Analysis of clay types and their binary systems

The objects of study were the Mali Budyshcha and Opishnia clays of two deposits in the Poltava region (Ukraine), binary systems of these clays, and ceramics based on them. It is noted that the efficiency of the practical use of these clays can be increased taking into account the peculiarities of their mineralogical composition. The features of the qualitative mineralogical composition of clays were studied by the methods of chemical, X-ray phase and thermal analysis. The amount of rock-forming minerals was determined using the new computer program «Mineral». It has been established that with an increased content of quartz in both samples, the Mali Budyshcha clay is cha-racterized by a combination of clayey rock-forming minerals – 18.8 % montmorillonite, 12.1 % kaolinite, 17.9 % feldspar and 7 % calcite. According to the intensity of characteristic diffraction peaks and the plane of the endothermic effect with a maximum at 550–575 °C, Opishnia clay is marked by a significantly higher content of kaolinite – 48.1 %. Large values of the quantitative ratio of oxides SiO2:Al2O3 and the content of alkaline earth and alkaline oxides of the RO+R2O type determine the ratio of Mali Budyshcha clay to the group of low-melting clays with a fire resistance of 1230 °C, in contrast to refractory clay (1620 °C). It has been established that in the range of maximum firing temperatures of 950–1100 °C, samples of Mali Budyshcha clay differ from Opishnia clay in changes in average density from 1.90 to 2.28 g/cm3 versus 2.00–2.09 g/cm3, a decrease in water absorption from 15.3 to 5.0 wt % versus 12.0–9.1 wt %. It is shown that the use of binary systems of the studied clays has a significant effect on the chemical and mineralogical composition, the degree of sintering, and the physical and mechanical properties of ceramics. When varying the quantitative ratio of clays from 4:1 to 1:1, the content of kaolinite changes the most – from 19.3 to 30.1 %. Аn increase in the content of kaolinite in binary systems leads to a gradual expansion of the possible temperature range of firing. At the same time, in comparison with Mali Budyshcha clay, Opishnia clay achieves a decrease in water absorption, an increase in density and strength.