A treatment system and method for reducing and solidifying the leachate of electrolytic aluminum slag and recycling its resources

Abstract

The present invention relates to a treatment system and method for reducing and solidifying the resource recycling of electrolytic aluminum slag leachate. The treatment system of the present invention mainly comprises: a pre-precipitation tank (1), a regulating tank (2), an aluminum hydroxide reaction precipitation tank (3), a primary defluorination coagulation precipitation tank (4), a precision filter 1 (5), an activated aluminum oxide precision defluorination device (6), a two-stage oxidation cyanide breaking reaction tank (7), an oxidation arsenic removal reaction tank (8), a precision filter 2 (9), an ultrafiltration membrane clarification device (10), a resin weight removal device (11), a membrane concentration system (12), a deammonification tower (13), and an evaporation concentration crystallization device (14). The treatment method of the present invention can effectively realize resource recycling, convert ammonia nitrogen into ammonia water resources, and prevent arsenide, fluoride and chloride salt from leaving the factory, thereby reducing the amount of solid waste generated, avoiding the problem of hazardous waste management and transportation, and having lower operating costs. The economic benefits and comprehensive operating costs of aluminum and ammonia nitrogen generated are much lower than those of traditional processes, truly "making pollution control effective and profitable".

Description

Technical Field

[0001] The present invention relates to the field of resource recovery and treatment of aluminum slag and aluminum ash leachate in the electrolytic aluminum industry, and in particular to a treatment system and method for reducing and solidifying the electrolytic aluminum slag leachate for resource recovery. Background Art

[0002] Since the beginning of the 21st century, my country's electrolytic aluminum industry has developed rapidly. In 2017, my country's electrolytic aluminum output reached 32.27 million tons, and its production capacity has exceeded 40 million tons, ranking first in the world for many consecutive years, accounting for 57% of the world's total output. At the same time, the environmental pollution problems caused by the development of the electrolytic aluminum industry have also received great attention from the country, the industry and society.

[0003] The production process of electrolytic aluminum will produce hazardous solid waste - overhaul slag. On average, 20 to 30 kilograms of overhaul slag will be produced for every ton of electrolytic aluminum produced. The overhaul slag produced by the overhaul of each aluminum electrolytic cell weighs about 100 tons. According to the annual plan of 100 cells, the annual solid waste generated is about 10,000 tons. Among the overhaul slag, carbonaceous materials account for about 37%, fluoride salts account for about 30%, and other substances are mainly carbonaceous materials β-alumina, nepheline, mullite, sodium aluminum oxide, a small amount of aluminum carbide, aluminum nitride, aluminum-iron alloy and trace amounts of cyanide.

[0004] It is known that the electrolytic aluminum slag leachate usually contains 300-1000mg / L of fluorine, 1-10mg / L of arsenic, 10-50mg / L of cyanide, 100-500mg / L of suspended solids, 2000-3000mg / L of aluminum, 500-1200mg / L of ammonia nitrogen, 300-1000mg / L of COD, 12-13 of pH value, and 3.5-4.0% of total salt, among which aluminum and ammonia nitrogen have relatively high recycling value. The leachate contains highly toxic soluble fluoride and cyanide. If not properly handled, they will mix with rainwater into rivers and seep into the ground, thereby polluting surface water, groundwater and soil, causing great harm to the surrounding ecological environment, public health and the growth of plants and animals.

[0005] At present, the existing methods for treating waste tank linings are mainly divided into two types: pyrolysis and wet treatment. Among them, pyrolysis treatment technology has good harmless treatment effect and large treatment capacity, but it still has defects such as high energy consumption, improper tail gas treatment, and easy to cause secondary pollution. Wet treatment technology has a simple process flow, strong operability and low operating cost, but due to the influence of the existing actual treatment effect and treatment cost, there are not many real practical applications, and most of them still build special yards for stacking.

[0006] To achieve harmonious development of the electrolytic aluminum industry, it is not only necessary to harmlessly treat the slag from the overhaul of aluminum electrolytic cells, but more importantly, it is necessary to turn the slag from the overhaul of aluminum electrolytic cells into treasure and extract the useful components for recycling and reuse.

[0007] And with the improvement of environmental protection requirements, it is difficult to achieve wastewater discharge standards and zero discharge is required. Therefore, a wastewater reduction and solidification resource reuse treatment system and method are proposed to recycle water, aluminum, ammonia nitrogen and salt solidification and drying, reduce the pollution caused by wastewater to the environment, reduce resource waste, and reduce corporate governance costs. It has important social and economic significance. Summary of the invention

[0008] The purpose of the present invention is to overcome the above-mentioned shortcomings and provide a treatment system and method for reducing and solidifying the resource recycling of electrolytic aluminum slag leachate. The system and method can effectively realize resource recycling, reduce the amount of solid waste generated, transform ammonia nitrogen into ammonia water for resource utilization, and prevent arsenide, fluoride and chloride salt from leaving the factory, thus avoiding the problem of hazardous waste management and transportation.

[0009] The objective of the present invention is achieved through the following technical solutions:

[0010] The first aspect of the present invention provides a treatment system for reducing and solidifying the leachate of electrolytic aluminum slag for resource reuse, which comprises a pre-precipitation tank, a regulating tank, an aluminum hydroxide reaction precipitation tank, a primary defluorination coagulation precipitation tank, a precision filter 1, an activated alumina precision defluorination device, a two-stage oxidation cyanide breaking reaction tank, a chemical oxidation arsenic removal reaction tank, a precision filter 2, an ultrafiltration membrane clarification device, a resin weight removal device, a membrane concentration system, a deammoniation tower, and an evaporation concentration crystallization device connected in sequence;

[0011] The aluminum hydroxide reaction sedimentation tank, the primary fluoride removal coagulation sedimentation tank, and the chemical oxidation arsenic removal reaction tank are respectively connected to high-pressure sludge dewatering devices, among which the primary fluoride removal coagulation sedimentation tank and the chemical oxidation arsenic removal reaction tank share the same high-pressure sludge dewatering device, the aluminum hydroxide reaction sedimentation tank is connected to another high-pressure sludge dewatering device, and the sludge dewatering device connected to the aluminum hydroxide reaction sedimentation tank is connected to the aluminum hydroxide workshop.

[0012] Furthermore, the aluminum hydroxide reaction sedimentation tank is connected to a hydrochloric acid pump for pumping in hydrochloric acid for neutralization and hydrolysis, and the primary defluorination coagulation sedimentation tank is connected to a calcium chloride and aluminum sulfate solution mixing pump for pumping in a mixture of calcium chloride and aluminum sulfate solution for reaction with fluorine.

[0013] Furthermore, the precision filter 1, the precision filter 2, and the ultrafiltration membrane clarification device are respectively provided with a backwash pump;

[0014] Furthermore, the pre-sedimentation tank, aluminum hydroxide reaction sedimentation tank, and primary fluoride removal coagulation sedimentation tank all adopt two-stage inclined tube sedimentation tanks; the two-stage inclined tube sedimentation tank includes a primary sedimentation tank and a secondary sedimentation tank, the primary sedimentation tank is provided with a first liquid inlet and a first overflow port, the secondary sedimentation tank is provided with a second liquid inlet and a second overflow port, the primary sedimentation tank and the secondary sedimentation tank are connected through the first overflow port and the second liquid inlet, and the primary sedimentation tank and the secondary sedimentation tank are respectively provided with inclined tubes.

[0015] The liquid inlet end of the two-stage inclined tube sedimentation tank corresponding to the primary defluorination coagulation sedimentation tank is also provided with a primary defluorination device, and the primary defluorination device comprises a primary dosing mixing zone and a primary oxidation reaction zone which are connected in sequence.

[0016] The two-stage oxidation cyanide destruction reaction pool comprises a drug adding mixing zone, a primary oxidation reaction zone and a secondary oxidation reaction zone which are connected in sequence, wherein stirring devices are arranged in the primary oxidation reaction zone and the secondary oxidation reaction zone.

[0017] At the same time, the second aspect of the present invention provides a method for treating the reduction and solidification of electrolytic aluminum slag leachate for resource reuse, which uses the treatment system for treating the reduction and solidification of electrolytic aluminum slag leachate for resource reuse described in the first aspect, and comprises the following steps:

[0018] 1) The leachate from the electrolytic aluminum slag is sent to the pre-sedimentation tank for precipitation, and the precipitated sludge is extracted and dehydrated from the V-shaped funnel at the bottom of the device. The residence time is 0.5-1.0 hours, and the obtained supernatant is sent to the regulating tank to achieve precipitation of solid particles, silt and other substances and clarification of wastewater;

[0019] 2) The supernatant after pre-precipitation is stirred in the regulating tank to reduce the fluctuation of its water quality parameters, and then overflows into the aluminum hydroxide reaction precipitation tank after staying for 1-2 hours;

[0020] 3) The overflow liquid of the regulating tank reacts with hydrochloric acid in the aluminum hydroxide reaction sedimentation tank, the reaction time is 10-30min, the reaction pH is controlled to be in the range of 7-8, the reaction molar ratio is: hydrochloric acid: aluminum>3:1, the suspended matter produced by the reaction is precipitated in the sedimentation tank of the aluminum hydroxide reaction sedimentation tank, the suspended matter settles to the V-type funnel, the sedimentation time is 0.5-2h, and the obtained supernatant overflows from the top overflow port;

[0021] 4) The supernatant overflowing from the aluminum hydroxide reaction sedimentation tank is mixed with calcium chloride and aluminum sulfate solution and pumped into the primary defluorination coagulation sedimentation tank by a pump, the reaction molar ratio is: calcium chloride: aluminum sulfate: fluorine> 1:2.5:1, the reaction time is 10-30min, the reaction pH is 8-9, the liquid after the reaction enters the sedimentation tank of the primary defluorination coagulation sedimentation tank for precipitation, and the suspended matter containing calcium fluoride and aluminum hydroxide colloid generated by the reaction is partially settled in the two-stage inclined tube sedimentation tank of the primary defluorination coagulation sedimentation tank to the V-funnel, the sedimentation time is 0.5-2h, and the supernatant obtained after precipitation flows out from the top overflow port;

[0022] 5) Since the primary defluorination sedimentation effect is poor, the suspended matter content is generally 10-100 mg / L, so the overflow liquid of the primary defluorination coagulation sedimentation tank is pumped into the precision filter 1 for filtration by a pump, and the filtrate with suspended matter <1 mg / L is obtained after filtration;

[0023] 6) The filtrate after passing through the precision filter 1 is pumped into the activated alumina precision defluorination device for activated alumina adsorption defluorination, and after adsorption defluorination, wastewater with a fluorine content of 2-4 mg / L is obtained;

[0024] 7) The wastewater after adsorption and defluorination is pumped into a two-stage oxidation cyanide breaking reaction pool for primary oxidation cyanide breaking and secondary oxidation cyanide breaking. The primary oxidation cyanide breaking is adjusted to pH=10, and the molar ratio of the primary oxidation cyanide breaking reaction is: sodium hypochlorite: cyanide=10:1. After the primary oxidation cyanide breaking, it is connected to the secondary oxidation cyanide breaking reaction pool through the top overflow. The secondary oxidation cyanide breaking is adjusted to pH=8, and the reaction molar ratio is: sodium hypochlorite: cyanide>2:1. After the two-stage oxidation cyanide breaking reaction time is 30 minutes, a liquid with cyanide reduced to 0.5 mg / L is obtained;

