Design of a furnace for refining copper prior to fusion

The design of a furnace for the removal of copper impurities prior to smelting is presented here. Impurities such as arsenic, antimony, bismuth, lead, and zinc are removed by heating the concentrate below 1000°C in an indirect way using the thermal energy from the gases of fusion and conversion. The concentrate heats up while sliding down along a hermetically sealed vacuum tunnel. After passing through filters, the volatilized substances are conducted along a tunnel with a decreasing temperature profile which induces a step-wise condensation and recovery of the different substances. The main operating cost of the furnace is due to the electric energy required by the vacuum pumps and the liquid air condensers. This cost turns out to be very small as compared to the overall operating cost of the smelter.