A device and method for processing ammonia-containing tail gas in noble metal refining

Abstract

The present application relates to the technical fields of ammonia-containing tail gas treatment, and discloses a noble metal refining ammonia-containing tail gas treatment device and method, which comprises a spray tower, a material gathering and gas guiding frame is fixedly installed in the middle of the inner cavity of the spray tower, and a front end treatment assembly is arranged below the material gathering and gas guiding frame in the spray tower. The ammonia-containing tail gas first completes primary spray dust removal and pre-ammonia removal in the adapter frame, preliminarily intercepts noble metal dust and most of the ammonia gas, then enters the inside of the material gathering and gas guiding frame, forms a closed atomization reaction zone through the circumferentially arranged atomizing nozzles, disperses the tail gas flow and realizes secondary ammonia removal and purification, and finally, the tail gas upflows through the multiple layers of packing plate regions, uses the spray liquid to dissolve and neutralize the residual ammonia gas, and realizes deep purification. The dust and ammonia molecules in the tail gas are fully removed, effectively solve the problems of complex composition, great treatment difficulty and non-standard emission of the noble metal refining ammonia-containing tail gas, and significantly improve the overall tail gas treatment quality and treatment stability.

Description

Technical Field

[0001] This invention relates to the field of ammonia-containing tail gas treatment technology, and in particular to an ammonia-containing tail gas treatment device and method for precious metal refining. Background Technology

[0002] In the recycling and smelting of hazardous chemical waste, it is often necessary to recover copper, tellurium, gold, platinum, palladium, silver, and waste precious metal catalysts through anode mud for comprehensive utilization. The silver leaching and platinum-palladium separation and purification processes require the addition of large amounts of ammonia water as complexing agents. The reduction section also adds hydrazine hydrate. The steam heating of the reactor, purification in the open fume hood, and material pressure filtration and cleaning will continuously release a large amount of ammonia-containing tail gas. At the same time, the system contains ultrafine silver powder, platinum-palladium precious metal particles, and inorganic salt crystallization salt spray, resulting in ammonia-containing tail gas being a composite waste gas containing both ammonia and solid metal dust. Since ammonia is polluting, it is necessary to treat and purify the ammonia in the tail gas.

[0003] Patent publication number CN119175002A discloses a waste gas spray tower for waste gas treatment, including a tower body, an air inlet pipe connected through the lower part of the tower body, a spray assembly located at the upper part of the tower body, a mixing assembly located between the spray assembly and the air inlet pipe inside the tower body, a drain assembly located at the bottom of the tower body, and an exhaust pipe located at the top of the tower body; the gas is distributed through the rotating mixing assembly, which will not cause blockage and does not require regular maintenance, thereby reducing labor intensity.

[0004] The above devices achieve the purpose of filtering fixed particles in the waste gas by directly passing the waste gas into the liquid at the bottom of the tower. However, when this treatment method is applied to the ammonia-containing tail gas of the precious metal smelting process, the tail gas of precious metal production carries a large amount of ultrafine silver powder, platinum-palladium particles and ammonium salt crystals. Relying on gravity natural sedimentation, only coarse particles with larger particle sizes can be intercepted. A large amount of fine precious metal powder is suspended in the circulating liquid phase for a long time and is difficult to separate and recover, resulting in serious loss of valuable metals. At the same time, a large number of fine particles are continuously mixed into the absorbent at the bottom of the tower, which will cause the impurity content of the absorbent to rise continuously, making it impossible to stably reuse it in the upstream silver leaching and platinum-palladium complexation reaction processes, reducing the recycling rate of ammonia resources. Therefore, this paper proposes a treatment device and method for ammonia-containing tail gas in precious metal refining to solve the above problems. Summary of the Invention

[0005] To address the aforementioned problems, this invention provides an ammonia-containing tail gas treatment device and method for precious metal refining.

[0006] The present invention provides an ammonia-containing tail gas treatment device and method for precious metal refining, which adopts the following technical solution: A device for treating ammonia-containing tail gas from precious metal refining includes a spray tower. A material-coagulating gas guide frame is fixedly installed in the middle of the inner cavity of the spray tower. A front-end processing component is provided below the material-coagulating gas guide frame inside the spray tower. A spraying mechanism is provided above the material-coagulating gas guide frame. An air inlet pipe is fixedly connected to the side wall of the spray tower. A first exhaust pipe is fixedly connected to the top of the spray tower. The front-end processing component includes a transfer frame. One end of the air inlet pipe is fixedly connected to the outside of the transfer frame. A receiving hopper is provided on the top of the transfer frame. The receiving hopper is located at the bottom of the material-gathering air guide frame. The receiving hopper penetrates the top wall of the transfer frame and is sealed and fixed to the transfer frame. A nozzle is fixedly connected to the bottom of the receiving hopper. A second exhaust pipe is fixedly connected to the side of the transfer frame opposite to the air inlet pipe. The second exhaust pipe extends to the space between the material-gathering air guide frame and the receiving hopper. A pump body is fixedly connected to the bottom of the inner cavity of the spray tower. An extension pipe is fixedly connected to the output end of the pump body. The extension pipe extends upward into the interior of the material-gathering air guide frame. Multiple atomizing nozzles are fixedly connected to the outside of the extension pipe. A filter box is provided on one side of the spray tower. A filter assembly for filtering the sprayed liquid is provided inside the filter box.

