S.m. Siadati, A. Monshi,
Volume 28, Issue 1 (6-2009)
Abstract
One of the main reasons for the blocking and sticking of the expendable layer in tundish plaster to the permanent layer and the subsequent increase in refractory consumption and associated costs is the use of low-melting phosphate binders. At high temperatures in continuous casting of steel, phosphate binders provide low-melting point melts which cause reactions between the two consuming and permanent layers, so that deskulling becomes difficult and the permanent layer is damaged. In this work, the using sulphate binders such as sulphamic acid and sulphates of aluminum, magnesium, ammonium, sodium, potassium, and calcium are studied as substitute binders. Some of the plaster properties manipulated by these different binders, namely cold crushing strength(CCS), Bulk Density (B.D), and Apparent Porosity (AP%), were measured according to ASTM. Studies by SEM and XRD showed that magnesium sulphate would be the best selection as a binder in tundish plaster. This binder provides strength at low temperatures, but dissociates to MgO and SO3 at high temperatures. SO3 evaporates and MgO is an oxide with a high melting point that does not react with the host oxide, usually MgO. No melting or reaction occurred and deskulling was easy without any damage to the permanent layer.
