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.

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.

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!

New Book- Plant Auditing

Plant Auditing: A Powerful Tool for Improving Metallurgical Plant Performance is the first book ever written to show how to get maximum benefit out of an audit. This comprehensive guide is easy to follow with numerous charts and checklists. It walks the reader through the complexities of setting up the right kind of audit, the type that will provide actionable steps to profitable outcomes. Also included are 20 case studies illustrating real-life problems typically encountered at plants that can be resolved through the audit procedures described in this book. 

The author, Deepak Malhotra, has more than 30 years of experience in metallurgical and mining auditing. A Gaudin Award recipient, he is eminently qualified to write this first book on plant auditing.

Since leaving AMAX in 1990, he has been president of Resource Development, Inc., a mining and metallurgy consulting and testing firm. He has served in several SME leadership positions, including chairing several international symposia.

The book is available from the SME.

Nickel, Cobalt and Precious Metals Conferences

MEI has for several years been a media partner for the ALTA series of conferences, held annually in Perth, Australia. These conferences are held over 5 days in May and cover the processing of nickel, cobalt, precious metals, copper, uranium and REE ores.

MEI's Precious Metals and Nickel-Cobalt conferences are held back to back over 4 days and this year were also held in May, which with hindsight was not a great idea.

In order to separate the two conferences, and to give workers in these fields the opportunity of networking with workers in opposite ends of the world, the next conferences in the MEI series will be held in October 2016, often a good time of year in Falmouth.

Precious Metals, and Nickel and Cobalt Processing are MEI's smallest conferences, but they provide excellent networking opportunities (see reports on Precious Metals '15 and Nickel Processing '15), with delegates from many countries discussing innovations and common problems with the aim of optimising plant operations. This is particularly important at times of depressed metal prices, and they could not be more depressed than at the present time, with the gold price recently falling to a 5-year low (see also an interesting discussion on LinkedIn- Low Metal Prices- Problem or Opportunity?). So we look forward once again to researchers and operators from around the world meeting in Falmouth in 15 months time.

Delegates at Precious Metals '15 relaxing in Falmouth

Full details of the conferences, including Calls for Abstracts, can be found at Precious Metals '16 and Nickel and Cobalt Processing '16.

July Cornwall and Devon Sundowners

Falmouth's Chain Locker pub was probably a hard act to follow after my two previous sundowners this month in the most exotic of locations, by and on the Zambezi River in Zambia (posting of 13th July). But it was good to be back at the quayside last night to meet up with around 20 regulars and a few CSM students who were celebrating their graduation this week.

On 3rd July over 30 Wolf employees, contractors and visitors congregated at the Miners’ Arms, Hemerdon to celebrate the start of ore commissioning at the Drakeland's Tungsten-Tin mine (see also
posting of 25th June), and Process Plant Manager Charlie Northfield has sent me this update:

Commissioning of the Drakelands process plant commenced on 23 June with the first ore introduced at the ROM bin. Commissioning of the primary and secondary crushers, rotary scrubber and tertiary crushers has been successfully completed. Commissioning of the fines gravity circuit including the deslime cyclones, spiral concentrators and shaking tables has also been completed. Preparations for commissioning of the DMS (dense medium separation) circuits is well advanced.

Renowned tin and tungsten expert Ron Goodman joined the team of consultants assisting the commissioning team. Ironically Ron assisted in the commissioning of the Wheal Jane tin processing plant in 1971 – the last metal mine to open in the UK! Ron is shown below (centre) with former AMAX project manager Roger Craddock (left) and AMAX mining engineer Paul Lister (right).

GR Engineering Services celebrated a successful week of commissioning. Shown below are process engineers Sean Sara, Alan Bax, David Ng, Graeme Perkins (commissioning manager) and Steve Hoban.

Wolf employees Henry Chalcraft, Andrew Harry, Adam Bromley,
Joseph Bentley and Tony Delany

Management software consultant John Ferris with Wolf Minerals’ Operations Manager Jeff Harrison and CFO Richard Lucas

Wolf’s Tania Bradford (training officer), Amy Hatswell (HR administrator), Dawn Parish (Senior HR officer) and Kerry Dee (HR Manager)