A method and special equipment for desulfurization and dechlorination of secondary lead smelting ash

Abstract

The present invention relates to a desulfurization and dechlorination method and special equipment for regenerated lead smelting ash. The desulfurization and dechlorination method has the following steps: S1, passing the regenerated lead smelting ash into a dechlorination device containing acid liquid and strong oxidizing substances below the liquid level, and performing oxidation reaction to obtain chlorine and acidic materials; S2, filtering the acidic materials to obtain filter residue and filtrate I, conveying the filter residue to the desulfurization device, further filtering the filtrate to obtain filtrate II, and passing it into the desulfurization device for desulfurization reaction to obtain desulfurized materials; S3, filtering the desulfurized materials, and the obtained solid is qualified chlorine-free and desulfurized ash, and the obtained liquid is purified and crystallized to obtain ammonium sulfate byproduct. The entire dechlorination and desulfurization process of the present invention can greatly reduce the processing cost, the process is simple, the chloride ion content in the ash after dechlorination is reduced to less than 500ppm, the risk of equipment corrosion is greatly reduced, the slag-making auxiliary materials required for sulfur fixation in the smelting process are reduced, the smelting output flue gas SO2 content is low, and the pollution to the environment is reduced.

Description

Technical Field

[0001] The invention belongs to the technical field of regeneration of useful parts of waste batteries, and relates to a method for desulfurization and dechlorination of recycled lead smelting ash and special equipment. Background Art

[0002] With the development of society, the demand for lead-acid batteries in various industries continues to increase. The number of lead-acid batteries scrapped each year is huge. At the same time, natural lead resources are becoming increasingly depleted. Therefore, recycling waste lead-acid batteries to produce recycled lead is an important source of lead.

[0003] Waste lead-acid batteries are first crushed and sorted to obtain components such as plastic, waste acid electrolyte, lead filings, and lead paste. Waste lead-acid batteries contain about 20% electrolyte, and the main component of waste acid electrolyte is dilute sulfuric acid, and the concentration of dilute sulfuric acid can reach more than 15%. The lead paste crushed and sorted from waste lead-acid batteries is the main source of lead resource recovery. The main components of lead paste include: PbSO4 (50-60%), PbO2 (20-30%), PbO (10-15%) and other substances (0.2-0.7%).

[0004] At present, the waste lead-acid battery recycling industry mostly uses pyrometallurgical smelting of lead-containing waste to produce crude lead and refined lead. The soot produced in the smelting process has a high lead content and all of it needs to be returned to the furnace for repeated smelting. However, there are the following problems with cyclic smelting: First, the chloride ions in the soot are continuously enriched as the number of times the soot is circulated into the furnace increases, which can easily cause equipment corrosion; second, the soot has a high sulfur content, and the cost of slag-making auxiliary materials required for return to the furnace for smelting increases. In addition, the SO2 concentration in the flue gas produced by smelting is high, and there are risks in tail gas treatment, so it is necessary to remove chlorine and sulfur impurities in the soot.

[0005] The main current chlorine removal technologies include chemical methods, ion exchange technology, and electrochemical technology. However, all of the above methods have certain limitations, such as high cost, single requirements for treatment material composition, and poor removal capacity. Summary of the invention

[0006] The purpose of the present invention is to overcome the deficiencies of the above-mentioned prior art, thereby providing a method for desulfurization and dechlorination of fly ash from recycled lead smelting. The method has a simple process and is cost-effective. It can reduce the chloride ion content in the fly ash to below 500 ppm. The SO2 content of the flue gas after desulfurization is low, which reduces pollution to the environment. It can also reduce the slag-making auxiliary materials required for sulfur fixation in the smelting process, and the amount of smelting slag is small.

[0007] The present invention also aims to provide special equipment for the above-mentioned method of desulfurization and dechlorination of secondary lead smelting ash.

