Sciencemadness Discussion Board

Iron powder from hot packs for hands?

LD5050 - 4-2-2018 at 08:20

I picked up some of those hot packs for hands that heat up when they are exposed to air. I was wondering if I could use the iron powder for reactions that call for it. The ingredients are iron powder, water, activated carbon, vermiculite.

I was thinking of somehow serperating off the iron powder any ideas? Also what is the difference of activated iron powder? Is this just treated with dilute hcl to remove oxides?

[Edited on 2-4-2018 by LD5050]

happyfooddance - 4-2-2018 at 12:11

Use a magnet. It will pick up a lot of the junk, but will be at least a better separation. Also be aware that the iron is made to oxidize quickly, the best thing would be to dump it in a flask and pull a vacuum, and remove the H20 on a hot water bath. Then transfer to a container and seal, OR blanket with inert gas if you have that capability.

The iron SHOULD work for reductions.

Edit: this iron IS activated iron. Vermiculite is I believe mostly aluminum and magnesium silicates, and but for superficial oxides is pretty inert. So it should be good for most uses, but if you are making iron salts expect a bit of Al and Mg contamination, probably some other things.

Also, use a plastic bag around the magnet. It makes it easier to release your iron from the magnet.

[Edited on 2-4-2018 by happyfooddance]

LD5050 - 4-2-2018 at 12:25

Awesome thanks for the tips! Do you think I should wash iron powder with dilute hcl after I separate is from the other junk? And possibly remove water and hcl u see vacuum then store in air tight container?

happyfooddance - 4-2-2018 at 12:45

Quote: Originally posted by LD5050  
Awesome thanks for the tips! Do you think I should wash iron powder with dilute hcl after I separate is from the other junk? And possibly remove water and hcl u see vacuum then store in air tight container?

You are welcome. I wouldn't wash it with HCl, but it all really depends on what you are using it for. I don't think an HCl wash will remove much. I base this on the fact that I once cleaned a bunch of vermiculite with about 10%HCl, at elevated temp for several days, and the vermiculite lost almost no weight. I did the same experiment with diatomaceous earth and lost almost no weight, but the DE was significantly more "white". So I am guessing it's just surface oxides of little quantity.

unionised - 4-2-2018 at 14:15

I'm pretty sure that powdered iron will dissolve almost immediately in any concentration of HCl that deserves the name.
Even water is going to react pretty quickly.

aga - 4-2-2018 at 14:30

I was wondering that.

'Activated' iron is presumably really finely powdered, so would react even with Air if fine enough.

Washing that kind of stuff with HCl would make FeCl2.

Melgar - 4-2-2018 at 18:20

Yes, unionized is correct. This stuff is designed to react very quickly, and there's really no point in an HCl wash, unless you want to ruin your reactants.

I'll add that iron is, in general, the least pure metal that's commercially available. Most metals are electrorefined, but with iron, they just blast it with carbon monoxide until the oxygen all leaves. So it's rarely very pure.

That form of iron powder does make a very good oxygen scavenger, which is the main thing that I use it for.

LD5050 - 4-2-2018 at 18:26

So is this stuff not a good idea to use for reductions?

happyfooddance - 4-2-2018 at 18:56

Again. Remove the water.

They are right. But if you remove the water (which isn't hard to do, I explained it.) It will work fine for reductions.

Edit: this stuff will work GREAT for reductions.

[Edited on 2-5-2018 by happyfooddance]

[Edited on 2-5-2018 by happyfooddance]

If you do an HCl wash it should be cold and dilute...

[Edited on 2-5-2018 by happyfooddance]

Melgar - 4-2-2018 at 21:13

I agree with all of that, except the HCl wash part, because then you're adding water. And that's the thing that you just emphasized needs to be removed. If you add water in the form of HCl, it will form a lump that you won't be able to break up.

happyfooddance - 4-2-2018 at 22:44

I expressly advised against an HCl wash, I said if they were to ddo it as he seemed bent on, it would be better cold and dilute. For reductions though this would not be inadvisable if done properly.

happyfooddance - 4-2-2018 at 22:56

Quote: Originally posted by unionised  
I'm pretty sure that powdered iron will dissolve almost immediately in any concentration of HCl that deserves the name.
Even water is going to react pretty quickly.

