Apparatus and method for preparing an additive for cast iron

Abstract

The application provides a preparation device and method of cast iron additive, and relates to the technical field of cast iron. The preparation device comprises a feeding container and a reaction container arranged in sequence from top to bottom. The bottom of the reaction container is provided with a reaction pit. The reaction pit is used for placing a composite ingot. The composite ingot comprises an inner ingot and a shell wrapping the inner ingot (the inner ingot is iron material, and the shell is magnesium material). One side of the shell is provided with an opening. The device is used for preparing the cast iron additive (including spheroidizing agent, vermicularizing agent or spheroidizing wire core material), and the preparation is safer and more environmentally friendly. The production efficiency is improved. Compared with the traditional "magnesium pressing method", the mechanical magnesium pressing is not needed in the production process. The loss of the main raw material magnesium is reduced. The process is simplified. The loss and production cost are reduced. The dangerous source is reduced. The fluctuation factor affecting the product quality is reduced. The magnesium oxide content of the cast iron additive prepared by the device is low. The product is uniform and has good quality.

Description

Technical Field

[0001] This invention relates to the field of cast iron technology, and in particular to an apparatus and method for preparing additives for cast iron. Background Technology

[0002] The foundry industry is one of the basic industries, and its products cover military, civilian, aerospace, railway, automobile, power equipment, infrastructure, and various industrial and agricultural machinery manufacturing. Castings are divided into non-ferrous castings and ferrous castings, with ferrous castings further subdivided into cast iron castings and cast steel castings.

[0003] Cast iron typically contains 2-4% carbon, with most of the carbon in the castings at room temperature existing as graphite in various forms. Based on these different graphite forms, cast iron is subdivided into ductile iron, gray cast iron, and vermicular graphite cast iron, among others. The production process of ductile iron inevitably involves spheroidizing agents, spheroidizing lines, and spheroidizing processes, typically added at levels between 0.7-1.5 wt%. These are the core additives and processes that determine the performance of ductile iron. Similarly, the production process of vermicular graphite cast iron uses vermicularizing agents, added at levels between 0.3-0.5 wt%, which are also core additives and processes that determine the performance of vermicular graphite cast iron.

[0004] The methods for producing spheroidizing agents, vermicularizing agents, and spheroidized wire core materials are similar and are collectively referred to as methods for producing (broadly defined) spheroidizing agents. Currently, there are two main methods for producing spheroidizing agents: the molten magnesium method and the pressing magnesium method. Each method has its advantages and disadvantages, but both have many unresolved problems. The molten magnesium method is relatively more efficient and less dangerous than the pressing magnesium method, but it is still very dangerous, causes severe pollution, and results in large fluctuations in product quality, especially in magnesium content. It also leads to significant magnesium loss, requires highly skilled operators, and poses considerable risks. Furthermore, it is impossible to remove slag from the product, resulting in a high impurity content. The pressing magnesium method offers more stable quality than the molten magnesium method, with relatively less magnesium loss and waste, but it is also highly polluting, inefficient, and has an even higher risk factor. There is still room for improvement in quality and waste reduction. Developing a safe, efficient, and high-quality spheroidizing agent production process has become an urgent technical challenge. Summary of the Invention

[0005] The purpose of this invention is to provide an apparatus and method for preparing additives for cast iron. The apparatus provided by this invention is used to prepare additives for cast iron (including spheroidizing agents, vermicularizing agents or spheroidized wire core materials), which has the characteristics of safety, high efficiency and good quality.

[0006] To achieve the above objectives, the present invention provides the following solution:

[0007] This invention provides an apparatus for preparing additives for cast iron, the additives for cast iron including spheroidizing agents, vermicularizing agents or spheroidizing wire core materials, including a feeding container and a reaction container arranged sequentially from top to bottom, the feeding container being located at the top opening of the reaction container;

[0008] The feeding container includes a enclosure, a bottom plate, a first baffle, and a second baffle. The edge of the bottom plate, both ends of the first baffle, and both ends of the second baffle are respectively sealed to the inner wall of the enclosure. A material leakage hole is provided on the bottom plate. The second baffle is located between the first baffle and the material leakage hole. There is a gap between the bottom end of the first baffle and the bottom plate. The bottom end of the second baffle is sealed to the bottom plate, and the top end of the second baffle is lower than the top end of the enclosure.

