Method for treating high-arsenic waste acid by using pyrite reinforced by cooperation of ultrasonic waves and superconducting high-intensity magnetic field

Abstract

The invention provides a method for treating high-arsenic waste acid by using pyrite reinforced by ultrasonic waves and a superconducting high-intensity magnetic field, and relates to the technical field of heavy metal pollution treatment. The method comprises the following steps: levigating pyrite, reacting with waste acid under the action of ultrasonic waves to form arsenic sulfide precipitate, carrying out solid-liquid separation, introducing air into a separated solution, controlling the pH value of the solution, introducing into a superconductive strong magnetic field to carry out arsenic precipitation reaction of iron arsenate, adding lime milk into treated water, controlling the pH value of the solution at 8-12, and carrying out solid-liquid separation to obtain the arsenic-arsenic-containing pyrite. And finally, deeply purified water and refined gypsum products discharged industrially are obtained. The method for treating the high-arsenic waste acid by introducing the external field reinforced pyrite has the advantages of being easy to operate, low in operation cost, short in treatment period, small in slag production amount, remarkable in arsenic removal effect and the like, and the purity gt of CaSO4 is obtained; and 96% of refined gypsum products. According to the method, waste acid treatment is achieved to the maximum extent, meanwhile, valuable components are recycled, and extra economic benefits are brought to enterprises.

Description

Technical Field

[0001] The invention relates to the technical field of heavy metal pollution control, in particular to a method for treating high-arsenic polluted acid by strengthening pyrite with ultrasonic wave and superconducting strong magnetic field. Background Art

[0002] High arsenic waste acid mainly comes from arsenic acid wastewater in the flue gas washing and purification process before the enrichment of aqueous solution in the non-ferrous metal (Cu, Pb, Zn, Ni and Sn, etc.) smelting process. The arsenic concentration in the waste acid is as high as 0.5-30g / L, the sulfuric acid concentration is as high as 10-200g / L, and it contains a variety of heavy metal elements such as Cu, Pb, Zn and Sb. It has the characteristics of complex composition, strong toxicity, large emission and difficulty in disposal. It is an important pollution source of non-ferrous metal smelting. If arsenic-containing waste acid leaks or is discharged at will, it will cause serious harm to the ecological environment and human safety. Arsenic can enter the human body through various channels, such as air breathing, drinking water and food chain. When arsenic enters the body, it is easy to combine with -SH to form a stable complex. The generated complex will hinder cell respiration, affect cell metabolism, and inhibit the synthesis and action of various enzymes in the body, which will cause organ lesions in the body. Long-term exposure to an arsenic-containing environment can cause skin, liver and other cancers. Once the arsenic content ingested by the human body is excessive, it will cause varying degrees of damage to the body.

