# Magnetite, a Simple method!

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after reading some of the difficulties making Magnetite in other threads, I took up the challenge of finding a more Simple and near foolproof method thats also much cheaper!

rather than using the commonly known FeCl3 method, Im going an alternative route.

you need only 2 readily available chems for this, Iron Sulphate (FeSO4) that you can get from almost Any gardening store as Moss killer for lawns, its also pretty easy to make if you wanted to.

and simple Washing Soda (Na2CO3), if for some bizzare reason you can get this then use baking soda thats been heated to a high heat for a while, this will convert it to washing soda also.

here:

washing soda on the left, iron sulphate on the right, I recrystalised the iron sulphate myself from Moss killer.

dissolve an equal weight of each in water, now I know that a mole of iron sulphate is a little heavier than a mole of the soda by about 10 grams, but we want the carbonate in excess and also to keep the method simple.

mix both solutions whilst stirring well, it will Instantly make a horrible gray/green "Mud" and thicken up a little too, this is normal, keep mixing

when its all mixed feel free to add more water and mix really well, leave it to stand now and youll see the "Mud" start to settle to the bottom leaving a murky liquid on the top, pour this liquid off carefully so as not to lose any "mud".

keep doing this at least 4 times, making sure you wash out as much of the soluble sodium sulphate as you can.

now you need to filter this "mud", a plain coffee filter is ideal for this, itll catch all the Iron Carbonate (Mud) that youv made and get rid of what should be just water by now.

keeping it in the filter paper put it somewhere to dry out, on a sheet of plastic out in the sun is fine.

when its dry it will crumble very easily and look just like Rust powder.

you Now have to heat this up very hot to decompose the carbonate, I used a crucible and bunsen burner:

the carbonate is on the left, in the crucible is now the Magnetite!

youll notice during heating that the Brown rusty carbonate will go Black during heating, this is normal, keep heating and keep the lid ON during this, dont allow too much or any Air to get in, if you do youll end up with an impure product.

let it cool naturally now (do try to make sure its cool before touching it!) itll take on a deep red to black color as shown (its a bit more red as I took the lid off to watch so I could give you more data).

a simple test with a magnet:

a little bit on the RED side, but Ill provide a further pic a bit later of the pure Black stuff.

yes, youll notice the magnet is in a plastic bag, how else would I get it off the magnet if the powder decided to cover it!

Have Fun!

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heres what it Should look like when youre not tempted to take the lid off during the reaction:

as you can see the stuff even sticks to the spatula that isnt even Magnetic, at least it Shouldnt be.

how it should look with the lid on, and an idea of the heat used:

but dont worry if you dont have a crucible, heres another method that works just as well!

you can use the lid off another tin can for a cover, but Do burn off all the plastic and paint coating 1st.

and for Completeness here are All the iron compounds featured and mentioned in this thread:

it gives a nice idea of Color.

Edited by YT2095
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Are you sure you didn't just make maghemite?

http://en.wikipedia.org/wiki/Maghemite

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FeCO3 is green. It oxidises very quickly in air to a godforsaken mixture of Fe(II) and Fe(III) carbonates/ oxides.

I think that you are getting some mixed oxidation state oxide but I doubt it's close to the stoichiometry for magnetite.

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Thats Interesting! and would explain why the Mud sludge when made is a green/gray, but when dry goes Brown.

it Does react completely with HCl giving off plenty of CO2 leaving a yellow soln behind and no PPT, my Fe2O3 does not, in fact its pretty inert to most acids (probably calcined).

although this: http://hyperphysics.phy-astr.gsu.edu/Hbase/Minerals/siderite.html in the top incarnation looks very much the same as my dried carbonate.

and yes the 1st try with the lid off is a good combination of both oxides, but the last one (the black gray powder), is indeed the magnetite, its insanely sensitive to even the mildest magnetic field as well, as demonstrated with the spatula.

the important thing to remember is that you MUST keep the lid ON during the heating and cooling, sneaking a peek will ruin it.

incidentally, the piles of powder on the paper got put into another crucible and quantity of carbon was added and mixed well.

it was then heated and cooled, and left behind a gray black powder as well, but there were also shiny crystaline bits in there too.

I guess the thing to do Now is to make some ferrofluid with it and test it out, just need to get some Oleic acid

Edited by YT2095
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OK, it starts as Fe(II); it gains some random ammount of oxidation as it dries, then you calcine it in the (near) absense of air.

How does it know to come out as exactly Fe3O4?

