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

Eloise Copper Mine

Overview of OperationOverview 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 ShaftOverview of Ventilation ShaftVentilation 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 ShaftDevelopment of Ventilation ShaftBegun 20th JulyMajor Pontil – 482.5m directional hole accurate within 0.35mHole reamed to accommodate RBA drill stringRBA back reamed 3.5m diameter shaft up to the cretaceous sediments (overburden)Lower rods – will expand upon this stepChanged to 660mm diameter head – reamed to surfacePiling contractors and Jetcrete worked together to bore and line the remaining 57m to a diameter of 3.0mInstallation of the southern ventilation fanAs a note increased the quanity of air from 82m3/s to 197m3/sCompleted 22nd December

The PROBLEMThe 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 SOLUTIONThe 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’sMechanical engineer to perform strength of material calculation’s.

These were then sent to Townsville Engineering for fabrication.

Super SpannerSuper Spanner

SPECIFICATIONSSPECIFICATIONS

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 spannerClose up of top spanner

The CONCEPTThe 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.

TheThe PROCESSPROCESSOperators 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.

PHOTO 1PHOTO 1

PHOTO 2PHOTO 2

PHOTO 3PHOTO 3

The COST ALTERNATIVESThe COST ALTERNATIVES

Alternative 1 Alternative 2Spanners $11,124 -

Delay Rates ($350/hr) $875 $42,000

Replacement Stabilizer Rod - $15,000

Time to Complete (hrs) 2.5 120

Total Cost $11,999 $57,000

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

The RESULTThe RESULT

Alternative 1 was chosenCompleted 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