[0007] By adopting the above technical solution, the ammonia-containing exhaust gas first undergoes initial spray dust removal and pre-ammonia removal within the transfer frame, initially intercepting precious metal dust and most of the ammonia gas. Subsequently, the exhaust gas enters the interior of the aggregate guide frame, where a closed atomization reaction zone is formed by circumferentially arranged atomizing nozzles, dispersing the exhaust gas flow and achieving secondary ammonia removal and purification. Finally, the exhaust gas ascends through the multi-layer packing plate area, extending the gas-liquid contact time and contact area, using the spray liquid to dissolve and neutralize residual ammonia gas, achieving deep purification. This structure progressively treats the exhaust gas through a step-by-step, layered, and zoned approach, ensuring that dust and ammonia molecules in the exhaust gas are fully removed. This effectively solves the problems of complex composition, high treatment difficulty, and non-compliance with emission standards for ammonia-containing exhaust gas from precious metal refining, significantly improving the overall exhaust gas treatment quality and stability.

[0008] Preferably, the material-gathering air guide frame includes an annular pipe, an upper material-gathering hopper, and a lower air-gathering hopper. The upper material-gathering hopper and the lower air-gathering hopper are fixedly connected to the top and bottom of the annular pipe, respectively. The extension pipe extends into the interior of the annular pipe, the atomizing nozzle is located inside the annular pipe, and multiple atomizing nozzles are distributed at equal intervals along the circumference outside the extension pipe.

[0009] By adopting the above technical solution, the atomizing nozzle atomizes the liquid and sprays it into the annular pipe. The exhaust gas can be fully mixed with the atomized liquid after entering the annular pipe.

[0010] Preferably, a grid plate is fixedly connected inside the annular tube, one end of the extension tube is fixedly connected to the grid plate, and the grid plate is located above the atomizing nozzle.

[0011] By adopting the above technical solution, the mesh plate can disperse the passing liquid, and the dispersed liquid can quickly mix with the exhaust gas.

[0012] Preferably, the spray tower is equipped with a feeding pipe inside, which extends out of the spray tower and is fixedly connected to it. One end of the feeding pipe is fixedly connected to the bottom of the adapter frame. The filter assembly includes an annular filter frame. Two support plates are fixedly connected inside the filter box. The annular filter frame is located between the two support plates. A hollow tube is fixedly connected to one side wall of the annular filter frame towards the spray tower. The hollow tube passes through one of the support plates and is rotatably connected to it. A rotating shaft is fixedly connected to the other side of the annular filter frame. The rotating shaft passes through the other support plate and is rotatably connected to it. The feeding pipe extends into the filter box and is fixedly connected to it. One end of the feeding pipe is connected to the inside of the hollow tube through a sealed bearing. A drain pipe is fixedly connected to the bottom of the filter box. The drain pipe extends to the bottom of the spray tower cavity and is fixedly connected to the spray tower.

[0013] By adopting the above technical solution, the filtered liquid in the filter box flows back to the spray tower through the drain pipe.

[0014] Preferably, a motor is fixedly connected to a support plate located on one side of the hollow tube, a first gear is fixedly connected to the outside of the hollow tube, and a second gear is fixedly connected to the motor through an output shaft. The first gear is located on one side of the second gear and meshes with the second gear.

[0015] By adopting the above technical solution, the motor is used to drive the first gear to rotate.

[0016] Preferably, the filter box is provided with a sealing cover on the side away from the spray tower. The sealing cover extends into the filter box and is connected to the filter box by threads. The annular filter frame is provided with a cleaning port on the side facing the sealing cover. A mesh cover is provided on the side of the cleaning port. The mesh cover extends into the cleaning port and is adapted to the cleaning port. The mesh cover is connected to the annular filter frame by bolts.

[0017] By adopting the above technical solution, after removing the mesh cover, the impurities filtered out of the annular filter frame can be taken out.

[0018] Preferably, the spraying mechanism includes multiple packing plates and spray pipes. The spray pipes are fixedly assembled inside the spraying tower. The multiple packing plates are all located below the spray pipes. A reuse liquid collection pipe is fixedly connected to one side of the spraying tower. The inlet end of the reuse liquid collection pipe extends to the bottom of the inner cavity of the spraying tower.

[0019] By adopting the above technical solution, the liquid stored at the bottom of the spray tower can be extracted through the recycling pipe and reused in the upstream silver leaching and platinum-palladium complexation reaction processes, thereby improving the recycling rate of ammonia resources.

[0020] Preferably, a third exhaust pipe is provided on one side of the spray tower, and a box is fixedly connected between the first exhaust pipe and the third exhaust pipe. The box is filled with acidic activated carbon, which is loosely arranged inside the box. An end cap is fitted at the top opening of the box, and the end cap and the box opening form a detachable sealing connection. Multiple grid condensation plates are fixedly connected inside the first exhaust pipe.

[0021] By adopting the above technical solution, acidic activated carbon can adsorb and treat residual ammonia in exhaust gas.

