| 摘要 |
PCT No. PCT/AU87/00080 Sec. 371 Date Sep. 19, 1988 Sec. 102(e) Date Sep. 19, 1988 PCT Filed Mar. 23, 1987 PCT Pub. No. WO87/05621 PCT Pub. Date Sep. 24, 1987.The invention concerns a process for the preparation of demineralized coal, comprising the steps of: (a) forming a slurry of coal particles, preferably at least 50% by weight of which particles have a maximum dimension of at least 0.5 mm, with an aqueous solution of an alkali, which solution has an alkali content of from 5 to 30% by weight, such that the slurry has an alkali solution to coal ratio on a weight basis of at least 1:1; (b) maintaining the slurry at a temperature of from 150 DEG to 300 DEG C., preferably 170 DEG C. to 230 DEG C., for a period of from 2 to 20 minutes substantially under autogenous hydrothermal pressure and rapidly cooling the slurry to a temperature of less than 100 DEG C.; (c) separating the slurry into alkalized coal and a spent alkali leachant solution; (d) regenerating the alkali leachant solution for reuse in step (a) above by the addition of calcium or magnesium oxide or hydroxide thereto to precipitate minerals therefrom; (e) acidifying the alkalized coal by treatment with an aqueous solution of sulphuric or sulphurous acid to yield a slurry having a pH of from 0.5 to 1.5 and a conductivity of from 10,000 to 100,000 mu s; (f) separating the slurry into acidified coal and a spent acid leachant solution; and (g) washing the acidified coal. |
