The Irish-headquartered company says that installing the system at the quarry has required some serious advanced enabling and civil engineering solutions. An Epiroc MB 1200 hammer is being utilised as part of the installation of system.
Kelly Earthmoving has a UK base in Preston and undertakes a variety of specialist work across the country. Whilst having Earthmoving in its name, the company headed up by Gerry Kelly offers a more specialised service to its long standing clients. “We can move earth, but that’s a little boring to us," says Gary Kelly. “We move earth from places others can’t or won’t get to.”
In addition to moving awkward earth, Kelly Earthmoving also incorporates complex ground engineering into the package. The company provides bank stabilisation, piling and de-vegetation work, in addition to specialist equipment.
“We already undertake rock breaking and cutting for our existing clients,” Kelly explains. “But this project has seen us extracting and breaking far more rock than we have ever done on a single job. It’s been a tough but enjoyable project to be involved in but also one that has been hard on the equipment.”
The project has seen the Kelly team on site for 12 months working on two separate sites. The terminal anchor point for the suspended conveyor system has been excavated and construction of a large concrete foundation is underway. This left the small, experienced team working almost at the top of the quarry and adjacent to an existing haul road.
The team has already created a working platform to allow the civil contractor to construct a piled wall which released the area required to construct the suspended conveyors deflection tower. Once completed, the Kelly team were back on site to create a 33 degree ‘slot’ through the upper quarry benches to accommodate the conveyors cable catenary profile.
From the upper platform, Kelly formed a slope down through the mudstone and rock to where a second working platform was broken out and levelled. At this point the team encountered the very hard rock that the quarry is famous for.
“We had a number of options for the removal of the rock head,” says Kelly. “We looked at sawing sections out, but the rock was littered with enough fractures that allowed us the quicker option of using hydraulic breakers instead.”
Whilst some of the exposed rock was easy to remove, the company found that the material below wasn’t and ended up breaking a number of hammers and countless chisels in the process.
“It was getting beyond a joke. Every couple of days we were breaking a chisel or sometimes more.” Kelly explains. “Our usual hammers were struggling with the hard rock so we decided to look at investing in something more reliable and productive to complete the job. Coyle Equipment Services has been supporting us on this project from their new, purpose built depot in West Bromwich, so on the advice of William Coyle we used an Epiroc MB 1200 hammer as a replacement for one of our existing tools."
He said his company has been very impressed with the Epiroc breaker’s reliability and performance in driving a path through the rock. Kelly says the 12-tonne, 157hp Menzi Muck walking excavator wields the Epiroc MB 1200 hammer with ease despite it being designed for the larger 15-26t carrier range.
“The Menzi is just a massive powerpack,” Kelly says. “It will push out over 200 litres per minute with the Powerline pump, far more than the Epiroc breaker requires.”
Lift capacity even at its full 6m reach is over 4 tonnes which Kelly says makes the Menzi an ideal hydraulic attachment carrier. Carrying a hefty 120mm diameter chisel, the MB 1200 delivers between 340 and 680 blows per minute which according to Kelly is more than capable of taking apart the rock they are now encountering.
Fitted with Epiroc’s AutoControl system, the hammer is able to detect pressure on the chisel. It also detects when the chisel breaks through the material to protect it from blank firing and causing potential damage to the percussion chamber.
“We’ve been very impressed with the hammer,” Kelly comments. “It’s more compact than the ones we have in the fleet, yet the performance is far better than anything we have used before. We’ve not had to change the chisel at all as the Epiroc original seems to be made of stern stuff.”
Despite having to deal with the pandemic and bad weather, Kelly says his company's team has delivered an impressive result for the quarry’s project team. “The men and machines have performed very well on the project,” he adds. “We don’t take on ordinary jobs, we always like a challenge!”