[0003] At present, the main methods for treating high-arsenic waste acid are lime-iron salt method, sulfidation method, scorodite precipitation method and evaporation concentration method. The lime-iron salt method is to first add lime milk to the high-arsenic waste acid to adjust the solution pH to 10-11, use calcium ions to react with arsenite ions and arsenate ions to generate calcium arsenite and calcium arsenate salt precipitates, then introduce air to oxidize the residual arsenite ions in the waste acid to arsenate ions, and finally add iron salt coagulant to remove the residual arsenic in the form of precipitation. The process of this method is simple, has strong adaptability to waste acid with different arsenic concentrations, and has a significant arsenic removal effect. However, since the waste acid contains a large amount of sulfate ions, the lime milk first neutralizes and precipitates with sulfate ions during the arsenic removal process of this method, and then combines with arsenate ions and arsenite ions, resulting in a large amount of sludge. The arsenate in the sludge has poor stability and high solubility, and is easily released into the environment to cause secondary pollution. In addition, the direct oxidation rate of arsenite ions by air is slow and the effect and dosage of iron salt coagulant are high. The sulfidation method is to add a sulfiding agent to the high-arsenic waste acid to react and generate an insoluble and stable arsenic sulfide precipitate. At the same time, the heavy metal ions in the solution react with the sulfiding agent to form a sulfide precipitate with a small solubility product, and finally remove the arsenic and heavy metal ions in the solution by solid-liquid separation. The sulfidation method has the advantages of simple process operation, small amount of arsenic sulfide slag and low water content, the sulfidation arsenic removal process is not affected by the solution pH, and the clean water recovery rate is high. However, the cost of sulfide reagents is high, and the surface of arsenic sulfide slag is easy to adsorb arsenic ions and needs to be safely stored; in addition, the solution after sulfidation arsenic removal needs further neutralization treatment, which will produce a large amount of neutralization slag solid waste. The scorodite precipitation method is to add an iron source to the high-arsenic waste acid under specific conditions to form a highly stable scorodite precipitate. The solid arsenic carrier has an arsenic content of up to 23%, and has the advantages of low iron source consumption and small amount of slag during the synthesis process. However, the synthesis process of scorodite requires a specific environment, such as a suitable solution pH and Fe / As molar ratio, a higher reaction temperature environment and a longer arsenic precipitation cycle, which seriously limit the industrial application of the scorodite precipitation method. The evaporation concentration method is a method of reducing the amount of waste acid solution by heating and evaporating high-arsenic waste acid and crystallizing it. This method can effectively reduce the amount of waste acid solution and recover valuable substances such as sulfuric acid and heavy metals, but it has high energy consumption and serious corrosion to equipment, making it difficult to promote and apply. Therefore, in view of the characteristics of high-arsenic waste acid in non-ferrous smelting, such as large output, strong toxicity, and high acid content, it is urgent to develop a set of key technologies that are simple to operate, low in operating cost, low in slag production, significant in arsenic removal effect, and can effectively recover valuable sulfate ions in waste acid.

[0004] Chinese invention patent CN108793583B discloses a method for treating wastewater containing trivalent arsenic by using microorganisms and pyrite. Ferrous salts and pyrite are added to the wastewater containing trivalent arsenic to be treated, and iron oxidizing bacteria in the logarithmic growth phase are added at the same time. After adjusting the pH value and reaction temperature, the wastewater is placed in a shaker for reaction for 3 to 5 days, and then separated and precipitated after standing. The invention involves the synergistic removal of arsenic by microorganisms and pyrite, which is complicated to operate and has a long disposal cycle. In addition, the use of ferrous salts is costly and does not promote industrialization.

[0005] Chinese invention patent CN113683150B discloses a method for removing arsenic from copper smelting wastewater using a zinc slag / pyrite composite treatment agent, wherein zinc slag and pyrite are mixed and ball-milled in a mass ratio of (1-3):1 to obtain a composite treatment agent, which is then added to arsenic-containing copper smelting wastewater and stirred for 4-6 hours to remove arsenic. The invention uses zinc slag as the main component of the composite treatment agent, which will introduce new heavy metal impurities into the waste acid and increase the negative end of the back-end treatment. In addition, the alkaline oxides in the zinc slag will increase the pH of the solution, which is not conducive to the precipitation of As2S3 and causes a waste of sulfate ions in the solution.

[0006] Chinese invention patent CN111003864B discloses a method for removing arsenic from waste acid by ultrasonic enhancement. First, the waste acid is preheated to 35°C, then a certain amount of hot iron powder (temperature: 35-80°C) and copper sulfate solution are added, and finally ultrasonic enhancement reaction is introduced to remove arsenic. In this invention, the metal iron powder needs to be preheated, which not only consumes a lot of energy but also has certain risks in operation. In addition, the use of pure chemical reagent iron powder and copper sulfate solution is costly and introduces new heavy metal impurities.

