Beneficiation of an amorphous Gypsum sample from M/s. Bikaner Gypsums Ltd., Rajasthan

A sample of gypsum designated as amorphous gypsum, analysing 37.71 % SO3 (equivalent to 81.08% gypsum CaSO4) was received from M/s. Bikaner Gypsums Ltd., Rajasthan for beneficiation studies. The sample contained quartz and calcite as the principal gangue followed by minor amounts of micas, hornblende, chlorite, tourmaline, garnet, feldspar, halite and clay minerals. When the original sample was crushed to -10 mesh and screened through 150 mesh, it gave a +150 mesh fraction of purity 87.0% gypsum and 5.79% insolubles, with a recovery of 88.5% gypsum. This product is suitable for use in the manufacture of ammonium sulphate fertilizer. The -150 mesh rejects when subjected to flotation yielded a concentrate of grade 96.4% gypsum and 87.3%. This concentrate can be used in the manufactures of plaster of Paris.