Latest development is the completion of the mine’s new carbonin- pulp (CIP) plant. Built at a cost of R58 million, the new plant was scheduled for completion in October 2007, and commissioning of the new circuit is now underway.
It is anticipated that this replacement of the old filter plant and zinc precipitation circuit, and upgrading and expansion of the metallurgical plant, will achieve three main objectives:It will reduce plant treatment costs per tonne by 25% from R52 p/t to R39 p/t; it will increase plant throughput capacity by 21 % to 170 000 tonnes per month; and it will increase gold recoveries by 3% from 93 to 96%.
The new CIP plant’s additional throughput capacity will be used to treat low-grade surface waste rock dumps. It will allow economic processing by Buffelsfontein of low-grade dumps that were previously untreatable through the old filter plant because of the fineness of the ore in these dumps.
The mine has a total compliant surface resource of 18.5 million tonnes grading at 0.52 g/t.
OTHER PLANTS MAY BE RE-COMMISSIONED
BGM has also commenced a feasibility study to consider the re-commissioning of the190 000 tonne per month North Gold plant and the 120 000 tonne per month gold flotation plant adjacent to the new CIP plant. Initial flotation test work has indicated that 67 % of the gold can be recovered from 12 % of the mass pull in the float plant, thus upgrading the mill feed from 0.52 g/t to a CIP feed grade of 3.0 g/t.
Previously the mine successfully operated the flotation plant, which was mothballed during 2003 due to the depletion of compatible surface sources which could be recovered through the filter plant. Should the feasibility study prove successful, this could result in a significant increase in gold production from surface sources. It is expected to be completed in the December 2007 quarter.
Despite the fact that total gold production is expected to increase in the December 2007 quarter, gold sold, as well as unit cash cost per kilogram, will be negatively impacted by an estimated lock-up of gold in the new CIP circuit of 160 kilograms. This will be partially offset by the recovery of gold from the clean-up of the redundant zinc precipitation circuit and old smelt house building which will commence during the December 2007 quarter.
“I am delighted that our project team has successfully completed this project, which will assist in improving safety, reducing operating costs and improving gold recoveries,” says Simmers chief executive officer Gordon Miller. “The decision to invest significant capital at BGM to improve efficiencies will pay dividends in the long term, and we look forward to extracting value from previously unavailable gold resources by using the inherent benefits of this state-of-the-art gold plant,” he adds.
TWO OTHER PROJECTS
In September Simmers announced that – in conjunction with First Uranium Corporation – it had commissioned an initial technical assessment to investigate the deepening of Buffelsfontein’s Strathmore Shaft, a project which has the potential to boost the mine’s proven and probable gold resources by as much as 50%.
The intention – as reported in MRA Issue 5 of 2007 – is to reveal the findings by the end of 2007, and to commence a further feasibility study which would be completed towards the end of 2008, after which a decision to mine will be made.
In our Issue 4 of 2007 earlier in the year, Mining Review Africa also covered the Simmers announcement of the re-opening of the high-grade Number Five Shaft at Buffelsfontein at a cost of R170 million. This shaft is scheduled to be back in production by the first quarter of 2008.
The re-opening of Five Shaft will result in a 5% increase in the overall life-of-mine grade; an improvement in peak production forecast to 318 000 ounces by 2014/15; and a 12.5% increase in total life of mine ounces from 4.5 million to 5.1 million.