Comprehensive treatment method for acid mine wastewater

Abstract

The invention provides an acid mine wastewater comprehensive treatment method, and belongs to the field of mine wastewater treatment.The method treats wastewater through three stages of iron removal pretreatment, replacement copper collection and neutralization treatment in sequence, firstly, the pH value of the wastewater is adjusted in an iron removal reaction tank for reaction, after solid-liquid separation, part of underflow flows back, and the rest enters a filter pressing system; then the liquid subjected to iron removal is guided into a copper recovery reaction tank, copper recovery is conducted through a reducing agent and an iron powder system, and underflow backflow and filter pressing treatment are conducted; and finally, adjusting the pH value of the liquid after copper collection in a neutralization reaction tank, oxidizing, carrying out solid-liquid separation and underflow reflux, and finally discharging after reaching the standard, thereby realizing deep purification of the acid mine wastewater. The slag generated by the method provided by the invention is common industrial solid waste, the environmental risk of waste slag stockpiling is reduced, the reaction efficiency is optimized through underflow reflux in the whole process, and efficient recovery of copper and stable standard treatment of wastewater are realized.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of mine wastewater treatment, and particularly relates to a comprehensive treatment method for acid mine wastewater. BACKGROUND

[0002] The sulfur-rich ore deposit of non-ferrous metal mine contains a large amount of sulfide minerals. Under the action of air, water and microorganisms, a series of physical and chemical and biochemical reactions such as weathering, leaching, oxidation and hydrolysis occur, and gradually form acid liquid containing sulfuric acid, which affects the environment around the mine. Therefore, it is necessary to treat these acid water to protect the environment around the mine.

[0003] Due to the fact that these acid water is generally rich in valuable substances such as copper and iron, the commonly used treatment method at present is mainly chemical precipitation method, including neutralization method and sulfidation method. Among them, the sulfidation method is widely used as the mainstream acid mine wastewater valuable substance recovery process. However, although the sulfidation method can achieve efficient recovery of valuable copper, it has the problem that the sulfidation agent such as sodium hydrosulfide and sodium sulfide in the acid system is easy to release hydrogen sulfide, a toxic and harmful gas, causing safety hazards and secondary pollution problems, especially in the application of environmentally sensitive areas. Therefore, how to reasonably optimize the copper recovery process of acid mine wastewater and avoid the generation of toxic and harmful gases such as hydrogen sulfide is the research focus of the current comprehensive treatment of acid mine wastewater.

[0004] Therefore, it is necessary to design a comprehensive treatment method for acid mine wastewater to solve the above problems. SUMMARY

[0005] In view of the technical problems in the background art, the present application provides a comprehensive treatment method for acid mine wastewater, which aims to solve the technical problems in the prior art that the sulfidation precipitation method has the safety and environmental hidden danger of hydrogen sulfide overflow, and the iron filings replacement method has the problems of low reaction efficiency, easy passivation, high equipment requirement, large investment and limited application.

[0006] The present application provides a comprehensive treatment method for acid mine wastewater, comprising the following steps: S1. inputting the acid mine wastewater into an iron removal reaction tank, adding a first pH adjusting agent to adjust the pH value to 3.5-3.7, and reacting for 0.25-0.5 h to obtain an iron removal turbid liquid; adding a flocculating agent to the iron removal turbid liquid, and performing solid-liquid separation to obtain an iron removal underflow and an iron removal overflow; returning 2-10% of the iron removal underflow to the iron removal reaction tank, and returning 25-35% of the iron removal underflow to a copper recovery residue pressure filtration system, and the rest of the iron removal underflow is subjected to pressure filtration dewatering treatment to obtain first pressure filtration residue and first pressure filtration liquid; S2. The iron-removed overflow and the first filter liquor obtained in step S1 are input into a copper recovery reaction tank, a reducing agent is added to adjust the ORP value to 350-450 mV, a reducing iron powder system reagent is added, and reaction is performed for 0.25-0.5 h to obtain a copper recovery turbid liquid; A flocculating agent is added to the copper recovery turbid liquid, and solid-liquid separation is performed to obtain a copper recovery underflow and a copper recovery overflow; 2-10% of the copper recovery underflow is returned to the copper recovery reaction tank, and the remaining copper recovery underflow is mixed with the iron-removed underflow input into the copper recovery residue filter pressing system in step S1, and then dewatering treatment is performed by filter pressing to obtain second filter pressing residue and second filter pressing liquor; S3. The copper recovery overflow and the second filter pressing liquor obtained in step S2 are input into a neutralization reaction tank, a second pH adjusting agent is added to adjust the pH value to 8.2-8.8, an oxidizing agent is introduced, and reaction is performed for 0.8-1.2 h to obtain a neutralization turbid liquid; A flocculating agent is added to the neutralization turbid liquid, and solid-liquid separation is performed to obtain a neutralization underflow and a neutralization overflow; 70-90% of the neutralization underflow is returned to the neutralization reaction tank, and the remaining neutralization underflow is subjected to dewatering treatment by filter pressing to obtain third filter pressing residue and third filter pressing liquor; wherein the neutralization overflow and the third filter pressing liquor are discharged after detection.

