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Author: Subject: Iron Oxide for use in Thermite
raistlin
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smile.gif posted on 2-9-2002 at 15:14
Iron Oxide for use in Thermite


Im just curious as to how I can get a sufficient ammount of iron oxide for an experiment I want to do. I have tried a method that lets you make the iron oxde, but it takes far too long, and the yield isnt worth my time. Besides the fact that it takes so long, the quality isnt that great because I have noticed that there is also copper oxide in it? Any suggestions?

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Rhadon
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[*] posted on 2-9-2002 at 16:04


Well, it is by far easier to buy the iron oxide, but if you want to actually make it yourself, I'd suggest electrolysis with Fe electrodes.
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[*] posted on 2-9-2002 at 21:59
Buy it...


...from a ceramics supplier! Like I keep telling people, they're the best thing since sliced bread. You can also make it by electrolysis but this is tedious. Far faster is to try what I learned from my old Mr. Wizard book as a child: mix 1 volume of vinegar with 2 of liquid bleach and add steel wool. It stinks, and the oxide will need to be thoroughly rinsed with water (if you care at all about purity), but this is much faster/easier than electrolysis.
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[*] posted on 3-9-2002 at 13:26


If your looking for Fe2O3 thats easy. Go down to the local junk yard, or whatnot and find some old rusty p.o.s item and scrape the rust off it. Just grind it up in a ball mill, or with a mortar and pestle. Voila, rust. If its FeO, you would have to buy it. But for thermite Fe2O3 works just fine
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blazter
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[*] posted on 3-9-2002 at 18:50


if you obtain the iron oxide in the form of rust from scrap metal (old rusted water tanks are very good for this IMO) i've found you need to dehydrate it before using it for thermite. raw rust is hydrated iron oxide and this water will get in the way of the thermite reaction. in my own limited experience with thermite the rust needed to be heated strongly in a crucible to rid it of the water. even then my thermite rarely self-sustained the reaction and only formed a glob of slag in the pile of thermite. I figure it was the quality of the aluminum i had used which was tediously filed from a block of aluminum that prevented the reaction to continue on its own.
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raistlin
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[*] posted on 4-9-2002 at 10:46


If you can afford it blazter, I would consider buying a coffee grinder to powder your aluminum. Not only will it take less time, but the quality will be higher. (At least it should be...)

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Rhadon
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[*] posted on 4-9-2002 at 11:58


I'd prefer buying the aluminum from a painter's supply store. It is both very fine and quite cheap.
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[*] posted on 15-10-2002 at 02:20


Ceramic supplier. They have really nice fine mesh. There's black, red and brown iron oxide.

What the difference is I don't know, more complete oxidation for black, least for red I'd guess. Black might contain the most oxygen for the fuel-oxidizer mix?
A hotter burn.

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[*] posted on 18-11-2002 at 20:49


I get my iron oxide from electrolysis of iron nails. It is pain stakinly slow. Under NaCl solution and 6Volts of power it takes me 3 weeks just to make 100 grams. After i made the final product i wash it then filter, let it dry then bake it to a high temperature. After that I get Fe2O3.
But its a very slow process.




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[*] posted on 19-11-2002 at 07:08


TNT - that's a bit of a crap way of doing it. It's best to buy it but if you can't find any then this also works:
It's easy to find Iron (ii) sulphate at garden centers used for "acid loving plants" or some shit. Dissolve it in hot water and add some ammonia to it and filter the precipitate. Let this dry or cook it like I do and it will be easily oxidized by the oxygen in the air. You will then have very pure Fe2O3 powder.
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[*] posted on 27-1-2012 at 18:47


Here's how I make it:
-I dissolve nails or steel wool in concentrated hydrochloric acid (available in the paint section of your local hardware store).
-Once bubbles have stopped forming on the metal, I filter the solution to remove the undissolved metal.
-I mix this with an excess of Sodium Bicarbonate in water. The unspent acid is neutralized and Iron(II) Hydroxide and Carbon Dioxide are formed.
-I filter the precipitate and rinse it thoroughly with purified water.
-I let it air dry and the atmospheric oxygen oxidizes it to Iron(III) Oxide.
-I then heat it to dehydrate it.
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weiming1998
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[*] posted on 27-1-2012 at 18:58


What about using a soluble iron salt (like iron chloride/iron sulfate), put sodium or potassium hydroxide in it, filter, then heat the filtered off powder on a stove or with a torch. There's your fine iron oxide.
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Neil
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[*] posted on 27-1-2012 at 19:25


CO3 is bad if you are trying to run scientific thermites with Fe2O3. If you drop the iron with a carbonate you really need to decompose any iron carbonate.
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[*] posted on 27-1-2012 at 20:06


Quote: Originally posted by Neil  
CO3 is bad if you are trying to run scientific thermites with Fe2O3. If you drop the iron with a carbonate you really need to decompose any iron carbonate.


