Abstract: A continuous process is disclosed for the production, with a high yield, of high purity silicon tetrafluoride, starting from an aqueous solution of fluorosilicic acid, which comprises:(a) reacting an aqueous solution of fluorosilicic acid with concentrated sulphuric acid, carried out with a short residence time and preferably under fluido-dynamic conditions of turbulence, inside a reaction zone;(b) separating a gaseous stream containing silicon tetrafluoride from a liquid stream of aqueous sulphuric acid, carried out inside a separation zone, directly connected with the reaction zone;(c) washing said gaseous stream with concentrated and cold sulphuric acid carried out inside a washing zone, for the purpose of separating a gaseous stream of purified silicon tetrafluoride; and, possibly(d) further purifying said gaseous stream of purified silicon tetrafluoride by means of techniques of adsorption on an adsorbent solid material.

Abstract: A process is disclosed for the production of water soluble ammonium phosphates, comprising the following steps:(a) to react in a reaction step ammonia and untreated phosphoric acid with P.sub.2 O.sub.5 concentration comprised within the range of from 30 to 54%, outcoming from wet processes;(b) to filter under high temperature conditions the reaction suspension, separating the impurity-containing sludges from an aqueous solution of ammonium phosphate;(c) to cool and crystallize the aqueous solution of ammonium phosphate;(d) to separate the formed ammonium phosphate crystals from the mother liquors.