CN105384288B - A kind of processing system and method for being used for acid waste water in metallurgical off-gas acid-making - Google Patents

Abstract

The invention discloses a treatment system and method for acid waste water in acid production from smelting flue gas. Sodium sulfide solution and acid waste water are input into a primary reactor for reaction to remove part of heavy metals and arsenic in the acid water, and then enter a primary thickener. , Thickener sludge is reused after pressure filtration, the supernatant and filter press filtrate enter the secondary reactor, and the magnesia absorption liquid discharged after desulfurization in the smelting environmental protection gas collection system added to the secondary reactor and its configuration For a good magnesium oxide solution, use the smelting ring collection flue gas desulfurization absorption liquid containing magnesium oxide, magnesium sulfite and magnesium oxide solution to fully neutralize the sulfuric acid in the acid water, and then add aluminum salt to reduce the heavy metal content in the reaction solution Reduced to the control range, enter the secondary thickener, the sediment of the thickener is filtered and sent to the hazardous waste treatment site for landfill, and the supernatant and filter press filtrate are treated with hydroxyl iron co-precipitation method to reach the standard and then reused or discharged . Realize the treatment of waste by waste, with strong pertinence, reduce the operating cost of environmental protection facilities, and reduce the external discharge of the system.

Description

A treatment system and method for acidic wastewater from smelting flue gas acid production

technical field

The invention belongs to the field of chemical industry, and relates to wastewater treatment in nonferrous metal smelting, in particular to a treatment system and method for acid wastewater in smelting flue gas acid production.

Background technique

During the wet scrubbing process of smelting flue gas acid production, a large amount of acid wastewater containing heavy metals such as nickel, copper, lead, and harmful elements such as arsenic and fluorine is produced, which pollutes the environment and has always been a problem that plagues flue gas acid production. The existing treatment The process function is single, the processing process is cumbersome, and all bad parts cannot be linked together for comprehensive cycle processing.

Contents of the invention

The purpose of the present invention is to provide a method for neutralizing the acidic wastewater by using magnesium oxide desulfurization absorption liquid, and to carry out advanced treatment on the neutralized wastewater using the co-precipitation method of hydroxyl iron, so as to realize The treatment method of acid waste water up to standard discharge.

The purpose of the present invention is achieved in the following manner: a treatment system for acid waste water in acid production from smelting flue gas, the output end of the acid water delivery pump for transporting acid waste water, and the sodium sulfide connected to the sodium sulfide storage tank The output ends of the pumps are all connected to the inlet of the first-stage reactor, the outlet of the first-stage reactor is connected to the inlet of the first-stage thickener through the pumping pipeline, and the bottom flow port of the first-stage thickener is connected to the inlet of the first filter press. They are connected by pumping pipelines, the overflow port of the primary thickener is connected with the inlet of the first clear liquid storage tank through pipelines, the first clear liquid storage tank, magnesium oxide solution storage tank, ferrous sulfate storage tank The outlets of the storage tank, aluminum salt storage tank, and absorption liquid storage tank are all connected to the inlet of the secondary reactor through pipelines, and the outlet of the secondary reactor is connected to the inlet of the secondary thickener through pumping pipelines. The top of the thickener is provided with a flocculant storage tank and communicates with it through the pipeline. The bottom outlet of the secondary thickener is connected to the inlet of the second filter press through the pumping pipeline, and the overflow port of the secondary thickener is connected through the pipeline. It is connected to the inlet of the second clear liquid storage tank, and the outlet of the second clear liquid storage tank is connected to the inlet of the regulating tank through the pumping pipeline. The road is connected, the wastewater in the primary aeration tank is aerated by the first blower, the first hydroxyl iron storage tank is arranged above the primary reaction tank and communicated with it through the pipeline, and the outlet of the primary reaction tank passes through The pumping pipeline is connected to the inlet of the third-stage thickener, the bottom outlet of the third-stage thickener is connected to the inlet of the third filter press through the pumping pipeline, and the overflow port of the third-stage thickener is connected to the second-stage thickener through the pipeline. The inlets of the aeration tanks are connected, and the waste water in the secondary aeration tanks is aerated by the second blower. The outlet of the secondary aeration tanks is connected to the inlet of the secondary reaction tanks through pumping pipelines. The second hydroxyl iron storage tank on the top of the tank is connected with it through the pipeline, the outlet of the secondary reaction tank is connected with the inlet of the fourth-stage thickener through the pumping pipeline, and the bottom flow port of the fourth-stage thickener is connected with the third filter press. The inlets are connected, and the filtrate outlet of the third filter press is led to the regulating tank through the pipeline.

