Articles tagged with: Mine Engineering

Work Breakdown Structures – Don’t Forget About The WBS

Date: May 22, 2015 Author: Ken Kuchling Comments: Leave a reply
mining project WBS
Normally at the start of a mining study, the team members receive a matrix of responsibilities.  This table shows which people (or groups) are responsible for different aspects of the study, i.e. who is responsible for geology, for mine design, for process design, infrastructure, etc.  This is great tool and a necessity in making sure that everyone knows what they are supposed to do.
Next we generate a project schedule based on some work plan.  In realty this isn’t the correct sequence.

Sometimes the WBS is forgotten

What often gets forgotten in early stage studies is providing the team members a Work Breakdown Structure (“WBS”).   I consider the WBS an equally important component as the responsibility matrix and both should always be provided.
The WBS is a hierarchical breakdown of the project into phases, deliverables, and work packages usually associated with cost estimation. It is a tree based structure, developed by starting with the final objective and then dividing that into manageable components based on size, duration, and responsibility.  Typically this is done for the capital cost estimate, breaking it down into individual cost areas and cost components.  A WBS can also be used for the operating cost estimate.
request for propoalsThe WBS can provide the following information to the team:
  • It assigns the costing responsibility to specific people or group so each know what must be delivered.
  • It provides a consistent format for developing and reporting the capital costs (and operating costs).
  • It helps ensure that no cost components get omitted and no costs get double counted.
  • It provides the cashflow modeler with a clean format to import the capital cost into the cashflow model.
  • The WBS should be developed before the project schedule, not after it.

Any study will benefit from a WBS

Typically a WBS is developed for pre-feasibility and feasibility mining studies but is often ignored at the PEA stage.  Some feel it is too detailed for that level of study.  I don’t feel this is the case.
The WBS is a communication tool to confirm responsibilities.  Thus even a simplified WBS is still useful at the PEA stage.
I have seen some instances where a WBS has been created but does not get wide distribution to the entire team.  The WBS should be provided to everyone and ideally a team session be held to walk through the WBS structure.
The idea is not make everyone a costing expert, but rather to ensure all understand how the project cost estimate will be structured.

Conclusion

The bottom line is that regardless of the level of study, a WBS should always be created.
Some will say the WBS is not required for early stage studies but I have found benefits in having one, at least for the capital cost estimate.   Obviously the level of detail in the WBS should be appropriate to the level of the study.
Once the WBS is in place, then go ahead and build your project schedule.
A competent Study Manager can easily create an initial WBS, thereby mitigating some headaches when the final study is being assembled.   You may even want a basis WBs at the proposal stage.
By the way, before awarding a study to anyone, try to have a prepared Request for Proposal beforehand.   I have written about the benefit of this document in a blog post titled “Request For Proposal (“RFP”) – Always Prepare One“
My entire blog post library can be found at this LINK with topics ranging from geotechnical, financial modelling, and junior mining investing.

 

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Potash Ore Grades – Check the Units

Date: May 20, 2015 Author: Ken Kuchling Comments: 3 Replies
KCl vs K2O
Having worked with the potash industry for many years, I have reviewed numerous geological reports for projects in Canada, Asia, Russia, and Africa.  One of the curious things that I have seen is the reporting of resource  grades in two different units; either as potassium oxide (K2O) or potassium chloride (KCl).

Is it K2O or KCl ?

Standard practice in the Saskatchewan industry is reporting ore grades using K2O units, with typical head grades in the range of 25% K2O.  Many of the international projects, but not all, have decided to use the KCl units. Therefore when comparing potash resource grades between deposits, one must be vigilant for the units used since there is a significant difference.
The conversion from K2O to KCl is based on the formula K2O = 0.6317 x KCl.   So a grade of 25% K20 is equal to 25/0.6317 = 39.6% KCl.  The KCl grade value is significantly higher.  The unit issue is relevant with low grade deposits, were an actual grade of 15% K2O may be reported as 23.7% KCl.  One might see the ore grade in KCl and assume it is comparable to Saskatchewan potash grades, when in reality they are quite different.

