CN113668016A - Method for recovering metallic lead by solid-phase electrolytic reduction and electrolytic cell with pressure filtration type plate frame - Google Patents

Abstract

The invention relates to the field of waste lead paste recycling, and discloses a method for recycling metallic lead through solid-phase electrolytic reduction and an electrolytic cell with a pressure filtration plate frame, wherein the method comprises the following steps: (1) contacting the waste lead plaster with a desulfurizing agent, and carrying out solid-liquid separation on a contacted mixture to obtain desulfurized lead plaster and desulfurized filtrate containing sulfate; (2) mixing the desulfurized lead plaster with an electrolysis promoter to prepare a cathode, and placing the cathode in an electrolytic bath for electrolysis to obtain metal lead and circulating electrolyte; the process optionally further comprises step (3): and (3) optionally supplementing a desulfurizing agent to the desulfurization filtrate, cooling and crystallizing, and then carrying out solid-liquid separation to obtain a sulfate crystal and a circulating regeneration desulfurizing agent. In the method provided by the invention, the lead plaster of the waste lead-acid battery is directly subjected to pre-circulation desulfurization and solidification-free electrolysis to obtain lead powder and sulfate. The electrolytic cell with the filter-press plate frame can realize the integration of production and electrolysis.

Description

Method for recovering metallic lead by solid-phase electrolytic reduction and electrolytic cell with pressure filtration type plate frame

Technical Field

The invention relates to the field of waste lead paste recycling, in particular to a method for recycling metallic lead through solid-phase electrolytic reduction and an electrolytic cell with a pressure filtration plate frame.

Background

Lead-acid batteries have good performance and cycle life and are widely used in communication devices, automotive ignition, and emergency lighting systems. According to statistics, about 80% of global lead yield is used for production of lead-acid storage batteries, and with scrapping of a large number of lead-acid batteries, the waste lead-acid batteries become an increasingly important secondary resource, and the recovery of the lead-acid batteries accounts for more than 85% of the total amount of the produced secondary lead. The cyclic regeneration of waste lead-acid batteries and the realization of the clean recovery of lead-containing secondary resources are important problems facing industries such as lead-acid batteries, secondary lead and the like. The lead-acid battery mainly contains lead paste and a grid, wherein the lead paste has complex components and high impurity content, and is a key and difficult point for recycling waste lead-acid batteries.

At present, the method for recovering lead plaster in a lead-acid battery mainly adopts pyrometallurgical high-temperature smelting to recover metallic lead, and the problems of serious pollution, high energy consumption and the like exist along with the release of oxysulfide gas and the entrance of lead dust into the environment in the process. Because the waste lead plaster mainly contains lead compounds such as lead sulfate, lead oxide, lead dioxide and the like, wherein the lead sulfate is insoluble in common electrolytes such as sulfuric acid, hydrochloric acid and the like, the direct solid-phase electrolysis method of the lead plaster containing the lead sulfate can be adopted for recovering the waste lead plaster into the metal lead. In solid-phase electrolysis, there are mainly two processes of acidic solid-phase electrolysis and alkaline solid-phase electrolysis depending on the electrolyte. For example, Girac reports a process for in-situ reduction of lead in waste storage batteries by a full-wet acidic electrolysis solid phase, which comprises the steps of putting lead mud into a crusher for crushing, adding a proper amount of lead monoxide and water to prepare a slurry, and coating the slurry on a stainless steel electrode plate. The polar plate is placed in dilute electrolyte for electrolysis after natural drying. According to calculation, the process has the lead recovery rate as high as 95 percent, and the comprehensive energy consumption is about 950 DEG and 1100 DEG electricity/ton. Aiming at the problem that a lot of lead mud and lead-containing waste liquid are generated in the disassembly process of the lead-acid battery, in order to realize the direct recovery of the polar plate of the waste lead-acid battery, the Pan army blue invents a double-power-supply multi-module direct electrolysis process in 2008. Placing a battery unit or a battery pack separated from a shell of a waste lead-acid battery into a lead alloy electrolytic tank, and electrolyzing by using a lead dioxide positive electrode as a cathode and a lead negative electrode as an anode as a power supply I; and a second power supply adopts a lead cathode as a cathode, an outer lead alloy tank as an anode and is placed in dilute sulfuric acid electrolyte for electrolysis. After electrolysis, the positive plate and the negative plate are directly reduced to metallic lead, 15-20% dilute sulfuric acid is obtained, and the single lead recovery rate is up to 96%. In the research process, researchers also find that a proper amount of acetate ions can effectively improve the activity and the cathode efficiency of the lead sulfate in the electrolysis process and shorten the electrolysis time. Inevitably, we see that the acidic solid phase electrodeposition process has the energy consumption problem of 1050 ℃ for lead per ton as high as 900-. In addition, the process is not suitable for the waste lead acid battery with the damaged battery or the mud phenomenon of the polar plate. In order to overcome the problem of overhigh energy consumption of acidic solid-phase electrolysis, a solid-phase electrolysis method taking an alkaline NaOH solution as an electrolyte is provided by the land source. The process adopts stainless steel as a cathode plate and an anode plate, a certain amount of lead paste slurry is coated on the cathode plate, after pressing, curing and forming, the lead paste slurry is put into an electrolytic tank of sodium hydroxide solution for electrolysis, and lead compounds are directly reduced to metallic lead on the cathode plate. The recovery rate of lead can reach 95%, and the energy consumption is 550 degrees electricity/ton. In addition, during the electrolysis process, the experiment determines that about 130 jin of sodium hydroxide is consumed by one ton of metal lead. In 2005, the terrg source subject group was improved on the aspects of electrodeposition process and electrode structure, and the electrolytic process was optimized, so that the direct current power consumption was reduced to 350 degrees per ton of lead, and the alkali consumption was controlled at 100kg per ton of lead. The cost of each ton of sodium hydroxide is up to 3200 yuan, so that the alkali consumption cost of the solid phase electrolysis process is higher. The analysis of the existing solid-phase electrolysis method shows that the main problems of the existing process are as follows:

(1) the energy consumption of electrolysis is higher

The alkaline NaOH solution is not only a desulfurizer, but also an electrolyte, so that NaOH is continuously consumed along with the desulfurization process, so that the impedance of the electrolyte is gradually increased, and the cell pressure in the middle and later periods of electrolysis is higher.

