Lead-bismuth smelting wastewater treatment method

Abstract

The invention belongs to the field of sewage treatment, and particularly discloses a lead-bismuth smelting wastewater treatment method. Comprising the following steps: (1) carrying out vulcanization reaction on waste acid wastewater, desulfurization and denitrification wastewater and a vulcanizing agent, and carrying out solid-liquid separation to obtain a first filtrate; (2) mixing the first filtrate with chlorine washing wastewater and silver production wastewater, sequentially carrying out oxidation treatment, iron-based flocculation treatment, fluorine ion precipitation treatment and flocculation treatment, and carrying out solid-liquid separation to obtain a second filtrate; and (3) adjusting the second filtrate to an alkaline condition, sequentially carrying out thallium removal treatment, calcium ion precipitation treatment and secondary flocculation treatment, and carrying out solid-liquid separation to obtain a purified filtrate. The efficient and economical multi-medium wastewater treatment system is constructed by combining a modular treatment unit with a synergistic process.

Description

Technical Field

[0001] The present invention belongs to the field of sewage treatment, and particularly relates to a method for treating lead-bismuth smelting wastewater. Background Art

[0002] The lead-bismuth smelting system includes a variety of different subsystems, such as the submerged bath smelting oxygen-enriched side-blown furnace (oxidation-reduction-fuming) system, lead-bismuth electrolysis, reverberatory furnace system, bismuth refining, tin refining, silver converter, silver electrolysis, gold recovery, vacuum furnace system, silver separation converter system, etc. These systems work together to achieve efficient smelting of lead and bismuth. To support these smelting processes, corresponding supporting systems are also equipped, such as a flue gas treatment system and a sewage treatment station. Since the raw materials processed by the smelting system are mainly hazardous wastes containing lead and rare scattered metals, a variety of wastewater is generated, including production wastewater, desulfurization and denitrification wastewater, waste acid generated during the sulfuric acid production process, wastewater used for cleaning equipment and the clothes of staff, and initial rainwater. The sewage treatment station must be able to simultaneously treat this comprehensive wastewater containing harmful substances such as waste acid, and in terms of design, it must ensure that these complex wastewaters can be treated with high standards and low costs.

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

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

[0005] To achieve the above purpose, the technical solution adopted by the present invention is: A method for treating lead-bismuth smelting wastewater, comprising the following steps: (1) Subject the waste acid wastewater and desulfurization and denitrification wastewater to a sulfidation reaction with a sulfiding agent, and obtain a first filtrate through solid-liquid separation; (2) Mix the first filtrate with chlorine-washing wastewater and silver-making wastewater, and successively perform oxidation treatment, iron-based flocculation treatment, fluoride ion precipitation treatment, and flocculation treatment, and obtain a second filtrate after solid-liquid separation; (3) After adjusting the second filtrate to an alkaline condition, successively perform thallium removal treatment, calcium ion precipitation treatment, and secondary flocculation treatment, and obtain a purified filtrate after solid-liquid separation.

[0006] Further, the process of the present invention further includes step (4): Adjust the pH of the laundry water and bathing wastewater to 6.0 - 9.0, and successively perform oxidation treatment, flocculation treatment, and solid-liquid separation to obtain a third filtrate.

[0007] Further, the process of the present invention further includes step (5): After adjusting the pH of the initial rainwater to 6.0 - 9.0, oxidation treatment, iron-based flocculation treatment, flocculation treatment, and solid-liquid separation are carried out in sequence to obtain the fourth filtrate.

[0008] Compared with the prior art, the beneficial effects of the present invention are as follows: By combining modular treatment units with a collaborative process, the present invention constructs an efficient and economical multi-media wastewater treatment system. This process realizes the organic unity of wastewater treatment adaptability, economy, and environmental protection, and has significant advantages of environmental friendliness, intensive investment, and optimized operating costs.

[0009] The present invention adopts a modular combination of sulfide precipitation - oxidation - adsorption - evaporation crystallization, combined with a medium-separation - collaborative treatment mechanism, to achieve the integrated disposal of multi-media wastewater. Through the complementary functions of process sections, it breaks through traditional technical barriers and forms an environmentally friendly and investment-intensive solution.

