Date of Award

2015

Degree Type

Thesis

Degree Name

Doctor of Philosophy

School

School of Engineering

Faculty

Faculty of Health, Engineering and Science

First Advisor

Associate Professor Sanjay Kumar Shukla

Second Advisor

Professor Daryoush Habibi

Abstract

The mine tailings are generated as the wastes worldwide as a result of exploration, excavation, blasting, beneficiation and extraction of mineral ores. In Western Australia, due to the extensive mining activities and increasing low grade ores, there is generation of mine tailings in large quantities, which could lead to environmental and disposal problems. The common practice of handling the tailings are to store them in tailing dams or as stockpiles near mine sites. Limited quantities are sometimes used as backfills and other applications. The utilisation of tailings in building and construction projects, which may consume a large volume of wastes, have not been explored extensively so far. Additionally, the understanding of chemical composition-based utilisation of tailings has very limited investigation.

In the present research, a critical review of the literature was made focusing on the utilisation of mine tailings in large quantities. Experiments have been conducted by developing a methodology to characterise the tailings based on the relationship that exists between electrical resistivity and the relative density of the tailings in dry and wet conditions. The results show that the electrical resistivity of iron ore mine tailings produced in Western Australia in dry condition ranges from 11 kΩm in a more dense state to 19 kΩm in a very loose state, while that in fully saturated condition ranges from 20 Ωm for a very dense state to 31 Ωm in a very loose state.

The laboratory investigation has been conducted to utilise iron ore tailings to produce geopolymer bricks. The sized tailings were mixed with sodium silicate solution used as an activator to form a paste. The paste was moulded and cured for different durations. It was found that the geopolymer bricks produced from iron ore tailings could have a compressive strength as high as 50.35 MPa. This is either superior or similar to international standard specifications for conventional bricks. Additionally, the new bricks will be more economical than conventional bricks with potential cost reduction of 36.8%.

The research has also investigated the utilisation of iron ore mine tailings to replace conventional aggregates in concrete. 100% of both fine and coarse conventional aggregates were replaced with tailings in the mixed design. The concrete mix was casted into moulds and cured. It was found that the compressive strength of the concrete with tailings aggregates at 28 days was 36.95 MPa which shows an improvement of 11.56% over the concrete with conventional aggregates. Additionally, the new concrete met all other requirements for quality assessment of concrete.

Finally, the research has conducted investigation into load-settlement behaviour of iron ore tailings to be considered as a structural fill material. The experiment was conducted in a model test tank in the laboratory varying the relative density of the tailings. It was found that the load-bearing capacity is 22 times higher, and the stiffness is 13.5 times higher than their values for conventional fill materials.

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