Investigation of iron ore mine tailings as an alternative concrete material

Devlin G Zoetelief

The ubiquitous use of traditional concrete can be attributed to its exceptional mechanical properties and low cost. Unfortunately, the two major components of concrete, cement and aggregate, come with an array of inherent environmental impacts. The high temperature processes of manufacturing cement make it a major contributor to global emissions, while aggregates are being over extracted from sensitive environments. Thus, sustainability targets are pushing the construction industry to consider alternative sources. Repurposing waste streams as concrete materials is a potential alternative that could mitigate concrete related impacts whilst simultaneously alleviating the issues of waste management. A substantial West Australian waste stream is the generation of tailings from iron ore mining. Due to the scale of the industry, tailings are a considerable economic and environmental liability to mine operators. By incorporating the iron ore mining waste into a commercial product, the harmful effects of producing concrete can be reduced whilst also improving the sustainability of WA’s most valuable commodity. Research revealed that iron ore tailings have successfully been applied as all constituents of a concrete mix. Its wide range of properties have been utilised as a concrete aggregate and provided binding as a supplementary cementitious material. Furthermore, it has successfully met the prerequisites for producing low carbon geopolymer concrete. However, there is little research regarding tailings sourced from the Pilbara region of WA. This project aimed to improve the utility of WA iron ore tailings by testing them as a concrete material. A full characterisation of the tailings was conducted to determine its potential as a cement and aggregate. This involved physical, chemical and mineralogical assessments. Several tailings based concrete specimens were also developed to investigate their strength and suitability for industry. To assess the sustainable outcomes of tailings concrete integration, a theoretical case study was conducted on a large-scale Pilbara railway project. The results of the characterisation found that the acquired tailings had inert properties, making them unsuitable for cementitious applications and more appropriate for aggregate substitution. The developed lab further concluded this as the tailings were unsuccessful as a geopolymer precursor. However, several specimens tested stronger than the control when incorporating tailings as a supplementary cementitious material or fine aggregate. The case study concluded that aggregate substitution has the greatest capacity for displacing natural river resources. Subsequently, environmental hazards associated with handling tailings can be somewhat alleviated and provide additional sources of revenue long after mine closure. Thus, stimulating new industry for nearby mining towns and improving iron ore profit margins. Carbon emissions were also reduced when incorporating the tailings as any material. Recommended further studies include the characterisation of tailings sourced throughout Pilbara iron ore operations. Investigating their properties would identify tailings most suited for concrete repurposing. Transitioning iron ore tailings from waste stream to construction resource can lessen the environmental impact of the concrete industry. It can reduce cement related emissions and prevent overextraction of natural resources. In addition, by utilising a major mining liability, the sustainability of WA iron ore improves and can stimulate a new Pilbara based industry.

Investigation of iron ore mine tailings as an alternative concrete material

Files and links (1)

Abstract

Details

Metrics