The soaring cost of rare earth oxides (REOs) has forced the price of magnets to rise, driving component manufacturers, machine builders, and OEMs to seek out ways to reduce the impact of the effect. The problem is that, when it comes to permanent-magnet motors, we'd come to take the benefits of REOs for granted.
For example, until very recently, the combination of the enhanced magnetic field strength introduced by neodymium and the thermal resilience contributed by dysprosium enabled the economical production of compact, high-torque motors that can survive harsh conditions. With the REO price jump, engineers find themselves considering alternative designs to minimize the amount of rare earth magnets in a system without hurting performance.
This post, the second in a five-part Design News series on rare earth materials, looks at engineering approaches to mitigate the effects of rare earth element (REE) prices on motor costs. In part 1, we set the context and outlined the four basic design approaches engineers can use to tackle the problem. Here, we'll focus on the first method to reduce the amount of rare earth magnets in permanent-magnet motors.
Faraday’s Law, which relates EMF to magnetic flux, describes the basic physics behind motor operation. In turn, we can express flux through a loop as a function of magnetic field and area. As a result, adjusting the geometry of a motor, particularly the windings, can give designers degrees of freedom for reducing magnet content while maintaining torque levels. “If done carefully, shortening the axial length of a motor and increasing its diameter to meet the same performance specifications can lead to less magnet material,” said Duane Hanselman, associate professor of electrical and computer engineering at the University of Maine.
Making tradeoffs
Motors can be magnet-oriented (to minimize copper windings) or copper-oriented (to minimize magnet material). Back when neodymium was cheap and copper was expensive, motor designers let the REO magnets do the work. Adjusting to the new cost basis just requires redistributing the active materials within a given volume essentially to compensate for the reduced magnet material with copper.
That's a good question, Cvandewater. In my brief searching on the question, I couldn't find any actual examples of recycling in this area. So it remains a good questions. And it makes sense that you put "rare" in quotes. These materials are listed as "rare earths" on the periodic table, but they are anything but rare.
Always fun to see an old discussion being moved back to the front of the stage... The only issue was that very little hard data was presented during that discussion, so my question is still if this recycling is indeed happening or not and whether it would be a meaningful contribution to the short-term scarcity of "rare" earth material (until the previously abandoned mines/non-China suppliers come back online).
Yes, that's pretty much what I learned in my reporting. It's an expensive ramp-up, so the only mine in North America, Molycorp, went public and raised $394 million to get going. By now they may be delivering materials. Not sure.
Here's a February article from the Atlantic that spells out the history and brings you up to date:
A) the rare earth material availability shortage is a short term (roughly 2 years) issue.
B) Because of the shortage there will be a spike in market price due to demand, but the price will start to come down as these other mining supplies come on stream.
C) the price will come back down and level off at a level somewhat higher than the previous "depressed price", when China was flooding the market with cheaper rare earth materials.
Another question: Does this include Beryllium mining in the USA too?
Good question, David12345. I covered rare earths last year for EDN and was surprised to find that North America has plenty of rare earth materials. The problem is that over that past two decades, these materials have been so cheap in China that is hasn't been cost effective to dig baby dig. Now with China rationing rare earths, it has become profitable to dig. But there is a time-consuming ramp-up. So it will be a couple years before all of these materials are flowing again.
Don't let the term "rare" fool you. Neodymium for instance is quite prevalent in nature but not necessarily in an economically extratable form.
Yes we have them and Canada has them. Extraction of REO is typically from tailings resulting from Uranium, Thorium or Iron mining.There simply isn't as much as in China but it is substantial and US mines are being reactivated. Some of these mines were shut down as a result of Chinese undercutting the market.
World Mine Production and Reserves: Reserves data for Australia, China, and India were updated based on data from the respective countries.
Mine production Reserves 2009 2010 United States — — 13,000,000 Australia — — 1,600,000 Brazil 550 550 48,000 China 129,000 130,000 55,000,000 Commonwealth of Independent States NA NA 19,000,000 India 2,700 2,700 3,100,000 Malaysia 350 350 30,000 Other countries NA NA 22,000,000 World total (rounded) 133,000 130,000 110,000,000
Do we even have appreciable quantities of these raw materials available to consider mining in the United States? I thought that some of these "rare earth" materials had only been found in a very few places on earth.
One obvious conclusion is to start digging on US soil for these materials. As I understand it China eventually will consume the entire supply of REO it is producing for it's wind power industry. We are just funding the construction of these mining operations and developing the technology to use these materials. Once they are in full swing they will have no motivation to sell these materials outside their country.
We looked at a number of sources to determine this year's greenest cars, from KBB to automotive trade magazines to environmental organizations. These 14 cars emerged as being great at either stretching fuel or reducing carbon footprint.
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