Simon Tose, Group Consulting Mining Engineer at AEL Mining Services (AEL), says blasting teams must follow the correct procedures in order to mitigate the possibility and severity of flyrock. "Any type of surface blasting breaks up rock, which is then propelled into the planned blast zone. Sometimes this rock is thrown further away than expected, which is referred to as wild flyrock and can result in damage to property as well as injuring people on the blast site and in nearby homes."
According to statistics published by the Office of Mine Safety and Health Research (OMSHR) in the US, between 1994 and 2005, 68 miners were injured because they were in the blast area during a blast and 32 miners were injured by flyrock.
Tose notes that the risk zone where rock can be expected to be thrown is known as the blast zone. "There is an exclusion zone that blasters will determine can be expected to have flyrock propelled into; but it is unknown just how far flyrock can be thrown, wild flyrock, making this a significant problem if it is not managed correctly."
"Currently, the safety zone within a blasting area is determined by algorithms, in order to assess the most likely blasting result. However, things can still go wrong, depending on the movement of the rock, so it is important to calculate risk zones as accurately as possible," he says.
Tose notes that AEL uses advanced blast design techniques in order to ensure that any risk of flyrock and other incidents is greatly reduced. "It is critical for blasting and mining services companies to adopt international best practice standards in order to be more proactive in controlling flyrock and limiting the number of blasting accidents; and there are now new ways to calculate risk zones more effectively such as AEL Mitigating Flyrock Risk Field Guide, validated internationally, face and blasthole profiling and the research work by Richards and Moore - a semi-empirical approach to flyrock range prediction with a methodology for quantification of flyrock distances relative to explosive confinement conditions, throw and safety, calibrated for each blast site.
"By managing explosions more effectively, it is possible to ensure a good control blast and to secure the blast area correctly. The mining industry has made great strides forward in reducing the number of workplace accidents but it is essential that companies keep up-to-date with innovative, new developments to ensure any risk is proactively mitigated as far as possible," concludes Tose.
