Fluorine free phospho gypsum - by heat treatment and sulphuric acid treatment

摘要

Fluorine free granulated phosphogypsum is obtd. by heat treatment and addn. of sulphuric acid of wet gypsum from phosphate plant, removing part of the face water to a residual water contact of 0.5-10% during the final heat treatment. It is then granulated by simultaneous addn. of sulphuric acid and binding additives. The amt. of energy needed to remove water is reduced, and the fluidised bed treatment of prior art, is made redundant.