Concentration Ratio is the Key

When looking at different potash projects, particularly those involving underground mining, a key economic factor is the concentration ratio.  This ratio represents the tonnes of potash ore needed to produce a tonne of final saleable product.
Typically the final potash product has a grade of 60% K2O.  Therefore a potash ore with a grade of 25% K2O would have a concentration ratio of about 2.4:1 (60%/25%).  This means that 2.4 tonnes of potash must be processed to produce 1 tonne of product (ignoring the process recovery factor).   For a lower grade ore with a head grade of say 15% K2O, the concentration ratio is 4:1 (60%/15%).

potash mining

This gives a rough sense for the comparable operation size required to meet the same final product production levels.  This also gives a indication for the relative amounts of salt tailings requiring disposal.  Low grade ore can generate significant quantities of tailings, the disposal of which is becoming a larger permitting issue.
In the past gold grades have been reported as “oz/ton” or currently as “g/t”, but most geological reports today are consistent with “g/t”.  Sometimes US based gold projects may use “oz/ton” however the magnitude in reported grades are fairly obvious between grams and ounces.  That isn’t the case with potash grades.
The bottom line is that potash is one commodity that will use different units when reporting ore grades.  Investors and reviewers must be aware of which units are being used.
If you are into potash mining, I have written a couple of blog posts about my brief, but interesting, time working at a potash mine in Saskatchewan.   This was early in my career and I had roles that included mine engineer, chief mine engineer and production foreman.  Each of these roles gave me a different perspective about a mining operation. In this two part blog, I share some stories relating to the uniqueness of potash mining.   If interested, here is the link “Stories from 3000 Feet Down – Part 1“.

 

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Importance of a Study Manager – That’s the Key

Date: May 18, 2015 Author: Ken Kuchling Comments: 1 Reply
project manager
Over my career I have worked as an engineering team member on numerous projects and mining studies.  Some studies went better than others.  Unfortunately some dragged on, ran over budget, and ended up delivering a less than optimal product once all was said and done.
There are numerous factors that will influence the successful completion of a study.   They can be related to the quality of the technical team, the budget, the time window, and direction from the Owner.  However the key factor that I observed is the competency of the Study Manager (or Project Manager).

Study Managers must wear many hats

Study managers are responsible for being the main liaison with the Owner. They must herd a team of geologists and engineers in the same direction. They must ensure that technical quality and consistency is maintained by the entire group.  They are responsible for ensuring that budgets and timelines are being met.  The combination of all of these responsibilities can be an onerous mission, more so depending on the experience of the Owner’s team.
Every technical team has those members that will deliver quality within timelines consistently.  There are also team members that have difficulty meeting targets.  The Study Manager, early on, needs to figure out who fits into which category and then must be able to work with each.

Studies can quickly grind to a halt

An entire study can quickly grind to a halt simply because one key component becomes bogged down. A good Study Manager may occasionally ruffle some feathers but is always appreciated by the team knowing that everyone will be held to account.
The Study Manager also needs to understand the objectives of the Owner and ensure the team is working towards those objectives.
The Study Manager however must also be honest with the Owner, keeping him informed of the actual progress and warn if some target will not be met.
The Study Manager coordinates communication within the team and with the Owner.  Some managers are excellent at this while others fall into the trap of communicating on a “need-to-know” basis or “too late” basis.
Timely and thorough communication is important.  Don’t assume that one is hampering progress by involving the team in frequent communications. They serve a purpose.

Environmental Assessments need engineering input

Often the Environmental Impact Assessment is being conducted concurrently with an engineering study.  The level of internal and external communication now becomes even more critical due to the large number of new technical disciplines involved.
It is not uncommon for EIA’s to make regulatory commitments  that have not been signed off by the engineering side. The Study Manager should be aware when such commitments are being made because the engineering design needs to reflect them.

You should approve the Study Manager

When approving the consultant’s Study Manager, keep in mind that in some instances you may find that different managers within the same organization may have different internal authority.  For example, if technical people are needed on another project, some managers are able to keep their team together.  Other managers may lose team members to the other project if that manager has more internal authority.  Losing manpower doesn’t help a study progress,  so if possible try to get a sense for the authority that the Study Manager has within the organization.

