CN101956214B - A method for recovering regenerated lead by electrolyzing alkaline lead-containing solution - Google Patents

Abstract

The present invention relates to a method for recovering regenerated lead by electrolyzing an alkaline lead solution, wherein a lead-containing alkaline electrolyte is directly obtained through a pre-catalytic conversion and an alkaline desulfurization leaching process. The electrolyte is graded and electrolyzed in an ion membrane electrolyzer to directly obtain high-purity metallic lead, and oxygen and sodium sulfate decahydrate are produced as byproducts. The method is an energy-saving new technology with a promising prospect for large-scale industrial application.

Description

A method for recovering regenerated lead by electrolyzing alkaline lead-containing solution

technical field

The invention relates to a method for recycling lead by alkaline electrolysis of a lead-containing solution, belonging to the field of hydrometallurgy for recycling lead from lead-containing materials and waste lead-acid batteries.

Background technique

Since the lead-acid battery was proposed by French engineer Plante in 1859, lead-acid battery has been widely used as a cheap and reliable rechargeable battery such as electric vehicles, automobiles, and uninterruptible UPS power supplies. In recent years, although there is competition from lithium-ion batteries and nickel-metal hydride batteries, lead-acid batteries have always been at the top of the secondary batteries, accounting for nearly 60% of the global output value of secondary batteries. According to the statistics of power supply-related industry associations, China's lead consumption reached more than 3.5 million tons in 2009, accounting for more than 23% of the world's total lead consumption. The large amount of toxic lead compounds contained in lead-acid batteries and the current relatively backward pyrolysis lead recycling technology have led to serious lead pollution in the recycling process of lead-acid batteries, such as the "blood lead" incident in North China in 2009. Since lead-acid batteries are currently the dominant power source for cars and electric bicycles and will continue to exist for a long period of time in the future, how to efficiently recycle lead-acid batteries so as to effectively realize the regeneration and recycling of lead resources and greatly reduce The pollution of lead to the environment has become an urgent problem to be solved.

The lead in lead-acid batteries is mainly the metal lead on the plate grid and tabs and the lead paste in the positive and negative electrodes. The lead in the grid and lug is simple lead, which can be recovered by conventional methods such as smelting. Lead paste accounts for more than 55% of the total lead in batteries and has complex components. Lead paste is mainly a mixture of Pb, PbSO ₄ , PbO and PbO ₂ . How to find an effective way to reduce the lead in the lead paste to obtain pure metallic lead has become a difficult point in the secondary lead process.

The current general method is pyrometallurgy, and the most representative company in the world is Italy's Engitec (Engitec). A large amount of sulfur dioxide, lead dust and lead-containing waste residues are easily produced in the pyrometallurgy process, which not only reduces the recovery efficiency of lead, but also causes serious lead pollution to the environment.

Relatively speaking, hydrometallurgy is a relatively clean and efficient smelting method, and many researchers have been trying to use it to effectively reduce the lead paste of lead-acid batteries. The hydrometallurgy that has been reported so far can be divided according to the different technical routes and processing media: 1) acid soluble lead salt electrodeposition technology; 2) liquid alkali-potassium sodium tartrate solution electrodeposition technology; and 3) solid phase electrolysis technology.

The acidic soluble lead salt electrodeposition technology can refer to the USBM process (Journal ofMetals, 1985,37 (2): 79-83) reported in 1985, the U.S. Patent US.Patent 4769116 of Italy Engitec Company and the U.S. Patent US. Patent 4451340. The above process is characterized by firstly using (NH ₄ ) ₂ CO ₃ or Na ₂ CO ₃ as a desulfurizing agent for desulfurization conversion, and then adding a reducing agent to reduce PbO ₂ in the lead paste. The generated PbO and PbCO ₃ are dissolved with HBF ₄ or H ₂ SiF ₆ to obtain a soluble lead salt electrolyte. Due to the high concentration of lead fluoroborate (silicate) and fluoroborate (silicon) acid, the lead ions in the waste liquid seriously pollute the environment, and the fluorine-containing compound solution itself is a highly toxic compound, which is very harmful to the body of the operator. . In addition, in the process of electrolysis, a large amount of lead dioxide by-products are precipitated on the anode plate, which reduces the recovery efficiency of lead and leads to a large secondary treatment load. At present, the electrolyzer voltage of this process is 2.7-3.2V, and the energy consumption per ton of lead is generally 700-950KWh. Although this method has high pollution and high energy consumption, because the purity of the regenerated lead can reach more than 99.99%, domestic units are still trying to industrialize the method.

In terms of alkaline electrolysis, Chen Weiping of Hunan University proposed a technology of "electrodepositing lead from liquid alkali-potassium sodium tartrate solution" (Chen Weiping, A new technology for wet recovery of waste lead battery fillers, Journal of Hunan University, 1996, 23 (6): 111-116). The characteristic of this process is that a large amount of lead dioxide is produced by the anode, and the current density of the cathode is low, generally only 150-250A/m ² . Moreover, the lead obtained by electrolysis is a kind of sponge lead with a high specific surface area, which is easy to cause short circuit of cathode and anode and oxidation in the melting process. Because potassium sodium tartrate is used to complex lead oxide, a large amount of lead tartrate needs to be consumed in the electrolysis process. The introduction of potassium and sodium tartrate increases the solution resistance and electrolyzer pressure, and the organic lead compound waste liquid is highly toxic and difficult to treat. These factors lead to the low space-time yield of the method, which requires a relatively high equipment footprint and investment and operation costs.

Compared with the wet process of carrying out complex conversion reactions in the above-mentioned acid-base solution and then electrolytic reduction, the wet process of directly performing electrolytic reduction in sulfuric acid electrolyte using the principle of lead-acid battery formation has also been reported. In 1985, the German patent (DE3402338A) and the British patent (1368423 and 1428957) successively reported the principle of forming the negative plate of the lead-acid battery, fixing the lead paste of the waste battery on a metal cathode, and performing electrolytic reduction in dilute sulfuric acid solution as the cathode , to get metallic lead and sulfuric acid. This method is limited by the solubility of lead sulfate in dilute acid, and the current density and lamination thickness are all small, resulting in low utilization rate of equipment, small cathode reduction depth, high tank pressure, and large energy consumption; and the concentration of recovered sulfuric acid is only 10 % or so, thus limiting industrial promotion. Chinese patent ZL200710157084.X (a method for electrolytic reduction of lead resources in lead-containing plaster sludge for regeneration of waste lead-acid batteries) uses a pump to pour lead sludge made of lead paste into an electrolytic cell containing sulfuric acid for continuous electrolysis. Continuous production can be directly realized and lead powder can be obtained. The disadvantage is that the voltage of the electrolyzer is as high as 2.92-3.12V, which makes the direct electrolysis energy consumption as high as 920KWh/t(Pb). The subsequent Chinese patent ZL200810114308.3 (method for recovering waste lead-acid battery lead by acid-type wet electrolysis) uses dual power sources and activators to greatly increase the reduction speed and efficiency of lead sulfate, and realizes lead-acid battery paste and board. The direct reduction of the grid realizes the power consumption of 600-700KWh per ton of lead, and can recover sulfuric acid with a concentration of up to 30%. The disadvantage is that this process requires separate electrolytic treatment of the monomers of the lead-acid battery during the electrolysis process, and it is not easy to realize large-scale industrial production.

