Clays and Mining – Friends or Foes?

Overburden is a generalized termed used to describe unconsolidated material encountered at a mine.  It can consist of gravels, sands, silts, and clays and combinations of each. Usually overburden is not given much focus in many mining studies. Very often, the overburden as a unit, is not adequately characterized.
This blog will explain why proper characterization can be an important issue,  particularly the clay component.
I also want to share some personal mining experiences with clays, all types of clays.  There is more to them than meets the eye; a fact often not apparent to those involved only in hard rock mining.
Clays have unique geotechnical properties that can make for challenging situations and require special consideration in project design.   Many simply view clay as a sticky cohesive material – no big deal. So let’s examine this a bit further. I tried to avoid geotechnical lingo where possible, since this blog isn’t being written for geotechnical engineers.
There are several types of clays, or clay-like materials that can be encountered in mining. Here are the ones that I have been lucky (or unlucky) enough to have dealt with over the years.
  • Normally consolidated clays
  • Over-consolidated clays
  • Sensitive (or quick) clays
  • Swelling clays
  • Saprolite clays
  • Kimberlite clays (muds)

What are the challenges?

Each of the clays listed above can be found in different locations, have unique properties, will behave differently, and can create specific mining challenges.   Clays can also cause problems in process plant circuits, but that is a subject outside my area of expertise.

Normally consolidated clays

These are the clays most people are familiar with, i.e. a sedimentary deposit of very fine particles that have settled in a calm body of water.   Normally consolidated clays are generally not a problem, other than having a high moisture content.  As such, they can be very sticky in loader buckets, truck boxes, and when feeding crushers.
When wet, they can become sloppy and difficult to handle efficiently.  They can creep and run when placed into waste dumps.  For these reasons, engineers must be aware if a large proportion of the overburden will consist of clays so they can avoid surprises.

Over-consolidated clays

These clays have undergone greater vertical compression in their history than in their current condition.  For example, perhaps they were once pre-loaded and compressed by a mile of glacial ice sheet during an ice age, which has subsequently melted.
Clays in general consist of very fine plate like particles, as shown in this sketch.   In over-consolidated clays, these particles have been flattened and tightly compressed as in the right image.   The result is that the clay may be dense, have a good cross bedding shear strength, but very low shear strength along the plates.  This characteristic is analogous to the lubricating properties of graphite, which is facilitated by sliding along graphite plates.
My experience in working with over-consolidated clays was at the Fort McMurray oil sands mining operations.  In that region the Clearwater clays formed part of the overburden sequence above the oil sands.  Stripping these clays with trucks and shovels was not exceptionally challenging.  They had low moisture content and were stiff.   The challenge really came when needing to build on top of them, for example building a waste dump or tailings dam.
The cross-bedding shear strength was good, with peak friction angles exceeding 25 degrees.  However after any creep or deformation, the peak shear strength was gone and the residual friction angle would now control stability.   The residual friction angles could drop as low as 6 degrees (very weak) and, upon surcharging the clay could maintain high internal pore pressures.   Due to these factors it was not uncommon to see tailings dams or waste dumps with 15:1 (H:V) downstream slopes.  This compares to the 3:1 slopes one may normally see at hard rock mine sites.
Building a 15:1 dam or dump is much less volume efficient than building a 3:1 embankment.  It also doesn’t take much instability to cause an embankment to creep along a foundation with only a 6-degree friction angle.  Hence the over-consolidated clays presented a unique engineering challenge when working in the oil sands.

Sensitive (quick) clays

Referring to the clay particle sketch shown above, quick clays represent a card house structure (on the left image).  These clays were often deposited in a quiet marine environment, where electrical charges prevented the clays from settling uniformly.  Instead, the clay particles tend to stack up like a house of cards.  The large void spaces are filled with water, whereby moisture contents can exceed 100% by weight.
When these clays are disturbed by vibration or movement, the house of cards structure collapses.  Combined with the excess void water, these clays will flow…. and flow a lot.   This video shows a slope failure in quick clays in Norway.  Try to stop that failure once it has initiated.
My experience with sensitive clays was at the former BHP bauxite mining operations along the northern coast of Suriname.   There were Demerara clay channels up to 20m thick over top of many of their open pits.   The bucketwheel excavators used for waste stripping would trigger the quick clay slope failures, sometimes resulting in the crawler tracks being buried and unfortunately also causing some worker fatalities.
I recall walking up towards a bucketwheel digging face as the machine quietly churned away.   About 70 metres from the machine, we would see cracks quietly opening all around us as the ground mass was starting to initiate its flow towards the machine.   Most times the bucketwheel could just sit there and dig.  Instead of the machine having to advance toward the face, the face would advance towards the machine.
To address the safety issue, eventually mine-wide grids of cone penetration tests were used to define the Demerara clay channels.  Dredges were then brought in to remove these channels before allowing the bucketwheels to strip the remaining sands and normally consolidated clays.

Swelling clays

In some locations, mines may contain swelling clays.  The issue with these clays is that they can absorb water rapidly, swell by 30%, and become extremely soft to operate on.  If they form part of the ore zone and find their way to the tailings pond, one may find they don’t want to settle out in the pond. Water clarification and clean water recycle to the plant can become an operational issue.   Mineralogy tests will indicate if one has swelling clays (smectites, montmorillonites, bentonite).  The swelling clays do have a functional use however, discussed later.

Kimberlite clays (muds)

The formation of the diamond deposits in northern Canada often involved the explosive eruption of kimberlite pipes under bodies of water. The lakebed muds and expelled kimberlite by the eruption would collapse back into the crater, resulting in a mix of mud and kimberlite (yellow zones in the image).   This muddy kimberlite could be soft, weak, and difficult to mine with underground methods.
Normally as one descends deeper into the kimberlite pipe,  the harder primary kimberlite dominates over the muddy material.   An upside is that the muddy kimberlite can be scrubbed fairly easily during processing, with the very fine clay particles being washed away.

Clays can’t be all bad?

Encountering clays at a mine site can’t be always negative?  There must be some benefits that clays can provide?   Well there are a few positive aspects.

Saprolite clays 

At many tropical mining operations (west African gold projects for example) the upper bedrock has undergone weathering, resulting in the fresh rock being decomposed into saprolite.  This clay-rich material can exceed 50 metres in thickness, can be fairly soft and diggable without blasting.   This is an obvious mining cost benefit.
As well, grinding circuits can easily deal with saprolite.  For example, if a 1000 tpd grind circuit is designed for the underlying deeper bedrock, it may be able to push through 1400 tpd of saprolite.   This would yield a 40% increase in mill throughput for little added cost.  This will boost early gold production.  However as the blend of saprolite to fresh rock declines over the years as the pit deepens, the plant throughput will decrease to the original design capacity.
One concern with saprolite sometimes is its sticky nature.   A truck load of saprolite ore dumped on a crusher grizzly may just sit there.  Possible some prodding or water flushing may be required to get it moving.  Nevertheless, this is normally an easily resolvable operating issue.

Clay core dams

One of the ways miners build water retention or tailings dams is to use mined waste rock.   The issue with this is that a dam built solely with waste rock will leak like a sieve, which can lead to piping failure.  One solution is to build an internal clay core in the center the dam to act as a seepage barrier.   Having on-site access to good quality clean clay fill is a benefit when such dams are required.   If the clay fill isn’t available at site, then more complex synthetic liners or internal seepage control measure must be instituted.
Compacted clay fill can also be used as a pond liner material for water retention ponds.
One can also purchase rolls of geosynthetic clay liners (GCL), whereby a thin layer of dried swelling clay is encapsulated between two sheets of geotextile.  Once the liner is laid out and re-hydrated with water, the clays swell and will act as an impervious liner.   The installation approach is somewhat simpler than for HDPE liners and such liners can be self-healing if punctured.  A downside is that the transport weight of these GCL liners can be significant.
See, there are some positives with having clay at site.

