| Type | Date | Précis |
|---|---|---|
| Collapse Structure | 20/01/2003 | A contract worker at a coal preparation plant noticed that a 23m long inclined covered conveyor gantry had partially collapsed approximately one third of the way from one end. It was still supported in a slumped position between the CPP main building and an external transfer tower at a height of 13m at one end to 20m at the other end. No persons were injured and no other damage was caused. Investigation has indicated that the 50-year-old fabricated gantry truss collapsed in bending due to corrosion failure of several internal vertical and diagonal angle iron members where they attached to the floor. Similar heavy corrosion has been found at the bottom joints of two similar gantries, which are now being repaired. |
| Fail Lift Machinery | 04/02/2003 | At the lorry-loading bunkers of a coal preparation plant a 3 tonne SWL hoist rope supporting a loading boom conveyor broke allowing it to fall about 2.5 metres onto the back of the lorry. No-one was injured and no serious damage was caused. The 8mm diameter hoist rope was found to have failed at a point just above the boom pulley block with the boom in the parked position and 1.12m below the fixed anchor end. The rope is thought to have been about 10 years old and was dry and rusted and there was some evidence of wire fatigue although reports contained no record of any visible defects found during routine inspection and thorough examination. Further examination of the rope is being carried out, improvements have been made to the inspection and maintenance regime, and a finite life has been set for such ropes. |
| Failure of Plant - Manriding | 12/02/2003 | During normal running of a dedicated top and bottom man-riding conveyor extending some 875m on a 1:27 gradient, the belt stopped automatically in response to a belt tear indication. The top belt had broken at a joint 170m inbye of the drive and delivery and parted approximately 18m. No persons were riding at the time, no one was injured and no serious damage was caused. The fairly new 0.9m wide Titan mechanical joint had combed out of the trailing length of the fairly old belt. The failure resulted from an isolated poor standard of jointing on worn belt. Improvements to standards of joint installation and inspection of belt and joints are being pursued to prevent a recurrence. |
| Fall of Ground | 20/01/2003 | Whilst carrying out an inspection along an old parallel intake roadway, supported by RSJs and wooden end set props, a command supervisor found a fall of ground at a 4‑way junction, where two seams converged and approximately 1.2m of roof coal had been left up when the road was driven in 1972. The roadway had originally been a return road but was made an intake 2 years ago. The immediate roof consisted on weak laminated mudstones, which, after the change of use, had apparently weathered over time, opened joints, and the weight of the detached rock bent the RSJ causing the roof to collapse. Ventilation of that part of the mine was not affected. There were no signs of any irregularity before the collapse. Old roads that are no longer needed will be progressively sealed and a further ground control assessment carried out elsewhere to try and identify vulnerable areas |
| Fall of Ground | 02/03/2003 | At a large miscellaneous mine a fall of ground occurred in a nominal 8.0m wide × 3.4m high crosscut driven in rock salt. The maximum height of the fall was estimated at one metre above the normal roof level, and it involved an estimated 12 tonne of rock some of which came to rest alongside electrical switches sited in the main travelling route. The roadway had been driven around June 1997 with the overlying potash mined in October 1996. The entrance to the crosscut had been additionally supported with 2 rows of longitudinal straps with 4.0m long reflex bolts at 2.1m centres during July 2002. This additional support had prevented the fall from extending into the access roadway. The original reflex bolts were point anchored and a recovered bolt showed sign of corrosion and pre-fall shearing. Remedial action involved the further bolting using 2.4m AT bolts and full column 4.0 reflex bolts. To minimise the likelihood of a recurrence the current roadway risk assessment programme has been extended to cover cross cuts and all areas where equipment is located |
| Fall of Ground | 19/03/2003 | In a square section roadway supported by straight RSJ supports fitted with a knuckle joint and cambered legs and used as an auxiliary intake airway, a fall of ground was discovered during a routine inspection. The fall occurred at a 3-way junction 5m inbye of another junction that had been reinforced with wooden link lock supports. The area had previously shown no signs of any unusual roof movement or deflection of the roadway support. The floor was soft and it would appear that the roof had progressively detached over at a good decoupling horizon some 1.2m above roof height and the increasing dead weight eventually pushed the support leg into the soft floor causing the roof to collapse. The ventilation was not restricted at any time. Old roads that are no longer needed will be progressively sealed and a further ground control assessment carried out elsewhere to try and identify vulnerable areas |
| Fan Stoppage | 02/01/2003 | On return after a Christmas shut down at a gypsum mine the main fan was found to have tripped out. Investigation revealed that all 24 alloy blades of the axial flow fan had detached from the impeller. The blades have been sent to the manufacturer for investigation, but it appears that most blades failed as a secondary consequence of a single blade failure. No persons were underground at the time and normal underground work has been suspended until temporary ventilation arrangements are commissioned |
