Articles tagged with: Mine Engineering

4 Mining Study Types (Concept to Feasibility)

Date: April 29, 2015 Author: Ken Kuchling Comments: 2 Replies
Over my career I have been involved in various types of mine studies, ranging from desktop conceptual to definitive feasibility.    Each type of study has a different purpose and therefore requires a different level of input and effort, and can have hugely different costs.
I have sat in on a few junior mining management discussions regarding whether they should be doing a PEA or a Pre-Feasibility Study, or a Feasibility instead of a Pre-Feasibility Study.    Everyone had their opinion on how to proceed based on their own reasoning.   Ultimately there is no absolute correct answer but there likely is one path that is better than the others.  It depends on the short term and long term objectives of the company, the quality and quantity of data on hand, and the funding available.

4 types of mining studies

In general there are 4 basic levels of study, which are listed below.  In this blog I am simply providing an overview of them.  On the web there are detailed comparison tables, but anyone can contact me at KJKLTD@rogers.com for an a full copy of my table (an excerpt is shown below).

Four Studies Table

1. Desktop or Conceptual Mining Study
This would likely be an in-house study, non-43-101 compliant, and simply used to test the potential economics of the project.  It lets management know where the project may go (see a previous blog at the link “Early Stage “What-if” Economic Analysis – How Useful Is It?”.    I always recommend doing a desktop study, and preparing some type of small internal document to summarize it.  It doesn’t take much time and is not made public so the inputs can be high level or simply guesses.  This type of early stage study helps to frame the project for management and lets one test different scenarios.
2. Preliminary Economic Assessment (“PEA”)
The PEA (or scoping study) can be 43-101 compliant and present the first snapshot of the project scope, size, and potential economics to investors.  Generally the resource may still be uncertain (inferred classification), capital and operating costs are approximate (+/- 40%) since not all the operational or environmental issues are known at this time.   Avoid promoting the PEA as an “almost” feasibility level study.

Don’t Announce a PEA Until You Know the Outcome

I recommend not announcing the start of a PEA until you are confident in what the outcome of that PEA will be.   A reasonable desktop study done beforehand will let a company know if the economics for the PEA will be favorable.  I have seen situations where companies have announced the start of a PEA and then during the course of the study, things not working out economically as well as envisioned.  The economics were poorer than hoped and so a lot of re-scoping of the project was required.  The PEA was delayed, and shareholders & analysts negative suspicions were raised in the meantime.
The PEA can be used to evaluate different development scenarios for the project (i.e. open pit, underground, small capacity, large capacity, heap leach, CIL, etc.).  However the accuracy of the PEA is limited and therefore I suggest that the PEA scenario analysis only be used to discard obvious sub-optimal cases.  Scenarios that are economically within a +/-30% range of each other many be too similar to discard at this PEA stage.  This is where the PFS comes into play.
3. Pre-Feasibility Study (“PFS”)
The PFS will be developed using only measured and indicated resources (no inferred resource used) so the available ore tonnage may decrease from a previous PEA study.  The PFS costing accuracy will be greater than a PEA.  Therefore the PFS is the proper time to evaluate the remaining mine development scenarios.  Make a decision on the single path forward going into the Feasibility study.

Use the PFS to determine the FS case

More data will be required for the FS, possibly a comprehensive infill drilling program to upgrade more of the the resource classification from inferred to indicated.  Many companies, especially those with smaller projects might skip the PFS stage  entirely and move directly to Feasibility.  I don’t disagree with this approach if the project is fairly simple and had a well defined scope at the PEA stage.
4. Feasibility Study (“FS”)
The Feasibility Study is the final stage study prior to making a production decision.  The feasibility study should preferably be done on a single project scope.  Try to avoid more scenario option analysis at this stage.
Smaller companies should be careful when entering the FS stage.  Once the FS is complete, shareholders will be expecting a production decision.  If the company only intends to sell the project with no construction intention, they have now hit a wall.  What to do next?

Sometimes management feel that a FS may help sell the  project.

I don’t feel that a FS is needed to attract buyers and sell a project.  Many potential buyers will do their own in-house due diligence, and possibly some alternate design and economic studies.   Likely information from a PFS would be sufficient to give them what they need.  A well advanced Environmental-Socio Impact Assessment may provide more comfort than a completed Feasibility Study would.

Conclusion

executive meetingMy final recommendation is that there is no right answer as to what study is required at any point in time.  Different paths can be followed but consideration must be given to future plans for the company after the study is completed.   Also consider what is the best use of shareholder money?
Company management may see pressure from retail shareholders, major shareholders, financial analysts, and the board of directors to “do a study”.  Management must decide which mining study path is in the best longer term interests of the company.  Maybe no study is warranted.
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Early Stage “What-if” Mine Economic Analysis – Its Valuable

Date: April 27, 2015 Author: Ken Kuchling Comments: Leave a reply
Mining study economics
Over my career I have worked with large and small mining companies and seen how they studied projects and potential acquisitions.
Large mining companies have their in-house evaluation teams that will jump on a potential opportunity that comes around and start examining it quickly.  These evaluation teams may consist of a specialized head office group supported by people temporarily pulled in from their mining operations.
They are experienced at what they do and can provide management with solid advice even if working with only limited data.  This help management decide very early on whether to further pursue the opportunity or walk away immediately.
Early stage economics are normally part of this evaluation approach.   Although they are not correct all of the time, more than often they save their company from wasting money on projects unlikely to fly.
However if you are a small mining company, what are your options?
You don’t have an in-house technical team sitting around ready to go.  Management still needs to know if this project has a chance.  If the project is early stage, sometimes management thinks its fine to take a gamble, acquire the project, and then put money into the ground rather than spending on early studies.

