Method and device for co-producing white carbon black and aluminum trioxide from coal gasification ash

Abstract

This invention relates to the field of coal gasification ash and slag resource utilization technology, specifically to a method and apparatus for co-producing silica and alumina from coal gasification ash and slag. The invention comprises methods and steps such as ash and slag decarbonization, alkali dissolution activation and impurity removal, silica production, alumina production, and mother liquor recycling, along with corresponding apparatus units. Through this invention, silica and alumina products are produced from coal gasification slag, thus effectively utilizing coal gasification slag resources.

Description

Technical Field

[0001] This invention relates to the field of coal gasification ash and slag resource utilization technology, specifically to a method and apparatus for co-producing silica and alumina from coal gasification ash and slag. Background Technology

[0002] Coal gasification ash is a major solid waste generated by coal gasification plants, comprising coarse and fine ash. Its main chemical components are silicon dioxide and aluminum oxide, while also containing iron oxide, calcium oxide, and a large amount of residual carbon. Currently, coal gasification ash is mostly disposed of through stockpiling, which occupies land resources, easily causes environmental pollution, and wastes silicon and aluminum resources.

[0003] Existing technologies for extracting silicon and aluminum components from coal-based solid waste have several drawbacks: a lack of differentiated treatment processes for coarse and fine coal gasification ash residues; the high residual carbon content in fine residues affecting product purity; the simultaneous dissolution of silicon and aluminum in traditional acid-base leaching processes, leading to difficult separation and low product purity; and high consumption of process reagents, lack of closed-loop recycling, and high production costs. Therefore, developing a coal gasification ash residue treatment process that can efficiently decarbonize, accurately separate silicon and aluminum, and co-produce high-value-added products has significant industrial value. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention provides a method and apparatus for co-producing silica and alumina from coal gasification ash residue, solving the technical problems of incomplete decarbonization, difficulty in separating silicon and aluminum, low product purity, and low resource utilization in existing processes.

[0005] To achieve the above objectives, the present invention adopts the following technical solution: A method for co-producing silica and alumina from coal gasification ash residue includes the following steps: Ash and slag decarbonization: Coal gasification coarse slag and / or fine slag are fed into a low-temperature oxidation decarbonization furnace, with the temperature controlled at 350℃~450℃. After holding at this temperature for a period of time, the material is transferred to a high-temperature roasting furnace and held at 650~750℃ for several hours to achieve deep decarbonization. The residual carbon content of the material is ≤1.0%. Alkali dissolution activation and impurity removal: The decarburized ash residue is transported to the alkali dissolution reactor, and a NaOH solution with a mass concentration of 10% to 30% is added and stirred to react. The reaction product is separated by a plate and frame filter press. The filter cake contains iron and calcium impurities, and the filtrate is a mixture of sodium aluminosilicate. Silica production: Sodium aluminosilicate mixture is fed into a silica reactor, carbon dioxide gas is introduced, the pH is adjusted to 8.5~9.5, and the temperature is 60℃~80℃ to produce silica precursor; the silica precursor is washed by a centrifugal washer until the conductivity is ≤50μS / cm, and then sent to a spray drying tower with an inlet temperature of 250℃~300℃ and an outlet temperature of 100℃~120℃ to obtain the finished silica product; Aluminum oxide production: Activated carbon is added to the silica mother liquor for adsorption and purification. After filtration, the liquor is sent to an aluminum oxide reactor. Carbon dioxide is introduced to adjust the pH to 7.0~8.0. The reaction is carried out at 40℃~60℃ to obtain aluminum hydroxide precipitate. After washing, the precipitate is calcined in a rotary calcining furnace at 1100℃~1200℃ to obtain aluminum oxide. Mother liquor recycling: The mother liquor after aluminum precipitation is transported to the evaporation and concentration tank. Lime milk (Ca(OH)2) is added to the concentrated mother liquor to carry out the causticization reaction. The NaOH alkaline solution produced by the reaction is returned to the alkaline dissolution reactor to realize the recycling of the reagent.

