A kind of abandoned pyrite area acid wastewater anti-silt ditch type processing system and method

Abstract

The present application relates to the technical field of abandoned pyrite area treatment, and particularly relates to a kind of abandoned pyrite area acid wastewater anti-silting ditch type processing system and method, including reaction ditch, the reaction ditch is divided into closed water inlet area, anoxic reaction zone, oxidation precipitation zone in sequence along the direction of acid wastewater communication by water distribution flower wall;The anoxic reaction zone is sequentially provided with neutralization reaction layer, barrier layer, cover layer from bottom to top;Water hole is provided on the water distribution flower wall, the water hole is below the top surface of the neutralization reaction layer, the liquid level of the closed water inlet area and the oxidation precipitation zone is higher than the water hole.The present application divides the reaction ditch into closed water inlet area, anoxic reaction zone, oxidation precipitation zone, avoids the oxidation of ferrous iron by anoxic environment of closed water inlet area and anoxic reaction zone, makes ferrous iron concentrated oxidation and precipitation in oxidation precipitation zone, realizes that neutralization, precipitation step subarea is completed, both can effectively treat iron-containing acid wastewater, and can solve the problem of too fast clogging and failure of reaction zone, ensure long-term operation of processing system.

Description

Technical Field

[0001] This invention relates to the field of abandoned pyrite mining area remediation technology, specifically to a ditch-type treatment system and method for preventing siltation and blockage of acidic wastewater from abandoned pyrite mining areas. Background Technology

[0002] The generation of acidic wastewater in abandoned pyrite mines is mainly due to the oxidation of pyrite. In the oxygen-deficient environment of mine shafts or slag heaps, the oxidation reaction usually proceeds slowly, but it is accelerated by the presence of water, oxygen, and sulfur-oxidizing bacteria. Acidic wastewater treatment often employs a reaction trench process using alkaline materials. The acidic wastewater seeping from the mine shafts or slag heaps is introduced into the reaction trench to react with alkali; this is a simple passive neutralization method. However, in an open, aerobic environment, ferrous sulfate is rapidly oxidized to ferric sulfate. As the pH increases, ferric hydroxide precipitates form, coating the surface of the alkaline materials involved in the reaction and accumulating continuously. This causes passivation of the reagents in the reaction trench, a decrease in reaction efficiency and rate, continuous sediment accumulation in the pores of the reagents, and blockage at the end of the reaction trench, ultimately leading to the paralysis of the treatment system and its inability to operate normally. Summary of the Invention

[0003] The purpose of this invention is to provide a ditch-type treatment system and method for preventing siltation and blockage of acidic wastewater from abandoned pyrite mining areas. This system can effectively treat iron-containing acidic wastewater and ensure long-term operation of the treatment system, avoiding rapid blockage and failure.

[0004] To achieve the above objectives, the technical solution of the present invention is a silt-prevention and anti-clogging ditch-type treatment system for acidic wastewater from abandoned pyrite mining areas, comprising a reaction ditch. The reaction ditch is divided into a closed inlet zone, an anoxic reaction zone, and an oxidation precipitation zone, which are sequentially connected along the flow direction of the acidic wastewater, by a water distribution wall. The anoxic reaction zone is provided with a neutralization reaction layer, a barrier layer, and a covering layer from bottom to top. The water distribution wall is provided with water passage holes, which are located below the top surface of the neutralization reaction layer. The liquid levels in the closed inlet zone and the oxidation precipitation zone are both higher than the water passage holes.

[0005] As one embodiment, the neutralization reaction layer is filled with limestone particles; the anoxic reaction zone is inclined downwards from the sealed water inlet zone to the oxidation precipitation zone.

[0006] As one embodiment, a drain pipe is provided at the bottom of the neutralization reaction layer. The starting end of the drain pipe is close to the sealed water inlet area, and the end extends below the liquid surface of the oxidation precipitation area. The drain pipe is inclined downward from its starting end to its end.

[0007] As one embodiment, the processing system further includes a rinsing device, wherein the beginning of the guide pipe is connected to the rinsing device through a beginning rinsing pipe, and the middle part of the guide pipe is connected to the rinsing device through a middle rinsing pipe.

[0008] As one embodiment, the flushing device includes a flushing fan and an air storage tank. The starting flushing pipeline and the intermediate flushing pipeline are both connected to the air outlet of the flushing fan, and the air inlet of the flushing fan is connected to the air storage tank. An air collection hood is provided at the top of the sealed water inlet area, and the air collection hood is connected to the air storage tank.

