FAQ's about Strategic Open Pit Planning






MaxiPit Info


Training and support
Importing models
Economic model
Ultimate pit
Pit slope modeling

What is the difference between MaxiPit and NPV Scheduler?* MaxiPit produces the ultimate pit, pit phases and optimal extraction sequence.

NPV Scheduler does everything MaxiPit does but then takes the user on to pushback design and optimizing the production schedules, or in other words, NPV Scheduler finds both the ultimate pit and the optimal pit.


Which computer operating systems are supported? Microsoft Windows 98 and NT 4 or later.


What training do I need to start using the program? MaxiPit comes supplied with a comprehensive set of introductory and advanced tutorials which take you step-by-step through all the important procedures needed to complete an optimization. The user interface is designed for ease of use, no complex parameter files to edit, just click the options you want on the dialogs and run. The programs also has a powerful set of contouring and charting tools for easy viewing and presentation of your optimization settings and results.
What support services are available? The developer provides a free to subscribe support Newsgroup where you can post questions and review related discussion topics. If you require a personalized support service, you can opt to subscribe to the support service for an annual fee which puts you in direct contact with the program author and qualifies you for discounts on all program upgrades. General phone support is also available through the developer.
What costs are involved with updates or upgrades? Minor software updates are available free of charge to all registered users. As there is no annual maintenance fee, upgrades attract an upgrade fee - the scale of the fee depends on the content of the upgrade. Subcribers receive substantial discounts on all upgrades.


What discounts are offered for multiple license purchases? Multi license packs (MLP) offer significant discounts for bulk purchases. Licenses can be purchased in quantities of 3 or more.
What deals are offered for universities? Significant educational discounts are offered on all products. Please contact MP & Associates for pricing: sales@mpassociates.gr.


How reliable is the ultimate pit generated by MaxiPit? An independent firm of international mining consultants was commissioned to compare the ultimate pit generated by MaxiPit against the ultimate pit generated by its most expensive competitor, Whittle Four-D. You can download the consultant's report from the product page to get all the details. To quote from the report...

"The results of the comparisons show no significant difference between the optimum pits generated by Maxipit or Whittle. The differences that do exist in product tonnage and metal are negligible, the higher differences in the total pit volume is a reflection of slope modeling accuracy and is to be expected."

And to quote from an in-house evaluation by CVRD, the largest iron ore mining company in Brazil...

"Comparing the results of MaxiPit and W4D with exactly the same slope sub-regions, there were not significant differences in the surface topography of the ultimate pits generated."

Who is using MaxiPit and/or NPV Scheduler?* Current users include:
Codelco, Chile (copper)
De Beers, South Africa (diamonds)
Placer Dome, Canada (gold)
Miller Mining, UK (coal)
Ultrafertil, Brazil (phosphate)
Normandy-LaSource, France (gold)
MBR, Brazil (iron ore)
CSN, Brazil (iron ore)
Knight Piesold, Argentina (borax)
Millennium, Brazil (mineral sands)
Ashanti Goldfields, Ghana (gold)
Polymetal, Russia (gold)
Sishen, South Africa (iron ore)
Rio Tinto, UK (various)
Orapa Mine, Botswana (diamonds)
Amplats, South Africa (platinum)
Placer Pacific, Australia (gold)


What is a phase? A phase (nested pit) is a Lerchs Grossman ultimate pit obtained for specific block economic values. The only criterion used to obtain a phase is the maximization of cash flow.
What is an ultimate pit? The ultimate pit gives the highest possible undiscounted cash flow without considering the practicalities of access or scheduling targets. It is a good first-order approximation for economic viability of an exploration target.
Importing models


What file formats are required for importing an ore reserve block model? ASCII text and SQL tables can be imported in two general formats. Text files can be either fixed column width or character delimited. Standard Datamine, Surpac, Vulcan, Micromine and Medsystem block models are also supported.
The grades in my block model are in % and ppm. How does the program know how to deal with this? Percent grades result in products expressed in 0.01 of the rock mass unit. For example, if the rock unit is metric tonnes, 1% is equivalent to 10kg/tonne and so 1 unit of product mass equals 10kg. Similarly, 1 ppm is equivalent to 1gram/tonne.
Economic model


Can mining and processing costs be varied for different ore or rock types? Yes, the reference mining and processing costs may be adjusted by specifying different cost adjustment factors for each rock type.
Can I predefine a profit model of my own and by-pass the calculation of block values? Yes, simply select either the cost or profit model option on the initialization dialog.
Is it possible to vary the mining cost with depth or by other user defined criteria? Yes, positional mining and processing cost adjustment factors can be read from the block model. These may be varied with depth, by rock type, by geotechnical quality, or in any way the user wishes.
What about multi-element ores? Yes, any number of grades or values may be specified in the input block model. Block revenues are derived from the accumulated value of all elements with prices set individually for each element. A variety of cut-off grade methods are also provided to control the selection of ore blocks.
Can I specify multiple ore processing methods? Yes, any number of processing methods e.g. mill and leach, may be specified. The program calculates the cut-over grade for each method ensuring the block is allocated to the processing method which generates the highest possible cashflow.
Can the initialized block value model be exported so I can check the values before proceeding with the optimization? Yes, you can review the block values using the Contour Bench tool or export the model back to your mining package.
Ultimate pit


Which technique is used to find the ultimate pit shell? MaxiPit is based on the Lerchs-Grossman pit optimization method. The numerical implementation differs from other pit optimizers, but the results are the same.
What does the optimal extraction sequence tell me? The pit optimization produces three valuable pieces of information about each block: (1) it determines whether the block is inside or outside the pit, (2) it determines if the block should be processed as ore, and by what processing method, or sent to the waste dump, and (3) it determines the block extraction sequence that generates the highest net present value for the pit. The latter is termed the optimal extraction sequence. Each block in the pit model is numbered, forming the most detailed possible set of nested pits. The sequence number is an extremely useful design guide when manual pit designs are being prepared.
Can I apply restrictions to the lateral and vertical extents of the pit? Yes, and as many as you wish. The ultimate pit extents may be controlled inside or outside a series of depth limited polygons created interactively by the user.
What about limiting the pit depth for underground mining? Yes, the underground mining and processing costs can be specified for each rock type and the program will automatically determine the economic limit to open pit mining.
Once the pit surface has been generated, what can I do with it? You can...
  • report the contents and value of the pit,
  • contour any block attribute by bench,
  • contour the ultimate pit surface and phase surfaces,
  • chart block attributes against extraction sequence or phases
  • export the pit model
  • export the pit surface
Slope modeling


How difficult is it to define complex slope regions? Any complex model takes time to build, but MaxiPit makes this task as easy and as visual as possible for the user. But don't take our word for it, read the evaluation reports on the product page... quoting from the independent consultant's report:

"The linking of blocks to model slopes is the core of any optimization package. On the basis of the limited analysis we have performed Maxipit models slopes at least as well as Whittle. The methodology for defining slopes in Maxipit is more flexible and more easily visually checked than that in Whittle. Maxipit has a capability to read the slope specifications from a Whittle parameter file, however this is a compromise which does not give as good a result as can be achieved by specifying the slopes using Maxipitís parameter screens."

Can I import DTM surface models from other programs to define slope regions? Yes, there are data source drivers for a wide range of DTM data sources and file formats.
* NPV Scheduler does everything MaxiPit does but also takes the user on to pushback design and optimizing the production schedules (in other words, NPV Scheduler finds both the ultimate pit and the optimal pit). MP & Associates can sell NPV Scheduler. If you are interested in this product, please contact us: sales@mpassociates.gr.

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