Lafarge Aggregates choose Sandvik Hydrocone
Lafarge Aggregates’ Dry Rigg Quarry, near Settle, North Yorkshire, has been quarrying and processing high-quality greywacke (locally referred to as gritstone) for more than 40 years. The quarry supplies high-PSV chippings to sites and depots as far afield as Hampshire and Edinburgh. Material from Dry Rigg has even been supplied to the Falkland Islands for the resurfacing of the airfield runway.
During the winter of 2004/5 Lafarge entered into discussions with various crusher manufacturers to upgrade the ageing tertiary section of the quarry’s existing plant, with the objective of increasing the quality and yield of key products. Sandvik, with the aid of their Plant Designer simulation software, were able to simulate both the existing plant and the proposed development, aiding Lafarge in their evaluation of the viability of the project. This tool proved to be invaluable, not only in the assessment of the final solution, but also for the assessment of alternatives that were subsequently disregarded.
Sandvik eventually secured the order with a solution that involved the replacement of two existing 3ft Shorthead machines with one Sandvik H4800 Hydrocone, fitted with the Sandvik ASRi control system. The proposed solution was implemented in the spring of 2005, with local engineering contractors Gissing & Lonsdale being employed to install the new crusher. Installation on the foundations of one of the old Shorthead machines was rapid owing to the use of a transitional frame, manufactured by Gissing & Lonsdale, to support the normal Sandvik floating frame that incorporates both the crusher and the drive motor.
The Sandvik ASRi control system has played a major part in the production improvements experienced at Dry Rigg. The system is able to operate in conjunction with all Hydrocone crushers and is the latest in a new generation of computer control systems that simultaneously monitor the crusher power draw, Hydroset pressure and position of the main shaft. All these parameters, together with program selection, calibration and a review of current and historical data, are stored and displayed on a remote display with a ‘touch-sensitive’ screen, mounted in the control cabin (fig. 1). The plant operator is now able to monitor, make adjustments under full operating load without stopping the crusher feed, change crushing programs and calibrate the crusher without leaving the control room. This has proved to be an additional benefit both in terms of productivity and the health and safety of the operators.
Sandvik are continually developing crushing chambers to maximize the yield of key size fractions. At Dry Rigg this has led to the selection of a chamber that has resulted in a significant increase in 10mm production. This can be seen on the accompanying graph (fig. 2), which demonstrates the steep gradation of the curve, maximizing the yield of 10 x 6mm product.
Installation, operation and an increase in the quality and yield of key products have all proven very successful, with yields increasing by over 25%. However, Lafarge have a rigorous policy of carrying out an audit of all capital projects to ensure the equipment is not only performing, but also producing the return on investment originally predicted. Lafarge have reported that the KPI (Key Performance Indicator) for Dry Rigg Quarry has seen a substantial improvement, solely attributable to the H4800 since its installation.
Bill Craggs, Lafarge cluster production manager for the North West, said: ‘The H4800 has not only met all the criteria that were predicted, it has exceeded them.’