A method for treating acidic waste water in smelting flue gas acid production using the above system, specifically comprising the following steps:

A. Send the acidic wastewater and sodium sulfide solution into the primary reactor for sulfidation reaction to remove some nickel, copper, lead heavy metals and arsenic in the acidic wastewater. The reaction solution is sent to the primary thickener for concentration and precipitation, and the underflow is sent to The first filter press presses the filter, and the filter residue is recycled;

B. The overflow supernatant of the primary thickener and the filtrate of the first filter press are sent to the secondary reactor, and the absorption liquid and magnesium oxide solution sent to the secondary reactor are neutralized, and then sulfurous acid is added The iron and aluminum salts react with the heavy metal ions in the reaction solution, and then the reaction solution is sent to the secondary thickener, and at the same time, the flocculant is added to concentrate and precipitate, and the underflow is sent to the second filter press for pressure filtration, and the filter residue is sent to hazardous waste treatment The supernatant of the secondary thickener and the filtrate of the second filter press enter the second clear liquid storage tank;

C. Part of the supernatant in the second clear liquid storage tank is sent to the regulating tank, and the wastewater in the regulating tank is sent to the primary aeration tank with the first delivery pump, and the wastewater in the primary aeration tank is aerated by the blower. After aeration, it is sent into the primary reaction tank by the second delivery pump, and the hydroxyl iron in the hydroxyl iron storage tank is added to the primary reaction tank, and the hydroxyl iron and the impurities in the wastewater of the primary reaction tank undergo adsorption complexation and ion exchange , Co-precipitation and lattice substitution reaction. After the reaction, the third conveying pump is sent to the third-stage thickener for concentration and precipitation. The filtrate of the third filter press is returned to the adjustment tank, and the filter residue of the third filter press is recycled;

D. The overflow supernatant of the third-stage thickener enters the secondary aeration tank, and the second blower aerates the wastewater in the second-stage aeration tank. After aeration, it is sent into the secondary reaction tank by the fourth delivery pump , add the hydroxyl iron agent in the hydroxyl iron storage tank to the secondary reaction tank, and the hydroxyl iron agent and the impurities in the secondary reaction tank wastewater undergo adsorption complexation, ion exchange, encapsulation co-precipitation and lattice substitution reaction again. After the reaction, Use the fifth conveying pump to send to the fourth-stage thickener for secondary concentration and precipitation, the bottom flow of the fourth-stage thickener is sent to the third filter press through the fourth filter press pump, and the filtered filtrate is returned to the adjustment tank. The filter residue of the third filter press is recycled and reused. After further removal of metal and arsenic pollutants in the wastewater, the overflow supernatant of the fourth-stage thickener is used up to the standard or discharged.

Wherein, the remaining part of the supernatant in the above-mentioned second liquid storage tank is used to configure magnesium oxide desulfurization absorption liquid or to prepare sodium sulfide solution.

The beneficial effects of the present invention are as follows: the present invention treats the flue gas from the smelting ring by the magnesium oxide desulfurization process, and the generated absorption liquid contains magnesium oxide and magnesium sulfite, which is neutralized and reused with acid waste water, and the neutralized The wastewater is treated in an advanced manner using the hydroxyl iron co-precipitation method to achieve the discharge of acidic wastewater up to standard. In the treatment process, the present invention enters the sodium sulfide solution and acid wastewater into the first-stage reactor to react to remove part of the heavy metals and arsenic in the acid water, and then enters the first-stage thickener. The machine filtrate enters the secondary reactor, and the magnesia absorption liquid and the prepared magnesia solution discharged after desulfurization in the smelting environmental protection gas collection system added to the secondary reactor are used to use the smelting ring collection flue gas desulfurization absorption liquid containing oxidation Magnesium, magnesium sulfite and magnesium oxide solution are fully neutralized with sulfuric acid in acid water, and then aluminum salt is added to reduce the amount of heavy metals in the reaction solution to the control range, and then enter the secondary thickener, and the sediment of the thickener is filtered Afterwards, it is sent to the hazardous waste treatment site for landfill, and the supernatant and filter press filtrate are treated with hydroxyl iron co-precipitation method to reach the standard and then reused or discharged. The treatment process of the invention realizes treating waste with waste, has strong pertinence, reduces the operating cost of environmental protection facilities, reduces the discharge volume outside the system, and achieves the reuse or discharge of acid waste water up to the standard.

