CN115109894A - Method for controlling splashing during desiliconization period of smelting stainless steel - Google Patents
Method for controlling splashing during desiliconization period of smelting stainless steel Download PDFInfo
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- 238000000034 method Methods 0.000 title claims abstract description 32
- 239000010935 stainless steel Substances 0.000 title claims abstract description 26
- 229910001220 stainless steel Inorganic materials 0.000 title claims abstract description 26
- 238000003723 Smelting Methods 0.000 title claims abstract description 25
- 239000002893 slag Substances 0.000 claims abstract description 78
- 238000007664 blowing Methods 0.000 claims abstract description 77
- QVGXLLKOCUKJST-UHFFFAOYSA-N atomic oxygen Chemical compound [O] QVGXLLKOCUKJST-UHFFFAOYSA-N 0.000 claims abstract description 65
- 239000001301 oxygen Substances 0.000 claims abstract description 65
- 229910052760 oxygen Inorganic materials 0.000 claims abstract description 65
- 229910052710 silicon Inorganic materials 0.000 claims abstract description 36
- 239000010703 silicon Substances 0.000 claims abstract description 31
- 235000008733 Citrus aurantifolia Nutrition 0.000 claims abstract description 19
- 235000011941 Tilia x europaea Nutrition 0.000 claims abstract description 19
- 239000004571 lime Substances 0.000 claims abstract description 19
- 238000003756 stirring Methods 0.000 claims abstract description 13
- 239000007788 liquid Substances 0.000 claims abstract description 12
- 238000005070 sampling Methods 0.000 claims abstract description 6
- 229910000831 Steel Inorganic materials 0.000 claims description 26
- 239000010959 steel Substances 0.000 claims description 26
- XUIMIQQOPSSXEZ-UHFFFAOYSA-N Silicon Chemical compound [Si] XUIMIQQOPSSXEZ-UHFFFAOYSA-N 0.000 claims description 24
- 238000006243 chemical reaction Methods 0.000 claims description 17
- 239000000463 material Substances 0.000 claims description 16
- 229910052799 carbon Inorganic materials 0.000 claims description 13
- CSJDCSCTVDEHRN-UHFFFAOYSA-N methane;molecular oxygen Chemical compound C.O=O CSJDCSCTVDEHRN-UHFFFAOYSA-N 0.000 claims description 10
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 8
- 238000004364 calculation method Methods 0.000 claims description 7
- 238000001816 cooling Methods 0.000 claims description 5
- WGLPBDUCMAPZCE-UHFFFAOYSA-N Trioxochromium Chemical compound O=[Cr](=O)=O WGLPBDUCMAPZCE-UHFFFAOYSA-N 0.000 claims description 4
- 229910000423 chromium oxide Inorganic materials 0.000 claims description 4
- 239000006260 foam Substances 0.000 claims description 4
- 239000011261 inert gas Substances 0.000 claims description 3
- 238000010438 heat treatment Methods 0.000 claims description 2
- 229910045601 alloy Inorganic materials 0.000 abstract description 9
- 239000000956 alloy Substances 0.000 abstract description 9
- 230000003647 oxidation Effects 0.000 abstract description 8
- 238000007254 oxidation reaction Methods 0.000 abstract description 8
- 238000005261 decarburization Methods 0.000 abstract description 5
- 238000009628 steelmaking Methods 0.000 abstract description 2
- 239000011651 chromium Substances 0.000 description 10
- 229910052804 chromium Inorganic materials 0.000 description 5
- 230000000694 effects Effects 0.000 description 5
- 239000007789 gas Substances 0.000 description 5
- IJGRMHOSHXDMSA-UHFFFAOYSA-N Atomic nitrogen Chemical compound N#N IJGRMHOSHXDMSA-UHFFFAOYSA-N 0.000 description 4
- XEEYBQQBJWHFJM-UHFFFAOYSA-N Iron Chemical compound [Fe] XEEYBQQBJWHFJM-UHFFFAOYSA-N 0.000 description 4
- VYZAMTAEIAYCRO-UHFFFAOYSA-N Chromium Chemical compound [Cr] VYZAMTAEIAYCRO-UHFFFAOYSA-N 0.000 description 3
- 238000004519 manufacturing process Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- 229910004298 SiO 2 Inorganic materials 0.000 description 2
- 229910052742 iron Inorganic materials 0.000 description 2