Conclusion

The bottom line is that when a project Owner has received proposals for a study and is in the process of awarding that job, the most important consideration is who will be the Study Manager.  If possible meet or chat about how they will manage the study and what their experience is.  Check references if possible.
The voluminous proposals provided by consulting firms contain a lot of information like Gantt charts, organizational charts, cost estimates, team resumes, safety plan, and corporate project experience.  Focus on the Study Manager. Don’t assume they are simply an administrator scheduling meetings and issuing monthly reports. They are the key to success.
A good Study Manager can make a poor engineering team perform, while a poor Study Manager can bog down a great technical team.
One thing to be aware of is that with some firms, a Study Manager is not the same role as a Project Manager.  The SM may undertake more clerical duties, such as weekly or monthly reports, manhour tracking, distributing documents, and coordinating the logistics of the study rather than the technical aspects that a Project Manager may look after.
Another blog post discusses undertaking studies using multiple engineering teams and the pitfalls to watch out for.  That blog post is at “Multi-Company Mining Studies Can Work Well…or Not“.
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Directional Drilling Open Pit Dewatering Wells – Great Idea

Date: May 16, 2015 Author: Ken Kuchling Comments: 4 Replies
open pit dewatering
I read an interesting article in the Mining Magazine May 2015 edition called “Top 10 Technologies”.  One of the new technologies that jumped out at me is the capability to directionally drill open pit dewatering wells.   This is an oil field technology from Schlumberger Water Services that was now going to be applied to mining.
One of my past roles was as a mine engineer on the Diavik diamond mine team. Pit geotechnical and hydrogeology were under my domain during project design and permitting from 1997 to 2000.
The granitic rock mass was geotechnically very competent with a limited amount of jointing and fracturing.  The pits were going to be located within a lake bed.
It was anticipated that groundwater seepage coming from a partly permafrost pit wall could create a host of operational problems in winter. Most of the groundwater flows were predicted to be along a few major structures or along single open joints.
Generally these major structures were near vertical, which created a problem when trying to intercept them with vertically drilled depressurization wells.  Either you hit one or you didn’t.

The use of directional drilling of pumping wells is a great innovation

Directional drilling of dewatering wells gives the opportunity to angle a pumping well to an orientation that allows the well bore to cut across vertical structures rather than paralleling them.   In addition, one could drill pumping wells near the pit crest targeting towards the ultimate pit bottom.  This may help improve drainage near the operating benches as the pit deepens and could eliminate the need to install inpit pumping wells if water becomes a problem.
Some open pits have constructed underground drainage galleries around the pit circumference to help intercept deep groundwater seepage.  Possibly directionally drilling aligned parallel to the pit wall can replace such high cost drainage galleries.
The bottom line is that the directional drilling innovation makes a lot of sense and mine operators should take a look at it.  It might help improve their pit dewatering systems.
If anyone has experience with directionally drilled dewatering wells, please let us know.
The hydrogeology at Diavik was unique in that the ground consisted of both permafrost and unfrozen ground.  It was likely that unfrozen ground would eventually form permafrost over time once exposed to the cold winter climate.  To read more about the hydrogeology at Diavik, check out this link “Hydrogeology At Diavik – Its Complicated“.
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.   
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Request For Proposal (“RFP”) – Always Prepare One

Date: May 15, 2015 Author: Ken Kuchling Comments: Leave a reply
Mining request for proposal
When it comes to time to undertake any type of mining study, whether small or large, whether sole sourced or competitively bid, it is always a good idea to prepare a Request For Proposal (“RFP”) document.
I know that it can be an annoyance, but an RFP document is a lot better than a simply phone calling a consultant describing what you want.  Its also better than a cursory email outlining what you want. In many cases the RFP doesn’t need to be a complex document; however RFP’s are appreciated by everyone involved.   It provides the documentation that can help make things go smoothly.

