Development of the $290m 5Mtpa project is on track for a start of longwall production in September next year, a few months ahead of the original schedule, not from the famed Bulli seam but from the number 3 Wongawilli seam, also highly prized by steel makers worldwide.
Those outside the Illawarra do perhaps not appreciate the complexity of the Dendrobium project. The initial mine plan calls for mining in three areas between previously mined areas and takes mine life out to 2027.
Beyond that there is a fourth area that contains more coal than the other three areas combined. The contract with the major customer, BHP Steel, is for an initial 30 years.
Already 100,000t of development coal have been stacked at the Kemira Valley coal handling plant and the first train load of coal was railed to the BHP Steel Port Kembla steelworks, just 7km away, on June 5. Dendrobium, incidentally, must have the shortest railing distance of any coking coal mine in the world: just 7km to an export port.
While Walter Constructions Group has initially undertaken development and construction, BHP Billiton has been busy recruiting and training its own workforce for the long term future.
Cuzzubbo is proud of the diversity of what will be an eventual 170-strong workforce. This is a workforce not just drawn from the traditional pool of coal miners in the Illawarra region but from throughout Australia.
New culture
“Our focus is on people, safety and standards,” Cuzzubbo says. Dendrobium is a new mine with a new culture.
“Dendrobium has had an opportunity to hand pick its workforce and is consequently using world’s best practice recruitment and selection techniques to attract the best people in the mining industry, whether coal or metalliferous.
“The selection process is based on applicants meeting the essential criteria of being aligned to the key values of Dendrobium Coal.
“In the first development crews we have employed a range of people from local mines, Queensland coal and metalliferous mines, not to mention newcomers to the industry.”
Cuzzubbo says the aim is to develop a one-team approach right across the site. All are under the same incentive schemes, which have team and project-wide components.
There is no demarcation and each team will be able to carry out a range of jobs. They will work out among themselves how to resolve issues and workloads.
The team leaders were recruited four months ahead of the rest of the teams to enable them to be intimately involved in recruitment and to work through how they effectively operate their work places with their teams.
This one team approach, incidentally, sees an end to managers’ bathhouses, clothing for supervisors, and other “them and us” type distinctions.
The first crew of the 170 who will work underground has already completed its lengthy induction process, bringing a third continuous miner into play for mine development. Cuzzubbo anticipates healthy competition between the crews to achieve the highest development rates.
A fourth crew will be recruited later this year to enable seven day, 12-hour shifts. Cuzzubbo says the seven-day, 12-hour rotating roster pattern was chosen after considering all aspects of health and safety, business performance and lifestyle preferences.
It was judged that working three or four days, followed by a complete break of three or four days would offer the employees the best lifestyle pattern in the area.
Taking shape
With $155m of the $290m capital expenditure already committed, the mine is rapidly taking shape. The mine surface facilities are already completed, based around the ex-Nebo mine offices and bathhouse.
The concrete floor of the workshop has to be re-laid because of a secret vault underneath where all the plans and documents about the Port Kembla steelworks were concealed during World War II.
The surface facilities separate heavy mine vehicles from light vehicles for refuelling and access purposes.
In an unusual underground flourish, pedestrians have right of way over vehicles. Vehicles must stop, and they do, until pedestrians have safely passed.
The ventilation shaft and fan have been finished and commissioned, two major underground conveyors are nearing completion, the Kemira coal load-out rail station in the aptly named Hidden Valley is nearly operational and – with 5km already driven – the longwall mains development is well underway to a mining height of 3.3-3.4m.
Driving of the first longwall panel maingate and tailgate will follow in the next few months.
Initial development was undertaken using a road header, producing a typical tunnel profile.
Now, however, development is being undertaken by Walter Construction Group using conventional Joy 12CM30 continuous miners and by BHP Billiton with upgraded Voest Alpine ABM20 series 3 cutting/bolting units.
Many mines are replacing ABM20 units, citing a range of operational problems, but BHP Billiton is supportive of the units, especially in seam heights like those at Dendrobium where the unit takes the miner closer to the roof for easier bolting, especially under conditions with high density roof support requirements.
The Dendrobium units have been upgraded to the mark 3 version, which Cuzzubbo says makes them similar to the standards of the ABM30 units used successfully in South African mines.
Larger dust blankets are used to shield the cutting head, while dust is sucked back into the coal chute by a fan, away from workers. New Hydramatic drill rigs have been fitted, as well as new much larger loader blades.
For increased safety against rib spalling, the bolting platform extends further to support the rib while protecting the worker.
In addition, the upgraded ABM20 can load-out stored coal to a shuttle car in 40 seconds, similar to a conventional continuous miner, against the previous two minutes.
Voest Alpine is putting its money where its mouth is with these ABM20 units. The upgrade contract is tied to a performance specification that guarantees 5.5m advance per operating hour.
The continuous miners are coupled with upgraded Joy 15SC32 15t-payload shuttle cars.
Wide and high drift
A feature of the Dendrobium mine is the wide and high drift into the coal seam (for transport and ventilation reasons) is concreted throughout, currently to around 700m from the portal.
However, Cuzzubbo says the plan is to concrete all major roads in the mains development, including access to all three mining areas, something that is essential because of water issues and speedy travel times.
