The Ngezi opencast operation has reached full production and plans are under way to establish a $110-million to $140-million mechanised underground mine, which will double production to 400 000 oz a year by the end of 2005.
Mining Weekly reports Zimplats chief executive officer Roy Pitchford as saying that, notwithstanding the success of its opencast mining, the majority of Zimplats resources are not accessible by opencast mining methods.
The company, therefore, began trial underground mining from the foot of one of the Ngezi Platinum Mine open-pit high walls in September, 2002. A mined-out section of the open-pit has been backfilled to provide an access ramp to the foot of the high wall. The trial mine is being mechanised in April 2003 as part of the
feasibility study. This will consist of low-profile drillrig, roof-bolters, LHDs
and a conveyor system.
Using information obtained from the underground trial mine Zimplats has updated its resources into reserves and reports an additional reserve for the Ngezi area of 284-million tons containing 31-million ounces 4E (platinum, palladium, gold and
rhodium).
The average grade is 1,65g/t platinum and 1,36 g/t palladium. This is at an average mining width of two metres and an average depth of 250 metres. Limited drilling is needed to add an estimated 30-million to 50-million extra tons from areas drilled only to inferred category of resource.
A $2-million bankable feasibility study for the first-phase expansion, which will include financing requirements, is in progress and scheduled for completion in the last quarter of this year.
In the first-phase expansion two-million tons a year (Mt/y) of ore will be produced from underground mechanised room-and-pillar mines (two portals, nominal 1 Mt/y each).
Production will be 200 000 oz 4E a year contained in matte. This first phase will be on stream and ramping up to full production during 2005. – Sapa