10# Crocodile derailment incident

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Presenter: Amos Xheko

AMRE Safety Seminar Date: 26/02/2019

Picture of the Crocodiles’ similarities

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Nile Crocodile Impala Crocodile

Presentation Overview

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❑ Introduction

❑ Decline Winder Specifications

❑ Drop raise Principle of Operation

❑ Sequence of Events Leading to the Accident

❑ Investigation

❑ Aftermaths

❑ Remedial Actions

Introduction to 10# incident of 14/11/2019

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Coll elev -696.00m

650m 9 Level -1340.000 -644.000 BC

10 Level -1411.400 -715.400 BC

11 Level -1476.400 -780.400 BC

12 Level -1541.400 -845.400 BC

13 Level -1604.400 -908.400 BC

14 Level -1671.400 -975.400 BC

Silo's ( 7 ) 440 ton@

1057m 15 Level -1736.400 -1040.400 BC

Decline shaft ore pass capacities

Pump Stn -1753.900 -1057.900 BC Level Waste Mer UG 2

Load Stn -1780.038 -1084.038 BC 16 Level -1795.0 -1099.0 BC 16 - 17 L 400 450 450

Shaft Bot -1827.505 -1131.505 BC 17 - 18 L 400 450 450

ChairLift

18 - 19 L 450 550 550Material Way1164m 17 Level -1850.0 -1154.0 BC 19 - 20 L 380 400 400

Material Way

Conveyor 18 Level -1905.0 -1205.0 BC

Ore Passes

1269m 19 Level -1960.0 -1264.0 BC

Vent-Hole

Conveyor

Fridge Plant9 MW - 4,91 C

2 x VK 32 Compressors

Man 15 m/s , 49mm, 3 deck (45) , C/W 90 cars per dayRock 15 m/s, 12.5t , 49 mm , 2,65 MW 5850t/d

#6.2 m Dia, 1131m deep4 Compartments

2 x 1,5 MW 6,6 Kv fans22.12 meters per second

ChairliftLength : 455 + 48 Angle = 14,5 Rope - 22mm 6x19(9-9-9-1)F RH BF 28,2 TonSpeed 1,5m/s 675persons/hChairs = 130 @ 7m/chairWheel dia + 1,5M

Conveyors6 off - 44m,130m,95m,669m,550m,275m (1798 m Total)

Speed ,1.6 m/s 250 kw drive motors1050mm & 1350mm width Angle = 11,5°350 tons/hour ave 6000t /day Reef & Waste7 Silo's 1600t reef & 800t waste

Decline WinderCrocodile (2 Cars) &C/Weight 62 cars per day 270 Kw, 26 Deg, 26 mm rope, 6 ton load 645 meter long shaft,4.5 m/s

5 # Fan1 x 6,6 Kv 932.5 kW 22.12 m/s , 433 m cub/s

Decline Winder Specification

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Description Details

Location Underground

Make IMG

Power 270kW

Drums Double

Speed 5 m/s

Main Brakes Calliper Brakes to each drum

Duty Material, men and rock

Inclination 26 deg

Licensed Yes

Length of Wind 500 m

Rope diameter 26 mm

Maximum Number of People 6

Marshall device

• Marshall device system used is a Guduza System Teschnology (GST)

• It consist of a eye that is mounted below the body of the Crocodile that constantly measures the distance to the rail

• When it detects the set distance variation it sends the signal via the I coil to trip the winder.

Note: When the Crocodile enters a station the drop set is lowered and the winder is put into a enforced creep and theMarshall is deactivated.

How? This is achieved by the drop set switch for the distance seen by the Marshall will vary as it enters the station and theoperating plane changes from 26 Degrees to horizontal.

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Drop Set Principle of Operation

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❑ Overhead drop sets are provided at each station landing and are lowered into the

shaft to move the conveyance between the shaft rails and the station landing.

❑ The lowering and raising of the drop set is achieved through the use of an

overhead Winch.

❑ Once the drop set is lowered, the winch rope is disconnected to allow the

movement of the conveyance between the shaft and the station landing.

❑ A safety hook is used to hold the drop set in its raised position.

❑ The safety hook is raised and lowered manually through the use of a fibre rope.

Drop Set Principle of Operation

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Safety Hook

Drop Set

Fibre Rope

Drop Set Principle of Operation

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Drop set lowered

Drop set in closed position

How to embark “ride” on the Crocodile

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Riding on a Crocodile

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Sequence of Events Leading to the Accident

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❑ On the 14/11/2018 at 16:55:51 the Onsetter gave a 4-1 signal to the Winding Engine

Driver to slowly go forward

❑ The WED proceeded to pull the conveyance towards the shaft.

❑ In the process the WED heard an unusual sound from the Winder motor and stopped the

winder immediately.

❑ The Onsetter gave a 1 signal again.

❑ The WED responded by locking the brakes.

❑ The Onsetter telephonically informed the driver that the Crocodile had derailed and that

two of her crew members were inside the Crocodile canopy.

❑ The WED made an entry in the WED logbook and immediate called the Operations

Engineer of the section.

❑ The Engineer informed the Mine Manager and the Engineering Manager.

❑ The Engineer and the Foremen then proceeded underground to the scene of accident to

conduct a preliminary investigation

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Bell and Event Recorder Report

Investigation

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❑ On arrival the Engineer and the Foremen established that the injured were safely

removed from the “Crocodile canopy” and thereafter gave them first aid.

❑ On the scene of accident it was discovered that the material car was lying in front of

the Crocodile and the front wheels still secured by securing hooks of the “Crocodile”.

❑ Close examination of the material car revealed a severe bend on the car and a dent

whose width corresponded to the width of the safety hook.

❑ The damaged material car on the drop set was removed and the Crocodile re-railed.

❑ During the trial run of the Winder it was further discovered that the front wheels of the

Crocodile were not running straight.

❑ The front wheels of the Crocodile and a damaged shaft fish plate were immediately

replaced.

❑ The DMR was informed about the accident.

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Position of the Crocodile & cars after the incident

Rear car

Front car

Crocodile

Position of hook after incident

Scene of Accident

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Position of the Crocodile & cars after the incident Position of hook after incident

Front Car

Scene of Accident

Wheels of the rear car

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Mark of the hook on material car Impact on the rear car

Scene of Accident

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Damaged Material Car

Damaged Material Car Front View Damaged Material Car Side View Material Car broken off Wheels

Aftermath

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❑Material cars were loaded and secured onto the “Crocodile”

❑ The two shaft helpers entered into the canopy while on the station landing

❑ The Onsetter signalled a 4-1 for the conveyance to be slowly raised without ensuring

that the safety hook is out of reach of the material cars

❑ The WED in response to the signal released the brakes and raised the conveyance

❑ The rear material car got hooked against the safety hook causing the Crocodile to

derail and as a result detached the front wheels of the first material car.

❑ As a results of the derailment the two shaft helpers got injured.

Remedial Actions

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Drop Set Position Alarm Adjustable Chain Latch

1. Installed a limit switch to activate an alarm whenever the drop set safety hook is not totally pulled in.

2. Installed an adjustable chain latch to compensate for the stretch of the fibre rope used to operate the safety hook

3. Re-visited the Risk Assessment and the SWP for the Crocodile

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THE END