[0007] As a further improvement of the present application, in step S2, the reducing iron powder system reagent comprises iron powder, activated carbon, bentonite, diatomite and zinc oxide, and the mass ratio is 80-95% : 1-3% : 2-10% : 1-6% : 0.5-1%.

[0008] As a further improvement of the present application, the dosage of the reducing iron powder system reagent is 1.4-2.0 times the amount of iron powder based on the theoretical reaction of iron powder and copper in acid mine wastewater.

[0009] As a further improvement of the present application, in step S1, the first pH adjusting agent is one or more of lime, sodium carbonate, sodium hydroxide and calcium carbide slag.

[0010] As a further improvement of the present application, in step S2, the reducing agent is one or more of sodium sulfite, thiosulfate, sodium metabisulfite and citric acid; and the grade of copper in the second filter pressing residue is ≥40%.

[0011] As a further improvement of the present application, in step S3, the oxidizing agent is air or hydrogen peroxide, and the second pH adjusting agent is lime or calcium carbide slag.

[0012] As a further improvement of the present application, the oxidizing agent is air, and the gas-liquid volume ratio is 1: (4-5).

[0013] As a further improvement of the application, the oxidant is hydrogen peroxide, and the mass ratio of the hydrogen peroxide to the divalent iron ion in the solution is (0.60-6):1.

[0014] As a further improvement of the application, the flocculant is a non-ionic flocculant, and the addition amount is 0-15 g / m 3 .

[0015] As a further improvement of the application, the pollutants in the acid mine wastewater include one or more of copper, iron, zinc, lead, arsenic, manganese, nickel, cadmium, chromium, and beryllium, and the concentration of copper ions is not less than 100 mg / L; and the temperature of the acid mine wastewater is greater than or equal to 5 DEG C.

[0016] The application has the following beneficial effects: The application provides a comprehensive treatment method for acid mine wastewater, which sequentially includes iron removal, copper recovery, and neutralization, and the wastewater is first treated in an iron removal reaction tank to adjust the pH of the wastewater to 3.5-3.7, and then the wastewater is treated by solid-liquid separation, and part of the underflow is returned, and the rest is introduced into a pressure filtration system; then the liquid after the iron removal is introduced into a copper recovery reaction tank, and copper is recovered by a reducer and iron powder system, and the underflow is returned and treated by pressure filtration; finally, the liquid after the copper recovery is adjusted to a pH of 8.2-8.8 in a neutralization reaction tank and is oxidized, and then the liquid is treated by solid-liquid separation and underflow return, and finally, the wastewater is discharged up to the standard. The whole process optimizes the reaction efficiency by underflow return, realizes efficient recovery of copper, and stably treats the wastewater up to the standard.

[0017] The comprehensive treatment method for acid mine wastewater provided by the application can still maintain a high reaction rate in a low-temperature environment, so that the safe, environmentally friendly, and efficient treatment of acid mine wastewater is realized, the target pollutants such as copper, lead, and arsenic in the treated acid mine wastewater can reach the first emission standard of the Integrated Wastewater Discharge Standard (GB 8978-1996) and the strict limit value of the direct discharge limit value requirement of Table 2 of the Copper, Cobalt, and Nickel Industrial Pollutant Discharge Standard (GB 25467-2010), the comprehensive recovery rate of copper can be more than 94%, the waste residue produced belongs to general industrial solid waste, and the application has significant economic, environmental, and social benefits, and provides a new idea for the treatment of acid mine wastewater, especially in cold regions.

