Monday, 31 August 2015

Wheal Jane is still very much alive

Many of you who visited Cornwall in the 1970s and 80s will have called in at the Wheal Jane mine near Truro, which produced tin, copper, zinc and silver.

Although the mine closed in 1992, the site is still very active, and regularly visited by minerals people from overseas, but for different reasons. SGS Minerals and Wardell Armstrong International, both based on site, have extensive laboratory and pilot plant mineral processing facilities and carry out testwork for clients from many parts of the world. Only 5 months ago, as a result of client demand for a copper porphyry project in Kazakhstan, WAI purchased a SAGDesign test mill from Starkey & Associates of Canada, the first to be installed in the UK (posting of 27th March).

A few days ago I called in at SGS Minerals Services UK to catch up with two visitors from Turkey. Zafir Ekmekci I know very well, as he represents Turkey on the Editorial Board of Minerals Engineering. He and his colleague Hakan Hassoy, from Polimetal Mining were in Cornwall for 3 days to work with SGS on the evaluation of a Turkish copper-zinc ore.
With Hakan Hassoy, SGS's Varun Gopalakrishnan and Zafir Ekmekci
Nigel MacDonald (left) with Physical Separation '15 delegates

This was my first visit to the new SGS offices and laboratories, and I was most impressed, not only by the facilities but also by the enthusiasm of its relatively young 16 strong team of mineral processors, many being graduates from nearby Camborne School of Mines (CSM). Their passion and motivation is exemplified by Nigel MacDonald, who as well as being operations manager also finds time to act as a very knowledgeable volunteer guide at the King Edward Mine Museum. Nigel has worked all over the world in the mineral processing industry for the last 30 years.

Some of the SGS team: Tim Sambrook, Varun Gopalakrishnan, Nigel MacDonald,
Dave Goldburn, Mike Cook, Dominic Comybeare and Jo Byrne
SGS is a world leader in inspection, verification, testing, and certification. The mining business line consists of regional offices serving local markets each of which calls upon a network of field leaders, experts, and, when necessary, equipment, and SGS Minerals Services UK Ltd is the headquarters for the ‘wider-European’ metallurgical operations. It was born out of Holman Wilfley Associates (HWA), which originally focused on gravity separation by Holman and Wilfley tables. As time progressed the need for expanded services and technical skills saw the implementation of flotation and magnetic testing facilities which lead to the acquisition of HWA by SGS in 2009. Since 2009, SGS has made multi-million pound investment in the Cornwall office and integrated it within the wider SGS Minerals strategic vision. Priding itself upon the strong relationships it holds with other local companies within Cornwall and Devon, SGS Cornwall regularly collaborates with the Wheal Jane Group, Grinding Solutions and clients such as Wolf Minerals on their Drakelands deposit. The team attracts the top talent from the Camborne School of Mines Minerals Engineering course and is always looking for the best new talent (those interested can email their CV to

The team is passionate about progressing the mining services sector within Cornwall and is involved in a range of initiatives to support the industry within the country. SGS has had a large part to play in the provision of Geochemistry data to the new Drakeland’s mine in Devon, which will become the fourth largest tungsten mine in the world (posting of 10 July 2014). In early 2015 SGS was successful in a bid for the contract for an onsite Geochemistry lab due to its local experience and global experience in running onsite laboratories for clients across the globe.

What I found particularly interesting is that SGS Cornwall recognises the importance of retaining mining skills within Cornwall and in 2015 started several initiatives to train the next generation of Cornish engineers and technicians. Currently SGS Cornwall is operating a Metallurgical Internship programme to offer high quality mining graduates / CSM undergraduates and 3-month training placement as a transition to further study in Minerals Engineering. Demand for these internship positions has been high, with candidates applying from across the globe. Within the lab, a bespoke 2-year training scheme is being implemented for the locally recruited technicians to develop their skills to a high level. Highly skilled technicians are vital to the impeccable QA/QC for which SGS is known but also provides an opportunity for Cornish technicians to transition to careers as metallurgists.

Partnering with local education institutions is recognised within SGS as part of the company’s ethos of sustainable development through working with the communities where their offices are based. SGS Cornwall is currently in discussion with Cornwall College and Camborne School of Mines to identify opportunities to work more closely together and bring the opportunities of a career in mining to more young people within Cornwall. As these plans develop, SGS intends to keep MEI informed so that the wider mining community can hear about the great talent developing within the county.

