I forget my chemistry, but I thought elements could only change permanently via nuclear means. In retrospect that seems totally wrong. Any help?
The iron reacts with oxygen to get iron(III) oxide (Fe2O3 - that's the rust). Fe2O3 (and other iron-containing ores) can be reacted to recover pure iron. Just based on a (faulty?) memory, I think it's called the Bessemer Process. So, no permanent change at all. And, yes, nuclear methods do permanently change the element's nucleus, changing it from one element into another.
The reaction that typically takes place when Iron rusts is. 4 Fe + 3O2 --- 2 Fe2O3 Iron is oxidized. You can then extract the pure iron back out through the Bessemer process, which is done by taking Carbon Monoxide and mixing it with the Iron Oxide, this reaction makes Pure iron, and Carbon Dioxide.
Iron is oxidized to various Iron(III) oxides (with varying amounts the elements of water in them (Fe2O3·nH2O). The iron nuclei are not changed. The iron can be recovered by reduction of the oxide. (For example, if rust were put into a blast furnace along with iron ore, it would be converted back to iron metal along with all the iron in the iron oxides in the ore.)
