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Burkhard

02/12/12 11:46 PM

#39311 RE: odega #39310

Absolutely, thats a huge advantage over tailing ponds.

De-watering tailings to higher degrees than paste produces a filtered wet (saturated) and dry (unsaturated) cake that can no longer be transported by pipeline due to its low moisture content. These filtered tailings are normally transported by conveyor or truck, deposited, spread and compacted to form an unsaturated tailings deposit. This type of tailings storage produces a stable deposit requiring no retention bunding and is referred to as ‘dry stack’.

A typical moisture content of less than 20% is achieved by using a combination of belt, drum, horizontal and vertical stacked pressure plates and vacuum filtration systems. The term ‘dry cake’ or ‘dry stack’ is not entirely correct as the tailings have a moisture content several percent below saturation. However, this terminology has been adopted by regulators and designers.

Like with thickened and paste tailings, the mechanical dewatering process compared to conventional slurry deposition increases costs. Producing wet and dry cake further increases this cost particularly if high throughputs are required. However, some of the many advantages to using dry stacking of tailings are:

•Can be used in areas where water conservation is critical and any water losses can jeopardize plant performance.
•Dry stacking is suited to areas of high seismic activity as the construction of retention embankments is prevented.
•For cold climates, dry stacking prevents pipe freezes and frosting problems with conventional impoundments.
•Groundwater contamination through seepage is virtually eliminated.
•Filtered tailings allow better recovery of dissolved metals and process chemicals (e.g. gold and cyanide).

Dry stack facilities are also easier to close and rehabilitate, require a smaller footprint compared to other surface tailings storage options (i.e. higher density), can be utilized in aggressive environments (e.g. undulating and steep terrain) and generate better regulator and public perceptions of tailings storage.

Also, dry stacking materials or waste can be removed by truck and deposited at predetermined areas or used to back fill open pits thus leaving the processing area clear of any visible waste and leaving the surrounding environment in a pristine condition.

Just another example of CGI keeping it real.

Sieg

M_T_Pockets

02/13/12 1:05 AM

#39317 RE: odega #39310

Odega, thanks for the update. Let us know if you hear any more interesting details. There is nothing like hearing the discussion first hand. Your opinion on what is said and the atmosphere of the discussions are invaluable!
TIA for your input!
CGFIA