Method for recovering lead from lead sulfate waste

Abstract

The invention provides a method for recovering lead from lead sulfate waste, which comprises the following steps: (1) mixing and slurrying the lead sulfate waste, magnesium salt and water, then adding the slurried material into a closed reaction kettle, introducing carbon dioxide gas, heating, stirring, and filtering after the reaction is finished to obtain magnesium sulfate filtrate and lead carbonate filter residue; the magnesium salt is one or more of magnesium oxide, magnesium hydroxide, magnesium carbonate, basic magnesium carbonate and a magnesium bicarbonate solution; (2) adding a fluosilicic acid solution into the lead carbonate filter residues, reacting to obtain a lead fluorosilicate solution, and electrolyzing the lead fluorosilicate solution to obtain electrolytic lead and electrolytic waste liquid; and (3) adding calcium hydroxide into the magnesium sulfate filtrate, heating, stirring, filtering after the reaction is finished, and carrying out mineral separation and classification on mixed slag through a hydrocyclone to obtain a light material mainly containing magnesium hydroxide and a heavy material mainly containing calcium sulfate. Compared with the prior art, the method is low in cost, free of wastewater and good in environmental benefit.

Description

Technical Field

[0001] The 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 decrease, medium- and low-grade minerals and complex metal associated ores are increasingly being developed and utilized, and the content of lead in various concentrates is getting higher and higher. Because lead is volatile and insoluble in sulfuric acid solution, most of the lead is enriched in smelting tailings, such as acid leaching slag from hydrometallurgical zinc smelting. At the same time, lead-acid batteries are widely used in automobiles, electric vehicles, electricity, UPS systems and other industries due to their low prices, stability and reliability. According to statistics, China's refined lead production will reach 7.564 million tons in 2023, and about 80% of refined lead will be used to manufacture lead-acid batteries. A large number of lead-acid batteries are scrapped every year. Therefore, the above waste is an important source of recycled lead.

[0003] These wastes contain a large amount of lead sulfate that is difficult to treat. The more mature treatment process is the pyrometallurgical method: the waste is directly put into the furnace as the raw material for lead smelting, and the metallic lead is smelted. According to the different smelting furnaces, the pyrometallurgical treatment process is divided into blast furnace method, Kivset method, top blowing sinking smelting method, QSL, Kaldor furnace method, Noranda method, Shuikoushan method, etc. The pyrometallurgical treatment process has the advantages of large processing capacity, simple operation, ability to recover rare and precious metals, and mature technology, but it also has problems such as high energy consumption, lead volatilization loss, and serious environmental pollution.

[0004] For the long-term development of the secondary lead industry, wet treatment technology has received attention. The wet treatment process generally transforms the difficult-to-treat lead sulfate into easy-to-treat lead carbonate and lead oxide, and then leaches the lead into the solution to recover the lead. When transforming lead sulfate, commonly used transformation agents are sodium carbonate, ammonium carbonate, sodium bicarbonate, ammonium bicarbonate, ammonia water, sodium hydroxide, chloride salts, etc. However, the prices of these transformation agents are relatively high, and there are also problems such as large amounts of sodium sulfate or ammonium sulfate waste liquid, difficulty in treatment, chloride salt corrosion equipment, and 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 volume of water 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 is completed 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 residue to 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 beneficiation and classification of the mixed slag through 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 ethylenediaminediacetate salt is one or more of ethylenediaminediacetate sodium, ethylenediaminediacetate potassium, ethylenediaminediacetate ammonium, and ethylenediaminediacetate magnesium.

[0013] In one of the embodiments, 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 port and the underflow port is 2-10:1.

[0017] In one embodiment, the method further comprises: 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 in 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 for leaching lead, the light material after the magnesium sulfate filtrate treatment can be returned to the lead sulfate transformation stage 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 increase the transformation rate and transformation rate of lead sulfate. 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 the existing wet treatment process, the present invention adopts low-cost magnesium salt as a transformation agent, and introduces carbon dioxide into a closed kettle to transform the magnesium salt into a magnesium bicarbonate solution first, and then lead sulfate reacts with magnesium bicarbonate to generate lead carbonate and magnesium sulfate solution. The magnesium sulfate filtrate obtained by filtration after transformation is added with calcium hydroxide to obtain a mixed slag of calcium sulfate, magnesium hydroxide and magnesium carbonate. The mixed slag can be divided 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 mass ratio of the volume of water to the mass of the lead sulfate waste and the magnesium salt is (2-10):1, and then the slurry is 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 a magnesium sulfate filtrate and a lead carbonate filter residue.

