Fly ash full-amount resource utilization method and system for realizing valuable metal extraction

Abstract

The invention discloses a coal ash full-amount resource utilization method and a coal ash full-amount resource utilization system for realizing valuable metal extraction. The method comprises the following steps: S1, adding high-alumina coal ash, carbide slag and a composite fluxing agent into a grinding machine, grinding, mixing and screening to obtain a raw material; s2, adding the raw material and water into a press, feeding an obtained formed blank into a roller kiln, carrying out high-temperature calcination, and crushing into fine-particle clinker by a crusher; s3, the fine particle clinker and a sodium carbonate solution are added into a leaching reactor, and an obtained leaching mixed material is fed into a first solid-liquid separation device to be separated into aluminum-rich leaching liquid and aluminum extraction residues; s4, the aluminum-rich leachate and calcium oxide are added into a desilication reactor, and obtained mixed material liquid is fed into a second solid-liquid separation device to be separated into desilication aluminum-rich leachate and aluminum extraction residues; and S5, adding the desiliconized aluminum-rich lixivium and carbon dioxide into a carbon component reactor, and feeding an obtained carbon component mixed material into a third solid-liquid separation device to be separated into aluminum hydroxide and waste liquid. The method can be used for extracting Al (OH) 3 from high-alumina fly ash, and has the advantages of low energy consumption and high purity.

Description

Technical Field

[0001] This invention relates to the field of comprehensive fly ash treatment technology, specifically a method and system for the full resource utilization of fly ash to achieve the extraction of valuable metals. Background Technology

[0002] my country produces over 30 million tons of high-alumina fly ash annually, with an alumina content ranging from 10% to 50%, making it an important potential resource to replace traditional bauxite. However, the current utilization of high-alumina fly ash resources faces significant bottlenecks:

[0003] First, the traditional alkaline aluminum extraction process requires high-temperature calcination at 1200-1400℃, resulting in high energy consumption. Furthermore, the parameters for processes such as ball milling and leaching are poorly compatible, leading to low aluminum extraction efficiency. Additionally, the purity of the extracted Al(OH)3 is relatively low.

[0004] Second, the leachate contains a large amount of sodium salts, lacks efficient regeneration methods, and is directly discharged, polluting the environment.

[0005] Third, the aluminum extraction process generates a large amount of aluminum extraction residue. Among them, the silicon-calcium residue is highly alkaline, and its reuse requires an additional dealkali treatment process before it can be used in building materials, which increases the process cost. If it is directly stored without dealkali treatment, it will easily cause soil salinization.

[0006] To address the above issues, there is an urgent need to develop an integrated technology and system that is low in energy consumption and utilizes all components. Summary of the Invention

[0007] One of the technical problems to be solved by this invention is to provide a method for the full resource utilization of fly ash for the extraction of valuable metals, so as to solve the problems of high energy consumption and low purity in the existing technology for extracting Al(OH)3 from high-alumina fly ash.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0009] A method for the full resource utilization of fly ash to achieve the extraction of valuable metals includes:

[0010] Step S1: Add high-alumina fly ash, carbide slag and composite flux to the mill, grind and mix evenly, and then screen out the raw material with a particle size below the preset particle size threshold.

[0011] The mill is preferably a vibratory mill. High-alumina fly ash, carbide slag and composite flux are repeatedly impacted and mixed in the vibratory mill to increase the specific surface area of ​​the material, refine the particle size, achieve uniform mixing and destroy the surface grains of the mullite phase; thus realizing mechanical activation and enhancing the reaction effect in subsequent steps.

[0012] The raw material is preferably screened by a vibrating screen, and coarse material with a particle size larger than a preset particle size threshold is returned to the mill for re-grinding and mixing.

[0013] Step S2: Add the raw material and water to the press and press to form a mold. The resulting molded blank is sent to the roller kiln for high-temperature calcination and then crushed into fine clinker by the crusher.

[0014] The press enables loose raw material particles to form a stable agglomerate structure, providing a structural basis for subsequent calcination, and facilitating transportation and saving space.

[0015] During the high-temperature calcination process in the roller kiln, the Ca(OH)2 contained in the carbide slag is converted into CaO. The CaO then reacts with the corundum in the high-alumina fly ash to generate Ca2+. 12 Al 14 O 33 In high-alumina fly ash, the mullite crystalline phase reacts with CaO to form Ca2Al2SiO7 and Ca... 12 Al 14 O 33 Ca2Al2SiO7 will continue to react with CaO to produce Ca 12 Al 14 O 33 The composite flux, along with Ca2SiO4, disrupts the stable structure of mullite, thereby separating the silicon and aluminum components in high-alumina fly ash. In this process, the composite flux, on the one hand, facilitates the formation of a eutectic system, significantly lowering the critical temperature for liquid phase formation; on the other hand, it integrates into the original crystal lattice, reducing the activation energy of phase transformation, breaking the stable state of the original crystal phase, and promoting phase transformation.

[0016] In this process, the large clinker obtained from high-temperature calcination is crushed into fine clinker particles in the crusher through mechanical forces such as extrusion and impact, thereby achieving pre-homogenization of particle size and increase of specific surface area. At the same time, microcracks and defects are formed on the surface of the fine clinker particles, which further enhances the reactivity of the material and provides an advantage for subsequent leaching.

[0017] Step S3: The fine-particle clinker and sodium carbonate solution (Na2CO3) are added to the leaching reactor for leaching reaction. The resulting leaching mixture is sent to the first solid-liquid separation device to separate it into a liquid phase of aluminum-rich leachate and a solid phase of aluminum extraction residue.

[0018] In the process of leaching the fine-particle clinker in Na2CO3 solution, the aluminum-containing component reacts with Na2CO3 to generate soluble NaAlO2, which dissolves in the solution to become an aluminum-rich leachate, thereby achieving the phase transformation and enrichment of aluminum elements; while the calcium-containing component precipitates as CaCO3 in solid form, and is then separated into aluminum-extracting residue by the first solid-liquid separation device.

[0019] Step S4: Add the aluminum-rich leaching solution and calcium oxide (CaO) to the desilication reactor to carry out the desilication reaction. The resulting mixture is sent to the second solid-liquid separation device to separate it into liquid phase desilication aluminum-rich leaching solution and solid phase aluminum extraction residue.

[0020] In the desilication reaction, CaO reacts with Na2SiO3 in the aluminum-rich leaching solution to generate insoluble CaSiO3, which is then separated into desilication-rich aluminum leaching solution and aluminum extraction residue by a second solid-liquid separation device, so as to remove soluble silicon from the aluminum-rich leaching solution and improve the purity of Al(OH)3.

[0021] Step S5: Add the desilication-rich aluminum leaching solution and carbon dioxide (CO2) to the carbon reactor for reaction. The resulting carbon mixture is sent to the third solid-liquid separation device to be separated into solid aluminum hydroxide (Al(OH)3) and liquid waste liquid.

[0022] In the carbonation reactor, CO2 is introduced into the desilication-rich aluminum solution for carbonation treatment. The pH of the desilication-rich aluminum solution gradually decreases, causing AlO2- to hydrolyze into Al(OH)3 crystals. The Al(OH)3 crystals then precipitate and are recovered by a third solid-liquid separation device. Meanwhile, impurities such as sodium silicate in the desilication-rich aluminum solution remain in the liquid phase and become waste liquid. This achieves efficient separation of aluminum and silicon impurities, improving the purity of Al(OH)3. Simultaneously, it achieves the capture and utilization of CO2, resulting in significant economic and environmental benefits.

