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 degrees C in an indirect way using the thermal energy fr om the gases effusion 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 indices a step-wise condensation and recovery of the different substances. The main operating cost of the finance 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.