A source treatment system and method for acidic wastewater from abandoned pyrite mine waste rock piles

Abstract

The present application relates to the technical field of abandoned pyrite mine area treatment, and particularly relates to a system and method for treating acid wastewater at the source of an abandoned pyrite mine area waste rock pile, comprising a seepage prevention structure arranged on the surface layer of the waste rock pile, a flood interception ditch arranged on the periphery of the waste rock pile, a blocking dam arranged on the downstream side of the waste rock pile, and an acid wastewater in-situ treatment pool arranged on the downstream side of the blocking dam; the acid wastewater in-situ treatment pool is located on the diffusion path of an acid wastewater pollution plume formed by underground seepage, and the concentrated water gushing point formed by dam body seepage of the blocking dam is in communication with the acid wastewater in-situ treatment pool through a flow guide device. The present application reduces the amount of acid wastewater by diverting the waste outside the waste rock pile; by arranging the acid wastewater in-situ treatment pool on the diffusion path of the acid wastewater pollution plume formed by underground seepage, the diffusion path of the acid wastewater pollution plume can be effectively cut off, and the intercepted acid wastewater and the water gushing formed by dam body seepage can be treated in-situ, thereby achieving source control of the acid wastewater.

Description

Technical Field

[0001] This invention relates to the field of abandoned pyrite mining area remediation technology, specifically to a source treatment system and method for acidic wastewater from abandoned pyrite mining area waste rock piles. Background Technology

[0002] Currently, historical pyrite mining areas suffer from significant problems of uncontrolled diffusion and pollution of acidic wastewater into groundwater, particularly in informal waste rock dumps. Atmospheric precipitation easily flows over uncovered waste rock piles, forming acidic wastewater that seeps into the untreated reservoir bottom, polluting surrounding soil and groundwater. How to treat this type of groundwater-generated acidic wastewater is a major challenge for the industry. To address these issues, it is necessary to design a source control system and method for acidic wastewater from abandoned pyrite mining waste rock piles to achieve source reduction and control of acidic wastewater. Summary of the Invention

[0003] The purpose of this invention is to provide a source treatment system and method for acidic wastewater from abandoned pyrite mine waste rock piles, which can reduce water volume at the source and prevent the spread of acidic wastewater pollution through in-situ multi-stage treatment, thereby achieving the goal of comprehensive treatment and source control of acidic wastewater.

[0004] To achieve the above objectives, the technical solution of the present invention is a source treatment system for acidic wastewater from waste rock piles in abandoned pyrite mines, comprising an anti-seepage structure installed on the surface of the waste rock pile, a flood interception ditch installed around the waste rock pile, a retaining dam installed downstream of the waste rock pile, and an in-situ acidic wastewater treatment pond installed downstream of the retaining dam; the in-situ acidic wastewater treatment pond is located on the diffusion path of the acidic wastewater pollution plume formed by underground seepage, and an inlet hole is provided on the upstream side of the in-situ acidic wastewater treatment pond; the concentrated water inflow point formed by seepage from the retaining dam body is connected to the in-situ acidic wastewater treatment pond through a diversion device.

[0005] As one implementation method, the acidic wastewater in-situ treatment tank is divided into a reduction zone, a neutralization zone, and a sedimentation zone that are connected sequentially along the direction of groundwater flow by a partition wall, and the water inlet is provided on the reduction zone.

[0006] As one embodiment, a hydrogen sulfide gas collection hood is provided at the top of the reduction zone. The hydrogen sulfide gas collection hood is connected to the sedimentation zone through a first pipe, and the end of the first pipe is located below the liquid surface of the sedimentation zone.

[0007] As one embodiment, the seepage-proof structure includes a passivation layer formed on the surface of the waste rock pile and a seepage-proof covering layer disposed on the surface of the passivation layer. The passivation layer is formed by mixing surface waste rock slag with calcium oxide.

[0008] As one implementation method, a gas distribution pipe is provided in the passivation layer, and the gas distribution pipe is connected to the hydrogen sulfide gas collection hood through a second pipe.

