WO2020101359A1 - Molten material treatment method and molten material treatment apparatus - Google Patents

Abstract

The present invention relates to a molten material treatment method and a molten material treatment apparatus used therefor, the molten material treatment method comprising the steps of: charging a receptacle, which has an open top part, with a molten material and treating the molten material; discharging the treated molten material from the receptacle; measuring the internal temperature of the receptacle; and controlling the internal temperature of the receptacle to be higher than a reference temperature. Presented are a molten material treatment method and a molten material treatment apparatus which can inhibit or prevent damage to refractories of a receptacle charged with a molten material.

Description

Melt processing method and melt processing apparatus

The present invention relates to a melt processing method and a melt processing apparatus, and more particularly, to a melt processing method and a melt processing apparatus capable of suppressing or preventing refractory damage of a container in which the melt is charged.

The production process of stainless steel (STS) includes an electric furnace process, a refining furnace process and a continuous casting process. At this time, due to the time difference between the electric furnace process and the continuous casting process, a waiting time occurs when the furnace body of the refining furnace is operated in the refining furnace process.

In the atmosphere of the furnace body, refractories built up inside the furnace body may be damaged. For example, slag penetrates into the pores of the refractory during the refining process. And after completion of the refining process, the slag remains in the pores of the refractory until the next refining process starts. The temperature of the refractory is gradually cooled from about several thousand to several hundred degrees Celsius, and the slag inside the pores is gradually cooled. When the temperature of the slag is about 725 ° C or lower, the phase changes to γ-C ₂ S and the volume expands by about 10%. Due to the volume expansion of the slag, cracks are formed inside the refractory material and the refractory material is damaged. That is, in the atmosphere of the furnace body, the slag remaining in the pores of the refractory material expands in volume to generate spalling of the refractory material.

On the other hand, Patent Document 1 below proposes a method for modifying stainless slag. According to patent document 1, when a boric acid compound is mixed with stainless steel slag, the volume change during cooling of the stainless steel slag can be prevented.

However, the method of Patent Document 1 is difficult to apply to the refining process of stainless steel. The reason for this is as follows. First, the economic efficiency is reduced due to the boric acid compound introduced into the slag for slag modification. Second, when the boric acid compound is added to the slag, damage to the refractory material is accelerated as the melting point of the slag is lowered.

In addition to the above-described method, as a method for improving the refractory life, there is a method of lowering the basicity of the slag. For example, if the basicity of the slag is lower than 1.3, the phase transition of the slag to γ-C ₂ S at 725 ° C. or less is suppressed, and volume expansion can be suppressed.

However, in general, the refractory material built in the furnace body used in the refining process of stainless steel is dolomite refractory material (CaO-MgO). At this time, the dolomite refractory material can react with the slag to increase the basicity of the slag. That is, even if the basicity of the slag is lowered during the refining process, the basicity of the slag rises to the basicity that can cause phase transition by reacting the slag that has penetrated the refractory in the atmosphere of the furnace body and the refractory. Accordingly, the slag is phase-shifted to γ-C ₂ S and the volume expands. That is, it is not possible to prevent refractory damage of the furnace body in the air by lowering the basicity of slag during the refining process.

The technology which is the background of the present invention is published in the following patent documents.

(Advanced technical literature)

(Patent Document 1) JP1999-061219 A

(Patent Document 2) KR10-2011-0019875 A

The present invention provides a melt processing method and a melt processing apparatus capable of suppressing or preventing refractory damage of a container in which a melt is charged.

Melt processing method according to an embodiment of the present invention, charging the melt in a container with an open top, and processing the melt; Discharging the processed melt from the container; Measuring the internal temperature of the container; Including; a process of controlling the internal temperature of the container to be higher than a predetermined reference temperature; and the process of measuring the internal temperature of the container includes a process of measuring the temperature of the refractory material built in the container.

In the process of processing the melt, slag is formed on the top of the melt, and measuring the temperature of the refractory may include measuring the surface temperature of the refractory at the height at which the slag is formed.

The process of measuring the surface temperature of the refractory may include detecting state information on the surface of the refractory in a non-contact manner and obtaining the surface temperature from the state information.

The reference temperature may be higher than the phase transition temperature of the slag.

The reference temperature may be determined according to the depth of penetration of the slag to the refractory.

The greater the porosity of the refractory, the deeper the penetration depth, and the deeper the penetration depth, the higher the reference temperature.

The process of detecting the state information on the surface of the refractory material includes a process of photographing a thermal image of the surface of the refractory, and a thermal imaging camera within 20 m from the surface of the refractory material during the process of photographing the thermal image of the refractory surface. Can be separated by a distance.

The process of controlling the internal temperature of the container to be higher than the reference temperature includes: comparing the measured temperature with the reference temperature; If the measured temperature is below the reference temperature, the process of heating the inside of the container to a temperature higher than the reference temperature; may include.

The process of heating the inside of the container includes tilting the container, spraying a flame inside the container, and after the process of heating the inside of the container, loading a subsequent melt into the container, and And processing the subsequent melt.

The melt may include molten steel for manufacturing stainless steel, and the refractory material may include a refractory material having a carbon content of less than 5% by weight of the total weight of the refractory material and a porosity of 20% or less.

Melt processing apparatus according to an embodiment of the present invention, the upper portion is opened, a container in which a refractory material is built; A lance disposed above the container; A heat source provided on the outside of the container; A temperature measuring unit disposed on the top of the container, supported by the heat source, spaced apart from the refractory, and capable of measuring the temperature of the refractory; It includes; a control unit for controlling the operation of the heat source so that the temperature of the refractory is higher than a predetermined reference temperature.

The container has an inlet region, an intermediate region and a lower region, and when the melt is processed, slag is located in the intermediate region, and the temperature measuring unit is configured to measure the surface temperature of the refractory material in the intermediate region. It may be inclined at the top of the container to face the region, or supported by the heat source and inclined relative to the extended direction of the heat source.

The temperature measuring unit includes a non-contact temperature measuring device, and the control unit may obtain the surface temperature from state information on the surface of the refractory detected by the non-contact temperature measuring device.

The non-contact temperature measuring device may include a thermal imaging camera, and the thermal imaging camera may be spaced within a distance of 20 m from the surface of the refractory material in the intermediate region.

The thermal imaging camera may have a hood in front of the lens to narrow the angle of view.

The control unit may operate the heat source to spray a flame inside the container when the temperature of the refractory is below a reference temperature.

According to the embodiment of the present invention, it is possible to suppress or prevent refractory damage of a container in which a melt is charged. For example, in the refining furnace process of stainless steel, the furnace body of the refining furnace is operated, and when the measured temperature is below a reference temperature by measuring the temperature of the refractory material built in the furnace body during the waiting time, the refractory material is heated to a temperature higher than the reference temperature. That is, the temperature of the refractory can be maintained at a temperature higher than the reference temperature during the waiting time. Accordingly, phase transition and volume expansion of the slag remaining in the pores of the refractory can be suppressed. Accordingly, occurrence of spalling of the refractory can be suppressed or prevented.

1 is a schematic diagram of a melt processing apparatus according to an embodiment of the present invention.

2 is a schematic view of a melt processing apparatus according to a modification of the present invention.

3 is a flow chart of a melt processing method according to an embodiment of the present invention.

4 is a phase equilibrium diagram of a slag according to an embodiment of the present invention.

5 is a thermal image photographing a furnace refractory furnace in a refining process in a refining process according to an embodiment of the present invention.

6 is a graph for explaining the change in the life of the refractory according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. However, the present invention is not limited to the embodiments disclosed below, and will be implemented in various different forms. Only the embodiments of the present invention are provided to make the disclosure of the present invention complete, and to fully inform the scope of the invention to those skilled in the art. The drawings may be exaggerated to describe embodiments of the present invention, and the same reference numerals in the drawings refer to the same elements.

Hereinafter, an embodiment of the present invention will be described in detail based on a refining furnace process for refining molten steel produced in an electric furnace process. However, the melt processing method and the melt processing apparatus according to the embodiment of the present invention can be variously applied to various processing processes for processing various melts contained in a refractory container in various ways.

1 is a schematic diagram of a melt processing apparatus according to an embodiment of the present invention. 2 is a schematic view of a melt processing apparatus according to a modification of the present invention. In this case, FIG. 1 omits the burner of the melt processing apparatus, and FIG. 2 shows only the container, burner, and temperature measurement unit of the melt processing apparatus.

First, a melt processing apparatus according to an embodiment of the present invention will be described.

Referring to Figures 1 and 2, the melt processing apparatus, the top is open, a container in which the refractory 12 is built, a lance 30 disposed on the top of the container, a heat source provided on the outside of the container, the container Is disposed on the top, supported by a heat source, spaced apart from the refractory 12, a temperature measuring unit capable of measuring the temperature of the refractory 12, the temperature of the refractory 12 is higher than a predetermined reference temperature of the heat source And a control unit (not shown) that controls operation.

The container may include a furnace body 10 of a refining furnace capable of accommodating and melting molten steel as a reactor capable of receiving a melt and processing in various ways. Here, the molten steel is, for example, a molten steel for manufacturing stainless steel manufactured in an electric furnace process, and the furnace body 10 may be a furnace body 10 of an Argon Oxygen Decarburization (AOD) refining furnace.

The furnace body 10 may have an internal space. The molten steel can be accommodated in the interior space. The furnace body 10 may be formed with a furnace opening open at the top. The lance 30 may be disposed on the top of the furnace body 10 to penetrate the furnace sphere in the vertical direction. A nozzle (not shown) may be installed to penetrate the lower portion of the furnace body 10 in a horizontal direction. Oxygen gas may be blown into the furnace body 10 through the lance 30. Argon gas can be blown into the furnace body 10 through the nozzle. The molten steel can be blown with argon gas and oxygen gas. During the blowing of molten steel, the content of carbon, oxygen and sulfur components in molten steel can be adjusted. At this time, a deoxidizing agent, a desulfurizing agent, and a flux may be introduced into the furnace body 10.

The furnace body 10 may include an iron shell 11 and a refractory material 12. The shell 11 may have a bottom plate extending in a horizontal direction and a side wall extending upward from the periphery of the bottom plate. The bottom plate may have a disc shape. The side wall may have a cylindrical shape with a convex center. The side wall has a horizontal axis (not shown) connected to the center, and the skin 11 can be tilted about the horizontal axis. The refractory material 12 may be constructed on the inner surface of the iron shell 11. Here, the refractory material 12 may include a refractory material having a carbon content of less than 10% by weight of the total weight of the refractory material and a porosity of 20% or less. More preferably, the refractory material 12 may include a refractory material having a carbon content of less than 5% by weight of the total weight of the refractory material and a porosity of 20% or less. The higher the carbon content of the refractory 12, the more difficult it is for the slag to penetrate the pores of the refractory 12. When the carbon content of the refractory material 12 is less than 10% by weight of the total weight of the refractory material, slag may penetrate into the pores of the refractory material 12. When the porosity of the refractory 12 exceeds 20%, refractory erosion may increase. The refractory material 12 may have various components and porosity depending on the type of melt. The type of refractory material may be various, such as dolomite refractories (CaO-MgO refractories), magron refractories (MgO-Cr ₂ O ₃ refractories), and carbon-containing refractories.

