| Collapse Scaffold |
26/04/2003 |
Following the installation of elevated pipe work at a methane utilisation plant on mine surface, a section of tower scaffolding over 5m high was found to have collapsed when contractors returned to the site after the weekend break. No one was injured and no one was working on the scaffold at the time. High winds over the weekend probably blew the unsecured tower over. A proper assessment would have identified this as a foreseeable event and enabled simple preventative measures to be put in place. |
| Failure of Plant-Shaft |
03/04/2003 |
During coal face salvage operations, a 6 tonne capacity air hoist bottom hook failed at the swivel section. The hoist was part of a complex lift used with a set of 4 tonne manual chain hoists to lift a 7.8 tonne pan set. The failed hook had been connected directly to the rack plate, which induced bending forces. Those involved had been advised of this well-known and understood problem but were all subsequently retrained. |
| Fall of Ground |
03/05/2003 |
A fall of ground occurred in a fenced off stub roadway in the driven in potash at a large, deep mine. Stub roadways are designed to collapse and provide stress relief on the main access roadways. On this occasion the collapse in the stub roadway extended slightly into the main travelling route and mineral spalled into this roadway. No one was hurt and the mineral, which spalled into the roadway, did not affect ventilation or egress. The maintenance crew leaving the district at the end of their shift discovered the fall. The mine will undertake a weekly review of extraction dimensions, extend the monitoring regime to include confirmation that tell tales are installed and record the readings, and examine the resource allocated to the geotechnical engineer. |
| Fan Stoppage |
01/04/2003 |
Booster fans were stopped for a period of 40 minutes when a defect occurred on 6,600-volt circuit breaker earth fault protection unit leading to a loss of power to the booster fans. The fans were restarted via the alternative supply. No adverse conditions arose from the stoppage. |
| Fan Stoppage |
01/04/2003 |
The power to the main fan was lost when a 3,300-volt coupler developed an earth fault. The sensitivity of 11kV and 3.3kV circuit breaker protection was checked pending the commissioning of planned improvements to the electrical distribution. |
| Fan Stoppage |
04/05/2003 |
During a planned reversal of main ventilation in a substantial section of a large mine, the resultant pressure drop against old workings that had been on the intake side caused emissions of firedamp into the return necessitating the stoppage of two booster fan sites when firedamp levels reached 1.25%. Planned dilution by air slippage at a regulator could not be undertaken as a telephone was inappropriately sited. The maximum firedamp level at one fan site was 1.47%, and at the other levels stayed below 1.25%. The sites were stopped for 59 and 21 minutes respectively, and there were no adverse conditions inbye. |
| Fan Stoppage |
02/06/2003 |
After a weekend shut down, the main fan at a miscellaneous mine had stopped and failed to restart. All 24 alloy blades of the axial flow fan had broken and detached from the fan shaft. The blades were fitted new and commissioned by the manufacturer two days before the failure. It appears that the main bearing supporting the fan shaft at the inlet end failed allowing the fan shaft to move slightly resulting in the blades catching the inside of the fan cowl. No persons were underground at the time and normal mining work was suspended until normal ventilation arrangements were restored. |
| Fan Stoppage |
15/06/2003 |
There was an unplanned stoppage of a 3.3kV cluster type underground booster fan when, during planned switching operations, a short circuit flashover developed in a defective live line indicator and resulted in the tripping of the fan's dedicated feeder. The stoppage occurred during a weekend maintenance shift and there was a delay of 60 minutes in restarting the fan. Although ventilation to the mine was reduced by 38% during this period no excessive methane was recorded during the stoppage or subsequent restoration. |
| Fan Stoppage |
22/06/2003 |
A Booster fan stopped after the temporary loss of power to the mine in a thunderstorm. It could not be restarted for a period of 55 minutes following the failure of the environmental monitoring system leading to the need to put the standby monitoring systems into operation. No adverse conditions arose from the incident. |
| Fan Stoppage |
22/06/2003 |
During a weekend period, there was a reduction in ventilation to
part of a mine when the incoming overhead lines were affected by a
series of lightning strikes and severe voltage surges caused
widespread trips and extensive loss of surface and underground
power supplies. Mine electricians were quickly deployed to restore
the supplies to the ventilating fans and the main surface fan was
successfully restarted just 23 minutes after tripping. However,
re-booting at the surface control room and checks in distribution
substations caused a delay of over two hours in restarting the
underground booster fans. No one was adversely affected and no
excessive methane was recorded. |
| Fan Stoppage |
29/06/2003 |
On a Sunday morning power was lost to the mine ventilation fans
when an 11kv to 3.3kv transformer situated at the bottom of the
mine drifts failed. It appears that the secondary winding of one of
three individual cores has arced causing a short. The transformer
was removed and sent to a specialist workshop for detailed
examination and repair. |
| Fan Stoppage |
29/06/2003 |
At a miscellaneous mine, power to the main fan, which is below
ground, was shut off automatically when a resin insulated air
cooled 11kV transformer winding developed an inter-turn defect.
