A method for recovering lead from lead sulfate waste

Abstract

The present invention provides a method for recovering lead from lead sulfate waste, comprising: (1) mixing the lead sulfate waste, magnesium salt and water to form a slurry, then adding the slurry to a closed reactor, introducing carbon dioxide gas, heating, stirring, and filtering after the reaction to obtain a magnesium sulfate filtrate and a lead carbonate residue; the magnesium salt is one or more of magnesium oxide, magnesium hydroxide, magnesium carbonate, basic magnesium carbonate, and magnesium bicarbonate solution; (2) adding a fluorosilicic acid solution to the lead carbonate residue to obtain a lead fluorosilicate solution, electrolyzing the lead fluorosilicate solution to obtain electrolytic lead and electrolytic waste liquid; (3) adding calcium hydroxide to the magnesium sulfate filtrate, heating, stirring, and filtering after the reaction, and performing beneficiation and classification of the mixed residue through a hydrocyclone to obtain a light material mainly composed of magnesium hydroxide and a heavy material mainly composed of calcium sulfate. Compared with the prior art, the present invention has low cost, no wastewater generation, and good environmental benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of lead regeneration, in particular to a method for recovering lead from lead sulfate waste. Background Art

[0002] As domestic rich ore resources continue to decline, the development and utilization of medium- and low-grade minerals and complex metal-related ores is increasing. Consequently, lead content in various concentrates is increasing. Because lead is volatile and insoluble in sulfuric acid solutions, it is mostly concentrated in smelting tailings, such as acid leaching residue from hydrometallurgical zinc smelting. Furthermore, lead-acid batteries, due to their low price and reliability, are widely used in industries such as automotive, electric vehicles, power generation, and UPS systems. According to statistics, China's refined lead production will reach 7.564 million tons in 2023, with approximately 80% used in lead-acid battery manufacturing. Consequently, a large number of lead-acid batteries are scrapped annually. Therefore, these waste materials are an important source of recycled lead.

[0003] These waste materials contain large amounts of lead sulfate, which is difficult to process. The most mature treatment process is pyrometallurgy: the waste is directly fed into a furnace as lead smelting raw material, where it is smelted to produce metallic lead. Depending on the type of smelting furnace, pyrometallurgy processes include blast furnace, Kivset, top-blown sinking smelting, QSL, Kaldor furnace, Noranda, and Shuikoushan. Pyrometallurgy offers advantages such as high throughput, ease of operation, recovery of rare and precious metals, and mature technology. However, it also presents challenges such as high energy consumption, lead volatilization losses, and severe environmental pollution.

[0004] For the long-term development of the secondary lead industry, wet treatment processes are gaining attention. Wet treatment processes generally transform difficult-to-treat lead sulfate into easily treatable lead carbonate and lead oxide, then leach the lead into a solution for lead recovery. Commonly used agents for lead sulfate conversion include sodium carbonate, ammonium carbonate, sodium bicarbonate, ammonium bicarbonate, ammonia, sodium hydroxide, and chloride salts. However, these agents are relatively expensive, and they also generate large volumes of sodium sulfate or ammonium sulfate wastewater, making it difficult to handle. Chloride salts can corrode equipment, leading to high costs. Summary of the Invention

[0005] Based on this, the object of the present invention is to provide a method for recovering lead from lead sulfate waste.

[0006] The present invention provides a method for recovering lead from lead sulfate waste, comprising the following steps:

[0007] (1) mixing the lead sulfate waste material, magnesium salt and water to form a slurry, wherein the mass ratio of the water volume to the lead sulfate waste material and the magnesium salt is (2-10):1, then adding the slurried material into a closed reactor, introducing carbon dioxide gas, heating and stirring, and filtering after the reaction to obtain a magnesium sulfate filtrate and a lead carbonate residue; the magnesium salt is one or more of magnesium oxide, magnesium hydroxide, magnesium carbonate, basic magnesium carbonate, and magnesium bicarbonate solution;

[0008] (2) adding a fluorosilicic acid solution to the lead carbonate filter residue to react and obtain a lead fluorosilicate solution, and electrolyzing the lead fluorosilicate solution to obtain electrolytic lead and electrolytic waste liquid;

[0009] (3) adding calcium hydroxide to the magnesium sulfate filtrate, heating and stirring, filtering after the reaction is completed, and performing mineral separation and classification on the mixed slag by a hydrocyclone to obtain light materials mainly composed of magnesium hydroxide and heavy materials mainly composed of calcium sulfate.

