Abstract: The present invention provides a process for efficiently dephosphorizing, dephosphorizing and decarbonizing, or desulfurizing, dephosphorizing and decarbonizing a hot metal in a converter. The amount of flux to be charged and the amount of bottom-blown gas are adjusted so that the bottom-blowing agitation power and the CaO/SiO.sub.2 ratio subsequent to the treatment become at least 0.1 kW/ton and from 0.7 to 2.5, respectively and the hot metal temperature at the treatment end point becomes from 1,200.degree. to 1,450.degree. C. Furthermore, the operation of the process is controlled so that the sum of a T.Fe concentration and a MnO concentration in the slag subsequent to the treatment becomes from 10 to 35% by weight by adjusting the top-blown oxygen feed rate, the flow rate of bottom-blown gas or the top-blowing lance height.

Abstract: A method of adding a low-melting point metal (e.g. Pb or Bi) to liquid steel for producing a free-cutting steel in a consistent manner and in high yield of addition is disclosed. In accordance with the method, at least one member selected from said low-melting point metal and an oxide thereof, and at least one member selected from the group consisting of quick lime and a carbonaceous material are mixed in specified optimum proportions and the mixture is blown into the liquid steel through an injection lance. The liquid steel may be agitated while the mixture is added, and the appropriate conditions for the agitation of the steel are also specified.