The products of selenite hydrothermal treatment in lithium chloride solutions

Selenite was boiled in LiCl solutions of different concentrations (1 M, 2 M, 3 M, 4 M and 5 M) at the respective boiling: temperatures and atmospheric pressure. The products were subjected to X -ray diffraction analysis, qualitative infrared analysis, differential thermal analysis, thermogravimetric analysis and microscopic examination. The product obtained in the I M LiCl solution was the beta-form Of calcium sulphate hemihydrate (beta-CaSO4.0.5H(2)O). In more concentrated LiCl solutons, 2 M and 3 M, the alpha-form of calcium sulphate hemihydrate (alpha-CaSO4.0.5H(2)O) was formed. The product obtained in the 4 M LiCl solution was also the alpha-form of calcium sulphate hemihydrate, only mixed with the gamma-form of calcium sulphate (gamma-CaSO4). Finally, in the 5 M LiCl solution the gamma-form of calcium sulphate or gamma-anhydrite was formed.