A method and system for purifying leachate from smelting slag

Abstract

The application discloses a smelting slag leachate purification treatment method and system, and belongs to the technical field of water treatment. The purification treatment method comprises the following steps: S1, using an aeration fan to perform aeration treatment on smelting slag leachate; S2, adjusting a pH value and performing precipitation treatment; S3, performing solid-liquid separation treatment by using a heavy metal separator; S4, removing sulfates; S5, capturing heavy metals; S6, performing solid-liquid separation treatment by using a coagulation, flocculation and high-efficiency cyclone water purifier; and S7, removing ammonia nitrogen. The smelting slag leachate is subjected to targeted purification treatment by using the purification treatment system in combination with the purification treatment method, so that a better purification treatment effect is achieved.

Description

Technical Field

[0001] This invention belongs to the field of water treatment technology and relates to a purification system and method for smelting slag leachate. Background Technology

[0002] Smelting slags such as water-quenched slag and desulfurized gypsum slag generated in the metal smelting industry are usually piled up in smelting slag dumps. Due to the leachate from smelting slag entering the groundwater, the quality of deep groundwater in the slag dumps is seriously substandard. Smelting slag leachate usually contains heavy metal pollutants such as sulfate, suspended solids, ammonia nitrogen, arsenic, cadmium, and copper. Among them, the sulfate content is high, exceeding the standard by more than 10 times. The leachate entering the groundwater causes water quality to exceed the standard, posing a significant threat to human health and the ecological environment. Therefore, it is necessary to purify the smelting slag leachate.

[0003] Currently, there is considerable research on the purification and treatment of pollutants such as incineration plant leachate and landfill leachate, typically employing methods such as anaerobic reactions, biochemical reactions, the Fenton process, and chemical synthesis. However, due to the differences in properties and pollutant characteristics among different types of leachate, the aforementioned treatment methods are not particularly effective for smelting slag leachate, resulting in unsatisfactory treatment outcomes.

[0004] Therefore, it is necessary to provide a method and system for purifying and treating smelting slag leachate to improve the purification and treatment effect of smelting slag leachate, thereby reducing or preventing smelting slag leachate containing pollutants from entering groundwater and causing water pollution. Summary of the Invention

[0005] In order to overcome the problems in the prior art, the present invention provides a more targeted purification treatment for smelting slag leachate, thereby improving the purification effect of smelting slag leachate.

[0006] To achieve the above objectives, the present invention is implemented through the following technical solution:

[0007] This invention proposes a purification system for smelting slag leachate. The system includes a comprehensive equalization tank 1, a primary mixing reaction tank 2, a heavy metal separator 3, a secondary mixing reaction tank 4, a tertiary mixing reaction tank 5, an intermediate tank 6, a high-efficiency cyclone purifier 7, and a quaternary mixing reaction tank 8. The comprehensive equalization tank 1 is used to hold the smelting slag leachate. The outlet of the comprehensive equalization tank 1 is connected to the inlet of the primary mixing reaction tank 2, and the outlet of the primary mixing reaction tank 2 is connected to the inlet of the heavy metal separator 3. The outlet of the heavy metal separator 3 is connected to the inlet of the secondary mixing reaction tank 4. The outlet of the secondary mixing reaction tank 4 is connected to the inlet of the tertiary mixing reaction tank 5. The outlet of the tertiary mixing reaction tank 5 is connected to the inlet of the intermediate tank 6. The outlet of the intermediate tank 6 is connected to the inlet of the high-efficiency cyclone water purifier 7. A pipe mixer 13 is installed on the pipe connecting the outlet of the intermediate tank 6 and the inlet of the high-efficiency cyclone water purifier 7. The supernatant outlet of the high-efficiency cyclone water purifier 7 is connected to the inlet of the quaternary mixing reaction tank 8.

[0008] Preferably, the smelting slag leachate contained in the integrated regulating tank 1 is pumped to the primary mixing reaction tank 2, and the intermediate tank 6 is pumped to the high-efficiency cyclone water purifier 7.

