A method and apparatus for separating different types of titanium-containing oxides in a melt by electromagnetic induction forces

Abstract

This invention belongs to the field of iron and steel smelting technology and discloses a method for separating different types of Ti-containing oxides in a melt using electromagnetic induction. The method includes: placing iron with a purity greater than 99% in a crucible, placing it in an induction furnace, introducing an inert gas into the furnace, and heating the iron to melt it by controlling the output power of the induction furnace; holding the melt at a certain temperature, first adding aluminum with a purity greater than 99%, and then adding titanium with a purity greater than 99% after a certain interval to alloy it; and finally cooling the alloying furnace or water quenching it to the solidification temperature to obtain an ingot. A corresponding apparatus is also provided. Using the above method and apparatus, different types of Ti-containing oxides in a melt can be effectively separated.

Description

Technical Field

[0001] This invention belongs to the field of iron and steel smelting technology, and particularly relates to a method and apparatus for separating different types of Ti-containing oxides in a melt by electromagnetic induction force. Background Technology

[0002] Non-metallic inclusions in steel are a collective term for various non-metallic particles embedded in the steel, and their types can be analyzed from different perspectives. For example, based on chemical composition, they can be classified as oxides, sulfides, and nitrides; based on plasticity, they can be classified as plastic inclusions, brittle inclusions, and non-deformable inclusions; and based on size, they can be classified as large inclusions and micro inclusions. In steel, oxides are the most common inclusions, including simple oxides, silicates, spinel inclusions, and calcium aluminates. Oxides are formed during the steelmaking process by the reaction of deoxidizers (such as aluminum and silicon) with oxygen in the molten steel. The most prevalent sulfide inclusion is MnS, which usually forms during the solidification of molten steel due to sulfur segregation. Nitride inclusions, such as AlN, TiN, and Ti(CN), have high melting points and stability, existing as precipitates in the steel. These inclusions have a significant impact on the strength and toughness of steel. Inclusions in steel can come from many sources, such as products generated by chemical reactions between various internal components or between the steel and the atmosphere or container in the furnace during the smelting, casting and solidification processes of steel, or particulate matter precipitated when the molten steel cools down due to factors such as reduced solubility.

[0003] Traditional electromagnetic stirring technology introduces electromagnetic force into molten steel by applying a strong magnetic field to the induction furnace. This electromagnetic force causes inclusions in the molten steel to migrate to the outside of the melt, promoting their removal and refining the solidification structure of the steel. This technology has advantages such as simple operation and significant results. However, this technology removes all types of inclusions in molten steel indiscriminately through electromagnetic induction, focusing on the interaction between the melt and particles while neglecting the influence of the differences in the particles themselves on their migration behavior within the melt.

[0004] It is generally believed that inclusions larger than 1 μm are detrimental to steel quality because large inclusions disrupt the continuity of the steel matrix. In recent years, the "oxide metallurgy" method, which utilizes inclusions smaller than 1 μm to refine the steel microstructure, has been applied. Researchers have discovered that fine and dispersed inclusions in steel can induce the formation of acicular ferrite. Since acicular ferrite is a microstructure with high dislocation density, it can improve the toughness of the heat-affected zone. Among inclusions with inducing ability, Ti-containing oxides were the first to be studied and have been widely used in oxide metallurgy.

[0005] In the Fe-Al-Ti-O system, Ti oxides exist in multiple valence states. At 1600℃, different Ti oxides with different valence states, such as Ti2O3, Ti3O5, and Al2TiO5, can be generated in molten steel. Traditional methods involve melting the alloy in a resistance heating furnace. The resulting ingot contains a mixture of different types of Ti oxides, making it difficult to separate different types of Ti oxides and multiphase inclusions in the melt. Detailed analysis of the quantity, density, size, composition, and phase characteristics of inclusions is not possible, thus failing to explain the formation mechanism of a single type of Ti oxide in the melt. Summary of the Invention

[0006] The technical problem to be solved by the present invention is to overcome the deficiencies and defects mentioned in the background art above, and to provide a method and apparatus for effectively separating different types of Ti-containing oxides in a melt by electromagnetic induction force.