[0023] Therefore, through steps S1 to S5, the present invention can extract Al(OH)3 from high-alumina fly ash, which has the advantages of low energy consumption and high purity, as detailed below:

[0024] Low energy consumption: Through the synergistic effect of the following steps, the calcination temperature of the formed billet in the roller kiln in step S2 can be reduced from 1400℃ in the traditional alkaline aluminization process to 900℃, reducing energy consumption by 15%-25% and effectively lowering production costs. The synergistic steps are as follows: Step S1 involves grinding and mixing high-alumina fly ash, carbide slag, and composite flux in a mill to achieve mechanical activation, enhancing the reaction effect in subsequent steps; during the high-temperature calcination in step S2, the composite flux lowers the sintering temperature by breaking stable Si-O-Si and Al-O-Si bonds in the raw materials, inducing the formation of soluble calcium aluminate and insoluble dicalcium silicate, promoting phase transformation, and achieving efficient separation of silicon and aluminum; furthermore, when CaF2 is used in the composite flux, F- can replace lattice oxygen to form (CaO). 11 (Al2O3)7(CaF2) further lowers the reaction energy barrier.

[0025] High purity: On the one hand, step S4 removes soluble silicon from the aluminum-rich leaching solution by reacting calcium oxide with Na2SiO3 in the aluminum-rich leaching solution to generate insoluble CaSiO3, thereby improving the purity of Al(OH)3 extracted from the desiliconized aluminum-rich leaching solution in step S5. On the other hand, step S5 introduces CO2 into the desiliconized aluminum-rich solution for carbonation treatment, which promotes the hydrolysis of AlO2- in the desiliconized aluminum-rich solution into Al(OH)3 crystals, while impurities such as sodium silicate in the desiliconized aluminum-rich solution remain in the liquid phase and become waste liquid, thus achieving efficient separation of impurities such as silicon from aluminum and improving the purity of Al(OH)3.

[0026] Furthermore, the reaction process in step S5 simultaneously achieves the capture and utilization of CO2, resulting in significant economic and environmental benefits.

[0027] Preferably, the method for the full resource utilization of fly ash further includes:

[0028] Step S6: The aluminum hydroxide (Al(OH)3) is fed into a calcining furnace and decomposed at high temperature to generate aluminum oxide (Al2O3).

[0029] Al(OH)3 undergoes a multi-stage phase transformation process under high temperature conditions, successively undergoing physical dehydration, chemical dehydration, lattice reconstruction, and crystal form optimization to generate Al2O3.

[0030] Steps S1 to S5 are implemented using the following parameters:

[0031] In step S1, the mass ratio of high-alumina fly ash, carbide slag and composite flux is (10-20):(20-35):1, and the composite flux contains two or three of CaF2, Na2CO3, CaCl2, NaF and NaSO4.

[0032] In the pressing and molding process of step S2, the mass ratio of raw material to water is 100:(10-5);

[0033] During the high-temperature calcination process in step S2, the calcination temperature is 900-1050℃, and the heat preservation time after calcination is 1-3 hours.

[0034] In the leaching reaction of step S3, the concentration of sodium carbonate solution is 35-60 g / L, and the solid-liquid ratio of fine clinker to sodium carbonate solution is 10:(1-2.5).

[0035] During the desilication reaction in step S4, 4-9g of calcium oxide is added to every 1L of aluminum-rich leaching solution.

[0036] In the reaction process of step S5, the rate of carbon dioxide introduction is 0.5-4 m / s. 3 / h, reaction time is 10-60min.

[0037] Preferably, steps S1 to S5 employ the following preferred parameters:

[0038] In step S1, the mill rotates at 400-600 rpm for 30-60 minutes, and the preset particle size threshold for the sieved raw material is 2 mm. Under these conditions, the grinding force is sufficient, which can balance the activation effect and production efficiency.

[0039] In the pressing and molding process of step S2, the hydraulic pressure of the press is 30-50MPa, and the molded blank is a disc-shaped blank with a diameter of 5-10cm and a thickness of 1-2cm. This makes the size of the disc-shaped blank appropriate, so that it can be heated evenly during high-temperature calcination, and avoids the large porosity of the molded blank due to insufficient pressure during pressing and molding, which would cause it to easily turn into powder during high-temperature calcination.

[0040] During the high-temperature calcination process in step S2, the heating rate is 5-9℃ / min.

[0041] During the crushing process in step S2, the crushing time is 10-40 minutes, and the particle size of the fine clinker is ≤1mm. This results in small and uniform particle size of the fine clinker, which helps to ensure complete reaction during leaching and improves the yield.

[0042] In the leaching reaction process of step S3, the reaction temperature is 60-90℃, the stirring rate is 400-500rpm, and the reaction time is 1.5-4h. Thus, the reaction temperature promotes the occurrence rate of the leaching reaction, stirring ensures the suspension of materials and avoids material sedimentation and agglomeration leading to incomplete leaching, and the reaction time ensures the completeness of the leaching process.

[0043] In the desilication reaction process of step S4, the reaction temperature is 60-90℃, the stirring rate is 400-500rpm, and the reaction time is 1-2.5h.

[0044] During the reaction process in step S5, the reaction temperature is 60-90℃.

[0045] As a preferred embodiment of the present invention: the carbon reactor in step S5 is a three-phase fluidized bed.

[0046] Therefore, compared with existing technologies that use stirred tanks or reactors as carbon separation reactors, this invention uses a three-phase fluidized bed. Carbon dioxide gas is introduced from the bottom inlet of the three-phase fluidized bed and aerated upwards, while the desilication-rich aluminum leaching solution flows downwards due to gravity after entering the three-phase fluidized bed. Thus, carbon dioxide gas and desilication-rich aluminum leaching solution undergo countercurrent mass transfer within the three-phase fluidized bed, ensuring a large contact area and high mass transfer efficiency between the gas and liquid phases. This significantly improves the reaction rate of carbon dioxide and desilication-rich aluminum leaching solution, resulting in higher efficiency and better effect in the carbon separation process.

[0047] As a preferred embodiment of the present invention, the method for full resource utilization of fly ash further includes:

[0048] Step S7: Add the waste liquid and NaOH from step S5 to the waste liquid regeneration reactor for reaction, and add the resulting recycled alkaline solution back to the leaching reactor from step S3 for leaching reaction.

[0049] Therefore, since the waste liquid in step S5 contains NaHCO3 generated by carbonation of the sodium carbonate solution (Na2CO3) in step S3 by introducing carbon dioxide (CO2) in step S5, the pH is reduced; while in the waste liquid regeneration reactor, NaOH is added to the waste liquid, which increases the pH, and NaOH reacts with NaHCO3 to generate sodium carbonate solution (Na2CO3), which can be used for leaching reaction in step S3, thereby achieving recycling.

[0050] In step S7, the pH of the recycled alkaline solution is 11-12.

[0051] Preferred method: By controlling the concentration of NaOH to 6-15 g / L, the pH of the recycled alkaline solution is precisely adjusted to 11-12.

[0052] As a preferred embodiment of the present invention, the method for full resource utilization of fly ash further includes:

[0053] Step S8: Add the aluminum extraction residue, acidic coal gangue and water from steps S3 and S4 to a wet ball mill for ball milling and mixing. After drying and screening, the mixed fine material with a particle size below the second preset particle size threshold is screened out and sent to a storage tank for temporary storage.

[0054] In the wet ball mill, the impact and crushing of steel balls combined with the lubrication and dispersion of water can refine the particle size of aluminum extraction residue and acidic coal gangue, increase the specific surface area of ​​the materials, and make the composition and particle size of the mixture uniform, thus avoiding problems such as alkali return and cracking of calcium silicate plates. At the same time, the alkaline components of aluminum extraction residue and the acidic components of acidic coal gangue come into full contact and undergo a neutralization reaction, stabilizing the pH of the mixture within the neutral range.

[0055] The mixture is preferably dried by a dryer and screened by a vibrating screen. Coarse material with a particle size larger than a second preset particle size threshold is returned to a wet ball mill for regrinding.

[0056] Step S9: The mixed fine materials, water, basalt fiber, and waterproofing agent are fed into a mixer and mixed. The resulting paste slurry is pressed into standard slabs by a hydraulic press.

[0057] The mixture of fine materials, water, basalt fiber, and waterproofing agent is homogenized through stirring, and the resulting paste-like slurry is suitable for subsequent pressing. The waterproofing agent is used to improve waterproofing and durability, and the basalt fiber is used to enhance the bending and impact resistance of the calcium silicate board.

