CN117778644A - Low-carbon iron-making method by blast furnace carbon circulation - Google Patents
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- CN117778644A CN117778644A CN202311858566.3A CN202311858566A CN117778644A CN 117778644 A CN117778644 A CN 117778644A CN 202311858566 A CN202311858566 A CN 202311858566A CN 117778644 A CN117778644 A CN 117778644A
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- 229910052799 carbon Inorganic materials 0.000 title claims abstract description 28
- 238000000034 method Methods 0.000 title claims abstract description 23
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 title claims abstract description 18
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 claims abstract description 242
- 229910052742 iron Inorganic materials 0.000 claims abstract description 121
- 239000002994 raw material Substances 0.000 claims abstract description 119
- 239000000446 fuel Substances 0.000 claims abstract description 75
- 239000007789 gas Substances 0.000 claims abstract description 44
- 238000003723 Smelting Methods 0.000 claims abstract description 25
- 239000003245 coal Substances 0.000 claims abstract description 22
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 17
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 17
- 239000001301 oxygen Substances 0.000 claims abstract description 17
- 238000006722 reduction reaction Methods 0.000 claims abstract description 16
- 238000002347 injection Methods 0.000 claims abstract description 15
- 239000007924 injection Substances 0.000 claims abstract description 15
- 239000002893 slag Substances 0.000 claims abstract description 4
- 239000000571 coke Substances 0.000 claims description 22
- 239000000463 material Substances 0.000 claims description 17
- 238000007664 blowing Methods 0.000 claims description 14
- 238000005261 decarburization Methods 0.000 claims description 14
- 239000003034 coal gas Substances 0.000 claims description 9
- 229910000831 Steel Inorganic materials 0.000 claims description 8
- 229910052739 hydrogen Inorganic materials 0.000 claims description 8
- 239000010959 steel Substances 0.000 claims description 8
- 238000009826 distribution Methods 0.000 claims description 6
- NINIDFKCEFEMDL-UHFFFAOYSA-N Sulfur Chemical compound [S] NINIDFKCEFEMDL-UHFFFAOYSA-N 0.000 claims description 4
- 230000015556 catabolic process Effects 0.000 claims description 4
- 238000006243 chemical reaction Methods 0.000 claims description 4
- 238000006731 degradation reaction Methods 0.000 claims description 4
- 230000009257 reactivity Effects 0.000 claims description 4
- 229910052717 sulfur Inorganic materials 0.000 claims description 4
- 239000011593 sulfur Substances 0.000 claims description 4
- 239000011449 brick Substances 0.000 claims description 3
- 238000002156 mixing Methods 0.000 claims description 3
- 229910052757 nitrogen Inorganic materials 0.000 claims description 3
- 238000004177 carbon cycle Methods 0.000 claims 1
- 239000002817 coal dust Substances 0.000 claims 1
- 238000005516 engineering process Methods 0.000 description 14
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 10
- 239000000126 substance Substances 0.000 description 8
- 229910000805 Pig iron Inorganic materials 0.000 description 7
- 229910002092 carbon dioxide Inorganic materials 0.000 description 5
- 239000000203 mixture Substances 0.000 description 4
- 238000005422 blasting Methods 0.000 description 3
- 239000001569 carbon dioxide Substances 0.000 description 3
- 238000007792 addition Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 238000002844 melting Methods 0.000 description 2
- 230000008018 melting Effects 0.000 description 2
- 238000012986 modification Methods 0.000 description 2
- 230000004048 modification Effects 0.000 description 2
- 238000004458 analytical method Methods 0.000 description 1
- 238000004939 coking Methods 0.000 description 1
- 238000002485 combustion reaction Methods 0.000 description 1
- 238000005262 decarbonization Methods 0.000 description 1
- 230000007613 environmental effect Effects 0.000 description 1
- 238000004519 manufacturing process Methods 0.000 description 1
- 238000012797 qualification Methods 0.000 description 1
- 239000007921 spray Substances 0.000 description 1
- 239000002918 waste heat Substances 0.000 description 1
- 239000002699 waste material Substances 0.000 description 1
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Abstract
The invention discloses a low-carbon iron-making method of blast furnace carbon circulation, which takes a blast furnace body as main smelting equipment, raw fuel is filled in through charging equipment at the top of the blast furnace, furnace burden is mainly iron-containing main raw materials and fuel, the fuel and the iron-containing main raw materials are alternately distributed in a layered mode, decarburized gas can be blown through a combined tuyere at a blast furnace tuyere, and blast furnace smelting is carried out through ultrahigh oxygen enrichment, hot air and coal injection operation at the combined tuyere, finally decarburized gas is used for completely replacing pulverized coal, and meanwhile, the blast furnace obtains molten iron and slag through reduction reaction of the iron-containing main raw materials.