(2) Usually, the electrolysis process needs to add 1.2 to 1.5 times more NaOH than the theoretical amount, and the electrolysis is difficult to recycle, so that the consumption of NaOH is higher.

(3) The cathode plate coated with the waste lead plaster needs to be cured for 6-24 hours in each electrolysis process, so that the electrolysis efficiency is greatly reduced, and continuous electrolysis is difficult to realize.

How to improve the utilization efficiency of sodium hydroxide and realize the recycling of electrolysis mother liquor and solidification-free continuous solid-phase electrolysis is a difficult problem to be solved urgently by a lead plaster solid-phase electrolysis process.

Disclosure of Invention

The invention aims to solve the problems of high cost, long flow path and high energy consumption in the solid-phase electrolytic recovery process of waste lead plaster in the prior art, and provides a method for recovering metallic lead by solid-phase electrolytic reduction without solidification and an electrolytic cell with a pressure filtration plate frame. The method has the advantages of low cost and easy industrialization.

In order to achieve the above object, an aspect of the present invention provides a method for recovering metallic lead by solid-phase electrolytic reduction, the method comprising the steps of:

(1) contacting the waste lead plaster with a desulfurizing agent, and carrying out solid-liquid separation on a contacted mixture to obtain desulfurized lead plaster and desulfurized filtrate containing sulfate;

(2) mixing the desulfurized lead plaster with an electrolysis promoter to prepare a cathode, and placing the cathode in an electrolytic bath for electrolysis to obtain metal lead and circulating electrolyte;

the process optionally further comprises step (3): and (3) optionally supplementing a desulfurizing agent to the desulfurization filtrate, cooling and crystallizing, and then carrying out solid-liquid separation to obtain a sulfate crystal and a circulating regeneration desulfurizing agent.

The invention provides in a second aspect an electrolytic cell with a pressure filtration plate frame, the electrolytic cell being provided with a cathode, an anode, a diaphragm and an electrolyte;

the cathode is formed by pressing the desulfurized lead plaster and the electrolytic accelerant by adopting a plate-and-frame filter press after the desulfurized lead plaster and the electrolytic accelerant are mixed;

the diaphragm is filter cloth of a plate-and-frame filter press;

the electrolyte is placed in the plate frame;

the anode is arranged between the cathode plate frames provided with the filter bags.

Compared with the prior art, the invention has the following advantages:

(1) the method for recovering the metallic lead by the solid-phase electrolytic reduction has low energy consumption and is easy to industrially implement;

(2) the method for recovering the metallic lead by the solid-phase electrolytic reduction can realize the recycling of materials, for example, the electrolyte can be recycled, such as being used for 6 times of recycling electrolysis, and can be degraded for desulfurization reaction;

(3) in the prior art, partial lead oxide and lead dioxide after desulfurization are too fine to be reduced, and the method provided by the invention adopts the desulfurized lead plaster and the electrolysis promoter to be mixed to prepare the cathode for electrolysis;

(4) compared with the prior art, the method has high process efficiency and does not add too much chemical reagent;

(5) preferably, the electrolysis is carried out in the presence of a magnetic field, so that concentration polarization in the electrolysis process is eliminated due to the directional movement of the electrolyte in the electrolysis process, and energy consumption is saved compared with the electrolysis process without the magnet under the same electrolysis condition;

(6) the invention provides an electrolytic cell with a pressure filtration plate frame, which breaks through the difficult problem that waste lead paste needs to be pre-cured and realizes the integration of production and electrolysis.

Drawings

FIG. 1 is a flow chart of a process for recovering metallic lead by solid phase electrolytic reduction according to an embodiment of the present invention;

FIG. 2 is a schematic view of an electrolytic cell with a filter-press frame according to an embodiment of the present invention.

Description of the reference numerals

1-desulfurization lead plaster cathode plate 2-filter bag diaphragm 3-anode plate

4-cathode feeding round hole 5-filter press electrolytic tank 6-filter press electrolytic tank fixing rod

External fixing plate

7-filter press electrolytic tank outer support

Detailed Description

The endpoints of the ranges and any values disclosed herein are not limited to the precise range or value, and such ranges or values should be understood to encompass values close to those ranges or values. For ranges of values, between the endpoints of each of the ranges and the individual points, and between the individual points may be combined with each other to give one or more new ranges of values, and these ranges of values should be considered as specifically disclosed herein.

The invention provides a method for recovering metallic lead by solid-phase electrolytic reduction, which comprises the following steps:

(1) contacting the waste lead plaster with a desulfurizing agent, and carrying out solid-liquid separation on a contacted mixture to obtain desulfurized lead plaster and desulfurized filtrate containing sulfate;

(2) mixing the desulfurized lead plaster with an electrolysis promoter to prepare a cathode, and placing the cathode in an electrolytic bath for electrolysis to obtain metal lead and circulating electrolyte;

the process optionally further comprises step (3): and (3) optionally supplementing a desulfurizing agent to the desulfurization filtrate, cooling and crystallizing, and then carrying out solid-liquid separation to obtain a sulfate crystal and a circulating regeneration desulfurizing agent.

In the invention, the waste lead plaster is conventional in the field, has a conventional composition and mainly comprises lead sulfate, lead powder, lead oxide and lead dioxide.