[0010] The present invention is compatible with various complex water qualities such as waste acid wastewater, desulfurization and denitrification wastewater, chlorine-washing wastewater, silver-making wastewater, laundry water, bath wastewater, and initial rainwater in lead-bismuth smelting. By dynamically switching between independent treatment and mixed treatment, it meets the removal requirements of different pollution factors and realizes an increase in the process reuse rate in the intensive disposal scenario.

[0011] The present invention establishes a shared mechanism for treatment units to reduce repetitive equipment investment; through the optimized configuration of the process route, it reduces the consumption of chemical agents and the generation of solid waste, and reduces the treatment cost.

[0012] The deep flocculation and evaporation crystallization units of the present invention act synergistically to ensure that pollutants such as arsenic and fluorine meet the standards stably, and at the same time realize the full quantification treatment of wastewater, avoiding secondary pollution. Detailed implementation manners

[0013] The inventors of the present application have found through research that for the multi-component and complex system of waste acid wastewater, desulfurization and denitrification wastewater, chlorine-washing wastewater, silver-making wastewater, etc. generated in the lead-bismuth smelting process, targeted removal of pollutants can be implemented in stages according to the characteristics of the wastewater in each section: for waste acid wastewater containing high-concentration heavy metal ions, sulfide - neutralization precipitation method is used to preferentially remove toxic substances such as arsenic; catalytic oxidation and complex-breaking treatment is carried out on desulfurization and denitrification wastewater containing thiosulfate and nitrite; a coagulation - air flotation collaborative purification process is designed for chlorine-washing wastewater containing chloride ions and colloidal impurities; for silver-making wastewater rich in precious metals such as silver and bismuth, resource recovery is achieved through displacement precipitation, and finally, through a gradient treatment system coupling mechanisms such as chemical precipitation, oxidation decomposition, and coagulation and flocculation, deep removal of pollutants and wastewater reuse are realized.

[0014] Specifically, it includes the following steps: (1) Carry out a sulfidation reaction on the contaminated acid wastewater and the desulfurization and denitrification wastewater with a sulfiding agent, and obtain a first filtrate through solid-liquid separation; (2) Mix the first filtrate with the chlorine-washing wastewater and the silver-making wastewater. After maintaining the system under acidic conditions, carry out oxidation treatment, iron-based flocculation treatment, fluoride ion precipitation treatment, and flocculation treatment in sequence. After solid-liquid separation, obtain a second filtrate; (3) Adjust the second filtrate to an alkaline condition, and then carry out thallium removal treatment, calcium ion precipitation treatment, and secondary flocculation treatment in sequence. After solid-liquid separation, obtain a purified filtrate.

[0015] In step (1): As one of the preferred solutions of this embodiment, the sulfiding agent is a sodium sulfide solution or a sodium hydrosulfide solution, and the concentration is 10-20 wt%.

[0016] Further preferably, the addition amount of the sulfiding agent is based on the arsenic content in the wastewater, and 10-15 L of the sodium sulfide solution or the sodium hydrosulfide solution is added per 1 kg of arsenic.

[0017] As one of the preferred solutions of this embodiment, before the sulfidation reaction, add acid to adjust the pH of the mixed wastewater to 0.5-1.0, and control the pH to be 1.2-1.8 during the reaction process.

[0018] Further preferably, the acid is sulfuric acid.

[0019] In step (2): As one of the preferred solutions of this embodiment, before carrying out the oxidation treatment, it further includes adjusting the pH of the mixed solution system to 3.0-4.0.

[0020] Further preferably, the pH value is adjusted by adding liquid caustic soda or flake caustic soda with a mass concentration of 28%-32%.

[0021] As one of the preferred solutions of this embodiment, the oxidizing agent used in the oxidation treatment is potassium permanganate and / or potassium chlorate.

[0022] Further preferably, the addition amount is 1-5 g of the oxidizing agent added per liter of wastewater, and the reaction time is 2-4 h.

[0023] As one of the preferred solutions of this embodiment, the iron-based flocculant used in the iron-based flocculation treatment is ferric chloride and / or polyferric sulfate.

[0024] Further preferably, the addition amount is 3-10 g of the iron-based flocculant added per liter of wastewater, and the reaction time is 0.5-1 h.

