Method for treating lead bismuth smelting wastewater

Abstract

The application belongs to the field of sewage treatment, and specifically discloses a lead-bismuth smelting wastewater treatment method. The method comprises the following steps: (1) performing a sulfidation reaction on waste acid wastewater and desulfurization and denitrification wastewater with a sulfidation agent, and obtaining first filtrate through solid-liquid separation; (2) mixing the first filtrate with chlorine washing wastewater and silver preparation wastewater, and sequentially performing oxidation treatment, iron-based flocculation treatment, fluorine ion precipitation treatment and flocculation treatment, and obtaining second filtrate through solid-liquid separation; (3) adjusting the second filtrate to an alkaline condition, and sequentially performing thallium removal treatment, calcium ion precipitation treatment and secondary flocculation treatment, and obtaining purified filtrate through solid-liquid separation. The application combines modular treatment units with a collaborative process to construct an efficient and economical multi-medium wastewater treatment system.

Description

Technical Field

[0001] This invention belongs to the field of wastewater treatment, specifically relating to a method for treating lead-bismuth smelting wastewater. Background Technology

[0002] The lead-bismuth smelting system encompasses a variety of subsystems, including an oxygen-enriched side-blown furnace (oxidation-reduction-fuming) system for molten pool smelting, a lead-bismuth electrolysis system, a reverberatory furnace system, bismuth refining, tin refining, a silver converter, silver electrolysis, gold recovery, a vacuum furnace system, and a silver separation converter system. These systems work together to achieve efficient lead and bismuth smelting. To support these smelting processes, corresponding auxiliary systems are also provided, such as a flue gas treatment system and a wastewater treatment plant. Since the smelting system primarily processes hazardous waste containing lead and rare metals, the resulting wastewater is diverse, including production wastewater, desulfurization and denitrification wastewater, acid from acid production, wastewater used for cleaning equipment and workers' clothing, and initial rainwater. The wastewater treatment plant must be able to simultaneously treat these combined wastewaters containing harmful substances such as acid, and its design must ensure that these complex wastewaters are treated to high standards and at low cost.

[0003] Currently, most existing wastewater treatment systems and processes primarily target wastewater generated from the smelting of non-ferrous metals such as lead, copper, and zinc. These treatment processes are often decentralized and isolated, resulting in relatively high treatment costs. To improve efficiency and reduce costs, it is necessary to develop and apply more integrated and efficient wastewater treatment technologies. Summary of the Invention

[0004] The purpose of this invention is to provide a method for treating lead-bismuth smelting wastewater, so as to solve at least one technical problem existing in the background art.

[0005] To achieve the above objectives, the technical solution adopted by the present invention is as follows:

[0006] A method for treating wastewater from lead and bismuth smelting includes the following steps:

[0007] (1) The wastewater and desulfurization and denitrification wastewater are subjected to a sulfurization reaction with a sulfurizing agent, and the first filtrate is obtained by solid-liquid separation;

[0008] (2) The first filtrate is mixed with chlorine washing wastewater and silver production wastewater, and then subjected to oxidation treatment, iron-based flocculation treatment, fluoride ion precipitation treatment and flocculation treatment in sequence. After solid-liquid separation, the second filtrate is obtained.

[0009] (3) After adjusting the second filtrate to alkaline conditions, thallium removal treatment, calcium ion precipitation treatment and secondary flocculation treatment are carried out in sequence, and purified filtrate is obtained after solid-liquid separation.

[0010] Furthermore, the process of the present invention also includes step (4):

[0011] After adjusting the pH of laundry water and bath wastewater to 6.0-9.0, they are subjected to oxidation treatment, flocculation treatment and solid-liquid separation in sequence to obtain the third filtrate.

[0012] Furthermore, the process of the present invention also includes step (5):

[0013] After adjusting the pH of the initial rainwater to 6.0-9.0, it is subjected to oxidation treatment, iron-based flocculation treatment, flocculation treatment and solid-liquid separation in sequence to obtain the fourth filtrate.

[0014] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0015] This invention constructs a highly efficient and economical multi-media wastewater treatment system by combining modular treatment units with collaborative processes. This process achieves a harmonious balance between adaptability, economy, and environmental friendliness in wastewater treatment, offering significant advantages such as environmental friendliness, intensive investment, and optimized operating costs.

