Since the birth of precalcining kiln in the early 1970s, it has gone through four stages of development. (1) The first stage. Early to mid 1970s. It is the birth and development stage of pre-decomposition technology.316L stainless steel vacuum brazing process In 1964, the German Dottenhausen cement plant used oil shale containing combustible components as a component of cement raw materials. In order to avoid premature volatilization of combustible components in the low-temperature part, they fed oil-bearing shale raw meal in the middle of the suspension preheater to increase the decomposition rate of raw meal entering the kiln, Vacuum heat treatment of aluminum alloy die castingscreating a precedent for pre-decomposition technology. But the precalciner kiln that really uses advanced fuel as the second heat source in the calciner started in 1971. Therefore, the birth of precalciner kiln should be the first SF kiln (Suspension Preheater-Flash Furnacel) jointly developed by Japan IHI Company and Chichibu Cement Company. MIM degreasing and sintering for ceramic hard alloyAfter the birth of the first SF kiln, various types of precalciner kilns appeared one after another in Japan (MFC furnace of Mitsubishi Corporation - 1971; RSP furnace of Onoda Cement Company - 1972; KSV furnace jointly developed by Kawasaki and Ube Cement Company - 1974 year, etc.). All calciners use heavy oil as fuel.Vacuum Oil Quenching for steel hardening heat treatment