QUANTITATIVE-DETERMINATION OF PYRITE IN, CERAMIC CLAY RAW-MATERIALS BY DTA

The thermal oxidative decomposition in air of 0-1.5 wt% of pyrite adde d to two traditional powdered clays was investigated by non-isothermal DTA. It emerged that the first step of the exothermic oxidation of py rite, in the 350-500 degrees C range, partly overlapped the endothermi c dehydroxylation of clay minerals, centred at 590 degrees C, and the result was dependent on the pyrite contents. Based on the values of th e area of the oxidative peak and of the corresponding oxidation heat, it is possible to calculate quantitatively the amount of pyrite presen t in the industrial clay bodies and therefore to inform the technician s of the factories so they can avoid the negative effects of reducing reactions that could occur during firing of ceramic raw materials.