[0022] A method for treating ammonia-containing tail gas from precious metal refining, comprising the use of the aforementioned ammonia-containing tail gas treatment device, and the steps of which are as follows: S1, Pre-spray dust removal and ammonia desulfurization During equipment operation, ammonia-containing tail gas generated from precious metal refining is stably introduced into the transfer frame at a flow rate of 0.6–1.0 m / s and a temperature of 35–55℃. The spray tower is equipped with a dilute sulfuric acid absorbent solution with a pH of 2.5–4.0 and a mass concentration of 1.2%–2.0%. The solution is sprayed downwards from the spray mechanism at a liquid-to-gas ratio of 8–12 L / m³. The sprayed absorbent solution passes sequentially through the packing plate, the aggregate guide frame, and the receiving hopper before entering the transfer frame. The ammonia-containing tail gas generated from precious metal refining is introduced into the transfer frame through the inlet pipe and then sprayed out, thus performing the initial spraying of the tail gas in the transfer frame and capturing precious metal dust and some ammonia gas within the tail gas. After the gas and liquid mix, the gas flows upwards through the second exhaust pipe, and the liquid falls and collects in the filter box to filter metal dust and other particulate matter. The filtered liquid flows back into the bottom of the spray tower for storage. The empty tower residence time in the tail gas tower is controlled at 2.5–4 seconds to ensure sufficient pretreatment reaction. S2, Layered Spray Purification The pump pumps the spray liquid stored at the bottom of the spray tower into the extension pipe, and sprays it onto the inner side of the annular pipe through the atomizing nozzle, forming uniform fine droplets of 40-80μm. The exhaust gas, after preliminary pretreatment by S1, flows upward and passes through the annular pipe, where it comes into full contact with and mixes with the atomized spray liquid inside the pipe, achieving secondary dust removal and ammonia removal. The mixed and purified exhaust gas continues to rise, and after being regulated and guided by the aggregate guide frame, it enters the upper spray mechanism. The absorbent liquid is continuously sprayed through the spray pipe, and the packing plate extends the gas-liquid contact time, fully absorbing the residual ammonia molecules in the exhaust gas, thus completing the deep purification treatment. S3, Terminal Activated Carbon Filtration After being purified by multi-stage spraying, the exhaust gas is discharged into the first exhaust pipe. During its flow within the pipe wall, the exhaust gas continuously dissipates heat through the heat-conducting pipe wall, achieving initial cooling. As the exhaust gas flows through the grid condenser plate inside the pipe, the staggered grid disperses and refines the airflow, increasing the contact area between water vapor and the low-temperature heat exchange surface. The water vapor undergoes sufficient heat exchange and liquefaction, and the condensed water droplets flow back to the spray tower along the pipe wall, thereby reducing the moisture content in the exhaust gas. The exhaust gas after passing through the first exhaust pipe finally enters the box filled with acidic activated carbon. The acidic activated carbon adsorbs trace amounts of escaped ammonia in the exhaust gas, and the clean exhaust gas is finally discharged through the third exhaust pipe in compliance with standards.

[0023] Preferably, the residence time of the exhaust gas in the activated carbon layer is controlled at 1.2 to 1.8 seconds. When the residual trace amount of water vapor in the exhaust gas causes the acidic activated carbon to become damp, or when the acidic activated carbon reaches saturation, the ineffective acidic activated carbon in the box is removed and replaced with a new carbon.

[0024] By adopting the above technical solution and easily replacing the acidic activated carbon body, the effective adsorption of residual ammonia in the exhaust gas can be guaranteed.

[0025] In summary, the present invention has the following beneficial technical effects: 1. A device and method for treating ammonia-containing tail gas from precious metal refining, wherein the ammonia-containing tail gas first undergoes initial spray dust removal and pre-ammonia removal within a transfer frame, initially intercepting precious metal dust and most of the ammonia gas; subsequently, the tail gas enters the interior of a material guide frame, where a closed atomization reaction zone is formed by circumferentially arranged atomizing nozzles, dispersing the tail gas flow and achieving secondary ammonia removal and purification; finally, the tail gas ascends through a multi-layer packing plate area, extending the gas-liquid contact time and contact area, using the spray liquid to dissolve and neutralize residual ammonia gas, achieving deep purification; this structure progressively treats the tail gas through a step-by-step, layered, and zoned approach, ensuring that dust and ammonia molecules in the tail gas are fully removed, effectively solving the problems of complex composition, high treatment difficulty, and non-compliance with emission standards for ammonia-containing tail gas from precious metal refining, and significantly improving the overall tail gas treatment quality and stability.

[0026] 2. A device and method for treating ammonia-containing tail gas from precious metal refining. The sprayed waste liquid is fed into an annular filter frame via a feeding pipe. The filter frame rotates continuously at low speed, causing internal impurities to continuously roll and loosen, preventing impurities from caking and clogging the filter surface. Simultaneously, slight centrifugal force accelerates the penetration of the chemical solution through the filter body, effectively improving filtration throughput and continuity. Furthermore, the rotating structure can rotate at high speed after shutdown to centrifuge and dry the impurities, achieving rapid solid-liquid separation, facilitating centralized cleaning and recycling of precious metal dust. The filtered clean sprayed liquid can be completely recycled back to the spray tower, significantly reducing chemical solution loss and production costs, while simultaneously achieving precious metal resource recovery and improving the overall economic efficiency and continuous operation capability of the equipment.

[0027] 3. A device and method for treating ammonia-containing tail gas from precious metal refining. During the flow of tail gas in the first exhaust pipe, heat is continuously dissipated and cooled. In conjunction with the grid condensing plates arranged in the rising section, the airflow is dispersed and refined, which greatly increases the contact area between water vapor and the low-temperature heat exchange surface. This allows the water vapor in the tail gas to be fully condensed and liquefied, and then flows back down along the pipe wall to the spray tower. This reduces the amount of water entering the acidic activated carbon body, thereby extending the service life of the acidic activated carbon body. The condensed tail gas is then subjected to trace ammonia adsorption by the acidic activated carbon body, which effectively delays the failure of activated carbon due to moisture, extends the activated carbon replacement cycle, ensures long-term stable and compliant emissions of the tail gas, and reduces equipment operation and maintenance costs. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the structure of the present invention; Figure 2 This is a cross-sectional view of the structure of the present invention; Figure 3 for Figure 2 Enlarged view of point A in the image; Figure 4 This is a cross-sectional view of the spray tower in this invention; Figure 5 This is a cross-sectional view of the first exhaust pipe in this invention; Figure 6 This is a cross-sectional view of the polymer air guide frame in this invention; Figure 7 This is a cross-sectional view of the filter box in this invention; Figure 8 This is a cross-sectional view of the annular filter frame of the present invention; Figure 9 This is a flowchart of the ammonia-containing tail gas treatment method in this invention.

