Abstract: A zinc- and lead-containing residue from a metallurgical plant is reprocessed by a thermal treatment in a circulating fluidized bed system. A major part of the heat demand is satisfied by a combustion of solid carbonaceous material in the fluidized bed reactor of the circulating fluidized bed system. A reducing fluidizing gas, which is virtually free of free oxygen, is fed to the lower part of the fluidized bed reactor. A solid carbon content of from 5 to 30% is adjusted in the fluidized bed in the lower portion of the fluidized bed reactor, which is supplied in its upper portion with oxygen-containing gases and in which CO.sub.2 is formed only at such a rate that zinc metal is not reoxidized. Substantially all solids are removed in a recycling cyclone from the suspension discharged from the reactor and the removed solids are recycled. The gas is cooled to a temperature at which zinc metal is oxidized to ZnO. The dust-like zinc compounds and lead compounds are removed from the gas.

Abstract: A process for the separation and recovery from an ore of a metal, or metals, particularly strategic and precious metals, notably gold. A carbon-containing, gold-bearing ore, notably a carbonaceous or carbonaceous pyritic ore, is contacted and microbially pretreated and leached with a heterotrophic microorganism, or admixture of microoganisms, at heterotrophic conditions to cultivate and grow and said microorganism, or microorganisms, and reduce the carbon content of the ore by consumption of the carbon.