In the research project it was investigated how the reduced viscosity of the clinker melt caused by alternative fuels influences the sintering reactions and the refractory lining in rotary kilns. It was investigated whether the typical by-products of alternative fuel ashes can lead to a sufficient degree of sintering already at lower process temperatures. In particular, the effects on the chemistry and mineralogy of clinkers and influences on the cement quality as well as on the refractory material were investigated.
For the investigations raw meal-ash mixtures were produced. In addition, various methods for determining the quantity and formation temperature of the melt were investigated. Laboratory clinkers were produced from the ash-doped mixtures in static and dynamic burning processes in order to clarify the influence of the combustion process on melt formation. The quality of the laboratory clinkers was evaluated. In order to determine the effects of the altered melt formation on the refractory lining in the rotary kiln, the coating formation and refractory corrosion were investigated in a laboratory rotary drum kiln.
A database was compiled which cement manufacturers can use to influence and further optimise the formation of the melt phase by selecting suitable alternative fuels and their proportion. Manufacturers of refractory products are provided with an improved knowledge base on the influence of the ashes of alternative fuels and the reduced operating temperature on coating formation and the durability of their products in rotary kilns.