A method for preparing single-crystal lead oxide from waste lead paste using a low-temperature pyrometallurgical process.

Abstract

This invention relates to a method for preparing monocrystalline lead oxide from waste lead paste using a low-temperature pyrometallurgical process, belonging to the field of resource recycling technology for waste lead-acid batteries. The invention involves removing waste positive and negative electrode plates from lead-acid batteries and washing them with water; peeling waste lead paste from the grids of the waste positive and negative electrode plates, grinding and sieving to obtain waste lead paste powder; mixing the waste lead paste powder with a desulfurizing agent, a desulfurization aid, and a crystal form control agent to obtain mixture A; calcining mixture A at 400-600℃ for 2-8 hours, followed by furnace cooling to obtain mixture B; washing and drying mixture B to obtain monocrystalline lead oxide, which is α-PbO, β-PbO, or Pb3O4. This invention directly uses waste lead paste from lead-acid batteries for a one-step low-temperature pyrometallurgical process to prepare monocrystalline lead oxide. The desulfurizing agent can directly desulfurize the waste lead paste, the desulfurization aid can lower the calcination temperature, and the crystal form control agent regulates the crystal structure of the generated lead oxide species, resulting in monocrystalline lead oxide with high purity and good crystallinity.

Description

TECHNICAL FIELD

[0001] The application relates to a method for preparing single crystal lead oxide by low-temperature fire process recovery of waste lead paste, and belongs to the technical field of resource recycling of waste lead-acid storage batteries. BACKGROUND

[0002] Lead-acid batteries play an important role in the charging battery market due to low cost, good safety performance, mature manufacturing technology and nearly 95% recovery rate, and are widely used in power transmission, uninterruptible power supply, starting power supply, energy storage system and other fields. The recycling and regeneration of waste lead-acid batteries is an important topic, which can not only effectively reduce the serious environmental problems caused by the discharge of lead-containing substances into the environment, but also has great significance for the recycling of valuable materials.

[0003] Waste lead-acid batteries, which are the largest raw material for recycled lead, are mainly composed of metal grid, lead paste, sulfuric acid electrolyte and plastic shell. The waste lead paste in the waste lead-acid battery is an important secondary lead resource, which is usually composed of 50-60wt% lead sulfate, 15-35% lead dioxide, 5-10wt% lead oxide and 1-5wt% metallic lead. The composition is complex, the recovery technology is difficult, and it has been the focus and difficulty of the recycling and utilization of the recycled lead industry. At present, the main technical methods for recycling waste lead paste include fire process and wet process recovery.

[0004] The most common and popular technical means for recycling lead resources from waste lead paste at home and abroad is based on fire metallurgy technology. In this process, lead in lead-acid battery waste is smelted in a reverberatory furnace, blast furnace, electric furnace or rotary furnace. This process reduces lead compounds and other lead-containing minerals or lead-containing compounds in waste lead paste to crude lead at high temperature, and then high-purity lead is obtained through refining. The whole process has the characteristics of relatively simple device operation and strong raw material adaptability, and has achieved great success in waste lead paste recovery, accounting for more than 90% of waste lead paste recovery technology. However, the traditional fire smelting process uses coal or coke as a reducing agent and fuel, with a temperature as high as 1200℃. In addition, while emitting acid gas SOx, lead fume is inevitably caused, and lead particles are discharged into the air environment, resulting in low lead recovery rate of only 80-90%. The wet-fire combined recovery process first converts lead sulfate in waste lead paste into lead carbonate with lower smelting temperature by using a desulfurizing agent, and the smelting temperature is reduced to 600-800℃, which reduces energy consumption and increases lead recovery rate to more than 98%. However, this method has a complex process and still requires a large amount of desulfurizing solvent and aqueous solution. SUMMARY

[0005] The present application aims at the technical problems of high energy consumption, SOx and lead dust secondary pollution, low desulfurization rate in the process of traditional pyrometallurgical recovery of lead paste from lead-acid battery, and excessive use of chemical reagents and large amount of waste liquid in the process of hydrometallurgical recovery of lead paste, and proposes a method for preparing single crystal lead oxide by low-temperature pyrometallurgical recovery of lead paste, which directly uses lead paste from lead-acid battery to prepare single crystal lead oxide by one-step low-temperature pyrometallurgical recovery, the desulfurizer can directly desulfurize the lead paste, the desulfurization aid can reduce the calcination temperature, and the crystal type control agent can regulate the crystal structure of the generated lead oxide species. The method has the advantages of simple operation, low required reaction temperature, high desulfurization rate, no SOx and lead dust pollutants, high purity and good crystalline of the obtained single crystal lead oxide product, and the reagents can be recycled, which can meet the requirements of industrial production.

