Page 68 - Hub-4 Magazine Issue 76
P. 68

The Tyrone International plant:
Commissioned in June 2022, 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 the customers’ existing scalper which scalps off the +50mm with the -50mm being fed up the primary feed conveyor. The plant has been future proofed with the electrical control system and wiring installed to add a fully electric drive scalper next year.
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 and sizing screen which removes any sand that has been carried through.
“This gives the stone a final rinse before and utilising a double deck screen to size the material into clean 10/20/40mm aggregate.
Any fine sand from the pre-screen, trash screen and sizing screen 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 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 deep, 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.”
A positive displacement pump extracts the sludge out of the centre of the thickener which is then pumped across to a large sludge holding tank where a stirrer keeps the silt in suspension. From here a twin centrifugal pump fills the press and creates the pressure required to force the water out of the sludge through the filter cloths attached to each filter plates.
When the water has filtered out of the cakes in the press the feed pump stops, and the press opens automatically and rapidly discharges ten cakes at a time.
The Fraccaroli & Balzan (F&B) over beam filter press:
The Fraccaroli & Balzan overhead beam filter press at MJ Teale offers so much more than other presses in the marketplace.
Fintan gave us the facts. “The Fraccaroli & Balzan overhead beam filter press at MJ Teale has 100 - 2 x 2 metre square plates. The capacity can be easily increased in the future by simply adding 30 more filter plates into the existing press frame which gives our customer an inexpensive way to future proof their business and meet increased demand as their business continues to grow.”
   | p68 | Sept/October 22 - Issue 76

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