Complexities and Opportunities for Gold Processing in a Changing Environment

The gradual exhaustion of free milling resources of gold ores has made the gold industry increasingly reliant on complex, refractory gold ores and other non-traditional sources such as leach tailings and electronic waste. However, the extraction of gold from these sources has been associated with significant challenges due to the inability of traditional methods to deal with the complex mineralogical characteristic of such feed material. 

While traditional pre-treatment methods such as roasting, pressure oxidation, bioleaching, etc. and the integration and combination of such techniques in alternative flow sheets have remained key, consideration is, however, now also being given to non-conventional techniques such as mechano-activation, cavitation and ultrasound pre-treatment processes prior to cyanidation. 

At the same time, the extraction of metals has also come under severe scrutiny from both regulators and the public leading to the establishment of stringent environmental laws that have also had a significant impact on the approach to gold processing. These, together with an increasing focus on the circular economy and the drive for responsibility in mining, have forced mining companies and researchers to look at alternative and environmental friendly reagents and to consider cleaner production and process re-engineering for sustainability in gold extraction. In her keynote lecture at Sustainable Minerals '22 Sehliselo (Selo) Ndlovu will discuss the challenges in gold extraction and the opportunities in research and development that have come about as a result of some of the changes happening in the gold hydrometallurgical processing sector.

Selo Ndlovu is a Professor in the School of Chemical and Metallurgical Engineering at the University of the Witwatersrand in Johannesburg, South Africa. She holds a PhD in Minerals Engineering from Imperial College, London. She joined the Engineering Faculty at Wits University in 2004 where she has since established a strong teaching and research base in hydrometallurgy, spanning precious and base metals, solid and liquid waste treatment, optimising existing and developing new processes for metal extraction. Selo currently holds the Department of Science and Innovation (DSI) and the National Research Foundation (NRF) funded SARChI research chair in Hydrometallurgy and Sustainable Development at the university. She is also a former President of the Southern African Institute of Mining and Metallurgy (SAIMM).

#SustainableMinerals22

Prof. Alban Lynch: 1930-2021, the first Director of the JKMRC

There was very sad news from Australia yesterday of the passing of one of the greats of mineral processing, Prof. Alban Lynch, the first Director of the Julius Kruttschnitt Mineral Research Centre (JKMRC). He was a man ahead of his time both in terms of technical innovation and in recognising the need to collaborate with industry. He encouraged his students to work on site and trusted them to find solutions to their research challenges. He led by example and in so doing established the JKMRC as an international leader in mining research.

Prof. Lynch at the JKMRC in the early 1970s

I first met Alban in 1986 when he presented a keynote lecture at the NATO Advanced Study Institute in Falmouth. Seven years ago I had the great pleasure of interviewing him for MEI, and I refer to the posting of 11th August 2014 for a full account of his life and work.  Following the interview I was great honoured when he suggested that he might reciprocate and interview me (posting of 2nd November 2015).

Alban Lynch was a legend in the mineral processing profession, particularly in the field of comminution, and he received many awards during his long career. He was an Officer of the Order of Australia, and in 2010 received what is considered to be mineral processing's top award, the Lifetime Achievement Award of the International Mineral Processing Congress (posting of 8th September 2010).

Prof. Lynch receiving the IMPC Lifetime Achievement Award
from Prof. Eric Forssberg, Brisbane 2010

In 1958 Alban joined the Dept. of Mining and Metallurgical Engineering at the University of Queensland (UQ), where he would remain for most of his long career. In 1962 a three year AMIRA project on grinding started at UQ with a group consisting of Alban, two graduate students and two technicians. The theme of the research became the modelling and simulation of grinding circuits. Mount Isa Mines supported the work and this was the start of the tradition of project research being plant based and of graduate students, including T.C. Rao (posting of 16 July 2014) spending months at plants on thesis projects, which had the objectives of improving local circuits and providing data to support the general programme on modelling and simulation. This all culminated in the publication of one of Alban's most well known books, Mineral Crushing and Grinding Circuits.

In 1971 the research group was given strong encouragement by MIM Holdings Ltd when the company established the JKMRC to be its Brisbane base, with Alban Lynch its first Director, a position he held until 1989, when he handed over to Dr. Don McKee, allowing Alban to concentrate on his new role as UQ's Professor and Head of Mining & Metallurgical Engineering, a position he held until 1993. By 1980 models of grinding and flotation circuits were well developed and another book was published Mineral and Coal Flotation Circuits, which Alban co-authored with N.W. Johnson, E.V. Manlapig and C.G. Thorne.