[0009] As one embodiment, the flushing device includes a flushing water pump, which is located in the sealed water inlet area. The initial flushing pipeline and the intermediate flushing pipeline are both connected to the outlet of the flushing water pump.

[0010] As one implementation method, the top of the sealed water inlet area is sealed, and the sealed water inlet area is divided into a first sealed water inlet area and a second sealed water inlet area by a first water-blocking wall. The end of the water inlet pipe extends below the liquid surface of the first sealed water inlet area, the second sealed water inlet area is connected to the neutralization reaction layer, and the liquid surface of the second sealed water inlet area is higher than the water passage hole.

[0011] As one embodiment, the oxidation precipitation zone is divided into a first oxidation precipitation zone and a second oxidation precipitation zone by a second water-retaining wall. The first oxidation precipitation zone is connected to the neutralization reaction layer, and the second oxidation precipitation zone is connected to the water outlet pipe. The top surface of the second water-retaining wall and the liquid level of the first oxidation precipitation zone are both higher than the water passage.

[0012] This invention also provides a method for preventing siltation and clogging of acidic wastewater from abandoned pyrite mining areas using a ditch-type treatment system described in any one of the above-mentioned methods. The method includes the following steps:

[0013] Iron-containing acidic wastewater from abandoned pyrite mine shafts and / or slag heaps is introduced into a closed inlet area under anoxic conditions. Then, it enters the neutralization reaction layer through water passages on the water distribution wall between the closed inlet area and the anoxic reaction zone, where a neutralization reaction takes place in an anoxic environment. Afterward, it enters the oxidation precipitation zone through water passages on the water distribution wall between the anoxic reaction zone and the oxidation precipitation zone, where ferrous iron in the wastewater is oxidized to ferric iron and precipitates.

[0014] As one implementation method, a small amount of precipitate generated is collected at the bottom of the neutralization reaction layer through a drainage pipe and discharged to the oxidation precipitation zone; the drainage pipe is periodically rinsed using a rinsing device, and each time the drainage pipe is rinsed, the beginning of the drainage pipe is rinsed first, and then the middle part of the drainage pipe is cleaned.

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

[0016] (1) This invention combines the iron-containing acidic wastewater generated by abandoned pyrite mines and / or slag heaps in an initial anoxic acidic state. The reaction channel is divided into a closed water inlet zone, an anoxic reaction zone, and an oxidation precipitation zone that are connected in sequence. The anoxic environment of the closed water inlet zone and the anoxic reaction zone prevents the oxidation of ferrous iron. The neutralization reaction layer in the anoxic reaction zone increases the pH value of the wastewater, so that ferrous iron is concentratedly oxidized in the oxidation precipitation zone and forms ferric hydroxide precipitate. The neutralization and precipitation are completed step by step and in separate zones. This invention can effectively treat iron-containing acidic wastewater and solve the problem of the neutralization reaction layer clogging and failing too quickly, ensuring the long-term operation of the treatment system.

[0017] (2) The upper part of the anoxic reaction zone of the present invention uses a barrier layer and a cover layer to closely fit the neutralization reaction layer, which can better isolate the external oxygen from the material exchange of the reaction zone, prevent ferrous salt from being converted into ferric salt and forming precipitation and blockage, and facilitate the replacement of the filling material; the neutralization reaction layer is filled with limestone reaction agent, which can reasonably control the pH value of the wastewater to stabilize to neutral, and control the formation of ferrous salt precipitation and blockage.

[0018] (3) The present invention sets up a drainage pipe at the bottom of the neutralization reaction layer to collect a small amount of suspended matter or precipitate formed in the neutralization reaction layer and drain it to the oxidation precipitation zone to avoid clogging of the neutralization reaction layer; at the same time, a flushing device is set up to flush the drainage pipe so that the silt in the drainage pipe is loosened and falls off and discharged into the oxidation precipitation zone with the wastewater flow.

[0019] (4) The sealed water inlet area of ​​the present invention adopts a fully enclosed water inlet and outlet to ensure the initial hypoxic environment; and the interior is divided into compartments to collect carbon dioxide generated in the hypoxic reaction zone as the gas source for the gas flushing of the hypoxic reaction zone guide pipe, and to provide water source for water flushing, so as to realize waste treatment and internal circulation of flushing medium.

[0020] (5) The oxidation precipitation zone of the present invention uses natural and cascading aeration to enhance the efficient conversion of ferrous salt into ferric precipitate under neutral conditions, and the precipitate is discharged with the sludge in a timely manner. Attached Figure Description

[0021] 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.