[0018] The acid mine wastewater comprehensive treatment method provided in the application is targeted at the pollution endowment characteristics of the acid mine wastewater rich in valuable substances such as copper, combined with the process characteristics of the current acid water treatment, and through reasonable design of the water treatment process, the acid mine wastewater is sequentially subjected to iron removal pretreatment, copper recovery by replacement, and neutralization treatment, and all the ferric iron is removed in the iron removal pretreatment, the efficient recovery of copper ions is realized in the copper recovery section, and at the same time, the oxidizing agent is used in the neutralization process, so that the neutralization overflow and the filter press liquor obtained in the neutralization process meet the emission standard, and the deep purification of the acid mine wastewater is realized. The slag generated by the method provided in the application is a general industrial solid waste, which reduces the environmental risk of waste residue storage, and the treatment process does not have toxic and harmful gas such as hydrogen sulfide overflow, so that the copper in the acid mine wastewater can be recovered safely, environmentally and efficiently.

[0019] The acid mine wastewater comprehensive treatment method provided in the application successfully overcomes the problems of large water quality fluctuation and low water temperature of the acid water by further regulating and controlling the pH value, ORP value, reducing iron powder system reagent formula, reflux ratio and other parameters in the treatment process, and can efficiently treat the acid mine wastewater into water bodies meeting the emission standard with a simple process, and at the same time, the efficient recovery of valuable copper is realized, which has high utilization value.

[0020] The acid mine wastewater comprehensive treatment method provided in the application has simple process, safe and reliable operation, and common and low-cost reagents, can treat the acid mine wastewater into water bodies meeting the emission standard, avoids the risk of hydrogen sulfide gas overflow in the conventional method, improves the recovery rate of copper, has significant economic, environmental and social benefits, and provides a new idea for the treatment of acid mine wastewater.

[0021] The above description is only a summary of the technical solutions of the application, in order to more clearly understand the technical means of the application, the specific embodiments of the application can be implemented according to the content of the specification, and in order to make the above and other purposes, characteristics and advantages of the application more obvious and easy to understand, the following specific embodiments of the application are described. BRIEF DESCRIPTION OF DRAWINGS

[0022] In order to more clearly illustrate the technical solutions of the application, the following will briefly introduce the drawings used in the application. Obviously, the drawings described below are only some embodiments of the application, and other drawings can be obtained by those skilled in the art without creating laborious work.

[0023] Figure 1 The acid mine wastewater comprehensive treatment method flow chart provided for the embodiments of the application. DETAILED DESCRIPTION

[0024] The technical solutions of the present application will be described in detail below with reference to the drawings. The following embodiments are only used to more clearly illustrate the technical solutions of the present application, and therefore only serve as examples, but cannot limit the protection scope of the present application.

[0025] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application belongs; the terms used herein are only for the purpose of describing specific embodiments and are not intended to limit the present application; the terms "include" and "have" and any variations thereof in the specification and claims of the present application and the above description of drawings are intended to cover non-exclusive inclusion.

[0026] Reference herein to "an embodiment" means that a particular feature, structure, or characteristic described in connection with the embodiment can be included in at least one embodiment of the present application. The appearance of the phrase in various places in the specification does not necessarily all refer to the same embodiment, nor is it necessarily mutually exclusive or alternative to other embodiments. It is explicitly and implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0027] In the description of the embodiments of the present application, the term "a plurality of" refers to two or more (including two), and similarly, "a plurality of groups" refers to two or more groups (including two groups), and "a plurality of pieces" refers to two or more pieces (including two pieces).

[0028] For acid mine drainage, the traditional sulfidation precipitation method for recovering copper has the safety and environmental protection hidden danger problem of hydrogen sulfide gas overflow, and the conventional iron filings displacement copper process has the problems of long reaction time, low reaction rate in low temperature environment, easy passivation of iron powder, and high design requirements of the reactor, resulting in large investment of the iron filings displacement copper process and limited application and promotion.

[0029] In order to solve the technical problems of safety and environmental protection hidden danger, low reaction efficiency, high cost, and limited application of the traditional acid mine drainage treatment, the present application provides a comprehensive treatment method for acid mine drainage, wherein the acid mine drainage is sequentially subjected to iron removal pretreatment, copper displacement recovery, and neutralization treatment, and a reduced iron powder system reagent is used to replace the traditional sulfidation agent, thereby avoiding the generation of H2S gas and significantly improving the safety; the method is suitable for low temperature environment and has high reaction rate, thereby widening the application range thereof.

