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Title: Environmental risk assessment of inorganic chemicals in mining environment
Author: Pan, Jilang
ISNI:       0000 0004 2688 2742
Awarding Body: Imperial College London
Current Institution: Imperial College London
Date of Award: 2009
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Mining is one of the human‟s earliest industrial activities. Indeed early civilizations such as the Bronze Age and Iron Age are named according to their use of metals; the importance of metals is still central to industrialization and urbanization. The enormous quantities of mine waste and tailings generated by mining every year however, are also of concern. The relocation and removal of large quantities of mineral and waste can also release chemicals into the environment especially surface water, groundwater and soil during the mining lifecycle if good mining engineering and mitigation are not performed. To optimise this risk management based on excellent risk analysis is required. The study analysed the mining life cycle, chemicals in the mining environment, current regulations on chemicals in the environment and the development of environmental risk assessment framework with particular focus on the inorganic substances. Chemicals in the mining environment were then grouped into a) the minor constituents of the ore deposits; b) chemicals used in mining such as explosives, leaching chemicals and froth flotation reagents. c) chemicals generated by mining, milling and smelting including Acid mine drainage (AMD) and emissions from smelting and refining. The natural and anthropogenic sources, potential pathways to environmental and human receptors and the implications on human health of key toxic metals and metalloids in the mining context were then evaluated. A new two-tier risk assessment was developed based on the four-step conventional risk assessment framework by the U.S.National Research Council (NRC). Tier 1 involved analysing and evaluating existing data using two new semi-quantitative risk screening and prioritisation procedures, namely Chemicals of Greatest Concern (CGC) and Media of Greatest Concern (MGC). CGC was developed using specific hazardous properties of the inorganic chemicals and their eco-toxicities in the environment. MGC was a system of decomposition using a combination of various decision-making tools such as Multi-criteria decision making (MCDM) and Hierarchical holographic modelling (HHM) to facilitate hazard identification and assessment. Tier 2 involved quantitative toxicity assessment, exposure assessment and risk characterisation which were used to quantify the total risk to human health using Monte Carlo simulations (MCS). The tiered risk-based approach developed was evaluated using three cases studies, viz, the Rustenburg platinum (Pt) mine, South Africa; the Lisheen lead (Pb) – zinc (Zn) mine, Ireland and the Richmond copper (Cu) smelter. The results from them were evaluated and compared as a basis for Anglo American plc‟s global strategic decision making. Finally, the strengths and weakness of the methodology developed were evaluated in relation to the application at current operational level. Future methodology refinement and incorporation of organic chemicals were also discussed.
Supervisor: Voulvoulis, Nick Sponsor: Anglo American plc
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral