Method for producing tobermorite by conducting microwave heating on siliceous waste and carbide slag

Abstract

The invention provides a method for producing tobermorite by conducting microwave heating on siliceous waste and carbide slag. The method comprises the following technological steps that 1, siliceous waste is calcined and activated to obtain siliceous powder; 2, the siliceous powder, the carbide slag and a sodium hydroxide solution are mixed to be uniform, and a microwave heating synthesis reaction is conducted; 3, after the reaction is completed, mixed slurry is filtered to obtain a filter cake and filtrate with alkali; 4, the filter cake is washed and dried to obtain the tobermorite, and filter cake washing waste liquid and the filtrate with alkali are recycled and reused in the sodium hydroxide solution. Compared with an existing synthesis method, the method has the advantages that the reaction temperature is low, the time is short, the technology is simple, the conditions are mild, the obtained tobermorite is high in purity, single in physical phase, free of impurities and high in crystallinity, the production cost is significantly reduced, resources are significantly saved, and meanwhile a new solving way is provided for the discharge problem of three bulk solid waste including coal gangue, acid-soluble aluminum fly ash and carbide slag.

Description

technical field [0001] The invention relates to a method for producing tobermorite, in particular to a method for producing tobermorite by microwave heating of siliceous waste and carbide slag. Background technique [0002] The main solid waste discharged from coal mines or coal-fired power plants is siliceous waste, such as fly ash and coal gangue. Acid extraction of alumina in fly ash is an effective way to realize high value-added utilization of fly ash. Currently, the types of acids used include hydrochloric acid and sulfuric acid. Acid-soluble dealuminated fly ash is the residue left after extracting alumina from fly ash by acid method. Its chemical composition is mainly silica and a small amount of alumina. If the generated waste residue is not comprehensively utilized, new solid waste will be generated and secondary pollution will be formed. As for coal gangue, although my country has formulated a basic national policy for the utilization of coal gangue resources, t...

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Problems solved by technology

[0006] The existing method for producing tobermorite generally adopts diatomite or quartz sand and alkali to generate industrial water glass under melting conditions, and then adds calcareous raw materials to prepare tobermorite by hydrothermal method. During the preparation process of raw materials, It is necessary to use a large amount of high-quality silicon ore such as quartz sand and diatomite to co-melt with soda ash or sodium sulfate in a melting kiln, and then cool, pulverize and dissolve to make it; this makes the selection of silicon raw materials require mining and consumption of quartz and diatomite, etc. A large number of non-renewable silicon ore resources; at the same time, calcium raw materials generally need to use coke or white coal and other high-quality fuels to separately burn lime and refined lime milk, which consumes a lot of energy and costs, and has a great impact on resources and the environment

[0007] Chinese patent CN104258804 discloses a comprehensive utilization method of coal gangue. One of the steps involves preparing tobermorite from coal gangue. The method adopted is the hydrothermal and water-insulated autoclaving method. This method has high reaction temperature, long reaction time, The process is complicated, the amount of alkali is large, etc., and the prepared tobermorite is a mixed phase, with poor crystallinity and low purity, which is not suitable for the preparation of high-performance insulation materials and adsorbent materials.

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