June Cornish Mining Sundowner- new and familiar faces and a great historical video

Despite the Cornish 'mizzle' there was a good turnout last night at Falmouth's Chain Locker for the June mining sundowner.

For the first time we almost had a full MEI team present. Jon, in the Luxembourg office, was missing but it was good to see Amanda and her son, Will Collins, who recently joined the MEI team.

As well as a few current Camborne School of Mines students, it was good to see a number of "old boys", who always have interesting stories to tell.

With CSM alumni Connor Spollen, Andy Wetherelt, Alun Jones,
Mark Alcock, Mark Shimmield and Nick Wilshaw

I was particularly pleased to see Connor Spollen, who graduated in mineral processing in 1990 and has had extensive experience in Chile, Ireland, Canada and USA. He is now based in USA as CEO of Jervois, a leading global supplier of responsibly sourced and produced cobalt and nickel materials. 

With Connor and son

It is 35 years since I last saw Connor. His final year project at CSM was on mass balancing and he produced a paper, co-authored by me and maths lecturer Nigel Powell, which was presented at the SME Annual Meeting in Denver. After the conference we headed for Copper Mountain where he, Barbara and Nigel skied for the first time.

Denver, 1991. Connor right and Nigel left

Sundowner regulars Dave and Treve Milden of Gravity Mining were missing last night, but were at last week's UK Mining Conference in Cornwall. Dave was also at Physical Separation '26 (YouTube video) in Cape Town in April, promoting the world's largest gravity concentrator, the C910 MGS.

The Multi-Gravity Separator (MGS) was invented by the late, great Richard Mozley and is now manufactured by Gravity Mining, a sponsor of Physical Separation '26. The C910 is a far cry from the MGS which was launched in Stockholm in 1988 by Richard and his team.

C910, and prototype MGS in 1988

Richard Mozley 1993

Dave came across this great video last week which was made in 1993 two years before Richard's death. It details the development of the MGS on the Wheal Jane concentrator, near Truro, and features Richard Mozley and two familiar faces at the mining sundowners, Kevin Ross, who was Managing Director of Carnon Consolidated, who owned the mine, and Mike Hallewell, who was then Metallurgical Superintendent. The MGS helped the concentrator at Wheal Jane to continue operating after mining stopped in 1991, as it processed ore brought in from the South Crofty tin mine. It finally closed in 1998, when South Crofty shut down. 

Mike and Kevin, 1993

Mike Hallewell continues his involvement with South Crofty. He is consulting metallurgist to Cornish Metals Inc., the mining developer whose success largely depends on successfully reopening the historic tin mine and benefiting from long-term demand for critical minerals. Mike will be a co-author of a paper at Critical Minerals '26 in Cape Town in November. Presented by James Strongman of Redruth company Petrolab, the paper will assess the economic impact of ore sorting, which will be used to pre-concentrate the ore at South Crofty.  Petrolab is a sponsor of the conference, and for Process Mineralogy '26 which precedes it, and James will be presenting papers at both events.

Amanda and Will with James Strongman

It was an excellent sundowner last night and I look forward to more surprises at the next one, which will be on Thursday July 16th at the Chain Locker, from 5.30pm.

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Memories of Ultrafine Grinding '06, Falmouth

Ultrafine Grinding '06 was held in Cornwall at the ill-fated Falmouth Beach Resort Hotel, which six years later was destroyed by fire.

The two-day conference was MEI's first ultrafine grinding conference, and was also the last as it was merged into the comminution series two years later.

Attended by 64 delegates from 24 countries, sponsorship was provided by Xstrata Technology, PMT-Jetmill, Saint-Gobain Zirpro, Industrial Minerals and notably Maelgwyn Mineral Services (MMS), sponsoring their first MEI Conference. Since then MMS has regularly supported MEI Conferences, particularly the comminution and flotation series, but others as well. 

Twenty-two papers were presented over the two days and selected papers were published in Volume 20 Issue 4 (2007) of Minerals Engineering.

Photos taken at the event, including a first evening coastal path walk and a final afternoon visit to the Camborne-Redruth historical mining district, are shown below.

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UK Mining Conference continues to grow

The annual UK Mining Conference in Cornwall was created by Jeremy Wrathall, of Cornish Lithium, in 2019 and is aimed at professional and private investors, brokers, financial institutions, supply chain consultants, government representatives, trade associations, as well as mine operators and explorers. 