[0008] A method for desulfurization and dechlorination of secondary lead smelting ash, characterized by the following steps:

[0009] S1. The recycled lead smelting ash in the ash storage tank is passed into a dechlorination reactor containing acid solution and strong oxidizing substances through a conveying screw, and the reaction conditions are controlled to obtain acidic materials, chlorine gas and acid mist. The chlorine gas and acid mist generated after the reaction are passed into the acid solution absorption tank and the alkali solution absorption tank in sequence through a conveying pipeline, and the remaining gas is discharged into the atmosphere;

[0010] S2, after primary filtration of the acidic material obtained in step S1, filter residue and filtrate I are obtained, the filter residue is conveyed to the desulfurization reaction tank through a closed screw, the filtrate II obtained after secondary filtration of the filtrate is passed into the desulfurization reaction tank, then a desulfurizer is added to the desulfurization reaction tank, the reaction conditions are controlled, and desulfurized materials, ammonia and acid mist are obtained. After the reaction is completed, the ammonia and acid mist in the desulfurization reaction tank are sequentially passed into the acid absorption tank and the alkali absorption tank described in step S1 through a conveying pipeline, and the residual gas is discharged into the atmosphere;

[0011] S3. After the reaction in step S2 is completed, the desulfurized material obtained is separated into solid and liquid, and the obtained solid is qualified ash for dechlorination and desulfurization. The obtained liquid is purified and crystallized to obtain ammonium sulfate by-product.

[0012] The main components of the recycled lead smelting ash in step S1 are lead sulfate, lead monoxide, lead chloride and other impurities. The sulfur content in the recycled lead smelting ash is 6-10wt%, and the chlorine content is 1-5wt%.

[0013] The acid solution in the dechlorination reactor in step S1 is waste acid electrolyte recovered from waste lead-acid batteries or dilute sulfuric acid with a concentration of 15-30wt%; the strong oxidizing substance in step S1 is hydrogen peroxide solution or lead paste.

[0014] In step S1, the mass ratio of the regenerated lead smelting ash to the acid solution is 1:2-6;

[0015] Cl in the recycled lead smelting ash in step S1 - The molar ratio of the content to the strong oxidizing substance is 1:1~3.

[0016] The reaction conditions in step S1 are: continuous stirring reaction for 5 to 8 hours under a closed negative pressure state, the reaction temperature is room temperature (0 to 35°C), and the stirring frequency during the reaction is 50 Hz;

[0017] The reaction conditions in step S2 are: continuous stirring reaction for 2 hours under a closed negative pressure state, the reaction temperature is room temperature (0-35° C.), and the reaction stirring frequency is 40 Hz.

[0018] In step S1, the acid in the acid absorption tank is a 5-20wt% dilute sulfuric acid solution; the alkali in the alkali absorption tank is a 5-20wt% sodium hydroxide solution.

[0019] The device used for the primary filtration in step S2 is a plate and frame filter press; the device used for the secondary filtration is an activated carbon filtration device.

[0020] In step S2, the desulfurizing agent is ammonium carbonate, and the molar ratio of the sum of the molar amounts of sulfur in the filter residue and the filtrate II to the desulfurizing agent is 1:1-1.5.

[0021] A special device for the desulfurization and dechlorination method of recycled lead smelting ash described in the above technical solution, comprising an ash storage tank for storing recycled lead smelting ash, the ash storage tank is connected to the upper input port of a dechlorination reactor through a screw conveyor 1, the bottom outlet of the dechlorination reactor is connected to a primary filter through a conveying pipeline 1, the solid output port at the bottom of the primary filter is connected to the upper port of the desulfurization reactor through a screw conveyor 2, and is used to input the filtered filter residue into the desulfurization reactor, the liquid output port on one side of the primary filter is connected to a secondary filter and the desulfurization reactor through a conveying pipeline 2, and is used to input the filtered filtrate into the desulfurization reactor after secondary filtration, the bottom of the desulfurization reactor is connected to a filter press through a conveying pipeline 3, and the filter press is connected to a purification crystallization reactor through a conveying pipeline 6; the solid obtained by filtration by the filter press is qualified chlorine and desulfurization ash, and the liquid obtained by filtration is purified and crystallized to obtain ammonium sulfate by-product.

[0022] The external discharge port at the top of the dechlorination reactor is connected to the negative pressure fan and the acid absorption tank via a conveying pipeline four, the external discharge port at the top of the desulfurization reactor is also connected to the negative pressure fan and the acid absorption tank via a conveying pipeline five, and the exhaust port at the upper end of the acid absorption tank is connected to the alkali absorption tank via a gas conveying pipeline; it is used to pass the gases generated by the reactions in the dechlorination reactor and the desulfurization reactor into the acid absorption tank and the alkali absorption tank in turn through a conveying pipeline four and then discharge them into the atmosphere.