[0009] Preferably, the purification system further includes a sludge thickening tank 10 and a filter press 12. The sludge inlet of the sludge thickening tank 10 is connected to the sludge outlet of the heavy metal separator 3 and the sludge outlet of the high-efficiency cyclone purifier 7, respectively. The sludge from the heavy metal separator 3 and the high-efficiency cyclone purifier 7 is pumped to the sludge thickening tank 10. The sludge outlet of the sludge thickening tank 10 is connected to the sludge inlet of the filter press 12, and the sludge is pumped from the sludge thickening tank 10 to the filter press 12 via a sludge pump 11. The filtrate outlet of the filter press 12 is connected to the inlet of the integrated equalization tank 1. The filtrate from the filter press 12 flows into the integrated equalization tank 1 by gravity.

[0010] Another aspect of the present invention proposes a method for treating smelting slag leachate using the above-mentioned purification system, the smelting slag leachate purification method comprising the following steps:

[0011] S1: Use aeration blower 14 to aerate the smelting slag leachate contained in the comprehensive equalization tank 1.

[0012] S2: After the smelting slag leachate treated by aeration in step S1 enters the primary mixing reaction tank 2, a pH adjuster is first added to the primary mixing reaction tank 2 to adjust the pH to 10.7-11. Then, polyaluminum chloride solution and polyacrylamide solution are added to the primary mixing reaction tank 2. After the reaction, flocs are generated. The heavy metal ions and suspended solids in the smelting slag leachate react with the pH adjuster to generate precipitates.

[0013] S3: After the mixture in step S2 enters the heavy metal separator 3, the liquid in the heavy metal separator 3 is aerated, and the heavy metal separator 3 performs solid-liquid separation treatment on the mixture to obtain liquid and sludge.

[0014] S4: After the liquid obtained in step S3 enters the secondary mixing reaction tank 4, 98% sulfuric acid is first added to the secondary mixing reaction tank 4 to adjust the pH value of the liquid to neutral. Then, a sulfate removal agent is added to the secondary mixing reaction tank 4 to carry out the reaction.

[0015] S5: After the liquid reaction in step S4, it enters the three-stage mixing reaction tank 5, and a heavy metal scavenging agent is added to the liquid in the three-stage mixing reaction tank 5 to carry out the reaction;

[0016] S6: After the liquid reaction in step S5, it enters the intermediate tank 6. The liquid in the intermediate tank 6 is pumped to the high-efficiency cyclone water purifier 7. Flocculant and coagulant are added to the pipeline mixer 13. At the same time, the liquid in the high-efficiency cyclone water purifier 7 is aerated. The high-efficiency cyclone water purifier 7 performs solid-liquid separation treatment on the liquid to obtain clear liquid and sludge.

[0017] S7: The clear liquid obtained in step S6 enters the four-stage mixing reaction tank 8. Ammonia nitrogen removal agent is added to the four-stage mixing reaction tank 8 to react and the liquid in the four-stage mixing reaction tank 8 is aerated to complete the purification treatment of smelting slag leachate and obtain clean liquid.

[0018] Preferably, the method further includes sludge treatment, the sludge treatment method comprising the following steps:

[0019] (a) The sludge produced by the solid-liquid separation of the heavy metal separator 3 and the high-efficiency cyclone water purifier 7 is pumped to the sludge thickening tank 10.

[0020] (b) The sludge collected in the sludge thickening tank 10 is transported to the filter press 12 by the sludge pump 11 for filter pressing to obtain filtrate and sludge residue.

[0021] (c) The sludge residue from step (b) is stored in a centralized manner, and the filtrate obtained in step (b) is returned to the integrated equalization tank 1 and mixed with the smelting slag leachate.

[0022] Preferably, in step S2, the pH adjuster is a solution prepared from CaO and water with a concentration of 10%-20%, the polyaluminum chloride solution has a concentration of 5%-10%, 200-300 grams of polyaluminum chloride solution are added per ton of wastewater, and the polyacrylamide solution has a concentration of 1‰-3‰, 10-15 grams of polyacrylamide solution are added per ton of wastewater.

[0023] Preferably, in step S4, the sulfate removal agent is a BaCl2 solution with a concentration of 10%, and 200-300 grams of BaCl2 solution are added per ton of wastewater.

[0024] Preferably, in step S5, the heavy metal capturing agent is a dithiocarbamate solution with a concentration of 30%-40%, and 50 grams of dithiocarbamate solution are added per ton of wastewater.