[0022] Figure 1 This is a schematic diagram of an anti-siltation ditch-type treatment system for acidic wastewater from abandoned pyrite mines provided in an embodiment of the present invention;

[0023] In the diagram: 1. Sealed water inlet area; 11. First sealed water inlet area; 12. Second sealed water inlet area; 13. First water-retaining wall; 14. Sealed manhole; 2. Anoxic reaction zone; 21. Neutralization reaction layer; 22. Barrier layer; 23. Covering layer; 24. Drainage pipe; 25. Initial flushing pipe; 26. Intermediate flushing pipe; 3. Oxidation and precipitation zone; 31. First oxidation and precipitation zone; 32. Second oxidation and precipitation zone; 33. Second water-retaining wall; 4. Water distribution wall; 5. Flushing fan; 6. Gas storage tank; 7. Gas collection hood; 8. Flushing water pump; 9. Inlet pipe; 10. Outlet pipe. Detailed Implementation

[0024] 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.

[0025] 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.

[0026] 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.

[0027] like Figure 1 As shown, this embodiment provides a silt-prevention and anti-clogging ditch-type treatment system for acidic wastewater from an abandoned pyrite mine area, including a reaction ditch. The reaction ditch is divided into a closed inlet zone 1, an anoxic reaction zone 2, and an oxidation precipitation zone 3, which are connected sequentially along the flow direction of the acidic wastewater, by a water distribution wall 4. The anoxic reaction zone 2 is provided with a neutralization reaction layer 21, a barrier layer 22, and a covering layer 23 from bottom to top. The water distribution wall 4 is provided with water passage holes, which are located below the top surface of the neutralization reaction layer 21. The liquid levels in the closed inlet zone 1 and the oxidation precipitation zone 3 are both higher than the water passage holes.

[0028] The iron-containing acidic wastewater generated from abandoned pyrite mine shafts and / or slag heaps is initially in an anaerobic acidic state, with a pH value generally between 2 and 3, and Fe... 2+ The ion concentration is generally 0.01–0.1 mol / L. In this embodiment, the anoxic, iron-containing acidic wastewater from mine shafts and / or slag heaps is introduced into the anoxic reaction zone 2 through a closed inlet zone 1 in an anoxic environment, which avoids the oxidation of ferrous iron. The iron-containing acidic wastewater undergoes a neutralization reaction in the neutralization reaction layer 21 in an anoxic environment, raising the pH value to 6–7. Ferrous iron may only precipitate in a small amount in the initial pH range, and under anoxic conditions, ferrous iron is not rapidly oxidized to ferric iron, thus controlling the formation of ferric hydroxide precipitation. Subsequently, the iron-containing neutral wastewater is discharged into the oxidation precipitation zone 3, where, under neutral and aerobic conditions, ferrous iron is rapidly oxidized to ferric iron, forming ferric hydroxide precipitation. The treatment system of this embodiment can achieve neutralization and precipitation in stages and zones, effectively treating iron-containing acidic wastewater and solving the problem of rapid blockage and failure of the reaction zone, ensuring the long-term operation of the treatment system. It is especially suitable for the treatment of small, dispersed mine shaft inflows or seepage from waste rock and slag heap slopes after source reduction.

[0029] In this optimized embodiment, the neutralization reaction layer 21 is filled with limestone particles; the anoxic reaction zone 2 is inclined downwards from the sealed inlet zone 1 to the oxidation precipitation zone 3. In this embodiment, the neutralization reaction layer 21 is filled with limestone particles as a neutralization agent. After acidic wastewater enters the neutralization reaction layer 21, the acidic substances react with the limestone to generate carbon dioxide gas. Because the anoxic reaction zone 2 is inclined downwards from the sealed inlet zone 1 to the oxidation precipitation zone 3, the generated carbon dioxide gas floats upwards along the slope of the neutralization reaction layer 21 through the gaps between the limestone particles to the top of the neutralization reaction layer 21 near the sealed inlet zone 1, and enters the sealed inlet zone 1 through the water passages on the water distribution wall 4 between the sealed inlet zone 1 and the anoxic reaction zone 2, accumulating in the upper space of the sealed inlet zone 1. This helps the sealed inlet zone 1 maintain an anoxic state for a long time, inhibiting the oxidation of ferrous iron in the iron-containing acidic wastewater. In one embodiment, the slope of the hypoxic reaction zone 2 is 0.01 to 0.05.

[0030] Furthermore, a drainage pipe 24 is provided at the bottom of the neutralization reaction layer 21. The starting end of the drainage pipe 24 is close to the sealed water inlet zone 1, and the ending end extends below the liquid surface of the oxidation precipitation zone 3. The drainage pipe 24 is inclined downward from its starting end to its ending end. In this embodiment, by providing a drainage pipe 24 at the bottom of the neutralization reaction layer 21, a small amount of suspended matter or precipitate formed in the neutralization reaction layer 21 can be collected and drained to the oxidation precipitation zone 3, avoiding clogging of the neutralization reaction layer 21.

