Kawasaki Steel Corporation

Sumitomo Chemical Company, Limited

Hiroshi Nishikawa

Masaru Washio

Yasuo Kishimoto

Naoki Kikuchi

Toshikazu Sakuraya

Kazuhisa Hamagami

Koji Yamaguchi

Tomomichi Terabatake

Nagayasu Bessho

Shuji Takeuchi

Fumio Sudo

Ryuichi Asaho

Hitoshi Ohsugi

Kyoichi Kameyama

Masanori Nishikohri

Akihito Hirota

Kimiharu Aida

Process for smelting reduction of chromium ore

Method and top blowing lance for decarburization refining chromium molten ferrous metal in which dust formation and chromium loss due to oxidation are suppressed and high productivity is achieved. Decarburization of molten ferrous metal is achieved by blowing gaseous oxygen into the molten metal in a refining furnace provided with a top blowing lance having a plurality of gas blowing nozzles at the tip of the lance. The gas blowing nozzles include at least one sub-nozzle provided at or near the lance axis and a plurality of main nozzles at an outer section of the lance. Blowing refining is carried out with oxygen flow from a plurality of the main nozzles at a flow rate higher than that from the sub-nozzle(s), when the carbon content in the molten metal is about 1 wt % or more.

Decarburization refining process for chromium-containing molten metal

A method of decarburizing refining molten steel containing Cr in such a manner that oxygen gas, inert gas or a mixture of inert gas and oxygen gas is blown to the surface of bath of molten steel containing Cr in a refining chamber and to a position below the surface of the steel bath. Inert gas is blown to the surface of the steel bath, and oxygen gas, the inert gas or a mixture of oxygen gas and inert gas is blown below the surface of the steel bath in a portion of or all of an overall period in which the concentration of C in the molten steel is in a range of 1 wt % and 0.05 wt %. Slag and molten steel are stirred so as to cause Cr.sub.2 O.sub.3 in the slag and C in the molten steel to positively take part in a reaction represented by expression (1) below:

Method of decarburizing refining molten steel containing Cr

A method of degassing and decarburizing molten stainless steel in a vacuum, which molten steel is produced in a steel making furnace. Molten steel is foamed in a vacuum tank. Before foaming the [N] (%) in the molten steel is increased. The foam is produced by denitrification of the steel during vacuum degassing. Oxidizing gas is blown through a top-blow lance onto the surface of the steel in a vacuum tank, causing the reaction C+1/2O.sub.2 .fwdarw.CO to decarbonize the steel. Temperature decrease of the molten steel is resisted by combustion of CO produced by the reaction of C+1/2O.sub.2 .fwdarw.CO.

Method of degassing and decarburizing stainless molten steel

A method of producing an ultra-low-carbon steel by conducting vacuum-decarburization of a molten steel by means of a vacuum degasifier of the type having recirculation pipes and a vacuum chamber. When the carbon content of the molten steel has come down to a level of 50 ppm or less, hydrogen gas is introduced together with an inert gas into the molten steel either by directly injecting a hydrogen-containing gas into the molten steel in the vacuum chamber through a tuyere provided in the wall of the vacuum chamber or by blowing the hydrogen-containing gas onto the surface of the molten steel in the vacuum chamber through a lance provided in the vacuum chamber. In order to enhance the effect produced by the method of the present invention, it is possible to take an additional measure such as blowing of hydrogen gas through a tuyere provided in the wall of the recirculation pipe or injection of hydrogen or hydrogen-containing gas through an injection lance immersed in the molten steel held in, a ladle.

Method of producing ultra-low-carbon steel

This invention relates to a system for generating a sequence of an industrial process by combining in a required sequence a plural number of processes each realized by operating an assembly of a plurality of apparatuses (solenoid valve, mixer, flow rate controller, etc.). Operation of the system comprises a first step of storing, in first memory, a sequence command containing apparatus data relating to the apparatuses and operation data relating to the operations of the apparatuses for preparing a command file for realizing the industrial process, a second step of storing in second memory a command file containing the sequence command read from the first memory, which simulates the industrial process and a third step of reading symbols, stored previously by the third memory, which corresponds to the apparatus data of the sequence command stored by the second memory. The operation of the system further comprises a fourth step of displaying a schema of a device for realizing the industrial process using the symbols read in the third step, and a fifth step of reading from the second memory the operation data of the sequence command, and simulating the operational procedure of the industrial process by the device in accordance with the operation data.

Device and method for generating a sequence of industrial process

A method of producing an ultra-low-carbon steel by using a vacuum degasser on a molten steel has the steps of conducting vacuum decarburization to attain a predetermined level of carbon content, e.g., 25 ppm or below, in the molten steel while progressively reducing the pressure in said vacuum degasser, conducting addition of hydrogen in which hydrogen is dissolved in said molten steel while said pressure is temporarily elevated to 20 Torr or above, and conducting final decarburization after reducing said pressure to 2 Torr or below. The addition of hydrogen may be conducted to meet the following conditions:

A process of degassing and decarbonizing is directed to a process for performing vacuum degassing non-deoxidized or slightly deoxidized molten steel utilizing RH process or DH process. The process includes blowing of oxygen or oxygen containing gas toward the surface of the molten steel in a vacuum chamber for promoting decarbonizing reaction. The process further includes a step of combustioning of CO gas in the vicinity of the surface of the molten metal at a timing, in which concentration of (CO+CO.sub.2) in an exhaust gas is higher than or equal to 5% and a ratio of CO.sub.2 versus (CO+CO.sub.2) in the exhaust gas is approximately 30%. Heat generated by combustioning of CO gas is utilized for compensating temperature drop of the molten steel.

Growing community of inventors

Chiba, Japan

Hiroshi Nishikawa