[0010] In one embodiment, in step (1), the lead sulfate waste, magnesium salt, activator and water are mixed together to form a slurry, and the activator is one or more of acetate and ethylenediamine diacetate, or one or more of methylamine, ethylamine, ethylenediamine, propylenediamine and amino acid.

[0011] In one embodiment, the acetate is one or more of sodium acetate, potassium acetate, ammonium acetate, and magnesium acetate.

[0012] In one embodiment, the EDTA salt is one or more of sodium EDTA, potassium EDTA, ammonium EDTA, and magnesium EDTA.

[0013] In one embodiment, the concentration of the activator is 0.1-3 mol / L, and the mass ratio of the volume of the activator and water to the lead sulfate waste and magnesium salt is (2-10):1.

[0014] In one embodiment, in step (1), the pressure of carbon dioxide in the reactor is 0.1-1.5 MPa, the temperature is raised to 10-100° C., and the reaction is stirred for 0.5-5 h.

[0015] In one embodiment, in step (3), the amount of calcium hydroxide added is 1 to 1.5 times the theoretical amount, the temperature is raised to 10 to 100° C., and the reaction is stirred for 0.5 to 5 hours.

[0016] In one embodiment, in step (3), the inlet pressure of the hydrocyclone is 0.11-0.3 MPa, and the volume flow ratio of the overflow outlet and the underflow outlet is 2-10:1.

[0017] In one embodiment, the method further includes returning the electrolytic waste liquid obtained in step (2) to step (2) for recycling.

[0018] In one embodiment, the method further includes returning the light material obtained in step (3) to step (1) for recycling.

[0019] The beneficial effects of the present invention are:

[0020] (1) Compared with the conversion agent of the prior art, the present invention adopts low-cost magnesium salt, and the process does not require expensive high-purity magnesium salt. The magnesium salt used can be light-burned magnesium oxide, magnesium hydroxide, basic magnesium carbonate, etc. containing impurities, and the raw material source is wide and the price is cheap.

[0021] (2) The electrolytic waste liquid of the present invention can be used sequentially to leach lead, the light material after the magnesium sulfate filtrate treatment can be returned to the lead sulfate transformation section for use as a transformation agent, and the heavy material can be sold as a product, without generating wastewater, and having good environmental benefits.

[0022] (3) The present invention adds an activator as a lead complexing agent, which can increase the solubility of lead sulfate in the solution and greatly improve the lead sulfate transformation rate and transformation rate. DETAILED DESCRIPTION

[0023] In order to further understand the present invention, preferred embodiments of the present invention are described below in conjunction with examples. However, it should be understood that these descriptions are only for further illustrating the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0024] In view of the problems of high cost, large amount of waste liquid generated, and difficult waste liquid treatment in existing wet treatment processes, the present invention adopts low-cost magnesium salt as a transformation agent, introduces carbon dioxide into a closed kettle, and transforms the magnesium salt into a magnesium bicarbonate solution first, and then reacts lead sulfate with magnesium bicarbonate to generate lead carbonate and magnesium sulfate solution. After the transformation, the magnesium sulfate filtrate obtained by filtration is added with calcium hydroxide to obtain a mixed slag of calcium sulfate, magnesium hydroxide and magnesium carbonate. The mixed slag can be separated into light materials mainly composed of magnesium hydroxide and heavy materials mainly composed of calcium sulfate by a hydrocyclone. The light materials can be returned to the lead sulfate transformation section for use as a transformation agent, and the heavy materials can be sold as products.

