CONTINUOUS PROCESS FOR COMPLETE REMOVAL OF ORGANIC IMPURITIES FROM AND COMPLETE DECOLORIZATION OF PREPURIFIED WET-PROCESS PHOSPHORIC ACID

摘要

A continuous process is indicated for complete removal of organic impurities from and complete decolorization of pre-purified wet-process phosphoric acid which has been purified by an extractive method using an organic solvent, freed from residual hydrofluoric acid by steam stripping and treated with hydrogen peroxide at elevated temperature, which comprises mixing the pre-purified wet-process phosphoric acid and the hydrogen peroxide in a mixing zone at a temperature of from 100 DEG to 200 DEG C., preferably 140 DEG to 160 DEG C., and allowing them to react at this temperature for a further 1 to 4 hours, cooling to from 85 DEG to 90 DEG C. the pre-purified wet-process phosphoric acid treated in this way and pumping it at this temperature with exclusion of air firstly through an activated charcoal bed which has been prepared on the basis of peat and has been steam-activated and has a BET surface area of from 800 to 1000 m2/g, and subsequently through a silicon carbide and/or graphite bed while maintaining a pumping rate of less than 0.5 m3/h of wet-process phosphoric acid per m3 of activated charcoal bed.