[0006] The raw materials used in this invention are coarse and fine coal gasification slag, and their typical chemical composition (mass fraction) is as follows: Coarse slag: SiO2 40%~50%, Al2O3 18%~25%, Fe2O3 3%~8%, CaO 2%~5%, residual carbon 2%~10%, other impurities ≤5%; Fine slag: SiO2 35%~45%, Al2O3 15%~22%, Fe2O3 5%~12%, CaO 3%~8%, residual carbon 10%~30%, other impurities ≤8%.

[0007] A device for co-producing silica and alumina from coal gasification ash residue includes an ash residue pretreatment unit, an ash residue decarbonization unit, an alkali dissolution activation and impurity removal unit, a silica production unit, an alumina production unit, and a mother liquor circulation unit. Each unit is connected via pipelines and pumps to achieve continuous production. The specific device is as follows: The ash and slag pretreatment unit includes a vibrating screen, a mixer, and a screw conveyor connected in sequence.

[0008] The ash decarbonization unit includes a low-temperature oxidation decarbonization furnace, a high-temperature roasting furnace, a hot blast stove, and a tail gas treatment device.

[0009] The alkaline dissolution activation and impurity removal unit includes an alkaline dissolution reactor, a plate and frame filter press (a), a flocculation sedimentation tank, and a matching NaOH solution preparation tank.

[0010] The silica production unit includes a silica reactor, a carbon dioxide supply system, a centrifugal washer, a spray drying tower, and a silica finished product storage silo.

[0011] The aluminum oxide production unit includes an activated carbon adsorption device, an aluminum oxide reaction vessel, a filter press and washing machine, a rotary calcining furnace, and an aluminum oxide finished product warehouse.

[0012] The mother liquor circulation unit includes an evaporation and concentration tank, a causticizing reactor, a plate and frame filter press (b), and an alkali storage tank.

[0013] Compared with the prior art, the beneficial effects of the present invention are: (1) A two-stage decarbonization process is adopted, which is suitable for coarse and fine slag mixed raw materials, and efficiently removes high content of residual carbon, avoiding carbon impurities from affecting product purity, and laying the foundation for subsequent silicon and aluminum extraction.

[0014] (2) By precisely controlling the pH, the stepwise precipitation and separation of silicon and aluminum can be achieved, which significantly improves the purity of silica and aluminum oxide products and meets industrial application standards.

[0015] (3) Construct an alkaline solution recycling system to significantly reduce reagent consumption, reduce waste liquid discharge, effectively utilize ash residue, and achieve full-scale utilization of solid waste. Attached Figure Description

[0016] Figure 1 This is a process flow diagram of the present invention; In the diagram: 1-Vibrating screen; 2-Coarse slag storage silo; 3-Fine slag storage silo; 4-Mixer; 5-Low-temperature oxidation decarbonization furnace; 6-High-temperature calcination furnace; 7-Alkali dissolution reactor; 8-Plate and frame filter press a; 9-Flocculation sedimentation tank; 10-Carbon dioxide supply system; 11-Silica reactor; 12-Centrifugal washer; 13-Spray drying tower; 14-Silica finished product storage silo; 15-Activated carbon adsorption device; 16-Alumina reactor; 17-Filter press washer; 18-Rotary calcination furnace; 19-Alumina finished product silo; 20-Evaporation and concentration tank; 21-Californification reactor; 22-Plate and frame filter press b; 23-Alkali storage tank. Detailed Implementation Example 1

[0017] The present invention will be further described in detail below with reference to specific embodiments, so that those skilled in the art can understand that the embodiments are merely preferred solutions and are not intended to limit the present invention.

