Articles tagged with: exploration

Don’t Cut Corners, Cut Cross-Sections Instead

Exploration cross-sectionThis article is about the benefit of preparing (cutting) more geological cross-sections and the value they bring.
Geological sections are one of the easiest ways to explain the character of an orebody. They have an inherent simplicity yet provide more information than any other mining related graphic.
Some sections can be simple cartoon-like images while others can be technically complicated, presenting detailed geological data.
Cartoon-stylized sections are typically used to describe the general nature of the orebody. The detailed sections can present technical data such as drill hole traces, color coded assays intervals, ore block grades, ore zone interpretations, mineral classifications, etc.
Sections provide a level of clarity to everyone, including to those new to the mining industry as well as those with decades of experience.
This article briefly describes what story I (as an engineer) am looking for in sections. Geologists may have a different view on what they conclude when reviewing geological sections.
I will describe the three types of geological sections that one can cut and what each may be describing. The three types are: (1) longitudinal (long) sections; (2) cross-sections; (3) bench (level) plans. Each plays a different role in helping to understand the orebody and mining environment.
There is also another way to share simple geological images via3D PDF files. I will provide an example later.

Longitudinal (Long) Sections

Geological long section examplesLong sections are aligned along the long axis of the deposit. They can be vertically oriented, although sometimes they may be tilted to follow the dip angle of an ore zone.
Long sections are typically shown for narrow structure style deposits (e.g. gold veins) and are typically less relevant for bulk deposits (e.g. porphyry).
The information garnered from long sections includes:
  • The lateral extent of the mineralized structure, which can be in hundred of metres or even kilometers. This provides a sense for how large the entire system is. Sometimes these sections may show geophysics, drilling to defend the basis for the regional interpretation.
  • Long sections will often highlight the drill hole pierce points to illustrate how well the mineralized zone is drilled off. Is the ore zone defined with a good drill density or are there only widely spaced holes? As well, long sections can show how deep ore zone has been defined by drilling. On some projects, a few widely spaced deep holes, although insufficient for resource estimation purposes, may confirm that the ore zone extends to great depth. This bodes well for potential development in that a long life deposit may exist.
  • Sometimes the long section drill intercept pierce points can be contoured on grade, thickness, or grade-thickness. This information provides a sense for the uniformity (or variability) of the ore zone. It also shows the elevations of the higher grade zones, if the deposit is more likely an open pit mine, an underground mine, or a combination of both.

Cross-Sections

Geological pit sectionCross-sections are generally the most popular geological sections seen in presentations. These are vertical slices aligned perpendicular to the strike of the orebody. They can show the ore zone interpretation, drill holes traces, assays, rock types, and/or color-coded resource block grades.
As an engineer, my greatest interest is in seeing the resource blocks, color coded by grade. Sometimes open pit shells may be included on the section to define the potential mining volume. The engineering information garnered from block model cross-sections includes:
  • Where are the higher-grade areas located; at depth or near surface?
  • If a pit shell profile is included, what will the relative strip ratio look like? Are the ore zones relatively narrow compared to the size of the pit?
  • How will the topography impact on the pit shape? In mountainous terrain, will a push-back on pit wall result in the need to climb up a hillside and create a very high pit slope? This can result in high stripping ratios or difficult mining conditions.
  • Does the ore zone extend deeper and if one wants to push the pit a bit deeper, is there a high incremental strip ratio to do this? Does one need to strip a lot of waste to gain a bit more ore?
  • Are the widths of the mineable ore zones narrow or wide, or are there multiple ore zones separated by internal waste zones? This may indicate if lower-cost bulk mining is possible, or if higher cost selective mining is required to minimize waste dilution.
  • How difficult will it be to maintain grade control? For example, narrow veins being mined using a 10 metre bench height and 7 metre blast pattern will have difficulty in defining the ore /waste contacts.
  • Cross-sections that show the ore blocks color coded by classification (Measured, Indicated, Inferred), illustrate where the less reliable (Inferred) resources are located and how much relative tonnage may be in the more certain Measured and Indicated categories.
Geological cross-section exampleWhen looking at cross-sections, it is always important to look at multiple cross-sections across the orebody. Too often in reports one may be presented with the widest and juiciest ore zone, as if that was typical for the entire orebody.  It likely is not typical.
Stepping away from that one section to look at others is important. Possibly the character of the ore zones changes and hence its important to cut multiple sections along the orebody.

Bench (Level) Plans

Mining Bench PlansBench plans (or level plans) are horizontal slices across the ore body at various elevations. In these sections one is looking down on the orebody from above.
Level plans are typically less common to see in presentations, although they are very useful. The level plans may show geological detail, rock types, ore zone interpretations, ore block grades, and underground workings.
The bench plan represents what the open pit mining crews would see as they are working along a bench in the pit. The information garnered from bench plans that include the block model grades includes:
  • Where are the higher-grade areas found on a level? Are these higher grade areas continuous or do they consist of higher grade pockets scattered amongst lower grade blocks?
  • Do the ore zones swell or pinch out on a bench? A vertical cross-section may give a false sense the ore zones are uniform. The bench plan gives an indication on how complicated mining, grade control, and dilution control might be for operators.
  • Do the ore zones on a bench level extend out beyond the pit walls and is there potential to expand the pit to capture that ore?
  • On a given bench what will the strip ratio be? Are the ore zones small compared to the total area of the bench?
As recommended with cross-sections, when looking at bench plans, one should try to look at multiple elevations.  The mineability of the ore zones may change as one moves vertically upwards or downwards through a deposit.