[0023] The desulfurization reaction tank is connected to the desulfurization agent adding device through a desulfurization agent screw conveyor 3, and the desulfurization agent adding device contains desulfurization agent;

[0024] The dechlorination reaction kettle and the desulfurization reaction tank are both provided with stirring devices; the middle and upper parts of the inner walls of the dechlorination reaction kettle and the desulfurization reaction tank are both provided with defoaming devices.

[0025] The invention introduces the method into which the fly ash from the regenerated lead smelting is passed into a dechlorination device containing acid liquid and strong oxidizing substances, the chloride (mainly lead chloride) contained in the fly ash from the regenerated lead smelting is reacted with the strong oxidizing substances in the dechlorination device to generate chlorine gas and acidic materials, the chlorine gas is introduced into an acid liquid absorption tank and an alkali liquid absorption tank for absorption, the acidic materials are filtered by a primary filtering device to obtain filter residue (mainly containing lead sulfate) and filtrate I (mainly containing dilute sulfuric acid and soluble sulfate), the filtrate I is adsorbed and removed with a small amount of unexhausted chlorine gas by a secondary filtering device to obtain filtrate II, the filter residue and filtrate II are mixed in a desulfurization device, reacted with a desulfurizing agent to generate more insoluble lead carbonate and ammonium sulfate, and ammonia gas is generated by a side reaction, the dilute sulfuric acid reacts with the ammonium carbonate to generate ammonium sulfate, so as to remove sulfur element in the fly ash and neutralize excessive sulfuric acid in the slurry. The desulfurized material is passed into the filter press for filtration. The solid dechlorinated and desulfurized qualified ash obtained after filtration is mainly composed of lead carbonate, which is transported back to the smelting system for smelting and lead extraction. The liquid component obtained by filtration is mainly ammonium sulfate solution containing a small amount of impurities. After purification and crystallization, ammonium sulfate by-product is obtained, which is a raw material for nitrogen-sulfur compound fertilizer.

[0026] The beneficial effects of the present invention are as follows: the acid solution used in the method for desulfurization and dechlorination of fly ash from recycled lead smelting of the present invention can be waste acid electrolyte obtained from the crushing and sorting of waste lead-acid batteries; the strong oxidizing substance used can be replaced by lead paste (containing lead dioxide) obtained from the crushing and sorting of waste lead-acid batteries; when hydrogen peroxide or lead paste is used for dechlorination, no other impurity elements are introduced; the entire dechlorination and desulfurization process can greatly reduce the processing cost; the process is simple; the chloride ion content in the fly ash after dechlorination is reduced to below 500ppm; the sulfur content in the fly ash after desulfurization can be stably controlled to be below 2wt%; when the equipment is returned to the furnace for smelting, the risk of equipment corrosion can be greatly reduced; the slag-making auxiliary materials required for sulfur fixation in the smelting process are reduced; the SO2 content of the smelting output flue gas is low, and the pollution to the environment is reduced. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a structural schematic diagram of the special equipment of the present invention;

[0028] In the figure: 1-ash storage tank; 2-screw conveyor 1; 3-dechlorination reactor; 3-1-stirring device; 3-2-defoaming device; 4-1-primary filter; 4-2-secondary filter; 5-transportation pipeline 1; 6-screw conveyor 2; 7-transportation pipeline 2; 8-desulfurization reactor; 8-1-stirring device; 8-2-defoaming device; 9-transportation pipeline 3; 10-filter press; 11-transportation pipeline 4; 12-transportation pipeline 5; 13-negative pressure fan; 14-acid absorption tank; 15-gas transmission pipeline; 16-alkali absorption tank; 17-desulfurization agent adding device; 18-screw conveyor 3; 19-purification crystallization reactor. DETAILED DESCRIPTION

[0029] In order to enable those skilled in the art to better understand the technical solution of the present invention, the present invention is further described in detail below in conjunction with embodiments.

