Harmless treatment system and method for aluminum ash

Abstract

The invention discloses an aluminum ash innocent treatment system. The system comprises a pretreatment module used for smashing, impurity removal and water washing of collected aluminum ash; the high-temperature melting module is used for melting the washed aluminum ash, energy is supplemented through metal aluminum oxidation heat release, aluminum nitride reacts with oxygen to generate aluminum oxide and nitrogen, meanwhile, the melting point is reduced through a fluxing agent, metal aluminum and slag are promoted to be separated, and the metal aluminum and the slag are collected respectively; the slag powder treatment module is used for carrying out quenching, crushing and grinding, acid leaching, microwave sintering and the like on the high-temperature molten slag so as to remove harmful substances, solidify heavy metal and convert the heavy metal into slag powder capable of being used as a raw material of a building material, and the waste gas treatment module is used for achieving waste gas purification and up-to-standard emission. The device has the beneficial effects that external energy input is reduced, energy consumption is reduced, purification of organic pollutants reaches the standard, manual intervention is reduced, and the operation cost is reduced.

Description

Technical Field

[0001] The present invention relates to the field of harmless treatment, and in particular to a system and method for harmless treatment of aluminum ash. Background Art

[0002] Aluminum ash is the main solid waste generated during aluminum smelting, casting and recycling, accounting for about 3%-5% of primary aluminum production. According to statistics, the world produces more than 10 million tons of aluminum ash each year, and my country, as a major aluminum industry country, has an annual production of over 3 million tons. Aluminum ash has a complex composition, mainly including metallic aluminum, aluminum oxide, aluminum nitride, as well as fluorides, heavy metals, soluble salts and other harmful substances. If it is directly piled up or landfilled without proper treatment, it will not only occupy a large amount of land resources, but the fluorides and heavy metals in it will also pollute the soil and groundwater through rainwater infiltration. Ammonia generated by aluminum nitride in contact with water will pollute the atmosphere, posing a serious threat to the ecological environment and human health.

[0003] Existing technologies include natural stacking and simple water washing, which can only remove some soluble salts and cannot effectively decompose aluminum nitride or solidify heavy metals. Aluminum nitride slowly reacts with water at room temperature to produce ammonia. If not handled properly, it will lead to continuous release of ammonia. Heavy metals exist in the slag powder in a free state and still have biological toxicity, making it difficult to meet environmental emission standards. At the same time, the traditional melting method requires raising the temperature to above 1500°C, and the energy consumption cost accounts for more than 40% of the total treatment cost. In addition, acidic gases containing fluorine and sulfur will be released during the high-temperature process. If the waste gas is not handled properly, it is easy to form acid rain pollution. In addition, traditional slag powder treatment requires natural cooling, multiple grinding, long-term acid leaching and other steps, and the overall treatment cycle is as long as 10-15 hours. Furthermore, the traditional sintering process requires continuous high-temperature heating for 4-6 hours, and energy consumption has not been fundamentally improved.

[0004] Therefore, those skilled in the art are committed to providing a system and method for harmless treatment of aluminum ash that can effectively solve the above technical problems. Summary of the Invention

[0005] To achieve the above object, the present invention provides an aluminum ash harmless treatment system, comprising:

[0006] Pre-treatment module, used for crushing, removing impurities and washing the collected aluminum ash;

[0007] The high-temperature melting module is used to melt the washed aluminum ash. The heat released by the oxidation of the metallic aluminum replenishes energy, allowing the aluminum nitride to react with oxygen to produce aluminum oxide and nitrogen. At the same time, the flux is used to lower the melting point, promoting the separation of the metallic aluminum and the slag, and collecting them separately.

[0008] The slag powder processing module is used to perform rapid cooling, crushing and grinding, acid leaching, microwave sintering and other treatments on the slag after high-temperature melting to remove harmful substances, solidify heavy metals and convert them into slag powder that can be used as raw materials for building materials;

[0009] The exhaust gas treatment module is used to purify the exhaust gas and ensure that it meets the emission standards.

[0010] Furthermore, the pretreatment module includes a jaw crusher, a vibrating screen, a water washing tank, an agitator and a solid-liquid separator. The jaw crusher and the vibrating screen are used to crush the collected aluminum ash to 0.5-5 mm and screen out large-sized impurities; the water washing tank, the agitator and the solid-liquid separator are used to wash the crushed and screened aluminum ash for 20-40 minutes at a water temperature of 40-60°C to remove surface fluorides and soluble salts, and separate the washed aluminum ash and washing wastewater.

[0011] Furthermore, the slag powder processing module includes a quenching unit for quenching the molten slag to form a vitreous body and inhibit the precipitation of harmful substances;

[0012] The crushing and grinding unit is used to crush and grind the slag after rapid cooling to 50-100 μm to obtain slag powder;

[0013] The acid leaching unit is used to remove harmful substances from the slag powder. After solid-liquid separation, the leachate enters the heavy metal recovery system, and the leached slag is washed and dried. In this embodiment, as a further preference, the acid leaching unit also includes an ultrasonic vibration device for destroying the passivation film on the surface of the slag powder through cavitation effect, thereby shortening the acid leaching time to 30-45 minutes.

[0014] A microwave sintering unit is used to ultrasonically treat the leached residue with a 5%-10% silane coupling agent solution for 15-30 minutes and then dry it;

[0015] Mixing mixer, used to prepare composite additives; enhance the solidification effect of heavy metals.

