Cylindrical samples of spent shale were heated. In each experiment, the weight loss was recorded as a function of time until the sample reached approximately constant weight. The final weight loss and the chemical analyses before and after the thermal treatment showed that virtually all carbon dioxide contained in dolomite is liberated during the heating of spent shale at these temperatures. The decomposition rate of dolomite can adequately be treated with a global, first order kinetics. The rate of dolomite decomposition in a block of spent shale can be predicted with reasonable confidence by properly accounting for intrinsic kinetics and heat transport effects.