[0009] As one implementation method, a carbon dioxide collection hood is provided at the top of the neutralization zone, and the carbon dioxide collection hood is connected to the gas distribution pipe through a third pipe.

[0010] As one embodiment, the passivation layer has a thickness of 0.8 to 1.2 mm, and the impermeable covering layer has a thickness of 80 to 150 mm; multiple layers of the air distribution pipes are arranged from top to bottom in the passivation layer, and the distance between the uppermost layer of the air distribution pipes and the impermeable covering layer is 8 to 15 cm.

[0011] As one implementation method, an organic matter reduction layer is provided in the reduction zone. The organic matter reduction layer adopts a modular combination structure and is assembled from several organic matter reduction modules. The organic matter reduction module includes a flower tube, plugs at both ends of the flower tube, and organic matter and sulfate-reducing bacteria filled in the flower tube.

[0012] As one implementation method, a neutralization layer is provided in the neutralization zone. The neutralization layer adopts a modular combination structure and is assembled from several neutralizing agent modules. The neutralizing agent module includes a flower tube, plugs at both ends of the flower tube, and limestone filled in the flower tube.

[0013] As one implementation method, there are at least two acidic wastewater in-situ treatment ponds connected in parallel, which completely cover the diffusion path of the acidic wastewater pollution plume formed by underground seepage.

[0014] This invention also provides a method for source treatment of acidic wastewater from abandoned pyrite mine waste rock piles. The method involves implementing the aforementioned source treatment system at the abandoned pyrite mine waste rock pile site, directing both atmospheric precipitation outside and within the waste rock pile area into intercepting ditches for centralized downstream discharge; and introducing acidic wastewater from underground seepage and seepage from the retaining dam into an in-situ acidic wastewater treatment pond, which then sequentially enters a reduction zone, a neutralization zone, and a sedimentation zone. In the reduction zone, sulfates in the water are reduced to hydrogen sulfide by sulfate-reducing bacteria. In the neutralization zone, acidic substances in the acidic wastewater react with limestone to generate carbon dioxide. After hydrogen sulfide is generated in the reduction zone, it is first introduced into the waste rock pile to react with heavy metals in the pile to generate metal sulfides. Then, the carbon dioxide gas generated in the neutralization zone is introduced into the waste rock pile to react with the calcium oxide on the surface of the waste rock pile to generate a calcium carbonate passivation layer. Finally, hydrogen sulfide is introduced into the precipitation zone to react with heavy metals in the wastewater to generate metal sulfide precipitates.

[0015] Compared with the prior art, the present invention has the following beneficial effects:

[0016] (1) This invention achieves the separation of clean water and wastewater outside the waste rock pile, and collects unpolluted atmospheric rainfall outside the waste rock pile in a concentrated manner, thereby reducing the possibility of clean water and waste rock residue mixing from the source and reducing the amount of acidic wastewater generated.

[0017] (2) The present invention sets an anti-seepage structure on the surface to achieve complete isolation between wastewater and residual waste rock residue, avoid the continuous aggravation of pollution, and further reduce the amount of acidic wastewater generated.

[0018] (3) This invention adapts to local conditions and sets up an acidic wastewater in-situ treatment pond on the diffusion path of the acidic wastewater pollution plume formed by underground seepage. This can effectively cut off the diffusion path of the acidic wastewater pollution plume and treat the intercepted acidic wastewater in-situ. At the same time, it can divert the concentrated water inrush point formed by seepage of the barrier dam to the acidic wastewater in-situ treatment pond for in-situ treatment. This can not only achieve source control of acidic wastewater and avoid further diffusion of pollutants, but also solve the problems of land acquisition and site selection that are often encountered in engineering.

[0019] (4) In this invention, after acidic wastewater enters the acidic wastewater in-situ treatment tank, it passes through the reduction zone, neutralization zone and sedimentation zone in sequence. The pH of the wastewater increases and the acidity decreases. Multiple pollutants such as sulfate and heavy metals are reduced and controlled, which can achieve source control of acidic wastewater.

[0020] (5) This invention utilizes hydrogen sulfide generated in the reduction zone to enhance the treatment of heavy metals in waste rock piles and effluent, and utilizes carbon dioxide generated in the neutralization zone to enhance the passivation effect of waste rock slag, thereby achieving waste treatment with waste.

