v1.6 and NPV Scheduler+MFO can be installed and run independently on the same computer.

"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."

Please contact your nearest Datamine office for details of the latest releases.

1. Design or import practical pushbacks. There are good push-back design features within NPV Scheduler, and realistic design constraints can be imposed. NPV Scheduler does not use ‘phases’ from optimization as the start point for push-back design.
2. Consider alternative pushback sequences.
3. Obtain realistic mining schedules that take into account any number of crucial targets like ore production rate, stripping ratios, cash flows, blending, contamination control, etc.
4. Determine realistic NPV estimates that can be very different from the very tentative figures produced by other products.

By ‘Scheduling’ we do not mean ‘sequencing’ - which is exactly what MaxiPit does. Scheduling starts from a practical set of pushback designs, which are then scheduled for Optimum NPV. Beware of the expression "sub-optimal maxima": either the schedule is optimized or it isn't - its a bit like calling something "almost unique".

A further enormous advantage of NPV Scheduler v2 is that it handles stockpiles, both building and reclaiming. No other product does this.

1. The phases may have little to do with the practical pushbacks. The pit sizes may vary wildly, especially when there is a gap problem. A phase may consist of several disjoint holes in the ground. There is no allowance for access. There is no possibility to limit early pushbacks to one area of the mine to avoid excessive infrastructure costs. This problem of the use of phases as a starting point is not eliminated even if you include controls on such aspects as minimum and maximum leads, maximum advance rate etc. NPV Scheduler itself has many practical controls on pushback generation. The important point is where you start from – and NPV Scheduler starts from realistic pushbacks.
2. The assumption that you mine one phase entirely before starting the next one is very unrealistic. For example, to keep the mill supplied with ore at all times you usually have to start prestripping the next phase way before you finished mining the previous one. This may change NPV a lot as you are moving waste stripping ahead in time.

Secondly, automating pushback generation is great but it needs to be coupled with interactive user controls so the user is able to satisfy external design criteria. In NPV Scheduler, the user retains full control over the position, extent and depth of every pushback.

Finally, "scheduling" in most other products is simplistic and does not meet the real life scheduling needs of an operating mine. Pushbacks are always extracted, to some degree, in parallel, if only to begin stripping the next pushback while the ore mining is concluded in the previous one. Even the simplest of mining operations requires a multi-target approach on scheduling. NPV Scheduler not only ensures that the pushbacks and schedules are practical, but also delivers the optimal solution for each set of user imposed conditions. If a non-optimal path is taken in extracting the pit (as occurs when phases are used to build pushbacks), the NPV will peak and then decrease before the ultimate pit is reached. In other words, the mine life is shortened. Only NPV Scheduler can obtain the optimal schedule and so maximize the NPV, cashflow and life of the mine.

The full incorporation of stockpiles and the integration of cut-off grade optimization (by MFO) are unique features of NPVS and the Mine Flow Optimizer together.

• 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

"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 Maxipit’s parameter screens."

1. Each pit, with the possible exception of the last one, is not smaller than a specified size (it may be larger).
2. Each pit contains spatially connected blocks; that is, it cannot consist of disjoint holes in the ground.
3. An access to each pit must be guaranteed. This is defined as follows. A given pit in a sequence of push-backs can be an extension of an earlier pit, or it can be located in a different sector of the mine sharing no common areas with the earlier pits. If the pit is an extension of an earlier one, then the boundaries of the two pits must coincide wherever they are identical with the final pit limits; anywhere else, the boundaries must be separated by a distance that is not less than the value of the Access Space Parameter.

The Pushback Generator takes the blocks from the extraction sequence and builds spatially connected pits until one of them reaches the minimum required size. Next, the pit is checked for NPV optimality and access requirement. This may result in adding additional blocks to the pit. For example, ore blocks that are accessible for mining may be added because otherwise they would be mined much later thus decreasing the NPV. The access space requirement may increase the pit size considerably. Thus, the pushbacks are unequal in size to improve NPV and ensure access. If the sizes vary too much, they can be adjusted using the Adjust tool.