Effect of selected impurities on the continuous precipitation of calcium sulphate (gypsum)

Abstract

Abstract The effects of selected cationic and anionic impurities on the precipitation of gypsum in aqueous brine have been studied in a continuous MSMPR crystalliser. Crystal size distributions, determined by in situ Malvern laser light‐scattering measurements, were found to be bimodal. The suspected presence of agglomerates was confirmed by microscopy. Aluminium and maleate ions both enhanced the degree of agglomeration, but reduced the overall growth and nucleation rates. Contrary to expectation, fumarate ions also exerted an observable effect on both agglomeration and crystal growth.