Mechanochemical processing of ZrSiO4

Abstract

The mechanochemical processing of the mineral zircon (ZrSiO4) is investigated with a view to exchanging the zirconium for other metals, leading to an easily extracted zirconia (ZrO2) phase. Room-temperature ball milling of zircon with calcium and magnesium in dry conditions, and with calcium hydroxide and sodium hydroxide in wet conditions, is examined. X-ray powder diffraction, scanning electron microscopy and differential thermal analysis were employed in analysis of as-milled and annealed powders. The effects of milling time and subsequent heat treatment on structure and morphology are reported. The results indicate that mechanochemical processing significantly increases the reactivity of zircon towards reducing metals. No immediate exchange reaction was found for as-milled powders, but after annealing at 1000 °C all samples showed partial or complete decomposition of ZrSiO4 resulting in multiphase systems. In these systems the major crystalline products were identified as ZrO2 or CaZrO3. Show more