[0016] Gradient field intensity microwave sintering furnace unit is used to sinter mixed materials to form dense building material raw materials; the heavy metal solidification rate is ≥92%, and the crystal orientation growth improves strength.

[0017] A waste heat recovery unit is installed on the top of the microwave sintering furnace to introduce the sintering waste gas (80-120°C) into the spray tower preheating section of the waste gas treatment module to heat 5-10% sodium hydroxide solution to 40-50°C, reducing the heating energy consumption of the spray tower by 15%-20% and increasing the fluoride removal rate by 5-8%;

[0018] The exhaust gas treatment module includes a cyclone dust collector for removing particulate matter in the exhaust gas; a spray tower for removing acidic gases; and an activated carbon adsorption tower for adsorbing organic pollutants with activated carbon.

[0019] Furthermore, it also includes a wastewater treatment unit and a control unit:

[0020] The wastewater treatment unit is used to treat water washing wastewater and acid leaching wastewater. The water washing wastewater is filtered through a ceramic membrane with a pore size of 0.1-0.5μm to remove suspended matter, and then separated and recovered by an electrodialysis membrane to recover fluoride ions and heavy metal ions. The treated wastewater is 100% reused in the water washing process, and the fluoride ion recovery rate is ≥90%.

[0021] The control unit includes a PLC control cabinet, a temperature sensor, a pressure sensor, a flow sensor and an AI intelligent control module. The AI ​​intelligent control module automatically optimizes process parameters based on real-time monitoring data (rotary kiln temperature, slag powder heavy metal content, microwave power) through a machine learning algorithm. When the lead content in the slag powder exceeds the standard, the proportion of boric acid in the composite additive is automatically increased to 2.5% and the microwave sintering time is extended by 5-10 minutes.

[0022] A method for harmless treatment of aluminum ash comprises the following steps:

[0023] S1: pre-treating the collected aluminum ash;

[0024] S2: melting the pretreated aluminum ash at high temperature to form slag;

[0025] S3: After high-temperature melting treatment, cooling, crushing, and grinding are performed to obtain slag powder;

[0026] S4: acid leaching of the slag powder and solid-liquid separation;

[0027] S5: The generated exhaust gas is subjected to dust removal treatment through a cyclone dust collector to remove particulate matter in the exhaust gas; then it enters a spray tower and is sprayed and washed with a 5-10% by mass sodium hydroxide solution to remove acidic gases such as fluoride and sulfur dioxide in the exhaust gas; finally, the organic pollutants and residual harmful substances in the exhaust gas are adsorbed by an activated carbon adsorption device, and the treated exhaust gas is finally discharged.

[0028] Furthermore, the pretreatment in step S1 specifically includes: crushing the collected aluminum ash, then screening the crushed aluminum ash, and making the aluminum ash particle size reach 0.5-5mm by screening, so as to remove larger impurities, and then washing the crushed and screened aluminum ash for 20-40min in a water temperature environment of 40-60°C. In the present invention, by setting the temperature and time, it is possible to efficiently remove some fluorides and soluble salts attached to the surface of the aluminum ash. After the washing is completed, the solid-liquid separation operation is carried out in time to obtain washed aluminum ash and washing wastewater respectively, and the washing wastewater is purified by the wastewater treatment system. In this embodiment, as a preference, the collected metallic aluminum (purity 98%) enters a vacuum distillation furnace (pressure <10Pa, temperature 850°C) for distillation and purification, and the residual amount of impurities (Fe, Si) is <0.1%, and the aluminum purity is increased to 99.9%, which can be used for 6061 aluminum alloy production.

[0029] Furthermore, step S2 specifically includes sending the washed aluminum ash into a rotary furnace for high-temperature melting treatment, wherein the temperature in the rotary furnace is controlled at 1200-1400°C, and air or oxygen is introduced to cause the metallic aluminum in the aluminum ash to oxidize and release heat, replenishing some heat, while causing the aluminum nitride to react with oxygen to produce aluminum oxide and nitrogen, with a reaction time of 1-3 hours; during the high-temperature melting process, a flux with a mass fraction of 5-10% is added, and the flux is a mixture of sodium carbonate and calcium oxide. In the present invention, the addition of the flux lowers the melting point of the aluminum ash, promotes the melting of the aluminum ash and the separation of impurities, forming a metal phase and a slag phase, and the slag is discharged through the slag discharge port, and the metallic aluminum is collected through the aluminum outlet. As a preferred embodiment of the present invention, a low-temperature melting section is further added after the rotary furnace, and microwave-assisted heating (power 200-300W) is simultaneously turned on. The selective heating of Na2CO3 by microwaves shortens the separation time of metallic aluminum and slag from 2 hours to 45 minutes, reducing energy consumption by 18%.

[0030] Furthermore, step S3 specifically includes rapidly cooling the discharged slag by water cooling at a cooling rate of 50-100°C / s, so that the slag solidifies and forms a glass body by cooling. In the present invention, the precipitation of harmful substances is suppressed by this method; then the rapidly cooled slag is crushed and ground to a particle size of 50-100 μm to obtain slag powder.

[0031] Furthermore, step S4 specifically includes acid leaching the slag powder, using a 10-20% by mass sulfuric acid solution at a temperature of 60-80°C for 1-2 hours. In the present invention, acid leaching removes harmful substances from the slag powder. After acid leaching, solid-liquid separation is performed to obtain a leachate and leachate residue. The leachate enters a heavy metal recovery system for treatment, and the leachate residue is washed and dried. The slag can be used as a raw material for building materials.