Description
Technical Field
The invention relates to a low-carbon iron-making method for blast furnace carbon circulation, and belongs to the technical field of blast furnace low-carbon iron-making.
Background
The technology of the modern blast furnace ironmaking process has been developed for hundreds of years, and the present technology has been improved in many aspects of high yield, low consumption, long service life, high efficiency, high quality, environmental protection, etc., and the blast furnace ironmaking process has been developed to a very perfect degree in terms of theory and technology. Counting CO of iron and steel enterprises according to international energy agency 2 The emission amount accounts for CO in the whole world 2 6.7% of total discharge, and blast furnace ironmaking CO 2 The emission amount accounts for about the whole production of CO from steel 2 70% of the discharge. Blast furnaces are the most dominant energy consumers and CO in the iron industry 2 The release source is further required to be further developed and applied to spray CO on the basis of continuously perfecting the traditional energy-saving and emission-reducing method (such as large coal injection, high air temperature and the like) 2 The technology of reducing the coal gas is convenient for continuously improving the energy saving and emission reduction effects.
Disclosure of Invention
The invention aims to provide a low-carbon iron-making method for blast furnace carbon circulation, which can reduce carbon dioxide emission, and has low consumption and high yield.
According to the technical scheme, the low-carbon iron making method with the blast furnace carbon circulation is characterized in that a blast furnace body is used as main smelting equipment, raw fuel is filled through charging equipment at the top of the blast furnace, furnace charge is mainly composed of iron-containing main raw materials and fuel, the fuel and the iron-containing main raw materials are alternately distributed in a layered mode in the furnace, decarburization gas can be blown through a combined tuyere at a blast furnace tuyere, blast furnace smelting is carried out through ultrahigh oxygen enrichment, hot air and coal injection operation at the combined tuyere, and finally decarburization gas is used for completely replacing pulverized coal, and meanwhile, the blast furnace is used for carrying out reduction reaction on the iron-containing main raw materials to obtain molten iron and slag;
the raw materials are uniformly distributed by four raw materials of an iron-containing first raw material, an iron-containing second raw material, an iron-containing third raw material and an iron-containing fourth raw material according to a certain proportion, and the raw materials are in mass percent: the first raw material containing iron accounts for 75-80% of the total mass of the raw materials in percentage by mass, the second raw material containing iron accounts for 11-16% of the total mass of the raw materials in percentage by mass, the third raw material containing iron accounts for 2-3% of the total mass of the raw materials in percentage by mass, and the fourth raw material containing iron accounts for 4-6% of the total mass of the raw materials in percentage by mass;
the TFe of the first raw material containing iron is 54.5 percent plus or minus 0.5 percent, R 2 The multiple is 1.85+/-0.08, the drum index +6.35mm is not lower than 81.5%, and the low-temperature reduction degradation index RDI +3.15 is not lower than 72%; the cold state compressive strength of the iron-containing second raw material is not lower than 2100N, and the reduction expansion index RSI is not higher than 15.5%;
the fuel layer is formed by uniformly mixing fuel 1 and fuel 2 according to a proportion, wherein the fuel consumption is 350-380 kg/t molten iron; the proportion of the fuel 2 is 4-8% of the fuel mass according to the mass percentage; the fixed carbon FCd% of the fuel is not less than 85.5% of the total mass of the fuel, the ash content Ad% is not more than 11.5% of the total mass of the fuel, the sulfur content St, d% is not more than 0.8% of the total mass of the fuel, the volatile Vdaf% is not more than 1.2% of the total mass of the fuel, the crushing strength M40 is not less than 89.5%, the wear resistance M10 is not more than 6.5%, the reactivity CRI is 35-50%, and the post-reaction strength CSR is 35-42.5%;