[0009] The bottom of the reaction vessel is provided with a reaction pit, the top of the reaction pit and the inner wall of the reaction vessel form an arc-shaped concave surface, and the arc-shaped concave surface is located directly below the leakage hole;

[0010] The reaction pit is used to place a composite ingot block, which includes an inner ingot block and a shell that encloses the inner ingot block. The inner ingot block is made of iron and the shell is made of magnesium. The shell has an opening on one side, which exposes the inner ingot block.

[0011] Preferably, the bottom of the feed container is provided with a plug-in tube, which is inserted into the top opening of the reaction container and the plug-in tube matches the top opening of the reaction container.

[0012] Preferably, the top of the first baffle is flush with the top of the enclosure.

[0013] Preferably, the composite ingot is made by an ingot preparation mold, the ingot preparation mold includes an ingot container, the ingot container has a receiving cavity with an open top, and a boss is provided in the middle of the bottom surface of the receiving cavity, and there is a gap between the bottom edge of the boss and the inner sidewall of the receiving cavity.

[0014] This invention provides a method for preparing an additive for cast iron, wherein the additive includes a spheroidizing agent, a vermicularizing agent, or a spheroidizing wire core material, and the preparation apparatus described above includes the following steps:

[0015] A composite ingot is placed in the reaction pit. The composite ingot includes an inner ingot and a shell that encloses the inner ingot. The inner ingot is made of iron and the shell is made of magnesium. The shell has an opening on one side, which exposes the inner ingot.

[0016] Molten ferrosilicon is fed into the feeding container. The molten ferrosilicon passes through the first baffle and the second baffle in sequence, and enters the reaction container through the leakage hole and the arc-shaped concave surface to react with the composite ingot to obtain alloy liquid.

[0017] After the alloy liquid is discharged, it is cooled and solidified to obtain the additive for cast iron.

[0018] Preferably, the mass content of Si element in the ferrosilicon liquid is 40-78%, and the temperature of the ferrosilicon liquid is 1250-1350℃.

[0019] Preferably, the molten ferrosilicon is poured into the feeding container from a transfer bag. The transfer bag is a container with a slag baffle plate on its top plate and a discharge port on its top. The slag baffle plate is close to the discharge port, and there is a discharge channel between the bottom end of the slag baffle plate and the inner wall of the transfer bag for the material in the transfer bag to flow to the discharge port.

[0020] Preferably, the iron material is steel, cast iron, or pig iron, and the magnesium material is metallic magnesium or magnesium alloy.

[0021] Preferably, the additive for cast iron comprises the following components in weight percentage: Si 30~50%, Mg 3.5~35%, RE 0~10%, Ba 0~5%, Ca 0~5%, Al 0~2%, and Fe balance; wherein RE is rare earth.

[0022] This invention provides an apparatus for preparing additives for cast iron, which has the following advantages compared with the prior art:

[0023] A composite ingot is placed in the reaction pit of the preparation device provided by the present invention. The composite ingot includes an inner block and a shell (the inner block is made of iron and the shell is made of magnesium) surrounding the inner block. When the molten ferrosilicon used to prepare the additive for cast iron flows into the reaction pit, the two metals in the composite ingot, namely the inner block and the magnesium (or magnesium alloy) shell, can react with the molten ferrosilicon at the same time (the shell of the composite ingot has an opening on one side). The two metals are heated at the same time, and the temperature difference between the inside and outside is not too large, avoiding some unnecessary reactions and enabling more uniform formation of each alloy phase. This is something that cannot be achieved in traditional spheroidizing agent production methods (such as the molten magnesium method and the pressing magnesium method).

[0024] Another advantage of composite ingots is that the overall density of the ingots is greater than or equal to that of molten ferrosilicon. This allows the composite ingots to sink to the bottom of the molten alloy, while the magnesium metal on the surface liquefies and vaporizes before floating to the surface. During this rising process, the ingots react with the molten ferrosilicon alloy instead of floating on the surface and vaporizing. Furthermore, the vaporization and explosion reaction during the rising process also stirs the molten alloy in the reaction vessel, starting from the bottom, which further promotes the absorption of magnesium.

