Method for treating cyanide-containing wastewater

Abstract

The present application relates to a kind of cyanide-containing wastewater treatment method, comprising the following specific steps: physical filtration;Permeation membrane filtration;PH value adjustment;Stripping treatment;Secondary PH value adjustment;Coagulation sedimentation;Biological activated carbon treatment;Wherein, the stripping tower used in step S4 is provided with waste liquid sprayer, multiple filler layers, and is connected with air blower outside at the bottommost filler layer;The bottom liquid collection area of stripping tower is connected with several liquid outlet branch pipes in parallel, the liquid outlet branch pipe is coaxially sleeved with superfine bubble air outlet pipe, the end of liquid outlet branch pipe in stripping tower is provided with open end, and is coaxially fixed with flow divider, the open end of flow divider is provided with spherical surface, and the end of flow divider on the side of superfine bubble air outlet pipe is provided with conical shape.The present application only needs to be stripped by one-stage stripping tower, which can ensure the absorption amount and efficiency of stripping, improve the treatment quality of cyanide-containing wastewater, ensure environmental protection, and effectively avoid secondary pollution.

Description

Technical Field

[0001] This invention relates to the field of wastewater treatment technology, specifically to a method for treating cyanide-containing wastewater. Background Technology

[0002] Gold cyanide processing plants generate large amounts of cyanide-containing wastewater during the gold beneficiation process. This wastewater contains not only highly toxic cyanide but also thiocyanates and heavy metal ions such as copper, zinc, and lead. If not effectively treated, it poses significant environmental risks. Currently, commonly used methods for treating cyanide-containing wastewater include acid recovery, alkaline chlorination, the Inco process, and sulfur dioxide treatment. Among these, the treatment of cyanide-containing wastewater requires multi-stage series acid stripping equipment. This involves spraying the wastewater onto a multi-layered packing layer of acidic solution and then introducing air. The process requires multiple stages of stripping equipment and a considerable treatment time to ensure sufficient contact between the wastewater and the acid, resulting in a relatively large overall equipment structure. However, as the amount of cyanide in the waste liquid decreases, the contact rate and absorption capacity also decrease, resulting in a large space occupied by the equipment and a relatively wasteful amount of equipment. Furthermore, for large volumes of waste liquid, simply relying on extending the treatment time is not only inefficient, but more importantly, it is difficult to cope with production pressure and demand. On the other hand, simply reducing the stripping equipment reduces the quality of the stripping treatment, resulting in incomplete treatment and still significant pollution.

[0003] Therefore, the research objective of this invention is to design a method for treating cyanide-containing wastewater that only requires a single-stage stripping tower to ensure the absorption capacity and efficiency of the stripping process, thereby improving the treatment quality of cyanide-containing wastewater, ensuring environmental protection, and effectively avoiding secondary pollution. Summary of the Invention

[0004] In view of the technical problems existing in the prior art, the present invention provides a method for treating cyanide-containing wastewater, which can effectively solve the technical problems existing in the prior art.

[0005] The technical solution of this invention is:

[0006] A method for treating cyanide-containing wastewater includes the following steps:

[0007] S1, Physical filtration: After being filtered by a bar screen, the cyanide-containing wastewater is sent to a sand filtration system to remove large particulate solid pollutants from the wastewater.

[0008] S2, Reverse osmosis membrane filtration: Wastewater is introduced into a reverse osmosis treatment system for reverse osmosis membrane treatment to obtain reverse osmosis concentrate;

[0009] S3, pH adjustment: Add sulfuric acid to the reverse osmosis concentrate to adjust the pH to between 2 and 3, and control the temperature of the reverse osmosis concentrate at 30-40℃;

[0010] S4, stripping treatment: the waste liquid obtained in step S3 at a temperature of 30-40℃ is pumped into the stripping tower, and air is introduced for acid stripping treatment. The stripped gas is absorbed by sodium hydroxide solution.

[0011] S5, Secondary pH adjustment: The waste liquid after acid stripping is passed into the adjustment tank and the pH is adjusted to between 8 and 10 with alkaline solution, and ozone is introduced.

[0012] S6, Coagulation and Sedimentation: The oxidized waste liquid is passed into the sedimentation tank, and a coagulant is added during the stirring process to carry out coagulation and sedimentation. After coagulation, the wastewater enters the sedimentation tank and is left to stand for 15-120 minutes.