What do you mean by "pretty sure"? I have not seen that elemental iron dissolves appreciably in HCl at any concentration, the oxides surely, but... What do you mean "pretty sure"?

Literally I struggle dissolving iron in HCl unless I add H2O2...

aga - 5-2-2018 at 01:07

Fe + 2HCl => H2 + FeCl2 (green)

... is a slow reaction. It works fine with wire wool, even large chunks of iron, just that it is slow.

The more finely divided the iron is, the faster it goes.

If you add H2O2 you'll get FeCl3 (brown/yellow)

FeCl2 will also react with oxygen in the air to FeCl3 although that is an even slower reaction.

LD5050 - 5-2-2018 at 04:11

The reason I brought up hcl wash is because I thought I read somewhere that this is how they "activate" the iron dust. Just wasn't sure or not if it would clean the oxides off but makes sense that it would probably just dissolve everything pretty quickly possibly. I will just evap water off and try to separate with magnet.

Sulaiman - 5-2-2018 at 05:49

I would imagine the iron dust being heated in a reducing atmosphere such as H2 or CO to remove surface oxides.

I just popped down to the lab (ok, shed) to check:
my iron powder, from minerals-water eBay UK, is a couple of years old now,
it is very fine and grey, it reacts immediately but not violently with 1M HCl releasing lots of fine bubbles.
20% HCl gives bubbles and foaming
So I guess the reaction rate is just a function of surface area and acid concentration
- assuming that it is not too oxidised.

EDIT: I just checked, from the vendors current description;
" High purity fine iron powder made of high purity iron by water atomization method.
Classified as mesh 100; however, more than 80% of particles are smaller than 44 microns (mesh 325) "

[Edited on 5-2-2018 by Sulaiman]

JJay - 5-2-2018 at 07:01

I have a couple of sets of Little Hotties hand warmers. They contain iron powder, activated carbon, water, and sodium chloride.

It's not completely clear to me how they work... does air permeate into the handwarmers and react with the iron, creating heat?

A magnet would go a long way towards removing impurities, but if the sodium chloride is finely powdered, it may be necessary to rinse it or melt it. I'm not exactly sure how you would filter iron out of molten sodium chloride, but a glass sinter or some glass wool might do the trick. I'm pretty sure you could burn off the carbon without melting or oxidizing the iron. It's a lot of work for a small amount of pure iron powder.

Depending on the amounts of the impurities and your intended use, purifying the contents of the handwarmers might not be necessary.

NeonPulse - 7-2-2018 at 00:21

I actually tried this attempted extraction of iron from the hot pocket packs. It failed. In order to get the fine powdered Fe I tried a magnet. Sure it picked up the iron but also the equally fine carbon cane along for the ride. I just couldn’t get a decent separation, the whole lot just clumped together. The powders were incredibly fine and even trying to put it in water to sink the heavier iron all I had was a black soup of finely divided carbon and iron. Trying to use a magnet here also proved useless. Surely there is a way though.

zed - 12-2-2018 at 16:38

I been thinking on this lately. Iron powder should be easy to acquire, but the world has turned upside down.

How about steel wool? Snip it up small, with scissors. Might serve.

Pretty sure I can get as much steel wool as I want, cheap, nearby, and within hours.

Sulaiman - 13-2-2018 at 00:46

For wet chemistry iron wool should be equivalent to iron powder, just a little slower to fully react,
but I have noticed that my iron wool does not rust as quickly as my tools in the lab/shed,
so there may be oils or something protecting the surface ?

Probably obvious but I'll type it anyway,
stainless steel wool/scouring pads have a high chromium content,
(I believe c18%),
which can form toxic and/or carcinogenic compounds, or confuse your experimental results.
Iron Powder unavailable ! ... maddness :P

zed - 13-2-2018 at 18:54

No problem with accidentally buying Stainless. Ordinary steel wool is dirt cheap; much cheaper than an equivalent weight of iron powder. In my experience, Stainless is never cheap. You pay a premium for Nickel or Chromium content.