1220th Ordinary General Meeting

Wednesday, 2 April 2014

"The Jameson cell"

Laureate Professor Graeme Jameson AO

At the 1220th ordinary general meeting of the Society, Laureate Professor Graeme Jameson described the development of the Jameson cell, one of the most important technological contributions to the Australian economy in the last 50 years.

The Jameson cell is a flotation cell used to concentrate the valuable components on ore in minerals processing. In a typical mining operation, the first two stages of extracting minerals are the mine itself from which the ore is recovered and the concentrator, where the valuable mineral is extracted from the rest. Generally, the valuable components are no more than 2% of the ore recovered, so there is a massive challenge in isolating this from spoil for further processing. An important technology developed to achieve this concentration step was the flotation cell, a process first developed early in the 20th century.

In a flotation technology, the ore is ground up into very fine particles and dispersed with water and surfactants in a large mixing vessel that can be kept agitated and into the bottom of which compressed air can be introduced. Reagents are added to make hydrophobic the valuable mineral particles exposed during the crushing. Air is bubbled through the suspension and the hydrophobic mineral particles attach to the bubbles, float to the surface as a froth and then are skimmed off for further processing and enrichment. Because large volumes of ore have to be treated to recover a relatively small proportion of valuable product, this is a very expensive step in recovering minerals: first, the ore has to be ground to very fine particle sizes (typically around 150 micrometres) – this takes a lot of energy; and second, the volume that has to be treated in preparing the slurry is large, so processing equipment is big and expensive. Any technology that reduces either the cost of grinding or the size of the processing equipment can have a major impact on the cost of production. The Jameson cell revolutionised the floatation process by reducing the size of the equipment needed to efficiently float off the minerals.

Over a period of several years, Professor Jamieson identified the optimum parameters for particle size and the corresponding optimum size for the air bubbles used to float the treated particles. Generally, particle size needs to be less than 150 micrometres, or, even better, less than 100 micrometres. The smaller the particle, the more likely it is to consist of the pure mineral. But the real technological breakthrough was identifying that the optimum bubble size is about 300 micrometres. Until then, conventional cells operated using bubbles about three times that size at about 1 mm diameter. Having identified the optimum bubble size, the challenge was then to design equipment that produced the right amount of sheer to generate bubbles of 300 micrometres diameter . This turned out to be relatively simple, using high pressure jets of water to entrain the air.

Much of the commercialisation work was done at Mount Isa in the 1980s and 1990s. Since then, the cell has been deployed around the world and is used routinely to extract coal, copper, lead, zinc and potash and is used in other industries such as oil-sands extraction and industrial waste treatment. The over 300 cells have been installed and the cumulative value created by this invention is more than $25 billion.

Professor Jameson was named NSW Scientist of the Year in 2013.

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