Molten iron treatment process

Abstract

A method of treating molten iron includes adding a metal treatment agent to the molten iron and stirring the molten iron with a rotating device including a rotor head that is corrosion and thermal shock resistant and allows for efficient application of the metal treatment agent.

Description

[Technical Field]

[0001] The present invention relates to a method for treating molten metal. In particular, the present invention relates to the treatment of molten iron, and more particularly to the treatment of molten iron to produce ductile iron (also known as nodular graphite iron or SGI) or compacted graphite iron (CGI) from the molten iron. The present invention also relates to a system, apparatus, and method for adding a metal treatment agent to molten metal. Nodular graphite iron (SGI) or compacted graphite iron (CGI) are used to manufacture components such as automotive parts, parts for construction or agricultural machinery, ductile iron pipe, and general engineering components, respectively. [Background technology]

[0002] Metal treatment agents are used to modify the composition, morphology, and / or distribution of inclusions in molten iron. Metal treatment agents applied to molten iron can include nodularizing agents and inoculants that can be used to change the morphology of the iron structure and produce ductile iron and CGI.

[0003] Thus, producing ductile iron and CGI from molten iron typically involves adding a nodularizing agent, such as magnesium, to convert the carbon and graphite present in the molten iron into spheroidized forms, with the magnesium acting as the nodularizing agent. When producing ductile iron from molten iron, an inoculant (e.g., zirconium, magnesium) may be added to promote nucleation of the carbon and graphite. In many cases, the nodularizing agents and inoculants are typically 90% ferrosilicon, with the ferrosilicon acting as a soluble carrier. In other words, the "active" component of such ferrosilicon-based nodularizing agents or inoculants may account for as little as 10% of the total weight or volume of the nodularizing agent or inoculant.

[0004] Because the boiling point of magnesium is lower than the melting point of iron, it is difficult and dangerous to add magnesium to molten iron. Therefore, if elemental magnesium is added in large quantities at once, it will either explosively vaporize or immediately oxidize upon contact with molten iron. For this reason, magnesium-based metal treatment agents are usually added in a stabilized form, such as ferrosilicon magnesium, rather than in elemental form.

[0005] Furthermore, the process of treating molten iron typically involves placing a ferrosilicon-based nodularizing agent in a vessel such as a processing ladle, and then pouring molten iron into the processing ladle so that the ferrosilicon-based nodularizing agent or nodularizing material can react with the molten iron. As a next step, a ferrosilicon-based inoculant is placed in a vessel such as a pouring ladle, and then the contents of the processing ladle are transferred to the pouring ladle, allowing the ferrosilicon-based inoculant to react with the contents of the pouring ladle to produce, for example, ductile iron. The nodularizing agent precipitates carbon as graphite spheres rather than graphite flakes, and the inoculant serves as a nucleus for increasing the number of graphite nodules in the ductile iron.

[0006] CN106435216, CN210560654, and EA016954 disclose rotating devices for use in aluminum processing. JPS6245464 and RU2247289 disclose rotating devices with protective outer surfaces. EP0691410 、 CN111004965 and US2015 / 267272 discloses a treatment agent for treating iron and steel. US 4,496,393 discloses a plunging capsule for supplying magnesium to molten iron. JP2007031810 discloses a desulfurization system and process. EP0396267 discloses a system for applying particulate metal treatment through a rotor. The present invention seeks to provide an improved method for treating molten metal, such as molten iron, which overcomes some of the limitations in the art, or at least provides a useful alternative. Summary of the Invention

[0007] In accordance with various embodiments of the disclosed subject matter, a method for treating molten iron is provided. According to claim 1 Provided 。

[0008] According to at least one embodiment, the metal treatment agent is added to the molten iron while it is being stirred, causing the metal treatment agent to bubble through the molten iron, for example, to produce ductile iron or compacted graphite iron (CGI) from the molten iron.

[0009] According to at least one embodiment, the metal treatment agent includes a nodulizing agent. In one embodiment, the nodulizing agent can be one or more of magnesium, calcium, and calcium carbide. In one embodiment, the nodulizing agent is magnesium. According to at least one embodiment, the metal treatment agent includes at least 50% magnesium. In some embodiments, the metal treatment agent includes at least 90% or at least 95% magnesium.

[0010] According to at least one embodiment, the molten iron can be received from a cupola furnace. The molten iron received from the cupola furnace can be desulfurized by bubbling at least one of magnesium, calcium, and calcium carbide through the molten iron. After desulfurization, the sulfur level in the molten iron can be tested. After desulfurization and / or testing, for example, magnesium can be used as a nodularizing agent and magnesium can be bubbled through the molten iron.

[0011] According to at least one embodiment, the method further comprises discharging a gas into the molten iron through the rotor head.

[0012] gold The metal treatment may include powder, wire, or cored wire. nothingAccording to at least one embodiment, the method can further include feeding a cored wire containing a metal treatment agent into the molten iron. In some embodiments, the cored wire includes an outer sheath containing a refractory metal. The wire can include an inner core containing a metal treatment agent.

[0013] In one embodiment, the metal treatment agent comprises magnesium, calcium, calcium carbide, cerium, ferrosilicon magnesium, or a combination thereof.

[0014] According to at least one embodiment, adding a metal treatment agent to the molten iron includes adding a first metal treatment agent and at least a second metal treatment agent. According to at least one embodiment, the second metal treatment agent includes at least 30% zirconium. In some embodiments, the second metal treatment agent includes at least 50% zirconium. According to at least one embodiment, the second metal treatment agent includes at least 30% barium, or at least 50% barium.

[0015] According to at least one embodiment, the second metal treatment agent may include an inoculant. The inoculant may be zirconium, manganese, barium, calcium, ferrosilicon, or a combination thereof. Preferably, the inoculant is zirconium.

[0016] According to at least one embodiment, the first metal treating agent includes magnesium. The second metal treating agent can include barium. The method can further include adding the first metal treating agent after adding the second treating agent.

[0017] According to at least one embodiment, the method further includes sparging argon gas into the molten iron. The argon may be sparged prior to adding the second treatment agent.

[0018] According to at least one embodiment, the rotating device includes a tubular sleeve having a rotor head at one end. The rotating device can include a shaft extending within the tubular sleeve, e.g., at least a portion of the shaft can be surrounded by the tubular sleeve. The tubular sleeve can be formed from a heat-resistant material that is resistant to corrosion and thermal shock. The shaft can be formed from a material including graphite. According to at least one embodiment, the shaft can be hollow. According to at least one embodiment, the metal treating agent is added to the molten iron through the hollow shaft. According to at least one embodiment, the metal treating agent is added to the molten iron via the rotor head. According to at least one embodiment, the metal treating agent is applied to the molten iron adjacent to the rotating device. According to at least one embodiment, a first metal treating agent is added to the molten iron via the rotor head, and a second metal treating agent is added to the molten iron adjacent to the rotating device.

[0019] According to at least one embodiment, the rotor head is integrally formed with the tubular sleeve, or alternatively, the rotor head can be coupled to the end of the tubular sleeve.

[0020] According to at least one embodiment, the hollow shaft has a first end and a second end. The first end may be surrounded by a tubular sleeve. Optionally, the second end of the hollow shaft is configured to be coupled to an apparatus for rotating the rotational device.

[0021] According to at least one embodiment, the rotor head includes an outlet for adding a metal treatment agent to the molten iron.

[0022] According to at least one embodiment, the shaft is a hollow shaft. The hollow shaft may be in communication with an outlet through which the metal treatment agent passes into the molten ferrous metal.

[0023] According to at least one embodiment, a rotating device (also referred to herein as a "rotor") for stirring molten metal (e.g., molten iron) is provided.

