Rotary blowing desulfurization method

Abstract

The invention relates to the field of metallurgy, and discloses a rotary blowing desulfurization method, in a molten iron pretreatment process, molten iron in a molten iron ladle is desulfurized by sequentially spraying a first desulfurizer into the molten iron, adding a second desulfurizer into the surface of the molten iron and spraying a third desulfurizer into the molten iron. The rotary blowing desulfurization method disclosed by the invention is beneficial to shortening the desulfurization time and improving the production efficiency while meeting the desulfurization effect, and is suitable for popularization and application in iron and steel enterprises.

Description

Technical Field

[0001] The invention relates to the field of metallurgy, and in particular to a rotary jet desulfurization method. Background Art

[0002] At present, the following methods are widely used for hot metal desulfurization: mechanical stirring method, injection method, injection method, KR method, and magnesium-based desulfurization method. The mechanical stirring method is to immerse the stirrer in the hot metal and rotate it at high speed to generate strong vortex and convection motion, so that the added desulfurizer is fully mixed with the hot metal. The desulfurizer reacts chemically with the sulfur in the hot metal, and the generated sulfide enters the slag phase, thereby reducing the sulfur content of the hot metal. The equipment structure of the mechanical stirring method is complex, and the maintenance and replacement cost of the stirrer is high. A certain amount of air may also be brought in during the stirring process, increasing the oxidation of the hot metal. The injection method uses an inert gas as a carrier to spray the desulfurizer into the hot metal through a spray gun. The gas carries the desulfurizer to form a high-speed jet, so that the desulfurizer is evenly dispersed in the hot metal. The desulfurizer reacts with sulfur to generate sulfides that enter the slag phase or gas phase to achieve desulfurization. In the injection method, the desulfurizer is not in sufficient contact with the sulfur in the hot metal, the desulfurization efficiency is low, and the desulfurizer consumption is large. The injection method is to inject the desulfurizer directly into the surface of the molten iron. The desulfurizer melts and mixes with the molten iron under the heat of the molten iron, and reacts chemically with sulfur. The sulfide produced by the reaction enters the slag phase, and then the sulfur-containing slag is removed by slagging. In the injection method, it takes a certain amount of time for the desulfurizer to melt and mix on the surface of the molten iron, and it is easy to cause local overreaction and surface slagging, the desulfurization efficiency is low, and the utilization rate of the desulfurizer is not high. The KR method is a special form of mechanical stirring method, which is similar to the general mechanical stirring method, but the stirrer is a special cross or T-shaped, which can produce a stronger stirring effect when rotating at high speed. At the same time, the KR method has good adaptability to desulfurizers and can use a variety of desulfurizers. The KR method has a good desulfurization effect and can reduce the sulfur content of molten iron to a very low level, but the equipment is complex, the maintenance cost of the stirrer is high, and the technical requirements for operators are also high. The magnesium-based desulfurization method uses magnesium or magnesium-based alloy as a desulfurizer. Magnesium vaporizes rapidly in molten iron, and the generated magnesium vapor reacts with sulfur in the molten iron to form magnesium sulfide. The reaction speed is fast and can quickly reduce the sulfur content of molten iron. The magnesium-based desulfurizer can be added to the molten iron by spraying or pouring. The magnesium-based desulfurization method has extremely high desulfurization efficiency and fast reaction speed; however, the cost of magnesium is relatively high, and there are certain safety risks during the operation, which requires strict control of the operating environment and conditions.

