Flotation '21: Day 4 update

Thursday 11th November

Circuits and plant practice was the theme of today's presentations, which got off to a fine start with a keynote lecture from Associate Professor Kym Runge, Group Leader of the SMI-JKMRC, University Of Queensland, Australia. Kym showed how an important role of a site metallurgist is to diagnose reasons for problems in a flotation circuit and devise strategies to overcome these problems. 

Traditionally this has involved performing and analysing information from a flotation circuit survey. It is difficult to determine from this information alone definitive flotation mineral recovery mechanisms and strategies for circuit improvement. There are, however, new analytical and modelling techniques that can be used to complement traditional survey data. These techniques are able to determine the effect of mineralogy, surface chemistry and circuit design on flotation circuit recoveries and grades. They can suggest strategies for improvement which would not have been identified via a conventional circuit audit. Kym reviewed these new approaches and used an industrial example to demonstrate the type of conclusions that can be derived. 

There were 20 presentations in another long day (see programme and abstracts), seven of these by conference sponsors. The first was by Glencore Technology's Glenn Steiper, who highlighted the imperative to reduce concentrator CapEx and Opex while maintaining throughput and metallurgy. He believes that the launching of the Jameson Concentrator is a step in the right direction to address these challenges as it treats the required tonnes, but offers many significant environmental and economic advantages.

Glencore Technology celebrating the 30th Anniversary of the Jameson Cell
with Graeme Jameson at Flotation '19

Livia Faustino represented Vale Institute of Technology, Brazil at Flotation '19, but now she is Project Manager with sponsor Clariant, Brazil, and this morning described the reverse cationic flotation of silicates by adding ultrafine iron ore tailings to the conventional flotation feed.

Zeiss Microscopy is a sponsor of many MEI Conferences. Eddy Hill joined Zeiss in 2012 with a remit to develop automated analytical solutions for geoscientists and the mining Industry. He attended Process Mineralogy '12 and Process Mineralogy '14, but this was his first flotation event and in his presentation he discussed 3D Mineralogy–X-ray microscopy automated mineralogy for a flotation circuit, which was introduced only last week).

Earlier in the year we welcomed Metso Outotec as a sponsor of Sustainable Minerals '21, and although this will be the first time that the company has had the opportunity to sponsor a flotation conference since the merger of Metso and Outotec, they were regular sponsors of many MEI Conferences under the names of their individual companies. The merger was completed in July last year, forming a unique new company with leadership in sustainable minerals and metals processing and recycling technologies.  It was great to have representatives present three papers today.

Guillermo Bermudez, of Metso Outotec Canada, presented strategies to optimise and modernise existing flotation circuits; Danish Bilal, of Metso Outotec Finland discussed the effect of ore blending on flotation and prediction of metallurgical performance of blended feed in flotation by simulation; and Janne Suhonen, also from Finland showed how locked cycle test results can be predicted from kinetic flotation test data.

Canada's Woodgrove Technologies sponsored Flotation '19, but were unable to attend, so it was good to have a presentation from David Hatton, manager of flotation development at Woodgrove, who are sponsoring once again. Woodgrove’s Staged Flotation Reactors (SFR) and Direct Flotation Reactors (DFR) are low-footprint and cost-efficient flotation units that are claimed to achieve higher upgrading at similar recovery to conventional flotation cells. David described the application of a novel benchtop flotation reactor for greenfields scale-up and design of industrial SFR and DFR Circuits.

Complementing today's and tomorrow's presentations was a 2-hour live panel discussion on the future of flotation circuits and machines (posting of 9th August). Chaired by Dr. Peter Amelunxen, experienced practitioners from around the world shared their views, and took part in lively discussions initiated by conference delegates. 

It was a shame that Prof. Graeme Jameson was unable to join the panel, due to connectivity problems in Australia. I am sure he would have made a valuable contribution to the wide-ranging discussions.

It is difficult to summarise a 2-hour discussion in a few paragraphs, but it was clear that future flotation circuits are likely to be hybrids, a mix of conventional mechanical cells, which are still very effective in treating particles in the 25-200 micron range, and a new generation of alternative machines such as Hydrofloat and Novacell for coarse flotation and Concorde and Jameson cells for ultrafine recovery.

There have been many challenges over the last 40 years, feed grades now being lower than many old tailings grades, and developments have led to a remarkable increase in mechanical cell size, but it is felt that 600-700 m3 cells are probably the limiting size. 

Existing operations have been slow to adopt the new cell technologies, mainly due to the risk involved. Mechanical cells work, so there has not been a great deal of incentive to upgrade old circuits, and process control strategies have to be adapted to the new technologies.

But the innovative new cells are now being employed in new circuits, often supplementing mechanical machines for different duties. Even so many plants are having a hard time accepting equipment that they are not familiar with, and cannot be easily scaled up from laboratory test-work, as can traditional machines.

As the world strives for zero carbon emissions, effective flotation of a very wide range of particle size is of prime importance, whether this be achieved by 'universal' flotation machines or by a combination of the old and the new. It was felt that coarse particle flotation will increase in importance, as it can be regarded as an ore sorting preconcentration stage, reducing not only energy, but also water requirements.

The live panel discussion was recorded and is available on demand for the next 6 months, as are all the presentations this week, so it is not too late to register!

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@barrywills