Casting Iron Using Aluminothermic Reaction




About: I would have to admit to having a creative and inquisitive nature, my mind is never really at rest. In 2000 I built my first High Voltage Device (Dimmer SW Ignition Coil / Then A Solid State Tesla Coil - My...


This project is both fun and gives some basic insight into metallergy & Basic Chemistry. This experiment should be carried out by Persons with some basic knowledge of chemistry and should not be attempted in anyway by inexperienced [Under Aged] Persons without adult supervision as in the wrong hands this is dangerous..............

Please be aware I am not responsible for the actions of the Irresponsible PROCEED WITH CAUTION !!!!!!!!!!!

This process is very well known and was discovered by a German Chemist Called Hans Goldschmidt ****[Please Google Him.......]****

It is basically an Exothermic reaction that involves >An Oxidised Metal & A Reducing Metal-----When Used in the right proportions the Oxidised Metal Is Reduced By the Reducing Metal Which In Turn Becomes Oxidised............The Oxygen swaps from one metal to the other >>>>>I will explain why this works later on in this Instructable....<<<<<<.

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Step 1: Materials

Lets Begin:-If you view my, Previous Instructable MAKING IRON OXIDE A DIFFERENT WAY You can make one of the main materials for this project: There are also sources for making the aluminium which is possible but an expensive mill is necessary and more time. There are plenty of sites for buying both at Ebay & Amazon.

Using my (Fe2O3) you will need at least 80gms of finely powedered Iron Oxide. and 26gms of [Finely Powdered (Al) 250Micron].

You will need a metal container any EMPTY steel WD40 or Small MIG gas bottle [EMPTY] and clean//// I used wheel bearing cases of different sizes and made a stack. Steel Plate A4 Size [210x297] X 19mm - (1) tissue role or 2" thick cardboard tube.

Starter Mix: Magnesium Chunk /Powder ---Potassium Permangante & Glycerine

You will Need a Refractory Material Like [SIO2] Sand Clean [wash several times and DRY!] or AL2O3

Safety Gear : Goggles /Gloves /Apron /Boots /Foam Fire Hydrant / bucket Of Water VENTILATION or do [OUTSIDE]

Tongs & Hammer.

2 Breaze Blocks or bricks.

Step 2: Proceedure

Taking Your Steel Plate

Place on top of your breaze block or 2 bricks - if this is to be done inside a garage or a blacksmith type area - all fire regulations and safety precautions must be followed carefully - especially ventilation.....

If to be done outside make sure it is set away from combustibles and a walk way route is possible.

Iron Mix :Take a small Zip lock bag - Pour in The 80gms of Iron Oxide and 26gms of Al Powder and put inside bag. Now Seal and mix by rubbing between fingers lightly until you have a grey powder.

Take your steel vessel / can - line with about 15mm of Sand or Aluminium oxide . Using a cardboard tube like a tissue role place in the centre of the can. A ( 15mm) gap should be observed outside the cardboard tube. Now infill this gap with refractory material. Holding the tube Fill with Iron mixture and gently tamp down. Both Refractory and Iron mix should be level - it does not matter if the iron mix is lower.

Step 3: Procedure [Part 2]

***********Safety gear should be worn throughout and caution is paramount ***********

Fire mix : Now make a small dimple in the middle of your mix and place a pinch of magnesium fines, in a small pile.

Put a small dimple in the middle of this again - now place a pinch of KMn04 using a piece of paper with a crease pour into dimple.

Now this is the important part, depending on humidity/ temperature and purity of these materials - the reaction may proceed slowly or reasonable quick, after a small drop of glycerin has been added on top of the Permanganate. You now have 30 / 45 seconds to move a safe distance away.....

Sometimes there may be no reaction at all - if this happens then use a long hot wire and touch the mix to introduce the necessary activation energy. The auto-ignition of the [Fire Mix] then provides the heat necessary to ignite the main charge of ferro-aluminium mix and reduction will then take place.

*******Please retire to a safe distance!!!!!!! ******
Until reaction has finished .....If ignition fails attempt again after 5 mins...

Step 4: Beware!!! Bright Light & Heat

The chemistry <<<<< what is taking place>>>>>> Is and Exothermic reaction> A massive amount of energy in the form heat and light is given out. This occurs because the energy released by the Reactants is greater then the energy of the Products. Bonds are broken and re-formed=Electrons are given & taken.....

This kind of reaction is also known as a REDOX reaction/// what is happening is, when Oxygen bonds to Iron Fe- The iron becomes Oxidised Fe III +3 because O2 Oxygen is electronegative -2 and steals Fe's electrons.

When we react Al powder with our Oxidised Iron [Fe2O3] - Something Weird happens......Because Al is an electro-positive +3 potential, it gives back or Donates it's electrons. So Fe III + 3e can now become Fe . In the process Al becomes oxidised because it loses its electrons Al is now, Al III +3 or (Al2O3) in the complete sense.

It is this electron transference which causes the heat See: (Bond Enthalpy) / (Activation Energy ) Wiki Pedia........Google most of the key words it may help you understand basic terminology ....