After 6 years as Head of Department at UQ, Alban spent a large portion of the next 15 years lecturing on modelling and setting up research programmes in other countries, notably in Malaysia, Brazil, Mexico and Turkey, also finding time to co-author more books, in 2005 The History of Grinding, with Chester Rowland, in 2010 The History of Flotation with Greg Harbort and Mike Nelson and in 2015 the Comminution Handbook.

Launch of History of Flotation at the 2010 IMPC in Brisbane,
with Mike Nelson and Greg Harbort

Despite his very busy international schedule Alban remained an active member of the JKMRC community throughout his life, and as recently as only 3 months ago he joined the JKMRC staff, students and alumni at the AusIMM MillOps '21 conference in Brisbane.

Our heartfelt condolences are extended to Alban’s family. He will be sadly missed and I invite all those of you who had known this remarkable man to submit your memories and appreciations.

@barrywills

The Cornish Mining Sundowner returns to Falmouth's Chain Locker Inn

It's hard to believe that the last Cornish Mining Sundowner at the Chain Locker was 19 months ago, but last night, with Coronavirus restrictions eased, we returned to our old haunt, with a great attendance and a number of new faces.

Making his sundowner debut was the new head of Camborne School of Mines (CSM), Prof. Stephen Hesselbo, and it was also good to see Dr. Penda Diallo, who is leaving CSM after 4 years as a lecturer in Sustainable Mining, to take up a position at the Aluminium Stewardship Initiative as Qualitative Research Manager.

Prof. Hesselbo presenting Penda with a bouquet in appreciation of her time at CSM

Stephen arrives, and Penda leaves, at a critical time in the history of CSM, as there has been no intake of undergraduate mining engineering students this year, due to Exeter University’s decision to end recruitment to undergraduate mining engineering for the first time in the 134-year history of CSM (posting of 13 September 2020).

However, all is possibly not lost, as I talked to my old CSM colleague John Coggan, Professor of Rock Engineering, last night. John is the Chair of a Working Group set up by CSM to investigate the potential interest from industry in supporting the development of an industry-focused pioneering degree-level blended learning undergraduate provision in ‘mining engineering’ to educate and train the next generation of mining professionals. The programme builds on the future demand for earth resources, green energy and technology metals, expectations around sustainability, and well-managed use of these precious resources. The pioneering programme is based on an apprenticeship style-programme and has been developed with an Industry Advisory Panel to ensure that the curriculum meets the needs of industry, incorporates best practice, and identifies the key knowledge, skills and behaviours that are essential to design, operate and safely manage either an underground or surface mining operation. To help shape and refine the structure and content of the programme, and to assess the level of potential interest, industry representatives have been asked to complete a short survey which closes on the 17th September. The results of the survey will help inform a proposal that will be presented to senior University management for approval towards the end of October, so hopefully there will be some good news for the November sundowner.

Stephen, Penda and John

Last night's sundowner was also the last before one of our regulars, Alexandra Sweeney, who has been working with the Met4Tech Centre goes to Durham to start her Mine water geothermal PhD. We wish Penda and Alexandra every success. 

Alexandra (4th left) with Stephen Hesselbo, flanked by CSM mineral processing lecturer
Dr, Rob Fitzpatrick, and Alexandra's mother Prof. Frances Wall, a former head of CSM

It felt like we were back to 'normality' again last night, but we must be wary, the pandemic is not yet over, and the winter months are approaching. All being well the next sundowner will be at the Chain Locker on Thursday October 21st, commencing at 5.30 pm. Do join us if you are in the Falmouth area.

@barrywills

We welcome two more sponsors for Flotation '21: Metso Outotec and Woodgrove Technologies

The response to Flotation '21, MEI's 10th flotation conference, and the first to be totally online, has been more than we could have hoped for, such that we have had to extend to five days to accommodate all the abstracts submitted, and we now have 21 major sponsors who have thrown their weight behind the event. The two latest are Metso Outotec and Woodgrove Technologies.

Last month we welcomed Metso Outotec as a sponsor of Sustainable Minerals '22, 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 just over a year ago, forming a unique new company with leadership in sustainable minerals and metals processing and recycling technologies. Headquartered in Finland, Metso Outotec employs over 15,000 professionals in more than 50 countries.

Established in 2009 by Glenn Kosick and Glenn Dobby to promote their Staged Flotation Reactor, Canadian company Woodgrove Technologies continues the mandate of their previous company, Minnovex, in providing innovative, technologically advanced flotation and advanced process control systems for the mineral processing industry. In 2018, for the first time in its history, a double award was made at the Canadian Mineral Processors Annual Meeting, when Glenn Dobby and Glenn Kosick were made Canadian Mineral Processors of the Year for their development of the Staged Flotation Reactor.

