CN-121992214-A - Method and system for realizing full-quantity resource utilization of fly ash for extracting valuable metals

CN121992214ACN 121992214 ACN121992214 ACN 121992214ACN-121992214-A

Abstract

The invention discloses a full-quantity recycling utilization method and system for fly ash for extracting valuable metals, wherein the full-quantity recycling utilization method and system comprise the steps of S1, adding high-alumina fly ash, carbide slag and a composite fluxing agent into a mill to grind, mix and screen out raw materials, S2, adding the raw materials and water into a press, feeding the obtained molded blank into a roller kiln to be calcined at high temperature, crushing the molded blank into fine-particle clinker through a crusher, S3, adding fine-particle clinker and sodium carbonate solution into a leaching reactor, feeding the obtained leaching mixed material into a first solid-liquid separation device to be separated into aluminum-rich leaching liquid and aluminum-extracting residues, S4, feeding the aluminum-rich leaching liquid and calcium oxide into a desilication reactor, feeding the obtained mixed material into a second solid-liquid separation device to be separated into desilication aluminum-rich leaching liquid and aluminum-extracting residues, and S5, feeding the desilication aluminum-rich leaching liquid and carbon dioxide into a carbon-separating reactor, and feeding the obtained carbon-separating mixed material into a third solid-liquid separation device to be separated into aluminum hydroxide and waste liquid. The invention can extract Al (OH) 3 from high-alumina fly ash, and has the advantages of low energy consumption and high purity.

Inventors

WEI CONG
ZHOU YAN
YAN XINYI
YI HAO
SHI HAOYANG
YE DIAN

Assignees

中国石油化工股份有限公司
中石化第五建设有限公司

Dates

Publication Date: 20260508
Application Date: 20251229

Claims (10)