[0013] S7, biological activated carbon treatment: The supernatant after precipitation is introduced into the biological activated carbon treatment system, and biological activated carbon treatment is carried out under the conditions of activated carbon packing, biofilm inoculum and air.

[0014] S8, the treated waste liquid enters the return water tank for return to the production process or discharge in compliance with standards;

[0015] In step S4, the stripping tower has numerous waste liquid nozzles distributed at its top. Multiple packing layers are spaced vertically below the waste liquid nozzles inside the stripping tower, with a blower connected outwards from the bottommost packing layer. A collection area is located at the bottom of the stripping tower, with a main outlet pipe connected outwards from one side of each collection area. Several branch outlet pipes are connected in parallel at the inlet end of the main outlet pipe, and these branch outlet pipes are installed side-by-side at intervals in the collection area of ​​the stripping tower. A corresponding microbubble outlet pipe is coaxially fitted inside the end of each branch outlet pipe that is not connected to the stripping tower. This microbubble outlet pipe extends outwards and connects to an external microbubble generator. The end of each branch outlet pipe inside the stripping tower is open and coaxially fixed with a corresponding distributor. The distributor is spherical at the open end of the branch outlet pipe and conical at the end on the side of the microbubble outlet pipe.

[0016] The alkaline solution in step S5 is sodium hydroxide or lime milk, and the coagulant in step S6 is a polymeric inorganic salt coagulant or a polymeric inorganic salt solution with a mass fraction of 10%-30%.

[0017] The biological activated carbon treatment system in step S6 is an upflow or downflow reaction tank. The bottom of the tank is equipped with a water distribution device and an aeration device. Above the aeration device is an activated carbon packing layer, with the carbon content accounting for 1 / 5-4 / 5 of the reactor volume. The biofilm-forming bacteria are nitrifying bacteria and nitrifying bacteria or cyanide-reducing bacteria. The biofilm formation method is either artificial addition of bacteria or dynamic cultivation for natural biofilm formation. The gas-liquid ratio is 1-15:1, and the biological activated carbon treatment time is 30-120 minutes.

[0018] In step S4, the spherical end of the distributor in the stripping tower has multiple radially arranged positioning rods distributed circumferentially. The two ends of the positioning rods are fixedly installed on the inner side wall of the liquid outlet pipe and the spherical end of the distributor.

[0019] The waste liquid nozzle is connected to the waste liquid outlet in step S3 via a corresponding liquid pump and a liquid guide valve. The main outlet pipe is equipped with a corresponding outlet valve and an outlet pump. The liquid guide valve and outlet valve are automatic valves and are electrically connected to the control system via the liquid pump, outlet pump, blower, and microbubble generator.

[0020] In step S6, a corresponding cover is fixedly installed on the upper part of the sedimentation tank. The cover is equipped with a feed pipe and a liquid inlet pipe. Supernatant outlet pipes and discharge pipes are respectively installed on the middle side and bottom of the sedimentation tank. A corresponding stirring shaft is rotatably installed on the lower side of the cover. Several staggered stirring rods are fixedly installed on the stirring shaft from top to bottom. A V-shaped stirring element is installed at the end of each stirring rod via a sleeved tubular flexible component, and the V-shaped opening of the stirring element is adjustable. The inner surfaces of the stirring element and the stirring rods are... The sides are respectively equipped with matching triggers and micro switches. When the V-shaped opening of the stirring component opens, the trigger fixedly installed on the stirring component moves towards the stirring rod as the end of the stirring component moves and touches the micro switch, which controls the stirring shaft to rotate in the opposite direction via electrical connection. A corresponding pressure sensor is installed on the stirring rod and embedded in the tubular flexible component. The detection end of the pressure sensor abuts against the connection between the stirring component and the tubular flexible component. When the pressure value detected by the pressure sensor is greater than F1, the forward and reverse motors stop.

[0021] The inlet pipe is connected to the waste liquid outlet in step S5 via a corresponding intermediate pump and intermediate valve.

[0022] The stirring component includes two plate-shaped blades hinged at their ends, which are tangentially fixed to the tubular flexible component, which is made of deformable rubber. When the two plate-shaped blades on the stirring component open, the tubular flexible component is stretched.

[0023] The stirring shaft is driven to rotate in both directions by a forward and reverse motor installed above the cover. When the micro switch is triggered, the forward and reverse motor rotates in the opposite direction.

