mechanised on reef raising at free gold`s bambanani mine

MECHANISED ON REEF
RAISING AT FREE GOLD’S
BAMBANANI MINE
050RUWORFN
Mine Manager, Free Gold - Bambanani Mine
N
Which is incidentally………..
z
The same height as
– BIG BEN
z
At the northern end
rises the Clock Tower,
a great symbol of
London with the
famous clock "Big
Ben", and 96m (316ft)
high itself
9 Contents
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Bambanani
The Problem
Why the Alimak?
The Project
Conclusions
The Future
Questions
BAMBANANI
zA
few general facts about the mine
– Part of the original President Steyn Gold Mine
– Known as Steyn 4
– Then Free Gold 1
– Then Bambanani
– Now Free Gold – Bambanani Mine
– After 23 rd September, 2003
z HARMONY – Bambanani Mine
Depth
9 Bambanani is the deepest mine in the Free State
with operations extending beyond the 3,000metre level, where virgin rock temperatures can
reach an exceptionally high 62ºC.
9 Sub Shaft Bottom at –3264 metres below surface
9 98MW installed cooling
Shaft System
z
z
Bambanani has one operating shaft, East Shaft
commissioned in the mid-1970s, and a sub-shaft
being added in the early 1980’s, which hoists
some 130,000 tpm.
Brattice walled for upcast ventilation
Seismicity
z
Bambanani’s depth and the nature of its geology,
including numerous local aberrations, have
meant that mining sequencing has become
essential in the management of seismic risk.
9 Ore reserve development is conventional hand held
drilling on day shift and compressed air loading for
cleaning on night shift. At present some 1400 metres are
developed monthly.
9 Raises situated 150 metres apart on strike are down
dipped ledged, equipped and stoped out on breast to the
limit line. Panels average 25 metres in length, each
served by its own gully and ore pass. Limited centre
gully scraping takes place. Some 22 000 m² are stoped
per month.
THE PROBLEM
Sub Shaft History
During the sinking stage of
the sub shaft a decision was
made to not develop 98 , 93
and 89 levels. The stations were cut to just off the
shaft barrel.
The idea was to reduce the number of operating levels
off the sub shaft and to speed up development on the
other levels. At some stage incline shafts would be
raised from 100 , 95 and 91 Levels creating the inter
levels of 98 , 93 and 89.
Bambanani Sub Shaft Levels
85
87
89
91
93
95
98
100
103
Inter Level Inclines
As is well known, the raising of an incline shaft the
establishment of an interlevel and the equipping thereof is
no easy task. The 100 – 98 incline system was started in
1996 and will be completed by September 2003. A period of
some 8 years.
The result of this is that 98 level lags some 800m from 95
level and 450 metres from 100 level.
Bambanani Sub Shaft Levels
85
87
89
91
93
95
98
100
103
Raise Development
To generate ore reserve it is
necessary to raise from 100 level
to 95 level, by-passing 98 level, an
incline distance of in excess of 200
metres and at a dip of in excess of
40º.
Conventional Raising
• Attempts were made to do this conventionally in
the past but as the raised approached the inter
level elevation efficiencies became too poor and
conditions deteriorated making the raise
hazardous to develop.
• A decision was taken to not develop above one
level.
Credit
z
z
In the late 1990’s Anglogold set up New
Technology Forums and this problem was one
tasked to them. The idea of a Raise Climber was
looked at by the team and the would have started
the project had it not ben for the sale.
The decision was made by Free Gold in February
2002 to go ahead with the project.
WHY THE
ALIMAK?
THE ALIMAK RAISE CLIMBER.
9 The Alimak is by no means new technology, they
have been around since 1948 . The over 2300 Raise
Climbers delivered so far have been used to drive more
shafts and raises than any other system; in all kinds of
rock, pilot and full-face, vertical and inclined, and even
for raise and vein mining.
9 The Alimak Method consists of five steps which make
up a cycle: Drilling, Loading, Blasting, Ventilation and
Scaling. The Raise Climber serves both as a work
platform and as a means of transport to the work site.