[0025] Specifically, the method for recovering lead from lead sulfate waste of the present invention comprises the following steps:

[0026] (1) Lead sulfate waste, magnesium salt and water are mixed to form a slurry, wherein the volume ratio of water to the mass ratio of lead sulfate waste and magnesium salt is (2-10):1, and then the slurried materials are added to a closed reactor, carbon dioxide gas is introduced, the temperature is increased, and stirring is performed. After the reaction is completed, the mixture is filtered to obtain magnesium sulfate filtrate and lead carbonate filter residue.

[0027] The lead sulfate waste refers to waste containing lead sulfate, including but not limited to lead sulfate leaching residue from hydrometallurgical zinc smelting, lead mud from copper pyrometallurgy, white smoke from copper pyrometallurgy, and lead paste from lead-acid batteries. The magnesium salt is one or more of magnesium oxide, magnesium hydroxide, magnesium carbonate, basic magnesium carbonate, and magnesium bicarbonate solution. The magnesium salt reacts with carbon dioxide to form magnesium bicarbonate, which in turn reacts with lead sulfate to form lead carbonate and magnesium sulfate. The reaction equation is as follows:

[0028] MgO+2CO2+H2O=Mg(HCO3)2

[0029] Mg(OH)2+2CO2=Mg(HCO3)2

[0030] Mg2(OH)2CO3+3CO2+H2O=2Mg(HCO3)2

[0031] Mg(HCO3)2+PbSO4=MgSO4+PbCO3+CO2+H2O

[0032] Therefore, the present invention uses a low-cost magnesium salt as a conversion agent to convert difficult-to-treat lead sulfate into easily treatable lead carbonate. When the magnesium salt is a magnesium carbonate or magnesium bicarbonate solution, the introduction of carbon dioxide gas into the reactor is unnecessary. Preferably, the amount of magnesium salt added is 1 to 3 times the theoretical amount of magnesium salt consumed by lead sulfate.

[0033] In order to reduce the amount of magnesium salt added and improve the transformation rate of lead sulfate, an activator is added during the reaction of lead sulfate and magnesium bicarbonate. The complex reaction between the activator and lead sulfate is utilized to increase the solubility of lead sulfate in the solution, so that the original liquid-solid reaction is changed to a liquid-liquid reaction, thereby greatly improving the reaction rate and transformation rate of lead sulfate and magnesium bicarbonate.

[0034] Specifically, lead sulfate waste, magnesium salt, activator and water are mixed together to form a slurry. The activator is one or more of acetate and ethylenediamine diacetate, or one or more of methylamine, ethylamine, ethylenediamine, propylenediamine and amino acid. The acetate is one or more of sodium acetate, potassium acetate, ammonium acetate and magnesium acetate. The ethylenediamine diacetate is one or more of sodium ethylenediamine diacetate, potassium ethylenediamine diacetate, ammonium ethylenediamine diacetate and magnesium ethylenediamine diacetate. The concentration of the activator is 0.1 to 3 mol / L, and the mass ratio of the volume of the activator and water to the lead sulfate waste and magnesium salt is (2 to 10):1.

[0035] Preferably, the pressure of carbon dioxide in the reactor is 0.1-1.5 MPa, the temperature is raised to 10-100° C., and the reaction is stirred for 0.5-5 h.

[0036] (2) adding a fluorosilicic acid solution to the lead carbonate filter residue to react and obtain a lead fluorosilicate solution, and electrolyzing the lead fluorosilicate solution to obtain electrolytic lead and electrolytic waste liquid.

[0037] This step utilizes established lead fluorosilicate electrolysis technology. The electrolysis wastewater can be recycled and reacted with the magnesium sulfate filter residue to produce a lead fluorosilicate solution. When the lead sulfate waste material is lead paste from lead-acid batteries, fluorosilicic acid and hydrogen peroxide are added to the lead carbonate filter residue, with the amount of hydrogen peroxide added being 1.1 to 2 times the theoretical amount. The hydrogen peroxide is used to reduce the lead dioxide in the residue to lead oxide.

[0038] (3) adding calcium hydroxide to the magnesium sulfate filtrate, heating and stirring, filtering after the reaction is completed, and performing mineral separation and classification on the mixed slag by a hydrocyclone to obtain light materials mainly composed of magnesium hydroxide and heavy materials mainly composed of calcium sulfate.

