Method of removing gangue materials from coal

Claim 1

A method of removing gangue materials from coals, including lignites, to provide high quality carbonaceous fuel and valuable byproducts comprising the steps of: a. comminuting the coal by physical impaction, screening the coal, and recycling the coal to provide particulate coal no larger than 3/8 inch particle sizes; simultaneously forming fine coal and platy gangue particles of about 1-20 micron particle size; b. drying said particulate coal by an updraft of hot gases that entrains said particulate coal, heats it to an elevated temperature and carries it overhead; c. separating the hot dried particulate coal and taking the hot gases and the fine coal and platy gangue material as overhead; d. separating from the overhead the fine coal and platy gangue materials for a fuel for generating the hot gas for said drying of step b; e. storing the hot dried coal at its elevated temperature; f. admixing said hot dried coal at its elevated temperature in an enclosed vessel with a cooler alcohol containing 1-4 carbon atoms, inclusive, to provide the thermal shock; and comminuting in said closed vessel; g. withdrawing and additionally comminuting said coal particles in the alcohol slurry to sizes having a majority of particles of minus 100 micron size; h. separating said slurry of comminuted said particles by settling velocity methods into an overflow containing the fine high quality carbon and sending it to storage; and into an underflow containing high settling velocity gangue materials that are in thickened slurry with fluid containing some low settling velocity particles; i. diluting the underflow of coarse high density coal and gangue materials with said alcohol; j. selectively comminuting to breakdown the coarse coal with relatively little breakage of the gangue material, which is more durable than said coal; k. separating the particles from step j. into an overflow containing the high quality carbon product that can be sent to storage; and an underflow of unwanted gangue materials containing 10-50 percent by weight of said coal and said alcohol; and l. recovering said alcohol from the admixture of the unwanted gangue materials and the coal.

Claim 2

A method of removing gangue materials from coals, including lignites, to provide high quality carbonaceous fuel and valuable byproducts comprising the steps of: a. comminuting the coal by physical impaction, screening the coal, and recycling the coal to provide particulate coal no larger than 3/8 inch particle sizes; simultaneously forming fine coal and platy gangue particles of about 1-20 micron particle size; b. drying said particulate coal by an updraft of hot gases that entrains said particulate coal, heats it to an elevated temperature and carries it overhead; c. separating the hot dried particulate coal and taking the hot gases and the fine coal and platy gangue material as overhead; d. separating from the overhead the fine coal and platy gangue materials for a fuel for generating the hot gas for said drying of step b; e. storing the hot dried coal at its elevated temperature; f. admixing said hot dried coal at its elevated temperature in an enclosed vessel with a cooler alcohol containing 1-4 carbon atoms, inclusive, to provide the thermal shock; and comminuting in said closed vessel; g. withdrawing and additionally comminuting said coal particles in the alcohol slurry to sizes having a majority of particles of minus 100 micron size; h. separating said slurry of comminuted said particles by settling velocity methods into an overflow containing the fine high quality carbon and sending it to storage; and into an underflow containing high settling velocity gangue materials that are in thickened slurry with fluid containing some low settling velocity particles; i. diluting the underflow of coarse high density coal and gangue materials with said alcohol; j. selectively comminuting to breakdown the coarse coal with relatively little breakage of the gangue material, which is more durable than said coal; k. separating the particles from step j. into an overflow containing the high quality carbon product that can be sent to storage; and an underflow of unwanted gangue materials containing 10-50 percent by weight of said coal and said alcohol; and l. recovering said alcohol from the admixture of the unwanted gangue materials and the coal.

Claim 9

A method of removing gangue materials from coals, including lignite, to provide high quality carbonaceous fuel and valuable by-products comprising the steps of: a. comminuting and screening the coal and gangue materials until the particles are all smaller than 100 microns; forming gangue particles of greater sphericity and density than the coal particles; b. forming a slurry of the -100 micron particles of coal and gangue material in alcohol having 1-4 carbon atoms, inclusive; c. separating by settling velocity separation the gangue materials having the greater sphericity, greater density and higher settling velocity from the coal particles leaving high quality carbonaceous products; and d. recovering the alcohol from the gangue materials.

Claim 10

A method of removing gangue materials from coals, including lignite, to provide high quality carbonaceous fuel and valuable by-products comprising the steps of: a. comminuting and screening the coal and gangue materials until the particles are all smaller than 100 microns; forming gangue particles of greater sphericity and density than the coal particles; b. forming a slurry of the -100 micron particles of coal and gangue material in alcohol having 1-4 carbon atoms, inclusive; c. separating by settling velocity separation the gangue materials having the greater sphericity, greater density and higher settling velocity from the coal particles leaving high quality carbonaceous products; and d. recovering the alcohol from the gangue materials.