My recent visits to WAI and SGS at the Wheal Jane site have shown me that exciting things are going to be happening for Cornish mining over the next few years and I will certainly be reporting on developments as things progress.

Thursday, 27 August 2015

An update on the Drakelands tungsten-tin mine

Charlie Northfield of Wolf Minerals has emailed to tell me that commissioning of the Drakelands process plant continued throughout July and into August (see also posting of 25th June). The primary, secondary and scavenger DMS circuits were successfully commissioned. The primary and concentrate regrind mills were also started up. Commissioning of the pre-concentrate refinery commenced with tests on the flotation cells, filter, dryer and reduction kiln. The month also saw the successful completion of 200 working days without a lost time incident (LTI). The official opening of the UK's newest metal mine is on September 17th.

Earlier this month Wolf employees and contractors enjoyed another good sundowner in the warm sunny weather at the Miners’ Arms, Hemerdon.


Monday, 24 August 2015

New Book- Comminution Handbook

One of the giants of comminution is undoubtedly Prof. Alban Lynch, who I had the honour of interviewing a year ago (posting of 11 August 2014). Amongst his many honours, last year he was inaugurated into International Mining's Hall of Fame.

I last saw him in Brisbane in 2010 where he was presented with the Lifetime Achievement Award at the IMPC (posting of 8th September 2010) and where his latest book, The History of Flotation, co-authored with Greg Harbort and Mike Nelson was launched (posting of 7th September 2010).

Great to hear therefore that a new work, set to become a seminal volume, is to be launched at Metplant '15 in Perth on September 7th. The Comminution Handbook, edited by Alban Lynch, is a new publication from The AusIMM with chapters from experts in all fields of comminution.

Most mineral processors think of grinding as wet grinding of mineral ores. On the first page Alban gently reminds us that more than twice this tonnage of cement and coal is subjected to fine dry grinding. So this text includes contributions on the whole array of crushing, grinding and classification equipment used to comminute the wide range of materials demanded by our communities. Of course, the discussion would not be complete without the explanations of sizing techniques, classification, testing and scale-up methods, mineral liberation, circuit design, process control, circuit practice and recent technology developments.  It should haunt us that more efficient devices such as high-pressure grinding rolls and tower mills were common in dry grinding at least 25 years before they were discovered for ore grinding. This book may help ensure that we don’t let that happen again.

The handbook begins with mineralogy, and reviews mineral liberation theory and quantitative analytical tools before addressing machines and circuits. Chapters 4 – 10 address types of comminution and classification machines including tumbling mills, crushers, stirred mills and HPGR, then chapters 11 – 16 cover circuit design, process control and modelling. Unlike classic mineral processing texts, this handbook gives substantial attention to comminution in the coal and cement industries as well as hard rock mining. The purpose of the book is to present comminution as it is today to those with the responsibility of improving the technology in the future.

The volume should appeal to professionals who are involved in, or have an interest in, comminution, metallurgy and related fields.

Friday, 21 August 2015

Cornish Mining Sundowner- August

A light drizzle drove us indoors for last night's Cornish Mining Sundowner at Falmouth's Chain Locker. Just over 20 people attended, exclusively Camborne School of Mines staff and students past and present. Apart from myself, past lecturers present were Phil Oliver and Tony Batchelor, and it was good to see past-Director Frances Wall, and my old mineral processing colleague Tony Clarke, one of the great driving forces behind the success of the King Edward Mine Museum. Although I did not catch their names there were a few post-graduate students present and I hope we continue to see more in the future, as the sundowner provides an ideal opportunity to network in a very sociable atmosphere, as well as to sample some of Cornwall's finest ales.

It would be good to see more current CSM staff at the sundowners. MEI's Biohydromet '16 consultant Chris Bryan was the only staff member present last night, and good also to see next year's keynote speaker, biohydrometallurgist Dave Dew in attendance. He graduated from CSM way back in 1979, as did Pete Walsh, who has now become a regular at these events.

Hopefully someone can help me out with a few names on the photos below.

Chris Bryan, Dave Dew, Tony Clarke, Phil Oliver, Nick Eastwood and Pete Walsh

Barbara Wills, Joan Oliver, Frances Wall, Barry Wills, ?, Carol Richards, ?

