Characterisation of the Contribution of Iron Ore Dust to the Environment at Port Hedland, Western Australia

摘要

Transport to and handling of iron ore at Port Hedland, Western Australia, results in the generation of airborne particulates that contribute to the atmospheric dust load, with concerns about potential local environmental impacts (eg mangrove swamps) and possible human health implications. Mineral and chemical characteristics of the <2.5 μm, 2.5 - 10 μm and 10-50 μm size fractions of iron ores typical of those managed at Port Hedland and of soil samples representative of background material collected around the port facilities, were determined to establish which ore types were most likely to contribute to background dust levels. Six iron ore types contained between four and six total wt per cent of <10 μm (ie <2.5 and 2.5-10 μm) sized material. The <2.5 μm fraction of all iron ores examined contained significant amounts of kaolinite of up to 20 -30 wt per cent. Background soil samples were contaminated with particles of iron ore as martite octahedra and grains of micro-platy hematite as detected by scanning electron microscopy (SEM) in the 2.5 - 10 μm and 10-50 μm size fractions. Fossilized wood fragments similar to those observed in Yandicoogina fines ore were also detected in some background soil samples. With a predicted increase in demand of channel iron deposits (CID) ores and the inherently dusty Marra Mamba ores (eg West Angelas, MAC, OB29/30/35, Marandoo), in conjunction with particulate emissions from hot-briquetted iron and direct reduced iron (HBI/DRI) processing plants, there is the potential for additional sources of anthropogenic dust to contribute to background levels. Mineralogical and chemical characterisation of the entire range of particulates that could be produced is necessary for a complete understanding of their potential impact on the local environment.