High-efficiency and low-cost ultralow-phosphorus-sulfur steel production method applied to converter refining process

Abstract

The invention provides a high-efficiency and low-cost ultralow-phosphorus-sulfur steel production method applied to a converter refining process, and belongs to the technical field of ferrous metallurgy. Comprising the steps of molten iron pretreatment deep desulfurization ([S] < = 0.001%), converter smelting, slagging-off, LF furnace feeding, power transmission temperature raising deoxidation, temperature measurement and sampling, power transmission temperature raising deoxidation, component fine adjustment, temperature measurement and sampling, component temperature fine adjustment, tapping, calcium treatment, soft blowing and steel feeding, and the molten iron is subjected to extreme deep desulfurization ([S] < = 0.001%) through a KR process. The sulfur load is thoroughly eliminated from the source; in the converter process, a single slag remaining method is adopted, a low-high-low dynamic oxygen supply system and a composite slag charge technology are combined, deep dephosphorization and decarbonization are synchronously completed in a single smelting period, and fine component adjustment and accurate temperature control are ensured through tapping slag washing, thorough slagging-off and LF short-process rapid treatment, so that the production cost is remarkably reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of steel metallurgy, and particularly relates to a high-efficiency and low-cost ultra-low phosphorus and sulfur steel production method applied to a converter refining process. BACKGROUND

[0002] With the rapid development of modern industry, especially the fields of aerospace, ocean engineering, new energy and high-end equipment manufacturing, the performance requirements for steel are becoming increasingly stringent. Ultra-low phosphorus ([P]≤0.005%) and ultra-low sulfur ([S]≤0.005%) or even extremely low phosphorus and sulfur ([P]≤0.003%, [S]≤0.003%) high-purity steel has become an indispensable key material. As the most harmful impurity elements in steel, phosphorus and sulfur can seriously deteriorate the toughness, welding performance, hydrogen-induced cracking (HIC) performance and low-temperature impact performance of the steel. Therefore, achieving economic, efficient and stable control of ultra-low phosphorus and sulfur is one of the core challenges of the progress of modern steelmaking technology.

[0003] At present, the mainstream process route for producing ultra-low phosphorus and sulfur steel in domestic and foreign converter steel plants is usually “hot metal pretreatment → converter dephosphorization → (reversing furnace / reversing slag) → converter decarburization → tapping → LF furnace deep desulfurization → RH vacuum treatment”. Although this traditional “double combination method” or “double slag method” can achieve the target, it has many inherent disadvantages: 1. High production cost: double slag operation or double combination process leads to a significant extension of the smelting cycle, reduces the converter operation rate, and there is a large amount of iron loss and heat loss in the process, which greatly increases the energy consumption and cost per ton of steel.

[0004] 2. Complex process flow: multiple reversing furnace and slag operations are required, the operation is complicated, the production process stability is poor, the precision of the end point control is extremely high, and any slight mistake will cause the composition or temperature to be out of range, resulting in steel modification or re-melting.

[0005] 3. Heavy burden on the refining process: excessive reliance on the deep desulfurization capacity of the LF furnace (ladle refining furnace) leads to high LF power consumption, long smelting time, severe furnace lining erosion, and the use of a large amount of deoxidizer and synthetic slag material, which increases aluminum consumption and slag material cost.

[0006] 4. Quality control risk: the long process flow increases the risk of secondary oxidation and rephosphorization and resulfurization of the molten steel, bringing uncertainty to the stable control of the final product quality.

[0007] Therefore, the industry urgently needs to develop a new process method that can realize the simultaneous and efficient removal of phosphorus and sulfur in the converter, maximize the efficiency of converter smelting, simplify the subsequent refining burden, and ultimately achieve efficient, low-cost and stable production of ultra-low phosphorus and sulfur steel. SUMMARY

[0008] To solve the above technical problems, the application provides a high-efficiency and low-cost ultra-low phosphorus and sulfur steel production method applied in a converter refining process, which is suitable for the production operation of all ultra-low P and S steels with aluminum deoxidization.

[0009] To achieve the above object, the application adopts the following technical scheme: a high-efficiency and low-cost ultra-low phosphorus and sulfur steel production method applied in a converter refining process, which comprises the following steps in sequence: 1) The molten iron is placed in a ladle and then is sent to a KR desulfurization station, and a desulfurizer is added to the molten iron for deep desulfurization; the stirring speed is controlled to be 100-125 rpm during charging, the stirring speed is controlled to be 170-180 rpm after charging, the stirring time is controlled to be 17-23 min, and the sulfur content of the molten iron after desulfurization is less than or equal to 0.001%.

[0010] The charging stage: low-speed stirring (100-125 rpm) realizes "safe dispersion and prevents splashing". The purpose is to ensure that the desulfurizer (usually CaO-based or CaC2-based powder) can smoothly and uniformly immerse into the surface of the molten iron instead of being violently blown away.

