CN111363881B - Method for reducing free oxygen content of converter end-point metal molten pool - Google Patents
Method for reducing free oxygen content of converter end-point metal molten pool Download PDFInfo
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- CN111363881B CN111363881B CN202010253659.3A CN202010253659A CN111363881B CN 111363881 B CN111363881 B CN 111363881B CN 202010253659 A CN202010253659 A CN 202010253659A CN 111363881 B CN111363881 B CN 111363881B
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
- C21C5/28—Manufacture of steel in the converter
- C21C5/30—Regulating or controlling the blowing
- C21C5/35—Blowing from above and through the bath
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
- C21C7/00—Treating molten ferrous alloys, e.g. steel, not covered by groups C21C1/00 - C21C5/00
- C21C7/04—Removing impurities by adding a treating agent
- C21C7/06—Deoxidising, e.g. killing
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Abstract
The invention discloses a method for reducing the free oxygen content of a converter end-point molten metal pool, belongs to the technical field of metallurgy, and solves the problem that clean smelting of molten steel cannot be achieved due to the fact that the free oxygen content of the converter end-point molten metal pool is too high in the prior art. A method for reducing the free oxygen content in the end point metal molten pool of converter features that the carbon-oxygen reaction interface of metal molten pool is increased, the CO partial pressure in metal molten pool is reduced, and the free oxygen content is reduced by controlling the gas supply of bottom-blowing gas supply element, the oxygen supply of top-blowing at the end point of converter and the combined blowing of bottom-blowing and top-blowing gas supply.
Description
Technical Field
The invention relates to the technical field of metallurgy, in particular to a method for reducing the free oxygen content of a converter end-point metal molten pool.
Background
The free oxygen content of the metal molten pool at the end point of the converter is related to the consumption of deoxidation alloy and the generation amount of deoxidation products, and has great influence on the cleanliness smelting of converter molten steel. The thermodynamics of the conventional converter end-point bath deoxidation are [ C ] + [ O ] → co (g), and Pco is the most important thermodynamic factor affecting the converter end-point metal bath [ C ], [ O ], and conventionally, it is considered that [ C ] × [ O ] ═ 0.0025 under the condition of 1600 ℃ and Pco ═ 1.0 atm.
The existing methods for reducing the carbon-oxygen content of the molten steel at the end point of the converter comprise the following steps: (1) firstly, adjusting the oxygen supply intensity through the top blowing oxygen blowing process to reduce the carbon-oxygen deposit before blowing is stopped; and then the carbon reduction material, the top gun nitrogen blowing and the bottom blowing stirring are added to adjust the slag for the second time to reduce the carbon oxygen deposit after the top blowing is stopped. (2) The lance position in the converting process is reduced, the addition of ore in the dynamic process is controlled, the control of the terminal lance lowering time is prolonged, the TFe of the final slag obtained by the converter is ensured to be less than or equal to 17%, and the oxygen content of the terminal molten steel is reduced by controlling the slag pouring and splashing time of the final slag. (3) Limestone is added into the molten steel and is decomposed in the molten steel, and the generated carbon monoxide and carbon dioxide can further play a role in stirring, so that sufficient balance between slag melting and furnace steel slag is promoted, and the carbon oxygen deposit at the end point of the converter can be further reduced. (4) Method for smelting and tapping in converter by top-blowing oxygen and bottom-blowing gas after adding semi-steel liquid steel into converterThe method reduces carbon-oxygen deposit, and the flow of bottom-blown nitrogen or argon at the earlier stage of smelting is 40-60m3The flow of bottom blowing argon in the middle stage of smelting is 40-60m3The flow rate of bottom blowing argon in the later stage of smelting is 70-90m3The flow rate of bottom-blown argon in the tapping process is 40-60m3/h。
The above methods focus on reducing the oxygen content of the final slag or reducing the partial pressure of CO in the converter, and although the value of the converter end-point bath [ C ] x [ O ] can be reduced to some extent, they cannot optimally reduce the free oxygen in the converter bath.
