The metallurgical industry generates annually huge amount of by-products and wastes in terms of slags, dust, sludge, millscale etc. In addition to these our industry also consumes a lot of energy and release a large quantity of green house gases such as CO2 and NOx. A large number of environmental technologies have been pilot tested at Swerea MEFOS in the past 20 years for the metal and energy industry. These include the long term projects for CO2-reduction and energy saving technologies, control of dioxin emission and various pyrometallurgical processes for treatment of wastes and by-products generated by the metal industry. Also MSW has been treated. The principle of efficient use of metallurgical reactors for treatment of various wastes and residue will be described and discussed. Some of the open pilot and demonstration projects carried out by Swerea MEFOS will be used as examples. These projects include • Processing slag, dust and sludge for recovery of valuable metals such as V, Cr, Ni, Mo, Pb and Zn • Recovery and efficient use of other important resources such as CaF2 and CaO from metallurgical slag and sludge • Using metallurgical reactors for energy production • Use of ASR as heat source for preheating and zinc removal of scrap. The experiences at Swerea MEFOS have shown that pilot testing is one of the most essential parts of the development of advanced green technologies for the metal industry.