What should I do if my skin touches fluosilicic acid? Properties and safety protection of fluosilicic acid

[Alias] Fluorosilicic acid, Hydrofluorosilicic acid

[Molecular formula]H2SiF6

[Properties] Fluorosilicic acid is a colorless gas. It is unstable and easily decomposed into silicon tetrafluoride and hydrogen fluoride. The aqueous solution is a colorless and transparent fuming liquid with a relative density of 1.32 and a boiling point of 108.5°C. It has a pungent odor and is volatile. Anhydrous fluorosilicic acid cannot be produced from fluorosilicic acid, the highest concentration is 60.92%. The most stable composition is 13.3%. It does not decompose during distillation: when the concentrated fluorosilicic acid solution is cooled, colorless dihydrofluorosilicic acid (H2SiF6·2H2O) can be precipitated, its melting point is 19°C, it can be freely miscible with water, and has disinfection performance. It can corrode glass, ceramics, lead and other metals and should be stored in iron, wax or plastic containers. Strongly corrosive to skin.

［Application］ Preparation of sodium fluorosilicate, potassium fluorosilicate, zinc fluorosilicate, magnesium fluorosilicate, fluorosilicon Calcium phosphate, ammonium fluorosilicate, cryolite and other basic raw materials of fluorosilicate and silicon tetrafluoride. Used for wood preservation, beer disinfection, metal plating and porcelain processing, etc. It is also used in the manufacture of coatings, cement hardeners, etc.

[Brief recipe]

①In industry, the acid hydrolysis method of silica powder is mainly used, which is obtained by dissolving silica powder in hydrofluoric acid, followed by acid hydrolysis, filtration and purification.

②It is prepared by mixing quartz powder, calcium fluoride and concentrated sulfuric acid and then heating. It can also be obtained by absorbing the silicon tetrafluoride gas released from the decomposition of phosphate rock in the phosphate fertilizer plant through water absorption.

［Safety and Protection］ Fluorosilicic acid is a class I inorganic acid corrosive substance, hazard code number: 91036. Packed in polyethylene plastic drums, each drum has a net weight of 20kg or 25kg, and the packaging should be marked with “corrosive substances” or “highly toxic”. Store in a cool, ventilated place.

When the skin is stained with fluosilicic acid, it should be washed immediately with plenty of water or 10% ammonium carbonate solution.