above technical solution, the beneficial effects of the present invention are:

[0019] (1) In step 1, the leaching rates of zinc and cobalt in the high-cobalt slag are both higher than 99.0%, the cobalt concentration in the leaching solution is 10-12 g / L, the Co / Mn ratio of the solution is higher than 10000, and the metal recovery rate is high; in step 2, the iron removal rate reaches 99%, the residual iron reaches 0.1 mg / L, the zinc loss rate is 3.6%, and the cobalt loss rate is 2.5%, which is beneficial to improving the iron removal rate, the loss of cobalt ions is not large, the impurity removal efficiency is high, and the loss is small; in step 3, the primary separation rate of zinc in the primary zinc removal process reaches 88%, and after the secondary zinc removal in step 4, the residual zinc reaches 26 mg / L. The purity of the cobalt carbonate product obtained by the method of the present invention is greater than 98%.

[0020] (2) Feasibility

[0021] The process is simple and easy to industrialize. It can be combined with existing equipment and production processes to the maximum extent. It does not emit any wastewater or waste gas, and can comprehensively recover valuable metals such as zinc and cobalt, thereby achieving efficient recycling of high-cobalt slag.

[0022] (3) Products

[0023] The product produced by the process is cobalt carbonate with a high purity, which can reach more than 98%. The production process is easy to control and the product quality is stable.

[0024] (4) Production costs

[0025] The process is simple, easy to operate, consumes less reagents and has low production cost.

[0026] (5) By controlling the reaction conditions, including the control of reaction temperature, time and other conditions during the preparation process, and the control of the amount of sodium carbonate added and the pH value of the reaction system during the precipitation of cobalt carbonate, incomplete reaction or the generation of by-products, uneven distribution of the crystal form and particle size of cobalt carbonate, and even the generation of other forms of cobalt compounds (such as cobalt hydroxide) can be avoided. When the above conditions are met, the purity of cobalt carbonate can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a process flow chart of the present invention. DETAILED DESCRIPTION

[0028] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments.

[0029] like Figure 1 shown.

[0030] Embodiment 1:

[0031] Step 1: zinc-cobalt leaching solution: 100 g of high-cobalt slag is taken, 15% sulfuric acid solution is used as leaching solution, the leaching liquid-to-solid ratio is 4:1, the leaching temperature is 85° C., and the reaction time is 2.0 h; ammonium persulfate is used as an oxidant, the solution potential is maintained at about 1.20 V during the leaching process, and the zinc-cobalt leaching solution A is obtained by filtering;

[0032] Step 2: Neutralization and impurity removal: In zinc-cobalt leaching solution A, sodium carbonate is added to adjust the pH value. The initial pH value of the iron removal process is 2.0, the end point pH value is 4.0, the temperature is 95°C, the reaction time is 120min, and the air is ventilated and hydrogen peroxide is added to oxidize and remove iron; after a period of reaction, the steam is turned off, and when the temperature drops to 50°C, 4.5g / L of zinc powder is added, and the reaction is carried out for 30min, and then filtered to obtain impurity removal solution B;

[0033] Step 3: Remove zinc once: add caustic soda to a concentration of 5 mol / L in a beaker, then add the impurity removal solution B, reaction temperature 85°C, liquid-to-solid ratio 5:1, reaction time 2h, then filter, the filter residue is crude cobalt. Add hydrogen peroxide to the filtrate for oxidation and filtration;

[0034] Step 4: Secondary zinc removal: During the secondary zinc removal process, water is added to the crude cobalt, the initial pH is controlled at about 3.0, the temperature is controlled at 60°C, and then zinc removal reagent B (9.0 g / L) is slowly added. After a period of reaction, the mixture is filtered, and the filtrate and residue are analyzed;

[0035] Step 5 Cobalt carbonate product: Add sodium carbonate solution to the zinc removal solution, control the temperature at 85°C, control the pH at about 8.0, and filter. The product is cobalt carbonate. Then add water to the cobalt carbonate, heat and wash it, and filter it. The purity of the cobalt carbonate product is greater than 98%.