Cornwall is the most appropriate area of the UK to hold such an event at it is at the centre of a renewed UK mining boom because of its deposits of lithium, tin, tungsten and other critical minerals. Recent developments include geothermal-lithium extraction projects and efforts to reopen historic mines such as South Crofty. An independent report published this week highlights how Cornish Lithium is set to unlock £5bn for the UK economy, tripling the GVA of the mining and quarrying sector in Cornwall and creating a further 1000+ jobs in the county. Lithium production should support the production of 760,000 EVs per year, enough to meet around 40% of the Government's annual lithium production target by 2035. 

The conference was held on 10-11 June, and was attended by over 450 delegates from 21 countries, a far cry from the 30 delegates at its inception in 2019. There were also pre and post conference events, including a geothermal forum, a geologists workshop, an investors congress, various site visits and a gala dinner with presentation of awards.

On the evening prior to the conference I called in at my 'local' the Chain Locker to hopefully catch up with some of the delegates attending a Cornish buffet supper, and I wasn't disappointed. I shared an outside table with a group of familiar Camborne School of Mines people. Linda and Mark Shimmield are based in Adelaide, but spend time in Cornwall each summer. Linda was the founding secretary of the CSM Association, and husband Mark graduated in mining engineering in 1982 and three years later Paul Benjamin and Andrew Mitchell graduated in mineral processing. It was also good to meet Arlan Yeleusszov. from Kazakhstan, who is completing an MSc in mining at CSM.

Linda, Paul, Arlan, Andrew, me and Mark

It was also good to see Jens-Michael Bergmann and Oxana Penning, of TOMRA, who will be supplying their sensor-based sorting machines to Cornwall's South Crofty tin mine and to Devon's Tungsten West mine at Hemerdon. The company will be exhibiting at Comminution '27 in Cape Town next April.

And on the way home I bumped into another CSM alumnus, Kirk Adams, and his partner Isabelle. Kirk, who will be the MC at the conference dinner, graduated in mining engineering in 1985.

UK Mining in Cornwall is not a mineral processing conference, but the venue, Falmouth's Princess Pavillion is only a short distance from home, so, as last year, I called in for the first morning, hoping to catch up with a few familiar faces.

Delegates have come from all over the world and none so far as Australia, so it was great to see Ben Wraith and Nigel Grigg, of Gekko Systems, Melbourne. Gekko will be providing jigs to Tungsten West and likely to the South Crofty project.

Ben and Nigel

Sepro Mineral Services will be supplying Falcon gravity concentrators to South Crofty, and Doug Caffell I last saw in Cape Town in April, where Sepro were exhibiting at Physical Separation '26 and Mineral Processing Circuits '26.

Doug Caffell (right) at the Sepro booth

Dave Mildren was also at Physical Separation '26 representing Gravity Mining as a sponsor. Cornwall-based Gravity Mining produces the Multi-Gravity Separators, and Dave and his bother Treve were at the MintMech stand, talking to their team of Ashley Hares, Laurie Thornton and Alun Jones. MintMech is a Cornwall-based engineering company focused on offshore marine, drilling, automation, and specialist industrial equipment.

MintMech also provides engineering and fabrication support to Gravity Mining, handling the design and build of the huge C910 MGS chassis, drum support arms and oscillating drive mount, to improve construction and performance.

Ashley, Laurie, Treve, Dave and Alun

I was pleased that Mervyn Stevens and Dan Cairns, of Worley, UK, introduced themselves to me. They will be at Critical Minerals '26 in Cape Town in November, where Mervyn will be presenting a paper on circular battery flowsheets, incorporating process intensification, selective impurity rejection and reagent regeneration to improve lithium, nickel, cobalt, and manganese recovery.

With Mervyn and Dan

It was great to see the AFX Mixing and Pumping Technologies team. The company sponsored Biomining '20, which was scheduled to be held in Falmouth, but because of Covid became an online conference, Biomining '21 the following year.

AFX Mixing and Pumping Technologies is a UK and South Africa-linked engineering company that designs and manufactures industrial mixing systems, agitators, and peristaltic hose pumps for heavy-duty process industries. The South African side of the business began as AFROMIX in 2006 and the UK business, AFX Mixing And Pumping Technologies Limited, was incorporated in 2015 and is headquartered in Poole, Dorset. Because of the South African connection the team expressed strong interest in an involvement with Hydrometallurgy '27 next year in Cape Town.

The AFX team

I had to confess to Kevin Hall and Steve Kilner that I had never heard of BJD Crushers, so it was good to talk to them. The company is based in Wakefield, West Yorkshire, and traces its roots back to 1897 under the original name British Jeffrey Diamond, which is where the initials BJD come from. They produce roll and impact crushers for quarrying, cement production, waste recycling, power generation and chemical processing.

