Official Opening of the Drakelands Tungsten-Tin Mine

Fourteen months ago I called in at the Wolf Minerals' Drakelands Mine at Hemerdon, near Plymouth, (posting of 10th July 2014) to see how things were progressing on the building of the processing plant with its interesting flowsheet (posting of 25th June). The site was certainly a hive of activity and commissioning took place ahead of schedule, at the end of June.

The processing plant site in June 2014

Speaking at the last CSM Annual Dinner (posting of 15th March) Wolf Minerals Managing Director Russell Clark said that there had been little local opposition to the mine. “People think that as you’re on Dartmoor, there must be protests. I have never seen support like this. We’re lucky we are in an area that has a mining history. A lot of local people are used to seeing a pit, used to seeing a quarry, and they recognise it’s good for the economy.” 

Production of tungsten is dominated by China, which has about 60 per cent of global reserves, but Drakelands could be the biggest tungsten mine in the Western World. However, since my last visit the price of tungsten, like most metals, has fallen markedly and Russell recently said that if prices were going to stay where they are now for the next 20 years the mine probably would not have been built, but he doesn't believe they will. In a recent interview in The Times (September 2nd 2015) he insisted that the market was at its lowest ebb. "There's going to be a point where people need to go back to the global market. At that point there will be a spike in the tungsten price and we should be in the perfect position to deal with it" he said. There are already signs that the weak market is forcing high-cost operators to shut down, and some private Chinese producers are beginning to close their operations.

No matter what happens, today was a very significant date in the mine's history, and I was privileged to be invited to the mine's official opening ceremony. Prior to that I joined the tour of the processing plant organised for media and brokers, and I was very impressed by how things have progressed since my last visit 14 months ago, the plant now producing 20 tonnes per week of tungsten concentrate.

Due to the high density of wolframite and the by-product cassiterite, gravity concentration dominates the flowsheet, DMS cyclones, spirals and shaking tables producing a combined W-Sn concentrate, from which arsenopyrite is removed by froth flotation.

Crucial to the flowsheet is a kiln which roasts hematite to magnetite, which is removed by low-intensity magnetic separators, before high-intensity magnetic separation separates the tungsten concentrate from the tin concentrate, the latter providing about 10% of revenue.

The DMS cyclone plant

DMS Cyclones

Tables and spirals

Shaking table

Comminution Handbook Launched at MetPlant '15

The Comminution Handbook (posting of 24th August) will be a welcome addition to the bookshelves of many practicing metallurgists and process engineers, as it has been many years since there has been a new publication of kind. Its sixteen chapters are structured around the themes of breakage characterisation, processing equipment, circuit design and process optimisation and control.

Edited by Prof. Alban Lynch, with contributions from 38 world experts, the book was launched last Monday in Perth, on the first day of MetPlant '15 organised by the AusIMM (see MEI Online for report on the conference). MEI was a media partner for the conference and I wish I could have attended to meet members of the Lynch family who were there to launch the book. Due to a recent fall, Alban could not be there in person, but his son Martin, daughter Suzy and grandson Clem were, together with his daughter-in-law Elizabeth (married to son Patrick, who was away.

Also in the photo below, kindly supplied by Suzy, are Janine Herzig, who officially launched the book on behalf of the AusIMM, and Greg Lane, a valuable contributor to the book, from Ausenco.

Clem Lynch, Martin Lynch, Janine Herzig, Greg Lane, Suzy Lynch-Watson and Elizabeth Lynch

I believe the book is set to become a seminal volume, and the MetPlant conference delegates clearly agreed, all 56 copies brought to Perth by the AusIMM staff being sold on the spot, with back-orders taken for many more. 

Zeiss Mineralogic Mining comes to Cornwall

Last week I reported on my visit to the impressive SGS Minerals Services laboratories at Wheal Jane, near Truro. Their mineralogical support is provided by Petrolab in nearby Redruth, whose local clients also include Wardell Armstrong International and Grinding Solutions, as well as Wolf Minerals' new Drakelands mine in Devon.