[0030] Example 1

[0031] A method for desulfurization and dechlorination of secondary lead smelting ash, the specific steps are as follows:

[0032] S1. Pass 1 ton of recycled lead smelting ash (mainly composed of lead sulfate, lead monoxide, lead chloride and other impurities, with a sulfur content of 7wt% and a chlorine content of 3wt%) through a conveying pipeline into a dechlorination device containing 3 tons of 30wt% sulfuric acid solution and 0.2 tons of 30wt% hydrogen peroxide below the liquid level (Cl in recycled lead smelting ash - The molar ratio of the content to H2O2 in hydrogen peroxide is about 1:2). Under sealed negative pressure (negative pressure 200pa), chlorine gas and acidic materials after dechlorination are obtained by dechlorination reaction for 6 hours. After the reaction, the gas in the dechlorination device is passed through the transmission pipeline in turn into the acid absorption tank (the liquid filled in it is 10wt% dilute sulfuric acid solution) and the alkali absorption tank (the liquid filled in it is 10wt% sodium hydroxide solution) below the liquid level. The remaining gas after treatment is clean air and can be directly discharged into the atmosphere;

[0033] S2, the acidic material obtained in step S1 is filtered through a primary filtering device (plate and frame filter press) to obtain filter residue and filtrate I, the chloride ion content in the filter residue is 100ppm, the sulfur content is 8.3wt%, the chloride ion content in the filtrate I is 150ppm, and the acid concentration is 26.8wt%. The filter residue is conveyed to the desulfurization device through a closed spiral, and the filtrate I is conveyed to the secondary filtering device (activated carbon filtering equipment) through a pipeline to further filter and remove the residual chlorine in the liquid. The obtained filtrate II is passed into the desulfurization device and mixed with the filter residue to re-form lead mud. 1.1 tons of ammonium carbonate is added to the desulfurization device to carry out desulfurization reaction under closed negative pressure (negative pressure 200pa). The molar ratio of the sum of the molar amounts of sulfur in the filter residue and the filtrate II to the molar amount of ammonium carbonate is about 1:1. The desulfurization reaction lasts for 2h, and a desulfurized material is obtained through the desulfurization reaction. After the desulfurization reaction is completed, the gas in the desulfurization device is sequentially passed into the acid absorption tank and the alkali absorption tank described in step S1 through a conveying pipeline, and the tail gas can be directly discharged;

[0034] S3. The desulfurized material obtained in step S2 is filtered, and the solid phase obtained after the filtration is the ash after desulfurization and dechlorination (sulfur content 1.4wt%, chlorine content 100ppm), which is transported back to the smelting system to recover lead, which can reduce smelting energy consumption, auxiliary material consumption and tail gas treatment risks and costs. The filtrate obtained after the filtration is mainly composed of ammonium sulfate solution containing a small amount of impurities (ammonium sulfate concentration is 32wt%), which is transported to the purification and crystallization system through a conveying pipeline, and ammonium sulfate by-product is obtained after purification and crystallization.

[0035] Example 2

[0036] A method for desulfurization and dechlorination of secondary lead smelting ash, the specific steps are as follows:

[0037] S1. One ton of recycled lead smelting ash (mainly composed of lead sulfate, lead monoxide, lead chloride and other impurities, with a sulfur content of 7wt% and a chlorine content of 3wt%) is introduced into a container containing 6 tons of spent acid electrolyte (containing 15wt% sulfuric acid) and 0.29 tons of 30wt% hydrogen peroxide (containing Cl in recycled lead smelting ash) through a conveying pipeline. - The chlorine gas and the acidic soot slurry material after dechlorination are obtained by dechlorination reaction for 8 hours under sealed negative pressure conditions. After the reaction, the gas in the dechlorination device is sequentially introduced into the acid absorption tank (the liquid filled therein is 10wt% dilute sulfuric acid solution) and the alkali absorption tank (the liquid filled therein is 10wt% sodium hydroxide solution) below the liquid level through a conveying pipeline. The remaining gas after treatment is clean air and can be directly discharged into the atmosphere.

[0038] S2, the acidic material obtained in step S1 is filtered through a primary filtering device to obtain a filter residue and a filtrate I, the chloride ion content in the filter residue is 70ppm, the sulfur content is 8.33wt%, the chloride ion content in the filtrate I is 100ppm, and the acid concentration is 13.63wt%, the filter residue is conveyed to the desulfurization device through a closed spiral, the filtrate I is conveyed to the secondary filtering device through a pipeline to further filter and remove the residual chlorine in the liquid, the obtained filtrate II is passed into the desulfurization device and mixed with the filter residue to re-form the lead mud, 1.09 tons of ammonium carbonate is added to the desulfurization device to carry out a desulfurization reaction under closed negative pressure conditions, the molar ratio of the sum of the molar amounts of sulfur in the filter residue and the filtrate II to the molar amount of ammonium carbonate is 1:1, the desulfurization reaction is continued for 2h, and a desulfurized material is obtained through the desulfurization reaction. After the desulfurization reaction is completed, the gas in the desulfurization device is sequentially passed into the acid absorption tank and the alkali absorption tank described in step S1 through a conveying pipeline, and the tail gas can be directly discharged;

