[ExI] not that rare earth (part 2 of at least 2)

[John Clark]

On Fri, Oct 31, 2025 at 5:34 PM <spike at rainier66.com> wrote:

>
>> * > I noticed Tesla phased them out, which tells me they designed around
> them (that is what they did, by going up the period one row for more
> available materials*
>


*On a typical chart of the elements they are arranged according to their
chemical properties, that's why you'll see that all the rare earth ones are
in a group of their own, they all have very similar chemical properties,
which is why in their natural ore they are all mixed together, and why it
is so difficult to refine them out into separate elements. But Mendeleev's
chart only takes an element's chemical properties into account, NOT an
element's magnetic or optical properties, and those are the very properties
that make some of the rare earths so valuable. In addition to magnets, the
rare earth elements are also of vital importance in fiber-optic
communications, lasers, LED lighting and displays, and night-vision
goggles.*

*>>…69% of rare earth mining comes from China, and more importantly 92% of
>> rare earth refining occurs in China….*
>
>
>
>
> *Ja, but for some applications, it doesn’t need to be “refined” in the way
> we think of the term refined. *
>

*I can't think of any application in which the rare earths don't need to be
refined out into separate elements, if there is such an application it must
not be a very important one.  *

* > A magnet can use a mixture of lanthanides. A magnet can use a mixture
> of lanthanides which can vary slightly, and the final product is the same*


*No. The purity requirements for rare earth magnets are quite stringent,
contamination with other lanthanides in the crystal structure of the magnet
seriously degrades magnetic properties, although Praseodymium is sometimes
deliberately added in very precise amounts to improve thermal stability.
Depending on how good a magnet you need a Neodymium magnet, the most
popular type, needs to be between 95 and 99% pure. A Samarium-Cobalt
magnet, the second most popular type, needs even greater purity, 99+%.*

*>> **Do we really need rare earth elements to get that extra few percent
>> efficiency in permanent magnets? *
>
>
>
>> *>>Yes. Not only are rare earth motors more efficient at converting
>> electricity to kinetic energy…John K Clark*
>
>
>
> *> John what are we comparing to please?  More efficient than iron
> magnets?  Sure, true but irrelevant.  Compare the rare earth magnets to
> alternative material magnets, such as alkali metal magnets,*
>

*Nobody has used iron magnets in motors or generators since the 1930s,
until just a few years ago when somebody said "magnet" they were almost
always talking about an Alnico Magnet, an alloy of Iron, aluminum, nickel
and cobalt that was discovered by a Japanese scientist about 95 years ago
and was revolutionary at the time. They are not nearly as strong but they
are superior to rare earth magnets in one respect, they can get as hot as
800° C and still retain their magnetic properties. *

*> Compare the rare earth magnets to alternative material magnets, such as
> alkali metal magnets*


*T**he entire column of Alkali metals on the periodic chart are
all extremely chemically reactive and do not form permanent magnets, they
are diamagnetic which means they are weakly repelled, not attracted, by a
magnetic field .*


> *> Conclusion: China’s monopoly on rare earth elements has been greatly
> exaggerated. *
>

*I don't think so.  *


*John K Clark*
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