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Pontikes Y.,Secondary Resources for Building Materials | Pontikes Y.,Center for High Temperature Processes and Sustainable Materials Management | Angelopoulos G.N.,University of Patras
Resources, Conservation and Recycling | Year: 2013

Utilisation of Bayer's process bauxite residue, BR, aka red mud, takes place in a very small fraction worldwide, most probably <5 wt.%. A success story in terms of industrial implementation is utilisation of BR as a raw material in cement production. The use of BR as a pozzolanic material has also been reported, with promising results in laboratory scale. This work aims to present an in depth review of these cases by providing a critical overview of the on-going research over the last forty years. To facilitate the transition from laboratory to industrial scale, a barriers and drivers analysis is also presented for the case of BR addition in the raw meal of cement clinker, following both BR and cement producers' perspective. It is demonstrated that tangible results can be achieved with present-day technology and that one of the major barrier is economic. A number of clear actions are suggested to accelerate the transition towards a more sustainable management of BR. © 2013 Elsevier B.V. Source


Pontikes Y.,Center for High Temperature Processes and Sustainable Materials Management | Kriskova L.,Center for High Temperature Processes and Sustainable Materials Management | Cizer O.,Building Materials and Building Technology Division | Jones P.T.,Center for High Temperature Processes and Sustainable Materials Management | Blanpain B.,Center for High Temperature Processes and Sustainable Materials Management
Advances in Cement Research | Year: 2013

The aim of this work was to investigate the hydraulic behaviour of a stainless steel converter slag after changing its chemical composition and cooling path. The target slag was designed to resemble ground granulated blast-furnace slag (GGBFS). A synthetic slag with a chemical composition close to stainless steel converter slags was mixed with 22, 30 and 38 wt% fly ash (FA) from lignite combustion, heated up to 15508C and then granulated by quenching in water; the solidified new slags were named FA22, FA30 and FA38 respectively. Quantitative X-ray diffraction on FA22 revealed that the amorphous phase was approximately 40 wt%, the rest being bredigite and merwinite. For FA addition of 30 wt% or more, the amorphous phase reached almost 100 wt%. The resulting slags showed significant hydraulic activity when mixed with sodium-based activators, with C-S-H, hydrotalcite and hydrogarnet being the main hydration products formed. The calorimetric behaviour and the mechanical properties of blended cements with 30 wt% FA30 and FA38 were comparable to a blended cement with GGBFS. Assuming that FA addition will take place during the liquid state of the slag, the proposed process can result in a new hydraulic binder. Source


Jones P.T.,Center for High Temperature Processes and Sustainable Materials Management | Geysen D.,Center for High Temperature Processes and Sustainable Materials Management | Tielemans Y.,Group Machiels | Pontikes Y.,Center for High Temperature Processes and Sustainable Materials Management | And 3 more authors.
JOM | Year: 2012

Material loops need to be closed by direct recycling of pre-consumer manufacturing scrap/residues, urban mining of post-consumer End-of-Life products, and landfill mining of historic (and future) urban waste streams. Prior to resource recovery from landfills, conditioning of the material is necessary in order to enable cost-efficient mining and reduce risks related to landfill re-use. Conditioning encompasses both pretreatment for immediate mining, such as measures preventing dust and odor problems, and in-situ transformation to a temporary storage. Innovative separation flow sheets are required which will deliver materials directly recoverable as new resources for the technosphere, and materials to be further valorized after transformational technologies. The Enhanced Landfill Mining Concept (ELFM) incorporates the goal to sequester, use, and offset a significant fraction of the CO2 arising during the energy valorization process. Source

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