Arsenic sulfide mud drying equipment and drying method

Abstract

The present invention discloses a drying equipment for arsenic sulfide mud, which includes a steam dryer, a spiral feeder, a cooling discharger, a hot exhaust pipe, a solid-gas separator, a clean air pipe, a scrubber, a scrubber pump, a circulation pipe, and an exhaust fan; the spiral feeder is used for feeding the steam dryer; the steam dryer is provided with a plurality of hollow spiral pipes and steam is passed through the steam dryer for heating and drying the arsenic sulfide mud; the cooling discharger is used for discharging the steam dryer; the hot exhaust pipe is connected to the top of the steam dryer for discharging the hot air generated in the steam dryer; the solid-gas separator is connected to the hot exhaust pipe, the solid-gas separator is connected to the scrubber through the clean air pipe, the top of the scrubber is connected to the inlet of the exhaust fan through a pipeline, and the scrubber pump is connected to the lower part of the scrubber. The present invention can completely and effectively remove moisture from the arsenic sulfide mud, and can process and utilize the exhaust gas generated during the drying process.

Description

Technical Field

[0001] The invention belongs to the technical field of harmless treatment of arsenic sulfide mud, and particularly relates to arsenic sulfide mud drying equipment and a drying method. Background Art

[0002] A large amount of waste acid is produced during the acid production process of non-ferrous metal smelting flue gas. These waste acids are discharged to the sewage treatment workshop for treatment. Since the waste acid contains heavy metal pollutants such as arsenic, copper, and lead, it is generally pre-treated by sulfidation to convert the heavy metal pollutants into sulfides. The sulfides that are settled are commonly known as "sulfide slag", and those with high arsenic content are commonly known as "arsenic sulfide mud". Arsenic sulfide mud contains a large amount of arsenic and other heavy metal elements. If it is not properly handled, the harmful elements will be released back into the environment, causing harm to the environment. At present, the treatment methods of arsenic sulfide mud include wet treatment and pyrolysis. The wet treatment is to use acid leaching, alkali leaching or salt leaching to separate arsenic from the mud residue first, and then carry out harmless treatment. However, it is difficult to completely leach arsenic by wet treatment, resulting in a low arsenic recovery rate. The arsenic remaining in the mud residue still needs further treatment, and the amount of acid, alkali and other leaching solutions is large, which increases the recovery cost. The pyrolysis method is a roasting reduction method. Because the water content of arsenic sulfide mud is high, arsenic sulfide mud is usually separated into solid and liquid by a thickener and a filter press, which cannot completely remove water, affecting the roasting effect and restricting the promotion and application of pyrolysis treatment technology. Summary of the invention

[0003] In view of the deficiency that the moisture in the arsenic sulfide mud treated by the above-mentioned pyro-roasting method cannot be completely and effectively removed, the present invention discloses an arsenic sulfide mud drying device and a drying method, which can not only quickly and effectively remove the moisture in the arsenic sulfide mud, but also can treat and utilize the tail gas generated in the drying process.

[0004] The present invention is achieved by adopting the following technical solutions:

[0005] An arsenic sulfide mud drying device, comprising a steam dryer, a spiral feeder, a cooling discharger, a hot exhaust pipe, a solid-gas separator, a clean air pipe, a scrubber, a scrubber pump, and an exhaust fan; the spiral feeder is used to feed the arsenic sulfide mud into the steam dryer for drying; the steam dryer is provided with a plurality of hollow spiral tubes, and steam is passed through the hollow spiral tubes to heat and dry the arsenic sulfide mud outside the hollow spiral tubes; the cooling discharger is used to collect and cool the arsenic sulfide mud dried by the steam dryer; the hot exhaust pipe is connected to the top of the steam dryer The solid-gas separator is connected to the hot exhaust pipe, a discharge port is provided at the bottom of the solid-gas separator, and the gas phase outlet of the solid-gas separator is connected to the clean air pipe; the clean air pipe is connected to the scrubbing tower, and the top of the scrubbing tower is connected to the inlet of the exhaust gas fan through a pipeline; the inlet of the scrubbing pump is connected to the lower part of the scrubbing tower through a pipeline, and the outlet of the scrubbing pump is connected to the upper part of the scrubbing tower through a pipeline; the outlet of the exhaust gas fan is connected to the exhaust gas treatment system or the chimney through a pipeline.