[0003] CN 116463474 A discloses a method for deep desulfurization of molten iron based on pure spraying granular magnesium desulfurization process. While conventional pure spraying granular magnesium is carrying out molten iron desulfurization reaction, the lime-based desulfurization agent adding device is used to continuously add the lime-based desulfurization agent to the spraying desulfurization tumbling area at the center of the molten iron tank liquid surface according to the ratio of the metal granular magnesium spraying amount to the lime-based desulfurization agent addition amount per unit time of 1:3 to 1:6; when the spraying end time is reached, the metal granular magnesium spraying and the addition of the lime-based desulfurization agent are stopped, and the spray gun is kept inserted without The mixture is stirred by blowing and carrier gas for 1 to 2 minutes, the blowing and carrier gas stirring is stopped, the spray gun is raised to the standby height, and the desulfurization of the molten iron is completed; the raw materials of the lime-based desulfurizer include 70 to 85% of active lime particles and 15 to 30% of additives by weight, and the raw materials of the additives include 37 to 63% of sintered calcium aluminate, 6 to 13% of used magnesium carbon brick particles, 15 to 30% of industrial grade soda ash, 6 to 13% of fluorite and 10 to 20% of silicon-aluminum-calcium-carbon alloy by weight. The prior art realizes the synergistic composite desulfurization reaction of conventional pure spraying of metal particles magnesium molten iron desulfurization and adding lime-based desulfurizer interface desulfurization in the tumbling area of ​​the center of the molten iron liquid surface. However, the industrial grade soda ash and fluorite of the prior art have an erosive effect on the refractory lining of the desulfurization equipment under high temperature environment, thereby increasing the equipment maintenance cost.

[0004] CN 112877505 B discloses a fluorine-free KR desulfurizer and a desulfurization method thereof. The desulfurizer comprises the following components in weight percentage: active lime: 75%-85%, aluminum ash: 6%-9%, sodium borate calcite: 6%-12%, and calcium carbide: 3%-4%; the weight percentage content of B2O3 in sodium borate calcite is ≥45%, and the weight percentage content of Na2O is ≥5%; the weight percentage content of CaO in lime is ≥90%, and the weight percentage content of SiO2 is ≤2%. The prior art realizes the fluorine-free desulfurizer, reduces the pollution to the environment, and can also effectively promote the dissolution of limestone, improve the use efficiency of the desulfurizer, and thus improve the desulfurization effect. In addition, it also effectively reduces the agglomeration phenomenon of the desulfurizer, and improves the utilization rate and desulfurization efficiency of the desulfurizer. However, the aluminum ash, the slag formed by the sodium borate calcite, and the products generated by the calcium carbide in the prior art have a corrosive effect on the refractory material and increase the equipment maintenance cost.

[0005] CN 111254257 B discloses a method for mechanically stirring desulfurization of molten iron based on bottom-blowing powder agent. After the rotation speed is increased to the working rotation speed, the desulfurizer is sprayed into the molten iron from the bottom of the molten iron tank; the particle size of the desulfurizer is less than 0.1 mm, and the desulfurizer is sprayed into the molten iron through a permeable brick installed at the bottom of the molten iron tank; the permeable brick adopts a slit-type powder-spraying permeable brick, and the installation position is at a distance D from the center of the tank bottom, 0≤D<L / 2, wherein L is the rotating diameter length of the stirrer; the mass percentages of the desulfurizer components are: CaO: 58-60%, Al2O3: 12-14%, SiO2: 3-5%, MgO: 10-11%, CaF2: 2-3%, soda ash: 3-4%, K2O: 3-5%, Na2O: 3-4%. This prior art improves the thermodynamic conditions of the desulfurization reaction, increases the effective length of the agitator blades, and effectively reduces the serious slag sticking between the agitator blades caused by the rigid rotor, which in turn leads to reduced stirring performance and short agitator life. However, the CaF2, K2O and Na2O in this prior art have an erosive effect on refractory materials and increase equipment maintenance costs. At the same time, the air-permeable bricks are easily blocked, affecting production.

[0006] Based on this, there is room for improvement in rotary injection of desulfurization agents. Summary of the invention

[0007] In view of this, the present invention provides a rotary spray desulfurization method to solve the problems of low desulfurization efficiency and high desulfurization agent consumption of the spray method.

[0008] The present invention provides a rotary spray desulfurization method, comprising: during the molten iron pretreatment process, desulfurizing the molten iron in the ladle by sequentially spraying a first desulfurizer into the molten iron, adding a second desulfurizer to the surface of the molten iron, and spraying a third desulfurizer into the molten iron.

[0009] In some embodiments, the first desulfurizer is passivated active lime, the second desulfurizer is ultrafine calcium carbonate powder, and the third desulfurizer is passivated pure magnesium particles.