[0027] Among them, the lead sulfate waste is waste containing lead sulfate, including but not limited to lead sulfate leaching slag from hydrometallurgical zinc smelting, lead mud from copper pyrometallurgy, white smoke from copper pyrometallurgy, waste lead paste from lead-acid batteries, etc. 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 generate magnesium bicarbonate, and magnesium bicarbonate reacts with lead sulfate to generate lead carbonate and magnesium sulfate. The reaction equation is as follows:

[0028] MgO+2CO2 +H 2 O=Mg(HCO 3 ) 2

[0029] Mg(OH) 2 +2CO 2 =Mg(HCO 3 ) 2

[0030] Mg 2 (OH) 2 CO 3 +3CO 2 +H 2 O=2Mg(HCO 3 ) 2

[0031] Mg(HCO 3 ) 2 +PbSO 4 =MgSO 4 +PbCO 3 +CO 2 +H 2 O

[0032] Therefore, the present invention adopts low-cost magnesium salt as a conversion agent, which can convert difficult-to-treat lead sulfate into easy-to-treat lead carbonate. When the magnesium salt is magnesium carbonate or magnesium bicarbonate solution, carbon dioxide gas may not be introduced into the reactor. 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 solubility of lead sulfate in the solution is increased by the complex reaction of the activator and lead sulfate, so that the original liquid-solid reaction is changed into 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 0.1-3 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.

[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 adopts the existing mature lead fluorosilicate electrolysis technology. Among them, the electrolytic waste liquid can be recycled and reacted with the magnesium sulfate filter residue to obtain a lead fluorosilicate solution. When the lead sulfate waste material is lead-acid battery waste lead paste, fluorosilicic acid and hydrogen peroxide are added to the lead carbonate filter residue, and the amount of hydrogen peroxide added is 1.1 to 2 times the theoretical amount. The hydrogen peroxide is used to reduce the lead dioxide in the slag to lead oxide.

[0038] (3) adding calcium hydroxide to the magnesium sulfate filtrate, heating and stirring, filtering after the reaction is completed, and performing beneficiation and classification of the mixed slag through 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 has a small amount of magnesium bicarbonate remaining. 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 have strong hydrophilicity, fine particle size and light weight, while calcium sulfate is easy to stick, has coarse particles and is relatively heavy. Based on this difference, the mixed slag can be divided 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 as a transformation agent, and the heavy materials can be sold as products. The reaction equation is as follows:

[0040] Mg(HCO 3 ) 2 +Ca(OH) 2 =MgCO 3 +2H 2 O+CaCO 3

[0041] MgSO 4 +Ca(OH) 2 =Mg(OH) 2 +CaSO 4

[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 in conjunction with 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 are 31.81% Pb, 2.16% Zn and 5.52% S in weight percentage) of 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 the light-burned magnesium oxide is 4:1 (in 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 turned on, the time is 1 hour, and the temperature is 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 the reactor, 1.1 times the theoretical amount of calcium hydroxide is added, the temperature is raised to 40°C, and the reaction is stirred 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 to be 0.15MPa, and the volume flow ratio of the overflow port and the underflow port is controlled to be 4:1, and 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% are obtained.

[0050] Example 2

[0051] This embodiment recovers lead from lead sulfate leaching residue (main components are 31.81% Pb, 2.16% Zn and 5.52% S in weight percentage) of 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 (in 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 the reactor, 1.1 times the theoretical amount of calcium hydroxide is added, the temperature is raised to 40°C, and the reaction is stirred 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 to be 0.15MPa, and the volume flow ratio of the overflow port and the underflow port is controlled to be 4:1, and 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% are obtained.

[0055] Example 3

[0056] This embodiment recovers lead from copper pyrometallurgical lead mud (main components are 52.86% Pb, 2.03% Cu, 4.36% Se, 5.69% Sn, 1.82% Bi, 0.76% Hg, 711.7% Ag / (g / t) in weight percentage), 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 (in 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, and the reaction is stirred at room temperature for 2 hours. The mixed slag obtained by the reaction is passed through a hydrocyclone for beneficiation and classification, and the inlet pressure of the hydrocyclone is controlled to be 0.18 MPa, and the volume flow ratio of the overflow port and the underflow port is controlled to be 3:1, and 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% are obtained.

[0060] Example 4

[0061] In this embodiment, waste lead paste of lead-acid batteries (main components by weight percentage are 74.18% Pb, 0.96% Al, 1.43% Fe, 0.71% Ba, and each lead phase by weight percentage is: 55.12% PbSO 4 、14.26% PbO、27.91% PbO 2 , 2.71% Pb) to recover lead, comprising the following steps:

[0062] (1) The waste lead paste of the lead-acid battery, light-burned magnesium oxide and sodium acetate solution are mixed and slurried. Wherein, 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 waste lead paste of the lead-acid battery and the light-burned magnesium oxide is 10:1 (in 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 turned on, and the time is 4 hours at room temperature. After the reaction is completed, vacuum filtration is performed to obtain magnesium sulfate filtrate and lead carbonate 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, and the reaction is stirred at room temperature for 1 hour. The mixed slag obtained by the reaction is passed through a hydrocyclone for beneficiation and classification, and the inlet pressure of the hydrocyclone is controlled to be 0.14 MPa, and the volume flow ratio of the overflow port and the underflow port is controlled to be 5:1, and 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% are obtained.

