Process for treating and comprehensively utilizing arsenic-containing acid wastewater in gold smelting and its matching equipment

Abstract

The present application relates to a kind of gold smelting arsenic-containing acid wastewater treatment and comprehensive utilization process method and its matching equipment, process method steps are as follows: the arsenic-containing acid wastewater from purification process is treated by degassing through desorption tower;Again detect the arsenic content of wastewater, according to the arsenic content high-low regulation PID control system;When arsenic content is high, using "hydrogen sulfide fully closed arsenic removal method+lime-iron salt three-stage neutralization method" fully closed gas circulation process method, when arsenic content is low, using "lime-iron salt three-stage neutralization method" circulation process method;Matching equipment includes desorption tower, sulfurization reaction tank import and hydrogen sulfide preparation and dosing system connection, export is connected with sulfurization thickener, filter press I, sulfurization filtrate tank in proper order.The present application proposes different process methods according to the arsenic content in wastewater, so that wastewater treatment is more targeted, and the arsenic content in wastewater is reduced by 99.99%, and arsenic content is reduced to below 0.1mg / L.

Description

Technical Field

[0001] This invention belongs to the field of heavy metal industrial wastewater treatment technology, specifically relating to a process and supporting equipment for the treatment and comprehensive utilization of arsenic-containing acidic wastewater from gold smelting. Background Technology

[0002] Roasting oxidation is a traditional, mature, and widely used method for oxidizing refractory gold ores. It involves boiling roasting to decompose the gold-encapsulated sulfide minerals into porous oxides, producing loose, porous roasted sand that facilitates gold leaching. Copper is then leached with dilute sulfuric acid, followed by filtration and washing to extract gold using cyanide leaching. With the increasing depletion of easily beneficiated ores, arsenic, copper, and carbon content in ores is becoming increasingly common. Arsenic-containing minerals mainly include… During the roasting process of ore, the vast majority of the arsenic is converted into sulfuric acid. The form enters the flue gas and is processed into sulfuric acid through processes such as dust removal, purification, drying, conversion, and absorption; however, the flue gas contains... Some of the arsenic-containing wastewater enters the wastewater during the purification and washing process, forming highly acidic wastewater. This arsenic-containing wastewater has a high acid concentration (150–175 g / L) and is typically used to leach roasting residue. The leachate is then purified, extracted, and electrowinning is used to extract copper, but the arsenic concentration in the raffinate is too high to be directly discharged and must be treated. The National Integrated Wastewater Discharge Standard classifies arsenic as a Class I pollutant, with a maximum permissible discharge concentration of 0.5 mg / L.

[0003] Currently, the main methods for treating arsenic-containing wastewater include the lime-ferroalloy method, sulfidation method, ion exchange method, electrodialysis method, microbial method, and membrane separation method. The lime-ferroalloy method is one of the commonly used methods for treating high-arsenic wastewater from non-ferrous metal smelting. This method has relatively low equipment requirements, low initial investment, and low treatment cost. However, its drawbacks include unstable wastewater treatment compliance, large slag volume, difficulty in resource utilization, and the generally stockpiling method for treating arsenic-containing wastewater, which carries a high risk of secondary pollution. The sulfidation method is commonly used to remove arsenic and polymetallic ions from wastewater, and the generated sulfides have a very low solubility product. However, sulfidation precipitation requires acidic conditions, resulting in high reagent costs. Excess sulfide ions in the supernatant need to be treated before discharge, and the resulting precipitate has fine particles, high water content, and is difficult to dehydrate. Furthermore, the treated wastewater has excessively high sodium salt content, is difficult to remove chlorides, and cannot be recycled. Furthermore, in recent years, the gold smelting industry has seen breakthroughs in gold, silver, and copper recovery technologies from arsenic-containing gold concentrates, leading to improved gold and silver leaching efficiency. However, the input of arsenic-containing ores results in high arsenic concentrations in acidic wastewater. The simple lime-iron salt method has revealed significant shortcomings, as the treated liquid often fails to meet national discharge standards. Therefore, a new process for treating arsenic-containing acidic wastewater is urgently needed. Summary of the Invention

[0004] To address the above problems, this invention provides a process and supporting equipment for the treatment and comprehensive utilization of arsenic-containing acidic wastewater from gold smelting.