Alkaline solid-phase pasting technology for regenerated lead can be found in the Chinese patent publication CN88103531 of Lu Keyuan, a researcher of the Chinese Academy of Sciences, and solid-phase electrolysis-a new technology for regenerated lead (Nonferrous Metal Regeneration and Utilization, 2005, (12): 16-17). The feature of this invention is that first, the positive and negative lead paste and water are mixed into a viscous paste, and coated on a metal mesh to make a cathode, and the lead-containing material is electrolyzed in an alkaline medium by intermittent operation to obtain a paste containing Lead powder of lead sulfate. The disadvantage is that the process of this method is complicated. After the electrolytic reduction is completed, the cathode plate needs to be hoisted out from the electric cell and the lead sludge is taken out, which leads to cumbersome loading and unloading of materials and excessive labor workload. Some new works have thickened the coating in order to reduce the amount of loading and unloading. The problem is that the current efficiency is relatively low, generally around 85%, and the reduction process is not complete, and 2% lead sulfate that is not fully reduced is included.

The recent Chinese patent ZL02132647.9 reported in 2004 overcomes the shortcoming of the former with thin stockpiles, and proposes to use a rectangular frame with a grid structure as the cathode, thereby increasing the amount of paste applied. The method of constant voltage electrolysis is used to overcome the shortcomings of the original single constant current electrolysis, and the end point of electrolysis is displayed by the change of current in the process of constant voltage electrolysis. The disadvantage of this method is that due to the complex composition of waste lead materials, the resistance of the paste itself has significant differences due to the differences in the composition of Pb and _PbO2 between batches of materials, so that the actual electrolysis current varies greatly under constant voltage electrolysis conditions. It is difficult to determine the end point of electrolysis by the drop of electrolysis current to 15-35% of the peak current, so there are still a large amount of unelectrolyzed lead compounds in the actual product, and the electrolysis rate is usually 85-96%. Due to the characteristics of the constant voltage electrolysis current floating change, the actual current in the mid-term of electrolysis is very large, and a large part of the voltage drops on the polarization of the two electrodes and the internal resistance of the solution, which makes the actual power consumption of this method very uneconomical, per ton Lead power consumption is 547-880KWh. Recent work also includes the Chinese invention patent (ZL200910024467.9) of Professor Lei Lixu of Southeast University, which uses mechanical methods to separate the positive and negative plates, and then performs electrolysis in sulfuric acid or NaOH solution to obtain lead and lead dioxide powders. . The disadvantage of this method is that a large number of manual sorting processes are required, and it is especially difficult to sort the positive plates that have been swollen and softened. In addition, the process simultaneously produces equal amounts of lead and lead dioxide powder, resulting in an actual lead recovery efficiency of only 50%.

A comprehensive analysis of the latest wet process at home and abroad compared with the current mature pyrotechnic process found that although the current wet process has improved the recovery rate of lead to a certain extent, the existing problems mainly include:

(1) In the process of electrolytic recovery of lead-containing waste, the complexing process of lead oxide needs to use complexing agent;

(2) The DC power consumption of acid electrolysis is relatively high, and the power consumption per ton of recycled lead is as high as 600-1000KWh, which is 550KWh higher than that of the fire method;

(3) Acidic electrolysis is highly corrosive, making it difficult for manufacturers to accept;

(4) Alkaline direct electrolysis has many by-products, such as by-product PbO ₂ , and the treatment process is complex; and

(5) The alkaline solid-phase pasting method cannot be continuously mechanized, which causes difficulties in actual industrial production.

Contents of the invention

An object of the present invention is to provide a method for recovering regenerated lead by electrolyzing alkaline lead-containing solution, which can directly complex lead oxide and alkaline solution without using a complexing agent.

Another object of the present invention is to provide a method that can significantly reduce energy consumption and regenerate lead by electrolyzing alkaline lead-containing solution.

Yet another object of the present invention is to provide a method for reclaiming regenerated lead by electrolytic alkaline lead-containing solution that prevents the formation of by-product lead dioxide at the anode, thereby improving the recovery rate of lead and generating industrially valuable by-products.

Another object of the present invention is to provide a method for recovering regenerated lead by electrolyzing alkaline lead-containing solution, which can recycle part of the raw materials.

According to one aspect of the present invention, the present invention provides a method for reclaiming secondary lead from lead-containing waste, comprising: (1) converting lead and oxides thereof in lead-containing waste into lead sulfate; (2) converting the lead-containing waste into lead sulfate; The lead sulfate is reacted with excess NaOH solution to generate Na ₂ [Pb(OH) ₄ ], or the lead sulfate and the lead sulfate present in the lead-containing waste are reacted with excess NaOH solution to generate Na ₂ [Pb( OH) ₄ ] to obtain a mixed solution containing Na ₂ [Pb(OH) ₄ ] and NaOH; and (3) selective ion electrolysis of the mixed solution to generate metallic lead and oxygen; wherein, the The excess NaOH solution concentration is 3-10 mol/L, preferably 5.5 mol/L, and the reaction temperature is 40-116°C, preferably 105°C.

In one embodiment, the lead waste includes lead paste from spent lead-acid batteries, PbO waste, Pb waste, _PbO2 waste, Pb(SO) ₄ waste, other lead-containing waste from the production of lead-containing batteries, and others Lead-containing waste in field production.

In one embodiment, lead and its oxides in the lead paste of the waste lead-acid battery are converted into lead sulfate by reacting with a mixed solution of ferrous perchlorate, perchloric acid and sulfuric acid. During the reaction process, the present invention utilizes a platinum wire electrode and a mercurous sulfate electrode inserted in the reactor to monitor the degree of progress of the reaction. Preferably, the concentrations of the ferrous perchlorate, perchloric acid and sulfuric acid are respectively 0.05-1.5mol/L, 0.1-3mol/L and 0.5-12mol/L, and the reaction temperature of the reaction is 30-95°C .