[0011] The principle is wetting and penetration: the desulfurizer is a powder with a density much lower than that of the molten iron. If high-speed stirring is started at the beginning, the strong vortex will push these light powders away and raise them instantly, causing a lot of smoke and material loss, and cannot effectively enter the molten iron to participate in the reaction. The lower initial speed allows the desulfurizer to be smoothly spread on the surface of the molten iron and gradually be "captured" and wetted by the vortex edge.

[0012] Avoiding violent reaction: the desulfurizer will have an endothermic reaction when it contacts with the molten iron. Instantaneous large input and violent stirring may cause local temperature to drop sharply, and even cause the molten iron to splash. Low-speed charging gives the system a buffer and preheating stage.

[0013] Reaction stage: High speed stirring (170-180 rpm) to achieve "intensive mixing, ultimate mass transfer". This is the key stage to achieve deep desulphurization ([S] ≤ 0.001%). The core purpose of high speed stirring is to maximize the reaction interface and intensify the mass transfer process. Principle 1: Create a huge reaction interface - "emulsification" effect. At high speed of 170-180 rpm, the stirrer will form a deep vortex ("crater") in the molten iron and "voluntarily" bring the upper slag (slag phase composed of desulfurization products CaS and unreacted desulfurizer) into the molten iron. The strong shear force will "tear" the large slag phase into countless micron-sized small slag droplets and disperse them uniformly in the entire molten iron pool. This process is called "emulsification". Key point: chemical reaction occurs at the interface of two phases. After emulsification, these tiny slag droplets provide a huge total reaction surface area, so that [S] in molten iron has countless "sites" to migrate to the slag and be fixed. The reaction interface changes from "a calm lake surface" to "a soda water full of countless micro-bubbles", and the efficiency increases exponentially. Principle 2: Intensify mass transfer - reduce boundary layer thickness. The essence of desulfurization reaction is: [atomic S] in molten iron → diffuse to slag-iron interface → react with (CaO) in slag to form (CaS) into slag phase. The limiting factor of the entire reaction speed is often the diffusion speed of [S] from the interior of molten iron to the interface.

[0014] According to the principle of fluid mechanics, the strong turbulence generated by high speed stirring can greatly thin the "diffusion boundary layer" of the molten iron side and the slag side. The thinner the boundary layer, the thinner the "resistance layer" that [S] atoms need to diffuse through, and the faster the diffusion speed. At the same time, the turbulence ensures the rapid homogenization of [S] concentration in the molten iron, avoiding the existence of local high concentration or "dead zone", so that the desulfurization reaction can continue and thoroughly. Principle 3: Continuous update of reaction interface, the strong flow brought by high speed stirring makes the slag-iron interface constantly washed and updated. The CaS product generated by the reaction is quickly taken away, and fresh desulfurizer with high sulfur capacity is continuously transported to the interface, maintaining the driving force for the reaction to continue in the positive direction (desulfurization).

[0015] 2) Add a kind of low S scrap steel and molten iron to the converter, add and smelt, use top and bottom combined blowing converter to smelt, adopt single slag and slag method, the molten iron accounts for 90-95%, and the rest is a kind of low S scrap steel, the phosphorus content in the molten iron is ≤0.100%, the phosphorus content in the a kind of low S scrap steel is ≤0.015%, and the sulfur content is ≤0.015%.

[0016] Single slag residue method refers to: after the last furnace steel out, not to pour out the end of the furnace slag, but to leave a part (usually 1 / 3 to 1 / 2 of the total amount of slag) of high basicity, high oxidizing slag in the converter for the next furnace smelting. Effect: the left over slag is called "residual slag", rich in FeO, which provides a basis for the rapid formation of the initial slag with good liquidity and oxidation in the early stage of the new furnace blowing, greatly speeding up the speed of early slag and slag formation. High basicity: the end of the slag is high basicity saturated lime slag, which provides a ready source of CaO for the new furnace, saves part of the new lime consumption, and establishes a high basicity environment in advance.

[0017] 3) The converter lower gun oxygen ignition is normal, low-phosphorus and low-sulfur slagging auxiliary materials are added, and the blowing adopts low-high-low q position oxygen supply operation mode, and the oxygen supply intensity is controlled at 2.9-4.8 Nm 3 / (min·t), the bottom blowing argon flow is controlled at 0.18-0.25 Nm 3 / (min·t), the ignition gun position is set to 1800 mm, after normal ignition, the blowing is carried out to 8% of the oxygen supply process, and then it is lifted to the normal blowing gun position of 1800-2200 mm, the ignition flow is 23000 Nm 3 / h, the oxygen supply is automatically increased to 50000-60000 Nm 3 / h after the first time, the deep blowing gun position is lowered to 1000 mm, and the oxygen supply is increased to 67000 Nm 3 / h, deep decarburization and uniform steel composition and temperature are carried out; at the same time, composite slag is added in the furnace.

