reef adjacent tau tona aga

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1

Reef Adjacent To Structures at TauTona Mine, AngloGoldAshanti South African Operations

DE DAVIES

Section Manager

TauTona Mine, AngloGold Ashanti South African Operations

SYNOPSIS

The paper describes the extraction of reef adjacent to geological structures in theCarbon Leader Reef Section at TauTona Mine. Traditionally long wall mining

has left feasible and economical blocks of ground adjacent to structures whennegotiating major geological features. This meant that mining through an up-throw fault, rolling to the reef elevation on the displaced side of the fault left reefin the long wall. High grade areas were abandoned and gold was sterilized.

In these tight economic times and with the need to continuously improve safetystandards the need arose to develop a technique to extract these blockseconomically and safely. It was believed that the structures in these abandonedareas were de-stressed and could now be mined in small volumes at a highgrade.

The term RATS is an acronym derived from “reef adjacent to structures” andaptly describes the process of identifying and extracting these blocks. Theviability of this method was addressed in terms of the mine design, undergroundinvestigations and financial risks.

The paper concludes with an analysis of the successes achieved to date.



2

INTRODUCTION

TauTona Mine is one of the AngloGold Ashanti Southern Africa operations. It isclose to the town of Carletonville in the province of Gauteng and about 70km

south-west of Johannesburg. TauTona is 46 years old and employs ± 4 000people. Mining operations are conducted at depths ranging from 1,800m to3,500m at which the world’s deepest stoping sections are found.

Figure 1: The geographical map of TauTona Mine

Ergo

Western Ultra

Deep Levels

TauTonaSavuka

Mponeng

Tau Lekoa

Great NoligwaKopanang

Moab Khotsong



3

TauTona’s values are:

People are our business… Our business is people.

Safety is our first value: We place people first and correspondingly put

the highest priority on safe and healthy practices and systems of work.We are responsible for seeking out new and innovative ways to ensurethat our workplaces are free of occupational injury and illness. We liveeach day for each other and use our collective commitment, talents,resources and systems to deliver on our most important commitment… tocare.

We treat each other with dignity and respect: We believe thatindividuals who are treated with respect and who are entrusted to takeresponsibility respond by giving their best. We seek to preserve people’sdignity, their sense of self-worth in all our interactions, respecting them for

who they are and valuing the unique contribution that they can make toour business success. We are honest with ourselves and others, and wedeal ethically with all of our business and social partners.

We value diversity: We aim to be a global leader with the right peoplefor the right jobs. We promote inclusion and team work, deriving benefitfrom the rich diversity of the cultures, ideas, experiences and skills thateach employee brings to the business.

We are accountable for our actions and undertake to deliver on ourcommitments: We are focused on delivering results and we do what we

say we will do. We accept responsibility and hold ourselves accountablefor our work, our behaviour, our ethics and our actions. We aim to deliverhigh performance outcomes and undertake to deliver on our commitmentsto our colleagues, business and social partners, and our investors.

The communities and societies in which we operate will be better offfor TauTona Mine having been there: We uphold and promotefundamental human rights where we do business. We contribute tobuilding productive, respectful and mutually beneficial partnerships in thecommunity in which we operate. We aim to leave host communities with asustainable future.

We respect the environment: We are committed to continuallyimproving our processes in order to prevent pollution, minimise waste,increase our carbon efficiency and make efficient use of natural resources.We will develop innovative solutions to mitigate environmental and climaterisks. (Mark Cutifani, Chief Executive Officer – AngloGold Ashanti)



Our objective is to mine gold safely at the correct profit margin. We are a teamthat produces gold by believing that the workplace can be injury free. We areachieving our targets through people, we want to maximise TauTona’scontribution to AGA shareholders by exploring and managing life of mineextension opportunities and striving for continual improvement. As depicted in the

following graph, safety statistics for the “RATS” operations from 2005 to 2008proofs that mining reef adjacent to structures at depth was done safely.

Figure 2: Injury Statistics for RATS 2005 – 2008

At TauTona Mine gold production declined from 2005 to 2008 by 27% to 9 332kg,owing to a greater-than-scheduled decrease in volumes of ore mined. This wasa result of increased seismic activity in the vicinity of the CLR shaft pillar which isbeing mined. Both face length and face advance were negatively affected byseismicity during 2008. (AngloGold Ashanti’s Report to Society, 2008, South

Africa: Johannesburg.)

At TauTona Mine we believe in continuous improvement and therefore it is ofutmost importance to review all our current processes, to find ways to make it

even more effective and value creating.

The concern we have is that TauTona mine traditionally used the longwall miningmethod. Our gold production has decreased and a need to create additional facelength arose in order to create flexibility. Because of increased seismicity, we hadto change our mining strategy. To remain sustainable we decided to develop amethod of extracting gold from the reef adjacent to structures without interferingwith the current operations, thus enhancing our gold profile.

0

1

2

3

4

5

2005 2006 2007 2008

Dressing Cases

Loss Time Injuries

Serious InjuriesFatalities

•26 June 2007 Laceration Finger Tools and equipment Serious injury

•07 Aug 2007 Contusion Thumb Tools and equipment Serious injury

Injury Statistics for “RATS” 2005 - 2008



5

REEF ADJACENT TO STRUCTURES (RATS):

The long wall mined through an up-throw fault, rolling to the reef elevation on thedisplaced side of the fault and leaving reef in the hanging wall. Depicted in the followingfigures are the original abandoned blocks left by longwall mining and a sketch indicating

reef displaced between 5 and 10 leaving reef adjacent to structures.