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thats a very good question, and one I dont have an exact answer for but can only hypothesise as to Why it works.

my idea goes like this:

since Fe2O3 is a a 70:30 ratio of iron to oxygen and Fe3O4 is a 72.3:27.6 ratio.

the the Fe3O4 is favoured in a reducing atmosphere, whereas the Fe2O3 would be in a Less reducing (or more Oxidising) atmosphere.

which would bear out my latter experiment of mixing all the oxides on that paper with carbon dust and reheating to leave a very magnetic black powder.

I predict that heating this again with the lid OFF will result in a Red powder of Fe2O3.

in fact my results do show this, in the 1st batch I made where I took the lid off to observe and ended up with a redish powder, but had the Black powder when I didnt take the lid off to peek, And the black powder is Intensely magnet sensitive whereas the redish attempt (peeking) is only marginal.

Also I can safely factor in that my Propane bunsen isnt anywhere near hot enough to effect either Fe2O3 or Fe3O4 directly with heat alone, but needs the chemical reduction/oxidation to make them change.

Also on a NASA site I read that iron carbonate will form magnetite on thermal decomp or high power mechanical shock (like an explosion or the likes).

Other than that, I really have no Exact idea of how or Why it works

====================================================================

after doing a little more research it seems that my Hypothesis is correct, you can quite easily reduce Fe2O3 to Fe3O4 using H2 and/or other organic substances at temps ranging 270c - 600c.

furthermore you can reverse this by Oxidation at similar temps.

and to test this, I have that pure Fe2O3 here that isnt at all magnetic (not even with a NIB magnet) and have mixed that with a little powdered carbon and heated that in a closed crucible.

result: Jet black highly magnetic Powder, as predicted

Edited by YT2095
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to get slightly off topic from the oxidation states, you said you needed oleic acid....

you can get the oleic acid here

http://www.hometrainingtools.com/product_categories/70/products/3005-oleic-acid-30-ml

and if you are really desperate, don't use vegetable oil, but you could use olive oil. olive oil has a higher concentration of oleic acid. it is of course not a pure source, i wonder the best way to break it down to its individual components...

the only problem that I had when I tried to make ferrofluid a while back was finding kerosene to suspend the magnetite olate (i think thats not the right name for it....), unfortunately they don't sell it where I live, and unfortuantely I don't have access to a fractionating distiller column

any other suggestions?

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Hmmm... that sounds easily doable if your REALLY pushed.

put Olive oil in the fridge, the Oleic acid will solidify, filter of the liquid portion.

saponify the remaining impure Oleic acid with NaOH to make the sodium salt (sodium Oleate), again filter this to remove water and glycerol.

then add HCl to leave the insoluble Higher purity Oleic acid.

but I think Ill just buy it, Im in no hurry anyway.

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Thats Interesting! and would explain why the Mud sludge when made is a green/gray, but when dry goes Brown.

it Does react completely with HCl giving off plenty of CO2 leaving a yellow soln behind and no PPT, my Fe2O3 does not, in fact its pretty inert to most acids (probably calcined).

although this: http://hyperphysics.phy-astr.gsu.edu/Hbase/Minerals/siderite.html in the top incarnation looks very much the same as my dried carbonate.

and yes the 1st try with the lid off is a good combination of both oxides, but the last one (the black gray powder), is indeed the magnetite, it`s insanely sensitive to even the mildest magnetic field as well, as demonstrated with the spatula.

the important thing to remember is that you MUST keep the lid ON during the heating and cooling, sneaking a peek will ruin it.

incidentally, the piles of powder on the paper got put into another crucible and quantity of carbon was added and mixed well.

it was then heated and cooled, and left behind a gray black powder as well, but there were also shiny crystaline bits in there too.

I guess the thing to do Now is to make some ferrofluid with it and test it out, just need to get some Oleic acid

this is all excellent experimentation and I have to commend you

However, I don't think you've totally understood the ferrofluid synthesis. the reason they synthesise the magnetite like that, in solution, is that they're trying to form a stable colloid, which won't precipitate (flocculate) over time.

If you take your powder, which I have no doubt is at least 80 or 90% magnetite, and make a sludge with some oil or other solvent, it'll be magnetic, and act a little bit like a ferrofluid, but when all is said and done it won't be a liquid, or a colloid. At best it will be a temporary suspension. None the less fun for it, though, I imagine.

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• 4 months later...

Supposedly modern synthetic engine oils have clever stuff to keep particulates in suspension, so possibly that might work nice as a ferrofluid like that. However, I don't know if the anti-oxidant additives etc will mess with it.

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