[0010] In some embodiments, the rotary jet desulfurization method comprises the following steps: Step 1, inserting a rotary spray gun into molten iron in a ladle and rotating the rotary spray gun at a first rotation speed; Step 2, spraying a first desulfurizing agent into the molten iron in a first spraying amount through a rotating spray gun, and at the same time adding a desulfurizing auxiliary agent to the surface of the molten iron in a first addition amount in the ladle; Step 3, after the first desulfurizing agent and the desulfurizing auxiliary agent are added, the rotation speed of the rotary spray gun is increased to the second rotation speed and maintained for the first time; Step 4, adding a second desulfurizing agent in a second amount to the surface of the molten iron in the ladle; Step 5: injecting the third desulfurizing agent into the molten iron with a second injection amount through a rotating spray gun.

[0011] In some embodiments, in step 1, the position where the rotary lance is inserted into the molten iron in the ladle is 300-500 mm from the bottom of the ladle, and the first rotation speed is 80-100 rpm.

[0012] In some embodiments, in step 2, the first injection amount is 3-4 kg / t molten iron, and the first addition amount is 0.2-0.4 kg / t molten iron.

[0013] In some embodiments, in step 2, the desulfurization auxiliary agent is liquid aluminum.

[0014] In some embodiments, in step 3, the second rotation speed is 100-120 rpm, and the first time is 4-5 minutes.

[0015] In some embodiments, in step 4, the second added amount is 0.6-1.2 kg / t molten iron.

[0016] In some embodiments, the particle size of the second desulfurizing agent is less than 30 μm.

[0017] In some embodiments, in step 5, the second injection amount is 0.15-0.25 kg / t molten iron.

[0018] Beneficial effects of the present invention: The rotary spray desulfurization method of the present invention is to add the desulfurizing agent passivated active lime, ultrafine calcium carbonate powder and passivated pure magnesium particles into the molten iron in a suitable manner according to their properties, and to select a suitable spraying amount or addition amount, so as to achieve effective desulfurization of the molten iron, so that the sulfur content in the desulfurized molten iron is less than 15ppm, and the synergistic effect of the desulfurizing agent shortens the desulfurization time by more than 3 minutes. The rotary spray desulfurization method of the present invention not only meets the desulfurization effect, but also helps to shorten the desulfurization time and improve production efficiency, and is suitable for promotion and application by steel enterprises, and shortening the desulfurization time has certain economic benefits. DETAILED DESCRIPTION

[0019] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the embodiments of the present invention are further described in detail below in conjunction with specific embodiments.

[0020] It should be noted that all expressions using "first" and "second" in the embodiments of the present invention are for distinguishing two non-identical entities with the same name or non-identical parameters. It can be seen that "first" and "second" are only for the convenience of expression and should not be understood as limitations on the embodiments of the present invention. The subsequent embodiments will not explain this one by one.

[0021] The rotary spray desulfurization method of the present invention comprises: during the pretreatment of molten iron, desulfurizing the molten iron in the ladle by sequentially spraying a first desulfurizer into the molten iron, adding a second desulfurizer to the surface of the molten iron, and spraying a third desulfurizer into the molten iron.

[0022] In some embodiments, the first desulfurizer is passivated active lime, the second desulfurizer is ultrafine calcium carbonate powder, and the third desulfurizer is passivated pure magnesium particles.

[0023] In some embodiments, the particle size of the passivated pure magnesium particles is 0.15 to 1.5 mm. Passivated active lime desulfurization is mainly the reaction of calcium oxide (CaO) with sulfur (S) in molten iron to form calcium sulfide (CaS) and oxygen (O). Under the condition of molten iron temperature of about 1300-1400℃, when the initial sulfur content is high, the desulfurization reaction is easy to proceed, thus achieving the purpose of desulfurization. As the reaction proceeds, the oxygen content in the system increases, which is not conducive to the desulfurization reaction. Adding aluminum liquid to deoxidize reduces the oxygen potential, which is conducive to the desulfurization reaction, thereby improving the desulfurization efficiency. Passivated active lime is a lime product after active lime has been passivated. The reaction activity has been properly controlled. During the molten iron desulfurization process, it can stably react with sulfur in the molten iron, and will not cause safety accidents such as molten iron splashing due to excessive reaction, making the desulfurization process more stable and safe, which is conducive to improving the controllability and desulfurization efficiency of the desulfurization operation.