raw fuel used by the blast furnace is weighed under a groove, is fed into the blast furnace from the furnace top through a conveying belt by a charging and distributing device at the furnace top of the blast furnace according to sequential batch circulation alternation of a coke bed layer and an iron-containing main raw material layer, so that reasonable distribution of edge airflow and center airflow is ensured, the center airflow is stabilized through a funnel with a certain depth, and meanwhile, stable and smooth edge airflow is obtained. In the material distribution process, the distance between a material level platform and a furnace throat steel brick is 300-400mm, the width of the material level platform is controlled to be about 1.5-2.0m, the depth of a central funnel is controlled to be 1.4-2.5 m, the material level shape is proper, and the material level is controlled to be 1.4-1.9m;
the decarburized coal gas at the blast furnace tuyere comprises the following specific components: the volume fraction of the decarbonized gas CO is 65-75%, H 2 Volume fraction of 10-20%, N 2 The volume fraction of CO2 and other components is 11-15%, the volume fraction of other gas components is 0.5-5%, the volume fraction of other gas components is 1-3%, the temperature of the blowing decarburization gas is 35-45 ℃, and the blowing amount is 100-250 Nm3/t iron;
specific parameters of the ultra-high oxygen enrichment, hot air and coal injection operation are as follows: the blast furnace blast temperature is 1150-1250 ℃, the volume of humidity in blast is 1.0-2.5%, the oxygen content in blast is 21-50%, the coal injection amount is 75-85 kg/t, and the smelting period is 6.5-8.5 h.
Advantageous effects
1. The invention adopts the iron-making method of injecting coal gas, injects 50-250 Nm3/t decarbonizing high-reducibility circulating coal gas, and high-concentration CO is conveyed to a blast furnace tuyere through a pipeline to realize CO and H 2 The gas with high reduction potential is enriched in the blast furnace again and is used for reducing the iron-containing main raw material of iron, thereby realizing carbon circulation and completely utilizing the carbon chemical energy. By gas circulation, CO and H in the high-reducibility circulating gas 2 The chemical energy is not wasted by removing CO 2 And then the waste heat is recycled in the blast furnace, so that the consumption of fossil energy by the blast furnace is reduced.
2. The invention adopts the blast oxygen content of the tuyere to be 26-50%, and can effectively compensate the theoretical combustion temperature drop of the tuyere swirling region after the coal gas is injected;
3. the invention adopts the iron-making method of injecting gas and simultaneously adds part of iron-containing fourthRaw materials, the pig iron yield is improved, the ratio of the iron-containing fourth raw materials is increased by 1kg/t, the fuel ratio is reduced by 0.52kg/t, and the iron-containing fourth raw materials only consume partial melting heat in the furnace and do not consume chemical heat, so that CO and H in the furnace 2 Compared with the traditional blast furnace smelting technology, the reducing atmosphere is sufficient, the reduction of the iron-containing main raw material can be obviously promoted, the utilization ratio of low-value waste iron-containing resources can be improved, and a new method is provided for the comprehensive utilization of metallurgical resources.
4. The invention adopts the injected gas as a grip, improves and optimizes the operation means of the blast furnace air supply system, integrates and reasonably matches the technology with the existing blast furnace ironmaking technology, reduces the coke ratio to the maximum extent, reduces the carbon dioxide emission and improves the smelting efficiency.
5. The invention provides an iron-making method for large blast furnace gas injection under low thermal strength fuel, which can ensure that eight-steel fuel improves the iron yield and pig iron qualification rate of the blast furnace by optimizing operation means under the fuel performance index of 36-42% of thermal strength CSR, improves various technical and economic indexes of blast furnace smelting, ensures stable and smooth blast furnace condition, and has low consumption and high yield.
Description of the embodiments
The invention will be further illustrated with reference to the following detailed description, which should be understood as merely illustrative of the invention and not as limiting the scope of the invention.
The method uses a blast furnace as smelting equipment, a gas decarburization device is used as blowing equipment, an iron-containing main raw material layer and a fuel layer are used as furnace materials in the blast furnace, raw fuel is weighed under a tank, and is fed into the blast furnace from the top of the blast furnace through a conveying belt by a charging and distributing device according to sequential batch circulation of the coke layer and the iron-containing main raw material layer; and blowing decarburized gas into a blast furnace tuyere, and carrying out blast furnace smelting by adopting ultrahigh oxygen enrichment, hot air and coal injection operation, so as to finally obtain molten iron and slag.