In one embodiment, the sulfuric acid is spent sulfuric acid in waste batteries, added sulfuric acid, or a mixture of spent sulfuric acid and added sulfuric acid.

In one embodiment, wherein the electrolysis in the step (2) is staged electrolysis, the staged electrolysis includes constant current electrolysis and subsequent pulse electrolysis, wherein the condition of the constant current electrolysis is: electrolyte temperature 60 ～120°C; cathode current density 150～3500A/m ² ; anode current density 400～5000A/m ² ; ionic membrane apparent current density 300～4500A/m ² ; and the condition of the pulse electrolysis is: the electrolyte temperature is 40～115℃; cathode current density is 60～2000A/m ² ; anode current density is 100～2900A/m ² ; ion membrane apparent current density is 30～2000A/m ² ; pulse duration is 0.01～1s; The ratio is 1:1 to 1:2.

In one embodiment, the staged electrolysis is performed sequentially in the constant-flow cationic membrane electrolyzer and the pulse cationic membrane electrolyzer respectively, or sequentially in the same cationic membrane electrolyzer.

In one embodiment, NaOH·2H ₂ O is further added to the mixed solution after electrolysis in step (3) to precipitate Na ₂ SO ₄ ·10H ₂ O, Na ₂ SO ₄ ·10H ₂ O is separated, and the main The remaining mixed solution containing NaOH is recycled to step (2).

According to another aspect of the present invention, there is provided a method for reclaiming secondary lead from PbO waste, comprising: (1) reacting PbO waste with excess NaOH solution to generate Na ₂ [Pb(OH) ₄ ] to obtain Na ₂ A mixed solution of [Pb(OH) ₄ ] and NaOH; and (2) electrolyzing the mixed solution to generate metallic lead, wherein the excess NaOH solution concentration in step (1) is 3-10mol/L, and the The temperature of said reaction is 60～115 ℃.

In one embodiment, the excess NaOH concentration is 5.5 mol/L, and the reaction temperature is 105°C.

In one embodiment, the electrolysis in the step (2) is staged electrolysis, and the staged electrolysis includes constant current electrolysis and subsequent pulse electrolysis, wherein the condition of the constant current electrolysis is: electrolyte temperature 60 ～120°C; cathode current density 150～3500A/m ² ; anode current density 400～5000A/m ² ; ionic membrane apparent current density 300～4500A/m ² ; and the condition of the pulse electrolysis is: the electrolyte temperature is 40～115℃; cathode current density is 60～2000A/m ² ; anode current density is 100～2900A/m ² ; ion membrane apparent current density is 30～2000A/m ² ; pulse duration is 0.01～1s; The ratio is 1:1 to 1:2.

In one embodiment, the staged electrolysis is performed sequentially in the constant-flow cationic membrane electrolyzer and the pulse cationic membrane electrolyzer respectively, or sequentially in the same cationic membrane electrolyzer.

In one embodiment, further comprising recycling the remaining mixed solution mainly comprising NaOH after electrolysis in step (2) to step (2).

The method for recovering regenerated lead by alkaline electrolysis of lead-containing solution of the present invention can efficiently convert lead-containing waste into high-purity lead without producing by-products such as PbO ₂ , significantly reduces energy consumption, and avoids the use of toxic and harmful substances in the recovery process And the secondary pollution caused by it, and realized the continuous fully enclosed industrial production.

Description of drawings

Fig. 1 is a method flowchart of an embodiment of the present invention;

Fig. 2 is the schematic diagram of ion-exchange membrane electrolyzer of the present invention.

Detailed ways

Exemplary embodiments will be described in more detail hereinafter with reference to the accompanying drawings. The drawings described are intended to illustrate the invention, not to limit it.

FIG. 1 is a flowchart of a method according to an embodiment of the present invention. Referring to Figure 1, waste lead-acid batteries are crushed and screened to obtain waste sulfuric acid, lead paste and grids. The lead plaster is converted into lead sulfate by reaction with sulfuric acid (waste sulfuric acid and added sulfuric acid) under the catalysis of catalyst ferrous perchlorate and perchloric acid, and the lead sulfate is mixed with ferrous perchlorate, ferric perchlorate and Mother liquor separation of perchloric acid. Iron powder or iron filings are added to this mother liquor to reduce the ferric perchlorate therein, and then the mother liquor is recovered for the next cycle. Add sodium hydroxide solution to the obtained lead sulfate, and react at a higher temperature to form a solution containing Na ₂ [Pb(OH) ₄ ], NaOH and Na ₂ SO ₄ . After separating this solution, constant current electrolysis and pulse electrolysis were performed sequentially to obtain lead at _the cathode and oxygen at the anode, as well as NaOH and _Na2SO4 in the electrolyte. NaOH·2H ₂ O is added to the electrolytic solution containing NaOH and sodium sulfate after the staged electrolysis process is completed to precipitate sodium sulfate in the electrolytic solution, and the precipitated sodium sulfate is filtered. The remaining NaOH solution is recovered for the next cycle.

The invention provides a method for recovering regenerated lead by electrolyzing alkaline lead-containing solution. Specifically, the present invention provides a method for recovering secondary lead from lead-containing waste. The lead-containing waste includes, for example, lead paste in waste lead-acid batteries, PbO waste, Pb waste, _PbO2 waste, Pb(SO) ₄ waste, other lead-containing waste in the production of lead-containing batteries, and other lead-containing wastes in the production of other fields. lead-containing waste, etc. Hereinafter, the present invention will be described in detail by taking recovery of secondary lead from the lead paste of waste lead-acid batteries as an example.

In one embodiment, the present invention provides a method for recovering regenerated lead from the lead paste of waste lead-acid batteries, comprising: a process of separating lead paste from waste lead-acid batteries, a process of catalytically converting the lead paste, Alkaline leaching purification process, staged electrolysis process in ion-exchange membrane electrolyzer and regenerating electrolytic mother liquor back to the alkaline leaching purification step.

(1) Process of separating lead paste:

The waste lead-acid battery is crushed by a conventional method such as a crusher, and separated by a conventional separation method such as density difference to obtain lead paste, grids, separators, casings, and waste sulfuric acid. Keep the separated lead plaster and waste sulfuric acid for later use.

(2) Catalytic conversion process:

The raw material of the catalytic conversion process is lead paste, wherein the lead in the lead paste exists as a mixture of Pb, PbSO ₄ , PbO and PbO ₂ . In this process, Pb, PbO and _PbO2 in the lead paste are converted into lead sulfate by reacting with sulfuric acid under the catalysis of ferrous perchlorate and perchloric acid.

