Provided is a non-oriented electrical steel sheet having such a low Al concentration so that it is excellent in terms of the recycling efficiency of scrap iron and having a high magnetic flux density and low iron loss.

The non-oriented electrical steel sheet according to the present invention has a chemical composition containing C; 0.0050 mass % or less, Si; 1.5 mass % to 5.0 mass %, Mn; 0.2 mass % to 3.0 mass %, sol.Math.Al; 0.0030 mass % or less, P; 0.2 mass % or less, S; 0.0050 mass % or less, N; 0.0040 mass % or less, T.Math.Ca; 0.0010 mass % to 0.0080 mass %, T.Math.O; 0.0100 mass % or less, REM; 0.0001 mass % to 0.0050 mass %, and a balance of Fe and inevitable impurities, in which a value of a mass-related fractional expression ((T.Math.Ca+REM)/(T.Math.O+S)), which is a relational expression for the masses of the four constituents described above, that is, T.Math.Ca, REM, T.Math.O, and S, is 0.4 or more.

Provided is a non-oriented electrical steel sheet having such a low Al concentration so that it is excellent in terms of the recycling efficiency of scrap iron and having a high magnetic flux density and low iron loss.

The non-oriented electrical steel sheet according to the present invention has a chemical composition containing C; 0.0050 mass % or less, Si; 1.5 mass % to 5.0 mass %, Mn; 0.2 mass % to 3.0 mass %, sol.Math.Al; 0.0030 mass % or less, P; 0.2 mass % or less, S; 0.0050 mass % or less, N; 0.0040 mass % or less, T.Math.Ca; 0.0010 mass % to 0.0080 mass %, T.Math.O; 0.0100 mass % or less, REM; 0.0001 mass % to 0.0050 mass %, and a balance of Fe and inevitable impurities, in which a value of a mass-related fractional expression ((T.Math.Ca+REM)/(T.Math.O+S)), which is a relational expression for the masses of the four constituents described above, that is, T.Math.Ca, REM, T.Math.O, and S, is 0.4 or more.

A method of purifying yttrium involves purifying element yttrium by high-temperature saturated dissolution, low-temperature recrystallization, high-temperature reduction and vaporization-based removal of impurities, in a simple manner, and at a low cost, such that yttrium element is unlikely to be contaminated by any raw material used in a manufacturing process.

Processes for producing low nitrogen, essentially nitride-free chromium or chromium plus niobium-containing nickel-based alloys include charging elements or compounds which do not dissolve appreciable amounts of nitrogen in the molten state to a refractory crucible within a vacuum induction furnace, melting said elements or compounds therein under reduced pressure, and effecting heterogeneous carbon-based bubble nucleation in a controlled manner. The processes also include, upon cessation of bubble formation, adding low nitrogen chromium or a low nitrogen chromium-containing master alloy with a nitrogen content of below 10 ppm to the melt, melting and distributing said added chromium or chromium-containing master alloy throughout the melt, bringing the resulting combined melt to a temperature and surrounding pressure to permit tapping, and tapping the resulting melt, directly or indirectly, to a metallic mold and allowing the melt to solidify and cool under reduced pressure.

Processes for producing low nitrogen, essentially nitride-free chromium or chromium plus niobium-containing nickel-based alloys include charging elements or compounds which do not dissolve appreciable amounts of nitrogen in the molten state to a refractory crucible within a vacuum induction furnace, melting said elements or compounds therein under reduced pressure, and effecting heterogeneous carbon-based bubble nucleation in a controlled manner. The processes also include, upon cessation of bubble formation, adding low nitrogen chromium or a low nitrogen chromium-containing master alloy with a nitrogen content of below 10 ppm to the melt, melting and distributing said added chromium or chromium-containing master alloy throughout the melt, bringing the resulting combined melt to a temperature and surrounding pressure to permit tapping, and tapping the resulting melt, directly or indirectly, to a metallic mold and allowing the melt to solidify and cool under reduced pressure.

A process for producing high-purity magnesium by means of distillation at reduced pressure, characterized in that, the high-purity magnesium condenses in the liquid state, whereby the starting material in the form of a magnesium-containing melt is present together with the upper region of a condensation vessel in the upper region of a retort, whereby the retort consist of a material that releases no volatile impurities into the magnesium steam, whereby the upper region of the retort is brought to a temperature above the boiling point of magnesium, within the limits of two level lines, and is then held constant, such that steam rises from the boiling magnesium-containing metal melt and fills the interior of the upper region of the retort, whereby the steam infiltrating the upper region of the condensation vessel condenses below the lower level line and collects as high-purity melt in the lower region of the condensation vessel, and whereby in order to prevent contaminated melt that drops from the region above the upper level line from reaching the opening of the condensation vessel, this is protected by a cover, which conveys the impure magnesium back again into the melt.

A process for producing high-purity magnesium by means of distillation at reduced pressure, characterized in that, the high-purity magnesium condenses in the liquid state, whereby the starting material in the form of a magnesium-containing melt is present together with the upper region of a condensation vessel in the upper region of a retort, whereby the retort consist of a material that releases no volatile impurities into the magnesium steam, whereby the upper region of the retort is brought to a temperature above the boiling point of magnesium, within the limits of two level lines, and is then held constant, such that steam rises from the boiling magnesium-containing metal melt and fills the interior of the upper region of the retort, whereby the steam infiltrating the upper region of the condensation vessel condenses below the lower level line and collects as high-purity melt in the lower region of the condensation vessel, and whereby in order to prevent contaminated melt that drops from the region above the upper level line from reaching the opening of the condensation vessel, this is protected by a cover, which conveys the impure magnesium back again into the melt.

A method for removing lead-210 (.sup.210Pb) from a metal, the method comprising determining a .sup.210Pb concentration in a metal to be refined; determining an amount of low alpha lead to be added to the metal to be refined from the .sup.210Pb concentration, the low alpha lead having a .sup.210Pb concentration below that of the metal to be refined; forming a doped metal mixture by adding the low alpha lead to the metal to be refined; refining the doped metal mixture to separate at least a portion of the lead in the doped metal mixture to form a refined metal having a .sup.210Pb concentration lower than that of the metal to be refined.

A method for removing lead-210 (.sup.210Pb) from a metal, the method comprising determining a .sup.210Pb concentration in a metal to be refined; determining an amount of low alpha lead to be added to the metal to be refined from the .sup.210Pb concentration, the low alpha lead having a .sup.210Pb concentration below that of the metal to be refined; forming a doped metal mixture by adding the low alpha lead to the metal to be refined; refining the doped metal mixture to separate at least a portion of the lead in the doped metal mixture to form a refined metal having a .sup.210Pb concentration lower than that of the metal to be refined.

Processes for producing low-nitrogen metallic chromium or chromium-containing alloys, which prevent the nitrogen in the surrounding atmosphere from being carried into the melt and being absorbed by the metallic chromium or chromium-containing alloy during the metallothermic reaction, include vacuum-degassing a thermite mixture comprising metal compounds and metallic reducing powders contained within a vacuum vessel, igniting the thermite mixture to effect reduction of the metal compounds within the vessel under reduced pressure i.e., below 1 bar, and conducting the entire reduction reaction in said vessel under reduced pressure, including solidification and cooling, to produce a final product with a nitrogen content below 10 ppm. The final products obtained, in addition to low-nitrogen metallic chromium in combination with other elements, can be used as raw materials in the manufacture of superalloys, stainless steel and other specialty steels whose final content of nitrogen is below 10 ppm.