Sunday, 22 July 2018

Is Ore Sorting set to replace Dense Medium Separation?

Dense medium separation (DMS)  has two principal applications: the preconcentration of minerals, that is the rejection of gangue prior to grinding for final liberation, and in coal preparation to produce a commercially graded end-product, clean coal being separated from the heavier shale or high-ash coal.
In principle, it is the simplest of all gravity processes and has long been a standard  laboratory method for separating minerals of different specific gravity. Heavy liquids of suitable density are used, so that those minerals lighter than the liquid float, while those heavier sink. Since most  heavy liquids are expensive or toxic, the dense medium used in industrial separations is a suspension in water of particles of some dense solid, ferrosilicon for metalliferous ores and magnetite for coal.
The process offers some advantages over other gravity processes. It has the ability to make sharp separations at any required density, with a high degree of efficiency, even in the presence of high percentages of near-density material. The density of separation can be closely controlled, and can be maintained under normal conditions for indefinite periods. The separating density can be changed as required and fairly quickly, to meet varying requirements.
Preconcentration is most often performed on metalliferous ores that are associated with relatively light country rock, such as silicates and carbonates. Lead-zinc (galena-sphalerite) ores are often pre-concentrated by DMS and it was commonly used with some of the Cornish tin ores, the cassiterite being found in lodes with some degree of banded structure, associated with other high-specific-gravity minerals such as the sulfides of iron, arsenic, and copper, as well as iron oxides. The lode fragments containing these minerals therefore have a greater density than the siliceous waste and allow early separation.
Typical DMS circuit
The process is, however, rather expensive, mainly due to the ancillary equipment needed to clean and recycle the medium, and the cost of the medium itself, and a viable alternative is electronic ore sorting, which is increasingly being used in the mining sector in order to reduce the amount of waste processed through the comminution circuit thus boosting the overall ore grade.
Last week it was reported that two tin operations are planning to use ore sorters as their method of preconcentration. Metals X and its joint venture partner Yunnan Tin have commenced commissioning of its new crushing and ore sorting facility at the Renison tin mine in Tasmania, Australia (MEI Online). The ore sorting equipment, provided by TOMRA, is expected to increase annual tin production at Renison by 15-20%, the TOMRA X-Ray transmission ore sorter expected to reject an estimated 200,000 t/y of waste at the crushing stage, upgrading the ore before the processing plant.
Also reported on MEI Online, the results of the definitive feasibility study on Kasbah Resources’ majority owned Achmmach tin project in Morocco have proven favourable enough for management to push forward into development, and it looks like being another operation to benefit from ore sorting technology. The plan has the ore sorter reject rate kept nominally to 40% of new feed, which will mean the positively sorted ore from the sorter, termed the “accepts”, will report to the downstream processing circuits. The company has carried out two phases of ore sorting testwork on the project, with the second phase involving sorting two tonnes of representative ore through a full size Steinert KSS multi-sensor ore sorting machine in Perth, Western Australia.
This could be great news for Cornwall, with the South Crofty tin mine revival under way. Up to its closure in 1998 South Crofty had used DMS to pre-concentrate the ore, as did the Geevor tin mine which closed eight years earlier. It will be interesting to see if electronic ore sorting is considered for the new processing circuit at South Crofty, and hopefully we may find out more at Physical Separation '19 next year. Both TOMRA and Steinert, the leading players in sorting technology, were major sponsors of Physical Separation '17, and I am sure they will be at next year's event with updates on this increasingly important technology.
The latest news on Physical Separation '19 can be found at #PhysicalSeparation19.
Twitter @barrywills

