Effect Of Desulfurized Gypsum On Cement Properties

2023-02-18

Desulfurized gypsum is an industrial by-product gypsum generated by the reaction of SO2 and CaCO3 during flue gas desulfurization in thermal power plants. The main component is CaSO4 · H2O. There are also some impurities, such as unreacted calcium carbonate, other impurities contained in limestone, and a small amount of potassium and sodium salts. The general content is not more than 0.5%. Desulfurized gypsum has a large output and is not limited by the natural gypsum production area. Its use in cement production has aroused widespread concern.

(1) Desulfurized gypsum is an industrial by-product gypsum produced by the reaction of limestone powder and sulfur dioxide. It does not contain impurities that have a negative impact on the performance of cement and is suitable for use as cement retarder.

(2) Similar to natural gypsum, desulfurized gypsum can adjust the setting time of cement normally. When 3%~5% desulfurized gypsum is added, the setting time of various types of cement can meet the requirements of national standards.

(3) Desulfurized gypsum contains CaCO3 and a small amount of soluble salt, which is beneficial to promote the development of cement strength and stimulate the activity of the mixture. The strength of cement using desulfurized gypsum as retarder is equivalent to that using natural gypsum, and the strength of some kinds of cement has been improved to a certain extent.

(4) After adding a small amount of cement, the desulfurized gypsum is pressed into granules, which not only meets the requirements of transportation and production use, but also does not significantly increase its production cost.