[0024] Ultrafine calcium carbonate (CaCO3) powder will decompose in the environment of high-temperature molten iron to generate calcium oxide and carbon dioxide. The calcium oxide desulfurization is as described above. Because ultrafine calcium carbonate powder has a large specific surface area, it can decompose quickly at high temperature, and the calcium oxide produced by decomposition is more active and can react quickly with the sulfur in the molten iron, achieving efficient desulfurization in a short time. Ultrafine calcium carbonate powder can be better dispersed in the molten iron, increasing the contact area with the molten iron, which can make the desulfurization reaction more sufficient, thereby improving the desulfurization efficiency. Ultrafine calcium carbonate powder is relatively pure and will not introduce too many impurity elements during the desulfurization process, which is very beneficial for ensuring the purity and quality of molten iron. The method of adding ultrafine calcium carbonate powder to the surface of molten iron can adopt the commonly used method in the field. For example, the ultrafine calcium carbonate powder can be discharged to the surface of molten iron by cooperating with a vibrating feeder and a chute. The ultrafine calcium carbonate powder can be discharged to the surface of molten iron by a screw feeder and a conveying pipeline.

[0025] When magnesium is added to the molten iron during desulfurization, it will first evaporate and dissolve. Due to the high temperature of the molten iron, magnesium will quickly turn into gas and dissolve in the molten iron. This process creates conditions for the subsequent desulfurization reaction. The magnesium dissolved in the molten iron reacts with the sulfur in the molten iron to form magnesium sulfide (MgS). Magnesium sulfide has a high melting point and a lower density than the molten iron. It will float from the molten iron into the slag, thereby achieving the purpose of desulfurization of the molten iron. The reaction activity of magnesium and sulfur is very high. In the process of molten iron desulfurization, only a small amount of magnesium needs to be added to achieve deep desulfurization. Magnesium reacts very quickly in molten iron and can complete the desulfurization process in a short time, which can effectively shorten the desulfurization treatment time of molten iron and improve production efficiency. In addition to reducing the sulfur content, pure magnesium desulfurization will not introduce other impurity elements that have a negative impact on the quality of molten iron. Since the reaction speed and efficiency of magnesium desulfurization can be well controlled, the sulfur content of molten iron can be accurately controlled within the required range. Magnesium is an active metal and is easily oxidized in the air. A protective film will form on the surface of the magnesium particles after passivation treatment, which can prevent the magnesium particles from being over-oxidized during storage and before adding molten iron, ensuring that magnesium can play an effective role in the molten iron desulfurization process.

[0026] The rotary jet desulfurization method of the present invention comprises the following steps: Step 1, inserting a rotary spray gun into molten iron in a ladle and rotating the rotary spray gun at a first rotation speed; Step 2, spraying a first desulfurizing agent into the molten iron in a first spraying amount through a rotating spray gun, and at the same time adding a desulfurizing auxiliary agent to the surface of the molten iron in a first addition amount in the ladle; Step 3, after the first desulfurizing agent and the desulfurizing auxiliary agent are added, the rotation speed of the rotary spray gun is increased to the second rotation speed and maintained for the first time; Step 4, adding a second desulfurizing agent in a second amount to the surface of the molten iron in the ladle; Step 5: injecting the third desulfurizing agent into the molten iron with a second injection amount through a rotating spray gun.

[0027] In some embodiments, in step 1, the position where the rotary lance is inserted into the molten iron in the ladle is 300-500 mm from the bottom of the ladle, and the first rotation speed is 80-100 rpm (revolutions per minute).

[0028] In some embodiments, in step 2, the first injection amount is 3-4 kg / t molten iron.

[0029] In some embodiments, in step 2, the first added amount is 0.2-0.4 kg / t molten iron.