[0007] To solve the above-mentioned technical problems, the technical solution proposed by this invention is as follows:

[0008] A method for separating different types of Ti-containing oxides in a melt by electromagnetic induction force includes:

[0009] Iron with a purity greater than 99% is placed in a crucible and then placed in an induction furnace. Inert gas is introduced into the furnace, and the iron is melted by controlling the output power of the induction furnace to obtain a melt.

[0010] After holding the melt at a certain temperature for a certain period of time, aluminum with a purity greater than 99% is added first, and titanium with a purity greater than 99% is added after a certain interval to alloy it.

[0011] The alloy melt is cooled in a furnace or water-quenched to the solidification temperature to obtain an ingot.

[0012] In one embodiment, the process further includes cutting the ingot, grinding and polishing its longitudinal section, first using an optical microscope to obtain the location and characteristic morphology of inclusions in the ingot sample, and then using scanning electron microscopy-energy dispersive spectroscopy to characterize the composition, morphology and size of each oxide.

[0013] In one embodiment, the electromagnetic frequency of the induction furnace is 30-200kHz, and the maximum output power is 5kW.

[0014] In one embodiment, the inert gas is argon, helium, or nitrogen, or a combination thereof.

[0015] In one embodiment, the melt holding temperature is 1600°C, and the temperature deviation is controlled within 3°C.

[0016] In one embodiment, the melt holding time is 5 min to 60 min.

[0017] In one embodiment, the interval between the addition of aluminum and titanium is 0.5 min to 10 min.

[0018] In one embodiment, the water quenching is performed by immersing a crucible containing the alloy melt in water for quenching to obtain an ingot, with a water quenching rate of 2°C / s to 8°C / s.

[0019] In one embodiment, the iron with a purity greater than 99% is a mixture of electrolytic iron and iron-containing alloys.

[0020] Based on a general inventive concept, the present invention also provides an apparatus for the above-described method of separating different types of Ti-containing oxides in a melt by electromagnetic induction force, comprising:

[0021] The furnace body includes a quartz tube, with quick-change furnace covers at the top and bottom of the quartz tube;

[0022] An induction coil is arranged around the outside of a quartz tube;

[0023] The quartz tube has an air inlet at the bottom and an air outlet at the top. The top of the quartz tube also has a material feeding port.

[0024] The quartz tube has a refractory lining near the bottom to support the crucible.

[0025] The thermometer uses infrared sensing to detect the temperature of the molten material inside the quartz tube.

[0026] Compared with existing technologies, the advantages of this invention are as follows: Ti can form different types of oxides in steel, and traditional methods cannot separate different types of Ti-containing oxides, such as Ti2O3 and Al2TiO5. However, in this patent application, electromagnetic induction force is used to separate different types of Ti-containing oxides in steel, thereby enabling the study of the formation mechanism of a single type of Ti-containing oxide.

[0027] A magnetic field is applied to molten steel in an induction furnace. In the Fe-Al-Ti-O system, Al or Ti oxides migrate to the vicinity of the crucible wall under the influence of electromagnetic induction. Due to differences in density, size, and composition among different types of Ti oxides in the melt, there are differences in the interfacial tension between the different types of Ti oxides and the molten steel, resulting in different migration rates and a "migration time difference"—meaning they reach different positions on the crucible wall within the same time frame. Furthermore, the migration behavior of Ti oxides is affected by factors such as current frequency, holding time, and charge ratio. Therefore, by controlling these influencing factors, different types of Ti oxides in the melt can reach different positions on the crucible wall within the same time frame, thus achieving separation.

[0028] Characterization methods show that, in cross-section, the alloy obtained using the method of this patent application has an outer layer consisting of a thickness of 100 to 700 μm from the crucible wall, where inclusions are mainly Al₂O₃, Al+Ti oxides, and Al-Ti oxides. The inner layer, excluding the outer layer, contains TiN inclusions. Within the outer layer, Al₂O₃, Al+Ti oxides, and Al-Ti oxides are distributed in different regions, demonstrating effective separation of different types of Ti oxides. This facilitates the understanding of the formation mechanism of a single type of Ti oxide in the melt. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 One embodiment of the apparatus for separating different types of Ti-containing oxides in a melt by means of electromagnetic induction force;

[0031] Figure 2 This is a distribution diagram of Al+Ti oxides and Al-Ti oxides in a molten iron-based alloy under the conditions of electromagnetic induction and without electromagnetic induction, wherein, a is the distribution diagram of Al+Ti oxides and Al-Ti oxides in the molten iron-based alloy under the condition of electromagnetic induction; b is the distribution diagram of Al+Ti oxides and Al-Ti oxides in the molten iron-based alloy without electromagnetic induction.