[0024] The rotating device includes a tubular sleeve having a rotor head at one end, a shaft extending through the tubular sleeve and at least a portion of the shaft being surrounded by the tubular sleeve. The tubular sleeve and the rotor head may be formed from a heat-resistant material that is resistant to corrosion and thermal shock. The shaft may be formed from a heat-resistant material including graphite.

[0025] In a first aspect of the present invention, a method for treating molten metal is provided. The method can include adding a metal treating agent to the molten metal. The method can include stirring the molten metal with a rotating device including a rotor head. In some embodiments, the molten metal is ferrous metal. In some embodiments, the molten metal is iron.

[0026] In some embodiments, the molten metallic iron has a temperature in the range of 1375-1550°C. Optionally, the temperature of the molten metal may be at least 1400°C, at least 1410°C, at least 1420°C, at least 1430°C, at least 1440°C, at least 1450°C, at least 1460°C, or at least 1470°C. Optionally, the temperature may be less than 1540°C, less than 1530°C, less than 1520°C, less than 1510°C, less than 1500°C, less than 1490°C, or less than 1480°C. In some embodiments, the molten metal is between 1450-1500°C.

[0027] In some embodiments, the molten iron may have a carbon equivalent content of 3 to 5 wt. Optionally, the carbon equivalent may be greater than 3.1, 3.2, 3.3, 3.4, 3.5, 3.6, 3.7, 3.8, 3.9, 4, 4.1, 4.2, 4.3, 4.4, or 4.5 wt. Optionally, the carbon equivalent may be less than 4.9, 4.8, 4.7, 4.6, 4.5, 4.4, 4.3, 4.2, 4.1, 4, 3.9, 3.8, 3.7, 3.6, or 3.5 wt. Note that any of the above lower range limits may be combined with any of the above upper range limits. The carbon equivalent is the total content of carbon in the molten iron and any additional substances (such as allowable elements) that have a similar effect to carbon.

[0028] It will be understood that any features and embodiments described in relation to one method may equally be applied to any other method described herein. [Brief explanation of the drawings]

[0029] Embodiments of the present invention will now be described, by way of example only, with reference to the accompanying schematic drawings in which parts corresponding to the reference numerals given herein are shown.

[0030] [Figure 1] FIG. 1 illustrates a rotation device according to one embodiment of the present invention, in accordance with various embodiments of the subject matter disclosed herein.

[0031] [Figure 2] FIG. 2 is a cross-sectional view of the rotational device shown in FIG. 1 according to various embodiments of the presently disclosed subject matter.

[0032] [Figure 3] FIG. 3 illustrates a hollow shaft for use with a rotation device according to one embodiment of the present invention, in accordance with various embodiments of the subject matter disclosed herein.

[0033] [Figure 4] FIG. 4 is a cross-sectional view of the hollow shaft shown in FIG.

[0034] [Figure 5] FIG. 5 illustrates a rotation device according to one embodiment of the present invention, in accordance with various embodiments of the subject matter disclosed herein.

[0035] [Figure 6] FIG. 6 is a cross-sectional view of the rotational device shown in FIG. 5 according to various embodiments of the presently disclosed subject matter.

[0036] [Figure 7] FIG. 7 is a schematic diagram illustrating a combination of a rotation device according to one embodiment of the present invention and a stirring apparatus for use in stirring and processing molten metal, according to various embodiments of the subject matter disclosed herein.

[0037] [Figure 8] FIG. 8 illustrates velocity field simulation data for (a) a dual-plate rotor head structure and (b) a single-plate rotor head structure rotating at 600 rpm, according to various embodiments of the subject matter disclosed herein.

[0038] [Figure 9] FIG. 9 shows simulation data of a scaled flow pattern corresponding to the velocity field simulation data shown in FIG.

[0039] [Figure 10] FIG. 10 illustrates velocity field simulation data and scaled flow pattern simulation data for a single-plate rotor head configuration rotating at (a) 100 rpm, (b) 200 rpm, and (c) 300 rpm, according to various embodiments of the subject matter disclosed herein.

[0040] [Figure 11] FIG. 11 is a high-resolution photomicrograph showing the structure of (a) gray iron, (b) compacted graphite iron (CGI), and (c) ductile iron castings according to various embodiments of the presently disclosed subject matter.

[0041] [Figure 12] FIG. 12 is a schematic diagram of an existing procedure for adding metal treatment agents to molten iron, according to various embodiments of the subject matter disclosed herein.

[0042] [Figure 13] FIG. 13 is a schematic diagram illustrating a procedure for adding a metal treatment to molten iron, according to various embodiments of the presently disclosed subject matter.

[0043] [Figure 14] FIG. 14 is a high-resolution photomicrograph of the structure of compacted graphite iron (CGI).

[0044] [Figure 15] Figure 15 shows a high-resolution micrograph of ductile iron with nodular graphite formed around each nucleus. DETAILED DESCRIPTION OF THE INVENTION

[0045] Various embodiments of the subject matter disclosed herein are directed to improved systems, methods, and apparatus for processing molten metal, such as molten iron, to convert the molten iron into improved forms of iron suitable for casting applications (e.g., compacted graphite iron (CGI) and ductile iron). FIG. 11, in accordance with various embodiments of the subject matter disclosed herein, shows high-resolution micrographs of three main types of castable iron products produced from molten iron: (a) gray iron, (b) compacted graphite iron (CGI), and (c) ductile iron. FIG. 14 shows the high-resolution micrograph of compacted graphite iron (CGI). FIG. 15 shows the high-resolution micrograph of ductile iron. FIG. 15a further shows spheroidal graphite 401 formed around a nucleus 403. In one embodiment, the nuclei can be provided by an inoculant additive that is added to the molten iron, whereby the graphite present in the molten iron forms graphite spheroids 401 around the nuclei 403 provided by the inoculant, forming more ductile (less brittle) forms of iron, such as ductile iron and compacted graphite iron (CGI).

[0046] Fig. 12 is a diagram showing an existing method for treating molten iron. According to the existing method shown in Fig. 12, a metal treating agent 205 (e.g., a nodularizing agent), such as a ferrosilicon-based nodularizing agent (e.g., FeSiMg), is placed in a treatment ladle 207 (or is pre-loaded into the treatment ladle 207), and then molten iron 203 present in a furnace 201 is transferred to the treatment ladle 207 carrying the metal treating agent 205. Arrow 202 indicates the transfer of the molten iron 203 to the treatment ladle 207.

[0047] After the molten iron 203 present in the furnace 201 is transferred to a processing ladle 207 containing a metal treatment agent 205, a first stage 400a begins, in which the metal treatment agent 205 reacts with the molten iron 203 to produce nodular molten iron 203a. The reaction between the metal treatment agent 205 and the molten iron 203 is indicated by arrow 209, thereby producing nodular molten iron 203a. The nodular molten iron 203a present in the processing ladle 207 is then transferred to a pouring ladle 211 that is pre-loaded with an inoculant 213, for example a ferrosilicon-based inoculant. Arrow 212 indicates the transfer of the nodular molten iron 203a to the pouring ladle 211. Next, the second stage 500a begins, in which the inoculant 213 reacts with the nodulated molten iron 203a to produce one or more ductile irons and / or compacted graphite irons (CGI) from the nodulated molten iron 203a. Arrow 215 indicates the next step in casting.

[0048] 12 , various existing methods include placing a metal treatment agent (such as a ferrosilicon-based nodularizing agent) in a first vessel, such as a processing ladle, to initiate a reaction, thereby producing nodularized molten iron. The existing methods optionally further include placing an inoculant, such as a ferrosilicon-based inoculant, in a second vessel, such as a pouring ladle, and then transferring the contents of the processing ladle (i.e., the nodularized molten iron) to the pouring ladle. As a result, the ferrosilicon-based inoculant reacts with the nodularized molten iron contained in the pouring ladle to produce ductile iron. The ductile iron can be used, for example, in cast iron products.

