A method for recovering lead from lead slag to prepare high-purity lead sulfate

Abstract

The application discloses a method for recovering lead from lead slag to prepare high-purity lead sulfate, and relates to the technical field of non-ferrous metal and rare earth metallurgy recovery. The method comprises the following steps: adding acetic acid into the lead slag, adding titanium dioxide as an oxidation catalyst, stirring, heating, then adding hydrogen peroxide drop by drop, filtering after reaction, obtaining a mixed solution of lead acetate and lanthanum acetate, adding a sulfuric acid solution, heating and evaporating, recycling the acetic acid solution to be used in the above cycle, filtering after evaporating and cooling, washing the obtained precipitate and drying to obtain high-purity lead sulfate. Through the synergistic effect of acetic acid, hydrogen peroxide and titanium dioxide, the purity of the product lead sulfate is improved, and the lead recovery rate is increased. The purity of the obtained lead sulfate product is greater than 98.5%, and the lead recovery rate can reach more than 97%, effectively solving the problems of high energy consumption, serious environmental pollution and low recovery rate in the prior art.

Description

Technical Field

[0001] This invention relates to the field of non-ferrous metal rare earth metallurgical recycling technology, specifically to a method for recovering lead from lead slag to prepare high-purity lead sulfate. Background Technology

[0002] In rare earth smelting, especially with mixed rare earth ores such as bastnaesite and monazite, after acid or alkaline decomposition, extraction separation, and deep impurity removal, waste slag containing lead sulfide, such as lanthanum-lead slag, is generated. In this type of waste slag, lead exists in the form of lead sulfide, containing 55-65% lead oxide (dry weight), 10-20% rare earth content (calculated as rare earth oxides REO), and barium exists in the form of barium sulfate, with a barium oxide content of 6-10%. Currently, most companies use temporary storage and stockpiling to dispose of this waste slag. This method not only occupies space resources but may also lead to lead ions (Pb) being released into the form of lead oxides. 2+ Lead can enter the environment in the form of lead or dust, causing soil and water pollution, and even harming human health through the food chain, such as causing lead poisoning.

[0003] Currently, traditional lead recycling methods mainly rely on high-temperature roasting or strong acid leaching technologies, but these methods generally suffer from high energy consumption, severe environmental pollution, and low recovery rates. Therefore, developing an efficient, environmentally friendly, and economically feasible lead recycling method to achieve resource recycling has become a critical issue that the industry urgently needs to address. Summary of the Invention

[0004] To address the aforementioned shortcomings in existing technologies, this invention provides a method for recovering lead from lead slag to prepare high-purity lead sulfate. This method increases lead recovery rate while improving product purity, effectively solving the problems of high energy consumption, severe environmental pollution, and low recovery rate in existing lead recovery methods.

[0005] To achieve the above objectives, the technical solution adopted by the present invention to solve its technical problem is: to provide a method for recovering lead from lead slag to prepare high-purity lead sulfate, comprising the following steps: S1. Add acetic acid and titanium dioxide to lead slag, stir and heat, then add hydrogen peroxide dropwise while keeping the temperature constant during the addition of hydrogen peroxide. After the reaction, filter to obtain a mixed solution of lead acetate and lanthanum acetate. S2. Add sulfuric acid solution to the mixed solution of lead acetate and lanthanum acetate obtained in step S1, then heat and evaporate to obtain lead sulfate and rare earth sulfate precipitates and recover the acetic acid solution. The acetic acid solution is returned to step S1 for recycling. S3. After evaporation and cooling, filter the acetic acid. The filtered acetic acid is returned to step S1 for use. Wash the obtained precipitate to obtain rare earth sulfate solution and lead sulfate precipitate. Dry the lead sulfate precipitate to obtain high-purity lead sulfate. The rare earth sulfate solution is returned to the rare earth process for rare earth recovery.

[0006] Furthermore, in step S1, the mass-to-volume ratio of lead slag, acetic acid, and hydrogen peroxide is: 190-210g: 300-400mL: 155-170mL.

[0007] Furthermore, in step S1, the mass-to-volume ratio of lead slag, acetic acid, and hydrogen peroxide is 200g:300mL:160mL.

[0008] Furthermore, in step S1, the concentration of acetic acid is 50-60 wt%.

[0009] Furthermore, in step S1, the concentration of acetic acid is 50 wt%.

[0010] Furthermore, in step S1, the concentration of hydrogen peroxide is 25-27 wt%.

[0011] Furthermore, in step S1, the concentration of hydrogen peroxide is 26 wt%.

[0012] Furthermore, in step S1, the amount of titanium dioxide added is 0.1-0.3% of the mass of lead slag.

