In the media

Lace development on schedule, says DiamondCorp

03 February 2011

Author: Petronel Smit

Junior miner DiamondCorp reported that the decline development at its Free State Lace mine is on schedule and within the £5-million budget to access the main kimberlite pipe at the -260 m level in March.

The Africa-focused company on Thursday reported that the development was progressing, despite heavy rainfall over the project area in recent weeks posing challenges for waste haulage and dewatering.

CEO Paul Loudon said the DiamondCorp team continued to successfully overcome the technical challenges of opening up an old kimberlite mine that has been underwater for more than 75 years.

“We are now weeks away from accessing the top level of the estimated 33-million tons of kimberlite remaining below any of the old working areas at Lace,” he noted.

DiamondCorp in December reported its intention to raise about £2,95-million through a new share placing for further development work at its Lace mine, and for debt repayments, after it raised £6,6-million in April 2010, to implement the decline development, among others.

The decline at Lace from the portal to the current working face was more than 1 km and about 200 m in vertical depth, with a further 220 m of development be completed before access to the main Lace kimberlite pipe was achieved. This decline would be used for the haulage of kimberlite for bulk testing purposes and for waste and ore haulage during the ramp up to full-scale production.

The 1,2-million-ton a year dense-media separation plant at Lace has also been successfully recommissioned with feed from the tailings ready for processing of fresh kimberlite. Once the existing vertical shaft was re-equipped for primary ore hoisting, the decline would be used for men, materials and ventilation for the remainder of the 25-year life of the mine.

The refurbishment of the vertical shaft and the ramp-up to full-scale production was scheduled to take between nine and 12 months to complete and, as at November, the cost for this development was estimated at £5,3-million.

The 1 328 ct of diamonds recovered during plant recommissioning would be tendered in Johannesburg during February to determine the current market price for Lace tailings diamonds.

Loudon said that world diamond prices have recovered to levels higher than before the crash of 2008, and the long-term metrics for the industry remained strong.

“We look forward to processing the first 30 000 t of fresh kimberlite at Lace in the months ahead and reporting the recovered mining grade and carat value before the end of the second quarter,” he added.

The Lace mine has also entered into a joint venture with African Mobile Crushers to investigate the potential for selling andesite waste rock from the decline development as sized crushed stone product.

Income from this activity has the potential to provide a useful contribution to ongoing mine development expenditure.

Meanwhile, the planning for a minibulk sampling programme on the first of two diamondiferous kimberlites discovered near Jwaneng, in Botswana, was also being finalised.

The first pipe to be tested would be J-05, a 1,5 ha kimberlite under about 28 m of Kalahari sand, which comprised calcretised kimberlite from about 28 m to 50 m vertical depth, slumped Karoo mudstones and volcaniclastic kimberlite from 50 m to up to 105 m vertical depth. It also hosted various facies of volcaniclastic and coherent kimberlite from 85 m to at least 218 m, the deepest drill intersections from the initial programme.

geological study suggested that the J-05 kimberlite was the same or similar age to the kimberlite being mined by Debswana at Jwaneng, the richest diamond mine in the world measured by value.

Analysis of core samples also revealed the presence of two macrodiamonds, suggesting the possibility of a coarse stone size distribution.

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