Page 59 - Hub-4 Magazine Issue 66

Recycling
The owner of RMS, commented, “Tyrone took us to a previous installation which we were overly impressed with and on the basis of the build quality and their knowledge we subsequently gave them the contract to supply and install a turnkey solution.
“The whole investment is down to the realisation of the opportunities and a way of dealing with a problem by reducing landfill.
“Additionally, the installation of the water treatment plant and the press is phenomenal. The whole operation would not work efficiently without it; it works effortlessly ensuring the whole system is in harmony. Absolutely first-class service from Tyrone International , a truly knowledgeable team and the back-up is superb.”
He, added, “We were very impressed right from the start and all the way through the build and now the plant is running we are even more impressed!”
A varied plant feed:
The new recycled aggregate washing plant is processing a combination feed of recycled materials containing anything from ‘muckaway’, to utility waste, trommel fines and the quantity of sand and the ratio of the sand/silt fraction completely varies in every bucket load going into the plant. However, the plant has been designed to accept a remarkably diverse feed whilst still retaining throughput.
Specified to process 120tph the plant is currently achieving an average of 140tph.
Material passes under a belt magnet and is then fed onto a pre-screen to remove the -5mm sand. The remaining 5-50mm is then fed forward into a twin shaft log washer; a completely new design by Tyrone this incorporates a lot of new design features, including extreme ease of access for maintenance of all parts.
This improved access philosophy is seen throughout the plant and also on the trash and dewatering screen.
Fintan McKeever – Director of Tyrone International, took us through the process, “After passing through the log washer, material is then fed onto a rinsing screen which removes any sand that has been carried through the log washer.
“This gives the stone a final rinse before being fed through a further two transfer conveyors and under a second belt magnet and then onto a 12 x 5 double-deck sizing screen where clean 10/20/40mm aggregate is produced.
Any fine sand collected from the pre-screen, trash screen, dewatering screen and the log washer is collected in a large sump tank which is situated under the log washer. It is then pumped to a Linatex cyclone which removes the majority of the silt; the underflow of this passes down to one side of a high-frequency dewatering screen which is fitted with spray bars. This washes the fine sand with any remaining silt passing through the deck and into a pump tank situated under the dewatering screen.
From here the fine sand is pumped up through a secondary Linatex cyclone which removes the remainder of the silt with the underflow passing on to the other side of the sand dewatering screen. Coming off the end of the dewatering screen there is the facility to blend as much, or as little of the fine sand back into the coarse sand to make any particular grading.“
All the trash material, polystyrene, plastics and small pieces of organics, wood exit the top of this cyclone with the silt and then flow by gravity down to a large high-frequency dewatering screen fitted with stainless steel wedge wire. This removes all the +1mm trash material, (keeping it out of the water treatment system); which is then deposited into a large skip.
The silt fraction and the water flow into the centre weir of the thickener tank where flocculent is added. Here the silt particles bind together and settle at the bottom of the thickener where a large rake is situated. Rotating slowly this rake incorporates large ploughs which pull the silt particles towards the centre. Because the ploughs are large a very thick high-density sludge is achieved.
Fintan, added, “The rake can be raised and lowered to eliminate any issues with blockages and allows full control of the density of the silt. If the silt gets too thick the rake can plough back down through it allowing ultimate control of the density.”
The Tyrone International plant:
Commissioned in December 2020, the recycled aggregate washing plant with a full water treatment system and filter press was designed by Tyrone International to fulfil the processing criteria for the material feed.
The material is based on an all-in aggregate feed, using a Tyrone International twin-screen scalper which scalps off the +50mm with the -50mm being fed up the primary feed conveyor.
www.hub-4.com Jan/Feb 2021 - Issue 66
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