This was the second such transformer winding to develop such a
problem and the transformer will be replaced. The stoppage was
prolonged by the need to install a replacement transformer winding,
but no adverse conditions arose from the stoppage. |
| Fire Underground |
13/05/2003 |
A fire broke out in the main return airway of a large colliery
as a result of the high-speed mineral conveyor rubbing against belt
the structure and hot fibres igniting coal fines underneath the
belt. The fire was detected by the environmental monitoring system,
investigated by district officials and extinguished using fire
hoses. No one was injured, no self-rescuers were used and persons
were not withdrawn. Formal enforcement action was taken by serving
improvement notices on the mine manager and mine owner. |
| Fire Underground |
21/05/2003 |
An official responding to a request from the control room
operator to investigate a high bearing temperature alarm on a
conveyor return end roller found glowing embers on the side plate
of the hopper section. The belt was running out of line and rubbing
against the side plate generating frictional heat. Only a small
amount of material stuck to the side of the plate burned. The
conveyor return end was sited below floor level and not cooled by
the main ventilation. The response to control room alarms was not
wholly adequate and exacerbated the problem. |
| Fire Underground |
27/05/2003 |
A fire broke out in the engine compartment of a small, diesel
powered, tracked dumper working below ground in a mine where ground
stabilisation work was being undertaken. The driver put out the
fire with a portable 6kg dry powder extinguisher after the
operation of the on-board Fire Suppression System (fire suppression
system), failed to quell the fire completely. No persons were
injured, no self-rescuers were worn, and equipment damage was
minimal. Hydraulic mineral oil, leaking from a damaged hydraulic
hose, was the fuel and the hot engine exhaust the most likely
source of ignition. Preventative measures include, properly
designing an on-board fire suppression system for the vehicle in
question and others at the mine, re-routing and shrouding of
hydraulic hoses and electric cables and fitting a portable fire
extinguisher to each vehicle. |
| Fire Underground |
30/05/2003 |
An official and two workmen travelling outbye at the end of the
night shift smelled burning. They traced the source to a trunk
conveyor receiving hopper where the blind side bearing on the idler
controlling the belt through the plough had collapsed causing the
belt to rub against the hopper, generating heat and igniting coal
fines. They put out the fire with water and cleaned up to ensure
no residual burning material remained. The fire was not detected by
the environmental monitoring. The idler has since been replaced
with one equipped with higher duty bearings and a review of the
suitability of bearings constructed with plastic cages has been
carried out. |
| Fire Underground |
02/06/2003 |
During an engine fluids level check, initiated loss of power, a
fire broke out below ground in the diesel engine compartment of a
telehandler when pressurised transmission fluid leaked from a
dipstick hole and dripped onto the adjacent hot exhaust. The mine
subsequently found that the transmission breather was blocked. The
on-board automatic fire suppression system relied on a contrived
arrangement to hold the firing handle open, but this was missing.
