Method for separating lead from zinc and copper in acetate system

Abstract

A method for separating lead from zinc and copper in acetate system, first, calcium carbonate and activator are added to the acetate leaching solution containing lead, zinc and copper, lead acetate in the solution is preferentially reacted with calcium carbonate to generate lead carbonate under the action of the activator, realizing selective precipitation of lead, then calcium hydroxide is added to the lead precipitation solution, zinc and copper in the solution are neutralized and precipitated, and sulfuric acid is added to the zinc and copper precipitation solution to return the acetate to leaching. The present application realizes low-cost and high-efficiency separation of each metal from the acetate leaching solution containing lead, zinc and copper, and the precipitation rate of lead, zinc and copper is greater than 98%.

Description

Technical Field

[0001] This invention belongs to the technical field of non-ferrous metal separation methods, specifically relating to a method for separating lead from zinc and copper in an acetate system. Background Technology

[0002] With the large-scale exploitation and consumption of mineral resources in my country, rich ores are becoming increasingly scarce, ore grades are declining year by year, and most are associated minerals. Sulfide ores suitable for beneficiation are becoming increasingly rare, and a large number of lead, zinc, and copper mixed ores are difficult-to-process oxide minerals, many of which are high-silica oxides. The non-ferrous metals in these high-silica minerals are difficult to directly leach using low-cost sulfuric acid because they generate large amounts of silica gel, making the slurry unfilterable. Papers such as Chen Yonghai et al.'s "Research Progress on Acid Leaching Desilication Process of High-Silica Zinc Oxide Ores" (Hunan Nonferrous Metals, Vol. 21, No. 1, 2005) and Li Linfei et al.'s "Research and Technological Progress on Wet Leaching of High-Silica Zinc Oxide Ores and Zinc Silicate Minerals" (Journal of Kunming University of Science and Technology (Natural Science Edition), Vol. 41, No. 4, 2016) have both described similar high-silica zinc oxide ores and their processing difficulties. In addition, the lead-silver slag produced by zinc hydrometallurgy mainly contains lead in the form of lead sulfate, and also contains small amounts of zinc and copper. Because the lead content in the slag is low and the sulfur content is high, it is difficult to process by pyrometallurgical methods.

[0003] For high-silica oxide ores, the main processing methods include pyrometallurgical treatment, acid leaching, alkaline leaching, and ammonia leaching. Pyrometallurgical processes are largely obsolete due to their high energy consumption, significant environmental pollution, and high cost. Acid leaching mainly refers to sulfuric acid leaching, including processes such as the Laoshan process, the Nuodiri process, the EZ process, neutralization coagulation, and pressure leaching. These methods primarily convert silicon in the solution into crystalline silicon dioxide or remove it by forming a dense precipitate. However, these methods are difficult to promote due to their demanding conditions and high technical difficulty. Alkaline leaching mainly refers to sodium hydroxide leaching. Alkaline leaching can avoid the leaching of impurities such as iron and reduce the number of impurity removal steps, but calcium oxide needs to be added to avoid silicon leaching. Zhao Zhongwei et al. proposed the "zinc Bayer process," which uses the Bayer process for alumina production to achieve alkaline dissolution, electrolytic deposition of zinc, and alkali regeneration of zinc oxide minerals. However, this process requires high temperature and high sodium hydroxide conditions, limiting its widespread adoption. Ammonia leaching uses ammonia-ammonium salts as leaching reagents to leach zinc and copper. This method avoids the formation of insoluble silica gel, but it has environmental problems caused by the strong volatility of ammonia. At the same time, it has the problem that silicate minerals such as zinc silicate and hemimorphite are difficult to leach, and the process is difficult to promote.

[0004] The lead-silver slag produced from zinc hydrometallurgy is currently mainly treated through processes such as its use as a raw material for pyrometallurgical lead smelting and wet chloride leaching. However, as a raw material for pyrometallurgical lead smelting, the low lead content and high sulfur content of the slag limit its use to small-scale additions and prevent large-scale processing. Wet chloride leaching uses excess chloride as the leaching agent to convert lead into a complex that enters the solution, achieving leaching. Simultaneously, precious metals such as gold and silver are also complexed and leached into the solution. Chinese invention patent application number 201310100691.8 discloses a lead sulfate hydrometallurgical process using CaCl2 + NaCl as the leaching solvent. This process leaches high-leaching slag containing lead sulfate from hydrometallurgical zinc smelting, lead slag after zinc leaching from lead-containing zinc oxide, or lead sludge from dismantled lead-acid batteries. The leaching solution is then used to replace lead with zinc, and the zinc is recovered and returned to the lead replacement process. The recovered zinc is then used to replace the lead in the solution. - The liquid is recycled to the lead sulfate chloride leaching process. This process not only extracts lead but also recovers some precious metals. It is suitable for the treatment of lead-silver slag with high precious metal content. However, the production cost of this process is high, and there are also problems such as high temperature and high chloride ion causing serious corrosion to the equipment, which makes it difficult to promote the process on a large scale.

