Mining in focus
M
ine planning should highlight the reality of the geological
structure, the process capabilities, and the economic
unpredictability of demand and commodity markets. Mine
planners and schedulers work shoulder to shoulder with most of the
technical service departments at a mine. They process geological sample
data from the mine, survey updates, production capacity of each stage of the
process, available equipment, machinery and human resources, sales demand
and commodity prices, production cost assumptions, and the health and
safety of workers.
Mine planning and scheduling work follow a logical order in which to
optimise productivity and minimise uncertainty. It also requires the mine
planner to have a good grasp of the mining process (a jack of all trades).
Mine planning and scheduling usually form part of the mineral resource
management (MRM) department.
Main focus on walls and the face
A mine plan should be the focus on the walls of meeting rooms and
offices at mines. It should be visible, visual, and has to contain a number of
elements, ranging from geological features to ventilation flow directions and
infrastructure locations, and should preferably be done on a small-scale map,
such as 1:1000. In comparison, the schedule should normally be visible near
the active working faces. Each month’s advance is indicated by a specific
colour and the layout will be reflecting the mining method, for example
board-and-pillar or strip mining.
The data used by mine planners is generated by the geological
department through structural mapping as well as geochemical sampling
and assays of drill core and face or bench samples. This data is used to
construct the base geological model and resource and reserve block models.
At the same time, geotechnical and rock engineering data is incorporated
into the model and maps. This is then combined with the mining advance
survey data, gathered at different intervals on so-called measuring days,
depending on the mining method. The combination of this data is used
to produce a planned production schedule based on mining constraints.
Optimising the plan typically requires completing multiple plan scenarios.
Mine plans are generally done at various planning intervals, for example
monthly, three-monthly, yearly, every five years, and life of mine. The
mine plans and schedules are periodically updated as new data, methods,
or assumptions are introduced. Mines generally employ short-term and
long-term mine planners.
The detail is in the data
The detail of the data contained in the block model also needs to be
sufficient for the level of planning that needs to be done. The short-term
mine plan will contain a higher density of data versus the long-term
model that can be updated as infill drilling is done over the life of mine.
Underestimating the mineable reef or seam over a couple of hectares may
result in a planned production shortfall. This is in effect sterilised mineable
ore that results in a revenue loss to the mine. The type of model applied for
a type of deposit will also have a bearing on the mine plan; for example, grid
models can be used to characterise stratified deposits in a more appropriate
way than block models. They also provide additional flexibility for mine
planning.
Several physical and legislative influences affect mine planning.
Hydrological constraints, lease or permit boundary, the presence of historical
sites or graves, topographic gradient, the location of related infrastructure,
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