[0031] Since the end of the drain pipe 24 extends through the water distribution wall 4 between the anoxic reaction zone 2 and the oxidation sedimentation zone 3 and below the liquid surface of the oxidation sedimentation zone 3, the anoxic environment of the anoxic reaction zone 2 can be further guaranteed. In addition, the part of the drain pipe 24 that extends into the oxidation sedimentation zone 3 is not perforated, and the end adopts a positive tee structure for water discharge. The positive tee structure can be a DN100 positive tee to avoid sediment clogging at the port of the drain pipe 24.

[0032] In one embodiment, the drainage pipe 24 is made of HDPE (high-density polyethylene) with a diameter of DN100. It is laid at a downward slope from the sealed water inlet zone 1 to the oxidation sedimentation zone 3 with a slope of 0.01. The limestone particles around the drainage pipe 24 have a large particle size, while the limestone particles away from the drainage pipe 24 have a small particle size.

[0033] In this embodiment, the top of the anoxic reaction zone 2 is uncovered to facilitate the replacement of the neutralization reaction layer 21. Specifically, the anoxic reaction zone 2 is an underground reinforced concrete structure, with the main body made of C30 strength concrete, using sulfate-resistant cement, and the inner wall is treated with anti-corrosion measures.

[0034] In one embodiment, the anoxic reaction zone 2 has a depth of 1.2m and a width of 1.0m, which can be widened according to the water volume. The length is extended according to the site conditions, and the inner bottom of the structure is connected to the sealed water inlet zone 1. The neutralization reaction layer 21 is filled with limestone with a particle size of 5-10mm, with a filling height of 0.5m and a filling width consistent with the width of the anoxic reaction zone 2.

[0035] Optimally, the treatment system further includes a flushing device. The starting end of the drain pipe 24 is connected to the flushing device via a starting flushing pipe 25, and the middle part of the drain pipe 24 is connected to the flushing device via a middle flushing pipe 26. Since a small amount of sludge may still exist in the drain pipe 24 after the treatment system of this embodiment has been running for a period of time, flushing the starting end and the middle part of the drain pipe 24 with the flushing device can loosen and dislodge the sludge in the drain pipe 24, allowing it to be discharged into the oxidation precipitation zone 3 with the wastewater flow.

[0036] Furthermore, the connection between the initial flushing pipe 25 and the guide drain pipe 24 is made using a 135° elbow, and the connection between the intermediate flushing pipe 26 and the guide drain pipe 24 is made using a 135° oblique tee. The location of the intermediate flushing pipe 26 is set according to the length of the anoxic reaction zone 2, with one set not exceeding 15m.

[0037] The upper ends of the starting flushing pipe 25 and the intermediate flushing pipe 26 extend 0.5m above the cover layer 23. The lower end of the starting flushing pipe 25 is connected to the guide pipe 24 by a 135° DN100 elbow, and the lower end of the intermediate flushing pipe 26 is connected to the guide pipe 24 by a 135° DN100 oblique tee. Valve #1 and valve #2 are respectively installed on the parts of the starting flushing pipe 25 and the intermediate flushing pipe 26 above the cover layer 23.

[0038] In one embodiment, the flushing device includes a flushing blower 5 and an air storage tank 6. The upper ends of the starting flushing pipe 25 and the intermediate flushing pipe 26 are respectively connected to the air outlet of the flushing blower 5 via connecting air pipes, and the air inlet of the flushing blower 5 is connected to the air storage tank 6. A gas collection hood 7 is provided at the top of the sealed water inlet area 1, and the gas collection hood 7 is connected to the air storage tank 6. In this embodiment, the flushing device does not use external air during air flushing, but uses carbon dioxide gas collected in the sealed water inlet area 1, which can keep the system in an oxygen-deficient state. Valves can be installed on each connecting air pipe to control the flushing process: first, the starting end of the guide pipe 24 is flushed through the starting flushing pipe 25, and then the middle part of the guide pipe 24 is flushed through the intermediate flushing pipe 26.

