Abstract: A mold additive for use in the continuous casting is disclosed, which comprises a base material for slag having a chemical composition of CaO--SiO.sub.2 --Al.sub.2 O.sub.3 system, a flux and a carbonaceous aggregate. The mold additive contains 0.5-2.0% by weight of carbon black and 1-4% by weight of activated carbon with an average particle size of not more than 10 .mu.m as the carbonaceous aggregate, and has a bulk density of not more than 0.9 g/cm.sup.3.

Abstract: A method of stirring molten metal by repeatedly sucking and rapidly discharging part of the molten metal into and out of a refractory cylinder having a lower opening end immersed in the molten metal in a ladle, comprises operating the stirring under a condition that an inner diameter (d) of the refractory cylinder is less than 1,000 mm, a relation between the inner diameter (d, mm) of the refractory cylinder and weight (W, ton) of the molten metal in the ladle is d/W.sup.0.5 >30, and an immersed depth of the refractory cylinder is within 200-700 mm. A pressurized gas for discharging the sucked molten metal out of the cylinder is introduced thereinto in an inclined direction relative to a vertical line against a point on an opposite inner wall of the cylinder at least 500 mm above the maximum suction level of the molten metal in the cylinder.

Abstract: Wear of tuyeres for refining a molten iron is prevented by blowing a CO-containing gas having the defined flow amount, oxygen gas flow amount and CO gas concentration as a shrouding gas which surrounds a core refining gas flow containing oxygen gas through tuyeres of concentric pipes. As the shrouding gas for cooling and protecting the tuyeres, use may be made of an exhaust gas discharged and recovered from a converter or a blast furnace by controlling the concentrations of CO and N.sub.2 in the exhaust gas to the specific limitations.

Abstract: A method of refining molten metal with stirring in a refining vessel by repeated operation of suction and discharge is disclosed, wherein a lower end of a refractory cylinder is immersed into a molten metal bath in the vessel and an inside of the cylinder opposite to the immersed end is alternately subjected to evacuation and pressurization. In this method, maximum and average values of pressure reduction velocity to be applied to the inside of the cylinder are limited to not more than 1,000 mmHg/sec and not more than 500 mmHg/sec, respectively, and an evacuation time is extended over at least 1.5 times intrinsic oscillation period of up and down movement of molten metal column inside the cylinder.

Abstract: In a top-and-bottom blown converter having a plurality of tuyeres arranged at the bottom of converter housing, a monitoring sub-lance is vertically movable within a region defined beween vertical planes passing through parallel lines horizontally spaced a distance of 300 mm from a tuyere aligning line.

Abstract: In a method for cooling tuyeres when molten iron is refined by blowing a refining gas containing oxygen, and by setting tuyeres below or above the meniscus of iron bath in a vessel for refining the molten iron, wherein concentric tuyeres are used and a refining gas containing oxygen gas is blown through the inner pipe of the concentric tuyere and a fluid for protecting the tuyeres is blown through the outer pipe of the tuyere so that the protecting fluid surrounds the refining gas in a sheath form to cool the top ends of the tuyeres, the protecting fluid being a mixture of gaseous or liquid carbon dioxide and carbon fine particles.

Abstract: A desulfurizing agent for injection mainly consisting of lime powders having a particle diameter which allows at least 50 wt. % of the lime powders to pass through a screen mesh of 100 .mu.m and containing 0.015 to 1.0 wt. % of silicone oil surfactant, 10 to 40 wt. % of carbonate or hydroxide of alkaline earth metal, and 2 to 20 wt. % of carbon. The desulfurizing agent further contains 2 to 10 wt. % of at least one fluoride selected from the group consisting of fluoride of alkaline metal, fluoride of alkaline earth metal, cryolite, and sodium silicofluoride.

Abstract: Steel materials having an excellent hydrogen induced cracking resistance when used under atmosphere containing H.sub.2 S, which contain 0.05 to 0.20% of C, 0.01 to 0.50% of Si, 0.60 to 2.00% of Mn, 0.01 to 0.10% of Al, less than 0.0020% of S, Ca of 0.0020% to less than 0.0050%. These steel materials are increased in the tensile strength by additionally containing at least one of Cu, Ni, Cr, B, Mo, Nb, V, Zr and Ti. Furthermore the effect of addition of Ca is stabilized by adding rare-earth elements.

Abstract: A method of producing layer-like clad metal materials is disclosed. The layer-like clad metal material is produced by applying an organic substance consisting mainly of carbon and hydrogen to the surface of a metallic core material having at its surface substantially no oxide film to form a coating film having a thickness of 50-3,000 .mu.m, placing said core material in a casting mold, pouring a molten metal having the same or different composition around said core material into said mold by a bottom pouring process to form a clad metal ingot, subjecting said ingot to slab rolling or forging to form an intermediate product, and then subjecting said intermediate product to a hot working and, if necessary, a cold working.