[0024] The bottom side of the cover is fixedly connected to a corresponding mounting tube at a position corresponding to the stirring shaft. The stirring shaft is rotatably sleeved onto the mounting tube via a corresponding bearing. The sedimentation tank is supported and installed by corresponding support legs. A corresponding closing cover is installed on the feed pipe. Corresponding inlet valves, discharge valves, and discharge valves are fixedly installed on the liquid inlet pipe, supernatant outlet pipe, and discharge pipe, respectively.

[0025] Advantages of this invention:

[0026] 1) This invention treats the waste liquid from gold extraction by cyanide through physical filtration, permeate membrane filtration, pH adjustment, stripping treatment, secondary pH adjustment, coagulation and precipitation, and biological activated carbon treatment, so as to effectively reduce environmental pollution. In addition, only a single stripping tower is needed for the stripping treatment. In addition to the blower stripping inside the stripping tower, several microbubble generators are arranged side by side. The gas outlet pipe of the microbubble generator is coaxially sleeved in the corresponding liquid outlet pipe. The outlet pipe is open and coaxially fixed with a distributor with a spherical end and a conical end. In conjunction with the outward flow of waste liquid via the discharge pump, ultra-microbubbles are sprayed in the opposite direction, allowing for further and more thorough contact and dissolution of soluble air impurities in the flowing waste liquid. This effectively improves the stripping effect and quality, and shortens the stripping time. By combining the relative directions of water flow and bubble spray, the charged adsorption on the bubble surface, and the high density of ultra-microbubbles, the waste liquid is treated. Not only are soluble air pollutants stripped out, but some pollutants are also strongly oxidized and decomposed, further improving the treatment effect of cyanide-containing wastewater.

[0027] 2) The distributor of this invention is spherically shaped at the open end of the liquid outlet pipe and conically shaped at the end on the side of the microbubble outlet pipe. Multiple radially arranged positioning rods are distributed circumferentially at the spherical end of the distributor for fixing and installing it. The distributor can uniformly disperse and guide waste liquid outwards and uniformly disperse and guide microbubbles inwards, ensuring the uniformity and stability of waste liquid treatment.

[0028] 3) This invention further improves the sedimentation tank by installing several staggered stirring rods at intervals from top to bottom on a reversible stirring shaft. A V-shaped stirring element with an adjustable V-shaped opening angle is installed on the outside of the stirring rods via a sleeved tubular flexible component. When the waste liquid and coagulant are first added to the sedimentation tank, the resistance is low. The forward rotation of the stirring shaft drives one side of the V-shaped opening of the stirring element to rotate in the stirring direction, thereby driving the plate blades of the stirring element to fully mix the waste liquid and coagulant, greatly improving the mixing efficiency and coagulation and sedimentation effect. As the waste liquid slowly settles and the stirring resistance gradually increases, the angle of the V-shaped opening of the stirring element gradually increases. Furthermore, the trigger element fixed to the hinge end of the stirring element moves towards the tubular flexible component, activating a microswitch installed on the stirring rod. This electrically connects to a reversible motor to drive the stirring shaft to rotate in the reverse direction, causing the end of the V-shaped cone of the stirring element to face the rotation direction, thus reducing the contact area. The mixing process is carried out in an accumulating manner, which promotes smooth mixing. The inclined side of the agitator can guide the material and promote mixing, improving the mixing effect and efficiency of the sedimentation stage while enhancing practical effect. Furthermore, when the agitator rotates in the opposite direction, its V-shaped opening gradually narrows under the action of resistance and presses the tubular flexible component. When the pressure of the tubular flexible component reaches the pressure value limited by the pressure sensor, the electric drive motor stops mixing, and the waste liquid settles. Thus, the mixing can be controlled according to the coagulation of the waste liquid, making the treatment more precise and the effect better. It can achieve energy saving and automation, and is more suitable for gold cyanide enterprises with large waste liquid treatment volume and short treatment time.

[0029] 4) This invention uses two hinged plate blades connected in a V-shape to form a stirring element. When rotating in the forward direction, it ensures a sufficiently large stirring contact surface to improve stirring efficiency and coagulation effect. When rotating in the reverse direction, the V-shaped cone ensures a smaller contact surface and diverts the flow. The plate blades are mounted using a tubular flexible component made of rubber. This tubular flexible component has a stretchable and restorable deformation capacity, which is sufficient to adapt to the increase in the angle of the V-shaped opening of the stirring element when the resistance increases and the decrease in the angle of the V-shaped opening when rotating in the reverse direction. Through the intervention of this elastic component, the opening and compression of the stirring element can be controlled to ensure the practical effect of this invention. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the stripping tower, regulating tank, and settling tank in this invention.

