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Long-term acid-generating and metal leaching potential of a sub-Arctic oil shale

Citation

Mumford, KA and Pitt, B and Townsend, AT and Snape, I and Gore, DB, Long-term acid-generating and metal leaching potential of a sub-Arctic oil shale, Minerals, 4, (2) pp. 293-312. ISSN 2075-163X (2014) [Refereed Article]


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Copyright 2014 MDPI AG Licenced under Creative Commons Attribution 3.0 Unported (CC BY 3.0) http://creativecommons.org/licenses/by/3.0/

DOI: doi:10.3390/min4020293

Abstract

Shales are increasingly being exploited for oil and unconventional gas. Exploitation of sub-arctic oil shales requires the creation of gravel pads to elevate workings above the heaving effects of ground ice. These gravel pads can potentially generate acidic leachate, which can enhance the mobility of metals from the shale. To examine this potential, pyrite-bearing shale originating from sub-Arctic gravel pad sites were subjected to leaching tests for 600 days at initial pH values ranging from 2 to 5, to simulate potential real world conditions. At set times over the 600 day experiment, pH, oxidation reduction potential (ORP), dissolved oxygen and temperature were recorded and small liquid samples withdrawn and analysed for elemental concentrations using total reflection X-ray fluorescence spectrometry (TRXRF). Six of eight shale samples were found to be acid generating, with pH declining and ORP becoming increasingly positive after 100 days. Two of the eight shale samples produced increasingly alkaline leachate conditions with relatively low ORP after 100 days, indicating an inbuilt buffering capacity. By 600 days the buffering capacity of all samples had been consumed and all leachate samples were acidic. TRXRF analyses demonstrated significant potential for the leaching of S, Fe, Ni, Cu, Zn and Mn with greatest concentrations found in reaction vessels with most acidic pH and highest ORP.

Item Details

Item Type:Refereed Article
Keywords:acid rock drainage, pH, oxidation reduction potential, metal concentration, total reflection X-ray fluorescence spectrometry (TRXRF)
Research Division:Earth Sciences
Research Group:Geochemistry
Research Field:Geochemistry not elsewhere classified
Objective Division:Expanding Knowledge
Objective Group:Expanding Knowledge
Objective Field:Expanding Knowledge in the Environmental Sciences
Author:Townsend, AT (Associate Professor Ashley Townsend)
ID Code:92195
Year Published:2014
Web of Science® Times Cited:2
Deposited By:Central Science Laboratory
Deposited On:2014-06-10
Last Modified:2017-11-06
Downloads:157 View Download Statistics

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