Mercury mobility in unsaturated gold mine tailings, Murray Brook mine, New Brunswick, Canada

Wetland-based passive treatment systems for gold ore processing effluents containing residual cyanide, metals and nitrogen species

“…There are a number of (successful) cyanide/gold mine wetlands in existence, but these generally have not been publicly described 47,48 . Models of cyanide removal in treatment wetlands have been 15 published 49,50,51 , but little effort has been dedicated to passive treatment of cyanide-rich tailings leachates. Currently, there is little information concerning the behaviour and suitability of passive systems to detoxify cyanide-rich solutions.…”

“…Cattails were analysed before and after the experiment. 15 A pilot-scale passive system was constructed between the cyanidation plant and the tailings disposal facility of a gold mine, within the perimeter of the latter, which is fenced and screened to prevent access by local wildlife (a potential handicap for engineered wetlands treating ecotoxic substances) 60 . The in-situ 20 pilot-scale system was designed in the light of the laboratory findings, and consisted of four units in series:…”

“…Although modern cyanidation plants are designed to minimise the concentrations of cyanide in slurries dispatched to tailings dams for long-term storage, even the modest residual concentrations of cyanide present in tailings dam pore waters can render the leachate 55 potentially toxic to freshwater organisms (and sometimes also to birds and terrestrial animals 13 ; ecotoxic effects may also arise from other contaminants (metals, sulphate, ammonium, nitrate) present in these pore waters, as cyanide complexation has been proved to enhance the release of lots of heavy metals such as Co, Fe, Hg, Ni, 60 Zn, Cu and Ag 14,15,16,17 .…”

“…The alternative approach, "leaching in pulp", involves placing the crushed and ground ore on lined pads, forming heaps which are then irrigated with dilute cyanide solutions. The solution 15 percolates through the heap and the cyanide dissolves the gold; the resultant leachate is then processed as described above.…”

Solid-phase partitioning of mercury in artisanal gold mine tailings from selected key areas in Mindanao, Philippines, and its implications for mercury detoxification

“…This release of mercury from the ball milling tails during CIP is facilitated either by physical (e.g., reduction in size) and/or chemical (i.e., solubization by CN -) processes as explained previously. A previous study by Shaw et al, (2006) showed that CN -mobilized mercury from the tailings and transported it through the porewater as mercury-cyanide complexes (predominantly Hg(CN) 2 ). Thus, the release of mercury into the surrounding aquatic environment is directly dependent on the rate of CN -leaching (Shaw et al, 2006).…”