[0031] Figure 2 for Figure 1 A cross-sectional diagram.

[0032] Figure 3 This is a cross-sectional view of the installation of the distributor and the liquid outlet pipe in this invention.

[0033] Figure 4This is a cross-sectional schematic diagram of the sedimentation tank in this invention (drive motor rotating forward).

[0034] Figure 5 for Figure 4 A schematic diagram of the state when the drive motor reverses.

[0035] Figure 6 This is a schematic diagram of the agitator (drive motor rotating forward).

[0036] Figure 7 for Figure 6 A schematic diagram of the state when the drive motor reverses.

[0037] In the attached diagram: 1. Stripping tower; 2. Waste liquid nozzle; 3. Packing layer; 4. Blower; 5. Liquid collection area; 6. Main liquid outlet pipe; 7. Sub-liquid outlet pipe; 8. Microbubble outlet pipe; 9. Diverter; 10. Positioning rod; 11. Liquid pump; 12. Liquid guide valve; 13. Liquid outlet valve; 14. Liquid outlet pump; 15. Sedimentation tank; 16. Cover; 17. Feed pipe; 18. Liquid inlet pipe; 19. Discharge pipe; 20. Stirring shaft; 21. Stirring rod; 22. Tubular flexible component; 23. Stirring component; 2301. Plate blade; 24. Trigger; 25. Microswitch; 26. Forward and reverse motor; 28. Support leg; 29. ​​Microbubble generator; 30. Supernatant outlet pipe; 31. Pressure sensor; 32. Regulating tank. Detailed Implementation

[0038] To facilitate understanding by those skilled in the art, the structure of the present invention will now be described in further detail with reference to the accompanying drawings:

[0039] refer to Figure 1-7 A method for treating cyanide-containing wastewater includes the following steps:

[0040] S1, Physical filtration: After being filtered by a bar screen, the cyanide-containing wastewater is sent to a sand filtration system to remove large particulate solid pollutants from the wastewater.

[0041] S2, Reverse osmosis membrane filtration: Wastewater is introduced into a reverse osmosis treatment system for reverse osmosis membrane treatment to obtain reverse osmosis concentrate;

[0042] S3, pH adjustment: Add sulfuric acid to the reverse osmosis concentrate to adjust the pH to between 2 and 3, and control the temperature of the reverse osmosis concentrate at 30-40℃;

[0043] S4, stripping treatment: the waste liquid obtained in step S3 at a temperature of 30-40℃ is pumped into stripping tower 1, and air is introduced for acid stripping treatment. The stripped gas is absorbed by sodium hydroxide solution.

[0044] S5, Secondary pH adjustment: The waste liquid after acid stripping is passed into the adjustment tank 32 and the pH is adjusted to between 8 and 10 with alkaline solution, and ozone is introduced.

[0045] S6, coagulation and sedimentation: The oxidized waste liquid is passed into sedimentation tank 15, and a coagulant is added during the stirring process to carry out coagulation and sedimentation. After coagulation, the wastewater enters the sedimentation tank and is left to stand for 15-120 minutes.

[0046] S7, biological activated carbon treatment: The supernatant after precipitation is introduced into the biological activated carbon treatment system, and biological activated carbon treatment is carried out under the conditions of activated carbon packing, biofilm inoculum and air.

[0047] S8, the treated waste liquid enters the return water tank for return to the production process or discharge in compliance with standards;

[0048] In step S4, the stripping tower 1 has numerous waste liquid nozzles 2 distributed at its top. Multiple packing layers 3 are spaced vertically below the waste liquid nozzles 2 inside the stripping tower 1, and a blower 4 is connected outwards from the bottom of the packing layer 3. A collection area 5 is located at the bottom of the stripping tower 1. A main outlet pipe 6 is connected outwards from one side of the collection area 5. Several branch outlet pipes 7 are connected in parallel at the inlet end of the main outlet pipe 6. The liquid collection area 5 of the stripping tower 1 is installed side by side at intervals. The end of the liquid outlet pipe 7 that is not connected to the stripping tower 1 is coaxially fitted with a corresponding microbubble outlet pipe 8. The microbubble outlet pipe 8 extends outward and connects to the microbubble generator 29 on the outside. The end of the liquid outlet pipe 7 located inside the stripping tower 1 is set in an open shape and is coaxially fixedly installed with a corresponding diverter 9. The diverter 9 located at the open end of the liquid outlet pipe 7 is set in a spherical shape and the end located on one side of the microbubble outlet pipe 8 is set in a conical shape.

