CN102220448A - Method for smelting uniform end-point molten steel composition with converter - Google Patents
Method for smelting uniform end-point molten steel composition with converter Download PDFInfo
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Abstract
The invention relates to a method for smelting uniform end-point molten steel composition with a converter and belongs to the technical field of converter steelmaking. The method is realized by nitrogen blowing and stirring through utilizing a converter oxygen gun at a smelting end point and comprises the following steps of: enabling a converter to carry out normal oxygen blowing smelting; after reaching the smelting end point, switching the top-blown gas from oxygen to the nitrogen, wherein the nitrogen supply intensity is 3.0-4.0Nm<3>/h.t steel and the nitrogen blowing time is 5-30 seconds; according to the nitrogen blowing time, properly raising a carbon catching temperature by 10-60 DEG C; and after the nitrogen blowing is finished, taking a sample to check, and tapping if the composition is qualified. According to the method disclosed by the invention, under the existing conditions and without adding new equipment, the problem of loss caused by an inaccurate check result which is resulted from non-uniform molten steel composition is solved, the operation is convenient, the method is simple, the cost is not additionally increased, the phosphor, sulfur and the like contained in the steel are further removed, the degree of per-oxidation of the molten steel is reduced, the steel material consumption is reduced, the cleanness of the molten steel is promoted, and the phenomena of per-oxidation of the molten steel, increase in steel material and deoxidant, and the like which are caused by an original oxygen re-blowing process are avoided.
Description
Technical field
The invention belongs to the converter steeling technology field, particularly relate to the method for the even endpoint molten steel composition of a kind of converter smelting, be particularly useful for the smelting endpoint molten steel composition is had the steel grade of strict demand.
Background technology
Converter current steel-making is the process for making of widespread usage, have plurality of advantages such as efficient height, rhythm is fast, output is big, power consumption is little, for general steel grade, after finishing, converter smelting gets final product direct pouring through simple processing or external refining, and for high level steel grade, then will be after converter smelting finishes through just casting after the complicated external refining.Though but adopt which kind of operational path, the composition of converter smelting endpoint will directly influence the refining or the casting of postorder, therefore guarantee that the accuracy of converter smelting endpoint molten steel composition has crucial effects.
Converter generally all adopts the top-blown oxidation method to smelt, because the influence of heat size, the type of furnace and top blast system, molten steel composition is not fully uniformly in converter, especially low-carbon (LC) and ultralow-carbon steel grade, because the oxidisability of molten steel and slag is very strong, therefore, converter smelting endpoint is materialsed and can not well be represented molten steel composition in the stove, so also just caused and detected the inaccuracy of composition, and then influenced the postorder processing.Also there are some converters to adopt top and bottom complex blowing technology in recent years, make the smelting cycle of converter that to a certain degree shortening be arranged, especially end-point control method there is better action, but since the bottom blowing effect be difficult to stable guarantee and bottom blowing intensity on the low side, so evenly still can't the guaranteeing of converter smelting endpoint molten steel composition.In actual production in order to prevent thus the industrial accident that causes, the general excessive oxygen blast or the oxygen of re-blowing of adopting guarantees that carbon content of molten steel and phosphorus content etc. meet the demands, and has just caused the peroxidation of molten steel, the increase that iron and steel stock consumes, a series of adverse consequencess such as erosion of converter lining like this.
