Optimization of the synthesis of highly pure calcium sulphate from dolomite ore

This study explores the synthesis of calcium sulfate (CaSO₄) from dolomite. The process involves leaching dolomite rock in hydrochloric acid and filtration to remove silica impurities. Optimization was achieved using the Box-Behnken design from Design Expert 13.0 software, with temperature (10-50 °C), time (5-10 min), and acid concentration (1-5 M) as variables. Optimal conditions for CaSO₄ synthesis were 10 °C, 10 min, and 3.5 M H₂SO₄. A significant quadratic model (P-value = 0.0002, R² = 0.923) was developed for CaSO₄ synthesis. XRD analysis confirmed the prominent phase angle of synthesized CaSO₄ at 11.8° with 92% purity. XRF analysis revealed a composition of 53.686% SO_3, and 41.798% CaO. The flaky morphology of CaSO₄ was observed from the SEM analysis, and TGA analysis showed stability at 200 °C and decomposition at 383.78 °C. This study demonstrates the suitability of Box-Behnken Design for determining optimal process parameters, and the high-purity CaSO₄ produced can be recommended for various applications, including bone implants, plaster of Paris, cement production, and soil remediation.