Nickel Processing '15 Conference Diary

Nickel Processing '15 was held at the St. Michael's Hotel, Falmouth, Cornwall, from May 13-14 2015, and immediately followed Precious Metals '15 at the same venue.

Nickel's roller-coaster ride over the past 3 years
Source metalprices.com

There is a current surplus of nickel at the moment, as demand for stainless steel has slowed, especially from China. Nickel prices have therefore suffered greatly recently, so this, always the smallest of MEI conferences, was attended by a small group of specialists, 27 in number from 12 countries, compared with 35 delegates at Nickel Processing '12 in Cape Town. In all there were representatives from Australia, Belgium, Canada, France, Greece, Finland, Philippines, South Africa, Sweden, Turkey, UK and USA.

Those that did attend the conference were treated to a fine programme of papers and I thank International Mining for their media support.

 

Wednesday May 13th

Jon welcomed the delegates to Cornwall this morning and then introduced Anne Oxley of Brazilian Nickel Ltd, UK, who chaired the morning session. This opened with an excellent keynote lecture from one of my old CSM students, Andrew Mitchell of Wood Mackenzie, UK, who set the scene for the next 2 days by looking at the future of nickel production, particularly in relation to the outlook for nickel sulphide and laterite resource development (see posting of 8th December 2014). He forecast that nickel stocks should move into deficit by the end of the year, which will push prices higher, and that there is no question that the future of nickel supply will depend on laterites.

Jon with Andrew Mitchell and Anne Oxley

First Quantum’s Kevitsa Mine is located in northern Finland and mines a large, low grade, polymetallic orebody. Payable metals include nickel, copper, gold and PGM group metals. Profitability, at high volume, low grade operations like Kevitsa, is highly geared to metal prices and process improvements. Since the operation commenced there has been a focus on maximising the separation process so as to improve the Cu-Ni process profitability. Ishmael Muzinda of First Quantum outlined a number of these process improvements, their introduction and efficacy with a focus on the work to improve fines flotation recovery.

Ishmael Muzinda with Barry Lumsden of Ausmetec, Australia

The post-coffee break session was chaired by Neil Snyders of the University of Stellenbosch, South Africa. Nickel is the predominant product at the Nkomati mine in South Africa. High grade nickel mineral ores (2%) from the Massive Sulphide Body have been depleted leaving those of low grade (0.3%). Consequently, the beneficiation of this nickel ore presents a challenge to the minerals processing industry. In response, Westhein Maree of the Cape Peninsula University of Technology showed how batch froth flotation tests were used to explore the effects of mixtures of potassium amyl xanthate and Senkol 700 on the recoveries and grades of nickel. In the mixtures, the xanthate accounted for 95.5, 90, 85 and 80 mole% respectively. This approach has a potential for enhanced recovery and subsequent grade of nickel and will have significant positive economic effects.

Westhein Maree (right) takes a break with Turkish delegates Cihan Ozdilek and Ersin Ozarslan

Akira Otsuki of the Université de Lorraine, France presented work on a study aimed at investigating the sulphidisation-flotation of nickel oxide, the major nickel form available in nickel laterite. Sulphidisation was conducted before flotation to convert the surface of nickel oxide to nickel sulphide.

It was good to have Nevill Rice at the conference. He was at the University of Leeds for 32 years and retired in 2002. Still keeping in touch with the industry by reviewing papers for journals, and meeting up with old colleagues, he gave a presentation on a hydrochloric acid process route for nickeliferous laterites.

Nevill Rice (right) relaxing in the sunshine with Cihan Ozdilek of Esan, Turkey,
John Forster of Queen's University, Canada and Ian Townsend of Outotec, UK

The short afternoon session was chaired by Barry Lumsden of Ausmetec Pty Ltd, Australia. In the first paper Paul Norris of Camborne School of Mines discussed the continuous processing of nickel/copper concentrates in bioreactors at high temperature. Inhibition of the thermophiles at high mineral pulp densities in primary reactors and the length of residence times for efficient copper extraction have been among the factors considered in continuous process development.

Paul Norris (left) with Andrew Mitchell and Graham Brock

The final paper of the day was presented by Keisuke Shibayama who presented the commissioning and operation status of the Taganito HPAL Plant Project in the Philippines. This project will produce 30,000 Ni-tons and 2,600 Co-tons per year as mixed sulfide for export to the SMM Nickel Refinery in Japan. The plant commissioning was completed on June 2014 and the operation has been running smoothly and has reached monthly production corresponding to its nameplate capacity.

Keisuke Shibayama (right) with Antione Dissaux, of Eramet, France, James Vaughan and Anne Oxley

After a great first day of papers, I led the usual three and a half mile walk into old Falmouth, where we met up with other delegates for good Cornish ale in the 17th century Chain Locker pub (see also posting of 14th May).