- 229910044991 metal oxide Inorganic materials 0.000 description 2
- 150000004706 metal oxides Chemical class 0.000 description 2
- 238000002156 mixing Methods 0.000 description 2
- 229910052759 nickel Inorganic materials 0.000 description 2
- 229910052757 nitrogen Inorganic materials 0.000 description 2
- 239000000126 substance Substances 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 229910000975 Carbon steel Inorganic materials 0.000 description 1
- 229910000599 Cr alloy Inorganic materials 0.000 description 1
- VYPSYNLAJGMNEJ-UHFFFAOYSA-N Silicium dioxide Chemical compound O=[Si]=O VYPSYNLAJGMNEJ-UHFFFAOYSA-N 0.000 description 1
- 229910002064 alloy oxide Inorganic materials 0.000 description 1
- 238000004458 analytical method Methods 0.000 description 1
- 230000009286 beneficial effect Effects 0.000 description 1
- 230000015572 biosynthetic process Effects 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 239000010962 carbon steel Substances 0.000 description 1
- 239000003575 carbonaceous material Substances 0.000 description 1
- 239000000788 chromium alloy Substances 0.000 description 1
- 238000007599 discharging Methods 0.000 description 1
- 238000005516 engineering process Methods 0.000 description 1
- 230000002349 favourable effect Effects 0.000 description 1
- 238000005187 foaming Methods 0.000 description 1
- 230000002401 inhibitory effect Effects 0.000 description 1
- 238000002844 melting Methods 0.000 description 1
- 230000008018 melting Effects 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000012986 modification Methods 0.000 description 1
- 230000004048 modification Effects 0.000 description 1
- 238000010587 phase diagram Methods 0.000 description 1
- 238000006479 redox reaction Methods 0.000 description 1
- 229910052814 silicon oxide Inorganic materials 0.000 description 1
- 239000002210 silicon-based material Substances 0.000 description 1
Classifications
-
- 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
- C21C7/072—Treatment with gases
-
- 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
- C21C7/0087—Treatment of slags covering the steel bath, e.g. for separating slag from the molten metal
-
- Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
- Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
- Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
- Y02P10/00—Technologies related to metal processing
- Y02P10/20—Recycling
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Analytical Chemistry (AREA)
- Refinement Of Pig-Iron, Manufacture Of Cast Iron, And Steel Manufacture Other Than In Revolving Furnaces (AREA)
Abstract
The invention relates to the field of steel making. A method for controlling splashing in the desiliconization period of smelting stainless steel comprises the following steps: (1) loading the high-silicon premelting liquid into an AOD furnace, and measuring and sampling temperature; (2) calculating the addition of cold charge, the addition of lime and oxygen blowing amount according to the charging conditions; (3) observing the flame at the furnace mouth when the oxygen blowing amount reaches 80-90%; (4) stopping blowing, and stirring by using bottom blowing; (5) shaking the furnace to 85-90 degrees, pouring the low-alkalinity slag into a slag pot, shaking the furnace to 0-4 degrees, and starting normal smelting. The method reduces the oxidation of the alloy while ensuring the desiliconization, ensures the fluidity of the slag by reasonably controlling the physicochemical characteristics of the slag at the end point of the desiliconization period, ensures the successful pouring of the low-alkalinity slag, and creates good conditions for the subsequent decarburization.
Description
Technical Field
The invention relates to the field of steelmaking, in particular to a method for controlling splashing in a desilication period of smelted stainless steel.