[0049] As shown, for example, in FIG. 13, various embodiments of the presently disclosed subject matter include various improvements over the method described with reference to FIG.

[0050] One embodiment of an improved method and system for treating molten metal, such as molten iron, is shown in FIG. 13. FIG. 13 illustrates a method for treating molten iron in accordance with at least one embodiment of the subject matter disclosed herein. According to the method illustrated in FIG. 13, molten iron 203 present in a furnace 201 is transferred to a processing ladle 207. Arrow 202 indicates the transfer of the molten iron 203 to the processing ladle 207. A rotating device 100 including a rotor head 5 is then introduced into the molten iron 203 contained in the processing ladle 207. During operation, the rotor head 5 of the rotating device 100 rotates to stir, churn, and / or agitate the molten iron 203. When a metal treating agent 205 (e.g., shown in wire form in FIG. 13) is added to the molten iron 203 while the rotor head 5 is stirring it, the metal treating agent 205 vaporizes and bubbles through the molten iron in the form of small bubbles 223.

[0051] In one embodiment, the metal treatment agent 205 comprises primarily magnesium. In one embodiment, the metal treatment agent comprises at least 20% magnesium. In various embodiments, the metal treatment agent 205 may comprise at least 25%, 30%, 35%, 40%, 45%, 50%, 55%, 60%, 65%, 70%, 75%, 80%, 85%, or 90% magnesium. In one embodiment, the metal treatment agent comprises at least 90% magnesium. In one embodiment, the metal treatment agent comprises at least 95% magnesium. In one embodiment, the metal treatment agent comprises at least 98% magnesium.

[0052] For ease of explanation, the metal treating agent 205 will be described below with reference to magnesium. Magnesium has a boiling point of approximately 1,996°F (1,091°C), while iron has a melting point of approximately 2,120°F (1,160°C). Because the temperature of molten iron is higher than the boiling point of magnesium, vaporization of magnesium occurs immediately upon contact with the molten iron. Thus, magnesium vaporizes upon interaction with the high temperature of the molten iron 203. The vaporized magnesium is converted into small bubbles 223 by stirring or agitating the molten iron due to the rotation of the rotating rotor head 5. In the first step 400 of the improved method and system, the metal treating agent 205 (e.g., in the form of a nodularizing agent such as magnesium) reacts with the molten iron 203 to produce nodularized molten iron 203a.

[0053] In various embodiments, the metal treatment agent can take the form of a powder, a wire, or a cored wire. In at least one embodiment, the method includes feeding a cored wire containing the metal treatment agent into molten iron. In one embodiment, the cored wire includes an outer sheath including a high melting point metal. The cored wire includes an inner core, and the inner core can include the metal treatment agent. In one embodiment, the metal treatment agent includes magnesium, calcium, calcium carbide, cerium, ferrosilicon magnesium, or a combination thereof. In one advantageous embodiment, the metal treatment agent 205 is in the form of magnesium.

[0054] In one embodiment, particularly when the magnesium is in powder form, a gas (e.g., argon gas) is added simultaneously with the magnesium into the molten iron, for example, to push the magnesium down and out of the hollow shaft forming part of the rotating device 100, preventing the magnesium from clogging.

[0055] In the existing process shown in FIG. 12 , magnesium is present at concentrations greater than 10%, causing the magnesium to react too vigorously with the molten iron 203. In contrast, in the improved process shown in FIG. 13 , for example, the rotation of the rotor head 5 advantageously generates very fine magnesium vapor bubbles, such as tiny bubbles 223, which are more readily absorbed by the molten iron. The stirring and agitation action of the rotor head 5 results in a less vigorously but highly effective reaction between the magnesium and the molten iron 203. In various embodiments, the rotation speed of the rotor head 5 is optimized to minimize the size of the magnesium (or any other suitable metal treatment agent) vapor bubbles, while simultaneously maximizing the surface area of ​​the magnesium in contact with the molten iron, thereby increasing the effectiveness of the reaction with the molten iron and further ensuring that different portions of the molten iron are in contact with the magnesium sequentially. Therefore, the stirring, agitation, etc., action of the rotor head 5 is advantageous. Therefore, the improved process not only optimizes the reaction but also reduces the time required to achieve the optimal reaction. The rotor's agitation action further assists this. The smaller magnesium bubbles allow the magnesium to be absorbed into the iron more quickly, improving yield and reducing (undesirable) oxidation. In various embodiments, the rotational speed of the rotor head 5 may be adjusted to optimize the reactions occurring in the first stage 400 (and second stage 500) shown in Figure 13.

[0056] The process shown in Figure 13 offers advantages over existing processes in that it uses higher concentrations of magnesium. The use of higher concentrations of magnesium offers significant cost benefits over existing processes, such as those shown in Figure 12. For example, in existing methods of ladle treatment known as the "sandwich process," metal treatment agents in the form of FeSiMg typically have a magnesium content of about 10% because higher magnesium concentrations result in overly violent reactions. In contrast, the improved processes disclosed herein can handle higher magnesium concentrations, for example, magnesium concentrations of up to 98% purity or higher, depending on the application at hand.

[0057] The reactions / processes occurring in the first stage 400 produce nodularized molten iron 203a. In at least one embodiment, the nodularized molten iron 203a itself can be used for casting. In other words, the nodularized molten iron 203a is in the form of ductile iron or compacted graphite iron (CGI) and is suitable for casting iron products. Arrow 215 indicates the next step in casting.

[0058] In some embodiments according to the improved process disclosed herein, the nodulated molten iron 203a is further subjected to a second stage 500. In the second stage 500, an inoculant 213 (shown in the form of a wire in FIG. 13 ) is applied to the nodulated molten iron 203a present in the processing ladle 207. According to at least one embodiment, the inoculant 213 reacts with the nodulated molten iron 203a and modifies the structure of the nodulated molten iron 203a, increasing the nodule count and reducing the nodule size to be more regular.

[0059] The process shown in FIG. 13 is advantageous because the reaction between the nodularizing agent and the molten iron, and the reaction between the inoculant and the molten iron, are much more effective than existing processes, such as those shown in FIG. 12. For example, in existing processes, the nodularizing agent and inoculant are typically based on 90% ferrosilicon (the ferrosilicon acts as a soluble carrier). In existing processes, the metal treatment agent in the form of FeSiMg (containing a low concentration of magnesium) is placed at the bottom of the ladle floor, which, due to the lack of stirring or agitation, results in inconsistent interaction between the molten iron and the magnesium vapor, and large bubbles of magnesium vapor interact with a fixed (i.e., non-moving) volume of molten iron. As a result, a high percentage of the magnesium vapor reaches the top surface of the molten iron without reacting with it, resulting in waste. Additionally, the molten iron contents are transferred to the next stage (i.e., second stage 500a) in an under-reacted state without the magnesium lower near the ladle floor having an opportunity to react with the molten iron, further adversely affecting the quality of the reaction and resulting in waste FeSiMg.

