Abstract: A low melting point solder alloy comprising effective amounts of tin, zinc and indium.

Abstract: Indium-containing feedstocks, such as flue dusts from a refining or smelting process, are treated to increase the concentration of indium and at the same time to reduce the concentrations of lead, copper, and arsenic. The flue dusts are treated in a sodium-doped lead bath at temperatures of 675.degree. to 800.degree. C. Soda ash in the amount of 15 to 35 weight percent is blended with the feed stock and added to the sodium-doped lead bullion. The sodium reacts with the dusts to form a liquid dross, which is removed, cooled, and crushed. The powdered dross is water leached to remove the sodium salts. The indium remains in the filler cake and can be processed by conventional methods for the recovery of indium. About 95% of the indium reports to the filter cake, while lead retention in the filter cake is only about 5-15% of the initial lead content in the dust. A majority of the zinc also reports to the filter cake.

Abstract: In the hydrometallurgical recovery of metal values from ores and the like in which a metal bearing source is reduced in the presence of at least one additive at temperatures ranging from about 500.degree. to about 900.degree. C. and thereafter extracted, the improvement of said process comprises pretreating a portion of process tails from a preceding run with the additive prior to the reducing roast. The additive which is used to pretreat the minor portion of the feed stock may comprise that which is recovered from the roaster offgas and admixed with a portion of the tail stream from the extraction step.