RU2145355C1 - Method of steel melting in converter - Google Patents

Abstract

FIELD: metallurgy, more specifically, steel melting in converter from vanadium iron. SUBSTANCE: method includes charging of scrap into converter; pouring of vanadium iron; supply of slag-forming materials, including lime; top blowing of melt with oxygen through submerged multinozzle lance; melt tapping from converter. In course of melting in (0.18-0.24)τ_bl since beginning of blowing, supplied to converter is mixture of chlorides of alkali-earth metals (Na,K)Cl with NaCl/KCl weight ratio of 0.3-0.7 and consumption of mixture within 1.5-2.5 kg/t of melt. In (0.3-0.34)τ_bl since beginning of blowing, slag is discharged from converter, and lime is supplied to converter in amount of 25-40 kg/t of melt, and blowing is continued up to heat completion, where τ_bl is duration of converter blowing. EFFECT: higher efficiency of process and its simplification, provided obtaining of vanadium pentoxide. 1 tbl, 1 ex

Description

 The invention relates to metallurgy, and more particularly, to steelmaking processes in a converter of vanadium cast iron.

The closest in technical essence is the method of steelmaking in the converter, including the supply of scrap metal to the converter, pouring vanadium cast iron into it, blowing the melt with oxygen from above through a multi-nozzle lance, and also pouring the intermediate into a steel-pouring ladle. Slag is poured into a slag ladle. Then the intermediate is poured into another converter, in which the finished steel is melted by blowing the melt with oxygen from above through a multi-nozzle submersible lance. In this case, vanadium pentoxide V ₂ O _{5 is} obtained in the slag.

 (See. "Steel production technology in modern converter shops." S.V. Kolpakov et al. M .: Mashinostroenie, 1991, p. 150 - 152).

The disadvantage of this method is the complexity of the process of steelmaking. This is explained by the need to re-purge the melt in another converter, which requires additional time. In addition, in order to determine the required carbon content in the melt, several knockouts of the converter are necessary. However, the required content of vanadium pentoxide V ₂ O ₅ in the slag is not provided.

 The technical effect when using the invention is to increase productivity and simplify the process of steelmaking and obtaining vanadium pentoxide.

 The indicated technical effect is achieved in that the method of steel smelting in the converter includes feeding scrap metal into the converter, pouring vanadium cast iron into it, feeding slag-forming materials, including lime, into the converter, purging the melt with oxygen from above through a multi-nozzle lance, and also draining the melt from the converter .

In the process of smelting through (0.18 - 0.24) τ _pr from the beginning of purging, a mixture of alkaline earth metal chlorides (Na, K) Cl with a weight ratio of NaCl / KCl = 0.3 - 0.7 and with a mixture flow rate of within 1.5 - 2.5 kg / t of melt, and through (0.3 - 0.34) τ _pr from the beginning of purging, slag is drained from the converter, after which lime is fed into the converter with a flow rate of 25 - 40 kg / t of melt and continue to purge the melt until the end of the smelting, where τ _CR - time purge the Converter.

The increase in productivity of the steelmaking process will occur due to the elimination of the need for repeated purging of the melt in another converter and the loss of time in this process. The supply of alkaline earth metal chlorides provides short-term foaming of slag with a high content of vanadium pentoxide, which contributes to its rapid and complete discharge from the converter. Subsequent supply of lime to the converter allows at the end of the purge to obtain steel of the required chemical composition. The foregoing is achieved only when using a mixture of sodium and potassium chlorides in the indicated weight ratio. When using mixtures of other alkaline earth metals, the required production efficiency of V ₂ O ₅ will not be ensured.

The range of values of the purge time of the converter before a mixture of chloride of alkaline earth metals is supplied to it within (0.18 - 0.24) τ _pr is explained by the physicochemical laws of the oxidation of vanadium from cast iron to slag in the form of vanadium pentoxide V ₂ O ₅ . At lower values, an insufficient amount of vanadium will pass into the slag. It is impractical to establish large values, since a high temperature is reached, which causes the development of decarburization and the recovery of vanadium from slag.

 The specified range is set in direct proportion to the capacity of the converter.

The range of values of the purge time of the converter before the slag is drained from it within (0.3 - 0.34) τ _pr is explained by the physicochemical laws of the formation and foaming of slag enriched in vanadium pentoxide V ₂ O ₅ . At lower values, the slag will not be sufficiently foamed. At high values, slag emissions from the converter are possible.