Dave Chilcott, ?, Malcolm Hooper, ?, Paul Burton, ?, ?, ?, Linda Batchelor, Tony Batchelor

Thursday, 20 August 2015

St. Agnes to Chapel Porth and Wheal Coates

St. Agnes beach, Trevaunance Cove

This is a fairly easy 3.3 mile walk, with an elevation gain of 720 ft, starting from the beach at St. Agnes, and leading to one of Cornwall's most photographed engine houses.

After a short steep hike up the clifftop from St. Agnes' Trevaunance Cove, the next 2 and a half miles is relatively gentle, but uninspiring cliff walking.

Above Trevaunance Cove 

Looking back towards Perranporth

Between St. Agnes and Wheal Coates
The great attraction of this walk is the opportunity of exploring Wheal Coates, the ruins of which tumble down the cliff, with one of Cornwall's most photogenic engine houses, the Towanroath Shaft pumping engine house, adjacent to the coastal path.

Wheal Coates' Towanroath pumping engine house

Looking south-west to distant St. Ives from Wheal Coates
The mine opened in 1802 and was worked until its closure in 1889. It came into full production in 1815. The surviving buildings date from the 1870s when deep underground mining began at the site. There are three engine houses that formerly housed Cornish engines. Towanroath Pumping Engine House (1872) was used to pump water from the adjacent 600 ft Towanroath shaft. Another Engine House was added in 1880 to crush ore for processing. A calciner dating from 1910-1913 roasted the tin to remove impurities such as arsenic.

In 1881 138 people were employed at the site to mine a seam of tin just below sea level but this and a subsequent period of operation from 1911-1913 were not very successful because tin production was sporadic. From 1815-1914 the mine produced 335 tons of copper and 717 tons of tin.

Looking back to the engine houses of Wheal Coates
From Wheal Coates the steep descent offers great views of the beach at Chapel Porth, and for anyone wishing only to visit Wheal Coates a good option might be to park at the National Trust car park at Chapel Porth and walk the half mile to the mine site.

The descent to Chapel Porth

More Cornish Walks

More on Cornwall

More on Cornish Mining

Monday, 17 August 2015

In conversation with Richard A. Williams

Professor Richard Williams is a remarkable man. He is currently a Pro Vice Chancellor at the University of Birmingham UK and Head of the College of Engineering and Physical Sciences, holding a Chair in Energy and Mineral Resources Engineering and leading work on large scale energy storage policy and technology.

Next month he will take over as Principal and Vice Chancellor at Heriot Watt University, a large science and engineering university based in Edinburgh, Dubai and Malaysia.

I first met Richard in 1986, when he attended the NATO Advanced Study Institute in Falmouth. He was then a Research Associate with Imperial College, UK, but it was obvious even at that early stage that he was destined for great things. In 1992 I invited him to the Editorial Board of the developing Minerals Engineering journal, a position he has held with enthusiasm and distinction ever since. But he is much more than a mineral processor. He is an academic leader, engineer and innovator, his leadership experience spanning a career developed at five UK Universities (Imperial, UMIST/Manchester, Exeter, Leeds and Birmingham) and he is one of the few engineers in UK to be an Academician of both the UK and Australian Academies of Engineering. He has particular experience at building and inspiring academic teams to develop significant new activities and business partnerships in UK and overseas locations. He has also been successful in the acquisition of global talent to build and focus research capacity and is widely networked in Singapore, Hong Kong, Malaysia and three provinces in China. His direct experience with building businesses and business awareness in UK and internationally has yielded new strong university partnerships in rail, automotive, renewable energy, nuclear, space technology and defence sectors. Some of these are cross-disciplinary reflecting the necessity for future research frontiers to address social, technical, political and economic agendas.

His academic work spans scholarly publications in chemical and mineral engineering sciences, to applied engineering and instrumentation that has created new high throughput manufacturing processes with major environmental and business benefits. He was appointed full professor aged 33 and one of the youngest Academicians and Vice Presidents of the Royal Academy of Engineering in 2000 and again recently in 2015. Amongst his many honours, awards and prizes is the Order of the British Empire (OBE) for services to science and engineering. He is on the technical advisory board of Lloyds Register Foundation.

Richard graduated from the Royal School of Mines, Imperial College in 1981 with a degree in Mineral Technology, and in 1985 with a PhD in the electrochemistry of ferrosilicon suspensions.