[0005] The specific technical solution is as follows:

[0006] A process for treating and comprehensively utilizing arsenic-containing acidic wastewater from gold smelting, characterized by comprising the following steps:

[0007] Step 1: The arsenic-containing acidic wastewater from the purification process is degassed using a degassing tower;

[0008] Step 2: Detect the arsenic content in the degassed wastewater and adjust the PID control system according to the arsenic content.

[0009] Step 3: When the arsenic (As) content is high, a fully closed gas circulation process of "hydrogen sulfide fully enclosed arsenic removal method + lime-ferrous salt three-stage neutralization method" is used for treatment. The hydrogen sulfide preparation and addition system, lime slurry preparation and addition system, and ferrous salt preparation and addition system are operated by regulating the PID control system. The specific method is as follows:

[0010] Step 3.1: Pump the degassed arsenic-containing acidic wastewater into a fully enclosed sulfidation reaction tank, allowing it to react with hydrogen sulfide gas from the hydrogen sulfide preparation and dosing system, as follows:

[0011]

[0012] In the reaction tank, arsenic (As) and other heavy metals react with hydrogen sulfide to form sulfide precipitates. Specifically, arsenic (As) reacts with hydrogen sulfide to form... Sedimentation occurs, at which point the arsenic content in the wastewater drops to below 0.05 mg / L;

[0013] Step 3.2: After the reaction in Step 3.1 is completed, the wastewater is dewatered by a sulfidation thickener, then filtered out by a plate and frame filter press to remove sulfidation slag. The sulfidation filtrate is pumped into a sulfidation filtrate tank, pressurized by a pump, and then sequentially fed into a first-stage neutralization tank, a second-stage neutralization tank, and a third-stage neutralization tank along with other wastewater in the buffer tank. The filtrate reacts with lime from the lime slurry preparation and addition system and ferrous salt from the ferrous salt preparation and addition system, as detailed below:

[0014] When iron salts are added to an aqueous solution, they produce Complexes, such as these substances, strongly adsorb colloidal particles in water to form flocs. These flocs collide with each other through adsorption, bridging, and cross-linking to form flocculated sediments. On the other hand, in water bodies... HE It will react with iron salts to produce The reaction produces and Sedimentation; on the other hand, in the water body and After being captured and rolled up by the flocculents, the arsenic will be deposited on the flocculents, thereby further removing arsenic from the wastewater.

[0015] Step 3.3: After the reaction in step 3.2 is completed, the wastewater is dewatered by a neutralization thickener, then filtered out by a plate and frame filter press to remove the neutralization residue. The neutralization filtrate is then filtered by a valveless filter and recycled into the return water tank.

[0016] Step 4: When the arsenic (As) content is low, a three-stage neutralization process using lime-ferrous salt is employed. The lime slurry preparation and dosing system, as well as the ferrous salt preparation and dosing system, are controlled by a PID control system. The specific method is as follows:

[0017] Step 4.1: After degassing, the arsenic-containing acidic wastewater is pressurized by a pump and then sequentially enters the first-stage neutralization tank, the second-stage neutralization tank, and the third-stage neutralization tank along with other wastewater in the buffer tank. The wastewater reacts with lime from the lime slurry preparation and dosing system and ferrous salt from the ferrous salt preparation and dosing system, as follows:

[0018]

[0019] Step 4.2: After the reaction in Step 4.1 is completed, the wastewater is dewatered by a neutralization thickener, then filtered by a plate and frame filter press to remove the neutralization residue. The neutralization filtrate is then filtered by a valveless filter and recycled into the return water tank.

[0020] Furthermore, in step 3.1, in order to increase the reaction intensity, a pressure pump is used to pressurize the mixture in the vulcanization reaction tank, and then the mixture is fully mixed and reacted by an injector before returning to the vulcanization reaction tank for circulation.