[0039] In one embodiment, the flushing device includes a flushing water pump 8, which is disposed in the sealed water inlet zone 1. The upper ends of the starting flushing pipe 25 and the intermediate flushing pipe 26 are respectively connected to the outlet of the flushing water pump 8 via connecting water pipes. In this embodiment, the flushing device does not use external oxygen-enriched water during water flushing, but instead uses oxygen-deficient water from the sealed water inlet zone 1, thus maintaining the system in an oxygen-deficient state. Furthermore, the water flushing employs a pulsed injection method to avoid significant fluctuations in the pH value of the wastewater in the oxidation precipitation zone 3. Valves can be installed on each connecting water pipe to control the flushing process: first, the starting end of the guide pipe 24 is flushed through the starting flushing pipe 25, and then the middle portion of the guide pipe 24 is flushed through the intermediate flushing pipe 26.

[0040] In another embodiment, the flushing device includes a flushing water pump 8, a flushing blower 5, and an air storage tank 6. The flushing water pump 8 is located in the sealed water inlet area 1. The upper ends of the starting flushing pipe 25 and the intermediate flushing pipe 26 are respectively connected to the outlet of the flushing water pump 8 via connecting water pipes. The upper ends of the starting flushing pipe 25 and the intermediate flushing pipe 26 are respectively connected to the outlet of the flushing blower 5 via connecting air pipes. The air inlet of the flushing blower 5 is connected to the air storage tank 6. A gas collection hood 7 is provided at the top of the sealed water inlet area 1. The gas collection hood 7 is connected to the air storage tank 6, and each connecting water pipe and each connecting air pipe is also equipped with a valve. In this embodiment, the flushing device uses a combination of water flushing and air flushing to enhance the flushing effect and simultaneously achieve an oxygen-deficient state in the system. Furthermore, after the carbon dioxide gas and wastewater flush the drain pipe 24, they enter the oxidation sedimentation tank, which can disturb the wastewater and increase the contact between the wastewater and oxygen.

[0041] Furthermore, the barrier layer 22 comprises, from bottom to top, a non-woven geotextile, a geomembrane, and another non-woven geotextile. The non-woven geotextile can be 200g / m². 2 The non-woven geotextile can be coated with a 1.5mm thick HDPE membrane.

[0042] In this embodiment, the barrier layer 22 is tightly attached to the neutralization reaction layer 21, and the edges are turned up 200mm along the groove wall. With the water level control of the sealed water inlet zone 1 and the oxidation precipitation zone 3 at both ends of the neutralization reaction layer 21, the neutralization reaction layer 21 can form a good sealed space.

[0043] Furthermore, the covering layer 23 is compacted and filled from the barrier layer 22 to the top of the anoxic reaction zone 2, achieving a density of over 90%. By adding the covering layer 23 to the barrier layer 22, a well-sealed space is further ensured for the neutralization reaction layer 21. In one embodiment, the covering layer 23 is made of clay and has a thickness of 0.5 m.

[0044] When the neutralization reaction layer 21 fails, the neutralizing agent can be replaced and the function of the neutralization reaction layer 21 can be restored by excavating the overburden layer 23 and exposing the barrier layer 22.

[0045] In this embodiment, the top of the sealed water inlet zone 1 is sealed to ensure an oxygen-deficient environment within it. Specifically, the sealed water inlet zone 1 is an integral sealed underground reinforced concrete structure, with the main body made of C30 strength concrete, using sulfate-resistant cement, and the inner wall treated with anti-corrosion measures. A sealed manhole 14 for maintenance can be provided at the top of the sealed water inlet zone 1.

[0046] In one embodiment, the sealed water inlet area 1 has a depth of 1.2m, a width of 1.0m, which can be expanded according to the water volume, and a length of 3.0m; the top of the sealed water inlet area 1 protrudes from the ground by no less than 0.2m.

[0047] In an optimized embodiment, the sealed water inlet zone 1 is divided into a first sealed water inlet zone 11 and a second sealed water inlet zone 12 by a first water-retaining wall 13. The end of the water inlet pipe 9 is sealed from the top of the first sealed water inlet zone 11 and extends below the liquid surface of the first sealed water inlet zone 11. The second sealed water inlet zone 12 is connected to the neutralization reaction layer 21, and the liquid surface of the second sealed water inlet zone 12 is higher than the water passage hole. Iron-containing acidic wastewater generated from the mine shafts and / or slag heaps of the abandoned pyrite mine is transported by gravity to the first sealed water inlet zone 11 through a pipeline in an oxygen-deficient environment. It overflows through the first water-retaining wall 13 to the second sealed water inlet zone 12, and then enters the oxygen-deficient reaction zone 2 through the water passage hole on the water distribution flower wall 4 between the second sealed water inlet zone 12 and the oxygen-deficient reaction zone 2. The carbon dioxide generated in the oxygen-deficient reaction zone 2 enters the second sealed water inlet zone 12 and accumulates in the upper space of the second sealed water inlet zone 12.

