| dc.description.abstract | In recent years, climate change has led to an increase in environmental issues. In an effort to reduce carbon emissions, many countries have implemented policies to promote environmental protection and aim for net-zero emissions. Industries that rely heavily on energy, such as the domestic paper industry, have begun to adopt carbon neutrality and energy transformation strategies to meet the goal of net zero carbon emissions by 2050.Among them, the waste-derived fuel in pulp and paper industry is primarily made up of light residue (waste paper slag) However, the solid recovered fuel (SRF) which was made from waste paper slag, often contains aluminum foil fragments, which can lead to metallic aluminum remain in co-combustion fly ash (CCFA), and can cause expansion on cement product when the CCFA is implemented reuse assignment.
This study aims to analyze the material properties of CCFA produced through domestic pulp and paper industry boilers (CFB boilers), which combustion SRF and coal. To explore the expansion potential of CCFA when it applied to cement materials, a method for measuring the content of reactive metal aluminum in CCFA was established based on the reaction of metal aluminum and water to produce hydrogen. Additionally, the effect of different heat treatment temperatures on the surface oxide layer of metallic aluminum powder and the reaction in different alkaline environments were tested. Discuss and evaluate the effect of pretreatment stabilization methods to enhances the reuse value of CCFA.
The results of this study indicate that SRF made from waste paper slag and pulper residue, as well as fly ash produced by co-firing SRF with coal (SRF(PR)-CCFA and SRF(TP)-CCFA), contain residual reactive aluminum components. This is mainly due to the fact that aluminum foil, which is a metallic aluminum material that remains in SRF fuel and cannot be fully oxidized during the CFB boiler combustion process. To reduce the reactivity of aluminum content in CCFA, three pretreatment methods were proposed based on the characteristics and reactions of the CCFA material: high-temperature calcination treatment, water immersion treatment, and cement curing treatment. The results showed that all three pretreatment methods effectively reduced the content of reactive aluminum in CCFA, thereby reducing the issue of volume expansion caused by the use of fly ash in cementitious materials. The research results contribute to understand the material properties of aluminum-containing CCFA and the mechanism of volume expansion that occurs while using in cementitious materials, and provide a more comprehensive understanding of the characteristics of CCFA derived from various waste fuels in the pulp and paper industry. In addition, various pretreatment and stabilization methods can be proposed for the complex and varied co-fired fly ash material, providing more diverse application pathways.
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