[0021] Furthermore, in step 3.1, the hydrogen sulfide gas generation process of the hydrogen sulfide preparation and addition system is "sulfur + methanol + waste heat boiler steam".

[0022] Furthermore, in steps 3.1 and 3.2, the residual hydrogen sulfide liquid is returned to the sulfidation reaction tank for recycling through the injector, and the residual hydrogen sulfide gas enters the alkali absorption tower, where it is absorbed by lime slurry spray. The absorbed residual gas is then returned to the purification process, and the remaining sulfidation slurry is pumped into the sulfidation filtrate tank for reaction.

[0023] Furthermore, in step 4 as described When the reaction occurs at pH 8, the arsenic (As) content can be reduced to below 0.1 mg / L, and The consumption is 0.6 kg / m³.

[0024] This invention also provides supporting equipment for a process for treating and comprehensively utilizing arsenic-containing acidic wastewater from gold smelting, including a desorption tower connected to a sulfidation reaction tank. The inlet of the sulfidation reaction tank is connected to a hydrogen sulfide preparation and dosing system, and the outlet is sequentially connected to a sulfidation thickener, a filter press I, and a sulfidation filtrate tank. The sulfidation filtrate tank is sequentially connected to a first-stage neutralization tank, a second-stage neutralization tank, a third-stage neutralization tank, a neutralization thickener, a filter press II, a valveless filter, and a return water tank. A lime slurry preparation and dosing system is connected between the sulfidation filtrate tank and the first-stage neutralization tank, and between the second-stage and third-stage neutralization tanks. The inlets of the first-stage and third-stage neutralization tanks are connected to a ferrous salt preparation and dosing system. The first-stage neutralization tank is also connected to a buffer tank, and the desorption tower is also connected to the first-stage neutralization tank.

[0025] Furthermore, the desorption tower is connected to the recovery tank in the purification process to realize the generation of... Gases are recycled and reused.

[0026] Furthermore, the sulfidation thickener and filter press I are connected to the sulfidation reaction tank via ejectors to achieve the recovery and recycling of residual hydrogen sulfide liquid; the sulfidation thickener and filter press I are sequentially connected to the alkali adsorption tower and the purification process recovery tank via ejectors; the alkali adsorption tower is connected to the lime slurry preparation and dosing system to achieve the recovery and recycling of residual hydrogen sulfide gas; the alkali adsorption tower is also connected to the sulfidation filtrate tank to achieve the recovery and recycling of sulfidation slurry.

[0027] Furthermore, a booster pump is connected between the desorption tower and the sulfidation reaction tank, and between the sulfidation filtrate tank and the first neutralization tank.

[0028] The beneficial effects of this invention are:

[0029] This invention proposes different process methods based on the arsenic content in wastewater, making wastewater treatment more targeted, and achieving a 99.99% reduction rate in arsenic content in the wastewater, with the arsenic content reduced to below 0.1 mg / L.

[0030] For wastewater with high arsenic content, a novel fully enclosed gas circulation process is adopted, which combines "hydrogen sulfide fully enclosed arsenic removal method + lime-iron salt three-stage neutralization method". The main equipment used in this process is inexpensive, easy to operate and maintain, stable in operation, and has a low accident rate. Moreover, the generated sulfide solubility product is small. Based on the different sulfide solubility products, the pH value and redox electrode potential depth during the sulfidation reaction stage can be controlled to comprehensively utilize elements such as arsenic, thereby rendering the arsenic-containing wastewater harmless and resource-efficient.

[0031] The hydrogen sulfide gas used in the "hydrogen sulfide fully enclosed arsenic removal method" is produced using "sulfur + methanol + waste heat boiler steam". These raw materials are readily available, have low production costs, and can produce hydrogen sulfide of different purities according to production needs. This solves the problems of high cost of arsenic removal agents such as sodium sulfide and phosphorus pentasulfide, sodium ions in the arsenic removal agents causing equipment crystallization and blockage, difficulty in removing chlorides, and inability to recycle wastewater.