[0048] Furthermore, the flushing water pump 8 is installed in the first closed water inlet zone 11 to pump the anoxic iron-containing acidic wastewater in the first closed water inlet zone 11 to the anoxic reaction zone 2 for flushing; the gas collection hood 7 is installed at the top of the second closed water inlet zone 12 to collect the carbon dioxide gas discharged from the neutralization reaction layer 21 into the second closed water inlet zone 12 and guide it to the external gas storage tank 6.

[0049] In this embodiment, the sealed water inlet zone 1 can maintain a hypoxic state for a long time in an environment that isolates external air and is filled with carbon dioxide, effectively inhibiting the oxidation of ferrous iron in the iron-containing acidic wastewater.

[0050] In one embodiment, the length of the first sealed water inlet zone 11 is 2.0m, the length of the second sealed water inlet zone 12 is 1.0m, and the water distribution flower wall 4 between the second sealed water inlet zone 12 and the anoxic reaction zone 2 is provided with multiple water passage holes. The diameter of the water passage holes is 10-30mm, and the spacing between the holes is 30mm. The liquid level of the second sealed water inlet zone 12 is higher than the uppermost water passage hole on the water distribution flower wall 4 between the second sealed water inlet zone 12 and the anoxic reaction zone 2. The side wall of the area where the water passage holes are provided on the water distribution flower wall 4 is provided with a composite dense mesh to prevent the loss of the agent in the neutralization reaction layer 21. The first water retaining wall 13 is provided with an overflow hole, and the overflow hole is 500mm higher than the end of the water inlet pipe 9, so that the water inlet space is in an oxygen-deficient state.

[0051] In this embodiment, the oxidation precipitation zone 3 is uncovered, and the open environment provides an aerobic environment for ferrous oxidation. Specifically, the oxidation precipitation zone 3 is an underground reinforced concrete structure, with the main body made of C30 strength concrete, using sulfate-resistant cement, and the inner wall is treated with anti-corrosion measures.

[0052] In one embodiment, the oxidation precipitation zone 3 has a depth of 2.5m, a width of 1.0m, which can be widened according to the water volume, and a length of 3.0m; the top of the oxidation precipitation zone 3 is connected to the anoxic reaction zone 2.

[0053] In an optimized embodiment, the oxidation precipitation zone 3 is divided into a first oxidation precipitation zone 31 and a second oxidation precipitation zone 32 by a second water-blocking wall 33. The first oxidation precipitation zone 31 is connected to the neutralization reaction layer 21, and the second oxidation precipitation zone 32 is connected to the water outlet pipe 10. The top surface of the second water-blocking wall 33 and the liquid level of the first oxidation precipitation zone 31 are both higher than the water passage hole to maintain the anoxic reaction zone 2 in an anaerobic state. Neutralized ferrous wastewater, neutralized in the anoxic reaction zone 2, enters the first oxidation sedimentation zone 31 through the water passage on the water distribution wall 4 between the anoxic reaction zone 2 and the first oxidation sedimentation zone 31. In the open environment, some of the ferrous wastewater is oxidized to ferric iron. The ferric iron further forms ferric hydroxide precipitate in the neutral environment, which, along with other colloids, suspended solids, and heavy metal precipitates, is deposited at the bottom of the first oxidation sedimentation zone 31. The wastewater above the first oxidation sedimentation zone 31 is aerated by a cascade aeration process through the second baffle wall 33 into the second oxidation sedimentation zone 32. During the cascade aeration process, the ferrous iron comes into full contact with oxygen, causing the remaining ferrous iron in the wastewater to be further oxidized to ferric iron, forming ferric hydroxide precipitate, which, along with other colloids, suspended solids, and heavy metal precipitates, is deposited at the bottom of the second oxidation sedimentation zone 32. The supernatant at the top of the second oxidation sedimentation zone 32 is discharged through the effluent pipe 10.

[0054] In one embodiment, a plurality of water passage holes are provided on the water distribution wall 4 between the anoxic reaction zone 2 and the first oxidation precipitation zone 31. The diameter of the water passage holes is 10-30 mm and the spacing between the holes is 30 mm. The top surface of the second water baffle 33 is 100 mm higher than the uppermost water passage hole on the water distribution wall 4 between the anoxic reaction zone 2 and the first oxidation precipitation zone 31. A composite dense mesh is provided on the side wall of the area on the water distribution wall 4 where the water passage holes are provided to prevent the reagent of the neutralization reaction layer 21 from being lost. The drop height between the top surface of the second water baffle 33 and the liquid surface of the second oxidation precipitation zone 32 is 500 mm.