1. A method for realizing full-scale resource utilization of fly ash for extracting valuable metals is characterized by comprising the following steps: S1, adding high-alumina fly ash, carbide slag and a composite fluxing agent into a mill, grinding and uniformly mixing, and screening out raw materials with particle diameters below a preset particle diameter threshold; S2, adding the raw materials and water into a press for compression molding, and sending the obtained molded blank into a roller kiln for high-temperature calcination and crushing the molded blank into fine-particle clinker by a crusher; S3, adding the fine particle clinker and the sodium carbonate solution into a leaching reactor for leaching reaction, and sending the obtained leaching mixture into a first solid-liquid separation device to separate into liquid-phase aluminum-rich leaching solution and solid-phase aluminum extraction residues; S4, adding the aluminum-rich leaching solution and calcium oxide into a desilication reactor for desilication reaction, and sending the obtained mixture liquid into a second solid-liquid separation device, wherein the mixture liquid is separated into liquid-phase desilication aluminum-rich leaching solution and solid-phase aluminum extraction residues; And S5, adding the desilication aluminum-rich leaching solution and carbon dioxide into a carbon dioxide reactor for reaction, and sending the obtained carbon dioxide mixture into a third solid-liquid separation device to separate into solid-phase aluminum hydroxide and liquid-phase waste liquid.
2. The method for realizing full-quantity recycling of the fly ash for extracting valuable metals according to claim 1 is characterized by further comprising the following steps: and S6, sending the aluminum hydroxide into a calciner for pyrolysis to generate aluminum oxide.
3. The method for realizing full-scale recycling of the fly ash for extracting valuable metals according to claim 1 is characterized in that the steps S1 to S5 are realized by adopting the following parameters: in the step S1, the mass ratio of the high-alumina fly ash to the carbide slag to the composite fluxing agent is (10-20): (20-35): 1, and the composite fluxing agent comprises two or three of CaF 2 、Na 2 CO 3 、CaCl 2 、NaF、NaSO 4 ; in the compression molding process of the step S2, the mass ratio of raw materials to water is 100 (10-5); In the high-temperature calcination process of the step S2, the calcination temperature is 900-1050 ℃, and the heat preservation time after calcination is 1-3h; In the leaching reaction process of the step S3, the concentration of the sodium carbonate solution is 35-60g/L, and the solid-liquid ratio of the fine particle clinker to the sodium carbonate solution is 10 (1-2.5); In the desilication reaction process of the step S4, 4-9g of calcium oxide is added into every 1L of aluminum-rich leaching solution; In the reaction process of the step S5, the speed of introducing carbon dioxide is 0.5-4m 3 /h, and the reaction time is 10-60min.
4. A method for realizing full-scale recycling of fly ash for valuable metal extraction according to any one of claims 1 to 3, wherein the carbon-containing reactor in the step S5 is a three-phase fluidized bed.
5. The method for realizing full-quantity resource utilization of the fly ash for extracting valuable metals according to any one of claims 1 to 3, which is characterized by further comprising the following steps: And S7, adding the waste liquid and NaOH obtained in the step S5 into a waste liquid regeneration reactor for reaction, and adding the obtained recycled alkali liquid into the leaching reactor for leaching reaction in the step S3 again.
6. The method for realizing full-scale recycling of the fly ash for extracting valuable metals according to claim 5, wherein in the step S7, the pH value of the recycled alkali liquor is 11-12.
7. The method for realizing full-quantity resource utilization of the fly ash for extracting valuable metals according to any one of claims 1 to 3, which is characterized by further comprising the following steps: S8, adding the aluminum extraction residues, the acid gangue and the water into a wet ball mill for ball milling and mixing, and sieving to obtain a mixed fine material with the particle size below a second preset particle size threshold after sequentially drying and sieving the obtained mixed material; Step S9, the mixed fine materials, water, basalt fibers and waterproof agents are sent into a stirrer to be stirred and mixed, and the obtained pasty slurry is pressed into a standard slab through a hydraulic press; And S10, placing the standard plate blank into an autoclave for high-temperature high-pressure curing, cooling to room temperature after curing, demolding, and cutting and polishing to obtain a finished product of the silicon-calcium plate.
8. The method for realizing full-scale recycling of the fly ash for extracting valuable metals according to claim 7, wherein the steps S8 to S10 are realized by adopting the following parameters: in the ball milling mixing process of the step S8, the mass ratio of the aluminum extraction residue to the acid gangue is (1.5-2.5): 1; In the step S8, the second preset particle size threshold is 100 μm; in the step S8, the pH value of the mixed fine material is 7-8, and the silicon-calcium ratio is 0.8-1.2; in the step S9, the mass ratio of the mixed fine materials to the water to the basalt fiber to the waterproof agent is 100 (20-30) to 5:2; In the high-temperature high-pressure curing process of the step S10, the constant temperature is 180-200 ℃ and the pressure is 0.8-1.1MPa.
9. The full-quantity coal ash recycling system for extracting valuable metals is characterized by comprising a high-alumina fly ash aluminum extraction module and a waste liquid regeneration module; the Gao Lvfen coal ash aluminum extraction module comprises: the mill is used for grinding and uniformly mixing the high-alumina fly ash, the carbide slag and the composite fluxing agent; the feed inlet of the vibrating screen is connected with the discharge outlet of the mill through a sealing pipeline and is used for screening out raw materials with particle sizes below a preset particle size threshold value; the feeding hole of the press is connected with the discharging hole of the vibrating screen and is used for shaping the raw materials and water pressure to obtain a shaped blank; The feeding end of the roller kiln is connected with the discharging port of the press through a high-temperature-resistant conveying belt and is used for carrying out high-temperature calcination on the formed green body; the feeding port of the crusher is connected with the discharging end of the roller kiln and is used for crushing the molded green body subjected to high-temperature calcination into fine particle clinker; the leaching reactor is characterized in that a feed inlet of the leaching reactor is connected with a discharge outlet of the crusher and is used for carrying out leaching reaction on the fine particle clinker and the sodium carbonate solution to obtain a leaching mixed material; The feed inlet of the first solid-liquid separation device is connected with the discharge outlet of the leaching reactor and is used for separating the leaching mixed material into liquid-phase aluminum-rich leaching liquid and solid-phase aluminum extraction residues; The feed inlet of the desilication reactor is connected with the liquid phase outlet of the first solid-liquid separation device and is used for carrying out desilication reaction on the aluminum-rich leaching solution and calcium oxide to obtain mixture feed liquid; The feed inlet of the second solid-liquid separation device is connected with the discharge outlet of the desilication reactor and is used for separating the mixed material liquid into desilication aluminum-rich leaching liquid in a liquid phase and aluminum extraction residues in a solid phase; The water inlet of the carbon component reactor is connected with the liquid phase outlet of the second solid-liquid separation device, and the air inlet of the carbon component reactor is connected with a carbon dioxide air source pipeline for reacting the desilication aluminum-rich leaching solution with carbon dioxide to obtain a carbon component mixed material; The third solid-liquid separation device is connected with the discharge port of the carbon component reactor and is used for separating the carbon component mixture into solid-phase aluminum hydroxide and liquid-phase waste liquid; The feeding port of the calciner is connected with the solid phase outlet of the third solid-liquid separation device and is used for decomposing the aluminum hydroxide at high temperature to generate aluminum oxide; the waste liquid regeneration module comprises: And the feed inlet of the waste liquid regeneration reactor is connected with the liquid phase outlet of the third solid-liquid separation device, and the discharge outlet of the waste liquid regeneration reactor is connected with the feed inlet of the leaching reactor through a pipeline and is used for reacting the waste liquid with NaOH, and the obtained recycled alkali liquor is added into the leaching reactor again for leaching reaction.
10. The full-quantity fly ash recycling system for extracting valuable metals according to claim 9 is characterized by further comprising a residue-made calcium silicate board module; The residue system calcium silicate board module includes: The feed inlet of the wet ball mill is respectively connected with the solid phase outlet of the first solid-liquid separation device and the solid phase outlet of the second solid-liquid separation device, and is used for ball milling and mixing the aluminum extraction residues, the acid gangue and the water to obtain a mixed material; The feed inlet of the dryer is connected with the discharge outlet of the wet ball mill and is used for drying the mixed materials; the feed inlet of the vibrating screen is connected with the discharge outlet of the dryer and is used for screening out mixed fine materials with the particle size below a second preset particle size threshold value from the dried mixed materials; the feed inlet of the stirrer is connected with the discharge outlet of the vibrating screen through a storage tank and is used for stirring and mixing the mixed fine materials, water, basalt fibers and waterproof agents to obtain pasty slurry; the feed inlet of the hydraulic press is connected with the discharge outlet of the stirrer and is used for pressing the pasty slurry into a standard slab; And the feeding port of the autoclave is connected with the discharging port of the hydraulic press through a conveying belt and is used for carrying out high-temperature and high-pressure maintenance on the standard slab.