| Fan Stoppage | 22/01/2003 | At a safety lamp gypsum mine the main fan underground was stopped for 90 minutes when a defect occurred at the surface 11kV supply affecting both the underground and surface supplies. The defect occurred on an air insulated 11kV connecting chamber of relatively old switchgear. The switchgear is to be replaced by modern equipment. No adverse conditions arose from the stoppage |
| Fan Stoppage | 25/01/2003 | At a large coal mine a failure in a HP water range, arising from corrosion, caused flooding that resulted in the stoppage of a booster fan on a Saturday afternoon. The subsequent failure of isolation valves in the range required the range to be isolated in the pit bottom area, and this also isolated the water supply to the fire protection system associated with another booster fan, which was stopped 100 minutes later. The corroded pipes were changed on the following day and both booster fans restarted. To reduce the likelihood of a recurrence the pipe ranges have been surveyed to confirm that there are no other pipes that are similarly corroded. Improved isolating valves are being sourced and a better testing regime instigated |
| Fan Stoppage | 10/03/2003 | Booster fans at a coal mine were stopped for a period of 3 hours and 11 minutes when a defect occurred on a fan supply GEB contractor coil at a time when no persons were underground. No adverse conditions arose from the stoppage |
| Fire Underground | 18/02/2003 | An 1100 volt armoured cable, resin filled, half coupler developed a short circuit and flames were emitted from the rear of the cable coupler/cable junction. Electrical protection operated efficiently to remove current. The flames were small and of short duration. Further investigation will take place to determine the nature of the breakdown. There was evidence to show that the cable box had been overheating leading up to the defect and systems will be put in place at the mine to accurately check similar heavily loaded feeder coupler temperatures on a more frequent basis. |
| Fire Underground | 16/02/2003 | An electrician in charge of a coal mine went to repair conveyor equipment during a weekend period, but failed to appreciate that his methods of testing would result in operation of the loop take up winch with its drum brake still applied. Although smoke came from the brake he repeated the test later in the shift, with smoke again being emitted. He did not inform any official of the heat having been generated and left the mine. The monitoring system subsequently alarmed due to excess CO, but this was not reacted to adequately and it was some 2.5 hours after the initial CO alarm before the fire was found. The fire involved glowing of fines underneath the loop take up brake and was extinguished using water. The mine has taken steps to improve the reaction to alarms of officials and control room operators |
| Fire Underground | 11/03/2003 | An outbreak of fire occurred 103m into a single entry development heading as a result of spontaneous combustion of coal in the roof of the steel supported roadway, near to a junction. No persons were withdrawn or wore self-rescuers. Inadequate packing over the junction had enabled coal tops to fall and the change of cross section had induced airflow over the corrugated sheet steel lagging. To prevent a recurrence, preventative measures will be increased at the planning stage, including mining to the rock top; replacing sheets with mesh lagging, minimising the number of junctions constructed and identifying and systematically spray sealing vulnerable places. |
| Fire Underground | 26/03/2003 | The driver of a 90HP battery locomotive had driven some 300m from the battery charging station after changing the battery when he noticed a burning smell. He subsequently discovered smoke coming from the battery vent, and on lifting the battery lid he saw small flames, approximately 150mm high, and quickly extinguished them using a dry powder extinguisher. The problem arose because of a spliced joint in a battery power lead failed causing electrical arcing, which ignited and damaged battery cells. |
| Fire/ Explosion Electrical | 29/03/2003 | At a miscellaneous mine a machine operator was attempting to start the auger of a 627kW, 3.3kV heliminer when a bang and a jet of flame "like a roman candle" came from the fuse chamber of the KFVG starter. All power tripped after 2-3 seconds and the operator noticed that the flame had ignited nearby oil impregnated salt deposits. The fire was quickly extinguished by the application of a single dry powder extinguisher and no adverse effects were monitored in the underground environment. The cause was a disruptive failure of a 3.3kV HRC line fuse and extensive internal damage due to heavy current arcing at the main connections. Electrical protection is to be improved. |
| Ignition of Gas Underground | 15/01/2003 | On a retreating longwall face coalmine, a frictional ignition of firedamp occurred behind the leading drum of a DERDS equipped with RAC and ITC wet cutting drums arranged in an anti-ignition mode. The hanging flame burned for approximately 2 to 3 minutes before being extinguished by the shearer operator using an on-board high-pressure fire-fighting hose. A 4 kg dry powder extinguisher was also discharged at the flame without effect. Investigation highlighted that a significant waste break accompanied by water had occurred shortly before the incident, probably inducing higher than normal gas flows. The ignition was thought to have been caused by a single blocked spray found on the drum cutting ring, the dry pick striking a sandstone quartz nodule in the roof and igniting a gas feeder in the roof/seam interface of the 1.8m high extraction. |
