Method for synthesizing fly ash zeolite by alkali fusion-microwave process

Abstract

The invention relates to a method for synthesizing fly ash zeolite by an alkali fusion-microwave process, particularly a method for synthesizing zeolite by utilizing industrial solid waste fly ash. In the invention, fly ash is used as a main raw material, NaOH is used as an activating agent, and an alkali fusion-microwave process is used for preparing the zeolite product. In the method, an ultrasonic dispersion process enables the activating agent to sufficiently contact the fly ash, and calcination enables the fusion reaction of the fly ash and the activating agent at high temperature, thereby increasing the conversion rate of the zeolite; the introduction of the 4A zeolite can enhance the purity of the 4A fly ash zeolite and reduce the generation of impure crystals; and microwaves are used for heating in the crystallization process, thereby greatly shortening the crystallization time of the zeolite. The method is simple to operate, has the advantages of simple equipment, short reaction time and energy saving, is convenient, feasible and practical, is suitable for industrial production of synthetic zeolite from fly ash, and develops a new way for comprehensive and cyclic utilization of fly ash.

Description

Technical field: [0001] The invention relates to a method for synthesizing fly ash zeolite by an alkali fusion-microwave method, specifically, a method for synthesizing zeolite mainly by using industrial solid waste fly ash. Background technique: [0002] Fly ash is a kind of fine-grained dispersed industrial solid waste after pulverized coal combustion, and its main component is SiO 2 and Al 2 o 3 , the total content of the two is above 70%. At present, the annual discharge of fly ash in my country has exceeded 160 million tons, and it is showing an upward trend year by year. According to relevant reports, the utilization rate of fly ash in my country is less than 40%, mainly used for road construction, building bricks and soil improvement. Fly ash has the characteristics of pozzolanic, and the synthesis of fly ash into zeolite is an effective way to turn fly ash into treasure and obtain high value-added products. [0003] The research on the synthesis of zeolite from ...

AI Technical Summary

Problems solved by technology

At present, the technology of using fly ash to synthesize zeolite is relatively mature. The main synthesis methods include hydrothermal synthesis, microwave-assisted synthesis, alkali fusion, salt heat, mixed alkali gas phase synthesis, and trace water system solid phase synthesis. method, etc., but the existing synthetic methods generally have shortcomings such as long reaction time, high cost, low zeolite conversion rate, and unsatisfactory product performance.

[0004] Hydrothermal synthesis is a traditional synthesis method that is widely used at present, but it has long aging time, high reaction temperature, high energy consumption, and low conversion rate of zeolite (a large amount of quartz and mullite in fly ash cannot be dissolved). And zeolite products are accompanied by by-product formation and other shortcomings

The microwave-assisted method is based on the traditional hydrothermal synthesis method. Although the speed of the fly ash crystallization process is improved, the synthesis time is greatly shortened, and the synthesis cost is reduced to a certain extent, it still cannot get rid of the traditional hydrothermal synthesis method. The problem inherent in the method, the conversion rate of the zeolite product is low

The alkali fusion method can convert most of the silicon-aluminum components in fly ash into zeolite, and the product does not contain mullite and quartz, which greatly improves the utilization rate of fly ash, and can be obtained by adjusting the silicon-aluminum ratio and optimizing the synthesis conditions Zeolite with higher purity, but the method is activated, heating and stirring takes a long time, and when reacting in a non-airtight container, the water in the reaction system is easy to volatilize

Although the salt heat method does not need to add water in the salt heat process, its composition contains a large amount of salt, and its products need to be washed with a large amount of water. If the treatment is not good, it will easily cause pollution to the environment, and the reaction temperature is high. Zeolite products The performance is not ideal

Mixed alkali vapor phase synthesis method can convert most of the silica-alumina components in fly ash, including mullite and quartz crystal phase, into cancryptite. Inferior disadvantages

Trace water system solid-phase synthesis method is difficult to complete the reaction due to the small amount of water in the reaction system and uneven mixing, and the conversion rate of fly ash and the performance of zeolite products are not ideal

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