Patent ID: 7828548

Claim:
A process for reducing metallic oxide or sulfide materials in a rotary kiln comprising a cylindrical shell having a material inlet end and a material outlet end, said process comprising a) inserting the materials into the inlet end of a kiln and moving such materials from the inlet end through the kiln toward the outlet end; b) introducing a reducing medium into the kiln, said reducing medium coming into contact with the materials as they move through the interior of the kiln; c) heating the materials in said reducing medium as they travel through the kiln at a temperature sufficient to reduce at least some of the materials to free metal product, said materials moving through said reducing medium in a direction countercurrent to the direction of the flow of the reducing medium through the kiln; and d) discharging materials from the kiln through an opening in the kiln shell at a first discharge point in the kiln which is, with reference to the direction of movement of the materials through the kiln from the inlet end toward the outlet end, located within the kiln at any point from where the temperature within the kiln begins to be greater than the temperature at the outlet end up to and including the point at which the temperature within the kiln is at its maximum, said discharge point being axially removed from the material outlet end.