The RFP doesn’t need to be complicated

executive meetingOwner’s Perspective: preparing an RFP gives the opportunity to collect the Owner’s team thoughts on the scope of study needed, on the deliverables required, and on the timing.   The RFP will outline this for the consultants and simultaneously help the owner’s team to get on the same page themselves.
The RFP is the opportunity for the owner to tell the consultants exactly what they are looking for in the mining study.  It also specifies what they want to see in the proposal to help them compare multiple proposals if needed.
Consultant’s perspective: receiving an RFP is great to them since having a detailed scope of work laid out means they don’t need to guess the scope when preparing their cost estimate.  It will be clear to the consultant what work is “in scope”.  If extra services are required in the future, then “out-of-scope” work can be defended.
An RFP also gives the consultant some reassurance that the Owner has put thought into exactly what they want them to do.

What to include in the RFP

The RFP sent to bidding consultants should contain (at a minimum) the items listed below. A sole sourced study can have a scaled back RFP document, but many of these key items should be maintained.
Much of this RFP information can be a single template document that will be modified if different scopes of work will be sent to different consultants (e.g. tailings design, pit geotechnical, groundwater, feasibility study, etc.).
  • Project Introduction (a high level overview of the project and the Owner).
  • Table of Responsibilities for the Study (if other consultants are being involved in different areas).
  • Scope of Work (for this Proposal), and highlight any specific exclusions from the scope.
  • Additional Requirements (update meetings, monthly reports, timesheets, documentation, etc.)
  • Schedule (the timing for the proposal, job award date, study kickoff, and completion date).
  • Instructions to the Bidder (e.g. what information should be provided in each proposal and in what format).
  • Other (the legal rights of the Owner, confidentiality statement, how proposals will be evaluated, etc.).

Specifying format makes it easier to compare proposals

If a company is competitively bidding the study, it can be easier to compare multiple proposals if certain parts are presented in the exact same format.  Usually different consulting firms have their own proposal format, which is fine, however certain sections of the proposal should be made easily comparable.
The RFP can request that each proposal should contain (at a minimum):
  • Confirmation of the scope of work based on the RFP, which may be more detailed than the RFP itself.
  • List of exclusions.
  • List of final deliverables.
  • Proposed Study Manager, resume and relevant study management experience.
  • Proposed team members, organizational structure by areas of responsibility, and resumes.
  • Cost estimate on a not-to-exceed basis for each area, subdivided by team member, hours and unit rates ,and possibly in a specific table format.
  • A fee table for the various job classifications that would be applied to out-of-scope additional man hours.
  • All indirect costs, administrative costs, indicating mark-ups (if any).
  • Miscellaneous disbursements (i.e., airfares, hotel, vehicles) and indicate if there are mark-ups.
  • Detailed study schedule to completion.
  • Payment schedule.
  • Specify if there are any potential conflicts of interest with other projects.

Conclusion

The bottom line is that an owner should always take the time to prepare some type of RFP for any mining study they want to undertake.  The owner should also request a consultant proposal based on that RFP, even if it is being sole sourced to just one consultant.
Depending on the size and nature of the study, one can use judgement on how detailed the RFP or consultant’s proposal must be, but one should always have the proper documentation in place beforehand.
A key part of any mining study is the project capital cost estimate.  In my view it is important that any RFP includes the requirement to develop a Work Breakdown Structure.  This has many uses, and is discussed further in the blog post “Work Breakdown Structures – Don’t Forget About The WBS“
My 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.  
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Mining Due Diligence Data Rooms – Help!

Date: May 13, 2015 Author: Ken Kuchling Comments: 3 Replies
Mining reviews
Many of us have heard the statement “Have a look in the data room, it’s all in there”. This can bring a cold sweat to even the most experienced engineer who undertaking a due diligence review.  How many of you can recall being given FTP access to a data room that is full of highly disorganized folders and sub-folders, files with cryptic names, different updates of the same file in different folders?

It’s like looking for a needle in a haystack.