[0025] Preferably, in step S6, the coagulant is a polyaluminum chloride solution and the flocculant is a polyacrylamide solution. The concentration of the polyaluminum chloride solution is 5%-10%, and 100-150 grams of polyaluminum chloride solution are added per ton of wastewater. The concentration of the polyacrylamide solution is 1‰-3‰, and 5-7.5 grams of polyacrylamide solution are added per ton of wastewater.

[0026] Preferably, in step S7, the ammonia nitrogen removal agent is a trichloroisocyanuric acid solution with a concentration of 10%, and 500-600 grams of trichloroisocyanuric acid solution are added per ton of wastewater.

[0027] The beneficial effects of this invention are:

[0028] 1. This invention improves the purification effect of smelting slag leachate by targeted purification treatment, effectively reduces or removes pollutants in smelting slag leachate, and reduces the risk of smelting slag leachate entering groundwater and causing water pollution.

[0029] 2. This invention utilizes aeration during the treatment of smelting slag leachate to agitate the leachate, causing it to churn and mix more evenly. This increases the probability of contact between reagents and contaminants, promoting the reaction. Simultaneously, it prevents solid matter from settling, keeping it in suspension and avoiding the accumulation of solid matter in the equipment, which would make cleaning difficult and affect the effective volume of the equipment.

[0030] 3. This invention recycles and treats the sludge generated during the purification process of smelting slag leachate, thus avoiding secondary pollution from the sludge.

[0031] 4. After treating the leachate from smelting slag, the present invention can obtain a clean liquid, namely water, which can be recycled and reused, thus helping to save water resources and realize waste reuse. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of the purification system structure of the present invention;

[0033] Figure 2 This is a flowchart of the purification treatment method of the present invention.

[0034] In the diagram, 1-Comprehensive equalization tank, 2-Primary mixing reaction tank, 3-Heavy metal separator, 4-Secondary mixing reaction tank, 5-Tertiary mixing reaction tank, 6-Intermediate tank, 7-High-efficiency cyclone water purifier, 8-Fourth-stage mixing reaction tank, 9-Clear water tank, 10-Sludge thickening tank, 11-Sludge pump, 12-Filter press, 13-Pipeline mixer, 14-Aeration blower. Detailed Implementation

[0035] The present invention will be further described in detail below with reference to specific embodiments.

[0036] Unless otherwise specified, all chemical reagents used in the embodiments of this invention are commercially available analytical grade reagents.

[0037] Example 1

[0038] This embodiment uses smelting slag leachate from an actual smelting slag stockpile for experimentation. First, the smelting slag leachate is added to a comprehensive equalization tank 1, and an aeration blower is used to aerate the leachate in the tank. Then, based on the liquid level of the leachate in the comprehensive equalization tank 1, when a threshold is reached, the primary booster pump is activated to pump the leachate from the comprehensive equalization tank 1 to a primary mixing reaction tank 2. A 10% CaO solution is first added to the primary mixing reaction tank 2, and mixed with the raw water through stirring to adjust the pH. Simultaneously, the pH of the primary mixing reaction tank is monitored in real time. When the pH value of the smelting slag leachate in mixing reaction tank 2 reaches the range of 10.7–11, the addition of CaO solution is stopped. Then, 300g of 5% polyaluminum chloride (PAC) solution and 15g of 1‰ polyacrylamide (PAM) solution are added per ton of wastewater. After the raw water is thoroughly mixed with the reagents through stirring, good flocs are formed. Heavy metal ions and suspended solids in the smelting slag leachate react with the precipitating agents to form precipitates. The liquid, suspended solids, and precipitates in the primary mixing reaction tank 2 flow by gravity at a high level. The liquid enters the heavy metal separator 3, where it undergoes solid-liquid separation. The resulting liquid flows into the secondary mixing reaction tank 4, while the sludge is pumped to the sludge thickening tank 10. Sulfuric acid is first added to the secondary mixing reaction tank 4, while the pH value of the liquid in the tank is monitored in real time. When the pH reaches neutral, a 10% BaCl2 solution is added to the secondary mixing reaction tank 4 at a rate of 200g BaCl2 per ton of wastewater. The BaCl2 reacts with sulfate ions to form barium sulfate precipitate. As the wastewater in the secondary mixing reaction tank 4... As the liquid volume increases, the liquid and sediment continue to flow into the tertiary mixing tank 5 through the connecting channel between the secondary mixing tank 4 and the tertiary mixing tank 5. A 30% dithiocarbamate solution is added to the tertiary mixing tank 5 at a rate of 50g per ton of wastewater. After the reaction in the tertiary mixing tank 5, the liquid continues to flow into the intermediate tank 6. The liquid in the intermediate tank 6 is then pumped to the high-efficiency cyclone purifier 7. During the transportation process, 100g of dithiocarbamate solution is added per ton of wastewater. A 10% PAC solution is added to the pipeline mixer 13, and a 3‰ PAM solution is added to the pipeline mixer 13 at a rate of 5g per ton of wastewater. The liquid undergoes multi-stage purification of the wastewater in the high-efficiency cyclone purifier 7, and after solid-liquid separation, sludge and clear liquid are produced. The clear liquid continues to flow into the fourth-stage mixing reaction tank 8, and the sludge is transported to the sludge thickening tank 10. A 10% trichloroisocyanuric acid solution is added to the fourth-stage mixing reaction tank 8 at a rate of 500g per ton of wastewater. After the liquid reacts in the fourth-stage mixing reaction tank 8, it flows into the clear water tank 9.