[0007] In summary, the existing high-arsenic contaminated acid treatment technology has problems such as complex operation, long reaction cycle, large amount of chemical reagents and slag, and high operating cost. Summary of the invention

[0008] In order to solve the above technical problems existing in the prior art, the embodiment of the present invention provides a method for treating high-arsenic acid contaminated by pyrite by using ultrasonic waves in combination with a strong superconducting magnetic field. This method uses ultrasonic waves in combination with a strong superconducting magnetic field to treat high-arsenic acid contaminated by pyrite for the first time, and combines multi-factor experiments to optimize the performance of field-assisted arsenic removal from pyrite and the preparation of refined gypsum products, comprehensively expanding its scene adaptability, and providing a method for the treatment of high-arsenic acid contaminated by non-ferrous smelting industry with simple operation, low operating cost, and significant arsenic removal effect.

[0009] The technical solution is as follows:

[0010] A method for treating high-arsenic contaminated acid with pyrite by using ultrasonic waves in combination with a superconducting strong magnetic field, the method comprising:

[0011] S1, crushing and grinding pyrite to obtain a pyrite arsenic precipitating agent;

[0012] S2, adding an arsenic precipitant to the waste acid and performing ultrasonic reaction while stirring until arsenic sulfide precipitate is generated, and performing solid-liquid separation on the reactants to obtain arsenic sulfide precipitate and separation liquid;

[0013] S3, introducing air into the separation liquid and controlling the pH value of the separation liquid to be 0.5-3.5, generating ferric arsenate and obtaining a solid-liquid mixture;

[0014] S4, placing the solid-liquid mixture obtained in step S3 in a superconducting strong magnetic field and continuing to introduce air for oxidation reaction, so that the arsenite ions / Fe in the solid-liquid mixture 2+ Rapid oxidation reaction occurs with O2 in the air, accelerating the reaction of arsenate ions with Fe 3+ generating ferric arsenate precipitate, and after the reaction is completed, performing solid-liquid separation on the reactants to obtain ferric arsenate precipitate and treated water;

[0015] S5. Add lime milk to the treated water obtained in step S4, control the end point pH of the solution to be 8-12, and finally obtain industrial discharge deep purified water and refined gypsum products, achieve deep purification of polluted acid and effective recovery and utilization of sulfate ions; determine the amount of lime milk added by adjusting the pH value.

[0016] Preferably, in the step S1, the S content of the pyrite is ≥45%, and the Fe content is ≥45%; and the grinding is performed to a size of less than 400 mesh.

[0017] Specifically, crushing and grinding pyrite to less than 400 mesh is beneficial to increase the reaction area with the polluted acid. - / Fe 2+ Arsenic precipitation agent, under the condition of S2, pyrite quickly dissolves and releases S - and Fe 2+ ions, among which S - The ions will react directly with the trivalent arsenic ions in the polluted acid to form arsenic sulfide precipitates.

[0018] Since the waste acid after treatment in step S3 still contains some arsenic ions, in order to further remove these arsenic ions, air is introduced and the pH value of the solution is controlled to be 0.5-3.5, which can generate ferric arsenate. In step S4, the magnetic field intensity is controlled to promote the arsenite ion / Fe in the mixed solution. 2+ Rapid oxidation reaction occurs with O2 in the air, accelerating the reaction of arsenate ions with Fe 3+ The ferric arsenate precipitate is generated, the arsenic ions in the polluted acid are removed, and the treated water is finally obtained;

[0019] Preferably, the arsenic ion concentration in the waste acid in step S2 is greater than 0.5 g / L.

[0020] Preferably, in step S2, the addition ratio of the arsenic precipitating agent to the contaminated acid is FeS2:As molar ratio (0.5-2):1.

[0021] Preferably, in step S2, the ultrasonic power is 50-400 W, and the stirring speed is 160-240 r / min.

[0022] Preferably, in step S2, the reaction temperature is 23-50° C., and the reaction time is 0.05-0.9 h.