In the present invention, the optional inclusion of step (3) means that step (3) may be included or may not be included, and step (3) is preferably included. The recycling of the desulfurizing agent can be realized by adopting the preferred embodiment.

According to the present invention, in step (1), preferably, the desulfurizing agent is at least one selected from the group consisting of sodium hydroxide, potassium hydroxide and ammonia water, and more preferably sodium hydroxide.

According to a specific embodiment of the invention, the contacting in step (1) is carried out in the presence of a solvent, specifically, the waste lead plaster is contacted with an aqueous solution of a desulfurizing agent. The concentration of the aqueous solution of the desulfurizing agent is preferably 1 to 20% by weight, and more preferably 5 to 15% by weight.

Preferably, the molar ratio of the usage amount of the desulfurizing agent to the theoretical usage amount of the lead sulfate desulfurization reaction in the waste lead paste is 0.8-3: 1, preferably 1.0 to 2.5:1, more preferably 1.0 to 2.2: 1.

the contact conditions in the step (1) are selected in a wide range so as to realize the desulfurization of the waste lead plaster, and preferably, the contact temperature in the step (1) is 0-120 ℃, and preferably 30-100 ℃. Preferably, in step (1), the contact time is 5-120min, preferably 20-60 min.

Preferably, the contacting is carried out under stirring conditions, preferably at a rate of 30 to 600 rpm.

The solid-liquid separation in step (1) is not particularly limited in the present invention, and various methods conventionally used in the art may be used.

According to the present invention, in the step (2), the electrolysis promoter is preferably at least one selected from the group consisting of lead powder, carbon black, carbon powder, zinc powder, hydrogen peroxide, activated carbon and graphene, and more preferably at least one selected from the group consisting of lead powder, hydrogen peroxide and carbon powder.

Preferably, the amount of the electrolysis promoter is 0.05-35% by weight, more preferably 0.1-15% by weight of the desulfurized lead paste.

In the present invention, the shape of the cathode is not particularly limited as long as the electrolysis can be achieved.

Preferably, the step (2) of mixing the desulfurized lead paste with an electrolysis promoter to form a cathode comprises the following steps: mixing the desulfurized lead paste with an electrolysis accelerant, and pressing the mixture into a cathode under an oil press. Preferably, the method further comprises curing the pressed cathode, wherein the curing time is preferably 2-20 h.

The oil press may be any of various oil presses conventionally used in the art.

Preferably, the oil press pressure is 0.1-10MPa, preferably 1-5 MPa.

Preferably, the cathode has a thickness of 0.5-5.5 cm.

According to the invention, in particular, an anode and an electrolyte are arranged in the electrolytic cell; preferably, the anode is made of nickel-cobalt iridium oxide coated nickel-plated steel plate.

Preferably, the electrolyte is at least one selected from the group consisting of an aqueous sodium hydroxide solution, an aqueous potassium hydroxide solution and aqueous ammonia, and more preferably an aqueous sodium hydroxide solution. In this preferred embodiment, the alkaline electrolyte is used, which is less energy consuming than the acidic electrolyte. In particular, the amount of the solvent to be used,

acid electrolyte electrolysis cathode: PbSO₄+2e＝Pb+SO₄ ^2- E⁰＝-0.356V

Anode: h₂O-2e＝2H⁺+1/2O₂ E⁰＝1.229V

And (3) total reaction: PbSO₄+H₂O＝Pb+H₂SO₄+1/2O₂

Alkaline electrolyte, various lead compounds obtain electrons at a cathode and are reduced into metallic lead, and an anode plate emits oxygen:

cathode: PbO +2e^-+H₂O→Pb+2OH^-E^θ＝-0.578V

PbO₂+2e^-+H₂O→PbO+2OH^-E^θ＝0.28V

PbO₂+2H₂O+4e^-→Pb+4OH^-E^θ＝-0.54V

Anode: 2OH^-+2e^-→H₂O+1/2O₂↑ E^θ＝0.401V

From the above principle, it is known that the tank pressure in the alkaline solution is lower than that of the acidic electrolyte, and therefore, the energy consumption is low.

The concentration of the electrolyte is selected in a wide range, and preferably, the concentration of the electrolyte is 5-35 wt%.

Preferably, in the step (2), the cell pressure of the electrolysis is 1.3-2.2V, preferably 1.5-1.85V.

Preferably, in step (2), the electricity isThe current density of the solution is 30-5000A/m²Preferably 100-650A/m²。

Preferably, in step (2), the current efficiency of the electrolysis is 95-99%.

According to a preferred embodiment of the present invention, the electrolysis of step (2) is carried out in the presence of a magnetic field. According to the invention, preferably, said magnetic field is achieved by placing a magnet under said electrolytic cell. More preferably, N35-N52 permanent magnets are used to accomplish the electrolysis process under magnetic drive.

Preferably, the direction of the magnetic field is perpendicular to the moving direction of ions in the electrolyte, so that the directional movement of the electrolyte in the electrolysis process is realized. Under the preferred embodiment, the electrolyte has spontaneous directional motion in the electrolytic process, so that concentration polarization in the electrolytic process is effectively eliminated, and energy consumption is saved compared with the electrolytic process without a magnetic field under the same electrolytic condition.

Further preferably, the direction of the lorentz force generated by the magnetic field is consistent with the buoyancy direction of the bubbles in the electrolysis process. In this preferred embodiment, the buoyancy and directional movement of the bubbles generated by the anode during electrolysis are made to be in the same direction.

In the present invention, the desulfurizing agent may or may not be supplemented in step (3), based on the concentration of the desulfurizing agent in the solution before solid-liquid separation.

According to the present invention, preferably, in the step (3), the desulfurization filtrate is subjected to optional replenishment of a desulfurizing agent so that the concentration of the desulfurizing agent is 8 to 15% by weight.