[0025] As one of the preferred solutions of this embodiment, the fluoride ion precipitation treatment is to add calcium hydroxide or calcium oxide to the first filtrate.

[0026] Further preferably, its molar addition amount is 2.2 to 2.8 times the molar amount of fluoride ions, and the pH is adjusted to 8.0 to 9.0 during the fluorine precipitation process.

[0027] As one of the preferred solutions of this embodiment, the flocculant used in the flocculation treatment is a PAM solution with a mass concentration of 0.5 to 1%, 1 to 2 ml of the flocculant is added to each 1 L of wastewater, and the reaction time is 5 to 30 min.

[0028] In step (3): As one of the preferred solutions of this embodiment, the alkaline condition is pH 10.0 to 12.0.

[0029] Further preferably, it is adjusted by adding liquid caustic soda or flake caustic soda with a mass concentration of 28% to 32%.

[0030] As one of the preferred solutions of this embodiment, the thallium removal treatment is to add a thallium remover to the second filtrate.

[0031] Further preferably, its addition amount is 0.1 to 0.5 kg of the thallium remover added to each m³ of wastewater, and the reaction time is 20 to 120 min.

[0032] As one of the preferred solutions of this embodiment, common reagents on the market can be used as the thallium remover, such as SES-FS thallium remover 001 purchased from Sains.

[0033] As one of the preferred solutions of this embodiment, the calcium ion precipitation treatment is to add sodium carbonate to the second filtrate.

[0034] As one of the preferred solutions of this embodiment, the flocculant used in the secondary flocculation treatment is a PAM solution with a mass concentration of 0.5 to 1%, 1 to 2 ml of the flocculant is added to each 1 L of wastewater, and the reaction time is 5 to 30 min.

[0035] As one of the preferred solutions of this embodiment, step (3) further includes: Detect the purified filtrate. If As ≤ 0.3 mg / L, F ≤ 20 mg / L, Tl ≤ 0.015 mg / L, and Ca ≤ 200 mg / L, the treatment is up to standard; If it does not meet As ≤ 0.3 mg / L, F ≤ 20 mg / L, Tl ≤ 0.015 mg / L, and Ca ≤ 200 mg / L, then cycle steps (2) and / or (3) for treatment.

[0036] If the arsenic and fluorine contents do not meet the standards, repeat step (2) for treatment; if the thallium and calcium contents do not meet the standards, repeat step (3) for treatment.

[0037] As one of the preferred solutions of this embodiment, in step (3): If the TDS of the purified filtrate is detected to be > 8%, evaporation crystallization is carried out.

[0038] As one of the preferred solutions of this embodiment, after the purified filtrate is treated to meet the standards, sulfuric acid is added to adjust the pH to 7 - 8, and then it is returned to the production workshop for reuse.

[0039] As one of the preferred solutions of this embodiment, the process of the present invention further includes step (4): After adjusting the pH of laundry water and bath wastewater to 6.0 - 9.0, oxidation treatment, flocculation treatment and solid-liquid separation are carried out in sequence to obtain the third filtrate.

[0040] As one of the preferred solutions of this embodiment, the third filtrate is detected: If As ≤ 0.3 mg / L, F ≤ 20 mg / L, Tl ≤ 0.015 mg / L, Ca ≤ 200 mg / L in the third filtrate, it is qualified; otherwise, it is returned to step (2) for mixing treatment with the first filtrate.

[0041] As one of the preferred solutions of this embodiment, if the third filtrate is qualified, it can be pumped into the production workshop for reuse.

[0042] As one of the preferred solutions of this embodiment, the oxidant used in the oxidation treatment is potassium permanganate and / or potassium chlorate.

[0043] Further preferably, the addition amount is 1 - 5 g of oxidant per liter of wastewater, and the reaction time is 2 - 4 h.

[0044] As one of the preferred solutions of this embodiment, the flocculant used in the 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.

[0045] As one of the preferred solutions of this embodiment, the process of the present invention further includes step (5): After adjusting the pH of the initial rainwater to 6.0 - 9.0, oxidation treatment, iron-based flocculation treatment, flocculation treatment and solid-liquid separation are carried out in sequence to obtain the fourth filtrate.

[0046] As one of the preferred solutions of this embodiment, if the thallium content in the initial rainwater > 0.015 mg / L, thallium removal treatment is carried out and then flocculation treatment is carried out.