[0013] Furthermore, in step S1, the amount of titanium dioxide added is 0.1% of the mass of lead slag.

[0014] Furthermore, in step S1, the temperature is increased to 55-60°C.

[0015] Furthermore, in step S1, the temperature is raised to 55°C.

[0016] Furthermore, in step S1, hydrogen peroxide is added dropwise until the lead slag changes from black to grayish-black.

[0017] Furthermore, in step S1, the reaction is carried out for 30-60 minutes.

[0018] Furthermore, in step S1, the reaction is carried out for 40 minutes.

[0019] Further, in step S1, the barium slag is removed by filtration.

[0020] Furthermore, in step S2, the mass-to-volume ratio of lead slag to sulfuric acid solution is 190-210g:382-507mL.

[0021] Furthermore, in step S2, the mass-to-volume ratio of lead slag to sulfuric acid solution is 200g:484mL.

[0022] Furthermore, in step S2, the concentration of the sulfuric acid solution is 0.4-0.6 mol / L.

[0023] Furthermore, in step S2, the concentration of the sulfuric acid solution is 0.5 mol / L.

[0024] Furthermore, in step S2, the mixture is heated to 110-115°C for evaporation.

[0025] Furthermore, in step S2, the mixture is heated to 112°C for evaporation.

[0026] Furthermore, in step S2, an acetic acid condensation and recovery device is connected to recover the acetic acid solution.

[0027] Furthermore, in step S3, the evaporation temperature is reduced to 101-103℃.

[0028] Furthermore, in step S3, the temperature is cooled to 102°C by evaporation.

[0029] Furthermore, in step S3, the sample is washed 5-6 times with pure water in a counter-current manner.

[0030] Furthermore, in step S3, the product is dried at 115-120°C.

[0031] Furthermore, in step S3, the product is dried at 120°C.

[0032] The present invention has the following beneficial effects: 1. This invention utilizes the synergistic effect of acetic acid and hydrogen peroxide, with titanium dioxide as an oxidation catalyst, to improve the purity of lead sulfate and increase lead recovery rate. The lead sulfate product obtained by the method provided by this invention has a purity greater than 98.5%, which is an improvement over traditional processes. Furthermore, by controlling the acetic acid concentration gradient and the oxidation intensity of hydrogen peroxide, the lead metal recovery rate exceeds 97%, significantly reducing resource waste. The obtained lead sulfate can be directly used in industries such as lead-acid batteries and pigments.

[0033] 2. In this method, the distillation temperature is controlled at 100-118℃, which effectively separates lead sulfate and acetic acid. Both the distilled and undistilled acetic acid can be recycled, reducing the amount of waste acid discharged.

[0034] 3. By using acetic acid for gentle leaching, the current problems of lead slag storage and environmental issues in rare earth smelting enterprises are effectively solved. At the same time, acetic acid can be recycled and reused, reducing the amount of auxiliary materials used and making it more environmentally friendly. Detailed Implementation

[0035] The principles and features of this invention are described below. The examples given are for illustrative purposes only and are not intended to limit the scope of the invention. Unless otherwise specified in the examples, conventional conditions or conditions recommended by the manufacturer should be followed. Reagents or instruments whose manufacturers are not specified are all commercially available products.

[0036] Example 1 A method for recovering lead from lead slag to prepare high-purity lead sulfate includes the following steps: S1. Take 200g of lead slag and test it. The moisture content of the lead slag is 34%, the dry weight of lead oxide is 60%, and the rare earth oxide content is 13.5%. Add 300mL of 50wt% acetic acid and 0.2g of titanium dioxide to 200g of lead slag. After stirring with a stirrer, heat to 55℃, and then add 160mL of 26wt% hydrogen peroxide dropwise to change the lead slag from black to grayish black. Keep the temperature constant during the addition of hydrogen peroxide. After reacting for 40min, filter to remove barium slag and obtain a mixed solution of lead acetate and lanthanum acetate. S2. Add 382 mL of 0.5 mol / L sulfuric acid solution to the mixed solution of lead acetate and lanthanum acetate obtained in step S1, then heat to 112 °C to evaporate, and obtain lead sulfate and rare earth sulfate precipitates and recover the acetic acid solution. The acetic acid solution is returned to step S1 for recycling. S3. After evaporation and cooling to 102℃, filter the acetic acid. The filtered acetic acid is returned to step S1 for use. The precipitate is washed five times countercurrently with pure water to obtain rare earth sulfate solution and lead sulfate precipitate. The lead sulfate precipitate is dried at 115℃ to obtain high-purity lead sulfate with a mass of 106.5g. The rare earth sulfate solution is returned to the rare earth process for rare earth recovery.

