A method for efficiently producing silicon tetrafluoride and sodium fluoride by utilizing sodium fluorosilicate

Abstract

The invention discloses a method for efficiently producing silicon tetrafluoride and sodium fluoride by using sodium fluorosilicate. The method includes a dehydration and drying process, a decomposition process, a desiliconization process and an absorption process, specifically: sodium fluorosilicate undergoes The dehydration drying process obtains anhydrous sodium fluorosilicate; then enters the decomposition process to obtain silicon tetrafluoride and semi-finished sodium fluoride; part of the silicon tetrafluoride is returned to the decomposition process as fluidizing gas, and the other part is used as a silicon tetrafluoride product; Part of the semi-finished sodium fluoride directly enters the desiliconization process to obtain sodium fluoride products and produce silicon tetrafluoride tail gas; the other part of the semi-finished sodium fluoride is used to absorb silicon tetrafluoride in the desiliconization tail gas to obtain semi-finished fluorine silicon Sodium acid is returned to the decomposition process, and the tail gas in the absorption process is sent to the alkali washing tower for treatment. The method is suitable for preparing silicon tetrafluoride and sodium fluoride by decomposing sodium fluorosilicate, and has the advantages of short process, low energy consumption, environmental friendliness and high added value of products.

Description

technical field [0001] The invention belongs to the fields of chemical industry and materials, in particular to a method for efficiently producing silicon tetrafluoride and sodium fluoride by using sodium fluorosilicate. Background technique [0002] my country is a big producer of phosphate fertilizers, and the production is accompanied by a large amount of fluosilicic acid output. At present, fluosilicic acid is mainly used to produce sodium fluosilicate. The product value of sodium fluorosilicate is low, the production capacity is excess, and the economic benefit is poor. Therefore, through technological innovation, the development and utilization of sodium fluorosilicate to produce high value-added fluorine salt chemicals has great economic and social benefits. Sodium fluorosilicate can be thermally decomposed to prepare silicon tetrafluoride and sodium fluoride. Silicon tetrafluoride is an important chemical raw material in the electronics and semiconductor industrie...

AI Technical Summary

Problems solved by technology

However, the process is still fixed-bed decomposition, which has small processing capacity and complicated operation, which is not conducive to large-scale continuous production, and needs to add decomposition aids, which increases the cost.

Chinese patent 201710216329.5 discloses a cyclic production process for preparing hydrogen fluoride from fluorosilicic acid, which involves thermal decomposition of sodium fluorosilicate to prepare sodium fluoride solid and silicon tetrafluoride gas, but does not give an actual operation plan

However, this process regenerates incompletely decomposed sodium fluorosilicate through a wet process, which has the disadvantages of long process, repeated drying, and high energy consumption.

[0004] In summary, the existing technology for preparing silicon tetrafluoride and sodium fluoride by pyrolysis of sodium fluorosilicate has problems such as melting agglomeration, incomplete decomposition, need to add additives, and long process

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