[0032] Furthermore, between step S4 and step S5, the dried leaching residue is mixed with silicon dioxide powder and then subjected to microwave sintering, specifically comprising:

[0033] S41: placing the dried leached residue in a 5%-10% silane coupling agent aqueous solution, ultrasonically treating for 15-30 minutes, and then drying to a moisture content of less than 1%;

[0034] S42: uniformly mixing 3%-5% silicon dioxide, 1%-2% boric acid, and 0.5%-1% nano-TiO2 according to mass fractions to form a composite additive;

[0035] S43: mixing the pretreated leaching residue and the composite additive in a ratio of 9:1, and stirring for 20-30 minutes in a mixer to form a mixture;

[0036] S44: Place the mixed material in a gradient field intensity microwave sintering furnace with a main microwave source frequency of 2.45 GHz and a power density of 1.2-1.5 W / cm at the bottom of the furnace cavity. 3 The side wall auxiliary microwave source frequency is 1.8GHz and the power density is 0.8-1.0W / cm 3 ;

[0037] S45: Pulse heating mode is used to perform the following three stages:

[0038] S45a: The first stage heating time is ten minutes and the power is 800W. In the present invention, the temperature is quickly raised to the starting temperature required for sintering through the first stage;

[0039] S45b: In the second stage, after the power is reduced from 800W to 500W, an intermittent heating operation is performed, wherein the intermittent heating specifically includes:

[0040] S45b1: The microwave power is maintained at 500 W, and the heating time is 1-1.5 minutes to heat the material;

[0041] S45b2: The microwave power is turned off for 3.5-6 minutes. This is a pause state. The material is no longer actively heated. The material relies on its own residual heat to maintain internal heat conduction and release thermal stress.

[0042] S45b3: Turn on the 500W power again for active heating. The active heating time in this stage is 3.5 minutes.

[0043] S45b4: Turn off the power again and pause for 2-3.5 minutes; S45c: In the third stage, adjust the power to 650W and continue heating for 16.5-17.5 minutes.

[0044] The present invention has the following beneficial effects:

[0045] 1. In the high-temperature melting module, aluminum nitride reacts fully with oxygen to generate aluminum oxide and nitrogen by controlling the temperature. The decomposition rate can reach over 98%, eliminating the potential pollution risk of aluminum nitride generating ammonia when it comes into contact with water. At the same time, the slag powder treatment module removes soluble heavy metals in the slag powder through acid leaching. At the same time, through composite additives and microwave sintering, the heavy metal solidification rate is ≥92%, effectively inhibiting the dissolution of heavy metals.

[0046] 2. The exhaust gas treatment module uses a three-stage treatment process consisting of cyclone dust removal, alkaline solution spraying, and activated carbon adsorption to improve the fluoride removal rate and purify acidic gases and organic pollutants to meet standards. The wastewater treatment unit uses ceramic membrane filtration and electrodialysis membrane separation, with a fluoride ion recovery rate of ≥90%. 100% of the treated wastewater is reused in the water washing process. This achieves zero emissions.

[0047] 3. After microwave sintering, the slag powder is converted into dense building material raw materials, which can be used to prepare concrete admixtures, ceramic products, etc., realizing the utilization of slag. In this way, the present invention effectively improves the economic value compared with the traditional landfill method. At the same time, the heat released by the oxidation of metal aluminum is used to supplement part of the heat, reducing external energy input. The waste heat recovery unit at the top of the microwave sintering furnace uses the sintering waste gas to heat the spray tower alkali solution, reducing energy consumption.

[0048] 4. The PLC control cabinet is combined with temperature, pressure and flow sensors to realize automatic linkage control of each link of pretreatment, melting, slag powder treatment and waste gas and wastewater treatment, reducing manual intervention and lowering operating costs. BRIEF DESCRIPTION OF THE DRAWINGS

[0049] Figure 1 It is a schematic block diagram of the method flow in the present invention;

[0050] Figure 2 It is a schematic structural diagram of the aluminum ash harmless treatment system of the present invention;

[0051] Figure 3 It is a structural schematic diagram of a specific embodiment of the plant layout of the present invention;

[0052] Figure 4 yes Figure 3 A schematic diagram of the partially enlarged structure at center A;

[0053] Figure 5 yes Figure 3 A schematic diagram of the partially enlarged structure at point B in the middle;

[0054] Figure 6 yes Figure 3 A schematic diagram of the partially enlarged structure at point C in the middle;

[0055] Figure 7 yes Figure 3 The schematic diagram of the local enlarged structure at D in the middle;

[0056] Figure 8 yes Figure 3 The schematic diagram of the local enlarged structure at E in the middle;

[0057] Figure 9 yes Figure 3 The schematic diagram of the partially enlarged structure at F in the middle;

[0058] Figure 10 This is a schematic diagram of the equipment connection logic of the pre-processing module in the present invention;

[0059] Figure 11 This is a logic diagram of microwave-assisted heating of the high-temperature melting module of the present invention;

[0060] Figure 12 This is a logic diagram of ultrasonic acid leaching of the slag powder processing module of the present invention;

[0061] Figure 13 This is a logical diagram of waste heat utilization of the exhaust gas treatment module in the present invention;

[0062] Figure 14 This is a logic diagram of gradient field intensity heating and waste heat recovery of the microwave sintering furnace of the present invention;

[0063] Figure 15 It is a logical schematic diagram of the membrane separation process of the wastewater treatment unit in the present invention.