Conclusion

All clays are not the same.  The mining of clays can create unique challenges for mining engineers and operating personnel.   Whenever I see study happily mention that their open pit mine waste consists of “free digging overburden”, I say to myself “Be careful what you wish for”.
One must ensure that the overburden is properly characterized, even though it may be viewed as an unimportant or uninteresting material.  Determine whether it consists of gravels, sands, silts, tills, or clays, or combinations thereof.   It can make a big difference in how it is mined, disposed of, and whether it can have any secondary uses on site.  In many studies that I have reviewed, the overburden tends to be forgotten and does not get the technical respect it deserves.
Please feel free to share any thoughts on your experience in working with clays.
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A Junior EIT Mining Story

We know the mining industry is having trouble attracting talent in all sorts of disciplines, including operations, technical, and supervision. Industry people have no shortage of ideas (right or wrong) on how this issue can be addressed in the future. Myself…I don’t really have any good suggestions.
Not long ago I was speaking with a 2020 graduate mining engineer (EIT = Engineer in Training). During our conversation, I was curious to know what attracted him to the industry and if he had any advice on how to reach out to others in his age group. I asked if he was willing to share his thoughts on my blog site. After all, who better to hear from than a recent graduate. He said “yes”, so for your interest, here is his story and his thoughts. (I decided to leave his name out of this article although he was not insisting on anonymity.)

So here’s the story (in his words)

Mining has been a part of my life for as long as I can remember. Being born in Sudbury, many of my family members have been, or are currently involved, in mining through a variety of occupations, including my father who I idolized. However, I never knew my true interest in the industry until my 11th-grade technology class. I had a teacher who was passionate about the mining industry, and he created a project that involved developing a very basic mine design.
Once I started the project, I realized that I enjoyed the design work, as it requires problem-solving which constantly stimulates the mind. After the conclusion of this project, I started doing my own research to expand my knowledge and realized that the financial side of mining had great interest to me as well. This led me at age 16 to start investing in the mining sector, which I continue to this day.
With this developed interest, and my family’s mining history, the decision to study Mining Engineering at Laurentian University was an easy decision. It allowed me to support my hometown and will allow me, given my career ambitions, to put this small school on the international map.
Before my first year of university, I had a summer job tramming at Macassa Mine in Kirkland Lake Ontario, which has been in production since 1933. My mentality was to get the boots on the ground and get the job done, whatever it took (with proper safety precautions of course). Using rail systems, dumping ore cars manually, jackleg drilling, etc. gave me the perspective that mining was archaic, mining was rough, and mining was only about the ounces.
Therefore, when I started the Mining Engineering program at Laurentian University in 2016, I already had a (somewhat negative) preconceived notion of the mining industry, but as my short career progressed, my opinions morphed into something different, something more positive.
Now that I have graduated and been employed for a couple of years, my perspective has changed. However, I feel that the perspective of the general population has not. People within mining have a (positive) bias and realize its importance in our everyday lives. This is showcased in the famous saying “if it is not grown, it is mined” and I believe that to get the industry to progress at an even faster rate, we need to get everyone on board.
It cannot be an industry that just takes from the Earth, it needs to be seen as one that values sustainability, supplies the world with required goods, and creates jobs with high employee satisfaction. Although this has started with companies taking more of an interest in stakeholder value and employee job satisfaction, based on my limited years in the industry, there is still lots of room for growth.
To change the negative view around mining, I believe the main focal point should be electric equipment and the ability for remote operation/work. With all this newly developed technology at our fingertips, I know that future operations will be safer and more sustainable, which should be better portrayed.
The battery-electric equipment will surely increase employee satisfaction since I know firsthand that one of the worst feelings as a worker is to have a scoop operating in a heading that is already 25+ degrees. It will also create more sustainability since the industry can transition from being reliant almost solely on fossil fuels.
In addition, I believe that remote equipment operation is not being used to its full capacity or explained to the younger generation. Right now, there has been equipment running in Canada that was operated in Australia. What is stopping mines from having equipment operators all over the world in urban office spaces or out of their own homes? I believe that for a company to visit a high school, or even a trades school, to sell the idea that you can operate a massive piece of equipment from the creature comforts of home, almost like a real-life video game, would be quite compelling to this audience.
Even creating a mining simulation video game where you can run through a story of being a manager, excavator/scoop operator, truck driver, etc. would get the thought of mining brought into the coming generations at a younger age. This would increase the talent pool from the more typical operator because more and more youth are getting skilled at remote operation through video games due to their increased screen time.
Not only equipment operators, but technical staff could be made fully, or partially, remote. When I describe my job to my (non-mining) peers, many are interested since mining is a fast-paced, stimulating, and rewarding industry.
But as soon as I describe the remote nature of the work, many young professionals, or high school students, get turned away. Therefore, showing teenagers, through school presentations or workshops, that a technical career in mining can lead you down so many avenues (scheduling, ventilation design, drill & blast, etc.) would pique their interest, but I believe adding the ability to work remote, with some occasional travel, would drive the point home.
InternPeople get comfortable and people are afraid to leave home, so selling a career that allows for boundless flexibility in job tasks and constant stimulation while living wherever you desire could allow a shrinkage in the current technical gap.
Overall, the mining awareness and outreach (approach) is still old school. Getting to youth and teenagers through various media streams could be the key to getting engagement from not only the current mining towns but larger urban centres as well.
I mentioned a mining simulation video game previously, but what is stopping us there. Many of my peers, and youth younger than myself, are entering the professions of doctors, lawyers, finance, or criminal investigators.
I might be wrong, but, intriguingly, these are industries are the base professions glorified on TV. Why not develop more TV shows based on mining? I know that there would be some population interest considering many people ask me if the gold we mine underground looks like what comes out of the pans in Yukon Gold Rush.
So do I think the mining industry is archaic…. not anymore.
Do I think the mining industry is rough… somewhat.
Do I think it is only about the ounces…., yes, since a mine will not run any other way.
However, I believe that there has been more importance placed on employee and stakeholder satisfaction. So, with more time, and more engagement from the public of all ages, I think this industry can have a bright future ahead.
END

Conclusion

Firstly, I would like to thank this engineer for taking time to write out his well formed thoughts, and for allowing me to share them.
Many of the mining people I meet are following along in family footsteps. No surprise there. However, the industry cannot rely on that farm system alone. It should be reaching out to broader society, although that may require some out-of-the-box thinking. People’s attitudes and personalities are different today than they were 20 years ago.  Many different doors are being held open as career options.
The discussion above has some interesting ideas from a person who would be the target of outreach efforts. It likely will take more effort than simply telling people “Hey, your iPhone uses metal, therefore mining is good, and you should work in mining”.

 

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Hard Rock Continuous Cutting – Reducing Drill & Blast

Several years ago I worked in the Saskatchewan potash industry where I grew my appreciation for continuous mining systems. Some of the key benefits were the high productivity per man-hour and the safe operating conditions.  On a 12 hour nightshift, with a crew of 16 people we could mine over 9,000 tonnes of ore.  Productivity is  likely even higher now with the larger machines.   Therefore, since that time, I have always kept an eye out for when similar technology can be applied in hard rock mining.
One of the research areas we are seeing these days is the development of continuous cutting technology for hard rock mine development.  The idea is to replace the conventional drill & blast approach with something more efficient and safer.  No need to deal with explosives, noxious gases, shatter the wall rock, or have personnel scale their way under loose conditions.
Recently I was contacted by someone associated with Robbins asking if I was aware of their MDM5000 mine development technology.  I wasn’t aware of it, but I wondered if there finally is a light at the end of the tunnel.

