CN118109657A - Duplex smelting method for reducing carbon dioxide emission - Google Patents
Duplex smelting method for reducing carbon dioxide emission Download PDFInfo
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- CN118109657A CN118109657A CN202410115208.1A CN202410115208A CN118109657A CN 118109657 A CN118109657 A CN 118109657A CN 202410115208 A CN202410115208 A CN 202410115208A CN 118109657 A CN118109657 A CN 118109657A
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- 238000003723 Smelting Methods 0.000 title claims abstract description 80
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 title claims abstract description 64
- 238000000034 method Methods 0.000 title claims abstract description 56
- 229910002092 carbon dioxide Inorganic materials 0.000 title claims abstract description 32
- 239000001569 carbon dioxide Substances 0.000 title claims abstract description 32
- 229910000831 Steel Inorganic materials 0.000 claims abstract description 155
- 239000010959 steel Substances 0.000 claims abstract description 155
- 238000007664 blowing Methods 0.000 claims abstract description 107
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims abstract description 94
- 229910052799 carbon Inorganic materials 0.000 claims abstract description 90
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 83
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 83
- 239000001301 oxygen Substances 0.000 claims abstract description 83
- 238000010079 rubber tapping Methods 0.000 claims abstract description 28
- 230000000694 effects Effects 0.000 claims description 15
- 125000004122 cyclic group Chemical group 0.000 claims description 11
- 239000002893 slag Substances 0.000 claims description 11
- 229910052782 aluminium Inorganic materials 0.000 claims description 8
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 claims description 8
- 239000002245 particle Substances 0.000 claims description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 abstract description 64
- 229910052757 nitrogen Inorganic materials 0.000 abstract description 32
- 229910000976 Electrical steel Inorganic materials 0.000 abstract description 7
- 230000008569 process Effects 0.000 description 30
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 21
- 239000007788 liquid Substances 0.000 description 11
- 238000006243 chemical reaction Methods 0.000 description 10
- 229910052742 iron Inorganic materials 0.000 description 10
- 238000004090 dissolution Methods 0.000 description 9
- 239000002994 raw material Substances 0.000 description 9
- 239000007789 gas Substances 0.000 description 8
- 235000008733 Citrus aurantifolia Nutrition 0.000 description 7
- 235000011941 Tilia x europaea Nutrition 0.000 description 7
- 239000004571 lime Substances 0.000 description 7
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 6
- 229910002091 carbon monoxide Inorganic materials 0.000 description 6
- 238000004519 manufacturing process Methods 0.000 description 6
- 229910002804 graphite Inorganic materials 0.000 description 5
- 239000010439 graphite Substances 0.000 description 5
- 238000009628 steelmaking Methods 0.000 description 5
- 241001062472 Stokellia anisodon Species 0.000 description 4
- 238000007599 discharging Methods 0.000 description 4
- 238000010438 heat treatment Methods 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 229910052751 metal Inorganic materials 0.000 description 3
- 239000002184 metal Substances 0.000 description 3
- 239000000571 coke Substances 0.000 description 2
- 238000005261 decarburization Methods 0.000 description 2
- 238000005868 electrolysis reaction Methods 0.000 description 2
- 239000011261 inert gas Substances 0.000 description 2
- CSJDCSCTVDEHRN-UHFFFAOYSA-N methane;molecular oxygen Chemical compound C.O=O CSJDCSCTVDEHRN-UHFFFAOYSA-N 0.000 description 2
- 239000002699 waste material Substances 0.000 description 2
- MYMOFIZGZYHOMD-UHFFFAOYSA-N Dioxygen Chemical compound O=O MYMOFIZGZYHOMD-UHFFFAOYSA-N 0.000 description 1
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 238000005262 decarbonization Methods 0.000 description 1
- 230000003111 delayed effect Effects 0.000 description 1
- 238000010586 diagram Methods 0.000 description 1
- 238000009792 diffusion process Methods 0.000 description 1
- 229910001882 dioxygen Inorganic materials 0.000 description 1
- 238000009826 distribution Methods 0.000 description 1
- 238000007667 floating Methods 0.000 description 1
- 230000006698 induction Effects 0.000 description 1
- 230000003993 interaction Effects 0.000 description 1
- 239000000155 melt Substances 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- QMQXDJATSGGYDR-UHFFFAOYSA-N methylidyneiron Chemical compound [C].[Fe] QMQXDJATSGGYDR-UHFFFAOYSA-N 0.000 description 1
- 239000000203 mixture Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 229910052698 phosphorus Inorganic materials 0.000 description 1
- 239000011574 phosphorus Substances 0.000 description 1
- 230000009467 reduction Effects 0.000 description 1
- 238000003756 stirring Methods 0.000 description 1
- 238000006467 substitution reaction Methods 0.000 description 1
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Abstract
The application discloses a duplex smelting method for reducing carbon dioxide emission, which solves the technical problem of high carbon dioxide emission in the prior art. The duplex smelting method for reducing carbon dioxide emission provided by the application comprises the following steps: adding scrap steel into an electric furnace for smelting, and tapping into a converter with a preset carbon source to obtain molten steel; adopting first flow and second flow to circularly and alternately pulse bottom blowing to the molten steel, and blowing oxygen at the top of an oxygen lance in the latter half stage of the circularly and alternately pulse bottom blowing to finish duplex smelting; wherein the first flow is less than the second flow. The duplex smelting method provided by the application has low carbon dioxide emission, and the nitrogen content of molten steel obtained by converter smelting tapping is low, so that the nitrogen content requirements of high-quality automobile plates and electrical steel are met.