Figure 3: Geological complexity of TauTonaMine

Figure 4: Abandoned blocks adjacent tostructures

Figure 5: Sketch indicating reef displaced between 5 and 10 metres leaving reef adjacent

to structures

OOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO

OOOOOOOOOOOOOOOOOOOOOOOOOOOOOO

Reef left in hanging

F a u l t Reef band

Reef band

RATSOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOOO

OOOOOOOOOOOOOOOOOOOOOOOOOOOOOO

Reef left in hanging

F a u l t Reef band

Reef band

RATS



6

METHODOLOGY

Support design:

The support design was based on the Fall of Ground Management Process(FOGM) with specific reference to mine wide design guidelines – FOGM 1 andthe Local area design guidelines – FOGM 2. FOGM 1 is aimed at the preventionof rock burst and FOGM 2 is aimed at the prevention of rock bursts and fall ofground.

FOGM 1: Mine wide design guidelines used

Both modelling and seismic trends must indicate that the planned RATSmining are sufficiently removed from current working places not to haveany interaction.

No mining into the stressed abutments at the top or bottom of a long wallincluding pillars.

All access ways must be positioned under mined out ground where nostress changes will occur due to the new mining activity.

FOGM 2: Local area design guidelines used

In order not to mine into existing excavations all stoping and developmentmust be clearly indicated and avoided.

To leave crush pillars against major faults.

To consider preconditioning of prominent dykes.

Design considerations

We assumed that shallow mining conditions would prevail as the area had beende-stressed with the original mining. Due to the regeneration of stress in theback areas, the stress would now be zero. Careful modelling shed some light onthe expected stress conditions. The initial elastic modelling indicated stresses ofapproximately 7 MPa. It was thus assumed that the back area stress would bebetween 0 MPa and 10 MPa.

Stope closure is a combination of elastic convergence and in-elastic bedseparation – especially in the hanging wall. This bed separation is at maximumclose to the stope face and decreases in magnitude further away (into thehanging wall). It was unknown how much of this bed separation would be visibleand what affect it would have on the planned mining.



7

Ideally, the support installed must prevent the first bed from falling, therebysupporting the additional layers in the hanging wall. The first layer is howeverunknown, but drilling support into the hanging wall will improve the integrity of theinitial support system design. If drilling is impossible, the support design mayhave to be adjusted as soon as the stoping has commenced and new information

becomes available.

Low closure rates were expected, thus stiff active support had to be designed.Because the expected closure rates could not be determined, yielding supportwas considered. Low seismic rates were probable, but close to abutments theseismic risks increased.

The possibility of back break conditions on large spans could not be disregarded. As proven by the platinum mines breaker lines of packs were often used toprevent back break from forming up to the face area. With packs on the gulliesand limited panel spans, these breaker lines would not be required.

Support design

The standard approach is to use the accident statistics for the applicablegeotechnical settings at the mine for the past 5 years to determine the falloutthickness to be supported. From this the support resistance and energyabsorption criteria can be calculated. The support standard is then designed tomeet these criteria.

In this case the accident statistics is not applicable as the geotechnical setting is

totally different. There are no accident statistics available for this geotechnicalsetting on TauTona.

With so many unknowns and a “new” geotechnical setting, a different approachto support design was required. Without accident statistics the next option wasto try and pre-determine a likely fallout thickness. The most likely falloutthickness is up to the first well defined bedding plane consisting of quartzite.

The bottom contact between the Greenbar and the quartzite has practically nocohesion and can be assumed to determine a likely thickness (2m above the reefcontact). This relates to a support resistance criterion of 53 kN. The nextbedding plane is the top contact of the Greenbar, a further 2m above the bottomcontact, relating to a support resistance criterion of 106 kN.

The current support standard of elongates (Profile props) spaced 1m by 1,6mgives a support resistance capability of 125 kN and can therefore support at leastup to the top contact of the Greenbar.



8

On a larger scale, including the packs in the equation and assuming 20 metrelong panels, the same support standard gives a support resistance capability of200 kN and can support up to 7,5 metres of dead weight (wedge).

Figure 6: FOGM 2 – Support strategy

If the separation is in excess of 7,5 metres, additional packs or in-stope pillarswill be considered.

Figure 7: FOGM 2 – Support strategy

1

2

3

2m

2m

?

Greenbar

1

2

3

2m

2m

?

Greenbar

<5m

In-stope pillars against

the major fault

2m

2m

5m

Mined out on reef Mined out on reef Mined out off reef

<5m

In-stope pillars against

the major fault

2m

2m

5m

Mined out on reef Mined out on reef Mined out off reef

Fallout thickness: Maximum of3.5 metres?

Fault

Mined out Area

Quartzite Beam

Reef left behind

1 = Quartzite beam (53kN)2 = Greenbar zone (106kN)3 = Total deadweight (200kN)



9

After considering all the above and careful modelling the following support designwas established:

180mm to 200mm diameter Profile props.

Pre-stressed packs (75cm by 150cm) on the gully shoulders.

No backfill. In-stope roof bolting would be required.

Continuous closure monitoring.