[0060] In contrast, the improved methods and systems disclosed herein allow pure (100%) magnesium, or magnesium at high concentrations (e.g., greater than 40%, 50%, 60%, 70%, 80%, 90%, 95%, 98%, and other percentages therebetween) to be subjected to the nodularization reaction, thereby reducing the cost and amount of raw materials required for the nodularization reaction. Furthermore, the improved methods and systems disclosed herein allow magnesium to be introduced from the top, eliminating the waste of unreacted magnesium that occurs in existing processes. The improved method and system disclosed herein provides a stable reaction due to the following factors: (1) the stirring action of the rotor head 5 actively moves the molten iron through and among the magnesium vapor bubbles; (2) the stirring action of the rotor head 5 creates smaller magnesium bubbles, thereby increasing the surface area of ​​contact between the molten iron and the magnesium; and (3) the magnesium feed rate / amount can be automatically controlled (because the magnesium is introduced from the top side into the molten iron already in the ladle). The improved method and system disclosed herein also eliminates the need to transfer the contents of the first ladle (processing ladle) to a second ladle (pouring ladle) before the next step (i.e., second step 500) is performed, because the magnesium and inoculant can be added to the molten iron in the same first ladle (processing ladle), as shown in FIG. 13, for example. The improved method and system disclosed herein allows for better monitoring and control of the reaction quality and control of the magnesium addition during the first stage 400 reaction because the magnesium, for example in wire form, is added to the molten iron from the top side, whereas in existing methods, the molten iron is poured onto the FeSiMg that is pre-charged in a ladle.

[0061] In accordance with the improved methods and systems disclosed herein, a method of treating molten iron includes adding a metal treating agent to the molten iron and stirring the molten iron with a rotating device including a rotor head 5. In some embodiments, the metal treating agent (e.g., a nodulizing agent in the form of magnesium) is added during stirring so that the metal treating agent bubbles through the molten iron to produce ductile iron or compacted graphite iron (CGI) from the molten iron.

[0062] The inventors have found that applying a metal treatment agent to molten iron while stirring the molten iron can reduce the amount of metal treatment agent required. Nodulizing agents, such as magnesium, rapidly vaporize in the molten iron. Therefore, the inventors have found that stirring the molten iron improves the dispersion of magnesium gas bubbles throughout the iron, reducing their size and increasing their surface area / volume ratio, resulting in longer residence time and improved absorption into the iron. In the case of magnesium, when the gas bubbles reach the top surface of the molten iron, they rapidly oxidize, forming an MgO slag layer, which renders them inactive as a nodulizing agent. The improved method disclosed herein has the advantage of minimizing the amount of magnesium that reaches the top surface of the molten iron. If this slag gets into the mold, it can plug filters and cause casting defects such as slag inclusions.

[0063] In some embodiments, the metal treating agent can be applied to the molten iron in the vicinity of the rotating device. Additionally or alternatively, the metal treating agent can be added to the molten iron through the hollow shaft, and optionally through the rotor head.

[0064] In various embodiments, the method may include feeding a cored wire containing a metal treating agent into the molten metal. In embodiments, the cored wire includes an outer sheath containing a high-melting point metal, such as iron or steel, and an inner core containing the metal treating agent. In embodiments, the metal treating agent includes a desulfurizing agent, a nodulating agent, an inoculant, or a mixture thereof. In embodiments, the metal treating agent includes magnesium, ferrosilicon magnesium, calcium, calcium oxide, calcium carbide, barium, strontium, or a combination thereof, in elemental or compound form.

[0065] In an advantageous embodiment, the cored wire comprises a magnesium core and an iron or steel sheath. In use, the outer sheath prevents the core material from reacting or oxidizing immediately and gradually melts or dissolves, releasing the core material at a predetermined depth below the surface of the molten metal. Combining processes with the cored wire can further enhance desulfurization and / or processing and structural modification of the molten iron.

[0066] In various embodiments, the rotating device 100 includes a tubular sleeve 1 having a rotor head 5 at one end and a shaft extending within the tubular sleeve 1 such that at least a portion of the shaft is surrounded by the tubular sleeve, the tubular sleeve 1 being formed from a heat-resistant material that is resistant to corrosion and thermal shock, and the shaft being formed from a material that includes graphite. In one embodiment, the shaft is a hollow shaft, such as the hollow shaft 3 shown in FIG. 1.

[0067] According to one embodiment, the hollow shaft has a first end and a second end, the first end being surrounded by a tubular sleeve, and optionally the second end of the hollow shaft being configured to be coupled to an apparatus for rotating the rotary device. According to one embodiment, the rotor head 5 includes an outlet for adding a metal treating agent to the molten iron. According to one embodiment, the shaft is a hollow shaft, and the hollow shaft can be in communication with an outlet. In one embodiment, the rotor head 5 is integrally formed with the tubular sleeve 1. In one embodiment, the rotor head 5 is coupled to an end of the tubular sleeve.

[0068] According to one embodiment, the metal treating agent is added to the molten iron through the hollow shaft. According to one embodiment, the metal treating agent is added to the molten iron through the rotor head 5. According to one embodiment, the metal treating agent is applied to the molten iron in the vicinity of the rotating device. According to one embodiment, gas is released into the molten iron through the rotor head 5.

[0069] For comparison, the mechanical properties of different forms of iron are as follows: (1) gray cast iron has an ultimate tensile strength (UTS) of 150 to 350 MPa (megapascals); and (2) ductile cast iron has an ultimate tensile strength (UTS) of 350 to 800 MPa (megapascals). The improved process disclosed herein effectively produces more ductile iron. Graphite present in molten iron in flake form often acts as a crack initiator. Changing the shape of the graphite to a spheroidal form increases the strength of the iron without making it too brittle. The nodularization process involves treating molten iron with a nodularizing agent, such as magnesium, which converts the graphite into a spheroidal form rather than a flaky form. While flaky graphite embrittles iron and reduces its ductility, spheroidal graphite increases the ductility of the iron and reduces its brittleness. Spheroidal graphite can increase the ductility of the iron, resulting in a steel that is not so strong that it becomes unusable due to the iron's brittleness. The use of a rotor head to stir the molten iron breaks up the injected bubbles of magnesium while simultaneously stirring the molten iron, improving absorption efficiency. The improved process allows for the feeding of a magnesium cored wire to initiate graphite spheroidization. Therefore, in at least one embodiment, the metal treatment agent includes a nodulizing agent, preferably magnesium. In some embodiments, cerium is used as the nodulizing agent. Magnesium is advantageous because it is cost-effective.

[0070] In some embodiments, the method includes discharging a solid metal treating agent through or near the rotor head. In some embodiments, the metal treating agent is in the form of a wire or powder. In some embodiments, the metal treating agent is contained within a cored wire. Discharging the metal treating agent through or near the rotor head allows for rapid and efficient distribution of the metal treating agent throughout the molten metal.

[0071] The inventors of the present invention have found that when Mg / Ca is rapidly dispersed throughout the metal before it vaporizes or oxidizes, this rapid dispersion of elemental Mg or Ca used as an oxidizer significantly reduces the risks normally associated with using elemental Mg / Ca in the molten metal, which also reduces the amount of metal treating agent needed to effectively treat the molten metal, reducing the buildup of excess metal treating agent that can cause embrittlement in the final casting.

[0072] A protective coating is not necessarily required because discharging the metal treatment agent through the rotor head serves to shield the metal treatment agent from exposure to the molten metal while contained within the rotating device, and the metal treatment agent can be discharged into the molten metal at a depth corresponding to the depth of the rotor head. However, for convenience, a cored wire with a protective coating can be used when other forms of metal treatment agent are not available or when the metal treatment agent needs to reach a lower depth before being discharged into the molten metal.

[0073] A further advantage of applying the treatment through the rotor head is that the feed rate of the metal treatment is less critical. Traditionally, the feed rate of the wire or cored wire is controlled so that the wire melts at the correct depth. If the wire is fed too slowly, it will melt too high in the molten metal; if it is fed too fast, the wire may contact and damage the lining of the vessel (such as a ladle or furnace) where the treatment is taking place.

[0074] In some embodiments, applying the metal treatment agent includes adding a nodularizing agent to the molten iron. The nodularizing agent can act to control the structure of carbon inclusions in the cast iron. For example, the nodularizing agent includes magnesium. The application of the nodularizing agent produces nodular graphite inclusions in the iron, which improves the impact and fatigue resistance of the final cast product.