[0025] 8) The liquid after cyanide removal is sent to a chemical oxidation arsenic removal reaction tank to add ferric chloride, and mixed to react to form a ferric arsenate suspension with extremely low solubility. The reaction molar ratio is: ferric chloride: arsenide> 1.5:1, the reaction time is 10-30 minutes, and the arsenide is reduced to 0.1 mg / L after chemical oxidation arsenic removal;

[0026] 9) filtering the liquid containing suspended matter obtained after arsenic removal through a second precision filter to obtain a filtrate with suspended matter less than 1 mg / L;

[0027] 10) The filtrate obtained by filtering the precision filter 2 is sent to an ultrafiltration membrane clarification device, the membrane pore size of the ultrafiltration membrane clarification device is 100,000-200,000 Daltons, the operating pressure is 0.1-0.3Mpa, and the operating temperature is 5-45°C, and the ultrafiltration filtrate is obtained after filtration;

[0028] 11) Pumping the ultrafiltration filtrate into a resin deweighting device for deep adsorption of calcium, magnesium, aluminum and iron, and obtaining deweighted water with an ion concentration of <2 mg / L after adsorption;

[0029] 12) Pumping the deweighted water into a membrane concentration system to concentrate and reduce the salt, first pumping it into a high-pressure reverse osmosis membrane system, and then entering a low-pressure reverse osmosis membrane system, concentrating the salt to a concentration of 9-10%, and the ammonia nitrogen to 2000 mg / L, recycling the water, producing water to 50-100 us / cm, and filtering a large amount of COD at the same time to ensure that the COD content does not exceed the standard, the operating pressure of the high-pressure reverse osmosis membrane system is 8-12 MPa, the operating pressure of the low-pressure reverse osmosis membrane system is 1.5-2.5 MPa, the temperature is 25-35° C., and the pH is 6.5-7.0. After membrane concentration, a membrane concentrated concentrate is obtained;

[0030] 13) The concentrated solution after membrane concentration enters the deammoniation tower device for ammonia nitrogen recovery. Liquid alkali is added to react with ammonium in the solution to produce ammonia, which is then volatilized to the top of the tower through steam heat transfer and overflowed. The overflowing ammonia gas is then condensed into ammonia water through a condensation device. The recovered ammonia water can reach a concentration of 15-20%, while the ammonia at the bottom of the kettle becomes less and less. Finally, the ammonia nitrogen evaporates to 15 mg / L and is discharged from the bottom of the kettle;

[0031] 14) The mother liquor at the bottom of the deamination tower is pumped into an evaporation, concentration and crystallization device by a pump, and the evaporation obtains qualified water and concentrated and solidified wet salt;

[0032] 15) The sludge obtained by precipitation at the bottom of the primary fluoride removal coagulation sedimentation tank and the chemical oxidation arsenic removal reaction tank is discharged into the same high-pressure sludge dehydration device for dehydration, and the sludge precipitated at the bottom of the aluminum hydroxide reaction sedimentation tank is discharged into another high-pressure sludge dehydration device for dehydration. After dehydration of the sludge at the bottom of the aluminum hydroxide reaction sedimentation tank, aluminum hydroxide with a water content greater than 40% is obtained, and the aluminum hydroxide with a water content greater than 40% is sent to the aluminum hydroxide workshop.

[0033] Preferably, the high-pressure sludge dewatering device uses a high-pressure plate and frame filter press, which can reduce the water content to 40-55%, the operating pressure is 2-5Mpa, and the operating time is 2-4h;

[0034] Furthermore, when the activated alumina adsorption reaches the saturation concentration, a 3-4% aluminum sulfate solution is used to regenerate the activated alumina defluoridation agent, and the regenerated waste liquid is returned to the reaction zone of the aluminum hydroxide reaction precipitation tank to recover aluminum;

[0035] Preferably, the activated alumina is r-alumina;

[0036] Compared with the existing technology, this scheme neutralizes and hydrolyzes the supernatant in the regulating tank with hydrochloric acid, and at the same time returns the above-mentioned regenerated waste liquid to the aluminum hydroxide reaction precipitation tank to continue to react with hydrochloric acid, and then dehydrates the aluminum hydroxide precipitate into sludge and sends it to the aluminum hydroxide workshop, thereby achieving the purpose of aluminum resource recovery of the aluminum in the electrolytic slag leachate and the aluminum in the reagent aluminum sulfate, and effectively achieving the beneficial effects of resource reuse and reduction of solid waste generation.

[0037] Furthermore, the filter elements of precision filter 1 and precision filter 2 are made of titanium-aluminum intermetallic compounds with a precision of 0.1-0.5um, which teach traditional filters the characteristics of large filtration flux, strong corrosion resistance, high filtration accuracy and long service life;

[0038] Furthermore, the precision filter 1 filters out the calcium fluoride and aluminum hydroxide colloidal suspended solids in the supernatant of the primary defluorination sedimentation tank. The suspended solids filtered by the precision filter 1 accumulate inside the filter and then reach a certain pressure before being backwashed back to the primary defluorination sedimentation tank for sedimentation. After sedimentation, the sludge is sent to the high-pressure sludge dehydration device for dehydration and solid waste is collected.

[0039] Furthermore, the precision filter 2 and the ultrafiltration membrane clarification system filter the residual calcium fluoride and ferric arsenate suspended matter, the ultrafiltration membrane clarification device accumulates the suspended matter and backwashes it back to the precision filter 2, the precision filter 2 accumulates the suspended matter and precipitates it and finally backwashes it back to the chemical oxidation arsenic removal reaction tank for precipitation, and then discharges it into the high-pressure sludge dewatering device to further collect solid waste and recycle water resources; compared with traditional treatment methods, the solid waste content in the waste liquid is further reduced, so as to achieve the purpose of preventing arsenide and fluoride from leaving the factory.

[0040] Furthermore, the ultrafiltration membrane system adopts a full-volume filtration method, and the filtrate simultaneously uses sodium bisulfite to reduce sodium hypochlorite to prevent oxidative damage to the membrane of the membrane concentration system later.

[0041] Preferably, the resin of the resin weight removal device adopts chelating resin, which has high weight removal accuracy and long resin life compared with the traditional technology, and solves the scaling problem of iron, aluminum and calcium salts in the subsequent membrane system;

[0042] Furthermore, when the resin adsorption reaches saturation, it is regenerated with acid and alkali regeneration solution, and the regenerated waste salt solution is directly sent to the evaporation concentration crystallization device for waste salt recovery;

[0043] Furthermore, the acid and alkali regeneration liquid are 4% hydrochloric acid and 4% sodium hydroxide.

[0044] Further preferably, the membrane concentration system is composed of a special high-pressure reverse osmosis membrane system and a low-pressure reverse osmosis membrane system. The membrane materials of the high-pressure reverse osmosis membrane system and the low-pressure reverse osmosis membrane system are made of high molecular polymer materials. The main characteristics of the device are high anti-fouling, high pressure resistance, COD resistance, high ammonia nitrogen interception rate, etc.

[0045] Traditional reverse osmosis membranes have obvious application advantages, avoiding the subsequent problems of unqualified ammonia nitrogen in effluent, low water yield and rapid membrane pollution.

[0046] Preferably, a NaOH solution is added to the deamination tower.

[0047] Furthermore, the water evaporated from the evaporation, concentration and crystallization device meets the standards for discharge or reuse, and the solidified salt is finally transported to a fixed place to be piled up in the rain shelter;

[0048] Compared with traditional technology, this solution effectively separates waste salt;

[0049] Furthermore, the sludge precipitated at the bottom of the aluminum hydroxide reaction sedimentation tank is dehydrated by a high-pressure sludge dehydration device and then sent to the aluminum hydroxide workshop for reuse; the sludge precipitated at the bottom of the primary defluorination coagulation sedimentation tank and the chemical oxidation arsenic removal reaction tank is discharged into a high-pressure sludge dehydration device for dehydration and then treated as hazardous waste or piled up on site;

[0050] At the same time, this scheme further recovers chloride salt by directly sending the regenerated waste salt solution to the evaporation concentration crystallization device;

[0051] The existing technology provides a better treatment method to reduce solid waste and avoid the problems of hazardous waste management and transportation.

[0052] Compared with the prior art, the present invention has the following beneficial effects:

[0053] (1) In this scheme, the aluminum slag leachate and the regeneration waste liquid are treated in the aluminum hydroxide reaction sedimentation tank and the high-pressure sludge dehydration device to obtain aluminum hydroxide with a moisture content greater than 40%. The aluminum hydroxide with a moisture content greater than 40% is returned to the aluminum hydroxide workshop for reuse, which effectively realizes resource recycling and reduces the amount of solid waste generated;

[0054] (2) This scheme uses primary fluorine removal, activated alumina precision fluorine removal, two-stage oxidation to break cyanide, chemical oxidation to remove arsenic, resin weight removal, evaporation concentration crystallization, precision filtration, ultra-membrane clarification and high-pressure sludge dehydration and other processes to remove cyanide by oxidation, convert fluorine and arsenic into calcium fluoride, dehydrate and collect ferric arsenate, and concentrate and crystallize chloride salt, effectively ensuring that arsenide, fluoride and chloride salt do not leave the factory, avoiding the problem of hazardous waste management and transportation;

[0055] (3) In this scheme, the membrane concentration system produces water that meets the standards and can be discharged or reused. Aluminum hydroxide with a water content of more than 40% is returned to the aluminum hydroxide workshop for resource utilization, and the deammonification tower produces 15-20% ammonia water products, and ammonia nitrogen is converted into ammonia water for resource utilization. The operating cost is lower than the original traditional precipitation process, and the economic benefits and comprehensive operating costs generated by aluminum and ammonia nitrogen are far lower than those of traditional processes, truly "making pollution control effective and profitable." BRIEF DESCRIPTION OF THE DRAWINGS

[0056] Figure 1 It is a process flow chart of the present invention.

[0057] Figure 2 This is a diagram of a two-stage inclined tube sedimentation tank.

[0058] Figure 3 This is a diagram of the primary fluoride removal coagulation sedimentation tank.

[0059] Figure 4 This is a diagram of a two-stage oxidation and cyanide destruction reaction pool.

[0060] In the figure, 1, pre-sedimentation tank; 2, regulating tank; 3, aluminum hydroxide reaction sedimentation tank; 4, primary defluorination coagulation sedimentation tank; 5, precision filter one; 6, activated alumina precision defluorination device; 7, two-stage oxidation cyanide breaking reaction tank; 8, chemical oxidation arsenic removal reaction tank; 9, precision filter two; 10, ultrafiltration membrane clarification device; 11, resin weight removal device; 12, membrane concentration system; 13, deammonification tower; 14, evaporation concentration crystallization device; 15, high-pressure sludge dehydration device; 16, hydrochloric acid pump; 17, calcium chloride, aluminum sulfate solution pump; 101, primary sedimentation tank; 102, secondary sedimentation tank; 1 011, first liquid inlet; 1012, first overflow port; 1021, second liquid inlet; 1022, second overflow port; 103, inclined tube; 401, primary dosing mixing zone; 402, primary oxidation reaction zone; 701, dosing mixing zone; 702, primary oxidation reaction zone; 703, secondary oxidation reaction zone; 704, stirring device; 705, incoming water and primary oxidizing agent inlet; 7021, primary oxidation liquid inlet; 7022, primary oxidation overflow port; 7031, secondary oxidation liquid inlet; 7032, secondary oxidation overflow port; 7033, secondary oxidizing agent inlet. DETAILED DESCRIPTION

[0061] The technical solution of the present invention is further described in detail below in conjunction with the accompanying drawings, but the protection scope of the present invention is not limited to the following.

