Tailings Management

Spying on Tailings Using Satellites

Date: June 28, 2024 Author: Ken Kuchling Comments: Leave a reply
There have been recent heap leach pad failures in the Yukon and Turkey and tailings dam failures in Chile and the Philippines.  As a result I have been seeing more posts on LinkedIn about the application of satellite based InSAR deformation monitoring.  Prior to that I had never heard of InSAR, so thought a little bit of background study might be worthwhile.
The following are my observations on what InSAR is and where it may be going.  I am by no means an expert in this technology.  I am merely viewing it from the perspective of a mine design engineer.

What is InSAR

InSAR is satellite-based “Interferometric Synthetic Aperture Radar”.    It can measure the distance from a satellite to a ground feature.  With repeated imaging it is used to detect changes in distance and measure displacements to within 5-10 millimetre accuracy.  Hence it can be used as a potentially cost-effective slope monitoring tool, albeit it cannot be the only tool, as discussed later.
The relevant satellite images have been available for years.  Currently the availability of analytical software to interpret the satellite data is improving.   It can detect millimeter-scale displacements, however only in the line-of-sight (LOS) direction of the satellite.   Using two or more satellites in different orbits, displacements in horizontal and vertical directions can be defined.
An example of a satellite being used is the Sentinel-1, launched in mid-2015 by the European Space Agency. This satellite information is open-source data.  It will have a 6 to 12 day revisit cycle in many locations.
The results of an InSAR displacement survey are typically shown as a series of colored data points, typically coloured green for the stable points, trending to yellow and red for points that are moving.
This blog has some example images.

Some Limitations With InSAR

There are some limitations with InSAR, so it can only be part of a monitoring program.  These limitations are:
  • The displacement direction is only measured in the direction of the satellite.  Hence one may not know in which direction the movement is occurring.  The magnitude of displacement could be underestimated depending on the apparent angle of measurement.
  • The movement being measured could consist of vertical settlement due to material consolidation and may not be horizontal and related to impending failure.
  • The displacement magnitude measured on opposite sides of a facility may have different accuracy, depending on the slope orientation versus the line-of-sight.
  • Areas with heavy vegetation may be difficult to monitor
  • Areas with heavy or persistent cloud cover can be difficult to monitor.
  • Areas with snow cover will be difficult to monitor.
  • The satellite return period may be weekly or every two weeks, so one is not able to analyze daily movements if a situation is critical.  If the return visit day has cloud cover, there will be no new satellite data collected.
  • Areas with on-going construction or tailings deposition will lead to erroneous results.
  • Due to the line of sight, not all slope failure modes may be detectible (for example piping failure).
Regardless of these limitations, InSAR can still play a role in any monitoring program since it is able to monitor large areas quickly.   Consider it as a pre-screening tool, being aware that not all failure modes may be detectible with it.

Discussion

On LinkedIn, one can see numerous posts where independent experts are examining historical InSAR data for recent failures to see whether early movement should have been detected.  The results seem to be quite positive in that areas that have failed might have been red-flagged prior to failure.
There are also zones that showed critical displacements but have not failed.
Typically, there are four ways to monitor displacement in pit slopes, tailings dams, heap leach pads, and waste dumps.   They are:
  1. Insitu monitoring using embedded instruments, for example slope indicators, extensometers, and settlement gauges.  These instruments provide information on what is happening internally within a slope, where actual movement is occurring, and they can be used in warning alert systems.
  2. Surface monitoring using radar (ground based InSAR) systems and survey prisms.  These tools measure only surface movements in selected areas, can be monitored as frequently as needed on an automated basis, and integrated into warning alert systems.
  3. Drone or aerial surveys can be used to measure topography and monitor movements over large areas.   This method requires a data processing delay (not real time) to derive the movement information, but such surveys can be done as frequently as needed.
  4. InSAR from satellite can be used over very large regions to highlight areas with movement.  That should trigger the implementation of one or more of the other monitoring approaches (if not already in place).