[0039] Among them, in addition to the main component magnesium sulfate, the magnesium sulfate filtrate also contains a small amount of magnesium bicarbonate. Adding calcium hydroxide to the magnesium carbonate filtrate can precipitate magnesium sulfate and magnesium bicarbonate to obtain a mixed slag of calcium sulfate, magnesium hydroxide and magnesium carbonate. Among them, magnesium hydroxide and magnesium carbonate are highly hydrophilic, have fine particle size and are light in weight, while calcium sulfate is easy to stick, has coarse particles and is relatively heavy in weight. Based on this difference, the mixed slag can be separated into light materials mainly composed of magnesium hydroxide and heavy materials mainly composed of calcium sulfate through a hydrocyclone. The light materials can be returned to the lead sulfate transformation section for use as a transformation agent, and the heavy materials can be sold as products. The reaction equation is as follows:

[0040] Mg(HCO3)2+Ca(OH)2=MgCO3+2H2O+CaCO3

[0041] MgSO4+Ca(OH)2=Mg(OH)2+CaSO4

[0042] Preferably, the amount of calcium hydroxide added is 1 to 1.5 times the theoretical amount, the temperature is raised to 10 to 100° C., and the reaction is stirred for 0.5 to 5 hours.

[0043] Preferably, the inlet pressure of the hydrocyclone is 0.11-0.3 MPa, and the volume flow ratio of the overflow outlet and the underflow outlet is 2-10:1.

[0044] In order to further understand the present invention, the method for recovering lead from lead sulfate waste provided by the present invention is described in detail below with reference to the embodiments, and the protection scope of the present invention is not limited by the following embodiments.

[0045] Example 1

[0046] This embodiment recovers lead from lead sulfate leaching residue (main components by weight percentage are 31.81% Pb, 2.16% Zn and 5.52% S) from hydrometallurgical zinc smelting, comprising the following steps:

[0047] (1) The lead sulfate leaching residue, light-burned magnesium oxide and water are mixed and slurried. The light-burned magnesium oxide is 1.2 times the theoretical amount, and the mass ratio of the volume of water to the lead sulfate leaching residue and light-burned magnesium oxide is 4:1 (unit: mL / g). The slurried material is added to a closed reactor, and carbon dioxide gas is introduced. The pressure in the reactor is maintained at 0.3 MPa, and stirring is started for 1 hour at a temperature of 40°C. After the reaction is completed, vacuum filtration is performed to obtain magnesium sulfate filtrate and lead carbonate residue.

[0048] (2) adding a fluorosilicic acid solution to the magnesium sulfate filter residue to react and obtain a lead fluorosilicate solution; purifying the lead fluorosilicate solution and then electrolyzing it to obtain 99.93% electrolytic lead.

[0049] (3) The magnesium sulfate filtrate is added to a reactor, and 1.1 times the theoretical amount of calcium hydroxide is added. The temperature is raised to 40° C. and stirred for reaction for 2 hours. The mixed slag obtained by the reaction is passed through a hydrocyclone for beneficiation and classification. The inlet pressure of the hydrocyclone is controlled at 0.15 MPa, and the volume flow ratio of the overflow port and the underflow port is controlled at 4:1 to obtain a light material with a magnesium hydroxide mass percentage of 86.47% and a heavy material with a calcium sulfate mass percentage of 94.21%.

[0050] Example 2

[0051] This embodiment recovers lead from lead sulfate leaching residue (main components by weight percentage are 31.81% Pb, 2.16% Zn and 5.52% S) from hydrometallurgical zinc smelting, comprising the following steps:

[0052] (1) The lead sulfate leaching residue, light-burned magnesium oxide and ethylenediamine are mixed and slurried. The light-burned magnesium oxide is 1.2 times the theoretical amount, the concentration of the ethylenediamine solution is 0.3 mol / L, and the mass ratio of the volume of the ethylenediamine solution to the lead sulfate leaching residue and the light-burned magnesium oxide is 4:1 (unit: mL / g). The slurried material is added to a closed reactor, carbon dioxide gas is introduced, the pressure in the reactor is maintained at 0.3 MPa, stirring is started, the time is 40 minutes, and the temperature is 40°C. After the reaction is completed, vacuum filtration is performed to obtain magnesium sulfate filtrate and lead carbonate residue.

