Precious Metals '12 Conference Diary

Precious Metals '12 was MEI's 4th International Symposium on the Processing of Precious Metal Ores and Concentrates.

Held at Cape Town's Vineyard Hotel from November 12-13, the conference was sponsored by Newmont Mining Corporation, Barrick Gold Corporation and Implats, with media sponsorship by the Gold & Minerals Gazette.

The following is my diary of events, which hopefully will be supplemented by comments from those who attended.

Monday November 12th


Jon, and Mike Adams

 Jon opened the conference this morning and welcomed the 51 delegates representing 11 countries. He then handed over to our consultant, Dr. Mike Adams, of Mutis Liber, Australia, who noted that this series of precious metals conferences has become the world's leading forum for discussion of innovation and research developments.

Mike reminded us that a precious metal is a rare, naturally occurring metallic element of high economic value. We now associate this with metals such as gold, but in 1855, before the Hall-Heroult process was developed, aluminium was exceedingly difficult to extract from its ores, and it was more valuable than gold. Bars of aluminium were exhibited at the Exposition Universelle of 1855 in Paris. In 2012 gold is the most precious metal, closely followed by platinum, the two metals which feature most prominently in this conference. Three other PGE metals are also 'precious' - rhodium, iridium and palladium.

Apart from one paper on silver, today's two sessions concentrated on the processing of gold, commencing with an excellent keynote from Dr. Rob Dunne, of Newmont, who gave a comprehensive overview of developments in gold processing over the past few decades. The largest gold producer is now China, followed by Australia, USA, Russia and then South Africa. There has been an 11% increase in gold production since 2004, but although the gold price has risen markedly there has been a 155% increase in production costs since 2005, so the profit margins are not as high as many people might think. Ores have become lower grade and more refractory, and Rob discussed the developments that have taken place in processing methods (i.e. milling, gravity, flotation, leaching, cyanide destruction/recovery and water treatment) and highlighted where advances are being made to make the gold industry more viable.

Teresa McGrath with keynote
speaker Rob Dunne

The first paper in the morning's technical session was presented by Teresa McGrath of Curtin University, Australia, who was making her debut as a presenter at an international conference. She discussed her PhD research project to create a model which simulates the behaviour of gravity recoverable gold (GRG) in a flash flotation unit operation. This was followed by papers on the CESL process, and methods to optimise gold processing operations.


Prof. Jannie van Deventer of the University of Melbourne presented his unconventional paper on invisible gold which is not detected by standard analytical techniques (see posting of 8th October). This provided much food for thought and discussion. I know that Jannie feels that the ideas that he presented would not pass peer-review, but I disagree and invite him to submit his paper to the special conference issue of Minerals Engineering. Maybe his ideas do challenge mainstream science, but little over 100 years ago so did Einstein's Relativity Theory, and Quantum Theory!

After lunch, the day concluded with a session containing papers on cyanide and cyanidation, and alternatives to conventional cyanide leaching.

Our sole exhibitor at the conference is CiDRA from the USA, who is displaying the SONARtrac clamp-on flowmeter, which provides a non-intrusive, online, real-time, measurement of the volumetric flow and entrained air present in the harshest environments and slurry conditions. The SONARtrac system is not affected by magnetite addition, as used in dense media separation, and does not suffer from drifts or offsets that commonly occur with magnetic flow meters. Processing plants around the world are utilizing the SONARtrac Systems to gain process efficiencies and to provide pipeline leak detection on tailings and slurry lines.

The CiDRA booth

Tuesday 13th November
Platinum group metals processing was the theme of today's session. This sector of the South African mining industry has in recent months been rocked by violent wildcat strikes that have led to killings, and destruction of infrastructure. Last week Amplats offered incentives which the workers turned down, and the parent company Anglo American placed four of its Rustenburg mines "under review", a move seen as a possible closure of the mines. With a deal secured in the gold sector, the platinum mines remain on the boil, and only three delegates from the platinum sector are at the conference. These are from Lonmin, a company which came to a deal with its workers in August, but only after a standoff that ended with police killing 34 miners.

So there was much interest in the keynote lecture this morning by Keith Liddell of Platmin Ltd., who discussed the processing of South African PGM ores, and the response to increasing operating costs, which have made profit margins extremely low despite high platinum prices. This year has been particularly drastic, and many mines are now non-profitable, some running at high losses due to factors such as very high electricity costs, and frequent power cuts, as well as very high mining costs due to deep mining. Although the underground miners work under appalling conditions, and have very reasonable arguments for higher pay, the dilemma is that payment of what we would call a reasonable wage would cause the total shut down of many mines.

Keith discussed how profitability could be improved by increasing the efficiency of processing and increasing recoveries. Flash flotation of fast floating material followed by longer flotation times to recover slow floating PGMs, and the use of energy efficient IsaMills, have improved recoveries by 2-4%, and energy efficient crushing by HPGR is increasingly used.

There was a great deal of discussion on the Kell Process (see posting of 9th March), which has great potential for the treatment of flotation concentrates, as it has been shown to be much more efficient than conventional smelting and base metal refining. Although the capital and operating costs of the Kell Process are around 50% and 70% respectively of smelting, the current economic climate is such that many mines cannot risk the investment in implementing this technology at present. Despite this, pilot plant trials of the process are scheduled for next year.

With Omolola Fayemi (South Africa), Tom Robinson (Canada),
Avela Majavu (South Africa) and Teresa McGrath (Australia),
who were presenting papers for the first time at an international conference

In his summing up of the conference, Mike Adams remarked on how the two keynote lectures had highlighted the squeeze on the gold and PGM industries, and how this conference has brought together highly motivated delegates who have discussed innovative technology which will bring economic benefits. Many people believe that there is a move away from pyrometallurgy to hydrometallurgy, and in fact there was only one pyrometallurgy paper at the conference. However, the future may see pyro and hydromet processes used in combination. It is also interesting to see nanotechnology creeping into mineral processing and extractive metallurgy.

So there are exciting potential developments ahead, and much to look forward to in 2014, when Precious Metals '14 will be held, at the Vineyard Hotel again, from November 20-21.

The 21 papers presented at Precious Metals '12 are now available on CD from MEI.