Background
At present, in order to further reduce the stainless steel smelting cost, the stainless steel smelting process is greatly developed. With the development of new technology, the addition amount of AOD cold burden begins to increase, and high-carbon and high-silicon materials become the mainstream of stainless steel production. The carbon and silicon content of the pre-solution is greatly increased in the actual production process and enters the furnaceThe highest silicon content reaches 5 percent (mass percent), the carbon content also rises to 2 to 5 percent (mass percent), and in order to solve the problem of large amount of slag after silicon element oxidation, an operation method for timely pouring out low-alkalinity slag in the final desiliconization stage is developed (the desiliconization stage is defined as the early stage of blowing the high-silicon premelting liquid and the stage before a large amount of Si is oxidized to the beginning of carbon-oxygen reaction). The silicon element carried by the pre-melt in the early stage of blowing the pre-melt with high silicon content is preferentially oxidized to generate slag, the alkalinity of the slag is reduced along with the oxidation of silicon, the surface tension is increased, and the good fluidity and air impermeability provide a foundation for the formation of foamed slag; with the further oxygen blowing, the silicon content in the molten steel is reduced, and Cr in the slag is reduced 2 O 3 The content is rapidly increased, the temperature is increased, the carbon-oxygen reaction is further intensified, and a large amount of formed gas provides a power condition for the foaming of the slag; along with the oxidation of a large amount of silicon element, the content of silicon oxide in the slag rapidly rises, the slag amount rapidly increases, the slag layer in the furnace becomes thick, the viscosity of the slag rises, and a large amount of carbon monoxide gas generated by carbon-oxygen reaction is more difficult to discharge, so that a slag amount condition is provided for splashing. After the reaction conditions of alkalinity, temperature, slag amount and carbon and oxygen are all satisfied, a large amount of foam slag is formed to gush out of a furnace mouth, splashing occurs to cause an accident, and meanwhile, a large amount of alloy oxide in the slag runs off along with splashing to cause the loss of alloy cost.
The slag alkalinity, the bath temperature, the slag quantity, the carbon-oxygen reaction, the oxygen blowing amount control and the silicon content control in the premelt liquid are all important factors influencing splashing during the desiliconization period, and the splashing is easy to occur due to improper control.
Chinese patent CN 105525055B discloses a method for controlling splashing in the decarburization period of converter low-slag smelting, which aims at controlling the mass fraction of molten iron Si in the converter to be 0.2-0.7%, and the splashing control in the decarburization period of the converter mainly achieves the effect of controlling splashing by controlling the lance position of a top lance and oxygen supply operation and by adding auxiliary materials and controlling the alkalinity of furnace slag, and has poor applicability to stainless steel smelting, and the problem of producing a pre-melted liquid with the stainless steel silicon content of more than 1.0% cannot be solved. Chinese patent CN 10877614B discloses a method for inhibiting splashing in the early stage of converter smelting, which mainly controls the splashing by controlling the top lance position and oxygen pressure in the early stage of converting and increasing the bottom blowing stirring effect, and can only inhibit the splashing by operating an oxygen lance but can not reduce the slag amount, thereby fundamentally solving the splashing problem. Chinese patent CN 105755199B discloses "anti-splashing smelting control for converter smelting high-silicon molten iron", this converter controls the top lance position and oxygen supply strength, and controls the final slag binary alkalinity to control splashing through dumping desiliconized slag in the slag-discharging stage, but the control method provided by this patent needs enough metal oxidation of slag to ensure the fluidity of slag during dumping, and it is inevitable to oxidize a large amount of chromium in the pre-molten liquid during the production process of stainless steel, and a large amount of alloy loss is caused during dumping.
In practical research, the applicant finds that the method for controlling splashing mainly aims at effectively controlling splashing in the process of smelting carbon steel by using a converter, but is not suitable for smelting stainless steel with high alloy content, cannot solve the problem of metal oxide loss in stainless steel slag, and cannot avoid the problem of small AOD furnace volume ratio. AOD is used in the process of smelting stainless steel by using premelt liquid with high silicon content due to the furnace volume ratio (0.52 m) 3 The/t) is far smaller than that of a converter, splashing cannot be well controlled by the method, and alloy is easy to lose along with a large amount of slag, so that a special slag control method for AOD desilication is urgently needed to be found out, and AOD early-stage splashing is controlled under the condition that chromium alloy is not lost.
Disclosure of Invention
The invention aims to solve the problems and provides a method for controlling splashing in the desilication period of smelting stainless steel.