The bottom blowing of the converter can effectively promote the stirring of a metal molten pool, the increase of the bottom blowing flow is beneficial to improving the stirring in the mass transfer efficiency, the balance of slag and steel is promoted, the utilization efficiency of top blowing oxygen can also be improved, but the bottom blowing air supply element is in a high-temperature environment and faces high-temperature corrosion damage, the increase of the bottom blowing air supply flow can lead to the erosion aggravation of surrounding bricks of the air supply element and the air supply element, the bottom blowing air supply element is not beneficial to maintenance, and the bottom blowing air supply element is not beneficial to the long service.
Disclosure of Invention
In view of the above analysis, embodiments of the present invention are directed to a method for reducing the free oxygen content of a molten metal bath at the end of a converter. The invention increases the reaction interface of the metal melting pool [ C ] - [ O ] and simultaneously reduces the CO partial pressure in the metal melting pool by matching top blowing and bottom blowing, thereby solving the problem that the clean smelting of the molten steel can not be achieved due to overhigh free oxygen content of the metal melting pool at the end point of the furnace.
The invention is realized by the following technical scheme:
a method for reducing the free oxygen content in the end point metal molten pool of converter features that the carbon-oxygen reaction interface of metal molten pool is increased, the CO partial pressure in metal molten pool is reduced, and the free oxygen content is reduced by controlling the gas supply of bottom-blowing gas supply element, the oxygen supply of top-blowing at the end point of converter and the combined blowing of bottom-blowing and top-blowing gas supply.
Further, controlling the bottom blowing gas supply element to supply gas comprises:
(a) controlling the number of bottom blowing gas supply elements;
(b) controlling the single branch air supply flow of the bottom blowing air supply element;
(c) controlling the outlet state of the bottom blowing gas supply element.
Further, the number of the bottom blowing gas supply elements is controlled to be determined by the formula N being W/20; wherein W is the charging amount of the molten steel in the converter, the unit of the number N of the bottom blowing gas supply elements is one, and the charging amount W of the molten steel in the converter is counted by t.
Further, the single branch supply flow Q of the bottom blowing supply element is controlledBottom(0.9-1.2) W; wherein W is the charging amount of molten steel in the converter, the charging amount is t, and the bottom blowing gas supply element has a single branch gas supply flow QBottomHas the unit of m3/h。
Further, the outlet state of the bottom blowing gas supply element is controlled as follows: 0 < delta P ═ P-P0Less than 0.3 MPa; wherein P is the flow Q of the single branch supply of the bottom blowing supply elementBottomWorking pressure under conditions, P0Is the flow rate QBottomUnder conditions of initial pressure of the bottom blowing gas supply unit.
Further, the method of controlling the outlet state of the bottom blowing gas supply element includes: controlling the gas supply pressure P of the single branch furnace bottom blowing gas supply element when the converter is openedBlow-in furnace＝0.2～0.5MPa。
Further, the method of controlling the outlet state of the bottom blowing gas supply element further comprises: setting the air supply pressure P of the bottom blowing air supply element of the converter slag splashing single branchSlag splashing＝0.4～0.6MPa。
Further, the method for controlling the outlet state of the bottom blowing gas supply element further comprises the step of controlling the thickness H of the converter bottom slag layer after slag splashing to be 50-100 mm.
Further, the method for controlling the end point top-blown oxygen amount of the converter comprises the following steps: controlling the top-blown oxygen supply Q after the measurement of the sublanceO2By the formula QO2Determining (0.89-0.99) Q; wherein Q is a theoretical calculated value of oxygen supply after the sublance is measured.