[0021] (6) The organic matter reduction layer in the reduction zone and the neutralization layer in the neutralization zone of the present invention are both modularly designed, which enables convenient and quick installation, cleaning and replacement, greatly improving work efficiency. Attached Figure Description

[0022] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0023] Figure 1 A schematic diagram of an acidic wastewater source treatment system for abandoned pyrite mine waste rock piles provided in an embodiment of the present invention;

[0024] Figure 2 This is a schematic diagram of the organic matter reduction module and the neutralizing agent module provided in an embodiment of the present invention;

[0025] In the diagram: 1. Waste rock pile; 2. Passivation layer; 3. Impermeable covering layer; 4. Barrier dam; 5. Upstream intercepting ditch; 6. Downstream intercepting ditch; 7. Aeration pipe; 8. Acidic wastewater plume; 9. In-situ treatment pond for acidic wastewater; 10. Reduction zone; 11. Neutralization zone; 12. Sedimentation zone; 13. Hydrogen sulfide gas collection hood; 14. Carbon dioxide gas collection hood; 15. Pipe; 16. Permeation hole; 17. Plug. Detailed Implementation

[0026] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0027] In the description of this invention, it should be understood that the terms "center", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0028] The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature; in the description of this invention, unless otherwise stated, "a plurality of" means two or more, and "a number" means at least one.

[0029] Example 1

[0030] like Figure 1 As shown, this embodiment provides a source treatment system for acidic wastewater from a waste rock pile in an abandoned pyrite mine. The system includes an anti-seepage structure on the surface of the waste rock pile 1, a flood interception ditch around the waste rock pile 1, a retaining dam 4 downstream of the waste rock pile 1, and an in-situ acidic wastewater treatment pond 9 downstream of the retaining dam 4. The in-situ acidic wastewater treatment pond 9 is located on the diffusion path of the acidic wastewater pollution plume 8 formed by underground seepage, and an inlet hole is provided on the upstream side of the in-situ acidic wastewater treatment pond 9. The concentrated water inflow point formed by seepage from the retaining dam 4 is connected to the in-situ acidic wastewater treatment pond 9 through a diversion device.

[0031] In this embodiment, an impermeable structure is installed on the surface of the waste rock pile 1 to prevent atmospheric precipitation from directly seeping into the interior of the waste rock pile 1, thereby reducing the generation of acidic wastewater and the spread of pollutants. At the same time, a flood interception ditch is set up outside the boundary of the waste rock pile 1 to divert atmospheric precipitation outside the waste rock pile 1 area and atmospheric precipitation within the area into the flood interception ditch, and centrally divert it to the existing downstream flood discharge system for discharge. This realizes the separation of clean water and sewage outside the waste rock pile 1, reducing the possibility of clean water mixing with waste rock slag from the source and reducing the amount of acidic wastewater generated.

[0032] Because the abandoned pyrite mine waste rock pile 1 contains a large amount of FeS2, when groundwater seeps into the waste rock pile 1, it will react with air and bacteria to form acidic wastewater with high content of heavy metals such as iron and manganese and sulfates. In this embodiment, by setting up an acidic wastewater in-situ treatment pond 9 on the diffusion path of the acidic wastewater pollution plume 8 formed by underground seepage, the diffusion path of the acidic wastewater pollution plume 8 can be effectively blocked, and the intercepted acidic wastewater can be treated in-situ. At the same time, the concentrated water inrush point formed by seepage from the barrier dam 4 can be diverted to the acidic wastewater in-situ treatment pond 9 for in-situ treatment. This can achieve source control of acidic wastewater and avoid further diffusion of pollutants. It is especially suitable for abandoned pyrite mine waste rock pile 1 with a history of long-term groundwater pollution caused by acidic wastewater seepage.