[0064] In the accompanying drawings, the components represented by the reference numerals are as follows:

[0065] 1. Main entrance and exit of the factory area; 2. Parking lot (10 charging parking spaces, 1 barrier-free parking space); 3. Biochemical pool (top of the pool covered with soil and greening); 4. Building C (frame structure, building fire resistance rating: Class II); 5. Weighbridge; 6. Building B (gantry steel frame structure, building fire resistance rating: Class II); 7. Rotary furnace smelting workshop; 8. Aluminum ingot finished product workshop; 9. Building A; 10. Rotary kiln equipment area; 11. Aluminum ash and aluminum slag storage area; 12. Operation room; 13. Dust collection and discharge pipeline; 15 1. Dust collector outlet; 2. Limestone storage yard; 3. Air compressor room; 4. Ball mill; 5. Raw material preparation production line; 6. Guardhouse; 7. Rainwater collection tank; 8. Accident pool; 9. Crushing and packaging line; 10. Dust collector; 11. Aluminum ash extraction production line; 12. Secondary entrance and exit of the plant; 13. Desulfurization tower and outlet; 14. Rotary kiln; 15. Centralized dust collection and discharge pipeline; 16. Multi-tube water-cooled radiator; 17. Deacidification tower; 18. Bag filter; 19. Desulfurization tower; 20. DETAILED DESCRIPTION

[0066] The present invention will be further described below with reference to the accompanying drawings and examples:

[0067] In the description of the present invention, it should be noted that the terms "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate and simplify the description of the present invention. They are not intended to indicate or imply that the devices or components referred to must have, be constructed, or operate in a specific orientation, and therefore should not be construed as limitations on the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0068] In the description of the present invention, it should be noted that, unless otherwise expressly specified or limited, the terms "installed," "installed," and "connected" should be understood in a broad sense. For example, they may refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in the present invention based on the specific circumstances.

[0069] like Figures 1 to 15 As shown, a harmless treatment system for aluminum ash includes:

[0070] Pre-treatment module, used for crushing, removing impurities and washing the collected aluminum ash;

[0071] The high-temperature melting module is used to melt the washed aluminum ash, release heat through the oxidation of the metal aluminum to replenish energy, so that the aluminum nitride reacts with oxygen to produce aluminum oxide and nitrogen. At the same time, the melting point is lowered by the use of flux, which promotes the separation of the metal aluminum and the slag and their separate collection. In the present invention, the high-temperature melting module includes a rotary kiln for high-temperature melting of the washed aluminum ash;

[0072] The rotary kiln is connected to the pretreatment module, and the pretreated water-washed aluminum ash is fed into the feed end of the rotary kiln through a conveying device; the rotary kiln is connected to the slag powder treatment module, and the slag discharged from the rotary kiln enters the quenching unit of the slag powder treatment module for quenching treatment; the rotary kiln is connected to the exhaust gas treatment module, and the exhaust gas generated by the rotary kiln is connected to the cyclone dust collector (dust collector) of the exhaust gas treatment module for dust removal treatment. In the present invention, the rotary kiln of the high-temperature melting module has a rotatable furnace body, an inner diameter of 2-5 meters, a length of 10-30 meters, a furnace body inclination angle of 1-5 degrees, a rotation speed of 0.5-2 revolutions per minute, and the lining material of the rotary kiln is made of high-temperature resistant and corrosion-resistant materials, which effectively extends the service life.

[0073] like Figure 5As shown in the figure, a low-temperature melting section (temperature 900-1100℃) is added to the tail of the rotary furnace, and an auxiliary microwave source (power 200-300W) is turned on simultaneously. The selective heating of sodium carbonate by microwaves can shorten the separation time of metallic aluminum and slag from 2h to 45min.

[0074] The rotary kiln can be heated by gas, oil, or electricity, depending on the actual situation. In order to further improve energy utilization, a waste heat recovery structure is installed at the rear of the rotary kiln to recover the waste heat from the high-temperature exhaust gas and use it to preheat the combustion air.

[0075] The slag powder processing module is used to perform rapid cooling, crushing and grinding, acid leaching, microwave sintering and other treatments on the slag after high-temperature melting to remove harmful substances, solidify heavy metals and convert them into slag powder that can be used as raw materials for building materials; Figure 6 As shown, the acid leaching unit is equipped with an ultrasonic vibration device (frequency 20-40kHz), which destroys the passivation film on the surface of the slag powder through the cavitation effect, shortening the acid leaching time to 30-45 minutes. The leached slag is treated with a silane coupling agent and then enters the microwave sintering furnace.

[0076] The exhaust gas treatment module is used to purify the exhaust gas and meet the emission standards. Figure 7 As shown, the sintering waste gas passes through the waste heat recovery unit ( Figure 8 ) The heated sodium hydroxide solution enters the spray tower. A preheating section is set at the bottom of the spray tower to use the waste heat of sintering exhaust gas to heat the alkali solution to 40-50°C, thereby improving the fluoride removal efficiency.

[0077] The pretreatment module includes a jaw crusher, a vibrating screen, a water washing tank, an agitator and a solid-liquid separator. The jaw crusher and the vibrating screen are used to crush the collected aluminum ash to 0.5-5 mm and screen out large-sized impurities; the water washing tank, the agitator and the solid-liquid separator are used to wash the crushed and screened aluminum ash for 20-40 minutes at a water temperature of 40-60°C to remove surface fluorides and soluble salts, and separate the washed aluminum ash and washing wastewater.