[0039] S3. The desulfurized material obtained in step S2 is filtered, and the solid phase obtained after the filtration is the ash after desulfurization and dechlorination (sulfur content 1.2wt%, chlorine content 70ppm), which is transported back to the smelting system to recover lead, which can reduce smelting energy consumption, auxiliary material consumption and tail gas treatment risks and costs. The filtrate obtained after the filtration is mainly composed of ammonium sulfate solution containing a small amount of impurities (ammonium sulfate concentration is 19.4wt%), which is transported to the purification and crystallization system through a conveying pipeline, and ammonium sulfate by-product is obtained after purification and crystallization.

[0040] Example 3

[0041] A method for desulfurization and dechlorination of secondary lead smelting ash, the specific steps are as follows:

[0042] S1. One ton of recycled lead smelting ash (mainly composed of lead sulfate, lead monoxide, lead chloride and other impurities, with a sulfur content of 7wt% and a chlorine content of 3wt%) is passed through a conveying pipeline into a dechlorination device containing 6 tons of spent acid electrolyte (containing 15wt% sulfuric acid) and 1.52 tons of sorted lead paste (containing 20wt% PbO2, 60wt% PbSO4). - The molar ratio of the content to PbO2 in the lead paste is 1:1.5), and the chlorine gas and the acidic soot slurry material after dechlorination are obtained by 8 hours of dechlorination reaction under sealed negative pressure conditions. After the reaction, the gas in the dechlorination device is sequentially passed through the conveying pipeline into the acid absorption tank (the liquid filled therein is a 10wt% dilute sulfuric acid solution) and the alkali absorption tank (the liquid filled therein is a 10wt% sodium hydroxide solution) below the liquid level. The remaining gas after treatment is clean air and can be directly discharged into the atmosphere;

[0043] S2. The acidic material obtained in step S1 is filtered through a primary filtering device (plate and frame filter press) to obtain filter residue and filtrate I. The chloride ion content in the filter residue is 200ppm and the sulfur content is 7.14wt%. The chloride ion content in the filtrate I is 200ppm and the acid concentration is 14.4wt%. The filter residue is conveyed to the desulfurization device through a closed spiral. The filtrate I is conveyed to the secondary filtering device (activated carbon filtering equipment) through a pipeline to further filter and remove the residual chlorine in the liquid. The obtained filtrate II is passed into the desulfurization device and mixed with the filter residue to re-form lead mud. 1.39 tons of ammonium carbonate is added to the desulfurization device to carry out desulfurization reaction under closed negative pressure conditions. The molar ratio of the sum of the molar amounts of sulfur in the filter residue and the filtrate II to the molar amount of ammonium carbonate is 1:1. The desulfurization reaction is continued for 2h. A desulfurized material is obtained through the desulfurization reaction. After the desulfurization reaction is completed, the gas in the desulfurization device is sequentially passed into the acid absorption tank and the alkali absorption tank described in step S1 through a conveying pipeline, and the tail gas can be directly discharged;

[0044] S3. The desulfurized material obtained in step S2 is filtered, and the solid phase obtained after the filtration is the ash after desulfurization and dechlorination (sulfur content 0.8wt%, chlorine content 189ppm), which is transported back to the smelting system to recover lead, which can reduce smelting energy consumption, auxiliary material consumption and tail gas treatment risks and costs. The filtrate obtained after the filtration is mainly composed of ammonium sulfate solution containing a small amount of impurities (ammonium sulfate concentration is 24.7wt%), which is transported to the purification and crystallization system through a conveying pipeline, and ammonium sulfate by-product is obtained after purification and crystallization.

[0045] The method for desulfurization and dechlorination of secondary lead smelting ash provided by the present invention utilizes a strong oxidizing substance to oxidize chloride ions in a solution under certain conditions and discharge them from the solution in the form of chlorine gas. The dechlorination technology can reduce the chloride ion content in the ash to less than 500ppm, so that it meets the chlorine corrosion resistance requirements of existing equipment, and solves the difficulty of chlorine corrosion in the recovery process of waste lead-acid batteries. After the chlorine-free ash is subjected to a desulfurization reaction, the sulfur content can be reduced to less than 2wt%, which can reduce the input of slag auxiliary materials in the secondary lead smelting process. At the same time, after smelting the desulfurized materials, the SO2 content in the flue gas is greatly reduced, which can reduce pollution to the environment.