Conclusion

A mining site consists of numerous constructed embankments and slopes of all types and heights.  Many of these slopes may be creeping and moving all the time – it’s a living beast.
The operator’s awareness about their site will be better the more monitoring tools they use.  This awareness is important given the critical role that slope stability plays.  We will see if InSAR technology achieves much wider adoption in the mining industry as a first phase of a stability monitoring programs.
Since InSAR monitoring is done from space, it does not require access to a property.  Hence it can be used by third parties or NGO’s to “spy” on facilities of concern anywhere.
Possibly over the next few years we will see independent donor-funded organizations monitoring tailings facilities around the globe.  They will be able to notify the public and mine operators “Hey, there is some movement on this mine site that needs to be addressed”.    An organization called World Mine Tailings Failures has started some discussions on this concept.   Check it out.
Finally, it is great for a mine site to collect a lot of displacement data, hopefully to forewarn of movement, displacement acceleration, and imminent failure.  However, this assumes that someone experienced is interpreting the data and its not just generating graphs for the file cabinet.   Perhaps AI can play a role here in the future, if the technical personnel to do this are lacking.
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Filtered Tailings Testing Checklist

Date: June 12, 2024 Author: Ken Kuchling Comments: 1 Reply
I have always been a big proponent of filtered (or dry stack) tailings over conventional tailings disposal. Several years ago I had written a blog (Fluid Tailings – Time to Kick The Habit?)  that this is the tailings disposal approach the mining industry should be moving toward.
Recently I have been seeing more mining studies proposing to use the dry stack approach. In some cases, they no longer even do the typical tailings trade-off study that look at different options. The decision is made upfront that dry stack is the preferred route due to its environmental acceptability and positive perceptions.
Recently I came across a nice document prepared by BHP and Rio Tinto titled “Filtered Stacked Tailings – A Guide for Study Managers (March 2024)”. I will refer to this document as “The Guide”. You should definitely get a copy of this Guide if your project is considering a dry stack operation. An information link is included at the end of this post.

A Guide for Study Managers

The Guide covers several topics, including tailings characterization; site closure concepts; filtered tailings stack design; material transport, stacking systems; and tailings dewatering methods. The Guide covers all the basics very well. The one area that jumped out at me is the tailings characterization and testing aspect.
Many assume that dry stack is simply filter, haul, dump, then walkaway. Its all very easy! However, in reality, the entire dry stack approach is complex.
One needs to be able to consistently dewater tailings from different ore types, then transport it under different climatic conditions, and then place and compact the tailings efficiently.
One also needs to be able to deal with plant upsets, when the filtered tailings don’t meet the optimal product specifications. So its not really that simple.
One of the chapters in the Guide details the different test work that should be done to understand the dry stack approach.  The list of tests is a lot longer than I had envisioned.  I previously knew some of the types of lab testing required, however the Guide outlines a very comprehensive list.
The Guide also categorizes the tests according to study stage, be it concept study, order of magnitude study, or Pre-Feasibility level. Interestingly, the concept study can rely mainly on published information. However, the more advanced mining studies require the lab testing of actual tailings material.

Testing Checklist

To help organize the complexity of testing, I have listed their suggested tests as to whether the test is related to material characterization, process characterization, or filtered product characterization. Each aspect serves a different purpose in understanding the workings of the filtered tailings approach. The engineer will decide at which study stage they wish to do each of the tests, or which of the them they actually need to do.
To keep the blog post brief, I am not describing the details for each test. Most geotechnical or process engineers will already be familiar with them, or anyone can search the web to learn more.

MATERIAL CHARACTERIZATION TESTS

  • Chemical composition Testing: using atomic absorption or spectroscopy, identify the elements within the tailings stream to highlight contaminants and potential flocculation issues.
  • Conductivity Test: increase knowledge of the tailings stream.
  • Mineralogy Testing: identify mineral types and clay minerals (if any) that could impact on performance.
  • Particle Shape Analysis: are there fibrous minerals present, as well as settling and rheology effects.
  • Particle Size Distribution: are the tailings coarse, or mainly fine silt and clay sized particles that can impact on filtering and product performance.
  • pH Test: determine the acidity of the tailings steam, can relate to flocculant selection.
  • Tailings Slurry Density Test: assess the pumpability and amount of thickening and filtering that will be required.
  • Tailings Solid Mass Concentration and Moisture content: required for process mass balances.
  • Specific Gravity Testing: assess the SG of the tailing particles, i.e. light or heavy minerals.
  • Total Dissolved Solids Test: assess the fluid composition, are minerals dissolvable.
  • Zero Free Water Test: relates to the solids concentration at which the sample is fully saturated and may relate to transportability.