The purpose of the invention is realized as follows: a method for controlling splashing in the desiliconization period of smelting stainless steel comprises the following steps: (1) loading the high-silicon premelting liquid into an AOD furnace, measuring the temperature and sampling; (2) and (3) calculating the cold charge addition, the lime addition and the oxygen blowing amount according to the charging conditions, wherein the calculation formula is as follows: 1) the formula for calculating the addition of the cold charge is as follows: the cold charge addition amount is = (the silicon content in the furnace is-0.35%) × 31 ÷ 8+ the early-stage material Si content is ÷ steel conversion amount is × 31 ÷ 8; controlling the end point Si content at 0.2-0.5%, converting at 0.1%, heating Si content to 28-35 deg.C, and cooling to 7-11 deg.C per ton of cold charge; 2) replenishing lime in the blowing desilication period to ensure that the binary alkalinity at the final desilication stage is controlled to be 1.3-1.5, wherein the calculation formula is as follows: lime addition amount = ((silicon content in furnace-0.35%) × steel conversion amount + early-stage material Si content) × 2.14 × 1.4; the end point Si content is controlled to be 0.2-0.5%, and the desiliconization end point binary alkalinity is controlled to be 1.2-1.6; 3) the oxygen blowing amount in the desiliconization period is calculated according to the following formula: oxygen blowing amount in the desiliconization period = ((furnace silicon-0.35%) × steel adding amount × 0.8+ Si content in the previous period × 0.8) ÷ oxygen utilization rate; the end point Si content is controlled to be 0.2-0.5%, and the oxygen utilization rate is 65-85%; the oxygen blowing amount is between 65 and 85 percent according to different desiliconization utilization rates of the silicon and carbon contents in the furnace; (3) observing the flame at the furnace mouth when the oxygen blowing amount reaches 80-90%, and stopping blowing when the flame overflows and a small amount of slag splashes at the furnace mouth and the carbon-oxygen reaction is intensified, the slag layer begins to foam; (4) stopping blowing, and reducing chromium oxide in the slag by using bottom blowing stirring and utilizing good fluidity of the steel slag and residual Si in the molten steel; (5) shaking the furnace to 85-90 degrees, pouring the low-alkalinity slag into a slag pot, shaking the furnace to 0-4 degrees, and starting normal smelting.
After blowing, the oxygen supply intensity is controlled at 1.7-1.9 Nm3/(min/t), and the gun position is operated at a low gun position.
And in the blowing process, cooling cold materials are added into the molten pool in batches according to the oxygen blowing amount and the oxygen blowing time, the feeding follows a constant speed, and the temperature of the molten pool is ensured to be stabilized between 1450 and 1550 ℃.
The side gun is stirred by inert gas, and the stirring flow is controlled to be 0.7-1.1Nm 3 /(min/t), the stirring time is controlled between 3 and 5 minutes.
The invention has the beneficial effects that: the method reasonably controls the slag alkalinity, the molten pool temperature and the desilication end point Si content in the desilication period of the stainless steel smelting, reasonably controls the oxygen blowing amount in the desilication period, and effectively controls the splashing in the desilication period of the stainless steel smelting. The method reduces the oxidation of the alloy while ensuring the desiliconization, ensures the fluidity of the slag by reasonably controlling the physicochemical characteristics of the slag at the end point of the desiliconization period, ensures the successful pouring of the low-alkalinity slag, and creates good conditions for the subsequent decarburization.
Detailed Description
The method is innovatively provided: the physicochemical properties such as the slag temperature, the alkalinity and the like in the early stage of AOD blowing are reasonably controlled, the carbon-oxygen reaction is controllable in the desiliconization period, the desiliconization oxygen utilization rate is improved, and the massive oxidation of the alloy is avoided while desiliconization is carried out; reasonably controlling oxygen blowing amount, fully desiliconizing and controlling Si content in the pre-melted liquid at the final desiliconizing stage; the temperature of a molten pool and the alkalinity of the slag at the final desiliconization stage are controlled within a reasonable range, so that the fluidity of the slag at the final desiliconization stage is ensured, and the subsequent deslagging effect is ensured to be good.
The applicant has determined that the slag CaO-SiO 2 -MgO-Cr 2 O 3 The analysis of the quaternary phase diagram shows that: the temperature of a molten pool should be controlled to be 1480-1530 ℃, the physical and chemical properties of the slag are best, the good fluidity of the slag at the end stage of desiliconization can be well ensured by controlling the physical and chemical properties of the slag in a green area, and the reduction and deslagging of metal oxides in the slag are very favorable. Therefore, the alkalinity of the slag should be controlled between 1.3 and 1.5, the Si content of the molten steel should be controlled between 0.3 and 0.4 percent, and the temperature is about 1500 ℃.