Never mind cross-sections – give me 3D

While geological sections are great, another way to present the orebody is with 3D PDF files to allow users to view the deposit in three-dimensions. Web platforms like VRIFY are great, but I have been told they sometimes can be slow to use.
Mining 3D PDF file3D PDF files can be created by some of the geological software packages. They can export specific data of interest; for example topography, ore zone wireframes, underground workings, and block model information. These 3D files allows anyone to rotate an image, zoom in as needed and turn layers off and on.
You can also create your own simplistic cross-sections through the pdf menus (see image).
A simple example of such a 3D PDF file can be downloaded at this link (3D DPF File Example). It only includes two pit designs and some ore blocks to keep it simple.
The nice thing about these PDF files is that one doesn’t need a standalone viewer program (e.g. Leapfrog viewer) to view them. They are also not huge in size. As far as I know 3D PDF files only work with Adobe Reader, which most everyone already has.  It would be good if companies made such 3D PDF files downloadable along with their corporate PowerPoint presentations.

Conclusion

Exploration cross-section exampleThe different types of geological sections all provide useful information. Don’t focus only on cross-sections, and don’t focus only on one typical section.  Create more sections at different orientations to help everyone understand better.
In 2019 I wrote an article describing the lack of geological cross-sections in many 43-101 technical reports. The link to that article is her “43-101 Reports – What Sections Are Missing?
Geological sections are some of the first items I look for in a report. Sometimes they can be hidden away in the appendices at the back of the report. If they are available, take the time to actually study them since they can explain more than you realize.
Note: You can sign up for the KJK mailing list to get notified when new blogs are posted. Follow me on Twitter at @KJKLtd for updates and other mining posts. The entire blog post library can be found at https://kuchling.com/library/
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Polymetallic Drill Results – Interesting or Not?

A while ago I posted an article about how one can evaluate the economic potential of a gold deposit using early-stage exploration intercepts.  That article can be found at this link.   Doing the same evaluation for a polymetallic deposit is a bit more challenging.  There will be different metals of interest, with variable grades, prices, and process recoveries.
When disclosing polymetallic drill results, many companies will convert the multiple metal grades into a single equivalent grade.  I am not a big proponent of that approach.
I prefer using the rock value, whether calculated as a recoverable “NSR dollar value per tonne” or as an “insitu value per tonne”.  Either rock value is fine for my purposes.
Interestingly NI 43-101 prohibits the disclosure of insitu rock value but allows the use of metal-equivalents.  In my view this is a bit counter-intuitive since the equivalent grade  can be more misleading than rock value.

What can drill intercepts show

The three aspects that interest me the most when looking at early-stage drill results are:
  1. The economic value of the rock (in $/t tonne). This can either be “insitu value” (assuming 100% recovery, 100% payable) or the “NSR value” incorporating recovery and payable factors (if available).   Personally, the 100% insitu value is simpler to calculate and assess.
  2. The depth to the top of the economic zone, which indicates if this deposit would be a lower cost open pit mine or must be a higher cost underground mine.
  3. The length of the economic intervals, which indicates whether bulk mining approaches are viable versus the need to selectively mine narrow ore zones. The economic interval lengths also give a sense for the potential tonnage size (i.e. is it a big deposit or a small one).
There are two types of early-stage exploration data that can be examined with respect to the three items of interest described above.  They are (i) the drill hole assay data and (ii) the drill hole "intercepts of interest".  I will show an example of each in this post using sample data from an actual exploration program.
One can examine individual drill hole assays to calculate the rock value profile along each drill hole.  One can also examine the rock values for the major and minor intervals of interest reported in company news releases.
I normally like to examine both, but the intervals of interest data is publicly disclosed and more readily available.  Drill hole assays are often a bit harder, if not impossible, to track down.

Economic Parameters

In a polymetallic deposit, the insitu rock value is simply the summation of value of the individual metal, based on their respective assay grades.   An NSR rock value would apply an adjustment for metal recoveries and smelter payables, thereby lowering the insitu rock value somewhat.  However the insitu value is fine if there is no metallurgical or process data to rely upon.
Next one must determine what insitu rock value is deemed potentially economic, i.e. the breakeven cutoff.
One can estimate a processing cost and G&A cost.  In an open pit scenario, one doesn’t include the mining cost since the goal is to decide whether to send a truck to the waste dump or to the crusher. Only the processing and G&A cost musts be recovered by the ore value.   In an underground mining scenario, one would include the mining cost in the cutoff calculation.
In our example, lets assume a unit processing cost of $12/t and a G&A cost of $$2/t, for a combined cost of $14/t.    If we envision a metal recovery range of 75%-95%, we can assume 85% for now.
If we envision a smelter payable range of 75% to 95%, we will assume 85% for that also.
The “NSR factor” would now be 85% x 85% or 75%. Therefore, if the breakeven cost is $14/t, then one should target to mine rock with an insitu value greater than $20/tonne  (i.e. $14 / 0.75). This would be the approximate ore vs waste cutoff.  It is still only ballpark estimate at this  early stage, but good enough for this type of review.
Normally it would be nice to see the average head grade (or rock value) at 3 to 4 times greater than the cutoff grade.  This is not a necessity but it is a positive factor.
For example, in a gold deposit with a 0.3 g/t cutoff, one would like to see average head grades at least 0.9 to 1.2 g/t or more.  If the average head grade is close to the cutoff grade, then possibly the orebody tonnage may be very sensitive to changes in cutoff.  This may not be a good thing.
In our example, with a breakeven cutoff rock value of $20/t, one would like to see some ore zones with insitu values 3-4x higher, or above $60 - $80/t.   We can target >$70/t rock as a "nice to have" with $20/t as the cutoff.
So far, its all pretty simple. Let’s look at some actual exploration data to see how to apply this approach.
Our example will be a polymetallic deposit containing four metals of interest; copper, gold, cobalt, and iron.  One can examine  a few drill holes as well as the intervals of interest.
Metal prices used in this example are Cu = $4/lb, Au = $1980/oz, Co = $15.50/lb, Fe concentrate = $100/tonne, assuming 100% recovery and 100% payable for everything.

