Effect of Phosphate Blending on Gypsum Morphology, Crystal Size Distribution and Filtration Rate

 E.A. Abdel-Aal§1, W.O. Shaaban1 and A.T. Kandil2

1. Central Metallurgical R&D Institute, P.O. Box 87 Helwan, Cairo, Egypt

2. Chemistry Department, Faculty of Science, Helwan University, Cairo, Egypt

Phosphoric acid is utilizing for production of fertilizers. It is mainly produced by the wet process, in which phosphate concentrate is leached with sulfuric and weak phosphoric acids with coproduction of calcium sulfate dihydrate (phosphogypsum). Gypsum morphology and crystal size distribution of New Valley (Egypt) and Russia phosphate as well as blends from them are studied.

Gypsum morphology of New Valley phosphate, Russia phosphate and blend from them are investigated. The crystal size distribution of New Valley and Russia phosphopgypsum show that the mean diameters of New Valley and Russia phosphogypsum samples are about 4.1 and 13.3 μm, respectively. With increasing blend ratio from Russia phosphate, the mean diameter is increased. The mean diameter of New Valley phosphogypsum increases from about 4.1 microns to 5.8 and 10.6 microns with blending ratios of 85 : 15 and 15 : 85 from New Valley : Russia blends, respectively. The filtration rate increase with increasing blending ratio from Russian phosphate. With blending ratios of 85 : 15 and 15 : 85 from New Valley with and Russia, the relative increase % in filtration rates were about 51 % and 250 %, respectively.