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how to extract from rust form rust rich soil? Answered

OK, so I have this big water treatment plant around me and there is a huge pit where the soil is deep orange and filled with rust. I know its rust because the people who work there told me its rust. If you just touch it your fingers are orange. So I went down there with a plastic bag and gathered up some chunks of soil that were dry and orange. I was wondering how i could extract the iron oxide(rust)  from it so there is no dirt in it and I have a pile of rust. I want to use it for thermite. Thanks alot!

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Jack A LopezBest Answer (author)2011-07-07

I think orange (hematite? Fe2O3) rust will stick to a strong magnet, and a picture of this is attached for those who are unconvinced. Obviously "magnetite" (black, Fe3O4) sticks to a magnet. Ditto for chunks of Fe metal.

Link to large image:
https://www.instructables.com/file/F4H9QX4GP7IHIYN/

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ostomesto (author)Jack A Lopez2011-07-09

I dont know if it will. I may not be using a strong enough magnet though. Its really confusing on what type it is and how to extract it so im gonna post a pic of it.

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Jack A Lopez (author)ostomesto2011-07-09

I should mention that the magnet in that picture is, uh... it's a big one.  It's a large (disc shaped, 2 inch diammeter, 0.5 inch thick) neodymium-iron-boron magnet. I've got it wrapped in cardboard and plastic to protect it, and to keep it from pinching my fingers too badly.

Also I should mention that I am not totally certain what iron oxides are present in my big jar of rust there.     That jar of rust was produced via an electrolysis cell with an iron anode and iron cathode.  These electrodes were a piece of reinforcing bar  and a soup can respectively.  I filtered out the resulting goop, then dried it and put it in a jar.  Interestingly, the goop (precipitate) in the cell was not orange immediately after it was formed.  It started out sort of brown/green colored , but it turned orange after I thoroughly dried it in air.

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ostomesto (author)Jack A Lopez2011-07-10

ok. So should i just go for elctroysis if i want large amounts?

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Jack A Lopez (author)ostomesto2011-07-10

But I thought you'd found the proverbial mother lode.
;-)
Well, the electrolysis method might be something to try.  I think it took several ampere*days, to make the quantity of rust shown in the picture. And I never did get around to trying to make thermite with it. 

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ostomesto (author)Jack A Lopez2011-07-10

well it is very orange and would seem that way but its not. If you didnt use it for thermite what did you use it for?

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Jack A Lopez (author)ostomesto2011-07-12

I haven't used it for thermite yet.  Fot the most part it has just been sitting on a shelf with the other unfinished projects.  I used a few grams of it in an attempt to make some ferrofluid, but that  did not work out very well.  At least I don't have to worry about it rusting. Ha!

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ostomesto (author)Jack A Lopez2011-07-12

haha. if you never use it I would love to "barrow" it for some thermite haha

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Dornier335A (author)2011-07-09

1. Put the rust in a NaCl solution for a week. All the iron will completely oxidize.
2. Wash it and filter it several times. You will get rid of the salt.
3. Dry it.
4. Bake it in an oven.
5. Use a magnet to separate the iron oxide from the dirt.


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ostomesto (author)Dornier335A2011-07-09

well the dirt doestn happen to have as much as I thought. Its really orange but it doesnt contain alot of actaul iron and rust particles

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Dornier335A (author)ostomesto2011-07-10

Take 2 nails of iron, attach them to a 9 volt battery and put them in a NaCl solution. They will turn into rust very quickly. Let the rust stay in the solution for a while so it can oxidize completely. Filter and wash. Dry. Bake in an oven.
Make your thermite!

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lemonie (author)2011-07-07

Bake it in a hot oven until it goes black.

L

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Jack A Lopez (author)lemonie2011-07-07

Black, like magnetite (Fe3O4)  black?  Somebody else was asking about this today, erm... yesterday, here:
https://www.instructables.com/answers/Making-Fe3O4-from-Fe2O3/

Just bake it?  Is it really that easy?


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lemonie (author)Jack A Lopez2011-07-07


Iron oxide, not magnetite - the rust-colour comes from water, it's just a drying process.

L

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Jack A Lopez (author)lemonie2011-07-08

Thanks for the clarification. So iron-3 oxide is orange when hydrated. Black when de-hydrated.

Guessing something like: 2 FeOOH = Fe2O3 +H2O?  Or maybe there's more water in it than that?  I guess I could weigh it before and after baking it...

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lemonie (author)Jack A Lopez2011-07-09


It's hexaqua iron that is yellow/orange/brown, yes.

L

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