REFILL: low-cost fillers from quarry waste

Leahill Quarry is located on the coast of SW Ireland (near Adrigole, Co. Cork) in an Upper Devonian gritstone (fine-grained sandstone) sequence that is worked to produce high specification crushed rock aggregates (exported into UK and mainland Europe). The nature of the rock results in large quantities of fines being produced during processing. Leahill Quarry produces about 270,000 tonnes per annum of fines (0-2mm materials) and ‘filler’ (material passing 75m) after processing (washing). In an attempt to find new outlets for Leahill fines, Tarmac Fleming and BGS took part in a three year EC–supported industrial research project called REFILL, which included other UK and Greek partners and was managed overall by MIRO (Mineral Industry Research Organisation). Further details on the project are available by contacting MIRO through their website at: www.miro.co.uk. The REFILL project consisted of various tasks which involved both Tarmac Fleming and BGS. Tasks 1 to 3 involved a study of existing production practices and a programme of technical evaluation of the fines from Leahill and other quarries in Britain. This involved characterization of the mineralogical, physical and chemical properties of the residues. Task 4 was a large-scale continuous test at Leahill Quarry to determine the effectiveness of a novel fluidised bed plant in terms of its ability to extract ‘filler’ from the 0-2mm fines. Tasks 5 to 8 investigated the potential end uses that could incorporate Leahill filler and fines, including an assessment of the available resources of fines, the availability of fines acceptable for particular applications and a review of the market potential for end-uses including asphalt, concrete, artificial soils and non-plastic sub-base materials.