Drill Hole Assays Examples

The following three graphs show down hole profiles for Drill Holes A, B, C.  For each hole there are two plots. One plot shows the insitu rock values down the hole.  The second plot is the same, except the x-axis minimum has been set to the breakeven cutoff value of $20/t. This is done simply to highlight the potentially economic zones.
Hole A:
Shows positive economic results with ore quality rock starting near surface and extending down to 120 metres.
While many of the assay values are between $20-$70/t there are a significant number exceeding $70/t.
This hole has good economic potential for production.
Polymetallic drill hole evaluation
Hole B:
Shows positive economic results with economic rock starting near surface.  There are multiple economic zones extending all the way down to 370 metres.
The upper part of the hole, from 40m to 100m, shows multiple assay values exceeding the $70 target.
A second potentially economic zone is seen at a depth of 130m to 190m, which is still within the open pit mining range.
This hole also has good economic potential.
Polymetallic drill hole evaluation
Hole C:
For comparison purposes, Hole C is neutral in that while there are multiple potentially economic zones, they have lower insitu value.
This hole doesn't have the economic consistency that was seen in Holes A and B.
Possibly this hole may be near the edge of the ore body, in which case such a profile is not unexpected.
Polymetallic drill hole evaluation
Normally I would not spend a lot of time examining holes with little to no grade.  Some may consider this as a biased view.   However, every orebody has its limits, and what is occurring along the edges isn’t that critical in my view.
My objective is to understand what is happening in the core of the orebody, since that is what will dictate the overall economics.  Is the core of the orebody marginal value, or does it consist of high value rock?   Ultimately it will be the exploration company's task to keep drilling to define if there is sufficient tonnage of this higher value rock to justify a mine.  However this shows that at least the grades are there.

Intervals of Interest Example

The next series of plots examines the insitu rock values over drill intervals typically published in a company news releases. The intervals of interest will composite the individual assays over larger widths based on the company’s technical judgement.
It is interesting to see whether the larger intervals have good economic potential.   The following charts combine both major intervals with minor zones, often referred to as “including” in news releases. Both major and minor intervals can provide useful information.
Insitu Rock Value vs Depth:
This chart shows the rock values for multiple report intervals versus their depth (top) along the hole.
One can see multiple intervals at open pit depths (<250 m) with insitu values above the $20/t cutoff and above the $70/t threshold.
Within the upper 250 metres, we are seeing multiple intervals with good value.  That is a positive sign.
Note that these depths are not depths from surface, but distance along the drill hole.  In reality the intervals may be slightly closer to surface, depending on the hole inclination.
Polymetallic assay interval evaluation
Insitu Rock Value vs Interval Length:
The next question to ask is whether the higher value zones are narrow or wide?
In the example here one can see some wide zones (70 to 90m) with rock values in the range of $40-70/t.   These are good open pit mining widths.
There are numerous higher grade zones ($70-$200/t) in the 5m to 20m width range.   These widths are still fine for open pit mining.
Some intervals are quite narrow (<5m), being a bit more difficult to mine.  Since many of these are higher grade, they will tolerate some mining dilution.
Polymetallic assay interval evaluation

Conclusion

Although publishing insitu rock values is prohibited by NI-43-101, I find them important in my understanding the economic potential of a deposit. Reviewing the insitu rock values spatially is not difficult and can shed light on what is there. Even at a very early stage, one can get a sense of economic character of the orebody.   This is a great approach to use when doing an acquisition due diligence on an exploration stage project consisting mainly of drill hole data.
In my view, it would be beneficial if all polymetallic drill results were reported with the individual grades and using a standardized industry wide insitu rock value formula. Then one could compare projects (or even different zones on the same project) on an equal basis.   The cutoff to be applied to different projects would vary but the insitu value is what it is.
This might be better than each company applying their own unique equivalent grade calculation to their exploration results.
The equivalent grade calculation still requires assumptions on the metal prices and recoveries.  The result is, unfortunately, presented as a grade value rather than a dollar value.
The intervals of interest published in news releases are usually not available for download.   Great Bear is (was) one example where the data was available.  It would be nice if more companies followed suit by releasing their interval data in CSV or Excel format.  It worked out well for Great Bear!
Perhaps the detailed hole assay data may be too complex or voluminous to release.  Maybe this level of information is not useful except to the more technically driven investors. Nevertheless it would still be nice to have access to this drill data in electronic form, at least in the core of the orebody.
For further light reading, the two previous articles referenced above are “Gold Exploration Intercepts – Interesting or Not?" and "Metal Equivalent Grade versus NSR for multi-metals – Preference?"
Note: You can sign up for the KJK mailing list to get notified when new blogs are posted. Follow me on Twitter at @KJKLtd for updates and other mining posts.   The entire blog post library can be found at https://kuchling.com/library/
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Let A.I. Help Target Your Infill Drilling

From time to time I come across interesting new tech that I like to share with colleagues.  The topic of this blog relates to solving the problem of defining an optimal infill drill program.
In the past I have worked on some PEA’s whose economics were largely based on Inferred ore.  The company wanted to advance to the Pre-Feasibility (PFS) stage. However, before the PFS could start they would need additional drilling to convert much of the Inferred resource into Measured and Indicated resources.
I’ve seen similar experience with projects that are advance from PFS to FS where management has a requirement that the ore mined during the payback period consist of Measured classification.

The Problem

In both cases described above, it is necessary for someone to outline an infill drill program to upgrade the resource classification while also meeting other project priorities.  The goal is to design an infill drill program with minimal time and cost yet maximize resource conversion.  Possibly some resource expansion drilling, metallurgical sampling, and geotechnical investigations may be required at the same time.
I’m not certain how various resource geologists go about designing an infill drill plan.  However, I have seen instances where dummy holes were inserted into the block model and then the classification algorithm was re-run to determine the new block model tonnage classification.   If it didn’t meet the corporate objectives, then the dummy holes may be moved or new ones added, and the process repeated.
One would not consider such a trial & error solution as optimal. It may not necessarily meet the cost and time objectives although it may meet the resource conversion goals.

