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

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

2. 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.

3. 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.

4. Development of Ventilation Shaft • Begun 20th 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 82m3/s to 197m3/s • Completed 22nd December

5. 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.

6. 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.

7. Super Spanner

8. 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

9. Close up of top spanner

10. 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.

11. ThePROCESS • 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.

12. PHOTO 1

13. PHOTO 2

14. PHOTO 3

15. The COST ALTERNATIVES *Note The spanners were available at the completion of the project. Sold to RBA at cost

16. 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