Patent ID: 7901644

Claim:
A process for extracting and recovering alkali metal from a char, the char comprising (i) one or more soluble alkali metal compounds and (ii) insoluble matter comprising one or more insoluble alkali metal compounds, the process comprising the steps of: (a) providing the char at an elevated temperature ranging from 50° C. to about 600° C.; (b) quenching the char in an aqueous medium to fracture the char and form a quenched char slurry; (c) contacting the quenched char slurry with carbon dioxide under suitable pressure and temperature so as to convert at least a portion of the insoluble alkali metal compounds to one or more soluble alkali metal compounds, and produce a first leached slurry comprising the soluble alkali metal compounds and residual insoluble matter; (d) degassing the first leached slurry under suitable pressure and temperature so as to remove a substantial portion of the excess carbon dioxide and hydrogen sulfide, if present, and produce a degassed first leached slurry; (e) separating the degassed first leached slurry into a first liquid stream and a residual insoluble matter stream, the first liquid stream comprising a predominant portion of the soluble alkali metal compounds from the degassed first leached slurry, and the residual insoluble matter stream comprising residual soluble alkali metal compounds and residual insoluble alkali metal compounds; (f) recovering the first liquid stream; (g) contacting the residual insoluble matter stream with carbon dioxide under suitable pressure and temperature so as to convert at least a portion of the residual insoluble alkali metal compounds to one or more soluble alkali metal compounds, and produce a second leached slurry comprising the soluble alkali metal compounds and a final residual insoluble matter; (h) degassing the second leached slurry under suitable pressure and temperature so as to remove a substantial portion of the excess carbon dioxide and hydrogen sulfide, if present, and produce a degassed second leached slurry; (i) separating the degassed second leached slurry into a second liquid stream and a final insoluble matter stream, the second liquid stream comprising a predominant portion of the soluble alkali metal compounds from the degassed second leached slurry, and the final insoluble matter stream comprising residual soluble alkali metal compounds and residual insoluble alkali metal compounds; (j) recovering the second liquid stream; (k) washing the final insoluble matter stream with an aqueous medium to produce a first wash stream comprising substantially all of the residual soluble alkali metal compounds from the final insoluble matter stream, wherein the quenching and contacting is performed in the substantial absence of gaseous oxygen.