With fellow Imperial College students John Marsden and Cathy Evans, and their
former tutor Prof Tim Napier-Munn at the IMPC in Brisbane
After a brief period as a Research Associate, he took up a lecturing appointment at the University of Manchester Institute of Science and Technology (UMIST) and became Honorary Professor of Chemical Engineering in 1993. In 1998 he became Royal Academy of Engineering – Rio Tinto, Professor of Minerals Engineering at Camborne School of Mines, which had recently been incorporated into the University of Exeter. In 1999 he left Cornwall to take up a position as Anglo American Professor of Mineral and Process Engineering at the University of Leeds, where in 2001 he became head of the Department of Mining and Mineral Engineering. In 2005 he was appointed Pro-Vice Chancellor for Enterprise and Knowledge Transfer and International Strategy and in 2010 for International Partnerships, before taking up the role in 2011 of Head of College of Engineering and Physical Sciences, and Pro-Vice Chancellor at the University of Birmingham.

At Birmingham he continued research in minerals systems with a focus on particle adhesion and wider systems energy. He was a Director of the Manufacturing Technology Centre in Coventry and of the development of a new metallurgical activity in the form of a £60M High Temperature Research Centre in collaboration with Rolls Royce. These activities have developed the Coventry site as a major industrial campus for the University of Birmingham. In 2013 he became Professor of Energy and Minerals Resource Engineering at Birmingham, and in 2014 Honorary Professor at Taylors University, Kula Lumpur, Malaysia as part of the Grand Challenge Alliance. He is a visiting professor at Southeast University in Nanjing and at Chinese Academy of Sciences.

A characteristic of his fundamental work in particle, surface science and processing systems has been the way it has transferred to industrial practice. His early work on packing of ‘arbitrary shaped particles’ is widely cited and used in particle packing and waste management. The frustrations of visualising the invisible particle behaviour in opaque mineral slurries led to the creations and commercialisation of industrial electrical tomography, now used worldwide in minerals separation and audit, hydraulic conveying and food sectors. He was amongst the first to demonstrate desk-top use of x-ray tomography in mineralogical assessment of complex ores and multi-scale modelling of filter cakes. 
Richard with other UK Pioneers of Process Tomography, Ken Primrose, Prof Brian Hoyle,
Prof Lynn Gladden, Prof J Seville, Prof H McCann and Prof D Parker

Richard (right) and his wife Jane (left) and collaborators from the nuclear industry
receiving the Institute of Chemical Engineering prize for best innovation based company
(Industrial Tomography Systems plc) from Mr Boris Johnson

On Sky TV discussing the energy storage
and transport using cryogenic liquids
In the last ten years his interest in heat and cold transfer in nanofluids and process scale energy utilisation has contributed to new work in using cryogenic fluids to store energy, provide zero-emission transport, resulting in a National Centre for Cryogenic Energy Storage. Related commercial equipment is now being developed. In conversation recently he said “As an academic your latest research is often your best! For me this involves two topics. First, new fundamental measurements on the origin of stickiness in industrial powders. Secondly, and at a completely different scale, the adoption and wider understanding of what is now termed ‘the cold economy’ - as industries see how they can store power and create cold resource using cryogenic liquids. This has opportunity to transform energy utilisation in mining and other sectors. A story that we hope may unfold in coming years.”

As I said earlier, he is a remarkable man, and the above brief outline of his achievements only scratches the surface of his many achievements in what has been a relatively brief career to date. The wonderful thing, however, is that his many accomplishments has not changed the man within. He is still the friendly, unassuming man that I met all those years ago at the NATO conference in Falmouth, so it was a pleasure to talk to him about his life and his thoughts on the future of science and engineering.

