ANALYSIS OF DRILL HOLE DEVIATION AT MT ISA COPER MINE AND ITS EFFECTS ON BLASTING PERFORMANCE Robert Edward Gelson The following thesis presents the findings from a research project conducted at Mt Isa Copper Mine, Queensland, Australia, in particular at the deep mining operation called Enterprise. The study investigated the drilling inaccuracy or deviation at the 3000 orebody and its resultant effects on blasting performance in relation to overbreak, underbreak and cost effectiveness. It was instigated due to large unexplainable ore losses and large dilution factors associated with the resultant blasted stopes in the 3000 orebody. The hand’s on study involved measuring the drilling accuracy of the P637 stope production rings, as these are responsible for blasting the majority of material and creating the stope perimeter. This data was collected in the field with the use of borehole surveying equipment. A blast modelling program called 2D Bench (which is part of the JKSimBlast software) was utilised to examine the disturbance in the spatial distribution of explosives as a result of drill hole deviation. The volumes of overbreak and underbreak were also calculated by importing stope Optech information into a 3D modelling program called Rhinoceros 4.0. An analysis was then made by comparing the results from each blasted section to deduce the effects of drilling inaccuracies to the overall final blasted volume. Three major blasts were investigated from one stope, P637. The blasts were characterised as individual regions having distinct pull volumes all with independent results from each other. The study was limited to three sections of stope P637 due to major time constraints in which to complete the down-hole surveys and acquire the blasting results. Stope P637 was chosen for investigation due to its favourability with the production schedule. The major results from the investigation were: • The overall drilling accuracy of the blast holes was poor with an average deviation of 7.2%, expressed as a percentage of the total length. • Blasting performance was greatly reduced when the borehole deviation was all in the same directional plane. • Multiple drill rings cause a cumulative effect of blast energy therefore, reducing the problems associated with drilling inaccuracy. • Less rings in a blast reduces the cumulative effect of blast energy therefore, a higher degree of drilling accuracy is required in small blasts to achieve satisfactory results. • Explosive energy distributions indicate that a reduced explosives quantity could be used in larger multiple ring blasts – a potential cost saving to the mine. • Total ore losses from the examined blasts on their own, equated to a loss of approximately $3.524 million in revenue, due to underbreak/lost ore. • Inefficient blasting also increases costs due to higher amounts of explosives being used, to counter (if possible) the drilling inaccuracies.