Description
Technical Field
The application belongs to the technical field of steelmaking, and particularly relates to a duplex smelting method for reducing carbon dioxide emission.
Background
The requirements of high-quality steel for automobile plates, electrical steel and the like on nitrogen content are extremely high, the nitrogen content of a general finished product is not more than 0.0030 percent, and the lower the nitrogen content in the product is, the better the stamping forming performance is, and the higher the yield is.
In the prior art, steel for automobile plates, electrical steel and the like with high requirements for nitrogen content are usually produced by adopting a conventional blast furnace-converter process, but the blast furnace ironmaking-converter steelmaking process can cause large CO 2 emission in the converter steelmaking process, and the low-carbon green development requirements are not met.
Therefore, there is a need for a low carbon dioxide emission smelting process.
Disclosure of Invention
The application provides a duplex smelting method for reducing carbon dioxide emission, which aims to solve the technical problem of high emission of CO 2 in the conventional blast furnace-converter smelting process.
The application provides a duplex smelting method for reducing carbon dioxide emission, which comprises the following steps:
adding scrap steel into an electric furnace for smelting, and tapping into a converter with a preset carbon source to obtain molten steel;
Adopting first flow and second flow to circularly and alternately pulse bottom blowing to the molten steel, and blowing oxygen at the top of an oxygen lance in the latter half stage of the circularly and alternately pulse bottom blowing to finish duplex smelting; wherein the first flow is less than the second flow.
In some embodiments, the first flow rate is 0.08-0.12Nm 3/min/t; the second flow rate is 0.12-0.2Nm 3/min/t.
In some embodiments, the lance position when the flow rate of the cyclically alternating pulse bottom blowing is a first flow rate is less than the lance position when the flow rate of the cyclically alternating pulse bottom blowing is a second flow rate.
In some embodiments, the oxygen lance position is 1.8-2.0m when the flow rate of the cyclic alternating pulse type bottom blowing is the first flow rate; and when the flow of the circulating alternate pulse type bottom blowing is the second flow, the lance position of the oxygen lance is 2.0-2.2m.
In some embodiments, in the cyclically alternating pulse bottom blowing, the switching period of the first flow rate and the second flow rate is 20-45s.
In some embodiments, the total time of the cyclically alternating pulse bottom blowing is 14-22min and the time of top blowing oxygen is 10-15min.
In some embodiments, the top-blown oxygen has an intensity of 3.0 to 3.8Nm 3/min/t.
In some embodiments, aluminum is added to the molten steel during tapping from the electric furnace to the converter to control the activity of oxygen in the molten steel to be 0.02% -0.03%.
In some embodiments, the mass of the carbon source preset in the converter is 20-25kg/t, and the particle size of the carbon source is 1-3 mm.
In some embodiments, in the latter half of the cycle of alternate pulse bottom blowing, a slag former is added into the converter, and then oxygen is blown by the oxygen lance.
The duplex smelting method for reducing carbon dioxide emission provided by the embodiment of the application comprises the following steps: adding scrap steel into an electric furnace for smelting, and tapping into a converter with a preset carbon source to obtain molten steel; adopting first flow and second flow to circularly and alternately pulse bottom blowing to the molten steel, and blowing oxygen at the top of an oxygen lance in the latter half stage of the circularly and alternately pulse bottom blowing to finish duplex smelting; wherein the first flow is less than the second flow. The application adopts scrap steel as raw material to replace blast furnace molten iron in the prior art, and the converter steelmaking does not need to remove a large amount of carbon in the molten iron, thereby reducing the discharge amount of carbon dioxide. In addition, the application adopts the duplex technology of electric furnace and scrap steel, a carbon source is preset in the converter, a circulating alternate pulse type bottom blowing mode of converter smelting is controlled, the full mixing of carbon and molten steel is promoted, oxygen is blown at the top of the latter half stage of circulating alternate pulse type bottom blowing, and the carbon source dissolved in the molten steel reacts with the oxygen to form carbon monoxide bubbles, so that nitrogen in the molten steel entering a metal molten pool through heating and electrolysis of an electric furnace smelting electrode is discharged, the nitrogen content in the molten steel after converter tapping is reduced, and the requirements of the nitrogen content of high-quality steel for automobile plates, electrical steel and the like are met.