[0049] This invention treats the waste liquid from gold extraction by cyanide through physical filtration, permeate membrane filtration, pH adjustment, stripping, secondary pH adjustment, coagulation and sedimentation, and biological activated carbon treatment, thereby effectively reducing environmental pollution. In the stripping process, only a single stripping tower 1 is required. In addition to the blower 4 installed in the stripping tower 1, several microbubble generators 29 are arranged side by side. The gas outlet pipe of the microbubble generator 29 is coaxially sleeved in the corresponding liquid outlet pipe 7. The outlet pipe 7 is open and coaxially fixed with a distributor 9 with a spherical end and a conical end. As the waste liquid flows outward through the discharge pump 14, ultra-microbubbles are sprayed inward in the opposite direction, allowing the air to come into full contact with and dissolve the soluble air impurities in the flowing waste liquid. This effectively improves the stripping effect and quality, and shortens the stripping time. By combining the relative directions of water flow and bubble spray, the charged adsorption on the bubble surface, and the high density of ultra-microbubbles, the waste liquid is treated. Not only are soluble air pollutants stripped out, but some pollutants are also strongly oxidized and decomposed, further improving the treatment effect of cyanide-containing wastewater.

[0050] The alkaline solution in step S5 is sodium hydroxide or lime milk, and the coagulant in step S6 is a polymeric inorganic salt coagulant or a polymeric inorganic salt solution with a mass fraction of 10%-30%.

[0051] The biological activated carbon treatment system in step S6 is an upflow or downflow reaction tank. The bottom of the tank is equipped with a water distribution device and an aeration device. Above the aeration device is an activated carbon packing layer 3, with the carbon content accounting for 1 / 5-4 / 5 of the reactor volume. The biofilm-forming bacteria are nitrifying bacteria and nitrifying bacteria or cyanide-reducing bacteria. The biofilm formation method is either artificial addition of bacteria or dynamic cultivation for natural biofilm formation. The gas-liquid ratio is 1-15:1, and the biological activated carbon treatment time is 30-120 minutes.

[0052] In step S4, the spherical end of the distributor 9 in the stripping tower 1 has a plurality of radially arranged positioning rods 10 distributed circumferentially. The two ends of the positioning rods 10 are fixedly installed on the inner side wall of the liquid outlet pipe 7 and the spherical end of the distributor 9.

[0053] The diverter 9 of this invention is spherically shaped at the open end of the liquid outlet pipe 7 and conical at the end on one side of the microbubble outlet pipe 8. Multiple radially arranged positioning rods 10 are distributed circumferentially at the spherical end of the diverter 9 for fixing and installing the diverter 9. The diverter 9 can uniformly disperse and guide waste liquid outwards and uniformly disperse and guide microbubbles inwards, ensuring the uniformity and stability of waste liquid treatment.

[0054] The waste liquid nozzle 2 is connected to the waste liquid outlet in step S3 via a corresponding liquid pump 11 and a liquid guide valve 12. The main outlet pipe 6 is equipped with a corresponding outlet valve 13 and an outlet pump 14. The liquid guide valve 12 and the outlet valve 13 are automatic valves and are electrically connected to the control system via the liquid pump 11, the outlet pump 14, the blower 4, and the microbubble generator 29.

