Today’s mineral and energy industry has almost as many supermodels as the fashion business. Less glamorous to the public perhaps – and certainly less pretty – these models are nevertheless driving a quiet revolution in exploration, discovery, mine development, mineral processing and energy use that amounts to tens of billions of dollars’ worth of future economic potential.

To many, modelling remains a “black art”, the realm of computer experts, and the garbage-in/garbage-out rule still holds sway. However, as more and more information about the nature of Australia accumulates, as computers increase in power and models can be checked against reality, confidence is growing that they offer a reliable way to predict the previously unknowable and burn off the fog of uncertainty which surrounds major decisions about the future of industry and technology......cases of cutting-edge modelling from Cooperative Research Centres (CRCs) follow.....

Clever crystals
Another set of smart models with a worldwide fan club are those devised by the Parker Centre to optimise hydrometallurgical crystallisation processes. These cystallisation steps can perform a variety of important services to a hydrometallurgical processing operation such as producing a pure product or removing harmful impurities. However, they can also have a dark side, with negative impacts on the process such as scale build-up and co-precipitation of impurities.

With billions of litres of precipitating slurries sitting in process vessels in hydrometallurgical plants around Australia at this moment, it is of major commercial consequence to work out how they will behave and can be optimised. Dr Dean Ilievski, of the Parker Centre and CSIRO, says it is not a simple task given the processes are extremely complex and often display counter-intuitive behaviour.

"This is where mathematical models of the processes have been of great value, particularly as a tool for troubleshooting or creating ‘what-if’ scenarios, as it is often not possible predict a crystalliser’s response to some change by hard thinking alone. Small process changes may lead to costly surprises.“

To deal with these complex systems the Parker Centre has developed a unique capability in modelling hydrometallurgical crystallisation processes from the atomic scale, for example predicting crystal morphologies or the likelihood of impurity molecule attachment, through to the industrial scale predicting the bulk product particle size distribution in mega-litre crystallisation vessels.

Dr Ilievski’s team have developed an integrated suite of laboratory tools and sophisticated models, which combine population balance models with chemical kinetics models and fluid dynamics. These are used by the researchers to analyse in fine detail the mechanisms at work in the process. The lab results can then be combined with models of plant-scale processes to predict the yield and particle size distribution that will occur under large-scale commercial conditions.

A Parker Centre researcher measures size distributions of gibbsite (alumina trihydrate) particles.

"We have successfully applied this approach to many industrial crystallisation problems, primarily in the alumina industry. Close and regular engagement with industry has led to the development of a number of analysis tools that are now being widely used commercially, such as methods for estimating the complex kinetics of precipitation processes and methods for modelling the breakdown of alumina product particles.”

The team also offers a suite of tests that allow alumina producers to understand and predict the quality characteristics of their product. These include the ability of the particle to resist breakdown, its shape, internal structure and chemical makeup. This is proving particularly valuable in cases where alumina particles “look right” but break down more readily than they should, with adverse effects on smelter performance.

The work by the research team have generated wide interest from the world’s resource company majors – including Rio Tinto, Alcan, Alcoa, Pechiney, Glencore, CVRD and BHP Billiton, leading to more than 30 industry sponsored projects for the team.

For further information, contact
Dr Iztok Livk, tel: (08) 9334 8902, e-mail: Iztok.Livk@csiro.au.

By Julian Cribb, Senior Editor, ScienceAlert.
First published in Australia’s Mining Monthly in March 2005 as part of a longer feature titled “Supermodels of Mining” in the Cutting Edge features series.