The redox reaction of silicon and chromium is as follows: cr (chromium) component 2 O 3 +Si→Cr+SiO 2 Theoretically, at 1500 ℃, the silicon content in the molten steel is higher than 0.35%, and the alkalinity in the slag is 1.4, the Cr in the slag 2 O 3 The equilibrium content is between 1.2 and 1.8% at a cost acceptable level. Therefore, the Si content at the end of desiliconization is reasonably controlled to be 0.3-0.4%.
The specific technical scheme of the invention is as follows:
1) and (4) loading the high-silicon premelted liquid into an AOD furnace, and measuring the temperature and sampling.
2) The cold charge adding amount, the lime adding amount and the oxygen blowing amount are calculated according to the furnace charging condition, and the calculation formula is as follows: firstly, the addition amount of cold materials ensures the temperature balance in the desilication period, and avoids the phenomenon that the carbon-oxygen reaction is violent and the splashing is caused because the temperature rises too fast, and the calculation formula is as follows: the cold charge addition amount is not larger than = (= (silicon content in furnace-0.35%) × 31 ÷ 8+ the early-stage material Si content is not larger than the steel conversion amount is not larger than 31 ÷ 8, and the end-point Si content is controlled to be 0.35%; the temperature of blowing 0.1 percent of Si content is raised to 31 ℃; the temperature of each ton of cold materials is reduced by 8 ℃. Secondly, lime is supplemented in the blowing desiliconization period, the binary alkalinity at the final desiliconization period is controlled to be 1.3-1.5, and the calculation formula is as follows: lime addition amount = ((silicon content in furnace-0.35%) × steel conversion amount + early-stage material Si content) × 2.14 × 1.4, and the end point Si content is controlled at 0.35%; the binary alkalinity of the desiliconization end point is controlled to be 1.4. And thirdly, when the amount of desiliconized oxygen ensures that the content of Si in the pre-molten liquid reaches a target value, the excessive oxygen blowing amount is avoided, so that the content of chromium oxide in the slag is high due to the low content of Si at the desiliconization end point, and meanwhile, the violent carbon-oxygen reaction and the splashing caused by the too low content of Si are also possible. The oxygen blowing amount in the desiliconization period is calculated according to the following formula: oxygen blowing amount in desiliconization period = ((furnace silicon-0.35%) × steel adding amount × 0.8+ Si content in the previous period × 0.8) ÷ oxygen utilization rate, and the Si content in the end point is controlled to be 0.35%; the oxygen utilization rate is 65-85%; the oxygen blowing amount fluctuates between 65 percent and 85 percent according to different desiliconization utilization rates of silicon and carbon contents in the furnace, the oxygen utilization rate changes along with the change of the carbon content of silicon in the furnace, the carbon in the furnace is high, and the low silicon can cause the reduction of the desiliconization oxygen utilization rate.
3) When the oxygen blowing amount reaches 85%, the flame at the furnace mouth is observed, when the flame overflows and a small amount of slag splashes at the furnace mouth, the carbon-oxygen reaction is accelerated, the slag layer begins to foam, and the blowing is stopped at the moment.
4) And after stopping blowing, using bottom blowing stirring to reduce the chromium oxide in the slag by utilizing the good fluidity of the steel slag and the residual Si in the molten steel.
5) Shaking the furnace to 85-90 degrees, pouring the low-alkalinity slag into a slag pot, shaking the furnace to-3 degrees, and starting normal smelting.
The specific implementation steps are as follows:
1) after adding the stainless steel pre-melting liquid, measuring the temperature and sampling, and calculating the lime addition, the oxygen blowing amount and the cold charge addition according to the furnace charging conditions.
2) The oxygen supply intensity after blowing is controlled to be 1.7-1.9 Nm 3 And v (min/t), the gun position adopts a low gun position operation.
3) After blowing is started, lime is added for slagging, and the calculated value is controlled to be 20-30 Kg/t.