The entire region D of the furnace body 10 may include a plurality of partial regions arranged in the vertical direction. The furnace body 10 may include an entrance region D3, an intermediate region D2, and a lower region D1 in a direction from top to bottom. Among them, the inlet area D3 may gradually increase its inner diameter downward. In addition, the inner diameter of the lower region D1 may gradually decrease downward. The middle region D2 may connect the lower region D1 and the inlet region D3. In the middle region D2, the inner diameter may be constant in the vertical direction, or the inner diameter may gradually increase and decrease again as it goes downward.

The molten steel may be charged into the inner space of the furnace body 10 through the inlet region D3, and may be accommodated in the lower region D1 and the middle region D2 of the furnace body 10. When processing molten steel, slag may be formed on the molten metal surface. At this time, the slag may be located in the intermediate region D2. Therefore, the slag can easily penetrate the pores of the refractory material 12 in the intermediate region D2. The refractory 12 in the middle region D2 of the furnace body 10 may be referred to as a slag penetration region. The slag may include stainless steel slag having a basicity of 1.3 or higher. Stainless steel slag refers to slag produced during the refining process of stainless steel. The basicity of slag can vary continuously during the processing of molten steel.

Referring to FIG. 2, a heat source (also referred to as a “heat supply source”) may be provided outside the furnace body 10. The heat source may include a burner 70, for example. In addition to the burner, the heat source may include various heat supply devices such as heat pipes and heating wires. Burner 70 may extend in a horizontal direction. The burner 70 may be supplied with at least one of liquefied petroleum gas and liquefied natural gas and at least one of oxygen and air to generate a flame F and spray the inside of the furnace body 10. At this time, the furnace body 10 may be tilted so that the furnace tool faces the burner 70.

The temperature measuring unit may include a non-contact temperature measuring device. The non-contact temperature meter may include a thermal imaging camera 60 and an infrared thermometer. Of course, the non-contact temperature measuring device may include various non-contact thermometers, in addition to the thermal imaging camera 60 and the infrared thermometer. Since the temperature measuring unit is a non-contact temperature measuring device, thermal disturbance can be prevented during temperature measurement. Here, the thermal disturbance means, for example, a thermal disturbance according to heat loss that may occur on the surface of the refractory material upon contact between the refractory material and the contact temperature measuring device.

The thermal imaging camera 60 and the infrared thermometer may be spaced apart from the refractory 12. The thermal imaging camera 60 and the infrared thermometer can measure the temperature of the refractory 12, specifically the surface temperature of the refractory 12.

More specifically, the thermal imaging camera 60 may measure the surface temperature of the refractory 12 in the form of a thermal image by photographing a thermal image of the surface of the refractory 12. At this time, the thermal imaging camera 60 may take a thermal image of the surface of the refractory 12 in the middle region D2 of the furnace body 10. That is, a thermal image of the slag penetration region, which is a partial region where the slag penetrates, can be captured in the entire region of the surface of the refractory 12.

The infrared thermometer measures the infrared radiation energy of the surface of the refractory 12 to obtain the surface temperature of the refractory 12 in the form of energy intensity and wavelength distribution. At this time, the infrared thermometer can obtain the energy intensity and wavelength distribution of infrared radiation energy for a predetermined location of the slag penetration region.

On the other hand, the furnace body 10 may be a shape that rotates symmetrically around the vertical axis (not shown) passing through the center of the furnace body 10. Accordingly, the temperature of the refractory material 12 in the slag penetration region in the circumferential direction of the furnace body 10 may be the same or similar. That is, when the thermal imaging camera 60 photographs the thermal image of the slag penetration region, the thermal image of the thermal image photographed at the same position in the circumferential direction of the furnace body 10 is thermal image at a different height from the same height The temperature distribution of the thermal image photographed with may be the same or similar to each other.

That is, when the thermal imaging camera 60 photographs the thermal image of the slag penetration region, the control unit, even if the thermal image at any position in the circumferential direction of the furnace body 10, the refractory of the slag penetration region from the captured thermal image ( The surface temperature of 12) can be accurately known.

1 and 2, the thermal imaging camera 60 may be disposed on the top of the furnace body 10 or supported by the burner 70. Specifically, referring to FIG. 1, the thermal imaging camera 60 according to an embodiment of the present invention can measure the surface temperature of the refractory 12 of the intermediate region D2 of the furnace body 10 so as to measure the surface temperature of the furnace body 10. ) May be disposed obliquely on the top of the furnace body 10 to face the intermediate region D2. In addition, the thermal imaging camera 60 may face the intermediate region D2 of the furnace body 10 in an inclined manner and measure the surface temperature of the refractory material 12 in the intermediate region D2. Referring to FIG. 2, the thermal imaging camera 60 according to a modified example of the present invention allows the burner 70 to be described later to measure the surface temperature of the refractory 12 in the middle region D2 of the furnace body 10 The burner 70 may be inclined with respect to the extended direction. Accordingly, the thermal imaging camera 60 may tilt the middle region D2 of the furnace body 10 when the furnace body 10 is tilted, and measure the surface temperature of the refractory material 12 in the middle region D2. .

The thermal imaging camera 60 may take a thermal image of the surface of the refractory 12. At this time, as the thermal imaging camera 60 moves away from the surface of the refractory 12, an error in the surface temperature of the thermal image and the refractory 12 captured by the thermal imaging camera 60 may occur. Accordingly, the thermal imaging camera 60 may be spaced within 30 m from the surface of the refractory 12 in the intermediate region D2 of the furnace body 10. Preferably, the thermal imaging camera 60 may be spaced within 20 m from the surface of the refractory 12 in the middle region D2 of the furnace body 10. That is, the distance L between the thermal imaging camera 60 and the surface of the refractory 12 in the intermediate region D2 of the furnace body 10 may be within 20 m. For example, if the thermal imaging camera 60 is farther than 20 m from the surface of the refractory 12 in the intermediate region D2 of the furnace body 10, the accuracy of the thermal imaging may deteriorate. On the other hand, if the thermal imaging camera 60 is farther than 30 m from the surface of the refractory 12 in the middle region D2 of the furnace body 10, due to interference with structures around the furnace body 10, the thermal imaging camera 60 Deployment can be difficult.