[0016] This invention employs a modular combination of sulfide precipitation, oxidation, adsorption, and evaporation crystallization, combined with a differentiated and synergistic treatment mechanism, to achieve integrated treatment of multi-media wastewater. By complementing the functions of each process stage, it overcomes traditional technological barriers, forming an environmentally friendly and cost-effective solution.

[0017] This invention is compatible with various complex water qualities, such as wastewater from lead and bismuth smelting, desulfurization and denitrification wastewater, chlorine washing wastewater, silver production wastewater, laundry water, bathing wastewater, and initial rainwater. Through dynamic switching between independent treatment and mixed treatment, it meets the removal requirements of different pollutants and improves the process reuse rate in intensive treatment scenarios.

[0018] This invention establishes a processing unit sharing mechanism to reduce investment in repetitive equipment; and reduces reagent consumption and solid waste generation through optimized process route configuration, thereby lowering treatment costs.

[0019] The synergistic effect of the deep flocculation and evaporation crystallization units in this invention ensures that pollutants such as arsenic and fluorine meet the standards stably, while achieving full-scale treatment of wastewater and avoiding secondary pollution. Detailed Implementation

[0020] The inventors of this application have discovered through research that the complex and diverse wastewater systems generated during lead-bismuth smelting, including acidic wastewater, desulfurization and denitrification wastewater, chlorine washing wastewater, and silver production wastewater, can be targeted for pollutant removal in stages based on the characteristics of the wastewater from each process: for acidic wastewater containing high concentrations of heavy metal ions, a sulfidation-neutralization precipitation method is used to preferentially remove toxic substances such as arsenic; for desulfurization and denitrification wastewater containing thiosulfate and nitrite, catalytic oxidation and complex breaking treatment is implemented; for chlorine washing wastewater containing chloride ions and colloidal impurities, a coagulation-flotation synergistic purification process is designed; and for silver production wastewater rich in precious metals such as silver and bismuth, resource recovery is achieved through displacement precipitation. Finally, a gradient treatment system coupling mechanisms such as chemical precipitation, oxidative decomposition, and coagulation flocculation is used to achieve deep removal of pollutants and wastewater reuse.

[0021] Specifically, it includes the following steps:

[0022] (1) The wastewater and desulfurization and denitrification wastewater are subjected to a sulfurization reaction with a sulfurizing agent, and the first filtrate is obtained by solid-liquid separation;

[0023] (2) The first filtrate is mixed with chlorine washing wastewater and silver production wastewater. After keeping the system under acidic conditions, oxidation treatment, iron-based flocculation treatment, fluoride ion precipitation treatment and flocculation treatment are carried out in sequence. After solid-liquid separation, the second filtrate is obtained.

[0024] (3) After adjusting the second filtrate to alkaline conditions, thallium removal treatment, calcium ion precipitation treatment and secondary flocculation treatment are carried out in sequence, and purified filtrate is obtained after solid-liquid separation.

[0025] In step (1):

[0026] As one of the preferred embodiments of this invention, the vulcanizing agent is a sodium sulfide solution or a sodium hydrosulfide solution with a concentration of 10~20wt%.

[0027] Further preferred is that the amount of the sulfiding agent added is 10-15L of sodium sulfide solution or sodium hydrosulfide solution per 1kg of arsenic, depending on the arsenic content in the wastewater.

[0028] As one of the preferred embodiments of this invention, acid is added before the sulfidation reaction to adjust the pH of the mixed wastewater to 0.5-1.0, and the pH is controlled to 1.2-1.8 during the reaction.

[0029] The acid is further preferably sulfuric acid.

[0030] In step (2):

[0031] As one of the preferred embodiments of this invention, before performing the oxidation treatment, the pH of the mixed solution system is adjusted to 3.0-4.0.

[0032] Further optimization involves adjusting the pH value by adding liquid alkali or caustic soda with a mass concentration of 28% to 32%.

[0033] As one of the preferred embodiments of this invention, the oxidant used in the oxidation treatment is potassium permanganate and / or potassium chlorate.

[0034] Further optimization involves adding 1-5g of oxidant per liter of wastewater, with a reaction time of 2-4 hours.