[0018] A method for co-producing silica and alumina from coal gasification ash residue includes the following steps: Ash and slag decarbonization: After screening, the coarse and fine slag from coal-water slurry gasification are separated, with the undersized coarse and fine slags in a 1:1 mass ratio. Coarse slag: SiO2 45%, Al2O3 22%, residual carbon 5%; Fine slag: SiO2 40%, Al2O3 20%, residual carbon 20%. The coarse or fine slag from coal gasification is fed into a low-temperature oxidation decarbonization furnace 5, where the temperature is controlled at 350℃~450℃ and held for 2 hours to remove surface free carbon and some organic carbon. Then, the ash and slag after low-temperature decarbonization are transferred to a high-temperature roasting furnace 6, where the temperature is controlled at a stable 650℃~750℃ and held for 1.5 hours to achieve deep decarbonization, with the residual carbon content of the material ≤1.0%.

[0019] Alkali dissolution activation and impurity removal: The decarburized ash residue is transported to the alkali dissolution reactor 7, and a 25% (w / w) NaOH solution is added and stirred to react, so that SiO2 reacts with NaOH to produce sodium silicate (water glass), and Al2O3 partially reacts to produce sodium aluminate. The reaction formulas are: SiO2 + 2NaOH = Na2SiO3 + H2O, Al2O3 + 2NaOH + 3H2O = 2NaAl(OH)4. The alkali dissolution product is sent to the plate and frame filter press a8 to separate the sodium aluminosilicate mixture (filtrate) and filter cake containing impurities such as iron and calcium. 0.5% to 1.0% flocculant (polyacrylamide) is added to the filtrate, stirred for 30 minutes, and allowed to settle to remove trace suspended impurities, resulting in a refined sodium aluminosilicate solution.

[0020] Silica production: Sodium aluminosilicate solution is fed into silica reactor 11, carbon dioxide gas is introduced, pH is adjusted to 8.5~9.5, and the temperature is 60~80℃ to generate silica precursor; silicate ions are precipitated to generate silica precursor; reaction formula: Na2SiO3+CO2+H2O=H2SiO3⬇+Na2CO3, H2SiO3=SiO2·nH2O (silica), silica precursor is washed by centrifugal washing machine 12, the silica mother liquor is separated and then washed with deionized water until the conductivity is ≤50μS / cm, and sent to spray drying tower 13, inlet temperature 250~300℃, outlet temperature 100~120℃, to obtain finished silica product.

[0021] Alumina production: The silica precipitation mother liquor (NaAl(OH)4, Na2CO3) is fed into the activated carbon adsorption device 15 to remove residual organic matter and pigments. After filtration, the refined sodium aluminate solution is fed into the alumina reactor 16, where carbon dioxide is introduced to adjust the pH to 7.0~8.0. The reaction is carried out at 40~60℃ to precipitate aluminate ions and obtain aluminum hydroxide precipitate. The reaction formula is: NaAl(OH)4 + CO2 = Al(OH)3⬇ + NaHCO3. The aluminum hydroxide slurry is fed into the filter press washing machine 17 to remove the aluminum precipitation mother liquor. It is then washed with deionized water until the pH of the filtrate is 7~8. The washed aluminum hydroxide is fed into the rotary calcining furnace 18, where the temperature is controlled at 1100~1200℃ and calcined for 2~3 hours to decompose and obtain high-purity aluminum oxide.

[0022] Mother liquor circulation: The aluminum precipitation mother liquor (mainly containing NaHCO3 and Na2CO3) is transported to the evaporation and concentration tank. Lime milk (Ca(OH)2) is added to the concentrated mother liquor to carry out the causticization reaction. The reaction formula is: Na2CO3+Ca(OH)2=NaOH+CaCO3⬇. The alkali solution is returned to the alkali dissolution reactor 7 to realize the recycling of the reagents.

[0023] Based on the invention patent technology of the above method, an invention device for the corresponding method technical solution is given, and the device technology is described in detail.

