| Failure of Plant - Manriding |
14/07/2003 |
While conveying mineral on slightly dipping 500kW maingate conveyor also used for top belt manriding, conveyor stopped automatically due to a trip when the belt broke at a joint close to delivery. No one was riding at the time, no one was injured and no serious damage caused. The belt had pulled out of joint clips, probably in an unzipping' manner, due to damage to the belt edge. Several clips and staples were missing, other clips were heavily abraded, staples were corroded at bends, and numerous staples had missing bent-over sections. The joint was just overdue for a planned 6 monthly change but this scale of deterioration should have been found by weekly thorough examination. Manriding was suspended until belt standards were improved and improvements made to planned maintenance and thorough examination. |
| Failure of Plant - Manriding |
07/08/2003 |
On a mine surface, while using a telehandling machine to push an empty ‘rollalong’ type skip with one of the forks, the shaft carrying the fork fractured. It was overloaded in bending, producing forces that it was not designed to withstand. The mine will avoid moving skips where possible, and where a skip has to be moved it will only be done with the correct equipment. |
| Fall of Ground |
09/07/2003 |
At a large coal mine a fall of ground occurred during face salvage operations. The face had been supported by rockbolts and plastic mesh in preparation for the salvage. 55 powered roof supports had been removed, using a ‘walking chocks’ system, and had been replaced by wooden cribs. The fall occurred between the face side row of wooden cribs and the face and was located in close proximity to a pillar edge in the overlying Barnsley seam 240m above the face. The mine had precluded access past the fall site as a precautionary measure and established 2 @ 9 man headings. |
| Fall of Ground |
23/07/2003 |
In a main gate of a longwall retreat face, supported by roof bolts and supplemented with passive wood and hydraulic supports, a fall of ground occurred 4m outbye of the face T-junction. The fall was about 13m long, 5m wide and about 1m high and fell within 5 minutes of initial warning signs. The roof was mudstone/siltstone overlain by a competent siltstone. Several of the roof bolts were broken and several tell tales were not recording due to the wires being nipped. It appears that the bolts broke due to high stress loads, probably caused by the adjacent face that retreated as the main gate was being developed. Other contributing factors were; changes in roof horizon, overlying seam pillar edges, increased front abutment stresses and a removal of some of the confining stress within the roof. |
| Fall of Ground |
05/08/2003 |
During a routine inspection at a large miscellaneous mine an overseer found fall of ground occurred in a fenced off stub roadway, which was designed to collapse and provide stress relief for the main access roadways. On this occasion the collapse in the stub roadway caused extensive damage to an oil bowser, which was parked at the entrance to the stub. No person sustained injury and there was no adverse effect on ventilation or egress. |
| Fan Stoppage |
06/07/2003 |
At a miscellaneous mine, power to the main fan, underground, was removed 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 necessity to install a replacement transformer winding, but no adverse conditions arose from the stoppage. |
| Fan Stoppage |
01/09/2003 |
At a gypsum mine, after several hours of running following a holiday shutdown, the main fan tripped on bearing vibration due to play in the inlet side bearing. The bearing and its pedestal were changed but on start up the following day a problem with the drive motor was apparent and the mine found that the slip rings and brushes were worn. The motor was sent away for the slip rings to be skimmed and new brushes to be fitted. The fan was recommissioned 7 days after the initial stoppage. Normal production was stopped during this period. The bearing has been sent away for examination to determine the cause of the failure. |
| Fan Stoppage |
13/09/2003 |
The ventilation of a mine was substantially reduced for 40 minutes when the main ventilating fan tripped on transformer over-temperature protection following a leakage of silicone insulating liquid. The breakdown occurred at the weekend and there was a delay in contacting the surface electrician to operate the powered louvres and start the standby fan. No one was adversely affected by the reduction in ventilation. |
| Fan Stoppage |
20/09/2003 |
After power was lost to both booster fans at the mine attempts were made to restart the fans from the surface control desk but this failed as the main dedicated booster fan 6600-volt feeder had tripped on earth fault protection. No one was below ground and the mine decided to delay restarting the fans until the following dayshift when men were scheduled to be working at the mine. The standby feeder was put into use and the booster fans restarted after being stopped for 13h 25m and 14h 45m. There were no adverse conditions resulting from the stoppage. A 'through joint' on the dedicated booster fan shaft feeder cable had failed and has been replaced . |
| Fan Stoppage |
28/09/2003 |
During a weekend maintenance period, the ventilation of a large miscellaneous mine was substantially reduced for 2½ hours when an electrician unwittingly earthed the 11kV distribution system and the power supplies to the fans tripped off. No adverse underground environmental conditions resulted |