The raw materials are uniformly distributed by four raw materials of an iron-containing first raw material, an iron-containing second raw material, an iron-containing third raw material and an iron-containing fourth raw material according to a certain proportion, and the raw materials are in mass percent: the first raw material containing iron accounts for 75-80% of the total mass of the raw materials in percentage by mass, the second raw material containing iron accounts for 11-16% of the total mass of the raw materials in percentage by mass, the third raw material containing iron accounts for 2-3% of the total mass of the raw materials in percentage by mass, and the fourth raw material containing iron accounts for 4-6% of the total mass of the raw materials in percentage by mass.
The TFe of the first iron-containing raw material is 54.5 percent+/-0.5 percent, and R is 2 The (times) value is 1.85+/-0.08, the drum index is not less than 81.5% with the length of +6.35mm, and the low-temperature reduction degradation index RDI is not less than 72% with the length of +3.15; the cold compressive strength of the iron-containing second raw material is not lower than 2100N, and the reduction expansion index RSI is not higher than 15.5%.
The fuel layer is formed by uniformly mixing fuel 1 and fuel 2 in proportion, wherein the fuel consumption is 350-380 kg/t of molten iron; the proportion of the fuel 2 is 4-8% of the fuel mass according to the mass percentage. The fixed carbon FCd% of the fuel is not less than 85.5% of the total mass of the fuel, the ash Ad% is not more than 11.5% of the total mass of the fuel, the sulfur St, d% is not more than 0.8% of the total mass of the fuel, the volatile Vdaf% is not more than 1.2% of the total mass of the fuel, the crushing strength M40 is not less than 89.5%, the wear resistance M10 is not more than 6.5%, the reactivity CRI is 35-50%, and the post-reaction strength CSR is 35-42.5%. The invention provides an iron-making method for blast furnace gas injection under low thermal strength fuel, which can ensure that eight-steel fuel improves various technical and economic indexes of the blast furnace under low thermal strength through optimizing operation means.
According to the low-carbon iron-making method with the blast furnace carbon circulation, raw fuel used by the blast furnace is weighed under a groove, and is fed into the blast furnace from the furnace top through a conveying belt by charging and distributing equipment of the blast furnace top according to sequential batch circulation of a coke bed layer and an iron-containing main raw material layer, so that reasonable distribution of edge airflow and center airflow is ensured, the center airflow is stabilized through a funnel with a certain depth, and meanwhile, stable and smooth edge airflow is obtained. In the material distribution process, the distance between the material level platform and the furnace throat steel brick is 300-400mm, the width of the material level platform is controlled to be about 1.5-2.0m, the depth of the central funnel is controlled to be 1.4-2.5 m, the material level shape is proper, and the material level is controlled to be 1.4-1.9m.
The blast furnace carbon circulation low-carbon ironmaking method comprises the following specific components of decarburized coal gas at a blast furnace tuyere: the volume fraction of the decarbonized gas CO is 65-75%, H 2 Volume fraction of 10-20%, N 2 The volume fraction of CO2 and other components is 11-15%, the volume fraction of other gas components is 0.5-5%, the volume fraction of other gas components is 1-3%, the temperature of the blowing decarburization gas is 35-45 ℃, and the blowing amount is 100-250 Nm3/t iron.
The specific parameters of the ultrahigh oxygen enrichment, hot air and coal injection operation are as follows: the blast furnace blast temperature is 1150-1250 ℃, the volume of humidity in blast is 1.0-2.5%, the oxygen content in blast is 21-50%, the coal injection amount is 75-85 kg/t, and the smelting period is 6.5-8.5 h.
Example 1: conventional blast furnace operation technology (reference operation period)
In this example (decarburization gas injection is 0Nm3/t iron):
the content of TFe in the iron-containing first raw material is 54.5%, the main chemical composition is shown in table 1, the drum index is 81%, and the low-temperature reduction degradation index RDI+3.15 is 72%.
