A method for treating molten iron includes applying a metal treatment agent to molten iron; and stirring the molten iron using a rotary device comprising a rotor head. The rotary device can be resistant to corrosion and thermal shock, and thereby permit efficient application of metal treatment agents.

A method for treating molten iron includes applying a metal treatment agent to molten iron; and stirring the molten iron using a rotary device comprising a rotor head. The rotary device can be resistant to corrosion and thermal shock, and thereby permit efficient application of metal treatment agents.

A rotary device and methods for treating molten metal, a tubular sleeve for said rotary device and the use of said rotary device in the treatment of molten metal. The rotary device comprises: a tubular sleeve comprising a rotor head at one end, the rotor head comprising a gas outlet for dispersing gas into molten metal; and a hollow shaft extending inside the tubular sleeve such that at least a portion of the hollow shaft is enclosed by the tubular sleeve, wherein the hollow shaft is fluidly connected to the gas outlet of the rotor head, the tubular sleeve is formed from a refractory material that is resistant to corrosion and thermal shock, and the hollow shaft is formed from a material comprising graphite. A first method comprises: applying a layer of synthetic slag material onto an exposed surface of the molten metal; and stirring the molten metal using a rotary device comprising a rotor head, such that the molten metal flows past the layer of synthetic slag material. A second method comprises: applying a metal treatment agent to molten metal; stirring the molten metal using a rotary device comprising a rotor head; and discharging gas into the molten metal through the rotor head.

When supplying oxygen source to molten pig iron inside a converter-type refining furnace and performing desiliconization, dephosphorization, and decarburization refining, one or more of slag removal flow shape, slag removal flow velocity, and slag surface shape while discharging slag through a throat is measured to estimate one or both of a slag removal amount and physical properties of removed slag. When sequentially performing one or both of desiliconization and dephosphorization, an intermediate step of discharging part or all of generated slag through the throat, and the remaining other refining step, in the intermediate step, the method measures one or two of slag removal flow shape, slag removal flow velocity, and slag surface shape, estimates one or both of amount and physical properties of slag removed, estimates remaining slag amount, or remaining slag amount and composition, and determines an auxiliary raw material amount to be fed in the other refining step.

When supplying oxygen source to molten pig iron inside a converter-type refining furnace and performing desiliconization, dephosphorization, and decarburization refining, one or more of slag removal flow shape, slag removal flow velocity, and slag surface shape while discharging slag through a throat is measured to estimate one or both of a slag removal amount and physical properties of removed slag. When sequentially performing one or both of desiliconization and dephosphorization, an intermediate step of discharging part or all of generated slag through the throat, and the remaining other refining step, in the intermediate step, the method measures one or two of slag removal flow shape, slag removal flow velocity, and slag surface shape, estimates one or both of amount and physical properties of slag removed, estimates remaining slag amount, or remaining slag amount and composition, and determines an auxiliary raw material amount to be fed in the other refining step.

A method for desulfurizing molten steel comprising taking a sample out from molten steel after tapping from a converter or during secondary refining and analyzing the sample rapidly with high accuracy by a method comprising a high frequency induction heating step wherein the sample is combusted and oxidized under the high frequency induction heating in an oxygen atmosphere having an oxygen purity of 99.5 vol % or more to convert S in the sample into SO.sub.2 and an analyzing step wherein SO.sub.2-containing gas produced in the high frequency induction heating step is analyzed through an ultraviolet fluorescence method to quantify S concentration of the sample.

A method for desulfurizing molten steel comprising taking a sample out from molten steel after tapping from a converter or during secondary refining and analyzing the sample rapidly with high accuracy by a method comprising a high frequency induction heating step wherein the sample is combusted and oxidized under the high frequency induction heating in an oxygen atmosphere having an oxygen purity of 99.5 vol % or more to convert S in the sample into SO.sub.2 and an analyzing step wherein SO.sub.2-containing gas produced in the high frequency induction heating step is analyzed through an ultraviolet fluorescence method to quantify S concentration of the sample.

A method for dephosphorization of molten iron includes, while blowing a hydrogen gas, a hydrocarbon gas, or a mixture of these gases into molten iron held in a vessel, supplying a slag-forming agent and an oxygen source to perform a dephosphorization treatment of the molten iron and obtain dephosphorized molten iron, and after the dephosphorization treatment, separating slag floating on a surface of the dephosphorized molten iron from the dephosphorized molten iron. In this method for dephosphorization of molten iron, before the dephosphorization treatment, when obtaining molten iron by melting a cold iron source in a melting furnace and discharging the molten iron from the melting furnace into the vessel, one or both of the following are performed: separating generated slag from the molten iron before the discharge; and separating slag that has flowed into the vessel along with the molten iron from the molten iron.

A method for dephosphorization of molten iron includes, while blowing a hydrogen gas, a hydrocarbon gas, or a mixture of these gases into molten iron held in a vessel, supplying a slag-forming agent and an oxygen source to perform a dephosphorization treatment of the molten iron and obtain dephosphorized molten iron, and after the dephosphorization treatment, separating slag floating on a surface of the dephosphorized molten iron from the dephosphorized molten iron. In this method for dephosphorization of molten iron, before the dephosphorization treatment, when obtaining molten iron by melting a cold iron source in a melting furnace and discharging the molten iron from the melting furnace into the vessel, one or both of the following are performed: separating generated slag from the molten iron before the discharge; and separating slag that has flowed into the vessel along with the molten iron from the molten iron.

The method employs a desulfurization agent that is introduced into a smelt of one of molten pig iron and molten steel. The desulfurization agent contains calcium oxide, bitumen and at least one flux agent, with the agent containing 1 to 10% by weight bitumen.