PROCESS CHARACTERIZATION TESTS

  • Total Suspended Solids: assess the quality of the return water from thickening or filtration.
  • Drained and Undrained Settling Test: to assess the thickening aspects and stack performance.
  • Setting Cylinder Tests: used to assess thickener settling performance.
  • Raked Setting Cylinder Tests: used to assess thickener settling performance.
  • Dynamic Continuous Settling Tests: used to assess thickening under continuous feed situation.
  • Minimum Moisture Content: assess the minimum moisture content achievable in filtration.
  • Vacuum/Pressure Filtration Test: often done by vendors, assess the filtering performance.
  • Compression Rheology: design consolidation / permeability data for filtering and disposal design.
  • Shear Rheology: provide information for pump and pipeline design.
  • Shear Yield Stress: provide processing insights for slurry dispersion and flocculation.

FILTERED PRODUCT CHARACTERIZATION TESTS

  • Leaching Tests (long term): assess whether the tailings stack will continue to leach metals and contaminants over the long term.
  • Leaching Tests (short term): assess whether the tailings stack will rapidly leach metals and contaminants.
  • Acid Base Accounting Tests: will the stack be an ARD concern.
  • Net Acid Generation: relates to ARD and neutralizing potential.
  • Air Drying Tests: determine the rate of natural air drying and dry density.
  • Atterberg Limits Testing: determine the plastic limit, liquid limit with respect to moisture content and stackability.
  • Consolidation Tests (one-dimensional): to assess the consolidation and settlement of the stack over time.
  • Proctor Density Tests: assess the optimal compacted density and moisture content vs the moisture content delivered by filtration.
  • Critical Void Ratio Tests: assess compaction, consolidation, and liquefaction potential.
  • Shear Testing: determine the geotechnical strength of the filtered product for stack height design.
  • Permeability Testing: assess the internal drainage characteristics of the filtered product.
  • Soil-water characteristics Tests: assess the unsaturated behavior of the filtered product.
  • Flow Moisture Point Tests: assess how well the material can be transported and placed.
  • Conveyance Testing: assess how well the material can be conveyed (troughing, steepness).
  • Minimum Angle for Discharge: used in the design of hoppers and chutes.
  • Angle of Repose Tests: used in hopper design and dry stack design. Ground Bearing Pressure: used to assess the trafficability of the deposit.

Conclusion

A dry stack operation might be just as complex as conventional tailings disposal, although that might not be the perception. Certainly, the processing side of filtered tailings is more complex than conventional tailings. The transportation design may also be more complex, as is the tailings placement methodology. The main complexity missing from the dry stack is the need for a large sludge retaining dam, albeit that is a huge and important difference.
Some might view the suggested testing checklist as overkill and decide that not all test work is necessary. That is most likely true for some situations, especially for small mines not dealing with large quantities of tailings. However for a project with a high capital investment, one doesn’t want to see the entire mill off-line because the tailings disposal system isn’t functioning.
Major miners, such as BHP and Rio Tinto, typically spare no expense on material testing for metallurgical or geotechnical purposes. They have the funds available to test and engineer to a high level to adequately de-risk the project to meet their investment thresholds.
Junior miners often don’t have the time or funds to spend on such comprehensive testing programs. “Good enough” is often good enough.
One reason why junior miners sign 5-year JV deals with the Major is the amount of technical work required to properly evaluate a project.
The Major understands the amount of time needed for sample collection, testing, analysis of results, and follow up with more testing. It takes a fair bit of time to reach a comfort level for moving forward. Even then, there are no guarantees of success.
Each tailings disposal project is unique in size, location, type of mineralization, site layout, and throughput rate, so each company must decide what level of testing is “good enough” to address their risk tolerance.
For those that would like to get a copy of the the Guide, you can find more information at this LinkedIn link.   I thank BHP and Rio Tinto for putting their heads (and wallets) together to prepare (and share) this document.

 

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Sustainable Mining – What Is It Really?

Date: December 6, 2019 Author: Ken Kuchling Comments: 4 Replies
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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Mineral Processing – Can We Keep It Dry?

Date: September 30, 2019 Author: Ken Kuchling Comments: 3 Replies
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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Landslide Blog – If You Like Failures

Date: April 5, 2016 Author: Ken Kuchling Comments: 2 Replies
slope failure blog
For those of you with a geotechnical background or have a general interest in learning more about rock slides and slope failures, there is an interesting website and blog for you to follow.
The website is hosted by the American Geophysical Union the world’s largest organization of Earth and space scientists. The blogs on their site are written by AGU staff along with contributions from collaborators and guest bloggers.

Landslide Blog screenshot

The independent bloggers have editorial freedom in the topics they choose to cover and their opinions are those of their authors and do not necessarily represent the views of the American Geophysical Union. This provides for some leeway on the discussions and the perspectives the writers wish to take.

