Modern Mining November 2016

COVER STORY

a ventilation fan installation at Nchwaning III shaft. The 460 kW centrifugal fan was installed adjacent to the existing three fans. The change-over of the surface fan intake from the trifurcated inlet to a quadfurcated inlet was successfully accomplished and the existing fans returned to service as planned. At Nchwaning II, the vertical shaft upgrade has comprised refurbishment of the exist- ing shaft steelwork, installation of new shaft loading facilities and the replacement of the existing 8-ton skips with new 14-ton skips. A refurbished rock winder has also been installed adjacent to the existing winder while the exist- ing man winder was also upgraded. Also required have been headgear and sheave altera- tions to suit the new ropes, larger skips and winder placement. All design work pre-construction and engi- neering support during the shaft upgrade was done by WorleyParsons, with Assmang taking direct charge of construction activities under Hennie Wessels from Assmang. The Gloria shaft stripping and second escape package, together with the Nchwaning II head- gear and shaft upgrade, were combined and Group Five was awarded the contract in April 2015. Stefanutti Stocks Civils was contracted to construct the winder house and Winder Controls installed the winder. Refurbishment of the Vecor rock winder (to be used at Nchwaning ll shaft) was com- pleted in June 2015 and the winder house in August 2015. A portion of the refurbishment of the shaft steel work was carried out over weekends so as not to interrupt mining activities. The major work, which includes the replacement of the loading boxes, sheave deck and all rock winder guides, took place during a planned shut period starting in March 2016. The lifting of the 57-ton sheave deck took place on 22 September 2016 using a 550‑ton crane. All sheaves and related equipment have been installed and aligned and roping up was underway as this article was being written. Commissioning, testing and licensing of both winders and shaft systems will commence dur- ing October and November 2016. Considerable development work, of course, forms part of the overall project. BRMO is undertaking all the development and associ- ated support work required at Nchwaning I and III shafts ‘in house’ and is being assisted by WorleyParsons, which is responsible for the design, procurement and management of the construction work. At Nchwaning II shaft, the development has been contracted out to Aveng

Mining, which was due to complete its contract during October 2016. The development contract has included: all satellite tips consisting of silos, tips, load- ing facilities, top and bottom conveyors and ramps between Seam 1 and Seam 2 reef planes at Nchwaning II shaft; all transfer points; con- veyor drives to Nchwaning I and II shafts; the TMM workshop; and all crusher chambers. Summing up WorleyParsons RSA’s involve- ment in the BRP, Greyling says it demonstrates the company’s abilities in virtually every facet of underground mine construction and development. “The Johannesburg office of WorleyParsons RSA houses much of the mining and shaft sinking expertise of the international WorleyParsons group and in fact is the group’s Global Centre for Excellence for precious metals processing and underground mine development,” he says. “All our skills have been deployed at Black Rock and have contrib- uted to what has been an extremely successful project thus far.”  Photos: Charles Corbett on behalf of Assmang

Top: The 11 m high graben tie-in structure.

Above: Conveyor in progress from graben tie-in to shaft system.

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