Developing a concept that can be used to quantify the motion of flyrock, with the intention of eventually producing a measuring tool for future flyrock research.

Abstract

Flyrock remains a significant risk to the health and safety of the mine’s employees and infrastructure as well as the safety of the neighbouring communities and their property. Losses and damages can result in significant financial and reputation consequences. The lack of fundamental research in recent years and quantifiable data relating to the relationship between blast design parameters and the risk of flyrock motivated this project. A number of authors concluded that major gaps in knowledge relative to flyrock caused by its random nature still remain a weakness in the field.

Recent papers published (since 2010) proposed a wide range of potential approaches and techniques to predict or investigate flyrock. However, the majority of these papers concluded that the proposed results were site-specific and could not be applied to other environments.

The focus of this project was to develop a concept that is able to quantify the flight path of the flyrock resulting from a blast. The motivation behind the development of this concept was to enable future researchers to quantify the impact of the different blast design parameters on the measured flyrock.

Various technologies were considered and investigated during this project. After a comparative analysis of these technologies, it was decided to use photogrammetry as the foundation of the proposed concept tool. The proposed concept consists of three main phases, namely (1) data acquisition, (2) image processing and data analysis and (3) data interpretation.

To date, progress has been achieved with phase one and phase two. In phase one, all objectives have been met. However, there are still areas which need refinement, specifically regarding the placement of the cameras in the field. In phase two, success was achieved with the proof of concept exercise in a controlled environment using a clay pigeon as the projectile. The process of calibrating the lenses has been established, however, further optimization is possible. Point-cloud data was successfully generated in the concept test, but converting the image data from subsequent quarry test blasts proved more challenging and is still a work in progress. Once phase two has been satisfactorily resolved, attention will focus on phase three.

Results to date have given a positive indication that the concept is viable and that additional work will prove the technology functional. Ultimately, it is envisioned that this tool can be used for one of three purposes, namely: • Mines can generate a database with accurate historical flyrock of their blasting operations. • Research teams can implement this tool to conduct quantitative research and investigations into flyrock and the impact of different blast design parameters on the risk of flyrock. • Point-cloud data combined with ballistics calculations can be used to visualise blasts and flyrock in Virtual Reality for training and education.