3199279 A description referring now to the figure coal and limestone are proportioned in a ratio which is derived from about 1 to 5 parts of cao per part of sulfur in the coal i e coal containing 2 5 sulfur requires an addition of 2 5 to 12 5 of cao or 5 0 to 25 limestone which contains 50 cao within the stone as caco 3 proportioning in a continuous system can be made by continuous weighing feeders which are adjusted to conform to a desired ratio after proportioning the two raw materials are conveyed to a grinding and blending station where they are ground and intimately blended to enable a final size structure which is suitable for balling or compacting and to provide an intimate mixture of very fine particles which enable sulfur fixation reactions to take place usually a size structure of approximately 48 mesh is satisfactory for carrying out both phenomena a number of approaches can be used for grinding and blending to provide a moist blend for balling for example one such technique is wet circuit grinding wherein both coal and limestone in their natural states are wet ground and blended together in a ball mill with water and a slurry is filtered to a filter cake by vacuum filtration another technique involves dry circuit grinding wherein the.