Harmless treatment system for secondary aluminum ash

Abstract

The utility model discloses an innocent treatment system for secondary aluminum ash. The innocent treatment system comprises a feeding mechanism, a first-stage fluorine-fixing denitrification pretreatment mechanism, a second-stage strengthening and desulfurization treatment mechanism and a third-stage desalination treatment mechanism which are sequentially connected in series. Through the synergistic effect of the three stages of treatment mechanisms, harmful components such as aluminum nitride, fluoride salt, chloride and sulfide in the secondary aluminum ash slag are efficiently removed, the content of aluminum oxide in the secondary aluminum ash slag raw material treated by the secondary aluminum ash slag treatment device is greatly increased, and the secondary aluminum ash slag raw material can be used as a high-quality high-aluminum material for producing floor tiles and water purifying agents; and harmless and resource utilization of the secondary aluminum ash is realized. In addition, the device is low in operation and maintenance cost, good in harmless and resourceful treatment effect on the secondary aluminum ash, capable of being applied in a large scale, good in social and economic benefits and environmentally friendly.

Description

Technical Field

[0001] This utility model relates to equipment for treating secondary aluminum ash slag, specifically to a harmless treatment system for secondary aluminum ash slag, belonging to the technical field of harmless treatment of secondary aluminum ash slag. Background Technology

[0002] Secondary aluminum ash slag typically refers to the waste material generated after primary aluminum ash slag is extracted into metallic aluminum, or aluminum-containing waste slag produced during the aluminum refining process. Secondary aluminum ash slag has a complex composition, containing components such as alumina, aluminum nitride, fluoride salts, chlorides, sulfides, and silicon. Because aluminum nitride (AlN) readily reacts with water in the air to produce ammonia, and because fluoride salts, chlorides, and sulfides are all toxic and hazardous substances, secondary aluminum ash slag is also classified as hazardous waste and has been included in the "National Hazardous Waste List."

[0003] With increasingly stringent environmental protection requirements, the safe disposal of secondary aluminum ash has become a focus of public attention. Since alumina in secondary aluminum ash is an important building material raw material, harmless treatment and resource utilization of the ash are reasonable disposal methods. Currently, many domestic researchers are conducting research on the resource utilization of secondary aluminum ash. For example, Chinese patent publication number "CN 115028367 A" discloses a method for preparing foamed microcrystalline glass from secondary aluminum ash, belonging to the field of solid waste resource utilization. The method involves uniformly mixing calcined secondary aluminum ash and waste glass, then adding water and a surface modifier to obtain a solid-liquid mixed-phase slurry. The slurry is stirred and foamed to obtain granular stabilized foam. Finally, the foamed microcrystalline glass is obtained through molding, demolding, drying, and sintering. Hydrophobic modification of the secondary aluminum ash and waste glass particles enhances their adhesion at the air-water interface, preventing foam collapse. Although this method utilizes secondary aluminum ash slag to prepare foamed microcrystalline glass with small pore size and uniform pore distribution, achieving resource utilization of secondary aluminum ash slag, there are still areas for improvement. CN115028367A only involves simple calcination treatment of the secondary aluminum ash slag, which cannot effectively eliminate the adverse effects of harmful substances such as aluminum nitride, fluoride salts, chlorides, and sulfides in the secondary aluminum ash slag, and certain safety hazards still exist. Therefore, in order to more safely utilize the alumina component in secondary aluminum ash slag to produce high-alumina materials, it is necessary to first fully eliminate the adverse effects of harmful components such as aluminum nitride, fluoride salts, chlorides, and sulfides in the secondary aluminum ash slag. Utility Model Content

[0004] To address the problem of secondary pollution caused by the poor removal efficiency of harmful substances such as aluminum nitride, fluoride salts, chlorides, and sulfides in existing technologies, this invention provides a harmless treatment system for secondary aluminum ash slag. The system employs a primary solid fluoride and denitrification pretreatment unit to decompose and eliminate aluminum nitride and fluoride salts from the secondary aluminum ash slag; a secondary intensification and desulfurization treatment unit to eliminate sulfides; and a tertiary desalination treatment unit to remove soluble salts such as chlorides. In other words, this three-stage treatment removes harmful components such as aluminum nitride, fluoride salts, chlorides, and sulfides from the aluminum ash slag, significantly increasing the alumina content in the secondary aluminum ash slag raw material. This allows it to be used in the production of high-quality, high-alumina materials for floor tiles and water purification agents, achieving the harmless utilization of secondary aluminum ash slag.

[0005] To achieve the above-mentioned technical objectives, the technical solution adopted by this utility model is specifically described as follows:

[0006] A harmless treatment system for secondary aluminum ash slag includes a feeding mechanism, a primary solid fluoride and nitrogen removal pretreatment mechanism, a secondary enhanced desulfurization treatment mechanism, and a tertiary desalination treatment mechanism. The feeding mechanism, the primary solid fluoride and nitrogen removal pretreatment mechanism, the secondary enhanced desulfurization treatment mechanism, and the tertiary desalination treatment mechanism are arranged in series.

