There are now new ways to calculate risk zones more effectively, especially with regard to mitigating the possibility and severity of flyrock, says Simon Tose, group consulting mining engineer at AEL Mining Services (AEL).
These include the AEL Mitigating Flyrock Risk Field Guide, which is validated internationally, as well as face and blast-hole profiling. Then there is the research carried out by Richards and Moore in terms of a semi-empirical approach to flyrock range prediction.
This encompasses a methodology for quantification of flyrock distances relative to explosive confinement conditions, throw and safety, calibrated for each blast site.
Blasting teams must follow the correct procedures in order to mitigate the possibility and severity of flyrock, says Tose. Wild flyrock has historically been a major problem in the mining industry, resulting in the injury of mineworkers who are caught in the blasting process.
However, the reality is that the risk of flyrock can be reduced greatly by using new techniques and improving the attitude of those involved in the blasting process.
Planned blast zone
“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. This can result in damage to property, as well as injuring people on the blast site and in the vicinity,” says Tose.
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.
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,” explains Tose.
However, it is unknown just how far flyrock can be thrown. Hence the term ‘wild flyrock’, which is a significant problem if managed incorrectly. 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. 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,” argues Tose.
“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.
“However, 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.