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The effects of hardpan layers on the water chemistry from the leaching of pyrrhotite-rich tailings material

Gilbert, SE, Cooke, DR and Hollings, P 2003 , 'The effects of hardpan layers on the water chemistry from the leaching of pyrrhotite-rich tailings material' , Environmental Geology, vol. 44, no. 6 , pp. 687-697 , doi:

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Column leaching experiments were used to determine the effects of an iron-rich hardpan layer, on the rate of tailings oxidation and the composition of leachate waters, from the Renison Bell tailings dams in western Tasmania, Australia. One-meter-long PVC columns, filled with tailings,
cover material (Cassiterite Flotation Tailings) and hardpan samples from the tailings dams, were leached over a period of 14 weeks. Under dry cover conditions, when hardpan was present, the solute loads peaked at 21–49 days (Fe at 2,294 ppm and SO4 2- at 4,700 ppm), and stabilised at much lower
concentrations after 9 weeks. In contrast, the solute
loads steadily increased over time in the column where hardpan was absent (SO4 -2 from 1,800 to 3,100 ppm, and Fe from 407 to 1,692 ppm). Under saturated cover conditions, the solute concentrations in the leachate also increased with time (SO4 2- from 1,900 to 17,000 ppm, and Fe from
480 to 8,500 ppm). The presence of a hardpan layer
between the reactive tailings and cover material has
been found to improve leachate water chemistry and
lessen the rate of sulphide oxidation.

Item Type: Article
Authors/Creators:Gilbert, SE and Cooke, DR and Hollings, P
Keywords: Hardpan, Mine tailings,Column leaching, Pyrrhotite oxidation, Tasmania, Australia
Journal or Publication Title: Environmental Geology
ISSN: 0943-0105
DOI / ID Number:
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