[0062] Example 1

[0063] like Figure 1 As shown, a treatment system for reducing and solidifying the leachate of electrolytic aluminum slag for resource reuse comprises a pre-precipitation tank 1, a regulating tank 2, an aluminum hydroxide reaction precipitation tank 3, a primary defluorination coagulation precipitation tank 4, a precision filter 1 5, an activated alumina precision defluorination device 6, a two-stage oxidation cyanide breaking reaction tank 7, a chemical oxidation arsenic removal reaction tank 8, a precision filter 2 9, an ultrafiltration membrane clarification device 10, a resin weight removal device 11, a membrane concentration system 12, a deammoniation tower 13, and an evaporation concentration crystallization device 14, which are connected in sequence.

[0064] Among them, the above-mentioned aluminum hydroxide reaction sedimentation tank 3, primary fluoride removal coagulation sedimentation tank 4, and chemical oxidation arsenic removal reaction tank 8 are respectively connected to high-pressure sludge dewatering devices 15, and the primary fluoride removal coagulation sedimentation tank 4 and chemical oxidation arsenic removal reaction tank 8 share the same high-pressure sludge dewatering device 15.

[0065] The aluminum hydroxide reaction sedimentation tank 3 is connected to a hydrochloric acid pump 16 for pumping in hydrochloric acid for neutralization and hydrolysis, and the primary defluorination coagulation sedimentation tank 4 is connected to a calcium chloride and aluminum sulfate solution mixing pump 17 for pumping in a mixture of calcium chloride and aluminum sulfate solution for reaction with fluorine;

[0066] Further, the precision filter 1 5, the precision filter 2 9, and the ultrafiltration membrane clarification device 10 are respectively provided with backwash pumps;

[0067] like Figure 2 As shown, the pre-sedimentation tank 1, the aluminum hydroxide reaction sedimentation tank 3, and the primary defluorination coagulation sedimentation tank 4 all adopt two-stage inclined tube sedimentation tanks; the two-stage inclined tube sedimentation tanks include a primary sedimentation tank 101 and a secondary sedimentation tank 102, the primary sedimentation tank 101 is provided with a first liquid inlet 1011 and a first overflow port 1012, the secondary sedimentation tank 102 is provided with a second liquid inlet 1021 and a second overflow port 1022, the primary sedimentation tank 101 and the secondary sedimentation tank 102 are connected through the first overflow port 1012 and the second liquid inlet 1021, and the primary sedimentation tank 101 and the secondary sedimentation tank 102 are respectively provided with inclined tubes 103.

[0068] like Figure 3 As shown, the liquid inlet end of the two-stage inclined tube sedimentation tank corresponding to the primary defluorination coagulation sedimentation tank 4 is also provided with a primary defluorination device, and the primary defluorination device includes a primary dosing mixing zone 401 and a primary oxidation reaction zone 402 which are connected in sequence.

[0069] The first liquid inlet 1011 is located at the bottom of the primary sedimentation tank 101, the first overflow port 1012 is located at the top of the primary sedimentation tank 101, the second liquid inlet 1021 is located at the bottom of the secondary sedimentation tank 102, the second overflow port 1022 is located at the top of the secondary sedimentation tank 102, the first liquid inlet 1011 is connected to the water inlet 104, and the water inlet 104 is located at the top of the primary sedimentation tank 101.

[0070] like Figure 4 As shown, the two-stage oxidation cyanide destruction reaction tank 7 includes a dosing mixing zone 701, a primary oxidation reaction zone 702 and a secondary oxidation reaction zone 703 which are connected in sequence, and a stirring device 704 is provided in the primary oxidation reaction zone 702 and the secondary oxidation reaction zone 703;

[0071] The dosing and mixing zone 701 is provided with an inlet 705 for water and a primary oxidizing agent, the primary oxidizing reaction zone 702 is provided with a primary oxidizing liquid inlet 7021 and a primary oxidizing overflow port 7022, and the secondary oxidizing reaction zone 703 is provided with a secondary oxidizing liquid inlet 7031, a secondary oxidizing overflow port 7032 and a secondary oxidizing agent inlet 7033;

[0072] The incoming water and primary oxidizing agent inlet 705 are located at the top of the dosing mixing zone 701; the primary oxidation liquid inlet 7021 is located at the bottom of the primary oxidation reaction zone 702, and the primary oxidation overflow port 7022 is located at the top of the primary oxidation reaction zone 702; the secondary oxidation liquid inlet 7031 is located at the bottom of the secondary oxidation reaction zone 703, the secondary oxidation overflow port 7032 is located at one end of the top of the secondary oxidation reaction zone 703, and the secondary oxidizing agent inlet 7033 is located at the other end of the top of the secondary oxidation reaction zone 703 and close to the secondary oxidation liquid inlet 7031.

[0073] A method for treating a certain electrolytic aluminum slag leachate by reducing and solidifying the leachate for resource reuse uses the treatment system for treating a certain electrolytic aluminum slag leachate by reducing and solidifying the leachate for resource reuse as described in the first aspect, and comprises the following steps:

[0074] 1) The electrolytic aluminum slag leachate is sent to the pre-precipitation tank 1 for precipitation, and the precipitated sludge is extracted and dehydrated from the V-shaped funnel at the bottom of the device, and stays for 0.5-1 hour, and the obtained supernatant is sent to the regulating tank 2;

[0075] 2) The supernatant after the pre-precipitation is stirred in the regulating tank 2, and after staying for 1-2 hours, it overflows into the aluminum hydroxide reaction precipitation tank 3;

[0076] 3) The overflow liquid of the regulating tank 2 reacts with hydrochloric acid in the aluminum hydroxide reaction sedimentation tank 3, the reaction time is 10-30min, the reaction pH is controlled to be in the range of 7-8, the reaction molar ratio is: hydrochloric acid: aluminum>3:1, the suspended matter produced by the reaction is precipitated in the sedimentation tank of the aluminum hydroxide reaction sedimentation tank 3, the suspended matter settles to the V-type funnel, the sedimentation time is 0.5-2h, and the obtained supernatant overflows from the top overflow port;

[0077] 4) The supernatant overflowing from the aluminum hydroxide reaction sedimentation tank 3 is mixed with calcium chloride and aluminum sulfate solution and pumped into the primary defluorination coagulation sedimentation tank 4 by a pump, the reaction molar ratio is: calcium chloride: aluminum sulfate: fluorine> 1:2.5:1, the reaction time is 10-30min, the reaction pH is 8-9, the liquid after the reaction enters the sedimentation tank of the primary defluorination coagulation sedimentation tank 4 for precipitation, and the suspended matter containing calcium fluoride and aluminum hydroxide colloid generated by the reaction is partially settled in the two-stage inclined tube sedimentation tank of the primary defluorination coagulation sedimentation tank 4 to the V-funnel, the sedimentation time is 0.5-2h, and the supernatant obtained after precipitation flows out from the top overflow port;

[0078] 5) The overflow liquid of the primary defluorination coagulation sedimentation tank 4 is pumped into the precision filter 5 for filtration, and the filtrate with suspended matter less than 1 mg / L is obtained after filtration;

[0079] 6) The filtrate after passing through the precision filter 5 is pumped into the activated alumina precision defluorination device 6 for activated alumina adsorption defluorination, and after adsorption defluorination, wastewater with a fluorine content of 2-4 mg / L is obtained;

[0080] 7) Pumping the wastewater after adsorption and defluorination into the two-stage oxidation cyanide breaking reaction tank 7 for primary oxidation cyanide breaking and secondary oxidation cyanide breaking cyanide removal, the primary oxidation cyanide breaking is adjusted to pH=10, the primary oxidation cyanide breaking reaction molar ratio is: sodium hypochlorite: cyanide=10:1, after the primary oxidation cyanide breaking, it is connected to the secondary oxidation cyanide breaking reaction tank through the top overflow, the secondary oxidation cyanide breaking is adjusted to pH=8, the reaction molar ratio is: sodium hypochlorite: cyanide>2:1, after the two-stage oxidation cyanide breaking reaction time is 30min, a liquid with cyanide reduced to 0.5mg / L is obtained;

[0081] 8) The liquid after cyanide removal is sent to the chemical oxidation arsenic removal reaction tank 8 to add ferric chloride, and the mixture reacts to form a ferric arsenate suspension with extremely low solubility. The reaction molar ratio is: ferric chloride: arsenide> 1.5:1, the reaction time is 10-30min, and the arsenide is reduced to 0.1mg / L after chemical oxidation arsenic removal;

[0082] 9) filtering the liquid containing suspended matter obtained after arsenic removal through a precision filter 9 to obtain a filtrate with suspended matter less than 1 mg / L;

[0083] 10) The filtrate obtained by filtering the precision filter 29 is sent to the ultrafiltration membrane clarification device 10, the membrane pore size of the ultrafiltration membrane clarification device 10 is 100,000-200,000 Daltons, the operating pressure is 0.1-0.3Mpa, the operating temperature is 5-45°C, and the full amount is filtered. The filtrate is simultaneously reduced with sodium hypochlorite using sodium bisulfite to prevent oxidative damage to the membrane of the membrane concentration system 12, and the ultrafiltration filtrate is obtained after filtration;

[0084] 11) The ultrafiltration filtrate is pumped into the resin deweighting device 11 by a pump for deep adsorption of calcium, magnesium, aluminum and iron, and deweighted water with an ion concentration of less than 2 mg / L is obtained after adsorption;

[0085] 12) Pumping the deweighted water into the membrane concentration system 12 by a pump to concentrate and reduce the salt, first pumping it into the high-pressure reverse osmosis membrane system, and then entering the low-pressure reverse osmosis membrane system, concentrating the salt to a concentration of 9-10%, and the ammonia nitrogen to 2000mg / L, recycling the water, producing water to 50-100us / cm, and filtering a large amount of COD at the same time to make the COD content not exceed the standard, the operating pressure of the high-pressure reverse osmosis membrane system is 8-12MPa, the operating pressure of the low-pressure reverse osmosis membrane system is 1.5-2.5Mpa, the temperature is 25-35°C, and the pH is 6.5-7.0, and a membrane concentrated concentrate is obtained after membrane concentration;

[0086] 13) The concentrated solution after membrane concentration enters the deammonification tower 13 device for ammonia nitrogen recovery, and liquid alkali is added to react with ammonium in the solution to produce ammonia, and the ammonia is then volatilized to the top of the tower through steam heat transfer and overflowed. The overflowing ammonia gas is then condensed into ammonia water through a condensation device. The recovered ammonia water can reach a concentration of 15-20%, while the ammonia at the bottom of the kettle becomes less and less, and finally the ammonia nitrogen volatilizes to 15 mg / L and is discharged from the bottom of the kettle;

[0087] 14) The mother liquid at the bottom of the deamination tower is pumped into the evaporation concentration crystallization device 14 by a pump, and water and concentrated and solidified salt are obtained by evaporation. The evaporated water meets the standards for discharge or reuse, and the solidified salt is finally transported to a fixed place for rain shelter and stacked;

[0088] 15) The sludge precipitated at the bottom of the primary fluoride removal coagulation sedimentation tank 4 and the chemical oxidation arsenic removal reaction tank 8 is discharged into the same high-pressure sludge dehydration device 15 for dehydration, and the sludge precipitated at the bottom of the aluminum hydroxide reaction sedimentation tank 3 is discharged into another high-pressure sludge dehydration device 15 for dehydration. After the sludge at the bottom of the aluminum hydroxide reaction sedimentation tank 3 is dehydrated, aluminum hydroxide with a water content greater than 40% is obtained, and the aluminum hydroxide with a water content greater than 40% is sent to the aluminum hydroxide workshop.

