I don't know anything about the controversy.
I am in favour of the 'dry stack' method which I plan to do at all our company's operations where feasible. In dry stacking you simple remove the water by filtration-suction before placing the tailings on land in a heap similar to dry landfill waste disposal practiced by cities.
Dry stacking increases thruput costs as it is higher energy, but it can significantly lower reclamation permitting time, insurance bonds and other costs. I am not sure Coeur is looking at it right. Closure is easier and cheaper as the whole wet tailings monitoring and water overflow and its hazards are eliminated. Monitoring time and cost after closure goes to zero, overflow and monitoring during operation goes to zero, reclamation can be ongoing as the waste is spread, so costs defrayed to pledge closure may be minimal and carrying cost of those funds are mnimal as they are reclaimed as fast as you reclaim -- which is today. Hazard of run off is minimal as well, as there is no chance of tailings failure and run off into streams, as you bury the waste with rip rap to stabilize it. Only a monstrous freak flash flood could carry the waste away into water courses. These Tsunami like occurrences are a vanishingly small likelihood.
Stacking does cover wetlands. The only way to avoid much of this this is to bury some dry waste, put some underground, and heap the rest up in a high hill. I don't agree that it is that much more expensive than the longer process of making and monitoring a wet tailings facility.
The reason Coeur does not want to do stacking is that it is cheaper to do energy-wise than wet tails. Wet tails is a mature technology. Dry stacking is new to most miners, and to them it is uncertain how to do it cheaply. Dry stacking costs about 2.50 a ton to do, vacuum energy and stacking cost. It must be a fairly low grade mine not to be able to stand that. On the other hand closure of the tailings pond has to be about 2.5 million at least, plus carried interest on the bond, so I would think at a million tons of a high grade mine that is break even or less. On the other hand it points to the fact that Kensington must be fairly low grade.
However I feel they want to avoid the process of going thru this all over again with the dry stacking proposal. As a rule, I find that when a company uses a straw-man proposal such as dry stacking to compete with their prejudice which is wet tails, they generally should have used the straw-man as it would have been better by far. What most people do is start with prejudices and stack reasons on those looking for other prejudices to build up to justify them. Cullaton Lake did a similar thing in the NWT 20 years ago. They went bust with Kilborn giving them the "best" option, ready made by their highly incompetent engineers.
Any time anyone says "simply put", you can be sure it is not simple.
Here is what Coeur says:
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The Kensington Gold Mine has been the subject of 900 environmental studies, extensive public input and agency review. We thought it would be helpful if we addressed one discussion topic - the management of the gold ore material once the gold has been removed.
"Tailings" defined: The material left after gold recovery is called tailings. Simply put, the Kensington tailings are sand-like material that are generally inert and contain less metal content than the native lake sediments where they will be placed. The Kensington tailings are very similar to the sands found at Sandy Beach in Juneau.
Kensington's gold recovery process: Kensington does not use the traditional cyanide process to recover gold. While cyanide can be safely used to recover gold, in response to public concerns the Kensington mine will not use this chemical. Instead, the gold will be recovered using a flotation process. This involves use of degradable flocculants, detergents and air to produce bubbles which the gold mineral attaches to and is then collected. The final flotation concentrate is then shipped to an off-site processing facility.
Lower Slate Lake: The approved plan involves construction of a tailings dam below a small, relatively unproductive lake called Lower Slate Lake. The water quality in the lake does not naturally meet state standards for aluminum and there is little or no spawning habitat for native fish. During mining, this area provides a geotechnically sound location for tailings while reducing impacts to productive wetland and other wildlife habitat.
At the end of mining, the tailings area will be reclaimed into a nearly 60-acre lake with improved productivity and aquatic habitat, as determined through the Final Supplemental Environmental Impact Statement prepared by the U.S. Forest Service. After mining the reclaimed lake will be restocked with wild native fish.
The best and only option: Kensington settled on the current tailings management plan after an exhaustive review of every conceivable alternative. In particular, during the early phases of mine permitting, seven different alternatives for disposal or management of this material were evaluated before the federal and state agencies proceeded with permitting the Lower Slate Lake option.
One alternative to Lower Slake Lake reviewed during mine permitting was a process known as dry stack tailings disposal. In this process the tailings are dried and stacked in a pile on the ground. This alternative was not selected as it was not feasible for the Kensington mine due to increased wetland impacts, logistics, and cost.
The approved plan versus the discarded "dry-stack" plan: The dry-stack option was rejected by the agencies for Kensington, in part, as it would:
* Affect 80 percent more wetlands and other waters than the approved plan,
* Permanently convert 113 acres of wetlands to uplands,
* Double onsite fuel handling and storage requirements (by more than 35 million gallons),
* Result in increased air emissions,
* Be highly visible from Lynn Canal, and
* Significantly increase both operating and reclamation costs.
Meets all standards of the Clean Water Act: The Kensington mine plan meets all standards of the Clean Water Act for placement of fill into the tailings storage area, as well as meeting water quality standards set by EPA and the State for discharges to Slate Creek - thereby protecting Berners Bay.
No acid drainage: The tailings will not produce an acid discharge due mainly to the nature of the ore body itself. This is a carbonate ore body, and the carbonate acts to neutralize the acid.
Tailings management is the approved method: Simply put, the temporary use of Lower Slate Lake is the best option for the Kensington mine and as such, was approved by the U.S. Army Corps of Engineers, U.S. Forest Service and State of Alaska as the environmentally favorable and feasible option.
List of Permits
The Kensington mine is fully permitted for operation. It currently holds almost 20 major permits and almost 60 permits in total.
Alaska Department of Environmental Conservation: 9 major permits and 3 additional permits
Alaska Department of Natural Resources: 10 major permits and 7 additional permits
City and Borough of Juneau: 2 major permits and 4 additional permits
U.S. Army Corps of Engineers: 2 major permits
U.S. Bureau of Alcohol, Tobacco, and Firearms: 1 major permit
U.S Coast Guard: 4 permits
U.S. Environmental Protection Agency: 1 major permit and 2 additional permits
U.S. Federal Communications Commission: 2 permits
U.S. Federal Aviation Administration: 1 permit
U.S. Forest Service: 3 major permits and 3 additional permits
U.S. National Marine Fisheries Services: 1 major permit
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