Converter steelmaking method using limestone instead of lime

Abstract

The invention discloses a converter steelmaking method by replacing lime with limestone, which comprises the following steps: calculating according to 40-60 kg of lime consumed by 1 ton of steel and 90% of CaO mass fraction in lime, adding 68-102 kg of limestone to 1 ton of steel for completely replacing lime, and releasing 28-42 kg of CO2 and 14-21 m < 3 > of CO2 by 1 ton of steel. The method provided by the invention is beneficial to reducing slag consumption and reducing the production cost of enterprises.

Description

Technical Field

[0001] The present invention relates to a converter steelmaking method using limestone to replace lime. Background Art

[0002] Currently, 120t converters use reactive lime for steelmaking. In the case of a high hot metal ratio, the converter has a high thermal surplus and needs to use slag materials for cooling, resulting in excessive consumption of slag materials. The decomposition process of limestone absorbs heat, and the generated gas can help with slag melting and phosphorus removal, achieving a two - birds - with - one - stone effect.

[0003] Literature Retrieval: It is found that there are periodicals and patents such as "Limestone Steelmaking" in a certain year. By comparison, the present invention is very different from such papers and patent literatures. The above - mentioned inventions mainly focus on the smelting process, while the present invention focuses on the chemical energy perspective, analyzing the practical feasibility of use and the promotion of lime consumption. Summary of the Invention

[0004] The purpose of the present invention is to provide a converter steelmaking method using limestone to replace lime, which is beneficial to reducing the consumption of slag materials and lowering the production cost of enterprises.

[0005] The technical solution adopted by the present invention is a converter steelmaking method using limestone to replace lime. Calculated according to the consumption of 40 - 60 kg of lime per ton of steel and the mass fraction of CaO in lime being 90%, to completely replace lime, 68 - 102 kg of limestone needs to be added per ton of steel, and the mass of CO2 released per ton of steel is 28 - 42 kg, with a volume of 14 - 21m 3 .

[0006] The technical principle of the method of the present invention is the decomposition reaction of limestone in the early stage of steel: For the decomposition reaction of CaCO3 in limestone, the temperature range considered is 900 - 1200K; for the reaction of CO2 with each element in hot metal, the temperature range considered is 1400 - 1700K. After the limestone particles are put into the converter, they will immediately heat up rapidly from the surface to the inside, and CaCO3 will quickly start to decompose. The relationship between the change in standard free energy and temperature between 900 - 1200K calculated according to this decomposition reaction and literature data is as follows. Since heat transfer occurs from the outside to the inside of the limestone particles, the decomposition reaction should also occur layer by layer from the surface to the inside.

[0007] CaCΟ3→ CaΟ + CΟ2, The reaction of CO2 with each element in hot metal: CO2 is an oxidizing gas in the initial stage of converter steelmaking blowing. It can react with various elements in hot metal. From the published data, the relationship between the change in standard free energy of the reaction of CO2 with various elements in hot metal to form simple oxides and temperature between 1400 and 1700 K can be calculated, as shown in equations (2) to (6);

[0008] It can be seen from equations (2) to (6) that CO2 has a certain oxidation ability for various elements in hot metal. When the oxygen supply in the initial stage of converter steelmaking blowing remains unchanged, the CO2 decomposed from limestone participates in the oxidation reaction of various elements in hot metal, which is equivalent to increasing the oxygen supply intensity. The enhanced oxygen supply effect of the CO2 decomposed from limestone is very effective for rapid slag formation.

[0009] Under the condition that the oxygen blowing amount remains unchanged in the early stage of blowing, such a large amount of CO2 reaches the hot metal surface within a few minutes, which not only is equivalent to strengthening the oxygen supply in the early stage of blowing, but also is a "soft blowing" method. Therefore, much more FeO will be produced than when using lime to form slag, thus accelerating the slag melting speed of fresh lime and being beneficial to the progress of the dephosphorization reaction.

[0010] The present invention is applicable to various top-bottom combined blowing converters in China. Limestone can be used instead of lime for smelting. When the converter adopts high hot metal ratio smelting, adding limestone can make up for the disadvantage of small temperature drop of active lime, reduce the consumption of active lime, and stabilize the end point temperature at the same time. Specific implementation mode

[0011] A converter steelmaking method using limestone to replace lime. Calculated according to the consumption of 40 - 60 kg of lime per ton of steel and the mass fraction of CaO in lime being 90%, to completely replace lime, 68 - 102 kg of limestone needs to be added per ton of steel, and the mass of CO2 released per ton of steel is 28 - 42 kg, with a volume of 14 - 21 m 3 .

Claims

1. A converter steelmaking method using limestone to replace lime, characterized in that Calculated according to the consumption of 40 - 60 kg of lime per ton of steel and the mass fraction of CaO in lime being 90%, 68 - 102 kg of limestone needs to be added to completely replace lime for one ton of steel. The mass of CO2 released per ton of steel is 28 - 42 kg, and the volume is 14 - 21 m 3 .

Images