Landslide Blog

One specific area they cover well in their Landslide Blog are the various occurrences of rock falls and landslides from any location around the globe. They will present commentary, images, and even videos of slope movements as they happen.
Often they will provide some technical opinion on what possibly caused the failure event to occur. The Landslide Blog has a semi-regular email newsletter that will keep you updated on new stories as they happen.
The following links are a few examples of the type of discussions they have on their website.
Here is a description of a small water dam failure in Greece.
Here is some video of the Samarco tailings runout in Brazil.
From time to time the Landslide Blog will examine mine slopes, tailings dams, and waste dump failures, however much of their information relates to natural earth or rock slopes along roads or in towns.
Some of their videos are quite fascinating, illustrating the forces behind some of earth’s natural erosion processes. Check it out for yourself.
The bottom line on all of this is that the less the mining industry is mentioned in the Landslide Blog, the better it is.
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Tailings Disposal Method Risk

Date: March 8, 2016 Author: Ken Kuchling Comments: 4 Replies
mine tailings
After the Mt Polley and Samarco tailings failures, there have been ongoing discussions about the benefits of filtered (dry stack) tailings as the only way to eliminate the risk of catastrophic failure. Mining companies would all like to see risk reductions at their projects.

Filtered tailings stack

However what mining companies don’t like to see are the capital and operating costs associated with dry stacking.
The filtering cost and tailings transport cost are both higher than for conventional tailings disposal. Obviously this cost increase gets offset against improved environmental risk and simpler closure.

What should a mining company do?

In my experience, when designing a new mining project, all companies will complete a trade-off study for different tailings disposal methods and disposal sites. Contrary to some environmental narratives, mining companies really do want to know what are their tailings disposal options.  They would likely all adopt the dry stack approach if it was the most advantageous and least cost method.
The mining companies are fully aware of the benefits but the dilemma is the cost and being able to somehow justify the technology. Complicating their decision, companies also have other ways for reducing tailings risk.

The tailings decision gets complex.

In a tailings risk analysis, people will use a risk-weighting approach to assign an expected economic impact to their tailings plans. For example, if the cost of a failure is $200 million and the risk is 0.1%, then the Expected Cost is $200,000. The problem with this is its based on a theoretical calculation on an assumed likelihood of failure.
In reality either the dam will fail or it won’t.  So failure remediation money will be spent ($200M) or it won’t be spent ($ zero), it won’t be partially spent ($200k).
The accepted tailings risk therefore becomes a subjective factor.
While implementing a dry stack may reduce the risk of catastrophic failure to near zero, implementing a $100,000 per year monitoring program on a conventional tailings pond will reduce its risk to a degree.
Implementing a more expensive $500,000 per year monitoring program would reduce that risk even further.
Installing in a water treatment plant to enable periodic water releases may further lower the tailings risk.
The company can look at various mitigation options to keep lowering their risk, although none of the options would necessarily bring the risk down to zero. Ultimately the company could compare the various risk mitigation options against the dry stack costs in order to arrive at an optimal path forward.  At that point the costs for dry stack may be competative.

What level of risk is acceptable?

So the question ultimately becomes how low does one need to bring the tailings risk before it is acceptable to shareholders, regulators, and the public. I don’t think the answer is that one must lower the risk down to zero. There are not many things in today’s world that have zero risk. Driving a car, air travel, shipping oil by ocean tanker, having a gas furnace in your house.. none of these have zero risk yet we accept them as part of life.
Environmental groups continually discuss ways of forcing regulators and mining companies to take action against the risk of tailings failure. This is commendable.
However they generally fail to provide any guidance on what level of risk would be acceptable to them or to the public. It is difficult for these groups to actually define what an acceptable risk level is. They offer no solutions, other than its either zero risk or shut down all mining.

Conclusion

We know that mining is here to stay so we all should work together towards solutions.
The solutions need to be realistic in order to be taken seriously and to play a real role in redefining tailings disposal. Dry stack may not be the only solution and we should be looking for more ways to improve tailings disposal.
Since these other options don’t seem to be available yet, dry stack tends to offer the best solution in most circumstances.  I have written another blog on this topic where I suggest the industry just bite the bullett and go to dry stack in all new projects.  The trend appears to be going that way but no where near 100% acceptance.   You can read that post at this link  “Fluid Tailings – Time to Kick The Habit?”

 

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Fluid Tailings – Time to Kick The Habit?

Date: November 12, 2015 Author: Ken Kuchling Comments: 8 Replies
dry stack tailings
What is one thing that we constantly hear about negatively yet we continue to do it (although we know it can be bad for us)?    Is that thing smoking or is it fluid tailings storage? Can we break either of these habits?

