The benefits of using ferrochrome slag as waste aggregate in South Africa

Abstract

This research study aims to promote and optimise the reuse of ferrochrome slag in South Africa. In support thereof, the objectives of this research study are to: identify and describe the environmental benefits of using ferrochrome slag as aggregate; to investigate the probable financial benefits of replacing natural aggregates with ferrochrome slag; and to describe methods of facilitating the reuse of ferrochrome slag as aggregate in South Africa. The research study collected data by the qualitative assessment of a systematic literature review from which a comparative analysis is drawn to achieve the aim and objectives of the study. Ferrochrome slag is generated from the production of ferrochrome and due to its physical and mechanical properties, it is a potentially suitable alternative to natural aggregate used in the construction of roads and infrastructure. South African environmental legislation classified ferrochrome slag as hazardous waste and therefore, the majority of ferrochrome slag has been disposed of onto slag dumps in South Africa. Due to the leaching potential of ferrochrome slag dumps, this has the potential to cause environmental degradation in the event that these disposal facilities are not correctly engineered and operated. The research study confirms that ferrochrome slag does not classify as hazardous when assessed against relevant human health or aquatic ecosystem hazard categories and that there are no physical hazards associated with the reuse of ferrochrome slag under normal conditions. Moreover, land degradation caused by aggregate mining may result in potentially negative environmental impacts and therefore suitable alternatives to natural aggregate should be considered by the construction industry. A key learning from this study indicates that ferrochrome slag is a potentially suitable alternative to natural aggregate for road construction and concrete in South Africa, and it has become a preferred alternative to natural aggregate in many other countries. The benefit of recycling waste such as ferrochrome slag can be summarised as reducing the reliance on natural material, reducing transport or production energy and reducing waste that has to be disposed of onto slag dumps. The study shows that reusing ferrochrome slag as aggregate is a financially viable and environmentally sustainable solution to ferrochrome slag waste management in South Africa. Recent developments toward implementing this solution suggest that the reuse of ferrochrome slag on large scale may realise in the near future; and the researcher acknowledges the effort towards achieving this goal.