CN114790503A - Smelting method by adding iron ore - Google Patents

Abstract

The invention discloses a smelting method for adding iron ore, which adopts converter-RH furnace-slab continuous casting process organization production to smelt steel, wherein the smelting steel comprises low-carbon hot-rolled sheet steel such as SPHC and the like; the method comprises the following steps: 1) the converter adopts a low-oxygen high-carbon steel tapping process, carbon is controlled according to 0.07-0.010 percent, steel is placed without deoxidation, and a modifier is added after steel is placed; 2) after the RH furnace is processed for 3-4 min, adding iron ore for decarburization, controlling the decarburization time to be 5-7 min, performing deoxidation alloying after decarburization, performing pure degassing for 5-9 min, and then taking out of the furnace and pouring in a continuous caster; the method utilizes the extremely strong decarbonization characteristic of an RH furnace and the high iron oxide characteristic of iron ore to realize a new steelmaking technology for directly reducing iron in the RH furnace by utilizing molten steel carbon elements on the basis of improving tapping carbon of the converter; the technology can obviously reduce the consumption of steel materials, increase the steel yield and bring direct economic and environmental benefits to enterprises.

Description

Smelting method by adding iron ore

Technical Field

The invention belongs to the field of steel metallurgy and steelmaking, and particularly relates to a smelting method by adding iron ore.

Background

In order to realize the overall goals of carbon peak reaching and carbon neutralization, a stock constraint mechanism based on carbon emission, pollutant emission and total energy consumption is gradually established and realized in China, so that the development path, the process structure and the environmental-friendly clean smelting technology of the iron and steel enterprise are deeply influenced; the smelting technology with low carbon emission and low energy consumption is a key subject to urgent attack of large-sized steel enterprises. The steel making mainly undertakes the production task from molten iron to qualified casting blanks, wherein the consumption of steel and iron materials is taken as an important technical index for steel making, the research on reducing the iron consumption and the related technology of improving the yield of molten steel become the key direction of the steel making strategy, and the method can generate greater benefit and reduce the carbon emission.

When smelting low-carbon hot-rolled sheet steel such as SPHC and the like, the conventional smelting process flow adopts a converter to an LF refining furnace to a continuous casting machine; the converter needs to control the end point carbon content to be within the standard requirement of steel grade, and meanwhile, LF refining is a recarburization process, so that the end point carbon content of the converter is relatively low and is about 0.04% on average, and great pressure is brought to the converter process, refractory and production; on one hand, the high oxidation degree of the molten steel can cause the problems of higher consumption of steel materials, reduced quality of the molten steel and the like; on the other hand, the consumption of the refractory material and the energy medium of the converter is caused; therefore, under the background that domestic and foreign iron and steel enterprises gradually move to low-carbon emission, the bottleneck problem existing in the equipment technology process needs to be changed through process optimization and breakthrough.

Disclosure of Invention

The invention aims to provide a smelting method for adding iron ore into SHC and other steel types by utilizing the rapid decarburization characteristic of an RH furnace. The invention fully optimizes the steelmaking process flow of related products by utilizing the metallurgical characteristics of RH decarburization and the oxygen content characteristics of iron ore; firstly, increasing the carbon content of molten steel by adopting a low-oxygen high-carbon smelting process from a converter; secondly, adding iron ore to perform vacuum decarburization operation in the RH treatment process; the process can directly increase the steel yield, reduce the carbon emission and simultaneously reduce the smelting burden of the converter.

In order to achieve the purpose, the invention adopts the following technical scheme:

the invention provides a smelting method by adding iron ore, which comprises the following steps:

1) the converter adopts a low-oxygen high-carbon tapping process, carbon is controlled according to 0.07-0.010 percent, steel is discharged without deoxidation, and a modifier is added after steel is discharged;

2) after the RH furnace is processed for 3-4 min, adding iron ore for decarburization, controlling the decarburization time to be 5-7 min, performing deoxidation alloying after decarburization, performing pure degassing for 5-9 min, and then taking out of the furnace and pouring in a continuous caster;

preferably, the modifying agent in the step 1) comprises CaO and Al ₂ O ₃ And SiO ₂ One or more than two of them, and the amount of the modifier added is 0.77-1.54 kg/ton steel.

Preferably, the oxygen content in the step 1) is 200-350 ppm.