[0030] Please refer to Figure 1 The embodiment of the present application provides a comprehensive treatment method for acid mine drainage, comprising the following steps: S1. inputting the acid mine drainage into an iron removal reaction tank, adding a first pH adjusting agent to adjust the pH value to 3.5~3.7, and reacting for 0.25~0.5h to obtain an iron removal turbid liquid; The flocculating agent is added to the iron removal turbid liquid, and solid-liquid separation is performed to obtain an iron removal underflow and an iron removal overflow; The 2-10% iron removal underflow is returned to the iron removal reaction tank, 25-35% of the iron removal underflow is introduced into the copper recovery residue filter pressing system, and the remaining iron removal underflow is subjected to filter pressing dewatering treatment to obtain first filter pressing residue and first filter pressing liquid; wherein the first filter pressing residue (i.e. iron removal residue) has leaching toxicity and toxic substance content reaching the requirements of general industrial solid waste, and can be stored as general industrial solid waste in compliance with regulations; S2. The iron removal overflow and the first filter pressing liquid obtained in step S1 are introduced into the copper recovery reaction tank, a reducing agent is added to adjust the ORP value to 350-450 mV, a reducing iron powder system reagent is added, and reaction is performed for 0.25-0.5 h to obtain a copper recovery turbid liquid; The flocculating agent is added to the copper recovery turbid liquid, and solid-liquid separation is performed to obtain a copper recovery underflow and a copper recovery overflow; The 2-10% copper recovery underflow is returned to the copper recovery reaction tank, so that the mass concentration of the solid phase in the copper recovery underflow in the recycling process is controlled at 10-20% to reduce the processing pressure of the copper recovery underflow filter pressing section, and the remaining copper recovery underflow is mixed with the iron removal underflow introduced into the copper recovery residue filter pressing system in step S1, and then subjected to filter pressing dewatering treatment to obtain second filter pressing residue and second filter pressing liquid; wherein the second filter pressing residue can be sold as copper residue; S3. The copper recovery overflow and the second filter pressing liquid obtained in step S2 are introduced into the neutralization reaction tank, a second pH adjusting agent is added to adjust the pH value to 8.2-8.8, so that most of the harmful substances such as heavy metals are converted into precipitates, an oxidizing agent is introduced to react for 0.8-1.2 h to obtain a neutralization turbid liquid; The flocculating agent is added to the neutralization turbid liquid, and solid-liquid separation is performed to obtain a neutralization underflow and a neutralization overflow; The 70-90% neutralization underflow is returned to the neutralization reaction tank, so that the mass concentration of the solid phase in the neutralization underflow in the recycling process is controlled at 15-30% to reduce the processing pressure of the subsequent section, and the remaining neutralization underflow is subjected to filter pressing dewatering treatment to obtain third filter pressing residue and third filter pressing liquid; wherein the neutralization overflow and the third filter pressing liquid are discharged after detection; the third filter pressing residue has leaching toxicity and toxic substance content reaching the requirements of general industrial solid waste, and can be stored as general industrial solid waste in compliance with regulations.

[0031] In the technical scheme of the embodiment of the present application, through step-by-step selective precipitation, iron is preferentially precipitated and removed under weak acidic conditions, avoiding interference with subsequent copper recovery; in the wastewater after iron removal, the displacement reaction of the reduced iron powder is used to efficiently reduce copper ions into elemental copper for recovery, avoiding the safety risk of hydrogen sulfide generated by the traditional sulfidation method, and neutralization and oxidation are performed on the residual wastewater to make the remaining heavy metal ions form stable precipitates, ensuring that the final effluent meets the standards. The entire process improves reaction efficiency and precipitation effect through partial underflow reflux, and by mixing part of the iron removal residue into the copper residue, the yield of the saleable copper residue is increased under the premise of ensuring the copper grade, realizing the unity of economic benefit and environmental benefit.

[0032] Further, in some embodiments, in step S2, the reduced iron powder system reagent includes iron powder, activated carbon, bentonite, diatomite and zinc oxide, and the mass ratio is 80-95%:1-3%:2-10%:1-6%:0.5-1%.

[0033] In the technical scheme of the embodiment of the present application, the iron powder can displace copper ions from the solution to generate elemental copper, and iron powder of different particle sizes (80-300 mesh) can be used; the activated carbon adsorbs the copper ions in the solution onto its surface, increasing the contact opportunity and local concentration of the iron powder and the copper ions, thereby significantly accelerating the reaction rate. In addition, the surface of the activated carbon can act as an electron transfer medium, reducing the activation energy of the reaction, further catalyzing the displacement reaction of the iron powder and the copper ions, and the fine copper particles generated can adhere to the activated carbon to form denser agglomerates, which helps subsequent solid-liquid separation, making the copper residue easier to settle and filter-press; the bentonite forms a charged colloid in water and can act as a crystal nucleus or skeleton to adsorb and wrap the fine copper particles, iron powder debris and other suspended solids generated by the reaction together to form larger and denser flocs, improving the settling performance and making the solid-liquid separation faster and more complete. The addition of bentonite makes the copper residue (second filter-pressing residue) formed finally have better plasticity and structural strength, which is not easy to run during filter-pressing dewatering, and the filter cake formed is also more regular; the porous structure of diatomite can form a filter cake with excellent permeability, preventing fine copper particles or other impurities from blocking the filter cloth, thereby significantly improving the filter-pressing efficiency and the clarity of the filtrate; zinc oxide helps to stabilize the pH value of the reaction system in the weakly acidic range suitable for iron powder displacement, preventing copper from dissolving back. Through the synergistic effect of multiple components, a high-efficiency, stable and multifunctional reaction system is formed, which not only safely and efficiently recovers copper, but also optimizes the kinetics and physical properties of the entire reaction and subsequent treatment process, making the process operation more stable.

[0034] Further, in some embodiments, the dosage of the reduced iron powder system reagent is based on the iron powder content and is added in an amount of 1.4-2.0 times the theoretical reaction of the iron powder with the copper in the acidic mine wastewater.

[0035] In the technical scheme of the embodiment of the present application, the dosage of the reduced iron powder system reagent helps to compensate for the consumption of side reactions caused by wastewater acidity, dissolved oxygen and other impurities, uses excess reactants to drive chemical equilibrium, ensures rapid and complete reaction, low residual copper concentration, provides sufficient safety redundancy, enables the process to adapt to fluctuations in actual water quality, ensures stable operation, controls reagent costs under the premise of ensuring treatment effect, and avoids secondary problems and resource waste caused by excessive addition. If the dosage of iron powder is increased, the reagent is added at a dosage of 2 times the theoretical value of the iron-copper reaction, the reaction temperature of the acid mine wastewater is increased to above 25°C (the higher the temperature, the faster the reaction rate), and the reaction time is extended to more than 1 hour, the effective recovery of copper in acid mine wastewater can also be achieved, but this method increases the process equipment investment and operating cost (iron powder, heating energy consumption), and because of the large amount of iron powder added, the grade of copper residue will be reduced, and the amount of neutralization residue will be increased.

[0036] Further, in some embodiments, in step S1, the first pH regulator is one or more of lime, sodium carbonate, sodium hydroxide, carbide slag.

[0037] In the technical scheme of the embodiment of the present application, the acid wastewater is pretreated by adding the first pH regulator, and the acidity is reduced by neutralizing part of the free acid, thereby creating a favorable reaction environment for the subsequent reduction of iron powder replacement; at the same time, this step can also promote the early precipitation of part of the metal impurities that are prone to hydrolysis, achieving preliminary purification of the water quality. The pH value needs to be controlled between 3.5 and 3.7. When the pH value is lower than 3.5, the trivalent iron in the acid mine wastewater cannot be completely precipitated, and the residual trivalent iron will consume related reagents in the copper recovery section; when the pH value is higher than 3.7, the copper in the acid mine wastewater will enter the iron residue in the form of precipitation, thereby causing loss of copper; the amount of iron removal residue mixed with the copper recovery underflow cannot be too high, otherwise the copper residue grade will be low and cannot be sold as copper products; the amount of iron removal residue mixed with the copper recovery underflow also cannot be too low, otherwise the copper grade will be too high, and with the unchanged pricing coefficient, it will affect the direct economic benefit. By mixing part of the iron removal residue into the copper residue, not only the amount of solid waste is reduced, alleviating the problem of tight storage capacity, but also the copper residue production is increased, increasing the economic benefit.

[0038] Further, in some embodiments, in step S2, the reducing agent is one or more of sodium sulfite, thiosulfate, sodium metabisulfite, and citric acid; the grade of copper in the second pressure filtration residue is ≥40%.

[0039] In the technical scheme of the embodiment of the present application, the ORP value of the acid mine wastewater is controlled to 350-450 mV by adding a reducing agent, thereby reducing the dosage of the reduced iron powder system reagent and in turn reducing the amount of subsequent neutralization residue; high-grade copper residue can be directly sold as copper concentrate, and the content of harmful impurities in the copper residue is relatively low, making it easier to meet the leaching toxicity standards of general industrial solid waste.

[0040] Further, in some embodiments, in step S3, the oxidant is air or hydrogen peroxide, and the second pH regulator is lime or carbide slag.

[0041] In the technical scheme of the embodiments of the present application, through oxidation and pH adjustment, efficient removal of heavy metals such as Fe and Mn remaining in the wastewater is ensured. The dosage of the oxidant is positively correlated with the content of divalent iron in the neutralizing liquid.