[0053] (2) adding a fluorosilicic acid solution to the magnesium sulfate filter residue to react and obtain a lead fluorosilicate solution; purifying the lead fluorosilicate solution and then electrolyzing it to obtain 99.94% electrolytic lead.

[0054] (3) The magnesium sulfate filtrate is added to a reactor, and 1.1 times the theoretical amount of calcium hydroxide is added. The temperature is raised to 40° C. and stirred for reaction for 2 hours. The mixed slag obtained by the reaction is passed through a hydrocyclone for beneficiation and classification. The inlet pressure of the hydrocyclone is controlled at 0.15 MPa, and the volume flow ratio of the overflow port and the underflow port is controlled at 4:1 to obtain a light material with a magnesium hydroxide mass percentage of 86.28% and a heavy material with a calcium sulfate mass percentage of 95.05%.

[0055] Example 3

[0056] This embodiment recovers lead from copper pyrometallurgical lead mud (main components by weight percentage are 52.86% Pb, 2.03% Cu, 4.36% Se, 5.69% Sn, 1.82% Bi, 0.76% Hg, and 711.7% Ag / (g / t)), comprising the following steps:

[0057] (1) The copper pyrometallurgical lead mud, magnesium hydroxide and sodium acetate solution are mixed and slurried. The magnesium hydroxide is 1.3 times the theoretical amount, the concentration of the sodium acetate solution is 1 mol / L, and the mass ratio of the sodium acetate solution to the copper pyrometallurgical lead mud and magnesium hydroxide is 5:1 (unit: mL / g). The slurried material is added to a closed reactor, carbon dioxide gas is introduced, the pressure in the reactor is maintained at 0.8 MPa, stirring is started, the time is 2 hours, and the temperature is 60°C. After the reaction is completed, vacuum filtration is performed to obtain magnesium sulfate filtrate and lead carbonate residue.

[0058] (2) adding a fluorosilicic acid solution to the magnesium sulfate filter residue to react and obtain a lead fluorosilicate solution; purifying the lead fluorosilicate solution and then electrolyzing it to obtain 99.95% electrolytic lead.

[0059] (3) The magnesium sulfate filtrate is added to a reactor, and 1.2 times the theoretical amount of calcium hydroxide is added. The reaction is stirred at room temperature for 2 hours. The mixed slag obtained by the reaction is passed through a hydrocyclone for mineral processing and classification. The inlet pressure of the hydrocyclone is controlled at 0.18 MPa, and the volume flow rate ratio of the overflow port and the underflow port is controlled at 3:1 to obtain a light material with a magnesium hydroxide mass percentage of 89.13% and a heavy material with a calcium sulfate mass percentage of 95.87%.

[0060] Example 4

[0061] This embodiment recovers lead from waste lead paste of lead-acid batteries (the main components are 74.18% Pb, 0.96% Al, 1.43% Fe, and 0.71% Ba by weight, and the lead phases are 55.12% PbSO4, 14.26% PbO, 27.91% PbO2, and 2.71% Pb by weight), comprising the following steps:

[0062] (1) The lead-acid battery waste lead paste, light-burned magnesium oxide and sodium acetate solution are mixed and slurried. The light-burned magnesium oxide is 1.3 times the theoretical amount, the concentration of the sodium acetate solution is 1 mol / L, and the mass ratio of the volume of the sodium acetate solution to the lead-acid battery waste lead paste and the light-burned magnesium oxide is 10:1 (unit: mL / g). The slurried material is added to a closed reactor, carbon dioxide gas is introduced, the pressure in the reactor is maintained at 0.3 MPa, and stirring is started for 4 hours at room temperature. After the reaction is completed, vacuum filtration is performed to obtain magnesium sulfate filtrate and lead carbonate filter residue.