The (bi)carbonate decomposes to carbon dioxide and hydroxide ions, and the precipitate is heated, decomposing any remaining carbonate to the oxide. Also, the bicarbonate is cheaper and safer than sodium hydroxide.

[Edited on 1-28-2012 by ManBearSwine]
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weiming1998
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[*] posted on 27-1-2012 at 20:47


Wait, doesn't decomposition of iron carbonate form FeO instead of the classical orange iron oxide, Fe2O3? Would FeO work as well as Fe2O3 in a thermite reaction?
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[*] posted on 27-1-2012 at 21:19


An inexpensive route but you will have to experiment on small scale to test whether the process is capable of producing sufficient quantity for your needs. Procedure is:

1. Mix vinegar and Bleach to make Hypochlorous acid in a solution with Sodium acetate. Use excess of vinegar (Acetic acid) as the NaOCl can vary from 3% to 6% in strength. Reaction:

NaOCl + CH3COOH --> HOCl + NaCH3COO

2. Add Iron (solid sheet, scraps or filings). There will be some bubbling as dilute HOCl is capable of attacking iron. With time, the solution becomes reddish brown with a ferric salt (FeCl3 and some Ferric acetate).

3. Add a convenient base (NaOH or NH4OH) to precipitate Fe(OH)3. Filter, wash and dry to obtain Fe2O3.

To speed up the process (careful, the reaction can get out of control bubbling Chlorine), use HCl + H2O2 (creates concentrated Chlorine water) in place of the HOCl preparation as:

2 HCl + O2 ---Heat--> 2 HOCl

is one of HCl + H2O2 reaction products although with the decomposition of H2O2 releasing oxygen. Continue with Steps 2 and 3.

There are YouTube videos on the reaction of Iron and HCl/H2O2. The third metal shown here, for example, is Fe.

http://www.youtube.com/watch?feature=endscreen&NR=1&...

Good luck.
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weiming1998
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[*] posted on 27-1-2012 at 21:36


Quote: Originally posted by AJKOER  
An inexpensive route but you will have to experiment on small scale to test whether the process is capable of producing sufficient quantity for your needs. Procedure is:

1. Mix vinegar and Bleach to make Hypochlorous acid in a solution with Sodium acetate. Use excess of vinegar (Acetic acid) as the NaOCl can vary from 3% to 6% in strength. Reaction:

NaOCl + CH3COOH --> HOCl + NaCH3COO

2. Add Iron (solid sheet, scraps or filings). There will be some bubbling as dilute HOCl is capable of attacking iron. With time, the solution becomes reddish brown with a ferric salt (FeCl3 and some Ferric acetate).

3. Add a convenient base (NaOH or NH4OH) to precipitate Fe(OH)3. Filter, wash and dry to obtain Fe2O3.

To speed up the process (careful, the reaction can get out of control bubbling Chlorine), use HCl + H2O2 (creates concentrated Chlorine water) in place of the HOCl preparation as:

2 HCl + O2 ---Heat--> 2 HOCl

is one of HCl + H2O2 reaction products although with the decomposition of H2O2 releasing oxygen. Continue with Steps 2 and 3.

There are YouTube videos on the reaction of Iron and HCl/H2O2. The third metal shown here, for example, is Fe.

http://www.youtube.com/watch?feature=endscreen&NR=1&...

Good luck.



Why bleach and vinegar, then NaOH to precipate? Why not just buy FeSO4 and add NaOH? If you seriously lack chemicals, why not just heat up some vinegar/HCl with chunks of iron in it, then precipate with NaOH?


No offense, but all your chemistry reactions seems to involve either chlorine or hypochlorites. What's the fascination with hypochlorites?