180mm to 200mm diameter Profileprops. (No Backfill)

Pre-stressed packs (75cm by 150cm)on the gully shoulders

Figure 8: Photos of 116 – 83 Stope indicating installed support units



11

Financial Risks:

Blocks were identified and prioritized according to the set criteria for inclusion inthe Business Unit Plan. The reef adjacent to structures was identified by theMineral Resources Department and each one was allocated with a specific block

number. These blocks were prioritized according to their volume and grade, theircurrent infrastructure utilisation and their proximity to current working places. Amulti disciplinary risk assessment followed after a financial evaluation was done.

Figure 11: Identified RATS blocks

X

XX

X

Feasible

Blocks

Not Feasible

X

XX

X

Feasible

Blocks

Not Feasible

X

XX

X

X

XX

X

Feasible

Blocks

Not Feasible



12

Recovered kilograms were determined by using the Basic Mining Equation(BME) Model. The initial blocks identified indicated 29479m

2 in total. After we

added a 50% discount it resulted in 1413.5 kg broken gold from the stopes. Theaverage values of these blocks were 3481cmg/t. It is important to note that theinitial assessments were done only from plans and a discount factor was added

when underground investigations and geological information became available.This BME model indicated a yield of 25.1g/t.

Figure 12: Total available gold (not discounted)

Plan

FACE LENGTH m 1 300 x FACE ADVANCE m 4.50 = TOTAL m2 m² 29 497 x ON REEF PERCENTAGE % 50.80%

= REEF m2 m² 14 984 x ON REEF cmg/t cmg/t 3 481

x RD = kg GOLD EX STOPES

kg

1 413.517+ VAMPING kg kg 0

+ REEF DEVELOPMENT kg kg 0 = TOTAL kg BROKEN kg 1 413.517

+/- U/G INVENTORY kg 0 = GOLD HOISTED kg 1 413.517

+/- SURFACE INVENTORY (SHAFT) kg 0 = GOLD DELIVERED TO PLANT kg 1 413.517

+/- PLANT INVENTORY kg 0 = GOLD CALLED FOR kg 1 413.517x MINE CALL FACTOR % 74.00%

x RECOVERY FACTO % 97.57%

= GOLD RECOVERED Kg 1 020.585

R3 481 STOPING WIDTH cm 100.0 MILLING WIDTH cm - TOTAL TONS HOISTED (REEF & WASTE) 40 607 TONS MILLED 40 607

IELD (GRADE RECOVERED) g/t 25.1

WIDTHS, TONNES, YIELD

Greenfield BME



13

The next step was to determine whether these blocks would be financially viableto mine. Due to the mining risk this model allowed us to use variable parametervalues to determine feasibility. Firstly the total incline square meters were used.

A 50% discount was added to establish the available square meters to be mined.This allowed us to group blocks together according to accessibility and locality.

Tonnages and contents of these blocks were calculated. Stoping anddevelopment costs were determined by using rand/m² and rand/m cost. Thisvariable model allowed us to use different units: gold price, rand/m, or rand/m² todetermine profits or losses in the different blocks or group of blocks.

The initial financial evaluation indicated that these blocks would be feasible tomine and could be extracted at a profit, thus enhancing the current gold profile.

0.0271 PILLAR NOFINAL

DATE 1 LPI TOTAL STOPING COSTS INCLUDING STORES (BUDGET 2005)

MCF Pla nt REC. GOLD PRICE% % R / Kg.

R/ton

R/ton

R/m

P la nt REC . To ta l R EC .

% %

26

28

36

70

TOTAL 3,832.965

306,637,216

WORKING PLACE H W SG R/ton M2 COST (R/M2 COST IN RANDS

HLGE 3.4 3.0 2.78 264 42028 2094 306,637,216RAW / CON.X/C 3.4 3.0 2.78 0

CROSSCUT 3.2 3.0 2.78 281 80.00RAISE + SLUSHER 3.0 1.8 2.78 500

BOXHOLE 1.2 2.4 2.78 937 88,007,051TRAVELLINGWAY 2.4 3.0 2.78 0 5,287,500

TOTAL 0PLANNED DEV.RATE; m / mth 0

3,294,55124

213,342,6655.7

STOPING,

DEVELOPMENT,

TOTAL ENGINEERING

FLAT RE-EQUIPPING,

DIAMOND DRILLING

WHEN CAN STOPING START ? Date :

PLANNED FACE ADVANCE m./mth.:

PLANNED WORKING PANELS No.:

PLANNED WORKING F/ LENGTH m.:

PLANNED MINING RATE m² / mth.:

PLANNED AREA TO MINE m².:

ESTIM.TIME TO COMPLETION Mths.:

40875

70047

4290

11855 100

105

120

30

900000

DEVELOPMENT COSTS

22.5

4056

0

TOT.STOPE TRE

0 069.57

TOT.DEV. COST

TREATMENT COSTS

4421

COST

225000

113896

SECTION 7 - FINRISK

AILABLE - FLBLOCK No.

INCLINED M² SW

BLOCK

LEVEL

STOPING TO BE DONE

MINED

LINE

GRADE

cm. g/m² Kilograms Au

TONS

OREx°

REEF DIP STOPE STATS

CONTENTS

UNIQUE PILLAR No.

21182

100%

90.3222.533331007816781613027

119.81

GOLD PRICE

R / Kg.

80,000

85.03 80,000

85.03 97.57

MCF

FACTORS

465

Full Width

88,007,051

UNIT COST

4th3rdIN 24IN 18

YEAR YEARMTHSNOW

MTHS

IN 6 IN 12

0

AVAILABILITY AND MINING RATEAS PER

MTHS MTHS

42028

24525

cm.g/t

2574

23.0

7113 23.0

2574

23.0

% GROUND AVAILABLE (MRIS)

42028

100.0

100

4205

100.0

0

60% 0% cm.