In the present invention, the conditions for the cooling crystallization are not particularly limited, and the solid can be precipitated. Preferably, the temperature of the cooling crystallization is 0 to 15 ℃, and then the solid-liquid separation is performed.

According to a particularly preferred embodiment of the present invention, the step (2) of mixing the desulfurized lead paste with an electrolysis promoter to form a cathode comprises: mixing the desulfurized lead plaster with the electrolysis accelerant, and pressing the desulfurized lead plaster and the electrolysis accelerant into a cathode by adopting a plate-and-frame filter press.

Preferably, the pressure filtration pressure is 0.01-10MPa, and the filter cake thickness is 0.2-50 mm; further preferably, the pressure filtration pressure is 0.1-4.0MPa, and the thickness of the filter cake is 5-40 mm; more preferably, the pressure filtration pressure is 0.3-1.2MPa, and the filter cake thickness is 15-35 mm.

According to the present invention, a plate frame comprising a stainless steel lining as a conductive cathode current collector is preferably used.

In a second aspect, the invention provides an electrolytic cell with a pressure filtration plate frame, as shown in fig. 2, the electrolytic cell is provided with a cathode (desulfurized lead plaster cathode plate 1), an anode (anode plate 3), a diaphragm (filter bag diaphragm 2) and electrolyte;

the cathode is formed by pressing the desulfurized lead plaster and the electrolytic accelerant by adopting a plate-and-frame filter press after the desulfurized lead plaster and the electrolytic accelerant are mixed;

the diaphragm is filter cloth of a plate-and-frame filter press;

the electrolyte is placed in the plate frame;

the anode is arranged between two cathode plate frames provided with filter bags.

Preferably, the electrolytic cell with the filter-press plate frame is used for enabling the desulfurization lead plaster to be subjected to solidification-free in-situ electrolysis in the plate frame to obtain lead powder.

According to a particularly preferred embodiment of the present invention, in the step (2), after the desulfurized lead plaster and the electrolysis promoter are mixed, the desulfurized lead plaster and the electrolysis promoter are pressed into cathodes by using a plate and frame filter press, filter cloth of the plate and frame filter press is used as a diaphragm, an electrolyte is placed in a plate and frame of the plate and frame filter press, and preferably, an anode is arranged in parallel between the two cathodes. By adopting the particularly preferred embodiment, the integration of production and electrolysis is realized, the curing waiting time required by the traditional solid-phase electrolysis is avoided, the curing-free direct electrolysis process of the lead paste is realized, the labor cost is greatly reduced, and the production efficiency is improved.

According to a specific embodiment of the invention, the electrolytic cell with the filter-press plate frame is further provided with a cathode feeding round hole 4, a filter press electrolytic cell outer fixing plate 5, a filter press electrolytic cell fixing rod 6 and a filter press electrolytic cell outer bracket 7. The specific embodiment of the arrangement is shown in fig. 2, the present invention is not particularly limited thereto, and those skilled in the art can appropriately select the arrangement according to the actual situation based on the above disclosure.

The electrolyte solution of the present invention is not particularly limited, and may be the electrolyte solution of the first aspect.

The anode of the present invention may be an inert electrode, such as a graphite electrode or a nickel-plated steel plate, or the anode of the first aspect.

According to a particularly preferred embodiment of the invention, when the desulphurating agent is sodium hydroxide, the process comprises: contacting the waste lead plaster with a desulfurizing agent (sodium hydroxide), and carrying out solid-liquid separation on a contacted mixture to obtain desulfurized lead plaster (lead carbonate) and a desulfurization filtrate containing sulfate (sodium sulfate);

(2) pressing the desulfurized lead plaster and an electrolysis accelerant (lead powder) into a cathode (round lead cake), and placing the cathode in an electrolytic bath for solid-phase electrolysis;

(3) and supplementing a desulfurizing agent to the desulfurization filtrate, and then carrying out solid-liquid separation to obtain a sodium sulfate crystal and a circularly regenerated desulfurizing agent (sodium hydroxide).

The present invention will be described in detail below by way of examples.

Example 1

The waste lead paste obtained from the waste super-power 6-DZM-12 battery is used as an experimental sample, and the weight percentage of the main components is as follows through analysis: 9.1% PbO, 7.0% Pb, 43.7% PbSO₄、39.0％PbO₂The balance being water.

(1) 1 kg of waste lead plaster is contacted with an aqueous solution of a desulfurizing agent (a sodium hydroxide solution with the weight percentage concentration of 10%) for desulfurization reaction, wherein the molar ratio of the using amount of the sodium hydroxide to the theoretical using amount of the lead sulfate in the waste lead plaster for desulfurization reaction is 2.2: 1. Carrying out solid-liquid separation after reacting for 30min under the conditions of heat preservation at 30 ℃ and stirring speed of 100 r/min to obtain desulfurized lead paste and desulfurized mother liquor containing sodium sulfate;

(2) uniformly mixing the desulfurized lead paste with 10 wt% of lead powder accelerant, pressing the mixture into a cathode with the thickness of 2.5 cm and the thickness of 10 multiplied by 13 square cm under the pressure of 3MPa in an oil press, solidifying the cathode for 10 hours, placing the cathode in an electrolytic cell filled with 20 wt% of sodium hydroxide and an anode made of a commercially available nickel-plated steel plate for electrolysis, controlling the current density to be 400 amperes per square meter, and electrolyzing to obtain metal lead and circulating electrolyte.

The cell pressure in the electrolysis process was 1.92V, and the current efficiency was 95%. The electrolytic energy consumption of each ton of lead is 525 DEG through calculation.

