Construction and operation of a plant to process the bottom ash from municipal solid waste incineration to maximize the recovery of strategic metals while optimizing the recyclability of the mineral fractions generated

© H-U-R

Around five million tonnes of bottom ash are produced every year in Germany from incinerating municipal solid waste that contain around ten percent metal. So far, it is only possible to recover this metal from the proportion of ash that has a grain size of more than three millimeters. The smaller-grained fine ash is often removed in advance by sieving and then dumped which means that the valuable materials it contains are lost.

The “STRATEGO” project partners are developing and constructing an industrial plant able to process even the smallest particles. The quality of the recovered metals should be same as the respective primary metals. Another focus of the project is on recovering the minerals that make up more than three quarters of municipal solid waste ash.

In the preceding project, a technology was already developed and tested on a pilot scale. This was able to double the volume of non-ferrous metals recovered from municipal solid waste bottom ash. Germany-wide, this means it would be possible to recover 27,000 tonnes of non-ferrous metals each year from 5.4 million tonnes of municipal solid waste bottom ash. In this follow-up project, the partners from industry and science are now further developing the technology for use on an industrial scale. In “STRATEGO”, two companies, H-U-R Hamburg GmbH Hamburger-Umwelt-Recyclingtechnologien (as project coordinator) and C.C. Umwelt AG from Krefeld, are working together with the Institute of Environmental Technology and Energy Economics – Waste Resources Management at the Hamburg University of Technology.

The heart of the innovation is the high-speed impact crushing of ash particles at a speed of up to 1,280 kilometers per hour. The impact blasts the metals free and makes them accessible for recycling. As well as optimizing this technology, “STRATEGO” wants to make the framework conditions for the plant more efficient, including operating the plant entirely with renewable energy and creating closed loops within ash processing.