[0005] In summary, traditional processes are all inadequate for processing high-silica oxide ores and lead-silver slag. Summary of the Invention

[0006] To address the shortcomings of existing technologies, the purpose of this invention is to provide a method for separating lead from zinc and copper in an acetate system, thereby solving the problems of difficulty and high cost in separating lead from zinc and copper in existing acetate systems.

[0007] The technical solution adopted in this invention is as follows: A method for separating lead from zinc and copper in an acetate system, comprising the following steps: (1) Sinking lead: A solution of acetate containing lead, zinc, and copper is mixed with calcium carbonate and an activator to form a slurry. The slurry is then added to a reaction vessel, heated to 20-150 °C, and stirred for 0.5-5 h. After the reaction is complete, the slurry is filtered, and the filter residue is lead slag, while the filtrate is lead precipitation solution. The amount of calcium carbonate added is 1 to 2 times the theoretical amount of calcium carbonate consumed by lead in the solution; the activator is one or more of nitric acid, hydrochloric acid, acetic acid, sulfuric acid, phosphoric acid, sulfur dioxide, carbon dioxide, nitrogen dioxide, and phosphorus pentoxide, and the concentration of the activator is 0.05 to 1 mol / L; (2) Zinc and copper immersion: The lead precipitation solution in step (1) is mixed with calcium hydroxide and slurried. Then the slurried material is added to the reaction vessel, heated to 10~100 ℃, stirred and reacted for 0.5~4 h, and the final pH is 7~11. After the reaction is completed, the slurry is filtered. The filter residue is zinc and copper slag, and the filtrate is zinc and copper precipitation solution containing calcium acetate. The amount of calcium hydroxide added is 1 to 2 times the theoretical amount of calcium hydroxide consumed by zinc and copper; (3) Regenerated acetic acid: Add the zinc and copper precipitate solution from step (2) into the reactor, add the sulfuric acid solution into the reactor, and the calcium acetate reacts with the sulfuric acid to generate calcium sulfate and regenerate acetic acid. After the reaction is completed, the slurry is filtered and the filtrate is the regenerated acetic acid solution, which can be returned to step (1) for lead precipitation. The gypsum slag is stored for further treatment.

[0008] Furthermore, the acetate solution containing lead, zinc, and copper is obtained by directly leaching high-silica oxide ores using acetic acid and acetates as leaching agents.

[0009] Furthermore, the acetate solution containing lead, zinc, and copper is obtained by first converting lead sulfate to lead carbonate from the wet zinc-lead-silver slag using carbonate, and then leaching it with acetic acid and acetate as leaching agents.

[0010] The technical principle of the method of the present invention is as follows: The solubility product of lead carbonate is K sp 7.4×10 -14 The solubility product of copper carbonate, K sp 2.3×10 -10 Zinc carbonate solubility product K sp 1.4×10 -11 The difference of several orders of magnitude indicates that when adding carbonates to precipitate lead, zinc, and copper, lead carbonate preferentially precipitates over copper carbonate and zinc carbonate. To enable the recycling of acetic acid and reduce production costs, this invention innovatively uses calcium carbonate as the carbonate precipitator for lead, zinc, and copper. Since calcium carbonate is a sparingly soluble salt with poor activity, an activator can be added to improve its activity. The activator is soluble in water to form a moderately strong acid. This moderately strong acid reacts with acetate in a strong acid-weak acid reaction to produce acetic acid. Acetic acid then reacts with calcium carbonate to produce carbon dioxide. Finally, the carbon dioxide reacts with lead acetate to produce lead carbonate and acetic acid, which then reacts again with calcium carbonate. Since the solubility product of lead carbonate is K... sp 7.4×10 -14 The solubility product of calcium carbonate, K sp 2.8×10 -9 The reaction occurs on a fraction of the order of magnitude smaller, therefore the acetic acid produced preferentially reacts with calcium carbonate, while lead carbonate remains largely unreacted and is preserved. This reaction continues until all the lead acetate is converted to lead carbonate precipitate. Simultaneously, due to the solubility product K of copper carbonate… sp 2.3×10 -10Zinc carbonate solubility product K sp 1.4×10 -11 With calcium carbonate solubility product K sp 2.8×10 -9 With similar solubility products, copper carbonate and zinc carbonate are difficult to form. As long as the amount of calcium carbonate added is controlled to the theoretical amount required to form lead carbonate, the formation of copper carbonate and zinc carbonate can be prevented.