Drawings
FIG. 1 illustrates a process step diagram of a duplex smelting process for reducing carbon dioxide emissions in one or more embodiments of the application.
Detailed Description
In order to make the present application more clearly understood by those skilled in the art, the technical solutions of the embodiments of the present application will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present application, and it is apparent that the described embodiments are only some embodiments of the present application, not all embodiments. All other embodiments, which can be made by those skilled in the art based on the embodiments of the application without making any inventive effort, are intended to be within the scope of the application.
The embodiment of the application provides a duplex smelting method for reducing carbon dioxide emission, which adopts duplex smelting means of an electric furnace and a converter, reduces the emission amount of carbon dioxide, presets a carbon source in the converter in advance, reduces nitrogen elements introduced by electric furnace smelting, and realizes the control of the low nitrogen content of molten steel at the end point of the converter.
Referring to fig. 1, the duplex smelting method for reducing carbon dioxide emission provided by the embodiment of the application includes the following steps:
S1, adding scrap steel into an electric furnace for smelting, and tapping into a converter with a preset carbon source to obtain molten steel;
S2, circularly and alternately pulse-type bottom blowing is adopted for the molten steel at a first flow rate and a second flow rate, and oxygen is blown out from the top of an oxygen lance in the latter half stage of the circularly and alternately pulse-type bottom blowing, so that duplex smelting is completed; wherein the first flow is less than the second flow.
The electric furnace takes scrap steel or direct reduced iron as raw materials, and heats and melts the raw materials to form molten steel. Oxygen can be blown into the electric furnace generally, the smelting effect is improved, and the carbon content at the end point of the electric furnace is not more than 0.1 percent. The electric furnace can be an arc furnace, an induction furnace and the like. The converter generally takes scrap steel and molten iron as raw materials, and the scrap steel and the molten iron are smelted into molten steel meeting requirements through oxygen blowing, and the scrap steel ratio of the converter is generally not more than 20 percent because the heat source of the converter mainly comes from heating elements in the molten iron.
In the application, firstly, the scrap steel is used as a raw material to smelt molten steel, and then the molten steel is poured into a converter to smelt, so that the duplex smelting process of the electric furnace-converter is formed, the scrap steel ratio of the duplex smelting process is 100%, and the carbon dioxide emission generated by the reaction of molten iron carbon and oxygen in the traditional converter smelting is reduced. The smelting period of the electric furnace is 40-50min and is matched with that of the converter, and the production efficiency is high.
Because the electric furnace heats the scrap steel by adopting the electrode, nitrogen in the air near the electrode is electrolyzed into a metal molten pool, so that the molten steel formed by the electric furnace after heating and melting the scrap steel contains a large amount of nitrogen elements, and a carbon source is added into the converter in advance and can react with oxygen blown into the converter to form CO bubbles, and the generated CO bubbles can bring out dissolved nitrogen in the molten steel in the process of upwards moving and escaping from the molten steel, so that the nitrogen content in the molten steel is reduced.
The carbon source may be graphite, coke, or the like, and is easily scattered due to its low density. Therefore, the carbon source is arranged in the converter in advance, and then molten steel in the electric furnace is tapped into the converter, so that the carbon source can be prevented from scattering to a certain extent, more carbon source is dissolved in the molten steel, and the carbon source remained on the surface of the molten steel is reduced. And CO bubbles formed by the reaction of the oxygen blown by the converter and the carbon source in the molten steel in the latter half stage of the cyclic alternating pulse bottom blowing float upwards, so that the nitrogen removal effect of the molten steel is improved. If molten steel in the electric furnace is tapped into the converter, then a carbon source is added, and the carbon source mainly stays on the surface of the molten steel, so that the difficulty of entering the molten steel by the carbon source in the smelting stage of the converter is increased, and the nitrogen removal effect is reduced.
