Wet-process phosphoric acid continuous purificn. - with addn. of aluminium ions to reduce fluorine content

摘要

Method comprises mixing the H3PO4 (opt. prefurified) with a miscible organic solvent in the presence of alkali metal or NH4 ions in an extrusion vessel. The organic phase is then passed through a series of extraction vessels in countercurrent contact with an aq. phase. The aq. or organic phase in >=1 of these vessels is treated with Al ions and the aq. phase in at least the last vessel is treated with alkali metal or NH4 ions. The treatment greatly reduces the F content of the product, making it suitable for use in the foodstuffs and pharmaceutical industries.