Monday, 23 January 2017

Report on the 2017 Canadian Minerals Processors Meeting

Our old friend Dr. Norman Lotter of Flowsheets Metallurgical Consulting Inc., Canada, was at last week's 49th CMP Meeting in Ottawa, Canada, and has kindly supplied us with this short report on the event:
A total of 537 delegates attended the CMP Meeting, from 11 countries. The plenary was entitled “The Need to Innovate: Celebrate the Past…Look to the Future”. Day 1 was spent on comminution; day 2 on flotation; and day 3 on gold and some innovations. In my view this was the strongest technical programme that I have seen at the CMP in five years.
Charlotte Gibson with Spencer Reeves
of Starkey and Associates
An interesting paper on reducing the dilution of spodumene concentrate with iron silicates by magnetic separation was presented by Dr. Charlotte Gibson, of SGS Canada.
Ed Wipf
A development in vibrating screen design at operations scale was reported by Ed Wipf, of EdRockMan IV, in which particularly the problem of classifying SAG mill discharge at a high tonnage has become a key problem because of wear and temporal overload situations. The new design is called Two-Mass Screens, and has rearranged the screen into a double-deck driven by a different mechanism. The campaign life of the screen has been considerably extended as a result of this different design.
Bern Klein
Prof Bern Klein, of UBC, has been leading a project on identification and rejection of waste rock at an early stage of the handling of the run-of-mine ore for the last fifteen years. Specific areas include:
- Characterization of ore sortability (heterogeneity)
- Selection of appropriate sorting scale and technology, according to the heterogeneity
- Standardization of testing and reporting procedures
- Development of sorting systems
It is planned to hold a series of workshops in Canada, South Africa and Germany and to setup attendance by video - conference connection for participants who cannot attend in person.
Tracy Holmes
A remarkable project on improving the flow of mill feed through a storage bin by testing and modelling the physical properties of the rock was presented by Tracy Holmes of Jenike and Johnson. The case study was at the Kittila Mine in northern Finland, where ratholing, bridging and freezing limit the free flow of ore to the mill. The modelling work led to a redesign of the bin with successful outcomes.
A reception was held on Tuesday evening for the organising committee of the recent IMPC meeting at Quebec City. The conference was very successful. In the photo below are some of the organising committee Norm Lotter, Jim Finch, Nathan Stubina, Jan Nesset and Don le Roux.
An interesting and worthwhile paper on the sustainable stabilisation of arsenic was presented by Gabriel Garcia Curiel, of Dundee Sustainable Technologies. Traditionally arsenic has been stabilised by a hydrometallurgical process, however in this work a different approach using vitrification and then set in glass. In this form there is no release of arsenic to the environment.
GoldCorp’s Simon Hille presented an update on their Peñasquito project in Mexico, where a brownfield expansion is adding a pyrite float to the final tailings of the main lead and zinc circuit to recover gold in a concentrate that undergoes an extractive process to refine the gold to bullion. These days, more and more of this refractory hosting of gold is developing, and we expect to see flotation becoming a more significant unit recovery process for this metal.
In the upcoming 50th meeting of the CMP, to be held in Ottawa in January 2018, the theme will be:
Day One: The Past, Day Two: The Present, Day Three: The Future.
The organising committee of the CMP and contributing authors are to be congratulated on a fine performance this year. The balance of academic and operational research and projects was just right, and the overall quality of papers was excellent.

Sunday, 22 January 2017

Utilising iron-rich residues from metallurgical processes to synthesise inorganic polymers

Many hydro- and pyro-metallurgical processes produce Fe-rich residues that find limited applications; notable uses are in the raw meal for cement production, as aggregate in concrete, as abrasive blasting grit, and as media in geotechnical and road pavement applications.
At next year's Sustainable Minerals '18 conference in Namibia, Prof. Yiannis Pontikes, of KU Leuven, Belgium will introduce, in a keynote lecture, an alternative process where the Fe-rich residue is used as raw material in the synthesis of inorganic polymers. These materials show properties comparable to Portland cement while having a smaller environmental footprint.
Yiannis Pontikes is a BOF-ZAP associate professor at the Department of Materials Engineering, KU Leuven, Belgium. He leads the Secondary Resources for Engineered Material (SREMat) research group, that consists of approximately 10 post-doctoral and postgraduate researchers. SREMat has built an expertise on the valorisation of residues towards ceramic, cement and inorganic polymer (geopolymer) formulations, from the level of binder synthesis all the way to full scale prototypes. He is on the Scientific Advisory Board of the Waste and Biomass Valorization journal, and in 2015, was one of the founders of the Journal of Sustainable Metallurgy, where he serves as the managing editor.

