What is the difference between desulfurized gypsum, natural gypsum and phosphogypsum

What is the difference between desulfurized gypsum, natural gypsum and phosphogypsum 1. Difference in meaning 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%. Desulfurized gypsum is a by-product of FGD process. FGD process is a technology that uses lime limestone to recover sulfur dioxide from coal or oil flue gas. Natural gypsum is gypsum stone contained in nature, mainly dihydrate gypsum and anhydrite. Phosphogypsum refers to the solid waste residue produced when phosphate rock is treated with sulfuric acid in phosphoric acid production. Its main component is calcium sulfate. Phosphogypsum is mainly composed of CaSO4 · 2H2O. In addition, it also contains a variety of other impurities. 2. Differences in characteristics Desulfurization gypsum is transparent, glass luster, cleavage surface is pearl luster, fibrous aggregate is silk luster, and the relative density is 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 fibrous aggregate silk luster. Cleavage is very complete, and medium, and cleavage slices are divided into rhombic bodies with an included angle of 66 and 114. Brittle. Hardness 1.5 ~ 2. There is a slight change in different directions. Relative density 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 is negligible. Fluoride, free phosphoric acid, P2O5, phosphate and other impurities in phosphogypsum are the main factors causing environmental pollution in the process of phosphogypsum stacking.  3. Difference in purpose Desulfurized gypsum is widely used in many application fields, such as architecture, building materials, industrial molds and art models, chemical industry and agriculture, food processing and medical beauty. It is an important industrial raw material. The difference between desulfurization gypsum powder and general gypsum powder lies in the different physical composition. Desulfurization gypsum powder also contains silica, sodium oxide, calcium carbonate, calcium sulfite, limestone, calcium chloride, magnesium chloride, etc. Natural gypsum is used as retarder in cement industry after rinsing and drying; After rinsing and drying, it is used to produce ordinary β Type gypsum powder, and produce gypsum blocks, large boards and other gypsum products; Directly used in agriculture as land conditioner; Directly used for road construction materials.