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SYNOPSIS

This paper describes bard and pillar trackless mining at

depths of 1 DOOm and deeper on the Merensky reef horizon.

BUS El PlE

INTR UCTI

Impala Platinunl Limited, Implat's major operational asset, has

its primary operations concentrated on the Impala lease area

on the Western limb of the world-renowned Bushveld

Complex, near the towns of Phokeng and Rustenburg in

South Africa's North West Province. The mining lease

covering approximately 27 500 hectares.

Mining at Impala focuses primarily on two reefs, Merensky

reef and UG2 Chromitite layer, a well- layered ultramafic to

mafic igneous succession of the 2 000 million year old

Bushveld Complex.

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INTRODUCTION C T.1

Thirteen operational shafts deliver ore to two reduction plants. A total of 16m tons per annum of which the TM3 bord and pillar operations delivers 11 % of the total volume of the mine.

12 Shaft's Merensky ore reserve block that has been mined conventionally, is being depleted rapidly. To maintain the production volume at the shaft, it was decided to mechanise the ore reserves below the bottom level of the shaft, as the channel width lends itself to trackless mining.

INTR UCT~ CONT.2

An ore reserve block below the deepest level, 20 level, on the

down dip side was available for mining, however the development

rate for opening up ore reserves for conventional mining did not

make any contribution to the short term mining plan.

An opportunity arose whereby the production challenge could be

met by implementing a bord and pillar TM3 mining method.

Feasibility studies pointed out that bord and pillar TM3 mining

could be mined at an acceptable profit margin in that specific ore

block. Mining cornmenced in late 2003.

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SAFETY

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SAFETY

• Safety is a priority and it is our goal to ensure that Impala's

safety performance, which currently ranks among the best in

South Africa, at least matches best international underground

mining practices .

., A behaviour - based safety observation process aimed at

eliminating actions that could cause injuries to employees,

has been implemented. This process creates commitment to

working safely.

• In line with a set of Best Practice safety rules, each operating

division introduced a set of five platinum rules to address

critical risks.

• The Lost Time Injury Frequency Rate for the current Business

Plan is 3.39 per million man hours worked.

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INING LAYOUT

The trackless section is situated on the deepest level of 12

shaft, 1000m deep, with a strike distance of 1.5km from the

shaft structure in a southerly direction.

Access to the section is through a twin haulage configuration:

A men-and-material haulage with man carriages, and an ore

transport haulage with a 20Dt electric overhead train.

All large equiprnent and machinery is dismantled or split on

surface and re-·assembled on 20 level station.

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1Nl LAYOUT CONT. 1

The conveyor belts are not fire-retarded, but equipped with a

automatic Fogtech fire suppression system on all the dip belt

drive units. The remaining strike belts have been equipped

with fire hydrant units, 30 meters apart.

A dip conveyor belt has being installed on true dip, on reef

and essentially in the middle of the ore block, within reach of

the development ends. A 2.2m/s 1050mm steel core conveyor

belt tips into a silo which feeds into a second silo via a

second dip conveyor belt loading into the 200t electric

overhead train, the final tram to the shaft.

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1Nl LAYOUT C T.2

Six strike conveyor belts tip onto the dip conveyor belt. Three from the north nlining direction and three from the south mining direction.

These are 1.5m/s 1050mm canvas conveyor belts with Rammer Z250 telescopic hydraulic hammers on each loading point at the face. The dip spacing between conveyor belts is 154m.

8elt forward moves are planned to maintain a maximum of 75m from the working face to the loading point.

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I I LAYOUT T.3

Strike belt sections

A strike belt section consists of 8 X 12m bords. Four X12m

Bords are up dip from the strike conveyor belt and 4 X 12m

bords are down dip. The 6m wide strike belt is drilled by a

conventional hand held rock drill crew and cleaned by an

LHD.

A strike conveyor belt section forms one unique mining unit

with the following allocated to that unit: a cost code, a

workgroup and trackless equipment.

The total TM3 section consists of six strike belt sections.

The development comprises of 3 down dip bords, two 12m

down dip intake airways and one 6m down dip conveyor bord.

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ININ yeLE

• Two 8 hour shifts per day, a night shift and a day shift.

• Eleven day fortnight.

ID On average 23 days per month.

• 274 Day's per year.

• End of morning shift surface centralized blasting.