[0025] The preparation apparatus provided by this invention is used to prepare additives for cast iron. The entire reaction process only involves the time it takes for molten ferrosilicon to flow into the reaction vessel, which varies from 1 to 3 minutes depending on the size of the reaction vessel. The reaction between the magnesium-containing composite ingot and the high-temperature molten ferrosilicon is also within this time, which is much shorter than the smelting time of magnesium melting. Moreover, the feed container increases the gas pressure inside the reaction vessel, improving the absorption rate and absorption rate of magnesium. It also enables production and reaction at relatively low temperatures, further reducing the intensity of magnesium reaction and gasification loss. Furthermore, the entire process is free from human intervention and influencing factors, and is not affected by individual operating skills or proficiency.

[0026] After the molten ferrosilicon is poured into the feeding container, it passes under the first baffle and over the second baffle. When the liquid level is high, the slag will be blocked by the first baffle, and when the liquid level is low, the slag will be blocked by the second baffle. After passing through multiple slag-blocking and slag-avoiding processes, the molten ferrosilicon flowing into the reaction vessel is relatively much purer, which further improves the product quality and stability.

[0027] The entire preparation device can be set up in a separate, safe area with convenient access to environmentally friendly dust removal facilities. Throughout the reaction process, staff can stay away from hazardous sources, high-temperature heat sources, and pollution sources. Meanwhile, the magnesium vapor and white smoke generated can be effectively treated by the environmentally friendly dust removal facilities, thus balancing safety and environmental protection.

[0028] Therefore, the preparation device provided by the invention is safe, produces little pollution, is highly efficient, produces clean alloy liquid, and the resulting cast iron additives have stable quality and high grade. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of the transfer bag in the apparatus for preparing the additive for cast iron according to the present invention;

[0030] Figure 2 This is a schematic diagram of the structure of the feed container and reaction vessel in the apparatus for preparing the additive for cast iron according to the present invention. Figure 1 ;

[0031] Figure 3 This is a schematic diagram of the ingot preparation mold in the apparatus for preparing additives for cast iron according to the present invention. Figure 1 ;

[0032] Figure 4 This is a schematic diagram of the ingot preparation mold in the apparatus for preparing additives for cast iron according to the present invention. Figure 2 ;

[0033] Figure 5 for Figure 4 A magnified view of a section at point A in the middle;

[0034] Figure 6This is a schematic diagram of the structure of the feed container and reaction vessel in the apparatus for preparing the additive for cast iron according to the present invention. Figure 2 ;

[0035] Figure 7 This is a schematic diagram of transferring molten ferrosilicon to a feed container and a reaction vessel using a transfer bag;

[0036] Figure 8 This is a schematic diagram of the structure of the ingot disc in this invention. Figure 1 ;

[0037] Figure 9 This is a schematic diagram of the structure of the ingot disc in this invention. Figure 2 ;

[0038] Figure 10 Scanning electron microscope (SEM) metallographic image of the spheroidizing agent prepared in Example 1;

[0039] Figure 11 The scanning electron microscope (SEM) metallographic image and energy dispersive spectroscopy (EDS) results of the spheroidizing agent prepared in Example 1 are shown below.

[0040] Figure 12 for Figure 11 Enlarged view of the energy spectrum detection result at point 8.1 in the middle;

[0041] Figure 13 for Figure 11 Enlarged view of the energy spectrum detection results at point 8.2 in the middle;

[0042] Figure 14 for Figure 11 Enlarged view of the energy spectrum detection results at point 8.3 in the middle;

[0043] Figure 15 for Figure 11 Enlarged view of the energy spectrum detection results at point 8.4 in the middle;

[0044] Figure 16 for Figure 11 Enlarged view of the energy spectrum detection results at point 8.5 in the middle;

[0045] Figure 17 for Figure 11 Enlarged view of the energy spectrum detection results at position 8.6 in the middle;

[0046] Figure 18 This is a comparison chart showing the production of spheroidizing agents using different processes in the examples. Figure 18 In the image, (a) is the slag produced by the molten magnesium method for producing spheroidizing agents, and (b) is the spheroidizing agent ingot produced in Example 1;

