Press room Clean water recovery Slab of silt dropping from the press Overall view
 

Haith sorts out the silt for Raymond Brown Recycling

11th November 2007

Haith Industrial has just completed the supply of a silt management system at Rookery Farm Landfill. Site of a new Aggregate Recycling plant for Raymond Brown Recycling, Haith supported Blue Machinery who installed the plant.

Raymond Brown Minerals & Recycling is part of the Raymond Brown Group which has been operating as an independent family business for over 50 years. The new washing plant at Rookery Farm has been installed to meet the increasing demand for secondary aggregates while reducing pressure on landfill. The plant has a water recovery system to reduce overall water demand and the silt resulting from the washing process is pressed into a manageable ‘cake'.

Landfill at Rookery Farm commenced in the 1980's after the construction of the M27. Recycling first started on the site in 1995 with crushing and screening of concrete. Then, in 2002, a pilot washing plant was installed to develop the production of clean construction aggregates. This plant had a very limited silt recovery system and required a lot of water, something that has now been addressed by the new plant.

Development of the Rookery Farm site was influenced by a number of factors including, in 2002, the ‘Making Waste Work' EU initiative to promote sustainable waste management. In 2003 Raymond Brown took an active part in Hampshire County Council's ‘More from Less' campaign, which looked at how waste could be used as an asset.

To treat wash water and silt produced from the aggregate recycling and washing system at Rookery Farm Haith Industrial designed a new system that, unlike lagoons, incorporates a series of high efficiency modular components. Each element of the system design is based specifically on the plant input and customer specification rather than standard sized modules in an effort to maximise the operating efficiencies. Both the Thickener and Filter Press can tolerate variances in the fluent as well as making operation easy. The Thickener has been sized to modest surface loading rates and volumes, which will collectively keep the flocculent demands to a minimum and accept the required silt yields.

Common to all of its treatment systems Haith included a silt or slurry buffer tank which is designed to receive and store the silt from the thickener at a rate dictated by the washing process. Standing between the Thickener and the Filter Press it buffers the silt volumes generated during the latter part of the pressing cycle when the feed to the press is dramatically reduced. Whilst these small variances can be accommodated in the Thickener larger silt volumes cannot, without the likelihood of a blockage. The inclusion of a buffer tank increases the systems flexibility and robustness.

Haith considers that Raymond Brown will find numerous benefits from the system including thickener rakes driven by a hydraulic system that suspends the rakes and obviates the need for submerged bearings and bushes. Furthermore, a fully automatic Overhead Beam Filter Press incorporates an automatic cloth washer system, which obviates the need for period manual washing. The system also provides effective cloth washing to increase cloth life; prevent the build up of cake on plate edges, which can cause plate damage and failure, and to maintain cycle times.

Steve Cole - Environmental & Development Director, commented," We were very impressed at the professional approach taken by Haith to the project. Site control and management was excellent during construction and following an initial commissioning period the plant is now functioning fully and producing a manageable silt cake."