Thermal behaviour of silica waste from a geothermal power station and derived silica ceramics

The silica waste originating from a geothermal power plant in Mexico was in vestigated with the aim of finding its applicability as a raw secondary mat erial for ceramics production. The thermal behaviour of the original silica waste (containing NaCl and KCI from marine brine) and of the purified sili ca was characterized by means of DTA/TG, emanation thermal analysis (ETA) a nd thermodilatometry (TD). The reactivity of the purified silica waste mixe d with CaCO3 (1.8 mass%) was characterized by means of ETA, DTA and TG. The microstructures and phase compositions of the final products prepared by h eating in air were tested by means of X-ray diffraction and of scanning ele ctron microscopy coupled with electron probe X-ray microanalysis. The therm al analysis methods allowed determination of the optimal conditions for the rmal treatment of the silica waste in order tp obtain partly sintered porou s materials for use as refractory bricks.