[0036] Example 2

[0037] Step 1: zinc-cobalt leaching solution: take 100g of high-cobalt slag, use 20% sulfuric acid solution as leaching solution, adopt leaching solution-solid ratio of 4:1, leaching temperature of 80°C, reaction time of 1.5h; use ammonium persulfate as oxidant, keep the solution potential at about 1.20V during the leaching process, and filter to obtain zinc-cobalt leaching solution A;

[0038] Step 2: Neutralization and impurity removal: In zinc-cobalt leaching solution A, sodium carbonate is added to adjust the pH value. The initial pH value of the iron removal process is 2.0, the end point pH value is 4.0, the temperature is 95°C, the reaction time is 120min, and the air is ventilated and hydrogen peroxide is added to oxidize and remove iron; after a period of reaction, the steam is turned off, and when the temperature drops to 55°C, 4.5g / L of zinc powder is added, and the reaction is carried out for 30min, and then filtered to obtain impurity removal solution B;

[0039] Step 3: Remove zinc once: add caustic soda to a concentration of 5 mol / L in a beaker, then add the impurity removal solution B, reaction temperature 85°C, liquid-to-solid ratio 5:1, reaction time 2h, then filter, the filter residue is crude cobalt. Add hydrogen peroxide to the filtrate for oxidation and filtration;

[0040] Step 4: Secondary zinc removal: During the secondary zinc removal process, water is added to the crude cobalt, the initial pH is controlled at about 4.0, the temperature is controlled at 60°C, and then zinc removal reagent B (9.0 g / L) is slowly added. After a period of reaction, the mixture is filtered, and the filtrate and residue are analyzed;

[0041] Step 5 Cobalt carbonate product: Add sodium carbonate solution to the zinc removal solution, control the temperature at 85°C, control the pH at about 8.0, and filter. The product is cobalt carbonate. Then add water to the cobalt carbonate, heat and wash it, and filter it. The purity of the cobalt carbonate product is greater than 98%.

[0042] Example 3

[0043] Step 1: zinc-cobalt leaching solution: 100 g of high-cobalt slag is taken, 15% sulfuric acid solution is used as leaching solution, the leaching liquid-to-solid ratio is 4:1, the leaching temperature is 80° C., and the reaction time is 2.0 h; ammonium persulfate is used as an oxidant, the solution potential is maintained at about 1.20 V during the leaching process, and the zinc-cobalt leaching solution A is obtained by filtering;

[0044] Step 2: Neutralization and impurity removal: In zinc-cobalt leaching solution A, sodium carbonate is added to adjust the pH value. The initial pH value of the iron removal process is 2.0, the end point pH value is 4.0, the temperature is 95°C, the reaction time is 120min, and the air is ventilated and hydrogen peroxide is added to oxidize and remove iron; after a period of reaction, the steam is turned off, and when the temperature drops to 55°C, 4.5g / L of zinc powder is added, and the reaction is carried out for 30min, and then filtered to obtain impurity removal solution B;

[0045] Step 3: Remove zinc once: add caustic soda to a concentration of 4 mol / L in a beaker, then add the impurity removal solution B, reaction temperature 80°C, liquid-to-solid ratio 5:1, reaction time 2h, then filter, the filter residue is crude cobalt. Add hydrogen peroxide to the filtrate for oxidation and filtration;

[0046] Step 4: Secondary zinc removal: During the secondary zinc removal process, water is added to the crude cobalt, the initial pH is controlled at about 4.0, the temperature is controlled at 60°C, and then zinc removal reagent B (9.0 g / L) is slowly added. After a period of reaction, the mixture is filtered, and the filtrate and residue are analyzed;

[0047] Step 5 Cobalt carbonate product: Add sodium carbonate solution to the zinc removal solution, control the temperature at 85°C, control the pH at about 8.0, and filter. The product is cobalt carbonate. Then add water to the cobalt carbonate, heat and wash it, and filter it. The purity of the cobalt carbonate product is greater than 98%. Flow chart:

[0048] The invention provides a process for preparing cobalt carbonate from high-cobalt slag, wherein the reaction temperature is 85 DEG C, the reaction time is 2.0 hours, and the leaching rates of zinc and cobalt in the high-cobalt slag are both higher than 99.0%. The high-cobalt slag, a cobalt-containing material produced in the process of wet zinc smelting, is used for leaching, the sulfuric acid concentration of the leaching solution is 15%, the cobalt concentration in the solution is 10-12 g / L, and the Co / Mn ratio of the solution is higher than 10000, so that the purpose of selective leaching can be achieved. The initial pH value of the iron removal process is 2.0, and the end point pH value is 4.0, so that the iron removal rate reaches 99%, the iron residue reaches 0.1 mg / L, the zinc loss rate is 3.6%, and the cobalt loss rate is 2.5%, which is conducive to improving the iron removal rate, and the loss of cobalt ions is not large. The zinc powder replacement copper and cadmium removal process , the amount of zinc powder added is 4.5g / L, the temperature is between 50-55℃, and the reaction time is 30min, which can achieve better results in the replacement of copper and cadmium; in the first zinc removal process, under the conditions of NaOH concentration 5mol / L, reaction temperature 85℃, reaction time 2h, and liquid-solid ratio of 5:1, the first zinc separation rate reaches 88%; in the second zinc removal process, the initial pH is controlled at about 3.0-4.0, the reaction temperature is 60℃, and the amount of zinc removal reagent B is 9.0g / L, the zinc residue reaches 26mg / L; in the process of sodium carbonate precipitation of cobalt carbonate, the reaction temperature is 85℃, and the reaction pH value is controlled at about 8.0. The cobalt carbonate product meets the requirements and the product purity is greater than 98%.

[0049] Through the above process test research, the high cobalt slag leaching, impurity removal, zinc-cobalt separation, and carbonate precipitation processes were studied, and the optimal process conditions for the whole process were determined:

[0050] The sulfuric acid concentration of the high-cobalt slag leaching solution is 15%, the reaction temperature is 85°C, the reaction time is 2.0 hours, and the zinc and cobalt leaching rates in the high-cobalt slag are both higher than 99.0%; the cobalt concentration in the leaching solution is 10-12 g / L, and the solution Co / Mn ratio is higher than 10000, which can achieve the purpose of selective leaching; the initial pH value of the iron removal process is 2.0, and the end pH value is 4.0, so that the iron removal rate reaches 99%, the iron residue reaches 0.1 mg / L, the zinc loss rate is 3.6%, and the cobalt loss rate is 2.5%, which is conducive to improving the iron removal rate and the loss of cobalt ions. Not much; in the zinc powder replacement process for copper and cadmium removal, the amount of zinc powder added is 4.5g / L, the temperature is 50℃, and the reaction time is 30min, which can achieve a better effect of copper and cadmium replacement; in the first zinc removal process, under the conditions of NaOH concentration 5mol / L, reaction temperature 85℃, reaction time 2h, and liquid-solid ratio of 5:1, the first separation rate of zinc reaches 88%; in the second zinc removal process, the initial pH is controlled at about 3.0-4.0, the reaction temperature is 60℃, and the amount of zinc removal reagent B is 9.0g / L, the residual zinc reaches 26mg / L; in the process of sodium carbonate precipitation of cobalt carbonate, the reaction temperature is 85℃, the reaction pH value is controlled at about 8.0, the cobalt carbonate product meets the requirements, and the product purity is greater than 98%.

[0051] A full-process verification test was carried out under the above test conditions, and the test results are shown in the following table.

[0052] Table 3 Controlled potential leaching test results

[0053]

[0054]

[0055] Table 4 Neutralization and impurity removal test results

[0056]

[0057] Table 5. Results of a zinc removal test

[0058]

[0059] Table 6 Secondary zinc removal test results

[0060]

[0061] Table 7 Recovery calculation table

[0062] Leaching Remove impurities One-step zinc removal Secondary zinc removal Cobalt deposition Total recovery rate Cobalt recovery rate % 90.0 98.0 98.0 98.0 99.0 83.86 Zinc recovery rate % 96.0 97.0 98.0 98.5 / 89.8

[0063] Table 8 Composition of output slag

[0064] Zn Co Mn Fe Ca S O Cu Cd Slag rate / % Leaching manganese slag 6.4 10.3 27.7 1.6 0.13 8.6 26.7 0.06 0.45 12 Iron slag removal 11.5 3.5 0.02 30.3 0.1 3.5 24.5 4.3 10.3 6.5 Acid slag 3.0 2.0 0.1 6.3 8.6 35 20 0.02 0.03 2.3

[0065] The cobalt leaching rate is 90% and the zinc leaching rate is 95%. After the leaching liquid is neutralized to remove iron, copper and cadmium, the cobalt loss rate is 2.0%. Zinc removal is carried out again, and the zinc removal liquid is returned to the zinc system after treatment. The cobalt loss rate is 0.5%. The crude cobalt is acid-dissolved and then zinc is removed for a second time. After the zinc removal slag is pickled, the liquid is returned to the leaching, and the cobalt loss rate is 2%. The cobalt recovery rate of the entire process is 83.86%, and the zinc recovery rate of the entire process is 89.8%.

