Page 43 - Hub 4 Magazine issue 53
P. 43

Bespoke structure which holds the huge Matec filter press
We produce a dirty crusher run daily which has also been building in large quantities since the quarry started. This is where Dernaseer got involved to come up with a wash plant solution for us to take the dirty fraction of our primary material and wash it to give us further aggregate that we can put into our concrete products. This washing plant is going to allow us to now recycle that previously waste product which is a huge opportunity for us and we are very happy with the plant, its working very well, and we have a great partnership with Dernaseer.”
Martin explained a little more about the plant “With a feed material of crushed dirty limestone, this bespoke wash plant consists of a 40m3 variable speed belt feed hopper fitted with a remote-control tipping grid which is fed by a Volvo dump truck. The 0-120mm material which passes through the grid is then delivered onto the main inclined conveyor which feeds all the material into a 7m x 2.5m rubber-lined scrubber barrel. The scrubber barrel is the most effective solution for the difficult feed material in this quarry as it accepts an all-in feed removing the need to separate fines first and it can handle much larger particles than a log washer.
“The scrubbed material is discharged onto a 6m x 1.83m three deck washing screen which utilises eight individually controlled spray bars on each deck. The screen is fitted with polyurethane screen media on all decks. The top deck scalps off any material above 15mm which is fed by conveyor to a Hazemag horizontal impact crusher. The crushed material is returned to the washing screen by conveyor. A split bottom deck, 3mm and 5mm, with rubber-lined catch-box, provides the feed to the cyclone sand plants to produce the required two sands. The +5-15mm is fed by conveyor to a 5m x 1.8 screen to separate the three required aggregate sizes. All chute-work on the plant employs a dead-box system which results in a rock on rock set-up providing excellent wear properties.
“The water treatment system at Crievehill receives dirty water, from the washing plant and has two purposes. Firstly, the water is clarified and recycled the water and secondly the
Dernaseer’s new 38,000sq ft (3,500m2) production facility
Dernaseer fabrication facility
Matec filter press
sludge is concentrated in preparation for further pressing. The dirty water coming from the cyclone overflows are mixed with a polymer flocculent solution and fed into the thickener tank. The sludge settles quickly at the bottom of the thickener where it is concentrated and gathered into the pumping cone due to the slow movement of a scraper inside the tank. The concentrated sludge is then pumped into a mud buffer tank which homogenises the sludge before being pumped to a Matec 2000 x 1500 x 140 filter press where it is pressed to produce a dry cake. The water from the pressed sludge is recycled to the washing plant. The clean overflow water from the thickener tank is discharged into the clarified water storage tank, where the water pump delivers it back to the washing plant. The finished products are 3mm sand, 5mm sand, 6-9mm, 10-12mm, 13-15mm with all +15mm going back to the crusher and returned to the washing screen for re- processing.”
For more information on wash plants and other products from Dernaseer please visit or call Martin Conway on +44 (0) 28 8776 7646 Nov 2018 - Issue 53
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