[Edited on 28-1-2012 by weiming1998]
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AJKOER
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[*] posted on 28-1-2012 at 13:11


If this person more likely has large amount of FeSO4 available, I agree.

As Bleach is available in food stores, it is cheap and strong oxidizer, my 1st choice. Note, Bleach is not necessarily the oxidizer employed, it could be a derivative (like Chlorine water, HCl, Cl2, HOCl, Cl2O or even Ferrates). The Bleach/Acetic acid combination to HOCl is quite interesting as the Sodium acetate is an apparent catalyst in some instances. Also, storing HOCl does not work well decomposing into weak HCl and producing O2 gas, or worst some HClO3 with diffused light to add chlorates.

I also like H2O2/ferrous salt and percarbonates (H2O2 with the catalyst Na2CO3 plus heat).

I try to avoid storing strong acids around as I have kids into everything, and throwing things that can't open.

Also, it has gotten to the point in America where anybody having chemicals or glassware is presumed to be......and not a garage chemist. Having served on a jury many times, I can attest to the fact that jurists are complete bias idiots no matter what the facts presented, so that is yet another reason not to have stuff around.
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Neil
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[*] posted on 28-1-2012 at 14:24


Quote: Originally posted by AJKOER  
An inexpensive route but you will have to experiment on small scale to test whether the process is capable of producing sufficient quantity for your needs. Procedure is:

1. Mix vinegar and Bleach to make Hypochlorous acid in a solution with Sodium acetate. Use excess of vinegar (Acetic acid) as the NaOCl can vary from 3% to 6% in strength. Reaction:

NaOCl + CH3COOH --> HOCl + NaCH3COO

2. Add Iron (solid sheet, scraps or filings). There will be some bubbling as dilute HOCl is capable of attacking iron. With time, the solution becomes reddish brown with a ferric salt (FeCl3 and some Ferric acetate).

3. Add a convenient base (NaOH or NH4OH) to precipitate Fe(OH)3. Filter, wash and dry to obtain Fe2O3.

To speed up the process (careful, the reaction can get out of control bubbling Chlorine), use HCl + H2O2 (creates concentrated Chlorine water) in place of the HOCl preparation as:

2 HCl + O2 ---Heat--> 2 HOCl

is one of HCl + H2O2 reaction products although with the decomposition of H2O2 releasing oxygen. Continue with Steps 2 and 3.

There are YouTube videos on the reaction of Iron and HCl/H2O2. The third metal shown here, for example, is Fe.

http://www.youtube.com/watch?feature=endscreen&NR=1&...

Good luck.




DO SOME EXPERIMENTING.

This is 100% useless to produce large amounts of Iron oxide, try it you will see.


"An inexpensive route but you will have to experiment on small scale to test whether the process is capable of producing sufficient quantity for your needs. Procedure is:"

An inexpensive route that you will have to test to see if it is truly inexpensive or even useful?


There is no way that dissolving Iron with bleach will come close to being as cheap as buying it from a pottery supply store or Ebay.


Bleach is not cheap, the water in bleach is cheap but saying bleach is cheap is like saying acetic acid from vinegar is cheap. I have tried making large amounts of Fe2O3 this way, it is just a waste of resources.




@weiming: FeO is unstable and will happily convert to Fe2O3 given the chance. Pure powdered FeO is rumoured to be pyrophoric.

@ManBearSwine: Yes, Your right I'm sorry I did not realise that you were already heating to the needed degree.
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AJKOER
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[*] posted on 28-1-2012 at 16:53


Neil: Yes, I agree that the dilute HOCl may not be a fast or cheap path to make Fe2O3. With respect to yield, per my suggested testing, you may have come to realize you need a oil drum of bleach/vinegar (cleaning supply store may provide higher strength and larger containers). If this is possible for you, then scale is not an issue (cost perhaps).

To be honest, we have not really factored the cost of labor/time in making fine Fe powder (or not), and of converting FeO to Fe2O3 (if necessary). In fact, if we have fine Iron powder, just adding Bleach may work to form some FeO quickly, but it still has to be further air oxidized. The advantage of my method is that it does dehydrate to Fe2O3 directly, while even strong HCl forms FeCl2, which upon adding a base, leads to Fe(OH)2 (or FeO.H2O).