[0006] A method for preparing single crystal lead oxide by low-temperature pyrometallurgical recovery of lead paste, the specific steps are as follows:

[0007] (1) removing the waste positive and negative plates from the lead-acid battery and washing them with water;

[0008] (2) stripping the lead paste from the grid of the waste positive and negative plates, grinding and sieving to obtain lead paste powder;

[0009] (3) mixing the lead paste powder with a desulfurizer, a desulfurization aid and a crystal type control agent to obtain a mixture A;

[0010] (4) calcining the mixture A at a temperature of 400-600℃ for 2-8h and cooling in the furnace to obtain a mixture B; during the calcination process, lead dioxide can directly decompose to generate lead oxide, the desulfurizer can react with lead sulfate in the lead paste to desulfurize and further pyrolyze to generate lead oxide; the desulfurization aid can reduce the reaction temperature of the system, promote the transmission and effective contact of the desulfurizer ions, and accelerate the desulfurization reaction; the crystal type control agent can be adsorbed on the surface of lead compounds to regulate the formation energy of different lead oxides during thermal decomposition, thereby regulating the crystal type state of the obtained lead oxide;

[0011] (5) washing and drying the mixture B to obtain single crystal lead oxide, the single crystal lead oxide is α-PbO, β-PbO or Pb3O4; the washing solution generated in the washing process is distilled to obtain a mixture of desulfurizer, desulfurization aid and crystal type control agent, which can be directly returned to step (3) to mix with the lead paste powder to obtain the mixture A.

[0012] The lead-containing substances in the lead paste of step (2) include lead sulfate, lead dioxide, lead oxide and metallic lead.

[0013] The desulfurizer in step (3) is one or more of sodium carbonate, potassium carbonate, sodium bicarbonate and sodium hydroxide.

[0014] The desulfurizer, the auxiliary desulfurizer and the crystal form control agent in the step (3) are one or more of sodium nitrate, potassium nitrate, sodium chloride, zinc chloride and lithium chloride.

[0015] The crystal form control agent in the step (3) is one or more of polyethylene glycol, polyvinylpyrrolidone, sodium dodecyl benzene sulfonate, NP-9, urea and tetrabutyl ammonium bromide.

[0016] The molar ratio of the desulfurizer to lead sulfate in the waste lead paste is 1:05~1.5, the molar ratio of the auxiliary desulfurizer to the desulfurizer is 0.1~3.0:1, and the crystal form control agent accounts for 0.1~5.0% of the mass of the mixture A.

[0017] The atmosphere of the roasting process in the step (4) is Ar, N2 or air.

[0018] The beneficial effects of the present application are:

[0019] (1) In the low-temperature roasting process, the desulfurizer, the auxiliary desulfurizer and the crystal form control agent jointly act on the lead-containing compounds in the waste lead paste to obtain lead oxides with good crystal form;

[0020] (2) The present application is roasted at a low temperature of 400~600℃, and the lead dioxide and lead in the waste lead paste directly react to generate lead oxide, while the lead dioxide itself decomposes to generate lead oxide; simply adding a desulfurizer to the system and then carrying out fire roasting cannot effectively desulfurize the waste lead paste, and the required temperature is still relatively high (900~1000℃);

[0021] (3) The present application introduces an auxiliary desulfurizer into the roasting system, which can significantly reduce the reaction temperature of the entire fire process, promote the transmission and effective contact of the desulfurizer ions, and accelerate the desulfurization reaction, so that the waste lead paste can be effectively desulfurized at a relatively low temperature (400~600℃) to promote the generation of lead oxide species;

