Crystal gazing brings potential

A MODELLING method that predicts crystal morphology and growth rates could create new processing possibilities for the minerals industry.

A modelling method that predicts crystal morphology and growth rates could create new processing possibilities for the minerals industry.

A team from the Nanochemistry Research Institute at Curtin University of Technology — a Parker CRC for Integrated Hydrometallurgy Solutions participant — is using atomic-level simulations to determine how fast molecules add to, or leave, the surface as a function of the surface environment.

Project leader Professor Julian Gale says that based on these rates, researchers can simulate morphology and crystal growth, consequently predicting crystal behaviour.

By working on different length-scales, it is possible to simultaneously reconcile the models with atomic detail, which is becoming increasingly available from in situ scanning probe microscopy and macroscopic observations, such as those provided by optical microscopy.

The research, which used urea as a model liquid, is an important first demonstration of the principles the team is developing, he says. “Crystal morphology or shape affects properties such as solubility and dissolution rates.

“It also changes how particles pack together — important for the pharmaceutical and other industries.”

Now that the team has demonstrated computer simulation is a feasible way of exploring the crystal growth process, Professor Gale says what it would like to do is the same thing for the minerals industry.

He says although the method is equally applicable to the minerals industry, it will be challenging.

“The potential benefits are the same — the method would help our understanding of how to manipulate the growth of technologically relevant materials.”

It could be used to find out ways of quickening the aluminium hydroxide crystallisation step of the Bayer process.

“If we can find out why this is particularly slow, we might be able to find a way of accelerating the growth, saving considerable expense.”

He says the converse is important in pipelines. “We want to avoid mineral formation as scale, which can block pipes. We can perhaps engineer molecular routes to slow down growth and prevent scaling.”

The team has already generated significant insights as to how barite, a common scale in oil pipelines, grows rapidly under some conditions.

This article first appeared in Process (October 2007) – a publication of CSIRO’s Minerals Resources sector.

Key contact:

Professor Julian Gale, Curtin University of Technology

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