The Solution

The DRX Drill Hole and Reporting algorithm developed by Objectivity.ca uses artificial intelligence to optimize the infill drilling layout.  It intends to match the QP/CP constraints with corporate/project objectives.
For example, does company management require 70% of the resource in M&I classifications or do they require 90% in M&I?  Each goal can be achieved with a different drill plan.
The following description of DRX is based on discussions with the Objectivity staff as well as a review of some case studies.  The company is willing to share these studies if you contact them.
The DRX algorithm relies on the resource classification criteria specified by the company QP.  For example, the criteria could be something like “For a block to qualify as Measured, the average distance to the nearest three drill holes must be 30 m or less of the block centroid. For a block to qualify as Indicated, the average distance from the block centroid to the nearest three holes must be 50 m or less. For a block to qualify as Inferred it will generally be within 100 m laterally and 50 m vertically of a single drill hole.
The DRX algorithm will use these criteria to optimize drill hole placement three dimensionally to deliver the biggest bang for the buck.   Whatever the corporate objective, DRX will attempt to find an optimal layout to achieve it.  The idea being that fewer well targeted holes may deliver a better value than a large manually developed drill program.
The DRX outcome will prioritize the hole drilling sequence in case the drill program gets cut short due to poor weather, lack of funding, or the arrival of the PDAC news cycle.
The DRX approach can also be used to optimally site metallurgical holes and/or geotechnical holes in combination with resource drilling if there are defined criteria that must be met (by location, ore type, rock type, etc.).   The algorithm will rely on rules and search criteria developed by experts in those disciplines.  It does not develop the rules, it only applies them.
DRX can also help optimize step-out drilling, such that the step-out distance will not be beyond the range that negates the use of the hole in a resource estimate.  It can also consider geological structure in defining drill targets.

By optimizing the number of drill holes and their orientation, the company may see savings in drill pad prep, drilling costs, field support costs, and sample assaying.
One can even request drilling multiple holes from the same drill pad to minimize drill relocation costs and safety issues in difficult terrain.
A large benefit of DRX is to be able to examine what-ifs.  For example, one may desire 85% of the resource to be M&I.   However, if one is willing to accept 80%, then one may be able to save multiple holes and associated costs.   Perhaps with the addition of just a few extra holes one could get to 90% M&I.   These are optimizations that can be evaluated with DRX.

An Example

In the one case study provided to me, a $758,000 manually developed drill program would convert 96.6% of the Inferred resource to Indicated.  DMX suggested that they could achieve 96.7% for $465,000. Alternatively they could achieve 94% conversion for $210,000.  These are large reductions in drilling cost for small reductions in conversion rate.  This may allow the drill-metres saved to be used for other purposes.
For that same project, a subsequent study was done to convert Indicated to Measured in a starter pit area. DRX concluded that a 5000-metre program could convert 62% of Indicated into Measured.  A 12,000-metre program would convert 86%,  A 16,000-metre program would achieve 92%.
So now company management can make an informed decision on either how much money they wish to spend or how much Measure Resource they want to have.

Conclusion

Although I have not yet worked with DRX, I can see the value in it.   I look forward to one day applying it on a project I’m involved with to develop a better understanding of what goes in and what comes out.   DRX hopes to become to resource drilling what Whittle has become to pit design – an industry standard.
The use of the DRX algorithm may help mitigate situations where, moving from a PEA to PFS, one finds that the infill program did not deliver as hoped on the resource conversion.  Unfortunately, this leaves the PFS with less mineable ore than anticipated and sub-optimal economics.
New tech is continually being developed in the mining industry.  Hopefully this is one we continue to see forward advancement. It makes sense to me and DRX could be another tool in the geologist toolbox.  Check out their website at objectivity.ca
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Gold Exploration Intercepts – Interesting or Not?

As a mining engineer, I am not usually called in to review a project that is still at the exploration stage. This is normally the domain of the geologist. However from time to time I have an interest in better understanding the potential of an early stage mining project. This could be on behalf of a client, for investing purposes, or just for personal curiosity.
At the exploration stage one only has drill interval data from news releases to examine. A resource estimate may still be unavailable.
The drill data can consist of long intervals of low grade or short intervals of high grade and everything in between. What does it all mean and what can it tell you?
The following describes an approach I use for examining early stage gold deposits. The logic can be expanded to other metals but would take more effort.
My focus is on gold because it has been the predominant deposit of interest over the last few years, and it is simpler to analyze quickly.

We All Like Scatter Plots

My approach relies on a scatter plot to visual examine the distribution of interval thicknesses and gold grades. Where these data points cluster or how they are distributed can provide some prediction on the overall economic potential of a project. Its not a guarantee, but only an indicator.
I try to group the analysis into potential open pit intervals (0 to 200 metres from surface) and potential underground (deeper than 200m) intervals. This is because a 20m wide interval grading 2.0 g/t is of economic interest when near surface, however of less interest if occurring at a 300m depth.
Using information from a news release, I create a two column Excel table of highlighted intervals and assay grades. The nice thing about using intervals is that the company has provided their view of the mineable widths.
If one is provided with raw 1-metre assay data you would have to make that decision, which can be a significant task. The company has already helped make those decisions.
Normally I tend to use the highlighted sub-intervals and not the main intervals since issues with grade smoothing can occur.
A large interval containing multiple high grade sub-intervals may see some grade smoothing.This happens if the grade between sub-intervals is very low grade or even waste. It takes a fair bit of effort to assess this for each drill hole, hence it is easier to work with the sub-intervals.
I have an online calculator (Drill Intercept Calculator) that lets you assess if grade smoothing is occurring.
When inputting the interval thickness, I prefer to use the true thickness and not the interval length. If the assay information does not specify true thicknesses, then I simply multiple the interval length by 0.70 to try to accommodate some possible difference in width. Its all subjective.
The assays can consist of Au (g/t) or AuEq (g/t) if more metals are present. If very high grades are encountered (greater than 10 g/t) I simply input 9.9 g/t into the Excel table so they fit onto my scatter plot. Extremely high grades can be sporadic and localized anyhow.
Finally I need to decide whether the project is located in a region of high operating cost, low cost or about average costs. High costs could be with a fly in/ fly out, camp operation, with diesel power, and seasonal access.
A low cost operation could be in temperate climate, with good access to local infrastructure, water, labour, and grid power. An average operation would be somewhere in between the two. Its just a gut feel.