[0046] Figure 1 This is a special equipment structure diagram for the above-mentioned method for desulfurization and dechlorination of recycled lead smelting fly ash. The fly ash storage tank 1 is connected to the dechlorination reactor 3 through a screw conveyor 2. The dechlorination reactor 3 is a tank body used for dechlorination reaction, and the common acid corrosion-resistant 316L material tank body is adopted. The dechlorination reactor 3 contains acid solution (30wt% dilute sulfuric acid) and strong oxidizing substance (30wt% hydrogen peroxide solution) for dechlorination. During the treatment, the chloride ions in the soot react with the strong oxidizing substance under acidic conditions to generate chlorine gas for discharge. The dechlorination reactor 3 is equipped with a stirring device 3-1 and a defoaming device 3-2. The stirring device 3-1 includes a stirring blade. The upper end of the stirring shaft of the stirring blade extends out of the tank body and is connected to the stirring motor. The defoaming device 3-2 is arranged in the upper middle part of the dechlorination reactor 3. The defoaming device 3-2 contains a defoaming agent. The top of the dechlorination reactor 3 is provided with an external discharge port for discharging the gas in the dechlorination reactor 3 for post-treatment. The gas discharged from the dechlorination reactor 3 is passed into the acid absorption tank 14 through the conveying pipe 11, and then passed into the alkali absorption tank 16 through the gas conveying pipe 15 after the reaction, and finally discharged into the atmosphere.

[0047] The bottom of the dechlorination reactor 3 is connected to the primary filter 4-1 (plate and frame filter press) through a conveying pipeline 5 to separate a small amount of unexhausted chlorine from the solid phase material. The bottom of the primary filter 4-1 is connected to the desulfurization reaction tank 8 through a screw conveyor 6 to input the filtered residue into the desulfurization reaction tank 8. The primary filter 4-1 is connected to the secondary filter 4-2 (activated carbon filter equipment, used to absorb the residual chlorine in the filtered liquid) and then connected to the desulfurization reaction tank 8 through a conveying pipeline 7. The filtrate after the primary filter 4-1 is filtered through the secondary filter 4-2. The secondary filter 4-2 is filtered twice and then input into the desulfurization reaction tank 8. The desulfurization reaction tank 8 is provided with a stirring device 8-1 and a defoaming device 8-2. The stirring device 8-1 and the defoaming device 8-2 in the desulfurization reaction tank 8 are consistent in structure with the stirring device 3-1 and the defoaming device 3-2 configured in the dechlorination reactor 3. The desulfurizer adding device 17 is a tank body storing the desulfurizer. The bottom outlet of the desulfurizer adding device 17 is connected to the desulfurization reaction tank 8 through a screw conveyor 18, which is used to add the desulfurizer (such as ammonium carbonate) into the desulfurization reaction tank 8.

[0048] The top of the desulfurization reaction tank 8 is provided with an external discharge port for discharging the gas in the desulfurization reaction tank 8 for post-processing. The gas in the desulfurization reaction tank 8 is sequentially passed into the acid absorption tank 14 and the alkali absorption tank 16 through the delivery pipeline 5 12. The bottom of the desulfurization reaction tank 8 is connected to the filter press 10 through the delivery pipeline 9, and the filter press 10 is connected to the purification crystallization kettle 19 through the delivery pipeline. The solid obtained by the filter press 10 is the qualified ash for dechlorination and desulfurization, and the liquid obtained by the filter press is purified and crystallized in the purification crystallization kettle 19 to obtain the by-product of ammonium sulfate.

[0049] The delivery pipeline 4 11 and the delivery pipeline 5 12 are connected to the negative pressure fan 13 and are used to pass the gas in the dechlorination reactor 3 and the desulfurization reaction tank 8 into the acid absorption tank 14 and the alkali absorption tank 16.

