Tailings dam
The Syncrude Mildred Lake Tailings Dyke in Alberta, Canada, is an embankment dam about 18 kilometres (11 mi) long and from 40 to 88 metres (131 to 289 ft) high.
The dam and the artificial lake within it are constructed and maintained as part of ongoing operations by Syncrude in extracting oil from the Athabasca oil sands; it is the largest dam structure on earth by volume, and as of 2001 it was believed to be the largest earth structure in the world by volume of fill.
[3] An estimated 3,500 active tailings impoundments stand around the world, although there is no complete inventory, and the total number is disputed.
[9][10] Brazil and Chile have banned the construction of upstream dams, deeming them too dangerous, and the fifty or so in the Brazilian state of Minas Gerais will have to be decommissioned by 2035.
Analyzing the mineralogy of tailings can reveal the presence of economically valuable minerals, such as rare earth elements or other metal resources.
[14] The infiltration line is the pathway through which water can enter in a specific area,[14] and it affects the safety and stability of tailings ponds.
Rather than consisting of a single uniform body, tailings are usually composed of multiple layers of sediment that differ in grain size and mineralogical composition.
[17] As an example, the Baptiste nickel project in British Columbia, Canada, is known for its potential to mineralize carbon in its tailings.
Similarly, the Gahcho Kué diamond mine in the Northwest Territories, Canada, has kimberlite pipes with the potential for carbon mineralization.
The primary mineralogy of the deposit consists mainly of quartz, topaz, fluorite, micas, clays, chlorite, K-feldspars and opaque minerals including wolframite.
While the tailings are not extensively oxidized, certain areas have elevated sulfate and metal concentrations including lower pH values.
Examples are those found at the abandoned Kam Kotia mine near Timmins, Ontario, Canada, which has been inactive for about 30 years[as of?].
These bacteria catalyze the production of toxic, acidic metal leachates that can severely affect natural ecosystems.
Certain species, such as Acidithiobacillus ferrooxidans, can also reduce iron (Fe (III)) in both aerobic and anaerobic environments at very low pH.
studies suggest that sulfate-reducing bacteria (SRB) can remain viable in oxygenated conditions and even engage in aerobic sulfate reduction in well-oxygenated microbial mats.
