Preparation and Properties of Foam Glass-ceramic from Diatomite

The results of the study of raw mix preparation and foam glass-ceramics production using diatomite as a raw material were presented in the following article. A mixture of diatomite and 40% NaOH solution was subjected to heating at a constant temperature of 775 °C. Samples of foam glass-ceramic from diatomite with an average density of 290 - 580 kg/m3, compressive strength of 1.7 - 7.8 MPa and thermal conductivity of 0.08 - 0.14 W/(m·K) were obtained. The investigations have shown that the hydrothermal pretreatment of mixture at the temperature of 90 °C may lead to the acceleration of the leaching of amorphous SiO2 from diatomite. It was discovered that the resulting soluble alkali silicates promote the process of foaming during heating and reduce the average density of the obtained samples. The optimal duration of the leaching process was estimated to be 30 minutes, which corresponds to the yield of SiO2 equal to 42.5% by the weight of dry diatomite.