Evaluating waste rock mineralogy and microtexture during kinetic testing for improved acid rock drainage prediction

Parbhakar-Fox, Anita, Lottermoser, Bernd and Bradshaw, Dee (2013) Evaluating waste rock mineralogy and microtexture during kinetic testing for improved acid rock drainage prediction. Minerals Engineering, 52 111-124. doi:10.1016/j.mineng.2013.04.022

Author Parbhakar-Fox, Anita
Lottermoser, Bernd
Bradshaw, Dee
Title Evaluating waste rock mineralogy and microtexture during kinetic testing for improved acid rock drainage prediction
Journal name Minerals Engineering   Check publisher's open access policy
ISSN 0892-6875
Publication date 2013
Year available 2013
Sub-type Article (original research)
DOI 10.1016/j.mineng.2013.04.022
Open Access Status
Volume 52
Start page 111
End page 124
Total pages 14
Place of publication Kidlington, Oxford, United Kingdom
Publisher Pergamon
Collection year 2014
Language eng
Abstract This study integrates detailed mineralogical and microtextural analyses of waste rock with the results of standard kinetic test procedures to identify the mineralogical changes that influence leachate chemistry over time. The integration of mineralogy and texture provides the opportunity for improved mine waste management strategies and acid rock drainage (ARD) prediction. Waste rock material from an abandoned gold mine in northern Queensland, Australia, was subjected to column leach kinetic testing over a 30 week period. The column feed comprised of a range of waste rock lithologies (porphyritic rhyolite, massive arsenopyrite, massive pyrite ± galena, and semi-massive polysulphide). In total, 12 individual columns were established to represent six lithologies prepared to two different size fractions (-10 mm and -4 mm). The mineralogy and microtextural characteristics of the column feed material was defined using quantitative X-ray diffractometry (QXRD), scanning electron microscopy and laser ablation (LA-ICPMS) at the start of kinetic tests, and at 5 week intervals during the length of the tests. These data were directly correlated with leachate chemistry (i.e., pH, SO4 and select elements). Results of this study indicated that sulphide oxidation was strongly influenced by the morphology of sulphide minerals, their trace element contents, the presence of mineral micro-inclusions and galvanic interactions with other sulphide minerals. Waste rock with abundant arsenopyrite was consistently the most acid forming, and oxidised to scorodite (enriched in Zn, Pb and Cu). Pyrite was commonly As-rich as indicated by LA-ICPMS mapping. QXRD results indicated that the abundance of rhomboclase, jarosite, alunite and hydrous ferric oxides increased over time. Galena weathered rapidly to porous anglesite, particularly when in direct physical contact with pyrite. Sphalerite contents decreased consistently over the 30 weeks implying its oxidation, however few reaction products were directly observed. By week 30, the -4 mm fraction material generated lower pH leachate, higher mass release of elements and sulphate for the majority of samples. This indicates that the particle size used in kinetic tests can exert a significant control on leachate chemistry, especially in the absence of abundant neutralising minerals. This contribution demonstrates the value of integrating mineralogy and microtextural analyses during kinetic testwork to improve the interpretation of sulphide oxidation for better prediction of ARD.
Keyword Acid rock drainage
Kinetic testing
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: Julius Kruttschnitt Mineral Research Centre Publications
Official 2014 Collection
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Citation counts: TR Web of Science Citation Count  Cited 11 times in Thomson Reuters Web of Science Article | Citations
Scopus Citation Count Cited 11 times in Scopus Article | Citations
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Created: Tue, 28 May 2013, 09:02:04 EST by Karen Holtham on behalf of Julius Kruttschnitt Mineral Research Centre