Further, the method for controlling the bottom blowing and the top blowing to supply air and perform combined blowing comprises the following steps:
switching the single branch air supply flow of the bottom blowing air supply element to Q2 min before the measurement of the sublanceBottom(ii) a After the measurement of the sublance, the single branch air supply flow of the bottom blowing air supply element is restored to QBottomAdjusting the amount of top-blown oxygen to QO2Wherein the bottom-blowing gas supply element has a single branch gas supply flow QBottom(0.9-1.2) W; wherein W is molten steel in the converterLoading in t, bottom-blowing gas supply element one-branch gas supply flow QBottomHas the unit of m3/h。
Compared with the prior art, the invention can realize at least one of the following beneficial effects:
1. according to the invention, the bottom blowing controls the circular seam type gas supply elements to supply gas, and the number of the bottom blowing gas supply elements is controlled; controlling the state of the outlet of the bottom blowing gas supply element (P-P ═ P & ltdelta P-0< 0.3 MPa): controlling the air supply pressure of the bottom blowing air supply element of the single branch converter to be P when the converter is openedBlow-in furnace0.2-0.5 MPa; setting the slag splashing gas supply pressure P of the single-branch furnace bottom blowing gas supply element of the converterSlag splashing0.4-0.6 MPa; after slag splashing, the thickness H of the converter bottom slag layer is 50-100 mm; (c) controlling the optimal single-branch supply flow, Q, of the bottom-blowing gas supply elementBottomAnd (0.9-1.2) W. The bottom blowing reduces the content of free oxygen at the smelting end point by controlling the quantity of the gas supply elements, the pressure of the gas supply elements and the flow control of the branch of the gas supply elements.
2. The control of the converter end point top blowing oxygen supply is realized by controlling the oxygen supply after the measurement of the sublance, and the oxygen supply after the measurement of the sublance is represented by the formula QO20.89-0.99Q. The top blowing control oxygen supply amount directly controls the free oxygen content at the smelting end point.
3. The invention relates to a combined bottom blowing and top blowing combined blowing method, which comprises the following steps: switching the single branch air supply flow of the bottom blowing air supply element to Q2 min before the measurement of the sublanceBottom(ii) a After the measurement of the sublance, the single branch air supply flow of the bottom blowing air supply element is restored to QBottomAdjusting the amount of top-blown oxygen to QO2. And in the smelting process, the flow of bottom blowing gas is adjusted in stages according to smelting requirements, and the combined top blowing and bottom blowing control is the combined optimization of top blowing gas and bottom blowing gas.
4. The invention realizes the increase of carbon-oxygen reaction interface of the metal molten pool, the reduction of CO partial pressure in the metal molten pool and the reduction of free oxygen content by controlling the air supply of the bottom blowing air supply element, the control of the terminal top blowing oxygen supply amount of the converter and the control of the combined blowing of the bottom blowing air supply and the top blowing air supply, and controls the free oxygen content to be less than or equal to 450 PPm.
In the invention, the technical schemes can be combined with each other to realize more preferable combination schemes. Additional features and advantages of the invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description.
Detailed Description
The following description of the preferred embodiments of the present invention is provided to illustrate the principles of the present invention and not to limit the scope of the invention.
The design principle of the invention is that the converter is shifted to the later stage of smelting according to the control of the content of free oxygen in molten steel by the content of carbon, and the reaction formula of carbon and oxygen in the blowing process is as follows:
[C]+[O]＝{CO}
the carbon-oxygen concentration product in the molten steel reflects the control level of the oxygen content of the molten steel at the blowing end of the converter. The smelting end point of the converter is calibrated by the activity relation between [ C ] and [ O ] measured by the sublance, and is determined according to the flame color of the smelting end point of the converter and the oxygen supply amount in smelting.
The invention can generate uniform and dispersed inert bubble groups in the metal melting pool while stirring the metal melting pool by bottom blowing inert gas to promote slag-steel balance. The inert bubble group increases the reaction interface of the metal melting pool [ C ] - [ O ], reduces the CO partial pressure in the metal melting pool, and the method can effectively reduce the free oxygen content of the metal melting pool at the end point of the converter and promote the clean smelting of the molten steel of the converter.