Description of drawings

Fig. 1 is a schematic diagram of the process flow of the present invention.

In the figure: 1 acid water delivery pump; 2 sodium sulfide storage tank; 3 sodium sulfide pump; 4 primary reactor; 5 primary reaction liquid delivery pump; 6 primary thickener; 7 first filter press pump; 8 first Clear liquid storage tank; 9 the first clear liquid pump; 10 the first filter press; 11 the filter residue of the first filter press; 12 magnesium oxide solution storage tank; 13 ferrous sulfate storage tank; 14 aluminum salt storage tank; 15 flocculant Storage tank; 16 Absorption liquid storage tank; 17 Absorption liquid transfer pump; 18 Secondary reactor; 19 Secondary reaction liquid transfer pump; 20 Secondary thickener; 21 Second filter press pump; 22 Second clear liquid storage tank; 23 second clear liquid pump; 24 second filter press; 25 second filter press residue; 26 first air blower; 27 first hydroxyl iron storage tank; 28 gas storage tank; 31 first-level aeration tank; 32 second delivery pump; 33 first-level reaction tank; 34 third delivery pump; 35 third-level thickener; 36 third filter press pump; 37 third press filter; 38 third press filter Machine filter residue; 39 the second blower; 40 the second hydroxyl iron storage tank; 41 the second aeration tank; 42 the fourth delivery pump, 43 the second reaction tank; 44 the fifth delivery pump, 45 the fourth thickener; 46 the fourth Filter press pump; 47 four-stage thickener supernatant.

detailed description

A treatment system for acidic wastewater: the output end of the acid water delivery pump 1 for transporting acidic wastewater and the output end of the sodium sulfide pump 3 connected to the sodium sulfide storage tank 2 are all connected to the inlet of the primary reactor 4 through a pipeline Then, the outlet of the first-stage reactor 4 is connected to the inlet of the first-stage thickener 6 through the pumping pipeline of the first-stage reaction liquid delivery pump 5, and the bottom outlet of the first-stage thickener 6 is connected to the inlet of the first filter press 10. The pumping pipeline of the first filter press pump 7 is connected between them, the overflow port of the primary thickener 6 is connected with the inlet of the first clear liquid storage tank 8 through the pipeline, the first clear liquid storage tank 8, the oxidation The magnesium solution storage tank 12, the ferrous sulfate storage tank 13, and the aluminum salt storage tank 14 are all connected to the inlet of the secondary reactor 18 through pipelines, and the absorption liquid storage tank 16 transports the absorption liquid to the secondary stage through the absorption liquid delivery pump 17 In the reactor 18, the outlet of the secondary reactor 18 is connected to the inlet of the secondary thickener 20 through the pumping pipeline of the secondary reaction liquid delivery pump 19, and a flocculant storage tank 15 is arranged above the secondary thickener 20 And communicate with it through the pipeline, the bottom outlet of the secondary thickener 20 is connected to the inlet of the second filter press 24 through the pumping pipeline of the second filter press pump 21, and the overflow port of the secondary thickener 20 passes through the pipeline It is connected to the inlet of the second clear liquid storage tank 22, and the outlet of the second clear liquid storage tank 22 is connected to the inlet of the regulating tank 29 through the pumping pipeline of the second clear liquid pump 23, and the outlet of the regulating tank 29 passes through the first delivery pump The pumping pipeline of 30 is connected with the inlet of the primary aeration tank 31, the outlet of the primary aeration tank 31 is connected with the inlet of the primary reaction tank 33 through the pumping pipeline of the second delivery pump 32, and the primary aeration tank The waste water in 31 is aerated by the first blower 26, the first hydroxyl iron storage tank 27 is arranged above the primary reaction pool 33 and communicates with it through the pipeline, and the outlet of the primary reaction pool 33 passes through the third delivery pump 34 The pumping pipeline of the three-stage thickener is connected with the inlet of the three-stage thickener 35, and the bottom flow port of the three-stage thickener 35 is connected with the inlet of the third filter press 37 through the pumping pipeline of the third filter press pump 36, and the three-stage thickener The overflow port of the machine 35 is connected with the entrance of the secondary aeration tank 41 through the pipeline, the waste water in the secondary aeration tank 41 is aerated by the second blower 39, and the outlet of the secondary aeration tank 41 is passed through the second blower 39. The pumping pipeline of the four delivery pumps 42 is connected with the entrance of the secondary reaction pool 43, the second hydroxyl iron storage tank 40 above the secondary reaction pool 43 communicates with it through the pipeline, and the outlet of the secondary reaction pool 43 passes through the fifth The pumping pipeline of the delivery pump 44 is connected to the inlet of the fourth-stage thickener 45, and the bottom flow port of the fourth-stage thickener 45 is connected to the inlet of the third filter press 37 through the pumping pipeline of the fourth filter press pump 46. The filtrate outlet of the third filter press 37 leads to the regulating tank 29 through a pipeline.