More conversations

Thursday, 13 August 2015

Descent into a Cornish submarine mine in 1850

The remarkable photos taken by JC Burrow in the late 19th century and his accompanying notes on descending the mines with his equipment bear testimony to the hardships faced by miners working in the deep mines of Cornwall (postings of 25th May and 2nd July).
But there are few contemporary accounts of what it was like in those mines near Land's End, which worked rich copper lodes far out to sea- Cornwall's submarine mines (posting of 2nd October 2014).
A fascinating book was published in 1851 "Rambles beyond railways or notes in Cornwall taken a-foot" in which the author, W. Wilkie Collins, describes a walking tour of Cornwall with a companion in 1850, shortly before Brunel's railway line crossed the River Tamar and opened up Cornwall for mass tourism (posting of 10 December 2012).
On leaving Land's End the author describes how, walking northwards, after about 5 miles they reached the Botallack copper mine where, armed with a letter of introduction, they were escorted underground.
Approaching Botallack mines from Land's End, 2015
These were the days before portable cameras, so we must rely on Collins' vivid descriptions of Botallack, both on the surface and underground:
"We were told to go to the counting-house to present our credentials; and on our road thither, we beheld the buildings and machinery of the mine, literally stretching down the precipitous face of the cliff, from the land at the top, to the sea at the bottom. Here, we beheld a scaffolding perched on a rock that rose out of the waves—there, a steam-pump was at work raising gallons of water from the mine every minute, on a mere ledge of land half way down the steep cliff side".
The steam pump he refers to is the lower pumping engine of the famous Crowns Engine Houses. This was built in 1835 and in 1842 a discovery of rich copper ore was made in the 85 fathom (510 ft) level on Crowns Lode, extending out under the sea. This lode was the principal copper producing lode of the mine, and 7,200 tons of copper ore were produced in 1842-1845. By the time that Collins visited the mine the price of copper had fallen rapidly and tin soon became the profitable metal, the upper winding engine opening in 1862.
Botallack mines in the late 19th century......
..... and today
Collins describes the clothes that he was given for the mine tour:
"The clothing consisted of a flannel shirt, flannel drawers, canvas trousers, and a canvas jacket—all stained of a tawny copper colour; but all quite clean. A white night-cap and a round hat, composed of some iron-hard substance, well calculated to protect the head from any loose stones that might fall on it, completed the equipment; to which, three tallow-candles were afterwards added, two to hang at the buttonhole, one to carry in the hand."
As the winding engine was 12 years away, descent of the mine was by ladders, the dangers of doing this being described in the posting of 2nd July.
"We left the counting-house, and ascended the face of the cliff—then, walked a short distance along the edge, descended a little again, and stopped at a wooden platform built across a deep gully. Here, the miner pulled up a trap-door, and disclosed a perpendicular ladder leading down to a black hole, like the opening of a chimney....just as we seemed to be lowering ourselves into total darkness, we were desired to stand on a narrow landing-place opposite the ladder, and wait there while the miner went below for a light. He soon reascended to us, bringing, not only the light he had promised, but a large lump of damp clay with it. Having lighted our candles he stuck them against the front of our hats with the clay—in order, as he said, to leave both our hands free to us to use as we liked.
The process of getting down the ladders was not very pleasant. They were all quite perpendicular, the rounds were placed at irregular distances, were many of them much worn away, and were slippery with water and copper-ooze. Add to this, the narrowness of the shaft, the dripping wet rock shutting you in, as it were, all round your back and sides against the ladder - the fathomless darkness beneath—the light flaring immediately above you, as if your head was on fire—the voice of the miner below, rumbling away in dull echoes lower and lower into the bowels of the earth—the consciousness that if the rounds of the ladder broke, you might fall down a thousand feet or so of narrow tunnel in a moment—imagine all this, and you may easily realize what are the first impressions produced by a descent into a Cornish mine.
By the time we had got down seventy fathoms, or four hundred and twenty feet of perpendicular ladders, we stopped at another landing-place, just broad enough to afford standing room for us three. Here, the miner, pointing to an opening yawning horizontally in the rock at one side of us, said that this was the first gallery from the surface; that we had done with the ladders for the present; and that a little climbing and crawling were now to begin. Our path was a strange one, as we advanced through the rift. Rough stones of all sizes, holes here, and eminences there, impeded us at every yard. Sometimes, we could walk on in a stooping position—sometimes, we were obliged to crawl on our hands and knees. Occasionally, greater difficulties than these presented themselves. Certain parts of the gallery dipped into black, ugly-looking pits, crossed by thin planks, over which we walked dizzily, a little bewildered by the violent contrast between the flaring light that we carried above us, and the pitch darkness beneath and before us.