[0023] Preferably, the air flow rate in step S3 is 80-150m 3 / h.

[0024] Preferably, the magnetic induction intensity of the superconducting strong magnetic field in step S4 is (2.0-4.5)×10 3 mT, the oxidation reaction time is 0.02-0.5h; the obtained treated water can be recycled as a flue gas pickling medium containing arsenic, thereby reducing the amount of spray water used in the flue gas pickling process.

[0025] The arsenic ion concentration in the treated water obtained in step S4 is lower than the comprehensive sewage discharge standard (GB8978-1996).

[0026] The industrial discharge deep purified water obtained in step S5 meets the comprehensive discharge standard of industrial wastewater; the purity of CaSO4 in the obtained refined gypsum product reaches more than 96%.

[0027] The beneficial effects brought about by the technical solution provided by the embodiment of the present invention include at least:

[0028] (1) The present invention uses ultrasound to enhance the dissolution of pyrite and release S - and Fe 2+ Ions reduce the energy barrier that needs to be overcome in the total reaction or partial reaction involved in the arsenic precipitation reaction process, thereby accelerating the precipitation rate of arsenic sulfide and shortening the reaction cycle. At the same time, it prevents the arsenic sulfide precipitate generated in the arsenic removal process from dissolving back.

[0029] (2) The use of superconducting high-strength magnets can not only promote the 2+ and oxygen to produce Fenton reaction, accelerating the arsenite ion and Fe 2+ It can also increase the ion oxidation rate, increase the activity of arsenate ions in the solution, promote the precipitation reaction of ferric arsenate, and shorten the reaction time. At the same time, it can also increase the sedimentation rate of arsenic sulfide and ferric arsenate flocs, and achieve effective separation of solution and solid.

[0030] (3) The present invention proposes a strategy for the recovery and utilization of sulfate ions in waste acid, avoiding the production of arsenic-containing neutralization slag in conventional disposal processes. The purity of CaSO4 in the prepared refined gypsum product reaches more than 96%, maximizing the resource utilization of waste acid and bringing additional economic benefits to the enterprise.

[0031] (4) Compared with the conventional pyrite treatment process of high-arsenic contaminated acid, the invention introduces external field assistance, which not only reduces the amount of pyrite used, but also increases the reaction rate and shortens the contaminated acid treatment cycle, which is conducive to industrial promotion and utilization.

[0032] (5) Choosing pyrite as the arsenic precipitation agent fully utilizes the sulfur and iron elements in it, produces a small and stable slag, and has a "killing two birds with one stone" effect. In addition, pyrite is cheap and easy to obtain, which effectively reduces the operating cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0034] Figure 1 This is a real picture of the refined gypsum prepared in Example 3 of the present invention;

[0035] Figure 2 This is a microscopic image of the refined gypsum prepared in Example 3 of the present invention. DETAILED DESCRIPTION

[0036] The technical solution of the present invention is described below in conjunction with the accompanying drawings.

[0037] In the embodiments of the present invention, words such as "exemplarily" and "for example" are used to indicate examples, illustrations or explanations. Any embodiment or design described as "example" in the present invention should not be interpreted as being more preferred or more advantageous than other embodiments or designs. Specifically, the use of the word "example" is intended to present the concept in a specific way. In addition, in the embodiments of the present invention, the meaning expressed by "and / or" can be both, or it can be either of the two.

[0038] The embodiment of the present invention provides a method for treating high-arsenic contaminated acid with pyrite by using ultrasound in conjunction with a strong superconducting magnetic field.