[0030] In some embodiments, the desulfurization auxiliary agent is liquid aluminum.

[0031] The present invention uses aluminum liquid to reduce temperature drop and shorten melting time on the one hand; on the other hand, it can quickly deoxidize and create thermodynamic conditions with low oxygen potential for desulfurization. The aluminum liquid can be added to the surface of the molten iron in a manner commonly used in the art. For example, the aluminum liquid can be placed above the ladle and the container can be slowly tilted to flow along a specific chute into the surface of the molten iron or directly into the surface of the molten iron. The aluminum liquid can be sprayed into the molten iron by a special spray gun.

[0032] In some embodiments, in step 3, the second rotation speed is 100-120 rpm, and the first time is 4-5 minutes.

[0033] In some embodiments, in step 4, the second added amount is 0.6-1.2 kg / t molten iron.

[0034] In some embodiments, the particle size of the second desulfurizing agent is less than 30 μm.

[0035] In some embodiments, in step 5, the second injection amount is 0.15-0.25 kg / t molten iron.

[0036] In some embodiments, the first desulfurizer and the third desulfurizer are respectively sprayed into the molten iron along the center direction of the molten iron in the ladle.

[0037] In some embodiments, the first desulfurizer and the third desulfurizer are respectively sprayed into the molten iron from the center of the molten iron in the ladle into the surrounding molten iron.

[0038] In some embodiments, the second desulfurization agent and the desulfurization auxiliary agent flow from the center of the molten iron in the ladle to the surface of the molten iron.

[0039] The rotary jet desulfurization method of the present invention achieves deep desulfurization of molten iron and shortens the desulfurization treatment time by matching the type of desulfurizer and the method of adding the desulfurizer to molten iron and selecting the appropriate addition amount of the desulfurizer.

[0040] When the rotary spray gun in the present invention sprays the first desulfurizer or the third desulfurizer into the molten iron, the inner layer of the rotary spray gun conveys the first desulfurizer or the third desulfurizer, and the outer layer of the rotary spray gun conveys inert gas, thereby achieving the spraying of the first desulfurizer or the third desulfurizer and the stirring of the molten iron by the gas at the same time.

[0041] Example 1 During the pretreatment of molten iron, the sulfur content in the molten iron in the ladle before desulfurization is 0.06%. The rotary spray gun is inserted into the molten iron in the ladle and rotated at a rotation speed of 80 rpm. The position where the rotary spray gun is inserted into the molten iron in the ladle is 500 mm from the bottom of the ladle. Then, the passivation active lime is sprayed into the molten iron by the rotary spray gun at a spraying amount of 3 kg / t molten iron, and aluminum liquid is added to the surface of the molten iron in the ladle at an addition amount of 0.2 kg / t molten iron. After the passivation active lime and aluminum liquid are added, the rotation speed of the rotary spray gun is increased to a rotation speed of 100 rpm and maintained for 4 minutes. Then, calcium carbonate ultrafine powder is added to the surface of the molten iron in the ladle at an addition amount of 0.6 kg / t molten iron, and the particle size of the calcium carbonate ultrafine powder is less than 30 μm. Finally, the passivated pure magnesium particles were sprayed into the molten iron at a spray rate of 0.15 kg / t of molten iron through a rotating spray gun, and the particle size of the passivated pure magnesium particles was 0.15-1.5 mm. After desulfurization of the molten iron, the sulfur content in the molten iron was reduced to 11 ppm, and the desulfurization treatment time was 14 minutes.

