ZEN has been talking about an open pit operation, presumably this is a more economical operation (but the PEA will tell the story) compared to an underground operation. Underground operation in which the miners have to chase the narrow (high grade) veins (e.g. some mines in Sri Lanka) would be labour intensive and costly. However, if the deposit is amenable to underground (high tonnage, block caving?) bulk mining then this kind UG operation would be econmical. There are many pros and cons for both methods. Just to name a few obvious ones, open pit may look cheaper, but there would be a lot of removal of the barren top layer and waste rock to get at the deposit. The EA process would be more lengthy in dealing with the waste rock, the mine tailings, and the big hole issue.

Looking at ZEN Albany East and West pipes , it would appear that the deposit geometry is suitable for a UG operation (vertical, and mineral in a well defined geometry). In addition, it would be easier to reach the deposit at depth beyond the current pit configuration for covering both pipes. The current pits are (as shown in the Presentation Slide 14) about 400-500m deep, and does not cover the entire height of the deposit, which has a good potential to be open at depth. Deeper pits to reach the lower part of the deposit would be a lot more costly (more waste rock to remove, water issues at depth,...). An example of a UG mine is shown in the link below. This could be superimposed on one of the pipes (say the East pipe) shown in Slide 14 of ZEN Presentation to illustrate a UG extraction of ZEN graphite deposit in the East Pipe. Extraction could be done on both pipes at the same time, or one after the other (do the high grade one first to get some cash flow). In this example a small pit is included in the design.

http://www.endeavourmining.com/s/Tabakoto.asp

A similar geometry is shown by the Noront Ni deposit in the Ring-of-Fire and NOT has decided to go with a UG operation (bulk high tonnage operation) with the processing facility and waste management underground. An interesting design, in a similar environment. The foot print is small and it's "an out of sight out of mind situation" as far as the environment is concerned. For ZEN, they can probably sink a common shaft for extracting the East and West pipe at the same time or do the high grade one first. They can follow NOT example and keep almost everything underground, including disposal of the waste by back-filling of the mined-out areas (at least to get away from the cold above).

http://norontresources.com/wp-content/uploads/2015/01/Corporate-Presentation-Q4-2014.pdf

Just an idea for ZEN to consider as an option. It might be even cheaper over the mine life than open pitting, but we would need some mining experts to take a look to see if this UG scheme has some merit. An mining expert in the house?

Just a bit of thinking outside the box.

May be ZEN will surprise us all with this UG option as well in the PEA?

goldhunter