[0032] Figure 3 This is a distribution diagram of inclusions on the cross-section of an alloy according to one embodiment;

[0033] Figure 4 One embodiment is a dispersed and regularly arranged Al-Ti oxide;

[0034] Figure 5 Energy dispersive spectroscopy (EDS) analysis of Al-Ti oxides in an alloy sample according to one embodiment;

[0035] Figure 6 The energy dispersive spectroscopy (EDS) spectrum of Al+Ti oxides in an alloy sample according to one embodiment is shown. Detailed Implementation

[0036] To facilitate understanding of the present invention, the present invention will be described more fully and in detail below with reference to the accompanying drawings and preferred embodiments, but the scope of protection of the present invention is not limited to the following specific embodiments.

[0037] Please see Figures 1-6 A method for separating different types of Ti-containing oxides in a melt by electromagnetic induction force, comprising:

[0038] S110. Place iron with a purity greater than 99% into a crucible, place it in an induction furnace, introduce inert gas into the furnace, and heat and melt it by controlling the output power of the induction furnace to obtain a melt.

[0039] Specifically, in one embodiment, the electromagnetic frequency of the induction furnace is 30kHz to 200kHz, and the maximum output power is 5kW.

[0040] The inert gas is argon, helium, or nitrogen, or a combination thereof. Preferably, the inert gas is argon.

[0041] S120. After holding the melt at a certain temperature, aluminum with a purity greater than 99% is added first, and after a certain period of time, titanium with a purity greater than 99% is added for alloying.

[0042] Specifically, in one embodiment, the melt is held at 1600°C, and the temperature deviation is controlled within 3°C. Furthermore, a dual-wavelength thermometer is used to monitor the melt temperature, and the temperature deviation is controlled within 3°C by adjusting the output power of the induction furnace. The melt holding time is 5 min to 60 min, and the interval between the addition of aluminum and titanium is 0.5 min to 10 min.

[0043] The system employs a dual-wavelength thermometer to monitor the melt for non-contact temperature measurement and provides real-time temperature feedback, enabling precise temperature control, including holding temperature, holding time, and heating / cooling rates.

[0044] Specifically, in one embodiment, the iron with a purity greater than 99% is a mixture of electrolytic iron and iron-containing alloys, wherein the purity of the electrolytic iron, aluminum, and titanium is greater than or equal to 99%, preferably 99.9%. More preferably, the purity of the electrolytic iron is greater than 99.9%.

[0045] S130: The alloy is furnace cooled or water quenched to the solidification temperature to obtain an ingot.

[0046] Specifically, in one embodiment, cooling the alloy to its solidification temperature to obtain an ingot can be achieved through furnace cooling or water quenching. Furthermore, if furnace cooling is used, the alloy is directly furnace-cooled to its solidification temperature to obtain an ingot, which is then removed together with the crucible.

[0047] Alternatively, water quenching can be used to cool the crucible containing the alloy melt by immersing it in water to quench it and obtain an ingot, with a water quenching rate of 2°C / s to 8°C / s.

[0048] Furthermore, the method of this patent application for separating different types of Ti-containing oxides in a melt by electromagnetic induction force also includes the following steps:

[0049] S140 also includes cutting the ingot, grinding and polishing its longitudinal section, first using an optical microscope to obtain the location and characteristic morphology of inclusions in the ingot sample, then using a scanning electron microscope to characterize the composition and morphology of each inclusion, and finally using energy dispersive spectroscopy to obtain the composition, morphology and particle size distribution of different types of Ti oxides.

[0050] Please see Figure 1 The present invention also provides an apparatus for use in the above method, comprising:

[0051] Furnace body 10, induction coil 20, and temperature measuring instrument 30. The induction coil 20 is arranged in a ring around the outside of the furnace body 10. The electromagnetic frequency and output power of the induction coil 20 are controlled by the control system.

