Phosphogypsum as a mineral filler for polymers


Problem Overview
	Phosphogypsum is the phosphate fertilizer industry solid waste, and phosphoric acid is the foundation of phosphate fertilizer industry. Wet phosphoric acid (WPA) production of sulfuric acid decomposition through phosphate rock formation extraction slurry, and then filter cleaning system in the phosphorylation. In the process of washing filters at the same time have a phosphogypsum waste. General production of one ton of phosphate per produces about six tons of phosphogypsum, the production of one ton per DAP emissions 2.5 to 5 tons of phosphogypsum, our WPA yield about 100 million tons. Phosphogypsum generally is powder, because contain 8 to 15%, so it is paste-like, the particle diameter is generally 5 to 150 micrometers, the main ingredients is CaSO4.2H2O, it usually is 70 to 90 %, which contained elements of the secondary sources of ore vary, more complex ingredients are generally contain elements of rock, Ca, Mg phosphate, carbonate and silicate, In addition, a small amount of organic phosphorus, sulfur, fluorine compounds. Phosphogypsum general appearance of a gray, light yellow, light green, and other colors, the relative density is 2.22 - 2.37, the capacity is 0.733 - 0.880 g/cm3. Because of their different manufacturers, their composition, color, physical properties and impurity content, types of impurities, and so the process and its principles vary, but they all have the common characteristics.
PHOSPHORIC ACID Production
Wet process phosphoric acid is prepared by adding sulfuric acid to calcium phosphate rock. The simplified reaction is: 3 H2SO4 + Ca3(PO4)2 + 6 H2O <--> 2 H3PO4 + 3 CaSO4.2H2O Wet-process acid can be purified by removing fluorine to produce animal-grade phosphoric acid, or by solvent extraction and arsenic removal to produce food-grade phosphoric acid.