[0039] The sludge produced in the heavy metal separator 3 and the high-efficiency cyclone purifier 7 is transported to the sludge thickening tank 10. The sludge is then pumped from the sludge thickening tank 10 to the filter press 12 by the sludge pump 11. The filter press 12 filters the sludge, and the resulting filtrate is transported to the integrated equalization tank 1. The resulting sludge residue is collected and stored in a unified manner.

[0040] In this embodiment, the pollutant content in the smelting slag leachate contained in the comprehensive regulating tank 1 and the pollutant content in the clear liquid in the clear water tank 9 were detected and the results were obtained. In this embodiment, the pollutant removal rate in the smelting slag leachate reached 90%.

[0041] Example 2

[0042] This embodiment uses smelting slag leachate from an actual smelting slag stockpile for experimentation. First, the smelting slag leachate is added to a comprehensive equalization tank 1, and an aeration blower is used to aerate it. Then, based on the liquid level of the smelting slag leachate in the comprehensive equalization tank 1, when a threshold is reached, the primary booster pump is activated to pump the smelting slag leachate from the comprehensive equalization tank 1 to a primary mixing reaction tank 2. A 20% CaO solution is first added to the primary mixing reaction tank 2 and mixed with the raw water through stirring to adjust the pH. Simultaneously, the pH value of the smelting slag leachate in the primary mixing reaction tank 2 is monitored in real time. When the pH value reaches the range of 10.7–11, the addition of CaO solution is stopped, and then 200g of CaO solution is added per ton of wastewater. A 10% polyaluminum chloride (PAC) solution and a 3‰ polyacrylamide (PAM) solution (10g per ton of wastewater) are added. After the raw water is thoroughly mixed with the reagents by stirring, good flocs are formed. Heavy metal ions and suspended solids in the smelting slag leachate react with the precipitating agent to form precipitates. The liquid, suspended solids, and precipitates in the primary mixing reaction tank 2 flow by gravity into the heavy metal separator 3. The heavy metal separator 3 performs solid-liquid separation treatment on the liquid, and the resulting liquid flows into the secondary mixing reaction tank 4. The resulting sludge is pumped to the sludge thickening tank 10. Sulfuric acid is first added to the secondary mixing reaction tank 4, and the pH value of the liquid in the secondary mixing reaction tank 4 is monitored in real time. When the pH value reaches neutral, 300g of sulfuric acid is added per ton of wastewater. A 10% BaCl2 solution is added to the secondary mixing reaction tank 4. BaCl2 reacts with sulfate ions to form barium sulfate precipitate. As the liquid level in the secondary mixing reaction tank 4 increases, the liquid and precipitate continue to flow into the tertiary mixing reaction tank 5 through the connecting channel between the secondary and tertiary mixing reaction tanks. A 40% dithiocarbamate solution is added to the tertiary mixing reaction tank 5 at a rate of 50g per ton of wastewater. After the reaction in the tertiary mixing reaction tank 5, the liquid continues to flow into the intermediate tank 6. The liquid in the intermediate tank 6 is then pumped to the high-efficiency cyclone purifier 7. During the pumping process, 150g of dithiocarbamate solution is added per ton of wastewater. A 5% PAC solution is added to the pipeline mixer 13, and a 1‰ PAM solution is added to the pipeline mixer 13 at a rate of 7.5g per ton of wastewater. The liquid undergoes multi-stage purification of the wastewater in the high-efficiency cyclone purifier 7, and after solid-liquid separation, sludge and clear liquid are produced. The clear liquid continues to flow into the fourth-stage mixing reaction tank 8, and the sludge is transported to the sludge thickening tank 10. A 10% trichloroisocyanuric acid solution is added to the fourth-stage mixing reaction tank 8 at a rate of 600g per ton of wastewater. After the liquid reacts in the fourth-stage mixing reaction tank 8, it flows into the clear water tank 9.