[0033] The intercepting ditch includes an upstream intercepting ditch 5 and a downstream intercepting ditch 6. The upstream intercepting ditch 5 is located on the upstream side and both sides of the waste rock pile 1, and is used to intercept unpolluted atmospheric precipitation outside the waste rock pile 1 area and divert it to the downstream for discharge. The downstream intercepting ditch 6 is located at the toe of the dam on the downstream side of the retaining dam 4, and its top surface is not higher than the top surface of the seepage-proof covering layer 3. It is used to intercept unpolluted atmospheric precipitation in the waste rock pile 1 area after it has been intercepted by the seepage-proof structure and divert it to the downstream for discharge.

[0034] In detail, the acidic wastewater in-situ treatment tank 9 is divided into a reduction zone 10, a neutralization zone 11, and a sedimentation zone 12, which are sequentially connected along the groundwater flow direction by a partition wall. Specifically, the reduction zone 10 is located upstream, the sedimentation zone 12 is located downstream, and the neutralization zone 11 is located between the reduction zone 10 and the sedimentation zone 12. The inlet is located on the upstream side of the reduction zone 10. The concentrated water inflow point formed by seepage from the retaining dam 4 is connected to the reduction zone 10 through a diversion device. The acidic wastewater first enters the reduction zone 10 for a reduction reaction to reduce sulfate, then enters the neutralization zone 11 for a neutralization reaction to increase alkalinity, and finally enters the sedimentation zone 12 to remove heavy metals. This comprehensive and effective treatment of the acidic wastewater reduces the risk of environmental pollution.

[0035] In one embodiment, a hydrogen sulfide gas collection hood 13 is installed at the top of the reduction zone 10 to collect hydrogen sulfide gas generated by sulfate-reducing bacteria under anaerobic conditions in acidic wastewater. The hydrogen sulfide gas collection hood 13 is connected to the sedimentation zone 12 via a first pipe, and the end of the first pipe is located below the liquid surface in the sedimentation zone 12. Since hydrogen sulfide gas is generated by the sulfate-reducing bacteria in the reduction zone 10, and hydrogen sulfide gas is a toxic and corrosive gas that will have a negative impact on the environment, this embodiment collects the generated hydrogen sulfide gas and introduces it into the sedimentation zone 12. This not only allows it to react with heavy metals in the wastewater to form metal sulfide precipitates, further reducing the concentration of heavy metals in the effluent, but also achieves waste-to-waste treatment.

[0036] In one embodiment, the seepage-proof structure includes a passivation layer 2 formed on the surface of the waste rock pile 1 and a seepage-proof covering layer 3 disposed on the surface of the passivation layer 2. The passivation layer 2 is formed by mixing the surface waste rock slag with calcium oxide. In this embodiment, calcium oxide, a remediation agent, is added to the surface waste rock slag. Calcium oxide can react with the moisture in the waste rock slag to generate calcium hydroxide, which not only reduces the moisture content of the waste rock slag and neutralizes the acidic substances in the waste rock slag, reducing the acidity of the waste rock slag, but also allows the generated calcium hydroxide to react with the carbon dioxide introduced later to form a calcium carbonate passivation layer 2 that coats the waste rock slag, thereby improving the physical and chemical stability of the waste rock slag. Preferably, the amount of calcium oxide used is 1-3% of the mass of the surface waste rock slag.

[0037] The specific construction method for the seepage prevention structure is as follows: First, the waste rock slag on the surface of the waste rock pile 1 is mixed evenly with a certain amount of the remediation agent calcium oxide to form a passivation layer 2 of a certain thickness. Then, the passivation layer 2 is leveled and compacted. Finally, concrete is sprayed onto the surface of the passivation layer 2 as a seepage prevention covering layer 3 to prevent surface runoff from entering the passivation layer 2. Further, the thickness of the passivation layer 2 is 0.8–1.2 m, and the thickness of the seepage prevention covering layer 3 is 80–150 mm. Preferably, the thickness of the passivation layer 2 is 1 m, and the thickness of the seepage prevention covering layer 3 is 100 mm.