9 It runs on a guide rail anchored to the hanging wall.
Using curved guide rail sections, the direction of travel
can be changed at any time; forward, backward or
sideways.
9 Alimak Raise Climbers are available with air, electric
or diesel/hydraulic drive units. The longest shaft driven
in one step so far is 1050 m (Norway). The platform can
be any shape and size. The largest work platform
supplied so far measured more than 30 sq.m.
THE PROJECT
THE ALIMAK RAISE
CLIMBER
AT BAMBANANI
The decision was made to not purchase the
equipment but to utilise a contractor on a blasted
unit rate to develop the raise.
The contractor chosen was Welprop Mining Services
who were tasked at preparing the cross cut and to
develop a standard raise from 100 level to 95 level.
The raise was developed conventionally for 18 metres
prior to the installation of the equipment. A further 15
metres was developed when deterioration of the side
walls started. It was decided to ledge this out and install
cementitious packs and then to continue advancing by
means of a T raise and a stoping width of 1.2 meters.
This also proved to be unsuccessful as the
sidewalls of the raise below the packs also
deteriorated causing the support to fall out.
The final decision was to take a full reef cut of 2.2
metres and 6.6 metres wide.
This method was used until the stopping distance just
below 95 level. A travelling way was then blasted from
the wide raise to the cross cut on 95 level.
Night Shift:
Winch
Team
Team Leader
TOTAL
2
1
1
4
Crew Day Shift:
Drillers
3
Team
6
Loco
2
Winch
1
Team Leader
1
TOTAL
13
Travelling Time:
Midway: 5 minutes up
5 minutes down
Top: 13 minutes up
13 minutes down
Drilling Pattern:
Full Cut: 2.2m stoping width
4 rows
61 holes
Breaking Point – 5 hole burn c
Explosives:
Anfex
Fuses and Igniter Cord
Time Blasting
THE PRODUCTION
RESULTS
Reef Metres Raised per Month
25
20
15
10
5
0
Jan Feb Mar Apr May Jun July Aug Sept Oct Nov Dec
Prog Reef Metres Raised per
Month
250
200
150
100
50
0
Jan Feb Mar Apr May Jun July Aug Sept Oct Nov Dec
Square Metres Achieved per
Month
140
120
100
80
60
40
20
0
Jan Feb Mar Apr May Jun July Aug Sept Oct Nov Dec
Prog Square Metres Achieved per
Month
900
800
700
600
500
400
300
200
100
0
Jan Feb Mar Apr May Jun July Aug Sept Oct Nov Dec
THE STANDARDS
3.3m
3.2m
2.5 m
Alimak Raise
Gully Center line
1m
6.6m
2.4m
2.3m
Section view
2m
2.3m
Not to scale
Alimak Raise
Tendon support
Elongate
Service way
150cm x 120cm Durapak
Traveling way
Row of slab lagging
on base of pack
Not to scale
Section view
Mining &
support
sequence
Temporary support
Tendons
1.5m
0.2m
Elongates
120cm x 120cm
Durapak
1.0m
1.0m
2.0m
1.5m
0.5m
Plan view
Not to scale
0.5m
Mining &
support
sequence
1.5m
0.2m
1.0m
1.0m
2.0m
1.5m
Not to scale
Plan view
Mining &
support
sequence
1.5m
0.2m
1.0m
1.0m
2.0m
1.5m
Plan view
Not to scale
Mining &
support
sequence
0.2m
1.0m
1.0m
2.0m
1.5m
Not to scale
Plan view
Mining &
support
sequence
0.2m
1.0m
1.0m
2.0m
1.5m
Plan view
Not to scale
Mining &
support
sequence
0.2m
1.0m
1.0m
2.0m
1.5m
Not to scale
Plan view
Support sequence
9 Durapak max 4.5m after blast from face.
9 With 0.5m required between face and support before
blast.
9 1,2m face advance per blast.
0 .5
m
Section view
Not to scale
Support sequence
9 Durapak max 4.5m after blast from face.
9 With 0.5m required between face and support before
blast.
9 1,2m face advance per blast.