[0032] The novel fully enclosed gas circulation process of "hydrogen sulfide fully enclosed arsenic removal method + lime-iron salt three-stage neutralization method" can realize "arsenic-containing wastewater desorption-purification and recovery and residual gases such as hydrogen sulfide alkaline adsorption-purification and recovery", which solves the problems of excessive sulfur ion treatment of arsenic-containing wastewater and recovery and recycling of toxic gases such as hydrogen sulfide.

[0033] For wastewater with low arsenic content, a recycling process using the "lime-iron salt three-stage neutralization method" is adopted. The amount of arsenic-containing waste residue after treatment is much smaller than that of the neutralization precipitation method, making the resource recovery of arsenic-containing waste residue possible.

[0034] (6) The wastewater treatment process is controlled by a PID control system, which greatly improves the automation level of the system, enables better monitoring of process indicators, and ensures the stability and safety of operation. Attached Figure Description

[0035] Figure 1 This is a schematic diagram of the process flow of the present invention;

[0036] In the diagram: 1-Desorption tower, 2-Sulfurization reaction tank, 4-Sulfurization thickener, 5-Filter press I, 6-Sulfurization filtrate tank, 7-First-stage neutralization tank, 8-Second-stage neutralization tank, 9-Third-stage neutralization tank, 10-Neutralization thickener, 11-Filter press II, 12-Valveless filter, 13-Return water tank, 14-Ejector, 15-Alkali adsorption tower, 16-Recovery tank for purification process, 17-Hydrogen sulfide preparation and addition system, 18-Lime slurry preparation and addition system, 19-Ferrous salt preparation and addition system, 20-Buffer tank. Implementation

[0037] To make the technical problems and solutions solved by the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for explaining the present invention and are not intended to limit the present invention. Example 1

[0038] like Figure 1 As shown, this embodiment provides a process for the treatment and comprehensive utilization of arsenic-containing acidic wastewater from gold smelting, including the following steps:

[0039] Step 1: The arsenic-containing acidic wastewater from the purification process is degassed in the degassing tower 1, and the SO2 and other gases generated are returned to the purification process for recycling.

[0040] Step 2: Detect the arsenic content in the degassed wastewater and adjust the PID control system according to the arsenic content.

[0041] Step 3: When the arsenic (As) content is high, a fully closed gas circulation process of "hydrogen sulfide fully enclosed arsenic removal method + lime-ferrous salt three-stage neutralization method" is used for treatment. The hydrogen sulfide preparation and addition system, lime slurry preparation and addition system, and ferrous salt preparation and addition system are operated by regulating the PID control system. The specific method is as follows:

[0042] Step 3.1: Pump the degassed arsenic-containing acidic wastewater into the fully enclosed sulfidation reaction tank 2, allowing it to react with hydrogen sulfide gas from the hydrogen sulfide preparation and dosing system 17. The hydrogen sulfide preparation and dosing system uses a "sulfur + methanol + waste heat boiler steam" process to generate hydrogen sulfide gas for arsenic removal, and the reaction is as follows:

[0043]

[0044] To increase the reaction intensity, a pressure pump is used to pressurize the mixture in the sulfurization reaction tank 2, and then the mixture is thoroughly mixed and reacted by the ejector 14 before being returned to the sulfurization reaction tank 2 for circulation. At this time, under acidic conditions, arsenic exists in the form of cations, and arsenic (As) reacts with hydrogen sulfide to produce… Precipitation occurs when other heavy metals react with hydrogen sulfide to form other sulfide precipitates, reducing the arsenic content in wastewater to below 0.05 mg / L.