[0007] Preferably, the feeding mechanism includes a feeding device, a raw material silo, and a belt scale. The feeding device, raw material silo, and belt scale are connected in series. Preferably, a gate valve is provided at the bottom outlet of the raw material silo. A vibrator is also provided on the lower outer wall of the raw material silo.

[0008] Preferably, the feeding device is a belt conveyor and / or a bucket elevator.

[0009] Preferably, the primary solid fluoride denitrification pretreatment unit includes a feeder, a ball mill, and a discharge buffer chamber. The feed end of the feeder is connected to the discharge end of the feeding mechanism. The feeder, ball mill, and discharge buffer chamber are arranged in series. An inert gas inlet pipe, a solid fluoride agent inlet pipe, and a water inlet pipe are also provided at the feed end of the ball mill. An exhaust pipe is provided at the top of the discharge buffer chamber, and a discharge chute is provided at the bottom of the discharge buffer chamber. The discharge end of the discharge chute is connected to the feed end of the secondary enhancement and desulfurization treatment unit.

[0010] Preferably, the feeder is a screw feeder. The water outlet of the water supply pipe extends into the inner cavity of the ball mill.

[0011] Preferably, the secondary enhancement and desulfurization treatment unit includes an enhancement reactor, an oxidation reactor, and a carbon dioxide slurry preparation reactor. The feed end of the enhancement reactor is connected to the discharge end of the primary solid fluoride denitrification pretreatment unit. The enhancement reactor, oxidation reactor, and carbon dioxide slurry preparation reactor are connected in series. The discharge end of the carbon dioxide slurry preparation reactor is connected to the feed end of the tertiary desalination treatment unit.

[0012] Preferably, the inner cavity of the enhanced reactor is connected to the inlet of the oxidation reactor via a first delivery pump and delivery pipe assembly. The inner cavity of the oxidation reactor is connected to the inlet of the carbon dioxide slurry preparation reactor via a second delivery pump and delivery pipe assembly. The inner cavity of the carbon dioxide slurry preparation reactor is connected to the inlet of the three-stage desalination treatment unit via a third delivery pump and delivery pipe assembly. An enhanced exhaust pipe is also provided at the top of the enhanced reactor. An oxidant inlet pipe is provided on the side wall of the oxidation reactor, and an oxidation safety valve is also provided at the top of the oxidation reactor. A carbon dioxide inlet pipe is provided on the side wall of the carbon dioxide slurry preparation reactor, and a slurry preparation safety valve is also provided at the top of the carbon dioxide slurry preparation reactor.

[0013] Preferably, each of the strengthening reactor, oxidation reactor, and carbon dioxide slurry preparation reactor is equipped with an independent stirring mechanism. Each stirring mechanism includes a stirring motor independently mounted on the top of the strengthening reactor, the top of the oxidation reactor, and the top of the carbon dioxide slurry preparation reactor. Each stirring motor is independently connected to a stirring blade located in the corresponding reactor cavity via a stirring shaft.

[0014] Preferably, the three-stage desalination treatment unit includes a belt filter, a brine tank, and spray heads. The feed end of the belt filter is connected to the discharge end of the secondary enhancement and desulfurization treatment unit. The brine tank is located below the belt filter. The spray heads are located above the belt filter and are connected to an external clean water source via water supply pipes.

[0015] Preferably, based on the material flow direction, the belt filter is divided into three spray sections connected in series: a first spray section, a second spray section, and a third spray section. Independent spray heads are installed above each of the three spray sections. The brine tank includes a high-concentration tank below the first spray section, a medium-concentration tank below the second spray section, and a low-concentration tank below the third spray section. The high-concentration tank, the medium-concentration tank, and the low-concentration tank are not interconnected.

[0016] Preferably, the water inlet of the spray head located above the first spray section is connected to the drain outlet of the medium concentration tank via a water supply pipe and a water pump. The water inlet of the spray head located above the second spray section is connected to the drain outlet of the low concentration tank via a water supply pipe and a water pump. The water inlet of the spray head located above the third spray section is connected to an external clean water source via a water supply pipe and a water pump.

[0017] Alternatively, the inlet ends of the spray heads located above the first and third spray sections are both connected to an external clean water source via water pipes and pumps. The inlet end of the spray head located above the second spray section is connected to the drain outlet of the medium concentration tank via a water pipe and pump. The drain outlet of the low concentration tank is connected to the inlet of the medium concentration tank via a water pipe and pump. A salt concentration detector is also installed in the medium concentration tank.

[0018] Preferably, the system also includes a dryer and a storage silo. The feed end of the dryer is connected to the feed end of the belt filter. The discharge end of the dryer is connected to the feed end of the storage silo via a conveyor.