[0089] Further, the sludge obtained by precipitation at the bottom of the aluminum hydroxide reaction sedimentation tank 3, the primary defluorination coagulation sedimentation tank 4 and the chemical oxidation arsenic removal reaction tank 8 is discharged into the high-pressure sludge dehydration device 15;

[0090] Preferably, the high-pressure sludge dewatering device 15 adopts a high-pressure plate and frame filter press, which can reduce the water content to 40-55%, with an operating pressure of 2-5 MPa and an operating time of 2-4 hours.

[0091] Further, when the activated alumina adsorption reaches the saturation concentration, a 3-4% aluminum sulfate solution is used to regenerate the activated alumina defluoridation agent, and the regeneration waste liquid is returned to the aluminum hydroxide reaction sedimentation tank 3;

[0092] Preferably, the resin of the resin weight removal device 11 is chelating resin, which has high weight removal accuracy, long resin life, and solves the scaling problem of iron, aluminum and calcium salts in the subsequent membrane system. When the resin adsorption reaches saturation, it is regenerated with acid and alkali regeneration liquid. The regenerated waste salt solution after regeneration is directly sent to the evaporation concentration crystallization device 14, and the acid and alkali regeneration liquid is 4% hydrochloric acid and 4% sodium hydroxide.

[0093] Preferably, the membrane materials of the high-pressure reverse osmosis membrane system and the low-pressure reverse osmosis membrane system are made of high molecular polymer materials. The main characteristics of the device are high anti-fouling, high pressure resistance, COD resistance, high ammonia nitrogen interception rate, etc., which have obvious application advantages over traditional RO membranes and avoid the problems of unqualified effluent ammonia nitrogen, low water recovery rate, and rapid membrane pollution.

[0094] Preferably, the filter elements of precision filter 1 and precision filter 2 are made of titanium-aluminum intermetallic compound with a precision of 0.1-0.5um;

[0095] Furthermore, when the precision filter 1 5 is backwashed, the backwash liquid returns to the primary fluorine removal coagulation sedimentation tank 4, when the precision filter 2 9 is backwashed, the backwash liquid returns to the chemical oxidation arsenic removal reaction tank 8, and when the ultrafiltration membrane clarification device 10 is backwashed, the backwash liquid returns to the precision filter 2 9.

[0096] Furthermore, the ultrafiltration membrane clarification device 10 filters and simultaneously inputs sodium bisulfite to reduce sodium hypochlorite.

[0097] Preferably, a NaOH solution is added to the deamination tower.

[0098] Preferably, the activated alumina is r-alumina.

[0099] More preferably, after the resin adsorption for weight removal reaches saturation, it is regenerated using 4% hydrochloric acid and 4% sodium hydroxide, and the regenerated waste salt solution is directly sent to the evaporation concentration crystallization device 14.

[0100] The raw water index of a certain electrolytic aluminum slag leachate is as follows:

[0101]

[0102] After the electrolytic aluminum slag leachate adopts this technology, the water production indicators of the membrane concentration system are as follows:

[0103]

[0104] The main treatment effects of a certain electrolytic aluminum slag leachate after being treated with this technical solution are as follows:

[0105]

[0106] Example 2

[0107] like Figure 1 As shown, a treatment system for reducing and solidifying the leachate of electrolytic aluminum slag for resource reuse comprises a pre-precipitation tank 1, a regulating tank 2, an aluminum hydroxide reaction precipitation tank 3, a primary defluorination coagulation precipitation tank 4, a precision filter 1 5, an activated alumina precision defluorination device 6, a two-stage oxidation cyanide breaking reaction tank 7, a chemical oxidation arsenic removal reaction tank 8, a precision filter 2 9, an ultrafiltration membrane clarification device 10, a resin weight removal device 11, a membrane concentration system 12, a deammoniation tower 13, and an evaporation concentration crystallization device 14, which are connected in sequence.

[0108] Among them, the above-mentioned aluminum hydroxide reaction sedimentation tank 3, primary fluoride removal coagulation sedimentation tank 4, and chemical oxidation arsenic removal reaction tank 8 are respectively connected to high-pressure sludge dewatering devices 15, and the primary fluoride removal coagulation sedimentation tank 4 and chemical oxidation arsenic removal reaction tank 8 share the same high-pressure sludge dewatering device 15.

[0109] The aluminum hydroxide reaction sedimentation tank 3 is connected to a hydrochloric acid pump 16 for pumping in hydrochloric acid for neutralization and hydrolysis, and the primary defluorination coagulation sedimentation tank 4 is connected to a calcium chloride and aluminum sulfate solution mixing pump 17 for pumping in a mixture of calcium chloride and aluminum sulfate solution for reaction with fluorine;

[0110] Further, the precision filter 1 5, the precision filter 2 9, and the ultrafiltration membrane clarification device 10 are respectively provided with backwash pumps;

[0111] like Figure 2 As shown, the pre-sedimentation tank 1, the aluminum hydroxide reaction sedimentation tank 3, and the primary defluorination coagulation sedimentation tank 4 all adopt two-stage inclined tube sedimentation tanks; the two-stage inclined tube sedimentation tanks include a primary sedimentation tank 101 and a secondary sedimentation tank 102, the primary sedimentation tank 101 is provided with a first liquid inlet 1011 and a first overflow port 1012, the secondary sedimentation tank 102 is provided with a second liquid inlet 1021 and a second overflow port 1022, the primary sedimentation tank 101 and the secondary sedimentation tank 102 are connected through the first overflow port 1012 and the second liquid inlet 1021, and the primary sedimentation tank 101 and the secondary sedimentation tank 102 are respectively provided with inclined tubes 103.

[0112] like Figure 3 As shown, the liquid inlet end of the two-stage inclined tube sedimentation tank corresponding to the primary defluorination coagulation sedimentation tank 4 is also provided with a primary defluorination device, and the primary defluorination device includes a primary dosing mixing zone 401 and a primary oxidation reaction zone 402 which are connected in sequence.

[0113] The first liquid inlet 1011 is located at the bottom of the primary sedimentation tank 101, the first overflow port 1012 is located at the top of the primary sedimentation tank 101, the second liquid inlet 1021 is located at the bottom of the secondary sedimentation tank 102, the second overflow port 1022 is located at the top of the secondary sedimentation tank 102, the first liquid inlet 1011 is connected to the water inlet 104, and the water inlet 104 is located at the top of the primary sedimentation tank 101.

[0114] like Figure 4 As shown, the two-stage oxidation cyanide destruction reaction tank 7 includes a dosing mixing zone 701, a primary oxidation reaction zone 702 and a secondary oxidation reaction zone 703 which are connected in sequence, and a stirring device 704 is provided in the primary oxidation reaction zone 702 and the secondary oxidation reaction zone 703;

[0115] The dosing and mixing zone 701 is provided with an inlet 705 for water and a primary oxidizing agent, the primary oxidizing reaction zone 702 is provided with a primary oxidizing liquid inlet 7021 and a primary oxidizing overflow port 7022, and the secondary oxidizing reaction zone 703 is provided with a secondary oxidizing liquid inlet 7031, a secondary oxidizing overflow port 7032 and a secondary oxidizing agent inlet 7033;

[0116] The incoming water and primary oxidizing agent inlet 705 are located at the top of the dosing mixing zone 701; the primary oxidation liquid inlet 7021 is located at the bottom of the primary oxidation reaction zone 702, and the primary oxidation overflow port 7022 is located at the top of the primary oxidation reaction zone 702; the secondary oxidation liquid inlet 7031 is located at the bottom of the secondary oxidation reaction zone 703, the secondary oxidation overflow port 7032 is located at one end of the top of the secondary oxidation reaction zone 703, and the secondary oxidizing agent inlet 7033 is located at the other end of the top of the secondary oxidation reaction zone 703 and close to the secondary oxidation liquid inlet 7031.

[0117] A method for treating a certain electrolytic aluminum slag leachate by reducing and solidifying the leachate for resource reuse uses the treatment system for treating a certain electrolytic aluminum slag leachate by reducing and solidifying the leachate for resource reuse as described in the first aspect, and comprises the following steps:

[0118] 1) The electrolytic aluminum slag leachate is sent to the pre-precipitation tank 1 for precipitation, and the precipitated sludge is extracted and dehydrated from the V-shaped funnel at the bottom of the device, and stays for 1 hour, and the obtained supernatant is sent to the regulating tank 2;

[0119] 2) The supernatant after the pre-precipitation is stirred in the regulating tank 2, and after staying for 2 hours, it overflows into the aluminum hydroxide reaction precipitation tank 3;

[0120] 3) The overflow liquid of the regulating tank 2 reacts with hydrochloric acid in the aluminum hydroxide reaction sedimentation tank 3, the reaction time is 30 minutes, the reaction pH is controlled to be 8, the reaction molar ratio is: hydrochloric acid: aluminum>3:1, the suspended matter produced by the reaction is precipitated in the sedimentation tank of the aluminum hydroxide reaction sedimentation tank 3, the suspended matter settles to the V-shaped funnel, the sedimentation time is 0.5-2 hours, and the obtained supernatant overflows from the top overflow port;

[0121] 4) The supernatant overflowing from the aluminum hydroxide reaction sedimentation tank 3 is mixed with calcium chloride and aluminum sulfate solution and pumped into the primary defluorination coagulation sedimentation tank 4 by a pump, the reaction molar ratio is: calcium chloride: aluminum sulfate: fluorine> 1:2.5:1, the reaction time is 30 minutes, the reaction pH is 9, the liquid after the reaction enters the sedimentation tank of the primary defluorination coagulation sedimentation tank 4 for precipitation, and the suspended matter containing calcium fluoride and aluminum hydroxide colloid generated by the reaction is partially settled in the two-stage inclined tube sedimentation tank of the primary defluorination coagulation sedimentation tank 4 to the V-funnel, the sedimentation time is 2 hours, and the supernatant obtained after precipitation flows out from the top overflow port;

[0122] 5) The overflow liquid of the primary defluorination coagulation sedimentation tank 4 is pumped into the precision filter 5 for filtration, and the filtrate with suspended matter less than 1 mg / L is obtained after filtration;

[0123] 6) The filtrate after passing through the precision filter 5 is pumped into the activated alumina precision defluorination device 6 for activated alumina adsorption defluorination, and after adsorption defluorination, wastewater with a fluorine content of 2-4 mg / L is obtained;

