Method for preparing aluminun fluoride, waterless magnesium sulfate and sodium fluoride

Abstract

The process of preparing aluminum fluoride, anhydrous magnesium sulfate and sodium fluoride includes the following steps: 1. decomposing sodium fluorosilicate to produce sodium fluoride solid and silicon tetrafluoride gas; 2. absorbing silicon tetrafluoride gas with water and hydrolyzing, and washing and drying silica to obtain carbon white; 3. reacting fluorosilicic acid solution and magnesia, filtering and concentrating to obtain crystal magnesium fluorosilicate hexahydrate; 4. decomposing magnesium fluorosilicate hexahydrate to produce magnesium fluoride solid, silicon tetrafluoride gas and water vapor; 5. absorbing silicon tetrafluoride gas and water vapor with water and hydrolyzing, and washing and drying silica to obtain carbon white; 6. reacting magnesium fluoride and sulfuric acid to produce anhydrous magnesium sulfate, condensing and rectifying to obtain anhydrous hydrofluoric acid; and 7. reacting anhydrous hydrofluoric acid and aluminum hydroxide to produce aluminum fluoride.

Description

technical field

[0001] The invention relates to a method for preparing aluminum fluoride, anhydrous magnesium sulfate, and sodium fluoride, in particular to a method for preparing aluminum fluoride, anhydrous magnesium sulfate, and fluoride by using sodium fluorosilicate, magnesium oxide, and aluminum hydroxide as raw materials. Sodium method. Background technique

[0002] Aluminum fluoride is used as an additive in the production of electrolytic aluminum to lower the melting point of the electrolyte and increase the conductivity of the electrolyte. Its traditional production process is hydrofluoric acid-dry process and hydrofluoric acid-wet process. Hydrofluoric acid - the raw materials of the dry process are hydrogen fluoride and aluminum hydroxide, and its production process includes pretreatment of aluminum hydroxide to remove crystal water, and then powdered aluminum hydroxide and hydrogen fluoride gas The reaction is fully mixed under the reactor, and aluminum triflu...