Key to the reliability of the system is the closed emulsion system used to supply emulsion to the portable charging unit. Using sealed bags ensures no contamination of the emulsion by dirt or rock, eliminating the possibility of pump failure as a result of foreign materials entering the pump. Emulsion is supplied to the mine in bulk, before being transported underground through the use of emulsion cassettes or pipelines where it is pumped into emulsion bags before being transported to the blastface.Among the technological advancements required in the migration of emulsion systems from mechanised operations to the narrow stope environment has been considerable improvement in the efficiency of the new emulsion pump technology. “Due to energy constraints often experienced in the underground environment, we have developed the units to operate on the low levels of compressed air available,” he said. “We have also adapted the product for mines that run on hydro-power systems.” A key element in the success of BME’s portable pump is the company’s highly stable range of Megapump emulsions, which are able to be re-pumped multiple times without any signs of deterioration. Due to the stability of the formulations, Megapump emulsion also has a long ‘shelf life’ – even once it is pumped and stored in emulsion bags ready for use at the stope face. Unlike Class 1 explosives like Anfo and cartridges, emulsion blasting agents are classified as a class 5.1 oxidiser and as a result they are not subject to the same legal requirements of class 1 explosives. Due to their increased level of safety and explosive free classification emulsions can be transported and stored in larger quantities and with greater flexibility allowing for greater time-savings, simplified logistics systems and increased productivity. Advantages of pumpable emulsions include increased coupling and efficiency within with in the blast, and good water resistance that eliminates the possibility of failed blasts when water remains within the blasthole following drilling activities. “An added advantage of emulsion is that, unlike Anfo, it is water resistant – so it can be pumped into wet blastholes without a problem,” said Pearton. “This further speeds up the charging process underground as emulsion will simply displace any water in the hole.”
BME has successfully conducting a number of working trials with their portable emulsion system to be used in narrow-stope underground mines. BME, a supplier of explosives to the South African open pit mining and quarrying industry, has adapted the principles of traditional mechanised charging equipment from large scale operations – creating a portable charging unit that is light-weight, robust and easy to operate. This has taken the company taken another step in delivering emulsion-based blasting solutions to narrow-stope underground mines. “We believe that emulsions are the future of underground mining,” said BME manager, research and development Selwyn Pearton. “We have developed a narrow reef emulsions pump that can dependably deliver the advantages of emulsions to confined, labour-intensive working environments.” The portable pump weighs just 13kg, so that it is easily carried by miners to and from confined mining stopes. When in use, two 20kg emulsion bags are fitted to the pump, sufficient emulsion to fill as many as 60 blast holes before being simply replaced to allow charging to continue. “The particular conditions of South Africa’s underground mines have guided the design of this unit,” said Pearton. “While existing emulsion charging equipment usually requires two skilled operators to function, the large number of units required with the narrow stope environment and the limitations on the level of skills within the workforce dictate the need for a new approach to emulsion technology.” For this reason the user interface has been simplified so that a single operator need only connect the necessary emulsion and sensitiser bags before activating the trigger on the charging lance to activate the pump. “The design of the system ensures the required mass and quality output is achieved for the specified blasting application,” he said.