4-rotor miner

In Saskatchewan potash the entire mining operation relies on track-mounted continuous miner technology.   The miners are connected directly to the shaft area using a network of conveyors, up to 10 km worth of conveyor.
The potash miners are able to undertake both development work and production mining whilst connected to conveyor.
From time to time they will rely on shuttle cars, scooptrams, or grasshopper conveyors for small development tasks. A roadheader may also be available for localized ground stabilization.
All of this mechanical cutting is done in potash (sylvinite rock), considered a soft rock with a compressive strength of 20-40 MPa. For comparison, hard rock can have compressive strengths exceeding 250 MPa.

Two approaches in hard rock

Hard rock piloting trials are underway at a few operations, using different vendors with different equipment.  These trials include companies like Komatsu, Robbins, Sandvik, and Epiroc.  Each are testing their own equipment and cutting technologies.
The hard rock cutting approaches generally fall into two camps.

Roadheader style

There are the track mounted roadheader style cutters, typically with a movable arm used to shape the excavation.  Any excavation shape is possible.

Tunnel Borer Style

Then there are the tunnel borer styles, where the machine propels itself with hydraulic shoes and the opening shape is based on the machine configuration. Normally a circular shaped opening is the result.
The roadheader style cutter is normally restricted to softer rock (< 50 MPa) while the tunnel borer is capable of much harder rock (200-250 MPa).

Robbins MDM5000

One system that peaked my interest is the Robbins MDM5000 because it can both cut hard rock and create a rectangular opening. Speaking with the vendor, this unit uses shoes to propel itself while cutting a rectangular shaped opening about 5m x 4.5m in size (see image).  A rectangular shape is preferred to the circular opening whereby the floor invert must be backfilled to provide a level operating surface.

MDM5000 opening shape

The MDM5000 configuration and advance rate allows the installation of ground support and utilities behind the advancing face.   Water sprays and dust collectors help to maintain visibility and air quality at the working face.
The Robbins unit is best suited for long straight drives although reportedly it can turn curves with 450-m radius.  Tighter turns may be feasibility in the future by tweaking the machine design.   Interestingly driving a drift uphill is easier than driving downhill due to the more efficient cuttings removal capability.
The MDM5000 unit can be linked to a Robbins conveyor system, which includes a head drive and an extensible belt storage unit that can feed out the conveyor belt as the machine advances forward.  This operation is similar to that used in the Saskatchewan potash industry.

Robbins MDM5000

A Robbins machine has been in operation at the Fresnillo mine for several years with favorable results (check out the link here).
One nice thing about disc cutters is that they can accommodate variable rock types (softer and harder) while road headers can be hindered by hard rock zones.  Roadheaders require a bit more consistency in rock quality.
Continuous cutting systems, such as the MDM5000, can be combined with vertical conveying technology, leading to safe and rapid development (>200m per month) in the right situation.

Conclusion

No doubt that we will eventually see more application of hard rock continuous cutting technology in the right situations.  The Stillwater Mine in Montana has been using a Robbins tunnel borer for years for development tasks.
No matter how well these new systems perform, there will still be some limitations.  This means the conventional drill and blast development will always be around.  However, keep your eyes on this mining technology sector as improvements in cutter head design and equipment mobility continue to evolve.
Coincidentally International Mining (Nov-Dec 2021) recently published an in-depth article on the various systems being looked at.  The link is here.

 

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Stories from 3000 Feet Down – Part 2

This is Part 2 of my story about working at a potash mine in Saskatchewan. If you haven’t read Part 1, here is the link to it “Stories from 3000 Feet Down – Part 1“.  It’s best to read it first.

Flooded Russian Potash Mine

As mentioned in Part 1, water seepage and potential leaks were always an operational concern. There were essentially two main fears; (i) that a borer would tunnel into an unforeseen collapse zone (i.e. an ancient sink hole) or (ii) that long term deformations in the mine would result in cracking of the overlying protective salt layer resulting in water inflow.
Any time wet spots were seen on the roof, the mining engineers or geologists were called out to take a look.
Sometimes the wet area was due to pockets of interstitial moisture. Other times it might have just been oil from a blown hydraulic hose on the borer. Wet spots all look the same when covered in dust.
Water ingress was such a concern in that an unmined pillar of 100 ft. would be left around all exploration core holes. These 3,000 ft. holes were supposedly plugged after drilling but you could never be certain of that. Furthermore, you couldn’t be certain of their location at potash depth. Hence, we didn’t want to mine anywhere close to them.
The process plant also had several water injection wells whereby excess water was injected into geological formations deep below the potash level. We left a 700 ft. pillar around these injection wells.
Carnallite is a magnesium salt that we encountered in some areas of the mine. It was weaker than the halite, resulting in more rapid room closure and deteriorating ground conditions. It was also hydroscopic and could absorb moisture out of the air. Sometimes we would water the underground travel ways to mitigate dust issues. With the resulting high humidity sometimes the carnallite areas might start to drip water. This resulted in another call to the engineers to come out and investigate.

Working on a production crew brings new learnings.

My period as a production foreman was great. When first assigned to this role, I was less than enthusiastic but when it was over 6 months later, I appreciated the opportunity. As a production foreman, we had a crew of 15 to 20 people responsible for mining 9,500 tons over a 12 hour shift. There was one foreman in the underground dispatch room and one face foreman travelling around supervising the borers and inspecting conveyors.
Ore grade control was a key responsibility of both the borer operator and mine foreman. The goal for the borer operator was to cut the roof even with the top of the high grade potash bed. The goal for the foreman was to ensure the operator was maintaining his goal. However, when looking at the potash face all the beds generally looked the same, especially when they are dusty.

Feel the glow

One key distinction was that the middle low grade bed had a higher percentage of insol clays. It was used as a marker bed. You would take your hardhat lamp and run it down against the wall. In the upper high grade potash bed, the cap lamp would have a halo, not unlike like the glowing salt rock lamps you see in stores. In the marker bed the halo would disappear, like putting a lamp against a rock wall.
Thus using the lamp you could identify the top of the marker bed, which was supposed to be kept 3.5 to 4 ft. off the floor. If borer operators were consistently more than 12 “ inches off optimal level, they could be written up (i.e. reprimanded). This was one of my tasks as foreman and I always hated doing it.
Lasers were used to guide the borer in a straight line but the marker bed was used for vertical control. Nowadays the use of machine mounted ore grade monitors is an option. By the way, if you’re looking at a potash project, be aware of the grade units being reported. A previous blog discusses this “Potash Ore Grades – Check the Units”.
The underground conveyor network consisted of 32” conveyors, feeding onto 42” conveyors, feeding on to 48”or 54” conveyors. Typically the length of the larger conveyors was in the range of a mile (5,000-6,000 ft.). The conveyors were all roof mounted, allowing for easy clean up underneath. Roof mounting was critical. Even some of the 600 hp conveyor drive stations were roof mounted, structure and all.

Conveyors were the reason for my one and only safety incident.