7500851

7113

23.0

TONS

DIAMOND DRILLING COST

ESTIMATED TIME TO COMPLETION: mths

5,287,500

+ PORTION OF OTHER COSTS **

R/rec.gm.#DIV/0!

705

RECOVERED GOLD, KG.

FINANCIALS

%

STOPING COSTS

TOTAL REVENUE (RANDS)

DEVELOPMENT COSTS

97.57

R/rec.gm.

ItemREVENUE

82.96

STOPING COSTS

852

267

706

2795

19276

6976

66463

AU TONA MINE- SECTION 311

11389623.0 109.9322.5

3829 22.5

22.5 113.96

Item% M² % M² UNIT COSTS USED IN INVESTIGATION

Unit Costs

STOPING

NEW DEVELOPMENT

FLAT END RE-EQUIPPING

FLTING

FINALSTOPE SHEET BLOCK No. ALL

DEVELOPMENT SHEET PANELS

100

SW Full Width

CW VALUE

(MRIS)

4620

24525

103.77

METRES

450 6755 7500

2802

0

R/m *Dev

3375000 COSTS7875007500

16.13 AVG Tons / M TOTAL MINING COST

9610

75000

11369 *Standard VR

TREATMENT AND OTHER COSTS PROFIT / LOSSR/rec.gm.

ITEM

Profit/Revenue %(R/ton) 113896 0

T (R/t & R/m)

(R/ton) 6755 0

TONSDIRECT COST

TOT.DEV. TREAT.

(Rand) 00

OTAL TREATMEN(R/ton) 0

(Metres) 0

Figure 13: Financial Model



14

IMPLEMENTATION

PILLAR INVESTIGATION PROCESS:

In the implementation process certain steps are critical to ensure all possible

constraints are addressed prior to allocation of resources. A flow sheet asdescribed in appendix 1 was used to ensure involvement of all the role players.

Geologist and Evaluator to identify all areas with Reef adjacent toStructures.

CAD’s Operator and Surveyor to update the plans and add additionalinformation.

SHE Officer to compile the necessary ventilation layout for initialinvestigation.

Mine Overseer to do initial underground investigation in conjunction withthe rock engineering, ventilation and engineering assessments.

Hold a workshop with all the necessary role players to do a baseline riskassessment.

If blocks are inaccessible from current infrastructure an initial developmentlayout is done in terms of the mine design.

Complete pillar investigation form and ensure sign offs from alldepartments.

See Appendix 1 for process flow sheet, section 1 to 10, were detailed and signedoff plans was used for inclusion into the mining schedule.

Figure 14: 1 and 200 Mine Plan



15

Reef adjacent to structures’ blocks were identified by using the volume, gradeand kilograms allocated to the blocks. This was determined by using Krigevalues.

Figure 15: Identified blocks by utilizing volume, value and grade

4 839m²@ 3 804cmgt

498.895kg

4 839m²@ 3 804cmgt

498.895kg 1 454m²@ 2 964cmgt

116.791kg

2 354m²@ 4 167cmgt

265.753kg

610m² @ 2822cmgt

40.882kg

1 454m²@ 2 964cmgt

116.791kg

2 354m²@ 4 167cmgt

265.753kg

610m² @ 2822cmgt

40.882kg

Green Bar erosionChannel ?

10 583m²@ 3 648cmgt

913.691kg

Green Bar erosionChannel ?

10 583m²@ 3 648cmgt

913.691kg

±10 000m² @ 3 648cmgt

913.691kg

±10 000m² @ 3 648cmgt

913.691kg



16

PROCESS:

From the pillar investigation process all relevant information was used todetermine and prioritize blocks according to their volume and grade, their currentinfrastructure utilisation and their proximity to current working places. A multi

disciplinary risk assessment was conducted and the blocks were scheduled interms of availability, equipping and resource requirements.

For the initial blocks identified no development was required to access theblocks. Resources were allocated in terms of equipment (winches, loco’s,loaders, switches, rails, box fronts, miscellaneous stores) and labour. The 111employees allocated to the project included stoping, equipping, horizontaltransport, haulage maintenance and supervision labour. The implementation ofthis mining method commenced with four crews doing the equipping, ventilation,support and establishment of the blocks. Each crew consisted of a Stope TeamLeader, Miners Assistant, four Rock Drill Operators - Stope and four Stope Multi

Task Crew members.

A crew movement and section build-up schedule was drawn up andimplemented. Stoping of the reef adjacent to structures commenced in June2005.

Due to the fact that the throw of the faults determined the face length shortpanels were designed with a face length between 10 and 20 metres. Most ofthese structures generally strike North East. The reef at TauTona Mine dips fromNorth to South at 22 degrees and strikes from East to West. Current box holeswere used as the initial attacking point. A diagonal wide gully was mined in a

western direction through the old stope until reef was intersected and continuedup to the fault position. After this establishment a north gully was positioned inthe centre of the block and in the direction of the fault. This establishmentcreated the face length and opened the block for extraction according to thesupport design specifications. All blocks were extracted without night shift, thusdoing both cleaning and blasting on day shift.