The invention provides a method for reducing the free oxygen content of a molten pool at the end point of a converter, which realizes the increase of a carbon-oxygen reaction interface of a metal molten pool, the reduction of CO partial pressure in the metal molten pool and the reduction of the free oxygen content by controlling the gas supply of a bottom blowing gas supply element, controlling the top blowing oxygen supply amount at the end point of the converter and controlling the combined blowing of bottom blowing gas supply and top blowing gas supply.
Firstly, controlling the bottom blowing gas supply element to supply gas
The air supply process of the bottom blowing air supply element is controlled, and the optimal air supply state of the bottom blowing air supply element is realized by controlling the number of the bottom blowing air supply elements, controlling the single branch air supply flow of the bottom blowing air supply element and keeping the outlet state of the bottom blowing air supply element.
Specifically, (a) the number of the bottom-blowing gas supply elements is controlled by the following formula:
n ═ W/20 (formula 1)
Wherein W is the charging amount of the molten steel in the converter, and the unit is ton. The formula is obtained by comprehensively considering the relation between the charging amount of molten steel in the converter and the flow demand of the bottom blowing inert gas in the actual production. The bottom-blown inert gas plays a role in stirring molten metal in a metal molten pool, and the relevance between the flow rate of the bottom-blown inert gas and the loading amount of the molten steel and the stirring capacity of the molten steel is large. The bottom blowing of the inert gas is used for well stirring the molten steel. The steel slag is not stirred, the free oxygen content in the molten steel is high, and the steel slag is not uniform. The flow of the inert gas is small, the pressure resistance of the bottom blowing outlet is large, the gas can flow out, the stirring capacity to the molten steel is insufficient, and the stirring effect cannot be achieved; the flow of the inert gas is large, the gas through impulse force is too large, and the good stirring effect on the molten steel cannot be achieved.
It should be noted that the number N of the bottom-blowing gas supply elements is even: if N is an even number W/20, the number of bottom blowing gas elements is measured to be N; if N is an odd number of W/20, the number of bottom-blowing gas elements is counted as N + 1. For example, 210/20 is 11, and the number of bottom blowing elements is set to 12.
(b) The single branch air supply flow of the bottom blowing air supply element is determined by the following formula:
Qbottom(0.9 to 1.2) W (formula 2)
Wherein, the flow coefficient is 0.9-1.2, which represents the relationship between the bottom blowing single branch flow and the molten steel charging amount in the converter. Under the condition of the optimal flow of the single branch of the bottom blowing gas supply element, the stirring effect of the inert gas on the molten steel in the converter is optimal, uniform and dispersed inert bubble groups are generated in the molten steel, the partial pressure of CO is effectively reduced, and therefore the content of free oxygen in the molten steel is reduced.
(c) The single branch outlet state of the bottom blowing air supply element is controlled as follows:
0＜ΔP＝P-P0＜0.3MPa
wherein P is the single-branch optimal flow QBottomUnder the condition of bottom blowing, the working pressure of the air supply element is expressed in unitMPa；P0Is the flow rate QBottomThe initial pressure of the bottom blowing gas supply element under the condition is MPa.
The gas flow in the branch has two functions, namely, the diffusion of inert gas is ensured; secondly, the steel-slag is promoted to be fully mixed; thirdly, the blown inert gas in the bottom blowing branch increases the dispersion degree of bubbles in the molten pool and the uniformity of steel-slag mixing in the molten pool, thereby reducing the vacuum degree of CO partial pressure. And the outlet of the bottom blowing gas supply element can reduce the peroxidation gradient of the slag-steel and reduce the CO partial pressure under the optimal state, thereby promoting the reduction of the free oxygen content.
The peroxide gradient is the difference value of the free oxygen content in the molten steel and the steel slag. In the converter smelting process, the oxygen sources are two: (1) top blown external oxygen input; (2) the iron oxide in the slag decomposes at high temperature to iron and oxygen. When the oxygen content in the steel slag is higher than that in the molten steel, the oxygen in the steel slag can be transferred into the molten steel to pollute the molten steel. When the converter bottom blowing gas supply element is in the optimum outlet state, delta P is greater than 0 and is equal to P-P0Less than 0.3MPa, and the inert gas is blown into the converter in the pressure value range, so that slag-steel mixing can be fully promoted, the slag-steel peroxidation gradient is reduced, the vacuum degree of CO partial pressure in the molten steel can be reduced, and the free oxygen content in a molten pool is reduced.
