THE PERFORMANCE OF HIGH QUALITY MAGNESIA RAW MATERIALS IN CEMENT APPLICATIONS

In terms of this contribution synthetic as well as natural dead burned magnesia raw materials have been investigated with respect to their performance for high temperature applications, such as refractory materials in the critical high temperature zones of cement rotary kilns. The raw materials have been grinded to the same fine grain sizes in order to compare the reactivity as a function of the grain size. Subsequently the fine powders have then been pressed to test samples in order to identify their thermo mechanical and chemical performance. The first experiments include high temperature mechanical properties such as, hot bending strength, high temperature Young's modulus of elasticity etc. Thermal shock tests in air and water were performed, and the thermal shock behavior was evaluated as a function of residual Young's modulus of elasticity at room temperature. The chemical stability of the materials was examined via the disc approach by measuring the change of the diameter of the disc samples as a function of temperature and in the presence of different corrosive slag agents. The specific micro-structure as well as the distribution of the impurities is responsible for the different kind of performance of the various DBM raw materials. Nedmag material presents very good mechanical, thermal and chemical properties, especially for severe conditions in cement kiln applying alternative fuels but also in metallurgical applications.