[0055] Furthermore, a cubic sludge pump pit with a side length of 0.5m is set at the bottom center of the first oxidation precipitation zone 31 and the second oxidation precipitation zone 32, and a slope of 0.01 is set around the sludge pump pit. The sludge in the sludge pump pit is periodically pumped out and transported for disposal.

[0056] Furthermore, the end of the outlet pipe 10 extending into the second oxidation precipitation zone 32 is a tee structure, specifically a DN100 HDPE tee, to prevent sediment from clogging the port of the outlet pipe 10. The outlet pipe 10 is 100mm lower than the center of the inlet pipe 9, with a slope of 0.01.

[0057] This embodiment also provides a method for preventing siltation and blockage of acidic wastewater from abandoned pyrite mines using a ditch-type treatment system described in any of the above embodiments. The method includes the following steps:

[0058] Iron-containing acidic wastewater from abandoned pyrite mine shafts and / or slag heaps is introduced into a closed inlet zone 1 under anoxic conditions. Then, it enters the neutralization reaction layer 21 through the water passages on the water distribution wall 4 between the closed inlet zone 1 and the anoxic reaction zone 2. The neutralization reaction takes place in the anoxic environment, raising the pH value to 6-7. Afterward, it enters the oxidation precipitation zone 3 through the water passages on the water distribution wall 4 between the anoxic reaction zone 2 and the oxidation precipitation zone 3. The ferrous iron in the wastewater is oxidized to ferric iron and forms a precipitate. The supernatant is discharged downstream.

[0059] The anti-siltation ditch-type treatment system for acidic wastewater from abandoned pyrite mines in this embodiment can be used alone or in combination along the mountain slope and seepage points. It can provide simple, long-term, low-consumption operation and maintenance for treating acidic wastewater from abandoned pyrite mines, and its layout is flexible and maintenance is simple.

[0060] Furthermore, a small amount of precipitate generated at the bottom of the neutralization reaction layer 21 is collected through the drain pipe 24 and discharged to the oxidation precipitation zone 3; the drain pipe 24 is periodically rinsed using a rinsing device, and each time the drain pipe 24 is rinsed, the beginning of the drain pipe 24 is rinsed first, and then the middle part of the drain pipe 24 is cleaned.

[0061] Specifically, an initial flushing pipe 25 and an intermediate flushing pipe 26 are connected to the beginning and middle of the drain pipe 24, respectively, and both the initial flushing pipe 25 and the intermediate flushing pipe 26 are connected to the flushing device. In this embodiment, the flushing device can use only water flushing, i.e., a flushing water pump 8 is installed in the first sealed water inlet zone 11 as the flushing device; the flushing device can also use only air flushing, i.e., an air collection hood 7 is installed in the second sealed water inlet zone 12, and an air storage tank 6 and a flushing fan 5 are installed outside the second sealed water inlet zone 12 as the flushing device; the flushing device can also use a combination of water flushing and air flushing.

[0062] The specific process for flushing the guide pipe 24 using a flushing device is as follows, taking the combined use of water flushing and air flushing as an example:

[0063] Air flushing process: Close valves #1 and #2, connect the outlet of flushing fan 5 to the starting flushing pipeline 25, start flushing fan 5, open valve #1, inject the carbon dioxide gas collected in the sealed water inlet zone 1 into the anoxic reaction zone 2, run for 3-5 minutes, and then stop flushing fan 5; close valve #1, connect the outlet of flushing fan 5 to the intermediate flushing pipeline 26, start flushing fan 5, open valve #2, inject the carbon dioxide gas generated in the sealed water inlet zone 1 into the anoxic reaction zone 2, run for 3-5 minutes, and then stop flushing fan 5;

[0064] Water flushing process: Close valves #1 and #2, connect the outlet of flushing water pump 8 to the starting flushing pipeline 25, open valve #1, start flushing water pump 8, and inject wastewater from the sealed inlet area 1 into the anoxic reaction zone 2 in a pulse manner by periodically opening and closing valve #1, 5-10 times, each time for 10-15 seconds, then stop flushing water pump 8; close valve #1, connect the outlet of flushing water pump 8 to the intermediate flushing pipeline 26, open valve #2, start flushing water pump 8, and inject wastewater from the sealed inlet area 1 into the anoxic reaction zone 2 in a pulse manner by periodically opening and closing valve #2, 5-10 times, each time for 10-15 seconds, then stop flushing water pump 8 and close valve #2.

[0065] The water flushing process and the air flushing process are each run once a week.