17

RATS PLANNING: CREW MOVEMENT AND SECTION BUILD- UP

Work Place Page Block cmgt M2 @ Gang March April May June July Aug Sept Oct Nov Dec J an ' 06 Feb Mar A pr May J un J ul Au g Sep t O ct No v Dec Jan ' 07 Fe

UCL LCL 60% 120m2 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 2

101 13 72 4293 1931 8 A 25 50 75 100 120 120 120 120 120 120

8 B 50 50 75 100 120 120 120 120 120 120

102 14 73 4703 1106 9

83 2 26B 3049 2588 11 C 50 50 100 120 120 120 120 120 120 120 120 120

11 D 50 75 100 120 120 120 120 120 120 120 120 120 120

85 1 26A 4136 2984 12 0 513 0 5

87 3 26C 2594 2244 10 E 50 50 100 120 120 120 120 120 120 120 120

9 0 100 100 120 120 120 120 120 120 120

87 4 28 3829 1287 11 F 50 50 100 120 120 120 120 120 120 120 120 120

85 1287 11 0 100 100 120 120 120 120 120 120 12

107,5 15 74 4870 1591 13 0 50 75 100 100 120 12

109 16 75 4899 1746 15 G 25 25 50 100 120 120 120 120 120 120 120 120 120 120 120 120 120

17 76 2240 739 6 0 50 100 100 120 120 120 120 12

93/94 12 36H 4444 2279 10 0 100 100 100 120 120 120 120 120 120 120

9 40 50 100 12

97 5 36A 3310 4145 35

94 7 36C 4055 1724 14 H 0 25 50 70 100 120 120 120 120 120 120 120 120 12

96/97 6 36B 3982 2678 11

11 I 0 50 70 10

93/94 11 36G 4742 1918 8 50 70 120 120 120 120 120 120 120

8 0 4

97 36

GRANDTOTAL 30247 0 0 0 150 275 475 690 800 840 840 840 865 890 890 830 850 870 940 870 915 860 920 1010 84

TOTAL GANGS 0 0 0 4 6 7 7 7 7 7 7 8 8 8 8 8 8 8 8 8 8 9 9

TOTAL GOLD KG' s @ 4056 cmgt 0 0 0 14,9 37,7 46,8 69 80,6 83,9 83,9 83,9 86,6 89,4 90,4 84,8 87,5 93,5 102 95,3 103 94 101 113,07 10

2 Year Au kg total = 1655.27

2 Year m2 total = 16460

Figure 16: Mining Schedule



18

BENEFITS OF MINING METHOD

The production profile improved from 1646m² produced in 2005 to 6579m² in2008. The gold profile in the RATS also increased from 112 kg broken in 2005to 592 kg’s broken in 2008. Since implementation of the project 23 864m² has

been mined and yielded 1938kg broken gold.

The reef adjacent to structures became an integral part of our resources andoptimized our plan. The limited window of opportunity to mine these blocks wasaddressed against the set criteria and included into our plan. This processenabled us to optimize the full potential to extract gold from RATS withoutinterfering with the current operations, thus enhancing our gold profile.

We had no previous knowledge of mining reef adjacent to structures at depththerefore a unique support strategy was designed and implemented successfully.Each block have its own design in terms of mining layout and support strategy toallow the successful extraction of these blocks.

Figure 17: Production Performance actual m² and Kilograms

0

1000

2000

3000

4000

5000

6000

7000

8000

9000

Act Total m2 1646 4698 8950 6579 1991

2005 2006 2007 2008 2009 YTD

0

100

200

300

400

500

600

700

800

Act Broken Gold 112 348 713 592 173

2005 2006 2007 2008 2009 YTD



19

CONSTRAINTS

It was foreseeable that ventilation and cooling would be the biggest constraint.This was addressed through the implementation of proper ventilation layoutsutilizing the current infrastructure.

Seismicity on structures was not excluded, but by implementing the uniquesupport design it was proven that this risk was minimized and controlled.

Inaccessibility of the blocks prior to mining provided us with limited geologicalinformation on the reef horizon. The structures in the blocks were modeled fromold geological mapping, thus creating a degree of uncertainty in terms ofconfidence levels in some blocks. Structural changes within the blocks whenmining commenced could influence the successful extraction of the blocks.

Interference with current mining, when mining reef adjacent to structures, posed

a major risk in certain areas which could influence the volume of the currentlongwall operation. Re-mining in these areas could increase the seismicity,resulting in the loss of the access ways to the existing long walls. In additionlayouts for ventilation were critical to ensure that ventilation conditions wereconducive for mining both the areas.

A proper assessment of all existing excavations in the proposed mining area wasnecessary to prevent unnecessary holing into established infrastructure.

CONCLUSION

Due to the complexity of the mining environment it is inevitable that one must beable to adapt to change in order to ensure the viability of the system. This paperdoes not seek to obscure your mind, but rather to stimulate the thinking process.

It is imperative to not only remember the basic principles of mining but tochallenge the obvious.

At TauTona Mine it was proven that mining reef adjacent to structures at depthneeded a dynamic and workable plan. The unique extraction sequence per blockwas a major contributor to the success of this mining method. The reality is that

successes and failures in blocks are inevitable. The multi disciplinary riskassessment and involvement of all services departments is imperative to ensurethe success of mining reef adjacent to structures.

The content of this paper results from approximately four years of experience inmining reef adjacent to structures at depth. It was written with the objective ofassisting fellow mining engineers in the planning and implementation of such amining method.



20

ACKNOWLEDGEMENTS

The author wishes to thank the management of TauTona Mine for permission topublish this paper and all the persons who assisted in the preparation.

