Abstract: A machine for breaking frozen lumps of coal into smaller lumps includes a housing, a rotor which revolves within the housing and has teeth for engaging the coal, and a breaker plate which together with the rotor forms a converging space into which the rotor moves the coal to break up any frozen lumps. In addition, the machine has a baffle plate which at its lower end pivots on the housing and is inclined downwardly toward the rotor so as to direct large frozen lumps of coal into the teeth of the rotor, at least when the machine is configured to process frozen coal. With little effort, the machine may be converted to a by-pass configuration which permits unfrozen coal to pass through the housing without coming into contact with the rotor, and this of course reduces wear on the rotor.