DISSOLUTION KINETICS OF ULEXITE IN AMMONIA SOLUTIONS SATURATED WITH CO2

The dissolution kinetics of ulexite in ammonia solutions saturated wit h carbon dioxide were investigated, Experiments investigating the foll owing parameters: concentration of ammonia; particle size; stirring sp eed; solid to liquid ratio; reaction temperature; and carbon dioxide f low rate; showed that ulexite can be dissolved completely in solutions of carbonic acid at atmospheric conditions, It was found that the dis solution rate increased with increasing ammonia concentration, reactio n temperature and calcination temperature, and with decreasing particl e size and solid to liquid ratio, It was observed that the flow rate o f carbon dioxide and stirring speed have almost no effect on the disso lution rate, It was determined that the dissolution rate of ulexite ca n be described by a first-order pseudo-homogeneous reaction model and an empirical equation for the process was developed: -ln(1-X) = 0(5)(C -A)(0.22)(d)(-0.92)(S/L)(-0.54)exp(-6600/T). t where C-A is the ammoni a concentration, d the initial particle size and (S/L) the solid to li quid ratio. The activation energy for the process was found to be appr oximately 55 kJ mol(-1)