The catalytic conversion process includes the following steps:

(1) The lead plaster is reacted with a mixed solution containing ferrous perchlorate, perchloric acid and sulfuric acid, so that Pb, PbO and _PbO in the lead plaster generate lead sulfate, wherein ferrous perchlorate, perchloric acid The concentrations of acid and sulfuric acid are respectively 0.05-1.5mol/L, 0.1-3mol/L and 0.5-12mol/L, and the reaction temperature is 30-95°C. Preferably, the concentrations of ferrous perchlorate, perchloric acid and sulfuric acid are 0.5 mol/L, 0.5 mol/L and 5 mol/L respectively, and the reaction temperature is 80°C.

In the reaction of step (1), H ₂ SO ₄ can be spent sulfuric acid in the waste battery, added sulfuric acid, or a mixture of spent sulfuric acid and added sulfuric acid. Ferrous perchlorate is the main catalyst, and perchloric acid acts as an activation and co-catalyst. Because the reaction of step (1) involves the generation of insoluble PbSO ₄ , and ferrous perchlorate and perchloric acid can generate highly soluble Pb(ClO ₄ ) ₂ with Pb, PbO and PbO ₂ in the reaction process, thus Selecting ferrous perchlorate and perchloric acid as a catalyst can accelerate the reaction process.

The specific reaction is as follows:

PbO ₂ +2Fe(ClO ₄ ) ₂ +4HClO ₄ ＝Pb(ClO ₄ ) ₂ +2Fe(ClO ₄ ) ₃ +2H ₂ O (I)

Pb+2Fe(ClO ₄ ) ₃ ＝Pb(ClO ₄ ) ₂ +2Fe(ClO ₄ ) ₂ (II)

PbO+2HClO ₄ ＝Pb(ClO ₄ ) ₂ +H ₂ O (III)

3Pb(ClO ₄ ) ₂ +3H ₂ SO ₄ ＝3PbSO ₄ +6HClO ₄ (IV)

The overall reaction formula is:

Pb+PbO+PbO ₂ +3H ₂ SO ₄ ＝3PbSO ₄ +3H ₂ O (V)

In order to ensure that the above process is carried out completely, a platinum wire electrode and a mercurous sulfate electrode can be inserted into the reactor to monitor the reaction process after the reaction has been carried out for a period of time. When the potential of the two electrodes is higher than 0.30-0.35V, a small amount of ferrous perchlorate and perchloric acid solution can be added to the reaction solution to promote the reaction. When the potential drops to between 0.0 and 0.3V, it indicates that the reaction is basically completed.

When the residual Pb and PbO ₂ in the lead paste are completely matched (that is, Pb:PbO ₂ is 1:1), Fe(ClO ₄ ) ₂ and HClO ₄ are not consumed before and after the reaction. Due to the particularity of waste batteries, the residual Pb and PbO ₂ in the battery are not exactly 1:1, usually 0-15% excess PbO ₂ , so ferrous perchlorate may be oxidized by residual PbO ₂ to generate perchloric acid iron.

The reaction solution in the post-reaction step (1) comprises lead sulfate, ferrous perchlorate, ferric perchlorate, perchloric acid and other impurities in the lead plaster, and the lead sulfate in the described reaction solution includes being present in the lead plaster PbSO ₄ and the PbSO ₄ generated in the step (1).

(2) The reaction solution in the step (1) is subjected to pressure filtration or centrifugation to obtain lead sulfate and a mother liquor comprising ferrous perchlorate, ferric perchlorate and perchloric acid. The resulting lead sulfate is used for subsequent use.

(3) add iron powder or iron filings in the mother liquor that comprises ferrous perchlorate, ferric perchlorate and perchloric acid to be reduced to ferrous perchlorate with ferric perchlorate, return to step ( 1) for recycling.

The specific reaction is as follows:

Fe+2Fe(ClO ₄ ) ₃ ＝3Fe(ClO ₄ ) ₂ (VI)

(3) Alkaline leaching purification process:

The raw material of the alkaline leaching purification process is the lead sulfate obtained in the above catalytic conversion process. During this process, lead sulfate reacts with the added sodium hydroxide solution at a higher temperature to form Na ₂ [Pb(OH) ₄ ].

The alkaline leaching purification process includes the following steps: excess NaOH solution reacts to generate Na ₂ [Pb(OH) ₄ ], thereby obtaining a mixed solution of Na ₂ [Pb(OH) ₄ ] and NaOH

(1) Reaction of lead sulfate and excess NaOH solution to generate Na ₂ [Pb(OH) ₄ ] and Na ₂ SO ₄ to obtain a mixed solution containing Na ₂ [Pb(OH) ₄ ], Na ₂ SO ₄ and NaOH. During the reaction, the concentration of NaOH is controlled to be 3-10 mol/L, the reaction temperature is 40-116° C., and the reaction time is 2-7 hours. The NaOH concentration is preferably 5-9 mol/L, most preferably 5.5 mol/L. The reaction temperature is preferably above 80°C, most preferably above 105°C. The reaction time is preferably 4 hours.

In step (1), lead sulfate first reacts with NaOH solution to generate Pb(OH) ₂ , and then complexes Pb(OH) ₂ with NaOH to generate Na ₂ [Pb(OH) ₄ ]. The specific reaction is as follows:

PbSO ₄ +2NaOH=Na ₂ SO ₄ +Pb(OH) ₂ (VII)

Pb(OH) ₂ +2NaOH=Na ₂ [Pb(OH) ₄ ] (VIII)

(2) Settling, filtering and purifying the mixed solution obtained in step (1) to further remove impurities therein. The purified mixed solution of Na ₂ [Pb(OH) ₄ ], NaOH and Na ₂ SO ₄ is ready for use.

The inventors of the present invention have found that Na ₂ [Pb(OH) ₄ ] formed by the complexation of NaOH and Pb(OH) ₂ (or PbO) has a high solubility at a relatively high temperature (preferably above 105°C), which can reach 95g /L above the concentration. This concentration meets the needs of industrial electrolysis. However, the complexation of NaOH with Pb(OH) ₂ (or PbO) was usually studied at a lower temperature range. In this temperature range, Pb(OH) ₂ (or PbO) has very low solubility in NaOH solution, or needs to add complexing agent potassium sodium tartrate to complex PbO and then electrolyze, as in the background technology "liquid alkali-potassium tartrate Electrodeposition of lead from sodium solution". The inventors of the present invention found that by controlling the concentration of NaOH to 3-10 mol/L, especially 5.5 mol/L, NaOH can be prevented from boiling even at 122° C. under normal pressure. At the same time, it was found that when PbO was close to the boiling point of water, the solubility of PbO increased sharply due to the supercritical effect.