Send the acidic waste water and sodium sulfide solution into the primary reactor for sulfidation reaction to remove some heavy metals such as nickel, copper, lead and arsenic in the acid water. The reaction solution is sent to the primary thickener for concentration and precipitation, and the underflow is sent to the filter press press filter, filter residue is recycled, the thickener overflow supernatant and filter press filtrate are sent to the secondary reactor, and the absorption liquid and magnesium oxide solution are sent to the secondary reactor for neutralization reaction, and the pH is adjusted. After reaching the appropriate range, add ferrous sulfate and aluminum salt, and when the total amount of heavy metals in the reaction solution drops to the control range, send the reaction solution to the secondary thickener, add flocculant at the same time to concentrate and precipitate, and the bottom flow is sent to the secondary thickener. The filter residue is sent to the hazardous waste treatment site for landfill, the supernatant of the thickener and the filtrate of the filter press enter the clear liquid storage tank, and part of the wastewater after two-stage neutralization is returned to the smelting environmental protection gas collection system Continue to configure the absorption solution and sodium sulfide solution, and part of it enters the hydroxyl iron co-precipitation treatment process for advanced treatment, and adds active iron-based chemicals to the primary and secondary treatment wastewater, and the chemicals and impurities in the wastewater undergo adsorption complexation, ion exchange, Encapsulation co-precipitation and lattice substitution, etc., realize the simultaneous removal of various heavy metals, arsenic and other pollutants, achieve the purpose of deep removal of metals, arsenic and other pollutants in wastewater, and discharge wastewater up to standard.

Example

A flue gas treatment of low-concentration sulfur dioxide smelting ring: adding magnesium oxide to the magnesium oxide preparation tank for preparation, after preparation, it is sent to the magnesium oxide slurry tank for slurry by a delivery pump, and after the slurry is completed, it is sent into the magnesium oxide slurry tank by a delivery pump The magnesium oxide slurry storage tank, the magnesium oxide slurry is sent to the absorption tower for desulfurization through the delivery pump, the fan sends the ring-collected flue gas generated by smelting to the absorption tower, and the circulation pump is turned on to send the magnesium oxide absorption liquid to the absorption tower spray device, and the absorption liquid Spray down from the spray device, contact with the flue gas from bottom to top in the absorption tower, and absorb the flue gas. After the dust removal reaches the standard, it is emptied through the chimney; after the magnesium oxide absorption liquid is recycled, it is sent to the absorption liquid storage tank 16 through the absorption liquid delivery pump, and is pumped into the secondary reactor 18 through the absorption liquid delivery pump 17 for acid water neutralization. .

The technological process of the present invention is described further with reference to Fig. 1:

Treatment of acidic wastewater: send the acidic wastewater into the primary reactor 4 with the acid water delivery pump 1, and the sodium sulfide pump 3 sends the sodium sulfide solution in the sodium sulfide storage tank 2 into the primary reactor 4 for sulfidation reaction, removing Some nickel, copper, lead and other heavy metals and arsenic in the acid water, after the reaction, use the primary reaction liquid delivery pump 5 to send the reaction liquid to the primary thickener 6 for concentration and precipitation, and the bottom of the thickener flows through the first filter press pump 7 Sent to the first filter press 10 for pressure filtration, the filter residue 11 of the first filter press is recycled, the supernatant from the overflow of the primary thickener 6 and the filter press filtrate enter the first clear liquid storage tank 8, and pass through the first clear liquid The pump 9 sends the clear liquid into the secondary reactor, and the absorption liquid delivery pump 17 sends the absorption liquid in the absorption liquid storage tank 16 and the magnesium oxide solution in the magnesium oxide solution storage tank 12 to the secondary reactor and the clear liquid pump 9 The clear liquid that sends in carries out neutralization reaction, and after fully reacting, after pH is adjusted to 7-8, add the ferrous sulfate in the ferrous sulfate storage tank 13 and the aluminum salt in the aluminum salt storage tank 14, the After the total amount of heavy metals dropped to 100mg/L, the reaction liquid is sent to the secondary thickener 20 with the secondary reaction liquid delivery pump 19, and at the same time, the flocculant is added from the flocculant storage tank 15 to concentrate and settle, and the secondary thickener The bottom flow is sent to the second filter press 24 for press filtration through the second filter press pump 21, the filter residue 25 of the second filter press is sent to the hazardous waste treatment site for landfill, the overflow supernatant of the secondary thickener 20 and the second filter press The machine filtrate enters the second clear liquid storage tank 22, and a part of the supernatant is returned to the smelting environmental protection gas collection system to continue to configure magnesium oxide absorption liquid and sodium sulfide solution, and the remaining part of the supernatant is sent to the regulating tank through the second clear liquid pump 23 In 29, the waste water is sent into the primary aeration tank 31 with the first delivery pump 30, and the waste water in the primary aeration tank 31 is aerated by the first air blower 26. After aeration, the waste water is sent into the primary aeration tank 31 with the second delivery pump 32 In the first reaction tank 33, hydroxy iron is added through the first hydroxy iron storage tank 27, and the impurities in the hydroxy iron and waste water undergo adsorption complexation, ion exchange, co-precipitation and lattice substitution. After the reaction, the third delivery pump 34 After being sent to the three-stage thickener 35 for concentration and precipitation, the bottom flow of the three-stage thickener is sent to the third filter press 37 for pressure filtration through the third filter press pump 36, and the third filter press filtrate is returned to the regulating tank 29, and the third The filter residue 38 of the filter press is recycled, the overflow supernatant of the third-stage thickener 35 enters the secondary aeration tank 41, and the waste water of the secondary aeration tank 41 is aerated twice by the second air blower 39. After aeration, use The fourth delivery pump 42 is sent to the secondary reaction tank 43, and the hydroxyl iron agent is added through the second hydroxyl iron storage tank 40, and the hydroxyl iron agent and the impurities in the wastewater undergo adsorption complexation, ion exchange, co-precipitation and lattice substitution again. After the reaction, the fifth delivery pump 44 is used to send to the fourth-stage thickener 45 for secondary concentration and precipitation, and the bottom flow of the thickener is sent to the third filter press 37 for pressure filtration through the fourth filter press pump 46. The filter press filtrate is returned to the regulating tank 29, and the filter residue 38 of the third filter press is recycled. After further removing pollutants such as metals and arsenic in the waste water, the fourth-stage thickener supernatant 47 overflowing from the fourth-stage thickener 45 reaches the standard for utilization or Efflux.

Claims (3)