The second iron-containing feedstock TFe content was 65.27% and its chemical composition was as shown in Table 1, with a compressive strength of 2100N and a reduction expansion index RSI of 14%.
The iron-containing third raw material TFe content was 48.9%, and the chemical composition thereof is shown in Table 1.
The chemical composition of the iron-containing fourth feedstock is shown in table 1 with a TFe content of 98.2%.
The fuel industry analysis is shown in Table 2, with a crushing strength M40 of 89.70%, a wear resistance M10 of 6.00%, a reactivity CRI of 40-50%, a post-reaction strength CSR of 36-42%, a sulfur content St, and a d of 0.47%.
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The iron-containing first raw material, the iron-containing second raw material, the iron-containing third raw material and the iron-containing fourth raw material in table 1 are mixed uniformly and then added into a blast furnace to form an iron-containing main raw material layer, the fuel in table 2 is added into the blast furnace to form a fuel bed layer, all raw fuels are weighed under a tank, and are fed into blast furnace top charging and distributing equipment through a conveying belt from the blast furnace top, and blast furnace smelting is carried out by alternately adding the coke bed layer and the iron-containing main raw material layer into the blast furnace from the top in turn in batch circulation. The iron-containing main raw material layer contains iron-containing first raw materials: iron-containing second raw material: iron-containing third raw material: the mass percentage of the iron-containing fourth raw material is 75 percent: 15%:5 percent to 5 percent. The temperature of the hot air is 1120 ℃, the blasting humidity is 12.32g/m < 3 >, and the oxygen enrichment rate is 3.5%.
The main operation indexes of the blast furnace smelting 1t molten iron under the conventional blast furnace operation conditions are shown in table 6. The ore-coke ratio is 3.89, the pig iron yield is 5000t, the coke ratio is 430kg/t, the coal ratio is 100kg/t, the fuel ratio is 550kg/t, and the CO is reduced 2 The carbon emission is 0kg/t, and the gas utilization rate is 45.2%.
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Example 2: (blowing 50 Nm) 3 T decarbonizing gas
The iron-containing first raw material, the iron-containing second raw material, the iron-containing third raw material and the iron-containing fourth raw material in the embodiment 1 are uniformly mixed and then added into a blast furnace to form an iron-containing main raw material layer, fuel is added into the blast furnace to form a fuel bed layer, all raw fuels are weighed under a tank, and are fed into a blast furnace top charging and distributing device through a conveying belt from the blast furnace top, and blast furnace smelting is carried out by sequentially and circularly and alternately feeding the raw materials from the top into the blast furnace from the top in batches according to the coke bed layer and the iron-containing main raw material layer. The iron-containing main raw material layer contains iron-containing first raw materials: iron-containing second raw material: iron-containing third raw material: the mass percentage of the iron-containing fourth raw material is 75 percent: 15%:5 percent to 5 percent. The temperature of the hot air is 1120 ℃, the blasting humidity is 12.32g/m < 3 >, and the oxygen enrichment rate is 5.5%.
Blowing 50Nm 3 The main operation indexes of the t decarburization gas blast furnace for smelting 1t molten iron are shown in Table 7. The ore-coke ratio is 4.0, the pig iron yield is 4120t, the coke ratio is 418kg/t, the coal ratio is 92kg/t, the fuel ratio is 530kg/t, and the gas utilization rate is 46.1%. Conventional high as in example 1Compared with the furnace operation technology (reference operation period), the yield is improved by 120t, the coke ratio is reduced by 12kg, the coal ratio is reduced by 8kg, the carbon emission is reduced by 48.8kg, and the gas utilization rate is improved by 4.70%.
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Example 3: (blowing 150 Nm) 3 T decarbonizing gas
The iron-containing first raw material, the iron-containing second raw material, the iron-containing third raw material and the iron-containing fourth raw material in the embodiment 1 are uniformly mixed and then added into a blast furnace to form an iron-containing main raw material layer, fuel is added into the blast furnace to form a fuel bed layer, all raw fuel is weighed under a tank, and is fed into a blast furnace top charging and distributing device through a conveying belt from the blast furnace top, and blast furnace smelting is carried out by sequentially and circularly and alternately adding the coke bed layer and the iron-containing main raw material layer into the blast furnace from the top in batches. The iron-containing main raw material layer contains iron-containing first raw materials: iron-containing second raw material: iron-containing third raw material: the mass percentage of the iron-containing fourth raw material is 75 percent: 15%:5 percent to 5 percent. The temperature of the hot air is 1080 ℃, the blasting humidity is 12.32g/m < 3 >, and the oxygen enrichment rate is 20.5%.