Preferably, the adding amount of the iron ore in the step 2) is as follows: correspondingly adding according to the constant oxygen amount of the circulation flow for 2-4 min: setting the fixed oxygen amount as X ppm, the added iron ore amount as Y (kg), the molten steel amount as t tons,

when the fixed oxygen amount is less than or equal to 300ppm, adding iron ore, wherein the calculation formula is as follows:

the amount of iron ore is y (kg) { [2100/(X +100) -5 ]. 150. multidot.t/130/}/2

When the fixed oxygen amount is more than 300ppm, the adding amount of the iron ore is as follows:

adding 1.15-1.16 kg of iron ore per ton of steel, adding 0.15-0.16 kg of carbon powder per ton of steel for deoxidation, adding the carbon powder in batches according to the addition amount, wherein each batch is less than or equal to 10kg, the interval time is 20-40 seconds, the temperature drop in the RH process is 15-20 ℃, 1-1.5 ℃/min, and the temperature drop of the iron ore is calculated according to 1.5 times of that of the waste steel;

the adding sequence is that the carbon powder is added after the iron ore is added for 0.5-2 min.

Preferably, the deoxidation in the step 2) is performed by using aluminum particles.

Preferably, the grade of the iron ore is greater than 60, and the iron ore comprises hematite and/or magnetite.

The invention provides a smelting method for adding iron ore into steel grades such as SHC and the like by utilizing the rapid decarburization characteristic of an RH furnace, wherein the smelting adopts a converter-RH furnace-slab continuous casting process for tissue production, the smelting steel grades comprise low-carbon hot-rolled sheet steel such as SPHC and the like, preferably but not limited to SPHC and SPHD sheet steel, and the specific components are as follows:

the method comprises the following steps:

1) the converter adopts a low-oxygen high-carbon steel tapping process, the carbon is controlled to be 0.07-0.010 percent, steel is discharged for deoxidation, and a proper amount of modifier is added after the steel is discharged;

2) after 3min of RH furnace treatment, adding a certain amount of iron ore for decarburization, controlling the decarburization time to be 5-7 min, performing deoxidation alloying after decarburization, pure degassing for 5-9 min, taking out of the furnace after proper temperature, and directly casting on a continuous casting machine (technological parameters can be adjusted according to specific equipment parameters of the RH furnace);

preferably, the adding amount of the iron ore in the step 2) is as follows: adding according to the fixed oxygen amount after circulating for 3 min: the fixed oxygen amount was X ppm, and the amount of iron ore added was Y (kg) (calculated based on 130 tons of molten steel).

When the fixed oxygen amount is less than 300pp, adding iron ore, wherein the calculation formula is as follows:

the amount of iron ore is Y (kg) { [2100/(X +100) -5 ]. 150/}/2

When the fixed oxygen amount is more than 300ppm, the adding amount of the iron ore is as follows:

adding 150kg of iron ore every time, simultaneously adding 20kg of carbon powder for deoxidation, wherein the carbon powder is added in batches in 10 kg/each time at an interval of 20-40 seconds (the adding amount is controlled according to the station entering temperature, the temperature is reduced to 15-20 ℃ in the RH process, and the temperature is reduced to 2.5 ℃ every time 100kg of iron ore is added);

the adding sequence is that iron ore is added for 1min, and then carbon powder is added;

preferably, the deoxidation in the step 2) adopts aluminum particles to perform direct deoxidation, so that the effect of heating the molten steel is achieved. Preferably, in the step 2), the technical parameters are formulated with reference to the condition that the grade of the iron ore is greater than 60, and other grades of iron ores can be correspondingly adjusted, wherein 60 means that the mass fraction of iron elements is 60%;

the oxygen content can be obtained by the skilled person through the controlled amount of carbon in the low-oxygen high-carbon tapping process.

Compared with the prior art, the invention has the advantages that:

the invention combines the composition system characteristics of low-carbon hot-rolled sheet steel such as SPHC and the like, adopts a high-carbon low-oxygen end-point smelting mode for preventing the molten steel of the converter from being oxidized, and compared with the prior art, can basically avoid the molten steel from being oxidized and obviously reduce the consumption of iron and steel materials of the converter; the quality of the molten steel of the converter is obviously improved; obviously reducing the consumption of refractory materials and energy media of the converter; obviously improves the residual content of key manganese elements of the converter.

The invention adopts the unique technical characteristics of the RH furnace for quick decarburization, adopts the technical measures of high carbon and low oxygen for steel discharge of the converter, utilizes the characteristic of high oxygen content of iron ore, and realizes the effect of quick decarburization under the vacuum environment of the iron ore in the RH furnace treatment process, thereby achieving the technical requirement of the carbon target of steel grade.