[0019] In this invention, the problem of secondary pollution caused by poor removal efficiency of harmful substances such as aluminum nitride, fluoride salts, chlorides, and sulfides in the resource utilization process of secondary aluminum ash slag in existing technologies is addressed. This invention achieves the harmless treatment of aluminum ash slag by setting up a primary solid fluoride and denitrification pretreatment mechanism, a secondary enhanced desulfurization treatment mechanism, and a tertiary desalination treatment mechanism. It efficiently removes harmful components such as aluminum nitride, fluoride salts, chlorides, and sulfides from aluminum ash slag. Furthermore, the alumina content in the secondary aluminum ash slag raw material after treatment by this invention is significantly increased, making it a high-alumina material for the production of floor tiles and water purification agents, thus realizing the resource utilization of secondary aluminum ash slag. Specifically: This invention firstly uses a primary solid fluoride denitrification pretreatment unit to effectively remove aluminum nitride, fluoride salts, and residual trace amounts of aluminum; a secondary enhanced desulfurization treatment unit further ensures the complete removal of aluminum nitride, fluoride salts, and aluminum; and an oxidation reactor and a carbon dioxide slurry treatment reactor further remove harmful sulfur ions and precipitate aluminum and calcium, reducing impurities in the brine; finally, a tertiary desalination treatment unit performs washing and filtration to further wash away soluble chloride salts in the filter cake. The aluminum ash filter cake can be used as a high-alumina material, which, after drying in a dryer, forms a high-alumina product.

[0020] In this invention, the feeding mechanism includes a feeding device, a raw material silo, and a belt scale. The feeding device can be a belt conveyor or a bucket elevator, primarily used to add secondary aluminum ash slag raw materials into the raw material silo (or other existing equipment capable of material feeding). The raw material silo is mainly used to buffer the secondary aluminum ash slag raw materials. It is equipped with a gate valve (electric or manual) at the bottom to adjust the feeding rate, and a silo wall vibrator on the lower outer wall (generally the outer wall corresponding to the discharge port) to prevent material blockage at the discharge port. The material discharged from the raw material silo is fed to the subsequent primary solid fluoride denitrification pretreatment unit for processing via a belt scale (which simultaneously conveys and weighs the material to control the material flow rate; this scale is linked to the gate valve).

[0021] In this invention, the primary solid fluoride denitrification pretreatment unit includes a feeder, a ball mill, and a discharge buffer chamber. The feeder is generally a screw feeder, the end of which is connected to the feed inlet of the ball mill. The ball mill feed inlet is also equipped with an inert gas inlet pipe (for introducing inert gas, such as nitrogen), a solid fluoride agent inlet pipe (for adding solid fluoride agents, such as calcium oxide), and a water inlet pipe. The outlet of the water inlet pipe must extend into the inner cavity of the ball mill (because the secondary aluminum ash slag raw material and solid fluoride agent may clump together at the ball mill feed inlet when exposed to water, easily causing blockage and affecting the feed). The inert gas inlet is connected to an external gas source (such as a nitrogen source) through a gas transmission pipe. The discharge buffer chamber is connected to the ball mill discharge outlet. The top of the discharge buffer chamber is equipped with an exhaust port (connected to an exhaust pipe). The discharge port at the bottom of the discharge buffer chamber feeds the material to the secondary enhancement and desulfurization treatment unit through a discharge chute. During the production process, the filling rate of the material inside the ball mill is generally around 15-40%. Because the filling rate of the ball mill is not high, there is always an exhaust space (discharge buffer chamber) at the discharge port when the ball mill is unloading. Harmful components such as ammonia and hydrogen generated inside the ball mill can overflow into the discharge buffer chamber through the discharge port in a timely manner and be drawn away from the exhaust port. In this way, the internal pressure of the ball mill will not be too high, which improves the stability of the system.

[0022] It should be noted that the reactions occurring in the ball mill of the primary solid fluoride denitrification pretreatment unit are generally as follows: most of the aluminum nitride decomposes and releases ammonia gas, which is promptly removed from the exhaust vent of the discharge buffer chamber using a deammoniation device; the added solid fluoride agent (CaO) reacts with fluoride ions to generate calcium fluoride, stabilizing the fluoride; the aluminum shavings remaining in the secondary aluminum ash react with alkali to produce sodium aluminate. The primary solid fluoride denitrification pretreatment unit can eliminate most of the harmful substances such as aluminum nitride and fluorides in the secondary aluminum ash. Specific reaction formulas involved include: AlN + 3H₂O = Al(OH)₃ + NH₃↑, CaO + H₂O + 2NaF = NaOH + CaF₂↓; 2Al + 2NaOH + 2H₂O = 2NaAlO₂ + 3H₂↑.

[0023] In this invention, the secondary enhanced desulfurization treatment mechanism includes an enhanced reaction vessel, an oxidation reaction vessel, and a carbon dioxide slurry preparation reaction vessel. The three reaction vessels have similar structures and are connected in series, each including a reaction vessel body and optionally, a stirring mechanism. The difference lies in that the enhanced reaction vessel has an enhanced exhaust port connected to an enhanced exhaust pipe at its top; an oxidation safety valve and a slurry preparation safety valve are respectively installed at the top of the oxidation reaction vessel and the top of the carbon dioxide slurry preparation reaction vessel. When the internal pressure of the oxidation reaction vessel and the carbon dioxide slurry preparation reaction vessel reaches a certain value, the safety valves (oxidation safety valve and slurry preparation safety valve) open, and the exhaust gas is discharged and transported to the exhaust gas treatment system through pipelines. An oxidant (e.g., ozone) inlet (connected to an oxidant inlet pipe) is provided on the lower side wall or bottom wall of the oxidation reaction vessel, and a CO2 inlet (connected to a carbon dioxide inlet pipe) is provided on the lower side wall or bottom wall of the carbon dioxide slurry preparation reaction vessel. After the secondary aluminum ash slurry, treated by the primary solid fluoride denitrification pretreatment unit, is reacted in the enhanced reactor and then transported to the oxidation reactor via the first conveying mechanism (first conveying pump and conveying pipe assembly). After reacting in the oxidation reactor, it is then transported to the carbon dioxide slurry conditioning reactor via the second conveying mechanism (second conveying pump and conveying pipe assembly). The slurry treated in the carbon dioxide slurry conditioning reactor is then transported to the tertiary desalination unit via the third conveying mechanism (third conveying pump and conveying pipe assembly). The first, second, and third conveying mechanisms have basically the same structure, all consisting of conveying pumps (each located at the bottom of the inner cavity of each reactor) and pipelines.