[0058] Step S10: Place the standard slab in an autoclave for high-temperature and high-pressure curing, and after curing, cool it to room temperature for demolding. Then, after cutting and polishing, obtain the finished calcium silicate board.

[0059] The standard slab undergoes a silicon-calcium hydration reaction during high-temperature and high-pressure curing to generate high-strength mineral tobermorite, enabling the finished calcium silicate board to meet the requirements for calcium silicate boards used in construction.

[0060] Therefore, through steps S8 to S10, the present invention can prepare the aluminum extraction residue generated in steps S3 and S4 into a finished calcium silicate board that meets the requirements for calcium silicate boards used in construction. This can replace the existing technology of using limestone and quartz sand obtained through mining as raw materials for calcium silicate boards, effectively reducing the exploitation of natural resources and alleviating ecological problems from the source. It solves the following existing problems: In the existing technology, the production of traditional building materials such as calcium silicate boards requires a large amount of natural limestone and quartz sand as the main calcium and silicon sources. Both of these need to be obtained through mining, which can easily cause ecological damage problems such as vegetation destruction, soil erosion, and geological subsidence.

[0061] Furthermore, during the mixing process in step S9, the alkalinity of the aluminum extraction residue and the acidity of the coal gangue are neutralized, which can replace the dealkali removal process for aluminum extraction residue from fly ash in the prior art. At the same time, it achieves effective disposal of the two industrial solid wastes, aluminum extraction residue and coal gangue, avoids the environmental hazards caused by solid waste accumulation, and achieves the effects of "treating waste with waste" and "co-processing solid waste".

[0062] Steps S8 to S10 are implemented using the following parameters:

[0063] During the ball milling mixing process in step S8, the mass ratio of aluminum extraction residue to acidic coal gangue is (1.5-2.5):1;

[0064] In step S8, the second preset particle size threshold is 100 μm;

[0065] In step S8, the pH of the mixed fine materials is 7-8, and the silicon-to-calcium ratio is 0.8-1.2.

[0066] In step S9, the mass ratio of the mixed fine materials, water, basalt fiber, and waterproofing agent is 100:(20-30):5:2;

[0067] During the high-temperature and high-pressure curing process in step S10, the constant temperature is 180-200℃ and the pressure is 0.8-1.1MPa.

[0068] Preferably, steps S8 to S10 employ the following preferred parameters:

[0069] During the ball milling and mixing process in step S8, the pH of the aluminum extraction residue is 8-11, and the pH of the acidic coal gangue is 2-4.

[0070] In the ball milling process of step S8, the mass ratio of solid material to water is 100:20 to ensure the fluidity of the material during ball milling, avoid high drying energy consumption due to excessive water or uneven material mixing due to insufficient water, and ensure that the particle size of the mixed fine material is ≤100μm.

[0071] During the drying process in step S8, the temperature is 200-350℃, and the product is dried to a moisture content of 1-3%.

[0072] During the pressing process in step S9, the standard slab size is 1220×2440×12mm, which conforms to the JC / T564.1-2018 industry standard, eliminating the need for secondary cutting and adapting to various application scenarios.

[0073] During the pressing process in step S9, the pressing pressure is 20MPa, the holding pressure is 60s, and the demolding speed is 5mm / s.

[0074] During the high-temperature and high-pressure curing process in step S10, the constant temperature stage lasts for 8-12 hours.

[0075] During the high-temperature and high-pressure curing process in step S10, the heating time is 1-2 hours and the cooling time is 4-6 hours to avoid thermal shock causing cracking of the slab and to control the flatness of the slab.

[0076] The second technical problem to be solved by this invention is to provide a system for the full resource utilization of fly ash that enables the extraction of valuable metals.

[0077] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0078] A system for the full-scale resource utilization of fly ash for the extraction of valuable metals is characterized by comprising: a high-alumina fly ash aluminum extraction module and a waste liquid regeneration module.

[0079] The high-alumina fly ash aluminum extraction module includes:

[0080] A mill is used to grind and mix high-alumina fly ash, carbide slag and composite flux evenly.

[0081] A vibrating screen, whose feed inlet is connected to the discharge outlet of the mill via a sealed pipeline, is used to screen out raw materials with a particle size below a preset particle size threshold.

[0082] A press, whose feed inlet is connected to the discharge outlet of the vibrating screen, is used to press the raw material and water into a molded blank.

[0083] The roller kiln has its feed end connected to the discharge port of the press via a high-temperature resistant conveyor belt, and is used to calcine the formed billet at high temperature.

[0084] The crusher, whose feed inlet is connected to the discharge end of the roller kiln, is used to crush the calcined billet into fine clinker.

[0085] The leaching reactor, whose inlet is connected to the outlet of the crusher, is used for leaching the fine clinker and sodium carbonate solution (Na2CO3) to obtain a leaching mixture.

[0086] The first solid-liquid separation device has its inlet connected to the outlet of the leaching reactor and is used to separate the leaching mixture into a liquid phase of aluminum-rich leaching solution and a solid phase of aluminum extraction residue.

[0087] The desilication reactor has its inlet connected to the liquid phase outlet of the first solid-liquid separation device, and is used for the desilication reaction of the aluminum-rich leaching solution and calcium oxide (CaO) to obtain a mixed liquid.

[0088] The second solid-liquid separation device has its inlet connected to the outlet of the desilication reactor and is used to separate the mixed liquid into a liquid phase of desilication-rich aluminum leaching solution and a solid phase of aluminum extraction residue.

[0089] The carbon reactor has its inlet connected to the liquid phase outlet of the second solid-liquid separation device and its inlet connected to a carbon dioxide gas source pipeline. It is used to react the desilication-rich aluminum leaching solution with carbon dioxide (CO2) to obtain a carbon mixture.

[0090] The third solid-liquid separation device has its inlet connected to the outlet of the carbon reactor and is used to separate the carbon mixture into solid aluminum hydroxide (Al(OH)3) and liquid waste liquid.

[0091] The calcining furnace has its feed inlet connected to the solid phase outlet of the third solid-liquid separation device, and is used to decompose the aluminum hydroxide (Al(OH)3) at high temperature to generate aluminum oxide (Al2O3).

[0092] The waste liquid regeneration module includes:

[0093] The waste liquid regeneration reactor has its inlet connected to the liquid phase outlet of the third solid-liquid separation device, and its outlet connected to the inlet of the leaching reactor via a pipeline. It is used to react the waste liquid with NaOH, and the resulting recycled alkaline solution is added back to the leaching reactor for leaching reaction.

[0094] Therefore, the fly ash full resource utilization system of the present invention can realize the above steps S1 to S7.

[0095] Preferably, the fly ash full-resource utilization system also includes a module for producing calcium silicate boards from the residue;

[0096] The residue-based calcium silicate board module includes:

[0097] A wet ball mill, whose feed inlet is connected to the solid phase outlet of the first solid-liquid separation device and the solid phase outlet of the second solid-liquid separation device, is used to ball mill and mix the aluminum extraction residue, acidic coal gangue and water to obtain a mixture.

[0098] A dryer, the feed inlet of which is connected to the discharge outlet of the wet ball mill, is used to dry the mixture.

[0099] A vibrating screen, whose inlet is connected to the outlet of the dryer, is used to screen out fine mixed materials with a particle size below a second preset particle size threshold from the dried mixture.

[0100] The agitator, whose inlet is connected to the outlet of the vibrating screen via a storage tank, is used to mix the fine mixed materials, water, basalt fiber, and waterproofing agent to obtain a paste-like slurry.

[0101] A hydraulic press, the inlet of which is connected to the outlet of the agitator, is used to press the paste slurry into standard slabs;

[0102] An autoclave, whose inlet is connected to the outlet of the hydraulic press via a conveyor belt, is used to cure the standard slab at high temperature and high pressure. After curing, the slab is cooled to room temperature for demolding, and then cut and polished to obtain the finished calcium silicate board.