[0037] Example 2 A method for recovering lead from lead slag to prepare high-purity lead sulfate includes the following steps: S1. Take 200g of lead slag and test it. The moisture content of the lead slag is 28%, the dry weight of lead oxide is 58%, and the rare earth oxide content is 15.7%. Add 300mL of 60wt% acetic acid and 0.4g of titanium dioxide to 200g of lead slag. After stirring with a stirrer, heat to 55℃. Then add 170mL of 25wt% hydrogen peroxide dropwise to change the lead slag from black to grayish black. Keep the temperature constant during the addition of hydrogen peroxide. After reacting for 30min, filter to remove barium slag and obtain a mixed solution of lead acetate and lanthanum acetate. S2. Add 484 mL of 0.4 mol / L sulfuric acid solution to the mixed solution of lead acetate and lanthanum acetate obtained in step S1, then heat to 110 °C to evaporate, and obtain lead sulfate and rare earth sulfate precipitates and recover the acetic acid solution. The acetic acid solution is returned to step S1 for recycling. S3. After evaporation and cooling to 101℃, filter the acetic acid. The filtered acetic acid is returned to step S1 for use. The precipitate is washed five times with pure water in a countercurrent manner to obtain rare earth sulfate solution and lead sulfate precipitate. The lead sulfate precipitate is dried at 120℃ to obtain high-purity lead sulfate with a mass of 112.1g. The rare earth sulfate solution is returned to the rare earth process for rare earth recovery.

[0038] Example 3 A method for recovering lead from lead slag to prepare high-purity lead sulfate includes the following steps: S1. Take 200g of lead slag and test it. The moisture content of the lead slag is 30%, the dry weight of lead oxide is 55%, and the rare earth oxide content is 16.9%. Add 400mL of 60wt% acetic acid and 0.6g of titanium dioxide to 200g of lead slag. After stirring with a stirrer, heat to 60℃, and then add 160mL of 27wt% hydrogen peroxide dropwise to change the lead slag from black to grayish black. Keep the temperature constant during the addition of hydrogen peroxide. After reacting for 60min, filter to remove barium slag and obtain a mixed solution of lead acetate and lanthanum acetate. S2. Add 507 mL of 0.6 mol / L sulfuric acid solution to the mixed solution of lead acetate and lanthanum acetate obtained in step S1, then heat to 115 °C to evaporate, and obtain lead sulfate and rare earth sulfate precipitates and recover the acetic acid solution. The acetic acid solution is returned to step S1 for recycling. S3. After evaporation and cooling to 103℃, filter the acetic acid. The filtered acetic acid is returned to step S1 for use. The precipitate is washed 6 times countercurrently with pure water to obtain rare earth sulfate solution and lead sulfate precipitate. The lead sulfate precipitate is dried at 115℃ to obtain high-purity lead sulfate with a mass of 102.3g. The rare earth sulfate solution is returned to the rare earth process for rare earth recovery.

[0039] Comparative Example 1 A method for recovering lead from lead slag to prepare lead sulfate includes the following steps: S1. Take 200g of lead slag, and test the moisture content of the lead slag to be 30%, the lead oxide content on dry weight to be 55%, and the rare earth oxide content to be 16.9%. Add 400mL of 60wt% acetic acid to 200g of lead slag, add 0.1g of titanium dioxide, stir with a stirrer, heat to 60℃, react for 3h, filter, and obtain a mixed solution. S2. Add 507 mL of 0.5 mol / L sulfuric acid solution to 450 mL of mixed solution, then heat to boiling. The system temperature at boiling point is 111 °C. Connect the acetic acid condensation and recovery device to recover the acetic acid solution. S3. After evaporation and cooling to 102℃, the mixture is filtered. The precipitate is washed six times under countercurrent conditions and dried at 120℃ to obtain lead sulfate, with a mass of 1.28g. The lanthanum sulfate washing solution can be returned to the rare earth production process for recycling, and the recovered acetic acid is returned to step S1.

[0040] Comparative Example 2 A method for recovering lead from lead slag to prepare lead sulfate includes the following steps: S1. Take 200g of lead slag, and test the moisture content of the lead slag to be 30%, the lead oxide content on dry weight to be 55%, and the rare earth oxide content to be 16.9%. Add 400mL of pure water and 0.1g of titanium dioxide to 200g of lead slag, heat to 55℃ with a stirrer, and then add 155mL of 27wt% hydrogen peroxide dropwise. After reacting for 3 hours, filter to obtain a mixed solution. S2. Add 155 mL of 0.5 mol / L sulfuric acid solution to 580 mL of the mixed solution obtained in step S1, and then heat to boiling. The system temperature at boiling point is 102 °C. S3. When the volume of the mixed solution evaporates to one-tenth of the initial volume, filter it, wash the precipitate five times by countercurrent, and dry it at 120°C to obtain lead sulfate with a mass of 0.14g.