The thermal camera 60 classifies the subject in the photographing area by temperature, and the pixels of the thermal image are color-coded according to temperature. At this time, as the size of the photographing area is smaller, the thermal imaging camera 60 can clearly distinguish the temperature profile of the subject. For example, if the size of the imaging area of the thermal imaging camera 60 is large, the temperature variation in the imaging area is large, and the thermal imaging of the surface of the refractory 12 is complicated. If the size of the imaging area of the thermal imaging camera 60 is small, the temperature deviation in the imaging area is small, and the thermal image on the surface of the refractory 12 becomes relatively simple.

The thermal imaging camera 60 may be provided with a lens hood (not shown) in front of the lens to reduce the size of the imaging area, that is, to narrow the angle of view of the lens (not shown) of the thermal imaging camera 60. At this time, the lens hood may have various shapes such as a circular lens hood and a square lens hood. The lens hood is a hollow cylindrical shape, and is mounted to surround the lens, and can be extended to the front of the lens. The lens hood narrows the angle of view of the thermal imaging camera 60, and the thermal imaging camera 60 can locally photograph the surface of the refractory 12 in the middle section D2 of the furnace body 10.

The control unit (not shown) may control the operation of the burner 70 so that the temperature of the refractory material 12 is higher than the reference temperature. The control unit may obtain the surface temperature of the refractory 12 from state information on the surface of the refractory 12 detected by the non-contact temperature measuring device.

Specifically, when the thermal imaging camera 60 is used as a non-contact temperature measuring device, the control unit may acquire the surface temperature of the refractory 12 from a thermal imaging photograph of the surface of the refractory 12 photographed by the thermal imaging camera 60. have. In addition, when an infrared thermometer is used as a non-contact temperature meter, the control unit may acquire the surface temperature of the refractory 12 from the infrared radiation energy of the surface of the refractory measured by the infrared thermometer.

When the surface temperature of the refractory material 12 is equal to or lower than the reference temperature, the control unit operates the burner 70 to rotate the above-described horizontal axis to incline the furnace body 10 and spray flame F into the furnace body 10. I can do it.

Specifically, the control unit receives a thermal image from the thermal imaging camera 60, reads the color of the pixels of the thermal image input, and at least one pixel displayed in a color corresponding to a temperature below a reference temperature among the pixels If it is abnormal, it is determined that the surface temperature of the refractory material 12 in the slag penetration region is below the reference temperature. When it is determined that the surface temperature of the refractory material 12 in the slag penetration region is equal to or lower than the reference temperature, the controller controls the operation of the horizontal axis described above to tilt the furnace body 10, and the flame (F) inside the furnace body 10 It can operate the burner 70 to spray.

Alternatively, the control unit receives the energy intensity and wavelength distribution of infrared radiation energy from the infrared thermometer, and if the received energy intensity or wavelength distribution is the energy intensity or wavelength distribution of infrared radiation energy corresponding to a temperature below the reference temperature, the slag penetration area It is determined that the surface temperature of the refractory material 12 is below the reference temperature. When it is determined that the surface temperature of the refractory material 12 in the slag penetration region is equal to or lower than the reference temperature, the controller controls the operation of the horizontal axis described above to tilt the furnace body 10, and the flame (F) inside the furnace body 10 It can operate the burner 70 to spray.

The melt processing apparatus is installed to surround the furnace sphere of the furnace body 10, the hood 20 through which the lance 30 penetrates in the vertical direction, the hopper 40 installed on the outside of the hood 20, the hopper 40 It is connected to, extending toward the furnace of the furnace body 10, may further include a chute (50) installed to penetrate the hood (20).

The inside of the hood 20 may be opened downward. The hood 20 may extend in the vertical direction. The lance 30 may be installed to penetrate the hood 20 in the vertical direction. The hood 20 may have negative pressure formed therein. The hood 20 may extract gas from the furnace port of the furnace body 10 using negative pressure. The thermal imaging camera 60 may be located inside the hood 20.

The hopper 40 may be a plurality. The hopper 40 may be stored in the input. The input may include a deoxidizing agent, a desulfurizing agent and a flux. At this time, the input may be various types depending on the process performed in the furnace body (10). A deoxidizing agent, a desulfurizing agent, and a flux may be stored in the hopper 40, respectively. A valve (not shown) is provided at the bottom of the hopper 40, and when the valve is opened, an input may be supplied to the chute 50.

The chute 50 may be installed such that one end is branched and connected to the lower portion of the hopper 40, the other end extends toward the furnace, and penetrates the lower portion of the hopper 20. The input may be charged into the furnace body 10 through the chute 50. The thermal imaging camera 60 may be supported at the other end of the suit 50. Of course, the thermal imaging camera 60 may be supported on the inner wall of the hood 20.

3 is a flow chart of a melt processing method according to an embodiment of the present invention. In addition, Figure 4 is a phase equilibrium diagram of a slag according to an embodiment of the present invention, Figure 5 (a) and (b) is a thermal imaging photograph of the furnace body refractory by refining in the refining process according to the embodiment of the present invention to be. In addition, Figure 6 is a graph for explaining the change in the life of the refractory according to an embodiment of the present invention.

Hereinafter, a method of treating a melt using a melt treating apparatus according to an embodiment of the present invention will be described in detail with reference to FIGS. 1 to 6.

The method of processing a melt according to an embodiment of the present invention includes charging a melt in a container with an open top, processing a melt, discharging a processed melt from a container, measuring an internal temperature of the container, and And controlling the internal temperature to be higher than a predetermined reference temperature. At this time, the process of measuring the internal temperature of the container includes a process of measuring the temperature of the refractory material built in the container.

