MINERALOGICAL AND INDUSTRIAL ASSESSMENT OF CLAY FROM PARTS OF THE FOLDED ZONE IN KURDISTAN REGION FOR CERAMIC PRODUCTION
Clays are used in the ceramic industries largely because of their contribution to the molding and drying properties of the wares being produced; many clays, such as kaolinite and red clays, are used because of favorable behavior during firing or because they produce favorable properties in fired ware. To assure the most effective use of a clay, the ceramic technologist must meet the problems of purification, the improvement of the working properties of clays through additions of non-plastic materials or chemicals and their behavior during firing. Therefore this study addresses the problems of some clay deposits from parts of the folded zone in Kurdistan Region for ceramic industry. X-ray diffraction is used to establish the mineralogical composition. It is found that the main clay minerals of these samples are chlorite, smectite, mixed layer, illite, and kaolinite, in addition to the non-clay minerals such as quartz, calcite, dolomite and feldspar. The raw materials were ground and sieved; some of the raw materials were mixed in different proportions in order to prepare different mixtures. Three different mixtures were prepared using red clay sample, kaolin, granite, sandstone, and limestone. Briquettes were molded from clay alone (A) and from different mixtures (1B, 2C) using a semi-dry pressing method (10% moisture content and pressure 5.6 in/cm²) in a dimension 5 × 5 × 1 cm. The briquettes were fired at three different temperatures (1125, 1150 and 1175 °C) with at rate of heating of 30 C°/h. The evaluation tests, physical and mechanical properties as well as chemical compositions of the studied samples show that the fired briquettes made from those samples which contain considerable amount of Al2O3 and low content of CaO such as samples 1, 5 and 7 from Fatha Formation; 8 and 9 from Injana Formation give the best results for the production of floor tile, wall tile, facing tile, and clay brick industry. The results also, showed that the best mixture to adequate characteristics for ceramics industry are mixture 2C fired at 1175 °C.