[0022] (4) The present application adds a crystal form control agent to the roasting system, which adjusts the formation energy of different lead oxides in the thermal decomposition process by adsorbing on the surface of lead compounds, ensures and realizes the generation of specific crystal form of lead oxide in the reaction process, and improves the purity and selectivity of the lead oxide product;

[0023] The present application can effectively desulfurize the waste lead paste at a relatively low temperature and directly convert it into lead oxide products in different crystal forms, greatly reducing the energy consumption of traditional fire treatment technology and avoiding the generation of SOx gas and lead dust secondary pollution in the traditional fire treatment technology; compared with the waste lead paste wet treatment technology, the present application avoids the use of a large amount of reagents and the generation of waste liquid. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 The process flowchart of the present application;

[0025] Figure 2 XRD pattern of the waste lead paste and the roasting product in Comparative Example 1;

[0026] Figure 3 XRD pattern of the waste lead paste roasting product in Comparative Example 2;

[0027] Figure 4 XRD pattern of the product Pb3O4 in Example 1;

[0028] Figure 5 XRD pattern of the product β-PbO in Example 2;

[0029] Figure 6 XRD pattern of the product α-PbO in Example 4. DETAILED DESCRIPTION

[0030] The application will be described in further detail below with reference to the embodiments. However, the scope of protection of the application is not limited to the content described.

[0031] Comparative Example 1: A method for preparing lead oxide by low-temperature pyrometallurgical recycling of waste lead paste, the specific steps are as follows:

[0032] (1) The waste positive and negative plates are taken out from the lead-acid battery and washed with water;

[0033] (2) The waste lead paste is peeled off from the grid of the waste positive and negative plates and placed in an oven to dry to remove the water on the surface and inside, ground and sieved to obtain waste lead paste powder; analysis shows that the lead-containing substances in the waste lead paste include lead sulfate, lead dioxide, lead oxide and metallic lead, and the content of PbSO4 is 46.8%, the content of PbO2 is 32.7%, the content of PbO is 12.4%, the content of Pb is 5.7%, and other lead forms are 2.4%, based on the mass of the lead-containing substances in the waste lead paste being 100%;

[0034] (3) 5 g of the waste lead paste powder is mixed with 0.9 g of a desulfurizing agent (sodium carbonate) to obtain a mixture A;

[0035] (4) The mixture A is placed in a roaster at a temperature of 600°C for 4 h, and cooled in the furnace to obtain a mixture B; during the roasting process, the lead dioxide can directly decompose to generate lead oxide, and the desulfurizing agent can react with the lead sulfate in the waste lead paste to desulfurize and further pyrolyze to generate lead oxide;

[0036] (5) The mixture B is washed with water and dried to obtain lead oxide;

[0037] The desulfurization rate of the waste lead paste in this comparative example is 63.2%, and the lead conversion rate is 72.1%. The XRD patterns of the waste lead paste and the roasting product in this comparative example are shown in Figure 2 , and Figure 2It is known that the roasting products are mainly composed of PbO·PbSO4, Pb3O4 and β-PbO. Even at high temperatures, the desulfurization rate and lead conversion efficiency of simple desulfurizing agents are still low, and high-purity single-crystal lead oxides cannot be obtained.

[0038] Comparative Example 2: A method for preparing lead oxides from waste lead paste using a low-temperature pyrometallurgical process, the specific steps of which are as follows:

[0039] (1) Remove the waste positive and negative plates from the lead-acid battery and wash them with water;

[0040] (2) The waste lead paste was peeled off from the grid of the waste positive and negative electrode plates and dried in an oven to remove surface and internal moisture. It was then ground and sieved to obtain waste lead paste powder. Analysis showed that the lead-containing substances in the waste lead paste included lead sulfate, lead dioxide, lead oxide and metallic lead. Based on the mass of the lead-containing substances in the waste lead paste as 100%, the content of PbSO4 was 46.8%, the content of PbO2 was 32.7%, the content of PbO was 12.4%, the content of Pb was 5.7%, and the content of other lead forms was 2.4%.

