Abstract: A metallurgical processing system for economically recovering metal values, such as columbium, tantalum, thorium, and uranium from dilute source solids, such as digestion sludges, by a series of steps including:1) slurrying the source solids with dilute hydrofluoric acid to produce a solid phase and a liquid phase containing dissolved tantalum and columbium, then extracting tantalum and/or columbium from the liquid phase by means of a liquid ion-exchange process and then, additionally;2) roasting the solid phase with sulfuric acid to recover and recycle hydrofluoric acid, leaching the roasted solids with dilute sulfuric acid to produce a disposable solid phase and a liquid phase containing thorium and uranium, and extracting thorium and uranium from the liquid phase by means of a liquid-liquid amine extraction process.

Abstract: Disclosed is a process for dissolving tantalum and/or columbium-containing materials contaminated with alkali metal impurities. The tantalum and columbium materials are digested in a solution comprising hydrofluoric acid and a fluosilicate-containing compound. The alkali metals are reacted to form precipitated fluosilicates, which then can readily be separated.

Abstract: A process for the recovery of columbium values from a columbium-containing aqueous hydrofluoric acid solution. The columbium-containing solution is heated, with agitation, to cause evaporation and hydrolysis, resulting in the formation of a slurry from which columbium oxyfluoride can be separated and recovered.

Abstract: A process for converting columbium oxyfluoride (CbO.sub.2 F) to columbium oxide (Cb.sub.2 O.sub.5) comprising heating CbO.sub.2 F under select pyrohydrolysis conditions.