It can be difficult to impossible to determine which files are important and relevant and which files have been simply dumped into the data room. There is nothing worse than spending a day reviewing an Excel financial model only to find out that it wasn’t the latest version and a different un-related folder had the correct version.
Data rooms are typically created for due diligence exercises, or during advanced an engineering stage. Regardless of the purpose, it is helpful for all involved  to have a document control person who understands what is in the data room, what is important, and what is non-essential.
Large projects often have an dedicated document control person to manage the data room.  However smaller companies in a due diligence phase may tend to use a team approach.  Everyone dumps all their electronic files into the data room, including email transcripts, using some type of sensible folder structure (hopefully).
It’s then up to the user to dig through the files to locate what they need.  This can be an onerous task, costing everyone money in wasted time.

Organization of the mining data room is key

Comprehensive searchable document management systems such as Ansarada, Aconex, SharePoint, and others are available.  They can be pricey and will require a team mindset to function, organize, and catalog the information.  However a properly implemented system can make it easier to search for files, keywords, and the latest versions of files. “Properly implemented” means that the entire team takes time when putting information in to ensure it is properly tagged meta-data.  Its is not uncommon for such systems to become repositories for hundreds or thousands of different files.
When using a cloud-based data room or FTP site, try to select one that allows bulk downloading of documents rather than only allowing one file download at a time.
Some data rooms, for security and tracking purposes, require users to be online in order to open a document, even documents downloaded onto your computer.  This makes it difficult to work when one doesn’t have internet access (like on an airplane).
Some data rooms limit the cut & pasting ability from the documents.  This can make it difficult to prepare your own summary  report if you want to include pasted images from the documents.

Conclusion

The bottom line is that management of a mining data room is critically important, although I don’t know if there is any single magic solution.
Small mining companies may have tight budgets and a limited management team so organizing data properly isn’t high on the priority list.   I suggest to anyone organizing a data room, please take the time to properly set up the folder structure, develop a single bibliography of what files are in there, and assign a person to be familiar with the general contents of the data room.
Unless its a legal case involving lawyers, don’t just dump in everything. Avoid unnecessary data files or “work in progress” files that are not actually required by anyone.

Read More on the Subject

Another aspect of data rooms that can help make a due diligence taxing is the way the spreadsheet models are built.  Models can either be made simple and user friendly, or can be complex showing how clever the model creator is.   You can read some thoughts on this at the following link “Mine Financial Modelling – Please Think of Others“.
For more discussion on the topic of mining due diligence, another blog post discusses the help that a technical checklist can deliver.  There are many aspects of a mining project, from legal, social, to technical and a checklist helps to avoid missing things.  You can read more about the checklist on this at “Mining Due Diligence Checklist“. You can even request a free copy of my Excel checklist if interested.

 

Note: If you would like to get notified when new blogs are posted, then sign up on the KJK mailing list on the website.  Follow us on Twitter at @KJKLtd for updates and insights.
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Junior Miners – Get Your Own Independent Consultant

Date: May 12, 2015 Author: Ken Kuchling Comments: 1 Reply
PEA consultants
Over the past few years I have worked in different consulting roles; as an independent consultant; as a member of a large consulting team; and as owner’s representative managing consultants.   I have learned that there is a role for both the independent consultant and larger consulting firms.  Read on for more in this self-serving article.

Independents have a role

A previous blog (“9. Large Consulting Firms or Small Firms – Any Difference?”) discusses where large and small consultants fit into the overall picture.   Large technical teams are required where there are broader scopes of work, significant effort levels, and where multiple skills sets are needed.
Independent consultants are a different thing.  They are best suited for assisting the Owner directly, either independently or as part of an overall corporate advisory team.  Non-technical junior mining management teams should always have access to in-house engineering capability for brainstorming or technical direction.
Even if some of the management are technically oriented, having independent thought is valuable. The question is whether the engineer should be a cheerleader or a true independent observer.
Independent consultants will differentiate themselves from large engineering firms in several ways.
  • They don’t bring a lot of extra personnel onto a job.  They focus only on what is needed and can draw in other expertise when needed.
  • They can provide unbiased advice.  Larger firm sometimes have business development conflicts. The independent consultant does not have the motivation to win a feasibility study or EPCM contract.
  • A company can develop a long term working relationship with an independent consultant.  Everyone gets familiar with each other’s objectives and goals.  Large engineering firms can be revolving doors with people moving on to other firms.
  • Independents can work efficiently at a pace of their own choosing.  This can result in lower costs and faster deliverables.  I know many independent consultants will work evenings and weekends to meet client targets.
  • Independents can provide long term stability since they won’t have any employee turnover.  Personally I was involved for over 15 years with a mining operating in Suriname.  The expat staff at the mine site experienced significant turnover.  This was partly due to them being promised personal development relocations.  I ended up being the only constant for the mine site.  I knew the history and why things were done they way they were.  I even had copies of old study reports they could no longer find in their files on site.  I knew what was done previously, thereby avoiding re-inventing the wheel each time there was a new technical manager was brought in.

