Rotary Furnace

Rotary furnaces are batch furnaces that generally utilize oxy-fuel burners and limit the volume of off-gases. The rotary furnace design gives high utilization of the input energy compared with the stationary furnace; they are very flexible and can accept a wide variety of feed materials. Since it is a batch furnace, the components of the furnace charge can be easily calculated on a weight or volume basis. The furnace can be operated by relatively unskilled workers who charge a batch into the furnace, smelt it for a given time period (4–6 h) and tap the furnace bullion and slag. The slag utilized by most of the rotary furnaces is FeS–Na₂S matte. Iron is added as a reducing agent along with coke and produces an oxide slag-matte combination.