[0045] Step 3.2: After the reaction in Step 3.1 is completed, the wastewater is dewatered by a sulfidation thickener and then filtered through a plate and frame filter press (I5) to remove the sulfidation slag. The sulfidation slag contains... It can be sold externally; the sulfidation filtrate is pumped into the sulfidation filtrate tank 6, and after being pressurized by a pump, it enters the first neutralization tank 7, the second neutralization tank 8, and the third neutralization tank 9 in sequence along with other wastewater in the buffer tank 20. It reacts with lime from the lime milk preparation and addition system 18 and ferrous salt from the ferrous salt preparation and addition system 19. The specific reaction is as follows:

[0046] When iron salts are added to an aqueous solution, they produce Complexes, such as these substances, strongly adsorb colloidal particles in water to form flocs. These flocs collide with each other through adsorption, bridging, and cross-linking to form flocculated sediments. On the other hand, in water bodies... and It will react with iron salts to produce The reaction produces and Sedimentation; on the other hand, in the water body and After being captured and rolled up by the flocculents, they will be deposited on the flocculents, thereby further removing arsenic from the wastewater;

[0047] The residual hydrogen sulfide liquid in steps 3.1 and 3.2 is returned to the sulfidation reaction tank 2 for recycling through the ejector 14. The residual hydrogen sulfide gas enters the alkali absorption tower 15, where it is absorbed by lime slurry spray. The absorbed residual gas is then returned to the purification process tank 16. Other sulfidation slurries (such as the small amount of calcium sulfide CaS slurry generated) are pumped into the sulfidation filtrate tank 6 for reaction.

[0048] Step 3.3: After the reaction in step 3.2 is completed, the wastewater is dewatered by the neutralization thickener 10 and then filtered by the plate and frame filter press II 11 to produce neutralization residue. The neutralization residue can be sold to cement plants for cement processing. The neutralization filtrate is filtered by the valveless filter 12 and then enters the return water tank 13 for recycling.

[0049] Step 4: When the arsenic (As) content is low, a three-stage neutralization process using lime-ferrous salt is employed. The lime slurry preparation and dosing system, as well as the ferrous salt preparation and dosing system, are controlled by a PID control system. The specific method is as follows:

[0050] Step 4.1: After degassing, the arsenic-containing acidic wastewater is pressurized by a pump and then sequentially enters the first-stage neutralization tank 7, the second-stage neutralization tank 8, and the third-stage neutralization tank 9 along with other wastewater in the buffer tank 20. There, it reacts with lime from the lime slurry preparation and dosing system 18 and ferrous salt from the ferrous salt preparation and dosing system 19. The specific reactions are as follows:

[0051] ;

[0052] At this time, the arsenic in the wastewater is... and It exists in the form of [a substance] and has the property of adsorbing hydroxides. and Will Adsorption and co-precipitation occur on flocculent precipitates; additionally... When the reaction occurs at pH 8, the arsenic (As) content can be reduced to below 0.1 mg / L, and Its consumption is only 0.6 kg / m³.

[0053] Step 4.2: After the reaction in Step 4.1 is completed, the wastewater is dewatered by the neutralization thickener 10 and then filtered by the plate and frame filter press II 11 to produce neutralization residue. The neutralization residue can be sold to cement plants for cement processing. The neutralization filtrate is filtered by the valveless filter 12 and then enters the return water tank 13 for recycling.

[0054] Experimental Example 1.1

[0055] When the arsenic (As) content is >800mg / L, the PID control system is set to handle high arsenic (As) content. When the arsenic (As) content is high, a fully enclosed gas circulation process of "hydrogen sulfide fully enclosed arsenic removal method + lime-iron salt three-stage neutralization method" is used. Random fixed-point sampling is performed, and the detection results before and after wastewater treatment are shown in Table 1.

[0056] Table 1: Comparison data of wastewater with high arsenic (As) content before and after treatment

[0057]

[0058] According to the comparison data of wastewater before and after treatment when the arsenic (As) content is high in Table 1, it can be seen that after the arsenic-containing wastewater is treated by the fully closed gas circulation process of "hydrogen sulfide fully closed arsenic removal method + lime-iron salt three-stage neutralization method", the arsenic (As) content in the wastewater decreases by 99.99%, and the arsenic (As) content can be reduced to below 0.1 mg / L.

