Learning from Nature: Solvothermal Crystallization of Zirconium in Volcanic Ejecta and its Relevance for Technical Applications

Sanidinites from Laacher See (Eifel, Germany) and the Middle Italian Volcanic Province are ideal materials to study the solvothermal transport of Zr. Sanidinites are rare porous magmatic cumulates, found as volcanic ejecta of explosive volcanoes. The gas composition in magma chambers is comparable with that in a combustion chamber of a municipal solid waste incineration (MSWI-) plant. The aggressive gas species like Cl2, HCl and SOx, resulting from combustion of municipal waste, pose a severe problem because they attack the superheater steel-tubes in MSWI-plants. To prevent corrosion, thermally sprayed yttria-stabilized Zr-oxide layers are used. The adaption of the solvothermal treatment for densification of these ceramics is investigated. This example demonstrates that a profound knowledge of processes in natural systems, e.g. solvothermal crystal growth in volcanites, provides novel solutions for technical applications.