Utilazation of zinc hydrometallurgy waste for artificial marble preparation

Abstract

Zn-waste and glass cullet were used as raw materials for producing glass-ceramics having the appearance of marble or artificial marble by non-melting and melting process. For non-melting process, glass-ceramics were prepared by sintering Zn-waste and clear cullet powder at 800℃ for 1 hour subsequently fired at 1000, 1050, and 1100℃ for 2 hours. The obtained glass-ceramics consisted of many pores and this high porosity resulted in low strength of about 29.7 MPa. In case of melting process, the mixtures of 20, 40, and 60 wt% of Zn-waste and glass cullet (clear and amber cullet) were melted at 1450℃ for 1 hour. The parent glasses were ground and pressed into a bar shape. Glass-ceramics were obtained after sintering at 750℃ and 850℃ for 2 hours. The crystalline phases were formed at 850℃. The major crystalline phases presented in glass-ceramics with clear cullet were diopside, cristobalite, and esseneite-sodian. While glass-ceramics with amber cullet, diopside, wollastonite, and cristobalite were found as the major phases. The density of glass-ceramics was between 2.41-2.83 g/cm3 and strength was 51-86.5 MPa. The maximum strength was attained for glass-ceramics contained 60 wt% of Zn-waste. Effects of sintering times on the properties of glass-ceramics were also studied. The strength of the specimen was raised from 86.5 to 96.5 MPa after sintering at 850℃ for 4 hours. Leaching toxicity of Pb, As, and Cd in the obtained glass-ceramics was in the range allowed by the US regulations. Glassceramics produced from melting and sintering process were suitable for artificial marble application and the properties were satisfied Thai Industrial Standard of marble slabs requirement.