[0124] 7) Pumping the wastewater after adsorption and defluorination into the two-stage oxidation cyanide breaking reaction tank 7 for primary oxidation cyanide breaking and secondary oxidation cyanide breaking cyanide removal, the primary oxidation cyanide breaking is adjusted to pH=10, the primary oxidation cyanide breaking reaction molar ratio is: sodium hypochlorite: cyanide=10:1, after the primary oxidation cyanide breaking, it is connected to the secondary oxidation cyanide breaking reaction tank through the top overflow, the secondary oxidation cyanide breaking is adjusted to pH=8, the reaction molar ratio is: sodium hypochlorite: cyanide>2:1, after the two-stage oxidation cyanide breaking reaction time is 30min, a liquid with cyanide reduced to 0.5mg / L is obtained;

[0125] 8) The liquid after cyanide removal is sent to the chemical oxidation arsenic removal reaction tank 8 to add ferric chloride, and the mixture reacts to form a ferric arsenate suspension with extremely low dissolution. The reaction molar ratio is: ferric chloride: arsenide> 1.5:1, the reaction time is 30 minutes, and the arsenide is reduced to 0.1 mg / L after chemical oxidation arsenic removal;

[0126] 9) filtering the liquid containing suspended matter obtained after arsenic removal through a precision filter 9 to obtain a filtrate with suspended matter less than 1 mg / L;

[0127] 10) The filtrate obtained by filtering the precision filter 29 is sent to the ultrafiltration membrane clarification device 10, the membrane pore size of the ultrafiltration membrane clarification device 10 is 200,000 Daltons, the operating pressure is 0.3Mpa, the operating temperature is 45°C, and the full amount filtration method is adopted. The filtrate is simultaneously reduced with sodium hypochlorite using sodium bisulfite to prevent oxidative damage to the membrane of the membrane concentration system 12 later, and the ultrafiltration filtrate is obtained after filtration;

[0128] 11) The ultrafiltration filtrate is pumped into the resin deweighting device 11 by a pump for deep adsorption of calcium, magnesium, aluminum and iron, and deweighted water with an ion concentration of less than 2 mg / L is obtained after adsorption;

[0129] 12) pumping the deweighted water into a membrane concentration system 12 to concentrate and reduce the salt, first pumping it into a high-pressure reverse osmosis membrane system, and then entering a low-pressure reverse osmosis membrane system, concentrating the salt to a concentration of 9-10%, and the ammonia nitrogen to 2000 mg / L, recycling the water, producing water to 50-100 us / cm, and filtering a large amount of COD at the same time to ensure that the COD content does not exceed the standard, the operating pressure of the high-pressure reverse osmosis membrane system is 12 MPa, the operating pressure of the low-pressure reverse osmosis membrane system is 2.5 MPa, the temperature is 25° C., and the pH is 7.0. After membrane concentration, a membrane concentrated concentrate is obtained;

[0130] 13) The concentrated solution after membrane concentration enters the deammonification tower 13 device for ammonia nitrogen recovery, and liquid alkali is added to react with ammonium in the solution to produce ammonia, and the ammonia is then volatilized to the top of the tower through steam heat transfer and overflowed. The overflowing ammonia gas is then condensed into ammonia water through a condensation device. The recovered ammonia water can reach a concentration of 15-20%, while the ammonia at the bottom of the kettle becomes less and less, and finally the ammonia nitrogen volatilizes to 15 mg / L and is discharged from the bottom of the kettle;

[0131] 14) The mother liquid at the bottom of the deamination tower is pumped into the evaporation concentration crystallization device 14 by a pump, and water and concentrated and solidified salt are obtained by evaporation. The evaporated water meets the standards for discharge or reuse, and the solidified salt is finally transported to a fixed place for rain shelter and stacked;

[0132] 15) The sludge precipitated at the bottom of the primary fluoride removal coagulation sedimentation tank 4 and the chemical oxidation arsenic removal reaction tank 8 is discharged into the same high-pressure sludge dehydration device 15 for dehydration, and the sludge precipitated at the bottom of the aluminum hydroxide reaction sedimentation tank 3 is discharged into another high-pressure sludge dehydration device 15 for dehydration. After the sludge at the bottom of the aluminum hydroxide reaction sedimentation tank 3 is dehydrated, aluminum hydroxide with a water content greater than 40% is obtained, and the aluminum hydroxide with a water content greater than 40% is sent to the aluminum hydroxide workshop.

[0133] Further, the sludge obtained by precipitation at the bottom of the aluminum hydroxide reaction sedimentation tank 3, the primary defluorination coagulation sedimentation tank 4 and the chemical oxidation arsenic removal reaction tank 8 is discharged into the high-pressure sludge dehydration device 15;

[0134] Preferably, the high-pressure sludge dewatering device 15 adopts a high-pressure plate and frame filter press, which can reduce the water content to 40-55%, with an operating pressure of 5 MPa and an operating time of 2 hours.

[0135] Further, when the activated alumina adsorption reaches the saturation concentration, a 4% aluminum sulfate solution is used to regenerate the activated alumina defluorinating agent, and the regenerated waste liquid is returned to the aluminum hydroxide reaction sedimentation tank 3;

[0136] Preferably, the resin of the resin weight removal device 11 is chelating resin, which has high weight removal accuracy, long resin life, and solves the scaling problem of iron, aluminum and calcium salts in the subsequent membrane system. When the resin adsorption reaches saturation, it is regenerated with acid and alkali regeneration liquid. The regenerated waste salt solution after regeneration is directly sent to the evaporation concentration crystallization device 14, and the acid and alkali regeneration liquid is 4% hydrochloric acid and 4% sodium hydroxide.

[0137] Preferably, the membrane materials of the high-pressure reverse osmosis membrane system and the low-pressure reverse osmosis membrane system are made of high molecular polymer materials. The main characteristics of the device are high anti-fouling, high pressure resistance, COD resistance, high ammonia nitrogen interception rate, etc., which have obvious application advantages over traditional RO membranes and avoid the problems of unqualified effluent ammonia nitrogen, low water recovery rate, and rapid membrane pollution.

[0138] Preferably, the filter elements of precision filter 1 and precision filter 2 are made of titanium-aluminum intermetallic compound with a precision of 0.5um;

[0139] Furthermore, when the precision filter 1 5 is backwashed, the backwash liquid returns to the primary fluorine removal coagulation sedimentation tank 4, when the precision filter 2 9 is backwashed, the backwash liquid returns to the chemical oxidation arsenic removal reaction tank 8, and when the ultrafiltration membrane clarification device 10 is backwashed, the backwash liquid returns to the precision filter 2 9.

[0140] Furthermore, the ultrafiltration membrane clarification device 10 filters and simultaneously inputs sodium bisulfite to reduce sodium hypochlorite.

[0141] Preferably, a NaOH solution is added to the deamination tower.

[0142] Preferably, the activated alumina is r-alumina.

[0143] More preferably, after the resin adsorption for weight removal reaches saturation, it is regenerated using 4% hydrochloric acid and 4% sodium hydroxide, and the regenerated waste salt solution is directly sent to the evaporation concentration crystallization device 14.

[0144] Example 3

[0145] like Figure 1 As shown, a treatment system for reducing and solidifying the leachate of electrolytic aluminum slag for resource reuse comprises a pre-precipitation tank 1, a regulating tank 2, an aluminum hydroxide reaction precipitation tank 3, a primary defluorination coagulation precipitation tank 4, a precision filter 1 5, an activated alumina precision defluorination device 6, a two-stage oxidation cyanide breaking reaction tank 7, a chemical oxidation arsenic removal reaction tank 8, a precision filter 2 9, an ultrafiltration membrane clarification device 10, a resin weight removal device 11, a membrane concentration system 12, a deammoniation tower 13, and an evaporation concentration crystallization device 14, which are connected in sequence.

[0146] Among them, the above-mentioned aluminum hydroxide reaction sedimentation tank 3, primary fluoride removal coagulation sedimentation tank 4, and chemical oxidation arsenic removal reaction tank 8 are respectively connected to high-pressure sludge dewatering devices 15, and the primary fluoride removal coagulation sedimentation tank 4 and chemical oxidation arsenic removal reaction tank 8 share the same high-pressure sludge dewatering device 15.

[0147] The aluminum hydroxide reaction sedimentation tank 3 is connected to a hydrochloric acid pump 16 for pumping in hydrochloric acid for neutralization and hydrolysis, and the primary defluorination coagulation sedimentation tank 4 is connected to a calcium chloride and aluminum sulfate solution mixing pump 17 for pumping in a mixture of calcium chloride and aluminum sulfate solution for reaction with fluorine;

[0148] Further, the precision filter 1 5, the precision filter 2 9, and the ultrafiltration membrane clarification device 10 are respectively provided with backwash pumps;

[0149] like Figure 2 As shown, the pre-sedimentation tank 1, the aluminum hydroxide reaction sedimentation tank 3, and the primary defluorination coagulation sedimentation tank 4 all adopt two-stage inclined tube sedimentation tanks; the two-stage inclined tube sedimentation tanks include a primary sedimentation tank 101 and a secondary sedimentation tank 102, the primary sedimentation tank 101 is provided with a first liquid inlet 1011 and a first overflow port 1012, the secondary sedimentation tank 102 is provided with a second liquid inlet 1021 and a second overflow port 1022, the primary sedimentation tank 101 and the secondary sedimentation tank 102 are connected through the first overflow port 1012 and the second liquid inlet 1021, and the primary sedimentation tank 101 and the secondary sedimentation tank 102 are respectively provided with inclined tubes 103.

[0150] like Figure 3As shown, the liquid inlet end of the two-stage inclined tube sedimentation tank corresponding to the primary defluorination coagulation sedimentation tank 4 is also provided with a primary defluorination device, and the primary defluorination device includes a primary dosing mixing zone 401 and a primary oxidation reaction zone 402 which are connected in sequence.

[0151] The first liquid inlet 1011 is located at the bottom of the primary sedimentation tank 101, the first overflow port 1012 is located at the top of the primary sedimentation tank 101, the second liquid inlet 1021 is located at the bottom of the secondary sedimentation tank 102, the second overflow port 1022 is located at the top of the secondary sedimentation tank 102, the first liquid inlet 1011 is connected to the water inlet 104, and the water inlet 104 is located at the top of the primary sedimentation tank 101.

[0152] like Figure 4 As shown, the two-stage oxidation cyanide destruction reaction tank 7 includes a dosing mixing zone 701, a primary oxidation reaction zone 702 and a secondary oxidation reaction zone 703 which are connected in sequence, and a stirring device 704 is provided in the primary oxidation reaction zone 702 and the secondary oxidation reaction zone 703;

[0153] The dosing and mixing zone 701 is provided with an inlet 705 for water and a primary oxidizing agent, the primary oxidizing reaction zone 702 is provided with a primary oxidizing liquid inlet 7021 and a primary oxidizing overflow port 7022, and the secondary oxidizing reaction zone 703 is provided with a secondary oxidizing liquid inlet 7031, a secondary oxidizing overflow port 7032 and a secondary oxidizing agent inlet 7033;

[0154] The incoming water and primary oxidizing agent inlet 705 are located at the top of the dosing mixing zone 701; the primary oxidation liquid inlet 7021 is located at the bottom of the primary oxidation reaction zone 702, and the primary oxidation overflow port 7022 is located at the top of the primary oxidation reaction zone 702; the secondary oxidation liquid inlet 7031 is located at the bottom of the secondary oxidation reaction zone 703, the secondary oxidation overflow port 7032 is located at one end of the top of the secondary oxidation reaction zone 703, and the secondary oxidizing agent inlet 7033 is located at the other end of the top of the secondary oxidation reaction zone 703 and close to the secondary oxidation liquid inlet 7031.

