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JSE-listed diamond exploration and development company DiamondCorp, says the 47 level block cave development at the Lace mine in the Free State province of South Africa is on track.

Treatment Plant Commissioning

The company reveals that it has completed the required modifications to the 1.2 Mtpa Lace processing plant to allow seamless transition from treatment of the tailings to underground kimberlite. Plant commissioning is underway and re-treatment of tailings will commence soon. The modifications were completed on schedule and within budget.

Tailings re-treatment will operate initially on a single shift until the market price for the Lace tailings diamonds is established with the first sale anticipated in September 2013. If prices achieved result in sufficiently attractive operating margins, the company says it will look to increase to two shifts and potentially three shift operations before year end as approximately 3.5 million t of tailings remain on site and available for processing. Tailings retreatment economics should be assisted by the recent weakness in the South African rand and the reported improvement in diamond prices.

Development Activities April-June 2013

Surface and underground development activities accelerated in the period April to June.

Trackless mining crews focussed their blasting activities on upper level conveyor belt declines and the loading loop on the 200m level. A handheld drilling crew advanced the 165 m level vent raise which will allow temporary ventilation for continuous blasting conditions down to the 470 m level.

Crews achieved the scheduled development metres during the period with cumulative cost per metre to the end of May c.15% under budget due to tight cost control and the operational efficiency of the company’s owner-operated mining fleet.

The company continues to be successful in recruiting experienced underground personnel. The total mine workforce now stands at 161 employees and underground development will move to three shift continuous operations in July 2013. Change houses sufficient to accommodate more than 300 employees at full-scale operations will soon be completed.

Excavation of a new 66 000 bank cubic metre (bcm) boxcut which will provide the surface entrance to the twin conveyor belt and services declines for the life of the mine is 75% complete. The boxcut is three weeks behind schedule due to encountering more competent ground earlier than expected which is slowing down the mining rate. This delay will have no impact on the overall development schedule as the activity is not on the critical path and the more competent ground is a positive with respect to mine portal stability. The boxcut development is 40% under budget on a bcm basis, as a result of owner-operated fleet efficiencies.

Mining fleet rebuild programme

Diamondcorp notes that a decision to develop a core competency in rebuilding in-house its heavy equipment mining fleet is already yielding results in terms of operating efficiencies. The first fleet of rebuilt underground trucks and loaders are providing better than 90% availability and operating significantly under budget with respect to diesel consumption.

In the past three months, a 9.5 ton underground loader, a 7.4 ton low profile underground loader and a 20 ton underground dump truck have been completely stripped and rebuilt in house on schedule and within budget. The company’s heavy equipment workshop is rebuilding these machines for between 25-50% of the price of new machines.

Two more loaders, two more 20 ton dump trucks and a single boom face drilling rig are next in line to be rebuilt.

Other activities

During the past quarter, the engineering, procurement, and construction management (EPCM) contract for the underground conveyor belt design, fabrication and installation was awarded. The design work is 100% complete and detailed drawings are now being generated and verified. Orders have been placed for the major imported belt and drive components, thereby fixing exchange rates.

Meanwhile, the company has taken delivery of a new Boart Longyear LM30 underground diamond drill rig and a programme of 2 000 m of underground core drilled is planned to be completed before the end of the year. This drilling will be undertaken from inside the kimberlite to better define margins of the bulge as well as the 47 level block cave area.

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