[0059] Experimental Example 1.2

[0060] When the arsenic (As) content is <800mg / L, the PID control system is set to have a low arsenic (As) content. When the arsenic (As) content is low, the "lime-iron salt three-stage neutralization method" circulation process is used. Random fixed-point sampling is performed. The detection results before and after wastewater treatment are shown in Table 2.

[0061] Table 2: Comparison data of wastewater before and after treatment when arsenic (As) content is low

[0062]

[0063] According to the comparison data of wastewater before and after treatment when the arsenic (As) content is low in Table 2, it can be seen that after the arsenic-containing wastewater is treated by the "lime-iron salt three-stage neutralization method" circulation process, the arsenic (As) content in the wastewater decreases by 99.99%, and the arsenic (As) content can be reduced to below 0.1 mg / L. Example 2

[0064] This utility model also provides supporting equipment for the treatment and comprehensive utilization process of arsenic-containing acidic wastewater from gold smelting, including a desorption tower 1, which is connected to a sulfidation reaction tank 2. The inlet of the sulfidation reaction tank 2 is connected to a hydrogen sulfide preparation and dosing system 17. The outlet of the sulfidation reaction tank 2 is sequentially connected to a sulfidation thickener 4, a filter press I 5, and a sulfidation filtrate tank 6. The sulfidation filtrate tank 6 is sequentially connected to a first-stage neutralization tank 7, a second-stage neutralization tank 8, a third-stage neutralization tank 9, a neutralization thickener 10, a filter press II 11, a valveless filter 12, and a return water tank 13. A lime slurry preparation and dosing system 18 is connected between the sulfidation filtrate tank 6 and the first-stage neutralization tank 7, and between the second-stage neutralization tank 8 and the third-stage neutralization tank 9. The inlets of the first-stage neutralization tank 7 and the third-stage neutralization tank 9 are connected to a ferrous salt preparation and dosing system 19. The first-stage neutralization tank 7 is also connected to a buffer tank 20, and the desorption tower 1 is also connected to the first-stage neutralization tank 7. The desorption tower 1 is connected to the purification process recovery tank 16 to realize the recovery and utilization of generated SO2 and other gases.

[0065] In Example 2, during operation, arsenic-containing acidic wastewater from gold smelting and air enter degassing tower 1. Degassing tower 1 degasses the arsenic-containing acidic wastewater, and the resulting gases are... The gas is then recycled in the purification process recovery tank 16; the arsenic-containing acidic wastewater after degassing is then processed in the next step according to the arsenic content.

[0066] For wastewater with high arsenic content, it is pumped into sulfidation reaction tank 2. Hydrogen sulfide preparation and addition system 17 adds hydrogen sulfide gas to sulfidation reaction tank 2, causing it to react with arsenic and other heavy metal elements in the wastewater. After the reaction, the wastewater is dewatered by sulfidation thickener 4 and then filtered out by plate and frame filter press 5 to remove sulfidation slag. The sulfidation filtrate is pumped into sulfidation filtrate tank 6. After being pressurized by a pump, the sulfidation filtrate, together with other wastewater in buffer tank 20, enters first neutralization tank 7, second neutralization tank 8, and third neutralization tank 9 in sequence. It reacts with lime from lime milk preparation and addition system 18 and ferrous salt from ferrous salt preparation and addition system 19. After the reaction, the wastewater is dewatered by neutralization thickener 10 and then filtered out by plate and frame filter press II 11 to remove neutralization slag. The neutralization filtrate is then filtered by valveless filter 12 and then enters return water tank 13 for recycling.

[0067] For wastewater with low arsenic content, after being pressurized by a pump, it enters the first neutralization tank 7, the second neutralization tank 8, and the third neutralization tank 9 in sequence along with other wastewater in the buffer tank 20. It reacts with lime from the lime slurry preparation and addition system 18 and ferrous salt from the ferrous salt preparation and addition system 19. After the reaction is completed, the wastewater is dewatered by the neutralization thickener 10 and then filtered by the plate and frame filter press II 11 to remove the neutralization residue. The neutralization filtrate is then filtered by the valveless filter 12 and then enters the return water tank 13 for recycling.

