Flash calcination of a magnesite ore in a free-fall reactor and leaching of magnesia

Flash calcination of a magnesite ore in a free-fall reactor and leaching of calcined magnesite with aqueous carbon dioxide were investigated. The effect of temperature and particle size on the weight loss were observed in the calcination experiments. The maximum weight loss was obtained as 43.2% for the particles of -100+140 mesh at the calcination temperature of 850 degrees C. In leaching experiments; leaching temperature and time, particle size, stirring speed, and solid/liquid ratio were selected as variables. The dissolution fraction of magnesium increases with the increase in the leaching time, temperature and to a lesser degree stirring speed. The dissolution also increases with decreasing solid/liquid ratio and particle size. A thermal gravimetric method was used to measure activation energy, preexponential factor and rate constants for the thermal decompositon of the magnesite ore. The activation energy and preexponential factor were calculated as 39.4 kcal mol(-1) and 3.5 X 10(6) s(-1), respectively. The rate constants were found to vary between 1.2 x 10(4) and 1.3 X 10(-2) s(-1) in the temperature range of 823 to 1023 K.