The use of medical gypsum powder:
It can be used as polishing powder, paper fillers, gas desiccant and medical plaster bandages. It is also used in metallurgy and agriculture. Cement factories also use gypsum to regulate the setting time of cement.
Calcium sulfide and carbon dioxide can be formed by high temperature interaction with carbon. Gypsum CaSO4•2H2O is a natural mineral, white, light yellow, light pink to gray transparent or translucent plate or fibrous crystals. Brittle, loss of 1.5H2O at 128℃, 2H2O at 163℃. In industry, gypsum is heated to 150℃ to dehydrate mature gypsum CaSO4•1/2H2O(or burnt gypsum), and then converted into CaSO4•2H2O by adding water. It can be used for plaster bandages, plaster models, chalk, crafts and building materials. Gypsum is also used as a speed regulator for cement to control its hardening rate. Paint putty, paper filler also used gypsum, daily point tofu can be used as a coagulant. Gypsum is applied agriculturally to reduce soil alkalinity. Gypsum ore and coal at high temperature can be used to produce SO2 for sulfuric acid. The solubility of CaSO4 is small, and its solubility presents a special condition of first increasing and then decreasing. If the solubility is 0.1928g / 100g water at 10℃ (the same below), 0.2097 at 40℃, and 0.1619 at 100℃, the hard water dissolved calcium sulfate will scale up in the high-pressure boiler (up to 400℃), causing harm. CaSO4 should be removed with Na2CO3 in advance to convert it into CaCO3 precipitation which is less soluble (to soften the hard water). When the marble encounters dilute H2SO4, due to the generation of slightly dissolved CaSO4 wrapped in the marble surface to block the contact with acid, so that the reaction stops, so it can not be used to produce CO2 with dilute H2SO4 and marble.