[0039] A method for treating high-arsenic contaminated acid with pyrite by using ultrasonic waves in combination with a superconducting strong magnetic field, the method comprising:

[0040] S1, crushing and grinding the pyrite to less than 400 mesh;

[0041] S2, adding the pyrite obtained in step S1 as an arsenic precipitant into the closed reaction tank A, introducing the polluted acid into the reaction tank A through a water pump and a pipeline, turning on the ultrasonic generator, stirring, reacting, and generating arsenic sulfide precipitation;

[0042] S3, introducing the waste acid from which the arsenic sulfide precipitate is removed in step S2 into reaction tank B through a water pump and a pipeline, introducing air and controlling the pH value of the solution to be 0.5 to 3.5, generating ferric arsenate, and obtaining a solid-liquid mixture;

[0043] S4, introducing the solid-liquid mixture obtained in step S3 into a superconducting strong magnetic field, and promoting the arsenite ion / Fe in the mixed solution by controlling the magnetic induction intensity of the magnetic field. 2+ Rapid oxidation reaction occurs with O2 in the air (generally 0.02 to 0.5 hours), accelerating the precipitation reaction rate of ferric arsenate, removing arsenic ions in the polluted acid, and finally obtaining treated water;

[0044] S5. Introduce the treated water obtained in step S4 into the reaction tank C, add lime milk, and control the end point pH of the solution to be 8-12, and finally obtain industrial discharge deep purified water and refined gypsum products.

[0045] This will be described below with reference to specific embodiments.

[0046] The chemical composition of pyrite used in the embodiments of the present invention is shown in Table 1.

[0047] Table 1

[0048] element Fe S Si Al O As Others Content (wt.%) 46.26 45.25 0.38 0.16 3.06 0.02 4.87

[0049] Example 1

[0050] The specific steps are as follows:

[0051] (1) Crushing and grinding the pyrite to less than 500 mesh accounts for 50%, which is beneficial to increase the reaction area with the polluted acid;

[0052] (2) Add an appropriate amount of pyrite as S into the closed reaction tank A. - / Fe 2+ Arsenic precipitator, the waste acid (chemical composition is shown in Table 2) is introduced into the reaction tank A through a water pump and a pipeline, and the reaction is carried out for 0.9h at an ultrasonic power of 50W, a stirring speed of 240r / min, and a reaction temperature of 50℃. Under this condition, pyrite dissolves rapidly and releases S - and Fe 2+ ions, among which S - The ions will directly react with the trivalent arsenic ions in the polluted acid to form arsenic sulfide precipitation;

[0053] (3) After the treatment in step (2), the waste acid still contains some arsenic ions. In order to further remove these arsenic ions, the waste acid is introduced into the reaction tank B through a water pump and a pipeline, and air is introduced into the reaction tank and the pH of the solution is controlled to be 0.5 to generate ferric arsenate and obtain a solid-liquid mixture;

[0054] (4) introducing the solid-liquid mixture obtained in step (3) into a superconducting strong magnetic field, and promoting the arsenite ion / Fe in the mixed solution by controlling the magnetic induction intensity of the magnetic field. 2+ It undergoes a rapid oxidation reaction with O2 in the air, with a reaction time of 0.02h, and at the same time accelerates the precipitation reaction rate of ferric arsenate, achieving efficient removal of arsenic ions in the waste acid. The final arsenic ion concentration in the treated water is 0.40mg / L, which is lower than the comprehensive sewage discharge standard (GB8978-1996);

[0055] (5) The treated water obtained in step (4) is introduced into reaction tank C, and lime milk is added thereto to control the end point pH of the solution to 12, thereby finally obtaining industrial discharge deep purified water and refined gypsum products, achieving deep purification of waste acid and effective recovery and utilization of sulfate ions.

[0056] In the step (2), the arsenic ion concentration in the waste acid is 0.5 g / L, and the addition ratio of pyrite to waste acid is a FeS2:As molar ratio of 0.5:1.

[0057] The air flow rate in step (3) is 80m 3 / h.

[0058] The magnetic induction intensity in step (4) is 2000 mT, and the effluent can be recycled as a flue gas pickling medium containing arsenic, thereby reducing the amount of spray water used in the flue gas pickling process.

