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Neodymium

Started by Guest_arboramans_* , Feb 19 2012 06:11 PM

 
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#1 Guest_arboramans_*

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Posted 19 February 2012 - 06:11 PM

Although it is classified as a rare earth it is in fact relatively common in the earth at 33mg per kilo. Commercially it is extracted from monazite and bastnaesite by ion exchange and solvent extraction processes. Neodymium metal can be made by the reduction of anhydrous halides with calcium metal. The current price is approx $4000 a kilogram. The World produces 7,000,000 kilograms a year, most of that in China, the second main producer is Canada but it's output is dwarfed by China.

A Toyota Prius uses around 1 kilogram.
Computer Hard Drives use around 10 grams
Electronic devices use between 5-25 grams
Wind Turbine Magnets use up to 2000kgs

from wikipedia:

There are two principal neodymium magnet manufacturing routes:
  • The classical powder metallurgy or sintered magnet process
  • The rapid solidification or bonded magnet process
Sintered Nd-magnets are prepared by the raw materials being melted in a furnace, cast into a mold and cooled to form ingots. The ingots are pulverized and milled to tiny particles. This undergoes a process of liquid-phase sintering whereby the powder is magnetically aligned into dense blocks which are then heat-treated, cut to shape, surface treated and magnetized. Currently, between 45,000 and 50,000 tons of sintered neodymium magnets are produced each year, mainly in China and Japan. As of 2011, China produces more than 95% of rare earth elements, and produces 76% of the world’s total rare earth magnets.
Bonded Nd-magnets are prepared by melt spinning a thin ribbon of the Nd-Fe-B alloy. The ribbon contains randomly oriented Nd2Fe14B nano-scale grains. This ribbon is then pulverized into particles, mixed with a polymer and either compression or injection molded into bonded magnets.

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This process produces an extreme amount of hazardous by-products. At the primary production source in Baotau, According to Du Youlu of Baogang’s safety and environmental protection department, seven million tons of waste a year was discharged into the lake, which is already 100ft high and growing by three feet each year.
Jamie Choi, an expert on toxics for Greenpeace China, says villagers living near the lake face horrendous health risks from the carcinogenic and radioactive waste.
‘There’s not one step of the rare earth mining process that is not disastrous for the environment. Ores are being extracted by pumping acid into the ground, and then they are processed using more acid and chemicals.'

#2 jasserEnv

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Posted 26 February 2012 - 10:15 PM

That is nasty indeed. I have used these magnets for applications in the past and wondering at their environmental impact especially knowing that they are coming from a country like China that seems to have respect for little other than profit, despite being communist and "for the people". I suspect that the problem associated with this mining is to due to the product being somewhat rare so that more earth must be processed to get the required material. Additionally, the complete lack of enforcement of environmental standards in China is also likely to blame.

I do hope that recycling of the material becomes more common. At $4000/kg, there is a market there for reprocessed materials. The biggest problem is finding the products that are using it.

#3 still learning

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Posted 29 February 2012 - 08:14 AM

View PostjasserEnv, on 26 February 2012 - 10:15 PM, said:

...... Additionally, the complete lack of enforcement of environmental standards in China is also likely to blame.
...... At $4000/kg, .

From what I've read elsewhere the Chinese neodymium mining, extraction and reduction process is nastily polluting.  Illegally polluting according to unenforced Chinese regulations, apparently.

Also not just a neodymium/rare earth element problem in the Baotou area, apparently pollution from processing more traditonal materials a problem too:  http://www.ingentaco...000002/art00002

Possibly some relief eventually: http://www.reuters.c...E6A60HD20101107
and   http://www.danjourse...il/a--7575.html

Dunno about the $4000/kg though http://www.metal-pag...ices/neodymium/

Can neodymium production be made safer and less polluting?  I expect so.  Will it in China?  Who knows?

#4 Guest_arboramans_*

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Posted 01 March 2012 - 02:59 PM

Is there a moral equivalency in polluting to produce one type of energy over another?
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