| Fire Underground |
02/07/2003 |
There was a fire at a miscellaneous mine when a conveyor stalled due to a build-up of congealed mineral at a manless transfer point. Frictional heat between the drive drums and the stalled fire-resistant conveyor belting caused led to the emission of large volumes of smoke. Workers who noticed the smoke stopped the conveyor system using a lockout. When they arrived at the drive they found that it was still smoking and, when they removed the inspection covers they saw a flame. The small fire was quickly quelled by the application of two CO2 and three 5kg dry powder extinguishers. No one was injured and no self-rescuers were worn. The mine is to improve its conveyor maintenance standards and install belt slip protection. |
| Fire Underground |
19/07/2003 |
On passing the end of a trunk conveyor receiving section, a belt patrolman smelled burning and saw a haze. On investigation he found an area of burning coal spillage at the blind side of the belt. He quickly extinguished the small flame using water from a dust suppression hose. None of the 78 persons underground at the time was affected and no one wore self-rescuers. The bottom belt strand had been rubbing on the structure, probably as a result of a missing tight side bottom idler from the first set outbye. Improvements have since been made to the transfer point to eliminate spillage, belt alignment monitoring has been improved, and changes have been made to conveyor inspection, maintenance and reporting arrangements. |
| Fire Underground |
12/07/2003 |
30 minutes after an alignment check and an oil change in the bearing box of 650kW axial flow booster fan, made in response a rising trend of low frequency vibration, a supervisor heard change in running tone and saw what he thought was oil vapour or smoke rising from fan nose cone area. He stopped the fan and found a slightly high oil level, which he corrected before restarting the fan. When he did so he saw smoke and hot particles nose cone. On examining the fan internally he found glowing embers around the base of the bearing box and quickly doused them with water. No persons were withdrawn, suffered ill effects or used self-rescuers. Preliminary findings indicated that bearing box overheated due to wear of drive side ball bearings which in turn ignited deposits of coal dust and paint on the base of the bearing box. The bearing box has been replaced, improved temperature monitoring provided, and inspection and maintenance arrangements improved. |
| Fire Underground |
01/08/2003 |
Following a Level 1 CO alarm generated at 2ppm by the multi-disciplinary alarm (MDA) system a surface control room operator asked the zone inspection official to investigate the cause. 75 minites later he found a heap of smouldering dry coal dust that had built up on the top plates of a conveyor tipper unit associated with a crusher. By this time the MDA had progressed to a Level 5 alarm at 6ppm CO. The official dug out the glowing fines and doused them with water. The fines had stalled the centre idlers of the last two heavy-duty belt triple-idler sets before the crusher receiving section and the frictional heat generated by the action of the moving conveyor belt ignited them. The fines had built up because the top plates were 2.2m above the floor and could not be seen from ground level. A series of engineering improvements is being undertaken to minimise the opportunity for fines to accumulate and to allow proper access for inspection and maintenance. |
| Fire Underground |
12/08/2003 |
A belt patrolman smelled burning and proceeded inbye to investigate. As he went to a telephone to report to the surface control room, the CO monitoring raised an alarm. He and an official found smoke coming from the drive of a trunk conveyor. They quickly extinguished glowing belt fibres with water from a dust suppression hose. No persons suffered ill effect, no self-rescuers were worn and no one was withdrawn. The travelling roller bearing in the loop take up had collapsed, causing the belt to run to one side and rub heavily against the side of the drive unit. Bearing maintenance procedures have been improved and alignment monitoring fitted to the bottom belt at the drive, which was some 400m from the jib end. |
| Fire Underground |
05/09/2003 |
A belt patrolman saw smoke and a few small flames from a mound of brown ash under one end of a 1150mm × 125mm idler where the bottom belt strand was rubbing on the vertical member of the supporting structure, of two-way manriding type but no longer used as such. He put out the fire using a shovel to scoop water from an adjacent hydrant and cleaned up the ash, unconsumed belt fibre fluff and spillage then altered the roller position to re-centre the 1200mm nominal width Type 8 belting of the 365m long, 13m lift, 2.3m/s conveyor. CO monitoring downstream peaked just below the 2ppm alarm level and the belt patrolman did not report the incident until the end of his shift, 3 hours later. No person was withdrawn or wore a self-rescuer. Arrangements at the mine to adopt a company initiative to strengthen the management team with respect to conveyor maintenance took effect three days after this incident. |
| Fire Underground |
01/09/2003 |
A heating, suspected to be the result of spontaneous combustion, occurred in a homotropally ventilated conveyor roadway.
