LF (ladle furnace) rapid heating refining process

Abstract

According to the refining process capable of rapidly heating the LF, after the LF refining furnace arrives at a station and before the slagging material is added into the steel ladle of the LF refining furnace, the state of the steel ladle is judged firstly, and the feeding mode that the slagging material enters the steel ladle is controlled according to different states of the steel ladle. When the steel ladle is in the standard working state, slagging materials are added into the steel ladle in two times, and the two slagging materials comprise refining slag, carbon powder and fluorite; when the steel ladle is in the state that argon blowing at the bottom of the steel ladle is not conducted, slagging materials are added into the steel ladle in two times, the slagging materials added for the first time comprise fluorite and carbon powder, slagging is achieved through the fluorite and the carbon powder, after argon blowing at the bottom of the steel ladle is smooth, the remaining slagging materials are added, and the slagging materials added for the second time comprise refining slag and carbon powder. For the initial smelting stage in the state that argon blowing at the bottom of the steel ladle is blocked, the characteristic that fluorite is quick in slagging is utilized, slag is quickly formed, the early-stage smelting time is shortened, the heating efficiency can be effectively improved, and meanwhile the molten steel quality is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of iron and steel metallurgy, and in particular relates to a LF rapid heating refining process. Background Art

[0002] LF refining (ladle furnace) is a refining method outside the furnace, which mainly refines the molten steel through arc heating, bottom argon stirring, adding composite slag, top slag refining, etc. LF refining technology is widely used in the steel industry, mainly for deoxidation, desulfurization, degassing, removal of inclusions, heating and adjusting the tapping temperature, and alloying and adjusting the chemical composition of molten steel.

[0003] The specific production process of molten steel is that the molten iron is desulfurized and vanadium is extracted to form semi-steel, which is then sent to the steelmaking converter. In the steelmaking converter, the carbon is removed to about 0.15%, and the temperature is raised to 1660℃-1690℃. Then, the composition of the molten steel is adjusted to the lower limit of the steel grade on the small platform behind the furnace and then sent to the LF furnace. After the molten steel enters the LF refining, it is sent to the RH degassing treatment, and finally the molten steel after RH degassing is cast on the casting machine. The main refining tasks of the LF refining process are arc heating and top slag refining. The LF refining process has relatively strict requirements on the purity and inclusions of its molten steel products.

[0004] However, in the prior art, the efficiency of LF refining process in treating molten steel is an average of 45min / furnace, the heating time is long, and there are foaming, overflowing and slag overflowing in the heating process, and the splashing is serious, resulting in a large amount of metal material loss. According to statistics, most of the electrode breakage occurs within 1-2min of arc heating. During this stage, the secondary voltage and current are unstable, and the voltage and current fluctuate greatly. The main problems are: 1. The molten steel treatment process overflows steel and slag, and the edge of the ladle sticks a lot of steel and slag, which affects the safe operation of the molten steel and affects the insertion depth during RH vacuum treatment. 2. A large amount of steel slag flows into the pit and ladle car, which is difficult to clean. Each slag cleaning takes 8 hours, and the non-production time is long, which affects the need for high production of heavy rails. 3. Due to the high operating rate, long working cycle, and operation in a high-temperature liquid environment, the furnace cover of the LF furnace often leaks and opens due to other reasons, which require repair welding, and the average life of the furnace cover is low.

[0005] Therefore, how to overcome the above technical defects is a problem that needs to be solved urgently by those skilled in the art. Summary of the invention

[0006] The object of the present invention is to provide a LF rapid heating refining process, which can effectively improve the heating efficiency and improve the quality of molten steel.