[0024] It should be noted that the main reactions occurring in the intensified reaction vessel are as follows: the unreacted aluminum ash slag in the ball mill continues to react; aluminum nitride continues to react to generate ammonia; the fluorinating agent reacts with fluoride ions to continue to generate stable fluorides; aluminum chips continue to react to generate hydrogen, but the reaction intensity is much lower than in the ball mill; the main reactions occurring in the oxidation reaction vessel are as follows: a strong oxidizing agent is used to oxidize the sulfur in the aluminum ash slurry to sulfate ions (3S). 2- +O3=3SO4 2- Its main function is to remove sulfur ions from aluminum ash slag. The main reactions occurring in the carbon dioxide slurry reactor are as follows: Carbon dioxide is used to precipitate aluminate ions to form aluminum hydroxide precipitate, and calcium ions in the solution are precipitated. The main purpose is to increase the alumina content of the high-alumina material and reduce impurities in the brine (2NaAlO2 + CO2 + 3H2O = 2Al(OH)3 + Na2CO3; Ca...). 2+ +Na₂CO₃=CaCO₃+2Na + ).

[0025] In this invention, the three-stage desalination treatment mechanism is mainly a belt filter. A spray head is installed above the belt filter, and a water receiving tank (i.e., a brine tank) is installed below it. The spray head washes the material conveyed to the belt filter, thereby washing the soluble chloride salts in the material into the brine tank, thus achieving the removal of soluble chloride salts from the aluminum ash slag.

[0026] Furthermore, based on the material flow, the belt filter is divided into three spray sections connected in series: spray section one, spray section two, and spray section three (more sections can also be set, such as sections 4, 5, 6, 7, and 8, etc.). Each section is equipped with an independent spray head. Simultaneously, the brine tanks located below the belt filter are also independently divided into high-concentration, medium-concentration, and low-concentration tanks. The brine in the medium-concentration tank is used as the spray water for spray section one, the brine in the low-concentration tank is used as the spray water for spray section two, and the spray water for spray section three is external clean water. Alternatively, the spray water for spray sections one and three is external clean water, and the brine in the medium-concentration tank is circulated by a circulation pump as the spray water for spray section two. A salt concentration detector is installed in the medium-concentration tank. When the chloride concentration in the medium-concentration tank reaches a certain value, it is discharged, and then water from the low-concentration tank is replenished into the medium-concentration tank through a water pump and pipeline.

[0027] Compared with the prior art, the beneficial technical effects of this utility model are as follows:

[0028] 1. The harmless treatment system for secondary aluminum ash slag of this utility model, through the synergistic action of three-stage treatment mechanisms, efficiently removes harmful components such as aluminum nitride, fluoride salts, chlorides, and sulfides from the secondary aluminum ash slag. Furthermore, the alumina content in the secondary aluminum ash slag raw material treated by this utility model is significantly increased, making it a high-alumina material for the production of floor tiles and water purification agents, thus realizing the harmless treatment and resource utilization of secondary aluminum ash slag.

[0029] 2: The harmless treatment system for secondary aluminum ash slag of this utility model has a simple overall structure, low equipment operation and maintenance costs, good effect on harmless and resource-based treatment of secondary aluminum ash slag, can be applied on a large scale, has good social and economic benefits and is environmentally friendly. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the overall structure of the system described in this utility model.

[0031] Figure 2 This is a schematic diagram of the feeding mechanism of this utility model.

[0032] Figure 3 This is a schematic diagram of the structure of the primary solid fluoride denitrification pretreatment mechanism of this utility model.

[0033] Figure 4This is a schematic diagram of the structure of the secondary enhancement and desulfurization treatment mechanism of this utility model.

[0034] Figure 5 This is a schematic diagram of the three-stage desalination treatment mechanism of this utility model.