[0018] Early "low" gun position - create the best window for dephosphorization: in the early stage of blowing, low gun position is used to strengthen stirring, the core purpose of which is to use the thermodynamic characteristics of the strong exothermic reaction of dephosphorization reaction. In a low temperature environment, the oxidation driving force of phosphorus is much greater than that of carbon. Strong stirring ensures that the high-oxidizing slag and low-temperature molten iron are fully mixed, and the limit removal of phosphorus is realized within the "golden temperature window" of dephosphorization. Late "low" gun position (deep blowing) - overcome diffusion resistance: in the late stage of blowing, the carbon content is reduced, and the dephosphorization driving force is weakened. At this time, the last strong stirring is carried out again by using low gun position, and the principle is to overcome the diffusion resistance of material transmission. Strong turbulence can thin the diffusion boundary layer of steel-slag interface, "pump" the residual phosphorus in the steel to the slag interface, and finally be captured by high basicity slag, solving the slow reaction kinetics problem at ultra-low phosphorus level; "Composite slag" quickly establishes a high-efficiency reaction zone: the essence of this slag (TCa 30%, TFe 30%) is a "high-activity synthetic slag slurry". High TFe enables it to melt instantly and greatly increase the oxidation of the local area; high TCa provides immediately available free CaO. The combination of the two quickly forms a high-alkalinity, high-oxidizing "reaction-active zone" in the furnace during the later stage of blowing. Emulsification and interface effect: this slag is extremely easy to be "emulsified" into micron-sized slag droplets under strong stirring, greatly increasing the total surface area of the steel-slag reaction. These countless micro-droplets of slag scattered throughout the molten pool act as efficient "micro-phosphorus traps", through the huge specific surface area, the last adsorption and fixation of residual phosphorus and sulfur in the molten steel, so as to push the phosphorus and sulfur content to an extremely low level that is difficult to achieve by conventional operation. In summary, the present application occupies the thermodynamic advantage by "slagging", controls the reaction sequence of temperature and elements by "low-high-low" mode, and finally solves the kinetic diffusion problem of extreme purity by the emulsification effect of "special slag". The three are closely linked, systematically optimizing the whole process from reaction start, process control to end sprint, thereby realizing the extreme ability of ultra-low phosphorus and sulfur in a single converter smelting cycle.

[0019] 4) When blowing to 80% of the oxygen supply process, use the TSC probe of the side gun to measure carbon, temperature and sampling, then add part of the slag-making material according to the measured carbon and temperature for adjustment, and according to the detection results of the side gun, smelting tracking is carried out until the smelting process requirements are met, the gun is started, and the TSO probe of the side gun is used for carbon measurement, temperature measurement, sampling and oxygen measurement at the end of blowing.

[0020] 5) Smelting end point control: carbon ≤0.04%, phosphorus ≤0.003%, sulfur ≤0.004% and temperature ≥1630℃.

[0021] Preferably, the composition and mass percentage of the composite slag in step 3 are: TCa content 30%, TFe content 30%, SiO2 content 5%, and the rest is CaO.

[0022] Preferably, the temperature of the molten iron entering the desulfurization station in step 1 is ≥1250℃, and the amount of desulfurizer is controlled to be 11-15 kg / t.

[0023] Preferably, the slag-making material in step 4 is a slag modifier, including active lime for increasing alkalinity, iron ore or sintered ore for temperature reduction and oxidation adjustment, and fluorite for improving fluidity if necessary.

[0024] Preferably, the slag-making auxiliary material in step 3 is lime, dolomite and sintered ore, wherein the sulfur content in lime is ≤0.005%, the sulfur content in dolomite is ≤0.005%, and the sulfur content in sintered ore is ≤0.001%.

[0025] Compared with the prior art, the advantages and positive effects of the present application are that: through the deep desulfurization pretreatment of hot metal, the high-strength "single-slag remaining slag method" precise smelting of converter, and the organic combination of high-efficiency slagging after the furnace and the rapid refining of LF, a new efficient and low-cost ultra-low phosphorus and sulfur steel production process is constructed; through the extreme deep desulfurization of KR process on hot metal ([S]≤0.001%), the sulfur load is completely eliminated from the source; in the converter process, the "single-slag remaining slag method" is adopted, combined with the innovative "low-high-low" dynamic oxygen supply system and the "special composite slag material" technology, the deep dephosphorization and decarburization are simultaneously completed in a single smelting cycle, and the limit ability of dephosphorization of the converter is challenged. Through the tapping slag washing, complete slagging and LF short process rapid treatment, the composition fine tuning and temperature accurate control are ensured, the whole process operation time is greatly shortened, and the production cost is significantly reduced under the premise of ensuring the quality. DETAILED DESCRIPTION

[0026] In order to more clearly understand the above-mentioned purposes, features and advantages of the present application, the present application will be further described below through examples. It should be noted that the examples of the present application and the features in the examples can be combined with each other without conflict.