[0029] Explanation of reference numerals in the attached drawings: 1. Spray tower; 2. Material gathering and air guiding frame; 201. Annular pipe; 202. Upper material gathering hopper; 203. Lower air gathering hopper; 204. Grid plate; 3. Front-end processing component; 301. Transfer frame; 302. Receiving hopper; 303. Spray head; 304. Second exhaust pipe; 305. Pump body; 306. Extension pipe; 307. Feeding pipe; 308. Atomizing nozzle; 4. Spraying mechanism; 401. Packing plate; 402. Spray pipe 5. Inlet pipe; 6. First exhaust pipe; 7. Filter box; 8. Filter assembly; 801. Annular filter frame; 802. Support plate; 803. Hollow tube; 804. Drain pipe; 805. Motor; 806. First gear; 807. Second gear; 808. Sealing cover; 809. Mesh cover plate; 9. Recycled liquid collection pipe; 10. Third exhaust pipe; 11. Box body; 12. Acidic activated carbon body; 13. End cap; 14. Mesh condenser plate. Detailed Implementation

[0030] The following is in conjunction with the appendix Figure 1 -Appendix Figure 9 The present invention will be described in further detail below.

[0031] like Figures 1 to 8 As shown, an ammonia-containing tail gas treatment device for precious metal refining according to an embodiment of the present invention includes a spray tower 1, a material guide frame 2 fixedly installed in the middle of the inner cavity of the spray tower 1, a front-end processing component 3 provided below the material guide frame 2 inside the spray tower 1, a spraying mechanism 4 provided above the material guide frame 2, an air inlet pipe 5 fixedly connected to the side wall of the spray tower 1, and a first exhaust pipe 6 fixedly connected to the top of the spray tower 1. The front-end processing component 3 includes a transfer frame 301. One end of the air inlet pipe 5 is fixedly connected to the outside of the transfer frame 301. A receiving hopper 302 is provided on the top of the transfer frame 301. The receiving hopper 302 is located at the bottom of the material gathering and air guiding frame 2. The receiving hopper 302 penetrates the top wall of the transfer frame 301 and is sealed and fixed to the transfer frame 301. A nozzle 303 is fixedly connected to the bottom of the receiving hopper 302. A second exhaust pipe 304 is fixedly connected to the side of the transfer frame 301 away from the air inlet pipe 5. The second exhaust pipe 304 extends between the material gathering and air guiding frame 2 and the receiving hopper 302. A pump body 305 is fixedly connected to the bottom of the inner cavity of the spray tower 1. An extension pipe 306 is fixedly connected to the output end of the pump body 305. The extension pipe 306 extends upward into the interior of the material gathering and air guiding frame 2. Multiple atomizing nozzles 308 are fixedly connected to the outside of the extension pipe 306. A filter box 7 is provided on one side of the spray tower 1. A filter assembly 8 is provided in the filter box 7 to filter the sprayed liquid.

[0032] The ammonia-containing tail gas generated from precious metal refining is introduced into the transfer frame 301 inside the spray tower 1 through the inlet pipe 5. It first undergoes initial dust removal and pre-ammonia removal treatment through the front-end processing component 3, effectively intercepting precious metal solid dust and large particulate impurities mixed in the tail gas, while also initially absorbing some ammonia. In specific operation, the spray liquid generated by the spraying mechanism 4 passes sequentially through the packing plate 401, the aggregate guide frame 2, and the receiving hopper 302 before entering the transfer frame 301. It contacts the tail gas that also enters the transfer frame 301, thus initially dissolving the ammonia in the tail gas. The liquid after contact with the tail gas passes through the transfer frame 301 and enters the filter box 7, where the filter component 8 filters and retains the precious metal solid dust and large particulate impurities it contains. The filtered liquid flows back into the bottom of the spray tower 1 for storage, while the initially dissolved tail gas is discharged through the second exhaust pipe 304 to the aggregate guide frame. Between the air frame 2 and the receiving hopper 302, the gas rises through the aggregated air guide frame 2 and is then sprayed and purified by the spraying mechanism 4. The pump body 305 can pump the liquid stored at the bottom of the spray tower 1 for reuse. It pumps the liquid into the extension pipe 306 and finally sprays it into the aggregated air guide frame 2 through the atomizing nozzle 308. At the same time, the liquid sprayed down by the spraying mechanism 4 also passes through the aggregated air guide frame 2. In this way, the atomized liquid and the liquid generated by the spraying mechanism 4 are re-contacted and dissolved with the tail gas entering the aggregated air guide frame 2. This achieves multi-stage treatment of tail gas by first absorbing the tail gas in the transfer frame 301, then atomizing and absorbing it again in the aggregated air guide frame 2, and finally being sprayed and absorbed by the spraying mechanism 4. On the basis of realizing the function of recycling the spraying liquid, it improves the treatment quality of ammonia-containing tail gas and avoids the problems of incomplete treatment of ammonia-containing tail gas, inability to circulate the liquid, and waste of precious metal dust.

[0033] The material-gathering air guide frame 2 includes an annular pipe 201, an upper material-gathering hopper 202 and a lower air-gathering hopper 203. The upper material-gathering hopper 202 and the lower air-gathering hopper 203 are fixedly connected to the top and bottom of the annular pipe 201, respectively. The extension pipe 306 extends into the interior of the annular pipe 201. The atomizing nozzle 308 is located inside the annular pipe 201. Multiple atomizing nozzles 308 are evenly distributed circumferentially outside the extension pipe 306.

[0034] In the specific implementation process, the lower gas-gathering hopper 203 can receive the rising exhaust gas from the pre-treatment below, gather and guide the scattered airflow, avoid local turbulence and short-circuiting of the exhaust gas, and ensure that the exhaust gas enters the annular pipe 201 evenly; the upper material-gathering hopper 202 can effectively receive the spray liquid falling from the upper spraying mechanism 4, concentrate and collect the spray liquid, and avoid the spray liquid from scattering and splashing and uneven accumulation. The extension pipe 306 extends into the annular pipe 201, and the atomizing nozzles 308 are evenly arranged circumferentially inside the annular pipe 201, which can form a uniform and closed atomizing spraying area inside the annular pipe 201. When the exhaust gas passes through the annular pipe 201, it can come into full-range and dead-angle contact with the atomized liquid mist, improving the initial atomization deammoniation and dust removal effect. The overall structure has three functions: regular airflow, liquid gathering and guiding, and closed atomization reaction.

