Element Collection

Element Collection

Sunday, March 28, 2010

Experiment: Black Iron Oxide Thermite

Thermite is most commonly made with red iron oxide (hematite, or common rust), but I went with black iron oxide (magnetite) because it should yield more metal per reaction. The ratio for this is 3.22:1 Fe3O4:Al by weight.

Full reaction: 8Al + 3Fe3O4 -> 9Fe + 4Al2O3

This reaction is 40g total, and used my old aluminum powder which was much more coarse (100 mesh vs 425 mesh used in the manganese thermite in my previous post). Look at the size of this reaction compared that one, and that should give you a rough idea of the difference particle size makes. Both are the same total amount of thermite. Check out the last picture and you can clearly see a lump of iron metal sitting on top of the reaction products. There was a larger piece down in the middle of it, and I was able to recover about 7g of good pieces of solid iron for my element collection.


  1. is more or less energy released with black iron oxide compared with red??

  2. Little late here, but breaking down the chemical calculations on enthalpy change from www.amazingrust.com's Thermite section, we get the following:

    Red Iron Oxide - Total enthalpy change of -3.98 kJ per gram of mixture in a 2.96:1 ratio by weight.

    Black Iron Oxide - Total enthalpy change of -3.68 kJ per gram of mixture in a 3.22:1 ratio by weight.

    So, simply put - the Red Iron Oxide is a little better, since it burns a little bit hotter and requires a little less material to do so. When it comes to melting the frying pan, though, you probably wouldn't notice much of a difference.