2 cents for what it is worth...
DM is under construction of a core sample building in Ely(near the office) that is as large as the Sate of Minnesota's in Hibbing that the Dept of Natural Resources has, The one in Hibbing stores ALL of the other mines core samples from MN. That should give you an idea the size of this deposit.
As far as Polymet, they will do an open pit mine, not because it is cheaper, but because the depoit is near the surface. Some of the deposit is actually sticking out of the earth. Their SDEIS is going to be released this summer then the final EIS and on to permits.
There will be NO water discharded from this mine to the environment. I own property just down the river from these mines, I have been studying this mining process since 2005. The PLATSOL process uses an autoclave: Pressure oxidation
Concentrate from the flotation cells will be put into a large sealed vessel called an autoclave. Oxygen will be added to create a chemical reaction with nickel concentrate. Heat generated by the exothermic reaction and the high pressure will drive the metals into solution.
DM may utilize a slightly different process, but the goal for both is to have a higher % of ore recovery and a happier bottom line.
DM will do an underground mine because of the depth of the metals and the location in respect to the Boundary Water Canoe Area . They will minimize the amount of surface disturbed by going to depth, creating an underground city or world for the entire project. They will take ore from the deepest portion of the deposit early on an then will backfill that mined area later on with the tailings(waste) rock.
One of the biggest issues that the mines need to get across to the entire world is this: there are a lot of older non-ferrous mines that have had to be cleaned up with super funds after the mine closed or they went bankrupt, so the public is hostile to this aspect and the environ-MENTAL-ists are using that as their defense to stop this mining. These older mines did not know of the sulfur contents that were approaching 30, here is the point THE SULFUR COMTENT IS LESS THAT '1', and MORE THAN 5 YEARS OF TESTING HAS DEMONSTRATED THAT THESE TAILINGS WILL NOT GENERATE ACID.
They are gong to have to have a mine closure plan and provide money up front to the state (100 million clams for Polymet) in the case of some disaster for cleanup. The waste rock will be put on the top of a tailings basin already there from the old Erie plant that has been there since 1950ish. This waste rock will be in liners and covered and have topsoil put over it and the planted, these liner systems are similar to what most all landfills have today and are successfully utilizing.
As far as DM and the environment, they have a battle coming with these nut cases at the Friends of the BWCA, Siera Club,etc, that worship the creation instead of the creator. It amazes me that they have so much funding from private wealthy folks that really think they are elistists. They think they are put here to protect us from ourselves.
There is another deposit that is at about the same stage as DM in the fact that they are still drilling and proving out the find and working toward a pre feasibility, mine plan, environmental studies, etc. They are located in the Yukon, a project called Wellgreen from Prophecy Platinum. Laying bets, I say that gets permited before DM from a jusisticional government process. Just look at Polymet and the years of delays, it should be coming around soon though for them. They are laying the ground work for all the other ones to follow. (Polymet is sponsoring the Minnesota State High School Hockey touney as I type. cool, the entire state watches this tournement) Teck has always been hush hush about their deposit, there are 2 smaller one not far from Polymet that they more that likey wil swallow up over time. And then there is RIO that has it hands on one as well.
The state will need these tax funds for the schools, counties, universities and general use taxes, not to mention all the payroll taxes. Iron ore mining in the area has paid billions for 110 years to the state, non-ferrous mining has the chance to out do its respected iron ore brother by paying even more funds to the government's pockets.
There are words tossed around about deposits like world class, massive, mega, etc. The only word that I can really come up with is Monster.