[0038] In optimizing the above embodiment, approximately 5 kg of cement-based penetrating crystalline waterproofing material and 15%–25% fly ash are added to each cubic meter of concrete in the impermeable covering layer 3, resulting in a concrete strength grade of C30, an impermeability grade of P8, and a sulfate resistance grade of KS150. By adding appropriate amounts of cement-based penetrating crystalline waterproofing material and fly ash to the concrete, the waterproofing performance, strength, and durability of the impermeable covering layer 3 on the surface of the waste rock pile 1 in the abandoned pyrite mine area can be effectively improved.

[0039] In an optimized embodiment, a gas distribution pipe 7 is provided within the passivation layer 2, and the gas distribution pipe 7 is connected to the hydrogen sulfide gas collection hood 13 via a second pipe. This embodiment can also introduce hydrogen sulfide generated in the reduction zone 10 into the passivation layer 2, which can not only react with heavy metal ions on the surface of the waste rock slag to form metal sulfides, thereby stabilizing the heavy metal ions and reducing their migration and release into the surrounding environment, but also achieve waste-to-waste treatment. The gas distribution pipe 7 can be pre-embedded in the passivation layer 2 during the construction of the seepage-proof structure.

[0040] Furthermore, valve #1 can be installed on the first pipeline and valve #2 can be installed on the second pipeline. Through valve #1 and valve #2, hydrogen sulfide gas can be controlled to be transported to the sedimentation zone 12 and the waste rock pile 1, respectively.

[0041] In this embodiment, the material of the air distribution pipe 7 can be high-density polyethylene (HDPE). Multiple layers of air distribution pipes 7 can be arranged within the passivation layer 2, with multiple air distribution pipes 7 spaced apart in each layer. The number of layers of air distribution pipes 7 and the spacing between each layer can be designed according to the thickness of the passivation layer 2 and the specific conditions of the waste rock pile 1. In one embodiment, two layers of air distribution pipes 7 are arranged from top to bottom within the passivation layer 2. The distance between the upper layer of air distribution pipes 7 and the impermeable covering layer 3 is 8-15 cm, preferably 10 cm; the distance between the lower layer of air distribution pipes 7 and the impermeable covering layer 3 is 45-55 cm, preferably 50 cm.

[0042] In an optimized embodiment, a carbon dioxide collection hood 14 is installed at the top of the neutralization zone 11 to collect the generated carbon dioxide gas. The carbon dioxide collection hood 14 is connected to the gas distribution pipe 7 via a third pipe. Since wastewater reacts with limestone in the neutralization zone 11 to generate carbon dioxide gas, this embodiment collects the generated carbon dioxide gas and introduces it into the passivation layer 2 of the waste rock pile 1. This not only reacts with the calcium hydroxide on the surface of the waste rock slag in the passivation layer 2 to form a calcium-based carbonate passivation layer 2 that encapsulates the waste rock slag, improving its physical and chemical stability and further controlling the pollution from residual waste residue, but also achieves waste-to-waste treatment.

[0043] Furthermore, valve #3 is installed on the third pipeline, through which the carbon dioxide gas can be controlled to be transported to waste rock pile 1.

[0044] In this embodiment, a hydrogen sulfide gas sensor can also be installed in the hydrogen sulfide gas collection hood 13 to monitor the concentration of hydrogen sulfide gas in the hydrogen sulfide gas collection hood 13 in real time; and a carbon dioxide gas sensor can be installed in the carbon dioxide gas collection hood 14 to monitor the concentration of carbon dioxide gas in the carbon dioxide gas collection hood 14 in real time.

[0045] In one embodiment, an organic matter reduction layer is provided within the reduction zone 10. This organic matter reduction layer adopts a modular assembly structure, consisting of several organic matter reduction modules. Each organic matter reduction module includes a perforated tube 15, plugs 17 at both ends of the perforated tube 15, and organic matter and sulfate-reducing bacteria filling the perforated tube 15. In this embodiment, the organic matter reduction layer is located at the bottom of the reduction zone 10 and has a height of not less than 1m. It is formed by stacking several organic matter reduction modules as needed and can be replaced periodically after the modules become clogged or fail. Each organic matter reduction module's perforated tube 15 is a cylinder with a diameter of 0.2m and a length of 1.0m, sealed at both ends by plugs 17. The material can be high-density polyethylene. The permeation holes 16 on the perforated tube 15 have a diameter of 10mm, and the porosity of the perforated tube 15 is 30%–50%. Figure 2 As shown; the organic matter filling the organic matter reduction module can be a mixture of peat, hay and soil, with a mass ratio of peat, hay and soil of 5:4:1. When acidic wastewater passes through the organic matter reduction layer, in an anaerobic environment, sulfate-reducing bacteria will reduce sulfate to hydrogen sulfide, thus reducing the sulfate content.

