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Blasting is a critical process at most hard-rock mines that affects almost every other stage of the operation but the detailed dynamics are not well understood. One reason for this is the difficulty of measurement and this lack of data has lead to myths and conflicting theories.
The University of Queensland developed an electronic blast movement monitor primarily as a grade control tool but it quickly became apparent that its accuracy and ease of data collection presented an opportunity to quantify 3-dimensional blast movement and therefore extend the understanding of blast movement dynamics.

Blasting is a critical process at most hard-rock mines that affects almost every other stage of the operation but the detailed dynamics are not well understood. One reason for this is the difficulty of measurement and this lack of data has lead to myths and conflicting theories. The University of Queensland developed an electronic blast movement monitor primarily as a grade control tool but it quickly became apparent that its accuracy and ease of data collection presented an opportunity to quantify 3-dimensional blast movement and therefore extend the understanding of blast movement dynamics.

This paper summarises six years of research by quantifying relationships and describing blast movement dynamics. For example, it examines the movement dynamics in all regions of the pattern including the confined and unconfined front edges; formation of the power trough; movement around initiation centrelines; and muckpile swell. The profile in most areas of the muckpile is D-shaped, with the maximum horizontal displacement occurring in the mid-elevation of the bench, but a notable exception is the power trough, where the lower part of the bench moves forward and the upper part of the bench drops down into the void. Superior knowledge of blast dynamics can be applied to improve blast designs.

The paper compares free-faced and buffered blasts, demonstrates that bench height has negligible effect on movement and why echelon initiation is preferred for optimal grade control. Finally, blast movement monitoring has been used to scrutinise design aspects such as sub-drill, electronic delay detonators, explosive performance and pattern geometry.

Published in 9th International Symposium on Rock Fragmentation by Blasting, September 13-17, 2009 Granada (Spain)

Read the full paper.