[0075] According to at least one embodiment, an inoculant is applied to molten iron to produce higher quality cast iron. The inoculant functions to form nuclei for iron or carbon crystallization. For example, in ductile iron, a higher amount of inoculant results in more nuclei, a higher nodule count, and better properties for the resulting iron.

[0076] In various embodiments, the inoculant can include or consist of zirconium, manganese, and other similar elements. In some embodiments, the inoculant can include or consist of barium, calcium, and other similar elements. According to at least one embodiment, the improved method includes applying a first metal treatment agent and at least a second treatment agent, where the second metal treatment agent includes an inoculant, preferably zirconium, manganese, barium, calcium, ferrosilicon, or a combination thereof. In one embodiment, the second metal treatment agent includes at least 30% zirconium, preferably at least 50% zirconium.

[0077] Existing ductile iron production methods add magnesium in the form of FeSiMg to spheroidize the graphite and then add an inoculant to induce nucleation. The improved method described herein uses a concentrated inoculant-cored wire that can be introduced into the molten iron while the rotating rotor head stirs the molten iron. This results in the active ingredients of the inoculant being easily dispersed and dissolved within the molten iron. The use of the rotating device 100 has the advantage of allowing the use of a more concentrated inoculant. The method described herein can reduce the amount of nodularizing agent and inoculant required. Therefore, the method described herein provides an environmentally friendly solution requiring fewer transportation and storage resources.

[0078] According to one embodiment, the molten iron is the product of a cupola furnace. As is well understood by those skilled in the art, a cupola furnace (or simply "cupola") is a melting apparatus used in foundries to melt cast iron. According to one embodiment, the molten iron received from the cupola furnace is desulfurized by bubbling at least one of magnesium, calcium, and calcium carbide into the molten iron, then testing the level of sulfur in the molten iron, and then bubbling magnesium into the molten iron to allow the magnesium to act as a nodularizing agent.

[0079] According to one embodiment, applying the metal treating agent to the molten iron includes adding a first metal treating agent (e.g., a nodularizing agent) and at least a second metal treating agent (e.g., an inoculant). According to one embodiment, the first metal treating agent is added to the molten iron through the rotor head 5, and the second metal treating agent is added to the molten iron in the vicinity of the rotating device.

[0080] According to one embodiment, applying a metal treating agent to the molten iron includes adding a first metal treating agent and a second metal treating agent, wherein the first metal treating agent includes barium and the second metal treating agent includes magnesium, and the method further includes adding the magnesium after the barium. In one embodiment, the first metal treating agent includes at least 30% barium. In one embodiment where the barium acts as a deoxidizer (rather than an inoculant), the barium is added to the bottom of the ladle before the rotor or by a wire fed adjacent to the rotor. In one embodiment where the barium acts as a deoxidizer, the barium can be placed at the bottom of a vessel, and then the molten iron can be added to the vessel, and then the molten iron can be stirred by a rotating device to enhance reaction of the barium with the molten iron.

[0081] In one embodiment, the method further includes dispersing argon gas into the molten iron before applying the second treatment agent. The argon gas can act to carry the first treatment agent within the hollow shaft or sleeve. In various embodiments, a gas (e.g., argon gas) is added with the magnesium cored wire or with the powdered magnesium to maintain a positive gas pressure within the rotor hollow and prevent the iron from flowing upward within the rotor.

[0082] In one embodiment, the sleeve comprises carbon. In one embodiment, the sleeve can be made from fused silica. While a sleeve made from fused silica may not require preheating before introducing the sleeve into the molten iron, a sleeve made from fused silica can be used only once and cannot be reused. In various embodiments, the sleeve can be made from any material that is non-reactive with iron and resistant to thermal shock. In some embodiments, the sleeve is preheated (e.g., using one or more burners) before being introduced into the molten metal. In one embodiment, the sleeve is heated to a temperature in the range of approximately 600-800°C. In some embodiments, the sleeve does not need to be preheated, i.e., the sleeve is configured for "cold start." In some embodiments, the sleeve is made from a carbon-bonded material, typically isostatically pressed. In some embodiments, the sleeve may be formed from a clay-graphite material or an alumina-based material. In one embodiment, the sleeve can be used 10, 20, or even 50 times before needing replacement.

[0083] The methods disclosed herein provide for the use of magnesium in a pure form, offering significant cost advantages over the less enriched magnesium (in the form of FeSiMg) used in existing methods. Pure magnesium can react violently with molten metal, but in the improved methods disclosed herein, the rotating rotor breaks the magnesium vapor into fine bubbles that are easily absorbed, and the stirring action of the rotor further promotes absorption of magnesium by the molten iron. The fine bubbles produced by the methods disclosed herein allow for faster absorption of magnesium into the iron, resulting in higher yields and less oxidation.

[0084] The methods disclosed herein can significantly reduce the amount of raw material required for the nodularization process. In one embodiment, the methods disclosed herein can reduce the amount of raw material used in the nodularization process by 70%. The methods disclosed herein can provide a more sustainable approach resulting from reduced transportation and storage resources. The methods disclosed herein can also provide automation of the magnesium addition process. Compared to existing methods, the methods disclosed herein use only one ladle (the same processing ladle can be used for the first stage 400 and the second stage 500). Existing methods require two ladles (a processing ladle and a pouring ladle) and an extra step of transferring the contents of the first ladle to the second ladle.

[0085] In some embodiments, the metal treating agent is added to the surface of the molten metal in the form of a powder. In some such embodiments, the molten metal is agitated with a rotating device so that the powder is mixed into the molten metal and dispersed throughout the molten metal. In some embodiments, the metal treating agent is added in the form of a wire and fed into the molten metal. In some embodiments, the wire is a cored wire including an outer protective sheath, as described with respect to the third aspect above. In some embodiments, the wire is fed into the molten metal with a rotating device.

[0086] In some embodiments, applying the metal treating agent to the molten iron can include adding a first metal treating agent and at least a second treating agent. In some embodiments, the first metal treating agent is added to the molten iron through the rotor head. The second metal treating agent can be added to the molten iron in the vicinity of the rotating device. The second metal treating agent can be added to the molten iron after the first metal treating agent has been added.

[0087] The second metal treatment agent can include any of the treatment agents described herein. In some embodiments, the second metal treatment agent can be an inoculant. The inventors have discovered that by stirring the molten iron, the inoculant can be added in the form of a concentrated cored wire. Therefore, the inoculant can be applied at a higher purity, or in other words, the amount of "carrier" present in the metal treatment agent relative to the active ingredient can be reduced. Inoculants are widely known and are often based on barium or zirconium compounds.

[0088] In some embodiments, the rotating device is particularly suited for stirring high temperature, high density molten metals (eg, iron).

[0089] In some embodiments, the method further includes discharging a gas into the molten metal through the rotor head. In embodiments, the gas includes one or more gases that are insoluble in the molten metal. In embodiments, the gas includes argon, nitrogen, carbon monoxide, or a mixture thereof.

[0090] In some embodiments, the method can further include flowing a gas through the rotor head immediately prior to removing the rotating device from the molten iron. The inventors have found that this can reduce the amount of iron remaining on the rotating device after the process is complete, thereby increasing the life of the rotating device.

[0091] The improved method disclosed herein is suitable for use with any ladle or furnace, including a coreless induction furnace (CIF). In embodiments in which the method is used with a ladle, molten metal can be poured (tapped) into the ladle from a CIF or cupola. The improved method disclosed herein is particularly suitable for processing molten iron, but can also be used to process other molten metals requiring nodularization, inoculation, or desulfurization.