[0059] The industrial wastewater deep purified water obtained in step (5) meets the comprehensive discharge standard of industrial wastewater (chemical composition is shown in Table 3) and can be reused; the purity of CaSO4 in the refined gypsum product obtained reaches 96.5%.

[0060] Table 2

[0061] element As <![CDATA[H2SO4]]> Zn Fe Sb Mg Pb Concentration (mg / L) 500 21000 15.36 18.90 6.74 0.42 7.35 element Ni Cd Hg Cl F Cr Cu Concentration (mg / L) 2.72 4.68 0.01 67.92 46.6 0.36 23.68

[0062] Table 3

[0063] element As F Zn Fe Sb Mg Pb Concentration (mg / L) 0.10 0.02 0.10 8.32 0.03 0.01 0.32 element Ni Cd Cl Concentration (mg / L) 0.65 0.21 0.64

[0064] Example 2

[0065] The specific steps are as follows:

[0066] (1) Crushing and grinding the pyrite to 80% below 400 mesh is beneficial to increase the reaction area with the polluted acid;

[0067] (2) Add an appropriate amount of pyrite as S into the closed reaction tank A. - / Fe 2+ Arsenic precipitator, the waste acid (chemical composition is shown in Table 4) is introduced into the reaction tank A through a water pump and a pipeline, and the reaction is carried out for 0.6h at an ultrasonic power of 400W, a stirring speed of 240r / min, and a reaction temperature of 45℃. Under this condition, pyrite dissolves rapidly to release S - and Fe 2+ ions, among which S - The ions will directly react with the trivalent arsenic ions in the polluted acid to form arsenic sulfide precipitation;

[0068] (3) After the treatment in step (2), the waste acid still contains some arsenic ions. In order to further remove these arsenic ions, the waste acid is introduced into the reaction tank B through a water pump and a pipeline, and air is introduced into the reaction tank while the pH of the solution is controlled to be 2.5 to generate ferric arsenate and obtain a solid-liquid mixture;

[0069] (4) introducing the solid-liquid mixture obtained in step (3) into a superconducting strong magnetic field, and promoting the arsenite ion / Fe in the mixed solution by controlling the magnetic induction intensity of the magnetic field. 2+ It undergoes a rapid oxidation reaction with O2 in the air, with a reaction time of 0.5h, and at the same time accelerates the precipitation reaction rate of ferric arsenate, achieving efficient removal of arsenic ions in the waste acid. The final arsenic ion concentration in the treated water is 0.28mg / L, which is lower than the comprehensive sewage discharge standard (GB8978-1996);

[0070] (5) The treated water obtained in step (4) is introduced into reaction tank C, and lime milk is added thereto to control the end point pH of the solution to 10, thereby finally obtaining industrial discharge deep purified water and refined gypsum products, achieving deep purification of waste acid and effective recovery and utilization of sulfate ions.

[0071] In the step (2), the arsenic ion concentration in the waste acid is 26 g / L, and the addition ratio of pyrite to waste acid is a FeS2:As molar ratio of 2:1.

[0072] The air flow rate in step (3) is 120m 3 / h.

[0073] The magnetic induction intensity in step (4) is 4500 mT, and the effluent can be recycled as a flue gas pickling medium containing arsenic, thereby reducing the amount of spray water used in the flue gas pickling process.

[0074] The industrial wastewater deep purified water obtained in step (5) meets the comprehensive discharge standard of industrial wastewater (chemical composition is shown in Table 5) and can be reused; the purity of CaSO4 in the refined gypsum product obtained reaches more than 97.3%.