The converter smelting stage adopts cyclic alternating pulse type bottom blowing, that is to say, alternating bottom blowing with first flow and second flow, for example, first adopting first flow bottom blowing for t min, then switching to second flow bottom blowing for t min, then switching back to first flow bottom blowing for t min, and alternately circulating. Because the first flow is smaller than the second flow, the molten steel in the converter is alternately subjected to bottom blowing with high bottom blowing strength and low bottom blowing strength.
The following overall process analysis for the whole cycle alternating pulse bottom blowing:
In the first half stage of the cyclic alternating pulse type bottom blowing, oxygen is not blown by an oxygen lance, when inert gas with high bottom blowing strength acts on molten steel, the liquid level of the molten steel is disturbed, part of carbon sources remained on the surface of the molten steel can be involved in the molten steel, the dissolution degree of carbon in the molten steel is increased, and the carbon sources which are not involved in the molten steel on the surface of the molten steel can be pushed to be close to the converter wall due to high bottom blowing strength. When inert gas with low bottom blowing strength acts on molten steel, the liquid level of the molten steel is calm, so that a carbon source pushed to be close to the converter wall under high bottom blowing strength is flatly paved on the surface of the molten steel again, and the carbon source can be involved in the molten steel to promote carbon dissolution during high-flow bottom blowing. The secondary high bottom blowing strength acts on the molten steel to enable the carbon source which is paved on the liquid surface again to be rolled into the molten steel again, and the two flow rates alternately circulate the bottom blowing, so that the contact area of the carbon source and the molten steel is increased, and the dissolution and diffusion efficiency of the carbon source into the molten steel is improved. Therefore, the circulation and alternation pulse type bottom blowing can increase the dynamic condition of the carbon source dissolved in the molten steel, and more effectively increase the dissolution degree of the carbon in the molten steel.
In the latter half stage of the cyclic alternating pulse type bottom blowing, oxygen is blown by an oxygen lance, so that the oxygen and a carbon source dissolved in molten steel in the former half stage are subjected to chemical reaction to form nitrogen-discharging CO bubbles, and the cyclic alternating pulse type bottom blowing can further lead the carbon source paved on the surface of the molten steel to be involved in the molten steel and react with the oxygen to form the nitrogen-discharging CO bubbles. The original carbon in the molten steel can be removed by oxygen blowing, so that the carbon content of the end point is below 0.06%.
According to the application, the carbon source is preset in the converter, so that more carbon sources are ensured to be dissolved in molten steel, the carbon source is accelerated to be dissolved in the molten steel by being matched with the circulating alternate pulse type bottom blowing, the efficiency and uniformity of carbon dissolution in the molten steel are improved, and meanwhile, a large number of nitrogen-discharging CO bubbles are formed by being matched with the oxygen lance in the latter half stage of the circulating alternate pulse type bottom blowing, and the denitrification effect is ensured.
In some embodiments, the first flow rate is 0.08-0.12Nm 3/min/t, e.g., 0.09Nm 3/min/t,0.10Nm3/min/t or 0.11Nm 3/min/t; at a flow rate of 0.08-0.12Nm 3/min/t, the bottom blowing does not disturb the liquid surface basically, and the main purpose is to enable the carbon source pushed to be close to the converter wall to be spread on the surface of molten steel again, and to enable the carbon source in the molten steel to be uniformly distributed in the molten steel. If the first flow is too large, the carbon source pushed to be close to the converter wall is difficult to be completely spread on the surface of the molten steel, so that the carbon source involved in the molten steel during high-strength bottom blowing is reduced, and the efficiency of dissolving the carbon source in the molten steel is affected. If the first flow rate is too small, the efficiency of the uniformity of the distribution of the carbon source in the molten steel is lowered to some extent.
In some embodiments, the second flow rate is 0.12-0.2Nm 3/min/t, e.g. 0.13Nm 3/min/t,0.14Nm3/min/t or 0.18Nm 3/min/t, etc., the second flow rate is a large flow rate, at a flow rate of 0.12-0.2Nm 3/min/t, such that the carbon source of the liquid surface is involved in the molten steel. If the second flow is too large, energy waste is caused to some extent. If the second force is too small, the effect of the carbon source being involved in the molten steel is weakened to some extent, which is disadvantageous in improving the efficiency of the carbon source being dissolved in the molten steel.
In some embodiments, in the latter half of the cycle of the pulse-type bottom blowing, the lance position of the oxygen lance is matched with the cycle of the pulse-type bottom blowing, that is, the lance position of the oxygen lance when the flow rate of the cycle of the pulse-type bottom blowing is the first flow rate is smaller than the lance position of the oxygen lance when the flow rate of the cycle of the pulse-type bottom blowing is the second flow rate, that is, the low bottom blowing strength corresponds to the low lance position and the high bottom blowing strength corresponds to the high lance position.
