| Dangerous Occurrence Type Text | DO Date | Dangerous Occurrence Précis |
|---|---|---|
| Escape of Gas | 14/02/2002 | An outburst of coal and methane occurred in an arch supported development heading working towards a fault. As the continuous miner squared the roadhead prior to support setting, without warning coal burst from the face exposing a wedge some 0.5m wide and 5m deep. Some 15 tonnes of coal were blown back up to 24m from the face, damaging the multi oiler and a light on the machine. Coal struck the machine operator and buried him up to his chest in coal inside the cab. Another workman was struck by debris at the rear of the machine. Neither was seriously injured. Monitoring indicated a peak of 4% firedamp in the roof near the face of the heading. It would appear that the wedge of coal had been under pressure at an intersection of three faults and was squeezed out, breaking up and releasing methane in the process. Proving boreholes will be drilled forward to prove the extent of faulting prior to the heading restarting. |
| Fail Lift Machinery | 15/01/2002 | In a gate road to a salvage face, supported by steel RSJ's with wooden end props, a lifting station, consisting of four 6 tonne capacity compressed air lifting blocks attached to lifting bolts set into very competent roof strata, was being used to lift a roadhead powered roof support weighing 12 tonnes onto a flat tram. Blocks were attached to each corner of the support when one of the hooks suddenly snapped on one of the lifting blocks. The method statement had been constructed for line supports not roadhead supports. With the hook attached to a roadhead support it exerted a shear load onto the hook swivel which consequently caused the hook to break. |
| Fail Lift Machinery | 30/01/2002 | While carrying a mine car of track ballast on a colliery surface, the driver of a forklift truck noticed that one of the twin lift chains had broken. Neither the forks nor load fell, no one was injured there was no damage. The chain failed close to the bottom anchorage due to failures in two adjacent link pins. Ultrasonic examination has indicated breaks in approximately 25% of the pins in the incident chain and a lesser number in the other chain. Operation of the forklift over poorly maintained concrete surfaces and over tracks, causing shock loading, and misuse are thought to be contributory. Other forklifts are being examined and improvements to control of use and to thorough examination are being pursued. |
| Failure of Plant - Manriding | 04/01/2002 | A manriding belt conveyor, located in a maingate to a coal face, failed at a mechanical joint when it became fast in a bottom belt plough support plate bracket on a movable return end loading section. No persons were riding at the time. The failure of an otherwise acceptable joint was attributed to 'unzipping' of the joint as a result of concentrated stress on one edge of the joint, and dynamic effects. Minor modification to the support plate resulted in a small vertical gap at the edge of the receiving section into which the belt ran and became fast. The gaps have since been filled to prevent a recurrence, and provision of return section alignment devices is being pursued. |
| Failure of Plant - Manriding | 07/01/2002 | During mineral conveying on a slightly rising 1500m long, 1.2m wide 675 kW trunk conveyor also used for top and bottom belt manriding, the conveyor stopped automatically due to a trip when the belt broke at a joint some 60m inbye of the delivery jib. No persons were riding at the time, no one was injured and there was no serious damage. A 160mm wide tail had torn off the blind side edge for approximately 100m and the remaining 1025mm of the leading joint had combed out of the belt. The damage appears to have been caused by the belt catching on sharp edges at several poorly graded line stands or by fouling a protruding line stand bolt. The joint was approximately 20% below normal strength due to over-skiving resulting in the outer fibres being shaved. The practice of skiving joints has been stopped, all skived joints have been replaced and improvements to belt slinging and structural alignment are being pursued to prevent a recurrence. |
| Fan Stoppage | 10/02/2002 | During a weekend period, there was a reduction in ventilation to part of a mine when, without prior warning, a 3 × 112kW underground booster fan stopped. Personnel were called to the mine and checks at the local transformer revealed that the low SF gas pressure trip had operated on the incoming high-tension circuit breaker. The electrician swapped to the standby supply and re-started the booster fan. During the 4 hours 1 minute stoppage, no one was adversely affected and no excessive methane was recorded. The switchgear manufacturer has been requested by the mine manager to urgently ascertain the cause of the sudden SF gas leak from the "sealed for life" tank. |
| Fan Stoppage | 02/02/2002 | During stormy weather electrical services to a small drift mine, including ventilation, were disrupted when the single incoming power supply was lost for a period of 3hours 30 minutes. The outage affected a wide geographical area and involved repairs to the Supply Authority's HV transmission network remote from the mine. Underground, no adverse environmental conditions arose and none of the three miners suffered any ill effect. |
| Fan Stoppage | 26/02/2002 | At a large coal mine a sudden barometric fall resulted in CH4 from an abandoned seam increasing the CH4 content in the pit bottom from zero to 0.5%. The consequential effect was to increase the GB content at the NE and NW booster fans to above 1.2%CH4. Production was suspended, the return booster fans were isolated and the situation monitored until it was possible to restart the booster fans some 3 hours 40 minutes and 5 hours 48 minutes later. No person suffered injury, no working area became gas fast and auxiliary ventilation systems continued to operate. To prevent a recurrence the manager has already pursued plans to replace the stoppings on the abandoned Swallow Wood seam. |