[0063] (2) adding a fluorosilicic acid solution to the magnesium sulfate filter residue and simultaneously adding hydrogen peroxide to reduce lead dioxide to obtain a lead fluorosilicate solution, purifying the lead fluorosilicate solution and then electrolyzing it to obtain 99.95% electrolytic lead.

[0064] (3) The magnesium sulfate filtrate is added to a reactor, and 1.3 times the theoretical amount of calcium hydroxide is added. The reaction is stirred at room temperature for 1 hour. The mixed slag obtained by the reaction is passed through a hydrocyclone for mineral processing and classification. The inlet pressure of the hydrocyclone is controlled at 0.14 MPa, and the volume flow ratio of the overflow port and the underflow port is controlled at 5:1 to obtain a light material with a magnesium hydroxide mass percentage of 86.38% and a heavy material with a calcium sulfate mass percentage of 95.67%.

[0065] Example 5

[0066] This embodiment recovers lead from waste lead paste of lead-acid batteries (the main components are 74.18% Pb, 0.96% Al, 1.43% Fe, and 0.71% Ba by weight, and the lead phases are 55.12% PbSO4, 14.26% PbO, 27.91% PbO2, and 2.71% Pb by weight), comprising the following steps:

[0067] (1) The waste lead paste of the lead-acid battery, light-burned magnesium oxide and sodium acetate solution are mixed and slurried. The light-burned magnesium oxide is 1.8 times the theoretical amount, the concentration of the sodium acetate solution is 3 mol / L, and the mass ratio of the volume of the sodium acetate solution to the waste lead paste of the lead-acid battery and the light-burned magnesium oxide is 4:1 (unit: mL / g). The slurried material is added to a closed reactor, and carbon dioxide gas is introduced. The pressure in the reactor is maintained at 0.3 MPa, and stirring is started for 2 hours at a temperature of 60°C. After the reaction is completed, vacuum filtration is performed to obtain magnesium sulfate filtrate and lead carbonate residue.

[0068] (2) adding a fluorosilicic acid solution to the magnesium sulfate filter residue and simultaneously adding hydrogen peroxide to reduce lead dioxide to obtain a lead fluorosilicate solution, purifying the lead fluorosilicate solution and then electrolyzing it to obtain 99.95% electrolytic lead.

[0069] (3) The magnesium sulfate filtrate is added to a reactor, and 1.1 times the theoretical amount of calcium hydroxide is added. The temperature is 60° C. and the reaction is stirred for 4 hours. The mixed slag obtained by the reaction is passed through a hydrocyclone for mineral processing and classification. The inlet pressure of the hydrocyclone is controlled at 0.17 MPa, and the volume flow rate ratio of the overflow port and the underflow port is controlled at 4:1 to obtain a light material with a magnesium hydroxide mass percentage of 88.69% and a heavy material with a calcium sulfate mass percentage of 96.81%.

[0070] Comparative Example 1

[0071] This comparative example recovers lead from lead sulfate leaching residue (main components by weight percentage: 31.81% Pb, 2.16% Zn, and 5.52% S) from hydrometallurgical zinc smelting, comprising the following steps:

[0072] (1) The lead sulfate leaching residue, light-burned magnesium oxide and water are mixed and slurried. The light-burned magnesium oxide is 1.2 times the theoretical amount, and the mass ratio of the volume of water to the lead sulfate leaching residue and light-burned magnesium oxide is 1.2:1 (unit: mL / g). The slurried material is added to a closed reactor, and carbon dioxide gas is introduced. The pressure in the reactor is maintained at 0.3 MPa, and stirring is started for 1 hour at a temperature of 40°C. After the reaction is completed, vacuum filtration is performed to obtain magnesium sulfate filtrate and lead carbonate residue.

[0073] (2) adding a fluorosilicic acid solution to the magnesium sulfate filter residue to react and obtain a lead fluorosilicate solution; purifying the lead fluorosilicate solution and then electrolyzing it to obtain 99.91% electrolytic lead.