[0066] The above embodiments are merely descriptions for the purpose of clearly illustrating the present invention, and are not limitations on the implementation methods. For those skilled in the art, other different forms of changes or modifications may be made based on the above descriptions. It is not necessary and impossible to enumerate all the implementation methods here, and the obvious changes or modifications derived therefrom are still within the scope of protection of the present invention.

Claims

1. A process for preparing cobalt carbonate from high-cobalt slag, characterized in that: The method comprises the following steps: step 1: zinc-cobalt leaching solution: potential-controlled leaching, taking 100 g of high-cobalt slag, using 15% sulfuric acid solution as leaching solution, using a leaching solution-solid ratio of 4:1, a leaching temperature of 85° C., a reaction time of 2.0 h, using ammonium persulfate as an oxidant, maintaining the solution potential at about 1.20 V during the leaching process, filtering to obtain a zinc-cobalt leaching solution A, wherein the zinc and cobalt leaching rates in the high-cobalt slag are both higher than 99.0%; the cobalt concentration in the leaching solution is 10-12 g / L, and the solution Co / Mn ratio is higher than 10000, thereby achieving the purpose of selective leaching; starting the timing after the potential is stable, and taking samples at regular intervals to analyze the solution and solid components; Step 2: Neutralization and impurity removal: In zinc-cobalt leaching solution A, sodium carbonate is added to adjust the pH value, and hydrogen peroxide is added to heat and ventilate to remove iron. After a period of reaction, the steam is turned off, and zinc powder is added to remove copper and cadmium when the temperature drops to 50-55°C. After a period of reaction, the filtrate and the filter residue are analyzed. The initial pH value of the iron removal process is 2.0, the end pH value is 4.0, the temperature is 95°C, and the reaction time is 120min. In this way, the iron removal rate reaches 99%, the residual iron reaches 0.1mg / L, the zinc loss rate is 3.6%, and the cobalt loss rate is 2.5%, which is conducive to improving the iron removal rate, and the loss of cobalt ions is not large; in the process of zinc powder replacement for copper and cadmium removal, the amount of zinc powder added is 4.5g / L, the temperature is between 50-55°C, the reaction is 30min, and then the impurity removal liquid B is obtained by filtration, which can achieve a better effect of replacement for copper and cadmium removal; Step 3: In the primary zinc removal process, NaOH is added to a beaker, and then the impurity removal liquid B is added. After heating and reacting for a period of time, the filter is filtered. The filter residue is crude cobalt. The filtrate is oxidized and filtered with hydrogen peroxide. Under the conditions of NaOH concentration of 5 mol / L, reaction temperature of 85°C, reaction time of 2 h, and liquid-solid ratio of 5:1, the primary separation rate of zinc reaches 88%; Step 4: In the secondary zinc removal process, water is added to the crude cobalt, and then sulfuric acid is slowly added to stir the reaction. Under the conditions of controlling the initial pH at 3.0-4.0 and the reaction temperature at 60°C, zinc removal reagent B (sodium hydroxide) is slowly added. After reacting for a period of time, the reaction is filtered. When the dosage of zinc removal reagent B is 9.0 g / L, the residual zinc content reaches 26 mg / L; Step 5: Cobalt precipitation: After zinc removal, sodium carbonate solution is added to the liquid, and the temperature and pH are controlled. The product is cobalt carbonate. The reaction temperature of the sodium carbonate precipitation process of cobalt carbonate is 85°C and the pH value is 8.

0. The cobalt carbonate product meets the requirements and the product purity is greater than 98%.

2. A process for preparing cobalt carbonate from high-cobalt slag according to claim 1, characterized in that: The chemical composition content of the high cobalt slag is as follows: The phase composition of high cobalt slag is as follows:

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