4) And in the blowing process, cooling cold materials are added into the molten pool in batches according to the oxygen blowing amount and the oxygen blowing time, and the constant speed of the addition is followed, so that the temperature of the molten pool is ensured to be stabilized between 1450 and 1550 ℃.
5) The cold charge addition follows the principle of priority of high-silicon high-carbon materials and priority of heavy materials with high alloy components.
6) When the oxygen blowing reaches the target value, the color of the flame is observed, and when the temperature rises and a little slag splashes outwards, the oxygen blowing is stopped.
7) The side gun is stirred by inert gas, and the stirring flow is controlled to be 0.9Nm 3 /(min/t), the stirring time is controlled between 3 and 5 minutes.
8) And (4) shaking the furnace to 85-90 ℃, pouring the low-alkalinity slag into a slag pot, and shaking the furnace to-3 ℃ to start normal smelting after the slag cannot flow out.
Example 1
180 tons of AOD are used for producing SUS304 stainless steel, and a process of intermediate frequency furnace + AOD + LF + CC is adopted.
1) The steel adding amount is 108t, and the steel adding components are as follows: 3.53 percent of C, 3.15 percent of Si, 21.54 percent of Cr, 4.51 percent of Ni and 1408 ℃ of steel mixing temperature.
2) After steel is added, the furnace is shaken to-3 ℃ and blowing is started, and the flow of the oxygen lance is 220Nm 3 Min, gun position 1.9m, oxygen 80Nm for side gun main gas 3 Min, nitrogen 20Nm 3 Min; lime was added 5t after the start of blowing.
3) After blowing for 4min, the oxygen blowing amount reaches 1400Nm 3 And adding 55t of cold charge into the blowing stopping material tank, and continuously blowing by adopting the parameters.
3) Converting to 3000Nm 3 During oxygen, lime is added for 5t, high-level 30t of cold burden is added at a constant speed, and the adding speed of the cold burden is controlled at 3 t/min.
4) Converting to 4000 Nm 3 And adding lime for 4t when oxygen is used, and continuously blowing the mixture with unchanged blowing parameters.
5) The oxygen blowing amount reaches 6500Nm 3 Stopping oxygen, stirring for 3.5min at a side lance flow rate of 100 Nm3/min, deslagging by rocking a furnace, and measuring temperature: 1501 ℃, sample composition: 3.24 percent of C and 0.26 percent of Si, meets the target requirement, has good slag fluidity at the end of desiliconization and Cr in slag 2 O 3 The content is 2.27 percent, and the target requirement is met.
In the example, the addition amount of slagging lime is gradually increased along with the oxygen blowing amount, the addition speed of the cold charge is controlled, the temperature of the molten pool is stable, the desiliconization effect is good, and the phenomenon of splashing in the desiliconization period does not occur.
Example 2
180 tons of AOD are used for producing SUS316 stainless steel by adopting the processes of (intermediate frequency furnace + electric furnace) + AOD + LF + CC.
1) Adding steel 180t, adding steel components: 2.499 percent of C, 1.19 percent of Si, 19.07 percent of Cr, 4.35 percent of Ni and 1552 ℃ of steel mixing temperature.
2) After steel is added, the furnace is shaken to-3 ℃ to start blowing, and the flow of the oxygen lance is 180Nm 3 Min, the gun position is 1.8m, oxygen used by side gun main gas is 80Nm3/min, and nitrogen used by side gun main gas is 20Nm 3/min; lime was added 5t after the start of blowing.
3) After blowing for 2min, the oxygen blowing amount reaches 800Nm 3 And (5) starting to add the high-position 20t of cold materials at a constant speed, and controlling the adding speed of the cold materials at 3 t/min.
4) Blowing to 1500Nm 3 During oxygen, lime is added for 2t, and the blowing is continued with unchanged blowing parameters.
5) The oxygen blowing amount reaches 2500Nm 3 Stopping oxygen, stirring for 4.0min at the side lance flow rate of 100 Nm3/min, deslagging by rocking the furnace, and measuring the temperature: 1552 ℃, sampling composition: 2.15 percent of C and 0.31 percent of Si, meets the target requirement, has good slag fluidity at the end of desiliconization and Cr in slag 2 O 3 The content is 2.03 percent, and the target requirement is met.
