Published in September 2009 Australian Longwall Magazine
In the fashion world it’s all about upcycling right now. For the inexperienced fashionista, that’s taking something vintage and giving it new life. That trendy fashion philosophy is being employed at Australia’s newest longwall starter – Gujarat NRE’s Wongawilli colliery near Wollongong in New South Wales. It’s an idea that could produce for the Indian company a nice little earner on Australian soil.
Gujarat picked up the old Elouera colliery from BHP Billiton in December 2007 for the bargain price of $49 million. The purchase gave Gujarat not only a coal lease, a recently working mine, ready-made surface infrastructure and the longwall equipment, but also underground driveage access to its Avondale colliery, avoiding the need to establish new surface infrastructure as originally planned.
Gujarat’s intentions in Australia, which it is successfully carrying out, are what other multinational or local coal companies have resigned to the too-hard basket. Gujarat is picking up idled mines with reserves still left, overhauling second-hand equipment and producing coal.
From this year through to 2013, Gujarat plans to recover 3 million tonnes of high-grade coking coal with the overhauled longwall at the renamed Elouera mine – Wongawilli. If, and more likely when, it pulls this off, the producer will have a mine up and running in a very small amount of time with, no doubt, very good margins.
When Gujarat picked up Elouera, longwall 17 had already been bolted up for eight months. BHP had completed the longwall and stored the equipment on the recovery face. All the emulsion in the roof supports was changed out to a storage fluid and all gearboxes were completely filled with oil. All the water cooling systems were filled with rust inhibitor.
Soon after buying the colliery, Gujarat progressed planning to recover the longwall for re-installation on the newly developed block 12 in July to August of this year.
In September 2008, a budget was put together to get the longwall up and running again. During the budget process, management identified that compliance to MDG 41 was going to be a real issue for the recovered roof supports and associated hydraulics. Extra funding was required to completely rehose the longwall.
“We looked at several options as to how and where this project would take place and, based on risk and cost, it was decided to do the complete rehose on the recovery face,” Gujarat longwall mechanical engineer Glenn Saunders said.
In December, the budget to rehose, recover and overhaul the longwall was approved, triggering the start of four months of planning to get the longwall operational again.
The existing equipment included roof supports manufactured in 1995 and pans, a shearer, drives and a Pantec puller sent over from BHP’s Tower colliery. From 2004 to 2007, 3Mt of coal was mined at Elouera with the equipment.
In January this year, Pirtek Fluid Systems was awarded the contract to supply hydraulic hosing to Gujarat.
“This partnership allowed us to really make a difference to the standards around high-pressure hydraulics and the awareness of the people that work on these systems,” Gujarat group engineering manager Steve Coffee said.
Pirtek coordinated training for the mine’s team before starting the rehose, providing hydraulic hosing diagrams in link one format so the installation of the hoses, fittings and staples could be achieved with a high degree of accuracy.
In January, the roof support rehose started with a small, full-time and inexperienced crew and two part-time roof support hydraulic experts. Longwall and Development Services and Inbye Mining Services each supplied an experienced mechanical service engineer.
Saunders said the roof support was broken down into seven separate circuits for seven separate hose kits.
“Every hose was given a code and serial number and we can now track all hoses on every roof support,” Saunders said.
The hydraulic isolation points were all redesigned and upgraded as part of the rehose.
Excluding the obvious challenges of the project, the Wongawilli team had to overcome some unforeseen hurdles along the way.
“There was a problem that the Department of Primary Industries highlighted with use of 20mm hose staples, particularly on the DA Ram circuit,” Saunders said.
“On all our supports we have now changed to 20mm Super Stecko hose and fittings on the DA Ram instead of the single 20mm staple.”
The rehose on the current 83 supports was completed with 10,042 metres of hydraulic hosing, 7480 hose assemblies, 16,500 adaptors and 32,120 staples replaced, and all supports fully audited and commissioned by the end of April this year.
“This, as far as I have been told, was a first for a complete longwall face to be rehosed on a recovery heading with all supports still supporting the roof,” Saunders said.
While the rehosing was being completed, the Gujarat team removed several pieces of equipment for overhaul. The Pantec puller, all the longwall transformers/PLC and all the chock pumps were brought to the surface for full overhaul.
The maingate and tailgate drives were also transported to the surface for small repair work and sprocket changes. A new armoured face conveyor chain and flight bars were supplied by Ellton Longwall and the shearer drums were fully overhauled by Kennametal.
Other suppliers working with Gujarat on the overhaul included Longwall Hydraulics, ABB, Joy Mining Machinery and Eickhoff.
No major design changes were required for the majority of the equipment as longwall conditions are going to be similar to those experienced previously.
Gujarat has, however, opted to change cutting sequences due to the existing goaf above longwall 12.
“In June 2009, with just a small crew working day shift, we were able to remove all the equipment bar the roof supports from longwall 17 by the first week,” Saunders said.
“Due to development delays, we did not get the new longwall installed until mid-June. Again, with the small inexperienced crew who had not even seen a longwall working, let
alone fully assembled one, we installed all equipment except the roof supports over about six weeks.”
During July, the roof support recovery of longwall 17 and installation to longwall 12 was completed, taking seven days.
“The longwall rehose undertaking was a project that allowed us to prove to ourselves that nothing is impossible. It’s the individual’s attitude, that seems like a little thing, that makes a big difference and we continue to lever off that,” Saunders said.
“The guys underground are proud of their achievement so far. We are in control at the moment and we have had time to do a lot of training to gain the experience necessary to maintain control during the ramp-up.
“Personally, I am finding it very challenging and rewarding.”
In August, longwall 12 commissioning and workforce training began with the installed face of Joy roof supports, Joy drives and pans and an Eickhoff SL 300 shearer. The mine has two new Joy continuous miners on order.
With the ramp-up of the longwall, Gujarat plans to increase run-of-mine production from the 179,000t produced in the 2009 financial year to an annual production of 1.5Mt.
Looking ahead, Coffee said conditions were expected to be good on longwall 12, although the existing goaf above the panel meant well-supported gate roads and strata management plans would be in place.
“Longwall 11, which is a rehand and will require an extra 27 supports, will be a challenge as we will be going through a high-stress zone. We also have to shorten the block by 60 supports midway through then cut around the old goaf area and extend the longwall back out to 110 roof supports.
“Longwall 19 will also be a challenge as we will take the longwall through 20 existing cut throughs.”
The longwall will then be taken into an old part of the colliery that hasn’t been mined since 1992 to cut six longwall blocks.
It is then back to known ground with longwalls 15 and 16, with conditions expected to be similar to longwall 12.
“We will have a planned 10 longwall changeouts over three to four years. It is not going to be easy but a challenge that I look forward to,” Saunders said.
“The plan after that is we will head into the new colliery, Wongawilli South/Avondale, and this is when we will see a large increase in production.”
Wongawilli’s timeline
April 2007: BHP Billiton bolts up Elouera and leaves longwall in storage on the recovery face
December 2007: Gujarat NRE buys Elouera from BHP
December 2008: Budget approved to rehose the longwall and overhaul the existing equipment
January 2009: Rehose starts on the recovery face
June 2009: Equipment removed from longwall 17
July 2009: Longwall 12 installation
August 2009: Longwall 12 commissioning and training
Rehose stats: Rehose of 83 supports involved 10,042 metres of hydraulic hosing, 7480 hose assemblies, 16,500 adaptors and 32,120 staples
