Reducing calcium sulphate hemihydrate ppn - by washing with surfactant

摘要

Use of a surfactant in the wet process for H3PO4 to was the filter cake, significantly reduces pptn. of CaSO4 1/2 H2O on the filter and minimises clogging. Surfactant may be aminogenic alkylbenzenesulphonic acids or their alkali metal salts with (8-18C) pref. (8-12C) alkyl gps or non-ionogenic condensates of alkylene oxide, pref. ethylene oxide (5-15 mol) with an alkylphenol (pref. 8-9C) alkyl) alkanol or glycol, or a mixture of the two in ratio 50:50 to 80-20. Surfactant is used at 0.0002-0.3% (pref. 0.002-0.2%) in the wash water at 20-90 degrees.