Friday, 20 July 2018

More good news for Cornwall at the July mining sundowner

A warm summer evening attracted over 30 mining folk to last evening's Cornish Mining Sundowner at Falmouth's Chain Locker. We were pleased to welcome to her first sundowner Maureen Atkinson, widow of former Camborne School of Mines (CSM) Director Prof Keith Atkinson, who sadly died last August (posting of 6th August 2017).
Maureen Atkinson (2nd left) with Linda Shimmield, Barbara Wills and Joan Oliver
There are always surprises at these sundowners, and no more so last night than the very welcome appearance of Glen Corder, from the Sustainable Minerals Institute (SMI) of the University of Queensland (UQ). Glen was accompanied by Talitha Santini, formerly with SMI, now with the University of Western Australia. They have been in Cornwall this week for the UQ-University of Exeter workshop for sustainable critical minerals, and working on potential collaboration with CSM. Glen and Talitha are pictured below with CSM's Frances Wall, who will be presenting a keynote lecture at Process Mineralogy '18 in November.
Frances, Talitha and Glen
Also nice to catch up with Dave Goldburn, Business Development Manager at Holman-Wilfley Ltd, and to thank him personally for their recently announced sponsorship of Physical Separation '19 in Falmouth next June.
Dave Goldburn (right) with retired mineral processor Steve Barber
It was good to talk to James Strong of Comminution '20 sponsor Grinding Solutions Ltd (GSL), to find out more of their alliance with Arq, who has committed to invest in a new technology and innovation centre at GSL to benefit from its hard rock ultrafine grinding technology and fine particle science culture to apply it to coal and fuels.
Arq will apply the cross functional use of long-standing minerals processing capabilities to optimise its own breakthrough energy technology which transforms the discard produced by coal mines into a new source of low cost energy. This novel process, Arq Technology™, involves the reclamation of extracted materials from coal mining underflow or legacy discard and then grinding it down to particles of 5 microns or less which can then be separated into over 99% pure hydrocarbons and inorganic material (ash). This microfine hydrocarbon (Arq Fuel™) is said to be far more valuable than traditional coal because it can contain less than 1% ash and almost no water.  This increase in value has the potential to change the face of the coal business across the world and Arq has partnered with GSL to develop and manage the Arq Technology Centre which has additional scope for future expansion.
James, who is commercial manager of GSL, said last night:  "We are proud to partner with Arq whose exciting new technology is set to change the global energy industry. The Arq Technology Centre leverages Grinding Solutions’ culture of innovation, expertise and experience and we are excited to transfer established technology from adjacent industries to make the world’s resources go further".
GSL continues to expand, and now has a force of 16 at its premises near Truro, which includes 12 metallurgists. In the last couple of weeks two new technical personnel were added to the staff, Adam Skitt, a Project Metallurgist back from working in Australia and Teresa Norejko, a Junior Chemical Engineer who recently obtained an MEng in Chemical Engineering, and it was good to welcome Teresa to her first sundowner. GSL are also constructing new laboratory and office facilities which will open later in the year and will continue to add to the staff to support this growth.
With GSL staff John Rumbles (metallurgist), Debbie Partridge (Business Administrator),
James Strong, Teresa Norejko and Jamie Goodship (Junior Metallurgist)
All in all an excellent sundowner, and apologies that I did not get round to photographing everyone- Barbara says I was talking too much (a touch of irony there!).  Anyway, we hope to catch up with everyone again at the next sundowner, at the Chain Locker again, on August 16th, starting 5.30 pm.
Twitter @barrywills

Wednesday, 18 July 2018

Cornish company Holman-Wilfley is the first major sponsor for Physical Separation '19