[0007] In order to solve the above technical problems, the present invention provides a LF rapid heating refining process, the refining process comprising: after the LF refining furnace arrives at the station and before the slag-making material is added to the ladle of the LF refining furnace, firstly judging the state of the ladle, the state of the ladle including the standard working state and the state where argon blowing at the bottom of the ladle is blocked;

[0008] When the ladle is in a standard working state, adding slag-making materials into the ladle twice, and the two slag-making materials both include refined slag, carbon powder and fluorite;

[0009] When the ladle is in a state where argon blowing at the bottom of the ladle is blocked, slag-forming materials are added into the ladle twice. The slag-forming materials added for the first time include fluorite and carbon powder to achieve slagging. After the argon blowing at the bottom of the ladle is unblocked, the remaining slag-forming materials are added. The slag-forming materials added for the second time include refined slag and carbon powder.

[0010] Optionally, in the above-mentioned LF rapid heating refining process, when the ladle is in a standard working state, the amount of slag-forming material added for the first time is 60%-70% of the total amount of slag-forming material, and the remaining slag-forming material is added for the second time.

[0011] Optionally, in the above-mentioned LF rapid heating refining process, when the ladle is in a standard working state, 200 kg-300 kg of refined slag, 40 kg-60 kg of carbon powder, and 50 kg-100 kg of fluorite are added to each furnace.

[0012] Optionally, in the above-mentioned LF rapid heating refining process, when the ladle is in a state where argon blowing at the bottom of the ladle is blocked, 80 kg-120 kg of fluorite and 20 kg-40 kg of carbon powder are first added to each furnace, and then slag is deslagging. After the argon blowing at the bottom of the ladle is unblocked, 200 kg-300 kg of refined slag and 20 kg-40 kg of carbon powder are added.

[0013] Optionally, in the above-mentioned LF rapid heating refining process, the slag-melting time is 5 min-8 min.

[0014] Optionally, in the above-mentioned LF rapid temperature rise refining process, when the ladle is in a state where argon blowing at the ladle bottom is blocked, the slag-forming material added for the second time further includes fluorite.

[0015] Optionally, in the above-mentioned LF rapid temperature rise refining process, the method of judging the state of the ladle includes: observing the churning of the molten steel, and / or detecting the flow rate of argon blowing at the bottom of the ladle by using argon blowing detection equipment.

[0016] Optionally, in the above-mentioned LF rapid temperature rise refining process, the method of observing the churning of the molten steel specifically includes: installing a camera in the ladle to monitor the churning of the liquid surface in the ladle.

[0017] Optionally, in the above LF rapid temperature rise refining process, after judging the state of the ladle and before adding the slag-forming material for the first time, 100kg-1000kg of lime is added first.

[0018] Optionally, in the above LF rapid temperature rise refining process, when the ladle is in a standard working state, each slag-forming material added is added simultaneously.

[0019] The present invention provides a LF rapid temperature-raising refining process, which has the following beneficial effects:

[0020] After the LF refining furnace arrives at the station, and before the slag-making materials are added to the ladle of the LF refining furnace, the state of the ladle is first determined, and the feeding method of the slag-making materials into the ladle is controlled according to the different states of the ladle. When the ladle is in the standard working state, the slag-making materials are added to the ladle twice, and the two slag-making materials include refined slag, carbon powder and fluorite; when the ladle is in the state where argon blowing at the bottom of the ladle is blocked, the slag-making materials are added to the ladle twice, and the slag-making materials added for the first time include fluorite and carbon powder, and slagging is achieved through fluorite and carbon powder. After the argon blowing at the bottom of the ladle is unblocked, the remaining slag-making materials are added, and the slag-making materials added for the second time include refined slag and carbon powder. For the initial stage of smelting when argon blowing at the bottom of the ladle is blocked, the characteristics of fluorite slagging quickly are used to quickly form slag, shorten the early smelting time, effectively improve the heating efficiency, and at the same time improve the quality of molten steel. DETAILED DESCRIPTION

[0021] The embodiments of the present invention are described in detail below. The embodiments described below are exemplary and are only used to explain the present invention, and should not be understood as limiting the present invention.