In addition thanks to Great Noligwa Mine for their Pillar Investigation ProcessFlow Sheet and Lourens Scheepers, Rock Engineering Manager, TauTona Minewho assisted with the support design.

REFERENCES

AngloGold Ashanti. (2008). Report to Society. South Africa: Johannesburg.

Jager, A.J.; Ryder, J.A. (1999). “A Handbook on Rock Engineering Practice forTabular Hard Rock Mines”.

Le Roux, W.L. (1979). “Mine Ventilation Notes for Beginners”.

Lurie, J. (1984). “South African Geology for Mining, Metallurgical, Hydrologicaland Civil Engineering.

Ritson, T.P. (1997). “Surveying for Mine Surveyors”.

Storrar, C.D. (1987). “South African Mine Valuation”.



21

APPENDIX 1: PROCESS FLOW SHEETS SECTION 1 TO 10

WORKING PLACE

MRM Pillar geologist.

Section 1 completed. Sign: Date:

MRM CAD Operator.


MRM Senior Evaluator


Section Surveyor.


MO Old areas.


MRM Planning officer.


MRM Pillar Geologist - FINRISK.


Rock Engineering Department.Section 8 completed. Sign: Date:

SHE Department.


Engineering Department


Summary

Geology ManagerSection 11 completed. Sign: Date:

Section ManagerSection 11 completed. Sign: Date:

MRM Manager.Section 11 completed. Sign: Date:

W

ORKI N G

P L A

C E

BLOCK No.

P I L L A

RN o.

PILLAR No.

BL O C K

N

o s.

FLOW SHEET FOR PILLAR INVESTIGATION FILE

TAUTONA MINE

Flow sheet for Pillar Investigation



22

WORKING PLACE

SECTION 1 PILLAR GEOLOGIST

i) Review available information:

1:200 stope sheets

1:200 development sheets

Assay tracings

ii) Complete updates:

Strike lines

Faulting

Facies type

RIH/RIF

iii) Determine:

RGSW

Hazardous conditions

iv) Transfer onto geological investigation sheet:

v) Transfer to CAD:

Signature :- Date:

PILLAR No.

BLOCK No.

TAUTONA MINE

W

ORKI N G

P L A C E

BL O C K

N

o s.

P I L L AR

N

o.

Section 1: Pillar Geologist



23

PILLAR No.

Geologist: Date: BLOCK No.

Working place:

Plan scale 1: 1000

Refer to Stope sheet: and Development sheet:

U/C F/W

Historic sampling in the adjacent panels indicate cmg/t.

It is proposed by Geology to

Facies type:

ORIS:

Geological comments:

INCLINED M2 :

INSERT A COPY (1: 100)

CW (cm) :

SW (cm):

Rock Engineering comments:

This p il lar C AN / CANNOT be mi ned safe ly . This p ill ar CAN / CANN OT be mined safe ly.

AppendixGEOLOGICAL INVESTIGATION

TAUTONA

MINE

GRADE (CMG/T) :

STOPING STYLE

RGSW cm.

INSERT A PLAN COPY (1: 1000) ON NEXT PAGE

Geological Investigation



24

WORKING PLACE

SECTION 2 - CAD OPERATOR/DRAFTSPERSON

i) Update geological information on CAD/Microstation

ii) Create print of area under investigation

iii) Check updates with pillar geologist

iv) Attach copy of print to geological investigation sheet

v) Attach copy of print to old area investigation sheet

Signature :- Date:

PILLAR No.

BLOCK No.

TAUTONA MINE

W ORKI N G

P L A C

E

CHECKLIST

BL O C K

N o s.

P I L L AR

N o.

Section 2: CAD Operator



25

WORKING PLACE

SECTION 3 - SENIOR EVALUATOR

i) Review available information:

ii) Capture relevant peripheral sampling:

iii) Evaluate block No's:

ORIS:

Inclined M2

CW (CM)

SW (CM)

GRADE (Cmg/t)

kriged

conventional

ORIS

Signature :- Date:

P I L L AR

N o.

PILLAR No.

TAUTONA MINE

W ORKI N G

P L A C E

CHECKLIST

BLOCK No.

BL O C K

N o s.

Section 3: Senior Evaluator



26

WORKING PLACE

SECTION 4 - SECTION SURVEYOR

MCF :- (%) LOW: MOD: HIGH:

PRF :- (%) LOW: MOD: HIGH:

All additional pegs required in place :- (Y/N)

Plans up to date :- (Y/N)

Layouts out and signed by all depts. :- (Y/N)

tons @ g/t

= 0 kg Au

Estimated tons and contents of mud in x/cut:

Remarks:

SIGNATURES:

Chief Gold Loss Officer: Date:

Section Surveyor: Date:

PILLAR No.

BLOCK No.

TAUTONA MINE

W

ORKI N G

P L A C E

CHECKLIST

Old gold / Lockup :-

BL O C K

N o s.

P I L L AR

N o.

Section 4: Section Surveyor



27

WORKING PLACE

SECTION 5 - M/O UNDERGROUND INVESTIGATIONS

i) State of working places:

Haulage _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

X/Cut _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Timber _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

bay _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

T/Way _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

B/Holes _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Cost estimate of opening up old areas to acess pillar:

a)Wet bulb:- b)Dry bulb:-

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

iv) Stoping layouts or pegs reqiuired: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

) Equipping required: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Cost estimate of equipping pillar:

vi) 2nd Escapeway:

In place YES NO

Condition GOOD FAIR BAD

Layout required YES NO

Comments _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ __ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

ii) Special requirements: _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

_ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _ _

Signature :- Date:

i) Development layouts or pegs required

R

BL O C K

N o s.

ii) Temperatures:

P I L L AR

N o.