Results

The following charts describe how it works, using randomly generated dummy assay data in this example.
In the Average cost scenario (left chart) the points are equally scattered both above and below the Likely Economic line. As one moves to a high-cost situation (middle chart) the curve moves upwards and more drill intervals now fall below the economic line.
This would give me an unfavorable impression of the project. The third graph is the Low-Cost scenario and one can see that more assays are now above the line. Hence the same project located in a different region would yield a different economic impression.
The economic boundaries (dashed lines) presented in the plots are based on my personal experience and biases. Other people may have different criteria to define what they would view as economic and uneconomic intervals.

Conclusion

There is not much that a layperson person can do with the multitude of exploration data provided in corporate news releases. However, by aggregating the data one can get a sense of where a gold project positions itself economically. The more data points available, the more that one can gather from the plot.
One should prepare separate plots for shallow and deep mineralization or for different zones and deposits on a property rather than aggregate everything together.
It may be possible to undertake a similar analysis with different commodities if one can summarize the assays into a single equivalent value or NSR dollar value. Unfortunately, exploration news releases don’t often include the poly-metallic interval equivalent grade or NSR value. Calculating these manually would add an extra step in the process, however it can be done.
If you want to try out the concept, I have posted the online spreadsheet to my website at the link Drill Intercept Potential where you can input Au exploration data of interest. Unfortunately, you cannot save your input data so it’s a one time event.   Anyone can do this – its not rocket science.
Let me know your thoughts, suggestions, or other ways to play with news release data.
If your project contains metals other than gold, then the rock (or ore) value will be based on the revenue from a combination of metals.   How to approach this in discussed in another blog post titled Ore Value Calculator – What’s My Ore Worth?

Great Bear Resources Example

Interesting the Great Bear Resources website allows one to download a data file with all their exploration intervals.  I have not seen another company provide this level of transparency.   I download their data file of over 1300 intervals and sub-divided them into major intervals and sub-intervals (more ore less).   The two plots below show the outcome.
The graph on the left is the sub-intervals showing that many points are above the “economic” line.  There are numerous data points along the top axis, indicating many sub-intervals at >10 g/t at widths ranging from 1 to 15 metres.  The graph on the right shows the major intervals.  While there are still many along the top axis, there are now more along the 40m width but at grades ranging from 1 g.t to 6 g/t.
One would surmise from these plots that overall there are many intervals above the line in the economic zone, showing the potential of the project.  It also shows that GBR have encountered many intervals likely sub-economic, but that’s the exploration game.

Great Bear Resources data

Examining polymetallic drill results in a similar manner isn’t as simple as this.   The mutiple metals of interest make the calaculations a bit more complex.   Another blog post discusses the approach I use for polymetallic, at this this link Polymetallic Drill Results – Interesting or Not?
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A Mining Career or a Travel Club

There have been some LinkedIn discussions about why the mining industry needs to attract more young people.  One of the selling points often mentioned is how mining gives a person the opportunity to experience the world.
Based on my own career, mining has definitely provided me with a chance to travel the world.  It will also help anyone overcome their fear of travel.   One will also learn that both international and domestic travel can be as equally rewarding.  There is nothing wrong with learning more about your own country.
The main purpose for my mining travel was due to either being a QP on a 43-101 study or visiting a site as a member of a due diligence team.   Other reasons have been to provide engineering support at a mine site or to meet with management teams for risk or strategy planning sessions.
Over the last year I haven’t traveled as much as in the past.  One reason is that not every QP working on a 43-101 report has to make a site visit. Fortunately, even when one doesn’t make a site visit, one still learns something about the local politics, legal system, infrastructure, and socio-economic situation in that country.
The map below shows places where I have been in my travels.  It also shows the locations of studies I was involved it. Mining really is a global business.   My map isn’t as cluttered as that of some geologists I know.  Exploration and resource geologists will visit many more destinations that an engineer will. After all, every project needs exploration drilling and a resource estimate, but not all projects advance to the engineering stage.

For those thinking of getting into mining, here is my list of pros and cons based on my own travel experience. Not everything is great about travel but some aspects of it can be fantastic.

What’s Good

  • I had the opportunity to visit many places for which there is a zero probability that I would have ever gone as a tourist.
  • Typically long duration long distance flights are in business class. You get lounge access and the perks associated with executive travel.   Less onerous short flights might be economy only, so be aware of your company policy.
  • All travel expenses, hotels, taxis, meals, etc. are paid for.  Just don’t get too exorbitant when wining and dining.  That’s the job of the senior person you are travelling with.
  • Upon arrival, often there will be a company representative to meet you at the airport.  They speak the local language and will take you where you need to go.  This saves you scrambling around an airport looking for a safe taxi to use.
  • You will get to meet local employees, go to dinner with them, travel around their country, and chat in the evenings. It’s a great way to learn about the people in the country you are visiting.
  • You will get to meet other technical people from around the world.  They might be expats working at a mine site or simply part of a multidisciplinary engineering team on the same visit.
  • You will be whisked away from tourist traps and thus have an opportunity to see the real countryside.
  • You will hit the ground running, get to visit mine sites, see some real live rocks, drill core, pit walls, equipment at work, and things happening.  You won’t get to see that while sitting in your downtown office.

What’s not so good

  • Unfortunately business trips are mostly of a very short duration since you’re not going there as a tourist.  You’re being paid for your time and expertise.

