January Cornish Mining Sundowner

A modest turnout last night at the County Arms Hotel, Truro, for the first Cornish mining sundowner of the year.

There is no new local news this month, so here is some old news- a little nostalgia from the Camborne School of Mines Graduation Day in 1990. Unfortunately not exactly HD, but you may recognise a few faces.

Next month, on February 20th, the sundowner returns to the Chain Locker in Falmouth for 10 months. Sundowners are on the third Thursday of each month, so if you are in town on those dates we would very much like you to join us.

John Starkey: 1936-2025

We had very sad news yesterday from Canada of the death of John Starkey, the founding President and Principal Consulting Engineer of Starkey & Associates, the name behind a number of the most successful grinding circuit designs in the mining industry. 

John and Donna Starkey

Over the last 25 years Barbara and I, and Jon and Amanda, have become great friends of John and his dear wife Donna, and despite being separated by over 3.500 miles, we have kept in touch by email and phone, and regular meetings around the world, particularly in Cape Town, where Starkey & Associates has been a regular sponsor of MEI's comminution conferences, and at SME Meetings in USA and memorably in Falmouth.

Dining in Cape Town, 2018

Barbara with John and Donna in Denver 2013, and with me in Phoenix in 2020

Visiting Falmouth in 2018

John Starkey graduated as a mining engineer in 1961 from the University of Toronto. He had wide experience in mines and process plants, his career including work at Kam Kotia, Kidd Creek, and INCO mines and mills.  He worked at Kilborn (now SNC Lavalin) for 12 years designing the Gays River, East Kemptville and Quintette process plants.  From 1964 he worked in SAG mill hardness testing as pilot plant engineer for A. MacPherson’s projects. 

John founded Starkey & Associates in 2000 and the company is now a global leader in ore hardness measurement, and grinding circuit design and optimisation, particularly for SAG mills.  He invented and co-developed the SPI and SAGDesign tests which are both widely used in industry today for the measurement of ore hardness for AG and SAG mill designs. His mission has always been to capture for clients the rich benefits of SAG milling technology, to help them find the most economical way to grind their ore.

In 2017 the Canadian Institute of Mining, Metallurgy and Petroleum awarded John the CIM Fellowship for his "outstanding contribution to the mineral processing field". He also became a CIM Distinguished Lecturer, in recognition of his "remarkable contribution to comminution design and practice", and as such spoke at CIM Branch and Student Chapter meetings across Canada, as well as being a frequent lecturer globally at universities, teaching the fundamentals of AG/SAG grinding mill operation and design.  In 2021 he presented a keynote lecture at Comminution '21, MEI's only online comminution conference.

The CIM Fellowship Award in 2017

As well as being an outstanding engineer, John was a very popular person with many friends and colleagues worldwide, as shown by the selection of photos below.

John and Donna at Comminution '12, Cape Town, with Arkady Senchenko and Anna Shevtsova

Salt Lake City, 2014

Comminution '14 Cape Town

John (5th left) with Comminution '14 delegates, hiking Table Mountain

At 77 years of age, John was MEI's oldest ever Table Mountaineer

Denver 2015 with Spencer Reeves

Comminution '16, Cape Town, with Peter Radziszewski, Brian Loveday and Spencer Reeves

IMPC, Quebec City, 2016 with Jon Wills and Dave Meadows

Comminution '18, Cape Town with Felicity and Nick Wilshaw

Comminution '18, Cape Town, with Erik Spiller

Denver 2017 with Jenna Hedderson and Hans von Michaelis

With Physical Separation '19 delegates at the Chain Locker, Falmouth

On behalf of us all at MEI, deepest condolences to Donna and the family. You are very much in our thoughts.

An invitation by Glencore Technology to an IsaMill workshop at Comminution '25

The need to grind ever finer, as ores have become more complex and of lower grade, has led to the successful adoption of stirred mills. The most successful of these has been the IsaMill, which has led the way in energy efficient ultra-fine grinding since its development in the early 1990s.

IsaMill

In the 6th edition of my book Mineral Processing Technology I highlighted, in the Introduction, the inability to treat the huge zinc-lead- silver deposit at McArthur River in Australia. Discovered in 1955, for 35 years it resisted attempts to find an economic processing route and it ranked as one of the world's largest undeveloped deposits, with reserves estimated at 227 million tonnes, Due to the extremely fine dissemination and intergrowth of the minerals, attempts to treat the ore by existing processing methods had proved fruitless. 