[0006] The present invention uses a steam heater provided with a hollow spiral tube to heat and dry the arsenic sulfide mud. The hot gas generated during the drying process is sent to a solid-gas separator through a hot exhaust pipe to separate and remove solid particles, and then sent to a scrubber for treatment and then sent to an exhaust gas treatment system or a chimney through an exhaust fan. The method of introducing steam into a hollow spiral tube in the steam heater to heat the arsenic sulfide mud can increase the contact area between the hollow spiral tube and the arsenic sulfide mud, improve the drying efficiency, and facilitate the evaporation of water in the arsenic sulfide mud, thereby achieving the purpose of quickly and effectively removing water from the arsenic sulfide mud. At the same time, the hot gas generated during the drying process is treated to remove arsenic entrained in the hot gas, thereby reducing the pollution of the environment by exhaust gas emissions.

[0007] Furthermore, the solid-gas separator is any one of an inner cyclone separator, an outer cyclone separator, a single-tube cyclone separator and a multi-tube cyclone separator.

[0008] Furthermore, the arsenic sulfide mud drying equipment also includes a waste heat boiler, and the hot gas in the hot exhaust pipe is sent to the waste heat boiler to recover the waste heat and then sent to the solid-gas separator. The waste heat boiler is set to recover the waste heat of the hot gas, reasonably utilize the waste heat resources, and reduce the waste of heat energy.

[0009] Furthermore, a first filter is provided on the pipeline between the exhaust fan and the scrubber, and a second filter is provided between the inlet of the scrubber pump and the scrubber. The first filter and the second filter are provided to filter particulate impurities in the exhaust gas and impurities in the wash liquid respectively to prevent them from damaging the exhaust fan and the scrubber pump.

[0010] Furthermore, the arsenic sulfide mud drying equipment also includes a sedimentation tank, and the bottom of the scrubber is connected to the sedimentation tank through a pipeline. The sedimentation tank is used to perform sedimentation treatment on the washing liquid in the scrubber, and the clarified washing liquid is recovered to the scrubber or the sewage treatment system through a pump. The provision of the sedimentation tank is conducive to separating and removing solid matter in the washing liquid, achieving the purpose of washing liquid regeneration, so that the washing liquid can be recycled.

[0011] A method for drying arsenic sulfide mud, which uses the above-mentioned arsenic sulfide mud drying equipment, specifically comprises the following steps:

[0012] S1. Add arsenic sulfide mud with a volume not exceeding 1500L into a screw feeder, then feed the arsenic sulfide mud into a steam dryer through the screw feeder for drying, and simultaneously introduce steam at 140 to 160°C into a hollow spiral tube in the steam dryer, the drying time being 30 to 60 minutes, and then collect and cool the dried arsenic sulfide mud using a cooling discharger;

[0013] S2. The hot gas generated by the drying steam engine is sent from the hot exhaust pipe to the waste heat boiler to recover heat, so that the hot gas temperature drops to 80-90°C and then sent to the solid-gas separator for treatment. The exhaust gas discharged from the solid-gas separator is sent to the scrubber for treatment and then sent to the exhaust gas treatment system or chimney through the exhaust gas fan.

[0014] The present invention controls the heating temperature and heating time to ensure that the moisture in the arsenic sulfide mud can be removed in a timely and effective manner. At the same time, the waste heat in the drying hot gas is recovered through the waste heat boiler to reduce the hot gas temperature. The low-temperature tail gas is beneficial to solid-gas separation and the adsorption of impurities by the washing liquid.

[0015] Furthermore, before adding the arsenic sulfide mud to the screw feeder, the arsenic sulfide mud is heated to 30-50° C., and the water content in the arsenic sulfide mud is 50-55%. By preheating the arsenic sulfide mud and controlling the water content in the arsenic sulfide mud, it is beneficial to remove the water in the arsenic sulfide mud in a timely and effective manner after entering the steam heater.

