Deoxidization is a method used in metallurgy to remove the rest of oxygen content from previously reduced iron ore during steel manufacturing.
Deoxidation is important in the steelmaking process as oxygen is often detrimental to the quality of steel produced.
For example, iron will transfer two of its electrons to oxygen, forming an oxide.
Oxygen forms oxides with the unwanted elements, such as carbon, silicon, phosphorus, and manganese, which appear from various stages of the manufacturing process.
These oxides will float to the top of the steel pool and remove themselves from the pig iron.
Due to the high temperatures involved in smelting, oxygen in the air may dissolve into the molten iron while it is being poured.
Some processes, while still able to lead to oxidation, are not relevant to the oxygen content of steel during its manufacture.
Some physical components of the steelmaking process itself, such as the electric arc furnace, may also wear down and oxidize.
This problem is typically dealt with by the use of refractory metals, which resist environmental conditions.
[1] If steel is not properly deoxidized, it will have lost various properties such as tensile strength, ductility, toughness, weldability, polishability, and machinability.
[2] This method of deoxidization involves adding specific metals into the steel.
These metals will react with the unwanted oxygen, forming a strong oxide that, compared to pure oxygen, will reduce the steel's strength and qualities by a lesser amount.
where AD and BD are parameters specific to different deoxidizers and T is the temperature in K°.
CO gas will float up to the top of the liquid steel and be removed by a vacuum system.
the reaction between carbon and oxygen is represented by the following chemical equilibrium equation:
where PCO is the partial pressure of the carbon monoxide formed.
Decreasing the oxygen activity(aO) will result in a higher equilibrium constant, thus more product, CO. To achieve this, subjecting the pool of steel to vacuum treatment decreases the value of PCO, allowing for more CO gas to be produced.
Afterwards, oxygen will diffuse from the steel into the lesser concentrated slag.