Abstract: This invention discloses (1) a dispersant for an aqueous carbonaceous solid slurry, which comprises a water-soluble copolymer having an average molecular weight of 1,000 to 500,000 and obtained by polymerizing (A) 0.1 to 7 mol % of a polyalkylene glycol mono(meth)acrylate type monomer, (B) 5 to 94.9 mol % of a sulfoalkyl (meth)acrylate type monomer, (C) 5 to 94.9 mol % of an unsaturated carboxylic acid type monomer, and (D) 0 to 20 mol % of other monomer (providing that the total amount of the monomers is 100 mol %) and/or a salt of the water-soluble copolymer and (2) an aqueous carbonaceous solid slurry composition, which comprises 100 parts by weight of as carbonaceous solid and 0.01 to 5 parts by weight of the aforementioned dispersant.

Abstract: The present invention relates to a process for preparing a coal-water slurry comprising the steps of screening coal into a coarse-grained coal and a fine-grained coal; subjecting said coarse-grained coal to gravity classification to classify into a low ash coal, a middle ash coal and a high ash coal; wet grinding a mixture of the fine-grained coal, the middle ash coal and part of the low ash coal, and subjecting same to flotation; preparing a first slurry having a solid concentration of 40-60 wt. % from the low ash froth resultant from flotation; and mixing another part of the low ash coal with this first slurry and wet grinding this mixture. This process can accord the solid concentration of the product slurry with an optional target value by adjusting the amount of the low ash coal mixed with the first slurry, and can use the remaining low ash coal not to be added to the first slurry for the purpose of preparing the second product slurry.

Abstract: A high-concentration coal-water slurry of a coal concentration as high as 71 percent by weight at a viscosity of 2,000 cp (at 25.degree. C.) can be produced by first coarsely crushing a starting coal, further pulverizing 95 to 30 percent by weight of the coarsely crushed thus obtained, subjecting the finely pulverized coal thus obtained, together with the remainder of the coarsely crushed coal, to crushing in a wet-type crusher, and pulverizing and adjusting the coal particles to a particle size constitution of 20 to 30 percent by weight of 200-mesh size and larger and 80 percent by weight or less of 350-mesh size and smaller.

Abstract: This process, which comprises subjecting coal to gravity classification to classify into a low ash coal, a middle ash coal and a high ash coal; deashing the middle ash coal by flotation; and using the deashed middle ash coal together with the low ash coal as the materials for producing a coal-water slurry, provides a low ash content and high solid content coal-water slurry in a high coal recovery as well as economically. This coal-water slurry is able to handle, store and burn as are fuel oils.

Abstract: High concentrated coal-water slurry is produced by coarsely crushing coal, thereafter pulverizing the coarsely crushed coal, together with water and a slurry dispersant, according to necessity, in a wet-type ball mill, and feeding back one portion of the finely pulverized coal slurry thus obtained into the inlet of the wet-type ball mill.