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Tonnage
150tph
Material
Sand & Gravel, Claybound Aggregates, Limestone, Crushed Rock
Output
Washed Sand & Aggregates
THE CHALLENGE
Creagh Concrete is the largest land based sand and gravel producer in Northern Ireland. The sand and aggregates they produce at various locations are used in the production of a range of pre-cast products as well as ready mix concrete.
"We currently produce 500,000 tonnes of material per year with 75% used internally and the remaining 25% being sold to the local market" explains Willie Doherty, Divisional Director at Creagh Concrete. The upgrade to the existing CDE washing plant was required as a result of a band of extremely difficult material being exposed near the floor of the pit. This material was not able to be processed effectively through the existing crushing, screening and washing plant due to high levels of plastic clay.
"Using our existing processing system we were not able to extract any value from the raw material" says James Diamon, Quarry Manager at Creagh Concrete. "The absence of a suitable attrition system within the existing plant needed to be addressed and it was at this point that we engaged with CDE to provide a tailored solution." The reserve is characterised by Agglomerate material with approximately 30% waste. Initial discussions with CDE were focused on establishing whether it made commercial sense to invest in a new processing system.
“The material we were faced with is among the worst that I’ve seen and at the outset all options were on the table including ceasing production at Draperstown and looking for reserves at a new site” says Willie Doherty. “The ideal solution was to be able to continue working at the existing site as all the required planning consents were in place which has obvious time and cost benefits.” Detailed discussions with the CDE Project Design team followed and the outcome was agreement on a two-stage upgrade to the existing plant.
THE SOLUTION
The first stage involved an upgrade of the existing water treatment and recycling system. This saw the replacement of the existing Aquacycle A400 thickener with the Aquacycle A1500. “Before we could consider beginning to process this difficult material the water treatment system needed a substantial upgrade in order to be able to cope with the higher level of waste silts and clays that we would now be dealing with” explains Colm Scullion.
The Aquacycle A1500 at Draperstown Quarry represents the first global installation for the new thickener which was designed specifically for this application and highlights the partnership relationship that has existed between CDE and Creagh Concrete since the early 1990’s. “The Creagh Concrete and CDE relationship works because we both understand the need to keep innovating and coming up with new and improved processing systems to allow operators like us to extract maximum value from our reserves” says Gerard McKeague Joint Managing Director at Creagh Concrete. “This focus on efficient and sustainable management of our natural resources is central to our business.”
Unlike many other instances where the Aquacycle thickener has been specified the driver was not an issue with water supply but rather an example of how environmental considerations are at the centre of the decision making process for Creagh Concrete. “We’re not short of water or space for settling ponds at Draperstown quarry” says Gerard McKeague. “The focus on water treatment as an essential part of the washing plant is driven by our mission to minimise the environmental impact of all our operations.” Once the water treatment upgrade had been completed, stage two of the plant upgrade was initiated. This involved the introduction of the AggMax portable logwasher and an EvoWash sand washing plant. The AggMax incorporates a Grizzly screen, Rotomax RX150S logwasher and Evoscreen dewatering screen on a single chassis.
THE RESULTS
Following successful completion of the two stage plant upgrade Creagh Concrete can continue to produce a wide range of sand and aggregate products from Draperstown quarry for the foreseeable future. “From an initial point where we thought our days at Draperstown were limited we are now in a position where we have comfort that the reserve is fully exploitable” says Gerard McKeague.
Before the new plant was installed Creagh Concrete were faced with a reserve that had cost £1 per tonne of material processed based on the purchase price for the quarry in 1991. The introduction of the new plant has reduced this to £0.25 per tonne.
