First Blast Signals Start of Shaft Sinking Phase at WESIZWE's Bakubung Platinum Mine
26 April 2011
TWP’s involvement with Wesizwe spans back to 2006 when it conducted the prefeasibility study. A full Bankable Feasibility Study (BFS), which was started in February 2007 and completed in June 2008, indicated the Bakubung Platinum Mine (formerly known as Frischgewaagd-Ledig) has the resources to sustain a 35 year life-of-mine (LOM), with a total PGM production of 330 000 oz per annum. TWP is currently wrapping up the first phase of the EPCM project scope which entailed access routes, fencing, the Eskom terrace, the Phase 1 pollution control dam, the Main and Ventilation Shafts terraces (excavating the box-cuts on both shafts), surface drainage and the environmental berm as well as earthworks.
“The first blast represents a momentous milestone for Wesizwe,” says Wesizwe CEO, Mr Arthur Mashiatshidi. “It is not common for exploration companies to take a project of this magnitude from exploration to production. Usually a mining major will take over the production after the exploration phase is concluded. In the case of Frischgewaagd-Ledig, Wesizwe will develop it into an operating mine, and the first blast signals the start of the long-awaited execution phase.”
Attended by executive representatives from Wesizwe, TWP and Scribante Construction, the first blast to establish the box cuts of the Main and Ventilation Shafts took place on 5 April 2011. BENCO Engineering conducted the blasting using underground emulsion charging units to open the ground. 460 detonators were positioned at a depth of 10m at the Main Shaft, and 135 detonators in 6m holes at the Ventilation Shaft. The two blocks were electronically detonated at the same time. Blast monitoring was conducted by Blast Management & Consulting with readings taken as the blasts were set off to measure the strength of any shock wave transmission from the point of detonation to the nearby houses and structures. This was to ensure that data was captured accurately to confirm the blast performance, aimed at minimal or no damage to any structure outside the blasting circle, as determined by the blasting specialists.
“The next step is to begin with civil works – collaring on the box cuts to stabilise the top 10m on the shafts, before the start of the pre-sink activities in nine months’ time,” says TWP project manager Jacob Mothomogolo. “The sinking will be one of the largest ticket items of the project, with an estimated 17-18% of the total capital allocated to it. The presink or slow sink on the shafts will be developed at a rate of 0,5m a day for up to six months, until a depth of about 80m is reached. At that time, we will switch over to a permanent set-up, including the installing of sinking winders, sinking headgears and establishing a power connection with Eskom. The sinking of both the Main Shaft and the Ventilation Shaft will be conducted simultaneously, with the former reaching a depth of 1 140m, and the latter a depth of 980m. The shafts will be 120m apart and will interconnect at certain levels,” says Mothomogolo.
The sinking phase, including equipping and commissioning of shafts, is expected to be completed within 62 months, at which time production build-up will begin and the capital footprint established. This will involve infrastructure development, tunnels, ore passes and any other excavation necessary to open up the resource block. The build-up period will also see TWP preparing for client handover with the establishment of a full mining operations team and personnel, and skills transfer by contractors to the permanent mine workforce. The mine will require approximately 3 200 people at full production. With the mine located in an established mining region, a skills survey indicated that there is currently a requirement to train local employment seekers if the mine is to meet its SLP commitment to sourcing most of its employees from the host and surrounding communities. Certain specialist skills may have to be brought it from the active mining sector outside the region.
It is expected that the mine will reach steady state production of 230 000 tonnes of ore per month (180 000 tonnes of Merensky reef / 50 000 tonnes UG2 reef) within four to five years’ time from start of build-up period.