The extraction of gold and Ag involves leaching the metal with

In the metallurgy of silver and gold, the leaching agents are

The technique  very useful in the refining of low melting metal like tin is

The naturally occuring chemical substances in the earth's crust obtainable by mining are called

The anodes are of impure metal and pure metal are taken as cathode. The technique used here is 

The ore is heated in regular supply of air in a furnace at a temperature below the melting point of metal is called

In the electrolytic cell for the extraction of Al, the gases formed in anode are

Heating of ores are called

Sphalerite is also called

______ is a type of gravity separation.