Modern Quarrying Q3 2019

construction material, mainly G products. They are mostly used to supplement production for project- specific contracts. As part of its compliance to the Proximity Detection System (PDS) legislation, Bridgetown Dolomite Mine is currently one of the test sites for Schauenburg’s surface PDS. It is currently running these systems on its dumpers, front- end loaders and LDVs, as well as pedestrian units. “Not every machine on site is installed at the moment because we are still a test site,” says Pretorius. “Out of this exercise, we will determine our level of risk, which will determine our level of compliance to the PDS legislation.” Safety and environmental management are key focus areas at Bridgetown Dolomite Mine. This is demonstrated by high scores in the 2018 Aspasa ISHE and Environmental audits. “We achieved 94,8% in our ISHE audit in 2018 and scored 97,88% in our Environmental audit, which is Showplace,” concludes Pretorius. l

quarry has industrial pumps in place to mitigate the risk. The quarry is a typical drilling and blasting operation. Drilling and blasting, outsourced to contractor Blasting and Excavating (B&E), is done once a month and blasts are kept fairly large at 60 000 tonnes of material on the ground. Four Bell articulated haulers (2 x B25D and 2 x B25E) are loaded by a Cat 340D excavator in the pit. A Cat 329D is used as a backup excavator, and is in most cases deployed with a hammer to break oversize material. From the pit, material is hauled to the main BDM plant where it is crushed into spec. Load and haul distances are fairly short and are currently around 1,2 km from the pit to the tipping point. Cycle times are, on average, about 8,5 minutes, depending on the point of loading. A total of five Cat 950 wheel loaders are used to stockpile and load customer trucks. They are also used to feed two Finlay 683 mobile screens operating on site. The two screens are used to produce road

to be installed in June. “We have already bought the compressor, air line systems and all the necessary components.” Further developments Apart from an array of technolog- ical developments, Bridgetown Dolomite Mine has recently com- pleted a life of mine development plan. “We had mining engineers on site in 2018 to determine the life of mine and quality of resource going forward. The material looks good and at this stage we are very pleased with what lies ahead. The critical part now is pit planning. Going deeper is always tricky because you need to plan your ramp designs accordingly,” says Pretorius. The life of mine development plan revealed that the quarry’s estimated life of mine is up to 2039. Issues of importance at this point are pit planning and water management. The quarry is located close to the Berg River. The pit is at this stage below river level, which poses a big risk of flooding. The