The melt processing method according to the embodiment of the present invention may include a process of controlling the internal temperature of the container to be higher than a predetermined reference temperature, charging the subsequent melt in the container, and processing the subsequent melt.

The melt may include molten steel for manufacturing stainless steel. Stainless steel for manufacturing stainless steel can be produced in an electric furnace process. The molten steel for the production of stainless steel produced in the electric furnace process may also be referred to as molten metal. Of course, the melt may vary.

The container may include a furnace body 10 of a refining furnace capable of receiving and blowing molten steel. The furnace body 10 may be the furnace body 10 of the AOD refining furnace. The refractory material 12 constructed inside the furnace body 10 may include a refractory material having a porosity of 20% or less and a carbon content of less than 5% by weight of the total weight of the refractory material. During the processing of the melt, slag may be generated inside the furnace body 10. The slag may be located inside the middle region D2 of the furnace body 10, and a slag layer may be formed at a predetermined thickness on the molten metal melt surface. The slag can contact the refractory 12 in the middle region D2 of the furnace body 10. The slag may include stainless steel slag having a basicity of 1.3 or higher. The slag may include calcium oxide (CaO) and silicon dioxide (SiO ₂ ). During the processing of the melt, the basicity of the slag can increase or decrease.

Slag has various phases according to temperature according to the basicity (C / S), which is an index indicating the ratio of calcium oxide and silicon dioxide. Figure 4 is a diagram of the equilibrium slag according to an embodiment of the present invention, specifically, FIG equilibrium CaO-SiO _{2 2-component} system phase. In the horizontal axis of the figure, the content of silicon dioxide in the slag is large when going to the right, and the content of calcium oxide in the slag is large when going to the left. The vertical axis of the drawing is the temperature axis. In the figure, the hatched square region is a region where the slag has a basicity of 1.3 or more.

Typically, during the process of refining the stainless steel, the basicity of the slag is controlled in the range of 1 to 3. At this time, 2CaO · SiO ₂ (Dicalcium silicate, C ₂ S) in the condition of the basicity of the slag is about 1.3 or higher, phase transitions from α-C ₂ S to α´-C ₂ S as the temperature of the slag decreases, and is about 725 ° C. The phase transitions to γ-C ₂ S again in the vicinity. At this time, C ₂ S density before and after the phase change becomes lower as the density is 2.97g / cm ³ eseo 3.31g / ㎝ ^3. At this time, a decrease in density at the same mass means volume expansion. That is, the C ₂ S phase of the slag before and after the phase transition undergoes a volume expansion of 10% or more, and powdering is performed. This is called slag differentiation. In addition, spalling of the refractory occurs by expansion of the C ₂ S phase of the slag that has penetrated into the pores of the refractory 12.

In this case, cracks are generated inside the refractory 12, and the life of the refractory 12 is reduced. On the other hand, the C ₂ S phase of the slag that has penetrated the pores of the refractory 12 is a high-melting-point phase, and when the above-described phase transition is suppressed, it can act as a protective layer. That is, the C ₂ S phase of the slag fills up the pores of the refractory 12 and prevents the penetration of the later slag without volume expansion.

First, a process in which a melt is charged into a container with an open top, such as a furnace body 10, and the melt is processed. A molten material such as molten steel is charged into the furnace body 10, and oxygen and argon are blown into the furnace body 10 through the lance 30 and the nozzle to blow the molten material. The melt can be blown with argon gas and oxygen gas. During the blow of the melt, the content of carbon, oxygen and sulfur components contained in the melt can be adjusted. At this time, a deoxidizing agent, a desulfurizing agent, and a flux may be introduced into the furnace body 10.

Thereafter, a process of discharging the melted material from the furnace body 10 is performed (S100). By rotating the horizontal axis (not shown) described above, the furnace body 10 is tilted, and the treated melt in the furnace body 10 is discharged to a ladle (not shown). During the processing of the melt, slag is formed on top of the melt. Thus, before or after the process of discharging the melt, slag exclusion may be performed. Slag exclusion means that the furnace body 10 is tilted to discharge the slag in the furnace body 10 to a slag port (not shown).

Thereafter, a process of measuring the internal temperature of the furnace body 10 is performed (S200). The process of measuring the internal temperature of the furnace body 10 includes a process of measuring the temperature of the refractory material 12 built in the furnace body 10. The temperature of the refractory 12 is measured in a non-contact manner using a thermal imaging camera 60 as a temperature measuring unit or an infrared thermometer. At this time, at the height at which the slag is formed, a thermal image of the surface of the refractory 12 is photographed to measure the surface temperature of the refractory 12 at the height at which the slag is formed in the form of a thermal image. Alternatively, by measuring the infrared radiation energy of the surface of the refractory 12 at the height at which the slag is formed, the surface temperature of the refractory body 12 at the height at which the slag is formed in the form of energy intensity and wavelength distribution is measured.

That is, the process of measuring the surface temperature of the refractory material includes detecting a state information on the surface of the refractory material in a non-contact manner using a non-contact temperature measuring device and obtaining a surface temperature of the refractory material from the state information.

Here, the status information may be varied, including thermal imaging and infrared radiation energy on the surface of the refractory. Therefore, the process of detecting the state information on the surface of the refractory material includes the process of taking a thermal image of the surface of the refractory material, and the process of obtaining the surface temperature from the detected state information is performed by the surface temperature from the captured thermal image photograph. It may include the process of obtaining a. At this time, the thermal image camera 60 may continuously photograph the thermal image of the refractory surface, or periodically photograph at a predetermined time interval.

Alternatively, the process of detecting the state information on the surface of the refractory material includes measuring the infrared radiation energy of the surface of the refractory material, and the process of obtaining the surface temperature of the refractory material from the detected state information is measured infrared radiation energy It may include the process of obtaining the surface temperature using at least one of the energy intensity and wavelength distribution of.