Application (patent) number provides a kind of method of oxygen nitrogen top blast dephosphorization for 03128987.8 invention.It mainly is the dephosphorization stage in early stage that is applied in converter two one-step steelmaking process, in top and bottom combined blown converter, adopt top blowing oxygen nitrogen, bottom blowing nitrogen or other rare gas element to carry out dephosphorization treatment, the top rifle has two kinds of source of the gas master modes, carries out oxygen nitrogen and mix and to blow or oxygen nitrogen intermittently blows in dephosphorization oxygen blast process.When the slag peroxidation will cause big splash, adopt oxygen nitrogen top blast mode, top blow oxygen lance switches to the nitrogen that full blows by the oxygen that full blows, or oxygen/nitrogen is mixed in proportion blowing, suppresses splash and strengthen the molten bath to stir, and improves the equilibrium kinetics condition of the phosphorus between the slag steel.This invention can also reach dephosphorization effect preferably when bottom blowing intensity is more weak.Can effectively suppress decarburizing reaction, the carbon content behind the dephosphorization of molten iron is improved, the recovery of manganese reaches more than 70% in the molten iron, for follow-up decarburization blowing creates favorable conditions.Improve the top air supply intensity simultaneously, add strong mixing, shorten time dephosphorization phase, improve dephosphorization rate.But for the last smelting endpoint molten steel composition of converter evenly and reduce to consume during terminal point and do not have any effect.Therefore in order to prevent because rate is smelt in the inhomogeneous influence of smelting endpoint molten steel composition, and reduce iron and steel stock consumption, the invention provides the even molten steel composition of a kind of converter smelting endpoint and reduce the method that consumes.
Summary of the invention
In order to overcome the above problems, the present invention aims to provide the even endpoint molten steel composition of a kind of converter smelting and reduces the method that consumes, and realizes by adopting the converter oxygen gun nitrogen flushing to stir at smelting endpoint.
The present invention realizes by following technical proposal:
1) the normal oxygen blast of converter is smelted, and after reaching smelting endpoint, top-blown gas is switched to nitrogen by oxygen;
2) the nitrogen top blast is for nitrogen intensity: 3.0～4.0Nm
3/ ht steel;
3) nitrogen flushing time: 5s～30s;
4) temperature control: according to nitrogen flushing time length, the catch carbon temperature suitably improves 10 ℃～60 ℃;
After nitrogen flushing finishes, inspection by sampling, composition is qualified can tap.
The present invention has following advantage and effect: it is inaccurate and the situation of rate is smelt in influence that bring 1) to have solved detected result that the molten steel composition inequality causes, has avoided the loss that brings thus; 2) utilize existing installation to need not newly to add any equipment; 3) easy and simple to handle, method is simple; 4) can further remove phosphorus, sulphur equal size in the steel to a certain extent; 5) reduce the Molten Steel over-oxidation degree, reduced iron and steel stock consumption; 6) reduce deoxidation products, improved steel quality; 7) Molten Steel over-oxidation, iron and steel stock and the reductor increase etc. of having avoided the former technology of re-blowing to bring.
Embodiment
The comparative example 1
Former technology:
Steel grade is pipe line steel X70, and the converter tapping amount is 100 tons, and production technique is " hot metal pretreatment-converter-ladle furnace refining-RH vacuum-treat-continuous casting ", and the converter tapping molten steel composition is set at: C%≤0.03%, P%≤0.006%, S%≤0.010%; The converter smelting endpoint sampling, the oxygen of re-blowing then, oxygen blast flow are 21000Nm
3/ h, oxygen supply intensity are 3.5Nm
3/ ht steel, oxygen blow duration is 15s, re-blows and gets three steel samples after finishing, the molten steel composition detected result is as shown in table 1.
The table 1 molten steel composition before and after the oxygen of re-blowing, mass percent %
| Re-blow before the oxygen | Sample 1# behind the oxygen re-blows | Sample 2# behind the oxygen re-blows | Sample 3# behind the oxygen re-blows | |
| ?C％ | 0.029 | 0.018 | 0.022 | 0.033 |
| ?P％ | 0.009 | 0.007 | 0.007 | 0.006 |
| ?S％ | 0.008％ | 0.008％ | 0.008％ | 0.009％ |
| Oxygen activity, ppm | 823 | 1338 | 1156 | 1020 |
| ?N，ppm | 21 | 22 | 23 | 20 |
| Liquid steel temperature | 1703 | 1728 | 1717 | 1709 |
The slag composition is detected, re-blows before the oxygen that FeO% is 22.4% in the slag, behind the oxygen of re-blowing in the slag FeO% be 26.5%.