[0075] Table 4

[0076] element As <![CDATA[H2SO4]]> Zn Fe Sb Mg Pb Concentration (mg / L) 26000 54000 19.65 34.76 8.34 8.54 16.34 element Ni Cd Hg Cl F Cr Cu Concentration (mg / L) 9.34 11.87 1.76 598.46 389.34 2.09 22.63

[0077] Table 5

[0078] element As F Zn Fe Sb Mg Pb Concentration (mg / L) 0.15 0.98 0.01 17.43 0.01 0.01 0.02

[0079] Example 3

[0080] The specific steps are as follows:

[0081] (1) Crushing and grinding pyrite to less than 400 mesh accounts for 20%, which is beneficial to increase the reaction area with the polluted acid;

[0082] (2) Add an appropriate amount of pyrite as S into the closed reaction tank A. - / Fe 2+ Arsenic precipitator, the waste acid (chemical composition is shown in Table 6) is introduced into the reaction tank A through a water pump and a pipeline, and the reaction is carried out for 0.9h at an ultrasonic power of 200W, a stirring speed of 180r / min, and a reaction temperature of 23℃. Under this condition, pyrite dissolves rapidly to release S - and Fe 2+ ions, among which S - The ions will directly react with the trivalent arsenic ions in the polluted acid to form arsenic sulfide precipitation;

[0083] (3) After the treatment in step (2), the waste acid still contains some arsenic ions. In order to further remove these arsenic ions, they are introduced into the reaction tank B through a water pump and a pipeline, and air is introduced into the reaction tank and the pH of the solution is controlled to be 3.5, so as to create favorable conditions for the synthesis of ferric arsenate;

[0084] (4) introducing the solid-liquid mixture obtained in step (3) into a superconducting strong magnetic field, and promoting the arsenite ion / Fe in the mixed solution by controlling the magnetic induction intensity of the magnetic field. 2+ It undergoes a rapid oxidation reaction with O2 in the air, with a reaction time of 0.2h. It also accelerates the precipitation reaction rate of ferric arsenate, achieving efficient removal of arsenic ions from the waste acid. The final arsenic ion concentration in the treated water is 0.36mg / L, which is lower than the comprehensive sewage discharge standard (GB8978-1996).

[0085] (5) The treated water obtained in step (4) is introduced into the reaction tank C, and lime milk is added thereto to control the end point pH of the solution to 8, thereby finally obtaining industrial discharge deep purified water and refined gypsum products, achieving deep purification of waste acid and effective recovery and utilization of sulfate ions.

[0086] In the step (2), the arsenic ion concentration in the waste acid is 11 g / L, and the addition ratio of pyrite to waste acid is a FeS2:As molar ratio of 1.5:1.

[0087] The air flow rate in step (3) is 150m 3 / h.

[0088] The magnetic induction intensity in step (4) is 3200 mT, and the effluent can be recycled as a flue gas pickling medium containing arsenic, thereby reducing the amount of spray water used in the flue gas pickling process.

[0089] The industrial wastewater deep purification water obtained in step (5) meets the comprehensive discharge standard of industrial wastewater (chemical composition is shown in Table 7) and can be reused; the purity of CaSO4 in the refined gypsum product is above 98.8%, and its physical and microscopic images are shown as follows: Figure 1 and Figure 2 As shown. Figure 1 It can be seen that the refined gypsum product is white granular. Figure 2 It can be seen that the refined gypsum product has a rectangular crystal structure.

[0090] Table 6

[0091]

[0092]

[0093] Table 7

[0094] element As Cl Zn Fe F Mg Pb Concentration (mg / L) 0.12 0.98 0.01 4.34 0.89 0.01 0.01

[0095] Comparative Example 1

[0096] The other experimental steps and conditions are the same as those in Example 3, except that there is no ultrasonic effect in step (2).

[0097] Comparative Example 2

[0098] The other experimental steps and conditions are the same as those in Example 3, except that: in step (4), there is no superconducting strong magnetic field.

[0099] Comparative Example 3

[0100] The other experimental steps and conditions are the same as those in Example 3, except that: step (2) does not involve the action of ultrasonic waves and step (4) does not involve the action of a superconducting strong magnetic field.

