JOHANNESBURG (miningweekly.com) – TSX- and JSE-listed Rockwell Diamonds has recently reached a number of milestones as it continues with its medium-term strategy to increase alluvial production volumes in the Middle Orange River region to 500 000 m3 a month.

“We have developed two new, internally funded mines, demonstrating our capability to bring new production capacity on line by making use of fit-for-purpose technology that is suited to each deposit’s specific geology and by chiefly reusing existing assets.

“These will bring our average monthly production volumes in the Middle Orange River region to 360 000 m3, putting us on track towards our medium-term target and also leading to improved quarterly earnings,” president and CEO James Campbell said in a statement to shareholders on Thursday.

Rockwell spent $3.6-million of its own money on the construction of the Saxendrift Hill Complex, which was now in production, and the Niewejaarskraal operation, which was ramping up to production.

The diamond miner pointed out that the Saxendrift Hill Complex mine was now running at close to nameplate capacity.

Further, as part of its volume growth strategy, the company has commissioned two Bourevestnik X-ray bulk sorters and two single particle sorters with a 100 000 m3 a month processing capacity, at the Saxendrift Hill Complex operation.

Rockwell explained that, to more fully evaluate the effectiveness of the Bulk X-ray technology, compared with traditional dense media separation (DMS) and pan plants, gravels from the Saxendrift Extension project were processed in parallel through the bulk X-ray system, as well as the Saxendrift mines's traditional pan plant in July.

“We are delighted with these results, which showed a 40% increase in grade when we processed Saxendrift Extension gravels in parallel through the Bulk X-ray and the pan plant system at Saxendrift during July,” noted Campbell.

This also led to the recovery of two rough diamonds larger than 30 ct.

The diamond producer expects the new Saxendrift Hill Complex plant to have 30% lower unit processing costs than the pan plant, providing further commercial benefits.

The bulk X-ray plant also has a lower environmental footprint with lower water consumption and power requirements than the traditional processing plants.

Meanwhile, at Niewejaarskraal, the commissioning of the first phase of the new DMS processing plant had gotten under way in July, within ten weeks of the project being approved.

The first diamonds, which included two rough diamonds larger than 20 ct, have been recovered.

Rockwell noted that high diamond values have compensated for slightly lower-than-anticipated grades for the initial gravels that have been processed during commissioning, owing to a greater variability in the Rooikoppie particle size distribution than was outlined in the previous operators' sampling reports.

However, plant efficiency has been confirmed through reprocessing the plant tailings through the bulk X-ray system, with no diamonds being recovered.

The next phase of commissioning, which started in the third week of August, entails processing a mix of Palaeo and Rooikoppie gravels.

Campbell said Rockwell would consider upgrading the Niewejaarskraal plant to use the same bulk X-ray technology that was implemented at the Saxendrift Hill Complex in future.

The long lead times in implementing the technology at the Saxendrift Hill Complex had prevented the company from considering it for the first phase of the Niewejaarskraal plant.

Future growth plans for the company would include further increasing the production capacity at Niewejaarskraal, as well as potential growth options for the company’s Wouterspan operation.