[0035] A grid plate 204 is fixedly connected inside the annular tube 201, and one end of the extension tube 306 is fixedly connected to the grid plate 204. The grid plate 204 is located above the atomizing nozzle 308.

[0036] The function of the grid plate 204 is that when the spray liquid generated by the spray mechanism 4 enters the annular pipe 201 downwards, it will first pass through the grid plate 204. When passing through the grid plate 204, it will be divided into multiple streams by the holes on the grid plate 204, so as to disperse the spray liquid and fall down, which can further increase its contact speed with the exhaust gas and avoid the situation where the spray liquid falls in a concentrated manner and cannot mix with the exhaust gas quickly.

[0037] The spray tower 1 is equipped with a feeding pipe 307, which extends out of the spray tower 1 and is fixedly connected to it. One end of the feeding pipe 307 is fixedly connected to the bottom of the adapter frame 301. The filter assembly 8 includes an annular filter frame 801. Two support plates 802 are fixedly connected inside the filter box 7. The annular filter frame 801 is located between the two support plates 802. A hollow tube 803 is fixedly connected to one side wall of the annular filter frame 801, which is inclined towards the side wall of the spray tower 1. The hollow tube 803 passes through one of the support plates. A support plate 802 is rotatably connected to the support plate 802. A rotating shaft is fixedly connected to the other side of the annular filter frame 801. The rotating shaft passes through another support plate 802 and is rotatably connected to the support plate 802. The feeding pipe 307 extends into the filter box 7 and is fixedly connected to the filter box 7. One end of the feeding pipe 307 is connected to the inside of the hollow pipe 803 through a sealed bearing. A drain pipe 804 is fixedly connected to the bottom of the filter box 7. The drain pipe 804 extends into the bottom of the inner cavity of the spray tower 1 and is fixedly connected to the spray tower 1.

[0038] The annular filter frame 801 has densely distributed holes, allowing impurities to enter. Solid impurities are trapped inside the annular filter frame 801, while liquids flow out through the holes. The feeding pipe 307 can stably transport the waste liquid containing dust and impurities collected inside the transfer frame 301 to the filter box 7. Inside the filter box 7, double support plates 802 form a suspended support structure for the annular filter frame 801, ensuring that the annular filter frame 801 can rotate stably. One side of the annular filter frame 801 is connected to the hollow tube 803 and connected to the feeding pipe 307 through a sealed bearing, allowing the annular filter frame 801 to rotate as a whole while ensuring the sealed delivery of the liquid and preventing leakage. The other side has a rotating shaft that rotates in conjunction with the support plate 802, enabling the annular filter frame 801 to rotate coaxially. In actual operation, the waste liquid containing impurities is transported by... Feed pipe 307 and hollow tube 803 are fed into the annular filter frame 801. When the annular filter frame 801 is driven to rotate, a dynamic centrifugal filtration effect can be formed. The liquid can quickly penetrate the filter body under centrifugal action. Compared with traditional static filtration, the filtration throughput is larger and less prone to clogging. It can continuously and efficiently intercept precious metal dust and ammonium salt solid impurities in the spray liquid. The filtered clean spray liquid flows back to the bottom of the inner cavity of the spray tower 1 through the bottom drain pipe 804, realizing the continuous recycling of the spray liquid and reducing the loss of liquid. At the same time, the advantage of the annular filter frame 801 being able to rotate is that when the exhaust gas is treated and before the filtered impurities need to be removed, the annular filter frame 801 can be driven to rotate at high speed to use centrifugal force to dry the spray liquid entrained inside the impurities, thereby achieving solid-liquid separation, which is convenient for workers to remove and handle.

[0039] A motor 805 is fixedly connected to a support plate 802 located on one side of the hollow tube 803. A first gear 806 is fixedly connected to the outside of the hollow tube 803. A second gear 807 is fixedly connected to the motor 805 through an output shaft. The first gear 806 is located on one side of the second gear 807 and meshes with the second gear 807.

[0040] The motor 805 drives the second gear 807 to rotate, the second gear 807 drives the first gear 806 to rotate, the first gear 806 rotates and drives the hollow tube 803 to rotate, and the hollow tube 803 further drives the annular filter frame 801 to rotate.

[0041] A sealing cover 808 is provided on the side of the filter box 7 away from the spray tower 1. The sealing cover 808 extends into the filter box 7 and is connected to the filter box 7 by threads. A cleaning port is provided on the side of the annular filter frame 801 facing the sealing cover 808. A mesh cover plate 809 is provided on the side of the cleaning port. The mesh cover plate 809 extends into the cleaning port and is adapted to the cleaning port. The mesh cover plate 809 is connected to the annular filter frame 801 by bolts.

[0042] The sealing cover 808 is used to ensure that the filter box 7 is sealed inside, with no leakage of medicine or exhaust gas when it is working. The annular filter frame 801 has a cleaning port on the outside and is equipped with a detachable bolt-type mesh cover 809. During normal operation, the mesh cover 809 blocks the cleaning port to ensure that the filter frame is sealed for filtration. When a large amount of precious metal dust and solid impurities are trapped inside the filter frame, the outer sealing cover 808 can be opened and the mesh cover 809 can be further removed to directly clean and recycle the solid impurities and precious metal powder accumulated inside the filter frame.

