A case study on stabilization and reuse of geopolymer-encapsulated brown coal fly ash

Abstract

Fly ash disposal for coal power stations is an ongoing problem. This paper explores the use of a geopolymeric material to stabilize fly ash and reduce the leach rates of metals, and at the same time determine whether the stabilized material can be reused and recycled as value-added products. Fly ash from the Latrobe Valley, Victoria, Australia, was collected and stabilized in a geopolymer with a molar silica to alumina ratio of 3. Fly ash was collected from electrostatic precipitators [precipitator fly ash (PFA)] and ash disposal ponds [leached fly ash (LFA)] so that a comparison in results between the two types could be made. In terms of stabilization of selected heavy metals, PFA showed better trends towards reduction in leach rates, although for this fly ash the initial concentration of heavy metals is low. LFA showed better trends towards reduction in major elemental leach rates. Compressive strength tests were carried out to determine the potential of the material to be used as recycled products. A maximum compressive strength of 32 MPa was achieved with a PFA-geopolymer combination, which shows that these materials can be recycled and reused. However, more research is still required to achieve greater compressive strengths. Scanning electron microscopy linked the leaching behaviour and compressive strength values with images that showed the fly ash particle-geopolymer interaction. Materials cost estimation was conducted to determine the cost of materials required to stabilize and reuse fly ash geopolymers.

Elaboration of a Phytoremediation Strategy for Successful and Sustainable Rehabilitation of Disturbed and Degraded Land

“…However, due to its high organic and oxygen content, lignite is desired for development as a feedstock for value-added chemicals and products [114,115]. Such value-added products may include geopolymers from coal 'gangue' (defined as the solid waste discharged during coal mining and coal washing) and/or activated lignite [116][117][118], iron-containing humics-stabilized nanoparticles [114], and carbonic nanostructures [119,120]. Early work by Haider and Martin [124] showed that cultures of the ascomycete Epicocium nigrum produced HA in vitro, which was evidenced by the formation of polymers and disappearance of substrate phenols.…”

Compressive strength of geopolymeric cubes produced from solid wastes of Alum Industry and Drinking Water Treatment Plants

“…Geopolymer is emerged as possible technological solution for the effective management of solid industrial wastes, as it achieves to turn a numerous of them into added value products [2,3,4,5], and stabilize and/or immobilize hazardous and toxic materials [6,7,8,9,10,11]. Geopolymers are further more touted for their high performance (high strength and durability), low CO 2 emission and low energy consumption.…”