Synopsis : ProgressofhotmetaltreatmenttechnologyinJapanandscientificresearcheswhichsupportedthetechnologyareoutlined.To meet the increasingly severe customer requirements for steel properties, integrated steelmakers developed technologies for purifying moltensteel,centeringonthedividedrefiningprocess,consistingofhotmetaltreatment,BOFdecarburizationandsecondaryrefining.Thehot metaltreatmentprocesseswereputintopracticeatalmostallsteelworksinthe1980s. Sincethe1990s,allcompanieshaveimprovedandrestructuredthehotmetaltreatmentfacilities,aimingatnotonlyimprovementofrefining efficiencysoastoachieveahigherdegreeofpuritysteelwithhigherproductivityatlowercost,butalsoreductioninslagvolumewiththe environmentalproblemstakenintoconsideration.Thedirectionsinwhichhotmetaltreatmenttechnologyistobepursuedinthefuturearealsocommentedbriefly.