Unlocking the potential of fly ash as a secondary raw material through the use of LSRI

Purpose and goal

The goal was to increase the potential reuse of resources from waste incineration fly ashes through increased knowledge of the chemical speciations of Zn and Sb in fly ashes before and after treatment of the ashes. The techniques XANES, nXANES and nXRF were used to reveal details of the complex chemical composition of 6 different ashes. The most common speciations were identified of Zn and Sb. This knowledge may help the industry partners to improve processes, provide guidance how the mineral residue can be valorized and if the ash may be classified as non-hazadous waste.

Expected results and effects

The most common Zn and Sb speciations in fly ash samples were identified. In zinc condensates the Zn was mostly in the form of alcaline salts and the content in larger and smaller particles were different. Through leaching tests information about the content before and after treatment was gathered. The knowledge will lead to optimized handling and valorization of ash. 17 Zn and 15 Sb containing compounds were added to the open library at Balder, MAX IV, for improved future analyses. One scientific article was written as part of the project and ideas for another three articles identified.

Planned approach and implementation

Samples of six different samples of untreated/treated fly ash have been tested with the techniques XANES, nXANES and nXRF at Balder, MAX IV in Lund and I14, Diamond, UK. The focus for the analyses has been to identify the speciations of zinc and antimony. For the analyses, known reference materials are necessary to compare with and through the project 17 zinc and 15 antimony substances were added to the reference library at Balder. The treatment of the samples was made with a series of leaching steps. The project members have regularly had seminars to discuss interpretations of the results.