VERFAHREN ZUR HERSTELLUNG VON ALUMINIUMFLUORID

1. A process of producing aluminum fluoride from aluminum hydroxide or alumina hydrate and hydrogen fluoride in a circulating fluidized bed system including a fluidized bed reactor, a cyclone separator and a recycling line, characterized in that partly reacted aluminum hydroxide circulated in a cooling cycle is added to fresh aluminum hydroxide or alumina hydrate in a first stage, in which the aluminum hydroxide is contacted with the hydrogen fluoride-containing exhaust gases from the circulating fluidized bed system so as to form a gas-solids suspension at a temperature of 150 to 250 degrees C, whereafter the solids are collected from the gas stream, at least part of the collected solids are passed through a cooler, cooled solids are re-contacted with fresh aluminum hydroxide or alumina hydrate, and a partial stream of the collected solids is supplied to the circulating fluidized bed system and is reacted therein at a temperature of at least 450 degrees C with hydrogen fluoride supplied in the form of a gas in a concentration up to 25 vol. %.