A new technology could make some of those mining tailings -- the waste rock -- a lot more valuable than they currently are.
Mining depends on getting the most of whatever mineral you want out of the rock it's mixed in. How valuable a deposit is depends on how easy it is to get the minerals out, and what technologies you can use to do that. Currently a lot of mining involves crushing the ore and making it into a slurry, with water as the liquid. Usually, a chemical, called a surfactant, is added to the slurry, which is then mixed with more water which gets aerated. The chemical depends on the ore and the mineral you want. If it's copper you use pine oil, for instance.
BLOG: Sandia Rolls Out Robot Rescuer For Mines
The surfactant sticks to the particles of the mineral (say, copper) and also to the bubbles. The bubbles float up to the surface and make a frothy layer a lot like the head on a beer. Remove the froth, and you can get the mineral you want by refining it.
Robert Pelton and his team at McMaster University in Ontario, Canada, created a new substance made of nanopartcles of polystyrene (similar to styrofoam). Using glass beads to simulate the kind of particles you'd see in mining, they found the polystyrene did a much better job of sticking to the beads than conventional surfactants. The difference is the recovery rate, which was close to 100 percent. The team published their results in the journal Langmuir.
BLOG: Strip Mine the Moon to Fuel Space Exploration
If this works for real-world mining it means that a lot more mining waste can be used. There are piles of tailings near many mines around the world, and they are left where they are because it isn't worth trying to process them for whatever they contain. Tailings piles can be an environmental hazard for years as toxic metals leach in to water. So anything that could boost recycling of that material is probably a good thing -- and has the added bonus of reducing the need for new mines.
Tags: Chemistry, Nanomaterials, Nanotech, Nanotoxicology
comments ( )