Furthermore, the invention maintains the optimal state of the outlet of the bottom blowing air supply element (P-P is equal to P when the delta P is more than 0)0< 0.3MPa) comprises:
(1) controlling the air supply pressure of the bottom blowing air supply element of the single branch converter to be P when the converter is openedBlow-in furnace＝0.2～0.5MPa；
(2) Setting the slag splashing gas supply pressure P of the single-branch furnace bottom blowing gas supply element of the converterSlag splashing＝0.4～0.6MPa；
(3) And after slag splashing, the thickness H of the converter bottom slag layer is 50-100 mm.
When the gas supply pressure of the gas supply element is lower than 0.2MPa when the converter is opened, the blowing pressure of bottom blowing inert gas is too low, so that the inert gas is condensed, and the bottom blowing gas supply element is damaged; if the blow-in pressure is too high and is higher than 0.5MPa, the pipeline of the bottom blowing gas supply element can be damaged due to the too high pressure. Therefore, the temperature of the molten metal is controlled,controlling the air supply pressure of the bottom blowing air supply element of the single branch converter to be P when the converter is openedBlow-in furnace＝0.2～0.5MPa。
After the converter is started, the converter starts to blow inert gas and oxygen gas from the bottom, and steel slag appears on the upper layer of the molten steel along with the smelting process of the molten steel in the converter. If the pressure of the single-branch bottom-blown inert gas of the converter is too low and is lower than 0.4MPa, the steel slag deposits and blocks the gas path of the bottom-blown gas supply element, the steel slag and the molten steel cannot be sufficiently mixed, so that the difference of oxygen content in the steel slag and the molten steel is large, free oxygen cannot be sufficiently utilized, and the free oxygen content is increased. Similarly, if the pressure of the inert gas blown from the bottom of the single branch of the converter is too high and is higher than 0.6MPa, the inert gas cannot be fully and uniformly dispersed in the molten steel, so that the partial pressure of CO cannot be reduced, and the free oxygen content in the molten steel cannot be effectively reduced. In the later stage of converter smelting, the content of iron oxide in the steel slag is related to the oxygen content in the molten steel. The content of the ferric oxide and the oxygen content in the molten steel have a relative equilibrium relation. Generally, the higher the content of iron oxide in steel slag, the stronger the oxidability of steel slag, the relatively higher the oxygen content in molten steel, and the lower the metal yield. The slag splashing layer formed by slag splashing has better corrosion resistance, can inhibit oxidation and decarburization on the surface of the lining brick of the furnace, and can also reduce erosion and scouring of high-temperature slag on the lining brick of the furnace, thereby protecting the lining brick of the furnace and prolonging the service life of the lining brick of the furnace. Through the blowing and splashing of high-pressure nitrogen, a high-melting-point slag layer is formed on the surface of the furnace lining and well adhered to the furnace lining. In the invention, the thickness of the converter bottom slag layer after slag splashing is designed to be 50-100 mm.
Secondly, controlling the top-blown oxygen supply amount of the end point of the converter
The purpose of controlling the top-blown oxygen supply amount of the converter terminal is to prevent overoxidation caused by excess oxygen, and under the coordination of bottom-blown inert gas purging, the use efficiency of top-blown oxygen is improved, and the input of free oxygen in the converter is reduced from the source.
The converter end point top-blown oxygen supply control method comprises the following steps: the oxygen supply amount after the measurement of the sublance is controlled to be determined by the following formula:
QO2(0.89 to 0.99) Q (formula 3)
Wherein Q is a theoretical calculated value of oxygen supply after the sublance is measured.
Thirdly, controlling the bottom blowing and the top blowing to supply air for matching
The combined double blowing control of bottom blowing and top blowing in the invention is the combined optimization of top blowing oxygen and bottom blowing inert gas.
