Dar es Salaam : Williamson Diamond, a largest diamond mine in the country, expansion plan will see tonnage throughput ramp increase to about 5.0 million tonnes per annum in next three years, as its life extended by 20 years.
The mine, partly owned by Petra Diamonds of South Africa, development plan is expected to deliver 350,000 carats per annum (ctpa) from a grade of approximately 7.0 carats per hundred tonnes (cpht).
A statement recently, shows that Petra’s current mine plan for Williamson, in Mwadui in Shinyanga, has a life extending to 2033. “ÉBut given that the Mwadui kimberlite hosts a major resource of 33.1 million of carats (Mcts), there is potential to extend the life-of-mine (LOM) considerably,” the statement indicates.
It adds: “Such an increase in run-of-mine (ROM) grade, partially offset by a finer diamond size population, is expected to yield a 7 – 10 per cent increase in revenue per tonne”.
This comes when the mine production increased 7.0 per cent for the year ending June 2015 to 202,265 carats compared to last year output of 188,465 carats, mainly due to the increase in ROM tonnes treated.
Also, revenue increased 15 per cent to 62.1 million US dollars from 53.9 million US dollars in 2014 due to higher ROM production and the higher proportion of ROM versus alluvial diamonds sold for the year.
The high average value per carat of Mwadui mine remained relatively in line with the prior year at 298 US dollars compared to 303 US dollars of last year. In this Petra’s financial year the management took a decision to carry out plant modifications at Williamson in order to improve throughput and diamond liberation.
This is a particularly relevant strategy at this lower grade operation and the modifications are planned to enable the mine to reach throughput of 5.0 Mtpa by 2018 at a grade of approximate 7.0 cpht — previously guided roughly 6.0 cpht.
The plant enhancements will include the introduction of an additional crusher circuit and two autogenous mills, with construction commencing in FY 2016 and commissioning of the crusher planned for FY 2016 and installation and commissioning of the two autogenous mills planned for H1 FY 2017.
The plant enhancements will include the introduction of an additional crusher circuit and two autogenous mills, with construction commencing next year. Also the commissioning of the crusher is planned for next year as well while installation and commissioning of the two autogenous mills are planned for first half of 2017.