Kevin and Steve

And finally, it's always great to catch up with Lucy Crane, who also lives in Falmouth. Lucy is Managing Director of Women in Mining (UK). WIM UK is a professional organisation, founded in 2006 to promote careers in mining and minerals for women, support networking and mentorship, improve gender diversity in the industry and to highlight female leaders and role models. It works with mining companies, universities, and policy makers to improve inclusion across the sector.

Lucy (centre) and the WIM UK team

It was an interesting few hours at the meeting and, as always, Jay One Events should be congratulated on organising such a large conference so efficiently. The next UK Mining Conference in Cornwall is scheduled for the week beginning 14th June 2027, at Falmouth's Princess Pavillion.

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When Solvent Extraction came to Africa

My career in mineral processing began in October 1969 at the the Nchanga Copper Mine in Zambia. In 1969 Nchanga produced copper from a mixed ore containing about 3% copper by weight. Ore had been mined from underground since 1938, but in 1955 open-pit mining commenced, and the giant Nchanga open-pit and the smaller Chingola and Mimbula-Fitula pits began to contribute to a total milled tonnage of about 30,000 tonnes per day treated at the massive operation. Underground ore contains mainly suphide minerals, chalcocite, chalcopyrite, covellite, bornite, while the shallower open-pit ores contain oxidised minerals, mainly malachite and azurite, as well as cuprite and chrysocolla.

My first two years at Nchanga were on the concentrator, mainly involved with flotation. The milled ore from underground and the open pits was first fed to sulphide flotation; then the sulphide tailings were sulphidised (using sodium hydrosulphide) before recovering the oxidised minerals. High grade sulphide concentrates were shipped 30 miles to Rhokana in Kitwe for smelting and high grade oxide concentrates were pumped to the high-grade leach-electrowinning plant.

Oxidised copper flotation is always less inefficient than sulphide flotation, and at Nchanga the situation is exacerbated because of the presence- in addition to the recoverable malachite and azurite- of relatively large amounts of poorly floatable cuprite and almost totally non-floatable chrysocolla.  Consequently, with an overall recovery of about 85%, the final tailings from oxide flotation still contained around 0.4% acid-soluble copper, resulting in a loss to the final tailings dams of around 150 tonnes per day of copper. 

It was decided that these losses must be recovered and the metallurgical manager, Jack Holmes (posting of 11 November 2017) was taken out of the direct management stream to determine how to deal with the  losses. He looked at many schemes but homed in on leach-solvent extraction after having travelled to the USA with a small team* to evaluate its potential.

Jack Holmes with the MEI team in 2017

In the late 1960s (1968 at Ranchers Bluebird Mine and 1970 at Bagdad Mine), solvent extraction had been successfully introduced to copper processing in the USA; so, after much process evaluation, a decision was made to develop and build a huge tailings treatment plant at Nchanga, to recover copper from not only continuing tailings arisings, but also from past tailings stored in the dams, and in 1974 this, then (and for many years) the world's largest solvent extraction plant, came on-stream, treating about 900,000 tonnes of tailings per month.

The huge plant was built in two stages, to achieve copper production as soon as possible. In stage 1, thickeners and neutralisation vessels were erected, together with the leaching pachucas in which the tailings minerals would be intensively agitated in a dilute solution of sulphuric acid to produce a weak copper sulphate solution. This would be upgraded and purified in Stage 2 by the solvent extraction process, before precipitating the copper by electrolysis.

During construction of Stage 2 I was on the commissioning team which put into operation Stage 1, to treat a large stockpile of low grade oxide concentrate, which had hitherto been found difficult to treat economically . The copper in this stage was precipitated from solution by cementation onto scrap iron in temporary Kennecott Cone units.

Leach pachucas and Kennecott Cones

I left before the Tailings Leach Plant came into operation, but was amazed when I visited in 2012 to see the scale of this process, which now treats up to 50,000 tonnes per day of current sulphide flotation tailings and old tailings in the leach-SX plant, 4500 tonnes per month of final copper being produced in a giant electrowinning tankhouse. 

A section of the massive Tailings Leach Plant in 2012,
with the smelter in the background on the site of the old high-grade leach plant

At MEI's Hydrometallurgy '27 conference in Cape Town next year, Dr. Kathy Sole will present a keynote lecture and will show how this elegant copper processing technology conforms to the principles for a circular hydrometallurgical flowsheet, and can be considered to have been ahead of its time with respect to these ideas. Today, some 20% of world primary copper cathode is produced using this technology, with the dominant contribution coming from the African Copper Belt and the keynote will draw on examples of developments and advances during the past five decades, and continuing in the modern era.

