Abstract: A new seamless pure calcium wire was boldly used to replace solid core pure calcium wire in 120 t LF of Masteel, in order to solve the problems of unstable yield and serious slag spattering in calcium treatment. It was found that the melting time of the new calcium wire could be prolonged and penetrated into the depth of molten steel due to the coating of nano-silica powder as the intermediate layer through theoretical exploration, and the theoretical feeding speed of the new calcium wire was 1.65 m/s through theoretical calculation. It was found that the highest yield of the new calcium wire was 34.6 % when the feeding speed was 1.5 m/s, while the average yield of the original calcium wire was only 20.7 % through field tests. And the large size inclusions could be greatly reduced and the CaO-Al2O3 composite inclusions could be transformed into C12A7 with low melting point by feeding new calcium wire into molten steel, which could better guarantee the pourability of molten steel.

Key words: calcium treatment, calcium wire, yield;inclusion denaturation