CN119120836A - A refining process of LF with rapid heating - Google Patents

Abstract

The present invention provides a LF rapid heating refining process. After the LF refining furnace arrives at the station and before the slag-forming material is added to the ladle of the LF refining furnace, the state of the ladle is first judged, and the feeding method of the slag-forming material into the ladle is controlled according to the different states of the ladle. When the ladle is in a standard working state, the slag-forming material is added to the ladle twice, and the two slag-forming 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, the slag-forming material is added to the ladle twice, and the slag-forming material added for the first time includes fluorite and carbon powder, and slagging is achieved by fluorite and carbon powder. After the argon blowing at the bottom of the ladle is unblocked, the remaining slag-forming material is added, and the slag-forming material added for the second time includes refined slag and carbon powder. For the initial stage of smelting when argon blowing at the bottom of the ladle is blocked, the characteristic of fluorite slagging quickly is utilized to quickly form slag, shorten the early smelting time, and effectively improve the heating efficiency while improving the quality of molten steel.

Description

LF (ladle furnace) rapid heating refining process

Technical Field

The invention belongs to the technical field of ferrous metallurgy, and particularly relates to a refining process for LF rapid heating.

Background

LF refining (ladle furnace, fully called ladle refining furnace) is an external refining method, and mainly realizes the refining of molten steel by means of electric arc heating, bottom argon blowing stirring, adding composite slag, top slag refining and the like. The LF refining technology is widely applied to the steel industry and is mainly used for deoxidizing, desulfurizing, degassing, removing impurities, heating and adjusting tapping temperature, alloying and adjusting chemical components of molten steel.

The production process route of molten steel is characterized in that molten iron is desulfurized and vanadium is extracted to form semisteel, the semisteel is sent into a steelmaking converter, carbon is removed to about 0.15% in the steelmaking converter, the temperature is increased to 1660-1690 ℃, then the molten steel is sent into an LF furnace after the molten steel is adjusted to the lower limit of steel grade by a small platform after the converter, the molten steel enters LF refining and is sent to RH degassing treatment, and finally the molten steel subjected to RH degassing treatment is cast by a casting machine. The primary refining task of the LF refining process is to adopt arc heating and top slag refining, and the LF refining process has strict requirements on the purity and inclusion of molten steel products.

However, in the prior art, the efficiency of treating molten steel in an LF refining process is 45 min/furnace on average, the heating time is long, the molten steel is foamed, overflowed and overflowed in the heating process, the splashing is serious, a large amount of metal materials are lost, and according to statistics, electrode breakage mostly occurs within 1-2min of arc starting heating, and the secondary voltage and current are unstable at the stage, and the voltage and current fluctuation is large. The method has the main problems that 1, steel overflow and slag overflow occur in the molten steel treatment process, steel and slag are adhered to the edge of a steel ladle, the operation safety of the molten steel is affected, and the insertion depth is affected during RH vacuum treatment. 2. A large amount of steel slag flows into a pit and a buggy ladle, so that the cleaning is difficult, 8 hours are needed for each slag removal, the non-production time is long, and the high-yield requirement of a heavy rail is influenced. 3. The furnace cover of the LF furnace has the problems of water leakage, open welding and the like due to high operation rate, long working period, operation in a high-temperature liquid environment and the like, repair welding is required, and the average service life of the furnace cover is low.

Therefore, how to overcome the above technical drawbacks is a urgent problem for those skilled in the art.

Disclosure of Invention

The invention aims to provide a refining process capable of quickly heating LF, so that the heating efficiency can be effectively improved, and the quality of molten steel can be improved.

In order to solve the technical problems, the invention provides a refining process for quickly heating LF, which comprises the steps of judging ladle states after an LF refining furnace arrives at a station and before a slag forming material is added into a ladle of the LF refining furnace, wherein the ladle states comprise a standard working state and a ladle bottom argon blowing non-passing state;

when the ladle is in a standard working state, adding a slag-forming material into the ladle twice, wherein the slag-forming material comprises refining slag, carbon powder and fluorite;

When the ladle is in a state that ladle bottom argon blowing is not conducted, adding slag forming materials into the ladle for two times, wherein the slag forming materials added for the first time comprise fluorite and carbon powder so as to realize slag melting, adding the residual slag forming materials after the ladle bottom argon blowing is conducted smoothly, and adding the slag forming materials added for the second time comprise refining slag and carbon powder.