Kathy Sole holds a PhD from the University of Arizona. She has been providing independent hydrometallurgical consulting services since 2011, with clients on six continents, and has worked across a wide range of commodities, including base metals, uranium, titanium, vanadium, and precious metals. Her main areas of expertise are in solvent extraction, ion exchange, and electrowinning. She also holds an adjunct professor position at the University of Pretoria. She received the 2019 Milton E. Wadsworth award from the SME and was twice awarded the Silver Medal of the SAIMM. Kathy is a Fellow of SAIMM and the South African Academy of Engineers.

* I would like to thank Ken Severs, who was part of the Stage 2 commissioning team, for checking details in this posting for accuracy.

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Growth Steel is the latest sponsor of Comminution '27

The Indonesian company Growth Steel is formally part of the Growth Steel Group, a privately held industrial manufacturing group headquartered in Medan, Indonesia. The group is best known internationally for supplying wear-resistant steel products and mill lining systems to the global mining industry. 

Growth Steel's first MEI Conference was Comminution '25, where they were represented by five delegates, four from Indonesia and one from UK, and they exhibited at the event. Now we welcome them back, not only as an exhibitor, but also as a sponsor of Comminution '27.

The Growth Steel team at Comminution '25

The company traces its roots to the Suhendra family, which founded the broader Growth Steel Group in 1964. The Growth brand as a mining and foundry business was established in 1989 and expanded into mining industry wear parts around 1996. Although headquartered in North Sumatra, Indonesia the company has additional sales offices located strategically around the world such as Australia, South Africa, Ghana, Peru, Chile and China. 

Growth Steel has the world’s largest single-location mill liner foundry and has become one of the world’s leading manufacturing foundries and a major global supplier of grinding mill lining systems. The company primarily serves mining and mineral processing operations, its products including steel and rubber mill liners, grinding balls and rods, crusher wear parts, fasteners and steel castings for heavy industrial use.

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May summary: sad news from South Africa, and the first heatwave of the year

None of the MEI team were at home on the first of the month. Amanda was in the Isles of Scilly, competing in the annual World Gig Championships.

Jon and family were camping in Nommerlayern, Luxembourg and Barbara and I were enjoying our last day at Plettenberg Bay, before the long taxi ride to George airport the next day, a short flight to Cape Town, the long flight to London and the long train journey to Cornwall.

A farewell to Plettenberg Bay

There was also sad news from South Africa early in the month. A memorial was held at the University of Cape Town on the 8th of the month, for Martin Harris, who died the previous month at the age of 66.

After completing his Masters degree at UCT, Martin joined the Centre for Minerals Research (CMR) in 1987. and made many contributions to the research carried out at the CMR. His initial involvement was in coal processing under the tutelage of his Master’s supervisor Professor JP Franzidis. Subsequently he specialised in the area of flotation circuit modelling, playing a key role in the development of flotation models under the AMIRA P9 project as one of the lead flotation researchers in that international flagship project. He attended few conferences, apart from some IMPCs and his last MEI Conference was fifteen years ago at Flotation '11, although Jon has good memories of socialising with him at the Centenary of Flotation in 2005. Tributes to Martin can be found on LinkedIn.

It is a while since I undertook a serious hike on the Cornish coastal path, part of the 630 miles (1014 km) South-West Way. The Cornish section is 300 miles (480 km) long and is notoriously rugged with many up and down sections. I can cope easily with the uphill sections, but struggle going downhill due to ancient knees!

Although the north coast, exposed to the Atlantic Ocean, has the most strenuous walks, there are some tough walks on the south-east path from St. Mawes to the Devon border and I have only done a few hikes along this stretch, a tough one being Carne Beach to Portloe, then on to Portholland, and especially Mevagissey to Charlestown, probably the most demanding hike on Cornwall's south coast. This month Amanda and her rowing friend Mo, walked the 77 miles from St. Mawes to Plymouth in six days. 

Amanda at Mevagissey harbour ready for the gruelling walk to Charlestown

Replica of the Nao Santa María in Charlestown harbour.
The ship is a full-scale replica of the 15th Century sailing ship used by
Christopher Columbus on his first expedition across the Atlantic in 1492.

Although the hike is generally considered moderate overall, Amanda and Mo welcomed their overnight stops, remarking that there are definitely some demanding sections as the path constantly goes down into coves and back up cliffs, so the cumulative ascent is substantial.

A welcome stop at Portloe

Mixing with the locals in Plymouth

Luckily the weather was perfect for hiking, unlike the following weekend where the UK was hit by a heatwave, with temperatures well over 30C recorded. Temperatures reached 27C here in Falmouth, and the beaches were packed during the Bank Holiday weekend, when Jon and family called in for a few days, giving us the opportunity for a family reunion on the beach.

Falmouth's Gyllyngvase beach, Bank Holiday Saturday

Family reunion on the beach

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