[0027] In the following description, many specific details are set forth in order to provide a thorough understanding of the present application, however, the present application can also be practiced in other ways different from those described herein, therefore, the present application is not limited to the specific embodiments disclosed in the following description. Example 1

[0028] The present embodiment provides a high-efficiency and low-cost ultra-low phosphorus and sulfur steel production method applied in the converter refining process, The chemical composition of the oil pipe TDXG20 is as follows in terms of weight percentage:

[0029] The balance is iron.

[0030] The present embodiment realizes the generation of the oil pipe TDXG20 through the following method steps, and the finished product P reaches 0.0045% and the finished product S reaches 0.0004%.

[0031] The steps are as follows: 1) The hot metal is placed in the KR desulfurization station, the desulfurizer is added to the hot metal for deep desulfurization, the temperature of the hot metal entering the desulfurization station is 1250℃, the dosage of the desulfurizer is controlled to be 13kg / t, the stirring speed of the stirrer is controlled to be 115rpm during feeding, the stirring speed of the stirrer is controlled to be 175rpm after feeding, the stirring time is controlled to be 20min, and the sulfur content of the desulfurized hot metal is 0.0009%; 2) Converter plus a low S scrap steel, add molten iron, charging smelting, using top and bottom combined blowing converter smelting, using single slag method, molten iron accounts for 93%, the rest is a low S scrap steel, the phosphorus content in the molten iron is 0.100%, the phosphorus content in the said low S scrap steel is 0.015%, the sulfur content is 0.015%; 3) The converter opens oxygen ignition normally, and low-phosphorus and low-sulfur slagging auxiliary materials are added, the slagging auxiliary materials are lime, dolomite and sinter, wherein the sulfur content in the lime is 0.005%, the sulfur content in the dolomite is 0.005%, and the sulfur content in the sinter is 0.001%, the blowing adopts a low-high-low lance position oxygen supply operation mode, the oxygen supply intensity is controlled to be 3.5 Nm 3 / (min·t), the bottom argon flow is controlled to be 0.20 Nm 3 / (min·t), the ignition lance position is set to be 1800 mm, after normal ignition, the blowing is carried out to 8% of the oxygen supply process, and then the normal blowing lance position 2000 mm is lifted, the ignition flow is 23000 Nm 3 / h, the oxygen supply amount is automatically increased to 55000 Nm 3 / h after the first time, the deep blowing lance position is reduced to 1000 mm before the lance is started at the end point, and the oxygen supply amount is increased to 67000 Nm 3 / h, deep decarburization and uniform molten steel composition and temperature are carried out; at the same time, 500 kg of composite slag is added into the furnace, and the composition and mass percentage of the composite slag in step 4 are as follows: TCa content 30%, TFe content 30%, SiO2 content 5%, and the rest is CaO; 4) When the blowing is carried out to 80% of the oxygen supply process, the TSC probe of the sub-lance is used for carbon determination, temperature measurement and sampling, and then part of the slagging material is added for adjustment according to the determined carbon and measured temperature, the slagging material is a slag adjusting agent, including active lime for increasing basicity, iron ore or sinter for reducing temperature and adjusting oxidizability, and fluorite for improving fluidity when necessary, smelting tracking is carried out according to the detection results of the sub-lance until the lance is started according to the smelting process requirements, and the TSO probe of the sub-lance is used for carbon determination, temperature measurement, sampling and oxygen determination at the end of blowing; 5) Smelting end point control: tapping carbon ≤0.04%, phosphorus 0.0025%, sulfur 0.0035%, and temperature 1630℃; 6) When the control requirements are reached, the molten steel is tapped, a certain amount of lime is added for slag washing during the tapping process, alloys are added into the ladle during the tapping process, and part of the lime is added for thick slag treatment after the tapping is completed; after the tapping is completed, the ladle is lifted to the slag removing position for slag removing operation, (the P removal operation is mainly carried out in the converter, and the purpose of the slag removing here is to remove the oxidizing slag to prevent P return); 7) After the slag removing is completed, the steel is adjusted to the LF furnace; the ladle is lifted to the refining position, and after the ladle is seated, the bottom argon flow is 700-900 NL / min (pressure 1.2-1.5 Mpa); 8) After entering the refining furnace, add lime 8 kg / t and refining slag 1200 kg / furnace to make slag and remove sulfur, with basicity range 9-13 (large amount of slag and high basicity are the key to control S removal); 9) Adjust argon flow to a certain range: 600-800 NL / min (pressure 1.1-1.3 Mpa), then start power supply, the first stage power supply time control 25-30 min, use a certain amount of composite deoxidizer 150 kg (aluminum particles, calcium wire, calcium carbide, etc. mixed according to the proportion of 3:3:4) for diffusion deoxidation, appropriate argon stirring intensity and deoxidation operation are the key to control S removal); 10) After the first power supply, adjust the argon flow to 700-900 NL / min (pressure 1.2-1.5 Mpa) for 2-3 min, then close the argon and take the molten steel sample (code LF-1) and slag sample; 11) Adjust the argon flow to a certain range of 400-600 NL / min (pressure 0.8-1.0 Mpa), continue to supply power to heat the molten steel, and add a certain amount of deoxidizer composite deoxidizer 80 kg (aluminum particles, calcium wire, calcium carbide, etc. mixed according to the proportion of 3:3:4) to the steel slag in batches; the laboratory reports LF-1 composition: P reaches 0.0038%, S reaches 0.0009%. Then add alloy according to the test data of the steel sample, add carbonizer, adjust argon, and take the sample after the electrode is raised (code LF-2), measure the temperature and take the slag sample; 12) Adjust the argon flow to a range of 200-300 L / min (pressure 0.5-0.8 Mpa), continue to supply power for a certain time to heat the molten steel, and add a certain amount of composite deoxidizer 30 kg (aluminum particles, calcium wire, calcium carbide, etc. mixed according to the proportion of 3:3:4) to the steel slag in batches; confirm the composition LF-2: P reaches 0.0039%, S reaches 0.0004%; 13) Adjust the argon flow to a certain range of 100-200 L / min (pressure 0.3-0.5 Mpa), continue to supply power, and confirm the composition, temperature and rhythm after the electrode is raised, then tap the steel; 14) Adjust the argon flow to 50-100 L / min (pressure 0.2-0.35 Mpa), tap the steel, and start soft blowing; 15) Feed the calcium wire at a certain speed for 10-15 meters; 16) Soft blow for a certain time; after soft blowing, lift the steel for pouring. Example 2