[0042] Further, in some embodiments, the oxidant is air, and the gas-liquid volume ratio is 1: (4-5).

[0043] In the technical scheme of the embodiments of the present application, the gas-liquid volume ratio ensures sufficient oxygen supply for the oxidation reaction. If the aeration amount is insufficient, the oxidation will not be complete, the reaction rate will be slowed down, and the treatment capacity will be reduced.

[0044] Further, in some embodiments, the oxidant is hydrogen peroxide, and the mass ratio of hydrogen peroxide to divalent iron ions in the solution is (0.60-6):1.

[0045] In the technical scheme of the embodiments of the present application, by accurately controlling the addition ratio of hydrogen peroxide, the oxidation reaction can be ensured to proceed fully, and the excessive oxidant remaining can be avoided to cause subsequent treatment burden or side reactions, thereby optimizing the process economy and treatment effect.

[0046] Further, in some embodiments, the flocculant is a non-ionic flocculant, and the addition amount is 0-15 g / m 3 .

[0047] In the technical scheme of the embodiments of the present application, a non-ionic flocculant such as non-ionic polyacrylamide (PAM) is used for flocculation and sedimentation. In step S1, the addition amount of the flocculant is 1-10 g / m 3 , in step S2, the addition amount of the flocculant is 0-5 g / m 3 , and in step S3, the addition amount of the flocculant is 1-15 g / m 3 .

[0048] Further, in some embodiments, the pollutants in the acid mine wastewater include one or more of copper, iron, zinc, lead, arsenic, manganese, nickel, cadmium, chromium, and beryllium, and the concentration of copper ions is not less than 100 mg / L; the temperature of the acid mine wastewater is ≥5℃.

[0049] In the technical scheme of the embodiments of the present application, the treatment method can efficiently treat acid mine wastewater with complex components and high concentration, and overcome the problems of large water quality fluctuation and low water temperature of acid water, and has significant economic, environmental and social benefits.

[0050] Some specific examples are listed below, it should be noted that the examples described below are exemplary, only for the explanation of the present application, and can not be understood as a limitation of the present application. The technical or conditions not specified in the examples, according to the literature described in the art or according to the product specification. The reagents or instruments are not specified by the manufacturer, are the conventional products can be obtained by market.

[0051] Example 1 The present embodiment provides a comprehensive treatment method for acid mine drainage, which contains high concentrations of heavy metals such as copper and iron. The concentration of copper fluctuates within the range of 150.10~1456.21mg / L, the concentration of iron fluctuates within the range of 265.25~861.72mg / L, the concentration of arsenic is about 4mg / L, the concentration of manganese is within the range of 24~35.64mg / L, and the water temperature is within the range of 5~10℃ throughout the year. The process flow diagram is shown in Figure 1 The specific steps include the following: S1. Input the acid mine drainage into the iron removal reaction tank, add lime to adjust the pH value to 3.6, so that the heavy metal ions (mainly trivalent iron, arsenic, etc.) are chemically precipitated to be removed in the form of heavy metal precipitated solids. After 0.5h of reaction, the iron ion concentration is reduced from 700mg / L to about 200mg / L, and the iron removal turbidity liquid is obtained; According to the dosage of 3g / m 3 , non-ionic polyacrylamide is added to the iron removal turbidity liquid, and solid-liquid separation is carried out by the iron removal thickener to obtain the iron removal overflow and the iron removal underflow in the form of sludge; 10% of the iron removal underflow is returned to the iron removal reaction tank, 30% of the iron removal underflow enters the copper recovery residue pressure filtration system, and the rest of the iron removal underflow is treated by the first pressure filter to obtain the first pressure filter residue and the first pressure filter liquid. The first pressure filter residue meets the requirements of general industrial solid waste and is disposed by stacking in accordance with the regulations; S2. The iron removal overflow and the first pressure filter liquid obtained in step S1 are input into the copper recovery reaction tank, 10% of sodium sulfite solution is added as a reducing agent to adjust the ORP value to 400mv, and the reducing iron powder system reagent is added. The mass ratio of 80 mesh iron powder, 200 mesh iron powder, activated carbon, bentonite, diatomite and zinc oxide is 68%:16%:3%:7%:5%:1%. The reducing iron powder system reagent is added according to 1.4 times the theoretical reaction amount of iron powder with copper in acid mine drainage. After 0.5h of reaction, the copper concentration in the liquid phase is below 0.5mg / L, and the copper recovery turbidity liquid is obtained; According to the dosage of 2g / m 3 , non-ionic polyacrylamide is added to the copper recovery turbidity liquid, and solid-liquid separation is carried out by the copper recovery thickener to obtain the copper recovery overflow and the copper recovery underflow in the form of sludge; The 8% copper recovery underflow is refluxed into the copper recovery reaction tank, and the remaining copper recovery underflow is mixed with the iron removal underflow entering the copper residue filter pressing system in step S1, and then is subjected to dewatering treatment by a second filter press to obtain second filter pressing residue and second filter pressing liquid; wherein the second filter pressing residue can be sold as copper residue (with a copper grade of 45%); S3. The copper recovery overflow obtained in step S2 and the second filter pressing liquid are input into a neutralization reaction tank, lime is added to adjust the pH value to 8.5, and air is blown into the neutralization reaction tank to control the gas-liquid ratio to 1:5, further oxidizing the residual divalent iron ions, and causing the heavy metal ions (mainly iron, arsenic, zinc, lead, manganese, nickel, etc.) to be chemically precipitated so as to be removed in the form of heavy metal precipitated solids. After 1 h of reaction, a neutralization turbid liquid is obtained; According to the dosing amount of 8 g / m 3 , non-ionic polyacrylamide is added to the neutralization turbid liquid, and solid-liquid separation is performed by a neutralization thickener to obtain a neutralization overflow and a neutralization underflow in the form of sludge. 75% of the neutralization underflow is refluxed into the neutralization reaction tank, and the remaining neutralization underflow is subjected to dewatering treatment by a third filter press to obtain third filter pressing residue and third filter pressing liquid; wherein the target heavy metals in the third filter pressing liquid and the neutralization overflow meet the first emission standard of the “Integrated Wastewater Discharge Standard” (GB 8978-1996) and the direct emission limit value requirement specified in the “Copper, Cobalt, Nickel Industrial Pollutant Discharge Standard” (GB 25467-2010), and are discharged in accordance with the standard; the leaching toxicity and toxic substance content of the third filter pressing residue meet the general industrial solid waste requirements, and the third filter pressing residue can be stored as a general industrial solid waste in compliance.