(3) And (2) supplementing a 30 wt% sodium hydroxide solution into the desulfurization mother liquor obtained in the step (1) to restore the concentration of the sodium hydroxide solution to 10 wt%, cooling to 5 ℃, and performing solid-liquid separation to obtain a sodium sulfate solid and a circulating regeneration desulfurizer. The circulating regenerated desulfurizer returns to the step (1) to desulfurize the next batch of materials. Through analysis, the lead powder is smelted to obtain a lead ingot with the purity of 99.92 percent.

Example 2

(1) 1 kg of waste lead plaster is contacted with an aqueous solution of a desulfurizing agent (a sodium hydroxide solution with the weight percentage concentration of 10%) for desulfurization reaction, wherein the molar ratio of the using amount of the sodium hydroxide to the theoretical using amount of the lead sulfate in the waste lead plaster for desulfurization reaction is 2.5: 1. Carrying out solid-liquid separation after reacting for 30min under the conditions of heat preservation at 45 ℃ and stirring speed of 100 r/min to obtain desulfurized lead paste and desulfurized mother liquor containing sodium sulfate;

(2) uniformly mixing the desulfurized lead paste with 10 wt% of lead powder accelerant, pressing the mixture into a cathode with the thickness of 1.5 cm and the thickness of 10 multiplied by 13 square cm under an oil press by adopting the pressure of 5.0MPa, solidifying the cathode for 6 hours, placing the cathode in an electrolytic cell filled with an anode made of 20 wt% of sodium hydroxide and a commercially available nickel-plated steel plate for electrolysis, controlling the current density to be 400 amperes per square meter, and placing the cathode 10 multiplied by 2.5 multiplied by 2 cm below the electrolytic cell³The square N52 magnet realizes the upward movement of the electrolyte, and the metal lead and the circulating electrolyte are obtained through electrolysis.

The cell pressure in the electrolysis process was 1.89V, and the current efficiency was 98%. Through measurement and calculation, the energy consumption of electrolysis is about 501 degrees electricity per ton. Experiments show that in the presence of a magnetic field, electrolyte in the electrolysis process forms directional movement which is the same as the buoyancy of bubbles, concentration polarization in the electrolysis process is eliminated, and the concentration polarization is saved by about 30mV compared with the electrolysis process without the magnet under the same electrolysis condition.

(3) And (2) supplementing a 30 wt% sodium hydroxide solution into the desulfurization mother liquor obtained in the step (1) to restore the concentration of the sodium hydroxide solution to 10 wt%, cooling to 5 ℃, and performing solid-liquid separation to obtain a sodium sulfate solid and a circulating regeneration desulfurizer. The circulating regenerated desulfurizer returns to the step (1) to desulfurize the next batch of materials. Through analysis, the lead powder is smelted by a pyrogenic process to obtain a lead ingot with the purity of 99.95%.

Example 3

(1) 1 kg of waste lead plaster is contacted with an aqueous solution of a desulfurizing agent (sodium hydroxide solution with the weight percentage concentration of 8%) for desulfurization reaction, wherein the molar ratio of the using amount of the sodium hydroxide to the theoretical using amount of the lead sulfate in the waste lead plaster for desulfurization reaction is 2.5: 1. Carrying out solid-liquid separation after reacting for 30min under the conditions of heat preservation at 60 ℃ and stirring speed of 300 r/min to obtain desulfurized lead paste and desulfurized mother liquor containing sodium sulfate;

(2) uniformly mixing the desulfurized lead plaster with 8 wt% of lead powder accelerant, pressing the mixture into a cathode with the thickness of 2.5 cm and the thickness of 10 multiplied by 13 square cm under the pressure of 3MPa under an oil press, solidifying the cathode for 6 hours, placing the cathode into an electrolytic cell filled with 20 wt% of sodium hydroxide and an anode made of a commercially available nickel-cobalt-iridium oxide coated nickel plated steel plate for electrolysis, controlling the current density to be 400 amperes per square meter, and placing 10 multiplied by 2.5 multiplied by 2 cm below the electrolytic cell³Electrolyzing the square magnet to obtain metal lead and circulating electrolyte.

The cell pressure in the electrolysis process was 1.75V, and the current efficiency was 95%.

Experiments show that the nickel-cobalt-iridium oxide can promote the anodic oxygen evolution reaction and reduce the overpotential of the anode, and compared with the common nickel-plated steel plate anode, the overpotential of 140mV can be saved, so that the ton of lead electrolysis is further reduced to 479 ℃.

(3) And (2) supplementing a 30 wt% sodium hydroxide solution into the desulfurization mother liquor obtained in the step (1) to restore the concentration of the sodium hydroxide solution to 8 wt%, cooling to 5 ℃, and performing solid-liquid separation to obtain a sodium sulfate solid and a circulating regeneration desulfurizer. The circulating regenerated desulfurizer returns to the step (1) to desulfurize the next batch of materials. Through analysis, the lead powder is smelted to obtain a lead ingot with the purity of 99.92 percent.

Example 4

(1) 1 kg of waste lead plaster is contacted with an aqueous solution of a desulfurizing agent (a sodium hydroxide solution with the weight percentage concentration of 10%) for desulfurization reaction, wherein the molar ratio of the using amount of the sodium hydroxide to the theoretical using amount of the lead sulfate in the waste lead plaster for desulfurization reaction is 2.5: 1. Carrying out solid-liquid separation after reacting for 50min under the conditions of heat preservation at 60 ℃ and stirring speed of 300 r/min to obtain desulfurized lead paste and desulfurized mother liquor containing sodium sulfate;

(2) uniformly mixing the desulfurized lead paste with 9 wt% of lead powder accelerant, pressing the mixture into a cathode with the thickness of 10 multiplied by 13 square centimeters and the thickness of 3.0 centimeters under an oil press under the pressure of 3MPa, solidifying the cathode for 6 hours, placing the cathode into an electrolytic cell filled with 15 wt% of sodium hydroxide and an anode made of a commercially available nickel-cobalt-iridium oxide coated nickel plated steel plate for electrolysis, controlling the current density to be 400 amperes per square meter, placing a circular magnet with the diameter of 16 centimeters below the electrolytic cell, and electrolyzing the circular magnet to obtain metal lead and circulating electrolyte.

The cell pressure in the electrolysis process was 1.81V, and the current efficiency was 95%.

(3) And (2) supplementing a 30 wt% sodium hydroxide solution into the desulfurization mother liquor obtained in the step (1) to restore the concentration of the sodium hydroxide solution to 10%, cooling to 5 ℃, and performing solid-liquid separation to obtain a sodium sulfate solid and a circulating regeneration desulfurizer. The circulating regenerated desulfurizer returns to the step (1) to desulfurize the next batch of materials. Through analysis, the lead powder is smelted to obtain a lead ingot with the purity of 99.92 percent.

Example 5

(1) 1 kg of waste lead plaster is contacted with an aqueous solution of a desulfurizing agent (a sodium hydroxide solution with the weight percentage concentration of 10%) for desulfurization reaction, wherein the molar ratio of the using amount of the sodium hydroxide to the theoretical using amount of the lead sulfate in the waste lead plaster for desulfurization reaction is 2.5: 1. Carrying out solid-liquid separation after reacting for 30min under the conditions of heat preservation at 70 ℃ and stirring speed of 100 r/min to obtain desulfurized lead paste and desulfurized mother liquor containing sodium sulfate;

(2) the desulfurized lead paste and 30 wt% of lead powder accelerator are uniformly mixed and then are pressed under an oil press under the pressure of 3MPa to form a cathode with the thickness of 10 multiplied by 13 square centimeters and the thickness of 2.5 centimeters, and after the mixture is solidified for 9 hours, the cathode is placed in an electrolytic cell provided with sodium hydroxide electrolyte and an anode made of a commercially available nickel-cobalt-iridium oxide coated nickel plated steel plate for electrolysis, the sodium hydroxide electrolyte in the electrolytic cell is from the electrolytic cell after the electrolysis of the embodiment 1, and the electrolyte is recycled for 6 times in the embodiment 1. Controlling the current density to be 400A/m, placing a circular magnet with the diameter of 16 cm below the electrolytic cell, and electrolyzing to obtain metal lead and circulating electrolyte.

The cell pressure in the electrolysis process was 1.80V, and the current efficiency was 95%.

(3) And (2) supplementing a 30 wt% sodium hydroxide solution into the desulfurization mother liquor obtained in the step (1) to restore the concentration of the sodium hydroxide solution to 10 wt%, cooling to 5 ℃, and performing solid-liquid separation to obtain a sodium sulfate solid and a circulating regeneration desulfurizer. The circulating regenerated desulfurizer returns to the step (1) to desulfurize the next batch of materials. Through analysis, the lead powder is smelted to obtain a lead ingot with the purity of 99.91%.

Example 6

(1) 1 kg of waste lead plaster is contacted with an aqueous solution of a desulfurizing agent (from the electrolyzed sodium hydroxide electrolyte in example 5, the recycling and degrading use of the sodium hydroxide solution are realized) to carry out desulfurization reaction, wherein the molar ratio of the using amount of the sodium hydroxide to the theoretical using amount of the lead sulfate in the waste lead plaster is 2.5: 1. Carrying out solid-liquid separation after reacting for 30min at the temperature of 60 ℃ and the stirring speed of 100 r/min to obtain desulfurized lead paste and desulfurized mother liquor containing sodium sulfate;

(2) uniformly mixing the desulfurized lead paste with 10 wt% of lead powder accelerant, pressing the mixture into a cathode with the thickness of 2.5 cm and the thickness of 10 multiplied by 13 square cm under an oil press under the pressure of 3MPa, solidifying the cathode for 8 hours, placing the cathode in an electrolytic cell filled with 20% of sodium hydroxide and an anode made of a commercially available nickel-cobalt-iridium oxide-coated nickel plated steel plate for electrolysis, controlling the current density to be 1000 amperes per square meter, placing a circular magnet with the diameter of 16 cm below the electrolytic cell, and electrolyzing the circular magnet to obtain metal lead and circulating electrolyte.

The bath pressure in the electrolysis process is 2.12V, the current efficiency is 98 percent, and the power consumption of ton lead is 562 degrees.

(3) And (2) supplementing a 30 wt% sodium hydroxide solution into the desulfurization mother liquor obtained in the step (1) to restore the concentration of the sodium hydroxide solution to 10 wt%, cooling to 5 ℃, and performing solid-liquid separation to obtain a sodium sulfate solid and a circulating regeneration desulfurizer. The circulating regenerated desulfurizer returns to the step (1) to desulfurize the next batch of materials. Through analysis, the lead powder is smelted to obtain a lead ingot with the purity of 99.85%.

Example 7

(1) 1 kg of waste lead plaster is contacted with an aqueous solution of a desulfurizing agent (potassium hydroxide solution with the weight percentage concentration of 10%) for desulfurization reaction, wherein the molar ratio of the consumption of the potassium hydroxide to the theoretical consumption required by the desulfurization reaction of the lead sulfate in the waste lead plaster is 2.5: 1. Carrying out solid-liquid separation after reacting for 30min under the conditions of heat preservation at 60 ℃ and stirring speed of 100 r/min to obtain desulfurized lead paste and desulfurized mother liquor containing potassium sulfate;

(2) uniformly mixing the desulfurized lead paste with 10 wt% of lead powder accelerant, pressing the mixture into a cathode with the thickness of 10 multiplied by 13 square centimeters and the thickness of 2.5 centimeters under the pressure of 3.5MPa in an oil press, solidifying the cathode for 12 hours, placing the cathode into an electrolytic bath with 20% of potassium hydroxide and an anode made of a nickel-plated steel plate coated with nickel-cobalt-iridium oxide on the market for electrolysis, controlling the current density to be 400 amperes per square meter, and electrolyzing to obtain metal lead and circulating electrolyte.