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

Optionally, in the above-mentioned LF rapid heating refining process, when the ladle is in a standard working state, the added refining slag per furnace is 200 kg-300kg, carbon powder is 40 kg-60kg, and fluorite is 50-kg kg.

Optionally, in the ladle bottom argon blowing non-passing state in the ladle rapid temperature rising refining process, 80-kg kg to 120kg fluorite and 20-kg kg to 40kg carbon powder are added into each furnace, slag melting is carried out, and 200-kg kg to 300kg refining slag and 20-kg kg carbon powder are added after ladle bottom argon blowing is smooth.

Optionally, in the refining process with the rapid temperature rise of the LF, the slag melting time is 5-8 min.

Optionally, in the above-mentioned LF rapid heating refining process, when the ladle is in a ladle bottom argon blowing non-passing state, the slag forming material added for the second time further includes fluorite.

Optionally, in the refining process with the rapid LF temperature rise, the method for judging the ladle state comprises observing the turning-over condition of molten steel and/or detecting the flow of ladle bottom argon blowing through argon blowing detection equipment.

Optionally, in the LF rapid heating refining process, observing the rising condition of molten steel specifically comprises monitoring the rising condition of the liquid level in the ladle by installing a camera in the ladle.

Optionally, in the above-mentioned LF rapid heating refining process, after determining the ladle status and before adding the slag forming material for the first time, 100kg to 1000kg of lime is added.

Optionally, in the above-mentioned LF rapid heating refining process, when the ladle is in a standard working state, each slag-forming material added each time is added simultaneously.

The invention provides a refining process for LF rapid heating, which has the beneficial effects that:

After the LF refining furnace arrives at a station and before the slag-forming material is added into a ladle of the LF refining furnace, judging the state of the ladle, and controlling the feeding mode of the slag-forming material into the ladle according to the different ladle states. When the ladle is in a state that bottom blowing argon of the ladle is not communicated, the slag forming material is added into the ladle in two times, wherein the slag forming material comprises fluorite and carbon powder, slag melting is realized through the fluorite and the carbon powder, the residual slag forming material is added after the bottom blowing argon of the ladle is smooth, and the slag forming material added in the second time comprises the refining slag and the carbon powder. For the initial smelting stage in the state that the bottom argon blowing of the steel ladle is not enabled, the rapid slagging of fluorite is utilized, the earlier stage smelting time is shortened, the heating efficiency can be effectively improved, and meanwhile, the quality of molten steel is improved.

Detailed Description

Embodiments of the present invention are described in detail below. The following examples are illustrative only and are not to be construed as limiting the invention.

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

In order to enable those skilled in the art to better understand the technical solutions provided by the present invention, the present invention will be further described in detail with reference to specific embodiments.

The refining process comprises the steps of judging the ladle state after the LF refining furnace arrives at a station and before adding slag forming materials into a ladle of the LF refining furnace, wherein the ladle state comprises a standard working state and a ladle bottom argon blowing non-passing state.

When the ladle is in a standard working state, adding the slag-forming material into the ladle in two times, wherein the slag-forming material comprises refining slag, carbon powder and fluorite.

When the ladle is in a state that ladle bottom argon blowing is not conducted, adding slag forming materials into the ladle for two times, wherein the slag forming materials added for the first time comprise fluorite and carbon powder so as to realize slag melting, adding residual slag forming materials after the ladle bottom argon blowing is conducted smoothly, and adding slag forming materials added for the second time comprise refining slag and carbon powder.

According to the LF quick heating refining process, after the LF refining furnace arrives at a station and before the slag forming material is added into the ladle of the LF refining furnace, the ladle state is judged, and the feeding mode of the slag forming material into the ladle is controlled according to the different ladle states. When the ladle is in a state that bottom blowing argon of the ladle is not communicated, the slag forming material is added into the ladle in two times, wherein the slag forming material comprises fluorite and carbon powder, slag melting is realized through the fluorite and the carbon powder, the residual slag forming material is added after the bottom blowing argon of the ladle is smooth, and the slag forming material added in the second time comprises the refining slag and the carbon powder. For the initial smelting stage in the state that ladle bottom argon blowing is not enabled, the characteristics of quick fluorite slag melting and low melting point are utilized, so that the auxiliary smelting can be realized, the earlier smelting time is shortened, the heating efficiency can be effectively improved, and meanwhile, the quality of molten steel is improved.

