Narottam Saha

• Research Theme 1: In-situ ecological engineering of mine wastes into the functional substrate

The sustainable rehabilitation of alkaline and saline bauxite residue through the ecological engineering approach has a profound impact on managing a huge amount of accumulated bauxite residue in Australia and around the globe (~ 4.6 billion tons). Our cost-effective technology for bauxite residue to functional soil formation by combining multiple interconnected phases such as weathering and bio-neutralization, hydrogeochemical stabilization, and development of physical structures has already proven a significant way forward in bauxite residue management.

Environmental and social benefits - The mobilization of toxic trace elements through seepage and runoff generated from bauxite residue has significant consequences on terrestrial and aquatic ecosystems and groundwater contamination. The dispersion of the fine tailing particles containing toxic elements to the surrounding environment via wind may also affect the environmental quality and human health. The ecological engineering approach of bauxite residue would significantly reduce the environmental pollution risks and transform the hostile tailing environment to soil-like growth media to ensure sustainable colonization of diverse plant species. Rehabilitation of the tailing dam to a new landform through ecological engineering approach may allow different land uses such as grazing, recreational playing field, etc.

Economic benefits – Using the conventional cover system to cap the tailings is associated with a huge financial cost (c.a. several hundreds of thousands of dollars per hector) and acquiring a large volume of topsoil required for the cover system is not feasible and economically viable for rehabilitation of remote mine sites. Our soil-less eco-engineering technology is cost-effective.

• Research Theme 2: Development of chemical technologies to prevent secondary pollution from sulphidic waste rock dumps

This ongoing research aims to develop a cost-effective and field-feasible engineering solution to treat the acid-generating waste rock dumps in situ by purposely formulated chemicals. This technology would minimize and prevent the AMD generation potential of sulphidic waste rock by passivation, encapsulation, and by forming a hardpan structure to create a barrier to stop air entry and hydraulic flow to retard oxidation reaction.

Environmental benefits – This Research aids both physical and geochemical stabilization of reactive materials and mitigates the toxic element pollution to the surrounding environment and allows a sustainable ecological/environmental performance in post-mining land use. The outcomes of the research through a detailed understanding of microstructure and mineralogy would pave the way forward for the rehabilitation of mine wastes in a much improved and sustainable way.

Economic benefits – The conventional soil cover and revegetation approach is not cost-effective and remains far from matching the environmental criteria of non-pollution for final closure. The large volumes of waste rock dumps (WRD) make it highly expensive to adopt the strategy of relocation and backfill in a deep pit, which warrants investigating a cost-effective alternative option. The surface passivation and hardpan formation technology will tackle those difficulties in a cost-effective manner.