The cell pressure in the electrolysis process was 1.79V, and the current efficiency was 97%.

(3) And (2) supplementing a 30 wt% potassium hydroxide solution into the desulfurization mother liquor obtained in the step (1) to restore the concentration of the potassium hydroxide solution to 10 wt%, cooling to 5 ℃, and performing solid-liquid separation to obtain potassium sulfate solid and a circulating regeneration desulfurizer. The recycling regenerant is returned to step (1) to desulfurize the next batch. Through analysis, the lead powder is smelted to obtain a lead ingot with the purity of 99.92 percent.

Example 8

This example demonstrates the solidification-free direct solid-phase electrolysis lead recovery process of the present invention.

(1) And (2) contacting 10 kg of waste lead plaster with an aqueous solution of a desulfurizing agent (a potassium hydroxide solution with the weight percentage concentration of 10%) to perform a desulfurization reaction, wherein the molar ratio of the using amount of sodium hydroxide to the theoretical using amount of the lead sulfate in the waste lead plaster for the desulfurization reaction is 2.5: 1. Reacting for 30min at the temperature of 60 ℃ and the stirring speed of 100 rpm to obtain the mixed slurry of the desulfurized lead plaster and the desulfurized mother liquor containing sodium sulfate.

The electrolytic cell of the filter press type was obtained from a commercial filter press comprising two nickel plated anodes of 10X 13 square cm and a thickness of 2mm and a polypropylene frame of 10X 13 square cm and a thickness of 3cm embedded with a stainless steel plate of 0.5mm, the filter bag being a commercial polyester filter bag. Pumping the mixed slurry into a filter press type electrolytic tank by using a filter press material pump, pumping 1 kg of clear water filter cake for cleaning, compacting under 0.6MPa, pumping a small amount of 20 wt% NaOH solution as electrolyte, electrolyzing while keeping the filter cloth in a soaking state, pumping the desulfurization slurry into a filter press for an anode plate, and controlling the cathode current density to be 600Am^-2And at the moment, the initial cell pressure is 2.05V, the current efficiency is about 98%, and after constant current electrolysis until the cell pressure is reduced to 1.93V and gradually increased to 2.2V, the electrolysis is finished, the cathode plate is detached, and the cathode lead powder is obtained after the filter bag is removed. The analysis shows that the power consumption is about 565 degrees per ton of lead. The lead powder is smelted to obtain a lead ingot with the purity of 99.91 percent.

Example 9

To further illustrate the versatility of the present invention, the present embodiment uses 10 kg of waste lead paste from the starting battery of the automobile with sail L2-400. Through EDTA titration analysis, the lead plaster contains 36.3 percent of lead sulfate by mass, the molar ratio of potassium hydroxide solution to lead sulfate is controlled to be 2.05:1, and about 14 kilograms of potassium hydroxide solution with the weight percentage concentration of about 10 percent is prepared to react with the lead plaster at the temperature of 40 ℃ for 20min to obtain desulfurized lead plaster, potassium sulfate and slurry of residual potassium hydroxide.

The mixture slurry of the desulfurized lead plaster and the desulfurized mother liquor containing potassium sulfate is obtained through the separation process.

The electrolytic cell of the filter press type is taken from a manufactured filter press type and comprises two commercial nickel-plated anodes with the thickness of 2mm and 10 multiplied by 13 square centimeters, and a polypropylene frame with the thickness of 3cm and embedded with stainless steel plate cathodes with the thickness of 0.5mm, wherein the filter bag adopts a commercial polyester filter bag.Pumping the mixed slurry into a filter press type electrolytic tank by using a filter press material pump, pumping 10 kilograms of clear water to clean a filter cake, compacting under 0.6MPa, pumping a small amount of KOH solution with the concentration of 20 wt% as electrolyte, electrolyzing while keeping the filter cloth in a soaking state, pumping the desulfurization slurry into a filter press for an anode plate, and controlling the cathode current density to be 600Am^-2The average cell pressure in the electrolysis process is 2.03V, and the current efficiency is about 98 percent. And after the electrolysis is finished, the cathode plate is detached, and the cathode lead powder is obtained after the filter bag is removed. Through analysis, the electricity consumption is about 537 degrees electricity/ton lead. The lead powder is smelted to obtain lead ingots with the purity of 99.8 percent.

Example 10

(1) 1 kg of the waste lead plaster of the automobile battery in the embodiment 9 is subjected to desulfurization reaction with a sodium hydroxide solution with the weight percentage concentration of 12%, and the molar ratio of the usage of the sodium hydroxide to the theoretical usage of the lead sulfate in the waste lead plaster for desulfurization reaction is kept to be 2.1: 1. Carrying out solid-liquid separation after reacting for 30min under the conditions of heat preservation at 30 ℃ and stirring speed of 100 r/min to obtain desulfurized lead paste and desulfurized mother liquor containing sodium sulfate;

(2) mixing the desulfurized lead paste with 300 g of 15 wt% hydrogen peroxide solution to convert most of lead dioxide components in the desulfurized lead paste into lead oxide, then filtering the lead oxide, pressing the lead oxide into a cathode with the thickness of 2.5 cm and the thickness of 10 multiplied by 13 square cm under the pressure of 3MPa in an oil press, solidifying the cathode for 10 hours, placing the cathode in an electrolytic cell filled with an anode made of 20 wt% sodium hydroxide and a commercially available nickel-plated steel plate for electrolysis, and controlling the current density to be 400A/square meter to electrolyze to obtain metallic lead and circulating electrolyte.