[0011] Zinc acetate and copper acetate are strong electrolytes. When zinc hydroxide precipitation is complete, the pH (residual ion concentration <10) is... -5 The concentration of copper hydroxide (mol / L) was 8.0, and the pH was <10 when copper hydroxide precipitation was complete. -5 The concentration (mol / L) is 6.7. Lead acetate is a weak electrolyte and poorly ionized. Although the pH is <10 when lead hydroxide is completely precipitated, the residual ion concentration is still low. -5 The pH value (mol / L) is 8.7, but the lead ion concentration in the solution is very low. The actual pH at which precipitation is complete is much higher than 8.7. Therefore, separation can be achieved by controlling the endpoint pH to preferentially precipitate copper and zinc, with a small portion of lead precipitating. Furthermore, lead hydroxide and zinc hydroxide are amphoteric hydroxides; if the pH is too high, they will dissolve and enter the solution. The pH at which zinc hydroxide precipitation begins to dissolve is 10.5, and the pH at which lead hydroxide precipitation begins to dissolve is 10. Therefore, by adding low-cost reagents to control the endpoint pH within a suitable range, zinc and copper can be selectively precipitated, achieving the separation of zinc, copper, and lead.

[0012] For high-silica oxide ores, direct leaching with acetic acid and acetate as leaching agents yields acetate solutions containing lead, zinc, and copper. This method not only leaches lead, zinc, and copper from the minerals but also utilizes acetic acid and acetate as a buffer solution with a pH between 4 and 7, making it difficult for silicon to dissolve and preventing the formation of silica gel. This achieves highly efficient and selective leaching of lead, zinc, and copper. For wet zinc-lead-silver slag, lead sulfate is first converted to lead carbonate using carbonate, followed by leaching with acetic acid and acetate as leaching agents, also yielding acetate solutions containing lead, zinc, and copper.

[0013] The advantages of this invention are as follows: (1) The use of an activator significantly improves the activity of calcium carbonate. The activator indirectly generates carbon dioxide, which can react with lead acetate to generate lead carbonate, thus solving the problem of poor activity of calcium carbonate. At the same time, the regenerated acetic acid continuously reacts with calcium carbonate to generate carbon dioxide, and the activator acts as a catalyst in this process.

[0014] (2) Separation of lead from zinc and copper was achieved. Calcium carbonate was activated by an activator to achieve preferential precipitation of lead carbonate, thus separating lead from zinc and copper. Calcium hydroxide was added to utilize the special weak electrolyte properties of lead acetate to achieve preferential precipitation of copper hydroxide and zinc hydroxide, thus separating lead from zinc and copper.

[0015] (3) Low processing cost. The reagents used in the entire process are low-cost calcium carbonate, calcium hydroxide and sulfuric acid. The activator plays the role of catalysis and is consumed in very small amounts. At the same time, acetic acid is recycled.

[0016] This invention first adds calcium carbonate and an activator to an acetate leaching solution containing lead, zinc, and copper. Under the action of the activator, the lead acetate in the solution preferentially reacts with calcium carbonate to form lead carbonate, achieving selective precipitation of lead. Then, calcium hydroxide is added to the lead precipitation solution to neutralize and precipitate the zinc and copper in the solution. Sulfuric acid is added to the zinc and copper precipitation solution to regenerate acetic acid. This invention uses low-cost calcium carbonate, calcium hydroxide, and an activator to achieve the separation of lead, zinc, and copper from acetate solutions. The precipitation rate of lead, zinc, and copper is greater than 98%; the lead slag product contains more than 60% lead and less than 2% zinc and copper; the zinc and copper slag product contains more than 40% zinc and copper and less than 2% lead. This invention achieves low-cost and efficient separation of lead, zinc, and copper from acetate systems and is applicable to the separation of lead, zinc, and copper in various acetate systems. Attached Figure Description

[0017] Figure 1 This is a flowchart of the present invention. Detailed Implementation

[0018] The invention will now be further described in conjunction with the accompanying drawings. Example 1

[0019] A method for separating lead from zinc and copper in an acetate solution containing lead, zinc, and copper. The acetate solution containing lead, zinc, and copper is obtained by direct leaching of high-silica oxidized ores using acetic acid and acetate as leaching agents, and its composition (g / L) is: Pb 60.5, Zn 23.3, Cu 5.7, Ca 15.3, HAc 8.2.

