iron from clay

Hi
I'm trying to get some iron out of the local earth (Washington, D.C.)
to make a little memento from my property.
I have lots of red clay from which I've extracted about 50 grams of
black iron oxide (or hydroxide) by using a rare-earth magnet.
Now I have to reduce the iron, either electrolytically or with carbon
and heat. I have an oxyacetylene torch and an arc welder.
Here are some of my questions:
If I try this electrolytically, is HCl a good way to put the oxide in
solution, or is there something better?
What kind of electrodes can the iron be stripped from?
Once I get the iron reduced, what ways are there to melt
small amounts of it? Are small induction furnaces available
for iron or steel?
Thanks for any help in the effort.
Bob
Reply to
Bob
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In principle if you got the oxide really hot, charcoal would reduce it handily and lime(stone) would float gangue to remove impurites and prevent surface oxidation. Blow oxygen through at the end to adjust carbon level. The iron/steel would be obtained directly as a liquid as in the Bessemer process - an incredible mess downwind.
If you went way heavy on the charcoal and started with clean iron oxide, no limestone, you might get wootz. Add maybe 50 ppm vanadium at the start (ashes from sea cucumber/sea squirt or tunicates in general - blood colored from tunichrome), heavily work the metal at barely dull red heat, and get Damascus steel. Borate flux would ease surface oxidation.
Reply to
Uncle Al
People who've tried electrolytic derusting, uniformly enthuse about the process.
You would too, I expect.
Take a battery charger - preferably with a 6 volt switch. Connect a stainless plate to the negative terminal, and place the oxide ore on it.
Connect a stainless plate or a lead one to the positive terminal and check that the oxide bubbles when the solution is made conductive with baking soda. Leave the thing to bubble for 12 hours or so.
As you can see, it is the mirror image of anodizing aluminum - where the oxide forms on the anode (+) plate.
But for small particles of oxide, there is a much, much faster process: Thermite. Powder the iron oxide. Mix with as much aluminum powder in a ceramic vessel. Light the mixture with a 'sparkler" It has to be glowing white hot to light the powder. The molten iron will run out after the fireworks subside.
Brian Whatcott Altus OK
Reply to
Brian Whatcott
I'm very impressed that someone posted this - exactly what I was about to suggest.
If the iron content was high enough, you could just mix up some thermit and reduce it with aluminum pwd. But there is probably so much Si and Ca in the clay that this might not work very well is you used stright clay. However, you say you have some good oxide, so thermit would certainly work. Might be able to get it going with the arc welder. Could probably use aluminum foil instead of pwd if need be.
Or you could grind up the whole mess about 1/2 oxide and 1/2 coke(or coal), and add it to a nice hot coal/coke fire. Typically you would need to perform this combustion insulated by some type of refractory material. Your cheapest route is to make a paste from silica sand and sodium silicate, or if you can get your hands on some alumina rich clay !
If you are really game for something new, get yourself a huge lens and melt the oxide. Then turn on your fuel gas with >no< oxygen. Blow the fuel-gas on the hot oxide, and the carbon from the acetylene will reduce the oxygen from the Fe2O3 and you'll have pure Fe. Pretty sure carbon has a higher affinity for O2 than Fe does. Should work. Whatever the case - you need some refractories.
Reply to
Lefty
You have pulled out some of the black oxide, Fe3O4. This stuff is heavy so 50gr ain't much. If the clay is red, you've left most of the iron in it. Maybe as much as 10% of the clay is Fe2O3, the stuff that makes the clay red. I think you can extract this with hot sulfuric acid to make ferrous sulphate. That you can purify to green crystals by by evaporating then re-disolving in clean water. Do several times. Once the crystals are clean, heat them to about 800 degC (red heat) to convert them to nearly pure Fe2O3. Do this until you have several pounds of pure oxide. That you can reduce to iron in a small furnace or forge with charcoal or coke. Use Borax as a flux and make the fire white hot with an air blow. You should be able to get a hunk of impure iron that you can pound out to a nice half pound slug. Do not expect to melt the iron. The furnace will not produce a hot enough fire but it will be hot enough to reduce the oxide and pound the metal. Good luck. Bob
Reply to
Bob Eldred
Take a big chunk of graphite and carve out a bowl shaped concave trough on the top side.