The present invention:
Steel grade is pipe line steel X70, the converter tapping amount is 100 tons, production technique is " hot metal pretreatment-converter-ladle furnace refining-RH vacuum-treat-continuous casting ", the converter tapping molten steel composition is set at: C%≤0.03%, P%≤0.006%, S%≤0.010%, catch carbon temperature are set at 1710 ℃, improve 40 ℃ than former catch carbon temperature; The converter smelting endpoint sampling, the nitrogen of re-blowing then, nitrogen flushing flow is 21000Nm
3/ h is 3.50Nm for nitrogen intensity
3/ ht steel, the nitrogen flushing time is 15s, re-blows and gets three steel samples after finishing, the molten steel composition detected result is as shown in table 2.
The table 2 molten steel composition before and after the nitrogen of re-blowing, mass percent %
| Re-blow before the nitrogen | Sample 1# behind the nitrogen re-blows | Sample 2# behind the nitrogen re-blows | Sample 3# behind the nitrogen re-blows | |
| C％ | 0.028 | 0.026 | 0.027 | 0.027 |
| P％ | 0.009 | 0.007 | 0.006 | 0.007 |
| S％ | 0.008％ | 0.008％ | 0.007％ | 0.007％ |
| Oxygen activity, ppm | 851 | 626 | 658 | 643 |
| N，ppm | 20 | 22 | 23 | 21 |
| Liquid steel temperature, ℃ | 1708 | 1681 | 1678 | 1671 |
The slag composition is detected, re-blows before the oxygen that FeO% is 22.8% in the slag, behind the oxygen of re-blowing in the slag FeO% be 22.1%.
By above two kinds of technologies contrast as can be known, re-blowing, three sample carbon contents differ bigger behind the oxygen, the molten steel oxygen activity all has in various degree with the oxygen of re-blowing before to be increased, therefore the inhomogeneous and Molten Steel over-oxidation degree increase of molten steel composition in the converter is described, by FeO% contrast in the slag before and after the oxygen of re-blowing as can be known, re-blowing, FeO% increases by 4.1% behind the oxygen, illustrates that iron and steel stock content increases in the slag.And three sample carbon contents behind the nitrogen of re-blowing are very approaching, and oxygen activity all has in various degree and to reduce, and the FeO% in the slag behind the nitrogen of re-blowing also has slight reduction, illustrate that the Molten Steel over-oxidation degree decreases, and contained iron and steel stock reduce to some extent in the slag.
The nitrogen and the two kinds of technologies of oxygen of re-blowing of re-blowing all have dephosphorization effect to a certain degree, and nitrogen pick-up is not had influence substantially.
Embodiment 2
Steel grade BH smelts, heat size 100t, production technique is " hot metal pretreatment-converter-ladle furnace refining-RH vacuum-treat-continuous casting ", the converter tapping molten steel composition is set at: C%≤0.04%, P%≤0.015%, S%≤0.015%, the catch carbon temperature is set at 1700 ℃, improve 50 ℃ than former catch carbon temperature, the nitrogen of re-blowing behind the converter catch carbon, flow are 18500Nm
3/ h is 3.08Nm for nitrogen intensity
3/ ht steel, the time is 30s, and the catch carbon liquid steel temperature is 1702 ℃, and temperature is 1648 ℃ behind the nitrogen of re-blowing, catch carbon and re-blow back molten steel and slag composition shown in table 3 and table 4.Phosphorus, the sulphur content of re-blowing as can be known behind the nitrogen in the steel all has to a certain degree and reduces, and all iron content and ferrous oxide content also have to a certain degree and reduce in the slag.
