Smart maths for greener mills

CSIRO has developed an Internet-based simulation tool that predicts the motion of particles inside grinding mills, providing insight into the way mills work and enabling energy savings from smarter, more energy efficient design.

webGF-Mill,as the package is known, assesses the design and function of the grinding mills used at mines to crush ore.

‘Improving mill design is important because of the amount of energy that mills use,’ says CSIRO mathematician Dave Morton. ‘Typically, grinding mills are very inefficient. An average mill around 10 metres in diameter consumes roughly the energy required to supply 10,000 average Australian households. Unfortunately, only 5% of this energy is consumed by the processes that actually break the rocks inside the mill.’

‘As well as decreasing costs for mining companies, improving mill performance has the potential to significantly reduce global consumption of fossil fuels and thus provide important environmental benefits,’ he says.

webGF-Mill, uses sophisticated simulation techniques to predict the collective motion of large numbers of particles. These methods, developed by CSIRO mathematicians, provide tools for studying the flow of granular materials such as minerals, powders and cereals. Understanding the way that granules move helps companies develop efficient methods for production, processing and transport of these materials.

webGF-Mill can be used to study three types of mills, the larger SAG (semi-autogenous grinding) and AG (autogenous grinding) mills, and the smaller ball mills.

As Australia is one of the world’s largest mineral producers, many mills are used at mine sites throughout Australia.

Typically, material is dug out of a mine as rocks up to 2m in size. Crushers break the rocks down to particles of around 200-300mm, which are then ground further in a SAG or AG mill. Oversized particles are then sent to ball mills for further crushing. Crushed material accepted from SAG, AG and ball mills is sent to flotation plants where valuable minerals are separated from the dirt for further processing.

webGF-Mill can be used to simulate a variety of different mill sizes, lifter geometries, ball and rock distributions, and fill levels.

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