On the chilly Pendennis headland overlooking the Fal estuary

Welcome drinks at the Chain Locker

 

Thursday May 14th

There were some very interesting papers in this morning's session, chaired by Nevill Rice and Camborne School of Mines' Chris Bryan.

Graham Brock of Direct Nickel Projects, Australia described "breakthrough technology" which leaches the full nickel laterite profile in nitric acid giving significant reductions in capital and operating costs compared to current technologies (see also MEI Online, December 3rd 2014). Graham effectively retired from Direct Nickel at the end of 2014 but now continues as a non-executive director and as a consultant.

Chris Bryan with Graham Brock and Nevill Rice

Following this interesting presentation, Anne Oxley, of Brazilian Nickel Ltd, UK) asked "why heap leach nickel laterites?" With the majority of nickel naturally occurring in laterite ores but the majority of production still in sulphides, she argued that it is high time there was a standalone commercial nickel laterite heap leach operation. The broad success of heap leaching of other metals has allowed hitherto uneconomic deposits to undergo successful economic exploitation, and heap leaching now accounts for between 25% and 40% of global copper and gold production. Nickel laterites are no different, every major and several junior nickel miners have evaluated nickel laterite heap leaching over the past decade and shown projects to have robust economics, with much lower capital costs than alternative hydrometallurgical options which have in general been dismal failures, both technically and commercially. Nickel Laterite Heap leaching is simple and flexible, and can be applied to the many laterite deposits that currently have no realistic path to production.

This set the scene for another interesting paper on laterite heap leaching. Akira Otsuki of the Université de Lorraine, France, explained the development of a characterisation method for partiallysaturated agglomerate beds in relation to nickel heap leaching operations.

Georgios Bartzas prepares for his presentation

The final paper of the morning was given by Georgios Bartzas of the National Technical University of Athens, who presented a case study on the life cycle assessment of FeNi production in Greece. Ferronickel (FeNi) is predominantly produced from nickeliferous laterite ores which are converted into a product with a nickel content of around 20%. With increasing emphasis being put on energy efficiency and global climate change, it is important for the nickel industry to understand in depth the energy use and to evaluate a number of potential opportunities for reducing the greenhouse gas footprint of primary FeNi production.

 

Akira Otsuki chaired the final session of the conference, which contained 4 presentations, from Australia, Canada and Sweden.

James Vaughan of the University of Queensland discussed the properties of a commercial solvent impregnated cation exchange resin for cobalt-nickel separations. The hydrometallurgical processing of nickel ore typically involves precipitation of a mixed nickel-cobalt intermediate precipitate, as selective separation of these two elements by sulphide or hydroxide precipitation is not feasible. However this is not necessarily required; for example “direct” two-stage solvent extraction was practiced at the Bulong refinery where a Cyanex 272 containing organic liquid was used to separate Co, Cu, Zn and Mn from Ni. Complexities associated with this process include the requirement of a flammable organic diluent, phase separation equipment as well as the risk of organic cross-contamination. He described an ion exchange resin process whereby the value metals Ni and Co are both loaded onto the cation exchange resin and separated in the elution stage. As nickel is preferentially loaded, a larger volume of resin is required translating to a significant capital cost for the resin inventory. Solvent impregnated resin offers the engineering advantages of ion exchange resin and the chemical selectivity of the solvent extraction process.

Nickel laterites are more difficult to process compared to sulphide ores due to their complex mineralogy and as a result, current industrial processes are energy intensive and costly to operate. Novel pyrometallurgical processes regarding the upgrading of nickel laterites are also being continuously investigated through laboratory research and pilot plant testing and Richard Elliott, of Queen's University, Canada, reviewed the current state of the art and discussed the potential applications of developing processes.

In a further paper from Queen's, John Forster presented results on the microwave carbothermic reduction processing of a silicate nickel laterite ore. The effects of processing time, microwave power, and charcoal and pyrite additions were investigated. The reduction process was followed by magnetic separation and optimum nickel grades of about 9% and recoveries of about 90% were achieved.

John Forster and Richard Elliott of Queen's University Canada.
This was their first visit to Europe, so Falmouth was a pretty good choice!

Srinivasan Suresh of Sweden's Luleå University presented the final paper of the conference, a study of the reduction of nickel oxide by hydrogen under microwave irradiation. He showed that reaction rates were significantly improved for microwave experiments under all conditions when compared to conventional heating. Therefore, it was concluded that microwave heating would significantly reduce processing time and enhance reaction kinetics and it has a potential to overcome several rate controlling steps involved in conventional processes.

Srinivasan Suresh with session chairman Akira Otsuki

Amanda then closed the conference, and invited delegates to attend Nickel Processing '17 in Falmouth in 2 years' time, when hopefully Andrew Mitchell's forecast of increasing nickel prices will boost this small but important sector of the base metals industry.

 

The papers from the conference, in unrefereed form, are available from MEI, and authors have been invited to submit their final papers for peer-review, for possible publication in a special issue of Minerals Engineering.