Description

Method and system for realizing full-quantity resource utilization of fly ash for extracting valuable metals Technical Field The invention relates to the technical field of comprehensive treatment of fly ash, in particular to a method and a system for realizing full-quantity resource utilization of fly ash for extracting valuable metals. Background The annual production of high-alumina fly ash in China exceeds 3000 ten thousand tons, and the alumina content reaches 10% -50%, so that the high-alumina fly ash is an important potential resource for replacing the traditional bauxite. However, there is a significant bottleneck in current high alumina fly ash recycling: Firstly, the traditional alkaline aluminum extraction process needs high-temperature calcination at 1200-1400 ℃, the energy consumption is high, and the suitability of the parameters of the ball milling, leaching and other links is poor, so that the aluminum extraction efficiency is low. The purity of the extracted Al (OH) 3 is low. Secondly, the leaching waste liquid contains a large amount of sodium salt, lacks a high-efficiency regeneration means, and is directly discharged to pollute the environment. Thirdly, the aluminum extraction residues generated in the aluminum extraction process have large production amount, the silicon-calcium residues in the aluminum extraction residues are large in alkalinity, and then the aluminum extraction residues are reused, and are subjected to dealkalization treatment by additionally adding dealkalization procedures, so that the aluminum extraction residues can be used for building materials, the process cost is increased, and if the aluminum extraction residues are not subjected to dealkalization treatment, soil salinization is easily caused by direct piling. In view of the foregoing, there is a need to develop a low energy consumption, full component utilization integrated technology and system. Disclosure of Invention The invention aims to solve the technical problems of high energy consumption and low purity of extracting Al (OH) 3 from high-alumina fly ash in the prior art. The technical scheme adopted by the invention is as follows: a method for realizing full-scale resource utilization of fly ash for extracting valuable metals comprises the following steps: S1, adding high-alumina fly ash, carbide slag and a composite fluxing agent into a mill, grinding and uniformly mixing, and screening out raw materials with particle diameters below a preset particle diameter threshold; The grinding machine is preferably a vibration grinding machine, and the high-alumina fly ash, the carbide slag and the composite fluxing agent are repeatedly impacted and mixed in the vibration grinding machine to achieve the effects of increasing the specific surface area of materials, refining the particle size, uniformly mixing and destroying the surface grains of the mullite phase, realize mechanical activation and strengthen the reaction effect for the subsequent steps. The raw materials are preferably screened by a vibrating screen, and coarse materials with the particle size larger than a preset particle size threshold value are returned to the mill for grinding and mixing again. S2, adding the raw materials and water into a press for compression molding, and sending the obtained molded blank into a roller kiln for high-temperature calcination and crushing the molded blank into fine-particle clinker by a crusher; wherein, the press makes loose raw material particles form stable agglomeration structure, provides structural basis for follow-up calcination, and is convenient for transport and space saving. In the high-temperature calcination process of the roller kiln, ca (OH) 2 contained in carbide slag is converted into CaO, the CaO reacts with corundum in the high-alumina fly ash to generate Ca 12Al14O33, mullite crystal phase in the high-alumina fly ash reacts with CaO to generate Ca 2Al2SiO7 and Ca 12Al14O33,Ca2Al2SiO7 which continuously react with CaO to generate Ca 12Al14O33 and Ca 2SiO4, so that the purpose of destroying the stable structure of mullite is realized, and the silicon-aluminum components in the high-alumina fly ash are separated. In the process, the composite fluxing agent is favorable for forming a eutectic system on one hand, obviously reducing the critical temperature of liquid phase formation, and on the other hand, the composite fluxing agent is excessively fused into the original crystal lattice, reduces the activation energy of crystal phase conversion, breaks the stable state of the original crystal phase and promotes the crystal phase conversion. The large clinker obtained by high-temperature calcination is crushed into fine-particle clinker by the action of mechanical forces such as extrusion, impact and the like in a crusher, so that the particle size pre-homogenization and the specific surface area increase are realized, and microcracks and defects are formed on the surface of the fine-particle cl