Double-tank method for production of sodium fluorosilicate

Abstract

The invention relates to a double-tank method for production of sodium fluorosilicate. The method mainly includes the steps of adding fluosilicic acid into two reaction tanks in two times, carrying out synthesis reactions, maintaining excess sodium sulfate in a slurry in the 1# reaction tank, keeping excess fluorosilicic acid in a slurry in the 2# reaction tank, conducting sedimentation and thickening twice on the sodium fluorosilicate slurry coming out from the 2# reaction tank, filtering and washing the separated thick slurry in a lower layer to obtain a wet sodium fluorosilicate semi-finished product, and conducting drying to obtain a sodium fluorosilicate finished product; adding calcium carbonate powder and lime milk into the supernatant and washing liquid separated by the two times of sedimentation and thickening to conduct neutralizing treatment, and returning the obtained neutral mother liquor with about 0.3% of a sodium ion content to a wet process phosphoric acid tail gas absorption system to recover sodium ions. The production method provided by the invention has lower raw material consumption, and realizes real circulation of sewage in sodium fluorosilicate production.

Description

Technical field [0001] The present invention belongs to the technical field of chemical industry, and specifically relates to a production of sodium fluorosilicate (Na 2 SiF 6 )Methods. Background technique [0002] Our company's existing concentrated phosphoric acid production system and a large amount of 8%-12% fluorosilicic acid from the fluorine absorption chamber of the heavy superphosphate mixing section can be used to produce sodium fluorosilicate with market benefits. [0003] At present, the most common production methods of sodium fluorosilicate are sodium chloride method and sodium sulfate method. No matter which method is used, a large amount of mother liquor will be produced, which is difficult for enterprises to deal with. In the conventional sodium sulfate method, in order to ensure the coarse crystallization of sodium fluorosilicate, an excess of 20-30% of sodium ions is generally required. No matter which method is used for recycling, the mother liquor containing ...

AI Technical Summary

Problems solved by technology

No matter which method is used, a large amount of mother liquor will be produced, which is difficult for enterprises to handle

In the conventional sodium sulfate method, in order to ensure that the crystallization of sodium fluorosilicate is coarse, an excess of 20-30% of sodium ions is generally required. No matter which method is used to recycle the mother liquor containing sulfuric acid, a large amount of sodium ions will enter the production system, resulting in The enrichment of sodium ions or the formation of sodium fluorosilicate precipitation during production lead to serious fouling of the production system, which affects the normal operation of production

Moreover, the traditional production method has low utilization rate of raw materials and high consumption

Chinese patent ZL200810018141.0 discloses a sodium sulfate intermittent production method using mother liquor salt, the raw material consumption of this method is high, and the sulfuric acid content in the mother liquor increases, resulting in low utilization rate; Sodium sulfate production method, which reduces raw material consumption and reduces the sodium ion content in the mother liquor, and returns the mother liquor to the phosphoric acid extraction system to recover sulfuric acid

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