By Hilary Mare
FOLLOWING massive water ingress at its Tschudi copper mine on May 11, Aim-listed copper miner Weatherly International has proceeded with a recovery plan that entails dewatering the mine with expectations that production levels will normalise by December, Confidente understands.
The recovery strategy and expenditure plan will require N$14.3 million.
Currently, work is under way to increase pumping capacity to lower and stabilise the water levels in all pits and allow mining operations to regain access to the ore.
Weatherly Namibia Chief Executive Officer, John Sisay remarked that, with the necessary financial assistance from Orion Mine Finance, the company is confident of implementing the recovery plan and restoring normalised production levels at Tschudi.
The recovery strategy is based on a 12 week delivery and includes water abstraction, related to all equipment and infrastructure required to reduce water levels in the pits and to pump it into the canal that runs along the footwall of the pit; water discharge, dealing with moving the water away from the open pit mining area and discharging it at re-injection areas which have been approved by Namibia’s Department of Water Affairs; and implementation of various supporting actions to improve post-recovery water management.
So far, abstraction capacity has been increased from 1 400 m3/h to 3 000 m3/h through the rental of additional diesel-driven pumps and the installation of 1 800 m of high-pressure high-density polyethylene pipelines.
A canal and settling dam are now fully commissioned to handle the water discharge, with the canal capable of handling more than 6 000 m3/h.
Distribution from the settling dam is maximised, with current installed infrastructure at 2 000 m3/h to direct water to various discharge points through a storm water pond, with the balance of the water overflowing the settling dam back into the aquifer.
Additional infrastructure is planned to increase distribution by 2 000 m3/h from the settling dam by the end of July.
Significant progress has been made to design, cost and implement a significant upgrade of the dewatering infrastructure.
The system will be upgraded to increase the abstraction and discharge rate to a nominal 3 000 m3/h through a predominantly electric grid-power system.
The system will be developed in three phases at an estimated capital cost of N$44 million. This will include an additional grid-power substation to increase power supply to Tschudi by 4 MVA to 12 MVA.
Management remains confident in the future financial viability of the Tschudi mine.
Tschudi is a low-cost open-pit mine extracting oxidised copper ore to be treated through heap-leach, solvent extraction and electro-winning. Environmental approval for the Tschudi mine was granted in April 2013 and ground-breaking was held in November 2013. Civil construction works at the mine site began in April 2014 and the first copper was produced in October 2015.
Tschudi is expected to produce an average of 17,000t of copper per annum during its 11-year life period. The deposit is expected to create more than 500 jobs.
The ore body of the Tschudi mine is located in the basal sandstones and minor conglomerates of the Malden Group. The deposit is open-ended at the south-west and has a strike length of approximately 2,500m.
Oxide mineralisation at Tschudi occurs up to a depth of 70m below surface. Beyond the 70m level, a transitional zone of mixed sulphide-oxide mineralisation then extends to a depth of approximately 110m, followed by a sulphide zone.
Copper mineralisation in the oxide zone is mainly composed of malachite and minor chalcocite. The mineralisation is disseminated through a sandstone and conglomerate unit lying above a dolomite unit. The sulphide zone contains chalcocite and bornite, while the transitional zone contains a combination of chalcocite and bornite.
As of December 2015, the mine was estimated to contain reserves of 24.4Mt of ore grading at 0.85 percent copper containing 207,000t of copper.
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