The lance position refers to the distance from the nozzle of the oxygen lance to the liquid level of the molten pool, namely the liquid level of the molten steel in the converter, and the nozzle of the oxygen lance and the liquid level of the molten steel are separated by a small distance when the bottom blowing strength is low, so that the fluidity of the upper part of the molten steel is mainly improved, carbon monoxide bubbles formed by the reaction of oxygen and carbon in the molten steel are concentrated on the central part of the liquid level of the molten steel, and at the moment, more slag and carbon sources are concentrated. When the high bottom blowing strength is achieved, the high oxygen lance position is adopted, the distance between the nozzle of the oxygen lance and the liquid level of molten steel is large, the fluidity of the underwater part of the molten steel is mainly improved, carbon monoxide bubbles formed by the reaction of oxygen and carbon in the molten steel are involved in part in the molten steel, the slag and the carbon source in the center of the liquid level of the molten steel are desulfurized, the carbon source is dissolved in the molten steel, and then the slag and the carbon source are gradually distributed on the furnace wall close to the converter. Thus, in addition to this, oxygen gas reacts exothermically with a small amount of carbon at the molten steel level in the latter half, and dephosphorization of slag.
That is, in the latter half stage of the cyclic alternating pulse type bottom blowing, the lance position of the oxygen lance is matched with the pulse type bottom blowing, namely, the high lance position corresponds to the high-strength bottom blowing, and the low lance position corresponds to the low-strength bottom blowing, so that the following three effects can be realized: 1. stirring the molten steel to enable carbon and oxygen in the molten steel to react to form carbon monoxide, and floating carbon monoxide bubbles to take away nitrogen. 2. Part of residual carbon source which is not completely dissolved on the surface of molten steel is gradually involved in the molten steel to participate in the carbon-oxygen reaction to remove nitrogen, and the other part directly reacts with oxygen on the surface of molten steel to release heat. 3. Realizes normal smelting of the converter, decarburization of molten steel and dephosphorization of steel slag.
In some embodiments, the oxygen lance position is 1.8-2.0m when the flow rate of the cyclic alternating pulse type bottom blowing is the first flow rate; and when the flow of the circulating alternate pulse type bottom blowing is the second flow, the lance position of the oxygen lance is 2.0-2.2m.
In some embodiments, the top-blown oxygen has an intensity of 3.0-3.8Nm 3/min/t.
In some embodiments, in the cyclically alternating pulse type bottom blowing, the switching period of the first flow and the second flow is 20-45s, that is, the first flow is switched to the second flow for 20-45s after the bottom blowing of the first flow for 20-45s, and then switched back to the first flow for alternate circulation. Too large or too small a switching period will reduce the efficiency of carbon dissolution in molten steel to some extent.
In some embodiments, the total time of the cycle alternating pulse bottom blowing is 14-22min, and the time of the latter half stage of the cycle alternating pulse bottom blowing, i.e. the time of top blowing oxygen is 10-15min, so that the bottom blowing time of the cycle alternating pulse bottom blowing without oxygen lance is 4-7min only, i.e. the first half stage of the cycle alternating pulse bottom blowing is shorter than the second half stage. The carbon source can be rapidly dissolved by adopting the simple circulation and alternation pulse type bottom blowing in a shorter time, and the nitrogen content of molten steel at the end point of the converter is reduced by adopting the long-time circulation and alternation pulse type bottom blowing and top blowing oxygen in combination, so that normal converter smelting is not delayed.
The application also comprises blanking, discharging and the like, the total time of the converter process is 40-45min, the electric furnace smelting time is 40-45min, the smelting periods of the two are matched, and the production efficiency is high.
In some embodiments, aluminum is added to the molten steel during tapping from the electric furnace to the converter to control the activity of oxygen in the molten steel to be 0.02-0.03%, i.e., 200-300 ppm. Adding aluminum for deoxidization in the tapping process, and controlling the oxygen activity after deoxidization, namely the dissolved oxygen in molten steel to be 200-300ppm, so as to ensure the operation safety of the electric furnace when tapping to a converter. If the activity of the oxygen discharged from the electric furnace is too high, the oxygen in the molten steel can react with a carbon source arranged in the converter severely to influence the operation safety when the electric furnace is discharged into the converter to a certain extent.
