ppc riebeeck mine and cement factory - Aurecon AME ...

PPC Riebeeck West: Storm water Management Plan Page 17
Figure 1-11: Visual indication of the future overburden dumps
1.5.6 Drilling, blasting and secondary breaking
Drilling: Drill holes are marked out in accordance with short term mine plans in areas stripped
of overburden. PPC Riebeeck has their own drill rig which is fitted with dust containment
equipment to perform the required drilling operations.
Explosives / Blasting: Blasting is conducted in accordance to detailed blasting work
instruction. Blasting in the quarry involves the direct ordering of bulk explosives from the
blasting contractor, transporting the explosives to the working face, the design of the blasting
pattern, the inspection of the hole depths, the charging of the holes, the stemming of the holes,
detonation of the explosives, ensuring that security arrangements are made and put in place
and the making safe of the working area after blasting (inspection and destruction of misfires).
Mining will take place through conventional drilling and blasting methods to an estimated final
depth of 240m. Blasting occurs on average every 2 weeks. Each blast is monitored for air
blast, noise and ground vibration.
Due to the soft nature of the overburden and shale, it can be removed using an excavator.
Below 30m depth the waste rock requires blasting to optimise the side wall slopes and to
expose the deeper limestone resources.
PPC Riebeeck has a licensed explosive magazine which is used to house accessories for the
blasting activities.
Secondary breaking: According to recent blasting studies, nearly all the fragmented rock is
less than 750mm which can then fit within the current primary crusher. The occasional
fragment of rock which is too large to fit into the primary crusher is transported to the primary
crusher area and then broken up through secondary breaking using a pecker, until it is of
suitable size to be crushed.