[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, 0.71% Ba by weight, and the lead phases are 55.12% PbSO4, 14.26% PbO, 27.91% PbO2, 2.71% Pb by weight), comprising the following steps:

[0067] (1) The waste lead paste of lead-acid batteries, 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 lead-acid batteries and the light-burned magnesium oxide is 4:1 (in 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 turned on, 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.

[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 the 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 beneficiation and classification, the inlet pressure of the hydrocyclone is controlled to 0.17 MPa, and the volume flow ratio of the overflow port and the underflow port is controlled to 4:1, and 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% are obtained.

[0070] Comparative Example 1

[0071] This comparative example recovers lead from lead sulfate leaching residue (main components are 31.81% Pb, 2.16% Zn and 5.52% S in weight percentage) of 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 the light-burned magnesium oxide is 1.2:1 (in 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 the reactor, 1.1 times the theoretical amount of calcium hydroxide is added, the temperature is raised to 40°C, and the reaction is stirred 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 to be 0.15MPa, and the volume flow ratio of the overflow port and the underflow port is controlled to be 4:1, and 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% are obtained.

[0075] Comparative Example 2

[0076] This comparative example recovers lead from lead sulfate leaching residue (main components are 31.81% Pb, 2.16% Zn and 5.52% S in weight percentage) of 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 the light-burned magnesium oxide is 15:1 (in 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 the reactor, 1.1 times the theoretical amount of calcium hydroxide is added, the temperature is raised to 40°C, and the reaction is stirred 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 to be 0.15MPa, and the volume flow ratio of the overflow port and the underflow port is controlled to be 4:1, and 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 are obtained.

[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] m 1 ——Mass of lead sulfate waste, in g;

[0085] m 2 ——mass of transformation slag, in g;

[0086] ω 1 ——Content of lead sulfate in lead sulfate waste, unit: %;

[0087] ω 2 ——Content of lead sulfate in transformation slag, unit: %;

[0088] Lead recovery rate:

[0089] Where:

[0090] α——lead recovery rate, unit: %;

[0091] m 1 ——Mass of lead sulfate waste, in g;

[0092] m 2 ——mass of transformation slag, in g;

[0093] β 1 ——Lead content in lead sulfate waste, unit: %;

[0094] β 2 ——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 can be seen from 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 effect.

[0098] Compared with Example 1, the activator is added in Example 2, and the lead sulfate conversion rate and lead recovery rate are improved. Moreover, compared with the lead sulfate conversion reaction time of 1h in Example 1, the reaction is completed in only 40min in Example 2, and the conversion rate is also improved compared with 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 the volume of water to the lead sulfate leaching residue and the light-burned magnesium oxide is less than the limit of the present invention (2 to 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 the volume of water to the lead sulfate leaching residue and the light-burned magnesium oxide is greater than the limit of the present invention (2 to 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 slurrying material is reduced. Therefore, in the present invention, the mass ratio of the volume of water to the lead sulfate waste and magnesium salt is (2 to 10): 1, which can achieve a higher lead sulfate transformation rate.

[0100] The technical features of the above-described embodiments may be arbitrarily combined. To make the description concise, not all possible combinations of the technical features in the above-described 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-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent application. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached 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 material, magnesium salt and water to form a slurry, wherein the mass ratio of the volume of water 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 is completed 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, 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 beneficiation and classification of the mixed slag through 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, characterized in that: 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 acids.

3. The method for recovering lead from lead sulfate waste according to claim 2, characterized in that: The acetate is one or more of sodium acetate, potassium acetate, ammonium acetate and magnesium acetate.

4. The method for recovering lead from lead sulfate waste according to claim 2, characterized in that: The ethylenediaminediacetate salt is one or more of ethylenediaminediacetate sodium, ethylenediaminediacetate potassium, ethylenediaminediacetate ammonium, and ethylenediaminediacetate magnesium.

5. The method for recovering lead from lead sulfate waste according to claim 2, characterized in that: 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.

6. A method for recovering lead from lead sulfate waste according to any one of claims 1 to 5, characterized in that: 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.

7. A method for recovering lead from lead sulfate waste according to any one of claims 1 to 5, 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.

8. A method for recovering lead from lead sulfate waste according to any one of claims 1 to 5, 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.

9. The method for recovering lead from lead sulfate waste according to any one of claims 1 to 5, characterized in that: Also includes: The electrolytic waste liquid obtained in step (2) is returned to step (2) for recycling.

10. The method for recovering lead from lead sulfate waste according to any one of claims 1 to 5, characterized in that: Also includes: The light material obtained in step (3) is returned to step (1) for recycling.