Short term pain for long term gain.

Those of us in the mining industry constantly hear from stakeholders about the negative impacts of fluid tailings storage.  By “fluid” I mean conventional tailings that can liquify and flow great distances.  We know of numerous mines that have had failures, resulting in fatalities and catastrophic damage. Check out the horrific example video below. It appears some people were walking or driving mid-way up the dam face.
We also know of many mines that have used fluid tailings their entire operating lives without any incidents.  Therefore some say it is fine to continue doing that.
The question for me has become whether the mining industry should kick the habit of fluid tailings storage even though not every dam has failed.

Quitting isn’t easy

Quitting smoking takes real effort, some pain, maybe a change in lifestyle, but most importantly an overall commitment to quit.   It isn’t easy but pays off in the long run.
The same holds for fluid tailings storage.
Moving away from conventional tailings storage requires real effort, some pain, a change in operating style, and a commitment to quit.  It won’t be easy but will pay off in the long run by avoiding major tailings incidents, less negative press, and fewer environmental permitting issues.  No longer will consultants and regulators be disputing factors of safety of 1.2 versus 1.5, when they could be discussing factors of safety of 5 versus 10.
Quitting fluid tailings storage may bring relief to stakeholders, shareholders, regulators, and mine management.  They’ll all sleep better at night knowing there isn’t a large mass of fluid being restrained simply by a dam at a factor of safety of 1.5.  Engineers say they can design dams that will be stable for perpetuity.  Even if one agrees with that statement, that is still no guarantee that failures won’t happen somewhere.

Conclusion

The bottom line is that no one wants to sit downwind of a smoker and no one wants to live downstream of a tailings dam.  Perhaps it is time for the mining industry to kick the habit of fluid tailings storage, regardless of the cost and discomfort. Short term pain for long term gain.
In another blog post I have discussed how tailings storage always require a tradeoff between cost and risk.  Normally lower cost options present high risks, and vice versa. How much risk is acceptable to a company or to the public?   You can read that post at this link “Tailings Disposal Method Risk“.
For those wishing to pursue the dry stack approach, a series of laboratory tests are required to characterize the talings, the process, and the placement method.  You can see a checklist of the test options at this blog post “Filtered Tailings Testing Checklist“.

 

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Oil Sands vs Tar Sands – Something I’ve Been Wondering About

Date: May 26, 2015 Author: Ken Kuchling Comments: 1 Reply
tar sand mining
Watching the television news in Canada these days, one sees the environmental opponents of the oil sands parading around with signs that say “Stop the Tar Sands”.  One way to distinguish whether someone is for or against the oil sands is to see what terminology they use.  Do they call them “oil sands” (i.e. pro groups) or “tar sands” (i.e.anti groups)?   Personally raw bitumen seems more tar-like than oil-like so the enviro’s seem to have it right.

Is it Oil Sands or Tar Sands

Going back many decades the oil sands were originally called the tar sands.  I’m not sure when the terminology shifted, but in the mid-1960’s the first large scale mining operation was called Great Canadian Oil Sands (GCOS).  I’m not sure why the terminology shift from tar to oil, but maybe it was related to the fact that “tar” was considered something of low perceived value while “oil” was considered something of high economic value.
Jed Clampett and familyLook at what oil did for the economic situation of Jed Clampett on the Beverly Hillbillies.  How about the show “Dallas”? There was also a lot of money and scotch drinking.
Back then we all wanted to discover an oil well in our backyard so perhaps the term “oil” implied some level of elegance and prosperity.
These days when one sees the term “oil” in the news, it tends to be associated with negatives.  We see oil references to rail explosions, pipeline ruptures, tanker spills, job layoffs, fracing, carbon emissions, Middle East wars, and protests.
These days I don’t know if there is any intangible benefit in using the term “oil” to describe your product anymore.  Maybe there is actually some intrinsic harm in doing so.
Tar sand bitumenTar (or bitumen) on the other hand, is a molasses-like substance generally viewed by the public as a material used to repair our streets and patch our roofs. A tar spill is not going to flow anywhere; it will barely flow out of the tank it is held in.  What is there not to like about tar?
So next time there is a protest with signs being held up to “Stop the Tar Sands”, the oil companies should shrug their shoulders, jump on the band wagon, and say “Yeah, tar, that’s us. So what are you worried about?”.
They should try to commandeer the word “tar” back from the protest groups since there really is nothing wrong with tar.  There seems to be a lot wrong with oil.

 

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