[0035] As one of the preferred embodiments of this invention, the iron-based flocculant used in the iron-based flocculation treatment is ferric chloride and / or polyferric sulfate.

[0036] Further optimization of the addition amount is 3~10g of iron-based flocculant per liter of wastewater, with a reaction time of 0.5~1h.

[0037] As one of the preferred embodiments of this invention, the fluoride ion precipitation treatment involves adding calcium hydroxide or calcium oxide to the first filtrate.

[0038] Further optimization involves adding a molar amount that is 2.2 to 2.8 times the molar amount of fluoride ions, and adjusting the pH to 8.0 to 9.0 during the fluoride precipitation process.

[0039] As one of the preferred embodiments of this invention, the flocculant used in the flocculation treatment is a PAM solution with a mass concentration of 0.5-1%, with 1-2 ml of flocculant added per 1 L of wastewater, and a reaction time of 5-30 min.

[0040] In step (3):

[0041] As one of the preferred embodiments of this invention, the alkaline conditions are pH 10.0~12.0.

[0042] Further optimization can be achieved by adding liquid caustic soda or caustic soda flakes with a mass concentration of 28% to 32%.

[0043] As one of the preferred embodiments of this invention, the thallium removal process involves adding a thallium removal agent to the second filtrate.

[0044] Further optimization involves adding 0.1~0.5 kg of thallium removal agent per m³ of wastewater, with a reaction time of 20~120 min.

[0045] As one of the preferred solutions in this embodiment, the thallium removal agent can be a commonly available reagent, such as SES-FS thallium removal agent 001 purchased from SEENS.

[0046] As one of the preferred embodiments of this invention, the calcium ion precipitation treatment involves adding sodium carbonate to the second filtrate.

[0047] As one of the preferred embodiments of this invention, the flocculant used in the secondary flocculation treatment is a PAM solution with a mass concentration of 0.5-1%, with 1-2 ml of flocculant added per 1 L of wastewater, and a reaction time of 5-30 min.

[0048] As one of the preferred embodiments of this invention, step (3) further includes:

[0049] The purified filtrate is tested. If As ≤ 0.3 mg / L, F ≤ 20 mg / L, Tl ≤ 0.015 mg / L, and Ca ≤ 200 mg / L, then the treatment meets the standards.

[0050] If As≤0.3mg / L, F≤20mg / L, Tl≤0.015mg / L, and Ca≤200mg / L are not met, then repeat steps (2) and / or (3) for treatment.

[0051] If the arsenic and fluorine content does not meet the standards, repeat step (2); if the thallium and calcium content does not meet the standards, repeat step (3).

[0052] As one of the preferred solutions in this embodiment, in step (3):

[0053] If the TDS of the purified filtrate is greater than 8%, then evaporation and crystallization shall be carried out.

[0054] As one of the preferred solutions in this embodiment, after the purified filtrate meets the standards, sulfuric acid is added to adjust the pH to 7-8 before returning it to the production workshop for reuse.

[0055] As one of the preferred embodiments of this invention, the process of the present invention further includes step (4):

[0056] After adjusting the pH of laundry water and bath wastewater to 6.0-9.0, they are subjected to oxidation treatment, flocculation treatment and solid-liquid separation in sequence to obtain the third filtrate.

[0057] As one of the preferred embodiments in this example, the third filtrate is detected:

[0058] If the third filtrate contains As≤0.3mg / L, F≤20mg / L, Tl≤0.015mg / L, and Ca≤200mg / L, it is qualified; otherwise, return to step (2) and mix it with the first filtrate.

[0059] As one of the preferred solutions in this embodiment, if the third filtrate is qualified, it can be pumped into the production workshop for reuse.

[0060] As one of the preferred embodiments of this invention, the oxidant used in the oxidation treatment is potassium permanganate and / or potassium chlorate.

[0061] Further optimization involves adding 1-5g of oxidant per liter of wastewater, with a reaction time of 2-4 hours.

[0062] As one of the preferred embodiments of this invention, the flocculant used in the flocculation treatment is a PAM solution with a mass concentration of 0.5-1%, with 1-2 ml of flocculant added per 1 L of wastewater, and the reaction time is 5-30 min.

