Recycling of zinc-hydrometallurgy wastes in glass and glass ceramic materials

The aim of Brite-Euram project CT94 -1018 has been to recycle jarosite (JW), an iron rich hazardous waste resulting from the hydrometallurgy of zinc ores, to obtain glass and glass-ceramic materials. Granite scraps and mud (GW), generated by the caving, cutting and sawing of the blocks, and glass cullet have been utilized as additives to define the batch composition. The average compositional ranges are 40–70% for JW, 20–40% for GW and 10–40% for glass-cullet. Several compositions were prepared and tailored for the final product destination; melted at the 1400–1450°C temperature range. Glass-ceramic materials have been obtained from the glassy-phase by means of a controlled nucleation and crystallization thermal treatment, yielding a 40–55% crystalline volume fraction. The properties of the glass and glass-ceramics have been tailored to favor the commercial exploitation of the products in the building industry, in the form of paving tiles wall covering panels, glass fibers for insulation and coloring pigments for ceramics. A 1 ton/day vitrification pilot plant, able to work in a continuous or discontinuous way, has been realized and tested using different waste streams.