[0024] A device for co-producing silica and alumina from coal gasification ash residue includes an ash residue pretreatment unit, an ash residue decarbonization unit, an alkali dissolution activation and impurity removal unit, a silica production unit, an alumina production unit, and a mother liquor circulation unit. Each unit is connected via pipelines and pumps to achieve continuous production. The specific device is as follows: The ash pretreatment unit includes a vibrating screen 1, a mixer 4, and a screw conveyor connected in sequence. The vibrating screen 1 is used to remove large impurities from the mixed ash. The qualified ash under the screen falls into the screw conveyor below, while the unqualified ash on the screen is ground and then fed back into the vibrating screen 1. The discharge end of the vibrating screen 1 is connected to the coarse slag storage bin 2 and the fine slag storage bin 3 through conveying device a. The discharge ports of the coarse slag storage bin 2 and the fine slag storage bin 3 are connected to the feed end of the mixer 4 through conveying device b and conveying device c, respectively. Both conveying device b and conveying device c are equipped with a precision weighing module. The discharge end of the mixer 4 is connected to the feed port of the low-temperature oxidation decarbonization furnace 5 of the decarbonization unit through the screw conveyor, realizing continuous conveying of ash.

[0025] The ash decarbonization unit is used to remove surface free carbon and some organic carbon from the ash, achieving deep decarbonization. The core equipment includes a low-temperature oxidation decarbonization furnace 5, a high-temperature roasting furnace 6, a hot air furnace, and a tail gas treatment device. The low-temperature oxidation decarbonization furnace 5 and the high-temperature roasting furnace 6 are connected in series to ensure thorough decarbonization. The low-temperature oxidation decarbonization furnace 5 is a horizontal drum-type decarbonization furnace, using electric heating or hot air heating. The temperature control system monitors the furnace temperature in real time, stabilizing it at 350℃~450℃. The furnace inlet is connected to a screw conveyor, and the outlet is connected to the inlet of the high-temperature roasting furnace 6 through a sealed pipe. Lifting plates are installed inside the furnace to ensure that the ash is evenly agitated and fully contacted with hot air, achieving preliminary removal of surface free carbon and some organic carbon through heating. The high-temperature roasting furnace 6 also adopts a horizontal drum structure. The furnace body uses a hot air furnace to provide high-temperature hot air. After the ash enters from the low-temperature decarburization furnace, it achieves deep decarburization through high-temperature roasting, ensuring that the residual carbon content of the ash after decarburization is ≤1.0%. A cooling section is set at the discharge end of the roasting furnace, and the temperature of the ash is reduced to below 150°C by air cooling to prevent the high-temperature ash from entering subsequent equipment and causing damage. The cooled decarburized ash is transported to the alkali dissolution activation and impurity removal unit by a sealed screw conveyor. The hot air furnace is an oil-fired or gas-fired hot air furnace, and the thermal power is designed according to the requirements of the decarburization furnace. It is connected to the hot air inlet of the low-temperature oxidation decarburization furnace 5 and the high-temperature roasting furnace 6 respectively. The hot air outlet is connected to the exhaust gas treatment device to realize the hot air recycling and reduce energy consumption. The exhaust gas treatment device consists of a cyclone dust collector, a bag filter dust collector, and an activated carbon adsorption tower. The exhaust gas (containing dust, a small amount of CO2, and organic waste gas) generated during the decarbonization process first enters the cyclone dust collector to remove most of the large dust particles; then it enters the bag filter dust collector to further remove fine dust; and finally it enters the activated carbon adsorption tower to adsorb the organic waste gas in the exhaust gas. The treated exhaust gas is discharged after meeting the national emission standards, and the collected dust can be returned to the batching and mixing machine for reuse.

