GB1326911A - Production of alkali metal or ammonium phosphate solutions - Google Patents

Abstract

1326911 Alkali metal and ammonium phosphates GIULINI GmbH Gebr 16 Oct 1970 [16 Oct 1969] 49273/70 Heading C1A An alkali metal or ammonium phosphate is produced by mixing impure aqueous H 3 PO 4 with a completely water-miscible organic solvent to produce a mainly organic phase containing H 3 PO 4 and a mainly aqueous phase, separating the two phases, reacting the organic H 3 PO 4 with an alkali metal or ammonium compound or ammonia, and separating the aqueous phosphate containing phase so produced. The initial H 3 PO 4 may be obtained by decomposing phosphate rock with H 2 SO 4 and may contain 20- 65% by wt. P 2 O 5 . The organic solvent may be aliphatic, aromatic, or cyclic mono- or polyhydric alcohol, ketone, ester, or cyclic ether, e.g. isopropanol or dioxan. The liquids may be mixed at 5-100‹ C. H 2 SO 4 may be added to the initial H 3 PO 4 or to the mainly aqueous phase to form sulphates of the inorganic impurities. The resulting aqueous phase is further treated with the solvent to extract H 3 PO 4 and the solvent is recycled. The alkali may be an oxide, hydroxide, carbonate, bicarbonate, or bacic phosphate, of Na, K or NH 4 , in aqueous solution or solid form, or gaseous NH 4 . Sufficient may be used to produce the mono-, di-, or tri-alkali form, and the product solution may be reacted with further alkali to form a different phosphate. The organic phase after separation of the aqueous phosphate may be treated with an alkali metal or ammonium compound, e.g. NaOH, to extract organic impurities into the aqueous phase, and the purified organic solvent recycled.