[0050] When in use, 1 ton of recycled lead smelting fly ash (mainly lead sulfate, lead monoxide, lead chloride and other sundries, with a sulfur content of 10wt% and a chlorine content of 10wt% in the smelting fly ash) stored in the fly ash storage tank 1 is passed through a screw conveyor 2 into a dechlorination reactor 3 containing 3 tons of 30wt% sulfuric acid solution and 0.65 tons of 30wt% hydrogen peroxide, and the materials are stirred by a stirring device 3-1. After 6 hours of dechlorination reaction, chlorine gas and acidic materials are obtained. The external discharge port provided on the top of the dechlorination reactor 3 passes the gas in the dechlorination reactor 3 through a conveying pipe 4 11 in sequence into an acid absorption tank 14 (the liquid filled therein is a 10wt% dilute sulfuric acid solution) and an alkali absorption tank 16 (the liquid filled therein is a 10wt% sodium hydroxide solution) below the liquid level. The residual gas after treatment is clean air and can be directly discharged into the atmosphere.

[0051] The acidic material obtained by the reaction in the dechlorination reactor 3 is filtered through the primary filter 4-1 to obtain a filter residue (after dechlorination, the chloride ion content in the filter residue is 100ppm) and a filtrate (the chloride ion content in the acid solution after dechlorination is 150ppm), and the sulfur content of the filter residue and the acid concentration of the filtrate are detected (the sulfur content in the filter residue is 8.86wt%, and the acid concentration of the filtrate is 25wt%). The filter residue is transported to the desulfurization reaction tank 8 through a screw conveyor 26, and the filtrate is transported to the secondary filter 4-2 through a pipeline for further filtration to remove residual chlorine. The filtrate filtered by the secondary filter 4-2 is passed into the desulfurization reaction tank 8 and mixed with the filter residue obtained by the filter pressing of the primary filter 4-1 to re-form a lead slurry, and 1.19 tons of lead slurry are added to the desulfurization reaction tank 8 through the desulfurizer adding device 17. The ammonium carbonate is subjected to a desulfurization reaction, and the desulfurization reaction lasts for 2 hours. A desulfurized material is obtained through the desulfurization reaction. The top of the desulfurization reaction tank 8 is provided with an external discharge port. The gas in the desulfurization reaction tank 8 (desulfurized ash, the sulfur content detection result is 1.46wt%) is sequentially introduced into the alkali solution absorption tank 14 and the acid solution absorption tank 16 described in step S1 through the conveying pipeline five 12. The tail gas is clean air and carbon dioxide gas after the ammonia and acid mist are removed, and can be directly discharged; the desulfurized material is filtered by a filter press 10, and the solid obtained after the filtration is the treated ash and lead paste, the main component of which is lead carbonate, which is transported back to the smelting system. The filtrate obtained after the filtration is an ammonium sulfate solution containing a small amount of impurities, which is transported to the purification crystallization kettle 19 through the conveying pipeline six for purification and crystallization to obtain ammonium sulfate by-product.

Claims

1. A method for desulfurization and dechlorination of secondary lead smelting ash, characterized in that: Here are the steps: S1, passing the recycled lead smelting ash in the ash storage tank (1) into a dechlorination reactor (3) containing acid liquid and strong oxidizing substances through a conveying screw, controlling the reaction conditions to obtain acidic materials, chlorine gas and acid mist, and passing the chlorine gas and acid mist generated after the reaction into an acid liquid absorption tank (14) and an alkali liquid absorption tank (16) in sequence through a conveying pipeline, and then the residual gas is discharged into the atmosphere; S2, after primary filtration of the acidic material obtained in step S1, filter residue and filtrate I are obtained, the filter residue is conveyed to the desulfurization reaction tank (8) through a closed screw, the filtrate II obtained after secondary filtration of the filtrate I is passed into the desulfurization reaction tank (8), then a desulfurizer is added to the desulfurization reaction tank (8), the reaction conditions are controlled, and desulfurized material, ammonia and acid mist are obtained. After the reaction is completed, the ammonia and acid mist in the desulfurization reaction tank (8) are successively passed into the acid absorption tank (14) and the alkali absorption tank (16) described in step S1 through a conveying pipeline, and the residual gas is discharged into the atmosphere; S3. After the reaction in step S2 is completed, the desulfurized material obtained is separated into solid and liquid, and the obtained solid is qualified ash for dechlorination and desulfurization. The obtained liquid is purified and crystallized to obtain ammonium sulfate by-product.