The bottom blowing and top blowing air supply matched secondary blowing control is as follows: bottom blowing air supply flow is switched to Q2 min before measurement of sublanceBottom(ii) a After the measurement by the sublance, the bottom-blowing air flow is restored to QBottomAt this time, the top-blown oxygen supply amount is adjusted to QO2。
The gas flow is not constant during the smelting of the molten steel in the converter, QBottom、QO2And performing staged adjustment according to smelting requirements. The sublance measurement is the last oxygen blowing before tapping, the flow of bottom-blown inert gas is increased, the molten steel in a molten pool is stirred quickly, and uniform and dispersed inert bubble groups are generated. Inert gas bubble group is increased]-[O]The reaction interface reduces the partial pressure of CO in the metal melting tank, the oxygen content of the molten steel-steel slag tends to be dynamic balance, and the utilization efficiency of free oxygen is improved. If the bottom-blown inert gas still has the original oxygen utilization rate, the oxygen supply is excessive, the free oxygen is increased, and the removal of the oxygen is difficult.
Example 1
Example 1 a method for reducing the free oxygen content in the molten metal bath at the end of the converter in accordance with the present invention will be described by taking the molten steel charge amount 210t as an example.
Controlling the number N of bottom blowing gas supply elements to be W/20; when the number N of the bottom-blowing gas supply elements is 210/20 and is considered to be an odd number, the number of the bottom-blowing gas supply elements is counted as N +1, that is, the number of the bottom-blowing gas supply elements is set to 12.
The flow coefficient is taken to be 0.933, at this time QBottom＝(0.93)W≈196m3/h。
In the later stage of converter smelting, 210t of molten steel is added into the converter, the blow-in pressure is set to be 0.4MPa, at the moment, 12 gas supply elements are opened at the bottom of the converter, and the single branch gas flow of the bottom blowing gas supply element is set to be QBottomIs 196m3H, top oxygen flow QO2Is set to 42000m3And h, starting top blowing oxygen by the converter, and starting converter smelting.
After the converter starts smelting, the pressure of the single branch gas supply of the bottom blowing branch gas supply element is kept to be 0.25 MPa. The slag splashing gas supply pressure of the converter single branch furnace bottom blowing gas supply element is set to be 0.5MPa, and the thickness of the slag layer at the bottom of the converter is 80mm after slag splashing is carried out in the converter smelting.
And when tapping is needed in the later stage of converter smelting, carrying out sublance measurement. Single branch gas flow Q of bottom blowing gas supply element switched 2min before sublance measurementBottom196m3H; after the sublance is measured, the single branch gas flow Q of the bottom blowing gas supply element is recoveredBottomTo 196m3H, adjusting the top-blown oxygen supply to QO2. The results of the smelting temperature and the smelting end point carbon and oxygen contents of the converter by the smelting process are shown in Table 1.
TABLE 1 converter smelting temperature and smelting end point carbon oxygen content
| Temperature of | [C]/％ | [O]/PPm |
| 1650 | 0.04 | 450 |
| 1660 | 0.03 | 442 |
| 1645 | 0.035 | 412 |
Example 2
In this example, the method of reducing the free oxygen content in the molten metal bath at the end of the converter in the present invention will be described by taking the molten steel charge amount of 300t as an example.
Controlling the number N of bottom blowing gas supply elements to be W/20; when the number N of the bottom-blowing gas supply elements is 300/20 and is considered to be an odd number, the number of the bottom-blowing gas supply elements is counted as N +1, that is, the number of the bottom-blowing gas supply elements is set to 16.
The flow coefficient is taken to be 1.1, at which time QBottom＝(1.1)W≈330m3/h。
In the later period of the steel smelting, 300t of molten steel is added into the converter, the blow-in pressure is set to be 0.45MPa, at the moment, 16 gas supply elements are opened at the bottom of the converter, and the single branch gas flow Q of the bottom blowing gas supply elementBottomIs set to 330m3H, top oxygen flow QO2Is set to 62000m3And/h, starting top blowing oxygen by the converter, and starting converter smelting.