Consultants and Stocks Options

A point of discussion is whether the independent consultants should receive stock option compensation.  I have worked under both situations.
Awarding stock options might eliminate the “independent” nature of the relationship and hence negated the ability to sign off as an independent QP.  In some circumstances, the company may not require the independent consultant to be a QP since they mainly fulfill an advisory role.
Does one want independent advice, from someone who may not be a significant shareholder or option holder?
One advantage of awarding stock options is that the consultant may become more beholden to the project.  They feel it is their project too, rather than simply acting as an adviser.  They may have a longer term interest in being involved with the project and the company.
Conversely the company may prefer the consultant doesn’t have any direct ownership so that their advice can be viewed as being unbiased. Having a contrarian view of corporate plans is a good thing.
I feel that awarding stock options is a good way to foster long term commitment from the consultant. It can be easier for them to walk away without any such inducement.

Conclusion

The bottom line is that independent consultants have a role to play and should be part of all owner’s teams, whether be on the Board or on an Advisory Panel.   The independent consultants can be selected based on their technical specialization (i.e. exploration, resource modelling, mining, metallurgy, environmental) and provide valuable part time guidance to the company.
The caveat is to ensure that the consultant is technically capable.  I have seen instances where certain members of the advisory panel gave poor advice.  perhaps they weren’t that technically capable but simply friends with some of the management.  Unfortunately other advisors would see these limitations, but not say anything out of professional courtesy.
Lastly, decide whether the engineer should be an honest advisor or a cheerleader.  Companies should want to hear the truth.  If a 3rd party due diligence teams comes in, they will be looking for flaws in the project.  It would be in a company’s self interest to know what those flaws are before the due diligence teams finds them.
One of the things an advisor can help do is decide the study path the company should take.  To learn more about the 4 mining study types, you can check out this blog post “4 Mining Study Types (Concept to Feasibility)“.
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Pit Wall Angles and Bench Widths – How Do They Relate?

Date: May 10, 2015 Author: Ken Kuchling Comments: 3 Replies
open pit slopes
An open pit wall will consist of a series of stacked benches.  Geotechnical engineers will normally provide the pit slope design criteria based on the inter-ramp angle (“IRA”) for various sectors around the pit.  The IRA represents the toe-to-toe slope angle, as shown in the diagram below.
The inter-ramp angle can be created in many ways, depending on the bench height (“BH”), bench face angle, and the catch bench or berm width.  Different combinations of these can be used to develop the same inter-ramp angle.

Pit wall schematic

Typically the bench face angle (“BFA”) will be dictated by the rock strength, the structural fabric, and whether controlled blasting is used (minimizing damage to the walls).   The BFA may vary around the pit or in different rock types, but it typically is in the range of 60° to 75°.
The catch bench (“CB”) or berm is used to catch spalling rock and prevent it from rolling down the pit wall,  creating a safety hazard.
A rule of thumb is that the catch bench width should be according to the formula 4.5m + 0.2H, where H is the height of the bench.   This means the recommended catch bench width for a 5m high bench should be about 5.5m; for a 10m high bench it should be 6.5m; and for 15m high bench it should be 7.5 metres.
Double benching (or triple benching) is used where the inter-ramp slopes angles are steep enough that single benching would result in an overly flatten slope.
For example if the inter-ramp slope is 50° and the BFA is 70°, then the corresponding calculated catch bench width for a 5m high bench would be 2.4 metres.  However such a small catch bench would be ineffective in catching spalliing rock.
If one double benched (i.e. left a catch bench every 10m instead of every 5m), then the calculated catch bench width would be 4.8 metres.  If one triple benched (i.e. left a catch bench every 15m), then the recommended width would be 7.1 metres.  Hence triple benching would be suggested in this case, assuming the rock mass is of sufficient strength to sustain a 15m high face.