[0046] In one embodiment, a neutralization layer is provided within the neutralization zone 11. This neutralization layer employs a modular assembly structure, consisting of several neutralizing agent modules. Each neutralizing agent module includes a perforated tube 15, plugs 17 at both ends of the perforated tube 15, and limestone filling the perforated tube 15. In this embodiment, the neutralization layer is located at the bottom of the neutralization zone 11 and is formed by stacking several layers of neutralizing agent modules as needed. The modules can be periodically cleaned or replaced after clogging or failure. Each neutralizing agent module's perforated tube 15 is a cylinder with a diameter of 0.2m and a length of 1.0m, sealed at both ends by plugs 17. The material can be high-density polyethylene. The permeation holes 16 on the perforated tube 15 have a diameter of 10mm, and the porosity of the perforated tube 15 is 30%–50%. Figure 2 As shown; the neutralizing agent module is filled with limestone. When acidic wastewater passes through the neutralization layer, the acidic substances react with the limestone to generate carbon dioxide gas, which increases the alkalinity of the wastewater.

[0047] After a period of operation, the organic matter reduction layer in reduction zone 10 and the neutralization layer in neutralization zone 11 will become clogged, requiring regular cleaning or replacement. Previously, this required overall operation, consuming significant machinery and manpower, and taking a considerable amount of time. This embodiment miniaturizes and modularizes the organic matter reduction and neutralization layers, equipping them with lifting lugs for overall lifting. A small truck crane can be used to assist manual disassembly, cleaning, and replacement, greatly improving work efficiency. Because the acidic wastewater from pyrite reacts with calcium carbonate, hydrogen sulfide, etc., it produces sulfates, hydroxides, sulfides, etc., which adhere to the organic matter reduction module and neutralizing agent module. These modules need to be periodically lifted for cleaning. After rinsing, the rinsing water is discharged to a sludge-water separation tank, and the bottom sludge is periodically removed and transported for landfill.

[0048] In this embodiment, the acidic wastewater in-situ treatment tank 9 can be an underground reinforced concrete structure with its bottom extending at least 1m into the bedrock layer to ensure that the diffusion path of the acidic wastewater pollution plume 8 is completely covered and blocked, and the pollution plume will not diffuse to the downstream of the acidic wastewater in-situ treatment tank 9 from other directions without being treated by the acidic wastewater in-situ treatment tank 9. The acidic wastewater in-situ treatment tank 9 is divided into a reduction zone 10, a neutralization zone 11, and a sedimentation zone 12 of similar size by a partition wall. Each zone is a closed structure with a cover. The upstream side of the reduction zone 10 has an inlet hole with a diameter of 10 mm and an opening rate of 30% to 50%, which can be adjusted according to the groundwater flow. The bottom of the partition wall between the reduction zone 10 and the neutralization zone 11 has a through hole with a diameter of 10 mm and an opening rate of 30% to 50%, which can be adjusted according to the groundwater flow. The top surface of the reduction layer is above this through hole. The top of the partition wall between the neutralization zone 11 and the sedimentation zone 12 has a through hole with a diameter of 10 mm and an opening rate of 30% to 50%, which can be adjusted according to the groundwater flow. The upper part of the sedimentation zone 12 is the reaction zone, and the lower part is the sedimentation zone. The heavy metal ions in the wastewater react fully with the hydrogen sulfide gas generated and transported from the reduction zone 10 to form heavy metal sulfide precipitates that are deposited in the lower part. This part of the precipitate can be periodically removed and transported for landfill.

