The town of Collie is situated 200km south-east of Perth within Western Australia’s only coalfield, which boasts two large coal mines. These coal mines are the main source of energy for the local power station, offering a reliable supply of electricity to the region. Following a breakthrough by Crusader Hose in the manufacture of a high pressure flexible hose for mine dewatering at depths up to 300m, Premier Coal, the largest of the two mines, chose to replace the fibreglass pipe connecting its deepest bore to the dewatering system with Flexibore® 300.
Premier Coal was previously owned by Wesfarmers Coal, but is now part of Yancoal Australia. In 2008, a major pipeline was installed at the open cut mine to lower the water table.
A large 600mm diameter ring main was installed around the perimeter, and 40 deep bores were drilled inside and around the pit. These bores are all between 199-245m deep – except one, which is 252m deep – and connected to the ring main to help keep the water table low.
Test pumping was carried out on all bores to measure the drawdown level, and the Perth-based consultant designing the system specified 150kW submersible pumps and flexible hose. Mark Sanders of Think Water Bunbury was then selected as the prime contractor for this dewatering project.
Using his 40-plus years of pumping experience and expertise with other Premier Coal mine projects to make his recommendations, Mark combined Grundfos Pumps with Flexibore® 250 rising main from Crusader Hose for 39 of the 40 bores.
A high performance hose
Flexibore® was chosen as the preferred hose for the dewatering system due to its ease of installation and excellent hydraulic performance.
“Flexibore® can swell up to 15 per cent under pressure and this dilation eliminates any build-up of iron bacteria or internal scaling,” Francois Steverlynck, Managing Director of Crusader Hose, said. To assist Mark carry out the first installation, Francois flew to WA.
Installing the flexible hose
To install the hose, it was rolled out, the pump connected and the power cable attached along its length, with Think Water able to install the pumps at a rate of one per day.
Only one bore– the deepest bore at 252m – was not suitable for using flexible hose as the depth exceeded the safety margin of Flexibore® 250. Fibreglass pipe was used instead, which required more labour and took three days to install due to the complexity of handling 6m sections of rigid pipe.
“That one pump for which Flexibore® could not be used really challenged me as I was unable to supply hose for the large submersible pump installed over 250m deep,” Francois said. “Because of this, I set the Engineering Team a challenge to fabricate a hose that could go down to 300m into a bore.”
A breakthrough flexible hose design for high pressure environments
Crusader Hose is an innovative company with a strong culture of continuous improvement and its Engineering Team has had a recent breakthrough – the ultra-high-pressure Flexibore® 300 series hose, which is the highest pressure layflat hose in the world for mine dewatering, with a burst pressure of 900m.
Mark re-entered into discussions with the dewatering supervisors at the mine about this new capability. “They were pleased to hear about this development and were impressed by the perseverance at Crusader Hose.
They were also pleased that all their original Flexibore® risers were still working well after more than 12 years of continuous pumping.
Based on this, we secured an order for a 252m length of the new Flexibore® 300 to replace the fibreglass column,” Mark said. Francois said the Flexibore® 300 is truly a pioneering achievement in the history of Crusader Hose.
“This development will hopefully be keenly adopted by many Australian mining companies and enable them to keep at the forefront of productivity and continuous improvement,” Francois said.
This partner content is brought to you by Crusader Hose. For more information, visit www.crusaderhose.com.au.