Pit Slope Designer App

A simple interactive app (Pit Slope Designer App) is available to show the relationship between all of these factors.  A screenshot of the calculator is shown below.  It allows one either to calculate the IRA given a set of bench height, BFA, and catch bench criteria; or calculate the catch bench width given the height, BFA, and IRA criteria.  The four upper cells are the input cells.
Single Bench Height (BH):  this is the input height of a single operating bench.
No. of Benches between catch benches:   this is the input for single, double, or triple benching.
Bench Face Angle (BFA):  this is the input bench face angle, in degrees
Catch bench (CB):  this is the width of each catch bench, either as an input or a calculated value.
Total Height (TH):  this is the calculated total height (# of benches X single bench height)
Inter-Ramp Angle (IRA): this is the slope angle in degrees, either as a calculated value or an input.

When double or triple benching, sometimes a small 1-2m drill berm may be left between benches due to the inability of the drill to position itself against the pit wall.  The width of the drill berm can possibly be eliminated by drilling the entire double bench or using smaller drills.
Sometimes one may see the term “geotechnical berm”.   In some pit designs a large bench is introduced periodically, e.g. every 120m-180m in continuous wall height, which acts as another measure to catch ravelling rock.

Conclusion

The bottom line is that the inter-ramp angle can be achieved in different ways depending on various components of the slope profile.  Safety is of the utmost importance and therefore the adequate sizing of the catch bench is important, as is the ability to access the benches and clean up the rubble buildup.  Double and triple benching maybe required in some circumstances to achieve the design wall angles yet maintain safety catch bench widths.
For those curious about how mine economics can be impacted by increasing the pit wall angle, a small study we did  indicated that going from 45 deg to 50 deg could reduce waste quantities by 15% This was equivalent to $50 million in savings.  To read more, follow this link.  “Steeper Pit Slopes Can Save Money“.
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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Financings – It Helps to Have a Credible Path Forward

Date: May 9, 2015 Author: Ken Kuchling Comments: 1 Reply
mine economics
Update: This blog was initially written in May 2015, however not much as changed to the end of 2018.
Let me say the obvious; the state of the junior mining market is not great these days.  The number of financings is down and it seems there are a lot of companies struggling to get their piece of the financing pie.   People mention to me that there actually is a fair bit of private equity funding available but only for the right projects.
I have heard from geologist colleagues that financing grass-roots exploration is still extremely difficult.  That is unless company management has had past successes or is well connected to the money scene.
I’m told that 43-101 resource estimates alone no longer generate much excitement.  For projects to be “on the radar” they need to be advanced to at least the PEA stage.  It seems that investors want some vision of what the project might eventually look like.
I have be made aware of more junior mining companies that are struggling for cash while others seemed to have no problem in getting at least some funding to continue their operations.  To me, the biggest differences between these two situations are;
  • If there is top notch management in place,
  • The type of project they had,
  • If their path forward and development plan made sense.

You don’t want to always change management

Management is what it is.  Companies attempt to bring on experienced people to the executive level or to the Board level.   Experienced management can hopefully establish if their project will have a high probability of success or if the project is going to be a hard sell.  This will provide guidance on whether to continue spending money on the project or look for a new project.
From my experience in undertaking due diligence, when a company is looking for financing it is important that  management have the capability to present an orderly, practical, and realistic path forward.  It is important to demonstrate where they will spend the money.
I have participated in due diligence meetings listening to management teams explain that they will have a resource estimate this year and be in production in two years.  Those around the table glance at one another, knowing that they will be lucky to have a feasibility study completed by that time and even more lucky to have their environmental permits in place.   This makes investors nervous.