The 6th edition was published in 1997 so I must have written this section shortly after the publication of the 5th edition in 1992, because in 1995 the McArthur River mine commenced production, the concentrator producing a bulk lead-zinc concentrate with an extremely fine product size of 80% minus 7 microns.

Development of a circuit for McArthur River ore recommenced in August 1989 at Mount Isa under the direction of Bill Johnson, the Milling Research Manager (posting of 27 August 2020). The ore was even more difficult to treat than the Mount Isa zinc-lead ore, well known for its difficult properties; one important outcome of the McArthur River project was the IsaMill, developed from the stirred milling technology of Netzsch Feinmahltechnik GmbH.

The mill was successfully introduced at  Mount Isa Mines and the Lead/Zinc Concentrator manager at that time was Joe Pease, who said that the team delivered the first significant breakthrough in fine grinding in 50 years, and the most significant development since SAG milling. The work at Mount Isa led to the development of the fine grinding necessary for mineral liberation of the McArthur River ore.

Joe Pease and Bill Johnson in Denver for their induction into
International Mining Hall of Fame in 2017

Mechanical Engineer Peter Woodall played a very important role in the pilot plant phase, the design modification phase and in numerous later activities with the mill and in 2008 Bill and Peter shared the Mineral Industry Operating Technique Award, for the development of the IsaMill technology.

The IsaMill technology, which is marketed by Glencore Technology, has spread into other duties in mineral processing and larger models have been developed, resulting in a large number operating in industry. The benefits of fine grinding in the IsaMill are now being applied at increasingly coarser grind sizes, and to a diverse range of minerals, a remarkable transition from the original small-scale applications. Larger ceramic media is now pushing the boundaries of feed size and can offer advantages in grinding efficiencies, product size distribution and internal wear.

Prior to Comminution '23, conference sponsor Glencore Technology held an afternoon workshop on the IsaMill at the Vineyard Hotel, attended by around 40 delegates.

Glencore workshop at Comminution '23

To celebrate the 30th Anniversary of the IsaMill, Glencore Technology invite Comminution '25 delegates to an exclusive workshop "Expanding the capability and application of the IsaMill" on Sunday 30 March immediately prior to the Comminution '25 welcoming reception. In the 2 hour workshop the Glencore Technology team will lead interactive sessions to help delegates make the right choices for their unique processing needs. Full details can be found on the workshop flyer.

#Comminution25

Green Flotation Depressants

Depression is used to increase the selectivity of flotation by rendering certain minerals hydrophilic, thus preventing their flotation. They are key to the economic flotation of many ores. They are generally classed as inorganics, small organics, and organic polymers. The use of polymeric depressants has the attraction of being less hazardous than the more widely used inorganic depressants, such as cyanide, which are widely used in sulphide systems. 

Biodegradable depressants are becoming more important due to environmental concerns and the need for environmentally friendly processes. They can replace or assist inorganic and toxic reagents in various flotation conditions.

Green Flotation Depressants, authored by Saeed Chehreh Chelgani et al, is a new publication on biodegradable depressants, delving deep into their performance, intricate structures, and adsorption mechanisms. The book describes diverse minerals and materials where these depressants have been used for their upgrading. Encompassing the entirety of current research, it is aimed at industry professionals and researchers in the field, especially on courses centered around froth flotation and recycling. From starch-based solutions to the diverse array of gums and the intriguing polyaspartate and tripolyphosphates each section unfolds a rich tapestry of knowledge, providing a holistic understanding of biodegradable depressants and their pivotal role in mineral processing.

Steinert to sponsor Comminution '25 and Physical Separation '26

I think everyone in the mining industry is now well aware of how important sensor-based electronic sorting has become and MEI is pleased to have the continuing involvement of Steinert, one of the leaders in this field. Steinert sponsored two of last year's 4 MEI conferences, Physical Separation '24 and Critical Minerals '24.

A busy Steinert booth at Physical Separation 24.......

.....and at Critical Minerals '24

It is not surprising that Steinert is to sponsor Comminution '25, as sorting waste rock and ore with low concentrations prior to comminution saves energy and water and enriches the grade of the ore.

