Improvements in the recovery processes of metal values and diphenols

摘要

Tar liquor is extracted with a weak aqueous alkaline solution, i.e. having a pH of 7-9, to obtain an aqueous extract which is then concentrated and thereafter extracted with a substantially water-immiscible organic solvent to yield a metal-value-containing aqueous phase including germanium and gallium, and a diphenolcontaining organic phase. The alkaline solution may be ammonium carbonate, sodium carbonate, or sodium bicarbonate. The p organic solvent may be butyl acetate or diethyl ether. The tar liquor may be that obtained by cooling gas below the condensation temperature, or by electrostatic precipitation from gas above the condensation temperature. Metal values specified are germanium and gallium, and the diphenol specified is catechol. Germanium may be recovered from the aqueous phase by evaporating to dryness, if desired first distilling off any organic solvent present, burning to yield an ash, and distilling the ash with hydrochloric acid to yield germanium tetrachloride. Gallium values may be recovered from the distillation residue in any known manner. The diphenol may be recovered from the organic phase by driving off the organic solvent and fractionating the residue. The residue remaining after diphenol recovery may be burned to yield an ash which is distilled with hydrochloric acid to recover any germanium values present.ALSO:Tar liquors resulting from the thermal decomposition of coal are worked up into a diphenol-containing phase and a metal-value-containing phase by extracting the liquor with a weak aqueous alkaline solution having a pH of 7-9, to obtain an aqueous extract, which is concentrated and then extracted with a substantially water-immiscible organic solvent, such as butyl acetate or diethyl ether, to yield a diphenol-containing organic phase. The alkaline solution may be of sodium or ammonium carbonate, or sodium bicarbonate. The diphenol, e.g. catechol, may be recovered from the organic phase by driving off the organic solvent and then fractionating the residue. The tar liquor may be that obtained by cooling gas to below the condensation temperature, or by electrostatic precipitation from gas above the condensation temperature.