Comparison of embodied energies of Ordinary Portland Cement with Bayer-derived geopolymer products
MetadataShow full item record
It has been shown that silicate-derived geopolymers can be manufactured with lower greenhouse gas emissions than can Ordinary Portland Cement (OPC). This is assuming that transport methods and distances are equal. In this paper, we have used published and newly-determined data, following closely with accepted life cycle assessment procedures, to evaluate the embodied energy of a new class of geopolymers, namely Bayer-derived geopolymers. These geopolymers utilise concentrated sodium aluminate solutions (Bayer liquor) with fly ash and other aluminosilicates to form geopolymers. Significantly, utilising this combination of industrial by-products can dramatically lower the embodied energy of Bayer-derived geopolymer. Under current industrial operations, Bayer liquor is recycled into the process after intensive treatment, in order to retain alumina and caustic soda however, under alternative configurations this impurity-laden stream could be removed, potentially enhancing environmental performance of both geopolymer and alumina production. In a reconfigured-system, with no allocation of embodied energy to the Bayer waste stream, this could reduce the embodied energy of the derived geopolymer concrete to as little as 0.33 GJ/t. Embodied energies of between 6 and 33% of those associated with OPC have been achieved depending on the process configuration and allocation assumptions used. Most importantly, such assessment indicates that for the first time, Bayer-derived geopolymer binders could be produced with embodied energy intensity at levels comparable to manufactured or recycled sand, gravel and stone.
Showing items related by title, author, creator and subject.
Jamieson, Evan; Penna, B.; Van Riessen, Arie; Nikraz, Hamid (2015)© 2016 Elsevier B.V. The Bayer process is the hydrometallurgical production of alumina, subsequently used within the chemicals industry and for smelting to aluminium. Bauxite deposits have with time become more problematic ...
Jamieson, Evan; Kealley, Cat; Van Riessen, Arie; Hart, Robert D. (2016)The Bayer process utilises high concentrations of caustic and elevated temperature to liberate alumina from bauxite, for the production of aluminium and other chemicals. Within Australia, this process results in 40 million ...
Li, Tian Siong (2000)Precipitation of gibbsite from supersaturated caustic aluminate solutions has been investigated extensively due to its central role in the commercial Bayer plant, for extracting the alumina compound from bauxite. The ...