Phosphogypsum contains soluble phosphorus, eutectic phosphorus, fluorine, organic matter and other harmful impurities, which deteriorate the performance of phosphogypsum, which is the main factor that cannot be used directly. Soluble phosphorus, fluorine and organic matter are distributed on the surface of phosphogypsum crystals. Impurities such as soluble phosphorus, eutectic phosphorus, and fluorine affect the hardening of cementitious materials and the bonding between crystals.
The phosphogypsum is calcined at a suitable temperature by the Liaoning Dongda powder swirl dynamic calcination process, and the eutectic phosphorus and organic matter can be removed. During the calcination process, the solid particles are directly mixed and contacted with the hot air flow and evenly distributed therein, which strengthens the mass transfer, In the heat transfer process, the thermal efficiency is greater than 80%, which is much higher than the heat utilization rate of the rotary kiln.
Phosphogypsum production Ⅱ type anhydrite calcination process
The wet phosphogypsum is sent into the dryer to remove the surface water, and then enters the first-stage cyclone calcination system to remove the crystal water, and then is sent to the second-stage dynamic calcination system for crystal modification. Quality and heat transfer, complete the process of dehydration and crystal transformation, and obtain type II anhydrite powder with excellent strength, whiteness, water resistance and other properties, and the calcination process is only ten seconds.
Characteristics of Type II Anhydrite Calcination in Phosphogypsum Production
Accurate temperature control, stable operation of the calciner, compact equipment structure, integrated design of drying, preheating, calcination and cooling, the system is environmentally friendly and energy-saving; the calcination degree of gypsum with different particle sizes is uniform, and the eutectic phosphorus can be removed.
Type II anhydrite can be used in self-leveling, dry mortar, plastering plaster and other fields; it can also replace fillers such as CaCO3, titanium dioxide, talc, etc. It has excellent performance and has wide application prospects in paper, rubber and plastic industries.