[0074] (3) The magnesium sulfate filtrate is added to a reactor, and 1.1 times the theoretical amount of calcium hydroxide is added. The temperature is raised to 40° C. and stirred for reaction for 2 hours. The mixed slag obtained by the reaction is passed through a hydrocyclone for beneficiation and classification. The inlet pressure of the hydrocyclone is controlled at 0.15 MPa, and the volume flow rate ratio of the overflow port and the underflow port is controlled at 4:1 to obtain a light material with a magnesium hydroxide mass percentage of 82.35% and a heavy material with a calcium sulfate mass percentage of 94.21%.

[0075] Comparative Example 2

[0076] This comparative example recovers lead from lead sulfate leaching residue (main components by weight percentage: 31.81% Pb, 2.16% Zn, and 5.52% S) from hydrometallurgical zinc smelting, comprising the following steps:

[0077] (1) The lead sulfate leaching residue, light-burned magnesium oxide and water are mixed and slurried. The light-burned magnesium oxide is 1.2 times the theoretical amount, and the mass ratio of the volume of water to the lead sulfate leaching residue and light-burned magnesium oxide is 15:1 (unit: mL / g). The slurried material is added to a closed reactor, and carbon dioxide gas is introduced. The pressure in the reactor is maintained at 0.3 MPa, and stirring is started for 1 hour at a temperature of 40°C. After the reaction is completed, vacuum filtration is performed to obtain magnesium sulfate filtrate and lead carbonate residue.

[0078] (2) adding a fluorosilicic acid solution to the magnesium sulfate filter residue to react and obtain a lead fluorosilicate solution; purifying the lead fluorosilicate solution and then electrolyzing it to obtain 99.95% electrolytic lead.

[0079] (3) The magnesium sulfate filtrate is added to a reactor, and 1.1 times the theoretical amount of calcium hydroxide is added. The temperature is raised to 40° C. and stirred for reaction for 2 hours. The mixed slag obtained by the reaction is passed through a hydrocyclone for beneficiation and classification. The inlet pressure of the hydrocyclone is controlled at 0.15 MPa, and the volume flow ratio of the overflow port and the underflow port is controlled at 4:1 to obtain a light material with a magnesium hydroxide content of 86.12% by mass and a heavy material with a calcium sulfate content of 93.85% by mass.

[0080] The lead sulfate conversion rate and lead recovery rate of Examples 1-5 and Comparative Examples 1-2 were calculated using the following calculation formula. The results are shown in Table 1.

[0081] Lead sulfate conversion rate:

[0082] Where:

[0083] η——lead sulfate transformation rate, unit %;

[0084] m1——mass of lead sulfate waste, unit: g;

[0085] m2——mass of transformation slag, unit: g;

[0086] ω1——the content of lead sulfate in lead sulfate waste, unit %;

[0087] ω2——the content of lead sulfate in the transformation slag, unit %;

[0088] Lead recovery rate:

[0089] Where:

[0090] α——lead recovery rate, unit %;

[0091] m1——mass of lead sulfate waste, unit: g;

[0092] m2——mass of transformation slag, unit: g;

[0093] β1——lead content in lead sulfate waste, unit %;

[0094] β2——lead content in silicofluoric acid leaching residue, unit: %.

[0095] Table 1 Transformation rate of lead sulfate and lead recovery rate

[0096] Transformation rate of lead sulfate Lead recovery rate Example 1 96.44％ 94.21％ Example 2 98.25％ 97.89％. Example 3 98.63％ 97.97％ Example 4 98.93％ 98.29％ Example 5 99.13％ 98.65％ Comparative Example 1 85.46％ 83.55％ Comparative Example 2 90.35％ 89.03％

[0097] As shown in Table 1, the lead sulfate conversion rates of Examples 1-5 of the present invention are all above 96%, and the lead recovery rates are all above 94%. Therefore, the method for recovering lead from lead sulfate waste of the present invention can achieve excellent recovery results.

[0098] Compared with Example 1, the addition of an activator in Example 2 improved both the lead sulfate conversion rate and the lead recovery rate. Furthermore, compared with the 1 hour reaction time for lead sulfate conversion in Example 1, Example 2 only required 40 minutes to complete the reaction, and the conversion rate was also improved compared to Example 1. Therefore, the addition of an activator in the present invention can increase the rate and conversion rate of lead sulfate conversion.

