At a large quarry in the Midlands, Kelly Earthmoving have delivered some enabling works associated with the installation of a cable suspended conveyor that will span nearly 1km across the quarry. Installing this system has required some serious advanced enabling and civil engineering solutions.
Kelly Earthmoving were brought on to the site due to their experience and specialist capability. The Irish company has a UK base in Preston and undertakes a variety of specialist work across the country. Whilst having Earthmoving in their name, the company headed up by Gerry Kelly offers a more specialised service to their long standing clients. “We can move earth, but that’s a little boring to us.” Gerry jokes “We move earth from places others can’t or won’t get to.”
Not only does Kelly Earthmoving move awkward earth but they also incorporate complex ground engineering into the package. From bank stabilisation, piling and de-vegetation work, the wide variety of services offered by the company, allied to the specialist equipment they run, puts them in a leading position for the technically demanding projects their clients entrust them with.
“We already undertake rock breaking and cutting for our existing clients.” Gerry 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. At the time of our visit, the terminal anchor point for the suspended conveyor system had been excavated and construction of a large concrete foundation was underway. This left the small but highly experienced team working almost at the top of the quarry and adjacent to an existing haul road. The team had 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.” Gerry explains “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.”
Gerry 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. And to be fair, we have been very impressed with the Epiroc breaker’s reliability and performance.”
Carefully driving a path through the rock, the 12 tonne, 157hp Menzi Muck 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.” Gerry explains “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 making 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 Gerry 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.” Gerry 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 a pandemic and bad weather thrown at them, the Kelly team has delivered an impressive result for the quarry’s project team. “The men and machines have performed very well on the project.” Gerry comments “We don’t take on ordinary jobs, we always like a challenge!”
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