[0041] Comparative Example 3 A method for recovering lead from lead slag to prepare lead sulfate includes the following steps: S1. Take 200g of lead slag and test it. The moisture content of the lead slag is 34%, the dry weight of lead oxide is 60%, and the rare earth oxide content is 13.5%. Add 300mL of 50wt% acetic acid to 200g of lead slag, stir with a stirrer and heat to 55℃. Then add 109mL of 27wt% hydrogen peroxide dropwise. Keep the temperature constant during the addition of hydrogen peroxide. After reacting for 40min, filter to remove barium slag and undissolved lead sulfide to obtain a mixed solution. S2. Add 382 mL of 0.5 mol / L sulfuric acid solution to the mixed solution obtained in step S1, then heat to 111 °C to evaporate, and connect to an acetic acid condensation and recovery device to recover the acetic acid solution. The acetic acid solution is returned to step S1 for recycling. S3. After evaporation and cooling to 102℃, filter the solution and wash the precipitate five times with pure water in a countercurrent manner to remove residual acetic acid and lanthanum sulfate. Then dry the solution at 115℃ to obtain lead sulfate with a mass of 82.04g.

[0042] Experimental Example 1 The purity of lead sulfate prepared by the methods provided in Examples 1-3 and Comparative Examples 1-3 was determined, and the results are shown in Table 1. The formula for calculating the purity of lead sulfate is: Purity (%) = (actual mass of lead sulfate produced / total mass of sample) × 100%.

[0043] Table 1. Purity of Lead Sulfate

[0044] As shown in Table 1, the lead sulfate product prepared by the method provided by the present invention has a purity of over 98%, which is higher than that of the lead sulfate prepared by the comparative example.

[0045] Experimental Example 2 The lead recovery rates of the methods provided in Examples 1-3 and Comparative Examples 1-3 were calculated, and the results are shown in Table 2. The formula for calculating the lead recovery rate is: Lead recovery rate (%) = (Actual recovered lead mass / Theoretical lead mass) × 100%.

[0046] Table 2 Lead recovery rate

[0047] As shown in Table 2, the method provided by this invention can achieve a lead recovery rate of over 97%, which is much higher than the lead recovery rate of the comparative example.

[0048] In summary, the method provided by this invention not only significantly improves the purity of lead sulfate products but also increases the lead recovery rate. The purity of the obtained lead sulfate product is greater than 98.5%, and the lead recovery rate can reach over 97%.

[0049] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for recovering lead from lead slag to prepare high-purity lead sulfate, characterized in that, Includes the following steps: S1. Add acetic acid and titanium dioxide to lead slag, stir and heat to 55-60℃, then add hydrogen peroxide dropwise while keeping the temperature constant during the addition of hydrogen peroxide. After the reaction, filter to obtain a mixed solution of lead acetate and lanthanum acetate. S2. Add sulfuric acid solution to the mixed solution of lead acetate and lanthanum acetate obtained in step S1, then heat to 110-115℃ to evaporate, obtain lead sulfate and rare earth sulfate precipitates and recover the acetic acid solution, which is returned to step S1 for recycling. S3. After evaporation and cooling, filter the acetic acid. The filtered acetic acid is returned to step S1 for use. Wash the obtained precipitate to obtain rare earth sulfate solution and lead sulfate precipitate. Dry the lead sulfate precipitate to obtain high-purity lead sulfate. The rare earth sulfate solution is returned to the rare earth process to recover rare earth. The mass-to-volume ratio of lead slag, acetic acid and hydrogen peroxide is 190-210g:300-400mL:155-170mL; In step S1, the concentration of acetic acid is 50-60 wt%. In step S1, the concentration of the hydrogen peroxide is 25-27 wt%. In step S1, the amount of titanium dioxide added is 0.1-0.3% of the mass of the lead slag; In step S3, the temperature is reduced to 101-103℃ by evaporation.

2. The method for preparing high-purity lead sulfate from lead slag as described in claim 1, characterized in that, In step S1, the reaction takes 30-60 minutes.

3. The method for preparing high-purity lead sulfate from lead slag as described in claim 1, characterized in that, In step S2, the mass-to-volume ratio of lead slag to sulfuric acid solution is 190-210g:382-507mL.

4. The method for preparing high-purity lead sulfate from lead slag as described in claim 1, characterized in that, In step S2, the concentration of the sulfuric acid solution is 0.4-0.6 mol / L.

5. The method for preparing high-purity lead sulfate from lead slag as described in claim 1, characterized in that, In step S3, the product is dried at 115-120℃.

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