[0099] In Comparative Example 1, the mass ratio of water volume to lead sulfate leaching residue and light-burned magnesium oxide is less than the limit of the present invention (2-10): 1, and the lead sulfate transformation rate is lower than that of Examples 1-5. This is mainly because the material after slurrying is too viscous, which is not conducive to the lead sulfate transformation reaction. In Comparative Example 2, the mass ratio of water volume to lead sulfate leaching residue and light-burned magnesium oxide is greater than the limit of the present invention (2-10): 1, and the lead sulfate transformation rate is also lower than that of Examples 1-5. This is mainly because the concentration of bicarbonate in the material after slurrying is reduced. Therefore, in the present invention, the mass ratio of water volume to lead sulfate waste and magnesium salt is (2-10): 1, which can achieve a higher lead sulfate transformation rate.

[0100] The technical features of the above-mentioned embodiments can be combined arbitrarily. In order to make the description concise, not all possible combinations of the technical features in the above-mentioned embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0101] The above-described embodiments merely represent several 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 application. 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 lead from lead sulfate waste, characterized in that, The following steps are involved: (1) mixing the lead sulfate waste, magnesium salt, activator and water to form a slurry, wherein the mass ratio of water volume to lead sulfate waste and magnesium salt is (2-10):1, in units of mL / g; then adding the slurried material into a closed reactor, introducing carbon dioxide gas, heating, stirring, and filtering after the reaction to obtain magnesium sulfate filtrate and lead carbonate residue; the magnesium salt is one or more of magnesium oxide, magnesium hydroxide, magnesium carbonate, basic magnesium carbonate, and magnesium bicarbonate solution; the activator is one or more of acetate and ethylenediamine diacetate, or one or more of methylamine, ethylamine, ethylenediamine, propylenediamine, and amino acid; (2) adding a fluorosilicic acid solution to the lead carbonate filter residue to react and obtain a lead fluorosilicate solution, and electrolyzing the lead fluorosilicate solution to obtain electrolytic lead and electrolytic waste liquid; (3) adding calcium hydroxide to the magnesium sulfate filtrate, heating and stirring, filtering after the reaction is completed, and performing mineral separation and classification on the mixed slag by a hydrocyclone to obtain light materials mainly composed of magnesium hydroxide and heavy materials mainly composed of calcium sulfate.

2. The method for recovering lead from lead sulfate waste according to claim 1, wherein The acetate is one or more of sodium acetate, potassium acetate, ammonium acetate, and magnesium acetate.

3. The method for recovering lead from lead sulfate waste according to claim 1, wherein The ethylenediaminediacetate salt is one or more of sodium ethylenediaminediacetate, potassium ethylenediaminediacetate, ammonium ethylenediaminediacetate, and magnesium ethylenediaminediacetate.

4. The method for recovering lead from lead sulfate waste according to claim 1, wherein The concentration of the activator is 0.1-3 mol / L.

5. The method for recovering lead from lead sulfate waste according to any one of claims 1 to 4, wherein: In step (1), the pressure of carbon dioxide in the reactor is 0.1-1.5 MPa, the temperature is raised to 10-100° C., and the reaction is stirred for 0.5-5 h.

6. The method for recovering lead from lead sulfate waste according to any one of claims 1 to 4, characterized in that: In step (3), the amount of calcium hydroxide added is 1 to 1.5 times the theoretical amount, the temperature is raised to 10 to 100° C., and the reaction is stirred for 0.5 to 5 hours.

7. The method for recovering lead from lead sulfate waste according to any one of claims 1 to 4, characterized in that: In step (3), the inlet pressure of the hydrocyclone is 0.11-0.3 MPa, and the volume flow ratio of the overflow outlet and the underflow outlet is 2-10:

1.

8. The method for recovering lead from lead sulfate waste according to any one of claims 1 to 4, characterized in that: Also includes: The electrolytic waste liquid obtained in step (2) is returned to step (2) for recycling.

9. The method for recovering lead from lead sulfate waste according to any one of claims 1 to 4, characterized in that: Also includes: The light material obtained in step (3) is returned to step (1) for recycling.