Coal purification and electrode formation
AssigneeAluminum Company of America
InventorSubodh K. Das
Life of this patent
Estimating the term…
Abstract
A process for purification of coal comprises forming an aqueous leaching solution containing nitric and hydrofluric acid. Impurities are removed by contacting coal having a mesh size not greater than 8 (Tyler Series) with the leaching solution for a period of 15 to 120 minutes at a temperature of 20.degree. to 100.degree. C. During the contacting of coal with leaching solution, a gaseous material such as air can be bubbled therethrough to provide additional mixing action and oxidant material. Thereafter, the solution is removed and the leached coal washed with water.
Claims21
A method of removing impurites from coal comprising:
- (a) providing an aqueous leaching solution containing at least one oxidizing agent selected from the group consisting of HNO.sub.3, H.sub.2 O.sub.2 and Fe.sub.2 (SO.sub.4).sub.3, and 0.5 to 10 wt. % hydrofluoric acid, the remainder essentially water;
- (b) contacting said coal with said solution to form a slurry having a solution to coal ratio in the range of 5:1 to 20:1, said contacting time being for a period in the range of 15 to 120 minutes at a temperature in the range of 20.degree. to 100.degree. C;
- (c) mixing said slurry with a gaseous media selected from the group consisting of air, oxygen and nitrogen;
- (d) separating said coal from said solution;
- and
- (e) washing said coal with water to provide purified coal.
A method of forming carbon electrodes from impure coal comprising:
- (a) providing an aqueous leaching solution containing 2 to 25 wt. % of at least one oxidizing agent selected from the group consisting of HNO.sub.3, H.sub.2 O.sub.2 and Fe.sub.2 (SO.sub.3).sub.4, and 0.5 to 10 wt. % hydrofluoric acid, the remainder essentially water;
- (b) contacting said coal with said solution to form a slurry having a solution to coal ratio in the range of 5:1 to 20:1, said contacting time being for a period in the range of 15 to 120 minutes;
- (c) mixing said slurry with a gaseous media selected from the group consisting of air, oxygen and nitrogen;
- (d) separating said coal from said solution;
- (e) washing said coal with water to provide purified coal;
- (f) calcining said washed coal to remove volatile matter therefrom;
- (g) blending said calcined coal with a coked carbonaceous material having a particle size larger than said coal;
- (h) mixing said blend of calcined coal and carbonaceous material with pitch to provide a mix;
- and
- (i) shaping said mix to an electrode configuration by heating in a mold.
A method of forming carbon electrodes from impure coal comprising:
- (a) providing an aqueous leaching solution containing 2 to 25 wt. % nitric acid and 0.5 to 10 wt. % hydrofluoric acid, the remainder water;
- (b) contacting said coal having a particle size not greater than 14 mesh (Tyler Series) with said solution to form a slurry having solution to coal ratio in the range of 5:1 to 20:1, said contacting being for a time period in the range of 45 to 90 minutes at a temperature in the range of 60.degree. to 100.degree. C;
- (c) mixing said slurry with air;
- (d) separating said coal from said solution;
- (e) washing said coal with demineralized water at a temperature not greater than 100.degree. C;
- (f) calcining said washed coal at a temperature of 500.degree. to 1300.degree. C for a period of 1/2 to 20 hours to remove volatile matter therefrom;
- (g) blending said calcined coal with a carbonaceous material having a particle size greater than 14 mesh (Tyler Series) to provide a blend having 25 to 45 wt. % carbonaceous material and 55 to 75 wt. % calcined coal;
- (h) mixing said blend of calcined coal and said carbonaceous material with pitch to provide a mix containing 10 to 30 wt. % pitch;
- and
- (i) shaping said mix to an electrode configuration by heating in a mold.
Dependencies are inferred from the claim text.