Improving gravity thickeners

A research program in Australia delivered A$295 million in direct benefits to the minerals-processing industry over the past six years, based on an investment of about A$10 million.

The program, known as AMIRA P266, was designed to improve gravity thickeners, a key piece of equipment in the processing of minerals.

Robert La Nauze, general manager of technology with Australian miner WMC Resources, one of 27 industry sponsors underwriting the project, says the research has delivered the most significant and immediate impact of any research project in which WMC is involved. The work is being carried out under the auspices of AMIRA, an industry association based in Melbourne that manages collaborative research efforts of the minerals industry.

AMIRA commissioned the strategic technology evaluation and management partnership (STEM) to assess the benefits of the last two phases of the P266 project.

According to STEM’s Ivor Bryan, the figures cited above are conservative estimates and do not include “a whole bunch of non-financial benefits.”

John Farrow, leader of the P266 research team, says the concerted research focus on the performance of gravity thickeners has shed light on their mysterious inner workings.

WMC engineers, working with Farrow’s team, have used the computational fluid dynamics (CFD) model developed by the P266 team to improve flocculant dispersal in a thickener at its Mt. Keith nickel operation in Western Australia. This resulted in an increase in solids concentration, and substantial water savings, which in turn allowed WMC to avoid the significant capital cost of increasing flow from its water bores.

Similarly, at Olympic Dam in South Australia, the CFD model allowed WMC to improve its thickener operations to such an extent that the company avoided the capital cost of purchasing a new thickener.

“People think of thickeners as a pretty archaic technology, but there’s still much that can be done to make significant improvements,” says Farrow.

Gravity thickeners are used wherever mineral processing involves wetting the ore. Thickeners separate fine particles from the fluids, holding them in suspension to produce a thick, mineral-rich slurry (the underflow) and a clear liquid stream (the overflow).

Some thickeners are up to 100 metres in diameter and treat tens of thousands of cubic metres of suspension per day. There are about 2,000 thickeners in the operations of the Australian and international companies, which sponsor the current phase of the P266 project.

STEM consultant Ivor Bryan says the P266 analysis confirms that investing in research can yield substantial dividends. The STEM report found that for an investment of about A$10 million to date (roughly A$7 million of it from the minerals industry, and the remainder from government), the project has generated current and potential benefits of at least A$545 million.

— The preceding is from Process Magazine, a monthly publication of Australia’s Commonwealth Scientific & Industrial Research Organization.