Development of lightweight aggregate and concrete from coal washery rejects

Abstract

Australia is the world’s second-largest coal exporter, and coal mining activities in this country have significant environmental impact due to the huge water consumption and waste production. A typical coal preparation plant (CPP) produces 75–120 kg of tailings per tonne of coal processed with a total solid content between 20% to 35% (w/w). The most conventional disposal method is to dispose coal tailings in tailings storage facilities (TSFs) or tailings dams. However, tailings dam failures due to overtopping, internal erosion, earthquake, etc. have always posed a serious environmental threat to the contamination of surface waters and aquifers. Alternatively, the dry disposal method can be adopted, where coal tailings can be dewatered and then used for making value-added products. Different dewatering methods, including flocculation and filtration are widely used to reduce the water content of mine tailings and their negative water impacts. Recycled water can be reused in preparation processes or for other purposes. Moreover, the application of mine tailings as construction materials through the geopolymerisation has been investigated by researchers as a sustainable solution for mine tailings disposal. This research investigated the optimisation of the flocculation process for coal tailings dewatering in terms of settling rate and turbidity removal using polyacrylamide-based (PAM) flocculants. The feasibility of using coal tailings for the production of artificial aggregates (used as road subbase materials) was then studied as a sustainable alternative solution for coal tailings disposal. This research confirms the feasibility of using coal tailings for the production of artificial aggregates, which can be used as a partial substitute for natural road subbase aggregates up to 56% (by volume) for mining haul roads.

Date of Thesis submission	2025
Original language	English
Awarding Institution	Western Sydney University
Supervisor	Zhong Tao (Supervisor), Bijan Samali (Supervisor) & Md Abdul Alim (Supervisor)