[0022] The core of the present invention is to provide a LF rapid heating refining process, which can effectively improve the heating efficiency and improve the quality of molten steel.

[0023] In order to enable those skilled in the art to better understand the technical solution provided by the present invention, the present invention will be further described in detail below in conjunction with specific embodiments.

[0024] Specifically, the present invention provides a LF rapid heating refining process, the refining process comprising: after the LF refining furnace arrives at the station and before the slag-making material is added to the ladle of the LF refining furnace, first judging the state of the ladle, the ladle state including the standard working state and the state where argon blowing at the bottom of the ladle is not passed.

[0025] When the ladle is in a standard working state, slag-making materials are added into the ladle twice, and both slag-making materials include refined slag, carbon powder and fluorite.

[0026] When the ladle is in a state where argon blowing at the bottom of the ladle is blocked, slag-forming materials are added into the ladle twice. The first slag-forming materials include fluorite and carbon powder to achieve slagging. After the argon blowing at the bottom of the ladle is unblocked, the remaining slag-forming materials are added. The second slag-forming materials include refined slag and carbon powder.

[0027] The LF rapid heating refining process provided by this scheme first determines the state of the ladle after the LF refining furnace arrives at the station and before the slag-making materials are added to the ladle of the LF refining furnace, and controls the feeding method of the slag-making materials into the ladle according to the different states of the ladle. When the ladle is in the standard working state, the slag-making materials are added to the ladle twice, and the two slag-making materials include refined slag, carbon powder and fluorite; when the ladle is in the state where argon blowing at the bottom of the ladle is blocked, the slag-making materials are added to the ladle twice, and the slag-making materials added for the first time include fluorite and carbon powder, and slag is achieved through fluorite and carbon powder. After the argon blowing at the bottom of the ladle is unblocked, the remaining slag-making materials are added, and the slag-making materials added for the second time include refined slag and carbon powder. For the initial stage of smelting when argon blowing at the bottom of the ladle is blocked, the characteristics of fluorite that slags quickly and can reduce the melting point can be used to achieve melting assistance, shorten the early smelting time, effectively improve the heating efficiency, and improve the quality of molten steel.

[0028] In a specific embodiment, when the ladle is in a standard working state, the amount of slag-forming material added for the first time is 60%-70% of the total amount of slag-forming material, and the remaining slag-forming material is added for the second time. Most of the slag-forming material is added for the first time to make it fully react in the ladle, and the remaining small amount of slag-forming material is added for the second time. The timing and method of adding the slag-forming material are crucial to the steelmaking process, which can help separate impurities and harmful elements in molten steel, improve the purity of molten steel, and thus produce high-quality steel products.

[0029] Furthermore, according to different ladle states, it is also important to control the amount of slag-forming materials added to the ladle. When the ladle is in a standard working state, the total amount of refined slag added to each furnace is 200 kg-300 kg, the total amount of carbon powder is 40 kg-60 kg, and the total amount of fluorite is 50 kg-100 kg. Since the above specific embodiment has recorded that the number of additions is twice, the first addition of slag-forming materials is 60%-70% of the total amount, and the second addition is the remaining amount. The specific ratio can be adaptively selected according to actual needs and is not further limited here.

[0030] Similarly, when the ladle is in a state where argon blowing at the bottom of the ladle is blocked, 80 kg-120 kg of fluorite and 20 kg-40 kg of carbon powder are added to each furnace first, and then slag is removed. After the argon blowing at the bottom of the ladle is unblocked, 200 kg-300 kg of refined slag and 20 kg-40 kg of carbon powder are added. Specifically, according to research, the slag removal time is 5 min-8 min, and this slag removal time range can achieve a good slag removal effect without affecting subsequent production efficiency.

