Potentially risky mining method debated at legislative hearing
by StaceyAt Friday afternoon’s legislative hearing held to address the possibility of future sulfide mining in Minnesota, there was standing room only. Concerned citizens from all over the state attended to hear testimony about this method to extract ores such as copper and nickel. Sulfide mining differs from taconite mining in that it has the potential for acid mine drainage: pollution caused by the exposure of sulfide minerals in the ground to air and water. Not only do sulfide mines pollute heavily while operational, they will continue to pollute for hundreds of years afterwards.
Those who would like to see the mining project go forward argue that a new mining site would give much needed employment to thousands of workers in the Iron Range, serving as an important aspect of the local economy. However, there are many who feel that the risks of sulfide mining should be addressed before putting the plans into practice. While Wisconsin has a moratorium in place stating that to achieve a permit for a sulfide mine the applicant must first prove they can operate a sulfide mine for ten years without acid mine drainage and close a mine without producing pollution for ten years afterwards, Minnesota has no such law.
“We want to see mining without harm and we want the companies to prove that it’s possible,” says Clyde Hanson, co-chair of the Sierra Club North Star Chapter’s Mining Without Harm campaign. “Proof, not promises” is what he would prefer from corporations such as PolyMet who have yet to show that their proposed mine near Babbitt successfully solves these environmental issues.
February 4th, 2008 at 11:30 am
The Polymet proposal has been tested in situ and its results made public. It depends on reacting the sulfuric acid formed by the reduction process to claim the metals with taconite of which there is a huge deposit in the northern Minnesota area (core sampled at over 200 feet deep) resulting from magnetic iron mining 20-30 yrs ago by Cleveland-Cliffs. The resulting compound is gypsum which is also a chemical that in itself is innocuous. The hidden value is that gypsum has commercial value and can add additional jobs to the area. Would the Sierra Club prefer to see the taconite removed or reclaimed seems the issue to me.
February 4th, 2008 at 5:51 pm
PolyMet is not proposing “in situ” (in place) mining of copper by injecting chemicals into wells and pumping up metals in solution. They are proposing an open pit mine.
PolyMet has done two years of humidity cell lab tests of their ore and waste rock to characterize its acid generating potential. DNR experts tell us that the ratio of sulfur to acid buffering compounds (like limestone) of the waste rockand the particle size distribution (of blasted rock) determine the acid generating potential. The smaller the particle size the higher the acid generation. Unfortunately acid mine drainage has not appeared lab tests until after five years of this test weathering (wetting and drying) and PolyMet only has two years of data. So they want to “infir” using data on rocks not from there mine to characterize its pollution potential as required by state rules. Yet at the same time they argue that “their mine is unique.”
Taconite is not being proposed as a buffering material for “hot” wastes. Limestone is proposed with gypsum as the result, which as some commercial potential, but will be landfilled for several years, maybe always. We want the mines to prove they can prevent acid mine drainage and leaching of toxic metals into surface and groundwater by the mine pit and wastes. Taconite is not involved.
We are referring to metallic sulfide mining, not taconite mining. The ore bodies do not mix. There was one taconite mine that had some metallic sulfide rock over the taconite layer. The sulfide rock was dumped into a large pile and it started generating acid mine drainage into Birch Lake. There is a passive treatment system in place there now that will have to be monitored and maintained forever. So far a mining company is paying for this, but will they eventually declare bankruptsy to get out of the obligation?