 The specified range is set in direct proportion to the capacity of the converter.

 The range of values of the weight ratio NaCl / KCl = 0.3 - 0.7 is explained by the physicochemical laws of their joint effect on the formation process and kinetics of short-term foaming of slag enriched in vanadium pentoxide. At lower values, the necessary foaming of the slag will not be provided. At high values, slag emissions from the converter are possible.

 The specified range is set in direct proportion to the flow rate of the mixture (Na, K) Cl.

 The range of flow rates of the mixture (Na, K) Cl in the range of 1.5 - 2.5 kg / t of the melt is explained by the physicochemical laws of the formation and foaming of vanadium-rich slag. At lower values, the necessary foaming of the slag will not be provided. At high values, slag emissions from the converter are possible.

 The range of lime flow rates in the range of 25 - 40 kg / t of melt is explained by the physicochemical laws of slag formation in the converter after discharge of foamed slag enriched in vanadium pentoxide. At lower values, the necessary removal of sulfur and phosphorus from the melt will not be provided. At large values, the basicity of the slag will exceed the permissible values.

 The specified range is set in direct proportion to the capacity of the converter.

 The analysis of scientific, technical and patent literature shows the lack of coincidence of the distinguishing features of the proposed method with the signs of known technical solutions. Based on this, it is concluded that the claimed technical solution meets the criterion of "inventive step".

 The following is an embodiment of the invention that does not exclude other variations within the scope of the claims.

 The method of steelmaking in the converter is as follows.

Example. When smelting steel of the St3 grade, scrap is fed into the converter, vanadium cast iron is poured into it, slag-forming materials, including lime, are fed into the converter, the melt is blown with oxygen through a multi-nozzle lance with a flow rate of 2.5 - 5.0 m ³ / min • t of melt . After smelting, the steel is poured into a steel pouring ladle and the remaining slag into a slag truck.

In the process of smelting through (0.18 - 0.24) τ _CR from the beginning of purging, a mixture of alkaline earth metal chlorides (Na, K) Cl with a weight ratio in the range of 0.3 - 0.7 and with a flow rate of the mixture in the range of 1 is fed into the converter 5 - 2.5 kg / t of melt. Under these conditions, slag enriched in vanadium pentoxide V ₂ O ₅ foams for a short time and increases its fluidity.

Through (0.3 - 0.34) τ _pr stop the melt blowing and pour the foamed slag from the converter into the slag carrier. After draining the slag, lime is fed into the converter with a flow rate of 25-40 kg / t of melt and the melt is purged with oxygen until melting is completed.

 The table shows examples of the method with various technological parameters.

 In the first example, due to the low consumption of the mixture of alkaline earth metal chloride (Na, K) Cl, insufficient melt purge time before the mixture is fed into the converter, and also the converter purge time together with the mixture, the necessary increase in the content of vanadium pentoxide in the slag being drained is not provided.

 In the fifth example, due to the large consumption of the mixture of alkaline earth metal chlorides (Na, K) Cl, the long time the melt is purged before the mixture is fed into the converter, and also the time the converter is purged, together with the mixture of alkaline earth metals, foamed slag is emitted from the converter, which is accompanied by losses of vanadium pentoxide.

In the optimal examples 2-4, due to the required values of the process parameters, an increased content of vanadium pentoxide V ₂ O ₅ is provided in the pre-slag slag from the converter. This eliminates the need for re-purging the melt in another converter, which leads to an increase in the productivity of the process of steel smelting of the required chemical composition.

Claims (1)

The method of steel smelting in a converter, including supplying scrap metal to the converter, pouring vanadium cast iron into it, feeding slag-forming materials, including lime, into the converter, blowing the melt with oxygen from above through a submersible multi-nozzle mold, and also draining the melt from the converter, characterized in that the process of smelting through (0.18 - 0.24) τ _pr from the beginning of purging into the converter serves a mixture of alkaline earth metal chlorides (Na, K) Cl with a weight ratio of NaCl / KCl = 0.3 - 0.7 and with a flow rate of the mixture within 1.5 - 2.5 kg / t of melt, and through (0.3 - 0.34) τ _pr from the beginning For purging, the slag is drained from the converter, after which lime is fed into the converter with a flow rate of 25–40 kg / t of melt and the melt is continued to be purged until the end of smelting, where τ _pr is the purge time of the converter.

Images