Over the last 20 years, magnesium has developed as the material of choice for the desulphurisation of hot metal during the steel making process.
In the vast majority of cases, sulphur is an undesirable element in steel and is kept to the lowest level compatible with cost. The requirement for steel producers to meet more stringent structural and environmental specifications and the desire to improve yield and reduce internal rejections, particularly relevant since the universal application of continuous casting, has resulted in a continuous drive to reduce sulphur levels over the last 25 years.
Magnesium has a high chemical affinity for sulphur and unlike other desulphurising reagents, dissolves in the iron-carbon melt with the result that its reaction with sulphur is homogeneous. This determines the most favourable kinetic conditions of the interaction of magnesium with sulphur. In order to overcome the violent agitation of hot metal when introducing magnesium, various methods have been developed to retard the reaction. These technologies have been refined to give tightly controlled, low cost operations. Today, the realisable benefits of using magnesium reagents include:
- The most cost effective reagent when operated under optimum conditions.
- Environmentally friendly.
- Similar injection transport performance to other reagents, but without the need for co-injection.
- Low material volumes to handle.
- Low slag generation - slag produced is usually inert.
- Low iron losses in the slag.
- Final sulphur levels below 0.002% can be achieved.
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Worldwide, steel manufacturers have taken advantage of the benefits magnesium offers in this field of application and Magnesium Elektron has played an important role in the development and supply of a range of magnesium reagents based upon pure and alloy MELMAGŪ magnesium granules. Over the last 20 years, total worldwide market growth has run at a compound rate of over 15% per annum and further growth is forecast as the technologies developed are applied in new geographical areas.