In the last 6 months I have learned a bit of what extractive metallurgy is about. One of my projects involves isolating an element from an ore where the desired element is one of many minor constitutents. What is important here is the term “minor constituents”. When the desired element is a minor constituent, then one necessarily faces the prospect of processing large quantities of mass.
Processing large quantities of mass requires that the material and energy inputs used in the process must be very inexpensive. Except for gold, you have to start thinking of heat as a kind of reagent that can be applied to make things happen. The lucky circumstance with gold is its affinity for cyanide in an oxygenated aqueous environment.
It is a very interesting and worthy challenge to start with rock and contrive to remove purified products from it. Half of the fun is working with the engineers and metallurgists. They have a very different perspective of industry than a stiff like me who has always relied on Aldrich for “raw materials”. I have had to recalibrate a bit. You don’t meet people like this at ACS meetings.
I have spent more than a little time digging into extractive metallurgy from the 19th century. A good deal of fairly sophisticated technology was worked out long ago for many metals on the periodic table. Mostly, what has changed between the metallurgy of yesteryear and today is that we now consider fairly low grade ore as economically viable.
The tailings of yesterday will become the ore of tomorrow. It just depends on the value. When you drive around the gold and silver mining districts in the Colorado Mineral Belt, the tailings that you see from the road have most likely been worked over at least once.