The inside of the Flash Concentrator Furnace (FC) 151
It is in the FC furnace that the matte produced by the FS furnace is concentrated into blister copper over 99.8% pure. The surface of the molten bath can be seen on the lower half of the image. The settler roof is the diagonal section in the middle while the top shows a portion of the large round reaction shaft connecting to the furnace roof. On both the FS and FC furnaces it is in the reaction shaft that the granulated feed material is introduced into the furnace along with draft (air flow) from 3 stories up and heated (smelted) to a molten state before it hits the bath. The vertical shafts of light are high intensity natural gas flames (manage burners) being injected into the furnace simply to maintain the heat levels produced in the reaction shaft and control the buildup of solid materials. There is another shaft called the uptake shaft behind this one on the north end of the furnace in which the hot draft is taken up and passed through large boilers to produce steam that is sent to the power plant to generate a great deal of the smelter's electricity. Both the FS and the FC furnaces have a reaction shaft, an uptake shaft and a boiler.