Murray & Roberts Cementation has begun work on a contract awarded by Sasol Mining to provide a men-and-material shaft and a ventilation shaft as well as a decline and coal seam development on the No 2 and No 4 seams at Sasol Mining’s greenfields Impumelelo mine project. The mine, located about 50 km from Secunda and 22 km from Greylingstad in Mpumalanga, is one of the biggest coal projects that Murray & Robert Cementation has been involved with to date. The shaft complex has been designed to operate for a minimum period of 35 years. Project duration is estimated at about 43 months, from May 2011 to November 2014, including site establishment and site de-establishment. Excavation on the men-and-material shaft, the ventilation shaft and the decline began in July 2011 and is well within the programme schedule.
RSV Enco-Goba Coal JV, comprising RSV Enco Consulting and Goba, is also project managing Sasol’s other greenfields mine complex projects, the nearby Thubelisha coal mine, which is being developed by Grinaker-LTA. Johann Prinsloo, senior project manager at Murray & Roberts Cementation, says that owing to the complexity of the project and in order to deliver a professional product, it was decided that Concor Civils, a Murray & Roberts Construction company, will undertake the civil construction of both shafts collars and the decline box cut, as well as portal construction with the closure of the box cut. Concor Civils will also carry out all other civil works for the site establishment.
The 11.7 m diameter men-and-material shaft will be 240 m deep, with a four sided station on No 4 seam and a three sided station on No 2 seam being developed for access to the coal production sections that will be mined by Sasol using mechanised mining methods. The shaft will be fully lined and equipped as a service shaft with buntons and guides. Murray & Robert Cementation will also erect the permanent steel structure headgear frame, conducting the installation in two phases. Headgear structure erected during the first phase will be used for the sinking operation and the permanent arrangement will be erected during the second phase. Lifting of pre-erected headgear sections will be carried out by a 750 t crawler crane. The shaft will be serviced by a 65 t payload cage and counterweight by means of a Koepe winder, which will allow Sasol Mining to lower its continuous mining equipment into the underground workings. During the sinking process a single drum 12 t kibble winder will be used for lowering and hoisting personnel and material up and down the shaft, while a stage winder will be used to lower and raise the four-deck working stage. A five-boom drill jumbo will drill the shaft and shaft cleaning will be carried out by means of an excavator into the kibble.
The 6.7 m diameter ventilation shaft will also be sunk to 240 m, with access through the four sided station on No 4 seam and the three sided station on No 2 seam to the coal production sections. During the sinking process, a double drum 8 t kibble winder will be used for moving personnel and material up and down the shaft and a stage winder will be used for lowering and raising the five-deck working stage. A temporary steel structure headgear frame will be erected for the sinking phase of this shaft. During pre-sinking of the ventilation shaft, a Scott derrick will be used to hoist material. Shaft drilling will be carried out using a four-boom drill jumbo and shaft cleaning will be undertaken with a cactus grab unit into the kibble. After sinking is completed, a permanent ventilation fan will be installed to service the mine.
