Verfahren zur Herstellung von wasserfreiem Magnesiumphosphat für sich oder in Mischung mit Calciumphosphat

摘要

Anhydrous magnesium phosphate is produced by reacting rock phosphate under anhydrous conditions and at a temperature not exceeding 600 DEG C. with an at least partly fused mixture of anhydrous magnesium chloride and an alkali metal or ammonium chloride containing at least the stoichiomatise amount of magnesium equivalent to the amount of calcium in the rock phosphate to be replaced by magnesium. Part or all of the chloride content may be removed by extraction with water, e.g. by quenching the hot product with water. The magnesium chloride and alkali metal or ammonium chloride may have a molar ratio of 1 : 1 and be present either as a mixture, or as a double salt. The rock phosphate may be introduced into a bath of the molten chlorides or it may be admixed with the solid chlorides and the mixture heated to sintering or complete fusion. Alternatively the solid mixture may contain magnesium chloride hexahydrate, and is then dehydrated and introduced into a bath of molten calcium chloride and alkali metal chloride and the precipitate of magnesium phosphate formed is separated from the bath.