A method for deep desiliconization of fly ash and recovery of silicon resources

A technology of resource recovery and fly ash, applied in chemical instruments and methods, silicate, transportation and packaging, etc., can solve the problems that the aluminum-silicon ratio of fly ash needs to be further improved, and achieve improved desiliconization efficiency and easy operation , The effect of not polluting the environment

Active Publication Date: 2021-07-09
HUANENG CLEAN ENERGY RES INST
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

[0005] Silicon in fly ash mainly exists in amorphous silica and mullite crystals. Most of the above process systems use lye to pre-desilicate fly ash to achieve the removal of amorphous silica , but the silicon element in the mullite crystal still exists in a large amount and stably, resulting in the aluminum-silicon ratio in the fly ash to be further improved; therefore, the development of the deep desilication technology system of the fly ash will improve the economic efficiency of the fly ash recovery and accelerate its resource recovery. It is important to use

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0022] Weigh the fly ash and put it into a ball mill tank, and carry out ball milling under the condition of 300rpm for 12h, put the fly ash after ball milling into a mesh bag of high temperature resistant material, and put 500g CaCl 2 Put the salt into the alumina crucible, add 5mol% CaO, and place the whole in the graphite crucible to prevent the leakage of liquid from damaging the furnace. Using the graphite crucible can consume the oxygen in the furnace and regulate the atmosphere of the furnace. Under the condition of argon atmosphere and 250℃ 2 Carry out the drying treatment for 48 hours, and then slowly raise the temperature to 850° C. at a rate of 4° C. / min under an inert atmosphere.

[0023] Put the fly ash precursor in the molten salt, slowly lift off the molten salt after reacting for 5 hours, take it out after cooling to room temperature under an inert atmosphere, and soak the test piece repeatedly with deionized water and dilute hydrochloric acid (0.1M). Ultrasou...

Embodiment 2

[0026] 500g CaCl 2 Put the salt into the alumina crucible, add 10mol% CaO, and place it in the graphite crucible as a whole to prevent damage to the furnace due to leakage. Using a graphite crucible can consume a certain amount of oxygen to regulate the atmosphere of the furnace. At 250°C for CaCl 2 The salt is dried for 48 hours. Then, under the protection of argon and cooling water, at 4°C min -1 The heating rate was used to slowly increase the temperature to 850 °C.

[0027] The fly ash precursor was placed in molten salt, and after 5 hours of reaction, the molten salt was slowly extracted, cooled to room temperature under an inert atmosphere, and then taken out, and the test piece was soaked repeatedly with deionized water and dilute hydrochloric acid (0.1M), and ultrasonically To remove the residual molten salt in the product, centrifuge the reaction product, and finally vacuum-dry it at 80° C. for 2 hours. The molar ratio of aluminum to silicon in the obtained desilic...

Embodiment 3

[0030] 500g CaCl 2 Put the salt into an alumina crucible, add 12mol% CaO, and place the whole in a graphite crucible to prevent damage to the furnace due to leakage. Using a graphite crucible can consume the oxygen in the furnace and control the atmosphere of the furnace. At 250°C for CaCl 2 The salt is dried for 48 hours. Then, under the protection of argon and cooling water, at 4°C min -1 The heating rate increases the temperature to 950 °C.

[0031] Put the fly ash precursor in the molten salt, and slowly extract the molten salt after reacting for 1 hour, take it out after cooling to room temperature under inert atmosphere conditions, soak the test piece repeatedly with deionized water and dilute hydrochloric acid (0.1M), and ultrasonically In order to remove the residual molten salt in the product, the reaction product was centrifuged, and finally vacuum-dried at 80° C. for 2 hours. The molar ratio of aluminum to silicon in the obtained desiliconized fly ash was 17.4. ...

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Abstract

The invention discloses a method for deep desiliconization of fly ash and recovery of silicon resources. The fly ash is ball milled and dried to form a fixed-shaped precursor; a certain amount of calcium oxide is added to molten salt, and under the condition of inert atmosphere protection, Heat the molten salt to a molten state; place the precursor of the fly ash in the molten reaction molten salt, react to a stable state, take out the reacted fly ash from the reaction molten salt and cool it under an inert atmosphere , the reaction product can be washed and dried to obtain deeply desiliconized fly ash; the reaction molten salt is cooled under inert atmosphere conditions, washed with water and filtered, and the obtained solid filter is calcium silicate; without using lye, the The silicon element is recovered in the form of silicate, which can effectively improve the desiliconization efficiency of fly ash, increase the aluminum-silicon ratio in the fly ash after desiliconization, the process is simple, and the effective recovery and utilization of silicon resources can be realized.

Description

technical field [0001] The invention belongs to the field of resource recovery of fly ash, and in particular relates to a method for deep desiliconization of fly ash and recovery of silicon resources. Background technique [0002] Fly ash is a major solid waste discharged from coal-fired power plants. Its large accumulation not only occupies land and causes waste of land resources, but also pollutes soil and water with heavy metals, thereby endangering human life, health and safety. Therefore, it is of great significance to develop the harmless treatment and resource utilization technology of fly ash. [0003] The main components of fly ash are metal oxides, unburned carbon and trace elements, among which metal oxides are mainly composed of aluminum oxide, silicon oxide, ferric oxide, calcium oxide, magnesium oxide and titanium dioxide. Due to the high content of alumina in fly ash, most fly ash resource utilization technologies currently focus on the recovery and utilizati...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): B09B3/00B09B5/00C01B33/24
CPCB09B3/00B09B5/00C01B33/24B09B3/40B09B3/35
Inventor 范金航郭东方汪世清刘练波郜时旺
Owner HUANENG CLEAN ENERGY RES INST
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