Gypsum distribution in mixed C&D waste sorting process and its state of existence in residue

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Abstract

If source separation is not sufficiently conducted, construction and demolition waste becomes mixed state (called Mixed C&D waste) which is difficult to recycle. In Japan, 45% of mixed C&D was treated at treatment facility to recover recyclables and 37% of it becomes residue that has to be landfilled and has a high risk of H2S generation. Hence, removal of gypsum from residue is urgently requested. In this study it was investigated how gypsum is distributed to various outputs in sorting process and what density range contains the biggest concentration of gypsum. Following results were obtained: 1) Gypsum was distributed most (52.4%) to small fraction <8 mm size. 2) By heavy liquid separation conducted for fine fraction, it was found that 93% of gypsum was concentrated in the density range between 1.59 and 2.28 where 24% of total mass was contained. Hence, in order to reduce the amount of gypsum headed for landfill, removal of this density range after segregating fine particles will be effective.

Journal

  • Proceedings of the Annual Conference of The Japan Society of Waste Management Experts

    Proceedings of the Annual Conference of The Japan Society of Waste Management Experts 19(0), 306-306, 2008

    Japan Society of Material Cycles and Waste Management

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