[0041] (3) Mix 5g of waste lead paste powder with 0.9g of desulfurizing agent (sodium carbonate) and 0.72g of desulfurization aid (sodium nitrate) to obtain mixture A;

[0042] (4) Mixture A is roasted at 600℃ for 4 hours and cooled in the furnace to obtain mixture B. During the roasting process, lead dioxide can directly decompose to generate lead oxides. The desulfurizing agent can react with lead sulfate in waste lead paste to desulfurize and further pyrolyze to generate lead oxides. The desulfurization aid can reduce the reaction temperature of the system, promote the transport and effective contact of desulfurizing agent ions, and accelerate the desulfurization reaction.

[0043] (5) Mixture B is washed with water and dried to obtain lead oxide; the water washing solution generated in the water washing process is distilled to obtain a mixture of desulfurizing agent and desulfurization aid, which can be directly returned to step (3) and mixed with waste lead paste powder to obtain mixture A;

[0044] In this comparative example, the desulfurization rate of waste lead paste was 94.6%, and the lead conversion rate was 97.5%. The XRD pattern of the roasted product in this comparative example is shown below. Figure 3 ,from Figure 3 It is known that the calcination product is mainly composed of Pb3O4 and β-PbO. Introducing desulfurizing agent and desulfurizing agent into the system at the same time can achieve a high desulfurization rate and lead conversion efficiency at a lower temperature. However, the crystal state of the obtained lead oxide is mixed, and it is still impossible to obtain a single crystal lead oxide with high purity.

[0045] Example 1: As Figure 1 As shown, a method for preparing single-crystal lead oxide from waste lead paste using a low-temperature pyrometallurgical process includes the following specific steps:

[0046] (1) The waste positive and negative plates are taken out from the lead-acid battery and washed with water;

[0047] (2) The waste lead paste is stripped from the grid of the waste positive and negative plates and placed in an oven to dry to remove the surface and internal moisture, ground and sieved to obtain waste lead paste powder; the waste lead paste of this example is the same as that of the comparative example;

[0048] (3) 5g of waste lead paste powder is uniformly mixed with 0.9g of desulfurizer (sodium carbonate), 0.72g of desulfurization aid (sodium nitrate), and 0.12g of crystal form control agent (sodium dodecyl benzene sulfonate) to obtain a mixture A;

[0049] (4) The mixture A is placed in a furnace at a temperature of 600°C and calcined for 4h, and cooled in the furnace to obtain a mixture B; during the calcination process, the lead dioxide can directly decompose to generate lead oxide, the desulfurizer can react with the lead sulfate in the waste lead paste to desulfurize, and further pyrolyze to generate lead oxide; the desulfurization aid can reduce the reaction temperature of the system, promote the transmission and effective contact of the desulfurizer ions, and accelerate the desulfurization reaction; the crystal form control agent can be adsorbed on the surface of the lead compound to control the crystal form state of the obtained lead oxide;

[0050] (5) The mixture B is washed with water and dried to obtain single crystal lead oxide Pb3O4; the washing solution produced in the washing process is distilled to obtain a mixture of desulfurizer, desulfurization aid, and crystal form control agent, which can be directly returned to step (3) to mix with the waste lead paste powder to obtain the mixture A;

[0051] In this example, the desulfurization rate of the waste lead paste is 98.7%, the lead conversion rate is 99.1%, and the obtained lead oxide species is Pb3O4, with a purity of 98.3%. The XRD spectra of the waste lead paste and the calcination product of the comparative example are shown in Figure 4 , and Figure 4 It can be seen that the calcination product is mainly composed of Pb3O4, and the simultaneous introduction of desulfurizer, desulfurization aid, and crystal form modifier into the system can achieve higher desulfurization rate and lead conversion efficiency at a lower temperature, and obtain single crystal lead oxide mainly composed of Pb3O4.

