Abstract: The process and application of 260 t converter steelmaking with limestone partial replacement lime were researched in Handan Iron and Steel Company，Hebei Iron and Steel Group Co.，Ltd. The temperature of molten iron which meet the limestone calcinations requirements, lime melting mechanism of slag formation, limestone decomposition mechanism of melting slag, limestone cooling effect and reasonable addition were analyzed. The research showed that limestone could partly replace lime, steelmaking production tests with limestone instead of part lime slag forming were carried out.The results showed that when limestone average addition 3.5~3.8t per furnace, the dephosphorization rate of plain carbon steel and low carbon steel increased respectively from 84.8% and 89.1% to 87%, 90.1%, consumption of lime respectively reduced from 10.3, 10.2t per furnace to 8.4, 8.5t per furnace, gas recovery reached 150m3/t, the cost decreased more than 2 yuan/t.

Key words: limdstone, steelmaking, lime, dephosphorization rate, slagging