[0063] As one of the preferred embodiments of this invention, the process of the present invention further includes step (5):

[0064] After adjusting the pH of the initial rainwater to 6.0-9.0, it is subjected to oxidation treatment, iron-based flocculation treatment, flocculation treatment and solid-liquid separation in sequence to obtain the fourth filtrate.

[0065] As one of the preferred solutions in this embodiment, if the thallium content in the initial rainwater is >0.015mg / L, then thallium removal treatment is performed before flocculation treatment.

[0066] As one of the preferred solutions in this embodiment, the thallium removal process involves adding a thallium removal agent to the initial rainwater.

[0067] Further optimization is to add it at a rate of per m 3 Add 0.1~0.5 kg of thallium removal agent to the wastewater and react for 20~120 min.

[0068] As one of the preferred solutions in this embodiment, the thallium removal agent can be a commonly available reagent, such as SES-FS thallium removal agent 001 purchased from SEENS.

[0069] As one of the preferred embodiments in this example, the fourth filtrate is detected:

[0070] If the fourth filtrate contains As≤0.3mg / L, F≤20mg / L, Tl≤0.015mg / L, and Ca≤200mg / L, it is qualified; otherwise, repeat step (5) for further processing.

[0071] As one of the preferred solutions in this embodiment, if the fourth filtrate is qualified, it can be pumped into the production workshop for reuse.

[0072] As one of the preferred embodiments of this invention, the oxidant used in the oxidation treatment is potassium permanganate and / or potassium chlorate.

[0073] Further optimization involves adding 1-5g of oxidant per liter of wastewater, with a reaction time of 2-4 hours.

[0074] As one of the preferred embodiments of this invention, the iron-based flocculant used in the iron-based flocculation treatment is ferric chloride and / or polyferric sulfate.

[0075] Further optimization of the addition amount is 3-10g of iron-based flocculant per liter of wastewater, with a reaction time of 0.5-1h.

[0076] As one of the preferred embodiments of this invention, the flocculant used in the flocculation treatment is a PAM solution with a mass concentration of 0.5-1%, with 1-2 ml of flocculant added per 1 L of wastewater, and a reaction time of 5-30 min.

[0077] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0078] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0079] Unless otherwise specified, all raw materials, reagents, instruments and equipment used in this invention can be purchased from the market or prepared by existing methods.

[0080] Example 1

[0081] (1) Prepare 1000ml of mixed wastewater of desulfurization and denitrification wastewater and waste acid wastewater. The raw water test data are shown in Table 1 below.

[0082] Table 1. Composition and impurity content of mixed wastewater (mg / L)

[0083]

[0084] The pH of the mixed wastewater was adjusted to 0.7 with 98% sulfuric acid. 157 ml of 15 wt% sodium sulfide solution was added to carry out the reaction, and the pH of the reaction was controlled to 1.8 with 98% sulfuric acid. The reaction was carried out for 2 hours, and then filtered to obtain the first filtrate.

[0085] (2) The first filtrate was mixed with chlorine-containing wastewater, silver-making wastewater and the third filtrate that failed treatment to obtain a total of 2000 ml of mixed solution. The pH value was adjusted to 4 with 30% liquid alkali, and 6 g of potassium permanganate oxidant was added. The reaction was carried out for 3 h. After the reaction was completed, 20 g of polyferric sulfate was added. After the reaction was complete, 34.4 g of calcium hydroxide was added to remove fluoride. In this embodiment, the fluoride content of the mixed solution was obtained or estimated before the fluoride removal to ensure that the molar amount of calcium hydroxide added was within 2.2 to 2.8 times the molar amount of fluoride ions. During the reaction of calcium hydroxide, the pH value of the solution was adjusted to 9.0 with caustic soda flakes. The reaction was carried out for 2 h, and 3 ml of 0.5% PAM solution was added. After the reaction was carried out for 25 min, the solution was filtered to obtain the second filtrate.

[0086] (3) Slowly add 30% liquid alkali to the second filtrate until the pH reaches 10.5, then add 1g of thallium removal agent (SES-FS thallium removal agent 001 purchased from SAINS in this embodiment) and react for 1 hour. Add 9.6g of sodium carbonate to remove calcium, then add 3ml of 0.5% PAM solution and react for 25 minutes. Place the solution in a settling tank to settle, then filter to obtain purified filtrate.