Therefore, the present invention employs direct complexation of NaOH with Pb(OH) ₂ (or PbO) at higher temperature to form Na ₂ [Pb(OH) ₄ ]. The advantages of this method are:

(1) The generated Na ₂ [Pb(OH) ₄ ] has high solubility at relatively high temperature and can be used in the subsequent electrolysis process, thus meeting the needs of industrial electrolysis;

(2) Overcome a large amount of lead dioxide by-product at the anode in the current non-selective electrolysis process, which reduces the recovery efficiency of lead;

(3) This method does not need to use complexing agents such as potassium sodium tartrate, so the problems of increased solution resistance and waste liquid treatment due to the addition of complexing agents will not occur, saving raw material costs;

(4) The high concentration of NaOH greatly improves the conductivity, thereby reducing the pressure of the electrolytic cell.

(4) Staged electrolysis process:

The raw material (ie, electrolyte) of the staged electrolysis process is the mixed solution containing Na ₂ [Pb(OH) ₄ ], NaOH and Na ₂ SO ₄ obtained in the alkaline leaching purification process. The segmented electrolysis process is carried out in an ion-exchange membrane electrolyzer, and sequentially includes constant current electrolysis and pulse electrolysis. The constant current electrolysis can be carried out in one ionic membrane electrolyzer first, and then transferred to another electrolyzer for pulse electrolysis. The difference between the two ionic membrane electrolyzers is that the power supply is different. Constant current electrolysis and pulse electrolysis can also be performed sequentially in the same electrolyzer by replacing the power supply. The result of electrolysis is to obtain lead at the cathode and oxygen at the anode.

Fig. 2 is the schematic diagram of ion-exchange membrane electrolyzer of the present invention. With reference to Fig. 2, ionic membrane electrolyzer of the present invention comprises direct current (or pulse) power source 1; Contain Na ₂ [Pb(OH) ₄ ], NaOH and Na ₂ SO ₄ Electrolyte inlet 2; Lead cathode plate 3; Electrodeposition Lead 4; lead concentration sensor 5; electrolyte outlet 6 containing NaOH and Na ₂ SO ₄ ; cationic membrane 7 (such as Nafion cationic membrane); nickel-plated anode 8; NaOH storage tank 9; crystal NaOH storage tank 10.

The staged electrolysis process includes the following steps:

(Taking the use of constant flow cationic membrane electrolyzer and pulsed cationic membrane electrolyzer as an example)

(1) Inject the electrolyte solution containing Na ₂ [Pb(OH) ₄ ], NaOH and Na ₂ SO ₄ into a constant-current cationic membrane electrolyzer for constant-current electrolysis, wherein the conditions for constant-current electrolysis are: the temperature of the electrolyte is 60～120℃, preferably 65～105℃, more preferably 75～100℃; cathode current density is 150～3500A/m ² , preferably 300～1000A/m ² , more preferably 400A/m ² ; anode current density is 400～ 5000A/m ² , preferably 500-4000A/m ² ; the apparent current density of the ionic membrane is 300-4500A/m ² ;

(2) When the concentration of Pb(OH) ₄ ^2- decreases to 20~35g/L (calculated as lead oxide), inject the electrolyte containing Na ₂ [Pb(OH) ₄ ], NaOH and Na ₂ SO ₄ into the Perform pulse electrolysis in a pulse type electrolyzer until the concentration of Pb(OH) ₄ ^2- is less than 3-5g/L (calculated as lead oxide), wherein the condition of pulse electrolysis is: the temperature of the electrolyte is 40-115°C, preferably 65- 105°C, more preferably 85-100°C; cathode current density 60-2000A/m ² , preferably 300-1500A/m ² ; anode current density 100-2900A/m ² , preferably 500-2500A/m ² ; ionic membrane The apparent current density is 30-2000A/m ² , preferably 50-1500A/m ² ; the pulse duration is 0.01-1s; the duty ratio is 1:1-1:2.

Under the action of an electric field, Pb(OH) ₄ ^2- is deposited on the lead cathode sheet 3 to form electrodeposited lead 4, ^OH- produces oxygen (not shown) at the nickel-plated anode 8, and Na ⁺ is released from the anode through the selective cation membrane move towards the cathode. NaOH is supplemented at the anode end during the staged electrolysis process. When the NaOH in the NaOH storage tank is consumed too much, add crystalline NaOH to the NaOH storage tank. The electrolytic solution after staged electrolysis contains NaOH and sodium sulfate.

The specific reaction is as follows:

Cathode: [Pb(OH) ₄ ] ^2- +2e=Pb+4OH ^- (IX)

Ion membrane: 2Na ⁺ _(anode) → 2Na ⁺ _(cathode) (X)

Anode: 2OH ^- -2e＝1/2O ₂ +H ₂ O (XI)

Total reaction: Na ₂ [Pb(OH) ₄ ]=Pb+1/2O ₂ +2NaOH (XII)

The present invention utilizes the principle of selective permeation of the cationic membrane, that is, the cationic membrane allows Na ⁺ to migrate from the anode to the cathode, thereby increasing the NaOH concentration at the cathode, and blocking [Pb(OH) ₄ ] ^2- from the migration of the cathode to the anode, Therefore, the by-product lead dioxide is prevented from being generated at the anode during the electrolysis process, and the industrially useful by-product oxygen can be generated at the anode.

The staged electrolysis adopted in the present invention can improve electrolysis efficiency and reduce power consumption. Most of the lead is rapidly electrolytically deposited during constant current electrolysis. During pulse electrolysis, high current electrolysis is used for a short time (0.1s), and then rest for a period of time (0.5s), so that the electrolyte around the electrode can be enriched to the electrode surface, and then electrolyze again in the next cycle. Through the pulse electrolysis method, energy-saving and thorough electrolysis can be realized in the low-concentration lead ion solution. Since pulse electrolysis is a discontinuous current, it ensures the efficiency of electrolysis on the one hand and the depth of electrolysis on the other hand. If it is continuous high-current constant-current electrolysis, the water in the cathode will be reduced during the electrolysis process and a large amount of hydrogen will be produced by-product, resulting in reduced efficiency.

In the present invention, adding NaOH at the anode end can maintain the Na ⁺ concentration at the anode end, thereby maintaining the continuous progress of the electrolysis reaction, and the added NaOH can be directly used as a raw material for the next cycle to complex PbO.

In the present invention, adding crystallized NaOH to the NaOH storage tank during the staged electrolysis can not only increase the concentration of NaOH in the NaOH storage tank, but also prevent exothermic and boiling phenomena caused by direct NaOH solid addition. Crystalline NaOH (NaOH·2H ₂ O) is obtained, for example, by treating NaOH solid with ice water.