4-rotor side pass

4-rotor borer side pass

First a little background. The underground ore storage capacity at K1 was about 3,000 tons. If the underground bins were filled anytime during a shift, the entire conveyor system would automatically trip off; all 10 miles of it. If you happened to have a mile long conveyor shut off while it was loaded to the brim with ore, good luck starting it up again.
If this happened, there were two choices. You could bring in the operators from the borers to start shovelling off the conveyor until it was unloaded enough to re-start. This option went over like a lead balloon with the crew.
The other not so great option was to use a scooptram to lift the belt counterweight up to reduce the belt tension. This allows the drive pulleys to start spinning. Then by lowering the counterweight back down perhaps the drives can inch the belt along. The idea being that possibly the momentum of the moving mass of potash would keep it moving. The downside is that you could break the belt. There was nothing worse than having to tell the cross shift they have both a stalled conveyor and a broken belt. Have a good shift people.
At 4 a.m. working as night shift face foreman, I knew the underground bins were nearing full. Driving along I saw that the mainline conveyor was full and spilling over the sides. A worst case conveyor shutdown was imminent. I called the dispatch office to ask why he hasn’t been shutting down borers and conveyors but there was no answer.
After several unanswered calls I started to hustle back to dispatch. I remember driving alongside the conveyor thinking “don’t shut off, don’t shut off”. Just then a heavy duty service vehicle pulled out of a cross-cut and I plowed right into it. I wasn’t going very fast (~20 km), but when a Toyota Land Cruiser hits a steel plate truck, the Toyota is the loser. The front end crumpled, and I later was told that there was major frame damage.
I’m not sure why the other driver didn’t see my lights. I’m also certain his lights were not on. Nevertheless, I did get written up for this incident with a reprimand for my personnel file. The reprimander had become the reprimandee. I still insist that the incident wasn’t my fault.
The Land Cruiser laid around the shaft for a few days until it could be hoisted up to surface. Everyone coming on shift got to see it . Once it was hoisted up, it laid outside the headframe for a few more days for all the surface workers to see. Ultimately, this incident resulted in the underground miners giving me the nickname “Crash”.
This is where I’ll end the potash story.

Conclusion

Saskatchewan potash is a unique mining situation. It has its own history and mining method. The people are great and it’s a great place to learn the difference between engineering school and real life.

Mine Engineering Dream Team

By the way, I also learned that small town Saskatchewan loves their senior hockey league (20-30 year age range). The local towns compete all winter; sometimes combatively. It was Esterhazy vs. Langenburg vs. Whitewood vs. Rocanville vs. Stockholm vs. Moosomin.
One of the first questions asked in my job interview at Mosaic was if I played hockey. You see, the ideal candidate for the job would have been an ex-NHL player, preferably an enforcer, who is also a mining engineer. Gotta stack the local team.

 

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Stories from 3000 Feet Down – Part 1

Mosaic K1 Mine

Between 1985 and 1989 I worked at the Mosaic K1 potash mine in Saskatchewan, Canada.  I had roles that included mine engineer, chief mine engineer and production foreman.   This was relatively early in my work career so it represented an important learning period of time for me.  Each of these roles gave me a different perspective about a mining operation.   In this two part blog, I’ll share some stories relating to the uniqueness of potash mining.
The K1 mine is 15 kilometres outside the town of Esterhazy; about 2.5 hours east of Regina.  The mine is located at a depth of around 3,000 feet below surface, hence the title of this blog.  I will be referring to imperial units in this text because when the mine started production in the early 1960’s the maps and units were imperial and continued on through the 80’s.   At my previous job with Syncrude we used metric units, so it took some time to mentally recalculate back.
Geologically, the province wide Esterhazy Member was being mined, named after the town.  The layer was about 8 ft high.  In other regions of Saskatchewan they are mining a different potash layer (the Patience Lake Member) which is located a few feet higher up. These mines have slightly different mining conditions than we experienced in Esterhazy.  An example of their conditions is shown in the photo, where a parting layer can result in a roof collapse.
The Mosaic K1 and K2 mine shafts are interconnected at depth 6 miles.  The total expanse of the K1 and K2 underground workings probably extends laterally over 18 miles.  Back in the 80’s they said there were over 1,000 miles of tunnel underground and probably a lot more now since the mines are still operating.  There is now a new K3 shaft which allows access to more distant potash reserves.

4-rotor borer

Potash, also termed sylvanite, mainly consists of intermixed halite (rock salt) and sylvite (potash) crystals. There are also minor amounts of insolubles (clays) and sometimes carnallite (a magnesium salt).  Sylvite (KCl) is the pay dirt, salt is the gangue mineral.
The production rooms being mined were about 75 ft. wide and 5,000 ft. long.  That is quite a large span, not likely possible in many other rock types other than salt rock.  Overall, the mine would extract about 40-45% of the potash, leaving behind the rest in the form of large pillars to support the overlying rock mass.

2-rotor borer

The mines use continuous miners or borers. In the 80’s they were Marietta miners and now they use borers from Prairie Machine (read more here).   When I was there they were starting to transition from two-rotor to four rotor machines.   The small machines would carve out ~350 tph, and the large ones could do over ~700 tph.
All borers are directly connected to the massive underground conveyor network that moves the ore from the cutter head to the shaft in a continuous process.
Mining excavates an 8 ft. high room consisting of three layers of interest.  A 4.3 ft. layer of high grade ore, a 1.7 ft. layer of low grade ore, and a 2.5 ft. layer of moderate grade potash.  This adds up to 8.5 ft., so the miners try to take the best 8 feet.  The best head grade would be delivered if the borer cut exactly to the top of the high grade 4.3 ft. seam. One didn’t want to overcut into overlying salt or undercut and leave high grade behind in the roof.  I’ll have more on how grade control was done in Part 2.
The air temperature underground is about 25C, so it’s quite a pleasant short sleeve climate.  Around the cutting face, the electric motors, and cutter head, temps can reach into the high 30 degree range. Hot but better than freezing. The mine was dry with very low humidity.   Hence metal didn’t rust.  However, bring the metal to surface and it would rust in no time.
Potash is termed a plastic rock, in that it will deform slowly under stress.  Hard rock will build up stresses and erupt violently in a “rock burst”.  Potash will go with the flow and deform.  Pillars will compress vertically and expand horizontally.  Room heights can decrease over time as much as 6 inches over several weeks in higher stress areas.
Interestingly when the borer shut down and all was quiet, one could walk to the freshly cut face.   You could hear the potash walls gently crackling like rice krispies, as the potash expanded into the opening.  After all, a few moments earlier the potash was being laterally confined under a vertical stress of 3,000 psi. That confinement is suddenly gone.
Roof closure was always an issue.  In panels that were almost mined out, all the ground stress was being carried by the unmined ground.  When advancing into this ground, roof closure could be so rapid that once a borer finished a 4 to 6 week room, the miner operator would need to cut a few inches off  the roof to get back to the front of the room.  It took a couple of days to get the borer out, rather than during a regular shift.
In very high stress areas you could see the floor heaving up as pillars were compressing laterally. That’s when you really knew that mining panel was done and operations should relocate to a new area.
I recall inspecting some of the very old workings from 20 years past.  The rooms looked like new except the roof had compressed down to 5 ft. in height.   We’d have to drive leaning sideways out of the jeep because the steering wheel was literally scraping the roof.

