Recyclate-containing magnesia-carbon refractories - Influence on the non-metallic inclusions in steel

The fabrication of MgO-C refractories containing MgO-C recyclates is a current approach for saving resources and energy. However, it must be ensured that the steel quality is not adversely affected, particularly with regard to non-metallic inclusions. The present study investigates MgO-C refractories containing different proportions of MgO-C recyclates (up to 83%) in contact with 16MnCr5 steel melt and a slag. A recyclate-free MgO-C material served as a reference. The tests were performed in a steel-casting simulator. By an automated feature analysis of the solidified steel, manganese sulfide and complex alumina-manganese sulfide inclusions were found to be the predominant ones in all steel samples. No negative influence of the recyclate on the inclusion count and the size distribution of the inclusions, the latter being determined for the sum of alumina and alumina-manganese sulfide as well as for the manganese sulfide inclusions, was observed.