Around one third of the first mining area, Area 1, is under the old Mount Kembla mine workings that worked the higher Number 1 seam. Besides geotechnical issues of localised high stress, the old workings are flooded. The adjacent Nebo workings, in the same Wongawilli number 3 seam, although down dip, are also flooded.
The intention is to drain the Mount Kembla workings once a pipeline is in place in the next couple of months. Until then, the mine has to contain and pump out the water that seeps into the roadways.
Holes are being drilled into the Mount Kembla workings, with the water either taken away by pipeline or funnelled to the Nebo workings that will effectively act as a sump.
The water taken offsite will be carried by a 5km long by 250mm diameter pipeline right down the Illawarra Escarpment to a location next to BHP Billiton Illawarra Coal’s head office where, being saline, it will be discharged into a tidal part of the creek system.
This pipeline system has large redundancy built in. Just on gravity alone it can handle up to 10ML/day and, with the addition of pumps, that figure can rise to 15ML/day.
Unlike water, gas is not an initial problem at Dendrobium. The first two areas to be mined have low methane levels of 3-5m3 a tonne.
However, in the third area to be mined, after 2010, the gas content rises to 15-17m3 a tonne and therefore gas drainage will be needed prior to mining, with each developed panel being drained for approximately two years before mining.
Longwall
Due to rationalisation of its Illawarra assets, BHP Billiton has not had to order a completely new longwall package.
For example, the longwall itself will use 180m of chocks from the Eloura mine that are relatively new and which will be fully refurbished.
A further 60m of new supports will be supplied by Joy Mining. These 1050t chocks are 1.75m wide and are currently being built in the UK. They are due for delivery around March next year so that a surface mini-build can be effected.
The new chocks will be used in the initial 240m wide face located towards gateroads where there are higher roof loadings.
Joy Mining has also gained major orders for new equipment designed for 3500tph operation: an armoured face conveyor; stage loader, a 7LS shearer and ancillary equipment.
Other suppliers include iPower for the power supply equipment, Flack Woods for the ventilation fan, Ardet for the ventilation shaft, and Anderson Industries for a modified Caterpillar grader.
Longwall panel one in the mining Area 1 is due for start up by September next year, several months ahead of schedule. This will be 240m wide by 2.4km long, or about one year’s production. It will be followed by a second panel in the same area of similar width and up to 2.3km long.
Further ahead there will be three panels in mining Area 2, also located between existing mined out areas. Around 2010, mining enters Area 3.
This area, with no limitations, will enable the longwall face to be expanded to a 300m width with blocks 5km long, and containing around 8Mt of coal.
In terms of anticipated productivity, Cuzzubbo tells Australian Mining that the project is predicated on around 30,000tp person year, based on mine site employees only.
The mine plan calls for production to start at around 4.6Mtpa and then grow to over 5Mtpa over the next couple of years. There is further upside to that output.
Walter Constructions’ contract extends to September next year to cover development up to the start of longwall panel one. However, depending on performance, this could be further extended as Dendrobium will require assistance in development of the mains and longwall panels until the 2008-2010 period.
Rill tower
Coal will be transported by underground conveyor 1.3km to the rail load-out facility at Kemira. The conveyor, being built by a joint venture of Walter Constructions and Continental Conveyors, has only a small, 70m low angle up dip, and then dives spectacularly out of the hillside on high trestles to spill out onto the stockpile, which is also constructed by Walter Constructions.
The 1.8m wide belt conveyor has a capacity of 4500tph but has been built with the potential to upgrade to 6000tpa. Its steep dive while loaded allows it to actually generate electricity to feed into the mine system.
All belt structures hang from the roof for easy of maintenance and cleaning of spilt coal.
The massive rill tower will load the coal into trains passing through an Ingal steel tunnel that runs under the stockpile. The stockpile has a capacity 150,000t.
Because of the compact nature of Hidden Valley, which is located next to the now disused O’Brien’s drift tunnel that used to bring coal down the Illawarra Escarpment, the trains cannot be operated in a conventional loop.
Instead, the locomotives will haul the wagons up to the entrance of the load-out, disconnect, run down a parallel line to the other end of the train and then push the wagons through the load-out tunnel. As a consequence trains will be limited to loads up to 1800t.
An integral part of the project is the washery at Port Kembla steelworks itself, which will have around 40 employees. This will incorporate a $25m thermal drier supplied by Heyl & Patterson of the US to reduce coal moisture content to the requirements of the steelworks.
A major emphasis during the whole Dendrobium project has been the local community. The mine and railway will in places operate very close to houses.
At the narrow ledge on the Illawarra Escarpment, which is the access to the mine, a high noise-baffling wall will be a permanent installation.
And, with the rail line to Port Kembla passing within six metres of some houses, great care has been given to reducing noise. A 10dBa reduction has been achieved by such measures as modifying the class 81 locomotives, changing brake shoes, altering the couplings and educating the drivers.
As a further gesture towards the community, three cents per tonne of coal produced, or up to $120,000 a year, will go towards community projects.
The first two of these, a children’s park and a walking track based around the Mount Kembla mine disaster memorial, are already underway.
FOOTNOTE: There is obviously no smoking underground in coal mines, but Dendrobium has a policy of no smoking whatsoever on site. The only smoking area is outside the main gate, making its BHP Billion's first non-smoking coal operation in the Illawarra.
Mine plan calls for production to start at around 4.6Mtpa and then grow to over 5Mtpa over the next couple of years.