FLASH DEHYDRATION OF ULEXITE AND INVESTIGATION OF DEHYDRATION KINETICS FROM THERMOGRAVIMETRIC DATA

The flash dehydration of a ulexite mineral in an entrained flow reacto r was investigated. Flash dehydration experiments were carried out in the range 400-700 degrees C with material of particle size -425+300 mu m. The weight loss at 700 degrees C dehydration temperature was measu red as 22%. A thermal gravimetric method was used to obtain the activa tion energy and rate constants for the dehydration of ulexite. The act ivation energy was in the range 48.2-53 kJ mol(-1) for different parti cle sizes. The rate constants for different particle sizes were found to vary between 1.8 x 10(-4) and 1.35 s(-1) in the temperature range 1 10-530 degrees C.