It is possible to do both

Management and the exploration team usually have a vision for their projects, even those projects with only limited information.   Each person may have a different opinion on the potential size and scope of what may ultimately exist there.  However the question is whether any of those visions have sufficient accuracy to warrant spending more shareholder money on the project.
Some of the junior mining management teams that I have worked with have found it beneficial early on to have a basic internal cashflow model on hand.   If properly constructed, these are simple to tweak to examine “what-if’s” scenarios.  Input the potential deposit size and mine life, potential head grades, expected metallurgy, and typical costs to see what the economic outcome is.  Does this project have a chance and, if not, what tonnage, head grade, recovery, or metal price is required to make it work?   The simple cashflow model can tell you all of this.

Early stage modelling adds value

The tangible benefits to very early financial modelling are:
  • It helps management to conceptualize and understand their project.  If done honestly, it will reveal both the opportunities and threats to success.
  • It helps management to understand what technical parameters will be most important for them to resolve and what technical factors can be viewed as secondary. This helps guide the on-going exploration and data collection efforts.
  • Periodically refreshing the economic model with new information will reveal if the economic trends are getting better or worse.

Its not 43-101 compliant

I must caution that this type of early stage economic analysis is not 43-101 compliant and hence can not be shared externally, no matter how much one might wish to.
Another caution is that in some cases these early stage un-engineered projections become “cast in stone”, with management treating them as if they are accurate estimates.  Then suddenly all subsequent advanced studies must somehow agree with the original cost guesses, thereby placing unreasonable expectations on the project and the people doing the work.
The early stage economic models can consist of simple one-dimensional tables using life-of-mine tonnages or two-dimensional tables showing assumed annual production by year.  Building simple cashflow models may take only 2-3 days of effort.  That is not an onerous exercise compared to the overall benefit they can provide.
The bottom line is that it is useful to take a few days to develop a simple cashflow model.  “Simple” also means that management themselves can tweak the models and don’t need to be modeling expert on hand at all times.  “Simple” means the model should be well.  In another block post I discuss why to avoid demonstrating one’s Excel skills in building models. Read more on that at this link  Financial Spreadsheet Modelling – Think of Others.
Most companies have a CFO that can easily undertake this type  of modelling, with the help of some technical input.  Be careful though, often CFO’s take the simple cashflow model to an unwarranted level of complexity.
The simplest of all models is the one-dimensional approach.  To learn more about the concept behind a simple 1D financial models, read the blog post “Project Economics – Simple 1D Model” .
The entire blog post library can be found at this LINK with topics ranging from geotechnical, financial modelling, and junior mining investing.
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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Mine Financial Modelling – Please Think of Others

Author: Ken Kuchling Comments: Leave a reply
Mining Cashflow modeling
In my role as a mining consultant I am often required to review spreadsheet cost models or cashflow models built by others.  Some of these spreadsheets can be monsters, incorporating multiple worksheets, cross-linking between worksheet cells, and having hard wired numbers inside cell formulas.
Some of the models I have reviewed will build the entire operating cost (mining, processing, G&A) in one grand file.  They will build in the capital cost too and finally provide the economic model… all in one spreadsheet!
This makes the model very complex to audit and it becomes difficult to follow the logic.  Sometimes gut feel says there are formula or linkage errors in there somewhere but you just can’t find them.  In these types of models my focus is on trying to figure out the formula logic than actually looking at the validity of the inputs and output.
It seems that only the model developer can really work with these spreadsheets and the rest of us can just hope that they have created everything correctly.

Don’t be too clever

Over the years, I have learned that there is an art to creating a clear, concise, and auditable cashflow model (or cost model). Once in awhile you come across one that is well crafted and isn’t an example of someone trying to show how clever they are.
In building the spreadsheet models I have learned to not do too much within the same model, especially if different people are involved in its foundation.  My other suggestions are:
  • Color coded input cells differently than formula cells.
  • Carry over values rather than linking to other worksheets.
  • Highlight cells that are carried over from other worksheets.
  • Never hardwire numbers into a formula.
  • Use named cells for key fixed inputs (like exchange rate, fuel price, etc.)
  • Use conditional formatting when possible to help identify errors.
  • Put your “Totals” column along the left side of the worksheet so you can add columns if needed.
I won’t go into detail on good spreadsheet practices, but you can check out the instructional presentations prepared by Peter Card at Economic Evaluations (http://economicevaluation.com.au).
He has some excellent practical recommendations that all financial modellers should consider.  It doesn’t take long to review his online courses and it’s worth your time to do it.  His recommendations can generally apply to any Excel modelling exercise, whether its costing, scheduling, or economic analysis.

Try to help by building in clarity.

The bottom line is that you must build your spreadsheet models compatible with the way you think.  However not everyone thinks the same way so try to keep all aspects easily identifiable and traceable.  Be consistent in the model format from worksheet to worksheet. Be consistent in methodologies on all worksheets and with all your models.   Your client, colleagues, and reviewers will thank you.
Another aspect of due diligences that can be taxing is figuring out the structure of a data room.   Simply throwing all of your files into an unstructured data room helps no one.   I have written another blog about this annoyance at “Mining Due Diligence Data Rooms – Help!“

 

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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