The reference temperature is defined as the surface temperature of the refractory 12 when the internal temperature of the refractory substance 12 is a temperature capable of preventing the spalling of the slag penetrating the refractory substance 12. The reference temperature may be determined in advance by reflecting the penetration depth of the slag in the phase transition temperature of the slag, and may be input to the control unit. Here, the phase transition temperature of the slag means a temperature at which the C ₂ S phase of the slag phase changes from α´-C ₂ S to γ-C ₂ S. In the case of stainless slag having a basicity of 1.3 or higher, the phase transition temperature may be a predetermined temperature value around 725 ° C.

The reason for measuring the surface temperature of the refractory 12 is to control the surface temperature of the refractory 12 to be higher than the reference temperature. Here, the reference temperature is higher than the phase transition temperature of the slag. The reason for this is as follows.

The refractory material 12 built in the furnace body 10 has a high temperature on the inner surface toward the inner space of the furnace body 10, and a temperature gradually decreases in the direction toward the iron shell 11 of the furnace body 10. Therefore, even if the surface temperature of the refractory 12 is higher than the phase transition temperature of the slag, the internal temperature of the refractory 12 may be lower than the phase transition temperature of the slag. In this case, slag penetrating deep inside the refractory 12 may be differentiated. That is, when the surface temperature of the refractory material 12 becomes a reference temperature or higher than the phase transition temperature of the slag, it is preferable to heat the refractory material 12 of the furnace body 10.

Therefore, by setting the reference temperature higher than the phase transition temperature of the slag, it is possible to control the surface temperature of the refractory material 12 in the slag penetration region to be higher than the phase transition temperature of the slag, and the slag penetrating inside the refractory material 12 of the slag It is possible to suppress or prevent the phase transition from being cooled to a temperature lower than the temperature.

At this time, the deeper the penetration depth of the slag penetrating into the interior of the refractory 12 from the surface of the refractory 12 through the pores of the refractory 12, the greater the difference between the reference temperature and the phase transition temperature. When the phase transition temperature of the slag is about 725 ° C, the reference temperature is greater than 725 ° C, and the deeper the penetration depth of the slag, the greater the reference temperature. That is, the reference temperature may be proportional to the depth of penetration of the slag penetrating into the interior of the refractory 12 from the surface of the refractory 12 through the pores of the refractory 12.

In summary, the reference temperature can be determined according to the depth of penetration of the slag to the refractory material 12. At this time, the larger the porosity of the refractory 12, the deeper the penetration depth of the slag, and the deeper the penetration depth of the slag, the higher the reference temperature. For example, porosity, penetration depth, and reference temperature are proportional to each other.

Here, if the porosity of the refractory 12 is about 20%, the depth through which the slag penetrates may be about 50 mm from the surface of the refractory 12. As the porosity increases, the penetration depth becomes deeper, and as the porosity decreases, the penetration depth may decrease.

The depth of penetration can be obtained by inspecting the refractory 12 built in the furnace body 10 at the end of the refining process. Alternatively, a refining experiment may be performed similarly to the refining furnace process using an experimental apparatus simulating the furnace body 10, and the depth of penetration of the slag may be obtained by inspecting the refractory of the experimental apparatus. Alternatively, the penetration depth can be theoretically determined by using physical properties of the refractory material 12 and slag during the refining process.

Considering the depth of penetration of the slag, the reference temperature may be set to 1100 ° C. When the surface temperature of the refractory material 12 is 1100 ° C, the temperature gradually decreases as it moves away from the surface of the refractory material 12, and the temperature of a portion 50 mm deep from the surface of the refractory material 12 is 725 ° C at a temperature higher than 725 ° C. Even close to, it can be maintained at a temperature higher than 725 ° C.

More preferably, the reference temperature can be set to 1300 ° C. Accordingly, when the surface temperature of the refractory material 12 is 1300 ° C, the temperature of a portion 50 mm deep from the surface of the refractory material 12 can be maintained at a temperature higher than 725 ° C. In addition, if the surface temperature of the refractory 12 is 1300 ° C, even if the slag penetrates deeper into the refractory 12 than 50 mm for reasons such as an increase in porosity of the refractory 12, the temperature of the portion where the slag penetrated is increased. It can be maintained at a temperature higher than 725 ° C.

In the process of photographing the thermal image of the surface of the refractory 12 with the thermal imaging camera 60, the thermal imaging camera 60 is separated from the surface of the refractory 12 by a distance within 20 m. That is, the distance between the surface of the refractory 12 and the thermal imaging camera 60 is within 20 m. Thus, it is possible to secure the accuracy of the photographed thermal image.

5 (a) and (b) are thermal imaging photographs of the furnace body refractory material in a refining process according to an embodiment of the present invention. Performing a smelting furnace process to which the melt processing method according to an embodiment of the present invention is applied, and taking a thermal image of the surface of the refractory 12 with a thermal imaging camera 60, as shown in FIGS. 5 (a) and 5 (b). I was able to get a thermal image.

5 (a) is a thermal image of the surface of the refractory film 12 taken by the thermal imaging camera 60 after the melt discharge is finished, the temperature of spot 1 is 1157 ° C, and the temperature of spot 2 is 1156 ° C. Appears.

FIG. 5 (b) is a thermal image of the surface of the refractory film 12 after a predetermined time has passed after discharging the melt, and the temperature of spot 1 is 822 ° C, and the temperature of spot 2 is 822 It appears that it is ℃. At this time, looking at part a (shown in black circle) of FIG. 5 (b), spalling of the refractory 12 is confirmed in the thermal image. That is, when the refractory 12 is cooled in the atmosphere of the furnace body 10 and the temperature of the surface of the refractory 12 becomes lower than the reference temperature, it can be confirmed that spalling occurs in the refractory 12.

