Monday, January 04, 2010

More on Rare Earth Metals

I'm hoping Tim stops by and leaves a link or three to some sites that would do a better job than this of educating one about how rare earth metals are processed. In the meantime, here's what I've found out about just what it takes to build all those green devices like Priuses and windmills.

Update: The video below has some cheap shots designed to inflame people who are ignorant of mining technologies used in the US. Tim stopped by and left a comment, part of which I've excised and included below.


Here's how you extract Tantalum and Niobium. Don't try this at home, kids!
The extraction and refining of tantalum, including the separation from niobium in these various tantalum-containing mineral concentrates, is generally accomplished by treating the ores with a mixture of hydrofluoric and sulfuric acids at elevated temperatures. This causes the tantalum and niobium values to dissolve as complex fluorides, and numerous impurities that were present also dissolve. Other elements such as silicon, iron, manganese, titanium, zirconium, uranium, thorium, rare earths, et c. are generally present. The filtration of the digestion slurry, and further processing via solvent extraction using methyl isobutyl ketone (MIBK) or liquid ion exchange using an amine extractant in kerosene, produces highly purified solutions of tantalum and niobium. Generally, the tantalum values in solution are converted into potassium tantalum fluoride (K2TaF7) or tantalum oxide (Ta2O5). The niobium is recovered as niobium oxide (Nb2O5) via neutralization of the niobium fluoride complex with ammonia to form the hydroxide, followed by calcination to the oxide.
Emphasis mine. As an almost-chemist (I took about 48 units of it in college), any time I see mounds of ores being washed by acids, I wonder how in the world the runoff can be processed into anything that can be re-released into nature. No wonder the process is blighting the areas downstream. I also wonder how much ammonia you need for the last process. That, too, is something you can't just pour into the rivers.

All of this leads me back to the VDH piece I've been linking to quite a bit lately and makes me generalize it to the whole green movement.
And then tragically Obama got elected and discovered that the real world had no relationship whatsoever to his fantasy impressions of it. In a cosmos of radical Islam, Chinese bankers, Japanese exporters, and Arab oil producers, there were no more law school profs, Rev. Wrights, or Chris Matthews and Newsweek editors to wink and nod and reassure Obama that his mellifluous but empty rhetoric allusions were at all reality-based.
Maybe turning big chunks of land into a wasteland (reality) in order to prevent something that isn't happening or at least isn't a real threat to anyone (broadly-accepted fantasy) isn't such a good trade-off. Nukes, anyone?

Update from Tim's comment: "Mining and processing in general gets a pretty bad rap, and things like the rather breathlessly shocked video that you linked to don't really help matters. Metals extraction can be done cleanly and safely, and for the most part the mining in the US *is* done pretty well. For example, acid leaching is well-developed technology for copper, and is handled without major acid spills simply by paying attention to the whole what-goes-in-must-come-out principle. This is helped by the fact that there really is a way to deal with acids - just neutralize them with a cheap alkali, like limestone, and then run it through your water-treatment plant."

9 comments:

Dean said...

And to think all those resources, and energy and chemistry stuff could have gone into something truly useful, like brewing beer.

Anonymous said...

Next you're going to make up more scare stories like hydrogen, which we know is EVERYWHERE, requires some sort of industrial process before it can power my car.

Puh.

Kelly the little black dog said...

While I agree you're right on target about Priuses, the windmills are just generators and any kind of generator is going to need these magnets.

Jeff Burton said...

I'll take nukes, thorium flavored, please.

tim eisele said...

Unfortunately, most of the references I'm aware of for rare earth production methods are either print-only, or items that I only have access to because our library has a journal subscription, so I can't really give a good link for processing. Wikipedia has some information, but I think it needs work. It basically amounts to either acid digestion or carbochlorination, followed by ion exchange to fractionate the mixed rare earths into individual metals.

I can link you up with some resource statistics, though, which if nothing else illustrate that there are lots of places to get rare earths other than the Chinese deposits.

http://pubs.usgs.gov/fs/2002/fs087-02/

http://minerals.usgs.gov/minerals/pubs/commodity/rare_earths/myb1-2007-raree.pdf


Mining and processing in general gets a pretty bad rap, and things like the rather breathlessly shocked video that you linked to don't really help matters. Metals extraction can be done cleanly and safely, and for the most part the mining in the US *is* done pretty well. For example, acid leaching is well-developed technology for copper, and is handled without major acid spills simply by paying attention to the whole what-goes-in-must-come-out principle. This is helped by the fact that there really is a way to deal with acids - just neutralize them with a cheap alkali, like limestone, and then run it through your water-treatment plant.

The problem with the rare earth mining in China, as far as I can see, is mainly just that it is being done in China. The only way it's going to be fixed is if they do it themselves, though.

K T Cat said...

Tom, I thought the video had some cheap shots, but some of the information was good. In the end, this is just more subsidizing green technologies, this time by letting the production get done where there are no expensive regulations.

K T Cat said...

I meant Tim, not Tom. I'm typing this on my Droid.

Ohioan@Heart said...

As a once-upon-a-time chemist... "hydrofluoric acid at elevated temperatures"?!?!?

Look, that's not just any acid. HF is really toxic. I used to pour concentrated acids without gloves or goggles all the time (probably stupid, but there you are). To handle HF I'd put on double gloves (the outer ones elbow length rubber gauntlets), goggles and a face shield, and a full length rubber coated leather apron. A small amount on your skin and you are a dead man walking. Wikipedia says skin saturation of 25 square inches can be fatal. Vapors will destroy the cornea. I wonder what the average length of time is that the Chinese workers last?

NOTE: I can't make this up: my captcha is "replated". How appropriate for a discussion on chemistry related to rare earth metals...

K T Cat said...

"Replated"? As a foodblogger, I thought that had to do with serving Cornish Game Hens ...

:-)