The cell pressure in the electrolysis process was 1.93V, and the current efficiency was 95%. The electrolysis energy consumption of one ton of lead is calculated to be 471 degrees of electricity. The reduction of power consumption is facilitated by the reduction of the lead dioxide component to lead oxide and oxygen by the electrolysis promoter hydrogen peroxide, thereby reducing the power requirements of the electrolysis process.

(3) And (2) supplementing a 30 wt% sodium hydroxide solution into the desulfurization mother liquor obtained in the step (1) to restore the concentration of the sodium hydroxide solution to 10 wt%, cooling to 5 ℃, and performing solid-liquid separation to obtain a sodium sulfate solid and a circulating regeneration desulfurizer. The circulating regenerated desulfurizer returns to the step (1) to desulfurize the next batch of materials. Through analysis, the lead powder is smelted to obtain a lead ingot with the purity of 99.92 percent.

The preferred embodiments of the present invention have been described above in detail, but the present invention is not limited thereto. Within the scope of the technical idea of the invention, many simple modifications can be made to the technical solution of the invention, including combinations of various technical features in any other suitable way, and these simple modifications and combinations should also be regarded as the disclosure of the invention, and all fall within the scope of the invention.

Claims (10)

1. A method for recovering metallic lead by solid phase electrolytic reduction, the method comprising the steps of:

(1) contacting the waste lead plaster with a desulfurizing agent, and carrying out solid-liquid separation on a contacted mixture to obtain desulfurized lead plaster and desulfurized filtrate containing sulfate;

(2) mixing the desulfurized lead plaster with an electrolysis promoter to prepare a cathode, and placing the cathode in an electrolytic bath for electrolysis to obtain metal lead and circulating electrolyte;

the process optionally further comprises step (3): and (3) optionally supplementing a desulfurizing agent to the desulfurization filtrate, cooling and crystallizing, and then carrying out solid-liquid separation to obtain a sulfate crystal and a circulating regeneration desulfurizing agent.

2. The method according to claim 1, wherein in the step (1), the desulfurizing agent is at least one selected from sodium hydroxide, potassium hydroxide and ammonia water;

preferably, the molar ratio of the usage amount of the desulfurizing agent to the theoretical usage amount of the lead sulfate desulfurization reaction in the waste lead paste is 0.8-3: 1, preferably 1.0 to 2.5: 1;

preferably, in step (1), the temperature of the contacting is 0-120 ℃, preferably 30-100 ℃;

preferably, in step (1), the contact time is 5-120min, preferably 20-60 min.

3. The method of claim 1, wherein in step (2), the electrolysis promoter is selected from at least one of lead powder, carbon black, carbon powder, zinc powder, hydrogen peroxide, activated carbon, and graphene;

preferably, in the step (2), the amount of the electrolysis promoter is 0.05-35% by weight of the desulfurized lead paste, and more preferably 0.1-15%.

4. The method of claim 1, wherein the step (2) of mixing the desulfurized diachylon with an electrolysis promoter to form a cathode comprises: mixing the desulfurized lead plaster with an electrolysis accelerant, and pressing the mixture into a cathode by an oil press;

preferably, the oil press pressure is 0.1-10MPa, preferably 1-5 MPa.

5. The method according to any one of claims 1-4, wherein an anode and an electrolyte are provided in the electrolytic cell;

preferably, the anode is made of nickel-cobalt iridium oxide coated nickel plated steel plate;

preferably, the electrolyte is selected from at least one of an aqueous sodium hydroxide solution, an aqueous potassium hydroxide solution and aqueous ammonia;

preferably, in the step (2), the cell pressure of the electrolysis is 1.3-2.2V, preferably 1.5-1.85V;

preferably, in the step (2), the current density of the electrolysis is 30-5000A/m²Preferably 100-650A/m²。

6. The method of any one of claims 1-5, wherein the electrolysis of step (2) is performed in the presence of a magnetic field that effects directional movement of the electrolyte during electrolysis; preferably, the magnetic field effects upward movement of the electrolyte;

preferably, said magnetic field is achieved by placing a magnet under said electrolytic cell;

preferably, the direction of the magnetic field is perpendicular to the moving direction of ions in the electrolyte, and more preferably, the direction of the lorentz force generated by the magnetic field is consistent with the buoyancy direction of bubbles in the electrolysis process.

7. The process according to any one of claims 1 to 6, wherein in step (3), the desulfurization filtrate is subjected to optional replenishment of a desulfurizing agent so that the concentration of the desulfurizing agent is 2 to 25% by weight.

8. The method of claim 1, wherein the step (2) of mixing the desulfurized diachylon with an electrolysis promoter to form a cathode comprises: mixing the desulfurized lead plaster with the electrolysis accelerant, and pressing the desulfurized lead plaster and the electrolysis accelerant into a cathode by adopting a plate-and-frame filter press;

preferably, the pressure filtration pressure is 0.01-10MPa, and the filter cake thickness is 0.2-50 mm;

further preferably, the filter pressing pressure is 0.1-4.0MPa, and the filter cake thickness is 5-40 mm.

9. The method of claim 8, wherein a plate and frame comprising a stainless steel lining as the conductive cathode current collector is selected.

10. An electrolytic cell with a pressure filtration plate frame is provided with a cathode, an anode, a diaphragm and electrolyte;

the cathode is the cathode of claim 8 or 9;

the diaphragm is filter cloth of a plate-and-frame filter press;

the electrolyte is placed in the plate frame;

the anode is arranged between the cathode plate frames provided with the filter bags;

preferably, the electrolytic cell with the filter-press plate frame is used for enabling the desulfurization lead plaster to be subjected to solidification-free in-situ electrolysis in the plate frame to obtain lead powder.

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