Detailed Description

Any feature disclosed in this specification may be replaced by alternative features serving equivalent or similar purposes, unless expressly stated otherwise. Unless expressly stated otherwise, each feature is only an example of a generic series of equivalent or similar features. The description is only for the purpose of facilitating understanding of the present invention and should not be construed as specifically limiting the present invention.

The invention is further illustrated with respect to specific examples, but the invention is not limited thereby within the scope of the description of the examples.

Example 1

The smelting adopts a converter-RH furnace-slab continuous casting process to carry out tissue production (taking 130 tons of molten steel as an example), the smelting steel is SPHC low-carbon hot-rolled sheet steel, the smelting furnace number is H221-01252, and the specific component requirements are as follows:

the specific technical operation steps are as follows:

1) the converter adopts a low-oxygen high-carbon tapping process, the end point carbon is 0.07 percent, steel is placed without deoxidation, and a proper amount of modifier is added after the steel is placed;

2) after the RH furnace is treated for 3min, the oxygen content is 185ppm according to the calculation formula of adding iron ore:

the amount of iron ore is Y (kg) { [2100/(X +100) -5 ]. multidot.150/}/2 ═ 177kg

177kg of iron ore is added for decarburization, the decarburization time is 5min, the oxygen content after decarburization is 180ppm, then aluminum particles are added for deoxidation alloying, the pure degassing time is 6min, and after the temperature is proper, the mixture is taken out of the station and directly poured on a continuous casting machine;

the endpoint sampling was made as follows: c: 0.042 percent; si: 0.012%; mn: 0.010%; p: 0.020%; s: 0.015 percent; and (3) Alt: 0.039%; the components meet the standard requirements of steel grades.

Preferably, under the condition that the grade of the reference iron ore is 60, other grades of iron ores can be correspondingly adjusted, wherein 60 means that the mass fraction of iron elements is 60%;

example 2

The smelting adopts a converter-RH furnace-slab continuous casting process to carry out tissue production (taking 130 tons of molten steel as an example), the smelting steel is SPHC low-carbon hot-rolled sheet steel, the smelting furnace number is H222-01341, and the specific component requirements are as follows:

the specific technical operation steps are as follows:

1) the converter adopts a low-oxygen high-carbon tapping process, the end point carbon is 0.09%, steel is discharged without deoxidation, and a proper amount of modifier is added after steel is discharged;

2) after the RH furnace is treated for 3min, the oxygen content is 102ppm, and according to the calculation formula of adding iron ore:

the amount of iron ore is y (kg) { [2100/(X +100) -5 ]. 150/}/2 ═ 404kg

Adding 404kg of iron ore for decarburization, wherein the decarburization time is 7min, the oxygen content after decarburization is 132ppm, adding aluminum particles for deoxidation alloying, the pure degassing time is 8min, taking out the cast ingot after proper temperature, and directly casting the cast ingot on a continuous casting machine;

the endpoint sampling was made as follows: c: 0.045%; si: 0.013%; mn: 0.012%; p: 0.018%; s: 0.013%; and (3) Alt: 0.045%; the components meet the standard requirements of steel grades.

Preferably, under the condition that the grade of the reference iron ore is 60, other grades of iron ores can be correspondingly adjusted, wherein 60 refers to the mass fraction of iron elements in the iron ores being 60%;

example 3

The smelting adopts a converter-RH furnace-slab continuous casting process to carry out tissue production (taking 130 tons of molten steel as an example), the smelting steel is SPHC low-carbon hot-rolled sheet steel, the smelting furnace number is H223-01426, and the specific component requirements are as follows:

the specific technical operation steps are as follows:

1) the converter adopts a low-oxygen high-carbon tapping process, but the carbon at the end point is 0.05 percent due to higher phosphorus control and 1 complementary blowing, the steel is not deoxidized, and a proper amount of modifier is added after the steel is discharged;

2) after RH furnace treatment for 3min, determining oxygen content to be 340ppm, measuring temperature to be 1610 ℃, and adding iron ore according to the temperature; every 150kg of iron ore is added, and 20kg of carbon powder is added at the same time for deoxidation:

adding 300kg +40kg of carbon powder into the iron ore

Adding carbon powder in batches at intervals of 30 seconds, wherein each time is 10 kg/time;

the adding sequence is that iron ore is added for 1min, and then carbon powder is added; the decarburization time is 8min, the oxygen concentration after decarburization is 320ppm, then aluminum particles are added for deoxidation alloying (simultaneously, the deoxidation and temperature raising effects are achieved), the pure degassing time is 9min, the temperature is measured at 1584 ℃ when the aluminum particles are taken out of the station, and the aluminum particles are directly poured on a continuous casting machine;

the endpoint sampling was made as follows: c: 0.032%; si: 0.010%; mn: 0.08%; p: 0.022%; s: 0.015 percent; and (3) Alt: 0.047 percent; the components meet the standard requirements of steel grades.