[0043] The spraying mechanism 4 includes multiple packing plates 401 and spray pipes 402. The spray pipes 402 are fixedly assembled inside the spraying tower 1. Multiple packing plates 401 are located below the spray pipes 402. A reuse liquid collection pipe 9 is fixedly connected to one side of the spraying tower 1. The inlet end of the reuse liquid collection pipe 9 extends to the bottom of the inner cavity of the spraying tower 1.

[0044] The spray pipe 402 is arranged above the packing plate 401, which can uniformly spray the ammonia absorption solution downwards. The multi-layer packing plate 401 is laid in the spraying area, which can greatly increase the gas-liquid contact surface area, while extending the upward path and residence time of the tail gas, allowing the pre-treated tail gas to have full and long-term contact with the sprayed solution, deeply absorbing the residual ammonia in the tail gas, and ensuring that the tail gas purification meets the standards. The bottom end of the recycling liquid collection pipe 9 set on the side wall of the spray tower 1 extends to the bottom liquid storage area of ​​the tower, which can extract the circulating liquid at the bottom of the tower at any time according to the working conditions of the solution concentration, pH, and impurity content, and reuse it for the upstream silver leaching and platinum-palladium complexation reaction processes, thereby saving resources.

[0045] A third exhaust pipe 10 is provided on one side of the spray tower 1. A box 11 is fixedly connected between the first exhaust pipe 6 and the third exhaust pipe 10. The box 11 is filled with acidic activated carbon 12, which is loosely arranged inside the box 11. An end cap 13 is fitted at the top opening of the box 11, and the end cap 13 and the opening of the box 11 form a detachable sealed connection. Multiple grid condenser plates 14 are fixedly connected inside the first exhaust pipe 6.

[0046] The acidic activated carbon used in this device is modified activated carbon impregnated with dilute sulfuric acid. Unlike ordinary activated carbon, which relies solely on physical adsorption, the modified activated carbon has acidic active sites on its surface, allowing it to undergo both physical adsorption and chemical neutralization fixation with alkaline ammonia, resulting in a higher adsorption capacity than ordinary activated carbon. In the specific implementation process, columnar activated carbon is impregnated at a constant temperature with a 5%–8% concentrated dilute sulfuric acid solution and then dried before use to ensure the permeability of the exhaust gas and the duration of adsorption contact. The loose arrangement of the activated carbon ensures both its adsorption capacity for ammonia in the exhaust gas and allows the exhaust gas to exit through the pores between the activated carbon particles. The first exhaust pipe 6 uses an extended heat-conducting metal pipe, and the grid condenser plate 14 is arranged within the rising section of the first exhaust pipe 6. During the long-distance flow of the exhaust gas through the heat-conducting pipe, heat can be continuously dissipated to the external environment through the pipe wall, achieving initial cooling of the exhaust gas. Furthermore, when the exhaust gas flows through the grid condenser plate 14 in the rising section, the heat is further reduced... The staggered grid structure can disperse straight airflow and refine air masses, significantly increasing the contact area between exhaust gas water vapor and the low-temperature plate surface and pipe wall. The absorbed exhaust gas heat can be quickly conducted to the pipe wall and dissipated, maintaining a low-temperature heat exchange state for a long time. This promotes the rapid cooling of water vapor carried in the exhaust gas to the dew point for liquefaction. At the same time, the structural design of the grid condenser plate 14 arranged in the rising pipe section allows the liquid water droplets generated by condensation to flow back to the interior of the spray tower 1 by their own weight, preventing the condensate from flowing backward into the rear box 11. This effectively delays the acid activated carbon body 12 from becoming damp, caking, and failing. After condensation treatment, the exhaust gas enters the interior of the box 11, where the loosely arranged acid activated carbon body 12 performs physical and chemical adsorption on the trace amounts of residual ammonia that escape from the exhaust gas, completing the final fine purification. Finally, the clean exhaust gas is discharged from the third exhaust pipe 10 in compliance with standards. When it is necessary to replace the acid activated carbon body 12, the end cap 13 can be removed to quickly replace the acid activated carbon body 12 inside the box 11.

[0047] like Figure 9 As shown, a method for treating ammonia-containing tail gas from precious metal refining is described above. The method uses the aforementioned ammonia-containing tail gas treatment device to treat the ammonia-containing tail gas. The steps of this method are as follows: S1, Pre-spray dust removal and ammonia desulfurization During equipment operation, ammonia-containing tail gas generated from precious metal refining is stably introduced into the transfer frame 301 at a flow rate of 0.6–1.0 m / s and a temperature of 35–55°C. The spray tower 1 is equipped with a dilute sulfuric acid absorbent solution with a pH of 2.5–4.0 and a mass concentration of 1.2%–2.0%. The absorbent solution is sprayed downwards from the spray mechanism 4 at a liquid-to-gas ratio of 8–12 L / m³. The sprayed absorbent solution passes sequentially through the packing plate 401, the aggregate guide frame 2, and the receiving hopper 302 before entering the transfer frame 301. The ammonia-containing tail gas generated from precious metal refining is introduced into the transfer frame 301 through the inlet pipe 5 and then sprayed out. This performs the initial spraying of the tail gas in the transfer frame 301 and captures the precious metal dust and some ammonia in the tail gas. After the gas and liquid are mixed, the gas flows upward through the second exhaust pipe 304, and the liquid falls and collects in the filter box 7 to filter the metal dust and other particulate matter. The filtered liquid flows back into the bottom of the inner cavity of the spray tower 1 for storage. The empty tower residence time in the tail gas tower is controlled at 2.5 to 4 seconds to ensure that the pretreatment reaction is sufficient. S2, Layered Spray Purification Pump 305 pumps the spray liquid stored at the bottom of spray tower 1 into extension pipe 306, and sprays it onto the inner side of annular pipe 201 through atomizing nozzle 308, forming uniform fine droplets of 40-80μm. The exhaust gas, after preliminary pretreatment by S1, flows upward and passes through annular pipe 201, fully contacting and mixing with the atomized spray liquid inside the pipe to achieve secondary dust removal and ammonia removal. The mixed and purified exhaust gas continues to rise, and after being regulated and guided by aggregate guide frame 2, it enters the upper spray mechanism 4. The absorbent liquid is continuously sprayed through spray pipe 402, and the gas-liquid contact time is extended with the help of packing plate 401 to fully absorb residual ammonia molecules in the exhaust gas, completing the deep purification treatment. S3, Terminal Activated Carbon Filtration After the exhaust gas is purified by multi-stage spraying, it is discharged into the first exhaust pipe 6. During the flow of the exhaust gas in the first exhaust pipe 6, it continuously dissipates heat to the outside through the heat-conducting pipe wall, achieving preliminary cooling. When the exhaust gas flows through the grid condensing plate 14 in the pipe, the staggered grid disperses and refines the airflow, increases the contact area between water vapor and the low-temperature heat exchange surface, and the water vapor is fully liquefied through heat exchange. The condensed water droplets flow back to the spray tower 1 along the pipe wall, thereby reducing the moisture content in the exhaust gas. The exhaust gas after passing through the first exhaust pipe 6 is finally passed into the box 11 filled with acidic activated carbon body 12. The acidic activated carbon body 12 adsorbs the trace amount of ammonia gas that escapes in the exhaust gas. The clean exhaust gas is finally discharged through the third exhaust pipe 10 in compliance with standards.

