Because the incineration of Municipal Solid Waste (MSW) reduces the volume of the MSW by 80% and its weight by 90%, it constitutes an increasingly frequent alternative to landfills.
The bottom ash is the incombustible part of the incinerated waste. In 2018, around 96 million tonnes of waste were treated in Waste-to-Energy plants in Europe, which led to the production of approximately 19 million tonnes of bottom ash. Important quantities of metals and minerals are present in these residues and offer many opportunities for recycling.
Treatment of bottom ash
The ash produced by incinerators is typically fly ash and bottom ash (Incinerator Bottom Bash, IBA) that are either conveyed together at the exit of the incinerator (like in the USA) or kept separate.
The ash typically contains between 1 and 3% of valuable non-ferrous metals (including precious) and 5 to 12% of Ferrous.
Ash coming from MSW incineration is characterized by having up to 50% of its mass smaller than 6 mm, depending on moisture content, which calls for specific technologies and experience.
SGM provides a complete range of technological solutions for both recovering and cleaning the metals in the ash.
Thanks to numerous references, SGM disposes of a longstanding extensive experience of the different technological solutions for processing MSW ash comprising:
- ballistic separator for screening and concentrating the solid pieces, including the metals, in a stream where moisture is also significantly reduced,
- special high frequency eddy current separators suitable for the recovery of metals down to 0.2mm,
- sensor based separators and
- air gravity tables for the separation of the light fraction from the heavy metals.
Decades of experience and the expertise acquired in the group companies BSB Ambiente and Iris Ambiente (production 90,000t/year each) allowed SGM to offer several technological solutions for ash treatment.