A Kinetic Analysis of Acid Leaching of Niobium and Zirconium from Titania Waste Residue Stream: An Energy Efficient Methodology for the Reclamation of Metal Values

Residues from rutile chlorination plants often contain relatively high concentrations of critical metals, essential for energy devices. Ironically, the conventional method of extraction of niobium and zirconium is quite energy demanding and detrimental to the environment. In this investigation, the kinetics of dissolution of niobium and zirconium from titania waste in hydrochloric acid solutions are investigated. The thermodynamic stability of minerals demands the use of chlorination, carbothermic reduction or alkaline fusion for breakdown of their mineral concentrate and upgrading before leaching in acid, usually hydrofluoric acid. Reclamation of niobium and zirconium values from titania waste presents an opportunity for a low energy process to be utilised. The effects of parameters leaching temperature (25 - 90 oC), acid concentration (0.5 - 2.5M), stirring speed and solid-to-liquid ratio were determined in the experiments. Leachates were analysed by ICP OES, using which the models for the leaching processes and activation energies were determined.