[0052] The furnace body 10 includes a quartz tube 110, with quick-change furnace covers 120 at the top and bottom. An air inlet 130 is located at the bottom of the quartz tube 110, and an air outlet 140 is located at the top. The air inlet 130 is used to introduce inert gas, and the air outlet 140 is used to discharge inert gas. A material feeding port 150 is also located at the top of the quartz tube 110 for feeding aluminum, titanium, etc. A refractory lining 160 for supporting the crucible is located inside the quartz tube 110 near the bottom.

[0053] The thermometer 30 uses infrared sensing to detect the temperature of the melt inside the quartz tube, and adjusts the electromagnetic frequency and output power of the induction coil 20 according to the temperature detected by the thermometer 30.

[0054] Specifically, the temperature measuring instrument 30 is a dual-wave temperature measuring instrument, which performs non-contact temperature measurement of the melt and provides real-time temperature feedback, enabling the heating system to achieve precise temperature control, including holding temperature, holding time, heating and cooling rates, etc.

[0055] The use of a quick-change furnace cover 120 ensures the airtightness of the furnace body and allows the crucible to be quickly removed for subsequent water quenching.

[0056] Unless otherwise defined, all technical terms used herein have the same meaning as commonly understood by those skilled in the art. The technical terms used herein are for the purpose of describing particular embodiments only and are not intended to limit the scope of the invention.

[0057] Unless otherwise specified, all raw materials, reagents, instruments and devices used in this invention can be purchased from the market or prepared by existing methods.

[0058] Example:

[0059] A method for separating different types of Ti-containing oxides in a melt using electromagnetic induction force includes the following steps:

[0060] (1) Weigh 120 grams of electrolytic iron and place it in a magnesium oxide crucible. Put the crucible into an induction furnace, control the electromagnetic frequency of the induction furnace to 200 kHz and the maximum output power to 5 kW, and heat the electrolytic iron to melt it in an Ar atmosphere at 1600 ℃ to obtain a melt. During the heating process, the temperature is monitored by a dual-wave thermometer, and the temperature deviation is controlled to be within 3 ℃ by adjusting the output power of the induction furnace.

[0061] (2) After holding the melt at a constant temperature for 30 minutes, 0.1491g of aluminum (99.9% purity) and 0.0954g of titanium (99.9% purity) were added sequentially, with an interval of 2 minutes between the addition of aluminum and titanium, to carry out alloying.

[0062] (3) Cool the alloy furnace to the solidification temperature to obtain the ingot.

[0063] (4) The total O content of the alloy was determined to be 0.0020% by inert gas melting pulse infrared absorption spectroscopy, the total N content was determined to be 0.0032% by inert gas melting thermal conductivity method, and the soluble Al content was determined to be 0.0497% and Ti content was determined to be 0.0636% by ICP-OES method.

[0064] Example 2:

[0065] 100g of electrolytic iron and 20g of carbon-containing pig iron were weighed and placed in a magnesium oxide crucible. The crucible was then placed in an induction furnace, with the electromagnetic frequency of the furnace controlled at 100kHz and the maximum output power at 5kW. The electrolytic iron was heated to melt at 1600℃ in a N2 atmosphere until a molten substance was obtained. During the heating process, the temperature was monitored using a dual-wavelength thermometer, and the temperature deviation was controlled to be within 3℃ by adjusting the output power of the induction furnace.

[0066] (2) After holding the melt at a constant temperature for 40 minutes, 0.0369g of aluminum (99.9% purity) and 0.0879g of titanium (99.9% purity) were added sequentially, with an interval of 5 minutes between the addition of aluminum and titanium, to carry out alloying.

[0067] (3) Take out the crucible containing the alloy melt, immerse the crucible in water to quench and obtain the ingot. The water quenching cooling rate is 3.7℃ / s.

[0068] (4) The total O content of the alloy was determined to be 0.0069% by inert gas melting pulse infrared absorption spectroscopy, the total N content was determined to be 0.0110% by inert gas melting thermal conductivity method, and the soluble Al content was determined to be 0.0123% and Ti content was determined to be 0.0586% by ICP-OES method.

[0069] Characterization analysis:

[0070] Characterization analysis of the alloys obtained in Examples 1 and 2 revealed that the inclusion observation area on each alloy cross-section comprised two regions: an outer layer and an inner layer. The distribution of inclusions on the alloy cross-section is shown in the figure. Figure 3 As shown.

