VERFAHREN ZUR HERSTELLUNG VON NASSVERFAHRENSPHOSPHORSAEURE.

摘要

Prodn. of wet-process H3PO4 is effected by digesting a phosphate ore with a mineral acid to form a lsurry of solids in crude H3PO4, and separating the H3PO4 from the slurry. The improvement comprises adding a soluble Al cpd. (I) to the ore or slurry in an amt. sufficient to give an Al concn. of 0.3-1 wt.% (based on P2O5). (I) is Al(OH)3, Al2(SO4)3, clay or an aluminate and is added to the ore or to the slurry during digestion (at a point near the ore feed inlet) in an amt. corresp. to 0.5-0.7 wt.% Al..