BLOCK No.

PILLAR No.

TAUTONA MINE

W ORKI N G

P L A C E

CHECKLIST

R

Section 5: Mine Overseer U/G Investigation



28

PILLAR No.

M/Overseer: Date: JUL 01 BLOCK No.

Working place:

Plan scale 1: 1000

3. Is the ventilation adequate?

What is required?

4.Tracks: are they required?

How many lengths?: Sleepers?:

5. Where do the pipes end?

Peg +\- :

6. How many air/ water pipes needed?

Sizes

7. Boxfronts: condition?

Can they be used?

Do they contain ore?

8. Are grizzlies available? Condition:

9. New B/HOLE required?

10. New T /WAY required?

11. No. of equipping shifts needed:

12. Cost of opening up (new dev excluded):

R

Mining comments: ESH comments:

This pillar IS / IS NOT mineable. This pillar CAN / CANNOT be mined safely.

OLD AREA PILLAR INVESTIGATIONMINE

TAUTONA

Old Area Pillar Investigation



29

WORKING PLACE

Mine Design

Provisional mining layout on CAD taking the current

Geological structure on CAD, the underground

investigation (App.) and Rock Engineering (App.) into account.

Cost treated (excl.dev.costs) R

Development costs R

Flat equipping costs, R/m R

HLGE required : (metres)

RAW/Conn.X/C required : (metres)

X/Cut development required : (metres)

Raise/slusher required : (metres)

BH / Orepass required : (metres)

T/Way required : (metres)

Timberbay required : (metres)

Flat re-equipping required : (metres)

Total Pillar Access dev.costs MODE R

Total Capital development co MODE R

Total Stoping costs : MODE R

Total Mining costs,(excl.D/dr il MODE R

Start date for minin Area that can be mined per year (M2) 2400

CAD Design File No

Copy of 1:1000 design to be attached.

ASSESSMENT : This pillar IS / IS NOT mineable.

Signature : Date:

M SLUSHER + M RSE

PILLAR No.

BLOCK No.

SECTION 6 - MINE DESIGN

TAUTONA MINE

P I L L AR

N o.

W

ORKI N G

P L A C E

BL O C K

N o s.

Section 6: Mine Design



30

Appendix F1

PILLAR No.

M/Overseer: Date: BLOCK No.

Working place:

Plan scale 1: 1000

Hlge.

X/Cut

T/Way

Slusher

B/Hole

TOTAL

Mine design/planning comments:

Mining comments:

Rock Engineering comments: ESH department comments:

STICK PLAN ONTO THIS PAGE

DEVELOPMENT PLAN REQUIRED FOR PILLARTAUTONA

MINE

Development Plan



31

0.0271

DATE 1 LPI TOTAL STOPING COSTS INCLUDING STORES (BUDGET 2005)

MCF Plant REC. G

% %

R/ton

R/ton

R/m

Plant REC. T

%

26

28

36

70

TOTAL

WORKING PLACE H W SG R/ton M2 COST (R/M2 COST I

HLGE 3.4 3.0 2.78 264 42028 094 3RAW / CON.X/C 3.4 3.0 2.78 0

CROSSCUT 3.2 3.0 2.78 281

RAISE + SLUSHER 3.0 1.8 2.78 500

BOXHOLE 1.2 2.4 2.78 937

TRAVELLINGWAY 2.4 3.0 2.78 0

TOTAL

PLANNED DEV.RATE; m / mth

2

STOPING,

DEVELOPMENT,

TOTAL ENGINEERING

FLAT RE-EQUIPPING,

DIAMOND DRILLING

WHEN CAN STOPING START ? Date :

PLANNED FACE ADVANCE m./mth.:

PLANNED WORKING PANELS No.:

PLANNED WORKING F/ LENGTH m.:

PLANNED MINING RATE m² / mth.:

PLANNED AREA TO MINE m².:

ESTIM.TIME TO COMPLETION Mths.:

40875

70047

4290

11855 100

105

120

30

900000

DEVELOPMENT COSTS

22.5

4056

0

TOT.STOPE TRE

0 0

TOT.DEV. COST

TREATMENT COSTS

4421

COST

225000

113896

SECTION 7 - FINRISK

AILABLE - FLBLOCK No.

INCLINED M² SW

BLOCK

LEVEL

STOPING TO BE DONE

MINED

LINE

GRADE

cm. g/m² Kilograms Au

TONS

OREx°

REEF DIP STOPE STATS

CONTENTS

UNIQUE PILLAR No.

21182

100%

90.3222.533331007816781613027

119.81

85.03

85.03 97.57

MCF

FACTORS

465

Full Width

88,007,051

UNIT COST

4th3rdIN 24IN 18

YEAR YEARMTHSNOW

MTHS

IN 6 IN 12

0

AVAILABILITY AND MINING RATEAS PER

MTHS MTHS

42028

24525

cm.g/t

2574

23.0

7113 23.0

2574

23.0

GROUND AVAILABLE (MRIS)

42028

100.0

100

4205

100.0

0

60% 0% cm.

7500851

7113

23.0

TONS

DIAMOND DRILLING COST

ESTIMATED TIME TO COMPLETION: mths

5,287,500

+ PORTION OF OTHER COSTS **

R/rec.gm.#DIV/0!

