An immersion probe with a variable connection length is configured to compensate for longitudinal and/or radial length variations in an immersion sublance connected to the immersion probe. The immersion probe is characterized by an adjustable portion that changes length upon engagement with a coupling end of an immersion sublance. The immersion probe can have a sensor head. An immersion assembly of the immersion probe connected to an immersion sublance can be used to take measurements or samples of molten metal in a converter furnace.

Disclosed is a disc-shaped sample chamber for collecting molten metal, the chamber comprising: a chamber body having a left body and a right body bonded to each other to define a disc-shaped sample space therebetween; an inlet extending upward from the chamber body and connecting the sample space with the outside; and a welded bonding portion disposed on at least one lateral face of the chamber body for bonding the left body and the right body to each other. Further, a probe having the chamber is disclosed.

Provided is a method of, in ladle refining treatment of a molten steel, accurately estimating the molten steel temperature after the ladle refining treatment. An operation method of ladle refining treatment by which ladle refining treatment of a molten steel is performed while continuously measuring a molten steel temperature during operation of the ladle refining treatment of the molten steel comprises setting a time earlier than a scheduled ending time of the ladle refining treatment in a continuous measurement period of the molten steel temperature as a determination timing, and estimating the molten steel temperature at the scheduled ending time on the basis of a change with time of the molten steel temperature in continuous measured data of the molten steel temperature from a start of continuous measurement of the molten steel temperature to the determination timing.

The present invention concerns a lance composed of a top lance (1t) and of a sublance (2) coupled to the top lance (1t), which forms a shoulder (1s) between the top lance and the sublance. The sublance (2) of the present invention is provided with a protective device (3) comprising a coupling end (2c) opening to the cavity (2v), wherein, when at rest, the protective device (3) is in an initial configuration characterized by an outer maximum diameter (D3o) which is not more than 10% larger than the diameter (D2) of sublance (2) (D3o≤1.1 D2), when the sublance (2) is coupled to the lance the protective device (3) contacts the shoulder (1s) and is deformed into a deformed configuration, forming a surface impervious to molten metal and slag, which spans over a whole area of the shoulder (1s).

The invention relates to a method for extracting metal from metal-containing raw material in a batch process by using a direct current electric arc furnace (100) having one or more than one top electrode (125) and at least one bottom electrode (115), wherein the method comprises the following steps: adding the metal-containing raw material to the furnace (100), thereby obtaining a loaded bath, moving the top electrode(s) (125) onto the raw material, heating the loaded bath in a heating step by applying direct current through the top electrode(s) to provide an arc to melt the raw material, thereby obtaining molten metal (202), wherein an average voltage during the heating step is from 20 V to 110 V, and forming solid metal from the molten metal (202). The invention further relates to a direct current electric arc furnace, a system comprising a direct current electric arc furnace, and a solid metal obtainable by the method.

The present disclosure provides a converter CO.sub.2—O.sub.2 mixed injection smelting method and a fire point area temperature dynamic control method. The method realizes online monitoring through an infrared temperature sensor installed inside an oxygen lance, dynamically adjusts the mixing ratio of CO.sub.2 and O.sub.2 and the height of the oxygen lance position according to the fire point area temperature changes and process requirements in different smelting stages, so that the secondary smelting system interlockingly and dynamically controls the fire point area temperature and the molten pool heating rate.

A decarburization end point determination method includes: estimating the carbon concentration and oxygen concentration of the molten steel and carbon dioxide gas concentration of exhaust gas in the vacuum chamber by using measurement values of the carbon concentration and the oxygen concentration of the molten steel, a measurement value of internal pressure of the vacuum chamber, and a model formula; correcting a parameter included in the model formula to reduce at least one of a difference between an estimate value and a measurement value of the oxygen concentration and a difference between an estimate value and a measurement value of the carbon dioxide gas concentration of the exhaust gas; estimating the carbon concentration of the molten steel by using the model formula in which the parameter is corrected; and determining timing when an estimate value reaches a target value as the completion time point of the vacuum decarburization treatment.

A decarburization refining method for molten steel under reduced pressure. The method includes an oxygen-blowing decarburization and a rimmed decarburization. Using operation data taken at a time when oxygen-blowing decarburization is started and a time when oxygen-blowing decarburization is ended, an amount of carbon removed while the oxygen-blowing decarburization is performed is estimated. Based on the estimated amount of carbon removed, a carbon concentration in molten steel at a time when the rimmed decarburization is started is estimated. Using the estimated value as the carbon concentration in molten steel at the time when the rimmed decarburization is started, a change over time in the carbon concentration in molten steel while the rimmed decarburization is performed is calculated. Based on the calculated change over time in the carbon concentration in molten steel while the rimmed decarburization is performed, a determination is made about a time when the rimmed decarburization is ended.

A system and method for monitoring consumption of graphite electrodes during the operation of an electric arc furnace (EAF) uses machine vision cameras operatively communicating with a computer processor. The system can determine, track, manage, and optimize the consumption of the graphite electrodes in real time. Electrode consumption is determined for each EAF heat by measuring the length and tip diameter of the electrode. The length and tip diameter are used to determine the electrode consumption amount using a consumption model. Measured hydraulic pressure within the EAF correlating with a known electrode weight can also be used to determine electrode consumption and correlated with the model calculation. Butt loss can also be determined based on the machine vision measured lengths of the electrode and/or based on the hydraulic pressure. The calculated electrode consumption amounts are also stored in a database and correlated to other measured EAF parameters for multiple EAFs.

The invention relates to a method and an apparatus for controlling the pressure in the exhaust gas duct of a converter in a steel mill using a pressure control loop. To optimize the defined pressure setpoint for the pressure control loop so as to prevent excessive amounts of outside air from being drawn in via the converter mouth, the pressure setpoint is determined according to the invention by adapting a raw value based on the extent to which smoke or flames is/are formed at the mouth (120) of the converter (100).