Flooded Russian Potash Mine

The biggest fear in potash mining is water inflow and mine flooding. There can be a water bearing layer about 50-70 feet above the mining level.  A layer of salt rock separates the two.  If you have groundwater flowing through a dissolvable material, it’s no surprise that the pathway will keep getting larger and larger. That’s why any sign of water seepage is taken seriously and causes the engineering team to leap into action (more on that in Part 2).
At least one potash mine in Saskatchewan has flooded.  A couple of others have come close but have managed to deal with the water inflows.
Barren areas where the sylvite has been leached away and replaced with pure halite are called salt horses.   I never knew why and still don’t.
Exploration core holes could be a mile apart so salt horses would be encountered unexpectedly.  They could be 20 or 2,000 feet in size; you never knew which.   They were a nuisance and an economic penalty.  If you tried to tunnel through them, you would send a lot of uneconomic salt up the shaft to the mill (which they did not like). Conversely, pulling out and abandoning a room was a painful decision because it took that borer off line for a couple of days to relocate. It’s an unplanned outage, which is not good if another borer happens to be moving at the same time.
On occasion, a borer would abandon the room and move to the next room 50 feet away and could pass by the same area without seeing the salt horse.  Upon reflection, perhaps we should have persevered in the previous room and gone another 20 ft. and we might have been through it.  Often the mill manager hollering about the mill getting too much salt was a deciding factor in whether to abandon a room or keep cutting.
For a year or so,  I also worked as a production foreman.  It was an interesting role. How does a young mining engineer four years out of school tell  guys working underground for 20 years what they need to do?
This also leads to the time when I wrecked a Toyota Land Cruiser underground.   I’ll leave that account to Part 2.  I’ve rambled long enough for today.
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Two More Mining Productivity Innovations

The mining industry is always on the lookout for new innovations as it strives to keep up with other industries.  In that light, periodically I like to highlight new technologies that I become aware of.   I’m trying to help spread the word  about them, which in turn may assist them in their on-going growth and development.
In this article I want to briefly describe two hardware / software companies that are working on technologies related to mine equipment productivity.    In no particular order, the two companies are Loadscan and SedimentIQ.  SedimentIQ is more of a startup than Loadscan which has a longer operating track record.
These technology companies are both targeting the open pit and underground markets, looking to provide simpler and less costly productivity solutions. Their technologies may be well suited for small to mid tier mines that cannot afford or don’t require the comprehensive Minestar type fleet management systems.
For the record, I get no fee or commission for promoting these companies; I just like what they are doing.

Loadscan

Loadscan has been around for a few years, but I only became aware of it recently.  It is a technology that allows the rapid assessment of the load being carried in truck.  It does not rely on the use of load cells or weigh scales to measure the payload.
Instead Loadscan uses a laser scanner and proprietary software to three dimensionally map the surface of the truck payload and then calculate its volume.  The results will indicate how consistent and optimal truck loading is volumetrically.   One can then calculate the payload tonnage by applying a bulk density.
The Loadscan technology will assess whether trucks are being over or under loaded, whether the loads are off-centre, or whether there is excess carryback on the return trip.
Successive truck payloads can be tracked manually or with RFID tags.   A cloud based database and web based dashboard are used to store the data and summarize it. The output can include an image of each individual load.
What is interesting about this technology is that it is simple to install in an operation.  It does not require retrofitting of a truck.
Results are immediate.  Loadscan provided an example where a message readout board can let the shovel operator immediately know how well each truck was loaded, resulting in improved education and better performance efficiency.
One can also assess how much better shovel bucket factors are in well blasted rock versus in blocky rock.
The Loadscan system is already in use in several mines globally.  The vendors can provide more technical  data if you need it.
Their website is https://www.loadscan.com/

SedimentIQ

SedimentIQ is a vehicle tracking platform using a smartphone app.  Their technology makes use of a phone’s built-in GPS, Bluetooth, and accelerometer to track vehicle operation.  The phone’s sensor can measure vibrations produced by an operating truck or loader.
Vibration is a fingerprint of a vehicle’s activity.  Therefore using machine learning, the SedimentIQ app can produce an “activity score” that decides whether a machine is parked, idling, or performing productive work.  The phone is not connected to the machine diagnostics system, so its very easy to install, only needing a power source.
The system can be used on any vehicle you want tracked, including trucks, drills, loaders, graders, dozers, etc. The system has the capability to monitor equipment location and speed.
In an open pit environment it uses the phone’s GPS to monitor vehicle location. In an underground setting the phone reads inexpensive Bluetooth beacons mounted along the side walls to track location.
The app will identify delay and downtime based on equipment vibration levels.  The system currently requires no interaction with the operator, working in the background.  Hence it will not identify the cause of delay (i.e. blasting delay, breakdown, inter-equipment delay, etc).  I would expect that in the future they could add a feature for the operator to tag delay types on the touch screen.
The SedimentIQ software will aggregate the cycle time and delay information and upload it in real time to a cloud based database.  A web-based dashboard allows anyone with access to view the real time production data graphically or export it to Excel.
The SedimentIQ platform is less expensive than high end fleet management software.  Although it may not provide all the bells and whistles of the high end software, it may deliver just what you need to monitor productivity in your mining operation.  It relies on relatively inexpensive smart phones that are locked to the application.
I recall as a mining student doing time studies.  I rode the shift crew bus with pencil in hand, timing the travel  from the mine dry to the various shovels to measure start up times.  I recall sitting with a stopwatch timing shovel buckets and truck loading times.  Both of these tasks can be done for every shift, every truck by equipping the crew bus and mine trucks with the SedimentIQ tech.
The platform is currently being tested at a couple of trials mines and the founders are looking for more mines willing to adopt and further refine their technology.
The website is https://sedimentiq.com/.

Conclusion

Both of these innovative technologies can provide useful information to open pit and underground mine operations.  They are in the growth stage, looking for wider adoption.   Input from users, whether positive or negative, will assist them with on-going development and enhancements. Their websites obviously have more on what their technology offers, including presentations, white papers, and case studies.
It would be nice to meld these two technologies in some way to allow the SedimentIQ cycle times to also track payloads.
Check them out.  Try them out.  Tell them Ken sent you.

 

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Vertical Conveyors Give Mining a Lift

There are not many things that are novel to me after having worked in the mining industry for almost 40 years.  However recently I came across a mining technology that I had heard very little about.  It’s actually not something new, but it has never been mentioned as a materials handling option on any project that I am aware of.
That innovative technology is vertical conveying. Not long ago I read about a vertical conveyor being used at the Fresnillo underground mine, hoisting 200 tph up from a depth of 400 metres and had a capital cost of $12.7 million.
I was aware of steep angle conveyors being used in process plants.  However they tended to be of limited height and have idlers and hardware along their entire length. Vertical conveyors are different from that.
After doing a bit of research, I discovered that vertical conveyors have been used since the 1970’s.  Their application was mainly in civil projects; for example in subway construction where one must elevate rock from the excavation level up to street level.   The mining industry is taking vertical conveyors to the next level.
I have never personally worked with vertical conveyors.  Therefore I am providing this discussion based on vendor information.  My goal is to create awareness to readers so that they might consider its application for their own projects.

How vertical conveying works

The background information on vertical conveying was provided to me by FKC-Lake Shore, a construction contractor that installs these systems.  FKC itself does not fabricate the conveyor hardware.  A link to their website is here.
The head station and tail station assemblies are installed at the top and bottom of a shaft.  The conveyor belt simply hangs in the shaft between these two points.  There is no need for internal guides or hardware down the shaft.   The conveyor belting relies on embedded steel cables for tensile strength and pockets (or cells) to carry the material.
The Pocketlift conveyor system is based on the Flexowell technology.  This has been advanced for deep underground applications with a theoretical lift height of 700 metres in one stage.   The power transfer is achieved by two steel cord belts that are connected with rigid cross bars. The ore is fed into rubber pockets, which are bolted onto the cross bars.    The standard Pocketlift can reaches capacities up to 1,500 m3/h and lift heights up to 700 m, while new generations of the technology may achieve capacities up to 4,000 m3/h.
The FLEXOWELL®-conveyor system is capable of running both horizontally and vertically, or any angle in between.  These conveyors consist of FLEXOWELL®-conveyor belts comprised of 3 components: (i) Cross-rigid belt with steel cord reinforcement; (ii) Corrugated rubber sidewalls; (iii) transverse cleats to prevent material from sliding backwards.   They can handle lump sizes varying from powdery material up to 400 mm (16 inch). Material can be raised over 500 metres with reported capacities up to 6,000 tph.

