Solar dissociation of zirconium silicate sand: A clean alternative to obtain zirconium dioxide

Abstract

Application of concentrated solar energy (CSE) in the industry of materials is a promising alternative that is developing in recent years to reduce the environmental impact while accomplishing the objective of producing high-quality products. It is important to enlarge the processes being studied with the competition of CSE to find the most attractive for the scalation up to the industrial level and thus contributing to the energy transition in the field of materials. Systematic laboratory research has been conducted within the thermal decomposition of metal carbonates, sulphates, hydroxides, and metal oxides with promising results using CSE, which has the competing advantage of heat production without releasing pollutants and the construction of the installation as principal cost. Nevertheless, the thermal decomposition of zirconium silicate (ZrSiO4), despite of the importance of zirconium dioxide in the field of ceramics and the high energy consumption in the process, has never been reported in the literature using CSE. The process proposed in this manuscript consists of two stages, the pyrometallurgical one, based on the direct application of CSE to ZrSiO4 to dissociate it into ZrO2 and SiO2, and the hydrometallurgical one, based on the aqueous extraction of the zirconium dioxide with NaOH at 200 °C for 6 h in pressure reactor. The double-stage process based on CSE leads to the synthesis of close to 95% purity monoclinic ZrO2. The energy for the pyrometallurgical route is supplied by a renewable energy source (CSE), thus contributing to reduce carbon dioxide emissions in the synthesis of ZrO2.