After the converter starts smelting, the pressure of the single branch gas supply of the bottom blowing branch gas supply element is kept to be 0.28 MPa. The slag splashing gas supply pressure of a single-branch converter bottom blowing gas supply element of the converter is set to be 0.55MPa, and the thickness of a slag layer at the bottom of the converter is 90mm after slag splashing is carried out in the converter smelting.
And when tapping is needed in the later stage of converter smelting, carrying out sublance measurement. Single branch gas flow Q of bottom blowing gas supply element switched 2min before sublance measurementBottomTo 330m3H; after the sublance is measured, the single branch gas flow Q of the bottom blowing gas supply element is recoveredBottomTo 330m3H, adjusting the top-blown oxygen supply to QO2. The results of the smelting temperature and the smelting key carbon and oxygen contents of the converter by the smelting process are shown in Table 2.
TABLE 2 converter smelting temperature and smelting end point carbon oxygen content
| Temperature of | [C]/％ | [O]/PPm |
| 1670 | 0.04 | 420 |
| 1655 | 0.033 | 425 |
| 1668 | 0.038 | 423 |
Comparative example 1
In the comparative example, 210t of molten steel was charged into a converter, 4 gas supply branches were provided for bottom-blowing, and the single-branch bottom-blowing flow rate was 80Nm3H is used as the reference value. The results of the smelting temperature and the carbon and oxygen contents at the smelting end point of the converter after the smelting period of one converter is finished are shown in Table 3.
TABLE 3 converter smelting temperature and smelting end point carbon oxygen content
| Temperature of | [C]/％ | [O]/PPm |
| 1670 | 0.045 | 560 |
| 1655 | 0.036 | 665 |
| 1668 | 0.044 | 553 |
The comparison of the results in tables 1-2 and 3 shows that the method for reducing the free oxygen content of the converter end-point molten metal pool provided by the invention is obviously superior to the prior art in terms of the reduction result of the free oxygen content of the converter end-point molten metal pool, the content of [ O ] can be controlled below 450PPm, and is reduced by more than 20% compared with the content of [ O ] of the converter end-point molten metal pool in the prior art, so that the free oxygen content of the converter end-point molten metal pool can be effectively reduced, and the clean smelting of converter molten steel is promoted.
The above description is only for the preferred embodiment of the present invention, but the scope of the present invention is not limited thereto, and any changes or substitutions that can be easily conceived by those skilled in the art within the technical scope of the present invention are included in the scope of the present invention.
Claims (7)
1. A method for reducing the free oxygen content of a converter end point molten metal pool is characterized in that the carbon-oxygen reaction interface of the molten metal pool is increased, the CO partial pressure in the molten metal pool is reduced, and the free oxygen content is reduced by controlling the gas supply of a bottom blowing gas supply element, controlling the top blowing oxygen supply amount of the converter end point and controlling the combined blowing of bottom blowing and top blowing gas supply;
the controlling the bottom blowing gas supply element to supply gas comprises:
(a) controlling the number of bottom blowing gas supply elements: determined by the formula N ═ W/20; wherein W is the loading amount of the molten steel in the converter, the unit of the number N of the bottom blowing gas supply elements is one, and the loading amount W of the molten steel in the converter is counted by t;
(b) controlling the single-branch air supply flow of the bottom blowing air supply element: qBottom(0.9-1.2) W; wherein W is the charging amount of the molten steel in the converter, and the charging amount is tBottom blowing element single branch supply flow QBottomHas the unit of m3/h；
(c) Controlling the outlet state of the bottom blowing gas supply element: 0 < delta P ═ P-P0Less than 0.3MPa, wherein P is the flow Q of the single branch supply of the bottom blowing gas supply elementBottomWorking pressure under conditions, P0Is the flow rate QBottomUnder the conditions, the initial pressure of the air blowing element is applied;