Blowing 150Nm 3 The main operation indexes of the t decarburization gas blast furnace for smelting 1t molten iron are shown in Table 5. The ore-coke ratio is 4.23, the pig iron yield is 5500t, the utilization coefficient is 2.2, the coke ratio is 394kg/t, the coal ratio is 76kg/tHM, the fuel ratio is 490kg/t, and the gas utilization rate is 47.8%.
Compared with the traditional blast furnace operation technology (reference operation period) of the embodiment 1, the yield is improved by 500t, the coke ratio is reduced by 36kg, the coal ratio is reduced by 24kg, the carbon emission is reduced by 146.4kg, and the gas utilization rate is improved by 2.6%.
Compared with the embodiment 2, the yield is improved by 380t, the coke ratio is reduced by 24kg, the coal ratio is reduced by 16kg, the fuel ratio is reduced by 40kg, the carbon emission is reduced by 97.6kg, and the gas utilization rate is improved by 1.7%. And each index is better than that of examples 1 and 2.
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Example 4: (blowing 250 Nm) 3 T decarbonizing gas
The iron-containing first raw material, the iron-containing second raw material, the iron-containing third raw material and the iron-containing fourth raw material in the embodiment 1 are uniformly mixed and then added into a blast furnace to form an iron-containing main raw material layer, fuel is added into the blast furnace to form a fuel bed layer, all raw fuel is weighed under a tank, and is fed into a blast furnace top charging and distributing device through a conveying belt from the blast furnace top, and blast furnace smelting is carried out by sequentially and circularly and alternately adding the coke bed layer and the iron-containing main raw material layer into the blast furnace from the top in batches. The iron-containing main raw material layer contains iron-containing first raw materials: iron-containing second raw material: iron-containing third raw material: the mass percentage of the iron-containing fourth raw material is 75 percent: 15%:5 percent to 5 percent. The hot air temperature was 1050 ℃, the blast humidity was 12.32g/m3, and the oxygen enrichment rate was 29.5%.
Blowing 250Nm 3 The main operation indexes of the t decarburization gas blast furnace for smelting 1t molten iron are shown in Table 6. The ore coke ratio is 4.49, the pig iron yield is 6000t, the utilization coefficient is 2.4, the coke ratio is 370kg/t, the coal ratio is 60kg/tHM, the fuel ratio is 450kg/t, and the gas utilization rate is 49.6%.
Compared with the embodiment 3, the yield is improved by 500t, the coke ratio is reduced by 24kg, the coal ratio is reduced by 16kg, the fuel ratio is reduced by 40kg, the carbon emission is reduced by 97.6kg, and the gas utilization rate is improved by 1.8%. And each index was better than example 3.
To this end, the decarburization gas is blown into the tuyere of the blast furnace by 50 to 250Nm 3 High-reducibility circulating gas for/t decarbonization, and high-concentration CO is conveyed to a blast furnace tuyere through a pipeline to realize CO and H 2 The gas with high reduction potential is enriched in the blast furnace again, and partial iron-containing fourth raw material is added, so that the pig iron yield is improved, and the iron-containing fourth raw material only consumes partial melting heat and does not consume chemical heat in the furnace, so that CO and H in the furnace are reduced 2 Compared with the traditional blast furnace smelting technology, the reducing atmosphere is sufficient, and the reduction of the iron-containing main raw material can be obviously promoted. Adopts ultra-high oxygen-enriched smelting with the blast oxygen content of 26-50% at a tuyere, and simultaneously optimizes blast of a blast furnace by utilizing the fuel of the eight-steel existing coking coal resource under the fuel performance index of 36-42% of thermal state strength CSRThe system uses the low-thermal-state strength fuel to be effectively coupled with the injection decarburization gas technology, integrates and reasonably matches the technology with the existing blast furnace ironmaking technology, reduces the coke ratio to the maximum extent, reduces the carbon dioxide emission and improves the smelting efficiency.
