All the papers in the technical sessions, and most of the poster papers are available on flash drive from MEI Online, and selected papers from the event will be published next year in a special flotation issue of Minerals Engineering.
Monday November 18th
|With Kari Heiskanen and Dee Bradshaw|
An interesting morning session consisted of nine papers, from Australia, Chile, Poland, Sweden, South Africa and UK. The session was broken by a long coffee break, giving delegates the opportunity to view the poster displays and the exhibition booths.
|At the eDart exhibit|
|At the ACIS/REXA booth|
|Kevin Galvin (left) at the FLSmidth booth|
Due to scarcity of fresh water and stringent regulations on the quality of discharged water, more and more flotation plants have to use groundwater, sea water and recycle water with a high concentration of electrolytes. Despite a number of studies that have been conducted to investigate the effect of saline water on mineral flotation, effective ways to solve many problems encountered in mineral flotation plants using saline water are not currently available. Bo Wang of the University of Queensland, presented a review of published articles addressing the effect of saline water on the interfacial phenomena taking place in the flotation process, such as surface wettability, bubble-particle collision and attachment, mineral particle interactions and frothing. The review provided an overall picture of current status of studies in this area and showed directions of future researches addressing different problems associated with using saline water in mineral flotation.
An intensive first day of papers ended with the first 'happy hour' where delegates relaxed and discussed the day's events over drinks in the beautiful Vineyard Gardens.
It has not been surprising that Fundamentals has been dominated by academic papers, but today papers from non-academics formed a fair portion of the 16 papers presented.
|Nilce Alves in discussion with Jan Cilliers|
Chris Greet of Magotteaux, Australia, is a familiar figure at MEI's flotation and comminution conferences, and he questioned the value of collecting quality liberation-by-size and mineral class data to assist in defining the form by which valuable species appear in the tailing and gangue minerals report into concentrates. This has long been recognised as world's best practice. Such studies are paramount in understanding how a flotation circuit is operating. Unfortunately, in many instances such an approach is deemed time consuming, expensive and yields quantitative data way too late to be effective in an operating plant. Realising that an understanding of the mineralogy of a system is intrinsic to resolving metallurgical problems in their concentrator, some operators have resorted to conducting virtual sizing to extract liberation data on a sized basis from unsized samples. Such a practice is pursued to minimise the cost. But, how reliable is the data generated? Does this methodology actually produce sound liberation-by-size and mineral class information that can be used to solve metallurgical problems? Chris showed unequivocally that completing a liberation study using virtual sizing via QEMSCAN is patently wrong.
|Chris Greet (right) with delegates at the Magotteaux booth|
It is good to see workers realising that flotation performance is influenced by comminution, and in this respect also good to see grinding media companies such as Magotteaux sponsoring this event as well as Comminution '14. Keramos is a small dynamic company sponsoring a flotation event for the first time. They provide ceramic grinding media as well as ceramic liners for pumps, valves, cyclones etc. The company has been involved with previous comminution conferences, and is sponsoring and exhibiting at Comminution '14.
After a long day at the conference we travelled around the Mountain into the city, for the conference dinner at Moyos on the Waterfront. This was our first time at this venue, but we found it slightly disappointing compared with previous venues.
Wednesday November 20th
|Jon with J-P Franzidis and Dariusz Lelinski|
Prof. Franzidis then introduced the keynote lecture, given by Dr. Dariusz Lelinski, of FLSmidth, USA. This was an excellent presentation, showing how the global mining sector has faced dramatic changes over the last five years. The growth of emerging countries, especially China, initiated a global boom in metals and energy prices. High prices attract investments; companies have spent millions of dollars to open new mines, expand old ones and upgrade equipment to increase production. Increased production from multiple sources often exceeds the demand. As a result, an extended period of high commodity prices has been followed by falling industrial demand for raw material, a decrease of all commodity prices and constraints on access to capital. In response, capital expenditures have been scaled back and non-core assets are being disposed. There is a shift from maximizing value by increasing production volumes to maximizing returns from existing operations by improved productivity and efficiencies.
Dee Bradshaw presented a paper on behalf of Metso authors who were unable to attend. She discussed how if the particle size that can be effectively recovered in a flotation cell could be increased, the product size from grinding could be significantly coarsened, resulting in a more eco-efficient flowsheet. The Metso work shows that coarse particle recovery is extremely sensitive to froth phase effects, with recovery optimal at shallow froth depth and when turbulence at the pulp-froth interface is minimised.
Homie Thanasekaran of Eriez Flotation Division, USA then discussed how traditional conventional flotation machines are effective for fine particle size classes; however, limitations due to particle buoyancy and bubble-particle detachment restrict their effectiveness when floating coarse particles. As a result, flotation circuits are generally configured to maximize the recovery of particles finer than 150-200 micron. In fact, grinding circuits expend significant energy reducing a feed stock to a particle in the size range suitable for flotation. Fortunately, a novel flotation device has been developed, the HydroFloat Separator, that overcomes these limitations by carrying out flotation in a dense, fluidized-bed medium allowing for the selective recovery of coarser particles (>0.250 mm). Over the last 15 years, this technology has been successfully applied to industrial minerals with several full-scale units installed to recover particles up to and exceeding 3 mm diameter within the industrial mineral sector. More recently, sulphide-based laboratory test work has shown that this novel device is also capable of recovering metalliferous values at a coarse grind size. Benefits of this approach, such as improved recovery, low energy consumption and reduced reagent addition were reviewed.
Papers on new ways of developing flotation flowsheets, flotation modelling and comparing laboratory batch flotation tests and mini pilot plant testing concluded an excellent opening session.
|Yang Zhiyong (right) at the Shenyang Florrea Chemicals booth|
|Jim Finch and Osvaldo Bascur|
|With Xuming Wang|
|Jussi Vaarno and Mehdi Safari|
In closing the conference, consultants Dee Bradshaw and J.-P. Franzidis stressed the important role that these events now have in bringing together flotation people from around the globe every two years. It is a unique conference, neither an academic nor an operators' event, but an ideal blend of the two. Prof Franzidis remarked how impressed he had been with the networking which has taken place over the past four days, during the long lunch and coffee breaks, and particularly in the successful new innovation of the 'happy hours'.
Amanda then closed the conference, inviting all to convene again in two years time for Flotation '15, before we all adjourned once more to the hotel gardens for the final happy hour (see YouTube video)!