Friday, 20 January 2017

Talk of lithium and tin over a few pints

There was much to talk about last night, at the first Cornish Mining Sundowner of the year, held at the County Arms in Truro. It was very well attended, despite a few of the regulars being missing.

It was particularly good to see so many Camborne School of Mines (CSM) students, and it is always great to hear them talk enthusiastically about their future careers in the mining industry.
Barbara with CSM students
There were also a number of CSM alumni present. After leaving CSM with a PhD Klaas van der Wielen worked with Swiss company Selfrag and then with Wolf Minerals at the Drakelands tungsten mine in Devon. This month he took up a position with Truro-based Grinding Solutions Ltd, and it was good to see him back at a sundowner, along with his boss Nick Wilshaw.
A concentration of mineral processors at the bar
And always good to see our old friend Bentley Orchard, formerly with FLSmidth, then Weir Minerals, but now happily retired and a member of a local male voice choir.
Barbara with Bentley Orchard
Making his sundowner debut was CSM alumnus Tom Clifford, Consultancy Director of Riventa, Truro, a team of global water pump energy specialists. Tom played football for CSM and his company agreed to sponsor the current team, and below he is seen donating a cheque for £600 to club treasurer Jake Dowling.
And yes, much to discuss last night, particularly the headline news of the day, lithium. It has long been known that there are lithium brines in contact with granite in the local groundwater, which may be exploited, not only for this metal, but also for its heat; the high geothermal gradient could mean that the mine water has potential for sale to local housing and industries for heating purposes (see also posting of 10 May 2010).
High levels of lithium readings were first recognised in 1864 in water flowing into Cornish mines, but there was then no market for this lightest of metals, and when the mines in Cornwall closed it was largely forgotten. Now lithium, vital for rechargeable batteries, has been named a strategically important mineral for the UK by the Government because of its importance for developing industries and its scarcity. At present, it is mainly mined in remote parts of Chile, Australia and Nevada in the USA but without a home grown source of lithium the UK would be vulnerable to shortfall as global demand increases.
In a major announcement made to the Stock Market yesterday morning, private firm Cornish Lithium, led by Camborne School of Mines graduate Jeremy Wrathall, confirmed that it has secured the rights to develop and extract, via deep drill holes, the lithium deposits under Cornwall, undertaking the largest, single unified exploration project in the county's history, the vast deposits having the potential to unleash a new major industry in the county.

As yet there has been no mention of the economics of extracting the lithium from the waters, which is a slow process, involving evaporation then leaching. In the major lithium brine regions evaporation is by solar radiation in large ponds, which may not be too practical in the mild and wet Cornish climate.
Cornish Lithium has signed agreements to develop potential deposits beneath the ground held by three main landowners in Cornwall, including the Tregothnan estate of Lord Falmouth and South Crofty in Pool, which is at the centre of a potential resurgence in tin mining.
And although I have been sceptical about the tin mining revival at South Crofty, it does look like things are actually happening. Siltbuster Process Solutions (SPS) is taking part in trials to show the treatability of the mine water from South Crofty, which closed in 1998. Once completed, the results will be used to show the viability of dewatering and the reopening of the mine. SPS has been asked to treat the mine water (which includes dissolved contaminates and metals in solution, principally iron) by reducing the metal content to allow safe discharge of the water to the nearby Red River. If successful, the trial will be an important next step in the reopening of the mine, for Strongbow Exploration Inc., which acquired it in July 2016.
So, fingers crossed that 2017 might be the year of the great revival of the Cornish, as well as the global, mining industry.