[0043] The sludge produced in the heavy metal separator 3 and the high-efficiency cyclone purifier 7 is transported to the sludge thickening tank 10. The sludge is then pumped from the sludge thickening tank 10 to the filter press 12 by the sludge pump 11. The filter press 12 filters the sludge, and the resulting filtrate is transported to the integrated equalization tank 1. The resulting sludge residue is collected and stored in a unified manner.

[0044] In this embodiment, the pollutant content in the smelting slag leachate contained in the comprehensive regulating tank 1 and the pollutant content in the clear liquid in the clear water tank 9 were detected and the results were obtained. In this embodiment, the pollutant removal rate in the smelting slag leachate reached 91%.

[0045] Example 3

[0046] This embodiment uses smelting slag leachate from an actual smelting slag stockpile for experimentation. First, the smelting slag leachate is added to a comprehensive equalization tank 1, and an aeration blower is used to aerate the leachate. Then, based on the liquid level of the leachate in the comprehensive equalization tank 1, when a threshold is reached, the primary booster pump is activated to pump the leachate from the comprehensive equalization tank 1 to a primary mixing reaction tank 2. A 15% CaO solution is first added to the primary mixing reaction tank 2, and mixed with the raw water through stirring to adjust the pH. Simultaneously, the pH of the primary mixing reaction tank is monitored in real time. When the pH value of the smelting slag leachate in mixing reaction tank 2 reaches the range of 10.7-11, the addition of CaO solution is stopped. Then, 250g of 7% polyaluminum chloride (PAC) solution and 13g of 2‰ polyacrylamide (PAM) solution are added per ton of wastewater. After the raw water is thoroughly mixed with the reagents through stirring, good flocs are formed. Heavy metal ions and suspended solids in the smelting slag leachate react with the precipitating agents to form precipitates. The liquid, suspended solids, and precipitates in the primary mixing reaction tank 2 flow by gravity at a high level. The liquid enters the heavy metal separator 3, where it undergoes solid-liquid separation. The resulting liquid flows into the secondary mixing reaction tank 4, while the sludge is pumped to the sludge thickening tank 10. Sulfuric acid is first added to the secondary mixing reaction tank 4, while the pH value of the liquid in the tank is monitored in real time. When the pH reaches neutral, a 10% BaCl2 solution is added to the secondary mixing reaction tank 4 at a rate of 250g BaCl2 per ton of wastewater. BaCl2 reacts with sulfate ions to form barium sulfate precipitate. As the wastewater in the secondary mixing reaction tank 4... As the liquid volume increases, the liquid and sediment continue to flow into the tertiary mixing tank 5 through the connecting channel between the secondary mixing tank 4 and the tertiary mixing tank 5. A 35% dithiocarbamate solution is added to the tertiary mixing tank 5 at a rate of 50g per ton of wastewater. After the reaction in the tertiary mixing tank 5, the liquid continues to flow into the intermediate tank 6. The liquid in the intermediate tank 6 is then pumped to the high-efficiency cyclone purifier 7. During the transportation process, 125g of dithiocarbamate solution is added per ton of wastewater. A 7% PAC solution is added to the pipeline mixer 13, and a 2‰ PAM solution is added to the pipeline mixer 13 at a rate of 6g per ton of wastewater. The liquid undergoes multi-stage purification of the wastewater in the high-efficiency cyclone purifier 7, and after solid-liquid separation, sludge and clear liquid are produced. The clear liquid continues to flow into the fourth-stage mixing reaction tank 8, and the sludge is transported to the sludge thickening tank 10. A 10% trichloroisocyanuric acid solution is added to the fourth-stage mixing reaction tank 8 at a rate of 550g per ton of wastewater. After the liquid reacts in the fourth-stage mixing reaction tank 8, it flows into the clear water tank 9.

