Cooperation between Concor Mining and Impala Platinum has facilitated the Impala Opencast project.
Hans Baasden, general manager Impala Platinum says that Concor Mining was originally selected through an open tender process in 2002. “Impala Platinum is an underground mining company and does not have the necessary expertise or the resources to undertake an opencast mining project, hence the decision to go the outsourcing route.”
Concor Mining began work on the Impala opencast mining project in 2002 in the vicinity of Impala No. 6 shaft. “We mined the Merenksy ore body first and in 2005 we started mining the UG2 orebody,” Rodger Herne, Concor Mining contracts director responsible for this project says. “In a two shift operation, we mine down to the 30 metre level in the pit, while the Impala underground operation mines lower down from their shaft systems.”
“Since we started the contract we have had no fatalities and our LTIFR (lost time injury frequency rate per million man-hour worked) is only 0.24,” Herne says. He explains that from the start of the contract until the end of November 2007 the company had achieved two million fatality free shifts. “This may seem like a long time to achieve this, but there are far fewer employees on an opencast mining site when compared to underground shaft operations.”
“All in all, we have 240 people on the site which spans an area of 15 km. These include a site manager; three junior site managers; six foremen each with two junior foremen; four reefing foremen who are responsible for the extraction of the ore which is essential to ensure the reef is extracted at the correct width and quality.”
Hand-in-glove with skilled and qualified personnel are the production focused items of plant. “We have five bulk excavators for overburden removal; six smaller excavators for cleaning the ore body and extraction of the ore body; five dozers for moving overburden and top soil; 25 trucks on site; three water carts and various ancillary support plant. A static jaw crusher services the southern pits on the contract while a mobile jaw crusher services the northern pits,” Herne says.
At the moment the company is working out of two Merensky pits and seven UG2 pits. “We use the strip mining method for mining our pits and our advances are normally 30 metres wide. We are also responsible for the complete drilling and blasting operation in all our pits. The orebody is exposed, extracted and transported to the rail siding five kilometres away where it is crushed and transported by rail to the plant for further processing,” Herne says.
“We have to be aware at all times not to hole through to the underground workings. For this we depend on surveys conducted 30 years ago and we work closely together with the mine’s surveyor to ensure that highwall positions are correct.”
Blasting on the surface is more involved than the blasting practiced underground. In some instances blasting occurs some 200 metres away from the process plant and this means it is essential to have the necessary expertise and experience to be able to control the blasting process and keep vibrations down to a minimum.
“Due to the infrastructure that is so close to opencast pits, emphasis is put on the blasting to ensure that we stay within the set blasting limits for vibration and air blast. Blasting occurs only twice a week because of our commitment to consider the local communities,” Herne says.
The lifespan of the opencast mine will extend to 2011 by which time both reef horizons will have been extracted.