 

The benefits of vertical conveying

Vendors have evaluated the use of vertical conveying against the use of a conventional vertical shaft hoisting.    They report the economic benefits for vertical conveying will be in both capital and operating costs.
Reduced initial capital cost due to:
  • Smaller shaft excavation diameter,
  • Reduced cost of structural supports vs a typical shaft headframe,
  • Structural supports are necessary only in the loading and unloading zones and no support structures in the shaft itself since the belt hangs free.
Lower operating costs due to:
  • Significantly reduced power consumption and peak power demand,
  • Lower overall maintenance costs,
  • No shaft inspections required,
  • The belt is replaced every 8 – 10 years.

Conclusion

I consider vertical conveying as another innovation in the mining industry. There may be significant energy and cost benefits associated with it when compared to conventional shaft hoisting or truck haulage up a decline.
With raise boring, one can develop relatively low cost shafts for the vertical conveyor.  Hardware installation would be required only at the top and bottom of the shaft, not inside it.
The vendors indicate the conveying system should be able to achieve heights of 700 metres.  This may facilitate the use of internal shafts (winzes) to hoist ore from even greater depths in an expanding underground mine. It may be worth a look at your mine.
As stated earlier, I have no personal experience with vertical conveying. Undoubtedly there may be some negative issues associated with the system that I am currently unaware of.
I would appreciate anyone sharing their experience with these conveyors either in a civil application or a mining environment.   I will gladly update this blog article with additional observations or comments.
Update: for those interested in open pit applications for high angle conveyors, here is a recent article.  This is a 37 degree angle 3,000 tph sandwich belt, which is different than the vertical conveyors discussed above.
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Sustainable Mining – What Is It Really?

We hear a lot about the need for the mining industry to adopt sustainable mining practices. Is everyone certain what that actually means? Ask a group of people for their opinions on this and you’ll probably get a range of answers.   It appears to me that there are two general perspectives on the issue.
Perspective 1 tends to be more general in nature. It’s about how the mining industry as a whole must become sustainable to remain viable. In other words, can the mining industry continue to meet the current commodity demands and the needs of future generations?
Perspective 2 tends to be a bit more stakeholder focused. It relates to whether a mining project will provide long-term sustainable benefits to local stakeholders. Will the mining project be here and gone leaving little behind, or will it make a real (positive) difference? In other words, “what’s in it for us”?
There are still some other perspectives on what is sustainable mining. For example there are some suggestions that sustainable mining should have a wider scope. It should consider the entire life cycle of a commodity, including manufacturing and recycling. That’s a very broad vision for the industry to try to satisfy.

How might mining be sustainable?

The solutions proposed to foster sustainable mining depend on which perspective is considered.
With respect to the first perspective, the solutions are board brush. They generally revolve around using best practices in socially and environmentally sound ways. A sustainable mining framework is typically focused on reducing the environmental impacts of mining.
Strategies include measuring, monitoring, and continually improving environmental metrics. These metrics can include  minimizing land disturbance, pollution reduction, automation, electrification, renewable energy usage, as well as proper closure and reclamation of mined lands.
Unfortunately if the public hates the concept of mining, the drive towards sustainability will struggle. Trying to fight this, the industry is currently promoting itself by highlighting the ongoing need for its products. Unfortunately some have interpreted this to mean “We make a mess because everyone wants the output from that mess”. I’m not sure how effective and convincing that approach will be in the long run.

Focusing on localized benefits

If one views sustainable mining from the second perspective, i.e. “What’s in it for us”, then one will propose different solutions. Maximizing benefits for the local community requires specific and direct actions. Generalizations won’t work.  Stakeholder communities likely don’t care about the sustainability of the mining industry as a whole.
They want to know what this project can do for them. Will the local community thrive with development or will they be harmed? Are the economic benefits be short lived or generational in duration? Can the project lead to socio-economic growth opportunities that extend beyond the project lifetime? Will the economic benefits be realized locally or will the benefits be distributed regionally?
One suggestion made to me is that all mining operations be required to have long operating lives. This will develop more regional infrastructure and create longer business relationships. A mine life of ten years or less may be insufficient to teach local entrepreneurship.  It maybe too short to ensure the long term continuation of economic impacts. Mine life requirement is an interesting thought but likely difficult to enforce.
Nevertheless the industry needs to convince local communities about the benefits they will see from a well executed mining project. Ideally the fear of a mining project would be replaced by a desire for a mining project. Preferably your stakeholders should become your biggest promoters. Working to make individual mining projects less scary may eventually help sustain the entire industry.

What can the industry do?

We have all heard about the actions the industry is considering when working with local communities. Some of these actions might include:
  • Being transparent and cooperative through the entire development process.
  • Using best practices and not necessarily doing things the “cheapest” way.
  • Focusing on long life projects.
  • Helping communities with more local infrastructure improvements.
  • Promoting business entrepreneurship that will extend beyond the mine life.
  • Transferring of post-closure assets to local communities.
There are teams of smart people representing mining companies  working with the local communities. These sustainability teams will ultimately be the key players in making or breaking the sustainability of mining industry.  They will build and maintain the perception of the industry.
While geologists or engineers can develop new technology and operating practices, it will be the sustainability teams that will need to sell the concepts and build the community bridges.
The sustainability effort extends well beyond just developing new technical solutions. It also involves politics, socio-economics, personal relationships, global influences, hidden agendas. It can be a minefield to navigate.

Conclusion

As a first step, the mining industry needs to focus more on local stakeholders and communities. Remove the fear of a mining project and replace it with a desire for a mining project. Mining companies must avoid doing things in the least expensive ways. They must do things in ways that inspire confidence in the company and in the project.
The ultimate goal of sustainable mining will require changing the public’s attitude about mining. Perhaps this starts with the local grass roots communities rather than with global initiatives. As a speaker said at the recent Progressive Mine Forum in Toronto, the mining industry has lost trust with everyone. It is now up to the mining companies, ALL OF THEM, to re-establish it. Unfortunately just one bad apple can undo the positive work done by others.  The industry is not a monolith, so all you can do is at least make sure your own company inspires confidence in the way you are doing things.
As an aside, I have recently seen suggestions that discounted cashflow analysis (i.e. NPV analysis) and sustainable mining practices may be contradictory. There may be some truth to those comments, but I will leave that discussion for a future blog.  You can read that blog at this link.
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Green Energy Storage Using Abandoned Mines

The mining industry is always looking for ways to rehabilitate their abandoned operations so that there may be a public use for them. This could entail leaving behind recreational lakes, building golf courses, creating nature parks or using empty pits as public landfills. Another rehabilitation idea being studied is using old underground mines as a means of green energy storage.  If successful, we do have a lot of abandoned mines in all regions of the country.

Compressed air can store energy

I was at the 2019 Progressive Mine Forum in Toronto and a presentation was given on underground compressed air storage. The company was Hydrostor (https://www.hydrostor.ca/).  They were promoting their Advanced Compressed Air Energy Storage (A-CAES) system.
It is a technology that addresses the power grid need for power transmission deferral services. The A-CAES system can theoretically provide low-cost, long duration bulk energy storage (i.e. hundreds of MWs, 4-24+ hour duration).
The idea is to store off-peak or excess power from solar, wind, or other generating source.  Then the system can release this power back into the system during peaks or low generation capacity. Solar and wind power normally don’t work as well at night.