[0032] In this example, the production of oil well pipe JDXY01 is also realized by applying the high-efficiency and low-cost ultra-low phosphorus and sulfur steel production method in the converter refining process, and the finished product P reaches 0.0050% and the finished product S reaches 0.0005%.

[0033] The chemical composition of the oil well pipe JDXY01 is as follows in terms of percentage by weight:

[0034] The method comprises the following steps in sequence: 1) The molten iron is fed to the KR desulfurization station, and a deep desulfurization is performed on the molten iron by adding a desulfurizing agent, the temperature of the molten iron entering the desulfurization station is 1250℃, the dosage of the desulfurizing agent is controlled to be 13 kg / t, the stirring speed of the stirrer is controlled to be 115 rpm during feeding, the stirring speed of the stirrer is controlled to be 175 rpm after feeding, the stirring time is controlled to be 20 min, and the sulfur content of the molten iron after desulfurization is 0.0009%; 2) A type of low-sulfur scrap steel is added to the converter, and the molten iron is added for smelting, a top and bottom combined blowing converter is used for smelting, a single-slag remaining slag method is adopted, the molten iron accounts for 93%, and the balance is a type of low-sulfur scrap steel, the phosphorus content in the molten iron is 0.100%, and the phosphorus content in the type of low-sulfur scrap steel is 0.015%, and the sulfur content is 0.015%; 3) The converter is ignited normally by opening the oxygen point with a gun, and a low-phosphorus and low-sulfur slag-making auxiliary material is added, the slag-making auxiliary material is lime, dolomite and sintered ore, wherein the sulfur content in the lime is 0.005%, the sulfur content in the dolomite is 0.005%, and the sulfur content in the sintered ore is 0.001%, the blowing adopts a low-high-low gun position oxygen supply operation mode, the oxygen supply intensity is controlled to be 3.5 Nm 3 / (min·t), the argon flow rate of bottom blowing is controlled to be 0.20 Nm 3 / (min·t), the ignition gun position is set to be 1800 mm, after normal ignition, the blowing is performed to 8% of the oxygen supply process, the normal blowing gun position is lifted to 2000 mm, the ignition flow rate is 23000 Nm 3 / h, the oxygen supply amount is automatically increased to 55000 Nm 3 / h in the first time, the deep blowing gun position is reduced to 1000 mm before the end gun, and the oxygen supply amount is increased to 67000 Nm 3 / h, deep decarburization and uniform molten steel composition and temperature are performed; at the same time, 500 kg of composite slag is added into the furnace, the composition and mass percentage of the composite slag in step 4 are as follows: TCa content 30%, TFe content 30%, SiO2 content 5%, and the balance is CaO; 4) When the blowing is performed to 80% of the oxygen supply process, the TSC probe of the sub-lance is used for carbon determination, temperature measurement and sampling, and then part of the slag-making material is added for adjustment according to the determined carbon and measured temperature, the slag-making material is a slag regulator, including active lime for increasing basicity, iron ore or sintered ore for reducing temperature and adjusting oxidation, and fluorite for improving fluidity when necessary, smelting tracking is performed according to the detection result of the sub-lance until the smelting process requirement is reached to start the gun, and the TSO probe of the sub-lance is used for carbon determination, temperature measurement, sampling and oxygen determination after the blowing is completed; 5) Smelting end control: tapping carbon ≤0.04%, phosphorus 0.0030%, sulfur 