As described above, a thermal image of the surface of the refractory 12 is photographed by the thermal image camera 60 to generate a thermal image and send it to the control unit to perform the following process.

Thereafter, a process of controlling the internal temperature of the furnace body 10, that is, the surface temperature of the refractory material 12 to be higher than a predetermined reference temperature is performed.

At this time, by comparing the measured temperature and the reference temperature, it is determined whether the measured temperature is below the reference temperature (S300). For example, the control unit reads the color of the pixels of the thermal image received from the thermal imaging camera 60, and if there is at least one pixel of a color corresponding to a temperature below a reference temperature, the refractory material of the slag penetration area ( It is judged that the surface temperature of 12) is below the reference temperature. On the other hand, if there is no pixel displayed in a color corresponding to a temperature below the reference temperature among the pixels of the thermal image, the controller determines that the surface temperature of the refractory material 12 in the slag penetration region is higher than the reference temperature.

Alternatively, the control unit compares the energy intensity and wavelength distribution of the infrared radiation energy received from the infrared thermometer with the energy intensity and wavelength distribution of the infrared radiation energy corresponding to a temperature below the reference temperature, so that the energy intensity or wavelength of the received infrared radiation energy If the distribution is included in the energy intensity or wavelength distribution of infrared radiation energy corresponding to a temperature below the reference temperature, it is determined that the surface temperature of the refractory material 12 in the slag penetration region is below the reference temperature. On the other hand, if the energy intensity or wavelength distribution of the received infrared radiation energy is not included in the energy intensity or wavelength distribution of the infrared radiation energy corresponding to a temperature below the reference temperature, the control unit may adjust the surface temperature of the refractory material 12 in the slag penetration region. It is judged that it is higher than the reference temperature.

If it is determined that the surface temperature of the refractory material 12 in the slag penetration region is below the reference temperature, that is, when the measured temperature is below the reference temperature, the inside of the furnace body 10 is heated to a temperature higher than the reference temperature (S400). . At this time, the process of heating the inside of the furnace body 10 includes tilting the furnace body 10 and spraying flames inside the furnace body 10. At this time, a heat source such as a burner 70 is disposed to face the inside of the furnace body 10, and a flame is injected into the furnace body 10 using the burner 70.

Here, flame spraying may continue until the subsequent melt is ready. Thereafter, when the subsequent melt is prepared, the burner 70 is stopped to stop the injection of the flame F. Subsequently, a subsequent melt is charged to the furnace body 10, and subsequent melt processing is started. Alternatively, the flame is sprayed for a predetermined time, and the flame is temporarily stopped, and then it is determined whether the subsequent melt is ready (S500). If the subsequent melt is not ready, the above-described temperature measurement process inside the container is repeated. When the subsequent melt is ready, the burner 70 is stopped to stop spraying the flame F. Subsequently, a subsequent melt is charged to the furnace body 10 and subsequent melt processing is started (S600).

On the other hand, if the measured temperature is higher than the reference temperature, the control unit determines whether a subsequent melt is prepared (S500). If the subsequent melt is not ready, the temperature measurement process inside the vessel is repeated. When the subsequent melt is ready, the burner 70 is stopped to terminate the injection of the flame F, the melt is charged into the furnace body 10, and processing of the subsequent melt is started (S600).

Thus, by maintaining the surface temperature of the refractory 12 higher than the reference temperature at all times, it is possible to suppress or prevent the slag differentiation that has penetrated into the refractory 12.

By the above-described process, during the process of processing the melt, the slag that has penetrated into the pores of the slag 12 is cooled in the atmosphere of the furnace body 10 and can be prevented or prevented from being expanded in volume while being phase-shifted. That is, slag differentiation can be suppressed or prevented by the above-described process.

On the other hand, in order to increase the temperature of the refractory 12, if the burner 70 is always operated, rather than immediately after discharging the melt from the furnace body 10, cooling of the refractory 12 can be promoted. While refining the melt in the furnace body 10, the furnace body 10 is controlled to have an internal temperature of about 2000 ° C. Immediately after discharging the melt from the furnace body 10, the temperature of the furnace body 10 has a temperature of about 1700 ° C to 1800 ° C. Here, the temperature of the flame injected from the burner 70 is around 1300 ° C. Accordingly, if the flame is injected into the furnace body 10 immediately after discharging the melt from the furnace body 10, the furnace body 10 can be rapidly cooled to about 1300 ° C. by the flame. On the other hand, increasing the proportion of oxygen supplied to the burner 70 to increase the flame temperature of the burner 70 to about 1700 ° C to 1800 ° C, there is a safety problem, and the tip of the burner 70 may be damaged by high heat. have.

As described above, according to an embodiment of the present invention, the furnace body 10 waits while the furnace body 10 waits until after the treatment of the melt is completed and discharged from the furnace body 10 at this time until a subsequent melt of the next cycle is prepared. It is possible to control the temperature of the refractory material 12 built in the interior to be higher than the reference temperature.

Specifically, while the furnace body 10 is in standby, the surface temperature of the refractory 12 may be measured in real time using a thermal imaging camera 60 in a non-contact manner, and the surface temperature of the refractory 12 may be measured using the measurement result. It is possible to control the operation of the burner 70 so that it is always higher than the reference temperature.

Therefore, while the furnace body 10 is in standby, the temperature of the refractory 12 can be maintained at all times above the critical temperature at which spalling does not occur. Therefore, while the furnace body 10 is in standby, spooling of the refractory 12 can be suppressed or prevented, and the life of the refractory 12 can be improved. That is, the furnace body 10 can be used smoothly without changing the refractory material and process conditions.