[0052] Example 2: As shown in Figure 1 , a method for preparing single crystal lead oxide by low-temperature pyrometallurgical recovery of waste lead paste, the specific steps are as follows:

[0053] (1) The waste positive and negative plates are taken out from the lead-acid battery and washed with water;

[0054] (2) The waste lead paste is stripped from the grid of the waste positive and negative plates and placed in an oven to dry to remove the surface and internal moisture, ground and sieved to obtain waste lead paste powder; the waste lead paste of this example is the same as that of the comparative example;

[0055] (3) 5 g of the waste lead paste powder is mixed with 0.75 g of the desulfurizer (sodium carbonate), 0.72 g of the desulfurization aid (sodium nitrate), and 0.08 g of the crystal form control agent (polyvinylpyrrolidone) to obtain a mixture A;

[0056] (4) The mixture A is calcined at a temperature of 500 ℃ for 6 h, and is cooled in the furnace to obtain a mixture B; during the calcination, the lead dioxide can directly decompose to generate lead oxides, the desulfurizer can react with the lead sulfate in the waste lead paste to desulfurize, and further pyrolyze to generate lead oxides; the desulfurization aid can reduce the reaction temperature of the system, promote the transmission and effective contact of the desulfurizer ions, and accelerate the desulfurization reaction; the crystal form control agent can be adsorbed on the surface of the lead compounds to regulate the crystal form state of the obtained lead oxides;

[0057] (5) The mixture B is washed with water and dried to obtain the single crystal form lead oxide β-PbO; the washing solution generated in the water washing process is distilled to obtain a mixture of the desulfurizer, the desulfurization aid, and the crystal form control agent, which can be directly returned to step (3) to be mixed with the waste lead paste powder to obtain the mixture A;

[0058] In this embodiment, the desulfurization rate of the waste lead paste is 97.6%, the lead conversion rate is 98.9%, the obtained lead oxide species is β-PbO, and the purity reaches 94.8%; the XRD spectra of the waste lead paste and the calcination product in this embodiment are shown in Figure 5 , and Figure 5 It can be known that the calcination product is mainly composed of β-PbO, and the simultaneous introduction of the desulfurizer, the desulfurization aid, and the crystal form modifier into the system can achieve a higher desulfurization rate and lead conversion efficiency at a lower temperature, and obtain a single crystal form lead oxide mainly composed of β-PbO.

[0059] Example 3: As shown in Figure 1 , a method for preparing a single crystal form lead oxide by low-temperature pyrometallurgical recovery of waste lead paste, the specific steps are as follows:

[0060] (1) The waste positive and negative plates are taken out from the lead-acid storage battery, and are washed with water;

[0061] (2) The waste lead paste is peeled off from the grid of the waste positive and negative plates, and is dried in an oven to remove the water on the surface and inside, and is ground and sieved to obtain a waste lead paste powder; the waste lead paste in this embodiment is the same as the waste lead paste in the comparative example;

[0062] (3) 5 g of the waste lead paste powder is mixed with 0.64 g of the desulfurizer (potassium carbonate), 0.93 g of the desulfurization aid (zinc chloride), and 0.06 g of the crystal form control agent (polyvinylpyrrolidone) to obtain a mixture A;

[0063] (4) mixture A is placed in a temperature of 550℃ for 2h, and mixture B is obtained by cooling in the furnace; during the roasting process, the lead dioxide can directly decompose to generate lead oxide, the desulfurizer can react with lead sulfate in the waste lead paste to remove sulfur, and further pyrolysis to generate lead oxide; the desulfurization aid can reduce the reaction temperature of the system, promote the transmission and effective contact of the desulfurizer ions, and accelerate the desulfurization reaction; the crystal type control agent can be adsorbed on the surface of lead compounds to regulate the crystal type state of the obtained lead oxide;

[0064] (5) mixture B is washed with water and dried to obtain single crystal type lead oxide β-PbO; the washing solution generated in the water washing process is distilled to obtain a mixture of desulfurizer, desulfurization aid and crystal type control agent, which can be directly returned to step (3) to mix with the waste lead paste powder to obtain mixture A;

[0065] In this embodiment, the desulfurization rate of the waste lead paste is 98.2%, the lead conversion rate is 99.3%, and the obtained lead oxide species is β-PbO, and the purity reaches 95.3%.

