The Safe Working Practice of Changing Out a Raisebore Reaming Head Underground Eloise Copper Mine

Overview of Operation Eloise Mine Site. Underground Operation – mining ~ 500,000t/annum – 70,000t/annum Cu Con. Currently 570m underground. Main Orebodies – Levuka and Elrose. Levuka South – offset by main faulting structure. Necessary to install new ventilation shaft to supply adequate ventilation to this area.

Overview of Ventilation Shaft Ventilation shaft established through collaboration of the following contractors. –Major Pontil. –Raisebore Australia. –Townsville engineering. –Jetcrete. –EROC (formally Peabody mining services). –Piling contractors. –Nortask. –Australian mining consultants (AMC). –Hard rock electrical. –Supervision and design Amalg resources.

Development of Ventilation Shaft Begun 20 th July Major Pontil – 482.5m directional hole accurate within 0.35m Hole reamed to accommodate RBA drill string RBA back reamed 3.5m diameter shaft up to the cretaceous sediments (overburden) Lower rods – will expand upon this step Changed to 660mm diameter head – reamed to surface Piling contractors and Jetcrete worked together to bore and line the remaining 57m to a diameter of 3.0m Installation of the southern ventilation fan As a note increased the quanity of air from 82m 3 /s to 197m 3 /s Completed 22 nd December

The PROBLEM Risk assessment conducted on all identifiable sections of the project. Significant risk associated with the servicing of the raisebore cutter head. Needed to completely isolate the area around the bottom of the reamed shaft – Identified 3m as being a safe working distance after risk assessment conducted.

The SOLUTION Planned for at least one change out. Decision between AMALG Res. and RBA was to design and fabricate an extended pair of breakout spanners. Drawings were completed sent to AMALG’s Mechanical engineer to perform strength of material calculation’s. These were then sent to Townsville Engineering for fabrication.

Super Spanner

SPECIFICATIONS Spanners constructed of: –Bisalloy 80 –50mm thick –Built up around jaws of spanner –Top spanner 3.85m –Bottom spanner 4.1m –Arguably the biggest spanners in North Queensland

Close up of top spanner

The CONCEPT Top spanner wraps around stabilizing rod inside ribs. Bottom spanner sits below it and offset from it. Portapower ram links the two spanners via a rod. Ram extended forcing spanners together. Force supplied sufficient to overcome the torque applied when initially tensioning rods. Joint between stem rod and stabilizer loosened. Simply rotate drill string anti clockwise to remove reaming head. Result – removal of reaming head without personnel being exposed to shaft brow.

The PROCESS Operators briefed and JSA agreed upon and signed off. Establish communications between surface drill rig operator and underground operators. Lower rods to floor. Forklift hooks up conventional spanner. Rotate rods so spanner on right hand side of drive. Forklift hooks up second wrap around spanner. Link two spanners with rod and portapower ram. Apply pressure to portapower to loosen raisebore head from stabilizer rod. Spanners removed. Stem rod and reaming head removed. Raisebore head dragged out with loader. Connect 660mm raisebore head.

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The COST ALTERNATIVES *Note The spanners were available at the completion of the project. Sold to RBA at cost Alternative 1Alternative 2 Spanners $11,124- Delay Rates ($350/hr) $875$42,000 Replacement Stabilizer Rod -$15,000 Time to Complete (hrs) Total Cost$11,999$57,000

The RESULT Alternative 1 was chosen Completed ahead of time and under budget Safe, economical and timely solution to a common problem The result proved that INNOVATIONS such as this can be implemented if a little thought goes into the initial design stages