Advanced spectroscopic techniques take industry one step towards circular economy
X-ray absorption spectroscopy (XAS) has the potential to provide unique information about the chemical forms of trace metals – information often needed to find safe and efficient use of industrial side streams and move the industry one step towards circular economy. The techniques allow us to investigate and optimise processes for recovering valuable resources from ashes as well as finding environmentally safe ways to use the mineral residue replacing virgin material, says Jenny Rissler at RISE.
As a step towards circular economy, processes for recovering valuable resources from industrial side streams is under development. As is the development of new and safe ways to find secondary use of such materials. As an example, chemical forms of trace metals are essential to know to best utilise the material in a safe and resource efficient way.
The purpose of the project on ash is to investigate the chemical speciation of Zn and Sb in fly ash and study the change in the speciation induced by various treatments.
– The chemical forms of certain trace metals – before and after processing of the ash – are crucial both for improving the processes to achieve a higher yield in extraction, but also for enabling the utilisation of the mineral residue, says Jenny Rissler.
Synchrotron-based XAS is a method of choice for identifying the chemical forms of the valuable or toxic trace metals in the complex ash matrices and, in lack of alternative methods, has the potential of becoming a standard industrial tool. However, to reach its full potential, further investigations are still urged.
Two synchrotron-based techniques will be applied: XAS and chemical mapping by nXRF and nXANES. The goal of the project will be to generate more information about the speciation so that the industrial partners in the longer run can improve their processes, unlocking the full potential in ash from Waste to Energy (WtE) as a secondary raw material. Another goal is to extend the open database of reference spectra of Zn and Sb at MAX IV, as an important step towards XANES to become a standard tool.
The work is done in a collaboration between RISE, Chalmers University, Fortum Waste solutions, Renova and NOAH.