Referring to FIG. 6, the X-axis of the graph refers to the furnace of the refining furnace, and the Y-axis refers to the life of the refining furnace. Here, when charging from the charging of the melt to the discharge of the processed melt is a one-time process, one refining furnace furnace is made of a plurality of times, for example, several hundred to several thousand times. When the furnace is finished by one refining, the refractory 12 of the furnace body 10 is rebuilt. Subsequently, the next refining furnace performs multiple rounds of the furnace. When the condition of the refractory material 12 is good, the number of rounding steps of the refining furnace furnace increases.

The line A of the graph shows a smelting furnace process of stainless steel by the above-described melt treatment method according to an embodiment of the present invention, and represents the number of rounding furnace furnace furnace processes by smelting furnace life. The B line of the graph shows the number of rounding furnace processes by furnace smelt as the life of the smelter while performing the smelter process with the melt processing method according to the comparative example of the present invention. Melt processing method according to a comparative example of the present invention, the process of measuring the internal temperature of the furnace body 10 in the above-described melt processing method according to an embodiment of the present invention, the internal temperature of the furnace body 10 is higher than the reference temperature Control was excluded.

As shown in lines A and B of the graph, it can be seen that when the smelting furnace process of the stainless steel was performed by the melt treatment method according to the embodiment of the present invention, the number of rounding processes by furnace smelter is increased. That is, in the case of the embodiment, it can be seen that the life of the refractory 12 is increased by 10% or more than the comparative example, and it can be seen that the life deviation of the refractory 12 is reduced to half. Therefore, according to an embodiment of the present invention, in the operation of the furnace body 10 for the refining process of stainless steel, it is possible to lengthen the refractory replacement time, thereby improving the productivity of the process and reducing costs by refining the stainless steel. You can.

The above embodiments of the present invention are for the purpose of describing the present invention and not for the limitation of the present invention. It should be noted that the configurations and methods disclosed in the above embodiments of the present invention may be modified in various forms by combining or crossing each other, and such modified examples may be viewed as the scope of the present invention. That is, the present invention will be implemented in a variety of different forms within the scope of the claims and equivalent technical spirit, and various embodiments are possible within the scope of the technical spirit of the present invention. Will be able to understand.

Claims (16)

1. Charging a melt in a container with an open top and processing the melt;

   Discharging the processed melt from the container;

   Measuring the internal temperature of the container;

   Including the process of controlling the internal temperature of the container to be higher than a predetermined reference temperature; includes,

   The process of measuring the internal temperature of the container,

   Melt processing method comprising the step of measuring the temperature of the refractory material built in the container.
2. The method according to claim 1,

   In the process of processing the melt, a slag is formed on top of the melt,

   The process of measuring the temperature of the refractory material,

   And measuring the surface temperature of the refractory material at a height at which the slag is formed.
3. The method according to claim 2,

   The process of measuring the surface temperature of the refractory material,

   A method of processing a melt, comprising the step of detecting state information on the surface of the refractory material in a non-contact manner and obtaining the surface temperature from the state information.
4. The method according to claim 2,

   The reference temperature is a melt processing method higher than the phase transition temperature of the slag.
5. The method according to claim 4,

   Melt treatment method for determining the reference temperature according to the depth of penetration of the slag to the refractory.
6. The method according to claim 5,

   The larger the porosity of the refractory, the deeper the penetration depth,

   The deeper the penetration depth, the higher the reference temperature is.
7. The method according to claim 3,

   The process of detecting the state information on the surface of the refractory material includes a process of photographing a thermal image of the surface of the refractory material,

   In the process of photographing the thermal image of the surface of the refractory material, a melt processing method of separating a thermal imaging camera at a distance within 20 m from the refractory surface.
8. The method according to claim 1,

   The process of controlling the internal temperature of the container to be higher than the reference temperature,

   Comparing the measured temperature with the reference temperature;

   And if the measured temperature is below the reference temperature, heating the inside of the container to a temperature higher than the reference temperature.
9. The method according to claim 8,

   The process of heating the inside of the container,

   Tilting the container, and spraying a flame inside the container,

   After the process of heating the inside of the container,

   And charging the subsequent melt into the container and processing the subsequent melt.
10. The method according to claim 1,

    The melt includes molten steel for manufacturing stainless steel,

    The refractory material has a carbon content of less than 5% by weight of the total weight of the refractory material, and a porosity of 20% or less.
11. A container in which an upper portion is opened and a refractory material is built inside;

    A lance disposed above the container;

    A heat source provided on the outside of the container;

    A temperature measuring unit disposed on the top of the container, supported by the heat source, spaced apart from the refractory, and capable of measuring the temperature of the refractory;

    The control unit for controlling the operation of the heat source so that the temperature of the refractory material is higher than a predetermined reference temperature.
12. The method according to claim 11,

    The container has an inlet region, an intermediate region and a lower region, and a slag is located in the intermediate region when processing the melt,

    The temperature measuring unit is disposed to be inclined at an upper portion of the container to face the intermediate region, or to be supported by the heat source and to be inclined with respect to the direction in which the heat source is extended, so as to measure the surface temperature of the refractory in the intermediate region. Melt processing device.
13. The method according to claim 12,

    The temperature measuring unit includes a non-contact temperature measuring instrument,

    The control unit is a melt processing apparatus for obtaining the surface temperature from the state information on the surface of the refractory detected by the non-contact temperature meter.
14. The method according to claim 13,

    The non-contact temperature measuring device includes a thermal imaging camera,

    The thermal imaging camera is a melt processing apparatus that can be spaced apart within a distance of less than 20m from the surface of the refractory material in the intermediate region.
15. The method according to claim 14,

    The thermal imaging camera is a melt processing apparatus having a hood in front of the lens to narrow the angle of view.
16. The method according to claim 11,

    The control unit melts the apparatus for operating the heat source to spray a flame into the interior of the container if the temperature of the refractory is below the reference temperature.

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