[0103] Therefore, the fly ash full resource utilization system of the present invention can realize the above-mentioned steps S8 to S10.

[0104] Compared with the prior art, the present invention has the following beneficial effects:

[0105] First, the present invention, through steps S1 to S5, can extract Al(OH)3 from high-alumina fly ash, and has the advantages of low energy consumption and high purity, as detailed below:

[0106] Low energy consumption: Through the synergistic effect of the following steps, the calcination temperature of the formed billet in the roller kiln in step S2 can be reduced from 1400℃ in the traditional alkaline aluminization process to 900℃, reducing energy consumption by 15%-25% and effectively lowering production costs. The synergistic steps are as follows: Step S1 involves grinding and mixing high-alumina fly ash, carbide slag, and composite flux in a mill to achieve mechanical activation, enhancing the reaction effect in subsequent steps; during the high-temperature calcination in step S2, the composite flux lowers the sintering temperature by breaking stable Si-O-Si and Al-O-Si bonds in the raw materials, inducing the formation of soluble calcium aluminate and insoluble dicalcium silicate, promoting phase transformation, and achieving efficient separation of silicon and aluminum; furthermore, when CaF2 is used in the composite flux, F- can replace lattice oxygen to form (CaO). 11 (Al2O3)7(CaF2) further lowers the reaction energy barrier.

[0107] High purity: On the one hand, step S4 removes soluble silicon from the aluminum-rich leaching solution by reacting calcium oxide with Na2SiO3 in the aluminum-rich leaching solution to generate insoluble CaSiO3, thereby improving the purity of Al(OH)3 extracted from the desiliconized aluminum-rich leaching solution in step S5. On the other hand, step S5 introduces CO2 into the desiliconized aluminum-rich solution for carbonation treatment, which promotes the hydrolysis of AlO2- in the desiliconized aluminum-rich solution into Al(OH)3 crystals, while impurities such as sodium silicate in the desiliconized aluminum-rich solution remain in the liquid phase and become waste liquid, thus achieving efficient separation of impurities such as silicon from aluminum and improving the purity of Al(OH)3.

[0108] Furthermore, the reaction process in step S5 simultaneously achieves the capture and utilization of CO2, resulting in significant economic and environmental benefits.

[0109] Secondly, the present invention uses a three-phase fluidized bed as the carbon separation reactor in step S5. Compared with the prior art which uses a stirred tank or a reaction vessel as the carbon separation reactor, it enables the carbon dioxide gas and the desilication alumina-rich leaching solution to flow in a countercurrent mass transfer manner in the three-phase fluidized bed, ensuring a large contact area and high mass transfer efficiency between the gas and liquid phases. This significantly improves the reaction rate of carbon dioxide and the desilication alumina-rich leaching solution, resulting in higher efficiency and better effect of the carbon separation process.

[0110] Third, in step S7, the present invention allows NaHCO3 in the waste liquid to react with NaOH to generate sodium carbonate solution (Na2CO3), which can be used for leaching reaction in step S3, thereby achieving recycling.

[0111] Fourth, through steps S8 to S10, the present invention can prepare the aluminum extraction residue generated in steps S3 and S4 into finished calcium silicate boards that meet the requirements of calcium silicate boards for building construction. This can replace the existing technology of using limestone and quartz sand obtained through mining as raw materials for calcium silicate boards, effectively reducing the mining of natural resources and alleviating ecological problems from the source.

[0112] Furthermore, during the mixing process in step S9, the alkalinity of the aluminum extraction residue and the acidity of the coal gangue are neutralized, which can replace the dealkali removal process for aluminum extraction residue from fly ash in the prior art. At the same time, it achieves effective disposal of the two industrial solid wastes, aluminum extraction residue and coal gangue, avoids the environmental hazards caused by solid waste accumulation, and achieves the effects of "treating waste with waste" and "co-processing solid waste".

[0113] In summary, this invention achieves the full recovery and utilization of Al, Si / Ca elements in high-alumina fly ash throughout the entire process, with a resource utilization rate of no less than 95%, producing high-value-added Al(OH)3 products and medium-value calcium silicate boards. Attached Figure Description

[0114] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments:

[0115] Figure 1 This is a flowchart of the present invention;

[0116] Figure 2 This is a schematic diagram of the three-phase fluidized bed used in the carbon reactor described in step S5 of the present invention. Detailed Implementation

[0117] The present invention will now be described in detail with reference to the embodiments and accompanying drawings to help those skilled in the art better understand the inventive concept of the present invention. However, the scope of protection of the claims of the present invention is not limited to the following embodiments. For those skilled in the art, all other embodiments obtained without creative effort without departing from the inventive concept of the present invention are within the scope of protection of the present invention.

[0118] Example 1

[0119] like Figure 1 As shown, this invention discloses a method for the full resource utilization of fly ash to achieve the extraction of valuable metals, comprising:

[0120] Step S1: Add high-alumina fly ash, carbide slag and composite flux to the mill, grind and mix evenly, and then screen out the raw material with a particle size below the preset particle size threshold.

[0121] The mill is preferably a vibratory mill. High-alumina fly ash, carbide slag and composite flux are repeatedly impacted and mixed in the vibratory mill to increase the specific surface area of ​​the material, refine the particle size, achieve uniform mixing and destroy the surface grains of the mullite phase; thus realizing mechanical activation and enhancing the reaction effect in subsequent steps.

[0122] The raw material is preferably screened by a vibrating screen, and coarse material with a particle size larger than a preset particle size threshold is returned to the mill for re-grinding and mixing.

[0123] Step S2: Add the raw material and water to the press and press to form a mold. The resulting molded blank is sent to the roller kiln for high-temperature calcination and then crushed into fine clinker by the crusher.

[0124] The press enables loose raw material particles to form a stable agglomerate structure, providing a structural basis for subsequent calcination, and facilitating transportation and saving space.

[0125] During the high-temperature calcination process in the roller kiln, the Ca(OH)2 contained in the carbide slag is converted into CaO. The CaO then reacts with the corundum in the high-alumina fly ash to generate Ca2+. 12 Al 14 O 33 In high-alumina fly ash, the mullite crystalline phase reacts with CaO to form Ca2Al2SiO7 and Ca... 12 Al 14 O 33 Ca2Al2SiO7 will continue to react with CaO to produce Ca 12 Al 14 O 33 The composite flux, along with Ca2SiO4, disrupts the stable structure of mullite, thereby separating the silicon and aluminum components in high-alumina fly ash. In this process, the composite flux, on the one hand, facilitates the formation of a eutectic system, significantly lowering the critical temperature for liquid phase formation; on the other hand, it integrates into the original crystal lattice, reducing the activation energy of phase transformation, breaking the stable state of the original crystal phase, and promoting phase transformation.

[0126] In this process, the large clinker obtained from high-temperature calcination is crushed into fine clinker particles in the crusher through mechanical forces such as extrusion and impact, thereby achieving pre-homogenization of particle size and increase of specific surface area. At the same time, microcracks and defects are formed on the surface of the fine clinker particles, which further enhances the reactivity of the material and provides an advantage for subsequent leaching.

[0127] Step S3: The fine-particle clinker and sodium carbonate solution (Na2CO3) are added to the leaching reactor for leaching reaction. The resulting leaching mixture is sent to the first solid-liquid separation device to separate it into a liquid phase of aluminum-rich leachate and a solid phase of aluminum extraction residue.

[0128] In the process of leaching the fine-particle clinker in Na2CO3 solution, the aluminum-containing component reacts with Na2CO3 to generate soluble NaAlO2, which dissolves in the solution to become an aluminum-rich leachate, thereby achieving the phase transformation and enrichment of aluminum elements; while the calcium-containing component precipitates as CaCO3 in solid form, and is then separated into aluminum-extracting residue by the first solid-liquid separation device.

