Jump to content

Iron oxide reduction


chrismohr

Recommended Posts

Here are my general questions about rust: 1) The melting point of iron is around 2750 F. But at what temperature can small or nano-sized iron oxide flakes "melt" when they are released into the air? 2) When this happens, at approximately what temperature can iron oxide reduction to iron begin to take place? Are there relatively simple ways for to make iron oxide reduce to iron or does this happen only when the temperature exceeds 2750 F (iron's melting point)? 3) At what temperature can small or nano-sized rust flakes reduce to iron and turn into small spheres? Are iron-rich microspheres a byproduct of regular fires at under 2200 F or are they unique to super-hot fires above 2750 F? Thank you!

Link to comment
Share on other sites

1

Iron forms a number of oxides, the one you will get by heating it in air until it melts (Fe3O4 and/ or Fe2O3) will melt at about 1500 C

The melting point isn't strongly affected by particle size so it doesn't matter if it's nanoparticulate or not.

2

it doesn't.

As pointed out, you need a reducing agent and a lack of air.

You can do this below the melting point of iron.

In fact, you can do it in solution in water, but not easily.

3 in general, they won't reduce to the metal.

If the flame is hot enough, they will melt and become roughly spherical at about 1500C

 

It would help if you explained why you are asking.

Also, science uses C or K not F.

Link to comment
Share on other sites

  • 1 month later...

1) the Tm of Fe203 Haematite is 1838 K and for Fe3O4 Magnetite is 1867 K. The melting point of a substance is only dependant on the temperature not on the environment.

2) the reduction of Iron can take place in the presence of CO as it does in the blast furnace (800 - 1050oC) so the formation of iron micro spheres in the system could depend on the flue gas composition; as the formation of Iron would only happen with sufficient CO. Excess O2 would result in the oxidation of the iron formed back to Iron oxide

Link to comment
Share on other sites

I wouldn't be surprised if the "iron-rich microsphere" produced by fires were iron oxides mixed with other solids. These would still qualify as iron-rich.

 

But could we reduce iron oxides at heat in vacuum? Concentrated sunlight can make up to 5900K theoretically, and the top of an oxide heap needs no other mechanical support. That would cost vacuum but save coal - cleaner, probably not cheaper.

 

Or copper, nickel, cobalt, molybdenum, tin, lead, which seem easier.

Link to comment
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
×
×
  • Create New...

Important Information

We have placed cookies on your device to help make this website better. You can adjust your cookie settings, otherwise we'll assume you're okay to continue.