GB303760A - A process of decomposing salts of complex hydrofluoric acids - Google Patents

Abstract

303,760. Meyerhofer, A. F. July 28, 1927. Rotary furnaces; roasting furnaces.- Complex fluorides such as sodium, potassium, or barium silicofluorides are decomposed to form a metal fluoride and a volatile fluoride by heating in thin layers in a partial vacuum. The material is rapidly brought to a decomposition temperature to avoid partial sintering. Neutral gases or vapours such as air, steam, oxygen, flue gas, producer gas, etc., may be used to accelerate the removal of the gaseous fluoride, or solid or liquid substances which volatilize during the heating may be used. The heating may be carried out in a rotating or oscillating furnace comprising a central reaction tube b Fig. 1 surrounded by an annular chamber a heated by burners g. Additional burners for supplying hot gases to the chamber a at various points along its length may be used. The tubes, gas-supply pipes etc. may be mounted upon each other by means of springs. The heating may also be effected by passing the material down a cone a Fig. 7 or onto a horizontal rotating disc heated from below by a gas burner h, a device for producing flameless combustion or an electric heater. Suction is applied to the gas outlet h to produce a partial vacuum in the reaction chamber. Specification 249,860, [Class 1 (iii), Oxides &c., Metallic], is referred to.