[0071] The outer layer refers to the region 100 to 700 μm thick from the crucible wall, and its inclusions are mainly Al₂O₃, Al+Ti oxides, and Al-Ti oxides. The inner layer is the region excluding the outer layer, and its inclusions are TiN. Al₂O₃ is a deoxidation product after the addition of Al; its formation mechanism involves Al₂O₃ generated in the molten steel migrating from the melt to the crucible wall under the influence of electromagnetic induction and agglomerating into clusters. Both Al+Ti oxides and Al-Ti oxides are distributed in the outer layer. Al+Ti oxides refer to a heterogeneous phase with uneven distribution of Al and Ti elements. Al-Ti oxides refer to a homogeneous phase with uniform distribution of Al and Ti elements. Figure 3 As shown, in the outer layer, Al2O3, Al+Ti oxide and Al-Ti oxide are distributed in different regions. It can be seen that by using the method of this patent application, different types of Ti oxides are effectively separated, which is beneficial to revealing the formation mechanism of a single type of Ti oxide in the melt.

Claims

1. A method for separating different types of Ti-containing oxides in a melt using electromagnetic induction force, characterized in that, include: Iron with a purity greater than 99% is placed in a crucible and then placed in an induction furnace. Inert gas is introduced into the furnace, and the iron is melted by controlling the output power of the induction furnace to obtain a melt. After holding the melt at a certain temperature for a certain period of time, aluminum with a purity greater than 99% is added first, and titanium with a purity greater than 99% is added after a certain interval to alloy it. The alloy melt is cooled in a furnace or water-quenched to the solidification temperature to obtain an ingot; The process also includes cutting the ingot, grinding and polishing its longitudinal section, first using an optical microscope to obtain the location and characteristic morphology of inclusions in the ingot sample, and then using scanning electron microscopy-energy dispersive spectroscopy to characterize the composition, morphology and size of each oxide; the alloy, viewed from the cross-section, has an outer layer consisting of a region 100 to 700 μm thick from the crucible wall, where the inclusions are mainly Al2O3, Al+Ti oxides and Al-Ti oxides, and an inner layer consisting of the region outside the outer layer, where the inclusions are TiN.

2. The method for separating different types of Ti-containing oxides in a melt by electromagnetic induction force according to claim 1, characterized in that, The electromagnetic frequency of the induction furnace is 30-200kHz, and the maximum output power is 5kW.

3. The method for separating different types of Ti-containing oxides in a melt by electromagnetic induction force according to claim 1, characterized in that, The inert gas is argon, helium, nitrogen, or a combination thereof.

4. The method for separating different types of Ti-containing oxides in a melt by electromagnetic induction force according to claim 1, characterized in that, The melt holding temperature is 1600℃, and the temperature deviation is controlled within 3℃.

5. The method for separating different types of Ti-containing oxides in a melt by electromagnetic induction force according to claim 1, characterized in that, The melt holding time is 5 min to 60 min.

6. The method for separating different types of Ti-containing oxides in a melt by electromagnetic induction force according to claim 1, characterized in that, The interval between the addition of aluminum and titanium is 0.5 min to 10 min.

7. The method for separating different types of Ti-containing oxides in a melt by electromagnetic induction force according to claim 1, characterized in that, The water quenching cooling is performed by immersing a crucible containing the alloy melt in water for quenching to obtain an ingot, with a water quenching cooling rate of 2℃ / s to 8℃ / s.

8. The method for separating different types of Ti-containing oxides in a melt by electromagnetic induction force according to claim 1, characterized in that, Iron with a purity greater than 99% is a mixture of electrolytic iron and iron-containing alloys.

9. An apparatus for the method of separating different types of Ti-containing oxides in a melt by electromagnetic induction force as described in any one of claims 1-8, characterized in that, include: The furnace body includes a quartz tube, with quick-change furnace covers at the top and bottom of the quartz tube; An induction coil is arranged around the outside of a quartz tube; The quartz tube has an air inlet at the bottom and an air outlet at the top. The top of the quartz tube also has a material feeding port. The quartz tube has a refractory lining near the bottom to support the crucible. The thermometer uses infrared sensing to detect the temperature of the molten material inside the quartz tube.

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