[0092] In some embodiments, the rotating device is rotated at a speed of at least 50 rpm, at least 100 rpm, at least 200 rpm, or at least 300 rpm to agitate the molten metal. In some embodiments, the rotating device is rotated at a speed of 800 rpm or less, 600 rpm or less, 500 rpm or less, 400 rpm or less, or 300 rpm or less to agitate the molten metal. In some embodiments, the rotating device is rotated at a speed of 50-600 rpm, 100-400 rpm, or 200-300 rpm, e.g., 250 rpm. Increasing the rotation speed increases the overall flow rate and the amount of downward flow from the rotor head (i.e., increases bottom agitation), but also increases the amount of air entrained in the molten metal. Increasing the rotation speed above 800 rpm can lead to the creation of vortices, entraining air, which can be released back into the molten metal, potentially causing detrimental effects. In some embodiments, the rotation speed is varied during the course of the method.

[0093] The rotating device may be for treating the molten metal with a gas, the shaft may be hollow, the rotor head may have a gas outlet for releasing the gas into the molten metal, and the hollow shaft may be fluidly connected to the gas outlet of the rotor head.

[0094] The inventors have found that a two-piece rotor including an inner shaft made of a material containing graphite and an outer tubular sleeve and rotor head made of a material with excellent heat resistance has excellent durability and life in high-temperature molten metals such as iron and steel. This embodiment of the rotating device shows little deformation even when repeatedly tested in molten steel, achieving good stirring and purging efficiency. It has been found that the hollow shaft containing graphite exhibits suitable resistance to the high temperatures of molten steel without melting or shattering, and also has a sufficient level of plasticity to be attached to a motor without breaking during use. While not wishing to be bound by theory, an inner shaft made of metal softens too much at the melting temperature of iron / steel, while an inner shaft made of a ceramic material is too brittle to be attached to a motor. The inventors have found that graphite is particularly suitable for the hollow shaft of the present invention. While graphite is typically considered unsuitable for use in molten iron because it may dissolve in molten iron, in the present invention, the hollow shaft containing graphite is protected by the outer tubular sleeve.

[0095] In some embodiments, the tubular sleeve is formed from a refractory substrate coated with alumina and / or magnesium zirconate, metal oxides, or combinations thereof, as well as refractory materials including fused silica, silicon carbide, alumina, carbon-bonded alumina, carbon-bonded ceramics, clay graphite, silicon nitride alumina, isostatically pressed (also known as isopressed) refractory mixtures containing metal oxides, carbides, or nitrides. The rotor head can also be formed from a refractory substrate coated with alumina and / or magnesium zirconate, metal oxides, or combinations thereof, as well as refractory materials including fused silica, silicon carbide, alumina, carbon-bonded alumina, carbon-bonded ceramics, clay graphite, silicon nitride alumina, isopressed refractory mixtures containing metal oxides, carbides, or nitrides. In some embodiments, the tubular sleeve and rotor head are both made from the same material. In other embodiments, the tubular sleeve and rotor head are made from different materials.

[0096] High temperature resistant materials including fused silica, silicon carbide, alumina, carbon-bonded alumina, carbon-bonded ceramics, clay graphite, silicon nitride alumina, isopressed refractory mixtures containing metal oxides, carbides, or nitrides, as well as refractory substrates coated with alumina and / or magnesium zirconate, metal oxides, or combinations thereof, have sufficient corrosion and thermal shock resistance for use in molten iron without degradation or the need for priming.

[0097] In some embodiments, the tubular sleeve and / or rotor head are formed from a refractory material comprising isostatically pressed carbon-bonded alumina, such as the Viso™ refractory material manufactured by Vesuvius Pic. The present inventors have found that rotors made using isopressed carbon-bonded alumina are particularly durable.

[0098] In some embodiments, the rotor head is integrally formed with the tubular sleeve. In other embodiments, the rotor head is a separate piece that is coupled to the end of the tubular sleeve. In such embodiments, the rotor head may be coupled to the end of the tubular sleeve by any suitable means, such as a threaded connection, a push-fit, or the like.

[0099] In some embodiments, the hollow shaft has a first end and a second end, and the first end of the hollow shaft is surrounded by a tubular sleeve. In some embodiments, the second end of the hollow shaft is configured to be coupled to an apparatus (e.g., a motor) for rotating the rotational device. For example, the second end of the hollow shaft can include a pulley configured to be connected to the motor by a V-belt, or the second end of the hollow shaft can be configured to be directly attached to the motor shaft. In some embodiments, the second end of the hollow shaft can be configured to receive a collar configured to be coupled to the motor shaft by other means, such as a flange with a bolt opening, including a collar for a V-belt pulley.

[0100] The length of the hollow shaft may be measured between the first end and the second end. In some embodiments, at least 50%, at least 60%, at least 70%, at least 80%, or at least 90% of the length of the hollow shaft is surrounded by the tubular sleeve. In some embodiments, the hollow shaft is substantially completely surrounded by the tubular sleeve; however, it will be understood that in such embodiments, the tubular sleeve is open near the second end of the hollow shaft, and the second end of the hollow shaft may remain coupled to an apparatus for rotating the rotational device.

[0101] In some embodiments, the first end of the hollow shaft (surrounded by the tubular sleeve) includes a locking portion configured to engage with a complementary receiving portion on the tubular sleeve. The locking portion and receiving portion not only serve to securely fasten the tubular sleeve to the hollow shaft, but also lock the hollow shaft and tubular sleeve against each other, preventing the hollow shaft from rotating independently of the tubular sleeve during use. The complementary receiving portion may be located at the end of the tubular sleeve that includes the rotor head. During use, the tubular sleeve softens, and while the softened tubular sleeve is supported by the internal graphite hollow shaft, some twisting of the rotor may occur. By providing the receiving portion at the end of the tubular sleeve that includes the rotor head, the tubular sleeve will twist less than if it were driven from the end away from the rotor head. It will be understood that the receiving portion does not necessarily have to be at the very end of the tubular sleeve, but may be located away from the very end.

[0102] In several embodiments, the locking portion and the receiving portion have polygonal cross sections. It will be understood that in such embodiments, the locking portion and the receiving portion have the same polygonal cross section, with the locking portion being slightly smaller in diameter to fit snugly within the receiving portion. The edges of the locking portion abut against the edges of the receiving portion, preventing the locking portion from rotating within the receiving portion. In some embodiments, the polygonal cross section includes at least 3, 4, 5, or 6 vertices. Preferably, the polygonal cross section has no more than 12, 11, or 10 vertices. This is so that the angles formed between the edges of the polygon are sufficiently acute to prevent the vertices of the locking portion from sliding between adjacent vertices of the receiving portion. In other embodiments, the locking portion and the receiving portion have circular cross sections with the strings removed.

[0103] The tubular sleeve has a length measured along its longitudinal axis. In some embodiments, the hollow shaft extends within the tubular sleeve along at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, or at least 90% of the length of the tubular sleeve. As such, the hollow shaft may terminate above the rotor head rather than extending into it. In some embodiments, the hollow shaft extends within the tubular sleeve along substantially the entire length of the tubular sleeve, with the first end of the hollow shaft located directly adjacent to the rotor head. Also, in some embodiments, when the hollow shaft does not extend substantially the entire length of the tubular sleeve and the first end of the hollow shaft is not directly adjacent to the rotor head, the tubular sleeve may include a conduit or bore fluidly connecting the hollow shaft to a gas outlet of the rotor head.

[0104] In some embodiments, the second end of the hollow shaft can be secured to the tubular sleeve by a clamping means. The rotor head can be of any suitable shape or form for stirring the molten metal.