[0020] See Figure 11 L of acetate solution, 46 g of calcium carbonate, and 0.1 mol / L acetic acid (an activator) were added to a sealed reactor. The reactor was heated to 80°C and stirred for 1 hour. After the reaction, the slurry was filtered, and the residue was lead slag. The mass contents of lead, zinc, and copper in the lead slag were 68.53%, 0.76%, and 0.12%, respectively. The filtrate was used as a lead precipitation solution for subsequent zinc and copper precipitation. The lead precipitation solution was mixed with a certain amount of calcium hydroxide and slurried. The slurry was then added to the reactor, heated to 60°C, and stirred for 2 hours. The final pH was 9. After the reaction, the slurry was filtered, and the residue was zinc and copper slag. The mass contents of zinc, copper, and lead in the slag were 40.46%, 9.69%, and 0.83%, respectively. The filtrate was a zinc and copper precipitation solution containing calcium acetate. Zinc and copper precipitate solutions are added to a reaction vessel along with a sulfuric acid solution diluted to a mass concentration of 10%. Calcium acetate reacts with sulfuric acid to produce calcium sulfate, while acetic acid is regenerated. After the reaction is complete, the mixture is filtered, and the filtrate is a regenerated acetic acid solution that can be returned for lead precipitation. The gypsum residue is stored for further treatment. Example 2

[0021] A method for separating lead from zinc and copper in an acetate solution containing lead, zinc, and copper. The acetate solution containing lead, zinc, and copper is obtained by first converting lead sulfate to lead carbonate from wet zinc-lead-silver slag using carbonates, and then leaching it with acetic acid and acetates as leaching agents. Its composition (g / L) is: Pb 93.1, Zn 16.5, Cu 3.4, Ca 8.4, HAc 10.2.

[0022] 1 L of solution, 60 g of calcium carbonate, and 0.05 mol / L sulfuric acid activator were added to a sealed reactor. The reactor was heated to 40 °C and stirred for 2 h. After the reaction, the slurry was filtered, and the filter residue was lead slag, with lead, zinc, and copper content of 62.17%, 0.37%, and 0.09% by mass, respectively. The filtrate was mixed with a certain amount of calcium hydroxide and pulped. The pulped material was then added to the reactor, heated to 70 °C, and stirred for 1 h. The final pH was 10. After the reaction, the slurry was filtered, and the filter residue was zinc and copper slag, with zinc, copper, and lead content of 36.21%, 7.24%, and 1.13% by mass, respectively. The filtrate containing calcium acetate was added to the reactor along with sulfuric acid solution diluted to a 10% mass concentration. The calcium acetate reacted with the sulfuric acid to produce calcium sulfate and simultaneously regenerated acetic acid. After the reaction, the slurry was filtered, and the filtrate was regenerated acetic acid solution, which could be reused. The gypsum slag was stockpiled for further processing. Example 3

[0023] A method for separating lead from zinc and copper in an acetate solution containing lead, zinc, and copper. The composition of the acetate solution containing lead, zinc, and copper (g / L) is: Pb 54.3, Zn 33.8, Cu 9.4, Ca 12.1, HAc 6.2.

[0024] 1 L of acetate solution, 50 g of calcium carbonate, 0.1 mol / L acetic acid as an activator, and 0.1 mol / L nitric acid as an activator were added to a sealed reactor. The reactor was heated to 50 °C and stirred for 1 h. After the reaction, the slurry was filtered, and the filter residue was lead slag, with lead, zinc, and copper content of 66.29%, 1.76%, and 0.32% by mass, respectively. A certain amount of calcium hydroxide was added to the filtrate for pulping. The pulped material was then added to the reactor, heated to 80 °C, and stirred for 2 h. The final pH was 9.8. After the reaction, the slurry was filtered, and the filter residue was zinc and copper slag, with zinc, copper, and lead content of 44.15%, 12.01%, and 0.37% by mass, respectively. The filtrate containing calcium acetate and a sulfuric acid solution diluted to a mass concentration of 10% are added to the reactor. The calcium acetate reacts with the sulfuric acid to produce calcium sulfate and simultaneously regenerate acetic acid. After the reaction is completed, the slurry is filtered, and the filtrate is a regenerated acetic acid solution that can be reused. The gypsum residue is stockpiled for further treatment. Example 4

[0025] A method for separating lead from zinc and copper in an acetate solution containing lead, zinc, and copper. The composition of the acetate solution containing lead, zinc, and copper is (g / L): Pb 120.2, Zn 14.1, Cu 1.9, Ca 9.4, HAc 5.4.