(5) Cycle process:

The sodium sulfate in the electrolytic solution is further precipitated by adding NaOH·2H ₂ O to the electrolytic solution containing NaOH and sodium sulfate after the segmental electrolysis process is completed, and the precipitated sodium sulfate is filtered. The remaining NaOH solution is returned to the above alkali leaching purification process for recycling.

The looping process includes the following steps:

(1) Add crystalline NaOH to the electrolyte solution containing NaOH and sodium sulfate after electrolysis, and gradually precipitate Na ₂ SO ₄ ·10H ₂ O crystals;

(2) After the electrolyte solution is filtered through the sodium sulfate crystals, the electrolyte solution (mainly NaOH) is returned to the above-mentioned alkali leaching purification process for recycling.

The present invention can make to adding crystallized NaOH during the circulation process: (1) under the same ion effect, impel the sodium sulfate in the electrolytic solution to separate out, reach the purpose of non-evaporation directly reclaiming sodium sulfate; (2) the added NaOH directly serves as The raw material of the next cycle is used to complex PbO; (3) Adding crystalline NaOH hardly produces exothermic and boiling phenomena, which is more conducive to the precipitation of sodium sulfate than non-crystalline NaOH.

In another embodiment, the present invention provides a method for recovering secondary lead from lead waste mainly containing PbO, comprising: an alkaline leaching purification process, a staged electrolysis process in an ion-exchange membrane electrolyzer and making the electrolysis Mother liquor regeneration returns to the circulation process of alkali leaching purification step.

(1) Alkaline leaching purification process:

The alkaline leaching purification process includes the following steps:

(1) Directly react lead waste mainly containing PbO with excess NaOH solution to generate Na ₂ [Pb(OH) ₄ ], thereby obtaining a mixed solution of Na ₂ [Pb(OH) ₄ ] and NaOH. During the reaction, the NaOH concentration is controlled to be 3-10 mol/L, the reaction temperature is 60-115° C., and the reaction time is 3-8 hours. The NaOH concentration is preferably 5-9 mol/L, most preferably 5.5 mol/L. The reaction temperature is preferably 80-110°C, most preferably 105°C. The reaction time is preferably 4 hours.

The specific reaction is as follows:

PbO+H ₂ O+2NaOH=Na ₂ [Pb(OH) ₄ ]

(2) Settling, filtering and purifying the mixed solution obtained in step (1) to further remove impurities therein. The purified mixed solution of Na ₂ [Pb(OH) ₄ ] and NaOH is ready for use.

(2) Staged electrolysis process:

The staged electrolysis process includes the following steps:

(Take the same ionic membrane electrolyzer using different power sources as an example)

(1) Inject the mixed solution of Na ₂ [Pb(OH) ₄ ] and NaOH into the ion-exchange membrane electrolyzer for constant current electrolysis, wherein the condition of constant current electrolysis is: the temperature of the electrolyte is 60-120°C, preferably 65-105 °C, more preferably 75-100°C; cathode current density is 150-3500A/m ² , preferably 300-1000A/m ² , more preferably 400A/m ² ; anode current density is 400-5000A/m ² , preferably 500-4000A /m ² ; the apparent current density of the ionic membrane is 300-4500A/m ² ;

(2) When the Pb(OH) ₄ ^2- concentration drops to 20-35g/L (calculated as lead oxide), replace the constant current power supply with a pulse power supply to continue pulse electrolysis until the Pb(OH) ₄ ^2- concentration Less than 3-5g/L (calculated as lead oxide), wherein the pulse electrolysis conditions are: electrolyte temperature is 40-115°C, preferably 65-105°C, more preferably 85-100°C; cathode current density is 60-2000A/ m ² , preferably 300-1500A/m ² ; the anode current density is 100-2900A/m ² , preferably 500-2500A/m ² ; the apparent current density of the ionic membrane is 30-2000A/m ² , preferably 50-1500A/m ² ; The pulse duration is 0.01~1s; the duty ratio is 1:1~1:2.

Under the action of an electric field, Pb(OH) ₄ ^2- deposits on the cathode to form lead, and ^OH- produces oxygen at the anode. The electrolyte solution after the staged electrolysis is completed contains NaOH.

(3) Cycle process:

The looping process includes the following steps:

The electrolyte solution containing NaOH is returned to the above alkali leaching purification process for recycling.

Example:

The method of the present invention will be further described below through specific examples.

Example 1

Get 10 specifications purchased on the market and be 12V, 12Ah waste lead-acid batteries for electric vehicles, the total weight of the battery pack is 45.5 kg. The specific implementation process is as follows:

1) Put 10 batteries into a crusher after discharge treatment, and then separate them in the water phase by using the density difference to obtain lead paste, grids, waste sulfuric acid, separators and shells.

2) Put the lead paste out of the pressure filter into the crusher and ball mill for crushing, and then sieve it with a 60-mesh stainless steel screen. through a sieve.

3) Take 40L of the waste sulfuric acid obtained in the process of (1) and adjust it to contain 5mol/L H ₂ SO ₄ , 0.5mol/L Fe(ClO ₄ ) ₂ and 0.5mol/L HClO ₄ after adding a small amount of concentrated sulfuric acid. Get 26 kg of lead plaster powder obtained by sieving in the process of (2) and waste sulfuric acid solution and mix evenly, and stir at 80° C. for 5 hours. During this process, lead, lead oxide and lead dioxide in the lead paste are gradually converted into lead sulfate under the catalysis of ferrous perchlorate and perchloric acid. At this time, the potential detection was 0.42V, indicating that there was a small amount of lead dioxide remaining in the reaction solution, and 2L of a mixed solution containing 3mol/L HClO ₄ and 0.5mol/L Fe(ClO ₄ ) ₂ was added until the detection potential dropped to 0.29V.

4) the lead sulfate obtained after centrifuging the reaction liquid in the process of (3), and the mother liquor containing ferrous perchlorate, ferric perchlorate and perchloric acid. The mother liquor is regenerated after reacting with 1.9 kg of iron filings, and returns to (3) process for recycling after adding sulfuric acid.

Separate and wash the reacted lead plaster in a centrifuge, add 280L of 32% NaOH solution to the product obtained by press filtration, and desulfate the lead sulfate and sodium hydroxide at 110°C, and simultaneously combined leaching reaction. During this process, almost all PbSO ₄ and NaOH of the lead paste were converted into Na ₂ [Pb(OH) ₄ ].

