When non-recyclable waste is processed to generate electricity one of the main by-products is called incinerator bottom ash (IBA).
IBA is the ash that falls from the base of the grate during the incineration process. However ‘ash’ is a slightly misleading term since it not only contains combusted products such as ash and slag but glass, brick, rubble, sand, grit, metal, stone, concrete, ceramics and fused clinker as well.
Once collected the incinerator bottom ash is loaded onto containers and transported to the jetty on dock tractors and trailers. It is then loaded on to our barges to be taken to an incinerator bottom ash processing facility at the Port of Tilbury in Essex.
On arrival at Tilbury the IBA is unloaded, stored and then processed. This involves using belt conveyors to move the IBA through a series of screens, over-belt magnets and eddy current machines to remove the metal and grade the remaining materials. The metals are separated and then sent on for further recycling.
The aggregate products produced from our ash at Tilbury range from classified fill and capping, in unbound / hydraulically bound mixtures through to aggregate used in bituminous road paving and low grade concrete.
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Every product has a range of rigorous tests that it must undergo to ensure that it is fit for purpose. These include tests for physical and chemical properties, for aggregate specification purposes and for environmental protection.
Our recycled sustainable aggregate has been used in some notable projects including the M25 widening scheme Junctions 29/30, the Bradwell-on-Sea Windfarm, Dubai Ports Thames Gateway development, the A13 Stamford-le-Hope by-pass and more recently the BWSC Tilbury Green Power Biomass project at the Port of Tilbury.
In recycling the IBA into sustainable aggregate, we are protecting our natural resources by reducing the need to quarry virgin aggregate from London’s surrounding countryside. We are also helping to bring down the carbon footprint of many construction firms by providing them with a valuable local alternative to the use of naturally mined aggregate.
The lightweight nature of the aggregate means that more product can be transported per vehicle movement saving the construction industry money, congestion and further reducing carbon footprint. The product is also exempt from the Government’s Aggregates Levy making it a cost effective alternative to quarried aggregate.