In some embodiments, the mass of the carbon source preset in the converter is 20-25kg/t, and the particle size of the carbon source is 1-3 mm. The adding amount of the carbon source is 20-25kg/t, namely, the adding amount of the carbon source is 20-25kg per ton of steel, and the control of the adding amount of the carbon source not only ensures the denitrification requirement, but also ensures that the endpoint temperature of the converter meets the smelting requirement. The particle diameter of the carbon source is controlled to be 1 mm-3 mm, so that the carbon source is easy to be remained in molten steel and has large reaction surface area. If the particle size of the carbon source is too large, the reaction rate of the carbon source and oxygen is reduced to a certain extent; if the grain size of the carbon source is too small, the carbon source is scattered outside the converter in the process of tapping from the electric furnace to the converter to a certain extent, and waste is caused.
In some embodiments, the end point oxygen activity of the electric furnace smelting is 0.03% to 0.05%.
In some embodiments, in the latter half of the cycle of the pulse-type bottom blowing, a slag former is added into the converter, and then oxygen is blown by the oxygen lance, that is to say, in the former half of the cycle of the pulse-type bottom blowing, the carbon source dissolution stage is mainly used, and the latter half of the cycle of the pulse-type bottom blowing is used for carbon-oxygen reaction, further dissolution of residual carbon source and dephosphorization and decarbonization of the converter. The slag former comprises lime which can remove phosphorus in molten steel.
In some embodiments, the electric furnace tapping temperature is 1600-1640 ℃, the converter end temperature is 1620-1680 ℃, and the converter end temperature is consistent with the converter end temperature under a traditional blast furnace-converter process.
In the application, firstly, the scrap steel is used as the raw material to smelt into molten steel, and then the molten steel is poured into a converter to smelt, thus forming the duplex smelting process of the electric furnace-converter, wherein the scrap steel ratio of the duplex smelting process is 100%, and the carbon dioxide emission of the traditional blast furnace and converter smelting is reduced. The smelting period of the electric furnace is 38-42min and is matched with that of the converter, and the production efficiency is high. The process of adding carbon and then blowing oxygen for decarburization is adopted, so that the nitrogen content of molten steel at the smelting end point of the converter is reduced, and the end point temperature and carbon content requirements are also ensured.
The duplex smelting method for reducing carbon dioxide emission provided by the embodiment of the application is further described below by referring to the examples.
Example 1
The smelting steel is steel for automobile plates, the ladle capacity is 200t, the smelting process comprises electric furnace smelting and converter smelting, and the method for producing the steel comprises the following steps:
An electric furnace smelting process comprises the following steps: smelting full scrap steel, wherein 188 tons of scrap steel is adopted; in the smelting process of the electric furnace, graphite blocks are added into the bottom of the converter, the addition amount is 22kg/t, and the granularity is 1-3mm. And tapping from the electric furnace to the converter with the graphite blocks added at the bottom, adding aluminum for deoxidization in the tapping process, and taking 38 minutes for electric furnace treatment after deoxidization, wherein the oxygen activity of molten steel is 273 ppm. Tapping from electric furnace
The converter adopts 0.09Nm 3/min/t and 0.18Nm 3/min/t of circulating alternating pulse type bottom blowing Ar gas, the total bottom blowing time is 18min, and the bottom blowing time of each flow is 35s. Lime is added when the Ar gas is circularly and alternately pulsed and bottom-blown for 5min, and then oxygen is blown by an oxygen lance for 13min. Wherein:
The lime addition amount was 22kg/t and the oxygen supply strength was 3.3Nm 3/min/t. When the bottom blowing Ar gas flow is 0.09Nm 3/min/t, the oxygen lance position is 1.9m, and when the bottom blowing Ar gas flow is 0.18Nm 3/min/t, the oxygen lance position is 2.1m;
the converter tapping and aluminum adding deoxidization, and the total time of converter treatment (including cyclic alternating pulse bottom blowing, tapping, slag splashing protection and the like) is 40min.
The content of N in the molten steel after tapping of the converter is 0.0013%, the content of C is 0.023%, and compared with the traditional converter smelting which takes scrap steel and molten iron as raw materials, the emission of CO 2 is reduced by 550kg/t.
