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Rust can be turned into iron metal again

by Dr. Krishna Kumari Challa

Jul 9

Q: Iron rusts very easily. But can rust be turned into metallic iron again?

Krishna: 

Yes, rust can be turned into iron metal again. Rust is iron that has chemically bonded with oxygen. To turn it back into metal, you must remove the oxygen. This process is called reduction. 
Here is how the change works:
The Chemical Process of Rusting ....
When iron rusts, its atoms give away electrons to oxygen. To reverse this, the rust must regain electrons and strip away the oxygen. Simply melting rusted iron will not work because the oxygen stays attached to the metal. 
How to reverse it
There are two main ways to change rust back into iron:
High-Heat Smelting: Industrial furnaces mix rust with a reducing agent, like carbon (coke). When heated to over 1250°C, the carbon steals the oxygen from the rust. This leaves behind pure, liquid iron metal. 
Electrolysis: You can use electricity to remove the oxygen. By putting the rusty object in water mixed with baking soda (an electrolyte) and passing an electrical current through it, the reaction forces the rust to drop the oxygen. This reveals the solid, unoxidized metal base beneath. 
Real-World Applications of This Process
Iron ore, which is found naturally in the earth, is essentially rust. The process used to turn iron ore into usable metal is the exact same chemical reduction used to turn scrap rust into iron again.
Scientists are even testing large-scale "rust-to-iron" cycles. In these systems, iron powder is burned as a clean fuel. This creates rust, which is then transformed back into iron using renewable hydrogen gas.