(672a) Effect of Particle Size Distributions in Modeling Calcium Fluoride Flash Drying

Calcium fluoride is a widely used inorganic compound that occurs naturally and is produced synthetically as a precipitated by-product of various processes.  The moisture content and drying behavior of calcium fluoride are important for its utility in the downstream production of other chemicals like hydrogen fluoride and in the various manufacturing operations in which it is used.  For many processes, it is important that the moisture content and particle size distribution of the raw material be within an acceptable range; so, a drying unit operation is often used to condition the calcium fluoride feed material prior to its use.  This work applies flowsheeting software to model the drying behavior of calcium fluoride wetcake in a cocurrent, pneumatic conveying “flash” dryer.  The particle size distribution of the calcium fluoride feed is the key input parameter varied in the drying simulations while drying air velocity and relative humidity are held constant.  The simulation results are also compared with thin-layer drying kinetics literature models fitted to experimental data generated at different drying temperatures (50^oC, 80^oC, 110^oC) for calcium fluoride wetcake with an initial moisture content of 30–35%w.b.  This work can be used to study the effect of feed material particle size distribution on size reductions that may occur as a result of drying in a pneumatic conveying operation.