the method for controlling the end point top blown oxygen supply of the converter comprises the following steps: controlling the top-blown oxygen supply Q after the measurement of the sublanceO2By the formula QO2Determining (0.89-0.99) Q; wherein Q is a theoretical calculated value of oxygen supply after the sublance is measured;
the combined blowing method for controlling the cooperation of bottom blowing and top blowing air supply comprises the following steps: when tapping is needed in the later stage of converter smelting, measuring a sublance, and switching the single-branch gas supply flow of the bottom blowing gas supply element to Q2 min before measuring the sublanceBottom(ii) a After the measurement of the sublance, the single branch air supply flow of the bottom blowing air supply element is restored to QBottomAdjusting the amount of top-blown oxygen to QO2Wherein the bottom-blowing gas supply element has a single branch gas supply flow QBottom(0.9-1.2) W; wherein W is the charging amount of molten steel in the converter, the charging amount is t, and the bottom blowing gas supply element has a single branch gas supply flow QBottomHas the unit of m3/h。
2. The method for reducing the free oxygen content of the molten metal bath at the end of the converter according to claim 1, wherein the ratio of the number of (a) bottom-blowing gas supply elements N: if N is an even number W/20, the number of bottom blowing gas elements is measured to be N; if N is an odd number of W/20, the number of bottom-blowing gas elements is counted as N + 1.
3. The method of claim 1, wherein Q in (b) is a value calculated from the free oxygen content of the molten metal bath at the end of the converterBottom＝(0.9～1.1)W。
4. The method of reducing the free oxygen content of the molten metal bath at the end of the converter according to claim 1, wherein said (c) controlling the outlet status of the bottom-blowing gas supply unit comprises: controlling single branch when converter is openedAir supply pressure P of road furnace bottom blowing air supply elementBlow-in furnace＝0.2～0.5MPa。
5. The method for reducing the free oxygen content of the molten metal bath at the end point of the converter according to claim 4, wherein the method for controlling the outlet status of the bottom-blowing gas supply element further comprises: setting the air supply pressure P of the bottom blowing air supply element of the converter slag splashing single branchSlag splashing＝0.4～0.6MPa。
6. The method for reducing the free oxygen content of the molten metal pool at the end point of the converter according to claim 5, wherein the method for controlling the outlet state of the bottom blowing gas supply element further comprises controlling the thickness H of the converter bottom slag layer after slag splashing to be 50-100 mm.
7. The method for reducing the free oxygen content of the molten metal bath at the end point of the converter according to claim 1, wherein in the combined blowing method of controlling the bottom blowing gas and the top blowing gas: qBottom＝0.93W。
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| JP2001200309A (en) * | 2000-01-18 | 2001-07-24 | Sumitomo Metal Ind Ltd | Top blowing oxygen lance for converter and converter refining method |
| CN100439517C (en) * | 2007-04-30 | 2008-12-03 | 武汉钢铁(集团)公司 | Terminal low-oxygen control method for top bottom combined blowing converter |
| CN104004877B (en) * | 2014-06-06 | 2016-06-01 | 攀钢集团攀枝花钢铁研究院有限公司 | A kind of method reducing converter terminal carbon oxygen and amassing |
| CN107245542A (en) * | 2017-05-19 | 2017-10-13 | 河钢股份有限公司承德分公司 | The method for reducing dissolved oxygen content in converter smelting endpoint molten steel |
| CN109825664A (en) * | 2019-04-12 | 2019-05-31 | 攀钢集团攀枝花钢铁研究院有限公司 | The method for reducing converter terminal molten steel carbon oxygen product |
| CN110157848A (en) * | 2019-05-06 | 2019-08-23 | 山东钢铁集团有限公司 | A kind of bottom blowing flow dynamics control method of top and bottom combined blown converter |
| CN110396567B (en) * | 2019-08-23 | 2023-04-14 | 鞍山市和丰耐火材料有限公司 | Layout structure of furnace bottom gas supply bricks for reducing carbon-oxygen deposit at converter end point and bottom blowing process |
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