A production method for smelting clean steel from full-scrap steel using duplex electric arc furnaces, which belongs to the field of electric arc furnace steelmaking. This method makes electric arc furnaces located in two positions be connected in series, wherein the electric arc furnace in a first position is dephosphorization electric arc furnace, and the electric arc furnace in a second position is decarbonization electric arc furnace.

Disclosed are a V-N microalloyed steel and a method for producing a V-N microalloyed and surface-crack-free continuous casting blank. The V-N microalloyed steel is composed of the following chemical components by mass percentage: 0.09%-0.13% of C, 0.1%-0.4% of Si, 1.0%-3.0% of Mn, less than or equal to 0.05% of P, less than or equal to 0.05% of S, 0.1%-0.4% of V, 0.011%-0.2% of N and the balance of Fe and unavoidable impurity elements. A continuous casting blank is subjected to component control according to the chemical components of the V-N microalloyed steel; and the production method therefor comprises converter smelting, LF refining and continuous casting steps in sequence. According to the present invention, by means of reasonable component design and smelting and continuous casting processes, the thermoplasticity of the continuous casting blank is improved, so that a high-temperature brittle region is prevented in a casting blank straightening region of the continuous casting blank or the thermoplasticity is good enough such that no surface crack appears, the casting blank is good in terms of surface quality and does not need to be cleaned, and the production efficiency is improved.

Disclosed are a V-N microalloyed steel and a method for producing a V-N microalloyed and surface-crack-free continuous casting blank. The V-N microalloyed steel is composed of the following chemical components by mass percentage: 0.09%-0.13% of C, 0.1%-0.4% of Si, 1.0%-3.0% of Mn, less than or equal to 0.05% of P, less than or equal to 0.05% of S, 0.1%-0.4% of V, 0.011%-0.2% of N and the balance of Fe and unavoidable impurity elements. A continuous casting blank is subjected to component control according to the chemical components of the V-N microalloyed steel; and the production method therefor comprises converter smelting, LF refining and continuous casting steps in sequence. According to the present invention, by means of reasonable component design and smelting and continuous casting processes, the thermoplasticity of the continuous casting blank is improved, so that a high-temperature brittle region is prevented in a casting blank straightening region of the continuous casting blank or the thermoplasticity is good enough such that no surface crack appears, the casting blank is good in terms of surface quality and does not need to be cleaned, and the production efficiency is improved.

A converter bottom blowing system comprises a first gas source connected in parallel with a lime powder silo, a lime powder blowing tank and a first injector, where a first cut-off valve is arranged between the lime powder blowing tank and the first injector; a second gas source connected in parallel with the biochar powder silo, the biochar powder blowing tank and the second injector, where a second cut-off valve is arranged between the biochar powder blowing tank and the second injector; a converter, where a plurality of bottom blowing lances are arrayed at a bottom of a converter, the bottom blowing lances are connected with the first injector and the second injector through a three-way valve, a third cut-off valve is arranged between the first injector and the three-way valve, and a fourth cut-off valve is arranged between the second injector and the three-way valve.

A converter bottom blowing system comprises a first gas source connected in parallel with a lime powder silo, a lime powder blowing tank and a first injector, where a first cut-off valve is arranged between the lime powder blowing tank and the first injector; a second gas source connected in parallel with the biochar powder silo, the biochar powder blowing tank and the second injector, where a second cut-off valve is arranged between the biochar powder blowing tank and the second injector; a converter, where a plurality of bottom blowing lances are arrayed at a bottom of a converter, the bottom blowing lances are connected with the first injector and the second injector through a three-way valve, a third cut-off valve is arranged between the first injector and the three-way valve, and a fourth cut-off valve is arranged between the second injector and the three-way valve.

A method for controlling a temperature of a molten steel during ladle furnace (LF) refining based on interpretable machine learning includes: acquiring process data of the LF refining and a target temperature of the molten steel during the LF refining; acquiring a prediction model for the temperature of the molten steel during the LF refining; calculating a base value for prediction of the temperature of the molten steel, SHapley Additive explanations (SHAP) values of key factor parameters, and a relationship trend between the key factor parameters and the SHAP values; and calculating a predicted value of the temperature of the molten steel during the LF refining, and acquiring a control result for the temperature of the molten steel during the LF refining according to the relationship trend and the predicted value of the temperature of the molten steel during the LF refining.

A method for controlling a temperature of a molten steel during ladle furnace (LF) refining based on interpretable machine learning includes: acquiring process data of the LF refining and a target temperature of the molten steel during the LF refining; acquiring a prediction model for the temperature of the molten steel during the LF refining; calculating a base value for prediction of the temperature of the molten steel, SHapley Additive explanations (SHAP) values of key factor parameters, and a relationship trend between the key factor parameters and the SHAP values; and calculating a predicted value of the temperature of the molten steel during the LF refining, and acquiring a control result for the temperature of the molten steel during the LF refining according to the relationship trend and the predicted value of the temperature of the molten steel during the LF refining.

Provided are a method and an arrangement for operating a metallurgical furnace. The method comprises a feeding step, and a temperature controlling step for controlling the temperature of a molten metal layer and a slag layer in a furnace space of the metallurgical furnace. The temperature controlling step comprises a first measuring step for measuring the slag temperature (T.sub.slag), a second measuring step for measuring the slag liquidus temperature (T.sub.slag, liquidus), and a calculating step for calculating a superheat temperature (T.sub.superheat) by calculating the temperature difference between the slag temperature (T.sub.slag) and the slag liquidus temperature (T.sub.slag, liquidus). In case the calculated superheat temperature (T.sub.superheat) is outside a predefined superheat temperature range (T.sub.superheat set), the method comprises an adjusting step for adjusting to adjust the actual superheat temperature. Also provided are computer program products.

A cold iron source melting ratio estimation device that estimates a melting ratio of a cold iron source charged into a converter-type refining furnace during refining of molten iron in the converter-type refining furnace. The device includes: an input section to which measured values of in-furnace information or estimated values of the in-furnace information is input, the in-furnace information including a molten iron temperature and a carbon concentration in the molten iron during refining; a database section that stores a model equation and parameters related to a refining reaction of the molten iron in the converter-type refining furnace; a computation section that computes the melting ratio of the cold iron source using the measured values or the estimated values input to the input section; and an output section that displays the melting ratio of the cold iron source computed by the computation section.

The present invention relates to a steel rebar comprising the following ingredients: 0.005%-0.030% of C, 0.3%-0.6% of Si, 1.2%-2.5% of Mn, 0.01% or less of P, 0.01% or less of S, 8.0%-10.0% of Cr, 1.0%-3.0% of Mo, 0.2%-0.4% of Sn, 0.01%-0.05% of Rare Earth element, and the remainder being Fe and unavoidable impurities. The present invention also provides a production method of steel rebar. The steel rebar of the present invention has excellent comprehensive mechanical properties and corrosion resistance performance, while meeting the requirements of anti-knock, the service life in sea water of the steel rebar is increased, thus it can be widely used in reinforced concrete structures in ocean environment.