In a specific embodiment, when the ladle is in a standard working state, the amount of the slag-forming material added for the first time is 60% -70% of the total amount of the slag-forming material, and the remaining slag-forming material is added for the second time. The slag forming materials are fully reacted in the steel ladle by adding most slag forming materials for the first time, and adding the rest slag forming materials for the second time, so that the adding time and the adding method of the slag forming materials are important for the steelmaking process, the impurity and harmful elements in the molten steel can be separated, the purity of the molten steel is improved, and the steel product with high quality is produced.

Furthermore, according to different ladle states, it is also important to control the feeding amount of slag forming materials into the ladle, when the ladle is in a standard working state, the total amount of refining slag added per furnace is 200 kg-300kg, the total amount of carbon powder is 40 kg-60kg, and the total amount of fluorite is 50 kg-100kg. Since the above specific examples have described that the number of additions is two, the slag-forming material added for the first time is 60% -70% of the total amount, and the remaining amount is added for the second time, the specific ratio may be adaptively selected according to actual needs, and is not further limited herein.

Similarly, when the ladle is in a state that ladle bottom argon blowing is not conducted, 80-120 kg of fluorite and 20-kg kg of carbon powder are added into each furnace, slag melting is conducted, and 200-kg-300 kg of refining slag and 20-kg-40 kg of carbon powder are added after ladle bottom argon blowing is conducted smoothly. Specifically, according to the research, the slag melting time is 5-8 min, and the slag melting time range can realize good slag melting effect without influencing the subsequent production efficiency.

When the ladle is in a state that ladle bottom argon blowing is not enabled, manually observing the viscosity/turning situation of molten steel and/or the reaction states such as gas pressure and argon blowing flow rate in the ladle, and after slag forming materials are added for the first time and slag melting is achieved, if the reaction states are detected to be not in accordance with preset standards, fluorite can be additionally added into the slag forming materials added for the second time, so that slag melting effect is enhanced in the second reaction.

In the specific embodiment, the method for judging the ladle state comprises the steps of observing the turning condition/viscosity of molten steel and detecting the flow of bottom blowing argon of the ladle through argon blowing detection equipment. The argon blowing detection equipment is mainly used for monitoring and controlling the ladle bottom argon blowing process, and ensures the flow stability of argon, thereby improving the quality of molten steel. The argon blowing detection equipment can be triggered when a tapping signal of the converter is detected, and whether the bottom argon blowing of the steel ladle has faults, such as blockage, air leakage, undercurrent blowing, more slag in the steel ladle or crusting and the like, is judged by analyzing the equivalent diameter of an argon flower area in a slag surface image of the steel ladle and combining the data of the current set parameters, input pressure, output pressure and the like.

In one mode, in order to ensure the bottom argon blowing effect, observing the stirring condition/viscosity of molten steel specifically comprises the step of monitoring the stirring condition of the liquid level in a ladle by installing a camera in the ladle. The method can intuitively observe the distribution of argon bubbles and the stirring effect of molten steel, thereby judging whether the bottom argon blowing operation is normal.

The two judging modes can be used for judging at the same time or selecting any one mode for judging, and can be adaptively selected according to actual conditions.

When the detection judges that the ladle bottom is in an argon blowing smooth state, the ladle is in a standard working state.

According to the technological requirement, after judging the ladle state and before adding slag forming material for the first time, lime 100 kg-1000kg is added. The argon blowing at the bottom of the ladle is not communicated, and lime added into the converter cannot be completely melted and has strong oxidizing property. Lime is a common slag-forming material, can improve the alkalinity of slag, is beneficial to removing sulfur, phosphorus and other impurities in molten steel, can improve the fluidity of slag, and is convenient for slag discharge. Lime is added before the steel slag is produced from the converter, so that the performance of the slag can be effectively improved, and the smelting efficiency is improved. The addition of lime is not only helpful for removing impurities in molten steel, but also can reduce corrosion of furnace lining and prolong the service life of the converter. In addition, the reasonable lime addition amount and time can reduce the energy consumption and environmental pollution in the steelmaking process, and meet the green production requirements of the modern steel industry.