[0055] In step S6, a corresponding cover 16 is fixedly installed on the upper part of the sedimentation tank 15. The cover 16 is equipped with a feed pipe 17 and a liquid inlet pipe 18. A supernatant outlet pipe 30 and a discharge pipe 19 are respectively provided on the middle side and bottom of the sedimentation tank 15. A corresponding stirring shaft 20 is rotatably installed on the lower side of the cover 16. Several staggered stirring rods 21 are fixedly installed on the stirring shaft 20 from top to bottom. A V-shaped stirring element 23 is installed at the end of each stirring rod 21 through a sleeved tubular flexible component 22, and the V-shaped opening of the stirring element 23 is adjustable. The stirring element 23 and the stirring rod 21 are opposite to each other. The inner sides are respectively provided with matching triggers 24 and microswitches 25. When the V-shaped opening of the stirring component 23 opens, the trigger 24 fixedly installed on the stirring component 23 moves towards the stirring rod 21 along with the end of the stirring component 23 and touches the microswitch 25, which controls the stirring shaft 20 to rotate in the opposite direction through electrical connection. A corresponding pressure sensor 31 is installed on the stirring rod 21 and embedded in the tubular flexible component 22. The detection end of the pressure sensor 31 abuts against the connection between the stirring component 23 and the tubular flexible component 22. When the pressure value detected by the pressure sensor 31 is greater than F1, the forward and reverse motor 26 stops.

[0056] The present invention further improves the sedimentation tank 15 by installing a number of staggered stirring rods 21 on the stirring shaft 20 that can rotate in both directions from top to bottom, and by installing a stirring element 23 in a V-shape with an adjustable V-shaped opening angle on the outside of the stirring rods 21 through a sleeved tubular flexible part 22. When the waste liquid and coagulant are first added to the settling tank 15, the resistance is low. The stirring shaft 20 rotates forward, causing one side of the V-shaped opening of the stirring element 23 to rotate in the stirring direction. This, in turn, causes the plate blades 2301 of the stirring element 23 to fully mix the waste liquid and coagulant, greatly improving the mixing efficiency and the coagulation and sedimentation effect. As the waste liquid slowly settles and the stirring resistance gradually increases, the angle of the V-shaped opening of the stirring element 23 will gradually increase. The trigger 24 fixed to the hinge end of the stirring element 23 will move towards the tubular flexible element 22 as the hinge end moves, triggering the micro switch 25 installed on the stirring rod 21. This electrically connects the forward and reverse motor 26 to drive the stirring shaft 20 to rotate in the reverse direction, causing the V-shaped cone end of the stirring element 23 to face the direction of rotation. The stirring direction is adjusted to reduce the contact area, promoting smooth stirring. The inclined side of the stirring component 23 can guide the material and promote mixing, improving the mixing effect and efficiency of the sedimentation stage while enhancing practical effect. Furthermore, when the stirring component 23 rotates in the opposite direction, its V-shaped opening will gradually narrow under the action of resistance and press against the tubular flexible component 22. When the pressure of the tubular flexible component 22 reaches the pressure value limited by the pressure sensor 31, the electric drive motor stops stirring, and the waste liquid settles. Thus, the stirring can be controlled according to the coagulation in the waste liquid, making the treatment more precise and the effect better. It can achieve energy saving and automation, and is more suitable for gold cyanide enterprises with large waste liquid treatment volume and short treatment time.

[0057] The inlet pipe 18 is connected to the waste liquid outlet in step S5 via a corresponding intermediate pump and intermediate valve.

[0058] The stirring component 23 includes two plate blades 2301 with their ends hinged together. The plate blades 2301 are tangentially fixed to the tubular flexible component 22. The tubular flexible component 22 is made of deformable rubber. When the two plate blades 2301 on the stirring component 23 are opened, the tubular flexible component 22 is stretched.

[0059] This invention uses two hinged plate blades 2301 connected in a V-shape to form a stirring element 23. When rotating forward, this ensures a sufficiently large contact area for stirring, improving stirring efficiency and coagulation. When rotating in the reverse direction, the V-shaped cone ensures a smaller contact area and diverts the flow. A tubular flexible member 22 made of rubber is used to mount the plate blades 2301. This flexible member has a stretchable and repositionable deformation capacity, sufficient to accommodate the increase in the angle of the V-shaped opening of the stirring element 23 when resistance increases and the decrease in the angle of the V-shaped opening when rotating in the reverse direction. Through the intervention of this elastic member, the opening and compression of the stirring element 23 are controlled, ensuring the practical effectiveness of this invention.

[0060] The stirring shaft 20 is driven to rotate in both directions by a forward and reverse motor 26 installed above the cover 16. When the micro switch 25 is triggered, the forward and reverse motor 26 rotates in the reverse direction.