[0047] As one of the preferred solutions of this embodiment, the thallium removal treatment is to add a thallium removal agent to the initial rainwater.

[0048] Further preferably, the addition amount is 0.1 - 0.5 kg of thallium removal agent per cubic meter of wastewater, and the reaction time is 20 - 120 min. 3 0.1 - 0.5 kg of thallium removal agent is added to the wastewater, and the reaction time is 20 - 120 min.

[0049] As one of the preferred solutions of this embodiment, the thallium removal agent can be a common reagent on the market, such as the SES-FS thallium removal agent 001 purchased from Sains.

[0050] As one of the preferred solutions of this embodiment, detect the fourth filtrate: If As ≤ 0.3 mg / L, F ≤ 20 mg / L, Tl ≤ 0.015 mg / L, and Ca ≤ 200 mg / L in the fourth filtrate, it is qualified; otherwise, recycle and process according to step (5).

[0051] As one of the preferred solutions of this embodiment, if the fourth filtrate is qualified, it can be pumped into the production workshop for reuse.

[0052] As one of the preferred solutions of this embodiment, the oxidants used in the oxidation treatment are potassium permanganate and / or potassium chlorate.

[0053] Further preferably, the addition amount is 1 - 5 g of oxidant added per liter of wastewater, and the reaction time is 2 - 4 h.

[0054] As one of the preferred solutions of this embodiment, the iron-based flocculants used in the iron-based flocculation treatment are ferric chloride and / or polyferric sulfate.

[0055] Further preferably, the addition amount is 3 - 10 g of iron-based flocculant added per liter of wastewater, and the reaction time is 0.5 - 1 h.

[0056] As one of the preferred solutions of this embodiment, the flocculant used in the 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.

[0057] To facilitate the understanding of the present invention, the following will describe the present invention more comprehensively and in detail in combination with preferred embodiments, but the protection scope of the present invention is not limited to the following specific embodiments.

[0058] Unless otherwise defined, all professional terms used hereinafter have the same meaning as commonly understood by those skilled in the art. The professional terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the protection scope of the present invention.

[0059] Unless otherwise specifically stated, all kinds of raw materials, reagents, instruments, and equipment used in the present invention can be obtained through market purchase or can be prepared by existing methods.

[0060] Example 1 (1) Prepare 1000 ml of the mixed wastewater of desulfurization and denitrification wastewater and waste acid wastewater, and the raw water detection data is shown in Table 1 below.

[0061] Table 1 Composition and impurity content of the mixed wastewater (mg / L) Adjust the pH value of the mixed wastewater to 0.7 with 98% sulfuric acid, add 157 ml of 15 wt% sodium sulfide solution for reaction, and control the pH value during the reaction to 1.8 with 98% sulfuric acid. React for 2 h, and then perform pressure filtration after the reaction to obtain the first filtrate.

[0062] (2) Mix the first filtrate with the chlorine-containing wastewater, silver-making wastewater, and the unqualified third filtrate to obtain a total of 2000 ml of the mixed solution. Adjust the pH value to 4 with 30% liquid caustic soda, add 6 g of potassium permanganate oxidant, and react for 3 h. After the reaction is completed, add 20 g of polyferric sulfate. After the reaction is complete, add 34.4 g of calcium hydroxide to remove fluorine. In this example, the fluorine content detection data of the mixed solution is obtained or estimated before defluorination to ensure that the molar addition amount of calcium hydroxide is within 2.2 - 2.8 times the molar amount of fluoride ions. During the reaction of calcium hydroxide, adjust the pH value of the solution to 9.0 with flake caustic soda, react for 2 h, add 3 ml of 0.5% PAM solution, and perform pressure filtration after reacting for 25 min to obtain the second filtrate.

[0063] (3) Slowly drop 30% liquid caustic soda into the second filtrate until the pH reaches 10.5, then add 1 g of thallium remover (in this example, SES-FS thallium remover 001 purchased from Sains) and react for 1 h. Add 9.6 g of sodium carbonate to remove calcium, add 3 ml of 0.5% PAM solution and react for 25 min, place it in a settling tank for sedimentation, and then filter to obtain the purified filtrate.

