Correlation between milling time, particle size for stabilizing rheological parameters of clay suspensions in ceramic tiles manufacture

Several parameters governed the rheological properties as well as the nature of the constituents, to the process of implementation. One of the major solution is to master the milling time which is responsible for the fineness of the grains, which in turn, conditioned the correct handling of the sintering mechanism, and allows highlight of the correlation between the size of the powders and the rheological properties. The introduction of a powder in a liquid induces changes in the interface of the solid phase when it passes from the vapor phase, to the liquid phase. To improve this understanding, we studied the influence of these parameters on the good dispersion of particles and more particularly the grain size. To do this, four mixtures composed of clay, kaolin, feldspar and sand were considered. The difference between each mixture, is the substitution of kaolin by feldspar with a decreased of kaolin (8%) compared to the initial rate. Each mixture was to undergo three grinding duration (-1 h, 30 min, 1 h and 2 h). The analysis of the rheological properties allowed us to note that the best flow was obtained with mixtures C3, C4, C5, corresponding to a grinding duration of 1 h 30 min. We also observed a clear correlation between the grinding time and viscosity. After drying of the suspensions, the powders obtained are grounded according to three types of particle sizes (0.25 - 1 and 1.25 mm) then pressed in the form of ceramic tiles physical-mechanical, analyses were performed on the cooked products. After optimization and comparative study between the different mixtures, it was found that the M3 mixture, with grain size of 1.25 mm provides the best products. The measured values are in agreement with the requirements of manufacturing standards and offer a higher mechanical strength to the tiles manufactured industrially.   Key words: Grinding, powder, stability, rheological parameters, ceramic tiles.