[0016] Furthermore, the washing liquid in the scrubber is a composite washing liquid, and the preparation method of the composite washing liquid is to weigh the raw materials according to the mass ratio of starch: polyacrylamide: ammonium persulfate: water: activated alumina of (5-10): (20-30): (0.5-1): 200: (5-10), and then evenly mix the starch, polyacrylamide, ammonium persulfate and water at 40-50°C for 1-2 hours, and then add activated alumina after natural cooling and stirring to obtain the composite washing liquid. The modified polyacrylamide obtained by starch modification is compounded with activated alumina to prepare the composite washing liquid, which can better adsorb particulate impurities and arsenic trioxide components in hot air and reduce the pollution of exhaust emissions to the environment.

[0017] Compared with the prior art, this technical solution has the following beneficial effects:

[0018] 1. The present invention adopts a steam heater provided with a hollow spiral tube to heat and dry the arsenic sulfide mud, which can timely and effectively remove the moisture in the arsenic sulfide mud, and at the same time process the hot air generated during the drying process, which can not only remove the particulate matter in the hot air, but also effectively remove the arsenic trioxide toxic gas generated by high-temperature drying.

[0019] 2. The process flow of the present invention is simple, which not only reduces the weight of hazardous waste arsenic sulfide mud, but also reduces the cost of hazardous waste disposal and environmental management pressure, and reduces the labor intensity of workers. At the same time, the process can continuously put in arsenic sulfide mud for drying through the cooperation of steam dryers, spiral feeders, cooling dischargers and other equipment. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a connection diagram of the arsenic sulfide mud drying equipment described in Example 2.

[0021] Figure numerals: 1-steam dryer, 2-screw feeder, 3-cooling discharger, 4-hot exhaust pipe, 5-solid-gas separator, 6-clean air pipe, 7-washing tower, 8-washing pump, 9-exhaust fan, 10-waste heat boiler, 11-first filter, 12-second filter, 13-sedimentation tank. DETAILED DESCRIPTION

[0022] The present invention is further described by the following examples, but is not intended to be limiting of the present invention. Specific experimental conditions and methods not specified in the following examples are conventional methods commonly known to those skilled in the art.

[0023] Embodiment 1:

[0024] An arsenic sulfide mud drying device comprises a steam dryer 1, a spiral feeder 2, a cooling discharger 3, a hot exhaust pipe 4, a solid-gas separator 5, a clean air pipe 6, a scrubber 7, a scrubber pump 8, and an exhaust fan 9; the spiral feeder 2 is used to feed the arsenic sulfide mud into the steam dryer 1 for drying; the steam dryer 1 is provided with more than 5 hollow spiral tubes, and steam is passed into the hollow spiral tubes to heat and dry the arsenic sulfide mud outside the hollow spiral tubes; the cooling discharger 3 is used to collect and cool the arsenic sulfide mud dried by the steam dryer 1; the hot exhaust pipe 4 is connected to the top of the steam dryer 1, and is used to discharge the hot air generated in the steam dryer 1; The solid-gas separator 5 is connected to the hot exhaust pipe 4, and a discharge port is provided at the bottom of the solid-gas separator 5. The gas phase outlet of the solid-gas separator 5 is connected to the clean air pipe 6; the clean air pipe 6 is connected to the scrubbing tower 7, and the top of the scrubbing tower 7 is connected to the inlet of the exhaust gas fan 9 through a pipeline; the inlet of the scrubbing pump 8 is connected to the lower part of the scrubbing tower 7 through a pipeline, and the outlet of the scrubbing pump 8 is connected to the upper part of the scrubbing tower 7 through a pipeline; the outlet of the exhaust gas fan 9 is connected to the exhaust gas treatment system or the chimney through a pipeline; the solid-gas separator 5 is any one of an inner cyclone separator, an outer cyclone separator, a single-tube cyclone separator and a multi-tube cyclone separator.