Twitter @barrywills

Monday, 16 January 2017

The Increasing Importance of Physical Separation Methods

Physical Separation '17 is building up to a must-attend event if you are involved with physical separation of minerals and coal. Physical separation features in almost every mineral processing circuit, encompassing a broad range of techniques and technologies including hydrocyclones, gravity concentration methods and thickeners, all of which make use of the inherent density difference between two mediums, as well as magnetic separation, and the increasingly important ore sorting technology.
One of the leading practitioners in the gravity concentration field is Sandy Lewis-Gray, Technical Director of Gekko Systems, Australia (see posting of 16 March 2015), one of the conference sponsors, who will present the first keynote at the conference, showing how opportunities for enhanced physical separation performance can now go beyond the common practice of optimising unit operation. Improved options exist for feed preparation ahead of the physical separation stage, enabling higher performance and lower cost outcomes for physical separation flowsheets and technologies.
Sandy and Elizabeth Lewis-Gray of Gekko Systems
Sandy will also co-author a paper with fellow Australian sponsor CRC Ore, who will describe the development of a new generation of comminution devices which can produce much steeper product size distributions than with conventional machines, and combined with precise classification will produce feeds which are well suited to gravity concentration and should also reduce flotation losses at both coarse and fine sizes. The use of such new applications in breakage technologies, combined with mineral liberation analysis to optimise liberation prior to the physical separation stage, provides options for pre-concentration and gangue rejection as well as better separation efficiency. The use of low cost gangue rejection and pre-concentration can be an intermediate step between mining and processing that allows lower cut-off grades in the mine whilst delivering higher grades to the mill, and conference sponsor Steinert Elektromagnetbau will assess the economic impact and viability of upgrading ores by pre- concentration using ore sorting.
Electronic ore sorting is becoming increasingly used, due to the development of rapid sensors in such sorters, but preconcentration prior to grinding is nothing new, and dense medium separation has long been an accepted method for treating coal and for early gangue rejection from certain metallic and non-metallic ores, including diamonds. Prof. Tim Napier-Munn (posting of 12 May 2014), former Director of Australia's JKMRC and a current CEEC Director, has many years of experience with dense medium cyclones, which were first patented in the 1940s, and will present the second keynote lecture at the conference, summarising the history of the process, considering its current status in mineral and coal processing, and suggesting ways in which the process might evolve. 
Tim (right) with fellow CEEC Director Mike Battersby at Comminution '14
So, there is much to look forward to in Falmouth in June. We will be putting the provisional programme together later this month, so it is not too late to submit an abstract for presentation at the conference, which immediately follows Computational Modelling '17 at the same venue.
Current Physical Separation '17 sponsors

Saturday, 14 January 2017

Light Rock in Tenerife

Tenerife, in Spain's Canary Islands archipelago, is the second largest ocean-island volcano on Earth after Mauna Loa in Hawaii. Only a 4 hour flight from the UK's provincial airports, and on the same time zone, it is a popular winter holiday destination due to its warm, sunny, sub-tropical climate.
Less than 200 miles from the African coast, Tenerife is dominated by the volcano Mount Teide, whose 3,718-metre (12,198 ft) summit is the highest point in Spain and the highest point above sea level in the islands of the Atlantic. If measured from its base on the ocean floor, it is at 7,500 m (24,600 ft) the third highest volcano on a volcanic ocean island in the world. It remains active, its most recent eruption being in 1909, and last October there were ill-informed scare stories that a major eruption was imminent.
Teide is the most visited national park in Spain and Europe and, by 2015, the eighth most visited in the world with some 3 million visitors yearly. If you can cope with the altitude the amazing lunar landscape is great hiking territory.  
Hiking in Teide National Park in 1997, under Mount Teide
The light coloured "lunar" rock in this area is ignimbrite, which is common in southern Tenerife. It has a characteristic pale yellow-orange colour and can be seen all around the southern coast, overlain with the later lava flows. 
Deposits of lava and ignimbrite above a typical basalt beach
A fine example of ignimbrite
Barbara and I returned yesterday from a week at Costa Adeje in southern Tenerife, topping up our vitamin D reserves, and it is evident in this area that just as a landscape is moulded by local geology, so is the local architecture. The UK 's beautiful Cotswolds area is famous for its buildings, made from the creamy Jurassic limestone, and southern Tenerife has ignimbrite, its Cotswold stone equivalent. As it is lightweight and easy to cut and shape, it is quarried and used locally as a building material.
A dry stone wall composed of ignimbrite
Tenerife's Ignimbrite is a pumice-dominated pyroclastic flow deposit formed from the cooling of pyroclastic material ejected from an explosive volcanic eruption around 600,000 years ago. As pyroclastic material settles it can build up thick layers, and if the temperature is sufficiently high (> 535°C) it can weld into rock, in a similar fashion to that which preserved the shapes of countless corpses after the 1st century eruption of Vesuvius. The pumice and basalt rocks that can be seen in many of the the outcrops were most likely picked up by the ground-hugging pyroclastic flow while it was cascading down the volcano's flanks.
All in all, Tenerife is a great escape from the winter blues and, if you are so inclined, also a great place to read the story of the island in the rocks.