5) The reaction solution obtained in (4) process is separated by pressure filtration to obtain an alkaline electrolytic mother liquor and 0.5 kg of residue with a lead content of 82 g/L. After analysis, the residue is basically an additive added to the battery production process such as barium sulfate. The lead-containing mother liquor enters the electrolytic cell for electrolysis after standing still and deep purification (that is, after conventional standing, using activated carbon to absorb impurities and microfiltration membrane filtration to remove impurities in the solution). Simultaneously in order to improve the morphology of the electrodeposited lead of negative electrode, add the gelatin of 0.15% and 0.2% DPE-III (electroplating additive, purchased from Wuhan Yuancheng Science and Technology Development Co., Ltd.) in electrolytic mother liquor to improve lead electrolysis process The smoothness of the surface.

6) The electrolytic mother liquor is introduced into the regenerative lead ion electrolyzer (1) for electrolysis. The size of the electrolytic cell is: the volume is 96 (length)*22 (width)*150 (height) cm ³ , and it is stirred by a 60W electric mixer. The pure lead plate with a thickness of 1mm and the nickel-plated 304 stainless steel plate are used as the cathode and the anode respectively, the Asahi Kasei F4602 ion membrane is used as the diaphragm, the structure of the electrolytic cell is 1 positive and 1 negative electrode structure, and the sealed electrolytic cell for placing the lead ion meter and the inlet and outlet . Firstly, constant current electrolysis was carried out in the electrolytic cell, the cathode and anode current densities were controlled to be 750A/m ² , the electrolysis temperature was 95°C, and the electrolysis voltage was 1.53V. After the electrolysis time reached 80min, when the lead concentration was 25g/L after detection, it was transferred to the electrolytic cell (two) to continue the pulse electrolysis. At this time, the pulse duration is 0.02s, the duty ratio is 1:1, the electrolysis temperature is 95°C, and the pulse peak voltage is 1.93V. Until the concentration of lead oxide in the electrolytic mother liquor is reduced to below 4g/L. The electrolytic mother liquor after electrolysis increases the actual concentration of NaOH to 32% again by supplementing crystallized NaOH, and then cools the electrolytic solution to 5° C., and at this time, sodium sulfate decahydrate crystals are precipitated in the solution. The mother liquor is subjected to solid-liquid separation to obtain 32% NaOH solution and sodium sulfate crystals, and the lead-containing NaOH mother liquor is returned to the extraction tank for recycling.

After testing and calculation, the cathode lead obtained 20.92 kg of lead with a purity of 99.991%, a current efficiency of 98.9%, and an energy consumption of 595kWh/t (Pb) for the direct electrolysis process of the lead paste, combined with the lead separated from the crushing process For grids and tabs, the comprehensive recovery rate of the battery is 97.2%, and the electrolysis energy consumption of all lead is 443KWh/t.

Example 2

Take a 12V, 54Ah waste automobile lead-acid battery with a total weight of 15.5 kg. The specific recycling process is as follows:

According to (1) and (2) process of embodiment 1, lead plaster, grid, dividing plate and plastics etc. are separated.

3) Take 12L of the waste sulfuric acid obtained in the above process and adjust its acidity to a mixed solution containing 4.0 mol/L sulfuric acid, 1 mol/L ferrous perchlorate and 1 mol/L perchloric acid. Get 6 kg of lead plaster powder and waste sulfuric acid solution obtained by screening in (2) process, mix the two, add 4.0mol/L sulfuric acid, 0.8mol/L ferrous perchlorate and 0.8mol/L perchloric acid at the same time The mixed solution was reacted at 85°C for 4 hours. The reaction was stopped when the detection potential decreased to 0.25V.

4) the lead sulfate obtained after centrifuging the reaction liquid in the process of (3), and the mother liquor containing ferrous perchlorate, ferric perchlorate and perchloric acid. The mother liquor is regenerated after reacting with 0.39 kg of iron filings, and the concentrated sulfuric acid is added to make the concentration rise to 4mol/L, and then return to (3) process for recycling.

After the reacted lead paste was separated and washed in a filter press, 65L of 35% NaOH solution was added to carry out desulfation and extraction reactions at 112°C. During this process, PbSO ₄ and NaOH in the lead paste undergo a complexation reaction, and almost all of them are converted into Na ₂ [Pb(OH) ₄ ].

5) The reaction solution obtained in (4) process is separated by pressure filtration to obtain an alkaline electrolytic mother liquor and 0.2 kg of residue with a lead content of 95 g/L. After analysis, the residues are basically non-lead additives added to the battery production process such as barium sulfate. The lead-containing mother liquor enters the electrolytic cell (1) and (2) in the embodiment 1 after standing and deep purification to carry out electrolysis successively. At the same time, in order to improve the morphology of electrodeposited lead at the cathode, 0.2% gelatin and 0.2% DPE-III by weight are still added in the electrolytic mother liquor as electrodeposition additives to improve the cathode process.

During the electrolysis process, the cathode and anode current densities were controlled to be 200A/m ² , the electrolysis temperature was 95°C, and the electrolysis voltage was 1.47V. After the electrolysis time reached 2 hours, when the lead concentration was 24g/L through detection, it was transferred to the electrolytic cell (two) to continue the pulse electrolysis. At this time, the pulse duration is 0.017s, the duty ratio is 1:1, the electrolysis temperature rises to 105°C, and the pulse peak voltage is 2.05V. Until the concentration of lead oxide in the electrolytic mother liquor is reduced to below 3.5g/L. The electrolytic mother liquor after electrolysis increases the actual concentration of NaOH to 35% again by supplementing crystallized NaOH, and then cools the electrolytic solution to 10° C., and at this time, sodium sulfate decahydrate crystals are precipitated in the solution. The mother liquor is subjected to solid-liquid separation to obtain 35% NaOH solution and sodium sulfate crystals, and the lead-containing NaOH mother liquor is returned to the extraction tank for recycling.

After testing and calculation, the cathode lead obtained 4.05 kg of lead with a purity of 99.992%, a current efficiency of 99.0%, energy consumption of the DC electrolysis process of 573kWh/t (Pb), and a comprehensive recovery rate of lead of 98.5%. Combined with the lead grids and tabs separated from the crushing process, the electrolysis energy consumption per ton of lead is 425KWh/t.

Example 3

Take 2 kg of lead-containing waste from the lead-acid battery production workshop of a certain company in Hebei, and pulverize it into powder through a ball mill. It is determined that it is mainly 95% lead oxide (PbO), 3% lead and a small amount of clay. The secondary lead process is as follows:

1) After ball milling the above lead-containing waste powder in an air atmosphere for 3 hours, sieve with a 60-mesh sieve to obtain a fine powder, then add 20L of 29% NaOH solution, and carry out leaching reaction at 100°C. During this process, the lead oxide in the waste and a small amount of lead oxidized newly generated lead oxide and NaOH undergo a complexation reaction to form Na ₂ [Pb(OH) ₄ ]. As determined by EDTA chemical titration, the Na ₂ [Pb(OH) ₄ ] part contained 99 g/L of lead, and about 0.05 kg of clay-like precipitate remained after filtration.