The above embodiments are described in terms of preferred embodiments of the present invention, and it should be noted that modifications and additions may be made to those skilled in the art without departing from the principles of the present invention, which modifications and additions should also be construed as falling within the scope of the present invention.
Claims (1)
1. The low-carbon iron-making method of a blast furnace carbon cycle, the iron-making method uses the blast furnace body as main smelting equipment, raw fuel is loaded through charging equipment on the top of the blast furnace, furnace charge is mainly iron-containing main raw materials and fuel, the fuel and iron-containing main raw materials are alternately distributed in layers, decarburization coal gas can be blown through a combined tuyere at a blast furnace tuyere, and blast furnace smelting is carried out by adopting ultrahigh oxygen enrichment, hot air and coal injection operation at the combined tuyere, and finally decarburization coal gas is used for completely replacing coal dust, and meanwhile, the blast furnace obtains molten iron and slag by carrying out reduction reaction on the iron-containing main raw materials; the method is characterized in that:
the raw materials are uniformly distributed by four raw materials of an iron-containing first raw material, an iron-containing second raw material, an iron-containing third raw material and an iron-containing fourth raw material according to a certain proportion, and the raw materials are in mass percent: the first raw material containing iron accounts for 75-80% of the total mass of the raw materials in percentage by mass, the second raw material containing iron accounts for 11-16% of the total mass of the raw materials in percentage by mass, the third raw material containing iron accounts for 2-3% of the total mass of the raw materials in percentage by mass, and the fourth raw material containing iron accounts for 4-6% of the total mass of the raw materials in percentage by mass;
the TFe of the first raw material containing iron is 54.5 percent plus or minus 0.5 percent, R 2 The multiple is 1.85+/-0.08, the drum index +6.35mm is not lower than 81.5%, and the low-temperature reduction degradation index RDI +3.15 is not lower than 72%; the cold state compressive strength of the iron-containing second raw material is not lower than 2100N, and the reduction expansion index RSI is not higher than 15.5%;
the fuel layer is formed by uniformly mixing fuel 1 and fuel 2 according to a proportion, wherein the fuel consumption is 350-380 kg/t molten iron; the proportion of the fuel 2 is 4-8% of the fuel mass according to the mass percentage; the fixed carbon FCd% of the fuel is not less than 85.5% of the total mass of the fuel, the ash content Ad% is not more than 11.5% of the total mass of the fuel, the sulfur content St, d% is not more than 0.8% of the total mass of the fuel, the volatile Vdaf% is not more than 1.2% of the total mass of the fuel, the crushing strength M40 is not less than 89.5%, the wear resistance M10 is not more than 6.5%, the reactivity CRI is 35-50%, and the post-reaction strength CSR is 35-42.5%;
raw fuel used by the blast furnace is weighed under a groove, is fed into the blast furnace from the furnace top through a conveying belt by a charging and distributing device at the furnace top of the blast furnace according to sequential batch circulation alternation of a coke bed layer and an iron-containing main raw material layer, so that reasonable distribution of edge airflow and center airflow is ensured, the center airflow is stabilized through a funnel with a certain depth, and meanwhile, stable and smooth edge airflow is obtained. In the material distribution process, the distance between a material level platform and a furnace throat steel brick is 300-400mm, the width of the material level platform is controlled to be about 1.5-2.0m, the depth of a central funnel is controlled to be 1.4-2.5 m, the material level shape is proper, and the material level is controlled to be 1.4-1.9m;
the decarburized coal gas at the blast furnace tuyere comprises the following specific components: the volume fraction of the decarbonized gas CO is 65-75%, H 2 Volume fraction of 10-20%, N 2 The volume fraction of CO2 and other components is 11-15%, the volume fraction of other gas components is 0.5-5%, the volume fraction of other gas components is 1-3%, the temperature of the blowing decarburization gas is 35-45 ℃, and the blowing amount is 100-250 Nm3/t iron;
specific parameters of the ultra-high oxygen enrichment, hot air and coal injection operation are as follows: the blast furnace blast temperature is 1150-1250 ℃, the volume of humidity in blast is 1.0-2.5%, the oxygen content in blast is 21-50%, the coal injection amount is 75-85 kg/t, and the smelting period is 6.5-8.5 h.
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