0.0050%, temperature 1630℃; 6) Steel tapping is carried out to reach the control requirements, a certain amount of lime is added during the tapping process for slag washing, alloy is added into the ladle during the tapping process, and part of the lime is added again for thick slag treatment after the tapping is completed; after the tapping is completed, the ladle is lifted to the slag removal station for slag removal operation, (the P removal operation is mainly carried out in the converter, and the purpose of the slag removal here is to remove the oxidizing slag to prevent P back) ; 7) After the slag removal is completed, the steel is adjusted to the LF furnace; the ladle is lifted to the refining station, and after the ladle is seated, the argon gas flow is 700-900 NL / min (pressure 1.2-1.5 Mpa) ; 8) After entering the refining furnace, 8 kg / t of lime and 1200 kg / furnace of synthetic slag are added for slagging and desulfurization, and the basicity range is 9-13 (large amount of slag and high basicity are the key to control S removal) ; 9) After adjusting the argon gas flow to a certain range: 600-800 NL / min (pressure 1.1-1.3 Mpa), start power supply, the first stage power supply time is controlled for 25-30 min, a certain amount of composite deoxidizer 150 kg (aluminum particles, calcium wire, calcium carbide, etc. in a mixture of 3:3:4 ratio) is used for diffusion deoxidation; (appropriate argon stirring intensity and deoxidation operation are the key to control S removal) ; 10) After the first power supply is completed, the electrode is lifted, the argon gas flow is adjusted to 700-900 NL / min (pressure 1.2-1.5 Mpa) for 2-3 min, then the argon gas is turned off, the temperature is measured, and the molten steel sample (code LF-1) and slag sample are taken; 11) Adjust the argon gas flow to a certain range of flow 400-600 NL / min (pressure 0.8-1.0 Mpa), continue to supply power to heat the molten steel, and at the same time, a certain amount of deoxidizer composite deoxidizer 80 kg (aluminum particles, calcium wire, calcium carbide, etc. in a mixture of 3:3:4 ratio) is added to the steel slag in batches; the laboratory reports the LF-1 composition: P reaches 0.0038%, S reaches 0.0009%. Then according to the test data of the steel sample, add alloy, add carbon additive, adjust argon, and lift the electrode after a certain time of power supply; lift the electrode, take the sample (code LF-2), measure the temperature, and take the slag sample; 12) Adjust the argon gas flow to a range of flow 200-300 L / min (pressure 0.5-0.8 Mpa), continue to supply power for a certain time of molten steel heating, and add a certain amount of composite deoxidizer 30 kg (aluminum particles, calcium wire, calcium carbide, etc. in a mixture of 3:3:4 ratio) to the steel slag in batches; confirm the composition LF-2: P reaches 0.0039%, S reaches 0.0004%; 13) electrode temperature measurement, slag sticking, fine adjustment of composition; adjust argon flow to a certain range of 100-200 L / min (pressure 0.3-0.5 MPa), continue to supply power, and confirm that the composition, temperature and rhythm are appropriate before tapping; 14) adjust argon flow to 50-100 L / min (pressure 0.2-0.35 MPa), tap, and start soft blowing; calcium treatment; 15) feed a certain amount of calcium wire at a certain speed, 10-15 meters; 16) soft blowing for a certain period of time; after soft blowing is completed, hoist the steel for pouring. Example 3

[0035] This example also realizes the production of oil well pipe EY27MSS-1 by applying the high-efficiency and low-cost ultra-low phosphorus and sulfur steel production method in the converter refining process, and the finished product P reaches 0.0050%, and the finished product S reaches 0.0005%.