[0042] Example 2 During the pretreatment of molten iron, the sulfur content in the molten iron in the ladle before desulfurization is 0.07%, and the rotary spray gun is inserted into the molten iron in the ladle and rotated at a rotation speed of 90rpm. The position where the rotary spray gun is inserted into the molten iron in the ladle is 400mm from the bottom of the ladle. Then, the passivation active lime is sprayed into the molten iron by the rotary spray gun at a spraying amount of 3.5kg / t molten iron, and aluminum liquid is added to the surface of the molten iron in the ladle at an addition amount of 0.3kg / t molten iron. After the passivation active lime and aluminum liquid are added, the rotation speed of the rotary spray gun is increased to a rotation speed of 110rpm and maintained for 4.5 minutes. Then, calcium carbonate ultrafine powder is added to the surface of the molten iron in the ladle at an addition amount of 0.9kg / t molten iron, and the particle size of the calcium carbonate ultrafine powder is less than 30μm. Finally, the passivated pure magnesium particles were sprayed into the molten iron at a spray rate of 0.2 kg / t of molten iron through a rotating spray gun, and the particle size of the passivated pure magnesium particles was 0.15-1.5 mm. After desulfurization of the molten iron, the sulfur content in the molten iron was reduced to 12 ppm, and the desulfurization treatment time was 16 minutes.

[0043] Example 3 During the pretreatment of molten iron, the sulfur content in the molten iron in the ladle before desulfurization is 0.09%, the rotary spray gun is inserted into the molten iron in the ladle and the rotary spray gun rotates at a rotation speed of 100rpm, and the position of the rotary spray gun inserted into the molten iron in the ladle is 300mm from the bottom of the ladle. Then, the passivation active lime is sprayed into the molten iron by the rotary spray gun at a spraying amount of 4kg / t molten iron, and aluminum liquid is added to the surface of the molten iron in the ladle at an addition amount of 0.4kg / t molten iron. After the passivation active lime and aluminum liquid are added, the rotation speed of the rotary spray gun is increased to a rotation speed of 120rpm and maintained for 5 minutes. Then, calcium carbonate ultrafine powder is added to the surface of the molten iron in the ladle at an addition amount of 1.2kg / t molten iron, and the particle size of the calcium carbonate ultrafine powder is less than 30μm. Finally, the passivated pure magnesium particles were sprayed into the molten iron at a spray rate of 0.25 kg / t of molten iron through a rotating spray gun, and the particle size of the passivated pure magnesium particles was 0.15-1.5 mm. After desulfurization of the molten iron, the sulfur content in the molten iron was reduced to 14 ppm, and the desulfurization treatment time was 19 minutes.

[0044] Comparative Example 1 During the pretreatment of molten iron, the sulfur content in the molten iron in the ladle before desulfurization is 0.06%. The rotary spray gun is inserted into the molten iron in the ladle and the rotary spray gun rotates at a rotation speed of 100rpm. The position where the rotary spray gun is inserted into the molten iron in the ladle is 500mm from the bottom of the ladle. Then, the passivation active lime is sprayed into the molten iron with a spraying amount of 5kg / t molten iron through the rotary spray gun. Passivation pure magnesium particles are sprayed at a spraying amount of 0.45kg / t molten iron, and the particle size of the passivation pure magnesium particles is 0.15-1.5mm. After the molten iron is desulfurized, the sulfur content in the molten iron is reduced to 19ppm, and the desulfurization treatment time is 18 minutes.

[0045] Comparative Example 2 During the pretreatment of molten iron, the sulfur content in the molten iron in the ladle before desulfurization is 0.07%. The rotary spray gun is inserted into the molten iron in the ladle and rotates at a rotation speed of 110 rpm. The position where the rotary spray gun is inserted into the molten iron in the ladle is 400 mm from the bottom of the ladle. Then, the passivation active lime is sprayed into the molten iron by the rotary spray gun at a spray rate of 5.5 kg / t of molten iron. Passivation pure magnesium particles are sprayed at a spray rate of 0.6 kg / t of molten iron, and the particle size of the passivation pure magnesium particles is 0.15-1.5 mm. After the molten iron is desulfurized, the sulfur content in the molten iron is reduced to 20 ppm, and the desulfurization treatment time is 20 minutes.

[0046] Comparative Example 3 During the pretreatment of molten iron, the sulfur content in the molten iron in the ladle before desulfurization is 0.09%. The rotary spray gun is inserted into the molten iron in the ladle and rotates at a rotation speed of 120 rpm. The position where the rotary spray gun is inserted into the molten iron in the ladle is 300 mm from the bottom of the ladle. Then, the passivation active lime is sprayed into the molten iron by the rotary spray gun at a spray rate of 6 kg / t molten iron. Passivation pure magnesium particles are sprayed at a spray rate of 0.75 kg / t molten iron, and the particle size of the passivation pure magnesium particles is 0.15-1.5 mm. After the molten iron is desulfurized, the sulfur content in the molten iron is reduced to 22 ppm, and the desulfurization treatment time is 23 minutes.