[0025] Embodiment 2:

[0026] like Figure 1 As shown, the difference between the arsenic sulfide mud drying equipment described in this embodiment and the equipment described in Example 1 is that: the arsenic sulfide mud drying equipment also includes a waste heat boiler 10, and the hot gas in the hot exhaust pipe 4 is sent to the waste heat boiler 10 to recover the waste heat and then sent to the solid-gas separator 5. The waste heat boiler 10 is set to recover the waste heat of the hot gas, reasonably utilize the waste heat resources, and reduce the waste of heat energy; a first filter 11 is provided on the pipeline between the exhaust fan 9 and the scrubber 7, a second filter 12 is provided between the inlet of the scrubber pump 8 and the scrubber 7, and a first filter 13 is provided between the inlet of the scrubber pump 8 and the scrubber 7. A filter 11 and a second filter 12 filter particulate impurities in the exhaust gas and impurities in the washing liquid respectively to prevent them from damaging the exhaust gas fan 9 and the washing pump 8; the arsenic sulfide mud drying equipment also includes a sedimentation tank 13, the bottom of the washing tower 7 is connected to the sedimentation tank 13 through a pipeline, the sedimentation tank 13 is used to sediment the washing liquid in the washing tower 7, and the clarified washing liquid is recovered to the washing tower 7 or the sewage treatment system through a pump. The setting of the sedimentation tank 13 is conducive to separating and removing solid matter in the washing liquid, achieving the purpose of washing liquid regeneration, so that the washing liquid can be recycled.

[0027] Embodiment 3:

[0028] A method for drying arsenic sulfide mud, which uses the arsenic sulfide mud drying equipment described in Example 2, specifically comprising the following steps:

[0029] S1. Add arsenic sulfide mud with a volume not exceeding 1500L into a screw feeder. Before adding the arsenic sulfide mud to the screw feeder, heat the arsenic sulfide mud to 40°C, and the water content of the arsenic sulfide mud is 53%. Then, the arsenic sulfide mud is sent to a steam dryer through the screw feeder for drying. At the same time, 145°C steam is introduced into the hollow spiral tube in the steam dryer. The drying time is 45 minutes. Then, the dried arsenic sulfide mud is collected and cooled by a cooling discharger;

[0030] S2. The hot gas generated by the drying steam engine is sent from the hot exhaust pipe to the waste heat boiler to recover heat, so that the temperature of the hot gas drops to 82°C and then sent to the solid-gas separator for treatment. The tail gas discharged from the solid-gas separator is sent to the scrubber for treatment and then sent to the tail gas treatment system or chimney through the tail gas fan; the washing liquid in the scrubber is a composite washing liquid, and the preparation method of the composite washing liquid is according to the mass ratio of starch: polyacrylamide: ammonium persulfate: water: activated alumina of 6:25:0.8:200:7. The raw materials are weighed, and then the starch, polyacrylamide, ammonium persulfate and water are uniformly mixed and reacted at 45°C for 1.5 hours, and then naturally cooled and then the activated alumina is added and stirred to obtain the composite washing liquid.

[0031] Embodiment 4:

[0032] A method for drying arsenic sulfide mud, which uses the arsenic sulfide mud drying equipment described in Example 2, specifically comprising the following steps:

[0033] S1. Adding arsenic sulfide mud with a volume not exceeding 1500L into a screw feeder. Before adding the arsenic sulfide mud into the screw feeder, the arsenic sulfide mud is heated to 30°C, and the water content of the arsenic sulfide mud is 50%. Then, the arsenic sulfide mud is sent into a steam dryer through the screw feeder for drying. At the same time, 140°C steam is introduced into the hollow spiral tube in the steam dryer. The drying time is 60 minutes. Then, the dried arsenic sulfide mud is collected and cooled by a cooling discharger;

[0034] S2. The hot gas generated by the drying steam engine is sent from the hot exhaust pipe to the waste heat boiler to recover heat, so that the temperature of the hot gas drops to 80°C and then sent to the solid-gas separator for treatment. The tail gas discharged from the solid-gas separator is sent to the scrubber for treatment and then sent to the tail gas treatment system or chimney through the tail gas fan; the washing liquid in the scrubber is a composite washing liquid, and the preparation method of the composite washing liquid is according to the mass ratio of starch: polyacrylamide: ammonium persulfate: water: activated alumina of 5:20:0.5:200:5. The raw materials are weighed, and then the starch, polyacrylamide, ammonium persulfate and water are uniformly mixed and reacted at 40°C for 1h, and then naturally cooled and then the activated alumina is added and stirred to obtain the composite washing liquid.