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PR UCTIO

Planned production for a strike belt section

" 2100m 2 /month.

• 12500Umonth.

Planned production for the total bord and pillar section.

" 12600m2 /month.

" 75000t/month.

On reef development to open up new bords.

.. 145m linear in the 3 development on reef bords.

" 8000Umontlh.

PIRODUCTION T. 1

Mining parameters

A stoping width of 1.9m is being achieved currently with a relative density of 3.05t1m3 and a head grade of 3.70g/t.

The drilling pattern is a burn cut of 50cm horizontal and 50cm vertical, addingl up to + 89 holes per face. Three meter effective drill holes are drilled and loaded with 4.5kg of Expanfo 200 alllmonium nitrate fuel oil explosives per hole. The bottom holes are loaded with Explogel V10 watergel exp~osives. ThE~ initiation system is a 7.8m 3800/3800 millisecond Dual Detonator Primadet nonelectric initiation system.

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PR UCTI CONT.2

SUPPORT

Support is provided by 4m x 12m yield grid pillars with 12m x

36m stable barrier pillars along the conveyor belts. In-stope

support is 1.5m hydra bolts on a 1.5m x 1.5m pattern.

Installation is done by a conventional hand held rock drill

crew, supporting two bords per shift. Extra support in the form

of shot crete and long anchors is installed at geological

features, low "C~" rating or poor ground conditions.

FLEET

et The trackless fleet per conveyor belt section consists of the

following:

et 1 Drill Rig. (Axera 126 LP Single boom HLX5 Drifter.)

• 2 LHD's. (EJC 115)

• 1 Utility 'Vehicle. (GHH)

• A swing LHD and Drill Rig is available per 3 belt sections for

replacement during scheduled maintenance.

• The developrnent section consists of:

• 1 Drill Rig. (Axera 126 LP Single boom HLX5 Drifter.)

o 2 LHD's. (EJC 115)

et 1 Utility Vehicle. (GHH)

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FLEET T. 1

The total fleet for this TM3 section is as follows:

• 10 Drill Rigs. (Exera, single boom, HLX 5)

• 18 LHD's. (EJC 115)

• 5 Utility Vehicles. (2 Fermel and 3 GHH)

• 2 Supervision vehicles. (Scorpions)

• 1 Breakdown Vehicle. (Toyota)

The total fleet is being maintained by Sandvik Mining and Construction (SMC) based on a labour hire contract basis. Parts and consumables are financed and managed by the Mine.

LABOUR COMPLEMENT

The total labour complement for this bard and pillar mining

section, including the logistic complement but excluding the

service departrnents, is listed below.

• Mining, Stope:

• Mining De,,:

CD Mining Sectionals:

• Engineering:

• SMC:

• TOTAL SECTION

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AT WORK

224

38

36

128

44

470

EFFICIENCIES

Efficiencies calculated, based on the production achieved

during the period July 2005 to January 2006 are below.

• LHD. (EJC 115)

• Drill Rig. (A.xera 126 )

e Average Face Advance.

et Average Advance Per Blast.

e Tons per total employee.

• Average on reef development.

6550tlmonth

2210m 2 /month

26.4m/month

2.8m/blast

185/month

194.6m/month

EFFICIE IES T. 1

Fleet efficiency for two full 8 hour shifts, including traveling

time to work place:

• LHD. 85 % Available and 74% Utilized.

• Drill Rig utilization, on percussion hours only.

4& Drill Rig. 92% Available and 35% Utilized.

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'T NAGE BUILD UP

Important points to mention which contribute to the success of

achieving the planned build up:

ID The drill ri~) determines the rate of mining and the mining

cycle.

Et The minin~) cycle must be understood and communicated between shifts ..

• Each strike belt section must understand their daily call

and aim to achieve that call.

4) Mining supervision must concentrate on the utilization of

the available fleet to ensure that production is being

achieved.

• Equipment utilization per shift must be maximized.

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NCLUSIO

The trackless mining section's total shaft cost per Kg PGM's

has proved to be competitive with other conventional shafts

on Impala. However, the wide channel width in this area that

has made trackless mining possible, is localised and is not

present at other Impala Shafts, except for a small section at

no. 14 Shaft.

Acknowledgement:

The author wishes to thank the management of Impala

Platinum for their permission to publish this paper, as well as

their commitment to better and safer mining.

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