We welcome back Physical Separation ‘17 sponsor Holman-Wilfley Ltd,  continuing their long-standing relationship with MEI by sponsoring next year's Physical Separation ‘19 in Falmouth.
Since Physical Separation 17 the company has been busy shipping its Laboratory 800 tables to nearly 50 universities and mining companies, with the industrial 7000 Wilfley machines going in to several large recycling projects in Scandinavia and southern Europe. The industrial sized Holman tables have had further units installed to upgrade capacity at Drakelands tungsten-tin mine in Devon and Holman 8000 tables have also being shipped to various mines around the world, including the expanding tungsten operations in Spain, and projects from Australia to Vietnam.
7000 Wilfley installation in Sweden
Holman 8000 installation in Spain
Managing Director Chris Bailey tells me that the company has planning consent to expand its Redruth facilities, and this will include creation of a purpose built in-house testing facility which will shortly be under construction. "We look forward to catching up with the various customers and our friends and discovering what developments in the science of physical separation has occurred in the last two years" says Chris.
As a major sponsor, Holman-Wilfley joins our industry advocate CEEC, and media partner International Mining in a now very dynamic mining atmosphere in Cornwall.

Updates on the conference can be found at #PhysicalSeparation19.
Twitter @barrywills

Sunday, 15 July 2018

Minerals Engineering: end of term report

The new look Minerals Engineering was launched in January of this year, with the merger of the journal with International Journal of Minerals Processing (IJMP) after 30 years of running separately, in the early days not too comfortably (posting of 22nd January).
Minerals Engineering's final report, for 2017, shows that the Impact Factor (IF) is still rising, to 2.707, retaining the journal's position as the world's  #1 mineral processing journal. It is good to see that the specialist journal Hydrometallurgy has also improved its impact factor to 3.3, so congratulations to Jochen Petersen and his editorial team.  
 In my opinion, more important than IF is the number of ScienceDirect downloads, over 558,000 in 2017, the increasingly high proportion from China highlighting the importance of this country to mineral processing research.
The number of papers submitted to the journal continues to increase, but of the 1254 papers submitted last year, 82% were rejected, a record number, suggesting that the pressure to publish is increasing the number of hastily prepared manuscripts.
As can be seen from the figures below, the number of papers from Asia, mainly China, continues to increase, but the rejection rate of Asian papers, while decreasing, is still too high.
It is interesting that the rejection rate of special issue papers was, by comparison, only 53% in 2017, and is 36% for this year to date. There are good reasons for this. The special issues (now virtual special issues) are, apart from a very few, papers presented at MEI Conferences. These essentially go through two review processes before submission to the journal. They are vetted by MEI and our consultants prior to acceptance for conference presentation, and then the draft papers which are submitted to the conference for discussion are revised by the authors after the conference before journal submission.
It will be interesting to see how the new journal progresses this year. Paper flow continues to increase, but unfortunately it is becoming more and more difficult to find researchers who are willing to spend valuable time refereeing papers. Many academics are keen, sometimes desperate, to have their papers reviewed for publication, but are unwilling to act as referees for others. This problem is exacerbated by the new laws on Data Protection, which does not allow editors to register new reviewers. Instead we have to contact potentially suitable reviewers and request that, if they are interested, they register themselves in the system. This is time consuming and leads to a further increase in average reviewing time for papers.
So I would like to conclude my summary of the journal report by thanking all those specialists who do give up some of their valuable time and contribute whole-heartedly to the valuable peer-review process. Here's to 2018 and beyond!
Twitter @barrywills

Thursday, 12 July 2018

The Zambezi: the perfect setting for a mining sundowner

We have been lucky enough to have been involved with many mining sundowners already this year, in some beautiful venues in Cornwall, Cape Town and Namibia, but slowly cruising the Zambezi, separating Zambia and Zimbabwe, is probably one of the greatest sundowner experiences.
Below are a few photos taken yesterday evening by Amanda, on the Cu-Co Africa River Cruise, which was sponsored by one of MEI's Flotation '19 supporters Axis House.
 

Wednesday, 11 July 2018

Zambia: Looking back a few years

Amanda and a few Cu-Co Africa delegates strolled down to Victoria Falls yesterday afternoon, and the photo suggests that the water flow is very much higher than it was at the same time three years ago, when I also photographed delegates by the Eastern Cataract:
Amanda (4th left) with delegates yesterday.........
.....and delegates at the same conference in July 3 years ago
And looking back even further; Amanda looks very much at home in the Livingstone shabeen below, thanks to her early training in Chingola way back in 1972, shortly before she left Zambia for the UK. She is clearly enjoying her first visit back to Zambia!
 