Example 2
The smelting steel is electrical steel, the ladle capacity is 210t, the smelting process is electric furnace smelting-converter smelting, and the method for producing the steel comprises the following steps:
An electric furnace smelting process comprises the following steps: smelting full scrap steel, wherein 205 tons of scrap steel is adopted; in the electric furnace smelting process, coke blocks are added into the bottom of the converter, the addition amount is 23kg/t, and the granularity is 1-3mm. And tapping from the electric furnace to the converter with graphite blocks added at the bottom, adding aluminum for deoxidization in the tapping process, and taking 39min for electric furnace treatment after deoxidization, wherein the oxygen activity of molten steel is 245 ppm. Tapping from electric furnace
The converter adopts 0.11Nm 3/min/t and 0.19Nm 3/min/t of circulating alternating pulse type bottom blowing Ar gas, the total bottom blowing time is 19min, and the bottom blowing time of each flow is 40s. Lime is added when the Ar gas is circularly and alternately pulsed and bottom-blown for 6min, and then oxygen is blown by an oxygen lance for 13min. Wherein:
Lime is added at 23kg/t and the oxygen supply strength is 3.5Nm 3/min/t. When the bottom blowing Ar gas flow is 0.11Nm 3/min/t, the oxygen lance position is 1.8m, and when the bottom blowing Ar gas flow is 0.19Nm 3/min/t, the oxygen lance position is 2.2m;
the converter tapping and aluminum adding deoxidization, and the total time of converter treatment (including cyclic alternating pulse bottom blowing, tapping, slag splashing protection and the like) is 40min.
The content of N in the molten steel after tapping of the converter is 0.0012%, the content of C is 0.023%, and compared with the traditional converter smelting which takes scrap steel and molten iron as raw materials, the emission of CO 2 is reduced by 420kg/t.
Examples 3 to 5
Examples 3 to 5 refer to example 1, the same process route was adopted, the process parameters of each step are shown in table 1 and table 2, the nitrogen content and carbon content in the molten steel after tapping in the converter are shown in table 3, and the process parameters not mentioned in table 1 and table 2 of examples 3 to 5 are the same as example 1.
TABLE 1
TABLE 2
TABLE 3 Table 3
| Numbering device | Nitrogen content/% | Carbon content of molten steel/% | Scrap ratio/% |
| Example 1 | 0.0013 | 0.023 | 100％ |
| Example 2 | 0.0012 | 0.023 | 100％ |
| Example 3 | 0.0013 | 0.022 | 100％ |
| Example 4 | 0.0014 | 0.021 | 100％ |
| Example 5 | 0.0011 | 0.026 | 100％ |
As can be seen from the data in Table 3, the duplex smelting method provided by the embodiments 1 to 5 of the application has the advantages that the nitrogen content in the molten steel after the steel is smelted by the converter is 11-14ppm, the nitrogen content is low, the nitrogen content requirement of high-quality automobile plates and electrical steel is met, the scrap steel ratio reaches 100%, and the emission of carbon dioxide is reduced.
The duplex smelting method for reducing carbon dioxide emission, which is improved by the application, has at least the following advantages:
(1) The application adopts scrap steel as raw material to replace blast furnace molten iron in the prior art, and the converter steelmaking does not need to remove a large amount of carbon in the molten iron, thereby reducing the discharge amount of carbon dioxide. The duplex smelting method provided by the application can reduce the CO 2 emission amount per ton of steel to 0.4-0.6 ton and the CO 2 emission amount to 70-80% by adopting the blast furnace to discharge 1.6-2.0 ton of CO 2.
(2) The application adopts the duplex technology of electric furnace and scrap steel, a carbon source is preset in the converter, a circulating alternate pulse type bottom blowing mode of converter smelting is controlled, the full mixing of carbon and molten steel is promoted, oxygen is blown at the top of the latter half stage of circulating alternate pulse type bottom blowing, and the carbon source dissolved in the molten steel reacts with the oxygen to form carbon monoxide bubbles, so that nitrogen entering a metal molten pool through heating and electrolysis of an electric furnace smelting electrode is discharged, the nitrogen content in the molten steel after converter tapping is reduced, and the requirements of high-quality steel for automobile plates, electrical steel and the like on the nitrogen content are met.
(3) The application adopts the combination of high gun position high bottom blowing strength and low gun position low bottom blowing strength, improves the dynamic condition of dissolving carbon source in molten steel, more effectively increases the dissolution degree of carbon in molten steel, utilizes CO bubbles produced by dissolved carbon and top blowing oxygen to promote the reduction of the nitrogen content of molten steel, realizes the control of the low nitrogen content of molten steel, and solves the problem of high nitrogen content in electric furnace smelting.
(4) The end point of the electric furnace adopts an Al deoxidization process, so that the safety of the oxygen activity of molten steel and the preset graphite reaction at the bottom of the converter is ensured.
(5) Compared with the converter smelting by molten iron, the lime used in the converter is 10-18kg/t, which is lower than the lime consumption (20-35 kg/t) by adopting a blast furnace and converter duplex process.
(6) The application adopts a duplex technology of an electric furnace and a converter, and the blowing end point of the converter is the same as the composition and the temperature of the molten steel at the end point of the converter in the traditional process of blast furnace and converter. The total time of the electric furnace and converter duplex process is 78-80min, which is far lower than the production period of the blast furnace and converter.