In the example, the addition amount of slagging lime is gradually increased along with the oxygen blowing amount, the addition speed of the cold charge is controlled, the temperature of the molten pool is stable, the desiliconization effect is good, and the phenomenon of splashing in the desiliconization period does not occur.
The method reasonably controls the slag alkalinity, the molten pool temperature and the desiliconization end point Si content in the desiliconization period of the stainless steel smelting, reasonably controls the oxygen blowing amount in the desiliconization period, and effectively controls the splashing in the desiliconization period of the stainless steel smelting. The method reduces the oxidation of the alloy while ensuring the desiliconization, ensures the fluidity of the slag by reasonably controlling the physicochemical characteristics of the slag at the end point of the desiliconization period, ensures the successful pouring of the low-alkalinity slag, and creates good conditions for the subsequent decarburization.
The above description is only an embodiment of the present invention, but the structural features of the present invention are not limited thereto, and any changes or modifications within the scope of the present invention by those skilled in the art are covered by the present invention.
Claims (4)
1. A method for controlling splashing in the desiliconization period of smelting stainless steel is characterized in that: the method comprises the following steps:
(1) loading the high-silicon premelting liquid into an AOD furnace, and measuring and sampling temperature;
(2) the cold charge adding amount, the lime adding amount and the oxygen blowing amount are calculated according to the furnace charging condition, and the calculation formula is as follows:
1) the formula for calculating the addition of the cold charge is as follows: the cold charge addition amount is = (the silicon content in the furnace is-0.35%) × 31 ÷ 8+ the early-stage material Si content is ÷ steel conversion amount is × 31 ÷ 8; controlling the end point Si content at 0.2-0.5%, converting at 0.1%, heating Si content to 28-35 deg.C, and cooling to 7-11 deg.C per ton of cold charge;
2) replenishing lime in the blowing desilication period to ensure that the binary alkalinity at the final desilication stage is controlled to be 1.3-1.5, wherein the calculation formula is as follows: lime addition amount = ((silicon content in furnace-0.35%) × steel conversion amount + early-stage material Si content) × 2.14 × 1.4; the Si content at the end point is controlled to be 0.2-0.5%, and the binary alkalinity at the desiliconization end point is controlled to be 1.2-1.6;
3) the oxygen blowing amount in the desiliconization period is calculated according to the following formula: oxygen blowing amount in the desiliconization period = ((furnace silicon-0.35%) × steel adding amount × 0.8+ Si content in the previous period × 0.8) ÷ oxygen utilization rate; the end point Si content is controlled to be 0.2-0.5%, and the oxygen utilization rate is 65-85%; the oxygen blowing amount is between 65 and 85 percent according to different desiliconization utilization rates of the silicon and carbon contents in the furnace;
(3) observing the flame at the furnace mouth when the oxygen blowing amount reaches 80-90%, and stopping blowing when the flame overflows and a small amount of slag splashes at the furnace mouth and the carbon-oxygen reaction is intensified, the slag layer begins to foam;
(4) stopping blowing, and reducing chromium oxide in the slag by using bottom blowing stirring and utilizing good fluidity of the steel slag and residual Si in the molten steel;
(5) shaking the furnace to 85-90 degrees, pouring the low-alkalinity slag into a slag pot, shaking the furnace to 0-4 degrees, and starting normal smelting.
2. The method for controlling splashing in the desilication period of the smelted stainless steel according to claim 1, characterized by comprising the following steps: after blowing, the oxygen supply intensity is controlled at 1.7-1.9 Nm3/(min/t), and the gun position is operated at a low gun position.
3. The method for controlling splashing in the desilication period of the smelted stainless steel according to claim 1, characterized by comprising the following steps: and in the blowing process, cooling cold materials are added into the molten pool in batches according to the oxygen blowing amount and the oxygen blowing time, the feeding follows a constant speed, and the temperature of the molten pool is ensured to be stabilized between 1450 and 1550 ℃.
4. The method for controlling splashing in the desilication period of the smelted stainless steel according to claim 1, characterized by comprising the following steps: the side gun is stirred by inert gas, and the stirring flow is controlled to be 0.7-1.1Nm 3 /(min/t), the stirring time is controlled between 3 and 5 minutes.
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