Influence de l'ajout des oxydes sur la cinétique de transformation du kaolin

Abstract

The objective of this present work is to enhance local raw materials by synthesizing mullite from Algerian DD3 kaolin and recycled alumina. First, we studied the starting powders (kaolin and aluminum slag) to better understand the phase transformations during sintering. The results obtained show the formation of mullite. We have enriched this kaolin and these mixtures (Kaolin + Aluminum slag) prepared in stoichiometric quantity by adding deferent percentages of MgO, in order to study the influence of magnesium oxide in the formation of mullite for both cases. We sintered the various mixtures prepared between 900°C and 1400°C for 2 h. To understand microstructural transformations and chemical reactions, we performed differential thermal analysis coupled with thermogravimetric analysis (GTA/ DTA). The phase transformations during the various heat treatments were analyzed by X-ray diffraction (XRD). Shrinkage loss in mass density were measured. The results show that magnesium oxide significantly influences the amount of mullite formed; also the more the quantity of MgO increases, the more the loss in mass decreases.