[0048] The residence time of the exhaust gas in the activated carbon layer is controlled between 1.2 and 1.8 seconds. When the residual trace amount of water vapor in the exhaust gas causes the acidic activated carbon body 12 to become damp, or when the acidic activated carbon body 12 reaches saturation, the ineffective acidic activated carbon body 12 in the box 11 is removed and replaced with new carbon.

Claims

1. A device for treating ammonia-containing tail gas from precious metal refining, characterized in that: The system includes a spray tower (1), a material-coagulating air guide frame (2) is fixedly installed in the middle of the inner cavity of the spray tower (1), a front-end processing component (3) is provided below the material-coagulating air guide frame (2) inside the spray tower (1), a spraying mechanism (4) is provided above the material-coagulating air guide frame (2), an air inlet pipe (5) is fixedly connected to the side wall of the spray tower (1), and a first exhaust pipe (6) is fixedly connected to the top of the spray tower (1). The front-end processing component (3) includes a transfer frame (301). One end of the air inlet pipe (5) is fixedly connected to the outside of the transfer frame (301). A receiving hopper (302) is provided on the top of the transfer frame (301). The receiving hopper (302) is located at the bottom of the material gathering and air guiding frame (2). The receiving hopper (302) penetrates the top wall of the transfer frame (301) and is sealed and fixed to the transfer frame (301). A nozzle (303) is fixedly connected to the bottom of the receiving hopper (302). A second exhaust pipe (304) is fixedly connected to the side of the transfer frame (301) away from the air inlet pipe (5). The second exhaust pipe (304) extends between the aggregate guide frame (2) and the receiving hopper (302). A pump body (305) is fixedly connected to the bottom of the inner cavity of the spray tower (1). An extension pipe (306) is fixedly connected to the output end of the pump body (305). The extension pipe (306) extends upward to the inside of the aggregate guide frame (2). Multiple atomizing nozzles (308) are fixedly connected to the outside of the extension pipe (306). A filter box (7) is provided on one side of the spray tower (1). A filter assembly (8) for filtering the sprayed liquid is provided in the filter box (7).

2. The ammonia-containing tail gas treatment device for precious metal refining according to claim 1, characterized in that: The material-gathering air guide frame (2) includes an annular pipe (201), an upper material-gathering hopper (202) and a lower air-gathering hopper (203). The upper material-gathering hopper (202) and the lower air-gathering hopper (203) are fixedly connected to the top and bottom of the annular pipe (201) respectively. The extension pipe (306) extends into the interior of the annular pipe (201). The atomizing nozzle (308) is located inside the annular pipe (201). Multiple atomizing nozzles (308) are evenly distributed circumferentially outside the extension pipe (306).

3. The ammonia-containing tail gas treatment device for precious metal refining according to claim 2, characterized in that: The annular tube (201) is fixedly connected to a grid plate (204), and one end of the extension tube (306) is fixedly connected to the grid plate (204). The grid plate (204) is located above the atomizing nozzle (308).

4. The ammonia-containing tail gas treatment device for precious metal refining according to claim 1, characterized in that: The spray tower (1) is equipped with a feeding pipe (307) inside. The feeding pipe (307) extends out of the outside of the spray tower (1) and is fixedly connected to the spray tower (1). One end of the feeding pipe (307) is fixedly connected to the bottom of the adapter frame (301). The filter assembly (8) includes an annular filter frame (801). Two support plates (802) are fixedly connected inside the filter box (7). The annular filter frame (801) is located between the two support plates (802). A hollow tube (803) is fixedly connected to one side wall of the annular filter frame (801) towards the spray tower (1). The hollow tube (803) passes through the filter frame (801). A support plate (802) is rotatably connected to the support plate (802). A rotating shaft is fixedly connected to the other side of the annular filter frame (801). The rotating shaft passes through another support plate (802) and is rotatably connected to the support plate (802). The feeding pipe (307) extends into the filter box (7) and is fixedly connected to the filter box (7). One end of the feeding pipe (307) is connected to the inner side of the hollow tube (803) through a sealed bearing. A drain pipe (804) is fixedly connected to the bottom of the filter box (7). The drain pipe (804) extends to the bottom of the inner cavity of the spray tower (1) and is fixedly connected to the spray tower (1).