1 .7
m
Not to scale
Section view
Support sequence
9 Durapak max 4.5m after blast from face.
9 With 0.5m required between face and support before
blast.
9 1,2m face advance per blast.
2 .9
m
Section view
Not to scale
Support sequence
9 Durapak max 4.5m after blast from face.
9 With 0.5m required between face and support before
blast.
9 1,2m face advance per blast.
4 .1
m
Not to scale
Section view
Support sequence
9 Durapak max 4.5m after blast from face.
9 With 0.5m required between face and support before
blast.
9 1,2m face advance per blast.
3 .2
m
2 .0
0 .9
m
m
Section view
Not to scale
Support sequence
9 Durapak max 4.5m after blast from face.
9 With 0.5m required between face and support before
blast.
9 1,2m face advance per blast.
m
3 .2
2 .1
m
Not to scale
Section view
Support sequence
9 Durapak max 4.5m after blast from face.
9 With 0.5m required between face and support before
blast.
9 1,2m face advance per blast.
3 .3
3 .2
m
m
Section view
Not to scale
Support sequence
9 Durapak max 4.5m after blast from face.
9 With 0.5m required between face and support before
blast.
9 1,2m face advance per blast.
4 .5
3 .2
m
m
Not to scale
Section view
Support sequence
9 Durapak max 4.5m after blast from face.
9 With 0.5m required between face and support before
blast.
9 1,2m face advance per blast.
1 .3
3 .2
m
Section view
2 .0
m
m
Not to scale
Support sequence
9 Durapak max 4.5m after blast from face.
9 With 0.5m required between face and support before
blast.
9 1,2m face advance per blast.
2 .5
3 .2
m
2 .0
m
m
Not to scale
Section view
Support sequence
9 Durapak max 4.5m after blast from face.
9 With 0.5m required between face and support before
blast.
9 1,2m face advance per blast.
3 .7
3 .2
m
m
Section view
Not to scale
Support sequence
9 Durapak max 4.5m after blast from face.
9 With 0.5m required between face and support before
blast.
9 1,2m face advance per blast.
0 .5
2 .0
3 .2
m
Section view
m
m
Support cycle re-start
Not to scale
THE CONCLUSION
The project has been a success in the following areas:
Safety:
Only one dressing case was recorded for the 12 month
period
Production:
Average advance below 98 level was 20 meters for the
wide raise per month.
Average advance above 98 level was 17 meters per month.
Sampling:
Full width stoping allowed the total channel to be sampled
Bambanani has a history of raising on bottom cut and
waste thus only allowing bottom cut sampling. This
method has improved the sampling statistics.
Costs:
Although not part of this presentation due to contractor
confidentiality the unit costs compared well with
conventional raising and ledging.
Overall Summary:
The project achieved its objective in that the raise was
successfully developed from 100 to 95 level.
The full width stoping has given us confidence in the values
of the area.
THE FUTURE
Due to the success of the project we extended the contract to the
next two raise lines, two units are now in operation.
The second raise is up 80 metres and the third raise is up 40
metres (both 6,6 m wide)
A forth site is being prepared as well
Our Dream
z Extend the width to 13
meters
z Maintain the same advance
z Replace Durapak with Lexus
z Equip gullies, winch beds and tips
z Reduce our ore generation time per raise
line by 9 months
13.0m
1.5m
0,7
m
1.0m
1.0m
2.0m
1.5m
0.5m
0.5m
Service way
150cm x 120cm
Durapak
Travelling way
Tendons
ACKNOWLEDGEMENTS.
My thanks to the following:
Peter Steenkamp. Operations Manager Free Gold for allowing me
to present this paper.
Welprop Mining Services, in particular Braam and Wally,for their
dedication to the Project and for research material for the paper.
Free Gold – Bambanani Mine Ore Reserve Department for their
assistance in obtaining plans, pictures etc for the paper and the
presentation.
Lastly to Dave Bowden, Shift Boss of Welprop, for his outstanding
commitment to safety, production and conditions in the actual mining
of the raises.
QUESTIONS
?
THE END