New home for batching plant

When land housing a Lintec containerised batching plant was needed for other purposes, one of Dubai’s largest producers of readymix concrete, Unimix, was able to take advantage of its mobile installation and move works to the nearby Jumeirah Beach Residence site with minimum disruption.

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By  Colin Foreman Published  April 16, 2005

New home for batching plant|~||~||~|Unimix, with its contract to provide a range of concrete grades for the Jumeirah Beach Residence (JBR) project, recently had to transfer its Lintec batching plant when the land was needed for other purposes. Although only recently introduced into the UAE by Lintec through its Middle East distributor Technobuild Construction Machinery, its containerised concept — offering speed of erection and dismantling, ease of installation and the ability to produce quality end products — proved ideal for Unimix. The original location alongside the Jumeirah Sheraton hotel was required for construction purposes. An alternative site was located within the JBR compound just several hundred metres away. Timing was critical as contractors had completed much of the foundations for the project’s 20-storey towers and a constant supply of concrete was needed for above ground pours. With Unimix able to temporarily meet demand from a second batching plant, it needed the Lintec system to be ‘up and running’ as quickly as possible. Although the second plant was close by, it meant using the busy Sheikh Zayed Highway, which together with Dubai’s heavy traffic congestion and restrictive use on its main highways for trucks, posed transportation difficulties. The individual plant units are installed within 100% ISO sea containers to provide a compact transportable system. Containerisation offers many advantages; even though the plant was not moved a great distance, it did not require the need for low loaders since the containers are neither over-width nor over-weight. Once moved, its large base meant that the container can sit on a normal compacted site surface without the need for concrete foundations. The re-assembled plant was ready for ‘fine tuning’ once the pre-installed pipes and cables had been connected and production was started within a week of moving. Operating 24 hours round-the-clock, the Unimix depot’s two batching plants produced almost 200 m³ of mix per hour for the foundations contract, supplying over 500 000 m³ in just 18 months. Now installed in its new ‘base’, the Lintec plant is running 24 hours a day to provide an anticipated 750 000 m³ for its 20 towers concrete placement contract. The plant is served by Unimix’s fleet of up to 30 mixer trucks, which have a capacity of 9-12 m3. At the input of the system, two 12 m containers, each split into three compartments, provide aggregate storage bins with a storage area of 200 m3. Two moisture centres within the bins ensure that the water content within the aggregate is automatically controlled. Unimix generally works with a mix of five different-sized aggregates up to a maximum size of 20 mm. Unique to the Lintec system offering is a pre-weighing system below the storage components, allowing Unimix to weigh the content of each respective compartment at any time; compared with a conventional weigh belt system which only allows measurement to be made in one compartment at a time. This can often result in a stop-start operation. With the Lintec system, a continuous belt operation eliminates stop-start to provide very fast loading cycles. The belt feeds onto a 24 m incline conveyor housed within two halves of a 12 m container. Upon installation, the container is hinged open to form two units which are bolted together at an incline angle of 29º. The Jumeirah installation features a twin tower configuration with each tower comprising a mixer unit and weighing unit, this time installed within 8 m ISO containers. The height of the mixing compartments is determined so as to allow easy drive-in access and loading of the cement trucks beneath the mixer. Two 8 m containers, once again split in half and housing instrumentation, support the raised twin towers. Ten 80 m3 silos ensure an 800 m3 storage capacity with five serving each twin tower. Since Unimix prefers to blend the mix itself, each twin tower can be served with, for example, cement, fly ash and ggbs slag.Each silo comprises an 8 m container at the base and a 12 m unit at the top, to provide an 18 m overall height. The installation also features a 25 m3 micro silica silo located on top of the weighing container, providing automatic injection as required. All of the silos are equipped with piping to allow easy dust-free filling by a pneumatic conveying system. A distribution belt at the top of the incline conveyor transports material to each of the towers as required, into the weighing containers. At the same time, the specified cement-mix, with any micro silica is also weighed. Once the correct weight has been achieved, the materials are then fed to the mixing container housing a patented Lintec twin shaft mixer. With two 55 hp motors, the belt-driven mixer also features fluid coupling to help protect the motors. In order to ensure smooth operation throughout the high summer daytime temperatures experienced in the Gulf region (which can often reach in excess of 40ºC), Unimix has opted to use an ice flake system to help cool the final mixed product. Supplied by KTI Plersch Kältetecnik, the ice weigher is installed at the foot of the incline conveyor for automatic mixing with the aggregate. Once this current project is completed, Unimix will be able to simply dismantle the complete Lintec installation and move it to its next location in just a matter of days. According to Technobuild Construction Machinery, the application has attracted considerable interest from Iranian visitors recognising the efficiency of the Lintec plant.||**||

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