plaster

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Anhydrite products

Anhydrite, natural anhydrous calcium sulfate [CaSO₄], an oblique Fangjing of the sulfate minerals.

Anhydrous calcium sulfate crystal clear, colorless, the proportion of 2.9 g/cm³, Mohs hardness of 3.0-3.5. Cheng Qian grey color massive ore, ore loading of loose bulk density about 1.849 T/M³, after processing the loose powder bulk density 919 Kg/M³.

The main purpose

Building materials industry: a cement-coagulation agents, agents of mineralization, particularly applicable to the production of concrete expanders, manufacture low-alkalinity special cement, anhydrite cementitious materials and products.

The chemical industry: co-production capacity of sulfuric acid and cement, for rubber, plastics and coatings, such as the production of fill. Application of agriculture: soil, pH adjustment, as feed additives, can add sulfur calcium nutrients.  

Ingredients:（%）

Note: The content of CaSO₄ of the sample 1# (first grade): 91.67%; that of the sample 2# (second grade): 79.72%.
　　Calculational formula of the grade of the anhydrite: CaSO₄+CaSO₄.2H₂O=1.7005×SO₃%+H₂O⁺%　
　　Production standard: GB/T5483-1996 " Gypsums and Anhydrites"
　　Quality analysis standard: GB5484-85 " Chemical Analysis Methods of Gypsums and Anhydrites"

Grade Rating （GB/T5483-1996）

Rating	First Grade	Second Grade	Third Grade	Fourth Grade
CaSO4+CaSO4.2H2O Grade, %（m/m)	≥85	≥75	≥65	≥55

The type and nature of gypsum:

Gypsum is a mineral title (CaSO4). Gypsum in the natural world can be divided into two broad categories: dihydrate gypsum plaster and water (anhydrite). Dihydrate gypsum contains two elements of the crystallization of water, chemical formula for CaSO4.2H2O, and anhydrite elements in the non-crystalline water or very little crystal water content (usually crystal water content ≤ 5%).

Gypsum and anhydrite dihydrate are rigid gas cementing material, after grinding process can be used to create painting materials, sheet metal and blocks of gypsum and other building materials. In cement industry, both of which can be used in cement production of condensate transfer agent, regulate the speed cement the role of condensation.

Compared with the dihydrate gypsum, anhydrite has a high solubility, but slower hydration. Crystal water content of the Nanjing-anhydrite little domestic production UEA, CEA, AEA series of concrete expanders important raw materials.