JOHANNESBURG (miningweekly.com) – JSE- and TSX-listed Rockwell Diamonds has exceeded its production target from its three operating mines in South Africa and is now operating at a break-even point, president and CEO John Bristow said on Monday.

Between June and September, the mines produces more than 2 500 ct/m as a result of operational and structural changes, which Rockwell implemented in early 2009, when the global economic crisis led to a sharp drop in rough diamond prices.

Rocwell placed its Wouterspan operation on care-and-maintenance in February, reduced its employee complement by a total of 180 personnel, and implemented initiatives to increase production and reduce operating costs.

These initiatives included a review of all contracts and out-sourcing arrangements, further refinement of mine plans, stringent grade control, smarter earth moving procedures, re-engineering initiatives to improve production throughput at Saxendrift, Holpan and Klipdam, and rigorous planned maintenance and repair programmes at all processing and recovery plants.

“In spite of the world economic recession, precipitous decline in diamond prices, and costly unforeseen corporate activity, Rockwell has demonstrated its ability to rapidly adapt to these challenges,” Bristow said.

He added that the diamond miner was “well placed” to return to profit.

Initiatives implemented to improve plant throughput and diamond recoveries had shown systematic benefit at all operations, Rockwell reported.

The Saxendrift mine had met profile expectations with regular recovery of large stones, including the most recent recoveries of stones of 122ct, 120ct, and 105ct in late September and early October 2009.

The Saxendrift operation’s Rotary pan plant underwent precommissioning in October and subsequent commissioning between February and April. It had now achieved budgeted throughput of about 200 000 t/m from the first phase of plant commissioning and operation. Re-engineering and enhancement of this plant was ongoing to further improve throughput and lower operating costs in phase two of the planned plant ramp-up.

Mining and operating cash costs achieved at Saxendrift have been lower than originally budgeted, while recovered grades have been in line with estimated grades.

Rockwell also reported that the Klipdam mine had continued to meet production targets on a regular basis and remained the flagship operation. Operating cash costs were below $3/t and ongoing refinements to material handling and efficient scheduling of mining and rehabilitation schedules would likely result in further improvements, the company stated.

Since March, considerable effort had been devoted to re-engineering of the Holpan dense media separation (DMS).

A programme, which has included replacing cyclones in each of the four 50 t/h cyclone units, improving vibrating screens and water jet flow for the recovery of ferrous silicon used to control the density medium, swapping out old de-sanding units with two new modified dewatering units to improve water reticulation and save costs, had led to an overall 65% increase in the throughput of the plant and concomitant lowering of costs.

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