5Carlsson G, Bramming M,Wheeler C. Top slag and gas purging-a low-budget method for desulfurizing steel in the ladle [J]. Iron & Steelrnaker,1987,14(2):31-34.
7Hatakeyama T, Mizukami Y, Iga K,et al. Development of a new secondary refining process using an RH vacuum degasser [J]. Iron & Steelmaker , 1989,16(7) :23-29.