[0035] Figure reference numerals: 1: Feeding mechanism; 101: Feeding device; 102: Raw material silo; 103: Belt scale; 104: Slide valve; 105: Vibrator; 2: Primary solid fluoride denitrification pretreatment mechanism; 201: Feeder; 202: Ball mill; 203: Discharge buffer chamber; 204: Inert gas inlet pipe; 205: Solid fluoride agent inlet pipe; 206: Water inlet pipe; 207: Exhaust pipe; 208: Discharge chute; 3: Secondary enhancement and desulfurization treatment mechanism; 301: Enhancement reactor; 302: Oxidation reactor; 303: Carbon dioxide slurry reactor; 304: First conveying pump and conveying pipe assembly; 305: Second conveying pump and conveying pipe assembly; 30 6: Third delivery pump and delivery pipe assembly; 307: Enhanced exhaust pipe; 308: Oxidant addition pipe; 309: Oxidation safety valve; 310: Carbon dioxide addition pipe; 311: Slurry conditioning safety valve; 4: Three-stage desalination treatment mechanism; 401: Belt filter; 4011: First stage of spraying; 4012: Second stage of spraying; 4013: Third stage of spraying; 402: Brine tank; 4021: High concentration tank; 4022: Medium concentration tank; 4023: Low concentration tank; 403: Spray head; 404: Salt concentration detector; 5: Stirring mechanism; 501: Stirring motor; 502: Stirring shaft; 503: Stirring blades; 6: Dryer; 7: Storage silo; 8: Feeder. Detailed Implementation

[0036] The technical solution of this utility model is illustrated below. The scope of protection of this utility model includes, but is not limited to, the following embodiments.

[0037] A harmless treatment system for secondary aluminum ash slag, comprising a feeding mechanism 1, a primary solid fluoride and nitrogen removal pretreatment mechanism 2, a secondary enhanced desulfurization and treatment mechanism 3, and a tertiary desalination treatment mechanism 4. The feeding mechanism 1, the primary solid fluoride and nitrogen removal pretreatment mechanism 2, the secondary enhanced desulfurization and treatment mechanism 3, and the tertiary desalination treatment mechanism 4 are arranged in series.

[0038] Preferably, the feeding mechanism 1 includes a feeding device 101, a raw material silo 102, and a belt scale 103. The feeding device 101, the raw material silo 102, and the belt scale 103 are connected in series. Preferably, a gate valve 104 is provided at the bottom outlet of the raw material silo 102. A vibrator 105 is also provided on the lower outer wall of the raw material silo 102.

[0039] Preferably, the feeding device 101 is a belt conveyor and / or a bucket elevator.

[0040] Preferably, the primary solid fluoride denitrification pretreatment unit 2 includes a feeder 201, a ball mill 202, and a discharge buffer chamber 203. The feed end of the feeder 201 is connected to the discharge end of the feeding mechanism 1. The feeder 201, ball mill 202, and discharge buffer chamber 203 are arranged in series. An inert gas inlet pipe 204, a solid fluoride agent inlet pipe 205, and a water inlet pipe 206 are also provided at the feed end of the ball mill 202. An exhaust pipe 207 is provided at the top of the discharge buffer chamber 203, and a discharge chute 208 is provided at the bottom of the discharge buffer chamber 203. The discharge end of the discharge chute 208 is connected to the feed end of the secondary enhancement and desulfurization treatment unit 3.

[0041] Preferably, the feeder 201 is a screw feeder. The water outlet of the water supply pipe 206 extends into the inner cavity of the ball mill 202.

[0042] Preferably, the secondary enhanced desulfurization treatment unit 3 includes an enhanced reactor 301, an oxidation reactor 302, and a carbon dioxide slurry preparation reactor 303. The feed end of the enhanced reactor 301 is connected to the discharge end of the primary solid fluoride denitrification pretreatment unit 2. The enhanced reactor 301, oxidation reactor 302, and carbon dioxide slurry preparation reactor 303 are connected in series. The discharge end of the carbon dioxide slurry preparation reactor 303 is connected to the feed end of the tertiary desalination treatment unit 4.

[0043] Preferably, the inner cavity of the enhanced reaction vessel 301 is connected to the inlet of the oxidation reaction vessel 302 via a first delivery pump and delivery pipe assembly 304. The inner cavity of the oxidation reaction vessel 302 is connected to the inlet of the carbon dioxide slurry preparation reaction vessel 303 via a second delivery pump and delivery pipe assembly 305. The inner cavity of the carbon dioxide slurry preparation reaction vessel 303 is connected to the inlet of the three-stage desalination treatment mechanism 4 via a third delivery pump and delivery pipe assembly 306. An enhanced exhaust pipe 307 is also provided at the top of the enhanced reaction vessel 301. An oxidant addition pipe 308 is provided on the side wall of the oxidation reaction vessel 302, and an oxidation safety valve 309 is also provided at the top of the oxidation reaction vessel 302. A carbon dioxide addition pipe 310 is provided on the side wall of the carbon dioxide slurry preparation reaction vessel 303, and a slurry preparation safety valve 311 is also provided at the top of the carbon dioxide slurry preparation reaction vessel 303.

[0044] Preferably, each of the enhanced reactor 301, the oxidation reactor 302, and the carbon dioxide slurry preparation reactor 303 is equipped with an independent stirring mechanism 5. The stirring mechanism 5 includes stirring motors 501, which are independently installed on the top of the enhanced reactor 301, the top of the oxidation reactor 302, and the top of the carbon dioxide slurry preparation reactor 303, respectively. Each stirring motor 501 is independently connected to a stirring blade 503 installed in the corresponding reactor cavity via a stirring shaft 502.