Tuesday, 10 July 2018

Copper-Cobalt Africa off to a great start

The bank of the Zambezi River was a perfect setting last night for the welcoming cocktail party at the SAIMM conference, held in association with the 9th Southern African Base Metals Conference.
MEI's Amanda was, of course, very much involved with the great networking opportunities, and has sent these photos, just a few of many that she will be posting on a 'people' blog when she returns from Zambia next week. I look forward to that, as over 290 delegates are registered for the event!
Conference chairperson Kathy Sole, with Lennart Scheunis of Umicore
Amanda with the Outotec delegation
 

Monday, 9 July 2018

Sizzling Sunday

The UK is basking in its longest heat wave in 5 years, and yesterday was particularly hot. I took a long slow bike-ride, passing two of Falmouth's main beaches, which looked splendid under a clear blue sky.
Falmouth's Swanpool Beach
Gyllyngvase Beach

Jon, along with 10,000 other cyclists, was enduring the 88 mile Velothon Sportive in Wales, said to be the most spectacular cycling event in UK, with temperatures over 30 C enhancing the challenge of the elevation gain of over 5000 feet.
Jon and his friend Matt in Wales

Amanda, meanwhile, was relaxing in Zambia, at the Avani Victoria Falls Resort in Livingstone. This is Amanda's first visit to the land of her birth since she left Chingola in 1973 as a one-year old. She is representing MEI at the SAIMM Copper-Cobalt Africa conference, which begins this evening.
Amanda and friends relaxing by the pool
A great view of The Smoke that Thunders, from the bank of the Zambezi
 

Friday, 6 July 2018

A brief visit to Cornwall by Magotteaux's Chris Greet

Every mineral processor is, or should be, aware that flotation efficiency is very much linked to the product from the upstream comminution circuit. Nevertheless it is common at large conferences, such as IMPCs and SMEs, for flotation and comminution sessions to run in parallel, such that there is little opportunity for specialists in these two areas to discuss comminution-flotation as a single entity. 
I am also aware, of course, that MEI's focussed comminution and flotation conferences, by attracting specialists in these two fields, do not encourage potential fruitful collaboration. This is something that we are trying to change by inviting specialists in comminution to present appropriate work at flotation and vice-versa. It is happening only slowly however, but one company that sets an example is Magotteaux, regular sponsors of MEI's comminution and flotation series. Dr. Chris Greet, Manager Metallurgy-Minerals Processing Research at Magotteaux Australia, has presented papers at most of the flotation conferences, and in recent years the comminution conferences, highlighting the intimate link between flotation and comminution, not only in regard to the size and liberation of particles, but also to pulp chemistry.
Chris (right) in full flow at Flotation '13
So important is pulp chemistry that Magotteaux designed a laboratory mill which reproduces the pulp chemical conditions of the plant grinding mill in the laboratory. The Magotteaux Mill® allows the user to investigate the impact of grinding chemistry on their metallurgical process. The product generated in the laboratory has nominally the same physical properties (particle size distribution) and pulp chemical properties (Eh, pH, dissolved oxygen, oxygen demand and EDTA extractable iron) as an equivalent sample taken from the plant. This signifies a distinct advantage in testing as the results produced in the laboratory are more representative of those that would be observed in a plant.
The UK company Grinding Solutions Ltd (GSL), regular sponsors of MEI's Comminution conferences, are also very aware of the link to flotation, and a couple of years ago took possession of the Magotteaux Mill in their rapidly expanding premises in Cornwall.  They have found that the mill enhances significantly the ability to monitor chemical conditions during milling, which allows greater understanding, and improvement, of flotation performance response.
Chris spent the day with GSL yesterday, a first and very brief visit to Cornwall, a welcome detour on his way from Dusseldorf to Johannesburg, and Barbara and I enjoyed a great meal with him, and Nick and Flee Wilshaw of GSL, in the most beautiful of settings overlooking Falmouth's Swanpool Beach.
Me, Chris, Barbara, Flee and Nick at Hooked on the Rocks, Falmouth
Twitter @barrywills