[0047] The sludge produced in the heavy metal separator 3 and the high-efficiency cyclone purifier 7 is transported to the sludge thickening tank 10. The sludge is then pumped from the sludge thickening tank 10 to the filter press 12 by the sludge pump 11. The filter press 12 filters the sludge, and the resulting filtrate is transported to the integrated equalization tank 1. The resulting sludge residue is collected and stored in a unified manner.

[0048] In this embodiment, the pollutant content in the smelting slag leachate contained in the comprehensive regulating tank 1 and the pollutant content in the clear liquid in the clear water tank 9 were detected and the results were obtained. In this embodiment, the pollutant removal rate in the smelting slag leachate reached 90%.

[0049] In summary, using the purification system and method of this invention to purify smelting slag leachate can effectively remove pollutants from the smelting slag leachate and obtain a clean liquid for normal use. The purification method of this invention is highly targeted and has a significant effect on the purification of smelting slag leachate.

[0050] Finally, it should be noted that the above preferred embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit it. Although the present invention has been described in detail through the above preferred embodiments, those skilled in the art should understand that various changes can be made to it in form and detail without departing from the scope defined by the claims of the present invention.

Claims

1. A method for purifying and treating leachate from smelting slag, characterized in that: The smelting slag leachate is purified using a purification system. The purification system includes a comprehensive regulating tank (1), a primary mixing reaction tank (2), a heavy metal separator (3), a secondary mixing reaction tank (4), a tertiary mixing reaction tank (5), an intermediate tank (6), a high-efficiency cyclone purifier (7), and a quaternary mixing reaction tank (8). The comprehensive regulating tank (1) is used to hold the smelting slag leachate. The outlet of the comprehensive regulating tank (1) is connected to the inlet of the primary mixing reaction tank (2). The outlet of the primary mixing reaction tank (2) is connected to the inlet of the heavy metal separator (3). The outlet of the heavy metal separator (3) is connected to the inlet of the secondary mixing reaction tank (4), the outlet of the secondary mixing reaction tank (4) is connected to the inlet of the tertiary mixing reaction tank (5), the outlet of the tertiary mixing reaction tank (5) is connected to the inlet of the intermediate tank (6), the outlet of the intermediate tank (6) is connected to the inlet of the high-efficiency cyclone purifier (7), and a pipe mixer (13) is installed on the pipe connecting the outlet of the intermediate tank (6) and the inlet of the high-efficiency cyclone purifier (7). The supernatant outlet of the high-efficiency cyclone purifier (7) is connected to the inlet of the quaternary mixing reaction tank (8). The method for purifying and treating smelting slag leachate includes the following steps: S1: Use an aeration blower (14) to aerate the smelting slag leachate contained in the integrated regulating tank (1); S2: After the smelting slag leachate after aeration treatment in step S1 enters the primary mixing reaction tank (2), a pH adjuster is first added to the primary mixing reaction tank (2) to adjust the pH to 10.7-11. Then, polyaluminum chloride solution and polyacrylamide solution are added to the primary mixing reaction tank (2). After the reaction, flocs are generated. The heavy metal ions and suspended solids in the smelting slag leachate react with the pH adjuster to generate precipitates. S3: After the mixture in step S2 enters the heavy metal separator (3), the liquid in the heavy metal separator (3) is aerated and the heavy metal separator (3) performs solid-liquid separation to obtain liquid and sludge. S4: After the liquid obtained in step S3 enters the secondary mixing reaction tank (4), sulfuric acid with a concentration of 98% is first added to the secondary mixing reaction tank (4) to adjust the pH value of the liquid to neutral, and then sulfate removal agent is added to the secondary mixing reaction tank (4) for reaction. In step S4, the sulfate removal agent is BaCl2 solution with a concentration of 10%, and 200-300 grams of BaCl2 solution are added per ton of wastewater. S5: After the liquid reaction in step S4, it enters the three-stage mixing reaction tank (5), and a heavy metal scavenging agent is added to the liquid in the three-stage mixing reaction tank (5) to carry out the reaction; S6: After the liquid reaction in step S5, it enters the intermediate tank (6). The liquid in the intermediate tank (6) is pumped to the high-efficiency cyclone purifier (7). Flocculant and coagulant are added to the pipeline mixer (13). At the same time, the liquid in the high-efficiency cyclone purifier (7) is aerated. The high-efficiency cyclone purifier (7) performs solid-liquid separation treatment on the liquid to obtain clear liquid and sludge. S7: The clear liquid obtained in step S6 enters the four-stage mixing reaction tank (8), and an ammonia nitrogen removal agent is added to the four-stage mixing reaction tank (8) to react and the liquid in the four-stage mixing reaction tank (8) is aerated to complete the purification treatment of smelting slag leachate and obtain clean liquid.

