The plot thickens

By Tony Kaye - CSIRO Process magazine
The global surge in commodity prices, fuelled by massive demand from China and other countries, has cemented Australia "s position as one of the world"s leading mining nations.

However, as well as having the raw resources to meet demand, Australia 's mining industry is at the leading edge of technology to maximise the efficiency and throughput of its operations.

A major AMIRA research program into the thickening process used to separate minerals from ore slurry has already produced benefits worth hundreds of millions of dollars.
Through the Parker Centre, CSIRO has been working closely with industry to enhance processes in the thickener stage through novel modelling and experimental approaches, as part of the AMIRA P266 Improving Thickener Technology project.

One powerful tool is computational fluid dynamics (CFD), which uses advanced computer software to model the flow of fluids through a minerals processing facility. This allows variations in physical design and operational parameters to be tested to achieve the best possible performance.

CSIRO Minerals research scientist Dr Tuan Nguyen says that since the project began in the late 1980s, the mining industry has achieved efficiency gains worth an estimated $295 million (net present value - NPV). In the longer term, gains are expected to exceed $500 million (NPV).

The team has successfully investigated ways of improving the performance of more than 100 thickeners, working with mining companies to achieve higher throughput, greater operational stability, enhanced overflow clarity, higher density in their underflows and lower flocculant consumption.

"Our work involves developing tools and knowledge to improve thickener performance for sponsoring companies," Tuan Nguyen says.

"In the core research program, we do a lot of basic research developing tools like CFD models of key thickening processes. We use these tools to help companies with thickener problems."

Working on one-to-one projects with sponsoring companies, Dr Tuan Nguyen says CFD, coupled with experimental measures, has resulted in better solids dispersion, enhanced mixing and flocculation conditions, more even solids discharge, reduced flocculant use, greater operational stability, savings in water use, improved mill uptime, reductions in tailings, increased tails viscosity and improvements in overall tailings storage capacity.
The current phase of research, P266E, is supported by 20 Australian and international companies, including mineral processing operators from most commodity sectors, equipment manufacturers and chemical suppliers.

The overall vision is to enhance full-scale thickener performance and downstream processes by refining and expanding concepts and applying skills to new thickener technology issues.
"We've been looking at thickeners all across the minerals industry, covering sectors such as alumina, base metals, gold and minerals sands," Dr Tuan Nguyen says. "Wherever thickeners are used, we can help.

"CFD is a very common tool nowadays and a lot of people are trying to do the same thing. But our advantage is the multidisciplinary team we have, comprising chemists, engineers and fluid dynamicists.

"Essentially, we can get the chemical data from our experimental work and put that into our CFD models. Our models are based on realistic systems - that's why we are leading the world."