[0061] The bottom side of the cover 16 is fixedly connected to a corresponding mounting tube 27 at a position corresponding to the stirring shaft 20. The stirring shaft 20 is rotatably sleeved onto the mounting tube 27 through a corresponding bearing. The sedimentation tank 15 is supported and installed by a corresponding support leg 28. A corresponding closing cover is installed on the feed pipe 17. A corresponding inlet valve, discharge valve and discharge valve are fixedly installed on the liquid inlet pipe 18, the supernatant outlet pipe 30 and the discharge pipe 19, respectively.

[0062] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A method for treating cyanide-containing wastewater, characterized in that, Includes the following steps: S1, Physical filtration: After being filtered by a bar screen, the cyanide-containing wastewater is sent to a sand filtration system to remove large particulate solid pollutants from the wastewater. S2, Reverse osmosis membrane filtration: Wastewater is introduced into a reverse osmosis treatment system for reverse osmosis membrane treatment to obtain reverse osmosis concentrate; S3, pH adjustment: Add sulfuric acid to the reverse osmosis concentrate to adjust the pH to between 2 and 3, and control the temperature of the reverse osmosis concentrate at 30-40℃; S4, stripping treatment: the waste liquid obtained in step S3 at a temperature of 30-40℃ is pumped into the stripping tower (1) and air is introduced for acid stripping treatment. The stripped gas is absorbed by sodium hydroxide solution. S5, Secondary pH adjustment: The waste liquid after acid stripping is introduced into the adjustment tank (32) and the pH is adjusted to between 8 and 10 with alkaline solution, and ozone is introduced; S6, coagulation and sedimentation: the oxidized waste liquid is passed into the sedimentation tank (15), and a coagulant is added during the stirring process to carry out coagulation and sedimentation. After coagulation, the wastewater enters the sedimentation tank and is left to stand for 15-120 minutes. S7, biological activated carbon treatment: The supernatant after precipitation is introduced into the biological activated carbon treatment system, and biological activated carbon treatment is carried out under the conditions of activated carbon packing, biofilm inoculum and air. S8, the treated waste liquid enters the return water tank for return to the production process or discharge in compliance with standards; In step S4, the stripping tower (1) has numerous waste liquid nozzles (2) distributed at its top. Multiple packing layers (3) are spaced vertically below the waste liquid nozzles (2) inside the stripping tower (1), and a blower (4) is connected outwards from the bottom of the packing layer (3). A collection area (5) is located at the bottom of the stripping tower (1), and a main outlet pipe (6) is connected outwards from one side of the collection area (5). Several branch outlet pipes (7) are connected in parallel at the inlet end of the main outlet pipe (6), and the branch outlet pipes (7) are connected to each other on the left and right sides. The liquid collection area (5) of the stripping tower (1) is installed side by side at right intervals. The end of the liquid outlet pipe (7) that is not connected to the stripping tower (1) is coaxially fitted with a corresponding microbubble outlet pipe (8). The microbubble outlet pipe (8) extends outward and connects to the microbubble generator (29) on the outside. The end of the liquid outlet pipe (7) inside the stripping tower (1) is set in an open shape and is coaxially fixedly installed with a corresponding distributor (9). The distributor (9) is set in a spherical shape at the open end of the liquid outlet pipe (7) and in a conical shape at the end on one side of the microbubble outlet pipe (8). In step S6, a stirring rod (21) is installed in the sedimentation tank (15) via a stirring shaft (20) that rotates in both directions. The end of the stirring rod (21) is fitted with a V-shaped stirring element (23) with an adjustable V-shaped opening angle via a sleeved tubular flexible part (22). When the waste liquid and coagulant are just added into the sedimentation tank (15) and the resistance is small, the stirring shaft (20) rotates in the forward direction, causing one side of the V-shaped opening of the stirring element (23) to rotate in the direction of stirring. A micro switch (25) is provided on the stirring rod (21). When the V-shaped opening of the stirring element (23) opens to the point of triggering the micro switch (25), the stirring shaft (20) is electrically controlled to rotate in the reverse direction, causing the end of the V-shaped cone of the stirring element (23) to face the direction of rotation. When the stirring element (23) rotates in the reverse direction and the V-shaped opening closes until the pressure of the tubular flexible part (22) reaches the limit pressure value F1, the forward and reverse motor (26) stops.

2. The method for treating cyanide-containing wastewater according to claim 1, characterized in that, The alkaline solution in step S5 is sodium hydroxide or lime milk, and the coagulant in step S6 is a polymeric inorganic salt coagulant or a polymeric inorganic salt solution with a mass fraction of 10%-30%.