[0049] In the optimized embodiment, at least two acidic wastewater in-situ treatment ponds 9 are connected in parallel, completely covering the diffusion path of the acidic wastewater pollution plume 8 formed by underground seepage. Since multiple acidic wastewater in-situ treatment ponds 9 operate in parallel, each pond 9 can be individually shut down for system maintenance, sludge cleaning, or silt flushing. The flushing water source can utilize drainage from intercepting ditches, and the water pressure can fully utilize natural elevation differences or employ portable equipment. The resulting muddy water is collected in a mud-water separation pond.

[0050] Example 2

[0051] This invention also provides a method for treating acidic wastewater from abandoned pyrite mine waste rock piles, comprising the following steps:

[0052] At the abandoned pyrite mine waste rock pile 1, the acidic wastewater source treatment system provided in Example 1 was implemented. Atmospheric precipitation outside and within the waste rock pile 1 area was diverted into intercepting ditches and centrally discharged downstream. Acidic wastewater from underground seepage and seepage from the retaining dam 4 were introduced into an in-situ acidic wastewater treatment pond 9. Specifically, a retaining dam 4 was constructed downstream of the waste rock pile 1, and an intercepting ditches were constructed around the waste rock pile 1. The remaining waste rock debris was then leveled on-site. An anti-seepage structure is constructed on its surface, and an air-distribution pipe 7 is pre-buried. Then, the existing exposed area of ​​the waste rock pile 1 in the abandoned pyrite mine area is investigated, and the main seepage points are investigated, sampled and tested to clarify the pollution situation and determine the downstream pollution plume diffusion range. Based on the pollution plume diffusion range of the acidic wastewater formed by underground seepage as determined by the investigation, the location and number of acidic wastewater in-situ treatment ponds 9 are determined and constructed. Then, the concentrated water inflow points formed by seepage of the above-ground dam body are introduced into the acidic wastewater in-situ treatment ponds 9 by gravity through the diversion device.

[0053] After entering the acidic wastewater in-situ treatment tank 9, the wastewater sequentially enters the reduction zone 10, neutralization zone 11, and sedimentation zone 12. In the reduction zone 10, sulfate-reducing bacteria reduce the sulfate in the acidic wastewater to hydrogen sulfide, thus reducing the sulfate content. In the neutralization zone 11, limestone reacts with the acidic substances in the wastewater to generate carbon dioxide gas, increasing the alkalinity of the wastewater. In the sedimentation zone 12, heavy metals are precipitated, thus removing the heavy metals.

[0054] After hydrogen sulfide is generated in reduction zone 10, valve #1 is first opened, and valves #2 and #3 are closed. The hydrogen sulfide gas generated in reduction zone 10 is introduced into passivation layer 2 of waste rock pile 1. It reacts with heavy metal ions on the surface of waste rock slag to form metal sulfides, thereby stabilizing the heavy metal ions. Then, valves #1 and #2 are closed, and valve #3 is opened. The carbon dioxide gas generated in neutralization zone 11 is introduced into passivation layer 2 of waste rock pile 1. It reacts with calcium hydroxide on the surface of waste rock slag in passivation layer 2 to form calcium carbonate passivation layer 2, which encapsulates the waste rock slag. Finally, valve #1 is closed, and valves #2 and #3 are opened. The hydrogen sulfide gas generated in reduction zone 10 is introduced into precipitation zone 12. It reacts with heavy metals in the wastewater to form metal sulfide precipitates, further reducing the concentration of heavy metals in the effluent.