[0078] like Figure 4 As shown, the aluminum ash is coarsely crushed by a jaw crusher and then enters a vibrating screening machine. The oversize material (particle size > 5mm) returns to the crusher, and the undersize material (0.5-5mm) enters a washing tank. The agitator in the washing tank maintains a water temperature of 40-60°C and stirs for 20-40 minutes. The solid-liquid separator separates the washed aluminum ash from the wastewater.

[0079] The slag powder processing module of the present invention includes a quenching unit (water cooling tank) for rapidly cooling the slag to form a vitreous body and inhibiting the precipitation of harmful substances;

[0080] Crushing and grinding unit (cone crusher, ball mill), used to crush and grind the quenched slag to 50-100 μm to obtain slag powder;

[0081] The acid leaching unit (acid leaching reactor, agitator) is used to remove harmful substances from the slag powder. After solid-liquid separation, the leachate enters the heavy metal recovery system, and the leached slag is washed and dried. In this embodiment, as a further preferred embodiment, the acid leaching unit also includes an ultrasonic vibration device (frequency 20-40kHz, power density 0.5-1W / cm 3 ), which is used to destroy the passivation film on the surface of the slag powder through the cavitation effect, shortening the acid leaching time to 30-45 minutes.

[0082] In the present invention, an ultrasonic vibration device is introduced into the acid leaching unit to destroy the passivation film on the surface of the slag powder through the cavitation effect, shortening the acid leaching time from 1-2 hours to 30-45 minutes; the full-process processing cycle is compressed from 10-15 hours in the traditional process to 5-6 hours, thereby increasing its production efficiency by 2-3 times.

[0083] Microwave sintering unit (silane coupling agent treatment tank, ultrasonic processor, dryer), used to ultrasonically treat the leached residue with 5%-10% silane coupling agent solution for 15-30 minutes and then dry it;

[0084] Mixing mixer, used to prepare composite additives; enhance the solidification effect of heavy metals.

[0085] Gradient field intensity microwave sintering furnace unit (microwave sintering furnace, axial magnetic field generator) is used to sinter mixed materials to form dense building material raw materials; the heavy metal solidification rate is ≥92%, and the crystal orientation growth improves strength.

[0086] The gradient field intensity microwave sintering furnace unit includes a furnace cavity, a main microwave source, an auxiliary microwave source and a waste heat recovery unit (such as Figure 8 The main microwave source frequency at the bottom of the furnace cavity is 2.45 GHz, and the power density is 1.2-1.5 W / cm 3 , sidewall assisted microwave source (frequency 1.8 GHz, power density 0.8-1.0 W / cm 3 ) A gradient field intensity heating area is formed through the axial magnetic field generator, so that the temperature field of the mixture is evenly distributed during the sintering process. A waste heat recovery unit is set on the top of the furnace body, and the sintering waste gas (80-120℃) is introduced into the spray tower preheating section of the waste gas treatment module through a pipe to heat 5-10% sodium hydroxide solution to 40-50℃, which can reduce the heating energy consumption of the spray tower by 15%-20% and increase the fluoride removal rate by 5-8%.

[0087] The axial magnetic field generator forms an electromagnetic field intensity that decreases along the height direction (top field intensity 0.8W / cm 3-Bottom 1.5W / cm 3 ) so that the temperature difference between the upper surface and the bottom of the material is ≤50℃ to avoid local overheating.

[0088] A waste heat recovery unit is installed on the top of the microwave sintering furnace to introduce the sintering waste gas (80-120°C) into the spray tower preheating section of the waste gas treatment module to heat 5-10% sodium hydroxide solution to 40-50°C, reducing the heating energy consumption of the spray tower by 15%-20% and increasing the fluoride removal rate by 5-8%;

[0089] The exhaust gas treatment module includes a cyclone dust collector for removing particulate matter in the exhaust gas; a spray tower for removing acidic gases (fluoride, sulfur dioxide, etc.); and an activated carbon adsorption tower for adsorbing organic pollutants with activated carbon.

[0090] The present invention also includes a wastewater treatment unit and a control unit:

[0091] The wastewater treatment unit is used to treat washing wastewater and acid leaching wastewater. The washing wastewater is filtered through a ceramic membrane with a pore size of 0.1-0.5μm to remove suspended matter, and then separated and recovered by an electrodialysis membrane to recover fluoride ions and heavy metal ions. After treatment, 100% of the wastewater is reused in the washing process, and the fluoride ion recovery rate is ≥90%. Figure 9 As shown in the figure, after the washing wastewater is filtered through a ceramic membrane (pore size 0.1-0.5μm) to remove suspended matter, it enters the electrodialysis membrane separation device to recover fluoride ions. The qualified wastewater after electrodialysis membrane separation is connected to the bottom of the washing tank through a recycling pipe (diameter DN50-80) to maintain the stability of the washing tank liquid level and water temperature. The qualified wastewater returns to the washing tank through the recycling pipe.

[0092] The control unit includes a PLC control cabinet, temperature sensors, pressure sensors, flow sensors, and an AI intelligent control module. This module uses a machine learning algorithm to automatically optimize process parameters based on real-time monitoring data (rotary kiln temperature, slag powder heavy metal content, and microwave power). If the lead content in the slag powder exceeds the standard, the module automatically increases the proportion of boric acid in the composite additive to 2.5% and extends the microwave sintering time by 5-10 minutes. This ensures a stable and controllable treatment effect and avoids manual control errors.