[0066] Example 4: As shown in the following, a method for preparing single crystal type lead oxide by low-temperature pyrometallurgical recovery of waste lead paste, the specific steps are as follows: Figure 1

[0067] (1) the waste positive and negative plates are taken out from the lead-acid battery, and washed with water;

[0068] (2) the waste lead paste is peeled off from the grid of the waste positive and negative plates and dried in an oven to remove the water on the surface and inside, ground and sieved to obtain waste lead paste powder; the waste lead paste in this embodiment is the same as that in the comparative example;

[0069] (3) 5g of waste lead paste powder is mixed with 0.72g of desulfurizer (sodium hydroxide), 0.65g of desulfurization aid (sodium chloride) and 0.08g of crystal type control agent (polyethylene glycol) to obtain mixture A;

[0070] (4) mixture A is placed in a temperature of 420℃ for 2h, and mixture B is obtained by cooling in the furnace; during the roasting process, the lead dioxide can directly decompose to generate lead oxide, the desulfurizer can react with lead sulfate in the waste lead paste to remove sulfur, and further pyrolysis to generate lead oxide; the desulfurization aid can reduce the reaction temperature of the system, promote the transmission and effective contact of the desulfurizer ions, and accelerate the desulfurization reaction; the crystal type control agent can be adsorbed on the surface of lead compounds to regulate the crystal type state of the obtained lead oxide;

[0071] (5) mixture B is washed with water and dried to obtain single crystal type lead oxide α-PbO; the washing solution generated in the water washing process is distilled to obtain a mixture of desulfurizer, desulfurization aid and crystal type control agent, which can be directly returned to step (3) to mix with the waste lead paste powder to obtain mixture A;

[0072] ​The desulfurization rate of the waste lead paste in the embodiment is 95.1%, the lead conversion rate is 97.8%, the obtained lead oxide species is α-PbO, and the purity reaches 93.7%; the XRD spectra of the waste lead paste and the calcined product in the embodiment are shown in Figure 6 It can be known that the calcined product is mainly composed of α-PbO, the simultaneous introduction of the desulfurizer, the desulfurization aid and the crystal modification agent into the system can realize higher desulfurization rate and lead conversion efficiency at a lower temperature, and the single crystal type lead oxide mainly in α-PbO is obtained. Figure 6

[0073] The specific embodiments of the present application are described in detail above, but the present application is not limited to the above-mentioned embodiments, and various changes can be made within the knowledge of those skilled in the art without departing from the purpose of the present application.​

Claims

1. A process for the preparation of monocrystalline lead oxides from spent lead paste by low temperature pyrometallurgical recycling, characterized in that, The specific steps are as follows: (1) removing the waste positive and negative plates from the lead-acid battery and washing with water; (2) stripping the waste lead paste from the grid of the waste positive and negative plates, grinding and sieving to obtain waste lead paste powder; (3) mixing the waste lead paste powder with a desulfurizing agent, a desulfurization aid and a crystal form control agent to obtain a mixture A; the crystal form control agent is one or more of polyethylene glycol, polyvinylpyrrolidone and sodium dodecylbenzenesulfonate; the molar ratio of the desulfurizing agent to lead sulfate in the waste lead paste is 1:0.5-1.5, the molar ratio of the desulfurization aid to the desulfurizing agent is 0.1-3.0:1, and the crystal form control agent accounts for 0.1-5.0% of the mass of the mixture A; (4) baking the mixture A at a temperature of 400-600°C for 2-8h and cooling in the furnace to obtain a mixture B; (5) washing and drying the mixture B to obtain a single crystal lead oxide, which is α-PbO, β-PbO or Pb3O4.

2. The process for the preparation of monocrystalline lead oxide from spent lead paste by low temperature pyrometallurgical recovery according to claim 1, characterized in that: The lead-containing substances in the waste lead paste in step (2) include lead sulfate, lead dioxide, lead oxide and metallic lead.

3. The process for the preparation of single crystal lead oxide from spent lead paste by low temperature pyrometallurgical recovery as claimed in claim 1 wherein: The desulfurizing agent in step (3) is one or more of sodium carbonate, potassium carbonate, sodium bicarbonate and sodium hydroxide.

4. The process for the preparation of single crystal lead oxide from spent lead paste by low temperature pyrometallurgical recovery as claimed in claim 1 wherein: The desulfurization aid in step (3) is one or more of sodium nitrate, potassium nitrate, sodium chloride, zinc chloride and lithium chloride.

5. The process for the preparation of monocrystalline lead oxide from spent lead paste by low temperature pyrometallurgical recovery according to claim 1, characterized by the fact that: The atmosphere in the baking process in step (4) is Ar, N2 or air.

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