High Volume Mixing Plant

• 
• 17th May 2009
• Materials Handling
 

Liebherr has designed, built and installed a high volume concrete mixing and batching plant for long-standing customer London Concrete Limited - part of the Aggregate Industries Group. A new Betomix 4.5 plant is now hard at work at London Concrete's brand new readymix facilities in Uxbridge, Middlesex. The plant came on stream in January 2009.

London Concrete Limited has been associated with Liebherr for many years and owns a large fleet of 8m³ HTM 804 truckmixers operating from its many depots in the home counties and all sourced from Liebherr-Great Britain. This is the company's first Liebherr batching plant and has been installed in a brand new depot on the Denham Road just outside Uxbridge. Featuring a twin shaft paddle mixer, six large volume automated aggregate and sand bins, eight admixtures and three large cement silos, the Betomix 4.5 plant is capable of producing high quality concrete up to 120 m³ per hour.

Sited within the Summerleaze Aggregates sand and gravel quarry, the Betomix 4.5 is more than capable of loading a continuous stream of truckmixers and, perhaps most beneficially, receives its sand and gravel requirements direct from Summerleaze by loading shovel from the nearby stockpiles, straight into the plant's feed hopper and then by conveyor to the aggregate bins. This highly beneficial arrangement between the two companies means that not only is there a convenient supply of high quality sand and gravel to the busy plant but there are no transport costs involved nor, of course, are there any fuel consumption, traffic problems or related emission issues with which to contend.

The Betomix 4.5 is one of the larger mixing plants in the Liebherr range and is comprised of modular elements, which allow a flexibility of design and construction to suit virtually any site. The great advantage of the London Concrete installation is that the site is brand new and, therefore, the configuration, materials flow and discharge area could be optimally designed. Vehicle access is excellent and there is plenty of space around the plant for truckmixers, delivery vehicles and plant/site maintenance, which would explain the tidiness and efficiency of the operation!

The Mixing Section

The three cement silos have approximately 90 tonnes (75m³) capacity each and are equipped with three reverse air type exhaust filters for dust emission control. Three 13m long cement screw conveyors feed the cement weigh hopper - each screw is capable of providing the required cement to the mix. Incoming aggregates are fed to the holding hopper by a 1200mm wide X 27m long feed conveyor which is inclined at 24º. Electro-mechanical systems weigh the cement and water. Significantly, the dual water supply for the plant comes from either a recycled water system or, for fresh water, the site has its own borehole and pump - once again, an indication of environmental best practice.

The heart of the plant is the Liebherr DW 4.5 twin-shaft paddle mixer, which features twin 75kW electric motor drive, discharge door and loading hopper/chute; a high pressure washdown system is included. The DW 4.5 has a single batch volume of 4.5m³ compacted concrete and the entire mixing section is fully enclosed for weather protection with the cladding including translucent panelling and lighting.

The control centre for the plant is housed in a 7m X 4m cabin including a Command Alkon plant control system, providing the required interface with the Liebherr starter panel. Also included within the cabin is an array of video monitors linked to strategically situated CCTV cameras around the site and inside the plant. This surveillance system provides the control team with continual images from inside the aggregate hoppers for safety and to ensure correct material discharge, the paddle mixer to monitor mix consistency and the surrounding areas to check on vehicle movement.

Aggregate/Sand Feed and Storage

Aggregates and sand are introduced to the plant via a ground-level hopper, complete with vibrator and designed for loading shovel dumping. From here, the sand and aggregates are conveyed to the storage bins by a fully enclosed 1000mm wide X 25m long chevron belted inclined conveyor. This, in turn, discharges onto an 800mm wide X 10m long tripper conveyor which automatically dumps the correct sand or aggregate into the required storage hopper via an innovative and efficient double-rolling movement, which is powered by a direct-geared electric motors.

Six in-line hopper compartments - each with a capacity of 50m³ (80 tonnes) ─ store two different sands and four aggregates. Levels are monitored by sonic-type indicators and the sand hoppers are equipped with moisture metres and vibrators. The enclosed conveyor for feeding the plant's materials holding hopper is 1000mm wide X 25m centres and includes a 12,000kg maximum load electro-mechanical belt weigher.

Liebherr-Great Britain incorporated a wall and roof structure specially designed and built to fully enclose the sand and aggregates hopper and trip conveyor installation, providing total weather protection and significantly contributing to even greater control of dust and noise emissions.

Further information:                           

Liebherr-Great Britain Limited
Tel: 01767-602100

Associated Links

• Hub-4 Profile of Liebherr Great Britain Ltd (Head Office)
• Liebherr Great Britain Ltd (Head Office) Company Website