[0045] Preferably, the three-stage desalination treatment unit 4 includes a belt filter 401, a brine tank 402, and spray heads 403. The feed end of the belt filter 401 is connected to the discharge end of the secondary enhancement and desulfurization treatment unit 3. The brine tank 402 is located below the belt filter 401. The spray heads 403 are located above the belt filter 401 and are connected to an external clean water source via a water supply pipe.

[0046] Preferably, based on the material flow direction, the belt filter 401 is divided into three spray sections connected in series: a first spray section 4011, a second spray section 4012, and a third spray section 4013. Independent spray heads 403 are respectively installed above the first spray section 4011, the second spray section 4012, and the third spray section 4013. The brine tank 402 includes a high-concentration tank 4021 located below the first spray section 4011, a medium-concentration tank 4022 located below the second spray section 4012, and a low-concentration tank 4023 located below the third spray section 4013. The high-concentration tank 4021, the medium-concentration tank 4022, and the low-concentration tank 4023 are not interconnected.

[0047] Preferably, the water inlet of the spray head 403 located above the first spray section 4011 is connected to the drain outlet of the medium concentration tank 4022 via a water supply pipe and a water pump. The water inlet of the spray head 403 located above the second spray section 4012 is connected to the drain outlet of the low concentration tank 4023 via a water supply pipe and a water pump. The water inlet of the spray head 403 located above the third spray section 4013 is connected to an external clean water source via a water supply pipe and a water pump.

[0048] Alternatively, the inlet ends of the spray heads 403 located above the first spray section 4011 and the third spray section 4013 are both connected to an external clean water source via water pipes and pumps. The inlet end of the spray heads 403 located above the second spray section 4012 is connected to the drain outlet of the medium concentration tank 4022 via a water pipe and pump. The drain outlet of the low concentration tank 4023 is connected to the inlet of the medium concentration tank 4022 via a water pipe and pump. A salt concentration detector 404 is also installed inside the medium concentration tank 4022.

[0049] Preferably, the system also includes a dryer 6 and a storage silo 7. The feed end of the dryer 6 is connected to the feed end of the belt filter 401. The discharge end of the dryer 6 is connected to the feed end of the storage silo 7 via a conveyor 8. Example 1

[0050] like Figure 1-5As shown, a harmless treatment system for secondary aluminum ash slag is disclosed. The system includes a feeding mechanism 1, a primary solid fluoride denitrification pretreatment mechanism 2, a secondary enhanced desulfurization treatment mechanism 3, and a tertiary desalination treatment mechanism 4. The feeding mechanism 1, the primary solid fluoride denitrification pretreatment mechanism 2, the secondary enhanced desulfurization treatment mechanism 3, and the tertiary desalination treatment mechanism 4 are arranged in series. Example 2

[0051] The same as Embodiment 1 is repeated, except that the feeding mechanism 1 includes a feeding device 101, a raw material bin 102, and a belt scale 103. The feeding device 101, the raw material bin 102, and the belt scale 103 are connected in series. Example 3

[0052] The same method as Embodiment 2 is used, except that a gate valve 104 is provided at the bottom outlet of the raw material silo 102. A vibrator 105 is also provided on the lower outer wall of the raw material silo 102. Example 4

[0053] Example 3 is repeated, except that the feeding device 101 is a belt conveyor. Example 5

[0054] The embodiment 4 is repeated, except that the primary solid fluoride denitrification pretreatment unit 2 includes a feeder 201, a ball mill 202, and a discharge buffer chamber 203. The feed end of the feeder 201 is connected to the discharge end of the feed mechanism 1. The feeder 201, ball mill 202, and discharge buffer chamber 203 are arranged in series. An inert gas inlet pipe 204, a solid fluoride agent inlet pipe 205, and a water inlet pipe 206 are also provided at the feed end of the ball mill 202. An exhaust pipe 207 is provided at the top of the discharge buffer chamber 203, and a discharge chute 208 is provided at the bottom of the discharge buffer chamber 203. The discharge end of the discharge chute 208 is connected to the feed end of the secondary enhancement and desulfurization treatment unit 3. Example 6

[0055] Example 5 is repeated, except that the feeder 201 is a screw feeder. The water outlet of the water supply pipe 206 extends into the inner cavity of the ball mill 202. Example 7

[0056] Example 6 is repeated, except that the secondary enhancement and desulfurization treatment unit 3 includes an enhancement reactor 301, an oxidation reactor 302, and a carbon dioxide slurry preparation reactor 303. The feed end of the enhancement reactor 301 is connected to the discharge end of the primary solid fluoride denitrification pretreatment unit 2. The enhancement reactor 301, oxidation reactor 302, and carbon dioxide slurry preparation reactor 303 are connected in series. The discharge end of the carbon dioxide slurry preparation reactor 303 is connected to the feed end of the tertiary desalination treatment unit 4. Example 8