[0026] The alkali dissolution activation and impurity removal unit is used to react decarburized ash with NaOH to generate sodium silicate and sodium aluminate, while removing impurities such as iron and calcium to obtain a refined sodium aluminosilicate solution. The core equipment includes an alkali dissolution reactor 7, a plate and frame filter press a8, a flocculation sedimentation tank 9, and a matching NaOH solution preparation tank. The alkali dissolution reactor 7 is a high-pressure reactor made of alkali-resistant stainless steel, equipped with a mechanical stirring device, temperature sensor, pressure sensor, and feed and discharge valves. The decarburized ash enters the alkali dissolution reactor 7 via a screw conveyor, while a pre-prepared NaOH solution is added to the NaOH solution preparation tank via a metering pump. The ash reacts with the NaOH solution, ensuring that SiO2 and NaOH fully react to generate sodium silicate, and that Al2O3 partially reacts to generate sodium aluminate. The plate and frame filter press a8 is used to separate the sodium aluminosilicate mixture (filtrate) from the filter cake containing impurities such as iron and calcium in the alkali dissolution product. After the filter cake produced by the plate and frame filter press a8 is collected, it is subjected to harmless treatment. The sodium aluminosilicate mixture produced by the filter press is transported to the flocculation settling tank 9. Polyacrylamide flocculant with a mass fraction of 0.5% to 1.0% is added to the flocculation settling tank 9 to remove trace suspended impurities. The overflow from the top of the flocculation settling tank 9 yields a refined sodium aluminosilicate solution, which is transported to the silica production unit by a transfer pump. The impurities settled at the bottom of the tank are discharged periodically.

[0027] The silica production unit is used to convert SiO2 in refined sodium aluminosilicate solution into finished silica. The core equipment includes a silica reactor 11, a carbon dioxide supply system 10, a centrifugal washer 12, a spray drying tower 13, and a finished silica storage silo 14. The silica reactor 11 is made of stainless steel and equipped with a stirring device, an online pH monitor, a temperature sensor, and a carbon dioxide inlet pipe. The refined sodium aluminosilicate solution enters the silica reactor 11 via a pump. The reaction temperature is controlled at 60-80℃ by jacket heating. The carbon dioxide supply system 10 introduces carbon dioxide gas (purity ≥99.5%) into the silica reactor 11 through the inlet pipe. The pH value of the reaction system is monitored in real time by the online pH monitor. When the pH drops to 8.5-9.5, the carbon dioxide supply is stopped, and the silica precursor is generated, ensuring sufficient precipitation of silica ions. The centrifugal washer 12 is used to separate the silica precursor from the silica precipitation mother liquor. The reacted materials (fumed silica precursor + silica precipitation mother liquor) enter centrifugal washer 12, where solid-liquid separation is achieved through centrifugal force. The silica precipitation mother liquor (containing NaAl(OH)4 and Na2CO3) is transported to the alumina production unit via pipeline. The fumed silica precursor remains in the centrifuge and is washed with deionized water through a spray device. The conductivity of the washing liquid is monitored in real time during the washing process until it reaches ≤50μS / cm, at which point the washing is complete. The spray drying tower 13 is a co-flow spray drying tower made of stainless steel, with the inlet temperature controlled at 250~300℃ and the outlet temperature controlled at 100~120℃. A centrifugal atomizer is used. The washed silica precursor is fed into an atomizer via a transfer pump. After being atomized into fine droplets, it enters a drying tower and comes into full contact with high-temperature hot air, instantly drying into finished silica. A discharge port is set at the bottom of the drying tower, which is connected to the finished silica storage bin 14. The exhaust gas at the top is treated by a bag filter before being discharged. The recovered fine silica particles are returned to the drying tower for re-drying.