Preferably, the above technical parameters refer to the condition that the grade of the iron ore is 60, and other grades of iron ores can be adjusted correspondingly, wherein 60 refers to the mass fraction of iron element being 60%.

The method utilizes the extremely strong decarbonization characteristic of an RH furnace and the high iron oxide characteristic of iron ore to realize a new steelmaking technology for directly reducing iron in the RH furnace by utilizing molten steel carbon elements on the basis of improving tapping carbon of the converter; the technology can obviously reduce the consumption of steel materials, increase the steel yield and bring direct economic and environmental benefits to enterprises.

From the results of the embodiment of the invention, when the SPHC low-carbon hot-rolled sheet steel is smelted, the end-point carbon of the converter can basically realize a high-carbon low-oxygen smelting mode, so that the burden of the smelting operation of the converter and refractory and energy media is reduced, and even if the end-point oxygen is high due to improper operation caused by special reasons, the RH furnace can still adopt an emergency smelting mode according to conditions to achieve the smelting process for adding iron ore.

The smelting method disclosed by the invention is adopted for smelting the steel such as the SPHC low-carbon hot-rolled sheet, the defects of difficult converter over-oxidation, refining deoxidation and slagging, long smelting period and the like caused by the traditional process are overcome, the technical requirements of low-oxygen high-carbon in the converter process and the technical characteristics of quick decarburization under the vacuum condition of an RH furnace are coupled, the pain points in smelting the steel are solved, the standard smelting process parameters and the practical experience are searched and established, and a new breakthrough and a new situation are brought for the promotion of the steelmaking process technology.

The method can be realized by upper and lower limit values and interval values of intervals of process parameters (such as temperature, time and the like), and embodiments are not listed.

Conventional technical knowledge in the art can be used for the details which are not described in the present invention.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not limited. Although the present invention has been described in detail with reference to the embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted without departing from the spirit and scope of the present invention as defined in the appended claims.

Claims (6)

1. A smelting method for adding iron ore comprises the following steps:

1) the converter adopts a low-oxygen high-carbon steel tapping process, carbon is controlled according to 0.07-0.010 percent, steel is placed without deoxidation, and a modifier is added after steel is placed;

2) and (3) after RH furnace treatment for 3-4 min, adding iron ore for decarburization, controlling decarburization time to be 5-7 min, performing deoxidation alloying after decarburization, pure degassing for 5-9 min, and then taking out of the furnace and directly casting on a continuous casting machine.

2. The smelting method according to claim 1, wherein the modifier in step 1) includes CaO and Al ₂ O ₃ And SiO ₂ One or more than two of the above, and the amount of the modifier added is 0.77-1.54 kg/ton steel.

3. The smelting method according to claim 1, wherein the oxygen content in the step 1) is 200 to 350 ppm.

4. The smelting method according to claim 1, wherein the iron ore is added in the step 2) in the following specific amounts: correspondingly adding according to the constant oxygen amount of the circulation flow for 2-4 min: setting the fixed oxygen amount as X ppm, the added iron ore amount as Y (kg), the molten steel amount as t tons,

when the fixed oxygen amount is less than or equal to 300ppm, adding iron ore, wherein the calculation formula is as follows:

the amount of iron ore is Y (kg) { [2100/(X +100) -5 ]. 150. multidot.t/130/}/2

When the fixed oxygen amount is more than 300ppm, the adding amount of the iron ore is as follows:

adding 1.15-1.16 kg of iron ore per ton of steel, adding 0.15-0.16 kg of carbon powder per ton of steel for deoxidation, adding the carbon powder in batches according to the addition amount, wherein each batch is less than or equal to 10kg, the interval time is 20-40 seconds, the temperature drop in the RH process is 15-20 ℃, 1-1.5 ℃/min, and the temperature drop of the iron ore is calculated according to 1.5 times of that of the waste steel;

the adding sequence is that the carbon powder is added after the iron ore is added for 0.5-2 min.

5. The smelting method according to claim 1, wherein the deoxidation in the step 2) is performed by using aluminum particles.

6. A smelting process according to claim 1, characterised in that the grade of the iron ore is greater than 60, the iron ore comprising hematite and/or magnetite.