[0129] Step S4: Add the aluminum-rich leaching solution and calcium oxide (CaO) to the desilication reactor to carry out the desilication reaction. The resulting mixture is sent to the second solid-liquid separation device to separate it into liquid phase desilication aluminum-rich leaching solution and solid phase aluminum extraction residue.

[0130] In the desilication reaction, CaO reacts with Na2SiO3 in the aluminum-rich leaching solution to generate insoluble CaSiO3, which is then separated into desilication-rich aluminum leaching solution and aluminum extraction residue by a second solid-liquid separation device, so as to remove soluble silicon from the aluminum-rich leaching solution and improve the purity of Al(OH)3.

[0131] Step S5: Add the desilication-rich aluminum leaching solution and carbon dioxide (CO2) to the carbon reactor for reaction. The resulting carbon mixture is sent to the third solid-liquid separation device to be separated into solid aluminum hydroxide (Al(OH)3) and liquid waste liquid.

[0132] In the carbonation reactor, CO2 is introduced into the desilication-rich aluminum solution for carbonation treatment. The pH of the desilication-rich aluminum solution gradually decreases, causing AlO2- to hydrolyze into Al(OH)3 crystals. The Al(OH)3 crystals then precipitate and are recovered by a third solid-liquid separation device. Meanwhile, impurities such as sodium silicate in the desilication-rich aluminum solution remain in the liquid phase and become waste liquid. This achieves efficient separation of aluminum and silicon impurities, improving the purity of Al(OH)3. Simultaneously, it achieves the capture and utilization of CO2, resulting in significant economic and environmental benefits.

[0133] Therefore, through steps S1 to S5, the present invention can extract Al(OH)3 from high-alumina fly ash, which has the advantages of low energy consumption and high purity, as detailed below:

[0134] Low energy consumption: Through the synergistic effect of the following steps, the calcination temperature of the formed billet in the roller kiln in step S2 can be reduced from 1400℃ in the traditional alkaline aluminization process to 900℃, reducing energy consumption by 15%-25% and effectively lowering production costs. The synergistic steps are as follows: Step S1 involves grinding and mixing high-alumina fly ash, carbide slag, and composite flux in a mill to achieve mechanical activation, enhancing the reaction effect in subsequent steps; during the high-temperature calcination in step S2, the composite flux lowers the sintering temperature by breaking stable Si-O-Si and Al-O-Si bonds in the raw materials, inducing the formation of soluble calcium aluminate and insoluble dicalcium silicate, promoting phase transformation, and achieving efficient separation of silicon and aluminum; furthermore, when CaF2 is used in the composite flux, F- can replace lattice oxygen to form (CaO). 11 (Al2O3)7(CaF2) further lowers the reaction energy barrier.

[0135] High purity: On the one hand, step S4 removes soluble silicon from the aluminum-rich leaching solution by reacting calcium oxide with Na2SiO3 in the aluminum-rich leaching solution to generate insoluble CaSiO3, thereby improving the purity of Al(OH)3 extracted from the desiliconized aluminum-rich leaching solution in step S5. On the other hand, step S5 introduces CO2 into the desiliconized aluminum-rich solution for carbonation treatment, which promotes the hydrolysis of AlO2- in the desiliconized aluminum-rich solution into Al(OH)3 crystals, while impurities such as sodium silicate in the desiliconized aluminum-rich solution remain in the liquid phase and become waste liquid, thus achieving efficient separation of impurities such as silicon from aluminum and improving the purity of Al(OH)3.

[0136] Furthermore, the reaction process in step S5 simultaneously achieves the capture and utilization of CO2, resulting in significant economic and environmental benefits.

[0137] The above is the basic implementation method of this embodiment one, and further optimizations, improvements and limitations can be made based on this basic implementation method:

[0138] Preferably, the method for the full resource utilization of fly ash further includes:

[0139] Step S6: The aluminum hydroxide (Al(OH)3) is fed into a calcining furnace and decomposed at high temperature to generate aluminum oxide (Al2O3).

[0140] Al(OH)3 undergoes a multi-stage phase transformation process under high temperature conditions, successively undergoing physical dehydration, chemical dehydration, lattice reconstruction, and crystal form optimization to generate Al2O3.

[0141] Steps S1 to S5 are implemented using the following parameters:

[0142] In step S1, the mass ratio of high-alumina fly ash, carbide slag and composite flux is (10-20):(20-35):1, and the composite flux contains two or three of CaF2, Na2CO3, CaCl2, NaF and NaSO4.

[0143] In the pressing and molding process of step S2, the mass ratio of raw material to water is 100:(10-5);

[0144] During the high-temperature calcination process in step S2, the calcination temperature is 900-1050℃, and the heat preservation time after calcination is 1-3 hours.

[0145] In the leaching reaction of step S3, the concentration of sodium carbonate solution is 35-60 g / L, and the solid-liquid ratio of fine clinker to sodium carbonate solution is 10:(1-2.5).

[0146] During the desilication reaction in step S4, 4-9g of calcium oxide is added to every 1L of aluminum-rich leaching solution.

[0147] In the reaction process of step S5, the rate of carbon dioxide introduction is 0.5-4 m / s. 3 / h, reaction time is 10-60min.

[0148] Preferably, steps S1 to S5 employ the following preferred parameters:

[0149] In step S1, the mill rotates at 400-600 rpm for 30-60 minutes, and the preset particle size threshold for the sieved raw material is 2 mm. Under these conditions, the grinding force is sufficient, which can balance the activation effect and production efficiency.

[0150] In the pressing and molding process of step S2, the hydraulic pressure of the press is 30-50MPa, and the molded blank is a disc-shaped blank with a diameter of 5-10cm and a thickness of 1-2cm. This makes the size of the disc-shaped blank appropriate, so that it can be heated evenly during high-temperature calcination, and avoids the large porosity of the molded blank due to insufficient pressure during pressing and molding, which would cause it to easily turn into powder during high-temperature calcination.

[0151] During the high-temperature calcination process in step S2, the heating rate is 5-9℃ / min.

[0152] During the crushing process in step S2, the crushing time is 10-40 minutes, and the particle size of the fine clinker is ≤1mm. This results in small and uniform particle size of the fine clinker, which helps to ensure complete reaction during leaching and improves the yield.

[0153] In the leaching reaction process of step S3, the reaction temperature is 60-90℃, the stirring rate is 400-500rpm, and the reaction time is 1.5-4h. Thus, the reaction temperature promotes the occurrence rate of the leaching reaction, stirring ensures the suspension of materials and avoids material sedimentation and agglomeration leading to incomplete leaching, and the reaction time ensures the completeness of the leaching process.

[0154] In the desilication reaction process of step S4, the reaction temperature is 60-90℃, the stirring rate is 400-500rpm, and the reaction time is 1-2.5h.

[0155] During the reaction process in step S5, the reaction temperature is 60-90℃.

[0156] Example 2

[0157] Based on the above embodiment one, this embodiment two also adopts the following preferred implementation method:

[0158] like Figure 2 As shown, the carbon reactor in step S5 is a three-phase fluidized bed.

[0159] Therefore, compared with the existing technology that uses stirred tanks or reaction vessels as carbon separation reactors, the present invention uses a three-phase fluidized bed, in which carbon dioxide gas (CO2) is introduced from the bottom air inlet 1 of the three-phase fluidized bed and aerated upward through the aeration plate 2, while the desilication-rich aluminum leaching liquid enters the three-phase fluidized bed from the liquid inlet 3 and flows downward due to gravity. Thus, carbon dioxide gas and desilication-rich aluminum leaching liquid undergo countercurrent mass transfer in the three-phase fluidized bed, ensuring a large contact area between the gas and liquid phases and high mass transfer efficiency. This significantly improves the reaction rate of carbon dioxide and desilication-rich aluminum leaching liquid, resulting in higher efficiency and better effect of the carbon separation process.