[0064] Detect that the purified filtrate is qualified, with As: 0.1 mg / L, F: 6 mg / L, Tl: 0.005 mg / L, Ca: 37 mg / L, and the remaining impurity elements meet the third-level standard of GB8978. Detect that the TDS of the purified filtrate is 7.15%.

[0065] Example 2 (1) Prepare another batch of 1000 ml of the mixed wastewater of desulfurization and denitrification wastewater and waste acid wastewater, and its raw water detection data is shown in Table 2 below.

[0066] Table 2 Composition and impurity content of the mixed wastewater (mg / L) Adjust the pH value of the mixed wastewater to 0.6 with 98% sulfuric acid, add 47 ml of 18 wt% sodium sulfide solution for reaction, and control the pH value during the reaction to 1.4 with 98% sulfuric acid. React for 1 h, and then perform pressure filtration after the reaction to obtain the first filtrate.

[0067] (2) Mix the first filtrate with chlorine-containing wastewater and silver-making wastewater to obtain a total of 2000 ml of mixed liquid. Adjust the pH value to 4 with 32% liquid caustic soda, add 4 g of potassium permanganate oxidant, and react for 3 h. After the reaction is completed, add 15 g of polyferric sulfate. After the reaction is complete, add 26.5 g of calcium hydroxide to remove fluorine. In this example, the fluorine content detection data of the mixed liquid is obtained or estimated before defluorination to ensure that the molar addition amount of calcium hydroxide is within 2.2 to 2.8 times the molar amount of fluoride ions. Then adjust the pH value to 8.5 with caustic soda, react for 2 h, add 3 ml of 0.5% PAM solution, and perform pressure filtration after reacting for 20 minutes to obtain the second filtrate.

[0068] (3) After adding 32% liquid caustic soda to the second filtrate to adjust the pH to 11, add 0.35 g of thallium removal agent SES-FS 001 and react for 1 h. Add 7.8 g of sodium carbonate to remove calcium, add 3 ml of 0.5% PAM solution and react for 30 min. Place it in a settling tank for sedimentation, and then filter to obtain the purified filtrate.

[0069] The detected As in the purified filtrate is 0.03 mg / L, F is 4 mg / L, Tl is 0.008 mg / L, Ca is 110 mg / L, Pb is 0.03 mg / L, Ni is 0.4 mg / L, and Cd is 0.004 mg / L, meeting the surface water environmental quality standard.

[0070] (4) Take 1000 ml of laundry water and 1000 ml of bath wastewater respectively. After mixing, adjust the pH value to 8.5 with 30% liquid caustic soda, add 4 g of potassium permanganate oxidant, and react for 2 h. Then add 3 ml of 0.5% PAM solution and react for 20 min, and perform pressure filtration to obtain the third filtrate; The third filtrate is detected to be qualified, with As: 0.02 mg / L, F: 1 mg / L, Tl: 0.003 mg / L, Ca: 31 mg / L, and the remaining impurity elements meeting the third-level standard of GB8978. The detected TDS of the purified filtrate is 9.71%, and it is sent to the evaporation crystallization system for treatment.

[0071] (5) Take 1000 ml of initial rainwater. The detected Tl in the raw water is 0.006 mg / L. Adjust the pH value to 9 by adding 30% liquid caustic soda, add 2 g of potassium permanganate, react for 2 h, add 3 g of polyferric sulfate, react for 0.5 h, add 1.5 ml of 0.5% PAM solution and react for 10 min, and perform pressure filtration to obtain the fourth filtrate; Detect the fourth filtrate, with pH: 9, As: 0.05 mg / L, F: 3 mg / L, Tl: 0.006 mg / L, Ca: 18 mg / L, and the remaining impurity elements meeting the third-level standard of GB8978.

[0072] Example 3 (1) Prepare 1000 ml of the mixed wastewater of desulfurized and denitrified wastewater and waste acid wastewater, and the original water detection data are shown in Table 3 below.

[0073] Table 3 Composition and impurity content of the mixed wastewater (mg / L) Adjust the pH value of the mixed wastewater to 0.8 with 98% sulfuric acid, add 240 ml of 12 wt% sodium sulfide solution for reaction, and control the pH value during the reaction process to 1.3 with 98% sulfuric acid. React for 2 h, and then perform pressure filtration after the reaction to obtain the first filtrate.