[0155] A method for treating a certain electrolytic aluminum slag leachate by reducing and solidifying the leachate for resource reuse uses the treatment system for treating a certain electrolytic aluminum slag leachate by reducing and solidifying the leachate for resource reuse as described in the first aspect, and comprises the following steps:

[0156] 1) The electrolytic aluminum slag leachate is sent to the pre-precipitation tank 1 for precipitation, and the precipitated sludge is extracted and dehydrated from the V-shaped funnel at the bottom of the device, and stays for 0.5 hours, and the obtained supernatant is sent to the regulating tank 2;

[0157] 2) The supernatant after the pre-precipitation is stirred in the regulating tank 2, and after staying for 1 hour, it overflows into the aluminum hydroxide reaction precipitation tank 3;

[0158] 3) The overflow liquid of the regulating tank 2 reacts with hydrochloric acid in the aluminum hydroxide reaction sedimentation tank 3, the reaction time is 10 minutes, the reaction pH is controlled to be 7, the reaction molar ratio is: hydrochloric acid: aluminum>3:1, the suspended matter produced by the reaction is precipitated in the sedimentation tank of the aluminum hydroxide reaction sedimentation tank 3, the suspended matter settles to the V-type funnel, the sedimentation time is 0.5 hours, and the obtained supernatant overflows from the top overflow port;

[0159] 4) The supernatant overflowing from the aluminum hydroxide reaction sedimentation tank 3 is mixed with calcium chloride and aluminum sulfate solution and pumped into the primary defluorination coagulation sedimentation tank 4 by a pump, the reaction molar ratio is: calcium chloride: aluminum sulfate: fluorine> 1:2.5:1, the reaction time is 10 minutes, the reaction pH is 8, the liquid after the reaction enters the sedimentation tank of the primary defluorination coagulation sedimentation tank 4 for precipitation, and the suspended matter containing calcium fluoride and aluminum hydroxide colloid generated by the reaction is partially settled in the two-stage inclined tube sedimentation tank of the primary defluorination coagulation sedimentation tank 4 to the V-funnel, the sedimentation time is 0.5 hours, and the supernatant obtained after precipitation flows out from the top overflow port;

[0160] 5) The overflow liquid of the primary defluorination coagulation sedimentation tank 4 is pumped into the precision filter 5 for filtration, and the filtrate with suspended matter less than 1 mg / L is obtained after filtration;

[0161] 6) The filtrate after passing through the precision filter 5 is pumped into the activated alumina precision defluorination device 6 for activated alumina adsorption defluorination, and after adsorption defluorination, wastewater with a fluorine content of 2-4 mg / L is obtained;

[0162] 7) Pumping the wastewater after adsorption and defluorination into the two-stage oxidation cyanide breaking reaction tank 7 for primary oxidation cyanide breaking and secondary oxidation cyanide breaking cyanide removal, the primary oxidation cyanide breaking is adjusted to pH=10, the primary oxidation cyanide breaking reaction molar ratio is: sodium hypochlorite: cyanide=10:1, after the primary oxidation cyanide breaking, it is connected to the secondary oxidation cyanide breaking reaction tank through the top overflow, the secondary oxidation cyanide breaking is adjusted to pH=8, the reaction molar ratio is: sodium hypochlorite: cyanide>2:1, after the two-stage oxidation cyanide breaking reaction time is 30min, a liquid with cyanide reduced to 0.5mg / L is obtained;

[0163] 8) The liquid after cyanide removal is sent to the chemical oxidation arsenic removal reaction tank 8 to add ferric chloride, and the mixture reacts to form a ferric arsenate suspension with extremely low solubility. The reaction molar ratio is: ferric chloride: arsenide> 1.5:1, the reaction time is 10 minutes, and the arsenide is reduced to 0.1 mg / L after chemical oxidation arsenic removal;

[0164] 9) filtering the liquid containing suspended matter obtained after arsenic removal through a precision filter 9 to obtain a filtrate with suspended matter less than 1 mg / L;

[0165] 10) The filtrate obtained by filtering the precision filter 29 is sent to the ultrafiltration membrane clarification device 10, the membrane pore size of the ultrafiltration membrane clarification device 10 is 100,000 Daltons, the operating pressure is 0.1Mpa, the operating temperature is 5°C, and the full amount filtration method is adopted. The filtrate is simultaneously reduced with sodium hypochlorite using sodium bisulfite to prevent oxidative damage to the membrane of the membrane concentration system 12 later, and the ultrafiltration filtrate is obtained after filtration;

[0166] 11) The ultrafiltration filtrate is pumped into the resin deweighting device 11 by a pump for deep adsorption of calcium, magnesium, aluminum and iron, and deweighted water with an ion concentration of less than 2 mg / L is obtained after adsorption;

[0167] 12) Pumping the deweighted water into the membrane concentration system 12 by a pump to concentrate and reduce the salt, first pumping it into the high-pressure reverse osmosis membrane system, and then entering the low-pressure reverse osmosis membrane system, concentrating the salt to a concentration of 9-10%, and the ammonia nitrogen to 2000mg / L, recycling the water, producing water to 50-100us / cm, and filtering a large amount of COD at the same time to make the COD content not exceed the standard, the operating pressure of the high-pressure reverse osmosis membrane system is 8MPa, the operating pressure of the low-pressure reverse osmosis membrane system is 1.5Mpa, the temperature is 35°C, and the pH is 6.5. After membrane concentration, a membrane concentrated concentrate is obtained;

[0168] 13) The concentrated solution after membrane concentration enters the deammonification tower 13 device for ammonia nitrogen recovery, and liquid alkali is added to react with ammonium in the solution to produce ammonia, and the ammonia is then volatilized to the top of the tower through steam heat transfer and overflowed. The overflowing ammonia gas is then condensed into ammonia water through a condensation device. The recovered ammonia water can reach a concentration of 15-20%, while the ammonia at the bottom of the kettle becomes less and less, and finally the ammonia nitrogen volatilizes to 15 mg / L and is discharged from the bottom of the kettle;

[0169] 14) The mother liquid at the bottom of the deamination tower is pumped into the evaporation concentration crystallization device 14 by a pump, and water and concentrated and solidified salt are obtained by evaporation. The evaporated water meets the standards for discharge or reuse, and the solidified salt is finally transported to a fixed place for rain shelter and stacked;

[0170] 15) The sludge precipitated at the bottom of the primary fluoride removal coagulation sedimentation tank 4 and the chemical oxidation arsenic removal reaction tank 8 is discharged into the same high-pressure sludge dehydration device 15 for dehydration, and the sludge precipitated at the bottom of the aluminum hydroxide reaction sedimentation tank 3 is discharged into another high-pressure sludge dehydration device 15 for dehydration. After the sludge at the bottom of the aluminum hydroxide reaction sedimentation tank 3 is dehydrated, aluminum hydroxide with a water content greater than 40% is obtained, and the aluminum hydroxide with a water content greater than 40% is sent to the aluminum hydroxide workshop.

[0171] Further, the sludge obtained by precipitation at the bottom of the aluminum hydroxide reaction sedimentation tank 3, the primary defluorination coagulation sedimentation tank 4 and the chemical oxidation arsenic removal reaction tank 8 is discharged into the high-pressure sludge dehydration device 15;

[0172] Preferably, the high-pressure sludge dewatering device 15 adopts a high-pressure plate and frame filter press, which can reduce the water content to 40-55%, with an operating pressure of 2Mpa and an operating time of 4h.

[0173] Further, when the activated alumina adsorption reaches the saturation concentration, a 3% aluminum sulfate solution is used to regenerate the activated alumina defluorinating agent, and the regenerated waste liquid is returned to the aluminum hydroxide reaction sedimentation tank 3;

[0174] Preferably, the resin of the resin weight removal device 11 is chelating resin, which has high weight removal accuracy, long resin life, and solves the scaling problem of iron, aluminum and calcium salts in the subsequent membrane system. When the resin adsorption reaches saturation, it is regenerated with acid and alkali regeneration liquid. The regenerated waste salt solution after regeneration is directly sent to the evaporation concentration crystallization device 14, and the acid and alkali regeneration liquid is 4% hydrochloric acid and 4% sodium hydroxide.

[0175] Preferably, the membrane materials of the high-pressure reverse osmosis membrane system and the low-pressure reverse osmosis membrane system are made of high molecular polymer materials. The main characteristics of the device are high anti-fouling, high pressure resistance, COD resistance, high ammonia nitrogen interception rate, etc., which have obvious application advantages over traditional RO membranes and avoid the problems of unqualified effluent ammonia nitrogen, low water recovery rate, and rapid membrane pollution.

[0176] Preferably, the filter elements of precision filter 1 and precision filter 2 are made of titanium-aluminum intermetallic compound with a precision of 0.1um;

[0177] Furthermore, when the precision filter 1 5 is backwashed, the backwash liquid returns to the primary fluorine removal coagulation sedimentation tank 4, when the precision filter 2 9 is backwashed, the backwash liquid returns to the chemical oxidation arsenic removal reaction tank 8, and when the ultrafiltration membrane clarification device 10 is backwashed, the backwash liquid returns to the precision filter 2 9.

[0178] Furthermore, the ultrafiltration membrane clarification device 10 filters and simultaneously inputs sodium bisulfite to reduce sodium hypochlorite.

[0179] Preferably, a NaOH solution is added to the deamination tower.

[0180] Preferably, the activated alumina is r-alumina.

[0181] More preferably, after the resin adsorption for weight removal reaches saturation, it is regenerated using 4% hydrochloric acid and 4% sodium hydroxide, and the regenerated waste salt solution is directly sent to the evaporation concentration crystallization device 14.

[0182] Example 4

[0183] like Figure 1As shown, a treatment system for reducing and solidifying the leachate of electrolytic aluminum slag for resource reuse comprises a pre-precipitation tank 1, a regulating tank 2, an aluminum hydroxide reaction precipitation tank 3, a primary defluorination coagulation precipitation tank 4, a precision filter 1 5, an activated alumina precision defluorination device 6, a two-stage oxidation cyanide breaking reaction tank 7, a chemical oxidation arsenic removal reaction tank 8, a precision filter 2 9, an ultrafiltration membrane clarification device 10, a resin weight removal device 11, a membrane concentration system 12, a deammoniation tower 13, and an evaporation concentration crystallization device 14, which are connected in sequence.

[0184] Among them, the above-mentioned aluminum hydroxide reaction sedimentation tank 3, primary fluoride removal coagulation sedimentation tank 4, and chemical oxidation arsenic removal reaction tank 8 are respectively connected to high-pressure sludge dewatering devices 15, and the primary fluoride removal coagulation sedimentation tank 4 and chemical oxidation arsenic removal reaction tank 8 share the same high-pressure sludge dewatering device 15.