[0047] The sulfur content in the molten iron in the ladle before desulfurization is different, and the amount of desulfurizer and the desulfurization time required are different to achieve a better desulfurization effect. Compared with the existing rotary jet desulfurization method, the rotary jet desulfurization method of the present invention shortens the desulfurization time, reduces the total amount of desulfurizer used, and improves the desulfurization effect accordingly, under the premise that the sulfur content in the molten iron in the ladle before desulfurization is the same.

[0048] The rotary jet desulfurization method of the present invention achieves effective desulfurization of the molten iron by adding the desulfurizer passivated active lime, ultrafine calcium carbonate powder and passivated pure magnesium particles into the molten iron in a suitable adding manner according to their properties, and selecting a suitable jetting amount or addition amount, so that the sulfur content in the molten iron after desulfurization is less than 15ppm. At the same time, the synergistic effect of the desulfurizer shortens the desulfurization time by more than 3 minutes.

[0049] The technical features of the above embodiments may be combined arbitrarily. To make the description concise, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0050] The above-mentioned embodiments only express several implementation methods of the present application, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for a person of ordinary skill in the art, several variations and improvements can be made without departing from the concept of the present application, and these all belong to the protection scope of the present application. Therefore, the protection scope of the patent of the present application shall be subject to the attached claims.

Claims

1. A rotary jet desulfurization method, characterized in that: include: During the molten iron pretreatment process, the molten iron in the ladle is desulfurized by spraying a first desulfurizer into the molten iron, adding a second desulfurizer to the surface of the molten iron, and spraying a third desulfurizer into the molten iron in sequence.

2. The rotary jet desulfurization method according to claim 1, characterized in that: The first desulfurizer is passivated active lime, the second desulfurizer is ultrafine calcium carbonate powder, and the third desulfurizer is passivated pure magnesium particles.

3. The rotary jet desulfurization method according to claim 2, characterized in that: The following steps are involved: Step 1, inserting a rotary spray gun into molten iron in a ladle and rotating the rotary spray gun at a first rotation speed; Step 2, spraying the first desulfurizing agent into the molten iron with a first spraying amount through the rotary spray gun, and adding a desulfurizing auxiliary agent to the surface of the molten iron in the ladle with a first addition amount; Step 3, after the first desulfurizing agent and the desulfurizing auxiliary agent are added, the rotation speed of the rotary spray gun is increased to a second rotation speed and maintained for a first time; Step 4, adding the second desulfurizing agent in a second amount to the surface of the molten iron in the ladle; Step 5: injecting the third desulfurizing agent into the molten iron with a second injection amount through the rotary spray gun.

4. The rotary jet desulfurization method according to claim 3, characterized in that: In the step 1, the position where the rotary lance is inserted into the molten iron in the ladle is 300 to 500 mm away from the bottom of the ladle, and the first rotation speed is 80 to 100 rpm.

5. The rotary jet desulfurization method according to claim 3, characterized in that: In the step 2, the first injection amount is 3-4 kg / t molten iron, and the first addition amount is 0.2-0.4 kg / t molten iron.

6. The rotary jet desulfurization method according to claim 3, characterized in that: In step 2, the desulfurization auxiliary agent is liquid aluminum.

7. The rotary jet desulfurization method according to claim 3, characterized in that: In the step 3, the second rotation speed is 100-120 rpm, and the first time is 4-5 minutes.

8. The rotary jet desulfurization method according to claim 3, characterized in that: In step 4, the second added amount is 0.6-1.2 kg / t molten iron.

9. The rotary jet desulfurization method according to claim 8, characterized in that: The particle size of the second desulfurizing agent is less than 30 μm.

10. The rotary jet desulfurization method according to claim 3, characterized in that: In the step 5, the second injection amount is 0.15-0.25 kg / t molten iron.