Effect of physicochemical characteristics on the use of clays from Kindia (Guinea) in ceramic compositions

To evaluate their potential uses in ceramic compositions, two different types of abundant clays from Kindia (Guinea Conakry), denoted ABD and ARD, were characterized with the chemical and mineralogical compositions, the specific surface area, the plasticity index, the particle size distribution, and the thermal behavior. Kaolinite and muscovite are the main clay minerals that are identified. Besides, non‐plastic minerals are large amount of quartz with a small particles size, goethite, hematite, anatase, and a small quantity of gibbsite. The two clays have a high plasticity index that is consistent with the small particle size and the broad size distribution. During heating, the fluxing behavior of the two clays induces a significant densification that is favored by the muscovite mineral combined with the reactive fine quartz. Besides, the firing shrinkage is limited to values of 4.5% and 3.5% for ABD and ARD respectively. In the objective of manufacturing ceramics, the two clays present the required properties. They present a sufficient plastic index in the green state, and after firing they lead to dense ceramics with an interesting bright color. The limited firing shrinkage is favorable to maintain the dimensional stability of vitrified ceramics as porcelain.