Abstract: There is proposed a method for preliminary treatment of molten iron wherein heat source for dissolving scrap is ensured sufficiently to improve iron yield while decreasing phosphorus concentration efficiently by suppressing the amount of flux solvent used in the process of desiliconization, dephosphorization and decarburization. In the method for preliminary treatment of molten iron by conducting desiliconization and dephosphorization of molten iron with a converter type container, molten iron is first charged into the converter type container to conduct desiliconization and then intermediate slag removal is conducted, and subsequently a lime-based flux solvent is added to the container while blowing oxygen to conduct dephosphorization of the molten iron, and thereafter newly untreated molten iron is charged into the container to conduct desiliconization, and subsequently the above treatments are repeatedly conducted with the same container.

Abstract: There is proposed a method for preliminary treatment of molten iron wherein heat source for dissolving scrap is ensured sufficiently to improve iron yield while decreasing phosphorus concentration efficiently by suppressing the amount of flux solvent used in the process of desiliconization, dephosphorization and decarburization. In the method for preliminary treatment of molten iron by conducting desiliconization and dephosphorization of molten iron with a converter type container, molten iron is first charged into the converter type container to conduct desiliconization and then intermediate slag removal is conducted, and subsequently a lime-based flux solvent is added to the container while blowing oxygen to conduct dephosphorization of the molten iron, and thereafter newly untreated molten iron is charged into the container to conduct desiliconization, and subsequently the above treatments are repeatedly conducted with the same container.

Abstract: A filler for a ladle tap hole valve, characterized by comprising a sand and a feldspar to be externally added and mixed together so that the total quantity of alkalis in the filler is 0.3 to 1.5 mass %, the feldspar having a particle size distribution of 0.3 to 1.7 mm, the sand being composed of 40 to 100 mass % of silica sand having a particle size distribution of 0.3 to 1.7 mm and 60 to 0 mass % of chromite sand having a particle size distribution of 0.1 to 0.85 mm.

Abstract: A filler sand for a ladle tap hole valve contains 45 to 55 mass % of zircon sand, 30 to 40 mass % of chromite sand and 10 to 20 mass % of silica sand and is blended externally with 0.05 to 5 mass % of carbon black calculated based on the total amount of the sands; or contains 30 to 90 mass % of chromite sand and 10 to 70 mass % of silica sand and is optionally blended externally with 0.05 to 5 mass % of carbon black, wherein 95 mass % or more of the chromite sand consists of particles having diameters falling within a range of 150 to 850 &mgr;m, 60 mass % or more of the chromite sand consists of particles having diameters falling within a range of 212 to 600 &mgr;m, 95 mass % or more of the silica sand consists of particles having diameters falling within a range of 300 to 1180 &mgr;m, and 90 mass % or more of the silica sand consists of particles having diameters falling within a range of 600 to 1180 &mgr;m.

Abstract: A filler sand for a ladle tap hole valve contains 70 to 90 wt % of chromite sand and 10 to 30 wt % of silica sand and is blended externally with 0.05 to 5 wt % of carbon black calculated based on the total amount of the chromite sand and the silica sand; or contains 70 to 90 wt % of chromite sand and 10 to 30 wt % of silica sand, wherein the chromite sand has a particle diameter distribution such that 99% or more of the chromite sand consists of particles having diameters ranging from 150 to 850 &mgr;m and that 95% or more of the chromite sand consists of particles having diameters ranging from 200 to 600 &mgr;m, and the silica sand has a particle diameter distribution such that 95% or more of the silica sand consists of particles having diameters ranging from 150 to 850 &mgr;m and that 80% or more of the silica sand consists of particles having diameters ranging from 200 to 600 &mgr;m.

Abstract: A filler for a sliding gate containing 70 to 90 wt % of chromite sand and 10 to 30 wt % of silica sand in which the particle size distribution of the chromite sand is substantially from 500 to 1,000 .mu.m, which is not melted, sintered or penetrated by molten metal (molten steel) poured in a ladle in a steel works, and therefore is easily discharged to let the gate through.