Hot metal is treated by de-S or de-P process at pretreatment station first then transported to BOF for oxygen blowing, and after tapping to ladle, liquid steel is further refined at LI (ladle Injection), RH (vacuum treatment) , VOD or STN (stirring station); refined liquid steel then sent to SCC or BCC for casting to slab or bloom semi-product, finally this semi-product is inspected or grinded, or scarfed to remove surface defects, then shifted to downstream for rolling.