  • Mining trips are usually not to majors centers, so once arriving in the country you really haven’t arrived yet.  There might be more air flights or long pickup truck rides to get to the final destination. There can be a lot of waiting and the days can be long (and frustrating).   I remember on trip in northern Russia where four of us with luggage were jammed into a Volkswagen Rabbit in a snowstorm. That two hour trip took five hours, but we were just happy to make it back to the hotel.
  • Sometimes your accommodations will be less than stellar, i.e. one star hotels or tents.  So you’ll need to learn how to appreciate the charm of those places and not complain that it isn’t the Four Seasons Hotel.
  • Some travel locations can be potentially unsafe and require travelling security. That can lead to a bit of uneasiness.  I recall a trip to northern Mexico where we had two armed guards travelling with us.  I’m not sure if they were really needed and it was strangely more calming without them once they left.
  • Long east-west trips can leave you jet lagged and dog-tired. However the expectation is that at 7 am next morning you’re ready for breakfast and then head straight into the office.  You’re being paid to get to work, not to sleep.
  • The site visits will be focused on collecting or reviewing data and then immediately travelling back home to write your report.  Sightseeing opportunities can be limited other than what you will see during the course of your work. Sometimes you’ll get back home and think that you never really saw the place.

Conclusion

Business travel has always been one of the best parts of my mining career.   I can remember the details about a lot of the travel that I did.   Unfortunately the project details themselves will blur with those of other projects.
When I do travel now, it’s a nice change if just one flight gets you to your final destination.
During this Covid period, international travel is greatly restricted.  It will be interesting to see how soon things can return to normal, if they ever do.   To miss out on the travel aspect of a mining career would be a shame, unless the only travel you want to experience is sitting on public transit for a few hours each day.
By the way, my all time favorite place for a mining trip is…..Argentina.  It’s a long way from Toronto, but well worth it.

 

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43-101 Reports – What Sections Are Missing?

Recently as part of a due diligence I was reviewing a couple of 43-101 technical reports and something jumped out at me. There were pages and pages of statistical plots. The plots included QA/QC and check assay diagrams, variograms, box plots, swath plots, and contact plots. There was no lack of statistical information. However, as a mining engineer, there was something missing that was of interest to me. Good geological sections were missing.
Its seems that most technical reports focus heavily on describing the mathematical aspects of the resource, but spend less time describing the physical aspects of the geology and the mineability.

Who is the audience

It’s always open to debate who these 43-101 technical reports are intended for. Generally we can assume correctly that they are not being written mainly for geologists. However if they are intended for a wider audience of future investors, shareholders, engineers, and C-suite management, then (in my view) greater focus needs to be put on the physical orebody description.
Understanding the nature of the orebody brings greater understanding of the entire project.

Everyone likes geology

Whenever I listen to investor conference calls, many of the analyst’s questions relate to the resource and the mining operation. Essentially the participants want to know if this will be an “easy” mine or a “hard” mine.
One simple way to explain this is with good geological sections. They help everyone understand any potential issues; i.e. a picture is worth a thousand words. Good cross-sections will describe the following aspects.
  • The complexity (or simplicity) of the ore zones,
  • The width of the ore zones,
  • The vertical extent of geological information,
  • The drill spacing and drilling density,
  • The spatial distribution of assay information,
  • The grade distribution laterally and vertically,
  • The waste distribution throughout the mine,
  • The mining block size in relation of the ore zone dimensions
One can learn a lot just by looking at well presented cross-sections.  The nice thing is that they are generally understood by non-technical people.

Suggestions

I would like to suggest that every technical report includes more focus on the operational aspects of the orebody.
My recommendation is that the following information becomes standard in all technical reports.
  1. At least three to five cross sections through the deposit. Don’t just present a best case typical cross-section.
  2. At least one or two longitudinal sections.
  3. At least three level or bench plans, showing the drill hole pierce points.
Each cross section/bench plan should consist of two parts.
Part 1 shows the drill holes with color coded grade intercepts, ore zone wireframes, and lithology or rock types.
Part 2 should be a block model cross section showing the wireframes, drill holes, and color coded block model grades using the ore/waste cutoff grade as one of the clearly defined grade bins.
It doesn’t really matter if the cross- sections are included in Section 14 or Section 16 of the Technical Report. However if they are included in Section 16 then one should overlay the pit design and/or underground stope shapes onto the sections.
I also recommend NOT incorporating these cross-sections in the appendices since they are too important to be hidden away. They should be described in the main report itself.

Conclusion

Improving the quality of information presented to investors is one key way of maintaining trust with investors. Accordingly we should look to improve the description of the mineable ore body for everyone. In many cases it is the key to the entire project.
I am not suggesting that one needs to remove the statistical plots since they do have their purpose and audience. I am simply suggesting that we should not forget about everyone else try to figured out the viability of the project.
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For those interested in reading other mining blogs, check out the Feedspot website at the link below. They have over 50 blog sites you check out. https://blog.feedspot.com/mining_blogs/
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Google Earth – Share Your Project in 3D

Google Earth is a great tool and it’s free for everyone to use. No doubt that many of us in the mining industry already use it regularly.
Previously I had written an article about how Google Earth can be used to give your entire engineering team a virtual site visit. It’s cheaper than flying everyone to site. That blog is available at this link “Google Earth – Keep it On Hand”.

What else can Google Earth do for me?

The Investor Relations (IR) department in a mining company can also take advantage of Google Earth’s capabilities. Typically the IR team are responsible for creating a myriad of PowerPoint investor presentations. Their slideshows will include graphics highlighting the project location, showing exploration drilling and planned site facilities for advanced projects. This is where Google Earth can be used to create a more interactive experience for investors.

Google Earth with 3D Buildings

Rather than relying only on PowerPoint, the technical team can create drillhole maps, 3D infrastructure layouts, open pit plans, 3D tailings dams, and import them into Google Earth.
By creating a KMZ file, one can share this information with investors, analysts, and stakeholders. This will provide an interactive opportunity to view the information themselves.
Viewers could fly around the site, zoom in and out as needed, examine things in 3D, and even measure distances. Viewers can even save the project in Google Earth and return back whenever curiosity dictates.
I have been a part of engineering teams where Google Earth has been used to share layout information. However I have not yet seen such information offered as a downloadable KMZ file to external parties. If you know of any companies that are currently doing this, please let me know (kjkltd@rogers.com) and I will share their link here.