[0087] The purified filtrate was tested and found to be qualified, with As: 0.1 mg / L, F: 6 mg / L, Tl: 0.005 mg / L, and Ca: 37 mg / L. Other impurities met the GB8978 Class III standard. The TDS of the purified filtrate was tested to be 7.15%.

[0088] Example 2

[0089] (1) Prepare another batch of 1000ml of mixed wastewater of desulfurization and denitrification wastewater and waste acid wastewater. The raw water test data are shown in Table 2 below.

[0090] Table 2. Composition and impurity content of mixed wastewater (mg / L)

[0091]

[0092] The pH of the mixed wastewater was adjusted to 0.6 with 98% sulfuric acid. 47 ml of 18 wt% sodium sulfide solution was added to carry out the reaction, and the pH of the reaction was controlled to 1.4 with 98% sulfuric acid. The reaction was carried out for 1 hour, and then filtered to obtain the first filtrate.

[0093] (2) The first filtrate was mixed with chlorine-containing wastewater and silver-making wastewater to obtain a total of 2000 ml of mixed solution. The pH value was adjusted to 4 with 32% liquid alkali, and 4 g of potassium permanganate oxidant was added. The reaction was carried out for 3 h. After the reaction was completed, 15 g of polyferric sulfate was added. After the reaction was complete, 26.5 g of calcium hydroxide was added to remove fluoride. In this embodiment, the fluoride content of the mixed solution was obtained or estimated before the fluoride removal to ensure that the molar amount of calcium hydroxide added was within 2.2 to 2.8 times the molar amount of fluoride ions. The pH value was adjusted to 8.5 with caustic soda flakes. The reaction was carried out for 2 h, and 3 ml of 0.5% PAM solution was added. After the reaction was carried out for 20 minutes, the solution was filtered to obtain the second filtrate.

[0094] (3) Add 32% liquid alkali to the second filtrate to adjust the pH to 11, then add 0.35g of SES-FS thallium removal agent 001 and react for 1h, add 7.8g of sodium carbonate to remove calcium, add 3ml of 0.5% PAM solution and react for 30min, place it in a settling tank to settle, and then filter to obtain purified filtrate.

[0095] The purified filtrate tested positive for As: 0.03 mg / L, F: 4 mg / L, Tl: 0.008 mg / L, Ca: 110 mg / L, Pb: 0.03 mg / L, Ni: 0.4 mg / L, and Cd: 0.004 mg / L, which met the surface water environmental quality standards.

[0096] (4) Take 1000ml each of laundry water and bath wastewater, mix them, adjust the pH value to 8.5 with 30% liquid alkali, add 4g of potassium permanganate oxidant, react for 2h, then add 3ml of 0.5% PAM solution and react for 20min, then filter to obtain the third filtrate.

[0097] The third filtrate was tested and found to be qualified, with As: 0.02 mg / L, F: 1 mg / L, Tl: 0.003 mg / L, and Ca: 31 mg / L. Other impurities met the GB8978 Class III standard. The TDS of the purified filtrate was tested to be 9.71%, and it was sent to the evaporation and crystallization system for further treatment.

[0098] (5) Take 1000ml of initial rainwater, the raw water test Tl: 0.006mg / L, adjust the pH value to 9 by adding 30% liquid alkali, add 2g of potassium permanganate, react for 2h, add 3g of polyferric sulfate, react for 0.5h, add 1.5ml of 0.5% PAM solution, react for 10min, filter by pressure, and obtain the fourth filtrate;

[0099] The fourth filtrate was tested and found to have the following properties: pH: 9, As: 0.05 mg / L, F: 3 mg / L, Tl: 0.006 mg / L, Ca: 18 mg / L. The remaining impurities met the GB8978 Class III standard.

[0100] Example 3

[0101] (1) Prepare 1000ml of mixed wastewater of desulfurization and denitrification wastewater and waste acid wastewater. The raw water test data are shown in Table 3 below.

