Optimising ambient setting Bayer derived fly ash geopolymers

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 tonnes of mineral residues (Red mud) each year. Over the same period, the energy production sector will produce 14 million tonnes of coal combustion products (Fly ash). Both industrial residues require impoundment storage, yet combining some of these components can produce geopolymers, an alternative to cement. Geopolymers derived from Bayer liquor and fly ash have been made successfully with a compressive strength in excess of 40 MPa after oven curing. However, any product from these industries would require large volume applications with robust operational conditions to maximise utilisation. To facilitate potential unconfined large-scale production, Bayer derived fly ash geopolymers have been optimised to achieve ambient curing. Fly ash from two different power stations have been successfully trialled showing the versatility of the Bayer liquor-ash combination for making geopolymers

Bayer-geopolymers: An exploration of synergy between the alumina and geopolymer industries

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

Hydration Study of Soy Protein in the 'Dry State'

The work reported focuses on the methodology employed by the Australian Food Futures collaboration to the study of proteins in the dry state. To date, 'dry' proteins (here used to describe solids with a moisture conten

Effects of thermal denaturation on the solid-state structure and molecular mobility of glycinin

The effects of moisture and thermal denaturation on the solid-state structure and molecular mobility of soy glycinin powder were investigated using multiple techniques that probe over a range of length and time scales. In native glycinin, increased moisture resulted in a decrease in both the glass transition temperature and the denaturation temperature. The sensitivity of the glass transition temperature to moisture is shown to follow the Gordon-Taylor equation, while the sensitivity of the denaturation temperature to moisture is modeled using Flory's melting point depression theory. While denaturation resulted in a loss of long-range order, the principal conformational structures as detected by infrared are maintained. The temperature range over which the glass to rubber transition occurred was extended on the high temperature side, leading to an increase in the midpoint glass transition temperature and suggesting that the amorphous regions of the newly disordered protein are less mobile. C NMR results supported this hypothesis