Now, HCl/H2O2 is much more costly but (see the video) a vigorous way to dissolve solid Iron. Still, I would conduct a test. Weigh my Fe and in 10 minutes, remove and re-weigh the Fe to estimate efficiency/feasibility. Note, the finer the Iron powder (hard work, I have tried filing and surrendered) the better this or any method.

As a matter of record, I have prepared Fe(OH)3 (not Fe2O3) per the dilute HOCl route. It formed an incredible voluminous precipitate and I can see why it is used in water purification. However, I would suspect, if I have dried it, a low yield of Fe2O3, hence my suggested testing.

[Edited on 29-1-2012 by AJKOER]
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weiming1998
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[*] posted on 28-1-2012 at 17:07


Actually, dilute acetic acid (vinegar) can actually attack iron pretty vigorously when heated! The iron acetate can then be precipated with NaOH or KOH. Or even precipation with Na2CO3/NaHCO3 (available as washing soda/baking soda), then heat. If FeO is unstable, then it probably will convert to Fe2O3 when cooled (some information suggests that FeO is stable at high temperatures.)

A low temperature simmer of some vinegar in an aluminum pot (I heard that vinegar doesn't attack aluminum because of passivation) with a few chunks of scrap iron, then precipation by OH-/CO3-2/HCO3- and heat should work cheaply and efficiently.

Heated HCl/NaHSO4 does the job better but it can't be contained in anything but a glass container/ The HCl fumes and droplets of NaHSO4 solution goes in the air and irritates people's noses and lungs.
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AJKOER
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[*] posted on 28-1-2012 at 18:14


Weiming1998: My source indicates that Fe(OH)2 rapidly converts in the presence of air via dark gray-green and black intermediates to Fe2O3.xH2O.

Note, Fe(OH)2 is soluble in acids, and also in hot concentrated NaOH to a slight extent forming hydroxoferrates(II), Na4[Fe(OH)6].

I would not use a carbonate to neutralize as insoluble FeCO3 could be formed. You want Fe(HCO3)2 which requires free CO2 in the water. Iron hydrogencarbonate in air forms Fe2O3.xH2O per my source.

Your info on Aluminum and vinegar is incorrect. Vinegar is reported to weaken the passivation of Al. This is a major concern to the Aluminum foil industry as having your food + vinegar in prolonged contact could result in Al leaching, a major public relations nightmare in light of increasing health concerns associated with Aluminum. I, myself, have pre-soaked Al in vinegar before dissolving in NH4OH (a little quicker).

Weiming1998 your method can similarly be attacked on scale/yield concerns. How big is your pot? (just joking)



[Edited on 29-1-2012 by AJKOER]
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weiming1998
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[*] posted on 28-1-2012 at 18:30


I haven't tried a pot yet, I use a glass beaker to contain the vinegar. So aluminum does get attacked by vinegar. Maybe cold HCl/NaHSO4 with Fe might work.. The reaction would be slow. The bleach/ vinegar mixture did yield rust (I tried that before), but I have to wait overnight (which an acid would have corroded the metal away) and the mixture smelt strongly of chlorine, even from a distance. But maybe that is a viable route to people that has a serious lack of chemicals, from regulations, or simply from having no access to various shops. But electrolysis of water by an iron nail is a very inefficient, slow, process. This process certainly doesn't require much chemicals, but costs a lot of electricity.
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Neil
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[*] posted on 28-1-2012 at 18:44


@AJKOER Just because something can be done - does not make it a good idea, a reasonable idea or a plausible synthesis.

Can you imagine how much fume you would be dealing with if you had a barrel full of bleach and vinegar fizzing away?

Can you imagine how much it would cost to buy that much bleach and vinegar?

Or how long it would take to filter the iron hydroxide sludge out of that much fluid?

Can you honestly suggest that a garbage can full of fizzing acid is a better idea then a beaker full of HCl digesting a bit of iron?

Really, Try things out.



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AJKOER
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[*] posted on 28-1-2012 at 18:55


OK, to be honest, the reaction of Al and vinegar is very slow (invisible). There is an inception period (meaning that nothing happens and then the reaction slowly commences). So don't change your process if the contact with Al is short-lived.

Using NaCl also is reported to cause pitting on Al metal and has been suggested as a primer in a Sciencemadness thread.
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