'A sheltered conveyor brings the Disco product from the carbonizers to this sheltered mechanical cooling wharf. A method of careful cooling in motion prevents spontaneous firing of the fuel and avoids injury to the structure of the product. The wharf is contructed of a series of grates, which are successively raised and lowered in a wavelike manner to keep the Disco product in motion and convey it slowly, while it is being cooled, down to the discharge end of the wharf.