Reuse and air classification of bioash

The amount of biomass ash (BA) produced worldwide is expected to increase in the near future because biomass is commonly regarded as a carbon neutral fuel. Therefore, sustainable methods for the utilization of BA will be needed to manage the increased flux of BA from the energy sector while concurrently dealing with a smaller allowance of BA that can be landfilled. Therefore, research into new technologies is needed to find and exploit methods to utilize BA in safe and economically and environmentally sustainable ways in order to maximize the environmental benefits of biomass combustion. Presently BAs are utilized primarily in the construction of landfills or disposed of in landfills, with a minor percentage recycled for various purposes. Viable alternatives to landfill construction and landfill disposal require supportive evidence for their practicality, which is currently limited. One of the main barriers to reuse is the presence of heavy metals in BA. Therefore, finding effective methods for isolating and removing heavy metals is important to allowing reuse and is pursued in this work. Furthermore, this thesis seeks to assess the quality of specific BA samples as the quality pertains to their final usage, and to assess the sustainability of the usage solution to the comparable product that BA is replacing. Technologies were evaluated for their suitability and feasibility for utilizing BA as a replacement for traditional natural resources in specific applications. This thesis will seek to clarify the usage of air classification for refining BA for reuse as a product with the goal of contributing to the knowledge of viable and sustainable solutions for the reuse of BA. Background information on the quantities, quality, formation, analytical methods, utilization options, treatment methods and law and regulation related to BA were investigated prior to the experimental design. Based on that research and the interests of Ekokem, evaluation of three BA samples for reuse in agriculture, earth construction, cement and landfill disposal was completed. Additionally, air classification tests were performed on the BA samples with the objective of isolating certain components of the BA in a separate fraction; those samples were also evaluated for the same reuse schemes. The experiments produced three types of results. First was the procedure development in how to carry out air classification experiments and results directly related to air classification that can guide future research. Second were the results for individual samples and their reuse potential; one sample showed reuse possibilities without refining; the two other samples showed some improvements through air classification with isolation of heavy metals in the fine air classified fraction. Lastly, challenges experienced and additional work related to the reuse of BA and air classification experiments were outlined