[0047] In the picture:

[0048] 1. Transfer bag; 101. Discharge port; 102. Slag baffle; 103. Discharge channel;

[0049] 201. Enclosure section; 202. Insertion tube; 203. First baffle; 204. Second baffle; 205. Material leakage hole; 206. Base plate;

[0050] 3. Reaction vessel; 301. Arc-shaped concave surface; 302. Reaction pit; 304. Reaction cavity;

[0051] 4. First release agent layer; 5. Ingot container; 6. Boss; 7. Inner insert; 8. Shell; 9. Second release agent layer; 10. Melt inside the reaction vessel; 11. Ingot tray; 12. Composite ingot. Detailed Implementation

[0052] The purpose of this invention is to provide an apparatus and method for preparing additives for cast iron, so as to solve the problems existing in the prior art and improve the preparation efficiency, safety and product quality of additives for cast iron (including spheroidizing agents, vermicularizing agents or spheroidized wire core materials).

[0053] To make the above-mentioned objects, features and advantages of the present invention more apparent and understandable, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0054] like Figures 1 to 9 As shown, this embodiment provides an apparatus for preparing additives for cast iron, including a feed container and a reaction container 3 arranged sequentially from top to bottom, with the feed container located at the top opening of the reaction container 3.

[0055] In this invention, the feeding container (referred to as the reaction cover in this embodiment) includes a containment portion 201, a bottom plate 206, a first baffle 203, and a second baffle 204. The edge of the bottom plate 206, both ends of the first baffle 203, and both ends of the second baffle 204 are respectively sealed to the inner wall of the containment portion 201. A leakage hole 205 is provided on the bottom plate 206. The second baffle 204 is located between the first baffle 203 and the leakage hole 205. There is a gap between the bottom end of the first baffle 203 and the bottom plate 206. The bottom end of the second baffle 204 is sealed to the bottom plate 206, and the top end of the second baffle 204 is lower than the top end of the containment portion 201.

[0056] In this invention, the area of ​​the first baffle 203 away from the second baffle 204 is called the water inlet zone, and the area above the second baffle 204 is called the water outlet zone. The vertical length of the first baffle 203 exceeds half the height of the water outlet zone and the water inlet zone, but is less than 80% of the height of the water outlet zone and the water inlet zone. The top of the second baffle 204 is higher than the bottom of the first baffle 203. In use, the material is injected into the feed container from the water inlet zone. After passing through the gap between the first baffle 203 and the bottom plate 206 and the water outlet zone, the material falls into the reaction vessel 3 through the discharge hole 205. The first baffle 203 blocks the slag impurities at higher positions in the material, and the second baffle 204 blocks the slag impurities at lower positions in the material. Therefore, the first baffle 203 is also called the upper slag baffle, and the second baffle 204 is also called the lower slag baffle.

[0057] In an optional embodiment, a preferred embodiment is provided with a connector 202 at the bottom of the feed container. The connector 202 is inserted into the top opening of the reaction container 3, and the connector 202 matches the top opening of the reaction container 3. In this invention, the connector 202 is used to support the feed container on the reaction container.

[0058] In the optional embodiments of this example, it is more preferred that the top end of the first baffle 203 is flush with the top end of the enclosure 201.

[0059] In this invention, the reaction container 3 (referred to as the reaction pack in this embodiment) preferably uses a heat-insulating lining for the reaction pack wall (including the side wall and the bottom plate) to prevent the temperature inside the reaction container from dropping too quickly. At the same time, the inner wall is made of refractory material to prevent molten silicon from sticking to the wall.

[0060] In this invention, a reaction pit 302 is provided at the bottom of the reaction container 3; the top of the reaction pit 302 forms an arc-shaped concave surface (also called a slow-flow groove) with the inner wall of the reaction container, and the arc-shaped concave surface is located directly below the discharge hole; the function of the arc-shaped concave surface 301 is to buffer the material (such as molten ferrosilicon) falling into the reaction container 3 through the discharge hole 205, so as to avoid turbulence and splashing.