2) Purify the lead-containing mother liquor obtained in the process of (1) and enter the electrolytic cell for electrolysis. In order to improve the morphology of electrodeposited lead at the cathode, 0.2% by weight of DPE-III was added to the electrolytic mother liquor as an electrodeposition additive to improve the cathode process.

3) carry out electrolysis in electrolyzer, electrolysis temperature is adjusted to 110 ℃, other conditions carry out step by step electrolysis with embodiment 2, cathode lead has obtained the lead of 1.92 kilograms, and its purity is 99.992%, anode is separated out a large amount of oxygen and is evacuated deal with. The electrolyte solution after electrolysis was analyzed by titration. 2.5g/L of lead remained. This part is transferred back to the leach tank for recycling again. After calculation, the energy consumption of the electrolysis process is 560kWh/t (Pb), and the comprehensive recovery rate of lead is 97.6%.

The method of the invention can directly obtain high-purity lead with a purity of more than 99.99% from the cathode, and simultaneously produce industrially valuable oxygen from the anode. The lead recovery rate for automotive lead-acid batteries is generally 97.2-98.9%, and the lead recovery rate for electric vehicle fully-sealed batteries reaches 97.1-99.2%. According to the scrapping situation of lead-acid batteries, the use time, the formula of lead paste and the current density of the electrolysis process, the power consumption per ton of secondary lead production is 380-490KWh. Compared with the prior art, it can significantly reduce energy consumption, avoid the use of toxic and harmful substances in the recycling process and the secondary pollution caused by it, and is a clean method for regenerating lead.

The present invention has been described in detail above through preferred embodiments and specific examples. However, those skilled in the art should understand that the scope of the present invention is not limited thereto, and any modifications or changes that do not depart from the present invention are within the scope of the present invention.

Claims (8)

1. A method of reclaiming secondary lead from leaded waste, comprising: (1) Convert lead and/or its oxides in lead-containing waste into lead sulfate; (2) react the converted lead sulfate with excess NaOH solution to generate Na ₂ [Pb(OH) ₄ ], or react the converted lead sulfate with the lead sulfate present in the lead-containing waste together with excess NaOH solution The reaction generates Na ₂ [Pb(OH) ₄ ] to obtain a mixed solution containing Na ₂ [Pb(OH) ₄ ] and NaOH; and (3) selective ion electrolysis of the mixed solution to generate metallic lead and oxygen, Wherein, the excess NaOH solution concentration in step (2) is 3-10mol/L, and the reaction temperature is 40-116°C; Wherein, the selective ion electrolysis in step (3) is a staged electrolysis comprising constant current electrolysis and subsequent pulse electrolysis, wherein the conditions of the constant current electrolysis are: electrolyte temperature 60-120°C; cathode current The density is 150-3500A/m ² ; the anode current density is 400-5000A/m ² ; the apparent current density of the ionic membrane is 300-4500A/m ² ; and the pulse electrolysis conditions are: the temperature of the electrolyte is 40-115°C; The current density is 60-2000A/m ² ; the anode current density is 100-2900A/m ² ; the apparent current density of the ionic membrane is 30-2000A/m ² ; the pulse duration is 0.01-1s; the duty ratio is 1:1- 1:2; Wherein, the staged electrolysis is carried out sequentially in the constant-flow cationic membrane electrolyzer and the pulse cationic membrane electrolyzer, or sequentially in the same cationic membrane electrolyzer. 2. The method for reclaiming regenerated lead from lead-containing waste as claimed in claim 1, wherein the excessive NaOH solution concentration in step (2) is 5.5mol/L, and the temperature of the reaction is 105°C. 3. The method of reclaiming secondary lead from lead-containing waste as claimed in claim 1, wherein said lead-containing waste comprises lead paste, PbO waste, Pb waste, _PbO waste, Pb(SO ) ₄ waste and at least one of other lead-containing waste from the production of lead-containing batteries. 4. the method for reclaiming regenerated lead from lead-containing waste as claimed in claim 3, wherein in step (1), lead in the described lead plaster and oxide compound thereof are mixed with ferrous perchlorate, high chlorine The mixed liquid reaction of acid and sulfuric acid is converted into lead sulfate, wherein the concentration of ferrous perchlorate, perchloric acid and sulfuric acid is respectively 0.05～1.5mol/L, 0.1～3mol/L and 0.5～12mol/L, wherein The sulfuric acid is waste sulfuric acid obtained from the waste lead-acid battery, or a mixture of the waste sulfuric acid and added sulfuric acid. 5. The method for reclaiming regenerated lead from lead-containing waste as claimed in claim 1, further comprising adding NaOH 2H ₂ O to the mixed solution after electrolysis in step (3) to separate out Na ₂ SO ₄ 10H ₂ O , Na ₂ SO ₄ ·10H ₂ O is separated, and the remaining mixed solution mainly containing NaOH is recycled to step (2). 6. A method of reclaiming secondary lead from PbO waste, comprising: (1) react PbO waste material with excess NaOH solution to generate Na ₂ [Pb(OH) ₄ ], and obtain a mixed solution containing Na ₂ [Pb(OH) ₄ ] and NaOH; (2) selective ion electrolysis of the mixed solution to generate metallic lead; Wherein, the excess NaOH solution concentration in step (1) is 3-10mol/L, and the reaction temperature is 60-115°C; Wherein, the selective ion electrolysis in step (2) is a staged electrolysis comprising constant current electrolysis and subsequent pulse electrolysis, wherein the conditions of the constant current electrolysis are: electrolyte temperature 60-120°C; cathode current The density is 150-3500A/m ² ; the anode current density is 400-5000A/m ² ; the apparent current density of the ionic membrane is 300-4500A/m ² ; and the pulse electrolysis conditions are: the temperature of the electrolyte is 40-115°C; The current density is 60-2000A/m ² ; the anode current density is 100-2900A/m ² ; the apparent current density of the ionic membrane is 30-2000A/m ² ; the pulse duration is 0.01-1s; the duty ratio is 1:1- 1:2; Wherein, the staged electrolysis is carried out sequentially in the constant-flow cationic membrane electrolyzer and the pulse cationic membrane electrolyzer, or sequentially in the same cationic membrane electrolyzer. 7. The method for recovering metallic lead from PbO waste as claimed in claim 6, wherein the excess NaOH solution concentration in step (1) is 5.5mol/L, and the reaction temperature is 105°C. 8. The method for recovering metallic lead from PbO waste as claimed in claim 6, further comprising recycling the remaining mixed solution mainly comprising NaOH after electrolysis in step (2) to step (2).

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