[0185] The aluminum hydroxide reaction sedimentation tank 3 is connected to a hydrochloric acid pump 16 for pumping in hydrochloric acid for neutralization and hydrolysis, and the primary defluorination coagulation sedimentation tank 4 is connected to a calcium chloride and aluminum sulfate solution mixing pump 17 for pumping in a mixture of calcium chloride and aluminum sulfate solution for reaction with fluorine;

[0186] Further, the precision filter 1 5, the precision filter 2 9, and the ultrafiltration membrane clarification device 10 are respectively provided with backwash pumps;

[0187] like Figure 2 As shown, the pre-sedimentation tank 1, the aluminum hydroxide reaction sedimentation tank 3, and the primary defluorination coagulation sedimentation tank 4 all adopt two-stage inclined tube sedimentation tanks; the two-stage inclined tube sedimentation tanks include a primary sedimentation tank 101 and a secondary sedimentation tank 102, the primary sedimentation tank 101 is provided with a first liquid inlet 1011 and a first overflow port 1012, the secondary sedimentation tank 102 is provided with a second liquid inlet 1021 and a second overflow port 1022, the primary sedimentation tank 101 and the secondary sedimentation tank 102 are connected through the first overflow port 1012 and the second liquid inlet 1021, and the primary sedimentation tank 101 and the secondary sedimentation tank 102 are respectively provided with inclined tubes 103.

[0188] like Figure 3 As shown, the liquid inlet end of the two-stage inclined tube sedimentation tank corresponding to the primary defluorination coagulation sedimentation tank 4 is also provided with a primary defluorination device, and the primary defluorination device includes a primary dosing mixing zone 401 and a primary oxidation reaction zone 402 which are connected in sequence.

[0189] The first liquid inlet 1011 is located at the bottom of the primary sedimentation tank 101, the first overflow port 1012 is located at the top of the primary sedimentation tank 101, the second liquid inlet 1021 is located at the bottom of the secondary sedimentation tank 102, the second overflow port 1022 is located at the top of the secondary sedimentation tank 102, the first liquid inlet 1011 is connected to the water inlet 104, and the water inlet 104 is located at the top of the primary sedimentation tank 101.

[0190] like Figure 4As shown, the two-stage oxidation cyanide destruction reaction tank 7 includes a dosing mixing zone 701, a primary oxidation reaction zone 702 and a secondary oxidation reaction zone 703 which are connected in sequence, and a stirring device 704 is provided in the primary oxidation reaction zone 702 and the secondary oxidation reaction zone 703;

[0191] The dosing and mixing zone 701 is provided with an inlet 705 for water and a primary oxidizing agent, the primary oxidizing reaction zone 702 is provided with a primary oxidizing liquid inlet 7021 and a primary oxidizing overflow port 7022, and the secondary oxidizing reaction zone 703 is provided with a secondary oxidizing liquid inlet 7031, a secondary oxidizing overflow port 7032 and a secondary oxidizing agent inlet 7033;

[0192] The incoming water and primary oxidizing agent inlet 705 are located at the top of the dosing mixing zone 701; the primary oxidation liquid inlet 7021 is located at the bottom of the primary oxidation reaction zone 702, and the primary oxidation overflow port 7022 is located at the top of the primary oxidation reaction zone 702; the secondary oxidation liquid inlet 7031 is located at the bottom of the secondary oxidation reaction zone 703, the secondary oxidation overflow port 7032 is located at one end of the top of the secondary oxidation reaction zone 703, and the secondary oxidizing agent inlet 7033 is located at the other end of the top of the secondary oxidation reaction zone 703 and close to the secondary oxidation liquid inlet 7031.

[0193] A method for treating a certain electrolytic aluminum slag leachate by reducing and solidifying the leachate for resource reuse uses the treatment system for treating a certain electrolytic aluminum slag leachate by reducing and solidifying the leachate for resource reuse as described in the first aspect, and comprises the following steps:

[0194] 1) The electrolytic aluminum slag leachate is sent to the pre-precipitation tank 1 for precipitation, and the precipitated sludge is extracted and dehydrated from the V-shaped funnel at the bottom of the device, and stays for 0.8 hours, and the obtained supernatant is sent to the regulating tank 2;

[0195] 2) The supernatant after the pre-precipitation is stirred in the regulating tank 2, and after staying for 1.5 hours, it overflows into the aluminum hydroxide reaction precipitation tank 3;

[0196] 3) The overflow liquid of the regulating tank 2 reacts with hydrochloric acid in the aluminum hydroxide reaction sedimentation tank 3, the reaction time is 20 minutes, the reaction pH is controlled to be 7.5, the reaction molar ratio is: hydrochloric acid: aluminum>3:1, the suspended matter produced by the reaction is precipitated in the sedimentation tank of the aluminum hydroxide reaction sedimentation tank 3, the suspended matter settles to the V-type funnel, the sedimentation time is 1 hour, and the obtained supernatant overflows from the top overflow port;

[0197] 4) The supernatant overflowing from the aluminum hydroxide reaction sedimentation tank 3 is mixed with calcium chloride and aluminum sulfate solution and pumped into the primary defluorination coagulation sedimentation tank 4 by a pump, the reaction molar ratio is: calcium chloride: aluminum sulfate: fluorine> 1:2.5:1, the reaction time is 20 minutes, the reaction pH is 8.5, the liquid after the reaction enters the sedimentation tank of the primary defluorination coagulation sedimentation tank 4 for precipitation, and the suspended matter containing calcium fluoride and aluminum hydroxide colloid generated by the reaction is partially settled to the V-funnel in the two-stage inclined tube sedimentation tank of the primary defluorination coagulation sedimentation tank 4, the sedimentation time is 1.5 hours, and the supernatant obtained after precipitation flows out from the top overflow port;

[0198] 5) The overflow liquid of the primary defluorination coagulation sedimentation tank 4 is pumped into the precision filter 5 for filtration, and the filtrate with suspended matter less than 1 mg / L is obtained after filtration;

[0199] 6) The filtrate after passing through the precision filter 5 is pumped into the activated alumina precision defluorination device 6 for activated alumina adsorption defluorination, and after adsorption defluorination, wastewater with a fluorine content of 2-4 mg / L is obtained;

[0200] 7) Pumping the wastewater after adsorption and defluorination into the two-stage oxidation cyanide breaking reaction tank 7 for primary oxidation cyanide breaking and secondary oxidation cyanide breaking cyanide removal, the primary oxidation cyanide breaking is adjusted to pH=10, the primary oxidation cyanide breaking reaction molar ratio is: sodium hypochlorite: cyanide=10:1, after the primary oxidation cyanide breaking, it is connected to the secondary oxidation cyanide breaking reaction tank through the top overflow, the secondary oxidation cyanide breaking is adjusted to pH=8, the reaction molar ratio is: sodium hypochlorite: cyanide>2:1, after the two-stage oxidation cyanide breaking reaction time is 30min, a liquid with cyanide reduced to 0.5mg / L is obtained;

[0201] 8) The liquid after cyanide removal is sent to the chemical oxidation arsenic removal reaction tank 8 to add ferric chloride, and the mixture reacts to form a ferric arsenate suspension with extremely low solubility. The reaction molar ratio is: ferric chloride: arsenide> 1.5:1, the reaction time is 20 minutes, and the arsenide is reduced to 0.1 mg / L after chemical oxidation arsenic removal;

[0202] 9) filtering the liquid containing suspended matter obtained after arsenic removal through a precision filter 9 to obtain a filtrate with suspended matter less than 1 mg / L;

[0203] 10) The filtrate obtained by filtering the precision filter 29 is sent to the ultrafiltration membrane clarification device 10, the membrane pore size of the ultrafiltration membrane clarification device 10 is 150,000 Daltons, the operating pressure is 0.2Mpa, the operating temperature is 30°C, and the full amount filtration method is adopted. The filtrate is simultaneously reduced with sodium hypochlorite by sodium bisulfite to prevent oxidative damage to the membrane of the membrane concentration system 12 later, and the ultrafiltration filtrate is obtained after filtration;

[0204] 11) The ultrafiltration filtrate is pumped into the resin deweighting device 11 by a pump for deep adsorption of calcium, magnesium, aluminum and iron, and deweighted water with an ion concentration of less than 2 mg / L is obtained after adsorption;

[0205] 12) Pumping the deweighted water into the membrane concentration system 12 by a pump to concentrate and reduce the salt, first pumping it into the high-pressure reverse osmosis membrane system, and then entering the low-pressure reverse osmosis membrane system, concentrating the salt to a concentration of 9-10%, and the ammonia nitrogen to 2000mg / L, recycling the water, producing water to 50-100us / cm, and filtering a large amount of COD at the same time to make the COD content not exceed the standard, the operating pressure of the high-pressure reverse osmosis membrane system is 10MPa, the operating pressure of the low-pressure reverse osmosis membrane system is 2Mpa, the temperature is 30°C, and the pH is 6.8, and a membrane concentrated concentrate is obtained after membrane concentration;

[0206] 13) The concentrated solution after membrane concentration enters the deammonification tower 13 device for ammonia nitrogen recovery, and liquid alkali is added to react with ammonium in the solution to produce ammonia, and the ammonia is then volatilized to the top of the tower through steam heat transfer and overflowed. The overflowing ammonia gas is then condensed into ammonia water through a condensation device. The recovered ammonia water can reach a concentration of 15-20%, while the ammonia at the bottom of the kettle becomes less and less, and finally the ammonia nitrogen volatilizes to 15 mg / L and is discharged from the bottom of the kettle;

[0207] 14) The mother liquid at the bottom of the deamination tower is pumped into the evaporation concentration crystallization device 14 by a pump, and water and concentrated and solidified salt are obtained by evaporation. The evaporated water meets the standards for discharge or reuse, and the solidified salt is finally transported to a fixed place for rain shelter and stacked;

[0208] 15) The sludge precipitated at the bottom of the primary fluoride removal coagulation sedimentation tank 4 and the chemical oxidation arsenic removal reaction tank 8 is discharged into the same high-pressure sludge dehydration device 15 for dehydration, and the sludge precipitated at the bottom of the aluminum hydroxide reaction sedimentation tank 3 is discharged into another high-pressure sludge dehydration device 15 for dehydration. After the sludge at the bottom of the aluminum hydroxide reaction sedimentation tank 3 is dehydrated, aluminum hydroxide with a water content greater than 40% is obtained, and the aluminum hydroxide with a water content greater than 40% is sent to the aluminum hydroxide workshop.

[0209] Further, the sludge obtained by precipitation at the bottom of the aluminum hydroxide reaction sedimentation tank 3, the primary defluorination coagulation sedimentation tank 4 and the chemical oxidation arsenic removal reaction tank 8 is discharged into the high-pressure sludge dehydration device 15;

[0210] Preferably, the high-pressure sludge dewatering device 15 adopts a high-pressure plate and frame filter press, which can reduce the water content to 40-55%, with an operating pressure of 3Mpa and an operating time of 3h.

[0211] Further, when the activated alumina adsorption reaches the saturation concentration, a 3.5% aluminum sulfate solution is used to regenerate the activated alumina defluorinating agent, and the regenerated waste liquid is returned to the aluminum hydroxide reaction sedimentation tank 3;

[0212] Preferably, the resin of the resin weight removal device 11 is chelating resin, which has high weight removal accuracy, long resin life, and solves the scaling problem of iron, aluminum and calcium salts in the subsequent membrane system. When the resin adsorption reaches saturation, it is regenerated with acid and alkali regeneration liquid. The regenerated waste salt solution after regeneration is directly sent to the evaporation concentration crystallization device 14, and the acid and alkali regeneration liquid is 4% hydrochloric acid and 4% sodium hydroxide.