| Fan Stoppage | 23/03/2002 | A major inrush of water at a large coal mine blocked the second means of egress from the mine and stopped the main ventilation with the subsequent tripping of the main surface fan. All those underground were quickly accounted for and no one was injured. Initial investigation suggests that the inrush originated from an area of old workings, to the rise side of a section of the main ventilation roadway, which were stopped off in the mid-1980s. Pipes through accessible stoppings allowed water to be drained and routine inspection prior to the incident had not indicated any significant change in water make from the area. It would appear that a large body of water had collected in the old workings, and the inrush resulted from the catastrophic failure of whatever structure was holding the water back. Mine owners and managers should make an assessment of any workings on the rise side of current workings to determine whether remedial action is necessary |
| Fire Underground | 17/01/2002 | Underground in a large miscellaneous mine, a small fire broke out in the engine compartment of a Bray wheel loader. The fire was rapidly extinguished using the on-board fire suppression system, and there were no adverse health effects. Indications were that small deposits of flammable material had penetrated thermal cladding on the exhaust system, and were ignited when the machine was used for an unusually long period that allowed the engine to achieve operating temperatures. The thermal cladding was provided to safeguard against ignition of hydraulic oil in the event of a burst pipe and, on balance of risk, will be retained. To prevent a recurrence, more attention will be paid to maintaining the tight fitting of cladding, and it will be removed periodically to clean below. |
| Fire Underground | 08/02/2002 | In a main coal clearance roadway supported by steel arches a command supervisor noticed a haze coming along the beltline. He contacted the control room operator who in turn contacted a beltman. During investigation he found smoke and flames, approximately 75 mm to 150 mm in length, coming from the tight side of the belt and extinguished them using a fire hose. No persons wore self-rescuers or were withdrawn. A bottom belt roller bearing had collapsed and ignited belt tailings and coal. The roller was on the apex of a change of roadway gradient and was subjected to higher-than-average forces. Investigation revealed that rollers in the area were being changed regularly because of failed bearings. |
| Fire Underground | 06/01/2002 | In a secondary intake locomotive roadway, during light running of a 300hp inseam manriding/mineral conveyor, a small fire occurred at the walking side bearing of one of the three rollers on the loop carriage. An electrician working nearby saw smoke and stopped the conveyor after which small flames were seen at the roller bearing. He quickly extinguished them using stone dust and a handheld extinguisher. No persons wore self-rescuers or were withdrawn. The studs securing the roller barrel to the bearing housing had failed and the roller bearing had seized resulting in heavy friction, high temperature and ignition of the grease vapours from the bearing. A prescribed manufacturers modification to increase the size of the studs had not been carried out during previous overhauls. |
| Fire Underground | 25/03/2002 | Within the intake drift of a Bathstone mine, fire broke out on a diesel telehandler-type lift truck resulting in the emergency evacuation of the mine. A trainee driver had left the parking brake on whilst the vehicle was in motion resulting in the outbreak of fire on the transmission disc brake. The onboard engine compartment fire fighting system could have no effect and application of a single dry powder fire extinguisher failed to quench the fire. No one was injured or wore self-rescuers. Investigation revealed that the parking brake dashboard warning light was inoperative due to the connection being broken by a wheel brace stored under the drivers seat. The presence of contractors, unfamiliar with the mine layout, also highlighted potential inadequacies in emergency exit signs and the instruction of visitors in escape routes and self-rescuer use. |
| Inrush of Water | 23/03/2002 | A major inrush of water at a large coal mine blocked the second means of egress from the mine and stopped the main ventilation with the subsequent tripping of the main surface fan. All those underground were quickly accounted for and no one was injured. Initial investigation suggests that the inrush originated from an area of old workings, to the rise side of a section of the main ventilation roadway, which were stopped off in the mid-1980s. Pipes through accessible stoppings allowed water to be drained and routine inspection prior to the incident had not indicated any significant change in water make from the area. It would appear that a large body of water had collected in the old workings, and the inrush resulted from the catastrophic failure of whatever structure was holding the water back. Mine owners and managers should make an assessment of any workings on the rise side of current workings to determine whether remedial action is necessary to secure against the possibility of an inrush. |
| Locomotives | 07/01/2002 | A 50 hp Bo-Bo battery locomotive hauling one empty flat was derailed at the leading axle of the trailing bogie, when the rear cab struck a collar on a 10" methane drainage range. No damage or injuries resulted. A clearance survey one month before had identified reduced clearances in this area, but had been conducted with a smaller locomotive so the extent of the reduction was not fully apparent, and remedial action was still awaited. To prevent a recurrence, clearance surveys will be conducted with the largest locomotive likely to travel the road, and drivers will be instructed not to travel where clearances are obviously severely restricted. |