Steinert's ‘dual energy’ x-ray transmission (XRT) is ideally suited for ore sorting because the x-ray radiation can penetrate stones with particle sizes up to 100 mm, allowing metals to be detected, even when they are not on the surface. 

In addition to XRT, Steinert offers other sensors that can be combined with one another. XRF (x-ray fluorescence) can be used to determine and sort individual chemical elements very precisely and optical sorting and lasers are well suited to the detection of ores with different colours, or crystalline structures.

Steinert is also the first sponsor to sign up for Physical Separation '26. There are many applications of Steinert technology in physical separation.  Electronic sorting has long been used in the recovery of diamonds, X-ray sorting systems screening out diamonds accurately and with high throughput rates at an early stage in the process. In contrast to conventional x-ray luminance processes, Steinert diamond sorting machines use high-resolution x-ray transmission sensors that screen the rock throughout. Detection takes place at the atomic level, and surface impurities do not affect the detection. This solution can be used early in the process in order to remove large diamonds before they are damaged or broken up in the subsequent crusher stages. Near-infrared (NIR) technology is also being used to analyse the complete material stream and reliably separate kimberlite from waste rock. Modern sorters have great advantages over the conventional sink/float process, not only in diamond processing.

We look forward to hearing the latest developments in electronic sorting at Comminution '25 and Physical Separation '26.

#Comminution25
#PhysicalSeparation26

Wishing you all the best for 2025

Five years ago this month I wondered what would be the main issues facing the world and the mining industry in 2020. Predicting the future is an impossible task I said. How true, as 2 months later the world ground to a halt with the onslaught of the Covid pandemic and the cancellation of all major events, including four MEI conferences and the International Mineral Processing Congress in Cape Town.

So I am a little wary now of expressing too much optimism, but I do hope for a year which sees a resurgence in the fortunes of many common metals, whose prices fell in the third quarter of 2024 due to signs of slowing industrial activity in major economies, especially China. 

We look forward to MEI's two major conferences which will be held in Cape Town this year, Comminution '25 and Flotation '25. But before these I will be in Denver next month, representing MEI as a media partner, for the Annual SME Meeting, which will be special this year as it includes the Komar Kawatra Symposium, and is in association with World Gold 2025, which should be well attended as gold is one of the few metals which has not suffered in 2024.

In March Comminution '25 will have a record number of presentations as well as exhibitors. Although the technical programme is now full we are still considering abstracts for poster presentation.

We will be back in Cape Town again in November for Flotation '25, where all the exhibition booths in the main exhibition area are already sold, but we have 7 booths available outside the main conference room. We expect a very full programme here too, so please submit your abstracts by the end of May if you would like to present your work.

The farewell sundowner at Flotation '25 will be a special evening for me, as I hope to celebrate the end of my eighth decade with flotation scientists from around the world, 10 days before my 80th birthday. 

A recent sundowner at the Vineyard Hotel

And thanks to a recent paper in Elsevier's Food Chemistry journal I will be able to relax in the knowledge that I will be celebrating with antioxidant alcohol!! As is well known, one of the reasons that alcohol consumption can contribute to disease is that its metabolism by the liver results in the production of highly reactive oxygen species. Such free radicals can react with and damage cellular components such as fats, proteins and DNA, affecting vital functions of cell membranes and blood vessel walls.

Antioxidants, which neutralise highly reactive free radicals. have been found to be present in several alcoholic drinks. Researchers at the University of Silesia, Poland, tested alcoholic beverages for antioxidant activity by electron paramagnetic resonance spectroscopy (EPR) using an EMX EPR spectrometer manufactured by Bruker, a regular sponsor of MEI's process mineralogy conferences. EPR is a technique that specifically detects species containing unpaired electrons, such as free radicals. The results clearly showed that some alcoholic beverages exhibit antioxidant properties. Red wines and brandy demonstrated the highest antioxidant activity, followed by whisky. 

So here's to a few glasses of pinotage with friends on November 20th, but in the meantime, with wine glass half full, I wish you all the very best for 2025.

Should we frown on those who enjoy an occasional glass of wine?

#Comminution25
#Flotation25
#MINEXCHANGE2025