CDE Contract Washing Plant for JA Woods
New sand and gravel washing plant installed in Co. Cork
CDE, the Co. Tyrone-based specialist designers and manufacturers of tailor-made equipment for the aggregates industry, have recently added to their ‘contract’ portfolio with the installation of a 150 tonnes/h sand and gravel washing plant for John A Woods Ltd.
John A Woods are major suppliers of stone, ready-mixed concrete, concrete products and bituminous materials to the building and construction industries in the south of Ireland. They are also one of the oldest quarry firms in the region; although incorporated in 1951, the company dates back to 1914 and was the first to set up a gravel washing plant in Ireland. Its founder, John A Woods, was also a founding member of Roadstone. Today the company operates in 15 locations throughout Ireland, with the new CDE contract plant being located in Watergrasshill, Co. Cork.
The washing plant processes 150 tonnes/h of ‘as dug’ material to produce a washed oversize, 20mm, 10mm and concrete sand. An AquaCycle thickener is used to recycle up to 80% of the water used during the washing process, significantly reducing the site’s fresh water requirements. The washed sand and aggregates are used for concrete production, while the waste sludge (approximately 600g/litre concentration) is pumped to a silt pond.
A CDE-operated front-end shovel loads directly into a 20-tonne reception hopper. This feeds a conveyor which carries the raw material to a triple-deck 1.5m x 5.0m ProGrade rinsing screen and discharges on to it via a rubber-lined washing box, which adds water to the material to create a slurry.
Equipped as standard with abrasion-resistant rubber lining on all surfaces that come into direct contact with the raw material, the ProGrade unit is fitted with rubber mats on the top two decks and polyurethane media on the bottom deck, which is standard practice throughout the ProGrade range. The feed material is washed and sized with the oversize, 20mm and 10mm products being sent down rubber-lined chutes to stockpile via mobile conveyors.
The sand is fed, under gravity, directly into the sump of a C-62 EvoWash compact sand washing plant, which CDE custom build according to each specific application. From here the material is pumped, via a Warman pump, to a cyclone which accurately separates the material at the customer’s required cut point (75µm in this particular case) with no unwanted fines loss.
From the cyclone the washed sand is sent to a high-frequency dewatering screen where it is dried to approximately 12% moisture content. The screen is fitted with wear-resistant polyurethane panels and features marshmallow springs for maximum efficiency. From here the dewatered sand is sent to stockpile via another mobile conveyor.
Meanwhile, the –75µm material separated by the cyclone is sent, under gravity, directly to the AquaCycle thickener. As the slurry enters the thickener tank, the material is mixed with a polyelectrolyte, prepared in an adjacent fully automatic dosing station, causing a thick sludge to rapidly settle to the bottom of the tank. Meanwhile, the clean water overflow from the thickener tank is sent to a storage tank from where it is pumped back to the ProGrade rinsing screen.
CDE maintain the plant on behalf of John A Woods under the terms of a ServiceMax after-sales package, with a CDE engineer visiting the site on a regular basis to carry out preventative maintenance on all the equipment. As mentioned earlier, CDE are also responsible for the loading shovel and its operator, and are paid on an agreed price per tonne of washed product produced.
The contract, which has proved to be an extremely successful partnership arrangement for John A Woods, is one of a number of such CDE contracts currently in operation throughout the UK and Ireland.