[0061] In this invention, the total volume of the inner cavity of the reaction vessel 3 (referred to as the reaction cavity 304 in this embodiment) is preferably 120-130% of the volume of all reactants used to prepare the additive for cast iron. The ratio of the height of the inner cavity of the reaction vessel 3 to the average diameter of the inner cavity (excluding the diameter of the reaction pit 302) is preferably 1.5-2, i.e., "height:diameter = 1.5-2:1". The volume of the reaction pit 302 preferably accounts for 15-20% of the total volume of the reaction vessel.

[0062] In this invention, the reaction pit 302 is used to place the composite ingot 12, which includes an inner ingot 7 and a shell 8 enclosing the inner ingot 7. The inner ingot 7 is made of iron, and the shell 8 is made of magnesium. One side of the shell 8 has an opening that exposes the inner ingot 7 (even if a portion of the inner ingot 7 is in contact with the outside). The opening is preferably located at the top of the composite ingot. As an optional embodiment, the composite ingot can be cubic, or designed as a cuboid, sphere, hemisphere, or other shapes; the opening is preferably a regular square frustum. As an optional embodiment, the iron material is preferably steel, cast iron, or pig iron, and the magnesium material is preferably metallic magnesium or magnesium alloy.

[0063] In this embodiment, the composite ingot 12 is preferably made by an ingot preparation mold. The ingot preparation mold includes an ingot container 5, which has a receiving cavity with an open top. A boss 6 is provided in the middle of the bottom surface of the receiving cavity, and there is a gap between the bottom edge of the boss 6 and the inner sidewall of the receiving cavity. As an optional embodiment, the receiving cavity can be in the shape of a cube, cuboid, sphere, hemisphere, or other shapes; the boss 6 is a regular square frustum.

[0064] As an optional embodiment, the ingot preparation mold can be made of one or a combination of heat-resistant steel, cast iron, cast steel, graphite, and refractory bricks. Considering the influence of the mold on the quality of the composite ingot, a composite structure of an outer layer of heat-resistant steel and an inner layer of graphite is optimal.

[0065] In the optional embodiments of this example, the receiving cavity is preferably cubic in shape. In the optional embodiments of this example, the boss 6 is preferably a regular square frustum. The function of the boss 6 is twofold: firstly, to allow the composite ingot to form an enclosing or semi-enclosing structure; and secondly, to form a notch on the composite ingot to facilitate contact between the molten ferrosilicon and the inner insert 7 when poured.

[0066] As an optional solution in this embodiment, the preferred method for preparing the composite ingot is as follows:

[0067] A first release agent layer 4 (refer to) is uniformly applied to the inner side of the ingot preparation mold. Figure 5 ), dry and set aside for later use;

[0068] An inner insert 7 is placed on the boss 6, and then molten magnesium metal or molten magnesium alloy is injected into the mold cavity and cooled to obtain a composite ingot.

[0069] In this invention, the first release agent layer 4 can be made of graphite-based materials, silicon-based materials, or mixed materials. The graphite-based release agent is obtained by uniformly mixing graphite powder with a solvent (water or organic solvent) and a binder (such as resin or sodium silicate), and is then uniformly applied to the inner side of the ingot preparation mold. In this invention, when steel is selected as the inner insert 7, it can be processed according to the design size standard or made into small briquettes of scrap steel; when cast iron is selected as the inner insert 7, it can be mass-produced; when pig iron is selected as the inner insert 7, pig iron blocks from a pig iron plant that meet the design standards can be directly selected.

[0070] In this embodiment of the invention, the assembly process of the preparation device is as follows: the composite ingot 12 is calculated to the corresponding weight according to the design composition of the additives for cast iron (described below), and placed in the reaction pit 302; then, the feeding container is covered, and the discharge hole 205 is aligned with the arc-shaped concave surface 301; the assembled device is placed in a separate reaction area for convenient and safe operation and configuration of environmental protection dust removal equipment. During the production reaction, both personnel safety and comfort are ensured, while also taking into account environmental protection, dust removal, and smoke removal.

[0071] This invention provides a method for preparing an additive for cast iron, wherein the additive includes a spheroidizing agent, a vermicularizing agent, or a spheroidizing wire core material, and the preparation apparatus described above includes the following steps:

[0072] A composite ingot 12 is placed in the reaction pit 302. The composite ingot 12 includes an inner ingot 7 and a shell 8 that encloses the inner ingot 7. The inner ingot 7 is made of iron and the shell 8 is made of magnesium. The shell 8 has an opening on one side, which exposes the inner ingot 7.

