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      New Milton sand ballast increase efficiency with a new Duo triple solution plant

      Located on Caird Avenue, New Milton, Dorset the 40-acre site is operated by New Milton Sand & Ballast (NMS). Owned by the Drew family since the thirties, extraction on the site has long expired and currently the company process all their materials here which are imported from two of their other sites. Imported materials being primary gravel from their Downton site and various British Standard Recycled materials from their Pennington site.

      Operating an aged wash plant was not efficient and NMS made the decision to invest in a new plant that would improve the processing efficiency and provide more saleable end product which included clean material for their concrete plant.

      Paul Drayton – Operations Director for NMS took up the story, “We sat down with several companies to discuss our requirement and ultimately chose Duo as they offered us a comprehensive solution with the inclusion of two AMP twin TAK Hydro Classifiers. In discussion this provided us with the confidence and reassurance to produce sands that were going to be contaminant free because ultimately, we needed to use the recycled material for our concrete plants.

      A successful tender:

      With the project awarded to industry leading specialist – Duo Equipment (part of Duo Group Holdings Ltd) supplied a unique ‘triple solution’ processing plant.

      Sand Processing:

      Capable of 150tph the plant is currently operating at 150tph for primary gravel and 80-100 tph for recycled materials; primary gravel is fed by wheeled loader into the heavy-duty remote-control tipping grid.

      When the plant feed is switched recycled material is fed into a mobile Warrior 1400X which screens off to stockpile any -70 – +40 before feeding into the grid. This machine is tracked out of position when the plant is fed with primary gravel.

      Material is then fed up an inclined feed conveyor under a magnet onto the top deck of the 3.7 x 1.5m Double-Deck Rinsing Screen. Fixed at an 18º working angle the top deck acts as a relieving screen to keep the pressure off the bottom deck. Here a 6mm aggregate is sent to stockpile with oversize fed onto a side conveyor to stockpile.

      Material is then fed into the log washer where the blades convey the material from the feed end of the scrub to a 3.7 x 1.5m double-deck part rinsing screen. Any organics such as roots or plastics are floated off to be dewatered over the Aggrescrub™ 6×2 trash screen. Underflow from the trash screen is received in a catch box under the screen and then gravity fed to the sump tank under the hull.

      The main product, sand falls through the bottom deck which is then pumped from the rinsing screen up to the twin 500mm hydro cyclones of the AMP sand plant. Consisting of a high-energy 3.2m x 1.5m split dewatering screen and two 150/100 pumps each separately for sharp and soft sand the specification is completed with one TAK 161 as the upward current classifier for soft sand and a second TAK 161 as the upward current classified for sharp sand.

      John, continued, “The TAK’s are an essential part of the process, with regards to contaminant removal. The plant is also capable of dealing with a percentage of Trommel Fines when required.

      All ongoing aggregate is fed via conveyor to a 16 x 5 triple-deck screen which then separates and feeds four separate stockpiles of 10mm/14mm/20mm/40mm clean aggregate.

      Organics Plant

      Situated above the organic’s removal plant the twin hydro cyclones remove the ultra-fine particles, taking them from the top and feeding a concentration of sand into the twin TAK hydro classifiers. When the sand settles in the TAK a clean water upstream current is introduced from the bottom and then by moving the set point, up or down you can then control precisely what the grading is at the bottom end of the sand and how much you float off.

      Cutting Edge Control System:

      The control system for this specific wash plant is stored in a centralised cabin on the site, which is one of the options offered by Duo, alternatively the panel can be mounted onto the machine, all of which are pre-wired.

      This option exemplifies the flexibility of Duo and the concept to suit individual customer needs or preferences.

      Other equipment – freshwater tank, flocculent unit, filtrate water tank, sludge pump and two belt press were supplied by NMS.

       

      A unique plant:

      The Plant has been designed to process as raised Sand & Gravel, General C & D recycled materials, which are dealt with on a rota system.

      Paul explained, “We generally change over every month which takes a whole day as the plant has to be thoroughly cleaned with attention specifically to the screens and the log washer to remove debris which would contaminate any primary material. We only need to do this when we change from recycled to primary feed as the change from primary to recycled has no effect.

      “It does take effort, but we have a rather cost-effective unique plant which can provide all the clean materials we desire.”

      John Collins – Technical Director, Duo Equipment, commented, “With NMS requiring to process alternate sharply contrasting feeds we based the design around the highly successful Aggrescrub™ 150 log washer and as there were quantities of organic contaminants in the feed, AMP twin TAK Hydro Classifiers were included to remove them from the fines fraction and provide a guaranteed clean, contaminant free material for the NMS Concrete Plants.”

      A financially sound investment:

      Paul commented, “I was very pleased with the commitment of the DUO engineers who were superb. The installation, Health and Safety procedures were all conducted at very high levels, I couldn’t fault them!

      “Since commissioning in June this year, the plant has been working five days a week doing a great job; bearing in mind it is multi-tasking washing the primary and recycled feed. Financially it has made sense for us to have one plant capable of handling both feeds as most companies who go down this route would operate two plants, so it’s fairly unique.”