[0055] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A system for treating acid wastewater from a waste rock pile in a waste pyrite mine area, characterized in that: The system comprises an impervious structure arranged on the surface layer of the waste rock pile, a flood interception ditch arranged on the periphery of the waste rock pile, a retaining dam arranged on the downstream side of the waste rock pile, and an acid wastewater in-situ treatment pool arranged on the downstream side of the retaining dam; the acid wastewater in-situ treatment pool is located on the diffusion path of the acid wastewater pollution plume formed by underground seepage, and a water inlet hole is arranged on the upstream side of the acid wastewater in-situ treatment pool; the concentrated water gushing point formed by the dam body seepage of the retaining dam is communicated with the acid wastewater in-situ treatment pool through a flow guide device; ​ The acid wastewater in-situ treatment pool is divided into a reduction zone, a neutralization zone and a precipitation zone by a partition wall, and the water inlet hole is arranged on the reduction zone; the impervious structure comprises a passivation layer formed on the surface layer of the waste rock pile and an impervious cover layer arranged on the surface of the passivation layer, and the passivation layer is formed by mixing the surface layer of waste rock slag with calcium oxide; a hydrogen sulfide gas collecting hood is arranged on the top of the reduction zone, and a gas distribution flower pipe is arranged in the passivation layer, and the gas distribution flower pipe is communicated with the hydrogen sulfide gas collecting hood through a second pipeline; a carbon dioxide gas collecting hood is arranged on the top of the neutralization zone, and the carbon dioxide gas collecting hood is communicated with the gas distribution flower pipe through a third pipeline.

2. The abandoned pyrite mine area waste rock pile acid wastewater source head treatment system according to claim 1, characterized in that: The hydrogen sulfide gas collecting hood is communicated with the precipitation zone through a first pipeline, and the end of the first pipeline is located below the liquid level of the precipitation zone.

3. The source treatment system for acidic wastewater from abandoned pyrite mine waste rock piles as described in claim 1, characterized in that: An organic matter reduction layer is arranged in the reduction zone, and the organic matter reduction layer adopts a modularized combined structure and is assembled by a plurality of organic matter reduction modules; the organic matter reduction module comprises a flower pipe, plugs arranged at both ends of the flower pipe, and organic matter and sulfate-reducing bacteria filled in the flower pipe.

4. The abandoned pyrite mine area waste rock pile acid wastewater source treatment system according to claim 1, wherein: the abandoned pyrite mine area waste rock pile acid wastewater source treatment system is characterized by comprising: a waste rock pile acid wastewater source treatment system according to any one of claims 1 to 3. A neutralization layer is arranged in the neutralization zone, and the neutralization layer adopts a modularized combined structure and is assembled by a plurality of neutralization agent modules; the neutralization agent module comprises a flower pipe, plugs arranged at both ends of the flower pipe, and limestone filled in the flower pipe.

5. The abandoned pyrite mine area waste rock pile acid wastewater source treatment system according to claim 1, wherein: the abandoned pyrite mine area waste rock pile acid wastewater source treatment system is characterized by comprising: a waste rock pile acid wastewater source treatment system according to any one of claims 1 to 4. The acid wastewater in-situ treatment pool has at least two and is arranged in parallel, and completely covers the diffusion path of the acid wastewater pollution plume formed by underground seepage.

6. A method for treating acid wastewater from a waste rock pile in a waste pyrite mine area, characterized in that: The acid wastewater in-situ treatment pool has at least two and is arranged in parallel, and completely covers the diffusion path of the acid wastewater pollution plume formed by underground seepage. In the waste rock pile of the abandoned pyrite mine area, the abandoned pyrite mine area waste rock pile acid wastewater source treatment system is constructed, atmospheric precipitation outside the waste rock pile area and atmospheric precipitation in the waste rock pile area are respectively introduced into the flood interception ditch and concentratedly drained to the downstream for discharge; the acid wastewater formed by underground seepage and the gushing water formed by the dam body seepage of the retaining dam are introduced into the acid wastewater in-situ treatment pool and sequentially enter the reduction zone, the neutralization zone and the precipitation zone; the sulfate in the acid wastewater is reduced to hydrogen sulfide by the sulfate-reducing bacteria in the reduction zone, and the acidic substances in the acid wastewater react with the limestone in the neutralization zone to generate carbon dioxide; after the hydrogen sulfide is generated in the reduction zone, the hydrogen sulfide is first introduced into the waste rock pile to react with the heavy metals in the pile body to generate metal sulfides, then the carbon dioxide gas generated in the neutralization zone is introduced into the waste rock pile to react with the calcium oxide on the surface layer of the waste rock pile to generate a calcium-based carbonate passivation layer, and the hydrogen sulfide is introduced into the precipitation zone to react with the heavy metals in the wastewater to generate metal sulfide precipitation.

Images