Today’s post from Darrienne Thobaven, one of our Strategic Mine Planning Knowledge Consultants, is Part Two in a Series on Strategic Mine Planning. In Part One, Darrienne discussed Putting the Strategy Back into Strategic Mine Planning.
All operating mine sites perform some sort of short-term or production mine planning. This form of planning for the mining business is tactical in nature, as opposed to strategic mine planning. A good quality mine planning process should include both strategic and tactical components. When an incomplete process is followed, issues often manifest in the short-term or production planning areas.
Examples of pain points experienced during tactical planning include:
- No ore available for mining (waste bound).
- Unable to meet blend requirements.
- Failure to achieve compliance between pit design and pit shell (for open cut mining).
- Unable to mine fast enough due to practical limitations such as small working area or grade control/blasting turn around.
- No ore available on stockpiles to feed mill when planned.
- Stockpiles breaching capacity (too much of an unwanted material type, or mining ore faster than capacity of process plant and stockpiles).
- No access into a mining area due to mining sequence chosen or unable to turn over grade control/blasts fast enough.
- Unable to meet planned mill head grade.
- Time consuming and frequent rework of plans to find a schedule solution.
- Lowered productivity as frequent rework of plans reduces production readiness for mining.
- No direction under changed conditions due to lack of understanding of critical success factors.
- Poorer financial performance.
Many of the above pain points could be caused by differences between mine planning assumptions and reality such as a poor reconciliation between resource geological predictions and grade control prediction; or assumed mining fleet productivities being higher than actual productivities achieved in production. Setting aside these issues with unrealistic or incorrect planning assumptions, all of the pain points listed could be a result of a flawed planning process.
The tactical issues are more likely to occur if there was no truly strategic planning performed. With the rush to get metal out the door and realize the cash flow, strategic planning may not be a priority and can be viewed as a time consuming exercise that does not add value. Or there may not be the skills or budget available for strategic planning.
By not performing truly strategic planning, the crucial learnings of bottlenecks, sensitivities and critical success factors are not understood, and therefore cannot be communicated to tactical planning or production management personnel.
Although operations exist that knowingly or unknowingly do not perform strategic mine planning, it is much more common that some degree of strategy is analyzed, at least at the feasibility stage and prior to commissioning. However, that effort is often made by external consultants and by the time production begins, the feasibility report is often found on a shelf gathering dust. As a result, the assumptions are outdated and there is a complete disconnect between the strategic and the tactical plan.
By not including practicalities or constraints, the strategic plan is often not achievable. In open cut mining of ore bodies overlaid by a waste zone, the vertical rate of advance (VRA) is often more limiting than total tonnes trucked. VRA is the maximum number of benches that can be mined in a period and is a limitation of the grade control or blasting processes. If the impact of different VRA assumptions (in vertical meters or benches mined per year) is not evaluated or even used as a constraint, then the strategic plan may mine at a rate that could never be reached.
This concludes Part Two of the Series. Next week, we will examine a complete mine planning process – be sure to check back for Part Three.
UPDATE: Post Three – The Three Phases of Mine Planning is now available online to read.
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