27 may be reintroduced and distributed within raw coal 25 in a step 28 in pre controlled amounts through one or more pipes located within or around the free falling coarser coal as the raw coal 25 is discharged at some higher elevation from a conveyor belt for example the pulverized course coal 9 is dried before being used in the injection step 22 an optimum formulation is indicated in step 30 the formulation allows co burning fine coal 32 as coal water slurry cws with pulverized coal from a pulverization step 24 fed by raw coal 25 a critical aspect of the novel method for utilizing fine coal without expensive drying of the fines 11 before combustion is shown by step 34 no drying is necessary when step 28 is bypassed or shut down co firing combustion has been successfully conducted burning low solids cws in a co firing mode 35 with pulverized coal as shown in step 32 in step 34 cws is provided from 100 mesh coal from a coal preparation plant classifying cyclone overflow this coal is cleaned the degree of cleaning is to at least about 9 4 to 12 4 ash and about 1 sulfur as illustrated generally in fig5 table 1______________________________________cws characteristics 100 mesh coal viscositysample percent solids dispersant 100 sec 1 1000 sec 1______________________________________1 61 50 1 00 232 1362 61 35 0 75 504 2303 61 30 0 50 308 1484 60 75 0 25 540 3185 60.