[0105] In some embodiments, the rotor head includes a flat surface (i.e., plate) extending perpendicular to the longitudinal axis of the tubular sleeve and a plurality of vanes projecting from the flat surface in a direction generally parallel to the longitudinal axis of the tubular sleeve. In such embodiments, a bore may be included in the flat surface. In some embodiments, the bore is located at the center of the flat surface. In some embodiments, the rotor head includes a second flat surface (i.e., plate) disposed opposite the first flat surface and connected to the first flat surface by a plurality of vanes or pillars. Such embodiments may also include vanes projecting from a base of the second plate. The plate may be generally circular or polygonal in shape, such as rectangular. In some embodiments, the plate may be generally rectangular in shape with concave edges and truncated corners.

[0106] It has been found that single-plate rotor head structures are easier to manufacture using pressing techniques (e.g., using materials such as isopressed carbon-bonded alumina) than double-plate structures. Although double-plate rotor head structures can be manufactured using pressing techniques, it has been found that complete densification of the entire rotor head cannot always be achieved. The single-plate rotor head structure may increase the amount of downward flow from the rotor head, while the double-plate rotor head structure may increase the amount of sideways flow from the rotor head.

[0107] The hollow shaft and tubular sleeve may be coupled by a friction fit. Other coupling means or mechanisms may also be used. In some embodiments, a tubular sleeve is provided for use with the rotation devices described herein.

[0108] The tubular sleeve can be formed from a refractory material that is insoluble in iron. The tubular sleeve can also be formed from a graphite-free refractory material such as fused silica. For example, the tubular sleeve can be formed from refractory materials including silicon carbide, alumina, carbon-bonded alumina, carbon-bonded ceramic, clay graphite, silicon nitride alumina, isopressed refractory composites including metal oxides, carbides, or nitrides, or refractory substrates coated with alumina and / or magnesium zirconate or metal oxides, or combinations thereof.

[0109] In some embodiments, the tubular sleeve includes an integrally formed rotor head at one end, the rotor head including the gas outlet, while in other embodiments, the tubular sleeve includes means, such as thread means, for coupling to a separate rotor head at one end.

[0110] The tubular sleeve can have a length measured along its longitudinal axis. In some embodiments, the tubular sleeve includes a bore for receiving the hollow shaft, the bore extending through the interior of the tubular sleeve along at least 30%, at least 40%, at least 50%, at least 60%, at least 70%, at least 80%, or at least 90% of the length of the tubular sleeve. In some embodiments, the bore for receiving the hollow shaft extends through the interior of the tubular sleeve along substantially the entire length of the tubular sleeve. In embodiments in which the bore for receiving the hollow shaft does not extend through the interior of the tubular sleeve along substantially the entire length of the tubular sleeve, the tubular sleeve can further include a conduit or bore for fluidly connecting the bore for receiving the hollow shaft to a gas outlet of the rotor head or a means for coupling to the rotor head.

[0111] In embodiments, the tubular sleeve includes a receiving portion configured to engage a complementary locking portion on the hollow shaft. In some embodiments, the receiving portion has a polygonal cross-section. In some embodiments, the polygonal cross-section includes at least 3, 4, 5, or 6 vertices. In some embodiments, the polygonal cross-section includes 12, 11, or 10 or fewer vertices. In other embodiments, the locking portion and receiving portion have a circular cross-section with the string removed.

[0112] It will be understood that any features or embodiments described in relation to the rotor may equally be applied to the tubular sleeve, and vice versa.

[0113] 1 and 2 illustrate a rotation device 100 according to one embodiment of the present invention. The rotation device 100 includes a tubular sleeve 1 and a hollow shaft 3 extending within the tubular sleeve 1. The tubular sleeve 1 has a rotor head 5 integrally formed at one end. The rotor head 5 is of standard double-plate construction and includes a first planar surface, such as a first plate 7, and a second plate 9, each extending perpendicular to the longitudinal axis of the tubular sleeve 1. The first plate 7 and the second plate 9 are connected to each other by a plurality of pillars 11. The rotor head 5 further includes an outlet 13 for releasing gas into the molten metal, the outlet being in the form of a bore extending through the first plate 7.

[0114] The hollow shaft 3 includes a first end 15 and a second end 17, with the first end 15 enclosed within the tubular sleeve 1. The hollow shaft 3 further includes a bore 19 extending therethrough (shown in FIG. 3). The tubular sleeve 1 includes a conduit 21 fluidly connecting the bore 19 of the hollow shaft 3 to the gas outlet 13 of the rotor head 5 so that gas and / or solid metal treating agents flow through the hollow shaft 3, through the rotor head 5 and into the molten metal during use. In some embodiments (not shown), the hollow shaft 3 includes multiple bores extending therethrough so that the gas and solid metal treating agents can be supplied separately through the hollow shaft 3.

[0115] The first end 15 of the hollow shaft 3 includes a locking portion 23 that engages with a complementary receiving portion 25 on the tubular sleeve 1. The cross-sectional shape of the locking portion 23 is circular when six adjacent chords are removed; that is, the cross-section of the locking portion 23 is generally hexagonal. The receiving portion 25 in the tubular sleeve 1 has a corresponding cross-sectional shape, and the edges and apex of the locking portion 23 abut against the receiving portion 25, preventing independent rotation of the hollow shaft 3 within the tubular sleeve 1.

[0116] A second end 17 of the hollow shaft 3 protrudes from the tubular sleeve 1 and is configured to be coupled to an apparatus for rotating the rotating device 100 (e.g., the apparatus shown in FIG. 7 ). In the illustrated embodiment, the second end 17 of the hollow shaft includes a circumferential groove 25 a. The circumferential groove 25 a can function as a pulley for connecting to a motor via a V-belt. Alternatively, the circumferential groove 25 a can be configured to engage with a collar (e.g., as shown in FIG. 6 ), which can act as a pulley for connecting to a motor via a V-belt or as a flange for connecting to a motor shaft by other means, such as a nut and bolt. In the illustrated embodiment, the second end 17 of the hollow shaft 3 further includes a recess 27 for engaging a clamping means (e.g., as shown in FIG. 7 ) that secures the hollow shaft 3 to the tubular sleeve 1.

[0117] The tubular sleeve 1 has a length LA measured along the longitudinal axis of the tubular sleeve 1. The hollow shaft 3 has a length LB measured along the longitudinal axis. The tubular sleeve 1 tapers inwardly along its length from a maximum diameter DA, with the diameter of the tubular sleeve decreasing slightly toward the rotor head 5. The hollow shaft 3 also tapers inwardly along its length from a maximum diameter DB at the first end 15 to a minimum diameter at the second end 17, corresponding to the inner diameter dimension of the tubular sleeve 1. The rotor head has a diameter DC.

[0118] FIG. 5 shows a rotation device 200 according to another embodiment of the present invention. The rotation device 200 includes a tubular sleeve 31 and a hollow shaft 33. The tubular sleeve 31 and the hollow shaft 33 are generally the same as the tubular sleeve 1 and the hollow shaft 3 shown in FIGS. 1 to 4, except that the tubular sleeve 1 includes a rotor head 35 having a single-plate structure. The rotor head 35 includes a flat surface (or plate) 37 extending perpendicular to the longitudinal axis A of the tubular sleeve 31, with vanes 39 protruding from the base of the plate 37. The plate 37 is generally rectangular in shape and has concave edges 41 and truncated corners 43.

[0119] The rotation device 200 includes a clamping means 45 for securing the tubular sleeve 31 to the hollow shaft 33. The rotation device 200 further includes a collar 47 that fits around the second end of the hollow shaft 33. The collar includes a flange 49 configured to couple the rotation device 200 to a rotation apparatus (e.g., shown in FIG. 7).