After we have walked a little farther in a crouching position, he calls a halt, makes a seat for us by sticking a piece of old board between the rocky walls of the gallery, and then proceeds to explain the exact subterranean position which we actually occupy. We are now four hundred yards out, under the bottom of the sea; and twenty fathoms or a hundred and twenty feet below the sea level. Coast-trade vessels are sailing over our heads.
One hundred and forty feet beneath us men are at work, and there are galleries deeper yet, even below that! The extraordinary position down the face of the cliff, of the engines and other works on the surface, at Botallack, is now explained. The mine is not excavated like other mines under the land, but under the sea! Having communicated these particulars, the miner next tells us to keep strict silence and listen. After listening for a few moments, a distant, unearthly noise becomes faintly audible—a long, low, mysterious moaning, which never changes, which is felt on the ear as well as heard by it—a sound that might proceed from some incalculable distance, from some far invisible height—a sound so unlike anything that is heard on the upper ground, in the free air of heaven; so sublimely mournful and still; so ghostly and impressive when listened to in the subterranean recesses of the earth, that we continue instinctively to hold our peace, as if enchanted by it, and think not of communicating to each other the awe and astonishment which it has inspired in us from the very first.
At last, the miner speaks again, and tells us that what we hear is the sound of the surf, lashing the rocks a hundred and twenty feet above us, and of the waves that are breaking on the beach beyond. The tide is now at the flow, and the sea is in no extraordinary state of agitation: so the sound is low and distant just at this period. But, when storms are at their height, when the ocean hurls mountain after mountain of water on the cliffs, then the noise is terrific; the roaring heard down here in the mine is so inexpressibly fierce and awful, that the boldest men at work are afraid to continue their labour. All ascend to the surface, to breathe the upper air and stand on the firm earth: dreading, though no such catastrophe has ever happened yet, that the sea will break in on them if they remain in the caverns below.
Hearing this, we get up to look at the rock above us. We are able to stand upright in the position we now occupy; and flaring our candles hither and thither in the darkness, can see the bright pure copper streaking the dark ceiling of the gallery in every direction. Lumps of ooze, of the most lustrous green colour, traversed by a natural network of thin red veins of iron, appear here and there in large irregular patches, over which water is dripping slowly and incessantly in certain places. This is the salt water percolating through invisible crannies in the rock. On stormy days it spirts out furiously in thin, continuous streams. Just over our heads we observe a wooden plug of the thickness of a man's leg; there is a hole here, and the plug is all that we have to keep out the sea."
And a reminder that rich seams of copper still lie below the Atlantic Ocean sea-floor:
"Immense wealth of metal is contained in the roof of this gallery, throughout its whole length; but it remains, and will always remain, untouched. The miners dare not take it, for it is part, and a great part, of the rock which forms their only protection against the sea; and which has been so far worked away here, that its thickness is limited to an average of three feet only between the water and the gallery in which we now stand. No one knows what might be the consequence of another day's labour with the pickaxe on any part of it."
And the retreat to the surface, or 'to grass':
"We next proceed to discuss the propriety of descending two hundred and forty feet more of ladders, for the sake of visiting that part of the mine where the men are at work. Two or three causes concur to make us doubt the wisdom of going lower. There is a hot, moist, sickly vapour floating about us, which becomes more oppressive every moment; we are already perspiring at every pore, as we were told we should; and our hands, faces, jackets, and trousers are all more or less covered with a mixture of mud, tallow, and iron-drippings, which we can feel and smell much more acutely than is exactly desirable. We ask the miner what there is to see lower down. He replies, nothing but men breaking ore with pickaxes; the galleries of the mine are alike, however deep they may go; when you have seen one you have seen all. The answer decides us—we determine to get back to the surface."
The 2nd edition of Rambles Beyond Railways..." is available from Amazon.

