Reading various threads on Neodymium from HDD magnets, it looks like the composition of the magnets has changed over time.
Weeks back i mentioned a computer shop that had closed and dumped a load of gear, in the lot i managed to bring home are some old HDD's.
From the size (storage capacity) and a few of the date codes on them, it looks like i have a few from late 80's right upto around 2005.
There isnt many of them but i wondered what age HDD's have the best magnets for Neodymium? I would like to have a go at extracting some Neodymium
compounds, mainly Chloride.silphate and nitrate.
CheersRogueRose - 10-9-2016 at 18:51
last years of 5.25" HD's and the first years of 3.5" SCSI hard drives. They both had really large magnetsMrHomeScientist - 12-9-2016 at 07:00
The older they are, the more likely they are to have SmCo magnets rather than Nd. I ran into that a few times when I got excited about some very large
magnets, then dissolved them in sulfuric acid only to get a green solution instead of a purple one! So large magnets may not necessarily be a good
thing.NEMO-Chemistry - 12-9-2016 at 08:40
The older they are, the more likely they are to have SmCo magnets rather than Nd. I ran into that a few times when I got excited about some very large
magnets, then dissolved them in sulfuric acid only to get a green solution instead of a purple one! So large magnets may not necessarily be a good
thing.
Ok so green = bad and pink = good! 2 really old ones look a nightmare to get into.Deathunter88 - 12-9-2016 at 08:53
The older they are, the more likely they are to have SmCo magnets rather than Nd. I ran into that a few times when I got excited about some very large
magnets, then dissolved them in sulfuric acid only to get a green solution instead of a purple one! So large magnets may not necessarily be a good
thing.
Ok so green = bad and pink = good! 2 really old ones look a nightmare to get into.
Huh? Every time I've dissolved magnets it has resulted in a green solution but it still produced nice pink neodymium sulphate crystals. MrHomeScientist - 12-9-2016 at 09:28
I'd guess the green was probably iron(II) in that case, although that is also what's in the purple/pink solutions. Usually the Nd color washes out any
iron colors. Weird that it seems in some cases it doesn't. I'll admit I didn't try to process any of my green solutions, because I had plenty of
purple/pink ones to go through. Sounds like a good experiment!
[Edited on 9-12-2016 by MrHomeScientist]Mabus - 13-9-2016 at 09:20
At least one of the earliest types of HDD (a big one) I took apart some time ago had a typical AlNiCo/ferrite magnet, and ferrite (?) shielding. But
they're easy to tell apart from Nd magnets: their color is black and don't react fast with acids.Texium - 13-9-2016 at 09:38
That seems unlikely, being as the magnets contain far more
iron than neodymium and the color of neodymium in solution is not incredibly strong.Sulaiman - 13-9-2016 at 10:19
From memory;
washing machine sized drives used huge ferrite magnets
scsi used SmCo
PC HDD used SmCo then Nd
small hdd used Nd and now NdPr
