Preparation and characterization of CaO-Al2O3-SiO2 glass-ceramics from molybdenum tailings

Molybdenum tailings (MTs) are by-products of the molybdenum mining industry, and further treatment are necessary before their disposal for avoiding contamination of the environment, such as landfills, plant covers, or using material productions. Here, MTs were blended with other chemical raw materials to manufacture a decorative glass-ceramic of CaO-Al2O3-SiO2 by sintering processes. The effects of Fe3O4 and TiO2 oxides in MTs on the melting and crystallization behavior of the glasses were investigated by DSC, XRD, FESEM, FTIR, and TEM. The results showed that the crystallization temperature (Tc) and crystallization activation energy (E) of the glasses decreased when the amount of MTs increased from 41 to 49 wt% (M1-M5). Wollastonite (CaSiO3) and catena-silicate (Ca2.87Fe0.13(SiO3)3), which constituted as the major and minor crystalline phases, were precipitated in the prepared glass-ceramic. In the five specimens tested, the crystalline phases were evenly distributed throughout the surface and sufficiently interlocked together. This one step sintering process, in which the glass ceramic was nucleated and crystallized at 1110 °C for 2 h, generated a material with an appearance suitable for building decoration.