[0035] Embodiment 5:

[0036] A method for drying arsenic sulfide mud, which uses the arsenic sulfide mud drying equipment described in Example 2, specifically comprising the following steps:

[0037] S1. Add arsenic sulfide mud with a volume not exceeding 1500L into a screw feeder. Before adding the arsenic sulfide mud to the screw feeder, heat the arsenic sulfide mud to 35°C, and the water content of the arsenic sulfide mud is 52%. Then, the arsenic sulfide mud is sent to a steam dryer through the screw feeder for drying. At the same time, 150°C steam is introduced into the hollow spiral tube in the steam dryer. The drying time is 45 minutes. Then, the dried arsenic sulfide mud is collected and cooled by a cooling discharger.

[0038] S2. The hot gas generated by the drying steam engine is sent from the hot exhaust pipe to the waste heat boiler to recover heat, so that the temperature of the hot gas drops to 88°C and then sent to the solid-gas separator for treatment. The tail gas discharged from the solid-gas separator is sent to the scrubber for treatment and then sent to the tail gas treatment system or chimney through the tail gas fan; the washing liquid in the scrubber is a composite washing liquid, and the preparation method of the composite washing liquid is according to the mass ratio of starch: polyacrylamide: ammonium persulfate: water: activated alumina of 8:28:0.8:200:8. The raw materials are weighed, and then the starch, polyacrylamide, ammonium persulfate and water are uniformly mixed and reacted at 48°C for 1 to 2 hours, and then naturally cooled and then the activated alumina is added and stirred to obtain the composite washing liquid.

[0039] Embodiment 6:

[0040] A method for drying arsenic sulfide mud, which uses the arsenic sulfide mud drying equipment described in Example 2, specifically comprising the following steps:

[0041] S1. Add arsenic sulfide mud with a volume not exceeding 1500L into a screw feeder. Before adding the arsenic sulfide mud to the screw feeder, heat the arsenic sulfide mud to 50°C, and the water content of the arsenic sulfide mud is 55%. Then, the arsenic sulfide mud is sent to a steam dryer through the screw feeder for drying. At the same time, 160°C steam is introduced into the hollow spiral tube in the steam dryer. The drying time is 30 minutes. Then, the dried arsenic sulfide mud is collected and cooled by a cooling discharger;

[0042] S2. The hot gas generated by the drying steam engine is sent from the hot exhaust pipe to the waste heat boiler to recover heat, so that the temperature of the hot gas drops to 90°C and then sent to the solid-gas separator for treatment. The tail gas discharged from the solid-gas separator is sent to the scrubbing tower for treatment and then sent to the tail gas treatment system or chimney through the tail gas fan; the washing liquid in the scrubbing tower is a composite washing liquid, and the preparation method of the composite washing liquid is according to the mass ratio of starch: polyacrylamide: ammonium persulfate: water: activated alumina of 10:30:1:200:10. The raw materials are weighed, and then the starch, polyacrylamide, ammonium persulfate and water are uniformly mixed and reacted at 50°C for 2h, and then naturally cooled and then the activated alumina is added and stirred to obtain the composite washing liquid.

[0043] Comparative Example 1:

[0044] The method for drying arsenic sulfide mud described in this comparative example is different from the method described in Example 3 only in that the washing liquid in the scrubbing tower is water.

[0045] Experimental example:

[0046] Arsenic sulfide mud was treated according to the methods described in Examples 3 to 6 and Comparative Example 1, and the moisture content in the arsenic sulfide mud after treatment, as well as the solid particles and arsenic content in the exhaust gas delivered by the exhaust blower were detected. The specific results are shown in Table 1.

[0047] Table 1 Effects of different methods in treating arsenic sulfide mud

[0048]

[0049] It can be seen from the above data that the method of the present invention can effectively remove moisture from arsenic sulfide mud, and at the same time purify the hot air in the drying process, so that the particulate matter and harmful substances in the exhaust gas meet the exhaust gas emission standards. The hot gas purification effect obtained by using water as the washing liquid in Comparative Example 1 is significantly lower than the effect of using the composite washing liquid in the present invention.

[0050] In addition, it should be understood that although the present specification is described according to implementation modes, not every implementation mode contains only one independent technical solution. This description of the specification is only for the sake of clarity. Those skilled in the art should regard the specification as a whole. The technical solutions in each embodiment may also be appropriately combined to form other implementation modes that can be understood by those skilled in the art.

