FLYROCK IN SURFACE MINING - LIMITATIONS OF CURRENT PREDICTIVE MODELS AND A BETTER ALTERNATIVE THROUGH MODELLING THE AERODYNAMICS OF FLYROCK TRAJECTORY
DOI:
https://doi.org/10.17159/Abstract
Flyrock analyses based on correlation and regression studies, including artificial neural networking and similar techniques, are inherently incapable of addressing two core issues—root causes of flyrock and the projection velocity—and give no information on the influence of rock size and its shape. The scaled depth of burial model does not specifically address the question of flyrock velocity. Flight trajectory calculations often neglect the effects of air resistance. Lundborg et al. 1975 and McKenzie 2009 models incorporate air resistance but use an implausible fragment velocity model.
It is shown that trajectory calculation with air drag affords the most promising approach to the prediction of flyrock range. Even without a generally applicable velocity model, trajectory calculations deliver credible answers to many questions in a number of important areas of flyrock analysis. Two worked examples are given to illustrate the potential of trajectory calculations.
A unique feature of the proposed trajectory model is that it collapses all suspected causes of flyrock, many of which are not well understood, to just a single parameter−the launch velocity. This indicates that the root causes of flyrock lie in the mechanisms of momentum transfer to broken rock and suggests new avenues of study.
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