1. A treatment system for acidic wastewater in smelting flue gas acid production, characterized in that: the output end of the acid water delivery pump (1) for transporting acidic wastewater, and the sulfide pump connected to the sodium sulfide storage tank (2) The output ends of the sodium pump (3) are all connected to the inlet of the primary reactor (4), and the outlet of the primary reactor (4) is connected to the inlet of the primary thickener (6) through the pumping pipeline. The underflow port of the thickener (6) is connected to the inlet of the first filter press (10) through a pumping pipeline, and the overflow port of the primary thickener (6) is connected to the first liquid storage tank (8) The inlets are connected by pipelines, the first clear liquid storage tank (8), magnesium oxide solution storage tank (12), ferrous sulfate storage tank (13), aluminum salt storage tank (14), used to recover and discharge after desulfurization The outlet of the absorption solution storage tank (16) of the magnesium oxide waste liquid is connected with the inlet of the secondary reactor (18) through pipelines, and the outlet of the secondary reactor (18) is connected with the secondary thickener through a pumping pipeline. The inlet of the two-stage thickener (20) is connected, and the flocculant storage tank (15) is provided above the secondary thickener (20) and communicated with it through the pipeline. The bottom flow port of the secondary thickener (20) is connected to the The inlet of the second filter press (24) is connected, the overflow port of the secondary thickener (20) is connected with the inlet of the second clear liquid storage tank (22) through a pipeline, and the outlet of the second clear liquid storage tank (22) The pumping pipeline is connected to the inlet of the regulating tank (29), and the regulating tank (29), the primary aeration tank (31), and the primary reaction tank (33) are respectively connected through pumping pipelines in sequence, The wastewater in the primary aeration tank (31) is aerated by the first blower (26), and the first hydroxyl iron storage tank (27) is arranged above the primary reaction tank (33) and communicated with it through pipelines, The outlet of the first-stage reaction tank (33) is connected to the inlet of the third-stage thickener (35) through the pumping pipeline, and the bottom outlet of the third-stage thickener (35) is connected to the third filter press (37) through the pumping pipeline. ) inlet, the overflow port of the third-stage thickener (35) is connected to the inlet of the second-stage aeration tank (41) through the pipeline, and the waste water in the second-stage aeration tank (41) passes through the second blower (39) It is aerated, the outlet of the secondary aeration tank (41) is connected to the inlet of the secondary reaction tank (43) through a pumping pipeline, and the second hydroxyl iron storage tank (40) above the secondary reaction tank (43) ) and communicate with it through the pipeline, the outlet of the secondary reaction tank (43) is connected to the inlet of the fourth-stage thickener (45) through the pumping pipeline, and the bottom flow port of the fourth-stage thickener (45) is connected to the third pressure filter The inlet of the filter press (37) is connected, and the filtrate outlet of the third filter press (37) is passed to the regulating tank (29) through a pipeline. 2. A method for treating acidic waste water in acid production from smelting flue gas utilizing the system as claimed in claim 1, characterized in that: specifically comprising the following steps: A. Send the acidic wastewater and sodium sulfide solution into the primary reactor (4) for sulfidation reaction to remove part of the nickel, copper, lead heavy metals and arsenic in the acidic wastewater, and send the reaction solution to the primary thickener (6) for concentration , sedimentation, and the underflow is sent to the first filter press (10) for pressure filtration, and the filter residue is recycled; B. The overflow supernatant of the primary thickener (6) and the filtrate of the first filter press (10) are sent to the secondary reactor (18), and the absorption liquid and the The magnesium oxide solution is neutralized, and the absorption liquid is the waste liquid containing magnesium oxide that is sent out from the absorption liquid storage tank (16) and discharged after desulfurization, and then ferrous sulfate and aluminum salt are added to react with the heavy metal ions in the reaction liquid , the reaction solution is sent to the secondary thickener (20), and at the same time, flocculant is added to concentrate and precipitate, and the underflow is sent to the second filter press (24) for pressure filtration, and the filter residue is sent to the hazardous waste treatment site for landfill, and the secondary thickener (20) The supernatant and the filtrate of the second filter press (24) enter the second clear liquid storage tank (22); C. Part of the supernatant in the second clear liquid storage tank (22) is sent to the regulating tank (29), and the waste water in the regulating tank (29) is sent to the primary aeration tank ( 31), the waste water in the primary aeration tank (31) is aerated by the blower (26), after aeration, it is sent into the primary reaction tank (33) by the second delivery pump (32), and in the primary reaction tank ( 33) is added to the hydroxyl iron in the hydroxyl iron storage tank (27), and the hydroxyl iron and the impurities in the primary reaction tank (33) undergo adsorption complexation, ion exchange, co-precipitation and lattice substitution reactions. After the reaction, After the third delivery pump (34) is sent to the third-stage thickener (35) for concentration and precipitation, the bottom flow of the third-stage thickener is sent to the third filter press (37) for pressure filtration through the third filter press pump (36). The filtrate of the third filter press (37) is returned to the regulating tank (29), and the filter residue (38) of the third filter press is recycled; D. The overflow supernatant of the third-stage thickener (35) enters the secondary aeration tank (41), and the second blower (39) performs secondary aeration on the waste water of the secondary aeration tank (41). After aeration , sent into the secondary reaction tank (43) with the fourth transfer pump (42), and the hydroxyiron medicament in the hydroxyiron storage tank (40) was added in the secondary reaction tank (43), and the hydroxyiron medicament and the secondary reaction tank ( 43) Impurities in wastewater undergo adsorption complexation, ion exchange, co-precipitation and lattice substitution reactions again. After the reaction, the fifth delivery pump (44) is used to send them to the fourth-stage thickener (45) for secondary concentration and precipitation Finally, the bottom flow of the four-stage thickener is sent to the third filter press (37) for press filtration through the fourth filter press pump (46), and the filtrate after the press filter is returned to the adjustment tank (29), and the filter residue of the third filter press (38 ) recycling, after further removing metal and arsenic pollutants in the waste water, the overflow supernatant (47) of the four-stage thickener (45) can be used up to the standard or discharged. 3. A method for treating acidic wastewater in acid production from smelting flue gas according to claim 2, characterized in that: the remaining part of the supernatant in the second clear liquid storage tank (22) is used to configure magnesium oxide Absorption solution or used to prepare sodium sulfide solution.