[0101] Table 8 shows the effect of pyrite on the residual arsenic ion concentration in the treated water and the purity of CaSO4 in the refined gypsum product with and without the external field. It can be seen from the data in Table 8 that, compared with the case without the external field, when the ultrasonic wave and the superconducting strong magnetic field are simultaneously introduced into the reaction system, the arsenic removal effect of pyrite on the high arsenic contaminated acid is significantly increased, and the purity of CaSO4 in the prepared refined gypsum product is improved, indicating that the external field assistance is conducive to strengthening the treatment of high arsenic contaminated acid with pyrite.

[0102] Table 8

[0103]

[0104] Among them, √ represents the effect of external field, and × represents no effect of external field.

[0105] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for treating high-arsenic acid contaminated with pyrite by using ultrasonic waves in combination with a strong superconducting magnetic field, characterized in that: The method comprises: S1, crushing and grinding pyrite to obtain a pyrite arsenic precipitating agent; S2, adding an arsenic precipitant to the waste acid and performing ultrasonic reaction while stirring until arsenic sulfide precipitate is generated, and performing solid-liquid separation on the reactants to obtain arsenic sulfide precipitate and separation liquid; S3, introducing air into the separation liquid and controlling the pH value of the separation liquid to be 0.5-3.5, generating ferric arsenate and obtaining a solid-liquid mixture; S4, placing the solid-liquid mixture obtained in step S3 in a superconducting strong magnetic field and continuing to introduce air for oxidation reaction, so that the arsenite ions / Fe in the solid-liquid mixture 2+ Rapid oxidation reaction occurs with O2 in the air, accelerating the reaction of arsenate ions with Fe 3+ generating ferric arsenate precipitate, and after the reaction is completed, performing solid-liquid separation on the reactants to obtain ferric arsenate precipitate and treated water; S5. Add lime milk to the treated water obtained in step S4, control the end point pH of the solution to be 8-12, and finally obtain industrial discharge purified water and gypsum.

2. The method of treating high-arsenic acid contaminated by pyrite by using ultrasonic wave and superconducting strong magnetic field according to claim 1 is characterized in that: In the step S1, the S content of the pyrite is ≥45%, and the Fe content is ≥45%; the grinding is grinding to below 400 mesh.

3. The method of treating high-arsenic acid contaminated by pyrite by using ultrasonic wave and superconducting strong magnetic field according to claim 1 is characterized in that: In step S2, the arsenic ion concentration in the waste acid is greater than 0.5 g / L.

4. The method of treating high-arsenic contaminated acid with pyrite by using ultrasonic wave and superconducting strong magnetic field enhancement according to claim 1 is characterized in that: In step S2, the addition ratio of the arsenic precipitating agent to the waste acid is FeS2:As molar ratio (0.5-2):

1.

5. The method of treating high-arsenic acid contaminated by pyrite by using ultrasonic wave and superconducting strong magnetic field according to claim 1 is characterized in that: In step S2, the ultrasonic power is 50-400W, and the stirring speed is 160-240r / min.

6. The method of treating high-arsenic acid contaminated by pyrite by using ultrasonic wave and superconducting strong magnetic field according to claim 1 is characterized in that: In step S2, the reaction temperature is 23-50° C., and the reaction time is 0.05-0.9 h.

7. The method of treating high-arsenic acid contaminated by pyrite by using ultrasonic wave and superconducting strong magnetic field according to claim 1 is characterized in that: The air flow rate in step S3 is 80-150m 3 / h.

8. The method of treating high-arsenic acid contaminated by pyrite by using ultrasonic wave and superconducting strong magnetic field as described in claim 1 is characterized in that: The magnetic induction intensity of the superconducting strong magnetic field in step S4 is (2.0-4.5)×10 3 mT, the oxidation reaction time is 0.02-0.5h; the obtained treated water can be recycled as a pickling medium for arsenic-containing flue gas.

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