Venetia diamond mine's primary crusher
The new primary crusher at the Venetia diamond mine near Musina
in the Limpopo Province, RSA was commissioned successfully on schedule
at the end of April 2006. This R232 million project to design, supply,
install and commission a replacement primary crusher commenced in
June 2004 and followed on earlier feasibility studies on the project
conducted by Bateman Engineering. The project also included conveyors,
a dust-extraction system, a workshop and an electrical substation
for the plant.
Once construction was completed, the last stages of the project saw
the work at the new crusher signed off as per the contract and quality
checks made. The electrical substation was energised and all the working
parts in the crusher and its infrastructure were tested. Material
was then passed through the plant to ensure no spillage of material
occurred and retrofits done where required.
As the crusher will have to cope with between four and five different
types of feed material, ranging from very hard (40 MPa hardness) to
wet and sticky, 1,000 t of each material was fed to the crusher. Each
of these materials was handled as per specification.
Finally, the crusher was operated for a period of 72 hours during
which it had to be shown that the crusher could process 1,200 t/h
of mine feed.
Several innovations were included in the facility. The presence of
large pieces of tramp iron in the feed, such as drill tubes up to
10m long and 150mm in diameter, has the potential to disrupt flow
through the crusher by entering and bridging the channels in the crusher,
resulting in feed blockages which would have to be cleared manually
while production was halted. This possibility is minimised by providing
the operator with a good view of the discharge of feed from the apron
feeder into the crusher so large pieces of iron can be detected and
removed from the crusher before a major blockage occurs.
A 90 t electrically operating travelling (EOT) crane with a 15 t
auxiliary crane and a clam-shell bucket is provided so that the crusher
can be maintained and material cleared out of the box surrounding
the crusher and for the easy removal of any tramp iron.
The gantry carrying the crane had to be erected from both ends. The
final 18 m span linking the ends fitted perfectly when it was lowered
into position, a compliment to the attention to detail by the design,
manufacturing and construction teams.
In facilities of this size, a separate access way is usually provided
so that large items of equipment can be reached for maintenance. In
the new crusher building, several access wells were provided, with
the main staircase also being used as the service duct for the electrical
cabling and piping, greatly facilitating access for maintenance.
Holding tanks at the top of the building mean that the lubrication
oil for the crusher can be pumped rather than being transported in
barrels, as has been done traditionally.
The ore feed to the crusher, containing large blocks of ore up to
1.5 m in size, are transported to the plant in 180 t haul trucks,
with allowance in the design for future 240 t trucks.
These large blocks drop from a considerable height into the bin with
tremendous impact. To ensure the bin is sufficiently robust, the liners
were installed first, welded and then used as permanent shutters against
which the concrete for the bin was poured. The concrete and the liners
therefore fit closely, with no gaps between the two, reducing the
risk of the plates being dislodged from the concrete.
The new crusher has been designed with an intended 20 to 25 year
life span and will enable the mine to maintain production when the
old crushing plant, located at the edge of the existing pit, is demolished
to extend the pit life for a further 10 years after which operations
will move underground. The change in the open-pit operations will
increase the stripping ratio of waste-to-ore from about 2 to 1 up
to as much as 10 to 1.
Bateman Engineering also assisted the mine personnel for a further
month with minor technical problems that were revealed during the
initial routine operations. The contract also provides for a subsequent
11-month guarantee period.
During this project Bateman Engineering was also engaged in a project
to upgrade the infrastructure at Venetia (see BATEMAN Globe No. 53).
These projects were undertaken subject to a partnership model agreed
between De Beers and Bateman Engineering that was introduced in 2004
(see BATEMAN Globe No 39).
For further details of the Venetia primary-crusher project please
contact James Nieuwenhuys, Senior General Manager, Diamonds, or Vincent
Diesel, Project Manager, on +27-11-899-9111 or email diamonds@BatemanEngineering.com.