[0073] Molten ferrosilicon is fed into the feeding container. The molten ferrosilicon passes sequentially through the first baffle 203 and the second baffle 204, and enters the reaction container 3 through the leakage hole and the arc-shaped concave surface 301 of 205, where it reacts with the composite ingot 12 to obtain an alloy liquid.

[0074] After the alloy liquid is discharged, it is cooled and solidified to obtain the additive for cast iron.

[0075] In this invention, the additives for cast iron include spheroidizing agents, vermicularizing agents, or spheroidized wire core materials, which are ferrosilicon-based alloy products. Spheroidizing agents and vermicularizing agents are mostly in block form, while spheroidized wire core materials are mostly small-particle powders. The particle size of spheroidizing agents is generally 2-40 mm, and can be further divided into ranges such as 3-10 mm, 3-25 mm, or 4-32 mm. Vermicularizing agents and spheroidizing agents have different compositions but similar appearances, with particle sizes also ranging from 2-40 mm, and can be further subdivided into different particle sizes. The particle size of spheroidized wire core materials is typically 0.2-2 mm. The additives for cast iron are mainly composed of ferrosilicon-magnesium alloys, mostly containing rare earth elements, and other low-content elements include calcium, aluminum, barium, and other elements. In this invention, the additive for cast iron preferably comprises the following components in weight percentage: Si 30~50%, Mg 3.5~35%, RE (rare earth) 0~10%, Ba 0~5%, Ca 0~5%, Al 0~2%, and Fe balance.

[0076] In this invention, the mass content of Si element in the ferrosilicon melt is preferably 40-78%, and the temperature of the ferrosilicon melt is preferably 1250-1350℃. In this invention, the smelting raw materials for the ferrosilicon melt include ferrosilicon and iron materials, depending on the designed composition of the additives for cast iron. They may also include calcium silicon, rare earth ferrosilicon, etc., and the iron materials can be one or more of steel, cast iron, and pig iron.

[0077] In this invention, the composite ingot 12 includes an inner ingot 7 and a shell 8 enclosing the inner ingot 7. The inner ingot 7 is made of iron, and the shell 8 is made of magnesium. The iron is preferably steel, cast iron, or pig iron, and the magnesium is preferably metallic magnesium or magnesium alloy. This invention does not impose any special requirements on the dimensions of the composite ingot 12; adjustments can be made according to actual production conditions.

[0078] In this invention, the compositions of the ferrosilicon liquid and the composite ingot are obtained according to formulas (1) to (5):

[0079] Formula (1),

[0080] Formula (2),

[0081] Formula (3),

[0082] Formula (4),

[0083] Formula (5),

[0084] In formulas (1)~(5),

[0085] D 标液 The density of the molten ferrosilicon;

[0086] Si%: The mass percentage of silicon in the molten ferrosilicon;

[0087] X%: The mass percentage of the inner insert 7 in the composite ingot 12;

[0088] X min %: The minimum mass percentage of the inner insert 7 in the composite ingot 12;

[0089] X max %: The maximum mass percentage of the inner insert 7 in the composite ingot 12;

[0090] D 内 The density of the inlay 7;

[0091] D Mg The density of the shell 8;

[0092] M Fe %: The percentage by mass of all iron materials added to the raw materials used in the preparation of additives for cast iron;

[0093] M Mg %: The percentage by mass of magnesium in the raw materials added to the additives used in the preparation of cast iron;

[0094] D 复块 The average density of the composite ingot 12;

[0095] V x %: Volume percentage of the inner insert 7 in the composite ingot 12;

[0096] X min %≤X%≤X max %, when X min %>X max In extreme cases, take X% = X. max %D 复块 ≥D 标液 .