3. The method for treating cyanide-containing wastewater according to claim 1, characterized in that, The biological activated carbon treatment system in step S6 is an upflow or downflow reaction tank. The bottom of the tank is equipped with a water distribution device and an aeration device. Above the aeration device is an activated carbon packing layer (3), with the amount of carbon accounting for 1 / 5-4 / 5 of the reactor volume. The biofilm-forming bacteria are nitrifying bacteria and nitrifying bacteria or cyanide-reducing bacteria. The biofilm formation method is to artificially add the bacteria for biofilm formation or to dynamically cultivate the bacteria for natural biofilm formation. The gas-liquid ratio is 1-15:1, and the biological activated carbon treatment time is 30min-120min.

4. The method for treating cyanide-containing wastewater according to claim 1, characterized in that, In step S4, the spherical end of the distributor (9) in the stripping tower (1) has a plurality of radially arranged positioning rods (10) distributed circumferentially. The two ends of the positioning rods (10) are fixedly installed on the inner side wall of the liquid outlet pipe (7) and the spherical end of the distributor (9).

5. The method for treating cyanide-containing wastewater according to claim 4, characterized in that, The waste liquid nozzle (2) is connected to the waste liquid outlet of step S3 through a corresponding liquid pump (11) and liquid guide valve (12). The main outlet pipe (6) is equipped with a corresponding outlet valve (13) and outlet pump (14). The liquid guide valve (12) and outlet valve (13) are automatic valves and are electrically connected to the control system with the liquid pump (11), outlet pump (14), blower (4) and microbubble generator (29).

6. The method for treating cyanide-containing wastewater according to claim 1, characterized in that, In step S6, a corresponding cover (16) is fixedly installed on the upper part of the sedimentation tank (15). The cover (16) is provided with a feed pipe (17) and a liquid inlet pipe (18). The middle side and bottom of the sedimentation tank (15) are respectively provided with a supernatant outlet pipe (30) and a discharge pipe (19). The stirring shaft (20) is rotatable and installed on the lower side of the cover (16). Several stirring rods (21) are fixedly installed on the stirring shaft (20) from top to bottom at intervals and in an alternating manner. The inner sides of the stirring element (23) and the stirring rods (21) are respectively provided with matching... The trigger (24) and micro switch (25) are installed on the stirring element (23). When the V-shaped opening of the stirring element (23) is opened, the trigger (24) fixedly installed on the stirring element (23) moves towards the stirring rod (21) along with the end of the stirring element (23) and touches the micro switch (25). A pressure sensor (31) for detecting the pressure of the tubular flexible element (22) is installed on the stirring element (23) and embedded in the tubular flexible element (22). The detection end of the pressure sensor (31) abuts against the connection between the stirring element (23) and the tubular flexible element (22).

7. The method for treating cyanide-containing wastewater according to claim 6, characterized in that, The inlet pipe (18) is connected to the waste liquid outlet in step S5 via a corresponding intermediate pump and intermediate valve.

8. The method for treating cyanide-containing wastewater according to claim 6, characterized in that, The stirring component (23) includes two plate blades (2301) with their ends hinged together. The plate blades (2301) are tangentially fixed to the tubular flexible component (22). The tubular flexible component (22) is made of deformable rubber. When the two plate blades (2301) on the stirring component (23) open, the tubular flexible component (22) is stretched.

9. A method for treating cyanide-containing wastewater according to claim 6, characterized in that, The stirring shaft (20) is driven to rotate in both directions by a forward and reverse motor (26) installed above the cover (16). When the micro switch (25) is triggered, the forward and reverse motor (26) rotates in the reverse direction.

10. A method for treating cyanide-containing wastewater according to claim 6, characterized in that, The bottom side of the cover (16) is fixedly connected to a corresponding mounting tube (27) at a position corresponding to the stirring shaft (20). The stirring shaft (20) is rotatably sleeved onto the mounting tube (27) through a corresponding bearing. The sedimentation tank (15) is supported and installed by a corresponding support leg (28). A corresponding closing cover is installed on the feed pipe (17). A corresponding inlet valve, discharge valve and discharge valve are fixedly installed on the liquid inlet pipe (18), the supernatant outlet pipe (30) and the discharge pipe (19).

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