Woodgrove's Staged Flotation Reactors and Direct Flotation Reactors are low-footprint and cost-efficient flotation units and design of circuits incorporating these devices will be described by the Manager of the Flotation Division, David Hatton, at the conference.

Updates can be found at #Flotation21

A stunning walk over southern England's highest cliff, Golden Cap

The South-West Coast Path is England's longest waymarked long-distance footpath. It stretches for 630 miles, running from Minehead in Somerset, along the coasts of Devon and Cornwall, to Poole Harbour in Dorset, including the latter county's famous Jurassic Coast.

Two days ago ago Barbara and I, out of Cornwall for only the second time since the start of the pandemic, did the challenging short hike between Seatown and Charmouth. Although only about 5 miles it took us up and over the Jurassic Coast's iconic Golden Cap, at 626 feet (191 metres) the highest point on the south coast of England. Its name comes from its yellow capping of weathered Upper Greensand, a sandstone typically deposited in marine environments like the one here in Jurassic times. When we first visited the area 16 years ago its golden cap was a memorable sight in the evening sunshine, but since then the colour has been dimmed by an increase in vegetation cover. Nevertheless the views from the top are as glorious as they ever were.

We took the bus from our base at Lyme Regis to Chideock and walked through the village to the coastal path at Seatown. From there it was a fairly gentle climb to Golden Cap where we were rewarded with fine views in every direction before descending to Charmouth and the bus back to Lyme Regis.

A highly recommended short hike if you are reasonably fit!

A gentle start

The steep climb to Golden Cap

Approaching Golden Cap

The view to the east towards Portland

Looking north to the beautiful medieval fields and countryside of Dorset

West to Lyme Regis and East Devon

The long descent

Approaching Charmouth

@barrywills

Physical Separation '22 and IntegratedMinPro '22: First call for abstracts

Physical Separation '22 and Integration, Optimisation & Design of Mineral Processing Circuits (IntegratedMinPro '22) were scheduled to run back to back in Falmouth next June, but as it is evident that international travel will not be possible for many countries by then, the conferences are now online.

Physical Separation '22 will now be online from May 9-11 2022.  This will be MEI's 7th Physical Separation conference and will bring together researchers and operators who have common interests in:

• Gravity concentration methods - single and multi-G separators and dense medium separation
• Classification techniques - hydrocyclones, air classifiers etc.
• Solid-Liquid Separation - thickeners, clarifiers etc.
• Electronic Sorting
• Magnetic and electrostatic separation
• Microwave technology. There are many aspects of mineral processing where the use of microwaves has potential and papers dealing with the enhancement of physical processes by microwaves are encouraged.

Our Media Partners are International Mining and Imformed, and our Industry Advocates are the Coalition for Eco-Efficient Comminution (CEEC), the Cornwall Mining Alliance and the Critical Minerals Association.

There is now a first call for abstracts and sponsors. Short abstracts should be submitted via the online portal by the end of February.

IntegratedMinPro '22, a brand new MEI Conference will run from June 13-15 2022 and we thank our first sponsor, Promet101, Media Partner International Mining, and Industry Advocates Cornwall Mining Alliance and the Critical Minerals Association for their early support.

As the demand for resources continues to increase, and amidst growing challenges of processing complex ores while minimising energy and environmental impact, we are entering an exciting time for innovation in mineral processing. Innovation in individual unit operations is complemented by innovative approaches to the entire mineral processing flowsheet, from rearrangement of an existing circuit to a new approach for a greenfield development.

IntegratedMinPro '22 invites papers on new approaches to mineral processing circuits, whether through design, modelling, optimisation or operation. This includes integration of unit operations (e.g. comminution and flotation), novel flowsheets that incorporate new equipment and new approaches to optimising circuit design. We invite abstracts in these areas by the end of March. Sponsorship details can also be found on the website.

As with all MEI Conferences presenters will be invited to submit papers to Minerals Engineering for peer-review after the conference. These will be handled exclusively by me, the journal's Editor-in-Chief, and I will take into account discussion at the conference and effectively fast-track the reviewing process.

If your paper is accepted for publication after refereeing, it will be published immediately in the first available regular issue of Minerals Engineering, and included in the Virtual Special Issue of the conference on ScienceDirect.

We look forward to your active participation in these two important events next year.  Updates are at:

#Physical Separation22
#IntegratedMinPro22