A method of preheating coal for coking comprises bringing a hot operating gas into direct contact with the coal to preheat the coal. Both the coal and the operating gas are passed into a separator and the separator is operated so as to effect the separation of the coarse preheated coal for delivery to the coke oven from the operating gases and coal dust. The operating gases and coal dust are then passed into a deduster to remove the coal dust from the operating gases. A portion of the removed dust is continuously directed into an accumulator. The dust is either supplied from the deduster or the accumulator to a combustion furnace where it is burned to generate at least a portion of the operating gas. The amount of coal dust which is accumulated in the accumulator is checked regularly and the separator is operated so as to produce sufficient dust to maintain a desired operating level in the accumulator so that dust will always be available in a sufficient quantity to operate the combustion chamber for supplying the operating gases.