Mineralogical and geochemical characterization of mine tailings in the King river delta, Western Tasmania: Implications for long-term stability of trace elements
Sibele C. Nascimento , David R. Cooke , Matthew J. Cracknell , Clare B. Miller , Anita Parbhakar-Fox
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引用次数: 0
Abstract
Nearly a century of mining activities at the Mount Lyell Cu-Zu-Au mine has resulted in the accumulation of ∼14 Mt of fine-grained tailings at the mouth of the King River, Western Tasmania. The tailings consist primarily of sulfides (i.e., pyrite, chalcopyrite, molybdenite, galena), silicates, and amorphous phases such as Fe-oxyhydroxides and sulphates. The long-term weathering of these anthropogenic-deltaic sediments has influenced the geochemical distribution and mineralogical hosts of trace metal(loid)s that are of both environmental concern and economic interest (i.e., Cu, Co, Au, Ag, Mo, As). In this study, the mineralogy, element deportment, and metal(loid) enrichment of variably altered delta sediments were investigated to understand how natural weathering processes influenced the environmental mobility and amenability to reprocessing these waste products.
Micro-scale compositional and textural domains were assessed using laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS), where metal(loid) relationships revealed a complex multi-stage diagenesis within the sediment. Generation of grain-scale geochemical domains through machine learning cluster analysis support the interpretation of in-situ mineralogical growth zones that influence the distribution of trace metal(loid)s. Eight clusters were identified by their unique mineralogical and chemical composition, revealing that metal(loids), initially bound to primary sulfides, have been remobilized and sequestered by authigenic material. This study demonstrates that the complex hydrodynamic and geochemical processes within the delta continue to influence the mobility and long-term stability of legacy contaminants within this deposit. Results demonstrate that machine learning cluster analysis provides a robust tool to understand the distribution of trace metal(loid)s within unconsolidated mining-impacted sediment that have been altered by complex hydrodynamic and geochemical processes. Knowledge generated in this study is relevant for assessing the feasibility of various remediation strategies, including reprocessing of tailings as an alternative management option.
期刊介绍:
Applied Geochemistry is an international journal devoted to publication of original research papers, rapid research communications and selected review papers in geochemistry and urban geochemistry which have some practical application to an aspect of human endeavour, such as the preservation of the environment, health, waste disposal and the search for resources. Papers on applications of inorganic, organic and isotope geochemistry and geochemical processes are therefore welcome provided they meet the main criterion. Spatial and temporal monitoring case studies are only of interest to our international readership if they present new ideas of broad application.
Topics covered include: (1) Environmental geochemistry (including natural and anthropogenic aspects, and protection and remediation strategies); (2) Hydrogeochemistry (surface and groundwater); (3) Medical (urban) geochemistry; (4) The search for energy resources (in particular unconventional oil and gas or emerging metal resources); (5) Energy exploitation (in particular geothermal energy and CCS); (6) Upgrading of energy and mineral resources where there is a direct geochemical application; and (7) Waste disposal, including nuclear waste disposal.