705

RECOVERED GOLD,

FINANCIALS

%

STOPING COSTS

TOTAL REVENUE (RAN

DEVELOPMENT COSTS

97.57

R/rec.gm.

ItemREVENUE

STOPING COSTS

852

267

706

2795

19276

6976

66463

TAU TONA MINE- SECTION 311

11389623.0 109.9322.5

3829 22.5

22.5 113.96

Item

% M² % M² UNIT COSTS USED IN INVESTIGATION

Unit Costs

STOPING

NEW DEVELOPMENT

FLAT END RE-EQUIPPING

FLTING

STOPE SHEET BLOCK No.

DEVELOPMENT SHEET PANELS

100

SW Full Width

CW VALUE

(MRIS)

4620

24525

103.77

METRES

450 6755 7500

2802

0

R/m *Dev

3375000 COSTS7875007500

16.13 AVG Tons / M TOTAL MINING COST

961

0

7500

0

11369 *Standard VR

TREATMENT AND OTHER COSTS PROFIT / LOSSR/rec.gm.

ITEM

Profit/Revenue %(R/ton) 113896 0

T (R/t & R/m)

(R/ton) 6755 0

TONSDIRECT COST

TOT.DEV. TREAT.

(Rand) 00

OTAL TREATMEN(R/ton) 0

(Metres) 0

Section 7: Financial Risk



32

WORKING PLACE

SECTION 8 - ROCK ENGINEERING

a). Is the pillar seismically active ? Rating

b). What is its seismic history ?

a). Is this a stabilising pillar ?

b). Pillar and Regional stability.

a). Primary :- X/cut

T/way

B/hole

Timber bay

Other

b). Secondary :-Haulage

X/cut

T/way

iv) Stoping method:

ASSESSMENT : This pillar CAN / CANNOT be mined safely.

Signature : Date :

W

ORKI N G

P L A C E

BL O C K

N o s.

ii) Stability:

iii) Development support recommendations:

i) Seismics:

v) Are proposed accesses overstoped?

vi) Development sequencing:

vii) Special instructions:

P I L L AR

N o.

PILLAR No.

BLOCK No.

TAUTONA MINE

Section 8: Rock Engineering



33

WORKING PLACE

SECTION 9 - SHE DEPARTMENT

i)Ventilation & Refrigeration

a). Air availability in the area

b). Requirements and Layout.

ii) Temperatures: a). Wet bulb :- b). Dry bulb :-

iii) What is the Kata in the area ?

iv) Nearest Refuge Bay:

v) Escape routes:

i) Methane and water: CH4 = % H2O (l/hr) =Precautions :-

Special instructions ?

ASSESSMENT : This pil lar CAN / CANNOT be mined safely.

Signature : Date

P I L L AR

N

o.

W

ORKI N G

P L A C E

BL O C K

N o s.

PILLAR No.

BLOCK No.

TAUTONA MINE

Section 9: SHE Department



34

WORKING PLACE

SECTION 10 - ENGINEERING DEPARTMENT

i) Telephone requirements:

ii) Lighting requirements.

iii) Cable requirements:

iv) Water, air and refrigeration requirements:

v) Other electrical requirements:

vi) Special instructions ?

Signature : Date:

P I L L AR

N o.

W ORKI N G

P L A C E

BL O C K

N o

s.

PILLAR No.

BLOCK No.

TAUTONA MINE

Section 10: Engineering Department



35

PILLAR VIABILITY INVESTIGATION

SUMMARY SHEET

Unique Pillar No.

Working placeMeasured or Indicated Resource Block Nos.

Area to be mined :- (M²) (70% OF TOTAL)

Reef Extraction ratio :- (%)

Off Reef Mining percentage :- (%)

Grade, (mode over full C/Width) :- (cm.g/t.)

Stoping SINGLE or DOUBLE CUT:-

Reef stripping potential :-

HW thickness :- (cm)

Full C/Width (cm)

Footwall thickness :- (cm)

RGSW :- (cm)

Tramming Width :- (cm)

Old gold / Lockup tons @ g/t.= Kg. Au

MCF for the pillar :- (%)

Plant Recovery Factor :- (%)

Estimated D/drilling costs, R

Total Pillar Access costs :- R

Total Capital costs :- R

Total stoping costs :-, R

Total working mining costs :-, R

Gold price used :- R/Kg.

Curr.Breakeven gold price:- R/Kg.

Total revenue :- R

Total Recovered Gold :- Kg.

R

FINAL ASSESSMENT :COMMENTS :-

Signature : PILLAR GEOLOGIST Date:

F

r o m F

i n r i s k

T O T A L

P R O D U C T I O N +

C O S T S

S T O R E S + C O R P O R A T E

N/A

TO BE CALC.

0

0

LOM DCF - Operational

PROFIT or LOSS :-

TAUTONA MINE

(ORIS)

#REF!

Pillar Viability Investigation



36

Geology Manager comments:


Signature :- Date:

Chief Surveyor comments:


Signature :- Date:

Section Manager comments

ASSESSMENT : This pillar CAN / CANNOT be mined safely and profitably.

Signature :- Date:

Production Manager comments:

ASSESSMENT : This pillar CAN / CANNOT be mined safely and profitably.

Signature :- Date:

MRM comments:

FINAL ASSESSMENT :

This pillar CAN / CANNOT be mined safely and profitably.

Signature :- Date:

0

Pillar Viability Investigation (continued)

reef adjacent tau tona aga

Documents