[0068] The sulfidation thickener and filter press I are connected to the sulfidation reaction tank 2 via ejector 14, enabling the recovery and recycling of residual hydrogen sulfide liquid during the dehydration process of the sulfidation thickener 4 and the filtration process of the filter press I 5. The sulfidation thickener 4 and filter press I 5 are connected to the alkali adsorption tower 15 and the purification process recovery tank 16 in sequence via ejector 14. The alkali adsorption tower is connected to the lime slurry preparation and dosing system, which provides lime slurry for the alkali adsorption tower. The lime slurry is sprayed to absorb the residual hydrogen sulfide gas during the sulfidation reaction, thereby realizing the recovery and recycling of the residual hydrogen sulfide gas during the sulfidation reaction. The alkali adsorption tower 15 is also connected to the sulfidation filtrate tank 6, realizing the recovery and recycling of the sulfidation slurry during the sulfidation reaction.

[0069] The present invention has been described in detail above through specific and preferred embodiments. However, those skilled in the art should understand that the present invention is not limited to the embodiments described above. Any modifications, equivalent substitutions, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A process for treating and comprehensively utilizing arsenic-containing acidic wastewater from gold smelting, characterized in that, Includes the following steps: Step 1: The arsenic-containing acidic wastewater from the purification process is degassed using a degassing tower; Step 2: Detect the arsenic content in the degassed wastewater and adjust the PID control system according to the arsenic content. Step 3: When the arsenic (As) content is >800 mg / L, a fully closed gas circulation process of "hydrogen sulfide fully closed arsenic removal method + lime-ferrous salt three-stage neutralization method" is adopted for treatment. The hydrogen sulfide preparation and addition system, lime slurry preparation and addition system, and ferrous salt preparation and addition system are operated by regulating the PID control system. The specific method is as follows: Step 3.1: Pump the degassed arsenic-containing acidic wastewater into a fully enclosed sulfidation reaction tank, allowing it to react with hydrogen sulfide gas from the hydrogen sulfide preparation and dosing system. The hydrogen sulfide gas is prepared using a "sulfur + methanol + waste heat boiler steam" process, and the reaction is as follows: ； ； In the reaction tank, arsenic (As) and other heavy metal elements react with hydrogen sulfide to form sulfide precipitates. Among them, arsenic (As) reacts with hydrogen sulfide to form As2S3 precipitate. At this time, the arsenic content in the wastewater drops to below 0.05 mg / L. Step 3.2: After the reaction in Step 3.1 is completed, the wastewater is dewatered by a sulfidation thickener, then filtered out by a plate and frame filter press to remove sulfidation slag. The sulfidation filtrate is pumped into a sulfidation filtrate tank, pressurized by a pump, and then sequentially fed into a first-stage neutralization tank, a second-stage neutralization tank, and a third-stage neutralization tank along with other wastewater in the buffer tank. The filtrate reacts with lime from the lime slurry preparation and addition system and ferrous salt from the ferrous salt preparation and addition system, as detailed below: When iron salts are added to an aqueous solution, they produce [Fe(H₂O)₆]. 3+ [Fe2(OH)3] 3+ [Fe3(OH)2] 4+ Complexes, these substances strongly adsorb colloidal particles in water to form flocs, and the flocs collide with each other through adsorption, bridging, and cross-linking to form flocculation and sedimentation; on the other hand, AsO3 in the water 3- and AsO4 3- Fe produced by the hydrolysis of iron salt 3+ The reaction produces FeAsO3 and FeAsO4 precipitates; on the other hand, AsO3 in the water... 3- and AsO4 3- After being captured and rolled up by the flocculents, they will be deposited on the flocculents, thereby further removing arsenic from the wastewater; Step 3.3: After the reaction in step 3.2 is completed, the wastewater is dewatered by a neutralization thickener, then filtered by a plate and frame filter press to remove the neutralization residue. The neutralization filtrate is filtered by a valveless filter and then recycled into the return water tank. Step 4: When the arsenic (As) content is ≤800mg / L, a three-stage neutralization process using lime-ferrous salt is adopted. The lime slurry preparation and dosing system and the ferrous salt preparation and dosing system are controlled by adjusting the PID control system. The specific method is as follows: Step 4.1: After degassing, the arsenic-containing acidic wastewater is pressurized by a pump and then sequentially enters the first-stage neutralization tank, the second-stage neutralization tank, and the third-stage neutralization tank along with other wastewater in the buffer tank. The wastewater reacts with lime from the lime slurry preparation and dosing system and ferrous salt from the ferrous salt preparation and dosing system, as follows: ； FeCl3 participates in the reaction at pH 8, which can reduce the arsenic (As) content to below 0.1 mg / L, and the consumption of FeCl3 is only 0.6 kg / m³. Step 4.2: After the reaction in Step 4.1 is completed, the wastewater is dewatered by a neutralization thickener, then filtered by a plate and frame filter press to remove the neutralization residue. The neutralization filtrate is then filtered by a valveless filter and recycled into the return water tank.

