The occurrence of phosphorus and other impurities in Australian iron ores

C. M. Macrae, N. C. Wilson, M. I. Pownceby, P. R. Miller

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The characterisation of high-P iron ores by fi eld emission gun electron probe microanalyser (FEGEPMA) was carried out to determine elemental associations in iron oxides sensus lato and, using this knowledge, to speculate on possible P incorporation mechanisms in goethite. Quantitative data was collected from two goethite-rich bulk ores and results showed that in both samples goethite was the main repository for phosphorus. The P-rich goethite also contained elevated levels of both aluminium and silicon. To understand the mechanism of P incorporation in goethite, high-P grains were located by coarse mapping of polished blocks with the FEG-EPMA. Analysis of element distribution maps collected on the P-rich grains showed that low-P regions within grains were typically associated with low-Al and high-Si, whereas high-P regions were associated with high-Al and low-Si. Based on follow-up quantitative analyses, a coupled substitution mechanism for phosphorus incorporation within goethite was proposed: 2Si 4+ = 1P 5+ + 1Al 3+. Additional quantitative analyses on further examples indicated the mechanism was only valid for Si contents in goethite of <1 wt per cent. Preliminary transmission electron microscope (TEM) studies confi rmed the presence of P, Al and Si in goethite.

Original languageEnglish
Title of host publicationIron Ore 2011
Subtitle of host publication11-13 July 2011, Perth, Western Australia : Proceedings
Place of PublicationCarlton South, Vic, Australia
PublisherAustralasian Institute of Mining and Metallurgy (AusIMM)
Number of pages9
ISBN (Print)9781921522437
Publication statusPublished - 2011
EventIron Ore Conference 2011: Meeting Growing Demand - Pan Pacific Hotel, Perth, Australia
Duration: 11 Jul 201113 Jul 2011


ConferenceIron Ore Conference 2011
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