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British Columbia Mine Reclamation Symposium

Flooding of oxidized waste rock amended with alkaline by-products Bäckström, Mattias; Domeij, Joel; Sartz, Lotta

Abstract

Leaching of trace elements (Cd, Cu, Pb and Zn) from oxidized waste rock amended with different alkaline by-products was studied during flooding. It has been argued that water covers for oxidized waste would significantly increase leaching through reductive dissolution of the pre-formed hydrous ferric oxides and the associated trace elements. After approximately three weeks pH in the reference had reached 2.5 and 3.3 in the pore and overlying water, respectively. This can be compared with pH from 6.1 (water works granules) to above 10 (lime kiln dust) in the amended systems. It is clear that the carbonate dominated alkaline by-products have lower pH than the oxide/hydroxide based by-products. However, the systems amended with carbonate based by-products have significantly higher alkalinity. Cadmium, Cu, Pb and Zn concentrations within the waste decreased with at least 99% compared to the reference. In most systems the surface waters can even be used as drinking water. Cadmium, copper and zinc concentrations are clearly related to pH with decreasing concentrations with increasing pH. Lead concentrations, on the other hand, decrease to pH 8, where the concentrations start to increase slightly again due to the formation of soluble Pb(OH)₃⁻ and Pb(OH)₄²⁻ species. The results indicate that flooding of oxidized waste rock amended with alkaline by-products can be used as a successful remediation technique.

Item Metadata

Title
Flooding of oxidized waste rock amended with alkaline by-products
Creator
Bäckström, Mattias; Domeij, Joel; Sartz, Lotta
Contributor
British Columbia Mine Reclamation Symposium; University of British Columbia. Norman B. Keevil Institute of Mining Engineering
Date Issued
2010
Description
Leaching of trace elements (Cd, Cu, Pb and Zn) from oxidized waste rock amended with different alkaline by-products was studied during flooding. It has been argued that water covers for oxidized waste would significantly increase leaching through reductive dissolution of the pre-formed hydrous ferric oxides and the associated trace elements. After approximately three weeks pH in the reference had reached 2.5 and 3.3 in the pore and overlying water, respectively. This can be compared with pH from 6.1 (water works granules) to above 10 (lime kiln dust) in the amended systems. It is clear that the carbonate dominated alkaline by-products have lower pH than the oxide/hydroxide based by-products. However, the systems amended with carbonate based by-products have significantly higher alkalinity. Cadmium, Cu, Pb and Zn concentrations within the waste decreased with at least 99% compared to the reference. In most systems the surface waters can even be used as drinking water. Cadmium, copper and zinc concentrations are clearly related to pH with decreasing concentrations with increasing pH. Lead concentrations, on the other hand, decrease to pH 8, where the concentrations start to increase slightly again due to the formation of soluble Pb(OH)₃⁻ and Pb(OH)₄²⁻ species. The results indicate that flooding of oxidized waste rock amended with alkaline by-products can be used as a successful remediation technique.
Genre
Conference Paper
Type
Text
Language
eng
Date Available
2010-12-09
Provider
Vancouver : University of British Columbia Library
Rights
Attribution-NonCommercial-NoDerivatives 4.0 International
DOI
10.14288/1.0042584
URI
http://hdl.handle.net/2429/30351
Affiliation
Non UBC
Peer Review Status
Unreviewed
Scholarly Level
Unknown
Copyright Holder
British Columbia Technical and Research Committee on Reclamation
Rights URI
http://creativecommons.org/licenses/by-nc-nd/4.0/
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Attribution-NonCommercial-NoDerivatives 4.0 International