[0031] When the ladle is in a state where argon blowing at the bottom of the ladle is blocked, the viscosity / tumbling of the molten steel, and / or the reaction states such as the gas pressure in the ladle and the argon blowing flow rate can be manually observed. After the slag-forming material is added for the first time and slag-forming is achieved, if it is detected that the above reaction states do not meet the preset standards, fluorite can be additionally added to the slag-forming material added for the second time to enhance the slag-forming effect during the second reaction.

[0032] In a specific embodiment, the method of judging the state of the ladle includes: one method is to observe the tumbling / viscosity of the molten steel, and the other method is to detect the flow rate of argon blowing at the bottom of the ladle through an argon blowing detection device. The argon blowing detection device is mainly used to monitor and control the process of argon blowing at the bottom of the ladle to ensure the stability of the flow rate of argon gas, thereby improving the quality of the molten steel. Usually, the argon blowing detection device can be triggered when the steel tapping signal of the converter is detected. By analyzing the equivalent diameter of the argon flower area in the slag surface image of the ladle, combined with the current set parameters, input pressure, output pressure and other data, it is judged whether the argon blowing at the bottom of the ladle is faulty, such as blockage, leakage, under-blowing, too much slag under the ladle, or crusting.

[0033] In one method, in order to ensure the effect of bottom argon blowing, the tumbling / viscosity of the molten steel is observed. Specifically, a camera can be installed in the ladle to monitor the tumbling of the liquid surface in the ladle. This method can visually observe the distribution of argon bubbles and the stirring effect of the molten steel, thereby judging whether the bottom argon blowing operation is normal.

[0034] The above two judgment methods can be used simultaneously or any one of them can be selected for judgment, and an adaptive selection can be made according to the actual situation.

[0035] When it is detected that the bottom of the ladle is in a state of unobstructed argon blowing, the ladle referred to in this article is in a standard working state.

[0036] According to the process requirements, after judging the state of the ladle and before the first addition of slag-making materials, add 100 kg-1000 kg of lime. If the ladle bottom argon blowing is blocked, the lime added to the converter cannot be completely melted and has strong oxidizing properties. Lime is a commonly used slag-making material. It can increase the basicity of the slag, help remove impurities such as sulfur and phosphorus in the molten steel, and also improve the fluidity of the slag, making it easier to discharge the slag. Adding lime before the converter slag is tapped can effectively improve the performance of the slag and improve the smelting efficiency. The addition of lime not only helps to remove impurities in the molten steel, but also reduces the erosion of the furnace lining and extends the service life of the converter. In addition, the reasonable amount and timing of lime addition can also reduce energy consumption and environmental pollution in the steelmaking process, which meets the green production requirements of the modern steel industry.

[0037] When the ladle is in a standard working state, each slag-forming material is added at the same time. Adding each slag-forming material at the same time can improve the refining efficiency, reduce the erosion of the ladle, optimize the submerged arc effect, and improve the thermal efficiency and power consumption.

[0038] In view of the problems existing in the prior art such as poor arc submergence effect and low heating efficiency of LF furnace in the LF refining process, the present invention provides a LF rapid heating refining process, which utilizes existing equipment, taps its functional potential, optimizes the LF furnace smelting operation process, and controls the feeding method and feeding amount of slag-making materials into the ladle according to the different states of the ladle. By accurately controlling the slagging and heating effects, the ladle slag overflow and metal splashing are reduced, and the safety of carbon deoxidation is ensured under the conditions of adapting to large-scale production, the production cost of the steelmaking process is reduced, and the cleanliness of molten steel and product quality are improved.

[0039] This plan adopts different refining modes, allowing employees to quickly adjust process parameters according to the composition and temperature of molten steel, starting from standardizing job operations. By optimizing the processing mode and improving heating efficiency, the heating rate of the LF furnace increased from an average of 3.6℃ / min to 4.2℃ / min, and the power consumption of the LF furnace was shortened from 30.93kwh / t to 30.61kwh / t, reducing costs by 1.28 million yuan and improving the quality of molten steel.