Table 3 catch carbon and the back molten steel composition of re-blowing change wt%
Table 4 catch carbon and the back slag composition of re-blowing change wt%
| Slag specimen | TFe | FeO | SiO 2 | CaO | MgO | Al 2O 3 | MnO | P 2O 5 | S |
| The converter catch carbon | 17.45 | 14.51 | 13.14 | 44.56 | 12.28 | 1.03 | 2.32 | 1.55 | 0.072 |
| The nitrogen of re-blowing | 15.15 | 13.36 | 13.79 | 49.83 | 11.95 | 1.1 | 2.03 | 1.54 | 0.076 |
Embodiment 3
Steel grade Q245H, heat size 100t, production technique is " hot metal pretreatment-converter-ladle furnace refining-RH vacuum-treat-continuous casting ", the converter tapping molten steel composition is set at: C%≤0.06%, P%≤0.015%, S%≤0.015%, the catch carbon temperature is set at 1680 ℃, improve 30 ℃ than former catch carbon temperature, the nitrogen of re-blowing behind the converter catch carbon, flow are 20500Nm
3/ h is 3.42Nm for nitrogen intensity
3/ ht steel, the nitrogen flushing time is 17s, and the catch carbon liquid steel temperature is 1676 ℃, and temperature is 1645 ℃ behind the nitrogen of re-blowing, catch carbon and re-blow back molten steel and slag composition as shown in table 5 and table 6.Phosphorus, the sulphur content of re-blowing as can be known behind the nitrogen in the steel all has to a certain degree and reduces, and all iron content and ferrous oxide content also have to a certain degree and reduce in the slag.
Table 5 catch carbon and the back molten steel composition of re-blowing change wt%
Table 6 catch carbon and the back slag composition of re-blowing change wt%
| Slag specimen | TFe | FeO | SiO 2 | CaO | MgO | Al 2O 3 | MnO | P 2O 5 | S |
| The converter catch carbon | 18.01 | 16.09 | 13.08 | 46.54 | 11.94 | 1.1 | 2.44 | 1.47 | 0.08 |
| The nitrogen of re-blowing | 16.26 | 14.91 | 13.27 | 49.52 | 11.41 | 1.18 | 2.15 | 1.49 | 0.083 |
The comparative example 4
Former technology:
Certain steel grade is produced 178 stoves altogether, heat size 100t, production technique is " converter-ladle furnace refining-continuous casting ", and heat size is 100t, and terminal point is set C%≤0.03%, the employing oxygen control endpoint molten steel composition of re-blowing, actual carbon content average out to 0.022%, compliance rate are 100%, and ladle furnace refining arrives at a station and sets C%≤0.045%, actual carbon content average out to 0.043%, fluctuation range is 0.038%～0.047%, and compliance rate is 93%, and the ladle furnace refining nitrogen content that arrives at a station meets the demands.
The present invention:
Identical steel grade with former technology is produced 87 stoves altogether, heat size 100t, production technique is " converter-ladle furnace refining-continuous casting ", and heat size is 100t, and terminal point is set C%≤0.03%, the employing nitrogen control terminal point of re-blowing, actual carbon content average out to 0.027%, compliance rate are 100%, and ladle furnace refining arrives at a station and sets C%≤0.045%, actual carbon content average out to 0.044%, fluctuation range is 0.040%～0.046%, and compliance rate is 99%, and the ladle furnace refining nitrogen content that arrives at a station meets the demands.
Contrast two kinds of technologies as can be known, adopt the present invention after actual converter terminal carbon content obviously improve, the peroxidation degree that has reduced molten steel is described, and the ladle furnace refining carbon content compliance rate of arriving at a station improved 6%, improved the control accuracy of composition.
Claims (1)
1. the method for the even endpoint molten steel composition of converter smelting: it is characterized in that: the normal oxygen blast of converter is smelted, after reaching smelting endpoint, improving 10 ℃～60 ℃ of catch carbon liquid steel temperatures according to the nitrogen time of re-blowing, top-blown gas is switched to the nitrogen nitrogen of re-blowing by oxygen, is 3.0～4.0Nm for nitrogen intensity
3/ ht steel, the nitrogen flushing time is 5s～30s.