[0160] Example 3

[0161] Based on the above embodiment one or embodiment two, this embodiment three also adopts the following preferred implementation method:

[0162] The method for the full utilization of fly ash also includes:

[0163] Step S7: Add the waste liquid and NaOH from step S5 to the waste liquid regeneration reactor for reaction, and add the resulting recycled alkaline solution back to the leaching reactor from step S3 for leaching reaction.

[0164] Therefore, since the waste liquid in step S5 contains NaHCO3 generated by carbonation of the sodium carbonate solution (Na2CO3) in step S3 by introducing carbon dioxide (CO2) in step S5, the pH is reduced; while in the waste liquid regeneration reactor, NaOH is added to the waste liquid, which increases the pH, and NaOH reacts with NaHCO3 to generate sodium carbonate solution (Na2CO3), which can be used for leaching reaction in step S3, thereby achieving recycling.

[0165] In step S7, the pH of the recycled alkaline solution is 11-12.

[0166] Preferred method: By controlling the concentration of NaOH to 6-15 g / L, the pH of the recycled alkaline solution is precisely adjusted to 11-12.

[0167] Example 4

[0168] Based on any one of the above embodiments one to three, this embodiment four further adopts the following preferred implementation method:

[0169] The method for the full utilization of fly ash also includes:

[0170] Step S8: Add the aluminum extraction residue, acidic coal gangue and water from steps S3 and S4 to a wet ball mill for ball milling and mixing. After drying and screening, the mixed fine material with a particle size below the second preset particle size threshold is screened out and sent to a storage tank for temporary storage.

[0171] In the wet ball mill, the impact and crushing of steel balls combined with the lubrication and dispersion of water can refine the particle size of aluminum extraction residue and acidic coal gangue, increase the specific surface area of ​​the materials, and make the composition and particle size of the mixture uniform, thus avoiding problems such as alkali return and cracking of calcium silicate plates. At the same time, the alkaline components of aluminum extraction residue and the acidic components of acidic coal gangue come into full contact and undergo a neutralization reaction, stabilizing the pH of the mixture within the neutral range.

[0172] The mixture is preferably dried by a dryer and screened by a vibrating screen. Coarse material with a particle size larger than a second preset particle size threshold is returned to a wet ball mill for regrinding.

[0173] Step S9: The mixed fine materials, water, basalt fiber, and waterproofing agent are fed into a mixer and mixed. The resulting paste slurry is pressed into standard slabs by a hydraulic press.

[0174] The mixture of fine materials, water, basalt fiber, and waterproofing agent is homogenized through stirring, and the resulting paste-like slurry is suitable for subsequent pressing. The waterproofing agent is used to improve waterproofing and durability, and the basalt fiber is used to enhance the bending and impact resistance of the calcium silicate board.

[0175] Step S10: Place the standard slab in an autoclave for high-temperature and high-pressure curing, and after curing, cool it to room temperature for demolding. Then, after cutting and polishing, the finished calcium silicate board is obtained.

[0176] The standard slab undergoes a silicon-calcium hydration reaction during high-temperature and high-pressure curing, generating the high-strength mineral tobermorite, thus enabling the finished calcium silicate board to meet the requirements for calcium silicate boards used in construction.

[0177] Therefore, through steps S8 to S10, the present invention can prepare the aluminum extraction residue generated in steps S3 and S4 into a finished calcium silicate board that meets the requirements for calcium silicate boards used in construction. This can replace the existing technology of using limestone and quartz sand obtained through mining as raw materials for calcium silicate boards, effectively reducing the exploitation of natural resources and alleviating ecological problems from the source. It solves the following existing problems: In the existing technology, the production of traditional building materials such as calcium silicate boards requires a large amount of natural limestone and quartz sand as the main calcium and silicon sources. Both of these need to be obtained through mining, which can easily cause ecological damage problems such as vegetation destruction, soil erosion, and geological subsidence.

[0178] Furthermore, during the mixing process in step S9, the alkalinity of the aluminum extraction residue and the acidity of the coal gangue are neutralized, which can replace the dealkali removal process for aluminum extraction residue from fly ash in the prior art. At the same time, it achieves effective disposal of the two industrial solid wastes, aluminum extraction residue and coal gangue, avoids the environmental hazards caused by solid waste accumulation, and achieves the effects of "treating waste with waste" and "co-processing solid waste".

[0179] The above is the basic implementation method of this embodiment four, and further optimizations, improvements and limitations can be made based on this basic implementation method:

[0180] Steps S8 to S10 are implemented using the following parameters:

[0181] During the ball milling process in step S8, the mass ratio of aluminum extraction residue to acidic coal gangue is (1.5-2.5):1.

[0182] In step S8, the second preset particle size threshold is 100 μm;

[0183] In step S8, the pH of the mixed fine materials is 7-8, and the silicon-to-calcium ratio is 0.8-1.2;

[0184] In step S9, the mass ratio of the mixed fine materials, water, basalt fiber, and waterproofing agent is 100:(20-30):5:2;

[0185] During the high-temperature and high-pressure curing process in step S10, the constant temperature is 180-200℃ and the pressure is 0.8-1.1MPa.

[0186] Preferably, steps S8 to S10 employ the following preferred parameters:

[0187] During the ball milling and mixing process in step S8, the pH of the aluminum extraction residue is 8-11, and the pH of the acidic coal gangue is 2-4.

[0188] In the ball milling process of step S8, the mass ratio of solid material to water is 100:20 to ensure the fluidity of the material during ball milling, avoid high drying energy consumption due to excessive water or uneven material mixing due to insufficient water, and ensure that the particle size of the mixed fine material is ≤100μm.

[0189] During the drying process in step S8, the temperature is 200-350℃, and the product is dried to a moisture content of 1-3%.

[0190] During the pressing process in step S9, the standard slab size is 1220×2440×12mm, which conforms to the JC / T564.1-2018 industry standard, eliminating the need for secondary cutting and adapting to various application scenarios.

[0191] During the pressing process in step S9, the pressing pressure is 20MPa, the holding pressure is 60s, and the demolding speed is 5mm / s.

[0192] During the high-temperature and high-pressure curing process in step S10, the constant temperature stage lasts for 8-12 hours.

[0193] During the high-temperature and high-pressure curing process in step S10, the heating time is 1-2 hours and the cooling time is 4-6 hours to avoid thermal shock causing cracking of the slab and to control the flatness of the slab.

[0194] Example 5

[0195] Embodiment 5 of the present invention discloses a system for the full resource utilization of fly ash for the extraction of valuable metals, comprising: a high-alumina fly ash aluminum extraction module and a waste liquid regeneration module;

[0196] The high-alumina fly ash aluminum extraction module includes:

[0197] A mill is used to grind and mix high-alumina fly ash, carbide slag and composite flux evenly.

[0198] A vibrating screen, whose feed inlet is connected to the discharge outlet of the mill via a sealed pipeline, is used to screen out raw materials with a particle size below a preset particle size threshold.

[0199] A press, whose feed inlet is connected to the discharge outlet of the vibrating screen, is used to press the raw material and water into a molded blank.

[0200] The roller kiln has its feed end connected to the discharge port of the press via a high-temperature resistant conveyor belt, and is used to calcine the formed billet at high temperature.

[0201] The crusher, whose feed inlet is connected to the discharge end of the roller kiln, is used to crush the calcined billet into fine clinker.

[0202] The leaching reactor, whose inlet is connected to the outlet of the crusher, is used for leaching the fine clinker and sodium carbonate solution (Na2CO3) to obtain a leaching mixture.

[0203] The first solid-liquid separation device has its inlet connected to the outlet of the leaching reactor and is used to separate the leaching mixture into a liquid phase of aluminum-rich leaching solution and a solid phase of aluminum extraction residue.

[0204] The desilication reactor has its inlet connected to the liquid phase outlet of the first solid-liquid separation device, and is used for the desilication reaction of the aluminum-rich leaching solution and calcium oxide (CaO) to obtain a mixed liquid.

[0205] The second solid-liquid separation device has its inlet connected to the outlet of the desilication reactor and is used to separate the mixed liquid into a liquid phase of desilication-rich aluminum leaching solution and a solid phase of aluminum extraction residue.