Monday, 10 August 2015

40 years of Mineral Processing Technology

It's hard to believe that 40 years ago I was hard at work writing the first edition of Mineral Processing Technology, and 40 years later Jim Finch and his team at McGill have just finished putting together the updated 8th edition, due on the shelves in October.
It's also hard to believe that all this came about by chance- writing a text-book was the last thing on my mind when I took up my post as a senior lecturer at Camborne School of Mines (CSM) in September 1974, with only 5 years' experience of mineral processing, in Zambia, and briefly with Johnson Matthey in Royston, under my belt.
At CSM my head of department was Frank Bice-Michell, a well-known authority on tin processing, the man who brought froth flotation to the Cornish mines, and author of The Practice of Mineral Dressing, a book published in 1950. But it was my fellow mineral processing lecturer, Dr. Dave Osborne, who was to have a profound influence on my subsequent career.
Dave and I got on very well right from the start, and he told me that he was thinking of writing a mineral processing textbook to replace the then standard book Mineral Processing, a voluminous text by E.J. Pryor, published in 3rd edition in 1965. He had in mind a more practical book, aimed at students, and he asked me if I would like to be involved. Rather impetuously I agreed, and we then drew up a work plan and assigned ourselves to taking responsibility for various chapters.
All went well for the first few months, until Dave decided to leave CSM to take up an appointment with Anglo Coal in South Africa, and it soon became apparent that his responsibilities there would preclude him from carrying on with the book, although he did publish the well-received Coal Preparation Technology in 1988.
By this time I was involved with setting up the new degree course in Mineral Processing Technology at CSM, and there was incentive to produce a text for the course, so I took over Dave's chapters and pressed on with the book, which was accepted by Pergamon Press and published in 1979.
Expecting it to be essentially a set of bound course notes for the new degree I was surprised by the reception that it received internationally, and its publication opened many doors for me, including visiting lectureships in Australia, South Africa, Malaysia and India, which helped me build up a network of contacts. I was also asked to write the annual review of mineral processing for the Mining Journal's Mining Annual Review, a great aid to updating the book for the next 5 editions, published in 1981, 1985, 1988, 1992 and 1997.
By the time the 6th edition was published I had left CSM to set up MEI, so was in the same situation as Dave Osborne in the mid-1970s, with little incentive to updating the book with only infrequent access to library facilities. So the book languished in the 6th edition for several years, until the new publisher Butterworth-Heinemann suggested that we appoint an editor of high international repute, who might like to update the text to take into account the rapid changes which were taking place in mineral processing.
Mineral processors had now become increasingly specialised with many researchers having little interest in areas outside their narrow fields, so there were few people who could provide the holistic approach necessary for taking on the task. One that I knew could was the highly respected Prof. Tim Napier-Munn, who was then Director of Australia's JKMRC. I knew Tim well, and he agreed to updating the book, a 'one-off' with his strong team from the JKMRC. As I expected Tim's group did an excellent job and the 7th edition was published in 2006, followed by a Chinese translation in 2011.
With Tim and the Chinese and English editions
Fully expecting the 7th edition to be the last I was not quite ready for the request from the publisher for a new edition only five years later. I had one person in mind, my old friend Prof. Jim Finch, at McGill University, Canada, who very much to my surprise agreed to set up a team to completely update the book. Jim and his team have done a marvellous job and I am pleased that this completely revamped edition is scheduled to be launched at Flotation '15 in Cape Town in November. The book is now available for pre-order, and you can obtain a 30% discount by quoting the MEI Promotion Code ATR30.

Thursday, 6 August 2015

New Book: An Applied Guide to Process and Plant Design

This is the second plant design book to be announced in the last couple of months. Unlike Metallurgical Plant Design (posting of 20 May), however, this book by Prof. S. Moran covers a wider range of application, to all branches of process engineering.

The book is intended as a guide to process plant design for both students and professional engineers. It covers plant layout and the use of spreadsheet programmes and key drawings produced by professional engineers as aids to design; subjects which are usually learned on the job rather than in education. This includes smarter plant design through the use of computer tools, including Excel and AutoCAD, "What If Analysis", statistical tools, and Visual Basic for more complex problems. The book also includes a wealth of selection tables, covering the key aspects of professional plant design which engineering students and early-career engineers tend to find most challenging.

Professor Moran draws on over 20 years' experience in process design to create an essential foundational book ideal for those who are new to process design, compliant with both professional practice and the IChemE degree accreditation guidelines.

The book is available from Butterworth-Heinemann.

Monday, 3 August 2015

In search of Dolcoath- Cornwall's greatest mine

The photograph below was taken in the early 1890s by the great Cornish mining photographer J.C. Burrow (posting of 25 May). It shows the extent of the mining activity on the north side of Carn Brea Hill, between Camborne and Redruth, as seen looking east from the top of the north stamps engine-house of the 'Queen of Cornish Mines' Dolcoath.

Dolcoath Mine started work for copper during the 1720s and of around 470 copper-producing mines in Cornwall and Devon, it became the fifth largest. But as depth increased the copper died out, and by 1832 the mine was in danger of closing. However tin ore was found deeper down at 1250 feet and the mine became the largest producer of tin in western England, reaching an output of 2000 tons per year in 1884. However by 1896 this had reduced to 1160 tons, and from 1912 it fell rapidly to only 400 tons in 1918.