Step 5: Let Cool for 30mins Then Remove Shell

Image (1) is 10mins after the reaction has ceased- you will need to walk away and leave to cool for 30mins more.

Image (2-3) remove casting cylinder and big chunk should be visible.

Image (4-5) using tongs turn chunk on it's side tap with a hammer with reasonable force to crack shell -(Think Walnut).

Now our shiny nugget of iron is revealed.....

Well done if yours is perfect - mine has a puddle beneath ;))

Conclusion: The product can make an excellent craft piece. I have made several larger pieces they can be used as an office paper weight /a pen base-stand or a collection piece for a collector of elements.....

Please Enjoy - Be careful - and feedback would be most appreciated Inspecter Gadget.............

Step 6: A Movie :)

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    36 Discussions


    3 years ago

    Codyslab on youtube did a silver refining using a similar reaction, and he wanted to slow the reaction down for a better product. Slowing the reaction down with adulterants like borax may yield a more usable less violent product.

    1 reply
    inspecter gadgetMakerIan

    Reply 3 years ago

    If you vary the grain size of the reactants you can also slow down the redox process - either way it is pretty Exothermic - funny enough (just as a side note) I did a Blacksmithing course last weekend and I tried to forge one of my 350 gm nuggets.....I got it bright yellow and it was still as hard as Flint but I managed to shape it. Iron is supposed to be ductile when super hot. This is good metal.....


    3 years ago

    So this is basically Termite! Ive seen workers welding train rails with that

    1 reply
    techno guy

    3 years ago

    This is pretty cool, I thought your little ingot looked like a space rock :)

    1 reply
    inspecter gadgettechno guy

    Reply 3 years ago

    Yes indeed I like them for that reason -Tesla would have enjoyed the instructables web site it kind of celebrates everything that he stood for - peace in our time would have been a bonus too ;)


    3 years ago on Introduction

    Since no casting of any object was done here, I think you need to change your instructable title. It was a real let down finding out that no useful objects were created.

    3 replies

    Please define Casting! - I have demonstrated the Pre Casting of an
    object - I used a mould to hold a material [Pre-cast] then I converted
    the material-cast into an object---You can use this material In a Plant
    Pot And Place above a casting frame, when the reaction takes place the
    molten material falls into Sprue [Pouring Hole] and Voila..... Define
    Hand-Stand, A person Standing On his/her Hands Or A Stand in the shape of a

    If your objective is to only produce ill-shaped lumps of iron with horrendous porosity then I indeed think your method is a complete success. I could not find any examples of anyone using thermite for casting because it think it is too hard to control for casting detailed non-porous objects. If you can produce a detailed non-porous fly wheel like the one in the following youtube video using thermite than I will be greatly impressed:

    inspecter gadgetwyldbyl

    Reply 3 years ago

    Many thanks for your youtube video - very
    enjoyable, not the first I may add. Apologies for the anticlimax - I was
    just putting an idea out there:-) - It would be possible to make non
    porous castings with thermite if the materials and casting methods were
    refined the only problem I have found is avoiding slag inclusion from
    time to time. I also made all reactants from scrap metal




    3 years ago on Introduction

    One of my favorite reactions of all time! There is a nice YouTube channel called ExplosionsAndFire - those guys seems to have virtually created "The Periodic Table of Thermite" - in other words they use loads of different metal oxides - very interesting and cool.

    If it is Fe2O3 You, Take your Starting weight. R.A.M. is (Fe) 55.85[x2]+(O)x3[48]

    111.7/159.7=69.9% So Multiply the starting weight of your Iron Oxide by .69 and you will have your weight.--For Magnetite Fe3o4 167/231=72% Multiply by .72


    3 years ago

    that's a very good and detailed instructable on mixing, setting off, and understanding thermite, but I was hoping you'd have instructions more so how to harness the process to actually cast items.

    5 replies

    If you make your mold with Green Sand and OR Fine AL203 and Have [2] Pouring Sprues You can Hover a Plant Pot Above Pouring Point and Cast this Metal. hope that helps


    Thanks for the infra red reminder. A lot of folk in glass and blast furnace work ended up with cataracts.

    I have to say, that in earlier years, I tinkered with many concoctions when the local chemist used to hand the ingredients over without too many questions.

    For spectacular displays, try nitrogen tri-iodide (touch sensitive) or magnesium powder and silver nitrate (water sensitive) - all the usual disclaimers apply - the latter one burnt a large hole in my mate's parents's antique table - both mixes are highly unstable.

    ARKtestinspecter gadget

    Reply 3 years ago

    I'll have to try that. I've been meaning to use my forge to melt down some Al and make some castings. we'll have to see.

    spark masterARKtest

    Reply 3 years ago on Introduction

    add the right amount of iron oxide to melted aluminum and it will be instant thermite.....the aluminum melt, the ironoxide goes ointo solution the o2 bins to the aluminum, and the reult is molten iron.

    have fun , beware of explosions and instant death and burning down the neighborhood, atracting a police presance!!