Gypsum Exports from Iran: There are 227 active mines of gypsum stone in Iran, plus 193 different type gypsum mines in Iran. These are the mines which produce raw gypsum rocks and lumps. We supply gypsum in constructional as well as agricultural and industrial grades. There are also plenty of factories which are producing gypsum powder with different specifications. Various setting times are used for many constructional usages.
Gypsum is calcium sulfate (CaSO4). Refined gypsum in the anhydrite form (no water) is 29.4 percent calcium (Ca) and 23.5 percent sulfur (S). Usually, gypsum has water associated in the molecular structure (CaSO4·2H2O) and is approximately 23.3 percent Ca and 18.5 percent S (plaster of paris). Gypsum fertilizer usually has other impurities so grades are approximately 22 percent Ca and 17 percent S. Gypsum is sparingly soluble (the reason wallboard gets soft but does not immediately dissolve when it gets wet, at least if only damp occasionally). Gypsum is the neutral salt of a strong acid and strong base and does not increase or decrease acidity. Dissolving gypsum in water or soil results in the following reaction: CaSO4·2H2O = Ca2+ + SO42- + 2H2O. It adds calcium ions (Ca2+) and sulfate ions (SO42-), but does not add or take away hydrogen ions (H+). Therefore, it does not act as a liming or acidifying material. The Ca2+ ions simply interact with exchange sites in soil and sulfate remains dissolved in soil water.