I called in at Petrolab last week to look at the installation of their new Mineralogic Mining automated mineralogy system (MEI Online), being installed by Al Cropp and Ben Tordoff of Zeiss. Both Zeiss and Petrolab are major sponsors of MEI's Process Mineralogy '17 and Zeiss is providing the same corporate support for Flotation '15 and Comminution '16, highlighting the company's current high profile in terms of innovation and industry presence.

Zeiss has worked very hard to make the Mineralogic platform versatile and robust in terms of method of analysis, automation and reproducibility. This versatility means that Petrolab can provide the latest innovative solutions and support for their metallurgical test programs. Petrolab Director James Strongman told me that, looking forward, he wants to see automated mineralogy become an integral part of all aspects of the mine from exploration and feasibility to environmental impact and remediation, and in collaboration with the application team at Zeiss he is very excited about the opportunities ahead.

Petrolab is actively involved and very keen on collaboration with academic research, and is currently supporting PhD research at the University of Plymouth into REE mineralisation and a recently completed MSc with Camborne School of Mines looking at the gravity and magnetic response of some rougher table feed samples supplied by Wolf Minerals. The MSc was very successful and James is now looking to take the student Jake Harrison on full-time as a junior mineralogist and lab assistant.

The link with CSM is an important one, and not surprising as Petrolab was founded in 1991 by Dr. Alan Bromley, who I worked with for many years at CSM. He was an inspirational geologist with a real interest in mineral processing, and a lecture that he gave way back in 1975 "A geologist looks at mineral processing" had a profound influence on the way that I also looked at mineral processing, as he showed that mineral processors should have a thorough knowledge of the mineralogical composition of their ores and concentrates. Now this is obvious, but at the time I had left Zambia only a couple of years before and during my time on the Nchanga Concentrator it is hard to believe now that, despite the wide suite of copper minerals, there was not even an optical microscope in the metallurgical office. If the tailings assay was creeping up, the answer was to add a little more reagent to the head of flotation, with little thought that the high assay may have been due to poor grinding, or the presence of poorly floating minerals.

It was great to see Alan at Petrolab. He sold the business to James in 2006, and John Fletcher joined James as co-Director in 2007. Alan had nothing but the highest praise for what they have done over the past decade, their impressive staff now comprising the two directors, two mineralogists, one software engineer and a thin section technician.

At Petrolab with Ben Tordoff, John Fletcher, Alan Bromley, Al Cropp and James Strongman

It is really good to see all the collaboration that is taking place now in the very dynamic minerals sector in Cornwall, and expect to hear much more of Petrolab and others in the future.

European Symposium on Comminution and Classification

Today is the first day of the ESCC2015 Conference, held in Gothenburg, Sweden. MEI is the official media partner, but as I was unable to attend I am grateful for this short report sent by the Local Organising Committee:


Professor Magnus Evertsson from Chalmers University of Technology began the conference by talking about that the long term sustainability and energy use is a unifying theme for the ESCC 2015 symposium. During the last century humankind has transformed from being a small world on a large planet to being a large world on a small planet. The debate around global warming and climate change is intensified. We do need to find sustainable solutions that are truly long term. A fossil free world is claimed by some researchers to be within reach in 35 years. To achieve that goal or at least to work in that direction, researchers in academia and industry have to join forces and we all need to contribute and cooperate to find smarter, cooler and more technically advanced solutions to our needs.

The first keynote speaker of the day was Professor Luis Marcello Tavares (Universidade Federal Rio de Janeiro) with his presentation about Advanced Modeling of Ball Mills, followed by Greta Fragnière (TU Braunschweig) and her presentation about Evaluation of a Mechanistic Model for Prediction of Breakage Rates Through Simplified Test Material and Malcolm Powell (University of Queensland) who talked about The Effect of Loading Rate in Single Impact Particle Breakage using High Velocity Breakage Device.

Todays sessions will cover the themes:
* Comminution and classification of industrial minerals, cement, ores and secondary materials.
* Grinding, dispersion and classification of fine particles
* Fundamentals, modelling and simulation

This seems to be the season for comminution conferences. MEI was also a media partner for last month's International Comminution & Classification Congress in Mexico, but my attempts to get there were thwarted by problems with my BA flights. In just over a week's time I will be in Vancouver to report on SAG '15. And then, of course, the end of next month is the deadline for abstracts for MEI's Comminution '16 in Cape Town.

