Abstract
	The aim of presented work was to study the progress of steel cleanliness during ladle furnace steel treatment at  Podbrezová Steelworks. The steel cleanness was characterised by amount,  composition and shape of non-metallic inclusions in steel. The steel and slag samples were taken in following technological steps: after addition of Al wire into steel in ladle; before addition of CaSi into steel in ladle; after addition of CaSi and Ar stirring in ladle; from tundish. After deoxidation of steel in ladle(preliminary and final) three types of inclusions were found: silicates with variable contents of other oxides ( CaO, FeO, MnO, Al2O3); Al2O3  inclusions, result of deoxidation process; and FeMnS based sulphides. After modification of Al2O3  inclusions by Ca globular calcium aluminates resulted. They also contained the surface layer of CaS. Calcium aluminate and silicate inclusions were removed from molten steel into slag, this process was supported by Ar bubbling. Finaly, high cleanliness in tundish was confirmed, improving of steel cleanliness was observed.