An apparatus is disclosed for a metallurgical furnace having a roof with an integrated off-gas hood. The roof has a hollow metal roof. The hollow metal roof has a top, a bottom, an outer sidewall and an inner sidewall. An opening extends from the top to the bottom and is defined by the inner sidewall. The opening is configured for one or more electrodes to pass therethrough. An enclosed space is defined between the top, the bottom, the inner sidewall and the outer sidewall. A spray-cooled system is disposed in the enclosed space and configured to spray coolant in the enclosed space on the bottom surface of the hollow metal roof. A channel having walls is disposed through the enclosed space, wherein the spray-cooled system extends between the top of the hollow metal roof and the wall of the channel.

The invention relates to a mixture to be introduced into the slag located on a metal melt in iron and steel metallurgy, the use of such a mixture, and a method for conditioning a slag located on a metal melt in a metallurgical vessel, for example in a converter, in an electric arc furnace or in a ladle, in iron and steel metallurgy.

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.

The present disclosure provides a method for producing a high nitrogen steel by a duplex melting process of a pressurized ladle refining and a pressurized electroslag remelting, which relates to the technical field of high nitrogen steel melting. In the present disclosure, the molten steel is subjected in sequence to a nitrogen alloying, a deep deoxidation and a deep desulfurization by adding a nickel-magnesium alloy and rare earth in the pressurized ladle furnace, and a combination of a blowing nitrogen from the bottom of the pressurized ladle and a pressurized nitriding at the interface of gas and the molten steel is used to achieve a high-efficiency nitrogen alloying, a uniform nitrogen distribution, and a decreased impurity content in the ingot; then the ingot is subjected to a pressurized electroslag remelting to obtain a high nitrogen steel.

A method for forming a protective antioxidative barrier on the furnace electrodes using a chemically altered cooling liquid containing an antioxidant additive. This method can be applied to electrodes used in electric arc furnaces and ladle metallurgy furnaces. The method can involve spraying the cooling liquid onto the electrode, thereby forming the protective antioxidative barrier and reducing the oxidation of the electrode.

Disclosed are processes for recycling chromium oxide and producing chromium-alloy steel. Chromium oxide is reduced to metallic chromium and metallic chromium is mixed with steel to form chromium-alloy steel.

The present disclosure provides a method for producing a high nitrogen steel by a duplex melting process of a pressurized ladle refining and a pressurized electroslag remelting, which relates to the technical field of high nitrogen steel melting. In the present disclosure, the molten steel is subjected in sequence to a nitrogen alloying, a deep deoxidation and a deep desulfurization by adding a nickel-magnesium alloy and rare earth in the pressurized ladle furnace, and a combination of a blowing nitrogen from the bottom of the pressurized ladle and a pressurized nitriding at the interface of gas and the molten steel is used to achieve a high-efficiency nitrogen alloying, a uniform nitrogen distribution, and a decreased impurity content in the ingot; then the ingot is subjected to a pressurized electroslag remelting to obtain a high nitrogen steel.

A method for forming a protective antioxidative barrier on the furnace electrodes using a chemically altered cooling liquid containing an antioxidant additive. This method can be applied to electrodes used in electric arc furnaces and ladle metallurgy furnaces. The method can involve spraying the cooling liquid onto the electrode, thereby forming the protective antioxidative barrier and reducing the oxidation of the electrode.

Disclosed is a slag discharging method in a process of producing ultra-low phosphorus steel, which relates to the technical field of iron and steel smelting, and in which molten steel is mixed with lime first to produce basic slag; then converting is performed with oxygen to increase the oxidizability of the basic slag; and a carbon-containing reducing agent is finally added, so that in the process that the carbon is oxidized to release a large amount of carbon monoxide gas, phosphates are captured, and the basic slag is rapidly foamed and overflows from the opening of the steel ladle, so that conditions are no longer available for rephosphorization. Also disclosed is a method for producing ultra-low phosphorus steel, which includes the above-described slag discharging method in a process of producing ultra-low phosphorus steel, and refining and ingotting after slag discharge.

An apparatus is disclosed for a metallurgical furnace having a roof with an integrated off-gas hood. The roof has a hollow metal roof section. The hollow metal roof section has a top and a bottom surface. The hollow metal roof section has a center opening configured for one or more electrodes to pass therethrough. An enclosed space is disposed between the top and the bottom surface. A spray-cooled system is disposed in the enclosed space and configured to spray-coolant on the bottom surface of the roof. The integrated off-gas hood has an inlet open to the center opening. The spray-cooled system is also configured to cool the integrated off-gas hood.