Connect the arc welder leads securely on opposite ends of the graphite block, and put your oxide in the bowl.
Put this thing under a vacuum, argon, or reducing gas, and hit it with 500 amps for 35 minutes, or just cook to taste.
Graphite reduces Fe2O3, and you get relatively pure iron. Might even wind up with steel if you do it this way.
Reply to
Lefty
only one thing to add: a microwave oven makes a good furnace for small work, and can can be used to both reduce and melt the metal. Google microwave foundry.
NT
Reply to
bigcat
[snip]
Indeed, this is not something to be tried indoors. Also, you want to think fairly carefully about how to contain this sucker. It gets foolishly hot. Socks
Reply to
Puppet_Sock
Thanks, Lefty. I've got this stuff (Fe2O3, I presume) pretty pure, I think, just by using a magnet to separate it from silica etc in a thin plastic dish of water. (It's amazing how easy it is, with a magnet, to get the iron out of the local clay.)
I'll try the thermite route, and, separately (of course), the reduction in charcoal, as per Uncle Al's suggestion.
Yesterday, I put some of the (presumed) oxide on a piece of wood an irradiated it with an arc between to carbon electrodes. Afterwards I dug around in the burned wood and found some small pieces of iron, which I verified as metallic by hammering them out.
Thanks for the suggestions.
Bob
Reply to
Bob
I've tried a graphite crucible several times with the arc, and using a graphite rod. The crucible might be too deep (about 10 cm), and I've 'flooded' the crucible with CO2, of which I have a cylinder. The arc, inside the crucible, fans out to all sides of the crucible, which is interesting in itself. I will try again, with inert gas. I would like to end up with steel.
Bob
Reply to
Bob
I hadn't thought of using hot sulphuric acid on the clay directly. I previously used HCl, which I neutralized with NaOH to produce a brown cake which was unmagnetic till after I heated it to red heat for a while. The resultant black stuff (which was magnetic) didn't however work well in the thermite method; i.e., I got nothing except magnetic chunks of alumina and god knows what else.
Neat suggestion, though. Gonna try this method too.
Thanks, Bob
Bob
Reply to
Bob
You're kidding! A home microwave oven can do that? Jeez, the woman will scream if I wreck the microwave, but I guess that's the price of knowledge . . .
Bob
Reply to
Bob
If you're going down the memento path, you might consider trying to do it in a traditional way. One of your local institutions (e.g. the library at Colonial Williamsburg) can probably tell you what the historical method would have been
Reply to
Michael
I'd go the thermite route to recover clean metal with minimum hassle, then maybe play with Damascus steel after reading up on it. The need for about 50 ppm vanadium in true Damascus steel to segregate dendritic phases is a fairly recent discovery. Pattern welding per se is very old. If you wish to do good job with high carbon and low carbon steel preforms you must interpose a thin shim barrier of silicon steel (e.g., jackammer bit) to stop carbon diffusion at the interface.
Doing it takes a lot of work. Doing it well requires a lot of knowledge and experience, too. Measure twice, cut once.
Reply to
Uncle Al
No need to wreck it, its only if you spill the stuff there will be trouble. It may melt the glass turntable, the steel floor, the table the microwave stands on, the floor, ceiling, carpet and floor below, and cool down in the soil below the house. So try and take care :)
NT
Reply to
bigcat
Well give it a try. Unfortunately hot acid may remove other substances from the clay that could interfere with the process or require more sophisticated separation of the solutes.
A simpler idea is to give up on iron and make a vessel, coffee cup or somthing from the clay and fire it into a ceramic momento. It's much easier to do and more likely to be successful, plus you can make something useful.
The problem with the thermite method is that it requires relatively pure oxide plus it is a bitch to get going. Oxide made from ferrous sulphate can be very pure if done right. It should work in the thermite method.
If your HCl results were magnetic they had iron in them or one or more of its oxides. Alumina is not magnetic.
My above suggestion, reducing with carbon in a forge then pounding the metal removes much of the slag and inclusions that will always be in iron made that way. That's the way iron was made before the 19th century and the blast furnace. Fires were not hot enough to melt it but the pounding and working squeezed out the non-metalic crud and welded the resultant metal to a cohesive hunk. They called it "wrought" iron and was a common product before the age of steel. Bob
Reply to
Bob Eldred

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