Refining:

Refining operations traditionally in the electric arc furnace have involved the elimination of, sulphur, aluminum, phosphorus, silicon, manganese and carbon from the steel. In current times, dissolved gases, especially nitrogen and hydrogen, have been recognized as a concern. Refining operations traditionally were carried out following meltdown that is, once a flat bath was attained. These refining reactions are all of dependent on the accessibility of oxygen. Oxygen was lanced at the ending of meltdown to lower the bath carbon content to the wished level for tapping. Most compounds that are to be removed throughout refining have a higher affinity for oxygen than the carbon. Therefore the oxygen will preferentially react along these elements to form oxides that float out of the steel and into the slag.

In modern EAF operations, especially those operating along a "hot heel" of molten steel & slag retained through the prior heat, oxygen might be blown into the bath during most of the heat. As a consequence, some of the melting and refining operations take place simultaneously.

Normally Sulphur and Phosphorus take place in the furnace charge in higher concentrations than are permitted generally in steel and might be removed. Unluckily the conditions favourable for eliminating phosphorus are the opposite of those promoting the elimination of sulphur. Usually Phosphorus elimination is carried out as early as possible in the heat. Hot heel practice is extremely beneficial for phosphorus elimination because oxygen might be lanced into the bath while its temperature is rather low. Early in the heat the slag shall contain high FeO levels carried over from the earlier heat therefore aiding in phosphorus elimination. High slag basicity (that means high lime content) is also beneficial for phosphorus elimination but care have to be taken not to saturate the slag along lime. This shall lead to a raise in slag viscosity that shall make the slag less influence. Sometimes fluorspar is added to help fluidize the slag. Stirring the bath along inert gas as argon is also beneficial because it renews the slag/metal interface therefore improving the reaction kinetics.