[0040] As shown in this application and claims, unless the context clearly indicates an exception, the words "a", "an", "a kind" and / or "the" do not refer to the singular, but also include the plural. Generally speaking, the terms "include" and "comprise" only indicate the inclusion of clearly identified steps and elements, and these steps and elements do not constitute an exclusive list. The method or device may also include other steps or elements. The elements defined by the sentence "includes a..." do not exclude the existence of other identical elements in the process, method, commodity or device that includes the elements.

[0041] In the description of the embodiments of the present application, unless otherwise specified, " / " means or, for example, A / B can mean A or B; "and / or" in this article is only a description of the association relationship of associated objects, indicating that there can be three relationships, for example, A and / or B can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present application, "multiple" means two or more than two.

[0042] In the description of this application, unless otherwise clearly defined, terms such as setting, installing, connecting, etc. should be understood in a broad sense, and technicians in the relevant technical field can reasonably determine the specific meanings of the above terms in this application based on the specific content of the technical solution.

[0043] The various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0044] The principles and implementation methods of the present invention are described in this article using specific examples. The description of the above embodiments is only used to help understand the method and core ideas of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made to the present invention without departing from the principles of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

Claims

1. A refining process for LF with rapid heating, It is characterized in that The refining process comprises: after the LF refining furnace arrives at the station and before the slag-making material is added into the ladle of the LF refining furnace, firstly judging the state of the ladle, wherein the state of the ladle includes the standard working state and the state where argon blowing at the bottom of the ladle is blocked; When the ladle is in a standard working state, adding slag-making materials into the ladle twice, and the two slag-making materials both include refined slag, carbon powder and fluorite; When the ladle is in a state where argon blowing at the bottom of the ladle is blocked, slag-forming materials are added into the ladle twice. The slag-forming materials added for the first time include fluorite and carbon powder to achieve slagging. After the argon blowing at the bottom of the ladle is unblocked, the remaining slag-forming materials are added. The slag-forming materials added for the second time include refined slag and carbon powder.

2. The LF rapid heating refining process according to claim 1, It is characterized in that When the ladle is in a standard working state, the amount of slag-forming material added for the first time is 60%-70% of the total amount of slag-forming material, and the remaining slag-forming material is added for the second time.

3. The LF rapid heating refining process according to claim 1 or 2, It is characterized in that When the ladle is in standard working condition, 200 kg-300 kg of refined slag, 40 kg-60 kg of carbon powder and 50 kg-100 kg of fluorite are added to each furnace.

4. The LF rapid heating refining process according to claim 1, It is characterized in that When the ladle is in a state where argon blowing at the bottom of the ladle is blocked, 80 kg-120 kg of fluorite and 20 kg-40 kg of carbon powder are first added to each furnace, and then slag is deslagging. After the argon blowing at the bottom of the ladle is unblocked, 200 kg-300 kg of refined slag and 20 kg-40 kg of carbon powder are added.

5. The LF rapid heating refining process according to claim 4, It is characterized in that The slag-forming time is 5min-8min.

6. The LF rapid heating refining process according to claim 1, It is characterized in that When the ladle is in a state where argon blowing at the bottom of the ladle is blocked, the slag-making material added for the second time also includes fluorite.

7. The LF rapid heating refining process according to claim 1, It is characterized in that The method of judging the state of the ladle includes: observing the tumbling of the molten steel, and / or detecting the flow rate of argon blowing at the bottom of the ladle by using an argon blowing detection device.

8. The LF rapid heating refining process according to claim 7, It is characterized in that The specific method of observing the churning of molten steel includes: installing a camera in the ladle to monitor the churning of the liquid surface in the ladle.

9. The LF rapid heating refining process according to claim 1, It is characterized in that After judging the state of the ladle and before adding the slag-making material for the first time, add 100 kg to 1000 kg of lime.

10. The LF rapid heating refining process according to claim 1, It is characterized in that When the ladle is in a standard working state, each slag-forming material added is added simultaneously.