[0102] Table 3. Composition and impurity content of mixed wastewater (mg / L)

[0103]

[0104] The pH of the mixed wastewater was adjusted to 0.8 with 98% sulfuric acid. 240 ml of 12 wt% sodium sulfide solution was added to carry out the reaction, and the pH of the reaction was controlled to 1.3 with 98% sulfuric acid. The reaction was carried out for 2 hours, and then filtered to obtain the first filtrate.

[0105] (2) The first filtrate was mixed with chlorine-containing wastewater, silver-making wastewater, and the unqualified third filtrate in this example to obtain a total of 2000 ml of mixed solution. The pH value was adjusted to 3.5 with 32% liquid alkali, and 5 g of potassium permanganate oxidant was added. After the reaction was completed, 7 g of polyferric sulfate was added. After the reaction was complete, 26.2 g of calcium hydroxide was added to remove fluoride. In this example, the fluoride content detection data of the mixed solution was obtained or estimated before the fluoride removal to ensure that the molar amount of calcium hydroxide added was within 2.2 to 2.8 times the molar amount of fluoride ions. The pH value was adjusted to 8.5 with caustic soda flakes, and 4 ml of 0.5% PAM solution was added. After reacting for 28 min, the mixture was filtered to obtain the second filtrate.

[0106] (3) Add 32% liquid alkali to the second filtrate to adjust the pH to 10.2, then add 0.55g of SES-FS thallium removal agent 001 and react for 80min. Add 10.1g of sodium carbonate to remove calcium, then add 3.5ml of 0.5% PAM solution and react for 15min. Place the solution in a settling tank to settle, then filter to obtain purified filtrate.

[0107] The purified filtrate was tested, and the following values ​​were found: As: 45 mg / L, F: 5 mg / L, Tl: 0.011 mg / L, Pb: 0.03 mg / L, Ca: 12 mg / L. Only arsenic exceeded the standard, so step (2) was repeated:

[0108] Adjust the pH to 3.5 with 32% caustic soda solution, add 5g of potassium permanganate oxidant, and after the reaction is complete, add 7g of polyferric sulfate. After the reaction is complete, adjust the pH to 8.5 with caustic soda flakes, add 4ml of 0.5% PAM solution, and filter under pressure after reacting for 28 minutes to obtain the second filtrate.

[0109] Since the thallium and calcium in the filtrate are already within acceptable limits, step (3) is not actually necessary. Testing the purified filtrate from step (2) yields the following results:

[0110] As: 0.02 mg / L, F: 5 mg / L, Tl: 0.010 mg / L, Pb: 0.03 mg / L, Ca: 13 mg / L, all within acceptable limits. Other impurities meet the GB8978 Class III standard. The TDS of the purified filtrate was 4.96%.

[0111] (4) Take 1000ml each of laundry water and bath wastewater, mix them, adjust the pH value to 6 with 30% liquid alkali, add 3g of potassium permanganate oxidant, react for 2h, then add 2.4ml of 0.5% PAM solution and react for 15min. Filter to obtain the third filtrate. The test results are As: 0.2mg / L, F: 2mg / L, Tl: 0.018mg / L, Ca: 53mg / L. The test results are unqualified. Return the unqualified third filtrate to step (2) and mix it with the first filtrate for treatment.

[0112] (5) Take 1000ml of initial rainwater. The raw water Tl is 0.017mg / L. Adjust the pH to 9 by adding 30% liquid alkali. Add 4g of potassium permanganate and react for 2h. Add 5g of polyferric sulfate and react for 1h. Add 0.19g of SES-FS thallium removal agent 001 and react for 60min. Add 1.2ml of 0.7% PAM solution and react for 30min. Filter by pressure to obtain the fourth filtrate.

[0113] The fourth filtrate was tested and found to contain: As: 0.03 mg / L, F: 1 mg / L, Tl: 0.005 mg / L, Pb: 0.03 mg / L, and Ca: 23 mg / L.

[0114] The above are merely preferred embodiments of the present invention and are not intended to limit the invention. Various modifications and variations can be made to the present invention by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of the present invention.