2. The method for desulfurization and dechlorination of secondary lead smelting ash according to claim 1, characterized in that: The main components of the recycled lead smelting ash in step S1 are lead sulfate, lead monoxide, lead chloride and other impurities. The sulfur content in the recycled lead smelting ash is 6-10wt%, and the chlorine content is 1-5wt%.

3. The method for desulfurization and dechlorination of secondary lead smelting ash according to claim 1, characterized in that: The acid solution in the dechlorination reactor (3) in step S1 is waste acid electrolyte recovered from waste lead-acid batteries or dilute sulfuric acid with a concentration of 15-30 wt %; the strong oxidizing substance in step S1 is hydrogen peroxide solution or lead paste.

4. The method for desulfurization and dechlorination of secondary lead smelting ash according to claim 1, 2 or 3, characterized in that: In step S1, the mass ratio of the regenerated lead smelting ash to the acid solution is 1:2-6; Cl in the recycled lead smelting ash in step S1 - The molar ratio of the content to the strong oxidizing substance is 1:1~3.

5. The method for desulfurization and dechlorination of secondary lead smelting ash according to claim 1, characterized in that: The reaction conditions in step S1 are: continuous stirring reaction for 5 to 8 hours under a closed negative pressure state, the reaction temperature is room temperature (0 to 35°C), and the stirring frequency during the reaction is 50 Hz; The reaction conditions in step S2 are: continuous stirring reaction for 2 hours under a closed negative pressure state, the reaction temperature is room temperature (0-35° C.), and the reaction stirring frequency is 40 Hz.

6. The method for desulfurization and dechlorination of secondary lead smelting ash according to claim 1, characterized in that: In step S1, the acid solution in the acid solution absorption tank (14) is a 5-20wt% dilute sulfuric acid solution; and the alkali solution in the alkali solution absorption tank (16) is a 5-20wt% sodium hydroxide solution.

7. The method for desulfurization and dechlorination of secondary lead smelting ash according to claim 1, characterized in that: The device used for the primary filtration in step S2 is a plate and frame filter press; the device used for the secondary filtration is an activated carbon filtration device.

8. The method for desulfurization and dechlorination of secondary lead smelting ash according to claim 1, characterized in that: In step S2, the desulfurizing agent is ammonium carbonate, and the molar ratio of the sum of the molar amounts of sulfur in the filter residue and the filtrate II to the desulfurizing agent is 1:1-1.

5.

9. A special equipment for the method for desulfurization and dechlorination of secondary lead smelting ash according to claim 1, characterized in that: The invention comprises an ash storage tank (1) for storing recycled lead smelting ash, wherein the ash storage tank (1) is connected to an upper input port of a dechlorination reactor (3) via a screw conveyor (2), and a bottom outlet of the dechlorination reactor (3) is connected to a primary filter (4-1) via a conveying pipe (5), and a solid output port at the bottom of the primary filter (4-1) is connected to an upper port of a desulfurization reactor (8) via a screw conveyor (6) for inputting filtered residue into the desulfurization reactor (8), and a liquid output port on one side of the primary filter (4-1) is connected to a secondary filter (4-2) and the desulfurization reactor (8) via a conveying pipe (7 ... The filtrate is filtered twice and then fed into the desulfurization reaction tank (8). The bottom of the desulfurization reaction tank (8) is connected to the filter press (10) via a delivery pipe (9), and the filter press (10) is connected to the purification crystallization kettle (19) via a delivery pipe (6). The external discharge port at the top of the dechlorination reaction kettle (3) is connected to the negative pressure fan (13) and the acid absorption tank (14) via a delivery pipe (4) (11). The external discharge port at the top of the desulfurization reaction tank (8) is also connected to the negative pressure fan (13) and the acid absorption tank (14) via a delivery pipe (5) (12). The exhaust port at the upper end of the acid absorption tank (14) is connected to the alkali absorption tank (16) via a gas delivery pipe (15).

10. The special equipment for desulfurization and dechlorination of secondary lead smelting fly ash according to claim 9, characterized in that: The desulfurization reaction tank (8) is connected to the desulfurization agent adding device (17) via a desulfurization agent screw conveyor 3 (18), and the desulfurization agent adding device (17) contains a desulfurization agent; The dechlorination reaction kettle (3) and the desulfurization reaction tank (8) are both provided with a stirring device; and the middle and upper parts of the inner walls of the dechlorination reaction kettle (3) and the desulfurization reaction tank (8) are both provided with a defoaming device.

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