In the present application, unless expressly stated or limited otherwise, a first feature "above" or "below" a second feature may include both the first and second features being in direct contact, as well as the first and second features not being in direct contact but being in contact with each other through additional features therebetween. Moreover, a first feature being "above," "over" and "on" a second feature includes the first feature being directly above and obliquely above the second feature, or simply indicating that the first feature is higher in level than the second feature. The first feature being "under", "below" and "beneath" the second feature includes the first feature being directly under and obliquely below the second feature, or simply means that the first feature is less level than the second feature.
In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise" indicate orientations or positional relationships are based on the orientations or positional relationships shown in the drawings, are merely for convenience in describing the present application and simplify the description, and do not indicate or imply that the devices or elements referred to must have a specific orientation, be configured and operated in a specific orientation, and therefore should not be construed as limiting the present application.
In the present application, unless specifically stated and limited otherwise, the terms "connected," "affixed," and the like are to be construed broadly, and for example, "affixed" may be a fixed connection, a removable connection, or an integral body; can be mechanically or electrically connected; can be directly connected or indirectly connected through an intermediate medium, and can be communicated with the inside of two elements or the interaction relationship of the two elements. The specific meaning of the above terms in the present application can be understood by those of ordinary skill in the art according to the specific circumstances.
Furthermore, descriptions such as those referred to as "first," "second," and the like, are provided for descriptive purposes only and are not to be construed as indicating or implying a relative importance or implying an order of magnitude of the indicated technical features in the present disclosure. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more features. In the description of the present application, the meaning of "a plurality" is two or more, unless explicitly defined otherwise.
While embodiments of the present application have been shown and described, it will be understood by those of ordinary skill in the art that: many changes, modifications, substitutions and variations may be made to the embodiments without departing from the spirit and principles of the application, the scope of which is defined by the claims and their equivalents.
Claims (10)
1. The duplex smelting method for reducing carbon dioxide emission is characterized by comprising the following steps of:
adding scrap steel into an electric furnace for smelting, and tapping into a converter with a preset carbon source to obtain molten steel;
Adopting first flow and second flow to circularly and alternately pulse bottom blowing to the molten steel, and blowing oxygen at the top of an oxygen lance in the latter half stage of the circularly and alternately pulse bottom blowing to finish duplex smelting; wherein the first flow is less than the second flow.
2. The duplex smelting method for reducing carbon dioxide emissions according to claim 1, wherein the first flow is 0.08-0.12Nm 3/min/t; the second flow rate is 0.12-0.2Nm 3/min/t.
3. The duplex smelting method for reducing carbon dioxide emission according to claim 2, wherein the lance position of the lance when the flow rate of the cycle alternating pulse bottom blowing is a first flow rate is smaller than the lance position of the lance when the flow rate of the cycle alternating pulse bottom blowing is a second flow rate.
4. The duplex smelting method for reducing carbon dioxide emission according to claim 3, wherein the lance position of the oxygen lance when the flow rate of the circulating alternate pulse type bottom blowing is the first flow rate is 1.8-2.0m; and when the flow of the circulating alternate pulse type bottom blowing is the second flow, the lance position of the oxygen lance is 2.0-2.2m.
5. The duplex smelting method for reducing carbon dioxide emissions according to any of claims 1-4, wherein in the cyclically alternating pulse bottom blowing, the switching period of the first flow rate and the second flow rate is 20-45s.
6. The duplex smelting method for reducing carbon dioxide emissions according to any of claims 1-4, wherein the total time of the cycle of alternating pulse bottom blowing is 14-22min, and the time of top blowing oxygen is 10-15min.
7. The duplex smelting method for reducing carbon dioxide emissions according to any of claims 1-4, wherein the top-blown oxygen has a strength of 3.0-3.8Nm 3/min/t.
8. The duplex smelting method for reducing carbon dioxide emissions according to any of claims 1-4, wherein aluminum is added to molten steel during tapping from the electric furnace to the converter to control the activity of oxygen in the molten steel to be 0.02% to 0.03%.
9. The duplex smelting method for reducing carbon dioxide emissions according to any of claims 1-4, wherein the mass of carbon source preset in the converter is 20-25kg/t, and the particle size of the carbon source is 1-3 mm.
10. The duplex smelting method for reducing carbon dioxide emissions according to any of claims 1-4, wherein in the latter half of the cyclic alternating pulse bottom blowing, a slag former is added to the converter prior to top blowing oxygen by the oxygen lance.
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