[miningmx.com] — JSE and Toronto-listed diamond miner Rockwell Diamonds has accelerated a number of projects to enhance the recovery of diamonds on existing operations as well as at the Tirisano project in South Africa, currently under development.
The company said on Tuesday that following on from the strategic review which was conducted at the beginning of the 2011 calendar year, it is taking further decisive action to improve the recovery of diamonds and turn its underperforming assets around.
Rockwell has three existing operations, two development projects and a pipeline of earlier stage properties with future development potential.
James Campbell, the newly appointed CEO and President of Rockwell who officially took office on June 1, explained: “Two factors crucial to successfully mining alluvial diamonds are the management of the geology and the metallurgical processes. We have invested significant time and effort in fully understanding our resources and the results have been confirmed by our independent qualified person.
“The grades and diamond values in our NI 43-101 reports are supported by actual production data and sales prices in addition to sample estimates. This conservative approach gives us comfort that they are currently accurate as we implement improved concentration and recovery technology to translate the resource into efficient extraction.”
A review of the Saxendrift processing plant uncovered opportunities to considerably improve front end processing efficiencies. Based on these findings, the Board has approved the replacement of the current vibrating screen at the in-field screening plant with a 3.0m x 8.0m DabmarBivitec screen, which is fit-for-purpose technology designed to process wet and sticky ores at the required processing rates. The capital cost for the replacement screen will be $600 000.
“A diamond size frequency analysis of Saxendrift’s production also showed that by increasing the recovery cut off from the current 2.5mm to 5mm, we could significantly improve plant efficiency,” said Campbell.
“In addition to improving the plant throughput, productivity gains could be realized by processing less fine materials and lowering overall waste volumes.”
There is a focus on maximising the stones exceeding 10mm in size and minimising the costs associated with processing volumes of material that may provide little reward or even negative returns.
At the Tirisano project, Paradigm Project Management, a mine project management consulting firm with experience of constructing more than 100 diamond processing plants, has completed a plant review. Their report highlighted improvements to ensure that Tirisano delivers the anticipated grades after commissioning.
The mine management team has also been changed and strengthened to ensure the effective implementation of the review recommendations and consequently the commissioning work schedule has been modified to accommodate the changes. The first two streams of the processing plant will be commissioned during the course of the third quarter of calendar 2011.
A review of the flow diagrams is underway by the company’s metallurgists to incorporate the latest recovery technologies and thereafter construction will resume on the remaining two streams, it said.
