Zeolites and other hydrothermal alteration products of synthetic glasses
Larsen, Gerburg; Plum, Karl-Heinz; Förster, Hansgeorg
European Journal of Mineralogy Volume 3 Number 6 (1991), p. 933 - 942
published: Dec 19, 1991
manuscript accepted: Mar 20, 1991
manuscript received: Mar 14, 1990
ArtNo. ESP147050306002, Price: 29.00 €
Abstract Experimental studies on the hydrothermal alteration of commercial insulation glasses were performed with special reference to applications using glass wool, basalt wool, diabase wool, and textile glass as starting materials. For comparison, glass powders were also included in the experiments. The chemical composition of the starting materials corresponds to natural basaltic and rhyolitic glass. Deionized water was used as the reacting solution. Experimental runs were carried out under autogenous pressure between 100 and 200°C and additionally at 200°C and 2000 bar. The reaction period ranged from 2 days to 30 days. The intention was 1) to identify the mineral phases formed, 2) to investigate how and to what degree mineral formation is controlled by temperature, pressure, and the chemical composition of the starting materials, and 3) to test, whether asbestos fibers are formed during the experiments. All minerals formed by alteration under the described conditions are the result of precipitation from supersaturated solutions, which were generated by the interaction between the vitreous samples and deionized water. Mineral formation is substantially controlled by the solution/sample ratio and the chemical composition of the insulation glasses. The following crystalline reaction products were formed: analcime, smectite, tobermorite, calcite, hydrotalcite, chabazite, sepiolite, stilbite, and erionite from basalt wool ; analcime, smectite, tobermorite, erionite, hydrotalcite from diabase wool ; analcime, sepiolite, cymrite, erionite, natrolite, phillipsite, smectite, quartz, and possibly gastaldite from glass wool ; garronite and CASH (calcium aluminium silicate hydrates) from textile glass. Reaction products at 200°C and 2000 bar were hydrotalcite from basalt wool, voluminous gel-like alteration layers from diabase wool, phillipsite, sepiolite, kaolinite, CSH, cymrite, and wairakite from glass wool, and CASH from textile glass. With regard to environmental mineralogy and human health, it is important to note that asbestos fibers were not formed under given conditions.