Imaging a crystal growing and changing, atom by atom, in its solution are among the world leading achievements of the Parker Centre’s crystallisation research team.

Growing desirable crystals - and not growing undesirable crystals - are vital to a wide range of mineral, chemical, power and other heavy industries – including major commodities such as gold, alumina, copper, zinc, nickel and uranium.

Despite the fact that humans have been using crystallisation for three or four thousand years to extract various minerals, the processes by which atoms move out of solution and form an ordered lattice structure that becomes a crystal remain mysterious in many aspects.

Associate Professor Mark Ogden and his team in the AJ Parker CRC for Hydrometallurgy are investigating the energetics of how atoms bind to the surface of a growing crystal, shedding new light on this process in order to boost the competitive edge of a wide array of extractive, processing and energy industries.

Whether it is obtaining a purer mineral product from a solution or preventing scale build-up in a cooling pipe, the answers lie with the behaviour of individual atoms – and whether this behaviour is encouraged or discouraged by various impurities or additives, he explains.

The team uses an atomic force microscope, in which a minuscule tip run across the surface of the growing crystal, thereby creating an image of its topography as it grows and changes, with such exquisite resolution that it allows individual atoms to be ‘seen’.

Doing this they can not only study the process of crystal formation and growth in the actual solution, but also precisely what happens when they add an inhibitor designed to discourage crystal growth (such as scale in pipes), Professor Ogden says.

The information is then used to refine what is believed to be the world’s most powerful computer model of the process of crystallisation. This is used to predict what will happen to crystal formation in the presence of various impurities and inhibitors, including the shape of the crystals formed (significant in various flows or filtration or processes).

"Every hydrometallurgical process has some form of crystallisation – wanted or unwanted – taking place. Our aim is to optimise the desirable and prevent or minimise the undesirable forms,” he says, adding “The Holy Grail is to develop a method for accelerating crystallisation.”

Of almost equivalent importance to the power sector and any major processor is preventing the build-up of unwanted scale deposits which cause downtime, financial losses and can pose safety threats. The team is testing new inhibitors for barium sulfate, a common scale, which appear to slow crystal growth and change its shape, and plans then to test the best on gypsum and calcite. Another team is looking at ways to control scale build-up through pipe design and flow.

Across the minerals, chemical and manufacturing industries, market pressures are pushing manufacturers to increase productivity in their crystallistion processes, while maintaining or improving quality (purity, phase, particle size and shape).

The Parker Centre's Crystallisation Program is laying the ground for an Australian world-lead in this field, as well as generating ideas that will form the basis of new industrial processes. At the same time, the program is undertaking a range of industry-funded crystallisation projects. Its overall objective is to make both technology and skills available to Australian industry to improve its productivity and international competitiveness.

For further information, contact
Associate Professor Mark Ogden, tel: (08) 9266 2483, e-mail: M.Ogden@curtin.edu.au.

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