When the ladle is in a standard working state, each slag making material added each time is added simultaneously, and the addition of each slag making material can improve refining efficiency, reduce corrosion to the ladle, optimize submerged arc effect and improve heat efficiency and electricity consumption.

Aiming at the problems of poor submerged arc effect, low heating efficiency of an LF furnace and the like in the LF refining process in the prior art, the LF rapid heating refining process provided by the invention utilizes the existing equipment to mine the functional potential of the LF furnace, optimizes the LF furnace smelting operation process and controls the feeding mode and the feeding amount of slag forming materials into a ladle according to different ladle states. By accurately controlling the slag melting and heating effects, ladle slag overflow and metal splashing are reduced, the safety of carbon deoxidation is ensured under the condition of adapting to mass production, the production cost of the steelmaking process is reduced, and the molten steel cleanliness and the product quality are improved.

The scheme adopts different refining modes, so that post workers can quickly adjust technological parameters according to the components and the temperature of molten steel, and the post workers start from the standard operation. Through optimizing the treatment mode, the heating efficiency is improved, the heating rate of the LF furnace is improved from 3.6 ℃ per minute to 4.2 ℃ per minute, the power consumption of the LF furnace is reduced to 30.61kwh/t from 30.93kwh/t, the cost is reduced by 128 ten thousand yuan, and the quality of molten steel is improved.

As used in the specification and in the claims, the terms "a," "an," "the," and/or "the" are not specific to a singular, but may include a plurality, unless the context clearly dictates otherwise. In general, the terms "comprises" and "comprising" merely indicate that the steps and elements are explicitly identified, and they do not constitute an exclusive list, as other steps or elements may be included in a method or apparatus. The inclusion of an element as defined by the phrase "comprising one does not exclude the presence of additional like elements in a process, method, article, or apparatus that comprises an element.

In the description of the embodiment of the present application, unless otherwise indicated, "/" means or, for example, a/B may represent a or B, and "and/or" herein is merely an association relationship describing an association object, which means that three relationships may exist, for example, a and/or B, and that three cases, i.e., a alone, a and B together, and B alone, exist. In addition, in the description of the embodiments of the present application, "plurality" means two or more than two.

In the description of the present application, unless explicitly defined otherwise, terms such as arrangement, installation, connection, etc. should be construed broadly and the specific meaning of the terms in the present application can be reasonably determined by a person skilled in the art in combination with the specific contents of the technical scheme.

In the present specification, each embodiment is described in a progressive manner, and each embodiment is mainly described in a different point from other embodiments, and identical and similar parts between the embodiments are all enough to refer to each other.

The principles and embodiments of the present invention have been described herein with reference to specific examples, the description of which is intended only to facilitate an understanding of the method of the present invention and its core ideas. It should be noted that it will be apparent to those skilled in the art that various modifications and adaptations of the invention can be made without departing from the principles of the invention and these modifications and adaptations are intended to be within the scope of the invention as defined in the following claims.

Claims (10)

1. A LF rapid temperature rise refining process, characterized in that the refining process comprises: 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 state of the ladle including 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 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 is characterized in that, 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. 4. The LF rapid heating refining process according to claim 1 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 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. 5. The LF rapid heating refining process according to claim 4 is characterized in that the slag-removing time is 5 min-8 min. 6. The LF rapid heating refining process according to claim 1 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 temperature rise refining process according to claim 1 is characterized in that the method of judging the state of the ladle comprises: observing the tumbling of the molten steel, and/or detecting the flow rate of argon blowing at the bottom of the ladle by an argon blowing detection device. 8. The LF rapid temperature rise refining process according to claim 7 is characterized in that observing the churning of the molten steel specifically comprises: installing a camera in the ladle to monitor the churning of the liquid level in the ladle. 9. The LF rapid heating refining process according to claim 1 is characterized in that, after judging the state of the ladle and before the slag-making material is added for the first time, 100 kg to 1000 kg of lime is added. 10. The LF rapid temperature rise refining process according to claim 1, characterized in that when the ladle is in a standard working state, each slag-forming material added each time is added simultaneously.