Claims

1. A method for treating wastewater from lead and bismuth smelting, characterized in that, Includes the following steps: (1) The wastewater and desulfurization and denitrification wastewater are subjected to a sulfidation reaction with a sulfiding agent, and the first filtrate is obtained by solid-liquid separation; the sulfiding agent is a sodium sulfide solution or a sodium hydrosulfide solution with a concentration of 10~20wt%; the amount of sulfiding agent added is based on the arsenic content in the wastewater, with 10~15L of sodium sulfide solution or sodium hydrosulfide solution added for every 1kg of arsenic; sulfuric acid is added before the sulfidation reaction to adjust the pH of the mixed wastewater to 0.5~1.0; the pH is controlled at 1.2~1.8 during the reaction. (2) The first filtrate is mixed with chlorine washing wastewater and silver production wastewater, and subjected to oxidation treatment, iron-based flocculation treatment, fluoride ion precipitation treatment and flocculation treatment in sequence. After solid-liquid separation, the second filtrate is obtained. Before the oxidation treatment, the pH of the mixed solution system is adjusted to 3.0-4.0 by adding liquid alkali or flake alkali with a mass concentration of 28%-32%. The oxidant used in the oxidation treatment is potassium permanganate and / or potassium chlorate, and the addition amount is 1-5g of oxidant per liter of wastewater. The reaction time is 2-4h. The iron-based flocculant used in the iron-based flocculation treatment is ferric chloride and / or polyferric sulfate, and the addition amount is 3-10g per liter of wastewater. Iron-based flocculant, reaction time 0.5-1h; the fluoride ion precipitation treatment involves adding calcium hydroxide or calcium oxide to the first filtrate, the molar amount of which is 2.2-2.8 times the molar amount of fluoride ions, and adjusting the pH to 8.0-9.0 during the fluoride precipitation process; the flocculant used in the flocculation treatment is a 0.5-1% PAM solution, 1-2 ml of flocculant is added per 1L of wastewater, and the reaction time is 5-30 min; (3) The second filtrate is adjusted to an alkaline condition of pH 10.0-12.0 by adding liquid alkali or flake alkali with a mass concentration of 28%-32%. Then, thallium removal treatment, calcium ion precipitation treatment and secondary flocculation treatment are carried out in sequence. After solid-liquid separation, purified filtrate is obtained. The thallium removal treatment is to add thallium removal agent to the second filtrate. The amount of thallium removal agent added is 0.1-0.5 kg per m³ of wastewater, and the reaction time is 20-120 min. The calcium ion precipitation treatment is to add sodium carbonate to the second filtrate. The flocculant used in the secondary flocculation treatment is a PAM solution with a mass concentration of 0.5-1%. 1-2 ml of flocculant is added per 1 L of wastewater, and the reaction time is 5-30 min. The purified filtrate is tested. If As ≤ 0.3 mg / L, F ≤ 20 mg / L, Tl ≤ 0.015 mg / L, and Ca ≤ 200 mg / L, then the treatment meets the standards. If As≤0.3mg / L, F≤20mg / L, Tl≤0.015mg / L, and Ca≤200mg / L are not met, then repeat steps (2) and / or (3) for treatment.

2. The processing method as described in claim 1, characterized in that, It also includes step (4): After adjusting the pH of laundry water and bath wastewater to 6.0-9.0, they are subjected to oxidation treatment, flocculation treatment and solid-liquid separation in sequence to obtain the third filtrate.

3. The processing method as described in claim 2, characterized in that, Test the third filtrate: If the third filtrate contains As≤0.3mg / L, F≤20mg / L, Tl≤0.015mg / L, and Ca≤200mg / L, it is qualified; otherwise, return to step (2) and mix it with the first filtrate.

4. The processing method as described in claim 1, characterized in that, It also includes step (5): After adjusting the pH of the initial rainwater to 6.0-9.0, it was subjected to oxidation treatment, iron-based flocculation treatment, flocculation treatment and solid-liquid separation in sequence to obtain the fourth filtrate. If the thallium content in the initial rainwater is >0.015 mg / L, then thallium removal treatment should be carried out before flocculation treatment.

5. The processing method as described in claim 4, characterized in that, Test the fourth filtrate: If the pH of the fourth filtrate is 7.0~9.0, As≤0.3mg / L, F≤20mg / L, Tl≤0.015mg / L, and Ca≤200mg / L, it is qualified; otherwise, repeat step (5) for treatment.

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