[0036] The chemical composition of the oil well pipe EY27MSS-1 is as follows in terms of weight percentage:

[0037] The steps include the following in sequence: 1) The molten iron is placed into the KR desulfurization station, and a deep desulfurization is performed on the molten iron by adding a desulfurizing agent, the temperature of the molten iron entering the desulfurization station is 1250°C, the amount of the desulfurizing agent is controlled to be 13 kg / t, the stirring speed is controlled to be 115 rpm during feeding, the stirring speed is controlled to be 175 rpm after feeding, the stirring time is controlled to be 20 min, and the sulfur content of the desulfurized molten iron is 0.0009%; 2) A type of low-S scrap steel and molten iron are added to the converter for smelting, a top and bottom combined blowing converter is used for smelting, a single-slag and slag-remaining method is adopted, the molten iron accounts for 93%, and the balance is a type of low-S scrap steel, the phosphorus content in the molten iron is 0.100%, and the phosphorus content in the type of low-S scrap steel is 0.015%, and the sulfur content is 0.015%; 3) The converter is ignited normally with the oxygen lance lowered, low-phosphorus and low-sulfur slag-making auxiliary materials are added, the slag-making auxiliary materials are lime, dolomite and sintered ore, the sulfur content in the lime is 0.005%, the sulfur content in the dolomite is 0.005%, and the sulfur content in the sintered ore is 0.001%, the blowing adopts a low-high-low lance position oxygen supply operation mode, the oxygen supply intensity is controlled to be 3.5 Nm 3 / (min·t), the bottom argon flow is controlled to be 0.20 Nm 3 / (min·t), the ignition lance position is set to 1800 mm, after normal ignition, the blowing is carried out to 8% of the oxygen supply process, and then the lance position is raised to the normal blowing position 2000 mm, the ignition flow is 23000 Nm 3 / h, the oxygen supply amount is automatically increased to 55000 Nm 3 / h, the end of the gun before the deep blow gun position is lowered to 1000mm, and the oxygen supply is increased to 67000Nm 3 / h, deep decarburization and uniform molten steel composition and temperature are carried out; at the same time, 500kg of composite slag is added into the furnace, and the composition and mass percentage of the composite slag in step 4 are as follows: TCa content 30%, TFe content 30%, SiO2 content 5%, and the rest is CaO; 4) When the blowing is to 80% of the oxygen supply process, the TSC probe of the side gun is used for carbon determination, temperature measurement and sampling, and then part of the slagging material is added for adjustment according to the determined carbon and measured temperature, the slagging material is a slag adjusting agent, including active lime for increasing basicity, iron ore or sinter for reducing temperature and adjusting oxidizability, and fluorite for improving fluidity if necessary, smelting tracking is carried out according to the detection results of the side gun until the smelting process requirement is reached, and the blowing is ended, and the TSO probe of the side gun is used for carbon determination, temperature measurement, sampling and oxygen determination; 5) Smelting end control: carbon ≤0.04%, phosphorus 0.0025%, sulfur 0.0035%, and temperature 1630℃; 6) When the control requirements are reached, the steel is tapped, a certain amount of lime is added for slag washing during the tapping process, alloy is added into the ladle during the tapping process, and part of the lime is added again for thick slag treatment after the tapping is ended; after the tapping is ended, the ladle is lifted to the slag removing position for slag removing operation, (the P removal operation is mainly carried out in the converter, and the purpose of the slag removing here is to remove the oxidizing slag material to prevent P return); 7) After the slag removing is ended, the steel is adjusted to the LF furnace; the ladle is lifted to the refining position, and after the ladle is seated, the argon gas flow is 700-900NL / min (pressure 1.2-1.5Mpa); 8) After entering the refining furnace, 8kg / t of lime and 1200kg / furnace of synthetic slag are added for slagging and desulfurization, and the basicity range is 9-13, (large amount of slag and high basicity are the key to control S removal); 9) After adjusting the argon gas flow to a certain range: 600-800NL / min (pressure 1.1-1.3Mpa), the power supply is started, the first stage power supply time is controlled to 25-30min, a certain amount of composite deoxidizer 150kg (aluminum particles, calcium wire, calcium carbide, etc. are mixed in a proportion of 3:3:4) is used for diffusion deoxidation, (appropriate argon stirring intensity and deoxidation operation are the key to control S removal); 10) After the first power supply is ended, the electrode is lifted, the argon gas flow is adjusted to 700-900NL / min (pressure 1.2-1.5Mpa) for 2-3min, and then the argon gas is turned off to measure the temperature and take the molten steel sample (code LF-1) and the slag sample; 11) adjust argon flow to a certain range of flow 400-600NL / min (pressure 0.8-1.0Mpa), continue to send power to heat the molten steel, while adding a certain amount of deoxidizer composite deoxidizer 80kg (aluminum particles, calcium wire, calcium carbide, etc. mixture according to the ratio of 3:3:4) to the steel slag in batches; LF-1 composition reported by the laboratory: P reaches 0.0038%, S reaches 0.0009%. Then according to the test data of the steel sample, add alloy, add carbonizer, adjust argon, send power for a certain time, and lift the electrode; lift the electrode, take the sample (code LF-2), measure the temperature, and take the slag sample; 12) adjust argon flow to a certain range of flow 200-300L / min (pressure 0.5-0.8Mpa), continue to supply power for a certain time to heat the molten steel, and add a certain amount of composite deoxidizer 30kg (aluminum particles, calcium wire, calcium carbide, etc. mixture according to the ratio of 3:3:4) to the steel slag in batches; confirm the composition LF-2: P reaches 0.0039%, S reaches 0.0004%; 13) lift the electrode, measure the temperature, and adjust the composition; adjust the argon flow to a certain range of flow 100-200L / min (pressure 0.3-0.5Mpa), continue to supply power, confirm the composition, temperature and rhythm, and then tap the steel; 14) adjust argon flow to 50-100L / min (pressure 0.2-0.35Mpa), tap the steel, and start soft blowing; calcium treatment; 15) feed a certain amount of calcium wire at a certain speed 10-15 meters; 16) soft blowing for a certain time; after soft blowing is completed, lift the steel for pouring.