[0097] The design composition of additives (spheroidizing agents, vermicularizing agents, or spheroidized wire core materials) for cast iron is fixed. The higher the mass percentage (X%) of the inner insert 7, the lower the Fe% content and the higher the Si% content in the ferrosilicon melt, resulting in a lower density of the ferrosilicon melt. Secondly, during the casting process, the density D of the composite ingot 12... 复块 The density D of the molten ferrosilicon must be greater than or equal to that of the molten ferrosilicon. 标液 Furthermore, the density of the inlay block 7 varies depending on the material chosen, and the increase in Fe content from the same material also differs. Therefore, the above variables are interconnected; a change in one variable will affect the others. Thus, each variable is controlled according to the empirical formula (1) and the design formulas (2), (3), (4), and (5).

[0098] The density of molten ferrosilicon is calculated using the empirical formula (1), which is applicable when the Si% content is between 40% and 78% and the temperature of the molten ferrosilicon is between 1250 and 1350℃. The density of molten ferrosilicon differs from that of solid ferrosilicon with the same composition. Based on experience and data calculation, an approximate empirical formula (1) is obtained.

[0099] In this invention, when the composition of the ferrosilicon melt and the composite ingot cannot meet the composition design requirements of the additive for cast iron, an alloy (such as a rare earth ferrosilicon alloy) can be added to the reaction vessel. In this embodiment, it is referred to as "melt material 10 in the reaction vessel". The melt material 10 in the reaction vessel is spread flat and covers the composite ingot 12 in the reaction pit 302, specifically at the opening of the composite ingot. Figure 6 As shown, the composite ingot with an opening facilitates the uniform distribution of the molten material 10 in the reaction pot within the reaction pit 302, so that the molten material 10 in the reaction pot can be melted and absorbed together during the reaction.

[0100] Unlike traditional methods, this invention applies to three different ferrosilicon melting methods. The first is electric furnace melting, which is the most common method in traditional spheroidizing agent production, but the process differs from the traditional method. The ferrosilicon melt, after being melted according to the designed composition, can be poured into transfer bag 1 or directly into the water inlet area of ​​the feeding container. The second is reduction furnace melting: Composite ingots are designed according to the composition range of the ferrosilicon melt produced by the reduction furnace, and then the reaction zone is assembled; the ferrosilicon melt from the reduction furnace gradually flows into transfer bag 1, and then from transfer bag 1 is poured into the water inlet area of ​​the feeding container. The third is duplex melting: The ferrosilicon melt from the reduction furnace is then poured into an electric furnace as needed to further adjust the composition, and then the above steps are repeated. The transfer bag 1 is a container. A baffle plate 102 is provided on the top plate of the transfer bag 1, and a discharge port 101 is provided on the top of the transfer bag. The baffle plate 102 is close to the discharge port 101, and a discharge channel 103 is provided between the bottom end of the baffle plate 102 and the inner wall of the transfer bag 1 to allow the material in the transfer bag 1 to flow to the discharge port 101. In this invention, the bag wall of the transfer bag 1 uses a heat-insulating lining to prevent the temperature inside the reaction bag from dropping too quickly, and the inner wall is made of refractory material to prevent the ferrosilicon liquid from sticking to the wall.

[0101] In this invention, after the molten ferrosilicon enters the transfer bag 1, it is preferably allowed to stand for 3 to 10 minutes, depending on the weight of the molten ferrosilicon in the bag. Specifically, when the weight of the molten ferrosilicon is less than 500 kg, it is preferably allowed to stand for 3 minutes; when the weight of the molten ferrosilicon is 500 kg to 2 tons, it is preferably allowed to stand for 3 to 5 minutes; when the weight of the molten ferrosilicon is 2 tons to 5 tons, it is preferably allowed to stand for 5 to 10 minutes; and when the weight of the molten ferrosilicon is greater than 5 tons, it is preferably allowed to stand for 10 minutes. After standing, the slag and harmful substances produced during smelting will float to the surface of the molten ferrosilicon (impurities with a density greater than that of the molten ferrosilicon will sink to the bottom of the furnace and will not be poured out). Figure 7 As shown, molten ferrosilicon flows out from the discharge port 101 (also known as the pouring nozzle). Most of the slag and harmful substances produced during smelting in the furnace are blocked by the slag baffle plate 102, preventing them from flowing into the reaction vessel in large quantities. This is the first slag-blocking process. This method can avoid most of the slag floating on the surface of the molten ferrosilicon, and there is no need to apply slag remover, which reduces the number of processes and costs, and also avoids the risk of secondary pollution that slag remover may bring. Because molten ferrosilicon is different from molten steel, there is no very effective slag-collecting agent. Traditional processes can only use broken glass and slag-removing tools to slowly remove slag, which is not only inefficient and ineffective, but also easily introduces additional slag or impurities.

