Treatment of solid fuels

A process for beneficiating and grinding solid fuel which comprises forming a mixture of particulate solid fuel having a majority of particles larger than U.S. Standard screen opening No. 20 and water, passing the mixture under conditions of turbulent flow through a heating zone to raise its temperature to between about 400 and 700.degree. F. at a pressure sufficient to maintain substantially all of the water in liquid state, passing the heated mixture at substantially the same temperature and pressure as it left the heating zone under conditions of turbulent flow through an elongated attrition zone for a period of time between about 5 seconds and 1 hour to form a mixture having a majority of particles smaller than U.S. Standard screen opening No. 20 and then cooling the mixture.