Appin Colliery is a mine located adjacent to Appin township which has been in production for almost sixty years, under the ownership of Australian Iron & Steel/BHP and later descendant companies BHP Billiton and (now) South32. Over those years it has seen much evolution and innovation; sadly, it was also the site of a major explosion causing ten deaths, in 1979 which in turn led to developments in improving mine safety by seam gas drainage.
Development of the Appin Mine
In 1959 Australian Iron & Steel Collieries commenced work on the development of the Appin Colliery, to mine the Bulli seam, located some 500 metres below the surface, from a site adjacent to the village of Appin. It is reasonable to assume that their decision to open a mine in the Bulli seam at Appin would have been encouraged by the mining lease areas acquired earlier by AIS in the Appin/Douglas Park areas. It is also reasonable to assume that in the 1950s some serious thought would have been given by their management to the future of their existing collieries, which were mining the Bulli seam from its outcrop on the Illawarra Escarpment. In 1959 the time taken to transport men and materials to and from the mine working places was at that time limiting, and certainly in the future would have continued to limit, the time available, for mining at the coal face. The available working time of employees underground had already been reduced and could be expected to diminish even further beyond 1959. These factors would have favoured a decision to open a mine, adopting modern coal mining systems and plant, in the Appin area.
Two inclined drift roadways 1780 metres in length were driven down from the surface to access the Bulli seam, and two shafts, located west of the mine site, were sunk from the surface to intersect the Bulli seam adjacent to the intersection of the two decline drift roadways with the Bulli seam.
Prior to the appointed of a contractor to drive the first of the two inclined drifts from the surface down to the Bulli seam, a direct rope haulage, controlled by radio from a car attached to the haulage rope, was installed on the mine site by AIS. This haulage was used by the contractor to drive one of the two planned inclined drifts down to the Bulli seam. The material removed to ‘drive’ this drift was loaded by a scraper winch into a train of bottom dump wagons attached to the direct rope haulage. This train of loaded wagons was hauled to the surface, and bottom dumped into a bin attached below an elevated surface gantry erected earlier by AIS. On completion of this driveage down to the Bulli Seam, the direct rope haulage was designated the ‘men and materials drift haulage’, and is employed to this day by the Colliery as the primary means of transport to and from underground for mine personnel and materials.
In 1961the driving of a second inclined drift conveyor belt roadway from the surface was commenced by the original contractor, using direct rope haulage supplied by AIS. A self-dumping “alligator car” was installed by the contractor to haul and dump the material removed in driving the drift to the surface. The material excavated in the driving of both drift roadways was placed on the surface, in areas chosen for the development of the Colliery surface area.
Along with the driving of the two inclined drift roadways, the sinking of the No1 Shaft was commenced and on its completion, the sinking of the No2 Shaft. These shafts were located west of the Colliery site and adjacent to Brooks Point Road, Appin. Both shafts were planned to intersect the Bulli seam in the same area in which the two inclined drifts being driven from the mine site would intersect the Bulli seam. The No1 Shaft served as the intake airway for the mine and No2 Shaft the return airway. A mine ventilation fan was installed on No 2 Shaft following the completion of its sinking.
Following the completion of the driving of the above inclined drift roadway, the sinking of the shafts, and the installation of the mine ventilation fan, the mining plant and machinery required to mine the seam was installed, with the production of coal from the mine commencing in 1962. The mined coal was loaded into mine cars by a continuous miner and hauled to the surface by the drift rope haulage (the men and material haulage) and rotary dumped into a bin erected under the permanent surface gantry structure. This coal was unloaded to trucks from the bin and delivered by road to the Port Kembla Steelworks.
The Slope Conveyer Belt
Following the completion of the driving of the second drift down to the Bulli seam, work commenced on the surface in 1962 to erect the slope belt conveyor drive-house building, and install the conveyor belt drive system in that building.
The conveyor belting for this installation, was manufactured in Germany by the Franz Clouth Company, shipped to Sydney on wooden drums, and delivered by road to the Appin mine site. This belting comprised multiple steel cords, embedded in a surrounding outer surface of rubber. The joining of the individual lengths of this belt was carried out on the site by employees of Franz Clouth, Germany. These men carried out the splicing of the individual lengths of steel cord embedded within the conveyor belting, and the vulcanizing of each spliced joint section to provide an installed endless conveyor belt. It was a major task.
In 1964 the installation of the belting and commissioning of a drive system, comprising two 450 kW drive motors and associated electrical control equipment housed in a building erected on the surface, was completed.
Coal was loaded on the conveyor from a storage bin in an excavation underground above the Bulli seam, at the intersection of the conveyor drift with the Bulli seam. On arrival at the surface the coal was unloaded on to another conveyor belt for delivery into a storage bin, from where it was loaded into road trucks, and delivered to the AIS Port Kembla Steelworks.
This slope conveyor belt wasat that point in time believed to have been the only single flight conveyor belt in the world having a centre to centre distance of 1600 ft (487ms), and raising coal some 500 metres in a single lift, from underground to the surface at a rate of 600 tonnes per hour.