| Locomotives | 08/01/2003 | A steel tyred battery powered locomotive, travelling at slow speed below ground at a large coal mine without a trailing load, was brought to rest by derailment whilst travelling over a facing turnout. The lockable switch change mechanism was not correctly adjusted, and the wheels on both axles split the points. The most likely cause of mal-adjustment is drivers trailing the points. The incident will be publicised and the prohibition on trailing points repeated to all drivers and guards. |
| Locomotives | 25/01/2003 | At a large coal mine all four wheels of the trailing bogie on a 50 hp BoBo locomotive were derailed when the locomotive ran over a conveyor idler, disturbed as the locomotive passed. At the time of the incident the locomotive was breasting three empty vehicles into the loader gate of the retreat face to remove the salvaged conveyor structure. This incident shows the need to ensure that salvaged operations are properly managed, including where appropriate, the provision of empty vehicles on site prior to salvage material being run outbye on the conveying system. |
| Locomotives | 14/02/2003 | While slowly hauling three loaded materials vehicles around a curve towards points at a turnout connecting the inbye end of a tailgate with a development cross-gate, the leading bogie of the Clayton 10t rubber tyred Bo-Bo locomotive derailed and caused the locomotive to come to rest. No one was injured and there was no damage. The curve was very tight and there was no gauge widening, causing the bogies to reach the limit of their articulation and the locomotive to derail. The mine has improved its track design processes, and standards of installation and commissioning. |
| Locomotives | 20/02/2003 | All four wheels of a locomotive travelling outbye along a main locomotive haulage road, with a 1.2m wide belt conveyor installed to one side, derailed when it struck a partially buried steel sleeper laying in the roadside causing it to stake into an arch leg. The locomotive had passed the incident site, going inbye without incident. The incident demonstrates the need to keep loose materials and objects well clear of rail tracks. |
| Locomotives | 01/03/2003 | In a main return roadway a 150 hp rack locomotive derailed as it passed over an area where a set of points had been removed and the track replaced. The made up length of rack bar had only 3 of the 6 securing bolts installed. There was also a high-pressure water range alongside the track and a valve had been leaking softening the floor and compromising track support. The locomotive caught the rack bar and, due to poor cross gradient, derailed. Maintenance and inspection procedures have since been reviewed. |
| Locomotives | 04/03/2003 | Underground at a large coalmine, a 150hp rack adhesion locomotive hauling a permitted trailing material load derailed when the coupling on the leading end of the locomotive struck a rack bar at a concave change of rail grade. No one was injured but the locomotive sustained damage to its braking system and suspension. The coupling elevating arrangements provided to prevent such contact had not been effectively maintained, and may have vibrated loose during travel, and the degree of coupling elevation had not been matched to the tolerable change of track grade. Both have now been remedied. |
| Locomotives | 04/02/2003 | Whilst travelling slowly around a turnout, hauling two vehicles from a main locomotive road into a cross-gate, a pony locomotive was derailed and brought to rest. No one was injured and no damage caused. The most likely causes of the derailment were the turnout curve being too tight and lack of adequate gauge widening at localised points on the curve, but the possibility of the safety chain being fitted too tightly cannot be ruled out. The curve radius and gauge widening will be increased and installation and commissioning procedures have been improved. |
| Withdrawal owing to smoke | 25/03/2003 | An internal failure in the diesel engine powering a welding and lighting generator caused it to emit smoke into the mine air in an intake roadway within a pillar and stall production panel at a large miscellaneous mine. After seeing a haze and smelling burning, six people withdrew immediately to fresh air, but they did not need to wear their oxygen self-rescuers and sustained no ill effects. At this stage it is not clear what caused the engine to fail but the investigation found significant deficiencies in the implementation of the planned, preventative maintenance scheme. The scheme has since been audited to identify and implement areas for improvement, and the engine sent to determine the cause of the failure. |
| Withdrawal owing to smoke | 31/03/2003 | Responding to a smoke alarm on a trunk conveyor, a belt patrolman identified and removed a defective three-piece top idler set, on which he identified a collapsed bearing. The idler set was very hot, he placed the set on the floor and went to run out a hose. On return he found smoke issuing from a piece of Bondina on which the idler set had been placed and melted a hole in it. This generated further smoke alarms. The idler set is thought to have only completed some 8 months, of not excessively heavy duty. To reduce the likelihood of further incidents the poor life expectancy of new idler sets is being pursued with the manufacturer and all items of potentially combustible scrap materials are being removed from the trunk conveyor roads. |