Comminution '16 Final Call for Abstracts

With mining companies having to tighten their belts in these hard times, the importance of optimising comminution, the most energy intensive operation in mineral processing, becomes ever more important.

Comminution '16, which will be held in Cape Town in April is the 10th in MEI's conference series, which have continued to grow, Comminution '14 attracting 226 delegates from 27 countries (see full report and pictures, and comments from delegates, in posting of 23 April 2014).

Reflecting the need to reduce energy and increase the efficiency of comminution, we now have the backing of the Coalition for Eco-Efficient Comminution (CEEC) as Industry Advocate, and already 16 companies are providing major corporate support to what we are sure will be another opportunity for experts from around the world to discuss new ideas and common problems.

For the first time we will be inviting plant operators to submit short abstracts and to take part in a session devoted to short presentations describing how innovative techniques have benefited their circuits. Operators can derive tremendous benefits by taking part in a conference such as this and highlighting their operations. As Clifford Mutevhe, of Anglo American Platinum commented: "Comminution '14 not only enhanced my knowledge but also helped me identify solutions to the milling circuit I manage. Some of the discussions we had, we have carried them forward as part of the business process improvements. I also managed to identify with a huge pool of knowledgeable people from across the world. I could not imagine communicating daily and interacting with people from SA, USA, France, Iran, China, Australia and various other countries. Some have become my friends, importantly."

Those who wish to present in the formal technical and poster sessions will also be required to submit draft papers before the conference. These unrefereed papers will be available to delegates on USB sticks. After the conference, authors will be invited to submit final papers, which will be peer-reviewed with a view to publication in a special issue of Minerals Engineering, the world's number 1 mineral processing journal. The deadline for abstract submission is the end of October.

Highlights of the technical sessions will be three keynote lectures from world renowned experts in comminution, Joe Pease of Mineralurgy Pty Ltd (posting of 15 January), Australia, Prof. Malcolm Powell of Australia's JKMRC, and Rob McIvor of Metcom Technologies Inc., USA (see posting of 1 June). Joe and Rob will also be presenting two workshops on the Sunday before the conference which will be of great value to plant metallurgical staff and management, grinding circuit equipment and material suppliers, and others interested in design and optimisation.

As always the conference will be held in Cape Town's Vineyard Hotel, its superb gardens under Table Mountain providing the perfect setting for the extended coffee breaks, lunches and happy hours, intended to give delegates the opportunity of relaxing and networking in the best of conditions.

The view from the Vineyard conference centre

Lunches will be served in the exhibition area, where 13 of the 23 booths available have already been reserved.

Last year at Process Mineralogy '14 we held the conference dinner at nearby Kirstenbosch Botanical Gardens and this was a great night of good food, wine and entertainment, so we look forward to the Comminution '16 dinner in this unique setting.

Kirstenbosch Botanical Gardens

All in all, a conference not to be missed and we look forward to seeing you at the Vineyard next April.

Porthtowan to Chapel Porth

This is a superb short walk, only 1.3 miles, between two of Cornwall's most picturesque little coves. For those wishing to walk from Porthtowan I would suggest that you extend the walk for another half a mile and take the steep hike up the cliff from Chapel Porth beach to the iconic Wheal Coates (posting of 20 August ), its Towanroath pumping engine house arguably being the most photographed in Cornwall, as it is more accessible than the famous Crowns Engine houses at Botallack (posting of 16th April).

There is also much evidence of mining activity just north of Porthtowan, although little remains now of Wheal Charlotte, which was worked not very succesfully for copper in the early 19th century, except for a crumbling engine house and a few spoil heaps.

Apart from the steep climb up the heavily eroded footpath from Porthtowan, this is a fairly easy little walk, with some great north coast scenery, particularly looking down to the beaches of Porthtowan and Chapel Porth, and the superb view looking north when approaching Chapel Porth of the not too distant Wheal Coates.

Porthtowan beach

The crumbling remains of Wheal Charlotte

Descending to Chapel Porth, with the view of Wheal Coates across the valley

Chapel Porth beach

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