[0213] Preferably, the membrane materials of the high-pressure reverse osmosis membrane system and the low-pressure reverse osmosis membrane system are made of high molecular polymer materials. The main characteristics of the device are high anti-fouling, high pressure resistance, COD resistance, high ammonia nitrogen interception rate, etc., which have obvious application advantages over traditional RO membranes and avoid the problems of unqualified effluent ammonia nitrogen, low water recovery rate, and rapid membrane pollution.

[0214] Preferably, the filter elements of precision filter 1 and precision filter 2 are made of titanium-aluminum intermetallic compound with a precision of 0.3um;

[0215] Furthermore, when the precision filter 1 5 is backwashed, the backwash liquid returns to the primary fluorine removal coagulation sedimentation tank 4, when the precision filter 2 9 is backwashed, the backwash liquid returns to the chemical oxidation arsenic removal reaction tank 8, and when the ultrafiltration membrane clarification device 10 is backwashed, the backwash liquid returns to the precision filter 2 9.

[0216] Furthermore, the ultrafiltration membrane clarification device 10 filters and simultaneously inputs sodium bisulfite to reduce sodium hypochlorite.

[0217] Preferably, a NaOH solution is added to the deamination tower.

[0218] Preferably, the activated alumina is r-alumina.

[0219] More preferably, after the resin adsorption for weight removal reaches saturation, it is regenerated using 4% hydrochloric acid and 4% sodium hydroxide, and the regenerated waste salt solution is directly sent to the evaporation concentration crystallization device 14.

[0220] The above is only a preferred embodiment of the present invention. It should be understood that the present invention is not limited to the form disclosed herein, and should not be regarded as excluding other embodiments, but can be used in various other combinations, modifications and environments, and can be modified within the scope of the concept described herein through the above teachings or the technology or knowledge of the relevant field. The changes and modifications made by those skilled in the art shall not deviate from the spirit and scope of the present invention, and shall be within the scope of protection of the claims attached to the present invention.

Claims

1. A treatment system for reducing and solidifying the leachate of electrolytic aluminum slag for resource recycling, characterized in that: It comprises a pre-precipitation tank (1), a regulating tank (2), an aluminum hydroxide reaction precipitation tank (3), a primary defluorination coagulation precipitation tank (4), a precision filter 1 (5), an activated alumina precision defluorination device (6), a two-stage oxidation cyanide breaking reaction tank (7), a chemical oxidation arsenic removal reaction tank (8), a precision filter 2 (9), an ultrafiltration membrane clarification device (10), a resin weight removal device (11), a membrane concentration system (12), a deammoniation tower (13), and an evaporation concentration crystallization device (14) which are connected in sequence; The aluminum hydroxide reaction sedimentation tank (3), the primary fluorine removal coagulation sedimentation tank (4), and the chemical oxidation arsenic removal reaction tank (8) are respectively connected to high-pressure sludge dewatering devices (15), wherein the primary fluorine removal coagulation sedimentation tank (4) and the chemical oxidation arsenic removal reaction tank (8) share the same high-pressure sludge dewatering device (15), the aluminum hydroxide reaction sedimentation tank (3) is connected to another high-pressure sludge dewatering device (15), and the high-pressure sludge dewatering device (15) connected to the aluminum hydroxide reaction sedimentation tank (3) is connected to the aluminum hydroxide workshop.

2. The processing system for reducing and solidifying the electrolytic aluminum slag leachate for resource recycling according to claim 1 is characterized in that: The aluminum hydroxide reaction sedimentation tank (3) is connected to a hydrochloric acid pump (16) for pumping in hydrochloric acid for neutralization and hydrolysis; the primary defluorination coagulation sedimentation tank (4) is connected to a calcium chloride and aluminum sulfate solution mixing pump (17) for pumping in a mixture of calcium chloride and aluminum sulfate solution for reaction with fluorine; the precision filter 1 (5), the precision filter 2 (9), and the ultrafiltration membrane clarification device (10) are respectively provided with backwash pumps.

3. The processing system for reducing and solidifying the electrolytic aluminum slag leachate for resource reuse according to claim 2 is characterized in that: The pre-sedimentation tank (1), the aluminum hydroxide reaction sedimentation tank (3), and the primary defluorination coagulation sedimentation tank (4) all adopt two-stage inclined tube sedimentation tanks; the two-stage inclined tube sedimentation tanks include a primary sedimentation tank (101) and a secondary sedimentation tank (102); the primary sedimentation tank (101) is provided with a first liquid inlet (1011) and a first overflow port (1012); the secondary sedimentation tank (102) is provided with a second liquid inlet (1021) and a second overflow port (1022); the primary sedimentation tank (101) and the secondary sedimentation tank (102) are connected via the first overflow port (1012) and the second liquid inlet (1021); and the primary sedimentation tank (101) and the secondary sedimentation tank (102) are respectively provided with inclined tubes (103).

4. The processing system for reducing and solidifying the electrolytic aluminum slag leachate for resource recycling according to claim 3 is characterized in that: The liquid inlet end of the two-stage inclined tube sedimentation tank corresponding to the primary defluorination coagulation sedimentation tank (4) is also provided with a primary defluorination device, and the primary defluorination device comprises a primary dosing mixing zone (401) and a primary oxidation reaction zone (402) which are connected in sequence.

5. The processing system for reducing and solidifying the electrolytic aluminum slag leachate for resource recycling according to claim 4 is characterized in that: The two-stage oxidation cyanide destruction reaction pool (7) comprises a dosing mixing zone (701), a primary oxidation reaction zone (702) and a secondary oxidation reaction zone (703) which are connected in sequence, and a stirring device (704) is arranged in the primary oxidation reaction zone (702) and the secondary oxidation reaction zone (703).

6. A method for reducing and solidifying the leachate of electrolytic aluminum slag for resource reuse, characterized in that: A treatment system for reducing and solidifying the electrolytic aluminum slag leachate for resource recycling as claimed in any one of claims 1 to 5 is used, and comprises the following steps: S100: First, the electrolytic aluminum slag leachate is sent to the pre-precipitation tank (1) for precipitation, with a residence time of 0.5-1.0h, and the obtained supernatant is then sent to the regulating tank (2) for stirring and regulation, with a residence time of 1-2h, and after regulation, it overflows into the aluminum hydroxide reaction precipitation tank (3); S200: the overflow liquid of the regulating tank (2) reacts with hydrochloric acid in the aluminum hydroxide reaction sedimentation tank (3) for a reaction time of 10-30 minutes, and the suspended matter produced by the reaction is precipitated in the sedimentation tank of the aluminum hydroxide reaction sedimentation tank (3) for a sedimentation time of 0.5-2 hours, and the obtained supernatant overflows from the top overflow port; S300: the supernatant overflowing from the aluminum hydroxide reaction sedimentation tank (3) is mixed with calcium chloride and aluminum sulfate solution and pumped into the primary defluorination coagulation sedimentation tank (4), the reaction time is 10-30min, the reaction pH is 8-9, the liquid after the reaction enters the sedimentation tank of the primary defluorination coagulation sedimentation tank (4) for precipitation, the precipitation time is 0.5-2h, the supernatant obtained after precipitation enters the precision filter 1 (5) for filtration, and the filtrate is obtained after filtration; S400: pumping the filtrate from the precision filter 1 (5) into the activated alumina precision defluorination device (6) for defluorination by adsorption of activated alumina, and obtaining wastewater with a fluorine content of 2-4 mg / L after defluorination by adsorption; S500: pumping the wastewater after defluorination by adsorption into a two-stage oxidation cyanide breaking reaction tank (7) to perform primary oxidation cyanide breaking and secondary oxidation cyanide breaking to remove cyanide, wherein the primary oxidation cyanide breaking is adjusted to pH=10, and the secondary oxidation cyanide breaking is adjusted to pH=8, and the two-stage oxidation cyanide breaking reaction time is 30 minutes to obtain a liquid after decyanation; S600: sending the liquid after cyanide removal into a chemical oxidation arsenic removal reaction tank (8), adding ferric chloride, mixing and reacting, the reaction time is 30 minutes, and obtaining a liquid containing suspended matter, and sequentially sending the suspended matter into a second precision filter (9) and an ultrafiltration membrane clarification device (10) to obtain an ultrafiltration filtrate; S700: The ultrafiltration filtrate is pumped into a resin deweighting device (11) for deep adsorption of calcium, magnesium, aluminum and iron, and deweighted water with an ion concentration of less than 2 mg / L is obtained after adsorption. The deweighted water is then pumped into a membrane concentration system (12) for concentration and reduction of salt to obtain qualified water and membrane concentrated concentrate. The membrane concentrated concentrate is sent to a deammoniation tower (13), and liquid alkali is added for distillation to obtain 15-20% ammonia water and a mother liquor at the bottom of the deammoniation tower. The mother liquor at the bottom of the deammoniation tower is pumped into an evaporation concentration crystallization device (14), and evaporated to obtain qualified water and concentrated and solidified salt.

7. The method for reducing and solidifying the electrolytic aluminum slag leachate for resource reuse according to claim 6, characterized in that: The method also includes discharging the sludge obtained by precipitation at the bottom of the aluminum hydroxide reaction sedimentation tank (3), the primary fluoride removal coagulation sedimentation tank (4) and the chemical oxidation arsenic removal reaction tank (8) into a high-pressure sludge dehydration device (15), wherein the high-pressure sludge dehydration device (15) connected to the aluminum hydroxide reaction sedimentation tank (3) obtains aluminum hydroxide with a moisture content of more than 40% after dehydration, and the aluminum hydroxide with a moisture content of more than 40% is sent to an aluminum hydroxide workshop for recycling. The high-pressure sludge dehydration device (15) adopts a high-pressure plate and frame filter press with an operating pressure of 2-5Mpa and an operating time of 2-4h.

8. The method for reducing and solidifying the electrolytic aluminum slag leachate for resource reuse according to claim 7, characterized in that: The membrane concentration system (12) is composed of a special high-pressure reverse osmosis membrane system and a low-pressure reverse osmosis membrane system. The operating pressure of the high-pressure reverse osmosis membrane system is 8-12MPa, the temperature is 25-35°C, and the pH is 6.5-7. The operating pressure of the low-pressure reverse osmosis membrane system is 1.5-2.5MPa, the temperature is 25-35°C, and the pH is 6.5-7.

9. The method for reducing and solidifying the electrolytic aluminum slag leachate for resource reuse according to claim 8, characterized in that: When the activated alumina adsorption reaches the saturation concentration, a 3-4% aluminum sulfate solution is used to regenerate the activated alumina defluorinating agent, and the regenerated waste liquid is returned to the aluminum hydroxide reaction precipitation tank (3).

10. The method for reducing and solidifying the electrolytic aluminum slag leachate for resource reuse according to claim 9, characterized in that: After the resin adsorption of the resin deweighting device (11) reaches saturation, it is regenerated using acid and alkali regeneration liquid, and the regenerated waste salt solution is directly sent to the evaporation concentration crystallization device (14).

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