Unlocking the potential of sulphide tailings: A comprehensive characterization study for critical mineral recovery.

Sulphide tailings are a major environmental concern due to acid mine drainage and heavy metal leaching, with costly treatments that lack economic benefits. Reprocessing these wastes for resource recovery can address pollution while creating economic opportunities. This study aimed to evaluate the potential for critical mineral recovery by characterizing sulphide tailings from a Zn-Cu-Pb mining site. Advanced analytical tools, such as electron microprobe analysis (EMPA) and scanning electron microscopy (SEM)-based energy dispersive spectroscopy (EDS), were utilized to determine the physical, geochemical, and mineralogical properties of the tailings. The results showed that the tailings were fine-grained (∼50 wt% below 63 µm) and composed of Si (∼17 wt%), Ba (∼13 wt%), and Al, Fe, and Mn (∼6 wt%). Of these, Mn, a critical mineral, was analyzed for recovery potential, and it was found to be largely contained in rhodochrosite (MnCO3) mineral. The metallurgical balance revealed that ∼93 wt% of Mn was distributed in -150 + 10 µm size fractions containing 75% of the total mass. Additionally, the mineral liberation analysis indicated that Mn-grains were primarily liberated below 106 µm size, suggesting the need for light grinding of above 106 µm size to liberate the locked Mn minerals. This study demonstrates the potential of sulphide tailings as a source for critical minerals, rather than being a burden, and highlights the benefits of reprocessing them for a resource recovery to address both environmental and economic concerns.

Nano/microplastics: Fragmentation, interaction with co-existing pollutants and their removal from wastewater using membrane processes.

NANO: and microplastic (NP/MP) is one of the most challenging types of micropollutants, coming from either direct release or degradation of plastic items into ecosystems. NP/MP can adsorb hazardous pollutants (such as heavy metals and pharmaceutical compounds) and pathogens onto their surface that are consumed by humans, animals, and aquatic living organisms. This paper presents the interaction of NP/MP with other pollutants in the water environment and mechanisms involved to enable the ultimate fate of NP/MP as well as the effectiveness of metal-organic frame (MOF)-based membrane over conventional membrane processes for NP/MP removal. It is found that conventional membranes could remove MPs when their size is usually more than 1000 nm, but they are ineffective in removing NPs. These NPs have potentially greater health impacts due to their greater surface area. MOF-based membrane could effectively remove both NP and MP due to its large porous structure, high adsorption capacity, and low density. This paper also discusses some challenges associated with MOF-based membranes for NP/MP removal. Finally, we conclude a specific MOF-based ultrafiltration membrane (ED-MIL-101 (Cr)) that can potentially remove both negative and positive charged NP/MP from wastewater by electrostatic attraction and repulsion force with efficient water permeability.

Development of a geospatial database of tailing storage facilities in Australia using satellite images.

Tailings storage facilities (TSFs) are the main source of pollution from mining operations. However, TSFs are increasingly being considered as the potential secondary sources of some critical minerals. Recovering the critical minerals from TSFs is important due to both environmental and economic implications. Yet, identification of the potential TSFs is the major challenge in this venture due to the lack of publicly available database of TSFs. The objective of this study was to identify the TSFs and document their status in the form of a database for Australia. Visual inspection and interpretation of satellite images in Google Earth were used to identify the TSFs in 6 states and the publicly available database of TSFs for Western Australia (WA) was validated in this study to incorporate into a national-level database. This study has identified 331 active and 759 inactive TSFs in Australia. Among the sites, 42 active and 56 inactive mine sites with TSFs were found within 2 km of urban centres in the studied states. Coal and gold were the major commodities of 27% of active mine sites with the TSFs and 38% of inactive mine sites with TSFs, respectively. Approximately 16% of active mine sites with TSFs and 28% of inactive mine sites with TSFs were found to process copper as a major commodity. Considering the companionability matrix, many of these TSFs could be explored for the possible recovery of critical minerals (e.g. rare earth elements, cobalt). This study has developed a national-level database of TSFs for Australia for the first time, and it could be used for a number of applications.