AbstractCalcination of a high organic matter phosphate and a phosphate containing pulverized coal up to 10 wt % was performed successfully in an impinging stream calciner. The results re‐established previous conclusions that the present calciner is a useful device.A simplified model has been developed for exploring the effect of various operating parameters on the concentration of phosphate particles at the impingement plane of the streams. It also assisted us in explaining the effect of the phosphate flow rate on the efficiency of calcination.It was established that the calcination rate of phosphate is governed by the internal resistance of the particle to the heat transfer, which was consistent with previous result