 

Flood the mine

The system uses excess electricity to run a compressor, producing heated compressed air. Initially heat is extracted from the air and retained inside a thermal store.  This preserves the heat energy for later use. Next the compressed air is stored in the underground mine, keeping a constant pressure.
While charging, the compressed air displaces water out of the mine, up a water column to a surface reservoir.
On discharge, water flows back down forcing air to the surface where it is re-heated using the stored heat and expanded to generate electricity.
Imagine an underground mine beneath an open pit, and seeing the open pit water level rise and fall daily as the compressed air is recharged underground and then released.
Hydrostor is currently building a $33 million 5-MW project in Australia at the Angas Zinc Mine site. I asked Hydrostor if they had any white papers describing the economics for a typical abandoned mine we might see here in Canada. Unfortunately they don’t have such a case study available.
Update: A Canadian example recnetly came to light; “How an old Goderich salt mine could one day save you money on your hydro bill“.
No doubt there would be capex and opex costs to build and operate the plant, but these would hopefully be offset by the power generation. It just not clear over what time horizon this payback would occur. Many abandoned underground mines are already in place; they are just waiting to be exploited.

Permitting is still an issue

Converting an abandoned mine into a power storage facility will still have its challenges. Cost and economic uncertainty are part of that.  In addition, permitting such a facility will still require some environmental study.
At Hydrostor’s proposed Australian operation, a fairly extensive environmental impacts assessment still had to be completed (see the link here).
Noise, vibration, air quality, ecology, traffic, surface water, groundwater impacts, visual impacts, employment, and indigenous consultations are aspects that would need to be addressed. However, given that this would be a green energy application, one might be able to get all stakeholders on board quickly.

Conclusion

We hear about sustainable mining and the desire to extend the positive social and economic impacts of a mining project. Energy storage is one way to extend the mine life into perpetuity by creating a localized power grid. Simply use wind or solar to recharge the system and then generate power over night.
If anyone is aware of a situation where something similar has been done, let me know and I will share it. Perhaps one day Hydrostor will provide a detailed economic study for a typical Canadian mine so that mining companies can see the economic potential.
Update:  In 2021 Hydrostor announced that it is developing two 500MW/5GWh energy storage projects in California, each of which would be the world’s largest non-hydro energy storage system ever built.  Read more at this link “Gigawatt-scale compressed air
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Mineral Processing – Can We Keep It Dry?

It’s common to see mining conferences present their moderated panels discussing “disruption” and Mining 2.0.   The mining industry is always looking for new technologies to improve the way it operates. Disruptive technologies however require making big changes, not tweaks.  True disruption is more than just automating haulage equipment or having new ways to visualize ore bodies in 3D.
Insitu leaching is a game changing technology that will eventually make a big difference.  Read a previous blog at “Is Insitu Leaching the “Green Mining” Future”.  Development of this technology will negate the need to physically mine, process, and dispose of rock.  Now that’s disruptive.
However, if we must continue to mine and process rock, then what else might be a disruptive technology ?

Is dry processing a green technique

Process water supply, water storage and treatment, and safe disposal of fine solids (i.e. tailings) are major concerns at most mining projects.
Recently I read an article titled “Water in Mining: Every Drop Counts”.
That discussion revolved around water use efficiency, minimizing water losses, and closed loop processing.   However another area for consideration is whether a future technology solution might be dry processing.

Dry processing is already being used

By dry processing, I am not referring to pre-concentration ore sorting or concentrate cleanup (X-ray sorting). I’m referring to metal recovery at the mineral liberation particle size.
In Brazil Vale has stated that it will spend large sums of money over the next few years to further study dry iron ore processing. By not using water in the process, no tailings are generated and there is no need for tailings dams.
Currently about 60% of Vale’s production is dry (this was a surprise to me) and their goal is to reach 70% in the next five years.   It would be nice to eventually get to 100% dry processing at all iron ore operations.   The link to the article is here “Vale exploring dry stacking/magnetic separation to eradicate tailings dams”.

Is dry grinding possible

Wet grinding is currently the most common method for particle size reduction and mineral liberation.  However research is being done on the future application of dry grinding.
The current studies indicate that dry grinding consumes higher energy and produces wider particle size distributions than with wet grinding. However it can also significantly decrease the rate of media consumption and liner wear.
Surface roughness, particle agglomeration, and surface oxidation are higher in dry grinding than wet grinding, which can affect flotation performance.
Better understanding and further research is required on the dry grind-float process. However any breakthroughs in this technology could advance the low water consumption agenda.
You can learn more about dry grinding at this link “A comparative study on the effects of dry and wet grinding on mineral flotation separation–a review”.

Electrostatic separation

Electrostatic separation is a dry processing technique in which a mixture of minerals may be separated according to their electrical conductivity. The potash industry has studied this technology for decades.
Potash minerals, which are not naturally conductive, are conditioned to induce the minerals to carry electrostatic charges of different magnitude and different polarity.
In Germany, researchers have developed a process for dry beneficiation of complex potash ores. Particle size, conditioning agents and relative humidity are used to separate ore.
This process consumes less energy than conventional wet separation, avoiding the need to dry out the beneficiated potash and the associated tailings disposal issue.
Further research is on-going.

 

Eddy current separators

The recovery of non-ferrous metals is the economic basis of every metal recycling system. There is worldwide use of eddy separators.
The non-ferrous metal separators are used when processing shredded scrap, demolition waste, municipal solid waste, packaging waste, ashes from waste incineration, aluminium salt slags, e-waste, and wood chips.
The non-ferrous metal separator facilitates the recovery of non-ferrous metals such as aluminium, copper, zinc or brass.
This technology might warrant further research in conjunction with dry grinding research to see if an entirely dry process plant is possible for base metals or precious metals.  Learn more at the Steinert website.

Conclusion

Given the contentious nature of water supply and slurried solids at many mining operations, industry research into dry processing might be money well spent.
Real disruptive technologies require making large step changes in the industry. In my opinion, insitu leaching and dry processing are two technologies that we will see more of over the next 20 years.
Ultimately the industry may be forced to move towards them due to environmental constraints.  Therefore let’s get ahead of the curve and continue researching them.

 

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Power Generation & Desalinization – An Idea that Floats

Access to a fresh water supply and a power supply are issues that must be addressed by many mining projects. Mining operations may be in competition with local water users for the available clean water resources. In addition, the greenhouse gas emissions from mine site power plants are also an industry concern. If your project has both water and power supply issues and it is close to tidewater, then there might be a new solution available.
I recently attended a presentation for an oil & gas related technology that is now being introduced to the mining industry. It is an innovative approach that addresses both water and power issues at the same time.
The technology consists of a floating LNG (liquefied natural gas) turbine power plant combined with high capacity seawater desalinization capabilities. MODEC is offering the FSRWP® (Floating Storage Regasification Water-Desalination & Power-Generation) system.
MODEC also has associated systems for power only (FSR-Power®) and water only (FSR-Water®)

FSRWP capabilities

The technology is geared towards large capacity operations that have access to tidewater. It provides many tangible and intangible operational and environmental benefits.  It can:
  • Generate fresh water supply (10,000 – 600,000 m3 /day)
  • Generate electrical power (80 to 1000 MW) using LNG
  • Can provide power inland (>100 km) from a tidewater based floating power plant
  • Can provide natural gas distribution on land via on-board re-gasification systems
  • Has LNG storage capacity of 135,000 cu.m
  • Has a refueling autonomy of 20 to 150 days
  • Allows low cost marine delivery of bulk LNG supply

Procurement & Application

The equipment can be procured in several ways. For instance it can be contracted as an IPP (Independent Power Producer), purchased as an EPCI (Engineering, Procurement, Construction and Installation), BOO (Build, Own and Operate) or BOOT (Build, Own, Operate and Transfer).
Typically it takes 18-24 months of contract award to deliver to the project site, although temporary power solutions can be provided within 60-90 days.
From a green mining perspective, the FSRWP produces clean power with the highest thermal efficiency and lowest carbon foot-print.
See the table for a comparison of different power generation efficiencies and carbon emissions per kW.
Gas turbines are not new technology to MODEC.  They currently own & operate 42 such generators, which can produce roughly 43 MW (each) in combined-cycle mode.