[0093] A method for harmless treatment of aluminum ash, comprising the following steps:

[0094] S1: pre-treating the collected aluminum ash;

[0095] S2: melting the pretreated aluminum ash at high temperature to form slag;

[0096] S3: After high-temperature melting treatment, cooling, crushing, and grinding are performed to obtain slag powder;

[0097] S4: acid leaching of the slag powder and solid-liquid separation;

[0098] S5: The generated exhaust gas is subjected to dust removal treatment through a cyclone dust collector to remove particulate matter in the exhaust gas; then it enters a spray tower and is sprayed and washed with a 5-10% by mass sodium hydroxide solution to remove acidic gases such as fluoride and sulfur dioxide in the exhaust gas; finally, the organic pollutants and residual harmful substances in the exhaust gas are adsorbed by an activated carbon adsorption device, and the treated exhaust gas is finally discharged.

[0099] The pretreatment in step S1 specifically includes: crushing the collected aluminum ash, then screening the crushed aluminum ash, and making the aluminum ash particle size reach 0.5-5mm by screening, so as to remove larger impurities, and then washing the crushed and screened aluminum ash for 20-40 minutes under a water temperature environment of 40-60°C. In the present invention, by setting the temperature and time, it is possible to efficiently remove some fluorides and soluble salts attached to the surface of the aluminum ash. After the washing is completed, the solid-liquid separation operation is carried out in time to obtain washed aluminum ash and washing wastewater respectively, and the washing wastewater is purified by the wastewater treatment system. In this embodiment, as a preference, the collected metallic aluminum (purity 98%) enters a vacuum distillation furnace (pressure <10Pa, temperature 850°C) for distillation and purification, and the residual amount of impurities (Fe, Si) is <0.1%, and the aluminum purity is increased to 99.9%, which can be used for 6061 aluminum alloy production.

[0100] The step S2 specifically includes sending the washed aluminum ash into a high-temperature rotary furnace for high-temperature melting treatment, wherein the temperature in the high-temperature rotary furnace is controlled at 1200-1400°C, and air or oxygen is introduced to oxidize the metallic aluminum in the aluminum ash to release heat, replenish part of the heat, and simultaneously react the aluminum nitride with oxygen to generate aluminum oxide and nitrogen, and the reaction time is 1-3 hours; during the high-temperature melting process, adding a flux with a mass fraction of 5-10%, and the flux is a mixture of sodium carbonate and calcium oxide. In the present invention, by adding the flux, the melting point of the aluminum ash is lowered, the melting of the aluminum ash and the separation of impurities are promoted, and a metal phase and a slag phase are formed. The slag is discharged through the slag discharge port, and the metallic aluminum is collected through the aluminum outlet. As a preferred embodiment, the present invention further adds a low-temperature melting section (temperature 900-1100°C) after the high-temperature rotary kiln, and simultaneously starts microwave-assisted heating (power 200-300W). The selective heating of Na2CO3 by microwaves is used to shorten the separation time of metal aluminum and slag from 2h to 45min, and the energy consumption is reduced by 18%; compared with traditional sintering, the microwave sintering time is shortened from 4-6h to 1h, thereby reducing its energy consumption; in this embodiment, the heat released by the oxidation of metal aluminum can provide 30%-40% of the heat required for melting, reducing the energy consumption of the rotary kiln by 25-30kWh / ton of aluminum ash, and combining with a flux (sodium carbonate-calcium oxide mixture) to reduce the melting temperature from 1500°C to 1200-1400°C.

[0101] The step S3 specifically includes rapidly cooling the discharged slag by water cooling at a cooling rate of 50-100°C / s, thereby solidifying the slag and forming a vitreous body. In the present invention, this method suppresses the precipitation of harmful substances; and then crushing and grinding the rapidly cooled slag to a particle size of 50-100 μm to obtain slag powder.

[0102] Step S4 specifically includes acid leaching the slag powder using a 10-20% by mass sulfuric acid solution at a temperature of 60-80°C for 1-2 hours. In the present invention, acid leaching removes harmful substances from the slag powder. After acid leaching, solid-liquid separation is performed to obtain a leachate and leach residue. The leachate is processed in a heavy metal recovery system, and the leach residue is washed and dried. The slag can be used as a raw material for building materials.

[0103] The step between step S4 and step S5 further includes mixing the dried leaching residue with silicon dioxide powder and then performing microwave sintering, specifically comprising:

[0104] S41: placing the dried leached residue in a 5%-10% silane coupling agent aqueous solution, ultrasonically treating for 15-30 minutes, and then drying to a moisture content of less than 1%;

[0105] S42: uniformly mixing 3%-5% silicon dioxide, 1%-2% boric acid, and 0.5%-1% nano-TiO2 according to mass fractions to form a composite additive;

[0106] S43: mixing the pretreated leaching residue and the composite additive in a ratio of 9:1, and stirring for 20-30 minutes in a mixer to form a mixture (three-dimensional mixer);

[0107] S44: Place the mixed material in a gradient field intensity microwave sintering furnace with a main microwave source frequency of 2.45 GHz and a power density of 1.2-1.5 W / cm at the bottom of the furnace cavity. 3 The side wall auxiliary microwave source frequency is 1.8GHz and the power density is 0.8-1.0W / cm 3 ;

[0108] S45: Pulse heating mode is used to perform the following three stages:

[0109] S45a: The first stage heating time is ten minutes and the power is 800W. In the present invention, the temperature is quickly raised to the starting temperature required for sintering through the first stage;

[0110] S45b: In the second stage, after the power is reduced from 800W to 500W, an intermittent heating operation is performed, wherein the intermittent heating specifically includes:

[0111] S45b1: The microwave power is maintained at 500 W, and the heating time is 1-1.5 minutes to heat the material;

[0112] S45b2: The microwave power is turned off for 3.5-6 minutes. This is a pause state. The material is no longer actively heated. The material relies on its own residual heat to maintain internal heat conduction and release thermal stress.

