AQW Inc. actively supports education and research on all aspects of alumina refining for the benefit of the industry, the global environment and the communities in which it operates.
An excellent introduction to refining technology can be found in 'Bauxite to Alumina: the Bayer Process' by Tony Bagshaw.
AQW is currently sponsoring the following PhD students:
José Gomes, Curtin University
Born in Brazil, José started his studies at the Institute of Physics of the University of São Paulo. After moving to Perth, he finished his BSc in Physics at Curtin University. He then undertook a Master of Chemical Engineering at Curtin with a thesis entitled “The Effects of Crystal Growth Modifiers on Bayer Precipitation” under the supervision of A/Prof. Hari Vuthaluru from Curtin, and Dr Tian Li and Dr Iztok Livk in the Alumina Group at CSIRO - Mineral Resources, with support from Alcoa.
In 2018 José was awarded an AQW Inc. scholarship for a PhD study aimed at improving environmental outcomes for bauxite residues through deeper understanding of the reaction pathways and controlling factors in the formation and leaching of aluminosilicates. The project will be jointly supervised by Dr Franca Jones (Curtin) and Dr Peter Smith (CSIRO).
PhD Title: Composition and leaching of aluminosilicates formed in caustic solutions.
Start Date: May 2018
Much of the alkalinity in bauxite residues is bounded within solid sodium aluminosilicates that are found in the bauxite ores turning the residue an environmentally hazardous material. Over time these materials leach alkalinity which can contaminate surrounding soil, surface water and ground water affecting land rehabilitation and the re-use.
José’s work aims to attack this problem at the source, by examining the mechanisms of formation and ways of controlling the presence of aluminosilicates in the desilication stage to achieve improved environmental outcomes for bauxite residue storage. He will study the factors that control the crystalline vs. amorphous nature of the silicates formed in residue, and their chemical compositions, particularly the proportions of Na, Si and Al. Of particular interest will be the reaction pathways in the formation of aluminosilicates from caustic soda under real-life industrial conditions and the effects of some organic and inorganic impurities on the formation of DSPs.
John Vogrin, The University of Queensland
John Vogrin is a PhD student in the School of Chemical Engineering at the University of Queensland. He completed his Bachelor’s degree in Chemical and Metallurgical Engineering also at the University of Queensland graduating with first class honours in 2015. He worked in the UQ hydrometallurgy group as a research assistant before starting his PhD. His previous experience also includes engineering process design at Hatch. John’s research aims to generate fundamental characterisation and solubility data for synthesised desilication products. This data will feed into the development of a robust thermodynamic model. John is sponsored by the Alumina Quality Workshop.
PhD title: Desilication product characterisation and chemical thermodynamic solubility model
Start date: 3rd of January, 2017
Impurities in Bayer liquor can have a deleterious effect on gibbsite crystallisation in terms of compromising product purity, size and strength specifications or by slowing down precipitation thereby decreasing refinery productivity. The aim of this project is to provide a deep fundamental understanding of these effects by studying the gibbsite crystallisation at the atomic, micro and macroscopic scales from which a pathway to mitigating these issues can be identified.
Impurity issues are that silica and calcium levels in hydrate compromise alumina purity, and calcium is also known to supress gibbsite nucleation. The specific mechanisms for this, e.g. isomorphous substitution; surface adsorption and over growth; precipitation and/or particulate impurity agglomeration are not well established. Understanding how these impurity effects occur is a first step in developing cost effective and robust mitigation strategies.
The project will develop new research capabilities building on the recent research from the UQ RT Bauxite & Alumina Technology Centre by Fu et al (2016) which describes an experimental technique and baseline conditions for studying gibbsite crystallisation in high ionic strength alkaline solution using atomic force microscopy. From these studies, a description of the growth mechanism for gibbsite was established. This sensitive technique will show how changes in the crystallisation mechanism occur as a function of aqueous phase impurities.
At the microscopic level, scanning electron microscopy optical microscopy and x-ray photoelectron spectroscopy will be used for ex-situ analysis of particle size, shape, internal and external morphology and surface chemistry respectively. This will allow us to comprehensively map the impurity distribution – i.e. do impurities accumulate at grain boundaries, as discrete crystals in the hydrate agglomerate, or dispersed through the hydrate crystal. The particle images will be analysed to quantify how gibbsite growth habit and particle morphology is affected by the impurities.
Macroscopic studies will measure the particle size distribution in batch and supersaturation controlled gibbsite crystallisation experiments using the in-situ focussed beam reflective measurement probe and ex-situ using the Accusizer particle counter. Particle population balance models will be used to deconvolute the specific impurity effects. Samples of crystallised gibbsite will be dissolved and assayed using ICP-OES to determine the impurity content. Macroscopic growth effects will also be studied by time lapse photography/in-situ optical microscopy using a heated flow-through cell (Fu & Vaughan 2014). Finally, hydrate particle strength will be measured using a single impact breakage test.
The outcome of the study will be a new understanding of impurity effects on gibbsite crystallisation which will assist refineries to meet product specifications and provide insight into gibbsite growth, one of the slowest industrial crystallisation reactions. Further, the methods and capability developed in this project for silica and calcium would provide a platform for future investigation of other impurities.