Northparkes Mines Winder East Skip Derailment Nathan Welsh, Senior Maintenance Engineer

Northparkes Mines

Winder Friction winder

Non Man Riding (Excluding

Maintenance & Emergency

Egress)

500 Metre Lift

MDG33 & MDG2005 Compliant

SIL Level 2 Compliant

Single materials handling

source of ore from the

Underground Mine

Winder Head Ropes Haulage Rope

Tail Ropes Balances Head

Rope Load

Guide Ropes Locates Skip in

Horizontal Plane

Guide Rope Weights Provides

Guide Rope Tension

Arrestor Frame Physical Barrier

E-Cam Communication from

Skip Devices to PLC, Utilises

Head & Tail Ropes to Transmit

Fixed Guide Operation

Fixed guides are

installed at the skip

loading and

unloading points

Prevents horizontal

movement of the skip

when loading and

unloading

Fixed Guide Operation

Incident Details

Time and Date of Incident: 1:38am

10th of March 2015

Incident Location: Main Winder

Loading Station Docking Point

Duration: 9140 minutes (6.3 Days)

Incident Aftermath

Lower Shoes on East Skip Did

Not Engage with Fixed Guides

Four Structural Beams Damaged

East Skip Stuck on Fixed Guides

at Loading Station Docking

Point

Timeline 01:35:49 Winder Tripped E-Cam Fault & Tub Latch Fault

@ Fresh Air Base

01:45:20 Winder Started in Manual

Lower Shoes on East Skip Do Not Engage with Fixed Guides

01:45:36 Winder Tripped E-Cam Fault & Tub Latch Fault

Timeline 01:47:10 Winder Started in Manual

01:47:15 Winder Tripped E-Cam Fault & Tub Latch Fault

Post 01:47:15 Maintenance Technician Calls SCADA to Shutdown

Winder due to Loud Noise Winder is Isolated East Skip

Derailment Identified

Photos

Investigation Investigation Item Outcome

Misalignment of Conveyance Due to ballast weight, liners, ore hang up, or skip moving within the bridle Disproved

Misalignment of Fixed Guides Due to impact damage (prior to incident), fatigue, or corrosion Disproved

Uncontrolled Entry into Fixed Guides Due to fault in the winder control code or elongation of the head ropes Disproved

Induced Conveyance Oscillation Due to loose or worn guide rope shoes/slippers, air flow, or obstruction in shaft Disproved

Guide Rope Oscillation Due to failure of stauff clamps or insufficient guide rope tension Disproved

Investigation Investigation Item Outcome

Misalignment of Conveyance Due to west shoe failing when struck by fixed guide Contributing Factor

Induced Conveyance Oscillation Due to acceleration/deceleration when restarting mid shaft in Contributing Factor manual, insufficient guide rope lubrication, or the skip stopping in a zone of high turbulence (fresh air base)

Investigation reviewed by OEM and 3rd party

Contributing factors identified but root cause could not be verified

3rd party modelling could not replicate incident using known

parameters

Controls Contributing Factor Countermeasure/Control

Misalignment of Conveyance West Shoe Failed When Struck by Fixed Guide

Induced Conveyance Modified control system so that skip will slow Oscillation: to 1 m/s at 25 metres above the fixed guides - Accelerating/Decelerating when in manual

when restarting mid shaft Greased guide ropes and confirmed 4 - Insufficient Guide Rope

weekly guide rope greasing is active inLubrication system - Shaft Air Flow

In addition Northparkes Mines is investigating the option of increasing

guide rope weights to reduce conveyance oscillation

Updated 4 weekly winder inspection with criteria and actions for visual inspection of the guide shoes

Summary Winder tripped 3 times on e-cam & tub latch fault

Lower Shoes on East Skip Do Not Engage with Fixed Guides

between 1st and 2nd trip

Multiple contributing factors were identified in the

investigation however a root cause cannot be validated

Actions were implemented to control identified contributing

factors before resuming production

Additional countermeasure is under investigation

Slide Number 1Northparkes MinesWinderWinderFixed Guide OperationFixed Guide OperationIncident DetailsIncident AftermathTimelineTimelinePhotosInvestigationInvestigationControlsSummary