Bayer-geopolymers: An exploration of synergy between the alumina and geopolymer industries
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Previously, caustic residues such as red mud and sodium oxalate have been used to provide filler and as a supplementary source of alkali for geopolymers. However, rather than incorporation of dilute alkali residues within geopolymer precursors, a significant counter-intuitive approach is to synthesise geopolymers using Bayer process liquors as a primary source of caustic sodium aluminate and to add locally available fly ash as a source of reactive silica and additional alumina.In addition to the potential for using significant quantities of industrial residues to manufacture geopolymers, these relatively new cements have the ability to bind a range of contaminants. As the Bayer process could achieve significant process impurity removal by utilisation of plant liquor, synergy between the alumina and geopolymer industries could be achieved.Geopolymers with a Si/Al ratio of 2.3 and a Na/Al ratio of 0.8 were targeted. With only synthetic plant liquor as the alkali activator, geopolymers with a mean compressive strength of 33 MPa were synthesised, while use of processed plant liquor resulted in compressive strengths of 43 MPa.
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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, E.; McLellan, B.; Van Riessen, Arie; Nikraz, H. (2015)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 ...
Sipos, Gabriella (2001)Sodium oxalate is one of the many organics present in Bayer liquor. Due to its limited solubility, sodium oxalate can co-precipitate with alumina trihydrate during precipitation. This can have detrimental effects on the ...