Metal mobility

At the EEGL, we study the roles that minerals play in metal and metalloid mobility with the goal of improving both recovery of economically important metal resources and the stability of trapping hazardous metals.

Mine sites and ore processing circuits are particularly interesting and valuable places to study mineral dissolution and precipitation reactions. Exposing rocks to Earth’s surface conditions initiates a suite of chemical reactions and mineral transformations. With exposure to water, air, and the biosphere, unstable minerals break down and new minerals form, commonly incorporating water and gasses from the environment. Because mine sites are typically rich in a variety of metals, the resulting anthropogenic mineral assemblages are always unique and sometimes bizarre.

The mobility of toxic metals during these reactions can sometimes cause contamination of waterways and soil. Managing metal mobility during in industrial processes and during remediation costs industry and governments many millions of dollars every year. On the flip side, mineral wastes provide a vast source of valuable metals, which could potentially be recovered.

Remediating arsenic contamination. Arsenic contamination is a serious environmental problem for many current and abandoned mine sites. The strategies commonly used to mitigate release of other common metals at mine sites (i.e., Cu, Co, Zn, Pb) are often ineffective in trapping and removing this redox-sensitive metalloid. We have been working with colleagues at the University of Nevada at Los Vegas and the Australian Synchrotron to investigate As-bearing mineral phases at abandoned mine sites to (1) assess their stability as novel traps for this element and (2) address the potential for As release under proposed remediation treatments (e.g., Hebbard et al. 2015).

Metal mobility during enhanced weathering and carbonation. Carbon mineralization technologies commonly use acids to enhance the rate of silicate mineral dissolution and carbonate precipitation. However, the favoured feedstock materials for carbon mineralization, such as mine tailings and other alkaline industrial wastes, commonly contain low levels of potentially hazardous transition metals. Therefore, the use of acids to accelerate mineral dissolution poses a potential risk for metal release into the biosphere. We are investigating the mobility of common trace metals found in ultramafic rocks and assessing the capacity of alteration products to aid in their sequestration (e.g., Hamilton et al. 2016).

Trapping non-target metals during Cu-U ore processing. While our research group was based in Australia, we were involved in the ARC Research Hub for Australian Copper-Uranium, which is led by The University of Adelaide. The Monash-based node is led by Prof Joël Brugger. We investigated the behaviour of Cu-U ore and gangue minerals to improve extraction of non-target metals during ore processing. Our end goal was to improve the environmental sustainability, marketability, and efficiency of Cu-U ore processing.