[0074] (2) Mix the first filtrate with the chlorine-containing wastewater, silver-making wastewater, and the unqualified third filtrate in this example to obtain a total of 2000 ml of the mixed solution. Adjust the pH value to 3.5 with 32% liquid caustic soda, add 5 g of potassium permanganate oxidant, add 7 g of polyferric sulfate after the reaction is completed. After the reaction is complete, add 26.2 g of calcium hydroxide to remove fluorine. In this example, obtain the fluorine content detection data of the mixed solution before defluorination or make an estimate to ensure that the molar addition amount of calcium hydroxide is within 2.2 to 2.8 times the molar amount of fluoride ions. Then adjust the pH value to 8.5 with caustic soda, add 4 ml of 0.5% PAM solution, and perform pressure filtration after reacting for 28 min to obtain the second filtrate.

[0075] (3) After adding 32% liquid caustic soda to the second filtrate to adjust the pH to 10.2, add 0.55 g of thallium removal agent SES-FS 001 and react for 80 min, add 10.1 g of sodium carbonate to remove calcium, add 3.5 ml of 0.5% PAM solution and react for 15 min, place it in a settling tank for sedimentation, and then filter to obtain the purified filtrate.

[0076] Detect the purified filtrate, in which As: 45 mg / L, F: 5 mg / L, Tl: 0.011 mg / L, Pb: 0.03 mg / L, Ca: 12 mg / L. Only arsenic exceeds the standard. Repeat step (2): Adjust the pH value to 3.5 with 32% liquid caustic soda, add 5 g of potassium permanganate oxidant, add 7 g of polyferric sulfate after the reaction is completed. After the reaction is complete, adjust the pH value to 8.5 with caustic soda, add 4 ml of 0.5% PAM solution, and perform pressure filtration after reacting for 28 min to obtain the second filtrate.

[0077] Since the thallium and calcium in the filtrate are already qualified, step (3) is actually not required. Detect the purified filtrate after repeating treatment step (2) to obtain: As: 0.02 mg / L, F: 5 mg / L, Tl: 0.010 mg / L, Pb: 0.03 mg / L, Ca: 13 mg / L, qualified. The other impurity elements meet the third-level standard of GB8978. Detect that the TDS of the purified filtrate is 4.96%.

[0078] (4) Take 1000 ml of laundry water and 1000 ml of bath wastewater respectively. After mixing, adjust the pH value to 6 with 30% liquid caustic soda. Add 3 g of potassium permanganate oxidant and react for 2 h. Then add 2.4 ml of 0.5% PAM solution and react for 15 min. Filter press to obtain the third filtrate. The test results are as follows: As: 0.2 mg / L, F: 2 mg / L, Tl: 0.018 mg / L, Ca: 53 mg / L. Since the test results are unqualified, return the unqualified third filtrate to step (2) and mix it with the first filtrate for treatment.

[0079] (5) Take 1000 ml of initial rainwater. The original water is tested for Tl: 0.017 mg / L. Adjust the pH value to 9 by adding 30% liquid caustic soda; add 4 g of potassium permanganate and react for 2 h; add 5 g of polyferric sulfate and react for 1 h; add 0.19 g of SES-FS thallium removal agent 001 and react for 60 min; add 1.2 ml of 0.7% PAM solution and react for 30 min. Filter press to obtain the fourth filtrate. Test the fourth filtrate: As: 0.03 mg / L, F: 1 mg / L, Tl: 0.005 mg / L, Pb: 0.03 mg / L, Ca: 23 mg / L.

[0080] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, various changes and modifications can be made to the present invention. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the scope of the present invention.

Claims

1. A method for treating lead-bismuth smelting wastewater, characterized in that, It includes the following steps: (1) Carry out a sulfidation reaction on the contaminated acid wastewater and the desulfurization and denitrification wastewater with a sulfiding agent, and obtain a first filtrate through solid-liquid separation; (2) Mix the first filtrate with the chlorine-washing wastewater and the silver-making wastewater, and successively carry out oxidation treatment, iron-based flocculation treatment, fluoride ion precipitation treatment and flocculation treatment, and obtain a second filtrate after solid-liquid separation; (3) After adjusting the second filtrate to an alkaline condition, successively carry out thallium removal treatment, calcium ion precipitation treatment and secondary flocculation treatment, and obtain a purified filtrate after solid-liquid separation.