A belt patrolman walked through the area at approximately 1900 and then returned to the area at 0145 when a POC alarm was triggered
at 25 units and he was sent to investigate. He discovered glowing area and doused it with water before summoning further assistance.
The the environmental engineer inspected later during the following shift and found no evidence of heating or possible cause.
No hot spots detected with thermal imager. CO monitoring was installed outbye of this conveyor and the monitoring in the remainder
of the mine reviewed |
| Fire Underground |
11/09/2003 |
A heating, suspected to be the result of spontaneous combustion,
occurred in a homotropally ventilated conveyor roadway. A belt
patrolman walked through the area at approximately 1900 and then
returned to the area at 0145 when a POC alarm was triggered at 25
units and he was sent to investigate. He discovered glowing area
and doused it with water before summoning further assistance. The
the environmental engineer inspected later during the following
shift and found no evidence of heating or possible cause. No hot
spots detected with thermal imager. CO monitoring was installed
outbye of this conveyor and the monitoring in the remainder of the
mine reviewed. |
| Locomotives |
15/07/2003 |
As a Bo-Bo locomotive was attempting to pull a vehicle loaded with a powered roof chock out of a shunt, the roof support canopy caught the side of the roadway derailing one of the locomotive bogies. |
| Locomotives |
09/09/2003 |
While slowly hauling a single manriding vehicle carrying 6 men around a turnout into a pit bottom terminus at the end of afternoon shift, an 18t steel tyred Bo-Bo locomotive jumped the points and the train was brought to rest largely by the derailment of the rear bogie. No persons were injured and no serious damage was caused. This may have been caused by loss of power from the leading bogie drive motor or by erratic operation. The motor speed control unit and a circuit breaker were sent for testing, and improvements to procedures for dealing with motor drive problems are being pursued. In the longer term, locomotive speed control systems are to be modernised. |
| Locomotives |
09/09/2003 |
A 90hp locomotive and the first vehicle in a run of five derailed as the driver braked on the approach to a gravel trap. The driver may have braked loco too close to gravel trap. |
| Locomotives |
19/09/2003 |
A locomotive derailed whilst hauling a vehicle carrying a powered roof support (PRS) up a tailgate roadway supported by rock bolts. The PRS transporter was at the apex of a change of gradient in the roadway when the canopy of the PRS struck a roof bolt and caused a holdfast that derailed the outbye end of the locomotive. The vertical clearance in this section of the road had been slightly reduced due to some minor floor lift and the PRS had not been fully lowered before being loaded on the surface. A dint has been taken, vertical clearances improved and a height marker has been constructed to ensure that all the chocks are fully lowered. |
| Locomotives |
30/09/2003 |
The trailing bogie of a Clayton Bo-Bo 10t battery locomotive derailed at slow speed during materials transport. An 18.7kW motor in the leading bogie was either not driving or more probably was powering intermittently. This caused 'surging' which led to the derailment. The manage's scheme of maintenance included a reference that 3½ weeks prior to the incident one of the motor internal connections had been showing signs of overheating but the electrician's report went unheeded. |