The on-board manual fire suppression system operated but the simple
2 nozzle system failed to quell the fire completely. The fire was
easily extinguished with the vehicle's portable extinguisher
and no person suffered any ill effects. |
| Fire Underground |
18/06/2003 |
A shift charge mechanical engineer detected a strong burning
smell whilst examining a site for a conveyor repositioning. He
found a heating on the blind side of the receiving conveyor
adjacent to the plough bottom idler. He summoned some nearby
conveyor maintenance workers who cleared away some accumulated coal
spillage and sprayed the area with water. There was no defect on
the idler and the bearings were intact. The fire was not detected
by the environmental monitoring. Records indicated that the
ventilation quantity was 17.34m3/s. |
| Fire Underground |
21/06/2003 |
An FSV driver below ground smelled burning and tracked it down
to a sparking 298kW 6.6k V conveyor drive motor. He stopped the
conveyor and saw flames around the motor drive shaft. He quickly
extinguished the fire with a single portable dry power
extinguisher. No person suffered any ill effect, or wore a self a
self-rescuer, or was withdrawn. Heat from the catastrophic failure
of the roller cage in the motor drive end bearing had caused
leakage and ignition of bearing grease. Bearing temperature
monitoring and in-service vibration detection are to be
improved. |
| Fire Underground |
25/06/2003 |
A fire occurred in an in seam intake conveyor roadway when a
bearing at one end of non-driven return end sprocket of metering
chain conveyor failed and generated heat. Workers in a heading
several hundred metres inbye smelled smoke, went to investigate and
saw 0.5m high flames above the sprocket bearing. They stopped the
panzer and flames went out but they applied a dry powder
extinguisher and cooled area with water. No one was withdrawn and
no one wore self rescuers. The bearing failed due to ingress of
fine coal through the seals, which were probably damaged due to
misalignment of the sprocket. A temperature-monitoring device had
given warning previously but the investigating fitter tensioned the
panzer thinking over-tension to be the cause. He did not check
bearing thoroughly and appears to have inadvertently detached
temperature probe from bearing during operation. Improvements to
design, maintenance and response of craftsmen to temp warnings are
being pursued to prevent a recurrence. |
| Ignition of Gas Underground |
25/06/2003 |
In the underground repair workshop of a large miscellaneous
mine, a fitter working on a diesel-powered telehandler sustained
minor burns when the vehicle's 95Ahr 12V lead-acid battery
exploded violently. Hydrogen gas emitting from the battery was
ignited by a spark from the fitter's angle grinder and the
flame flashed-back into the top of the battery. Batteries will in
future be removed or shielded if there is a likelihood of sparks
falling on or near them. |
| Locomotives |
01/04/2003 |
Two wheels of the leading cab of a 50 hp Bo-Bo locomotive
derailed when the locomotive was driven into a passbye and made
contact with a pipe joint on a methane drainage range. The track
and clearances had been commissioned during December 2002 and at
that time only one methane range was in the roadway. A second
range, which the locomotive struck, was installed directly beneath
the first range during January. The mine is to pursue an improved
procedure for identifying and evaluating changes that might have an
adverse effect on clearances in transport roads and to feed that
into the design. |
| Locomotives |
22/04/2003 |
A steel tyred battery powered locomotive travelling at slow
speed hauling a material load was brought to rest by derailment
whilst travelling round a 20m radius turnout curve. Floor movement
had resulted in excessive track twist, which was being checked
regularly by observing the passage of a loco and reporting any
outer wheel lift. However, the locomotive had just had new wheel
sets fitted, which reduced the margin against derailment. The
turnout was re-laid immediately after the incident. Track twist
should be properly measured against prescribed standards, and where
necessary fitted with a checkrail. |
| Locomotives |
29/04/2003 |
While turning round a 150hp double-ended, Bo-Bo locomotive at a
passbye at an inbye main manriding terminus, all four wheels of the
leading bogie detailed at slow speed just beyond the points. No one
was injured and no serious damage resulted. The points blades were
split and out of adjustment and the locking fish tail for the LH
blade had come out of its locating saddle, which had been
displaced. Once the points were readjusted and bolts tightened the
worked satisfactorily. Tests showed that when the locomotive
wheels just clear of the points the operator could see the nearside
blade but could not see the offside blade sufficiently well to
ensure that it was correctly set. It is likely the maladjustment
was caused by the derailment and that the most likely cause of the
incident is that the loco wheels were too close to the points
preventing the LH rail fully closing and the operator from seeing
this. |
| Overturn Dangerous Substance |
04/06/2003 |
On the surface of a tourist mine during major construction
works, a 13 tonne tracked hydraulic excavator overturned. The
unwitnessed incident occurred when the excavator was negotiating a
short but steep incline slope between working levels. The machine
tilted backwards onto its counterweight and landed upside down. The
driver who was apparently wearing a lap belt escaped injury. There
were deficiencies in operator competency, an absence of suitable
information regarding the safe use of excavators on steep slopes
and inadequate ground works design by the mine owner and principal
contractor. |