2. The processing method according to claim 1, characterized in that, In step (1): The sulfiding agent is a sodium sulfide solution or a sodium hydrosulfide solution, with a concentration of 10-20 wt%; the addition amount of the sulfiding agent is based on the arsenic content in the wastewater, and 10-15 L of the sodium sulfide solution or the sodium hydrosulfide solution is added per 1 kg of arsenic; Before the sulfidation reaction, add acid to adjust the pH of the mixed wastewater to 0.5-1.0; control the pH to be 1.2-1.8 during the reaction, and the acid is sulfuric acid.

3. The processing method according to claim 1, characterized in that, In step (2): Before carrying out the oxidation treatment, it also includes adjusting the pH of the solution system obtained by mixing to 3.0-4.0; adjusting the pH value by adding liquid caustic soda or flake caustic soda with a mass concentration of 28%-32%; The fluoride ion precipitation treatment is to add calcium hydroxide or calcium oxide to the first filtrate, and the molar addition amount is 2.2-2.8 times the molar amount of the fluoride ion, and adjust the pH to 8.0-9.0 during the fluoride precipitation process.

4. The processing method according to claim 1, wherein In step (3): The alkaline condition is pH 10.0-12.0, and it is adjusted by adding liquid caustic soda or flake caustic soda with a mass concentration of 28%-32%; The calcium ion precipitation treatment is to add sodium carbonate to the second filtrate.

5. The processing method according to claim 1, characterized in that, Step (3) also includes: Detect the purified filtrate. If As≤0.3 mg / L, F≤20 mg / L, Tl≤0.015 mg / L, Ca≤200 mg / L, the treatment is up to standard; If it does not meet As≤0.3 mg / L, F≤20 mg / L, Tl≤0.015 mg / L, Ca≤200 mg / L, then cycle steps (2) and / or (3) for treatment.

6. The processing method according to claim 1, wherein It also includes step (4): Adjust the pH of the laundry water and the bath wastewater to 6.0-9.0, and successively carry out oxidation treatment, flocculation treatment and solid-liquid separation to obtain a third filtrate.

7. The processing method according to claim 6, wherein Detect the third filtrate: If As≤0.3 mg / L, F≤20 mg / L, Tl≤0.015 mg / L, Ca≤200 mg / L in the third filtrate, it is qualified; otherwise, return to step (2) to mix and treat with the first filtrate.

8. The processing method according to claim 1, wherein, It also includes step (5): Adjust the pH of the initial rainwater to 6.0-9.0, and successively carry out oxidation treatment, iron-based flocculation treatment, flocculation treatment and solid-liquid separation to obtain a fourth filtrate; If the thallium content in the initial rainwater > 0.015 mg / L, carry out thallium removal treatment and then flocculation treatment.

9. The processing method according to claim 8, characterized in that, Detect the fourth filtrate: If the pH is 7.0-9.0, As≤0.3 mg / L, F≤20 mg / L, Tl≤0.015 mg / L, Ca≤200 mg / L in the fourth filtrate, it is qualified; otherwise, cycle step (5) for treatment.

10. The processing method according to any one of claims 1 to 9, characterized in that, In steps (1)-(5): The oxidizing agent used in the oxidation treatment is potassium permanganate and / or potassium chlorate, and the addition amount is 1-5 g of oxidizing agent added to each liter of wastewater, and the reaction time is 2-4 h; The iron-based flocculant used in the iron-based flocculation treatment is ferric chloride and / or polyferric sulfate, and the addition amount is 3-10 g of iron-based flocculant added to each liter of wastewater, and the reaction time is 0.5-1 h; The flocculant used in the flocculation treatment or the secondary flocculation treatment is a PAM solution with a mass concentration of 0.5-1%, 1-2 ml of flocculant is added to each 1 L of wastewater, and the reaction time is 5-30 min; The thallium removal treatment is to add a thallium removal agent to the second filtrate or initial rainwater, and the addition amount is 0.1~0.5 kg of the thallium removal agent per m 3 of wastewater, and the reaction time is 20~120 min.

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