Quarrying

rom their base in Frome in the West in Cider Country, WCD FSleeman & Sons Ltd supply drilling and blasting services to a total of 18 quarries in and Herefordshire, counties that have extensive cider Country apple orchards, abundant limestone and good rail connections with London. Output from most of these quarries is The company provides the drill ‘as-needed’ basis to avoid the crushed and screened and then rigs and site personnel, and potential problems associated transported by rail to London on undertakes the design and layout with site magazine location and purpose-built trains. of the blasting grid, surveys the security. The lower 6m of each Founded some 27 years ago by holes, carries out laser profiling of prepared hole is loaded with William ‘Dixie’ Sleeman, with a the face and specifies the blast 13kg/m of Orica bulk emulsion single Atlas Copco pneumatic drill design. Most drilling and blasting and a 16L Pentolite booster rig, the company now operates a contracts are ‘rock-on-ground’ primed using a Sureline non- fleet of eight Atlas Copco down- packages, which are priced on a electric detonator. The top 4m of the-hole (DTH) machines, per tonne or per cubic metre each hole is stemmed using comprising two ROC L8s, one basis. 14mm chippings. ROC L6 and five ROC 460s. All of Sleeman’s first venture outside Following blasting, Wainwright these machines are moved Cornwall was in 1983 when they use an excavator and 40-tonne frequently between sites because were awarded a contract by John dumptrucks to deliver the rock their individual productivity Wainwright & Co. Ltd at Moons to the primary crusher at the outstrips the capacity of any Hill Quarry, Somerset, which has main pit, some 1.2km distant. single client quarry. However, the been in operation for over 100 Here, the material is crushed and combination of fast drill rigs and years. This site’s long-term screened to form up to 12 ease of movement makes good success lies in the fact that it is different roadstone products, economic sense and is becoming the only local source of basalt some of which are consumed on increasingly popular among and, despite a regular output of site in Wainwright’s own coating Sleeman’s ROC L8 at contractors working small and around 1 million tonnes per year, plant. The remainder is stocked ® Moons Hill Quarry medium-sized quarries. The ROC still has 80 years of accessible series of drill rigs is designed with reserves under development in a easy transportation in mind, and westerly extension of the main the dimensions of all of the pit. Sleeman machines are well within Today, nearly 20 years later, the European guidelines for Sleeman are still the drilling and movement by low-loader, so no blasting contractors at Moons permits are required. Hill, employing one of their new ROC L8 drill rigs at the site. Company history Sleeman originated in Roche, Moons Hill Cornwall, near to the largest Quarry china clay operations in the Wainwright’s Moons Hill Quarry world. Here, William ‘Dixie’ is a typical Sleeman drilling and Sleeman was, for many years, blasting contract. In an extension operations manager for Mid of the main pit, the ROC L8, Cornwall Contractors, a drilling equipped with a Secoroc COP 44 contractor with a fleet of Atlas hammer, is employed drilling Copco drill rigs. The fledgling 115mm holes on a 4.0m x 4.0m Sleeman company was originally grid pattern. The bench height is engaged by English China Clays 10m and the basalt itself is hard (ECC) in drilling and blasting the and loose jointed, a situation in granite dykes that were inhibiting which DTH drilling excels. The hydraulic extraction of the clay. face angle is currently 15°, but Since their inception, Sleeman this may be reduced to 10° in have offered a full drilling and certain areas. blasting service to their clients. Explosives are delivered on an

QM May 2002 www.qmj.co.uk 13 Chipping Sodbury, where some 500,000 tonnes of rock is being drilled and blasted. The ROC L8s also work at ’s and Dulcote Quarry. Three of Sleeman’s Atlas Copco ROC 460 drill rigs are also engaged in small jobs around the Mendips, while the fourth is based at Tarmac Western’s Bayston Hill Quarry, near Shrewsbury, and the fifth covers Tarmac Western’s Strinds, Dolyhir and Gore quarries. Each of the ROC 460 drill rigs is powered by an Atlas Copco XR compressor rated at 12–20 bar pressure. Sleeman’s ROC L6 rotates between three drilling and blasting contracts located at Tarmac Southern’s , Stancombe and Durnford quarries. Bench heights at all these operations are in the order of 14–15m, which is close to the maximum height allowable in the UK without a full geological survey. Hole size is normally The ROC L6 tramming in the open for sale and is right, as well as backwards and 115mm, but around 20% are into position shipped out by the company’s forwards. drilled at 127mm diameter. In the own fleet of trucks or by The rig is powered by a limestone rock that characterizes customers or contract haulage. 317kW (431hp) Caterpillar diesel most of these sites, a 4.5m x Every month Sleeman bring in a engine, while an on-board Atlas 4.5m grid pattern is employed in 20-tonne excavator equipped Copco screw compressor order to reduce fly-rock and with a hydraulic breaker to deal delivers 405 litres/s (858ftJ/min) concentrate the rock pile. with any build-up of oversize of air at 25 bar (363psi). The Secoroc Magnum boulders. The unit is capable of drilling premium-quality drill bits being holes as large as 165mm (6.5in) used last a minimum of 1,000 Atlas Copco ROC down to depths of 54m (176ft), drilled metres and are treated as L8 and flushing them clean for consumables, so re-grinding is not The ROC L8 from Atlas Copco is charging. The ROC L8 can be carried out. a high-production crawler rig, fitted with a range of Atlas Copco Planned performance for the mounted on heavy-duty tracks, Secoroc DTH rock drills such as ROC L6 and ROC L8 machines is with ample power to deliver high the COP 44, COP 54 and COP 1.5m/min, and 600mm/min for the penetration rates and deep holes. 64 (4in, 5in and 6in, respectively), smaller ROC 460s. It has a rod-handling capacity for which are among the fastest on Sleeman have eight operational hole depths of 54m and can be the market. staff and two working directors, used for both pre-splitting and An electronic system for hole the latter comprising Steve production, making it a complete inclination and depth control Sleeman and his brother. There solution for drilling in quarries ensures that the blast holes are are four blasting licence holders and open-pit mines. accurately aligned. to handle the 5.5 million tonnes The ROC L8 cab provides per year extracted under the good all-round visibility and a Contracts various drilling and blasting user-friendly instrument layout, elsewhere contracts. Atlas Copco Construction & Mining and meets all international safety Sleeman’s second ROC L8 joins Ltd, Swallowdale Lane, Hemel requirements. The machine is its sister machine in providing Hempstead, Herts HP2 7HA; tel: equipped with a high-performance drilling services to seven or eight (01442) 222100; fax: (01442) 234467; DTH rock drill for fast and other quarries in and around the email: [email protected]; website: straight drilling, and features a — the Somerset www.atlascopco.co.uk hydraulic break-out table and geological structure that hosts double drill-steel support, which large limestone reserves. Among helps the operator to thread and the sites being worked are unthread the drill steels. The rock Hanson Aggregates’ Battscombe drill assembly is mounted on a and Tytherington quarries. flexible single-section boom with Sleeman are also carrying out a wide feed swing to the left and development work for Hanson at

14 www.qmj.co.uk QM May 2002