[0206] The carbon reactor has its inlet connected to the liquid phase outlet of the second solid-liquid separation device and its inlet connected to a carbon dioxide gas source pipeline. It is used to react the desilication-rich aluminum leaching solution with carbon dioxide (CO2) to obtain a carbon mixture.

[0207] The third solid-liquid separation device has its inlet connected to the outlet of the carbon reactor and is used to separate the carbon mixture into solid aluminum hydroxide (Al(OH)3) and liquid waste liquid.

[0208] The calcining furnace has its feed inlet connected to the solid phase outlet of the third solid-liquid separation device, and is used to decompose the aluminum hydroxide (Al(OH)3) at high temperature to generate aluminum oxide (Al2O3).

[0209] The waste liquid regeneration module includes:

[0210] The waste liquid regeneration reactor has its inlet connected to the liquid phase outlet of the third solid-liquid separation device, and its outlet connected to the inlet of the leaching reactor via a pipeline. It is used to react the waste liquid with NaOH, and the resulting recycled alkaline solution is added back to the leaching reactor for leaching reaction.

[0211] Therefore, the fly ash full resource utilization system of the present invention can realize the above steps S1 to S7.

[0212] The above is the basic implementation method of this embodiment five, and further optimizations, improvements and limitations can be made based on this basic implementation method:

[0213] Preferably, the fly ash full-resource utilization system also includes a module for producing calcium silicate boards from the residue;

[0214] The residue-based calcium silicate board module includes:

[0215] A wet ball mill, whose feed inlet is connected to the solid phase outlet of the first solid-liquid separation device and the solid phase outlet of the second solid-liquid separation device, is used to ball mill and mix the aluminum extraction residue, acidic coal gangue and water to obtain a mixture.

[0216] A dryer, the feed inlet of which is connected to the discharge outlet of the wet ball mill, is used to dry the mixture.

[0217] A vibrating screen, whose inlet is connected to the outlet of the dryer, is used to screen out fine mixed materials with a particle size below a second preset particle size threshold from the dried mixture.

[0218] The agitator, whose inlet is connected to the outlet of the vibrating screen via a storage tank, is used to mix the fine mixed materials, water, basalt fiber, and waterproofing agent to obtain a paste-like slurry.

[0219] A hydraulic press, the inlet of which is connected to the outlet of the agitator, is used to press the paste slurry into standard slabs;

[0220] An autoclave, whose inlet is connected to the outlet of the hydraulic press via a conveyor belt, is used to cure the standard slab at high temperature and high pressure. After curing, the slab is cooled to room temperature for demolding, and then cut and polished to obtain the finished calcium silicate board.

[0221] Therefore, the fly ash full resource utilization system of the present invention can realize the above-mentioned steps S8 to S10.

[0222] Example 6

[0223] Embodiment Six of the present invention conducts an experiment on the optimal implementation method composed of Embodiments One to Five above, in order to verify the technical effect of the present invention.

[0224] High-alumina fly ash, carbide slag, and CaF2 were ground in a vibratory mill at a mass ratio of 15:25:1 for 40 minutes. The resulting raw material, after sieving, was mixed with water at a mass ratio of 100:7 and pressed into shape in a hydraulic press. The green body was then calcined in a roller kiln at 1000℃ for 2 hours, followed by crushing for 15 minutes to obtain clinker. The clinker and a 40 g / L Na2CO3 solution were reacted at a solid-liquid ratio of 10:1 in a leaching reactor at 65℃ for 2 hours, followed by filtration through a solid-liquid separation device A. The liquid phase was reacted with 6 g / L CaO in a desilication reactor at 65℃ for 2 hours, and then filtered through a solid-liquid separation device B to obtain a desilication-rich alumina leachate. CO2 was introduced into the alumina-rich alumina leachate in a carbonation reactor at 70℃ at a gas flow rate of 2 m / s. 3 The process is carried out at a rate of 15 minutes per hour. The material is then fed into a solid-liquid separation device C to separate the solid phase product, which is then calcined in a calcining furnace at 1200℃ to obtain Al2O3. The main chemical composition of this product is shown in Table 1 below, meeting the AO-1 grade in GB / T24487-2022 "Alumina". Therefore, this invention can extract Al(OH)3 from high-alumina fly ash and further obtain Al2O3 product with high purity.

[0225] Table 1

[0226]

[0227] High-alumina fly ash, carbide slag, and composite flux were ground in a vibratory mill at a mass ratio of 10:30:1 for 30 minutes. The resulting raw material, after sieving, was mixed with water at a mass ratio of 100:10 and pressed into shape in a hydraulic press. The billet was then fed into a roller kiln and calcined at 900℃ for 2 hours, followed by crushing for 15 minutes to obtain clinker. The clinker and a 55 g / L Na₂CO₃ solution (solid-liquid ratio 10:1) were reacted in a leaching reactor at 80℃ for 2 hours, followed by filtration through a solid-liquid separation device. The liquid phase and 4 g / L CaO were reacted in a desilication reactor at 80℃ for 2 hours, and then filtered through a solid-liquid separation device to obtain a desilication-rich alumina leachate. CO₂ was introduced into the alumina-rich alumina leachate in a fluidized bed carbonization reactor at 40℃ at a purge rate of 1 m³ / s. 3 The process is carried out at a rate of 40 minutes per hour. The material is then fed into a solid-liquid separation device to separate the solid phase product, which is then calcined in a calcining furnace at 1200℃ to obtain Al2O3. The main chemical composition of this product is shown in Table 2 below, meeting the AO-2 grade in GB / T 24487-2022 "Alumina". Therefore, this invention can extract Al(OH)3 from high-alumina fly ash and further obtain Al2O3 product with high purity.

[0228] Table 2

[0229]

[0230] Aluminum extraction residue and acidic coal gangue were ball-milled in a wet ball mill for 30 minutes at a mass ratio of 2:1, then dried in a dryer at 300℃ for 15 minutes and sieved. Fine materials, water, basalt fiber, and waterproofing agent were added to a mixer at a mass ratio of 100:30:5:2, and the mixture was stirred to form a slurry. The slurry was then pressed into shape under a hydraulic press at 20MPa, and cured in a horizontal autoclave for 1 hour of heating, 9 hours at 190℃, and 4 hours to room temperature. The resulting calcium silicate board was cut and polished. The mechanical properties of the finished product were tested as follows: flexural strength of 8.4MPa (R3 grade), and impact strength of 1.6kJ / m² (C2 grade), meeting the requirements of Class B products in standard JC / T 564.1-2018 "Fiber Reinforced Calcium Silicate Board Part 1: Asbestos-Free Calcium Silicate Board". Therefore, it can be seen that the present invention can prepare the aluminum extraction residue generated in steps S3 and S4 into a finished calcium silicate board that meets the requirements of calcium silicate board for building.

[0231] Adding 8 g / L NaOH to the waste liquid in the waste liquid regeneration reactor, the pH of the recycled alkali solution is approximately 12, and it can be added back to the leaching reactor for leaching again, allowing for reuse up to 6 times. Therefore, this invention, through step S7, reacts NaHCO3 in the waste liquid with NaOH to generate sodium carbonate solution (Na2CO3), which can be used for the leaching reaction in step S3, thereby achieving recycling.

[0232] This invention is not limited to the specific embodiments described above. Based on the above content and in accordance with common technical knowledge and conventional methods in the field, without departing from the basic technical concept of this invention, this invention can also make other equivalent modifications, substitutions or alterations, all of which fall within the protection scope of this invention.

