During 2010, the huge 328 hectare Lafarge cement manufacturing site at Hope in Derbyshire, was presented with a health and safety challenge that would require a novel solution that is unique in the United Kingdom.The site is divided into three areas: the actual works and batching plant, which cover 63 hectares; a 109 hectare shale quarry; and a limestone quarry that covers a further 156 Hectres.
The limestone quarry operates 12 benches - each measuring 15 metres in height - covering three geological periods of Carboniferous limestone, all of which have to be mined simultaneously due to the differing silica content of the limestone. The silica content is high in the top benches, extremely high in the middle and low at the bottom. As a result there has to be a constant mix of the mined material. Cement has to be made from all three types of limestone. Blasting takes place an average three to four times per week with each blast producing between 15,000 and 20,000 tonnes.
The Health and Safety Executive (HSE) insisted that, as each bench was processed, the faces should be dressed as well. The only practical and economical solution was to use an excavator to load out the blasted material and to dress the benches as works progressed. Finding an excavator with a suitable combination of loading power and reach was one challenge; finding a method to allow that machine to move quickly around the site was quite another.
“Although we have great faith in our local Finning account manager Dean Turner, we pointed out that any excavator required to travel around a quarry of this size with such regularity would run up huge undercarriage repair and maintenance costs and would prove uneconomical,” says Lafarge’s deputy quarries manager Colin Reid. “But then he showed us a video of a transportation system and our scepticism turned to intrigue.”
The excavator solution came in the shape of a Caterpillar 390D ME excavator fitted with a 3.4 metre stick and 6.9 metre Smart Boom supplied by sole UK Cat dealer Finning UK Ltd. To move the 90 tonne machine around the site, Finning further recommended the addition of the Sleipner E90 transport system; a pair of heavy-duty, double-wheeled dollies that fit on the excavator tracks.
The Sleipner system allows the excavator to drive onto the dollies, (idler first) releasing the automatic braking system. The excavator then turns around and lowers its boom into the back of a tipper, using the bucket as an anchor, and effectively turning the excavator into a wheel-mounted trailer that can be towed around the site at around 10 times the travel speed of the excavator under its own power.
Once on station, the excavator operator simply raises the boom releasing it from the tipper, and drives off the Sleipner wheels.
Although the Finnish-developed Sleipner system is used extensively around the world, the Hope Quarry is the first installation in the UK, and is the culmination of a protracted approval process that took more than 12 months. Indeed, Finning even took a representative of the Health and Safety Executive to a quarry in Germany to show a Sleipner system in action, a move that ultimately convinced the HSE of the system’s efficacy.
The system is built to accommodate 30, 50, 70, 90, 100 and 120 tonne machines on a four-wheel system, and 190, 250, 310 and 400 tonne machines on the original eight-wheel version from which the company derives its name (after Sleipnir, the mythical eight-legged horse that carried Norse god Thor into battle).
According to Sleipner export and marketing manager Nichole Beyer, the Sleipner system is simple to use and has a payback time of less than six months. “Customer experience around the world has demonstrated an average five percent increase in productivity, but where most companies make real savings is in the reduction of undercarriage wear,” she says. “Most excavators will go through three sets of tracks in a lifetime. At more than £50,000 per set, there are significant cost savings to be made if equipment owners can safeguard those tracks by using our system.”
Beyer points out that the repair and maintenance advantages don’t end there. “Traditionally, an engineer would have to carry out repairs in the field because it was just too time consuming to drive an excavator back to the workshop,” she explains. “Our system means that the machine can be returned to the workshop in a fraction of the time, protecting the engine and hydraulic lines from the ever-present threat of dust contamination associated with open-air repairs.”
Working with a new excavator, open-air repairs are not yet a concern for Lafarge deputy quarries manager, Colin Reid. But he is already convinced of the Sleipner system’s operational benefits. “I would readily admit that our initial feeling towards the system was one of scepticism. But after being transported using the system a few times during training, all of our operators said they liked the system,” he concludes. “And while it is still early days, the Sleipner system has already significantly reduced face change times and had a positive impact on our productivity levels.”
Thanks for this story go to our friend Mark Anthony of Demolition News.