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: A cutting structure, for a rotary drill bit, is of the kind comprising a preform cutting element having a front cutting face formed of superhard material, such as polycrystalline diamond, and a rear face bonded to a carrier of less hard material, such as cemented tungsten carbide. The cutting element is bonded to the carrier by means of an alloy having the following composition:Ni about 30% to about 60%Pd about 30% to about 62%Si about 3% to about 15%wherein % is weight percent.An alternative alloy has the following composition:Cr about 4% to about 10%Fe about 1% to about 5%Si about 2% to about 7%C about 0.01% to about 0.10%B about 2% to about 5%Ni Balancewherein % is weight percent.