[0113] S45b3: Turn on the 500W power again for active heating. The active heating time in this stage is 3.5 minutes.

[0114] S45b4: Turn off the power again and pause for 2-3.5 minutes; the above steps are used to perform active heating and pausing cycles; during the pause phase, the temperature difference between the inside and outside of the material is reduced, which can reduce microcracks caused by thermal expansion and contraction. Compared with the traditional continuous heating method, the heating method of the present invention can effectively reduce the crack rate by about 10%.

[0115] S45c: In the third stage, the power is adjusted to 650W, and heating is continued for 16.5-17.5 minutes. In the present invention, this step maintains the sintering temperature at 800-1000°C at medium and low power, which can effectively promote the slow growth of crystals and the full progress of heavy metal solidification reaction.

[0116] The present invention uses the above microwave sintering to achieve a pulse cycle of high-power heating, low-power insulation and medium-power curing, avoiding the problems of material overheating or uneven sintering caused by traditional continuous heating; at the same time, compared with the traditional sintering time of 4-6 hours, the time is greatly shortened, thereby improving efficiency and reducing costs.

[0117] Compared with traditional treatment processes, this invention can reduce ammonia emissions by more than 95%, acid gas emissions by more than 80%, and the risk of heavy metal leakage by 90%, effectively curbing the pollution of aluminum ash to soil, water and atmosphere; achieving harmless and resource-based treatment of aluminum ash, in line with the national dual carbon goals and solid waste resource utilization policies, and has significant environmental and social benefits.

[0118] The above describes in detail the preferred embodiments of the present invention. It should be understood that those skilled in the art can make numerous modifications and variations based on the concepts of the present invention without inventive effort. Therefore, any technical solutions that can be derived by those skilled in the art through logical analysis, reasoning, or limited experimentation based on the concepts of the present invention and the prior art should be within the scope of protection defined by the claims.

Claims

1. A harmless treatment system for aluminum ash, characterized by: include: Pre-treatment module, used for crushing, removing impurities and washing the collected aluminum ash; The high-temperature melting module is used to melt the washed aluminum ash. The heat released by the oxidation of the metallic aluminum replenishes energy, allowing the aluminum nitride to react with oxygen to produce aluminum oxide and nitrogen. At the same time, the flux is used to lower the melting point, promoting the separation of the metallic aluminum and the slag, and collecting them separately. The slag powder processing module is used to perform rapid cooling, crushing and grinding, acid leaching, microwave sintering and other treatments on the slag after high-temperature melting to remove harmful substances, solidify heavy metals and convert them into slag powder that can be used as raw materials for building materials; The exhaust gas treatment module is used to purify the exhaust gas and ensure that it meets the emission standards.

2. The aluminum ash harmless treatment system according to claim 1, characterized in that: The pretreatment module includes a jaw crusher, a vibrating screen, a water washing tank, an agitator and a solid-liquid separator. The jaw crusher and the vibrating screen are used to crush the collected aluminum ash to 0.5-5 mm and screen out large-sized impurities; the water washing tank, the agitator and the solid-liquid separator are used to wash the crushed and screened aluminum ash for 20-40 minutes at a water temperature of 40-60°C to remove surface fluorides and soluble salts, and separate the washed aluminum ash and washing wastewater.

3. The aluminum ash harmless treatment system according to claim 2, characterized in that: The slag powder processing module includes a quenching unit for quenching the slag to form a vitreous body and inhibit the precipitation of harmful substances; The crushing and grinding unit is used to crush and grind the slag after rapid cooling to 50-100 μm to obtain slag powder; The acid leaching unit is used to remove harmful substances from the slag powder. After solid-liquid separation, the leachate enters the heavy metal recovery system, and the leached slag is washed and dried. In this embodiment, as a further preferred embodiment, the acid leaching unit also includes an ultrasonic vibration device for destroying the passivation film on the surface of the slag powder through cavitation effect, thereby shortening the acid leaching time to 30-45 minutes. A microwave sintering unit is used to ultrasonically treat the leached residue with a 5%-10% silane coupling agent solution for 15-30 minutes and then dry it; Mixing and blending machine, used for preparing compound additives; Gradient field intensity microwave sintering furnace unit, used for sintering mixed materials to form dense building material raw materials; A waste heat recovery unit is installed on the top of the microwave sintering furnace to introduce the sintering waste gas (80-120°C) into the spray tower preheating section of the waste gas treatment module to heat 5-10% sodium hydroxide solution to 40-50°C, reducing the heating energy consumption of the spray tower by 15%-20% and increasing the fluoride removal rate by 5-8%; The exhaust gas treatment module includes a cyclone dust collector for removing particulate matter from the exhaust gas; a spray tower for removing acidic gases; Activated carbon adsorption tower, used for activated carbon adsorption of organic pollutants.

4. The aluminum ash harmless treatment system according to claim 3, characterized in that: Also includes wastewater treatment unit and control unit: The wastewater treatment unit is used to treat water washing wastewater and acid leaching wastewater. The water washing wastewater is filtered through a ceramic membrane with a pore size of 0.1-0.5 μm to remove suspended matter, and then separated and recovered by an electrodialysis membrane to recover fluoride ions and heavy metal ions; The control unit includes a PLC control cabinet, a temperature sensor, a pressure sensor, a flow sensor and an AI intelligent control module. The AI ​​intelligent control module automatically optimizes process parameters based on real-time monitoring data through a machine learning algorithm. When the lead content in the slag powder exceeds the standard, the proportion of boric acid in the composite additive is automatically increased to 2.5% and the microwave sintering time is extended by 5-10 minutes.