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Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102732665A (en) * | 2012-03-29 | 2012-10-17 | 鞍钢股份有限公司 | Method for adding nitrogen in molten steel in last phase of steel making |
| CN103451350A (en) * | 2013-08-13 | 2013-12-18 | 攀钢集团攀枝花钢铁研究院有限公司 | Method for controlling nitrogen content in molten steel |
| CN104928432A (en) * | 2015-06-11 | 2015-09-23 | 江苏永钢集团有限公司 | Method for removing phosphorus in converter through blowing nitrogen |
| CN110218841A (en) * | 2019-06-27 | 2019-09-10 | 武汉钢铁有限公司 | A kind of method of producing ultra-low phosphorous steel by converter |
| CN112342340A (en) * | 2020-10-14 | 2021-02-09 | 石横特钢集团有限公司 | Nitrogen supplementary blowing dephosphorization process for converter |
| CN115011751A (en) * | 2022-06-22 | 2022-09-06 | 包头钢铁（集团）有限责任公司 | High manganese steel converter end point manganese alloying control method |
| CN116694851A (en) * | 2023-05-26 | 2023-09-05 | 福建三宝钢铁有限公司 | High-nitrogen process method for deformed steel bar |
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|---|---|---|---|---|
| GB2057509A (en) * | 1979-08-30 | 1981-04-01 | Boc Ltd | Steel making in top-blown converter |
| CN1966752A (en) * | 2006-02-11 | 2007-05-23 | 湖南华菱涟源钢铁有限公司 | Process for producing C-Mn-Al killed steel |
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2011
- 2011-06-02 CN CN 201110147555 patent/CN102220448A/en active Pending
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2057509A (en) * | 1979-08-30 | 1981-04-01 | Boc Ltd | Steel making in top-blown converter |
| CN1966752A (en) * | 2006-02-11 | 2007-05-23 | 湖南华菱涟源钢铁有限公司 | Process for producing C-Mn-Al killed steel |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102732665A (en) * | 2012-03-29 | 2012-10-17 | 鞍钢股份有限公司 | Method for adding nitrogen in molten steel in last phase of steel making |
| CN103451350A (en) * | 2013-08-13 | 2013-12-18 | 攀钢集团攀枝花钢铁研究院有限公司 | Method for controlling nitrogen content in molten steel |
| CN103451350B (en) * | 2013-08-13 | 2015-04-29 | 攀钢集团攀枝花钢铁研究院有限公司 | Method for controlling nitrogen content in molten steel |
| CN104928432A (en) * | 2015-06-11 | 2015-09-23 | 江苏永钢集团有限公司 | Method for removing phosphorus in converter through blowing nitrogen |
| CN110218841A (en) * | 2019-06-27 | 2019-09-10 | 武汉钢铁有限公司 | A kind of method of producing ultra-low phosphorous steel by converter |
| CN112342340A (en) * | 2020-10-14 | 2021-02-09 | 石横特钢集团有限公司 | Nitrogen supplementary blowing dephosphorization process for converter |
| CN115011751A (en) * | 2022-06-22 | 2022-09-06 | 包头钢铁（集团）有限责任公司 | High manganese steel converter end point manganese alloying control method |
| CN115011751B (en) * | 2022-06-22 | 2023-08-25 | 包头钢铁（集团）有限责任公司 | Endpoint manganese alloying control method for high manganese steel converter |
| CN116694851A (en) * | 2023-05-26 | 2023-09-05 | 福建三宝钢铁有限公司 | High-nitrogen process method for deformed steel bar |
| CN116694851B (en) * | 2023-05-26 | 2024-04-05 | 福建三宝钢铁有限公司 | High-nitrogen process method for deformed steel bar |
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Application publication date: 20111019 |