[0052] The water quality before and after treatment in the present embodiment is detected, and the results are shown in Table 1.

[0053] Table 1 Water quality before and after treatment Note: The pH value is dimensionless, and the units of the remaining indicators in the table are “mg / L”.

[0054] From the above results, it can be seen that after treatment by the acid mine wastewater comprehensive treatment method provided in the present embodiment, the water quality after treatment meets the corresponding requirements, and the treatment capacity of the iron-containing acidic water in the overall treatment process reaches 500 m 3 / h, realizing efficient treatment of acid mine wastewater, and the copper recovery rate of valuable substances reaches 94.2%.

[0055] Comparative Examples 1-5 Comparative Examples 1-5 each provide a comprehensive treatment method for acid mine wastewater, and differ from Example 1 in that the pH value in step S1, the ORP value in step S2, the reductant iron powder system reagent formulation, the reagent dosage, and the pH value in step S3 are changed, respectively. The corresponding parameters for each of the comparative examples are shown in Table 2, and the remaining steps and parameters are substantially the same as in Example 1 and will not be described again here.

[0056] Table 2 Process parameters in Example 1 and Comparative Examples 1-5 After treating the iron-containing acid water according to the methods provided in Comparative Examples 1-5 above, the effluent water quality and the solid waste produced were detected, and the results are shown in Table 3.

[0057] Table 3 Test results As can be seen from Table 3, controlling the pH value in step S1 to be below 3.5 directly affects the copper recovery rate. If the ORP value in step S2 is not controlled to be below 450 mV, the reductant iron powder system reagent will be consumed, and the copper recovery rate will be reduced to 76.2%, which is relatively low. If only reductant iron powder is used to replace the copper in acid mine wastewater, there is a problem of low copper recovery rate. The dosage of the reductant iron powder system reagent is closely related to the copper recovery rate, and below 1.2 times the theoretical dosage, the copper recovery rate cannot reach more than 80%. If the pH value in step S3 is not controlled to be around 8.5, it will not be possible to ensure that each pollutant in the acid wastewater is effectively treated to meet the standard, especially Mn, which in Comparative Example 5 had a concentration of 2.5 mg / L after treatment, which is higher than the limit value of 2 mg / L required by the standard.

[0058] It should be noted that the present application is not limited to the above-described embodiments. The above-described embodiments are merely examples, and embodiments having substantially the same configuration and playing the same role and effect as the technical idea within the scope of the technical solutions of the present application are all included within the technical scope of the present application. Furthermore, within the scope of the main idea of the present application, various modifications that can be thought of by those skilled in the art, other modes constructed by combining part of the configuration elements of the embodiments are also included within the scope of the present application.

