CALCINATION OF PHOSPHATE IN IMPINGING STREAMS .1. DEVELOPMENT, THEORYAND MODELING

An impinging-stream reactor, developed and tested for calcination of p hosphate with low organic matter content, has proven to be an efficien t device for conducting this process. Modeling of the calcination proc ess has been done along two lines. Considering a single particle and a ssuming that calcination rate is controlled by the heat transfer in th e particle, resulted in a criterion for testing the effect of temperat ure on the enrichment Of P2O5 and other phenomena. Performing a heat b alance on the reactor and on the particle, and incorporating physical concepts, led to correlations with only one adjustable parameter for t he conversion of carbonates as a function of the operating parameters. The major conclusion drawn from implementation of the model was that phosphate calcination is governed by the internal resistance of the pa rticle to the heat transfer. The calcination efficiency results, as we ll as the practical experience gained in this study, indicated that th e impinging-stream calciner may provide a promising tool for phosphate enrichment, and more generally, for processes involving gas-solid con tact at high temperatures.