[0057] Example 7 is repeated, except that the inner cavity of the enhanced reactor 301 is connected to the inlet of the oxidation reactor 302 via a first delivery pump and delivery pipe assembly 304. The inner cavity of the oxidation reactor 302 is connected to the inlet of the carbon dioxide slurry preparation reactor 303 via a second delivery pump and delivery pipe assembly 305. The inner cavity of the carbon dioxide slurry preparation reactor 303 is connected to the inlet of the three-stage desalination treatment mechanism 4 via a third delivery pump and delivery pipe assembly 306. An enhanced exhaust pipe 307 is also provided at the top of the enhanced reactor 301. An oxidant addition pipe 308 is provided on the side wall of the oxidation reactor 302, and an oxidation safety valve 309 is also provided at the top of the oxidation reactor 302. A carbon dioxide addition pipe 310 is provided on the side wall of the carbon dioxide slurry preparation reactor 303, and a slurry preparation safety valve 311 is also provided at the top of the carbon dioxide slurry preparation reactor 303. Example 9

[0058] Example 8 is repeated, except that each of the enhanced reactor 301, oxidation reactor 302, and carbon dioxide slurry reactor 303 is equipped with an independent stirring mechanism 5. The stirring mechanism 5 includes stirring motors 501, which are independently installed on the top of the enhanced reactor 301, the top of the oxidation reactor 302, and the top of the carbon dioxide slurry reactor 303, respectively. Each stirring motor 501 is independently connected to a stirring blade 503 installed in the corresponding reactor cavity via a stirring shaft 502. Example 10

[0059] The embodiment 9 is repeated, except that the three-stage desalination treatment mechanism 4 includes a belt filter 401, a brine tank 402, and spray heads 403. The feed end of the belt filter 401 is connected to the discharge end of the secondary enhancement and desulfurization treatment mechanism 3. The brine tank 402 is located below the belt filter 401. The spray heads 403 are located above the belt filter 401 and are connected to an external clean water source via a water supply pipe. Example 11

[0060] Repeating Example 10, except that, according to the material flow, the belt filter 401 is divided into three spray sections connected in series: a first spray section 4011, a second spray section 4012, and a third spray section 4013. Independent spray heads 403 are respectively installed above the first spray section 4011, the second spray section 4012, and the third spray section 4013. The brine tank 402 includes a high-concentration tank 4021 located below the first spray section 4011, a medium-concentration tank 4022 located below the second spray section 4012, and a low-concentration tank 4023 located below the third spray section 4013. The high-concentration tank 4021, the medium-concentration tank 4022, and the low-concentration tank 4023 are not interconnected. Example 12

[0061] Example 11 is repeated, except that the water inlet of the spray head 403 located above the first spray section 4011 is connected to the drain outlet of the medium concentration tank 4022 via a water supply pipe and a water pump. The water inlet of the spray head 403 located above the second spray section 4012 is connected to the drain outlet of the low concentration tank 4023 via a water supply pipe and a water pump. The water inlet of the spray head 403 located above the third spray section 4013 is connected to an external clean water source via a water supply pipe and a water pump. Example 13

[0062] Example 11 is repeated, except that the water inlet ends of the spray heads 403 above the first spray section 4011 and the third spray section 4013 are both connected to an external clean water source via water pipes and pumps. The water inlet end of the spray heads 403 above the second spray section 4012 is connected to the drain outlet of the medium concentration tank 4022 via a water pipe and pump. The drain outlet of the low concentration tank 4023 is connected to the inlet of the medium concentration tank 4022 via a water pipe and pump. A salt concentration detector 404 is also installed in the medium concentration tank 4022. Example 14

[0063] The system repeats Example 13, except that it also includes a dryer 6 and a storage silo 7. The feed end of the dryer 6 is connected to the feed end of the belt filter 401. The discharge end of the dryer 6 is connected to the feed end of the storage silo 7 via a conveyor 8.

Claims

1. A system for innocuous treatment of secondary aluminum dross, characterized by: The system comprises a feeding mechanism (1), a first fluorine-fixing and denitrogenation pretreatment mechanism (2), a second strengthening and desulfurization treatment mechanism (3) and a third desalination treatment mechanism (4); the feeding mechanism (1), the first fluorine-fixing and denitrogenation pretreatment mechanism (2), the second strengthening and desulfurization treatment mechanism (3) and the third desalination treatment mechanism (4) are sequentially connected in series.

2. The system of claim 1, wherein: The feeding mechanism (1) comprises a feeding device (101), a raw material bin (102) and a belt scale (103); the feeding device (101), the raw material bin (102) and the belt scale (103) are sequentially connected in series.

3. The system of claim 2, wherein: A plug valve (104) is arranged at the bottom discharge port of the raw material bin (102); a vibrator (105) is further arranged on the lower outer wall of the raw material bin (102).

4. The system of claim 2 or 3, wherein: The feeding device (101) is a belt conveyor and / or a bucket elevator.

5. The system of claim 1, wherein: The first fluorine-fixing and denitrogenation pretreatment mechanism (2) comprises a feeder (201), a ball mill (202) and a discharge buffer chamber (203); the feeding end of the feeder (201) is connected with the discharge end of the feeding mechanism (1); the feeder (201), the ball mill (202) and the discharge buffer chamber (203) are sequentially connected in series; an inert gas adding pipeline (204), a fluorine-fixing agent adding pipeline (205) and a water adding pipeline (206) are further arranged at the feeding end of the ball mill (202); an air extraction pipeline (207) is arranged at the top of the discharge buffer chamber (203), and a discharge chute (208) is arranged at the bottom of the discharge buffer chamber (203); the discharge end of the discharge chute (208) is connected with the feeding end of the second strengthening and desulfurization treatment mechanism (3).