5. The ammonia-containing tail gas treatment device for precious metal refining according to claim 4, characterized in that: A motor (805) is fixedly connected to a support plate (802) located on one side of the hollow tube (803). A first gear (806) is fixedly connected to the outside of the hollow tube (803). A second gear (807) is fixedly connected to the motor (805) through an output shaft. The first gear (806) is located on one side of the second gear (807) and meshes with the second gear (807).

6. The ammonia-containing tail gas treatment device for precious metal refining according to claim 4, characterized in that: The filter box (7) is provided with a sealing cover (808) on the side away from the spray tower (1). The sealing cover (808) extends into the filter box (7) and is connected to the filter box (7) by threads. The annular filter frame (801) is provided with a cleaning port on the side of the sealing cover (808). A grid cover plate (809) is provided on the side of the cleaning port. The grid cover plate (809) extends into the cleaning port and is adapted to the cleaning port. The grid cover plate (809) is connected to the annular filter frame (801) by bolts.

7. The ammonia-containing tail gas treatment device for precious metal refining according to claim 1, characterized in that: The spraying mechanism (4) includes multiple packing plates (401) and spray pipes (402). The spray pipes (402) are fixedly assembled inside the spraying tower (1). Multiple packing plates (401) are located below the spray pipes (402). A reuse liquid collection pipe (9) is fixedly connected to one side of the spraying tower (1). The liquid inlet end of the reuse liquid collection pipe (9) extends to the bottom of the inner cavity of the spraying tower (1).

8. The ammonia-containing tail gas treatment device for precious metal refining according to claim 1, characterized in that: The spray tower (1) is provided with a third exhaust pipe (10) on one side. A box (11) is fixedly connected between the first exhaust pipe (6) and the third exhaust pipe (10). The box (11) is filled with acidic activated carbon (12). The acidic activated carbon (12) is loosely arranged inside the box (11). An end cap (13) is fitted at the top opening of the box (11). The end cap (13) and the opening of the box (11) form a detachable sealed connection. Multiple grid condenser plates (14) are fixedly connected inside the first exhaust pipe (6).

9. A method for treating ammonia-containing tail gas from precious metal refining, characterized in that: The steps of this method are as follows: S1, Pre-spray dust removal and ammonia desulfurization During equipment operation, the ammonia-containing tail gas generated from precious metal refining is stably introduced into the transfer frame (301) at a flow rate of 0.6-1.0 m / s and a temperature of 35-55℃. The spray tower (1) is equipped with a dilute sulfuric acid absorption solution with a pH value of 2.5-4.0 and a mass concentration of 1.2%-2.0%. The solution is sprayed downward from the spraying mechanism (4) under the condition of a liquid-to-gas ratio of 8-12 L / m³. The sprayed absorption solution passes through the packing plate (401), the aggregate guide frame (2), and the receiving hopper (302) in sequence before entering the transfer frame (301). In the process, the ammonia-containing tail gas generated from precious metal refining is introduced into the transfer frame (301) through the inlet pipe (5) and then sprayed out, thereby performing the initial spraying of the tail gas in the transfer frame (301) and capturing the precious metal dust and some ammonia in the tail gas. After the gas and liquid are mixed, the gas flows upward through the second exhaust pipe (304), and the liquid falls and collects in the filter box (7) to filter the metal dust and other particulate matter. The filtered liquid flows back into the bottom of the inner cavity of the spray tower (1) for storage. The empty tower residence time in the tail gas tower is controlled at 2.5 to 4 seconds to ensure sufficient pretreatment reaction. S2, Layered Spray Purification The pump body (305) pumps the spray liquid stored at the bottom of the spray tower (1) into the extension pipe (306), and sprays it onto the inside of the annular pipe (201) by the atomizing nozzle (308) to form uniform fine droplets of 40-80μm. The tail gas after the initial pretreatment by S1 flows upward and passes through the annular pipe (201), and is fully mixed with the atomized spray liquid in the pipe to achieve secondary dust removal and ammonia removal. The mixed and purified tail gas continues to rise, and after being regulated and guided by the aggregate guide frame (2), it enters the upper spray mechanism (4). The absorbent liquid is continuously sprayed through the spray pipe (402), and the gas-liquid contact time is extended with the help of the packing plate (401) to fully absorb the residual ammonia molecules in the tail gas and complete the deep purification treatment. S3, Terminal Activated Carbon Filtration After the exhaust gas is purified by multi-stage spraying, it is discharged into the first exhaust pipe (6). During the flow of the exhaust gas in the pipe wall of the first exhaust pipe (6), it continuously dissipates heat to the outside through the heat-conducting pipe wall, achieving preliminary cooling. When the exhaust gas flows through the grid condenser plate (14) in the pipe, the staggered grid disperses and refines the airflow, increases the contact area between water vapor and the low-temperature heat exchange surface, and the water vapor is fully liquefied through heat exchange. The condensed water droplets flow back to the spray tower (1) along the pipe wall, thereby reducing the moisture content in the exhaust gas. The exhaust gas after passing through the first exhaust pipe (6) is finally passed into the box (11) filled with acidic activated carbon body (12). The acidic activated carbon body (12) adsorbs the trace amount of ammonia gas that escapes in the exhaust gas. The clean exhaust gas is finally discharged through the third exhaust pipe (10) in compliance with the standard.

10. A method for treating ammonia-containing tail gas from precious metal refining according to claim 9, characterized in that: The residence time of the exhaust gas in the activated carbon layer is controlled at 1.2 to 1.8 seconds. When the residual trace amount of water vapor in the exhaust gas causes the acidic activated carbon body (12) to become damp, or when the acidic activated carbon body (12) reaches saturation, the ineffective acidic activated carbon body (12) in the box (11) is removed and replaced with new carbon.

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