Claims

1. A method for the full resource utilization of fly ash to achieve the extraction of valuable metals, characterized in that, include: Step S1: Add high-alumina fly ash, carbide slag and composite flux to the mill, grind and mix evenly, and then screen out the raw material with a particle size below the preset particle size threshold. Step S2: Add the raw material and water to the press and press to form a mold. The resulting molded blank is sent to the roller kiln for high-temperature calcination and then crushed into fine clinker by the crusher. Step S3: Add the fine-particle clinker and sodium carbonate solution to the leaching reactor for leaching reaction. The resulting leaching mixture is sent to the first solid-liquid separation device to separate it into a liquid phase of aluminum-rich leaching solution and a solid phase of aluminum extraction residue. Step S4: Add the aluminum-rich leaching solution and calcium oxide to the desilication reactor for desilication reaction. The resulting mixture is sent to the second solid-liquid separation device to separate it into liquid desilication aluminum-rich leaching solution and solid aluminum extraction residue. Step S5: Add the desilication-rich aluminum leaching solution and carbon dioxide to the carbon reactor for reaction. The resulting carbon mixture is sent to the third solid-liquid separation device to be separated into solid aluminum hydroxide and liquid waste liquid.

2. The method for full resource utilization of fly ash for extracting valuable metals according to claim 1, characterized in that: The method for the full utilization of fly ash also includes: Step S6: The aluminum hydroxide is fed into a calcining furnace and decomposed at high temperature to generate aluminum oxide.

3. The method for full resource utilization of fly ash for extracting valuable metals according to claim 1, characterized in that: Steps S1 to S5 are implemented using the following parameters: In step S1, the mass ratio of high-alumina fly ash, carbide slag and composite flux is (10-20):(20-35):1, and the composite flux contains two or three of CaF2, Na2CO3, CaCl2, NaF and NaSO4. In the pressing and molding process of step S2, the mass ratio of raw material to water is 100:(10-5); During the high-temperature calcination process in step S2, the calcination temperature is 900-1050℃, and the heat preservation time after calcination is 1-3 hours. In the leaching reaction of step S3, the concentration of sodium carbonate solution is 35-60 g / L, and the solid-liquid ratio of fine clinker to sodium carbonate solution is 10:(1-2.5). During the desilication reaction in step S4, 4-9g of calcium oxide is added to every 1L of aluminum-rich leaching solution. In the reaction process of step S5, the rate of carbon dioxide introduction is 0.5-4 m / s. 3 / h, reaction time is 10-60min.

4. The method for full resource utilization of fly ash for extracting valuable metals according to any one of claims 1 to 3, characterized in that: The carbon reactor described in step S5 is a three-phase fluidized bed.

5. The method for the full resource utilization of fly ash for extracting valuable metals according to any one of claims 1 to 3, characterized in that: The method for the full utilization of fly ash also includes: Step S7: Add the waste liquid and NaOH from step S5 to the waste liquid regeneration reactor for reaction, and add the resulting recycled alkaline solution back to the leaching reactor from step S3 for leaching reaction.

6. The method for full resource utilization of fly ash for extracting valuable metals according to claim 5, characterized in that: In step S7, the pH of the recycled alkaline solution is 11-12.

7. The method for full resource utilization of fly ash for extracting valuable metals according to any one of claims 1 to 3, characterized in that: The method for the full utilization of fly ash also includes: Step S8: Add the aluminum extraction residue, acidic coal gangue and water to a wet ball mill for ball milling and mixing. After drying and screening, the resulting mixture is screened to separate fine mixed materials with a particle size below the second preset particle size threshold. Step S9: The mixed fine materials, water, basalt fiber, and waterproofing agent are fed into a mixer and mixed. The resulting paste slurry is pressed into standard slabs by a hydraulic press. Step S10: Place the standard slab in an autoclave for high-temperature and high-pressure curing, and after curing, cool it to room temperature for demolding. Then, after cutting and polishing, the finished calcium silicate board is obtained.

8. The method for full resource utilization of fly ash for extracting valuable metals according to claim 7, characterized in that: Steps S8 to S10 are implemented using the following parameters: During the ball milling mixing process in step S8, the mass ratio of aluminum extraction residue to acidic coal gangue is (1.5-2.5):1; In step S8, the second preset particle size threshold is 100 μm; In step S8, the pH of the mixed fine materials is 7-8, and the silicon-to-calcium ratio is 0.8-1.

2. In step S9, the mass ratio of the mixed fine materials, water, basalt fiber, and waterproofing agent is 100:(20-30):5:2; During the high-temperature and high-pressure curing process in step S10, the constant temperature is 180-200℃ and the pressure is 0.8-1.1MPa.

9. A system for the complete resource utilization of fly ash to achieve the extraction of valuable metals, characterized in that, include: High-alumina fly ash aluminum extraction module and waste liquid regeneration module; The high-alumina fly ash aluminum extraction module includes: A mill is used to grind and mix high-alumina fly ash, carbide slag and composite flux evenly. A vibrating screen, whose feed inlet is connected to the discharge outlet of the mill via a sealed pipeline, is used to screen out raw materials with a particle size below a preset particle size threshold. A press, whose feed inlet is connected to the discharge outlet of the vibrating screen, is used to press the raw material and water into a molded blank. The roller kiln has its feed end connected to the discharge port of the press via a high-temperature resistant conveyor belt, and is used to calcine the formed billet at high temperature. The crusher, whose feed inlet is connected to the discharge end of the roller kiln, is used to crush the calcined billet into fine clinker. The leaching reactor, whose inlet is connected to the outlet of the crusher, is used for leaching the fine clinker and sodium carbonate solution to obtain a leaching mixture. The first solid-liquid separation device has its inlet connected to the outlet of the leaching reactor and is used to separate the leaching mixture into a liquid phase of aluminum-rich leaching solution and a solid phase of aluminum extraction residue. A desilication reactor, whose inlet is connected to the liquid phase outlet of the first solid-liquid separation device, is used to carry out a desilication reaction between the aluminum-rich leaching solution and calcium oxide to obtain a mixed liquid. The second solid-liquid separation device has its inlet connected to the outlet of the desilication reactor and is used to separate the mixed liquid into a liquid phase of desilication-rich aluminum leaching solution and a solid phase of aluminum extraction residue. The carbon reactor has its inlet connected to the liquid phase outlet of the second solid-liquid separation device and its gas inlet connected to a carbon dioxide gas source pipeline. It is used to react the desiliconized aluminum-rich leaching solution with carbon dioxide to obtain a carbon mixture. The third solid-liquid separation device has its inlet connected to the outlet of the carbon reactor and is used to separate the carbon mixture into solid aluminum hydroxide and liquid waste liquid. The calcining furnace has its feed inlet connected to the solid phase outlet of the third solid-liquid separation device, which is used to decompose the aluminum hydroxide at high temperature to generate aluminum oxide. The waste liquid regeneration module includes: The waste liquid regeneration reactor has its inlet connected to the liquid phase outlet of the third solid-liquid separation device, and its outlet connected to the inlet of the leaching reactor via a pipeline. It is used to react the waste liquid with NaOH, and the resulting recycled alkaline solution is added back to the leaching reactor for leaching reaction.

10. The fly ash full-resource utilization system for extracting valuable metals according to claim 9, characterized in that: The fly ash full-scale resource utilization system also includes a module for producing calcium silicate boards from the residue. The residue-based calcium silicate board module includes: A wet ball mill, whose feed inlet is connected to the solid phase outlet of the first solid-liquid separation device and the solid phase outlet of the second solid-liquid separation device, is used to ball mill and mix the aluminum extraction residue, acidic coal gangue and water to obtain a mixture. A dryer, the feed inlet of which is connected to the discharge outlet of the wet ball mill, is used to dry the mixture. A vibrating screen, whose inlet is connected to the outlet of the dryer, is used to screen out fine mixed materials with a particle size below a second preset particle size threshold from the dried mixture. The agitator, whose inlet is connected to the outlet of the vibrating screen via a storage tank, is used to mix the fine mixed materials, water, basalt fiber, and waterproofing agent to obtain a paste-like slurry. A hydraulic press, the inlet of which is connected to the outlet of the agitator, is used to press the paste slurry into standard slabs; An autoclave, whose inlet is connected to the outlet of the hydraulic press via a conveyor belt, is used to cure the standard slab under high temperature and high pressure.

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