WINNING
The road grades and width of the permanent ramps, spirals, as well as loading and tipping points, are
influenced by the size of the trackless equipment and the effective safe operating slope angle.
expenditures (capex) refer to the cost
associated with establishing the mine or
quarry. This pertains to the expenses of
conducting the front-end studies, such as
the appointment of EPCM consultants and
contractors to do the various feasibility
studies, trade-off studies, and optimisation
studies and designs.
Operating costs (opex) are the costs
associated with the day-to-day running of
the operation. This is the actual nuts and
bolts required to run the mine or quarry.
It entails everything from the salaries, the
fuel, and service of trackless equipment, to
the water and electricity of the plant.
Marketing considerations relate to
having a market for the product being
produced. In the case of an opencast
mining operation, it would entail having an
offtake agreement in place before the first
ton of material is processed. In the case of
a quarry, market condition will be driven
by construction and associated property
development. Dimension stone operations,
on the other hand, are at the mercy of
the current trends, such as marble versus
granite countertops.
The selection of mining equipment is
usually done to determine the equipment
best suited to the type of material, size
of the operation, and on-site processing
requirements. The mining equipment
selection will include everything from
the blasthole drill rigs, excavators,
and front-end loaders to haul trucks.
The equipment will be sized to meet
the requirement set out by the mining
schedule and the capacity of the plant.
Open pits and quarries use trackless
mining, and trade-off studies will usually
be done to determine the benefit of
using certain brands of heavy vehicles,
based on the production specifications.
Correct selection of vehicles will also
have an impact on the capital layout and
operational costs.
The on-site plant set-up will be
determined by the level of beneficiation
or processing that is required of the
product at the mine gate. Quarries may
require only basic crushing and screening
equipment, whereas opencast operations
may require more sophisticated washing
plants. The operator has the option of
having a fixed capacity plant for the life of
mine or flexibility by using a modular plant
set-up. As with the trackless equipment,
the plant equipment selection is based
on the requirements of the operation and
optimising it as far as possible.
The rate of production is influenced by
commodity or product price and demand.
Locating infrastructure in terms of the
cost impact it has on the mine is another
factor that needs to be kept in mind when
doing the plant design and selection. The
placement of the entire infrastructure, from
the offices, parking bays, and workshops to
plant, needs to be optimised. This includes
distance from the mining or quarrying
operation, without sterilising portions of
the deposits, and proximity to the access
road(s) for road transport to market
delivery or shipping points. ■
ABOUT THE AUTHORS
Nicolaas C Steenkamp is an independent
geological/geotechnical consultant, while
Breton Scott is the managing director of
Bowline Professional Services.
Bowline Professional Services provides
consultation services during the planning
and front-end development of opencast
or quarry operations and has a unique
service offering called ‘Mine in a Box’. This
concept fast-tracks (without shortcuts)
the design and development processes to
bring a small-scale mine into production
as early as possible.
QUARRY SA | JULY/AUGUST 2018 _ 15