- [Narrator] The New South Wales Resources Regulator
provides safety information to mine operators
in the New South Wales mining industry
to help achieve safe mining operations.
To comply with mining regulations, mine operators
must develop and implement principal control plans
including a mechanical engineering control plan.
When incidents such as an unintended release
of mechanical energy occur, mine operators must review
and revise control measures at their mine sites.
We have reviewed control measures associated
with two lateral load shifting incidents
that occurred in 2019.
Since 2015, 81 incidents have occurred in the New South Wales
mining industry involving lifting, towing and snigging.
Thirty-seven of these incidents resulted
in workers being injured.
We have published information on our website
about these two lateral load shifting incidents.
The first was an investigation information release
titled "Worker injured releasing jammed conveyor chain"
and the second was a safely alert titled "Flight bar
ejects hitting worker while installing a conveyor chain."
Both of these are available to download from our website
at www.resourcesregulator.nsw.gov.au.
The Armored Face Conveyor, known as the AFC,
had a flight bar jammed in the bottom race
on an earlier shift.
It was possible the chain or a flight bar
had been damaged while freeing the chain.
The workers had tried to use the pivot arm tensioners
to slow run the AFC but the tailgate pivot arm tensioner
was not operational.
It was determined the main gate drive pivot arm tensioner
would be operated in reverse and the shearer would assist
by pulling the slack AFC chain from the maingate drive.
Workers were tasked with inspecting
the AFC chain for damage.
The inspection required running the AFC chain in reverse.
The towing assembly used consisted of recovery strops,
synthetic rope, bow shackle and a Rud link.
Shortly after the load was applied to the towing assembly
by tramming the shearer, the Rud link failed.
The bow shackle and rope recoiled back
towards the three workers at the maingate.
The bow shackle hit the shearer operator
on the lower right leg.
This diagram shows the lateral load transfer system
that the workers set up.
Two 50 tonne Kevlar tow strops were used.
A strop connected each strand
of the AFC chain to the tow rope.
A single 42 millimetre synthetic rope was connected
between the tow strops to a large bow shackle.
A bow shackle connected the rope to the shearer.
The shackle had a working load limit of 35 tonnes.
The attachment point on the shearer
was an eight tonne Rud link.
The workers did not know the tractive effort of the shearer.
It was capable of a maximum tractive effort
of about 56 tonnes.
The tractive effort of the shearer could have been reduced
by disengaging one of the two drive motors.
A safe working procedure did not exist for this task.
The previous shift had conducted a JSA
but this was not used.
The workers did not review the JSA
nor conduct their own JSA.
The workers had not completed the required training.
Three workers were in the vicinity of the maingate
ramp pans to inspect the AFC chain
as it moved around the maingate drive.
The shearer operator was in the roof support walkway,
about 22 metres or 15 roof supports,
from the failed connection point on the shearer.
Because the Rud link failed on the shearer
the release of energy caused the rope in the large shackle
to recoil towards the workers.
Two other workers were also at risk of being hit.
This diagram shows the rated capacity and the breaking load
for each component in the lateral load system used.
When the breaking load of the components are compared
the weakest component in the system was the Rud link
with a breaking load of 32 tonnes.
The shearer was capable of exerting
up to 56 tonnes of pull force,
therefore exceeding the strength of the Rud link.
Independent metalergical analysis identified
the Rud link fractured across two opposite corners.
There was no fatigue or preexisting cracks
on either fractured surface.
The deformation of the Rud link indicated a sideways
and twisting loading of the link was not
in accordance with its intended use.
Our investigation information release provides
information about the incident
and how to safely use a Rud link.
The shearer original equipment manufacturer
has also published a technical bulletin
on the use of lugs and links fitted to the shearer.
Although the breaking load has been discussed
the working load limit is the primary rating used
to select components for lifting and snigging applications.
The conveyor chain had broken on a continuous miner
and was being reinstalled.
An LHD and QDS winch were being used
to pull the chain back onto the miner.
As the chain came around the foot shaft sprocket,
a flight bar jammed.
One side of the flight bar failed and was ejected,
striking a worker in the shoulder.
Other workers nearby were also placed at risk.
This diagram shows the lateral load transfer system
the workers set up.
A QDS winch on an LHD was connected to the chain
by a 22 millimetre sythetic winch rope.
The capacity for the winch was about 10 tonnes.
The 22 millimetre synthetic winch rope
had a yield capacity of 42 tonnes.
A three tonne rated sling was looped around
each side of the flight bar and threaded
through the eyelet of the rope.
The load on the system at the time of failure
was not known, as the conveyor chain jammed.
One side of the flight bar failed and recoiled
towards the spotter, who was on the platform.
The workers did not have a safe work procedure for the task.
The manufacturer's manuals did not provide specific
information about where, or how, to connect the rope,
nor details of how to pull the conveyor chain
onto the miner.
No-go zones were not specified.
A worker was on the platform
with a continuous miner acting as a spotter.
A second worker was adjacent to the boomer,
the continuous miner, acting as a spotter.
A third worker was standing beside the winch.
A fourth worker was in the LHD operating the wind.
The worker standing on the platform of the continuous miner
was hit in the shoulder by the flight bar when it failed.
The other workers were also at risk if the load transfer
system had failed in a different way.
Before the incident, the 22 millimetre
synthetic rope had failed.
The rope was repaired and the task continued.
The initial failure was not reviewed nor assessed
and the workers did not put additional
risk control measures in place.
This diagram shows the breaking load for each component
in the lateral load transfer system.
The winch was hydraulically set up to apply a 10 tonne load.
The breaking strength of the flight bar was unknown
but was not expected to fail.
For a task set up in this manner the LHD should never
be driven, as the maximum tractive effort
of the machine becomes the load.
In reviewing both of these incidents,
similar causal factors were identified.
There was no safe work procedure existing for either task.
The weakest components were not identified
because the breaking loads of each
of the components were not understood.
There were problems with training and competency of workers
and supervisors were not present during both tasks.
In review of both case studies there were similar
causal factors identified.
Connection point strength was less
than the load used for the task.
The weakest links were the connection points selected,
incorrect no-go zones were identified
and earlier events before each incident
of equipment failures had not been reported
and reviewed by supervisors.
Our recommendations.
Develop safe work procedures for lateral load tasks.
Dynamic lateral shifts are complex tasks.
The New South Wales Resources Regulator
recommends the following.
Mine operators should review their lifting
and towing equipment management plans
to ensure all activities using lifting and towing equipment
are appropriately addressed,
including non-routine towing activities.
Mine operators must provide adequate information,
training and instruction to protect workers
from risk while carrying out lifting and towing tasks.
Mine operators should seek the appropriate
engineering advice in the design and selection of equipment
when conducting complex lifting and towing tasks.
If the ratings and strengths of any components are unknown
stop, seek advice.
When planning a task involving lifting or towing
the rating and yield load of all components,
including the connection points,
must be considered in the design
of the lifting or towing system.
Additionally, the structure supporting the connecting point
should also be considered.
People designing towing, pulling or snigging activities
must know and understand the maximum forces
capable of being applied to the system,
such as tractive effort or weight force.
Safe standing zones must be established
to account for component failures within the system.
Mine operators should review compliance reporting systems
to ensure workers notify a supervisor
when pulling and lifting failures occur.
Workers should not resume the pulling or lifting task
until supervisors are notified of the failure
and the incident is reviewed,
with additional controls put in place.