[0038] The above is only a preferred embodiment of the present application, and is not intended to limit the present application in other forms. Any skilled person in the art can modify or change the above disclosed technical content to equivalent embodiments applied to other fields, but any simple modification, equivalent change and modification of the above embodiments made according to the technical essence of the present application without departing from the technical solution content of the present application shall still fall within the protection scope of the present application.

Claims

1. A high-efficiency, low-cost method for producing ultra-low phosphorus and sulfur steel in a converter refining process, characterized in that, The method includes the following steps in sequence: 1) The molten iron is placed in the ladle at the KR desulfurization station, where desulfurizing agent is added to perform deep desulfurization. The agitator speed is controlled at 100-125 rpm during the addition of the agent, and then at 170-180 rpm after the addition. The stirring time is controlled at 17-23 min. The sulfur content of the desulfurized molten iron is ≤0.001%. 2) Add Class I low-S scrap steel and molten iron to the converter for smelting. Use a top-and-bottom combined blowing converter for smelting and adopt the single-slag retention method. The molten iron accounts for 90-95%, and the balance is Class I low-S scrap steel. The phosphorus content in the molten iron is ≤0.100%, and the phosphorus content and sulfur content in the Class I low-S scrap steel are ≤0.015% and ≤0.015%, respectively. 3) The converter's lower lance oxygen ignition is normal. Low-phosphorus and low-sulfur slag-forming additives are added. The blowing process adopts a low-high-low q lance position oxygen supply operation mode, and the oxygen supply intensity is controlled at 2.9-4.8 Nm. 3 / (min·t), the bottom-blown argon flow rate is controlled at 0.18-0.25 Nm³. 3 / (min·t), the initial blowing lance position is set to 1800mm. After normal ignition, when the blowing reaches 8% of the oxygen supply process, the lance position is raised to the normal blowing lance position of 1800-2200mm, and the ignition flow rate is 23000Nm. 3 / h, immediately and gradually increasing the oxygen supply to 50,000-60,000 Nm³. 3 / h, before the final blast, the deep blowing position is lowered to 1000mm, and the oxygen supply is increased to 67000Nm. 3 / h, to carry out deep decarburization and homogenize the composition and temperature of molten steel; at the same time, composite slag is added into the furnace; 4) When the blowing process reaches 80% of the oxygen supply process, use the auxiliary lance TSC probe to determine carbon, measure temperature and take samples. Then, add some slag-forming material to adjust according to the determined carbon and measured temperature. Follow up the smelting process according to the auxiliary lance test results until the smelting process requirements are met and the lance is lifted. After the blowing process is completed, use the auxiliary lance TSO probe to determine carbon, measure temperature, take samples and determine oxygen. 5) Smelting endpoint control: Carbon content of tapped steel ≤0.04%, phosphorus ≤0.003%, sulfur ≤0.004%, and temperature ≥1630℃.

2. The method for producing high-efficiency, low-cost ultra-low phosphorus and sulfur steel in the converter refining process according to claim 1, characterized in that: The composition and mass percentage of the composite slag material described in step 3 are as follows: TCa content 30%, TFe content 30%, SiO2 content 5%, and the remainder is CaO.

3. The method for controlling laser filament additive manufacturing process parameters based on molten pool images according to claim 1, characterized in that: In step 1, the temperature of the molten iron entering the desulfurization station is ≥1250℃, and the amount of desulfurizing agent is controlled at 11-15kg / t.

4. The method for controlling laser filament additive manufacturing process parameters based on molten pool images according to claim 1, characterized in that: The slag-forming material mentioned in step 4 is a slag conditioner, including active lime for increasing alkalinity, iron ore or sinter for cooling and adjusting oxidation, and fluorite for improving fluidity when necessary.

5. The method for controlling laser filament additive manufacturing process parameters based on molten pool images according to claim 1, characterized in that: The slag-forming auxiliary materials mentioned in step 3 are lime, dolomite, and sinter, wherein the sulfur content in lime is ≤0.005%, the sulfur content in dolomite is ≤0.005%, and the sulfur content in sinter is ≤0.001%.

Images