Petra Diamonds, the majority shareholder of the Williamson, said the current mine plan has a life of 18 years while potential mine life 50 years plus. “But given that the Mwadui kimberlite hosts a major resource of 39.6 Mcts (million carats), there is potential to extend the LOM (Life of Mine) considerably,” the firm said on its website.
Petra’s current mine plan at Williamson is to ramp up ROM production from ca. 2.5 million tonnes (Mt) in its 2013 financial year to ca. 3.6 Mt by 2016 financial year, following the introduction of a re-crush system into the plant circuit. And in the first nine months of the Petra’s financial year, Williamson mine output increased significantly major rehabilitation to its treatment plant.
According to interim management statement issued by Petra, owns 75 per cent stake at the mine, diamond production increased by 471 per cent in nine months from July 2012 to March, this year. The production has gone up from 21,570 carats in nine months that ended in March 2012 to 123,243 recorded in nine months that ended in March this year.
The firm statement said the mine’s run-of-time (ROM) production continued as planned, where basing on tonnages treated it has improved significantly to remain in line with projections. “At Williamson, ROM production continued as planned,” the statement said attributing it to “commissioning of the rebuilt treatment plant, with ROM tonnages (increase) significantly.”
William produces 5.6 carats per hundred tonnes (cpht), which remains in line with guidance of 5.5 cpht backed by commissioning of the rebuilt treatment plant. The mine that underwent extensive development to increase its capacity last year saw its treated tonnage increased by 436 per cent from 423,131tonnes to 2,266,113 tonnes in the said nine-months.
Open University Senior Lecturer, Dr Hildebrand Shayo said the increased production at the Mwadui mine was good news since many people thought deposits at the mine had finished. “This is good news,” Dr Shayo said “as the mine is going to continue producing.
Some of us think it has reached its mining tenure.” The swelling production only came from phase one of expansion. The mine’s Phase 2 expansion project, which was initially planned to take the mine to 10 million tonnes per annum (mtpa), is currently on hold, though Petra continues to consider approaches to further significantly increase production beyond 3.6mtpa.
“An expansion plan above this level will be dependent upon appropriate electricity and water supply, as well as the results recorded from treatment by the rebuilt plant of main pit material over the medium term,” the firm website shows. According to Wikipedia, Williamson is the world’s largest economic kimberlite by surface area at 146 hectares in size.
It is a historic source of high value Type II diamonds and fancy pinks. It is Tanzania’s only important diamond producer and despite having been operated continuously since 1940, the pit is only 90 metres at its deepest point due to the large size of the deposit.
The mine was discovered in 1940 by Dr John Williamson, a Canadian Geologist and is the largest economic primary diamond deposit to be in continuous production. By the 1950s the mine had developed into a successful operation with state-of-the-art equipment and a labour force of several thousand.
In 1958, the mine was sold to an equal partnership between De Beers and the colonial Government of Tanganyika. De Beers operated the mine until 1973. From 1974 to 1993, the mine was operated by STAMICO (the State Mining Corporation). In 1993 De Beers returned to Williamson as operators, together with a recapitalisation and ownership restructuring.
Production increased to approximately 195,000 carats per annum to 2005. Despite the increase in tonnages treated the mine did not return to profitability and De Beers decided to sell its 75 per cent interest to Petra in November 2008. Petra completed the acquisition of Williamson in February 2009.
The turnaround comes after expansion capital expenditure (Capex) of 20.6 million US dollars for 2012 was predominantly spent on finalising the rebuilt plant and on other production related activities, including pit shaping/shale removal, haul road construction and slimes/tailings handling facilities.
Due to the deferral of the Phase 2 expansion, 25 million US dollars of previously planned Capex was not spent in 2012. The deferral of the original Phase 2 expansion programme also resulted in expansion Capex savings in 2013 of 29 million US dollars (in comparable 2013 financial year money terms).
Petra Diamonds is an independent diamond mining group and an increasingly important supplier of rough diamonds to the international market. The company has interests in eight producing mines: Seven in South Africa (Finsch, Cullinan, Koffiefontein, Kimberley Underground, Helam, Sedibeng and Star) and one in Tanzania (Williamson).
At least life will continue at Mwadui mine, as diamonds seem to be forever there.
Source: The Daily News, reported by Abduel Elinaza in Dar es Salaam
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