Keep plans realistic and achievable

It does not help the perception of a management team (or the project itself) if the path forward is unrealistic and unattainable.  The exception being if the management team have done it before.   Similarly low-balling cost estimates and presenting great NPV’s will usually fool no one that has experience. It ultimately may do more harm to credibility than good.
The bottom line is that in order for a project (and the management team) to get serious attention from potential investors is to make sure there is a realistic view of the project itself and have a realistic path forward.
Even a good property can be tarnished by making the technical aspects look over-promotional rather than real.  Make sure the right technical people are involved in the entire process and that company management are listening to them.
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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Ore Value Calculator – What’s My Ore Worth?

Date: May 8, 2015 Author: Ken Kuchling Comments: 4 Replies
rock economic value
In my view, one of the most important things you need to understand about your orebody is the insitu rock value. Hopefully it is economic, i.e. an ore value.  Its the key driver in shaping the economics of any mining project.
The two main nature-driven factors in the economics of a mining project are the ore grade and the ore tonnage.  In simplistic terms, the ore grade will determine how much incremental profit can be generated by each tonne of rock processed.
The ore tonnage will determine whether the cumulative profit generated all the ore will be sufficient to pay back the project’s capital investment plus provide some reasonable profit to the owner.

 

Does the Ore Grade Generate a Profit ?

In order to understand the incremental profit generated by each ore tonne one must first convert the ore grade into a revenue dollar value.   This calculation will obviously depend on metal prices and the amount of metal recovered.  For some deposits with multiple metals, the total revenue per tonne will be based on the summation of value contributed by each metal. Some metals may have different process recoveries and different net smelter payable factors, so several factors come into play.
To help calculate the value of the insitu ore, I have created a simple cloud-based app at this link (Rock Value Calculator App).    Simply enter your own data in the light colored cells and the rock values are calculated on a “$ per tonne” basis. Since the table is pre-populated, one must zero out the grade values for metals of no interest.

 

Price: represents the metal prices, in US dollars for the metals of interest.
Ore Grade: represents that head grades for the metals of interest in the units as shown (g/t and %).
Process Recovery: represents the average % recovery for each of the metals of interest.
Payable Factor: represents the net payable percentage after various treatment, smelting, refining, penalty charges.  This is simply an estimate depending on the specific products produced at site.  For example, concentrates would have an overall lower payable factor than say gold-silver dore production.  For concentrates, 85% is a reasonable number while for dore bars, 95% is a reasonable value.
Insitu Rock Value: this output is the dollar value of the insitu rock (in US dollars), without any process recovery or payable factors being applied.
NSR Rock Value: this output represents the net smelter return dollar value after applying the process recovery and payable factors.  This represents the actual revenue that could be generated and used to pay back operating costs.  One can see the impact that these payables have on the overall value.

Mining Profit = Revenue – Cost

The final profit margin will be determined by subtracting the mine operating cost from the NSR Rock Value.  These operating costs would include mining, processing, G&A, and some offsite costs.  Typically large capacity open pit operations may have total operating costs in the range of $10-15/tonne, while conventional hardrock underground operations would be much higher ($50->$100/t).

Conclusion

The bottom line is that very early on one should understand the net revenue that your project’s head grades may deliver.   How valuable is the rock?   It is a fairly simple calculation to undertake.
You can even start evaluating the rock at the exploration drilling stage.  I have a cloud-based calculator for this at the link “Drill Intercept Analysis“.  This calculator is a bit more complex than the Rock Value Calculation but relies on inputting drill intercept data.
Ore value will give sense for whether its a high margin project or whether the ore grades are marginal and higher metal prices or low operating costs will be required. The earlier one understands the potential economics of the different ore types, the better one will be able to visualize, design, and advance the project.
For gold deposits, I have another blog post that discusses grades, values, and how they related to open pit or underground mining costs.  Low grade narrow intervals like have much less economic potential than wide low grade interval or narrow high grade gold intervals. You can read that post at this link “Gold Exploration Intercepts – Interesting or Not?“

 

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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