Why Mine Plans Rarely Survive Reality

Balancing Mine Life and Revenue in Planning

Within certain mining situations, there is a delicate balance between how much mine life to achieve and ensuring enough exploration and construction time. Sometimes these factors take a front seat over strictly focusing on revenue. The approach involves picking apart what is going to be easy to mine, what can be done with a minimal haulage fleet, and how everything will sequence together.

Once you get a pit shell and a pit design, those are easy to look at in completion. However, there are many difficulties, especially when running multiple pits and determining how to sequence things in the best way.

Operational Challenges Software Cannot Capture

There are many things that mining software does not pick up well regarding operational challenges in really small benches at the bottom of pits. Most software shows a decreased mine rate and accounts for difficult drilling and gaps between loading and blasting. However, it does not capture the full operational challenge of trying to squeeze a shovel and three trucks down in a bench that is only a couple hundred feet wide. When starting a long haul from a tiny pit, there are many additional impacts and factors to consider.

Parallel Processes and Unexpected Events

Many things run in parallel during mine planning and operations. Unexpected equipment downs, personnel issues, and accident damage occur regularly. In some cases, operations encounter unexpected voids that require different planning approaches. At mines with historical underground workings, voids routinely changed entire pit designs mid-pit, throwing all long-range plans and whole departments into disarray.

Building Adaptability Into Mine Plans

Creating a perfect mine plan is not entirely possible. Part of the planning process involves making a plan that has some level of adaptability built in. If operations are completely dependent on a plan being exactly what it is, with no options or alternatives if something goes wrong, difficult challenges arise very quickly.

The first casualty in every war is the plan – this principle applies directly to mine planning and becomes ingrained through years of working in technical services. It happens all the time.

Realistic Plan Compliance Expectations

Based on experience, if a mine plan is implemented at 80% accuracy, that is excellent. Generally, 80 to 85% compliance to the plan is considered pretty good. Most of the time, compliance has been over 85% for long-range planning.

Short-range planning is more variable. Some weeks are so unplanned that the week two plan can run right alongside the current week. Other times, two or three days into execution, the short-range plan no longer exists.

Achieving High Plan Accuracy Through Flexibility

Achieving near 90% accuracy goes back to adaptability. Developing a long-range plan with options is essential. For instance, when mining two different pits, try to be in areas where if ore does not show up, the strip ratio goes wrong, or a void gets in the way, there are other options in the other pit for delivering similar ore types while managing the problem.

This approach provides time to divert mining assets. If a shovel is lost, a loader can be moved over. Truck counts can be changed if that adaptability is built in. If a plan involves finishing a very small pit as the only ore feed while stripping nothing but waste for half a year in another pit, and there is an issue with ore delivery or the loading unit, real problems arise with downstream effects to the process plant and crushers.

When operations start ore dives in areas that get out of sequence, they quickly move away from any semblance of the long-range plan. If the plan has options built in with backups, that is the best way to stay with something that looks like what was planned for at the end of the year.