There also is VRIFY

VRIFY is a new cloud based platform that provides 3D viewing capability. It provides a map based graphic tool to IR departments for sharing project information. VRIFY can also enhance collaboration among engineering teams by enabling a group to view a virtual project and sketch on the image in real time.

VRIFY desktop screenshot

VRIFY also allows more detailed information to be displayed in the form of hotspots within a project. Click on them to get more information on that topic (see image to the right).
Although I have only been given a demo of VRIFY, it appears to be a nice package that provides more functionality than Google Earth. Unfortunately VRIFY is not free for a company to use. The minimum subscription cost is about $10,000 (plus extras).
In June 2019 VRIFY made a deal with Kirkland Lake Gold whereby interested property vendors can submit their project to Kirkland Lake management for their review.
Here is the link (https://vrify.com/dealroom). In the proposed approach, the project information is submitted using the VRIFY platform. Essentially some of the same information presented in a PowerPoint is now provided in a more interactive fashion. Participating companies must first enter into a client service agreement with VRIFY. We will see how this idea works, since it does add a cost and new complexity for the property vendor.
There is another cloud based service called Reality Check, which offers virtual reality site visits.

Conclusion

The bottom line is that the trend in the mining industry is towards more open data sharing whether you’re connecting with the public or within your own engineering team. New and old cloud based platform tools can be used to do this. It just depends on your budget.
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Is Insitu Leaching the “Green Mining” Future

It is no surprise to anyone that permitting new open pit mines in today’s environment is getting more difficult and even impossible in some areas.   Underground mines also have their challenges, permitting as well as requiring relatively high grades to be economic.
So where might our future metal supplies come from?  What are the options?

Insitu leaching may be the answer

I recently came across an insitu leaching website, called BIOMore.  This was an initiative sponsored by the EU that looked at insitu leaching technology for metal recovery.    Environmental issues associated with mining in Europe, particularly open pit mining, raised concerns about how ore bodies in the EU might be developed in the future.
Insitu leaching technology was viewed as playing an important role.  This is due to its minimal surface disturbance, ability to operate at great depth, and its potential in urban and developed locations.  Sounds like a nice solution to have on hand.
The EU-funded BIOMOre research project was completed in 2018.  It was designed to develop a new technological framework for the insitu recovering of metals from deep deposits.  The process would rely on controlled stimulation of pre-existing fractures in combination with insitu bio-leaching.  The study mainly focused on the application of existing technologies.

Fracing will be an issue

Insitu leaching essentially relies on exposing mineralized surfaces to leach solutions.  This may require hydro-fracturing (fracing) to enhance insitu bio-leaching using bacteria and acid.   Fracing is currently banned in some European countries so this is going to be a potential issue.  From a leaching perspective, the trade-off would be between no fracing, reduced cost & lower metal recovery against higher cost & higher metal recovery with fracing.
If insitu leaching technology development is successful, it could help exploit European base metals from porphyry deposits (Cu, Au, Mo, Cu, REE, PGE, Re, Pb, Cu, Pt, Au) and other gold and uranium deposits.   Insitu leaching would avoid building a mine, mine infrastructure, and it generates almost no tailings nor waste dumps.  Leaching is expected to be cheaper than traditional mining and more acceptable to the public. Insitu leaching is being touted as “Green Mining”

What did they conclude

This study deliverables included comprehensive documentation, an economic evaluation, and risk analysis of a potential insitu bio-leaching operation.  The basis was a theoretical deposit, looking at different well field set-ups.
The study concluded that accessing potential deposits at depths of around 1000 m is economically feasible only if curved wells are used.  The most relevant operational parameters are sufficient permeability in the ore zone and an adequate contact surface between the ore and leaching solution.   The depth of the deposit is indirectly relevant, but more importantly the well installation cost per volume of deposit is critical.  Hence curved wells are optimal.
One interesting suggestion was combining an insitu leach operation with geothermal energy recovery.  This might result in additional project revenue stream with only a marginal cost increase.
It was suggested that insitu leach operations might be attractive in former mining regions where high grade deposits have been mined out yet nearby low grade deposits are well defined. Social license for insitu leaching may also be more accepting in these areas.
If you are interested in learning more about insitu leaching technology and the chemistry aspect, the BIOMore study deliverables are available for downloading at this site.
In the past, mining engineers like myself were told to learn the basics of crushing, grinding, and flotation to become more well rounded.  I may suggest that future mining engineers may need to learn the basics of directional drilling, hydro-fracing, and chemistry.  Sounds like petroleum engineering.
Update: The University of Western Australia is also looking at electric fields to extract metals from hard rock ore, the sample principle as electro-plating.  Check out more information at this link “No more digging – a new environmentally friendly way of mining“.

Some aspects are still uncertain

In practical terms, some things are still not clear to me. For example are how much effort and diligence must go into properly characterizing the permeability of a rock mass.  As well, how complex a task is it to metallurgically characterize the deposit spatially with regards to it being amenable to insitu leaching.  Not all ore types will behave the same and be amenable to leaching.
I am also curious about the ability to finance such projects, given the caution associated with any novel technology.  Many financiers prefer projects that rely on proven and conventional operating methods.
Notwithstanding those concerns, likely insitu leaching technology will continue to advance and show even more promise, and eventually gain greater acceptance.
While some innovators are looking at new ways to drill, blast, and move rock, the real innovators are looking at ways to recover metals without moving any rock at all.
For those interested, Excelsior Mining is looking to open a copper oxide insitu leaching operation in Arizona.  Here is video of how their technology will work.
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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AI versus the Geologists

We likely have all seen recent articles about how Artificial Intelligence (AI) is going to change the mining industry.   I have been wondering if AI is a real solution or just a great buzzword.   My original skepticism has diminished somewhat and let me explain why.
At a booth at the 2019 PDAC I had a chance to speak with a publicly traded company called Albert Mining (referencing Albert Einstein’s intelligence).  They are providing exploration consulting services by applying a form of AI and have been doing so for many years.  The company has been around since 2005 but were not using the term AI to describe their methods.
These days the term “AI” has become very trendy.  Currently IBM Canada and Goldcorp are using Watson and AI to further their exploration efforts on the Red Lake property. GoldSpot Discoveries is another recent player in the mining AI field.  It appears Goldspot offers something similar to Albert Mining but they extend their platform to include picking projects, picking teams, and picking investments. That’s a lot of analysis to undertake.  Albert Mining is focused solely on mineral exploration.