2. The method for purifying and treating smelting slag leachate according to claim 1, characterized in that: The smelting slag leachate contained in the integrated regulating tank (1) is pumped to the primary mixing reaction tank (2), and the intermediate tank (6) pumps the liquid to the high-efficiency cyclone water purifier (7).

3. A method for purifying and treating smelting slag leachate according to claim 1 or 2, characterized in that: The purification system also includes a sludge thickening tank (10) and a filter press (12). The sludge inlet of the sludge thickening tank (10) is connected to the sludge outlet of the heavy metal separator (3) and the sludge outlet of the high-efficiency cyclone water purifier (7). The sludge in the heavy metal separator (3) and the high-efficiency cyclone water purifier (7) is pumped to the sludge thickening tank (10). The sludge outlet of the sludge thickening tank (10) is connected to the sludge inlet of the filter press (12). The sludge is pumped from the sludge thickening tank (10) to the filter press (12) by the sludge pump (11). The filtrate outlet of the filter press (12) is connected to the inlet of the integrated regulating tank (1).

4. The method for purifying and treating smelting slag leachate according to claim 1, characterized in that: The method also includes sludge treatment, the sludge treatment method comprising the following steps: (a) The sludge generated by the solid-liquid separation of the heavy metal separator (3) and the high-efficiency cyclone purifier (7) is pumped to the sludge thickening tank (10); (b) The sludge collected in the sludge thickening tank (10) is transported to the filter press (12) by the sludge pump (11) for filter pressing to obtain filtrate and sludge residue; (c) The sludge residue from step (b) is stored in a centralized manner, and the filtrate obtained in step (b) is returned to the integrated regulating tank (1) and mixed with the smelting slag leachate.

5. The method for purifying and treating smelting slag leachate according to claim 1, characterized in that: In step S2, the pH adjuster is a solution prepared from CaO and water with a concentration of 10%-20%, the polyaluminum chloride solution has a concentration of 5%-10%, and 200-300 grams of polyaluminum chloride solution are added per ton of wastewater. The polyacrylamide solution has a concentration of 1‰-3‰, and 10-15 grams of polyacrylamide solution are added per ton of wastewater.

6. The method for purifying and treating smelting slag leachate according to claim 1, characterized in that: In step S5, the heavy metal capturing agent is a dithiocarbamate solution with a concentration of 30%-40%, and 50 grams of dithiocarbamate solution are added per ton of wastewater.

7. The method for purifying and treating smelting slag leachate according to claim 1, characterized in that: In step S6, the coagulant is a polyaluminum chloride solution and the flocculant is a polyacrylamide solution. The concentration of the polyaluminum chloride solution is 5%-10%, and 100-150 grams of polyaluminum chloride solution are added per ton of wastewater. The concentration of the polyacrylamide solution is 1‰-3‰, and 5-7.5 grams of polyacrylamide solution are added per ton of wastewater.

8. The method for purifying and treating smelting slag leachate according to claim 1, characterized in that: In step S7, the ammonia nitrogen removal agent is a trichloroisocyanuric acid solution with a concentration of 10%, and 500-600 grams of trichloroisocyanuric acid solution are added per ton of wastewater.

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