Sciencemadness Discussion Board - Magnets

Magnets

Dalis - 4-5-2015 at 19:54

I have collected a few magnets for my element collection. I would like to know who I could figure out what kind of magnet it is. I have a crushed magnet from a BaneBots motor, 6 hardrive magnets, and a few from headphone speakers. If anyone got any good ideas as to acquisition of other metals, do let me know.

diddi - 4-5-2015 at 20:30

your magnets will be mixtures of elements and prolly not much use as specimens. the hard drive magnets contain Nd, Fe and B. good luck separating them. (there are several threads on SM) The other magnets may contain Fe, Ni, Co, Sm depending on the construction method and application (eg high end speakers often use CoSm). Again, hard to extract the individual elements.

Many metals can be obtained in everyday items, and it really depends on how fussy you are about presentation and purity. eg if you want some lithium, buy a lithium battery and rip it open. (see SM threads) but beware that it will blacken almost instantly.
if you want tungsten, grab an incandescent light bulb filament...

the bulk of elements you will find are combined and required at least some chemistry to extract, but that is the fun of it all.

MrHomeScientist - 5-5-2015 at 06:14

I don't know what a BaneBot is, but headphone and hard drive magnets are almost certainly neodymium - it's the only type that meets the requirement of small size and high strength. As diddi said, this is an alloy: Nd2Fe14B. As you can see, the majority is iron. If you want to separate out the components of the alloy, it's a hell of a task (trust me). Getting the boron out is easy (dissolve the magnet in sulfuric acid and it will be left over as a black powder), but separating out the iron and reducing the Nd back to a metal is the tricky part.
See the thread The trouble with neodymium... for all our efforts towards this goal. Right now I have some clean NdF3 that I plan on reacting with lithium metal to free the elemental neodymium, using an inert atmosphere crucible I built. I haven't tested it yet, though, so who knows. Exciting times ahead though!

A possible way to test what you have is to dissolve a piece of each magnet in sulfuric acid. Neodymium magnets will yield a dark purplish solution. Several of my magnets I tried yielded a green solution, which I suspect (but am not sure) might be the samarium variety.

Dalis - 5-5-2015 at 12:55

So to remove nickel plating I would have to either crush the magnets or use nitric acid right? Also BaneBots is a motor manufactor.

blogfast25 - 5-5-2015 at 13:03

Quote: Originally posted by Dalis

So to remove nickel plating I would have to either crush the magnets or use nitric acid right? Also BaneBots is a motor manufactor.

I demagnetise the magnets first on a hotplate, then crush them somewhat. I don't remove the nickel (it's quite resistant to HCl/H2SO4). Any Ni that does dissolve will stay with the Fe in later stages of the work-up.

I use 33 % HCl, in excess. H2SO4 didn't work very well for me: Nd sulphate is poorly soluble, even more so when hot. HNO3 is overkill as both Fe and Nd are electropositive metals.

If you're looking to isolate the Nd, please report your findings in the thread linked to above (RE data are already too scattered over this forum).

MrHomeScientist - 5-5-2015 at 13:04

The way I did it was to heat the magnet with a propane torch for a couple minutes until it demagnetized (see: Curie temperature), snapped it into several large pieces, and peeled off the Ni as much as possible. Demagnetizing makes it much simpler to work with. Don't worry if you can't get all the plating off, since it shouldn't dissolve in sulfuric acid anyway*. The more you get off, the more magnet surface is available to react and the faster it will dissolve. Warning: dissolving an entire hard drive magnet takes several days in my experience. Heating the solution should of course speed this up a bit.

*Interestingly, though, I have had instances where the nickel mysteriously vanishes by the time the magnet is fully dissolved

Edit: Dang! Blogfast beat me to it

But yes, see the thread I linked for more info than you ever wanted to know about this process.
If I ever do finally succeed, I will definitely post a succinct report in the prepublication section.

[Edited on 5-5-2015 by MrHomeScientist]

Dalis - 5-5-2015 at 13:07

Quote: Originally posted by MrHomeScientist

I don't know what a BaneBot is, but headphone and hard drive magnets are almost certainly neodymium - it's the only type that meets the requirement of small size and high strength. As diddi said, this is an alloy: Nd2Fe14B. As you can see, the majority is iron. If you want to separate out the components of the alloy, it's a hell of a task (trust me). Getting the boron out is easy (dissolve the magnet in sulfuric acid and it will be left over as a black powder), but separating out the iron and reducing the Nd back to a metal is the tricky part.
See the thread The trouble with neodymium... for all our efforts towards this goal. Right now I have some clean NdF3 that I plan on reacting with lithium metal to free the elemental neodymium, using an inert atmosphere crucible I built. I haven't tested it yet, though, so who knows. Exciting times ahead though!

A possible way to test what you have is to dissolve a piece of each magnet in sulfuric acid. Neodymium magnets will yield a dark purplish solution. Several of my magnets I tried yielded a green solution, which I suspect (but am not sure) might be the samarium variety.

Couldn't you just use CaO or chalk instead of lithium? And use a furnace instead of the chamber. Heck is CaO a good reganent for metal seperation? I have chalk from when I was younger.

Dalis - 5-5-2015 at 13:11

Quote: Originally posted by MrHomeScientist

The way I did it was to heat the magnet with a propane torch for a couple minutes until it demagnetized (see: Curie temperature), snapped it into several large pieces, and peeled off the Ni as much as possible. Demagnetizing makes it much simpler to work with. Don't worry if you can't get all the plating off, since it shouldn't dissolve in sulfuric acid anyway*. The more you get off, the more magnet surface is available to react and the faster it will dissolve. Warning: dissolving an entire hard drive magnet takes several days in my experience. Heating the solution should of course speed this up a bit.

*Interestingly, though, I have had instances where the nickel mysteriously vanishes by the time the magnet is fully dissolved

Edit: Dang! Blogfast beat me to it

Nickel carbonile...... It converted to nickel carbonile. As a warning that is VERY toxic. NiCO. I was worried about that. Also couldn't you use a density column to sperate the Nicklel?

[Edited on 5-5-2015 by Dalis]

blogfast25 - 5-5-2015 at 13:29

Quote: Originally posted by Dalis

[/rquote]

Nickel carbonile...... It converted to nickel carbonile. As a warning that is VERY toxic. NiCO. I was worried about that. Also couldn't you use a density column to sperate the Nicklel?

The chances of forming nickel carbonyl (Ni(CO)4

is as close to zero as you can possibly get. Where would the CO come from? Even with access to CO nickel carbonyl isn't that easy to prepare.

CaO???? Try to concentrate on getting your magnets to dissolve first.

@MrHS: with reflux at BP (simmering) it's a couple of hours, tops. About 50 % stoichiometric excess of HCl.

MrHomeScientist - 6-5-2015 at 05:36

Geez maybe I need to switch acids...
And then just add potassium sulfate to drop out the double salt (no intermediate steps)? Seems like you'd need more sulfate around for complete precipitation.

blogfast25 - 6-5-2015 at 06:17

Quote: Originally posted by MrHomeScientist

And then just add potassium sulfate to drop out the double salt (no intermediate steps)? Seems like you'd need more sulfate around for complete precipitation.

You do but it's an inexpensive chemical.