Consulting Engineers & Project Managers · Shaft Sinkers (Pty) Ltd. Title: Presentation to AMRE- No 16 Shaft rope accident Author: Diana Created Date: 3/22/2007 3:34:54 PM ...
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Consulting Engineers & Project Managers
PRESENTATION TO THE A.M.R.E.
DESCRIPTION OF AN ACCIDENT TO THE No 16 SHAFT KIBBLE WINDER
WINDING ROPE
Shaft Safety Seminar – 8 March 2007
Mathew Watt
Consulting Engineers & Project Managers
No 16 Shaft Project
Where?
Forecast completion date?
Production rate?
EPCM?
Shaft Sinking contractor?
Safety?
Consulting Engineers & Project ManagersDescription of the winding equipment
Slinging the drill jumbo to shaft bottom Sinking stage
Four drum stage winder Construction of headgear chutes
Consulting Engineers & Project Managers
5,5 m kibble winder
16 ton payload kibbles
4 drum stage winder
120 ton stage (suspended from eight falls)
4,8 m sinking service winder
Kibble ropes: 48 mm 18 strand “Fishback” non spin
Extract of rock process flow diagram
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Extract from the general arrangement drawing of the headgear kibble tipping system
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Description of the accidentOn the 11 December 2006 the following happened:
The underlay kibble was in the process of being tipped
The lazy chain hook detached from the oblong link
The kibble swung uncontrolled into the swing chute of the overlay compartment
The force of impact was sufficient to open the swing chute into the compartment and trap the winding rope between the stationary and swing chute
Consulting Engineers & Project Managers
Photograph showing the relative position of the swing chute, winding rope and stationary chute (from above)
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Photograph showing the extent of deformation of the winding rope
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Photograph showing the winding rope (from below)
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Findings of the investigating teamLashing operations had not been carried out in the proceeding 7 hours
The pneumatic system is equipped with a supply side shut off valve. At the time of the accident the system was un pressurised
The WED witnessed the detachment of the lazy chain from the oblong (via Closed Circuit Camera and drivers display)
The winding rope was flattened to about 25 mm thick
The extent of damage could not be ascertained
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Extract from the general arrangement drawing of the headgear kibble tipping system
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Returning the winding system to normal operationThe suspended portion of the overlay rope was secured to the bank steel work
The overlay swing chute was secured by means of a chain block
The overlay swing chute was returned to the closed position using the pneumatic system
The damaged area of the rope was lowered to the bank for inspection
Consulting Engineers & Project Managers
Consulting Engineers & Project Managers
Observations made following the visual inspection:
• One broken wire in strand 1• One broken wire in strand 2• Damaged wires in strands 3 and 4• Two broken wire in strand 5• Damaged wires in strands 6 to 12• The displacement of the broken wires was measured as 1 m• Severely disturbed strand pattern
Returning the winding system to normal operation
Consulting Engineers & Project Managers
Consulting Engineers & Project Managers
Consulting Engineers & Project Managers
Consulting Engineers & Project Managers
Consulting Engineers & Project Managers
Electro magnetic testing was conducted 70 m above and 20 m below the damaged area
The instrument showed a slight loss in steel area
Loose ends of the broken wires were removed
The displaced strand was returned to its normal position
Returning the winding system to normal operation
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EMT – 18 December 2006
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Photograph showing the rope during repairs
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Photograph showing the rope after repairs
Consulting Engineers & Project Managers
Photograph showing the rope after repairs
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EMT – 12 January 2007
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The impact of the broken wires was assessed in accordance with the code of practice “ Condition assessment of steel wire ropes on mine winders” – SANS 0293
The operation of the pneumatic system for the swing chutes was proven
The winder was returned to operation (8 hours delay)
Returning the winding system to normal operation
Consulting Engineers & Project Managers
Application of SANS 0293The presence of broken wires was determined to have been of no significance
The variation in lay length exceeded that as recommended in 5.10.3 paragraph b (12 % deviation)
Consulting Engineers & Project Managers
Consulting Engineers & Project Managers
Consulting Engineers & Project Managers
Long term prognosisOwing to the position of the broken wires and the proximity of another wire crossing over other wires which could not be rectified in the repair, which had the potential to be cause fordiscard, it was considered best to substitute this rope with the spare
The rope change was planned and completed on 27 January 2007
The damaged rope is now held us the “statutory spare”
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Lessons learnedPneumatic system:System needs to be continually pressurised to ensure the chutes remain in the “home” position
Swing chute design:Eliminate the contact point between the stationary and swing chute
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Remedial actionsInstallation of a cylinder to positively lock the swing chute inthe home position
Continuous monitoring of pneumatic system pressure
Master isolating valve changed from normally closed to normally open
Design changed initiated to eliminate the nip point
Consulting Engineers & Project Managers
Consulting Engineers & Project Managers
Consulting Engineers & Project Managers
ConclusionWith a considered approach and calm heads – significant shaft sinking time was saved as well as the cost associated with discarding the rope
Pneumatic systems need to be assessed to understand what happens in the event of a lack of system pressure
Consulting Engineers & Project Managers
AcknowledgementsImpala Platinum - Rustenburg Operations
Shaft Sinkers (Pty) Ltd
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