2. The process for treating and comprehensively utilizing arsenic-containing acidic wastewater from gold smelting according to claim 1, characterized in that, In step 3.1, in order to increase the reaction intensity, the mixture in the vulcanization reaction tank is pressurized by a pressure pump, then fully mixed and reacted by an injector before being returned to the vulcanization reaction tank for circulation.

3. The process for treating and comprehensively utilizing arsenic-containing acidic wastewater from gold smelting according to claim 1, characterized in that, In steps 3.1 and 3.2, the residual hydrogen sulfide liquid is returned to the sulfidation reaction tank for recycling through the injector, and the residual hydrogen sulfide gas enters the alkali absorption tower, where it is absorbed by lime slurry spray. The absorbed residual gas is then returned to the purification process, and the remaining sulfidation slurry is pumped into the sulfidation filtrate tank for reaction.

4. A supporting equipment for a process of treating and comprehensively utilizing arsenic-containing acidic wastewater from gold smelting, comprising a desorption tower, characterized in that, The desorption tower is connected to the sulfidation reaction tank. The inlet of the sulfidation reaction tank is connected to the hydrogen sulfide preparation and dosing system, and the outlet is sequentially connected to the sulfidation thickener, filter press I, and sulfidation filtrate tank. The sulfidation filtrate tank is sequentially connected to a first-stage neutralization tank, a second-stage neutralization tank, a third-stage neutralization tank, a neutralization thickener, a filter press II, a valveless filter, and a return water tank. A lime slurry preparation and dosing system is connected between the sulfidation filtrate tank and the first-stage neutralization tank, and between the second-stage neutralization tank and the third-stage neutralization tank. The inlets of the first-stage and third-stage neutralization tanks are connected to the ferrous salt preparation and dosing system. The first-stage neutralization tank is also connected to a buffer tank. The desorption tower is also connected to the first-stage neutralization tank. The desorption tower is connected to the recovery tank of the purification process to realize the recovery and utilization of the generated SO2 gas; The sulfidation thickener and filter press I are connected to the sulfidation reaction tank via ejectors to achieve the recovery and recycling of residual hydrogen sulfide liquid; the sulfidation thickener and filter press I are connected in sequence to the alkali adsorption tower and the purification process recovery tank via ejectors; the alkali adsorption tower is connected to the lime slurry preparation and dosing system to achieve the recovery and recycling of residual hydrogen sulfide gas; the alkali adsorption tower is also connected to the sulfidation filtrate tank to achieve the recovery and recycling of sulfidation slurry.

5. The supporting equipment for the process of treating and comprehensively utilizing arsenic-containing acidic wastewater from gold smelting according to claim 4, characterized in that, A booster pump is also connected between the desorption tower and the sulfidation reaction tank, and between the sulfidation filtrate tank and the first neutralization tank.

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