Abstract: A process is provided for burning a coal water slurry comprising providing clean coal fines of less than 100 mesh at about 50 weight % and water at about 50 weight % by co-firing the coal water slurry in a continuous stream with a separate stream of pulverized coal wherein about 80% of the total BTU output of the furnace is provided from the pulverized coal and approximately 20% of the BTU output is provided from the coal water slurry. First, a quarl in the furnace is preheated using natural gas, for example. The furnace is next fired with a fuel source of 60% pulverized coal and 40% natural gas. A coal water slurry with fines of minus 100 or smaller is subsequently gradually introduced into the furnace as the gas input is gradually decreased.