5. A method for harmless treatment of aluminum ash, characterized in that: The following steps are involved: S1: pre-treating the collected aluminum ash; S2: melting the pretreated aluminum ash at high temperature to form slag; S3: After high-temperature melting treatment, cooling, crushing, and grinding are performed to obtain slag powder; S4: acid leaching of the slag powder and solid-liquid separation; S5: The generated exhaust gas is subjected to dust removal treatment through a cyclone dust collector to remove particulate matter in the exhaust gas; then it enters a spray tower and is sprayed and washed with a 5-10% by mass sodium hydroxide solution to remove acidic gases such as fluoride and sulfur dioxide in the exhaust gas; finally, the organic pollutants and residual harmful substances in the exhaust gas are adsorbed by an activated carbon adsorption device, and the treated exhaust gas is finally discharged.

6. The harmless treatment method for aluminum ash according to claim 5, characterized in that: The pretreatment in step S1 specifically includes: crushing the collected aluminum ash, then screening the crushed aluminum ash to reduce the particle size of the aluminum ash to 0.5-5mm by screening, thereby removing larger impurities, and then washing the crushed and screened aluminum ash for 20-40 minutes at a water temperature of 40-60°C. After the washing is completed, a solid-liquid separation operation is promptly performed to obtain washed aluminum ash and washing wastewater, respectively, and the washing wastewater is purified by a wastewater treatment system. In this embodiment, as a preference, the collected metallic aluminum (purity 98%) enters a vacuum distillation furnace (pressure <10Pa, temperature 850°C) for distillation and purification, and the residual impurities (Fe, Si) are <0.1%, and the aluminum purity is increased to 99.9%, which can be used for 6061 aluminum alloy production.

7. The harmless treatment method for aluminum ash according to claim 6, characterized in that: The step S2 specifically includes sending the washed aluminum ash into a rotary furnace for high-temperature melting treatment, wherein the temperature in the rotary furnace is controlled at 1200-1400°C, and air or oxygen is introduced to oxidize the metallic aluminum in the aluminum ash to release heat and replenish part of the heat, while allowing the aluminum nitride to react with oxygen to generate aluminum oxide and nitrogen, and the reaction time is 1-3 hours; during the high-temperature melting process, adding a flux with a mass fraction of 5-10%, wherein the flux is a mixture of sodium carbonate and calcium oxide, to form a metal phase and a slag phase, the slag is discharged through a slag discharge port, and the metallic aluminum is collected through an aluminum outlet.

8. The harmless treatment method for aluminum ash according to claim 7, characterized in that: The step S3 specifically includes rapidly cooling the discharged slag by water cooling at a cooling rate of 50-100°C / s, solidifying the slag and forming a glass body by cooling, and then crushing and grinding the rapidly cooled slag to a particle size of 50-100 μm to obtain slag powder.

9. The harmless treatment method for aluminum ash according to claim 8, characterized in that: The step S4 specifically includes acid leaching the slag powder, wherein the acid used for the acid leaching is a sulfuric acid solution with a mass fraction of 10-20%, the acid leaching temperature is 60-80°C, and the acid leaching time is 1-2 hours. After the acid leaching, solid-liquid separation is performed to obtain a leachate and a leachate residue. The leachate enters a heavy metal recovery system for treatment, and the leachate residue is washed and dried.

10. The harmless treatment method for aluminum ash according to claim 9, characterized in that: The step between step S4 and step S5 further includes mixing the dried leaching residue with silicon dioxide powder and then performing microwave sintering, specifically comprising: S41: placing the dried leached residue in a 5%-10% silane coupling agent aqueous solution, ultrasonically treating for 15-30 minutes, and then drying to a moisture content of less than 1%; S42: uniformly mixing 3%-5% silicon dioxide, 1%-2% boric acid, and 0.5%-1% nano-TiO2 according to mass fractions to form a composite additive; S43: mixing the pretreated leaching residue and the composite additive in a ratio of 9:1, and stirring for 20-30 minutes in a mixer to form a mixture; S44: Place the mixed material in a gradient field intensity microwave sintering furnace with a main microwave source frequency of 2.45 GHz and a power density of 1.2-1.5 W / cm at the bottom of the furnace cavity. 3 The side wall auxiliary microwave source frequency is 1.8GHz and the power density is 0.8-1.0W / cm 3 ; S45: Pulse heating mode is used to perform the following three stages: S45a: The first stage heating time is ten minutes and the power is 800W; S45b: In the second stage, after the power is reduced from 800W to 500W, an intermittent heating operation is performed, wherein the intermittent heating specifically includes: S45b1: The microwave power is maintained at 500 W, and the heating time is 1-1.5 minutes to heat the material; S45b2: The microwave power is turned off for 3.5-6 minutes. This is a pause state. The material is no longer actively heated. The material relies on its own residual heat to maintain internal heat conduction and release thermal stress. S45b3: Turn on the 500W power again for active heating. The active heating time in this stage is 3.5 minutes. S45b4: Turn off the power again and pause for 2-3.5 minutes; S45c: In the third stage, adjust the power to 650W and continue heating for 16.5-17.5 minutes.

Images