Mooring options

Currently there are three mooring options for the floating system that should fit most any tidewater situation.
Jetty or Dolphin mooring is suitable for protected areas or near-shore applications where the water depth is in the range of 7 to 20 meters.
Tower Yoke mooring is ideal for relatively calm waters where the water depth is between 20 to 50 meters.
External Turret mooring is similar to a Tower-Yoke and is ideal for water depths exceeding 50 meters or where the seabed drops off steeply into the ocean.

Power transmission

Twenty years ago it was impractical to transmit AC power long-distances and subsea power cable technology was not as advanced as it is today. Hence an offshore power plant like a FSRWP was not technically viable. Due to R&D efforts over the last 15 years it is now possible to economically transmit AC. For example it is possible to transmit up to 100 MW over 100 miles through a single subsea cable. In addition, it is also viable to transit 200 MW at 145 kV from a vessel to shore.

Water treatment

Modern FSRWP’s use reverse osmosis membrane technology to produce industrial or potable water.  This is similar to most conventional onshore desalination plants.
The main benefits of floating offshore desalination are increased overall thermal efficiency if both power and water production are combined on a single vessel. In addition, seawater sourced offshore and rejected brine discharged offshore minimizes risk to coastal marine life.

Conclusion

The bottom line is that if your mining project is near shore, and has both water supply and power issues, take a look at the FSRWP technology. One might say it is greener technology by using LNG (rather than coal, heavy fuel oil, or diesel) to generate power.  At the same time it avoids competition with locals for access to fresh water.
This technology won’t be suitable for all mining situations, but perhaps your mine site fits the model. Reportedly rough costs for power are in the range of $0.10-$0.14/kwh with a capital cost of $1M-$1.5M per MW.
There will be minimal closure costs associated with dismantling the power plant.  One just floats it away at the end of the mine life.
Check out the MODEC website if you wish to learn more: https://www.modec.com/fps/fsrwp/index.html
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For those interested in reading other mining blogs, check out the Feedspot website at the link below. They list 60 mining related blog sites that you check out. https://blog.feedspot.com/mining_blogs/
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Cyber Security – Coming to a Mine Near You

The mining industry is being told to take advantage of digitalization. As an example, here is a link to a recent article that discusses this “Can mining decode the opportunities of the future?”. The article says “To achieve sustainable improvements in productivity, mining companies will need to overcome a digital disconnect that has held them back”.
I fully agreement with this sentiment, although there are some cautions when adopting new technology.

Not everything is positive

The mining industry will see positive impacts from digitalization.  Unfortunately more reliance on technology also brings with it significant risks.  These risks are related to cyber security.
I recently attended a CIM presentation here in Toronto that focused on cyber security, specifically related to the mining industry. The potential negative impacts to a company can be significant.
Some mining companies already have experienced these negative impacts, albeit in some cases it may not be well publicized. I will highlight some examples later in this blog.
(By the way, I appreciate that the CIM presenter gave me access to the information in his presentation).

Attackers and threats

There are several ways that mining companies can be attacked via technology channels. The attackers could be foreign governments, anti-mining groups, disgruntled employees, or just your average everyday miscreant. There are several avenues as described below.
  • Hack-tivsm: Where a company website may be defaced and blocked as part of a campaign against the opening of a new operation.
  • Data Breaches: Security breaches on websites resulting in leaked sensitive data including personal identification, credentials, and investor information.
  • Industrial Control Attack: Amending software code on major equipment resulting in shutdown or damage.
  • Business Interruption: Attacking systems so the company must be temporarily disconnected from the internet and forcing replacement of all hard drives and servers.
  • Dependent Business Interruption: Overwhelming servers in order to degrade cloud services and websites.

Examples

The following are some examples of how different attack approaches have been used with success.
  • April 2016 – a Canadian gold-mining firm suffered a major data breach when hackers leaked 14.8 GBs of data containing employee personal information and financial data.
  • May 2015 – a Canadian gold mining company was hacked resulting in 100GBs+ worth of stolen data being released.
  • May 2013 – a large platinum producer experienced a security breach on their website resulting in leaked sensitive data online including personal data, credentials, and investor information.
  • February 2015 – A junior mining company was the victim of a cyber scam that resulted in the company paying a $10M deposit into an unknown bank account intended for a sub-contractor.
  • November 2011 – In an attempt to gain information on bid information about a potential corporate takeover, hackers attacked the secure networks of several law firms and computers of the Government of Canada’s Finance Department and Treasury Board.
  • August 2008 – Hackers were able to gain access to the operational controls of a pipeline where they were able to increase the pressure in the pipeline without setting off alarms resulting in an explosion. Beyond damaging the pipeline, the attack cost millions of dollars and also caused thousands of barrels of oil to spill close to a water aquifer.
  • 2014 – A steel mill was the victim of a phishing attack which allowed attackers to gain access to their office network causing outages of production networks and production machines. The outages ultimately resulted in a blast furnace not being properly shut down causing significant damage to the plant.
  • 2003 – Cyber attackers were able to gain access to the SCADA network of an oil tanker resulting in an 8 hour shutdown.
  • August 2012 – A large state-owned oil and gas supplier, experienced an attack intended to halt their supply of crude oil and gas which resulted in more than 30,000 hard drives and 2,000 servers being destroyed ultimately forcing I.T. systems to be disconnected from the internet for two weeks.
  • 2014 – Malware was used to gain access to a Ukrainian regional electricity distribution company to gain remote access to SCADA systems and remotely switch substations off, leaving 225,000 without electricity for three hours.
How many similar incidents have occurred, being unreported or not as publicly visible as these?  Recently Air Canada had a major computer outage.  Was that a squirrel chewing through a wire or a full-on cyber attack?

Ask yourself if you are ready

As your mining company continues to move into the digital world, you must ask:
  1. If an attacker were to disable your business application or a production facility, how long would it take to recover? How much would it cost you? How would you even measure the cost?
  2. How do you ensure your third party vendors’ security standards are appropriate? What would you do if a key supplier or key customer had a data breach that impacted you or hinder their deliveries? How do you mitigate your exposure to such events?
  3. What type and how much sensitive information are you responsible for? If you learned today that your network was compromised, what is your response plan?  Who would you call to investigate a data breach? What law firm would you use and do they have breach response experts?
A cyber attack can impact on operations, public perception, legal liability, and corporate trust.  This can mirror the legal impact of a tailings dam failure.  So are there any mitigations?

Cyber insurance is available

Companies can now consider the growing cyber insurance industry. Traditional insurance indemnifies property, casualty, crime, errors & omissions, and kidnap & ransom events. Cyber insurance adds additional coverage for breaches related to data confidentiality, operations technology malfunctions, network outages, disruption of 3rd parties, deletion or corruption of data, encryption of data, cyber fraud and theft.
While nobody wants to add another cost burden on their business, the gains from digitalization don’t come without pains.

Conclusion

The bottom line is that there is no stopping the digitalization of the mining industry. It is here whether anybody likes it or not. At the same time, there is likely no stopping the growth of cyber crime.
Likely we will hear more hacking stories as miners adopt more of the new technology.
The first line of defense are your security policies and procedures.  Bring in an expert for a security audit. As an option, you can contact cyber insurance brokers that have the expertise to help.
 Its great to see an executive at the head office operating a scooptram at their underground mine.  Its not so great to see some kid in a basement operating that same scooptram (and setting production records).
Open your doors to technology but at the same time keep them locked.
Note: If you would like to get notified when new blogs are posted, then sign up on the KJK mailing list on the website.  Otherwise I post notices on LinkedIn, so follow me at: https://www.linkedin.com/in/kenkuchling/.
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