[0028] The alumina production unit is used to convert Al2O3 in silica precipitation mother liquor into high-purity alumina. The core equipment includes an activated carbon adsorption unit 15, an alumina reactor 16, a filter press and washing machine 17, a rotary calcining furnace 18, and an alumina finished product silo 19. The activated carbon adsorption unit 15 is a fixed-bed adsorption tower filled with granular activated carbon. The silica precipitation mother liquor flows from top to bottom through the adsorption tower via a pump. The activated carbon adsorbs residual organic matter and pigments in the mother liquor. The purified sodium aluminate solution, after impurity removal, flows out from the bottom of the adsorption tower and enters the alumina reactor 16. The alumina reactor 16 is a stainless steel reactor equipped with a stirring device, an online pH monitor, a temperature sensor, and a carbon dioxide inlet pipe. After the purified sodium aluminate solution enters the reactor, the reaction temperature is controlled at 40~60℃ through jacket cooling. The carbon dioxide supply system 10 introduces carbon dioxide into the reactor to adjust the pH to 7.0~8.0, generating aluminum hydroxide precipitate and ensuring sufficient precipitation of aluminate ions. The filter press and washing machine 17 is used to separate aluminum hydroxide precipitate from aluminum precipitation mother liquor. The reacted material enters the filter press and washing machine 17. The aluminum precipitation mother liquor (mainly containing NaHCO3 and Na2CO3) is transported to the mother liquor circulation unit through pipelines. The aluminum hydroxide slurry remains on the filter plate and is washed with deionized water through a spray device. The pH value of the washing filtrate is monitored in real time until pH=7~8, completing the washing process and obtaining a pure aluminum hydroxide filter cake. The rotary calcining furnace 18 is a horizontal rotary calcining furnace. The furnace body is heated electrically or by gas. The temperature control system stably controls the furnace temperature at 1100~1200℃. The aluminum hydroxide filter cake enters the calcining furnace via a screw conveyor and is calcined inside the furnace to fully decompose and generate high-purity aluminum oxide. A cooler is installed at the discharge end of the calcining furnace, using water cooling to reduce the temperature of the aluminum oxide to below 100℃ to avoid high-temperature oxidation. The cooled aluminum oxide product is sent to the aluminum oxide finished product silo 19.

[0029] The mother liquor recycling unit is used to recycle and reuse the aluminum precipitation mother liquor. It converts NaHCO3 and Na2CO3 in the mother liquor into NaOH, which is then returned to the alkali dissolution reactor 7, reducing reagent consumption. The core equipment includes an evaporation and concentration tank, a causticizing reactor 21, a plate and frame filter press b22, and an alkali storage tank 23. The evaporation and concentration tank is a multi-effect evaporation and concentration tank, utilizing industrial waste heat or steam heating to evaporate and concentrate the aluminum precipitation mother liquor (containing NaHCO3 and Na2CO3), removing excess water and increasing the mother liquor concentration to 30%-40% (mass concentration). The distilled water generated during the concentration process is collected and used as deionized water, achieving water resource recycling. The causticizing reactor 21 is a stainless steel reactor. The concentrated mother liquor enters the causticizing reactor 21, where lime milk (Ca(OH)2) is added. The lime milk reacts with the mother liquor to generate Na(OH)2 and CaCO3 precipitates. The plate and frame filter press b22 is used to separate the NaOH alkaline solution and CaCO3 filter cake from the causticizing reaction products. The NaOH alkaline solution enters the alkaline solution storage tank 23. The NaOH alkaline solution in the alkaline solution storage tank 23 is then returned to the alkaline dissolution reactor 7 by a metering pump, realizing the recycling of reagents and reducing production costs.

[0030] A device for co-producing silica and alumina from coal gasification ash residue also includes a control system. The control system adopts a PLC automatic control system and is equipped with a touch screen operation interface. It can monitor parameters such as temperature, pressure, pH value, and flow rate of each device in real time, realize the linkage control, parameter adjustment and fault alarm of each unit equipment, and ensure the continuous and stable operation of the device.