Coal production from Appin mine commenced in 1962. Mine cars were filled at the coal face by a continuous miner and hauled by battery locomotives to the bottom of the men and materials (MM) drift roadway. These mine cars were hauled to the surface by the drift haulage and rotary dumped into a bin erected beneath the surface gantry. The empty mine cars were returned underground, and the coal dumped into the above bin loaded into road trucks to be hauled to the AIS Port Kembla Steelworks. This system of coal haulage to the surface using mine cars remained in service until the slope belt conveyor was placed in service.
The mining of the Bulli seam at this depth of cover proved to be exceedingly difficult in terms of both the levels of mine gas released when mining the seam, and supporting of the roof of the mined roadways. The Bulli coal seam at this colliery was found to contain 15 cubic meters of methane gas in each tonne of coal.
Continuous miners and shuttle cars were employed to mine the seam, and steel roof bars and support legs were required to support the roof as opposed to the more usual timber roof bars and props. Given the above concerns, other types of mining machines were considered, as a means of achieving better roof control and coal output, and a Goodman full face boring machine was installed. Use of this machine resulted in a decrease in both the dimensions and the shape of the mined roadways, and this resulted in some improvements in the control of the roof.
However the reduction in the width of the mining place created by this machine proved to be a problem in terms of access around the machine, the ventilation of the working place, and the clearance surrounding the mobile plant chosen to accept the mined coal and haul it away from the mining place. While some improvement was made in the support of the roof and the ventilation of the face area, a decision was made to trial another model of the Goodman Boring machine. That machine was delivered and placed in service, and withdrawn after a short time, as it did not affect the improvements expected. While some ongoing and innovative attempts were made to eliminate the problems, the desired results were not achieved. The Goodman Borer was taken out of service, and replaced by the earlier continuous miner/shuttle car combination.
The quantity of methane gas released during and following the mining of the Bulli seam led to the installation underground,of a small capacity gas drainage plant. The objective of this plant was to gather the methane in the coal body before cutting the coal, remove it from the working place, and take it to the surface. This early plant proved to be completely inadequate, and in the early 1980s a surface methane drainage plant, comprising seven vacuum pumps was erected on the surface at the shaft site. A mine wide gas collection pipeline system was installed, and linked via one of the mine shafts to the surface drainage plant. This system of gas drainage did make some improvements in conditions underground. The gas collected by this plant was released to atmosphere.
In 1969 the Longwall Mining System was installed at the colliery. This plant package was supplied by Dowty Engineering UK. The roof supports in this package included a sliding inner, two leg roof support located erected between the outer two leg outer support legs of each roof support. This sliding inner leg and attached roof support bar was designed to provide immediate support to the roof, when the shearer passed along the face past that particular support. This package of plant demonstrated its ability to support the roof and did contribute to acceptable level of coal production, from the longwall.
Mining the Bulli seam at Appin was, as noted earlier, accompanied by high levels of methane gas, in the developing of longwall roadways, and the mining of longwall panels. This problem initially led to the predrilling of the coal seam prior to its being mined, to drain and collect gas from the seam and this practice continues at the mine. Gas is drawn into a mine wide gas collection system and linked by a pipeline to a battery of vacuum pumps installed on the surface.
This gas as noted earlier was initially being discharged to the atmosphere. In 1986 a methane gas powered 5.0 megawatt generating plant was installed at the shaft site and delivered a supply of electric power to the Appin Colliery and shafts site plant. The surplus power output was linked into the NSW State Electricity grid.
The Appin Colliery Explosion
At 11.00 pm on Tuesday 24th July 1979 a major tragedy occurred at the Appin Colliery. An explosion occurred underground in the Longwall K Panel of the mine, which resulted in the death of all fourteen men in the panel at that time. This tragic event was associated with work being carried out to change the existing ventilation system of the K Panel. The work involved in these changes commenced on the day shift, and continued on in the afternoon and night shifts.
The planned changes to the ventilation involved the completion of work on a mine ventilation overcast being erected over the central roadway of the panel. The purpose was to make that roadway the only intake airway into the panel, and the remaining right and the left-hand roadways the return airways, from the panel. It was during the final stages of this work that the explosion occurred.
The bodies of ten men were found in the panel crib room, located approximately 250 metres outbye of the working face area. The bodies of a further four men, (a deputy with an oil flame safety lamp, an electrician, a fitter, and a shift undermanager also with an oil flame safety lamp and a methane monitoring device) were found in the working face area of the panel.
A Judicial Enquiry into the disaster was conducted by Justice AJ Goran QC and was followed by a Coronial Enquiry, the two enquiries differing to a degree in their conclusions as to the direct cause of the explosion. A comprehensive paper setting out the circumstances of the explosion and loss of life may be found here. This paper was presented at the University of Wollongong Coal Operators’ Conference in 2010.
The two enquiries as noted differed in their conclusion as to the direct cause of the explosion – the actual ignition source. But the explosion itself was a methane/air explosion, and as noted earlier, the ensuing years saw much work done to mitigate the release of methane from the coal body being mined into the mine working area. This included pre-drainage of the coal seam, to ensure that a similar event could not occur in future.