Wednesday, 4 July 2018

Provisional programmes for Process Mineralogy '18 and Hi-Tech Metals '18 published

Process Mineralogy '18 and Hi-Tech Metals '18 will run back to back at the Vineyard Hotel in Cape Town in November.
Sundowner in the Vineyard Hotel Gardens

Process Mineralogy '18 is the 5th in the well established series, and is sponsored by ZEISS, Bruker, Thermo Fisher Scientific and iMin Solutions. The media sponsor is International Mining. The provisional programme can be found here.
Current Process Mineralogy '18 sponsors
Hi-Tech Metals '18 is a brand new MEI Conference, and, as expected, is off to a fairly quiet start. The provisional programme can be found here.
Programmes for both conferences will evolve over the coming weeks, so if you would like to present papers at either, or both, events, please let me have your short abstracts as soon as possible.
The very latest updates on the conferences can be found at #ProcessMineralogy18 and #HiTechMetals18.
 

Sunday, 1 July 2018

Wheal Peevor- a forgotten historical mining gem

Remarkably few people that I talk to in Cornwall have heard of Wheal Peevor, which is situated in a remote area 1.5 miles north-east of the once rich mining town of Redruth. Largely overgrown and forgotten until 2003, Wheal Peevor was the subject of an £810,000 grant to repair, protect and preserve this important site, which was open to visitors in January 2008.
The mine site is extraordinary because it is a rare example of what was once ordinary, and the network of tracks and trails around the site, along with way finder points and very informative information boards, give a real insight into the history behind the landscape and the present-day diversity of the wildlife and flora.
Strategically placed information boards
So impressed was I when I first saw it, only a few weeks ago, that we will be incorporating a visit into the programme of next year's Physical Separation '19.
The once impressive entrance to Wheal Peevor
The five hectare site is unusual because it is the only 3 engine house mine site in the important central mining District around Camborne and Redruth. It contains the remains of three engine houses: the largest engine, with a 72 inch cylinder, was used for pumping water out of the mine; the second, used for winching material in and out of its shaft and the third, with a 32 inch engine, operated 48 heads of Californian stamps for crushing the ore, which was then treated in buddles, and the concentrate calcined to remove arsenic, the ruins of the processing plant also being part of the trail.
The stamps, pumping, and winding engine houses
The winding engine house viewed from the pumping engine house interior
The remains of 20th century Frue vanner foundations in front of the Stamps House
Wheal Peevor was a very wet mine underground, records stating that there were at one stage three Newcomen Engines working on the sett in an attempt to de-water the mine. By the early 19th century it also had the advantage of being drained by the Great County Adit, a network of over 40 miles of interconnected adits which drained over 100 mines in the district, before emptying into the Carnon River near the village of Twelveheads.
The mine was being worked for copper at shallow depth in the late 18th century, but when the copper price slumped after 1788, rich tin deposits were discovered at depth underlying the copper. The tin ore assayed at about 4% as opposed to the more usual 1-2% and fortunes improved, and in its heyday Wheal Peevor employed 186 men underground and about 135 people on the surface. The mine struggled on through the 1880s but by the late 1880s it was no longer economically viable and was abandoned. However attempts were made to re open it in 1912 and 1938 primarily for the extraction of wolfram.
Although Wheal Peevor was a relatively small mine it had been extremely rich, producing 3280 tons of cassiterite, 5 tons of 4% copper ore, 7 tons of pyrite and 12 tons of arsenopyrite between 1872 and 1889.

Twitter @barrywills  #PhysicalSeparation19