Abstract: The invention provides a remediation method of soil, water and/or gases by prompt dehalogenation of halogenated hydrocarbons by allowing the halogenated hydrocarbons contained at least in one of the soil, water and/or gases to contact an iron powder containing about 0.03 to about 2% by mass of sulfur preferably on the surface, and an iron powder for use in the remediation method.

Abstract: A method for rendering halogenated hydrocarbons harmless, in which the halogenated hydrocarbons in at least one of polluted media, soil, water (groundwater, etc.), and gas are rapidly dehalogenated by the contact with an iron powder carrying an inorganic compound having an electric resistivity of about 1×10−4 &OHgr;·m or less on the surface thereof, is provided. The iron powder for environmental remediation includes an inorganic compound having an electric resistivity of about 1×10−4 &OHgr;·m or less on the surface thereof is also provided.

Abstract: The invention provides a remediation method of soil, water and/or gases by prompt dehalogenation of halogenated hydrocarbons by allowing the halogenated hydrocarbons contained at least in one of the soil, water and/or gases to contact an iron powder containing about 0.03 to about 2% by mass of sulfur preferably on the surface, and an iron powder for use in the remediation method.

Abstract: Process and apparatus for refining silicon by treatment in a graphite vessel with irradiation with an electron beam while removing impurity elements by evaporation. A single graphite vessel is used, or plural graphite vessels are arranged in sequence. During treatment in successive graphite vessels, molten silicon is poured in succession from one vessel to another. Use of graphite vessels improves heat efficiency, prevents contamination and produces refined silicon containing very low contents of impurities.

Abstract: Method for producing highly purified silicon for use in solar cells by a single solidification purification, pouring silicon into a mold and gradually fractionally solidifying it while solidifying the liquid surface, followed by purifying the solidified silicon by zone melting or continuous casting using an electromagnetic mold, or by zone melting in combination with continuous casting, and optionally causing directional solidification to concentrate impurities, leaching and recycling.

Abstract: An object of the present invention is to provide a process and apparatus for the continuous flow production of polycrystalline silicon from metallic silicon or silicon oxide as a raw material and also for the manufacture of a wafer by using it, which process and apparatus permit the mass production at a low cost.

Abstract: In a method of producing a molten aluminum-killed steel for forming a thin steel sheet, molten steel tapped from a converter is decarburized to a predetermined carbon concentration by using a vacuum degasser, and Al is added to the molten steel in the vacuum degasser to deoxidize the molten steel. A material containing metallic Ca is then added to the molten steel to produce a Ca content of about 0.0005 to 0.005 wt %, and to satisfy [%Ca].times.[%S].ltoreq. about 2.times.1 0.sup.-5. Thereafter, degassing is performed on the molten steel.

Abstract: A method of manufacturing steel having Ca including the steps of adding Ca metal or alloy containing Ca to molten steel in a ladle that has been killed by adding a reducing agent, such as Al, to the molten steel in a predetermined quantity when or after the molten steel has been discharged from a converter, subjecting the molten steel to a vacuum degasification process, and supplying the molten steel to a mold through a tundish so that the molten steel is continuously cast, wherein Ca metal or alloy containing Ca is added to the molten steel in the tundish.

Abstract: Disclosed is a method of refining of a high purity steel capable of effectively lowering impurities in molten steel into respective ultra-low ranges. In secondary refining for molten steel after a molten iron prerefining process and a converting process, a reducing agent and a flux are added on the bath surface within a ladle containing the molten steel decarburized in a converter so that the composition of slag on the bath surface is adjusted in such a manner that the total concentration of FeO and MnO becomes 5 wt % or less, and subsequently, impurities in the molten steel are effectively lowered into respective ultra-low ranges using a RH vacuum degassing unit.

Abstract: A process for producing an extremely low carbon steel in a top- and bottom-blown converter. The process is characterized in top-blowing a mixed gas of oxygen gas and an inert gas onto a molten steel in the top- and bottom-blown converter. The mixed gas is blown through a top-blowing lance at the final decarburization stage, while a gas (selected from a group consisting of an inert gas, oxygen gas and a mixture of oxygen and an inert gas) is bottom-blown into the molten steel in the converter.

Abstract: A process for producing a steel in at least two converters using a great or substantial amount of an iron-bearing cold material. The iron-bearing cold material and a carbonaceous material are supplied into one of the converters under the presence of a molten iron or a preliminarily treated molten iron and are melted therein under oxygen-blowing to obtain a preliminarily treated molten iron containing a high content of carbon, and the preliminarily treated molten iron is refined in the other converter under oxygen-blowing to obtain a molten steel having the given composition.

Abstract: In the top-and-bottom blown converter steel making process, a process is provided wherein the position of the bottom-blowing tuyeres is set such that the maximum X.sub.0 among the distances X between the respective tuyreres and the center of the converter bottom is up to 1.3 times the horizontal distance Y between the central vertical axis of the converter and the outermost boundary of a hot spot region developed on the molten iron surface by the top-blowing oxidizing gas from the lance. By setting the position of the bottom blowing tuyeres in this manner, the interference of the bottom-blowing gas with the top-blowing gas is promoted to enhance the agitation between the slag and the metal to reduce the concentration of iron value (T.Fe) in the slag, thereby improving the iron yield.

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.