Claims

1. A comprehensive treatment method for acid mine drainage water, characterized by, The method comprises the following steps: S1. Acid mine drainage is input into an iron removal reaction tank, a first pH regulator is added to adjust the pH value to 3.5-3.7, and reaction is performed for 0.25-0.5 h to obtain an iron removal turbid liquid; A flocculating agent is added to the iron removal turbid liquid, and solid-liquid separation is performed to obtain an iron removal underflow and an iron removal overflow; 2-10% of the iron removal underflow is returned to the iron removal reaction tank, 25-35% of the iron removal underflow is input into a copper recovery residue pressure filtration system, and the rest of the iron removal underflow is subjected to pressure filtration dewatering treatment to obtain first pressure filtration residue and first pressure filtration liquid; S2. The iron removal overflow obtained in step S1 and the first pressure filtration liquid are input into a copper recovery reaction tank, a reducing agent is added to adjust the ORP value to 350-450 mV, a reducing iron powder system reagent is added, and reaction is performed for 0.25-0.5 h to obtain a copper recovery turbid liquid; A flocculating agent is added to the copper recovery turbid liquid, and solid-liquid separation is performed to obtain a copper recovery underflow and a copper recovery overflow; 2-10% of the copper recovery underflow is returned to the copper recovery reaction tank, and the rest of the copper recovery underflow is mixed with the iron removal underflow input into the copper recovery residue pressure filtration system in step S1, and then subjected to pressure filtration dewatering treatment to obtain second pressure filtration residue and second pressure filtration liquid; S3. The copper recovery overflow obtained in step S2 and the second pressure filtration liquid are input into a neutralization reaction tank, a second pH regulator is added to adjust the pH value to 8.2-8.8, an oxidizing agent is introduced, and reaction is performed for 0.8-1.2 h to obtain a neutralization turbid liquid; A flocculating agent is added to the neutralization turbid liquid, and solid-liquid separation is performed to obtain a neutralization underflow and a neutralization overflow; 70-90% of the neutralization underflow is returned to the neutralization reaction tank, the rest of the neutralization underflow is subjected to pressure filtration dewatering treatment to obtain third pressure filtration residue and third pressure filtration liquid; wherein the neutralization overflow and the third pressure filtration liquid are discharged after detection.

2. The method for comprehensive treatment of acid mine drainage water according to claim 1, characterized in that, In step S2, the reducing iron powder system reagent comprises iron powder, activated carbon, bentonite, diatomite and zinc oxide, and the mass ratio is 80-95%:1-3%:2-10%:1-6%:0.5-1%.

3. The method for comprehensive treatment of acid mine drainage water according to claim 2, characterized in that, The amount of the reducing iron powder system reagent is added in an amount of 1.4-2.0 times the theoretical reaction amount of iron powder with copper in the acid mine drainage, based on the iron powder content.

4. The method for comprehensive treatment of acid mine drainage water according to claim 1, characterized in that, In step S1, the first pH regulator is one or more of lime, sodium carbonate, sodium hydroxide and calcium carbide residue.

5. The method for comprehensive treatment of acid mine drainage water according to claim 1, characterized in that, In step S2, the reducing agent is one or more of sodium sulfite, thiosulfate, sodium metabisulfite and citric acid; and the grade of copper in the second pressure filtration residue is ≥40%.

6. The method for comprehensive treatment of acid mine drainage water according to claim 1, characterized in that, In step S3, the oxidizing agent is air or hydrogen peroxide, and the second pH regulator is lime or calcium carbide residue.

7. The method for comprehensive treatment of acid mine drainage water according to claim 6, characterized in that, When the oxidizing agent is air, the gas-liquid volume ratio is 1:(4-5).

8. The method for comprehensive treatment of acid mine drainage water according to claim 6, characterized in that, When the oxidizing agent is hydrogen peroxide, the mass ratio of hydrogen peroxide to divalent iron ions in the solution is (0.60-6):

1.

9. The method for comprehensive treatment of acid mine drainage water according to claim 1, characterized in that, The flocculant is a non-ionic flocculant, and the addition amount is 0-15 g / m 3 .

10. The method for comprehensive treatment of acid mine drainage water according to claim 1, characterized in that, The pollutants in the acid mine drainage include one or more of copper, iron, zinc, lead, arsenic, manganese, nickel, cadmium, chromium and beryllium, and the concentration of copper ions is not less than 100 mg / L; and the temperature of the acid mine drainage is ≥5℃.

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