Claims

1. A method for drying arsenic sulfide mud, characterized in that: Arsenic sulfide mud drying equipment is used to dry arsenic sulfide mud, which specifically includes the following steps: S1. Add arsenic sulfide mud with a volume not exceeding 1500L into a screw feeder, then feed the arsenic sulfide mud into a steam dryer through the screw feeder for drying, and simultaneously introduce steam at 140 to 160°C into a hollow spiral tube in the steam dryer, the drying time being 30 to 60 minutes, and then collect and cool the dried arsenic sulfide mud using a cooling discharger; Before adding the arsenic sulfide mud into the screw feeder, the arsenic sulfide mud is heated to 30-50°C, and the water content of the arsenic sulfide mud is 50-55%; S2. The hot gas generated by the steam dryer is sent from the hot exhaust pipe to the waste heat boiler to recover heat, so that the hot gas temperature drops to 80-90°C and then sent to the solid-gas separator for treatment. The tail gas discharged from the solid-gas separator is sent to the scrubber for treatment and then sent to the tail gas treatment system or chimney through the tail gas fan; The washing liquid in the scrubbing tower is a composite washing liquid, and the preparation method of the composite washing liquid is as follows: the raw materials are weighed according to the mass ratio of starch: polyacrylamide: ammonium persulfate: water: activated alumina of (5-10): (20-30): (0.5-1): 200: (5-10), and then the starch, polyacrylamide, ammonium persulfate and water are uniformly mixed at 40-50° C. for 1-2 hours, and then the activated alumina is added after natural cooling and stirred to obtain the composite washing liquid; The arsenic sulfide mud drying equipment comprises a steam dryer (1), a spiral feeder (2), a cooling discharger (3), a hot exhaust pipe (4), a solid-gas separator (5), a clean air pipe (6), a scrubber (7), a scrubber pump (8), and an exhaust fan (9); the spiral feeder (2) is used to feed the arsenic sulfide mud into the steam dryer (1) for drying; the steam dryer (1) is provided with a plurality of hollow spiral tubes, and steam is introduced into the hollow spiral tubes to heat and dry the arsenic sulfide mud outside the hollow spiral tubes; the cooling discharger (3) is used to collect and cool the arsenic sulfide mud dried by the steam dryer (1); the hot exhaust pipe (4) is connected to the top of the steam dryer (1); The solid-gas separator (5) is connected to the hot exhaust pipe (4), the bottom of the solid-gas separator (5) is provided with a discharge port, and the gas phase outlet of the solid-gas separator (5) is connected to the clean air pipe (6); the clean air pipe (6) is connected to the scrubber (7), the top of the scrubber (7) is connected to the inlet of the exhaust fan (9) through a pipeline; the inlet of the scrubber pump (8) is connected to the lower part of the scrubber (7) through a pipeline, and the outlet of the scrubber pump (8) is connected to the upper part of the scrubber (7) through a pipeline; the outlet of the exhaust fan (9) is connected to the exhaust gas treatment system or the chimney through a pipeline; The arsenic sulfide mud drying equipment also includes a waste heat boiler (10), and the hot gas in the hot exhaust pipe (4) is sent to the waste heat boiler (10) to recover the waste heat and then sent to the solid-gas separator (5).

2. The method for drying arsenic sulfide mud according to claim 1, characterized in that: The solid-gas separator (5) is any one of an inner cyclone separator, an outer cyclone separator, a single-tube cyclone separator and a multi-tube cyclone separator.

3. The method for drying arsenic sulfide mud according to claim 1, characterized in that: A first filter (11) is provided on the pipeline between the exhaust gas fan (9) and the scrubbing tower (7), and a second filter (12) is provided between the inlet of the scrubbing pump (8) and the scrubbing tower (7).

4. The method for drying arsenic sulfide mud according to claim 1, characterized in that: The arsenic sulfide mud drying equipment also includes a sedimentation tank (13). The bottom of the scrubbing tower (7) is connected to the sedimentation tank (13) through a pipeline. The sedimentation tank (13) is used to perform sedimentation treatment on the washing liquid in the scrubbing tower (7), and to recover the clarified washing liquid to the scrubbing tower (7) or a sewage treatment system through a pump.

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