Dolcoath was particularly famous for its depth, "as deep as Dolcoath" being a familiar Cornish expression to indicate anything of great depth. By 1882 the mine had reached a depth of 2,160 feet and had 12 miles of tunnels. In 1895 it took men employed in the lower levels between 2-3 hours to go down and return to the surface, so they could not work more than 4-5 hours a day. A new shaft, the Williams Shaft, was started in October 1895, intended to be the first 3,000-foot vertical shaft in Cornwall. It was completed in 1910 and came into use the next year and the mine became the largest and deepest in Cornwall, and the world's deepest tin mine, eventually reaching a depth of 3,300 feet below the surface.

In 1920 when the mine had become virtually worked out and following the tin price collapse (new deposits were also being found elsewhere in the world) Dolcoath finally closed. Like many Cornish miners, the men were in great demand for their hard rock mining expertise, and many of these "Cousin Jacks" took their skills to the new mines of North America, Australia and the gold mines of the Witwatersrand, hardly imagining that around 100 years later deep mining would mean anything up to 12,800 ft (3.9 km) in depth!

Contrast the scene in Burrow's 19th century photograph with that today from a similar but lower viewpoint, as there is now no trace of the stamps engine house. In fact very little now remains of the once intensive tin mining operations in this area, the head-gear on the left being that of South Crofty, the last mine to close in 1998, and the ruined engine house in the centre is Tincroft, which can be seen in Burrow's photo.

Harriett's Shaft
Much of the area is now derelict or taken over by housing and industrial development, and very few engine houses or shafts now remain. One of the best preserved is Harriett's Shaft Engine House, which served as a pumping house, and also for winding man-riding skips which replaced the famous Dolcoath man-engine in 1897. Nothing now remains of the nearby man-engine, which was installed in 1854 and reached a depth of nearly 1500 ft (see also posting of 25 May).

Further south, and almost hidden in dense undergrowth, are the remains of Williams' Shaft, Cornwall's deepest vertical shaft, sunk between 1895 and 1910 to meet the Dolcoath main lode.

The overgrown ruins of Williams' Shaft engine house
But nothing now remains of the once extensive dressing floors which upgraded the mined ore to produce cassiterite, or 'black tin' concentrates. The photo below shows Dolcoath's extensive use of rag frames, which were used to recover small amounts of tin from very fine material, or slimes, which were in the tailings of the buddle concentrators.

Rag frames at Dolcoath
Rag frames were simple machines comprising a wooden deck inclined at a shallow angle. The feed pulp was distributed by a board and flowed evenly down the deck where the heavier particles settled whilst the lighter material passed over a hinged tailboard and flowed to a tailing launder. Positioned above the deck was a wooden box held within a pivoted tilting frame. Water continually flowed into this box, and when full, it tipped over cascading the water over the deck to wash off the deposited material. This was deflected into a separate parallel launder by the tailboard, which was momentarily raised by the tipping water box/ tilting frame. After a few seconds the now empty box returned to its original position to start the cycle again. Many hundreds of rag frames would be linked together to form a “slimes plant” and would have been a common surface feature on many 19th and early 20th century Cornish mines. Being made entirely of wood, nothing remains of these ingenious devices, and the only place where they can now be seen in action is at the King Edward Mine Museum in Camborne.

Rag Frames at King Edward Mine Museum
Incidentally, I had always wondered why Dolcoath was always described as the world's deepest tin mine, not the world's deepest mine. In 1882 it had reached a depth of 2160 feet, so what was the world's deepest mine at that time? I was amazed when I Googled and discovered that in 1882 the world's deepest mine was in the north of England, near Manchester, in a small cotton milling town called Ashton-under-Lyne, and the mine was the Ashton Moss Colliery, with a depth of 2850 ft.

Not only was I amazed by this, I was also totally flabbergasted, as Ashton-u-Lyne was where I was born and raised, and for most of my early life prior to going to University I lived with my parents on the Ashton Moss council estate, only about a mile from this mine, which we knew as the Snipe Pit, and which closed down in 1959. I was well aware that Ashton was a cotton milling town, as the old mills dotted the landscape very much like the mining engine houses dot the landscape of Cornwall, and my mother and grandmother had worked in the cotton mills. But I was unaware that in the 19th century the town also had several deep coal mines, of which Ashton Moss was just one. Now, rather like Dolcoath, very little evidence remains- the site of the Ashton Moss mine is now a large retail park, and the only legacy is the nearby pub, the Snipe Inn, one of my many watering holes during my late teens!