Desulfurization gypsum, also known as flue gas desulfurization gypsum, sulfur gypsum or FGD gypsum, is mainly composed of calcium sulfate dihydrate CaSO4 2H2O, with a content of ≥93%. Desulfurization gypsum is a by-product of FGD process, which is a technology to recover sulfur dioxide from coal or oil flue gas by using lime-limestone

Natural gypsum is gypsum stone in nature, mainly gypsum dihydrate and anhydrite.

Phosphogypsum refers to the solid waste produced when phosphate rock is treated with sulfuric acid in phosphoric acid production, and its main component is calcium sulfate. The main component of phosphogypsum is CaSO4 2H2O, and it also contains many other impurities.

2. Differences in characteristics

Desulfurized gypsum is a transparent, glassy, cleavage pearlescent and filamentous fiber aggregate with a relative density of 2.3. Desulfurization gypsum powder has the characteristics of renewable, small particle size, stable composition, less harmful impurities and high purity.

Natural gypsum cleavage surface has pearl luster and fiber aggregate silk luster. Cleavage is extremely complete and moderate, and the cleavage sheet splits into rhombuses with plane angles of 66 and114 respectively. Sexually fragile. The hardness is 1.5~2. Slight changes in different directions. The relative density is 2.3.

Phosphogypsum also contains arsenic, copper, zinc, iron, manganese, lead, cadmium, mercury and radioactive elements. They are extremely trace, and most of them are insoluble solids, and their harm can be ignored. Impurities such as fluoride, free phosphoric acid, P2O5 and phosphate contained in phosphogypsum are the main factors that cause environmental pollution during storage.

3, the difference in use

Desulfurized gypsum is widely used in architecture, building materials, industrial molds and art models, chemical industry, agriculture, food processing, medicine and beauty. It is an important industrial raw material. The difference between desulfurization gypsum powder and general gypsum powder lies in the difference in physical composition. Desulfurization gypsum powder also contains silicon dioxide, sodium oxide, calcium carbonate, calcium sulfite, limestone, calcium chloride, magnesium chloride and so on.

Natural gypsum is used as retarder in cement industry after rinsing and drying; After rinsing and drying, it is used to produce ordinary beta gypsum powder and gypsum products such as gypsum blocks and boards. Directly used in agriculture as an improver of land; Materials directly used in road construction.

Gypsum, an industrial by-product produced in the production of high-concentration phosphorus compound fertilizer, also increased rapidly, from 1 1 10,000 tons in 2000 to more than 40 million tons in 2008, and the accumulated storage capacity exceeded 1 100 million tons. The output of phosphogypsum in Yunnan, Hubei, Guizhou, Shandong, Anhui, Chongqing, Jiangsu, Sichuan, Guangdong and Shaanxi accounts for 9 1.5% of the total national phosphogypsum output.

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