Why Wouldn't a Coal Plant Collect the Mercury for Resale?

I know that I am starting a firestorm with this one, but here goes.

Most of the criticism I have heard about the coal-fired energy plant that is being discussed near Great Falls has revolved around waste mercury that would be an aerosol by-product of burning coal.

First, I only know enough about this to blather, probably incomprehensibly. I am not in the industry, I am not a chemist and I have not extensively studied the issue. As I do in many of these posts, I am actually using this space to ask questions without a preconceived answer.

However, it seems to me that mercury is a valuable industrial metal. If we are building a new plant with new technology, why would that mercury not be collected for resale? A couple quick internet searches showed that this summer, mercury's spot price was more than $1,000 per flask, or about $15 per pound. That is much more expensive than copper, which would be collected and guarded like gold by any scrap outfit.