[0120] Figure 6 is a cross-sectional view of the rotation device 200 shown in Figure 5. A first end of the hollow shaft 33 is enclosed within the tubular sleeve 31 and includes a locking portion 51 that engages a complementary receiving portion 53 in the tubular sleeve 31. A bore 55 extends through the hollow shaft 33 and is fluidly connected by conduits 59, 61 to a gas outlet 57 of the rotor head 35.

[0121] The second end of the hollow shaft 33 includes a circumferential groove 63 which engages the collar 47. A clamping means 45 cooperates with the collar 47 to secure the tubular sleeve 31 to the hollow shaft 33.

[0122] 7 shows a rotating device 300 according to one embodiment of the present invention assembled with an apparatus 302 for rotating the rotating device 300 and for injecting gases and / or metal treatment agents into the molten metal through the rotating device 300. In use, the rotating device 300 is lowered into a ladle 304 (or furnace). The ladle 304 can be filled with molten metal either before or after the rotating device 300 is lowered therein. The rotating device 300 is then used to process the molten metal, for example, using a method according to the present invention.

[0123] Example 1 A rotary device according to one embodiment of the present invention was fabricated, comprising a hollow shaft comprising graphite and a tubular sleeve comprising fused silica. The tubular sleeve includes an integrally formed rotor head. The length of the tubular sleeve measured along the longitudinal axis is 123 cm (not including the rotor head). The graphite shaft extends within the tubular sleeve along 100 cm of its length. The graphite shaft has a maximum diameter of 7.6 cm. The tubular sleeve has a maximum diameter of 11.6 cm and a wall thickness of 1.6 cm.

[0124] The rotor head is of standard double-plate construction, consisting of two parallel rectangular plates with concave edges and truncated corners, connected by four pillars. The first plate has a central bore for releasing gases into the molten metal. The plates are 25 cm in diameter.

[0125] The rotating device was successfully used to process molten metal. After repeated use, slight softening of the fused silica caused some warping and distortion of the rotor head, reducing mixing efficiency.

[0126] <Example 2> Another rotational device according to an embodiment of the present invention was fabricated, comprising a hollow shaft comprising graphite and a tubular sleeve comprising VISO™ isostatically pressed carbon-bonded alumina. The dimensions of the rotational device were the same as those of the rotational device in Example 1.

[0127] The rotating device of Example 2 is an improved rotor head structure including a single plate and vanes. The plate is generally rectangular in shape with concave edges and truncated corners, with each corner having four vanes extending from the bottom surface of the plate. The plate has a central bore for releasing gas into the molten metal. The plate has a diameter of 25 cm.

[0128] The rotating device of Example 2 was used 18 times to process molten metal without any signs of deformation and with minimal wear. The graphite shaft was able to be used further with a replaced outer sleeve because it showed no signs of failure. The graphite shaft was found to be capable of at least 50 failure-free uses.

[0129] Flow pattern simulation was performed using OpenFoam™ software to compare the flow velocity and flow direction of the single-plate rotor and the double-plate rotor in molten steel at various rotational speeds. The results are shown in Figures 8-10.

[0130] Figure 8 shows the velocity fields for the double-plate rotor (a) and the single-plate rotor (b) after 15 seconds of rotation at 600 rpm, and Figure 9 shows the scaled flow patterns. Both configurations achieved similar peak flow velocities. However, the flow direction was slightly different: the outlet flow from the double-plate rotor was mostly horizontal, while the single-plate configuration exhibited more downward flow. Both rotor configurations demonstrated good simulated stirring performance in the molten steel, although the single-plate rotor exhibited slightly higher torque than the double-plate rotor (235 N.m vs. 271 N.m).

[0131] Figure 10 shows the velocity field and scaled flow patterns after rotating the single-plate rotor at (a) 100 rpm, (b) 200 rpm, and (c) 300 rpm for 15 seconds. The mixing performance was shown to improve with increasing rotation speed.

Claims

1. 1. A method for treating molten iron, comprising: adding a wire or cored wire containing a metal treatment agent into molten iron, the metal treatment agent including a nodularizing agent; stirring the molten iron using a rotating device (100, 200) including a tubular sleeve (1, 31) and a rotor head (5, 35) provided at one end of the tubular sleeve (1, 31); It contains the rotor head (5, 35) includes at least one flat surface extending in a direction perpendicular to the longitudinal axis of the tubular sleeve (1, 31) and a plurality of vanes projecting from the flat surface in a direction substantially parallel to the longitudinal axis of the tubular sleeve (1, 31), the rotor head (5, 35) including an outlet for adding the wire or cored wire into molten iron; The wire or cored wire is applied through the rotor head (5, 35). A method for processing molten iron.

2. The method of claim 1, wherein the metal treatment agent contains at least 50%, preferably at least 90%, more preferably at least 95% magnesium.

3. adding said metal treatment agent during said stirring, thereby causing said metal treatment agent to bubble through the molten iron; producing spheroidal graphite iron (SGI) or compacted graphite iron (CGI), also known as ductile iron, from the molten iron; 3. The method of claim 1 or claim 2, comprising:

4. The rotation device comprises: a shaft (3, 33) extending through said tubular sleeve (1, 31), at least a portion of said shaft (3, 33) being surrounded by said tubular sleeve (1, 31); The tubular sleeve (1, 31) is made of a heat-resistant material that is resistant to corrosion and thermal shock, The shaft (3, 33) is made of a material including graphite, 4. A method according to any one of claims 1 to 3, wherein the shaft is a hollow shaft (3, 33) and the wire or cored wire is added to the molten iron through the hollow shaft.

5. receiving the molten iron from a cupola furnace; The method includes desulfurizing molten iron by bubbling at least one of magnesium, calcium, and calcium carbide through the molten iron, then testing the sulfur level in the molten iron, and then bubbling magnesium through the molten iron to act as a nodulizing agent.

5. The method according to any one of claims 1 to 4.

6. 6. The method of any one of claims 1 to 5, further comprising discharging gas into the molten iron through the rotor head (5, 35).

7. A method according to any one of claims 1 to 6, wherein the cored wire comprises an outer sheath comprising a high melting point metal and an inner core comprising the metal treatment agent, and the metal treatment agent further comprises calcium, calcium carbide, cerium, ferrosilicon magnesium, or a combination thereof.

8. A method according to any one of claims 1 to 7, wherein a second metal treatment agent separate from the metal treatment agent is added to the molten iron in the vicinity of the rotating device (100, 200).

9. 9. The method of claim 8, wherein the second metal treatment agent comprises an inoculant, preferably zirconium, manganese, barium, calcium, ferrosilicon, or a combination thereof.

10. A method according to either claim 8 or claim 9, wherein the metal treatment agent comprises magnesium and the second metal treatment agent comprises barium, and the method further comprises adding the second metal treatment agent and then adding the metal treatment agent.

11. 11. The method of any of claims 8 to 10, further comprising sparging argon gas into the molten iron before adding the second metal treatment agent.

12. 12. The method according to any one of claims 8 to 11, wherein the second metal treatment agent comprises at least 30% zirconium, preferably at least 50% zirconium, and / or the second metal treatment agent comprises at least 30% barium.

13. 10. The method of claim 4 or any claim dependent thereon, wherein the rotor head (5, 35) is integrally formed with the tubular sleeve (1, 31) or the rotor head (5, 35) is connected to an end of the tubular sleeve (1, 31).

14. 10. The method of claim 4 or any claim dependent on claim 4, wherein the hollow shaft (3, 33) has a first end and a second end, the first end being surrounded by the tubular sleeve (1, 31), and the second end of the hollow shaft (3, 33) is configured to be coupled to an apparatus for rotating the rotating device (100, 200).

15. A method as described in claim 4 or any claim dependent on claim 4, wherein the hollow shaft (3, 33) is connected to the outlet.

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