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Initiative #423 Hollow bar and carbothyx application

Initiative DescriptionThe hollow bar with Carbothix is a rapidly installed single pass long anchor support

system in comparison to conventional cablebolts. Attempting to eliminate FOG events atboth Kencana and Toguraci for improved production reliability a ma!or strategy shift hasbeen decided upon by Gosowong "anagement regarding what constitutes T# groundsupport going forward. This change involves increasing the capacity and suitability of the T#support class using long anchors $hollowbars with Carbothix%.

The bond strength developed between the resin grout and mudstone&argillic contactis significantly better than the bond strength between splitset steel and mudstone&argillicmaterial. 'igher bond strength per meter together with a longer bolt $(m)% provides a muchhigh capacity support element.

*nabling pro!ect for accelerated production&ore tonnes.

+educed FOG events

,mproved advance rates in very poor ground $normally associated with high grades%.

Key Decisions and interdependencies

Additional cost of hollowbolts and resin -#/ p.a

Additional 0alue of CutsOf Total meterage $1((1% 23 is T# $4566m%Of T# 53 in Ore $424#m%##4 Cuts $2.57m%44.71 'ours improvement $76.88 to #2.#4 'rs% 9 24.#3 improvement:otentially allows 87 Additional Ore Cuts through increased heading availability:otential +evenue -#.(m

;et cash -#.2m*nabling pro!ect for accelerated production&ore tonnes.

How does this initiative change and improve our business performance

Currently the high capacity long anchors used for ground support in very poorroc/mass conditions at Kencana are twin strand bulbed cablebolts.

Complete shotcrete mesh ? bolt cycle

@ore hole with !umbo or solo drill

"anually install cablebolts with the service crew and ,T

"ix and pump grout

ait minimum of 1 hours for grout to cure

Tension and plate cablebolts with service crew and ,T advance face.

This is a very slow process $2# to #1 hours% and provides significant opportunity for

the wea/ roc/ to yield ? fail before long anchor ground support is installed grout has curedand tensioning can occur.

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4. ,n extremely poor ground areas extensive production delays can be experiencedwith hole collapse and subse=uent inability to install cablebolts. Occasionally it isimpossible to unbloc/ holes by re9drilling due to continued hole collapse and ahigher ris/ alternative must be developed $ie. rib pillars or reduced number ofcablebolts etc.%. 'eadings in T# ground can generally be turned around 2#96( hours.,f cablebolts are needed however this becomes 6(9#1hours. ,f re9drills are neededor solo is unavailable delays to heading advance can increase even more. Theimpact on production given that our highest grade headings are normally associatedwith our poorest ground conditions can be significant.

2. A serious concern when trying to recover fall of ground areas is the re=uirement toexpose personnel to increased ris/s when wor/ing in an ,T bas/et out beneath verypoor ground. This increased exposure is due to the re=uirement to manually installand grout cablebolts at Kencana.

6. Currently the =uality aspects of cablebolt installation are put in the hands of our

grouting crew which is a tas/ normally reserved for our least experiencedunderground employees. This can occasionally result in problems with poorly groutedcablebolts which has in the past been suspected as a /ey contributor to historic fallof ground incidents. An example of this was in the K294A where a 6 wee/ delay wascaused due to a FOG incident believed to be caused by ineffective cable bolting.*xtensive resources were diverted to this heading from other mining areas to recoverthe high grade heading $27g&t%.

For these three /ey reasons mentioned above cablebolts are considered to beunsuitable for certain situations at Kencana and an alternative bolt is re=uired to addressthese concerns.

After a review of various bolting options available on the mar/et a suitablealternative long anchor was identified in the self drilling anchor $B