[0066] 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 non-clogging ditch type treatment system for acid waste water in a waste pyrite mine area, comprising a reaction ditch, characterized in that: The reaction ditch is divided into a closed water inlet area, an anoxic reaction area and an oxidation precipitation area in sequence along the flow direction of the acidic wastewater by a water distribution flower wall; the anoxic reaction area is provided with a neutralization reaction layer, a barrier layer and a cover layer in sequence from bottom to top; the water distribution flower wall is provided with a water passing hole, the water passing hole is below the top surface of the neutralization reaction layer, the liquid levels of the closed water inlet area and the oxidation precipitation area are higher than the water passing hole; the anoxic iron-containing acidic wastewater generated by the mine and / or slag heap of the abandoned pyrite area is introduced into the closed water inlet area under anoxic environment.

2. The acid wastewater anti-fouling trench type treatment system for abandoned pyrite mine area according to claim 1, characterized in that: The neutralization reaction layer is filled with limestone particles; the anoxic reaction area is downwardly inclined from the closed water inlet area to the oxidation precipitation area.

3. The acid wastewater anti-fouling trench type treatment system for abandoned pyrite mine area according to claim 2, characterized in that: The bottom of the neutralization reaction layer is provided with a guide and drainage flower pipe, the start end of the guide and drainage flower pipe is close to the closed water inlet area, the end end of the guide and drainage flower pipe extends below the liquid level of the oxidation precipitation area, and the guide and drainage flower pipe is downwardly inclined from the start end to the end end.

4. The acid wastewater anti-fouling trench type treatment system for abandoned pyrite mine area according to claim 3, characterized in that: The start end of the guide and drainage flower pipe is connected with the flushing device through a start end flushing pipeline, and the middle part of the guide and drainage flower pipe is connected with the flushing device through an intermediate flushing pipeline.

5. The acid wastewater anti-fouling trench type treatment system for abandoned pyrite mine area according to claim 4, characterized in that: The flushing device includes a flushing fan and an air storage tank, the start end flushing pipeline and the intermediate flushing pipeline are connected with the air outlet of the flushing fan, the air inlet of the flushing fan is connected with the air storage tank, and the top of the closed water inlet area is provided with an air collecting hood which is communicated with the air storage tank.

6. The acid wastewater anti-fouling trench type treatment system for abandoned pyrite mine area of claim 4 or 5, characterized in that: The flushing device includes a flushing water pump, the flushing water pump is arranged in the closed water inlet area, and the start end flushing pipeline and the intermediate flushing pipeline are connected with the water outlet of the flushing water pump.

7. The acid wastewater anti-fouling trench type treatment system for abandoned pyrite mine area according to claim 1, characterized in that: The top of the closed water inlet area is closed, the closed water inlet area is divided into a first closed water inlet area and a second closed water inlet area by a first water retaining wall, the end end of the water inlet pipe extends below the liquid level of the first closed water inlet area, the second closed water inlet area is communicated with the neutralization reaction layer, and the liquid level of the second closed water inlet area is higher than the water passing hole.

8. The acid wastewater anti-fouling trench type treatment system for abandoned pyrite mine area according to claim 1, characterized in that: The oxidation precipitation area is divided into a first oxidation precipitation area and a second oxidation precipitation area by a second water retaining wall, the first oxidation precipitation area is communicated with the neutralization reaction layer, and the second oxidation precipitation area is communicated with the water outlet pipe; the top surface of the second water retaining wall and the liquid level of the first oxidation precipitation area are higher than the water passing hole.

9. A method for preventing clogging of a trench for treating acidic waste water from a waste pyrite mine area, characterized by, The method comprises the following steps: The iron-containing acidic wastewater generated by the mine and / or slag heap of the abandoned pyrite area is introduced into the closed water inlet area under anoxic environment, then enters the neutralization reaction layer through the water passing hole on the water distribution flower wall between the closed water inlet area and the anoxic reaction area, and performs neutralization reaction in the anoxic environment, and then enters the oxidation precipitation area through the water passing hole on the water distribution flower wall between the anoxic reaction area and the oxidation precipitation area, the ferrous iron in the wastewater is oxidized into ferric iron, and a precipitate is formed.

10. The method for preventing siltation and blockage of acidic wastewater from abandoned pyrite mining areas as described in claim 9, characterized in that: A small amount of precipitate generated in the bottom of the neutralization reaction layer is collected by the drainage flower pipe and discharged to the oxidation precipitation area; the flushing device is used to periodically flush the drainage flower pipe, and the start of the drainage flower pipe is flushed first, and then the middle of the drainage flower pipe is cleaned.

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