Here is what I learned

Albert Mining’s system, called CARDS (Computer Aided Resource Detection System) uses pattern recognition and multi-variate analysis to examine a mineral property to look for targets.     The system requires that the property has some known mineralization hits and assay samples.  These are used to “teach” the software.   Both positive hits and negative hits are valuable in this teaching step.
The exploration property is sub-divided into cells and data are assigned to each cell.  These data attributes could be derived from geophysics, geochemistry, topography, soil samples, indicator minerals, assayed samples, geological maps, etc.  I was told that a cell could contain over 700 different data attributes.
The algorithm then examines the cell data to teach itself which attributes correlate to known mineralization and which attributes correlate with barren areas. It essentially determines a geological “signature” for each mineralization type.    There could be millions of data points and combinations of attributes.  Correlation patterns may be invisible to the naked eye, but not to the computer algorithm.
Once the geological signatures are determined, the remainder of the property is examined to look for similar signature hits.  Geological biases are eliminated since it is all data driven.   The newly defined exploration targets are given a ranking score based on the extent of correlation.
Some things to note are that the system works best for shallow deposits, unless one has some deep penetrating geophysical surveys.  The system works best if there is fairly uniform data coverage across the entire property.  The property should also have generally similar geological conditions and as mentioned before, the property needs to have some mineralized assay information.
This exploration approach reminds me somewhat of the book Moneyball.  This book is about the Oakland A’s baseball team where unconventional statistics were used to rank players in order to find hidden gems.

Are geologists becoming obsolete?

I was told that many in the geological community tend to discount the AI approach.  Either they don’t think it will work or they are fearing for their jobs.  Personally I don’t understand these fears nor can I really see how geologists can ever be eliminated.  Someone still has to collect and prepare the data as well as ultimately make the final decision on the proposed targets.   I don’t see the downside in using AI as another tool in the geologist’s toolbox.
Albert Mining’s stock price has recently gained some traction (note: I am not promoting them)  because junior mining news releases are starting to mention their name more often (Spruce Ridge Resources and Falco Resources are some examples).
Probably years ago if a mining company said their drill targets were generated by an algorithm, they might have gotten strange looks.   Today if a mining company says their drill targets were generated by AI, it gives them a cutting edge persona.  Times have changed.

In conclusion

I suggest we all take a closer looks at the AI technology to better understand what it does.
P.S. I  might also suggest that Albert Mining consider revising their company name to incorporate the term “AI” to stay on trend. (Update: In October 2019, Albert Mining changed their name to Windfall Geotek; I’m not sure it better explains what they do).
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The Mining Bank or eBay for Mining Properties

mining properties
I recently attended the Money Show here in Toronto to learn a bit more about personal finanace, investing strategies, and to check out  the latest stock analysis software.
There was also a trade show, but only one mining company booth was present.  This definitely wasn’t the PDAC.  Interestingly there were about five marijuana company booths, so that is where the promotion is today.
The lone mining company was Globex Mining, here is their website.  They referred to themselves as a “mining bank”, so that was something that peaked my interest.

Mining bank

Speaking with their president, Jack Stoch, he gave me an overview on their business model.  As I understood it, GLOBEX’s model is to acquire a portfolio of mineral properties.  They would try to enhance their value by undertaking some limited geological work.  Finally they would option, JV, or sell the property while retaining an NSR royalty.
Mr. Stoch told me that Globex currently has over 140 land packages in their inventory.  Their properties will be at different stages.  Some have resource estimates, others only mineralized drill intersections, mineral showings, untested geophysical targets, or combinations of these.
They are focusing their acquisitions on lower risk jurisdictions like Quebec, Ontario, Nova Scotia, New Brunswick, Tennessee, Nevada, Washington, and Germany.  They try to acquire historical mines that have old shafts, following the adage the best place to find a new mine is next to an old mine.   They also have some industrial mineral properties.

 

Globex’s only NSR revenue property right now is a zinc project in Tennessee that can generate a seven-figure royalty each year, when that operation is up and running.  Unfortunately for Globex the zinc operation has not been in consistent operation the last few years.

Its a good concept

I like the concept that Globex are promoting.  I like the idea of having a one-stop shop that acquires and options out exploration properties to mining companies looking for new projects.
I also like the idea of trying to consolidate land packages in an area,  minimizing the patchwork of multiple ownership claims that can hinder advanced development.
Globex hope that by putting time and effort into a bunch of properties a few of them will pay off.  If they can generate sufficient NSR revenues, the company may get to the self-sustaining stage.

Its not a new idea

The idea of companies involving themselves in a portfolio of early stage prospects isn’t new.  This has been being done by EMX Royalty Corp (formerly Eurasian Minerals) for properties around the globe.    Abitibi Royalties is also doing something vaguely similar, whereby they would help fund prospectors in exchange for a long term royalty on a property. There are likely others.
There is a high risk to being successful but the cost of entry is relatively low.
It will be interesting to watch Globex over the longer term to see how many properties they can acquire and how many of these will pay off. Spending a bit of money on mapping and exploration on a property may benefit them by increasing value in the eyes of potential partners.
Statistically, mineral exploration is a high risk game but by limiting expenditures and diversifying the portfolio, some of that risk can be mitigated.
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