[0031] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for co-producing silica and alumina from coal gasification ash residue, characterized in that: Includes the following steps: Ash and slag decarbonization: Coal gasification coarse slag and / or fine slag are fed into a low-temperature oxidation decarbonization furnace, kept at a certain temperature for a period of time, and then transferred to a high-temperature roasting furnace to achieve deep decarbonization. The residual carbon content of the material is ≤1.0%. Alkali dissolution activation and impurity removal: The decarburized ash residue is transported to the alkali dissolution reactor, NaOH solution is added and stirred to react, and the reaction product is separated by a plate and frame filter press. The filter cake contains iron and calcium impurities, and the filtrate is a mixture of sodium aluminosilicate. Silica production: Sodium aluminosilicate mixture is transported to silica reactor, carbon dioxide gas is introduced to generate silica precursor; silica precursor is washed by centrifugal washer until conductivity is ≤50μS / cm, and then sent to spray drying tower to obtain finished silica. Aluminum oxide production: Activated carbon is added to the silica mother liquor for adsorption and purification. After filtration, the liquor is sent to an aluminum oxide reactor and carbon dioxide is introduced to react, resulting in aluminum hydroxide precipitate. After washing, the precipitate is calcined in a rotary kiln to obtain aluminum oxide. Mother liquor recycling: The mother liquor after aluminum precipitation is transported to the evaporation and concentration tank. Lime milk (Ca(OH)2) is added to the concentrated mother liquor to carry out the causticization reaction. The NaOH alkaline solution produced by the reaction is returned to the alkaline dissolution reactor to realize the recycling of the reagent.

2. The method for co-producing silica and alumina from coal gasification ash and slag according to claim 1, characterized in that: The temperature of the low-temperature oxidation decarburization furnace is controlled at 350℃~450℃, and the temperature of the high-temperature roasting furnace is controlled at 650℃~750℃.

3. The method for co-producing silica and alumina from coal gasification ash residue according to claim 1, characterized in that: The NaOH solution has a mass concentration of 20% to 30% and an alkali dissolution temperature of 90℃ to 110℃.

4. The method for co-producing silica and alumina from coal gasification ash residue according to claim 1, characterized in that: In the production process of silica, carbon dioxide gas is introduced to adjust the pH to 8.5~9.5, and the reaction is carried out at a temperature of 60℃~80℃.

5. The method for co-producing silica and alumina from coal gasification ash residue according to claim 1, characterized in that: The spray drying tower has an inlet temperature of 250℃~300℃ and an outlet temperature of 100℃~120℃.

6. The method for co-producing silica and alumina from coal gasification ash residue according to claim 1, characterized in that: In the production of aluminum oxide, carbon dioxide is introduced to adjust the pH to 7.0~8.0, the reaction temperature is 40℃~60℃, and the calcination temperature in the rotary kiln is 1100℃~1200℃.

7. An apparatus for co-producing silica and alumina from coal gasification ash residue, and a method for realizing the co-production of silica and alumina from coal gasification ash residue, characterized in that: The system includes a slag pretreatment unit, a slag decarbonization unit, an alkali dissolution activation and impurity removal unit, a silica production unit, an alumina production unit, and a mother liquor circulation unit. These units are connected via pipelines and pumps to achieve continuous production. The slag pretreatment unit comprises a vibrating screen, a mixer, and a screw conveyor connected in sequence. The slag decarbonization unit includes a low-temperature oxidation decarbonization furnace, a high-temperature calcining furnace, a hot blast furnace, and a tail gas treatment device. The alkali dissolution activation and impurity removal unit includes an alkali dissolution reactor, a plate and frame filter press (a), a flocculation sedimentation tank, and a matching NaOH solution preparation tank. The silica production unit includes a silica reactor, a carbon dioxide supply system, a centrifugal washer, a spray drying tower, and a silica finished product storage silo. The alumina production unit includes an activated carbon adsorption device, an alumina reactor, a filter press washer, a rotary calcining furnace, and an alumina finished product silo. The mother liquor circulation unit includes an evaporation and concentration tank, a causticizing reactor, a plate and frame filter press (b), and an alkali solution storage tank.

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