6. The system of claim 5, wherein: The feeder (201) is a screw feeder; the water outlet end of the water adding pipeline (206) extends into the inner cavity of the ball mill (202).

7. The system of claim 1, wherein: The second strengthening and desulfurization treatment mechanism (3) comprises a strengthening reaction kettle (301), an oxidation reaction kettle (302) and a carbon dioxide slurry adjusting reaction kettle (303); the feeding end of the strengthening reaction kettle (301) is connected with the discharge end of the first fluorine-fixing and denitrogenation pretreatment mechanism (2); the strengthening reaction kettle (301), the oxidation reaction kettle (302) and the carbon dioxide slurry adjusting reaction kettle (303) are sequentially connected in series; the discharge end of the carbon dioxide slurry adjusting reaction kettle (303) is connected with the feeding end of the third desalination treatment mechanism (4).

8. The system of claim 7, wherein: The inner cavity of the intensifying reactor (301) is connected with the feed inlet of the oxidation reactor (302) through the first delivery pump and the delivery pipe group (304); the inner cavity of the oxidation reactor (302) is connected with the feed inlet of the carbon dioxide slurry adjusting reactor (303) through the second delivery pump and the delivery pipe group (305); the inner cavity of the carbon dioxide slurry adjusting reactor (303) is connected with the feed end of the three-stage desalination treatment mechanism (4) through the third delivery pump and the delivery pipe group (306); the intensifying exhaust pipe (307) is further arranged on the top of the intensifying reactor (301); the oxidant adding pipe (308) is arranged on the side wall of the oxidation reactor (302), and the oxidation safety valve (309) is further arranged on the top of the oxidation reactor (302); the carbon dioxide adding pipe (310) is arranged on the side wall of the carbon dioxide slurry adjusting reactor (303), and the slurry adjusting safety valve (311) is further arranged on the top of the carbon dioxide slurry adjusting reactor (303).

9. The system of claim 7 or 8, characterized in that: The independent stirring mechanisms (5) are arranged in the intensifying reactor (301), the oxidation reactor (302) and the carbon dioxide slurry adjusting reactor (303); the stirring mechanism (5) comprises the stirring motor (501) independently arranged on the top of the intensifying reactor (301), the top of the oxidation reactor (302) and the top of the carbon dioxide slurry adjusting reactor (303) respectively; each stirring motor (501) is independently connected with the stirring paddle (503) arranged in the inner cavity of the corresponding reactor through the stirring shaft (502).

10. The system of claim 1, wherein: The three-stage desalination treatment mechanism (4) comprises the belt filter (401), the salt water pool (402) and the spray head (403); the feed end of the belt filter (401) is connected with the discharge end of the secondary intensifying and desulfurization treatment mechanism (3); the salt water pool (402) is arranged below the belt filter (401); the spray head (403) is arranged above the belt filter (401), and the spray head (403) is connected with the external water source through the water delivery pipe.

11. The system of claim 10, wherein: According to the material direction, the belt filter (401) is divided into the spray first section (4011), the spray second section (4012) and the spray third section (4013) which are sequentially connected in series; the independent spray head (403) is arranged above the spray first section (4011), the spray second section (4012) and the spray third section (4013) respectively; the salt water pool (402) comprises the high concentration pool (4021) below the spray first section (4011), the medium concentration pool (4022) below the spray second section (4012) and the low concentration pool (4023) below the spray third section (4013); the high concentration pool (4021), the medium concentration pool (4022) and the low concentration pool (4023) are not connected with each other.

12. The system of claim 11, wherein: The water inlet end of the spray head (403) above the first spray section (4011) is connected to the drain of the medium concentration tank (4022) through a water pipe and a water pump; the water inlet end of the spray head (403) above the second spray section (4012) is connected to the drain of the low concentration tank (4023) through a water pipe and a water pump; the water inlet end of the spray head (403) above the third spray section (4013) is connected to an external clean water source through a water pipe and a water pump; Alternatively, the water inlet end of the spray head (403) above the first spray section (4011) and the water inlet end of the spray head (403) above the third spray section (4013) are both connected to an external clean water source through a water pipe and a water pump; the water inlet end of the spray head (403) above the second spray section (4012) is connected to the drain of the medium concentration tank (4022) through a water pipe and a water pump; the drain of the low concentration tank (4023) is connected to the water inlet of the medium concentration tank (4022) through a water pipe and a water pump; and a salt concentration detector (404) is arranged in the medium concentration tank (4022).

13. The system of any of claims 10-12, wherein: The system further comprises a dryer (6) and a storage bin (7); the feed inlet of the dryer (6) is connected to the feed inlet of the belt filter (401); the discharge end of the dryer (6) is connected to the feed inlet of the storage bin (7) through a lifting machine (8).

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