| Locomotives | 25/01/2002 | Underground in a coal mine, a 50hp battery powered Bo-Bo locomotive derailed as the driver attempted to drive away. Indications were that the locomotive jacknifed upwards when only the trailing bogie motor was driving and the park brake had not been released. Daily single motor drive tests had not identified the leading motor was not driving. More work required to validate the apparent forces involved, after which the single motor drive test may require modifying. |
| Locomotives | 13/02/2002 | While pushing two loaded vehicles around a curve from a main road into a heading on a gradient rising at 1 in 13, the leading outside wheel of a 50hp rubber tyred Bo-Bo locomotive rode up on to the outer rail of the curve. While driving slowly in the opposite direction to correct the problem, both locomotive bogies twisted and derailed bringing the locomotive to rest. No person sustained injury and there was no damage. The problem arose between the points and the V of the turnout before the leading wheel reached the check rail. There was negative super-elevation in this area. The relatively tight radius curve and the forces acting on the locomotive bogie due to the heavy load on a steep gradient are factors that increase the likelihood of derailment. The curve will be super-elevated and ballasted and provided with a long check rail to reduce the forces on the outer wheel flanges. |
| Locomotives | 11/02/2002 | Underground at a large coal mine a 28 tonnes Bo-Bo locomotive derailed at slow speed during shunting operations at a facing turnout. There was no significant damage and no one was injured. One set of wheels split the points, which had given trouble previously. The curved switchblade stood proud of the stock rail and had suffered wheel impact damage that further prevented it fitting closely under the machine-chamfered surface of the stock rail. The switchblade will be re-machined and refitted, to fit closely under the stock rail in contact with the slideplate. Those inspecting will be informed of the potential problem if switchblade entry is not properly maintained. |
| Locomotives | 01/03/2002 | While travelling along a main locomotive return down a 1:20 gradient, a Clayton 15t 0-4-0 steel-tyred, battery locomotive hauling a 9t unbraked load consisting of 4 empty and 2 lightly loaded trams, ran into a gravel arrester and was brought safely to rest. No-one was injured and there was no serious damage. The track was in good dry condition and little evidence of a locked skid was found. The most likely cause to have been the driver applying the brakes too late. Further testing of the locomotive is planned. Trackside notices are to be improved, a 'sand' notice is to be provided, and stopping distance information is to be reiterated to drivers. |
| Locomotives | 06/03/2002 | Underground at a large coal mine a pony locomotive was brought to rest by derailment whilst shunting a low height skateboard vehicle round a trailing turnout. The driver did not identify the cause, but reconstruction showed that an insecure safety chain caught in the heel block and caused a holdfast that could generate forces sufficient to lift the front wheels of the locomotive. Drivers and shunters will be required to secure idle safety chains to the bracket provided in future. |
| Locomotives | 22/02/2002 | Underground in a large coal mine a battery powered pony locomotive was brought to rest by derailment when it rode onto belt spillage. The track was little used, and spillage cleaning had been ongoing for some time. The driver and shunter were warned to take care, but misjudged the minimum cleaning necessary. The system of work resulted in the unacceptable practice of a 'spotter' travelling in front of a laden vehicle being pushed. In future, little used track not maintained will be isolated, and recommissioned by a competent person prior to use. The repetitive nature of this type of defect has led to the Mines Inspectorate withdrawing consent to operate locomotives underground at this mine. |
| Locomotives | 24/01/2002 | In a main locomotive road, a 150hp diesel powered steel-tyred, 0-4-0 rack locomotive hauling two materials vehicles at approximately 4mph over the brow of an incline, was suddenly brought to rest by derailment, when the leading drive pinion ran onto a steel plate which had fallen onto the track from a previous materials train. The driver could not see the plate due to the change in gradient and the pitching of the locomotive. Both the driver and the shunter suffered whiplash injuries resulting in being off normal work for several weeks. |
| Locomotives | 11/03/2002 | At the junction of a main return with a tailgate roadway a 50hp BoBo locomotive, travelling inbye with one vehicle attached, derailed on a curve when a 300mm diameter GRP pipe being transported on top of the locomotive, jammed between the articulated cab ends. No persons were injured and there was only superficial damage. |
| Locomotives | 07/03/2002 | Underground in a large coal mine a battery powered pony locomotive was brought to rest by derailment when it rode onto debris in the track. Indications were that the section of track was little used and was not regularly inspected by supervisors. Periodic inspection by engineering staff had identified the problem some time ago, but the defect had not been classed as safety related and no action was taken. Poor discipline and the repetition of avoidable incidents has now led to the Mines Inspectorate withdrawing consent to operate locos underground at this mine. |