| 摘要 |
A process for substantially reducing the amount of insoluble fluoride-forming species in a coal feed material comprising slurrying a coal feed with a fluoride acid in the presence of an amount of fluoride-complexing species at least equal to the amount necessary to form tightly-bound complex ions with substantially all free-fluoride-ions in the slurry to produce a leached coal product and a spent leach liquor, and separating the leached coal product from the spent leach liquor. The process produces a clean purified fuel with ash content of less than about 5%, and preferably less than about 1%. Loss of fluorine values by formation of insoluble fluorides is minimized. Alkali metals and alkaline earths are substantially dissolved. The process generally comprises sizing the coal to 10 mm or less, leaching the sized coal with hydrofluoric acid in the presence of a determinable amount of a fluoride-complexing species such as silicon or aluminum, separating the leached coal from the spent leach liquor, and optionally some or all of the following: (a) pre-drying or physically beneficiating feed with high moisture or high mineral matter (ash) content; (b) cleaning the leached coal by washing and/or (c) heat treatment; (d) freeing pyrite (and other heavy minerals) and coal from attached silicates and aluminosilicates and physically separating the freed pyrite; (e) subjecting the leached coal to a second strong acid leach. In the preferred processes, hydrofluoric acid is recovered for recycling.
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