[0026] 1 L of acetate solution, 80 g of calcium carbonate, 0.1 mol / L sulfuric acid as an activator, and 0.2 mol / L nitric acid as an activator were added to a sealed reactor. The reactor was heated to 30 °C and stirred for 2 h. After the reaction, the slurry was filtered, and the filter residue was lead slag, with lead, zinc, and copper content of 68.89%, 0.58%, and 0.03% by mass, respectively. A certain amount of calcium hydroxide was added to the filtrate for slurry formation. The slurry was then added to the reactor, heated to 50 °C, and stirred for 2 h. The final pH was 10.5. After the reaction, the slurry was filtered, and the filter residue was zinc and copper slag, with zinc, copper, and lead content of 38.33%, 4.95%, and 1.5% by mass, respectively. The filtrate containing calcium acetate was added to the reactor along with sulfuric acid solution diluted to a 10% mass concentration. The calcium acetate reacted with the sulfuric acid to produce calcium sulfate and simultaneously regenerated acetic acid. After the reaction, the slurry was filtered, and the filtrate was regenerated acetic acid solution, which could be reused. The gypsum slag was stockpiled for further processing.

[0027] Those skilled in the art should understand that the above embodiments are only some embodiments of the present invention, and not all embodiments based on the scope of protection of the claims of the present invention, nor are they a limitation on the scope of protection of the present invention. All omissions, modifications, and equivalent substitutions made based on the claims of the present invention should be included within the scope of protection of the present invention.

Claims

1. A method for separating lead from zinc and copper in an acetate system, characterized in that, Includes the following steps: (1) Sinking lead: A solution of acetate containing lead, zinc, and copper is mixed with calcium carbonate and an activator to form a slurry. The slurry is then added to a reaction vessel, heated to 20-150 °C, and stirred for 0.5-5 h. After the reaction is complete, the slurry is filtered, and the filter residue is lead slag, while the filtrate is lead precipitation solution. The amount of calcium carbonate added is 1 to 2 times the theoretical amount of calcium carbonate consumed by lead in the solution; the activator is one or more of nitric acid, hydrochloric acid, sulfuric acid, phosphoric acid, sulfur dioxide, nitrogen dioxide, and phosphorus pentoxide, and the concentration of the activator is 0.05 to 1 mol / L; (2) Zinc and copper immersion: The lead precipitation solution in step (1) is mixed with calcium hydroxide and slurried. Then the slurried material is added to the reaction vessel, heated to 10~100 ℃, stirred and reacted for 0.5~4 h, and the final pH is 7~11. After the reaction is completed, the slurry is filtered. The filter residue is zinc and copper slag, and the filtrate is zinc and copper precipitation solution containing calcium acetate. The amount of calcium hydroxide added is 1 to 2 times the theoretical amount of calcium hydroxide consumed by zinc and copper; (3) Regenerated acetic acid: Add the zinc and copper precipitate solution from step (2) into the reactor, add the sulfuric acid solution into the reactor, and the calcium acetate reacts with the sulfuric acid to generate calcium sulfate and regenerate acetic acid. After the reaction is completed, the slurry is filtered, and the filtrate is the regenerated acetic acid solution, which is returned to step (1) for lead precipitation. The gypsum slag is stored for further treatment.

2. The method for separating lead from zinc and copper in an acetate system according to claim 1, characterized in that, The acetate solution containing lead, zinc, and copper is obtained by directly leaching high-silica oxide ores using acetic acid and acetates as leaching agents.

3. The method for separating lead from zinc and copper in an acetate system according to claim 1, characterized in that, The acetate solution containing lead, zinc, and copper is obtained by first converting lead sulfate to lead carbonate from the wet zinc-lead-silver slag using carbonates, and then leaching it with acetic acid and acetates as leaching agents.

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