[0102] The settled transfer package 1, carrying the molten ferrosilicon, is transferred to the reaction zone. For example... Figure 7 As shown, after the molten ferrosilicon is poured into the water inlet area of ​​the feeding container, due to the principle of communicating vessels, the molten ferrosilicon passes under the first baffle 203, over the second baffle 204, and overflows into the water outlet area. When the liquid level is high, the slag is blocked by the first baffle; when the liquid level is low, the slag is blocked by the second baffle. These are the second and third slag-blocking processes. After passing through these three slag-blocking processes, the molten ferrosilicon flowing into the water outlet area of ​​the feeding container is relatively much purer.

[0103] After the molten ferrosilicon flows into the outlet area of ​​the feed container, it flows into the reaction container 3 through the discharge hole 205 and spreads into the reaction pit 302 along the arc-shaped concave surface 301. The molten ferrosilicon that enters the reaction pit 302 begins to react with the composite ingot 12. The inner insert 7 and the magnesium (or magnesium alloy) shell 8 in the composite ingot 12 can react with the molten ferrosilicon simultaneously (the shell of the composite ingot has an opening on one side), which can more uniformly form various alloy phases. The magnesium (or magnesium alloy) and iron in the inner insert 7 react with the molten ferrosilicon simultaneously. Although the melting / dissolving order and rate are different, they react in basically the same time period and space. The different alloy phases in the produced cast iron additives (including spheroidizing agents, vermicularizing agents, or spheroidized wire core materials) are mutually encapsulated, and the uniformity between the phases is better. Figure 10 and Figure 11 As shown, the spheroidizing agent ultimately forms a complex series of phases, rather than a single phase. Therefore, when the original ferrosilicon melt reacts simultaneously with substances containing both Fe and Mg, it is easier to form a uniformly dispersed phase. This is something that cannot be achieved in traditional spheroidizing agent production methods.

[0104] During the reaction, the addition of a feed container to reaction vessel 3 increases the internal pressure, thereby improving the absorption rate and efficiency of magnesium by the ferrosilicon liquid. This also allows for production and reaction at relatively lower temperatures, further reducing the intensity of the magnesium reaction and vaporization losses. Furthermore, it reduces reaction splashing, providing safety protection and minimizing heat radiation and environmental pollution. The entire reaction zone can be located in a separate, safe area with easily accessible environmental dust control facilities. Throughout the reaction process, workers can remain away from hazardous sources, high-temperature heat sources, and pollution sources. Simultaneously, the magnesium vapor and white smoke generated can be effectively treated by the environmental dust control facilities, achieving a balance between safety and environmental protection.

[0105] After all the molten ferrosilicon has flowed into reaction vessel 3, wait for the reaction inside to calm down slightly, generally within 30 seconds, then open the feed container to discharge the molten alloy from the reaction vessel and allow it to cool and solidify. In this embodiment of the invention, the discharge specifically involves pouring the molten alloy into ingot tray 11. The ingot tray 11 can be made of heat-resistant steel, cast iron, refractory materials, graphite, or composite materials, maximizing the surface area of ​​the molten alloy after pouring. The height of the molten alloy should not exceed 30 mm. The ingot tray 11 does not require heat insulation and needs to dissipate heat quickly. Figure 8 and Figure 9 As shown, the two side walls of the ingot tray 11 are designed to slope outwards with a certain radius (R). A second release agent layer 9 is pre-coated evenly. The material of the second release agent layer 9 can be graphite-based, silicon-based, or a composite solvent. During the cooling and solidification of some components of the alloy liquid, the volume will expand due to the production and precipitation of different phases. The slope of the side walls facilitates demolding. After the alloy in the ingot tray 11 cools to room temperature, it is removed and crushed to obtain the target cast iron additive particles.

[0106] The method for preparing additives for cast iron provided by this invention is safer and more environmentally friendly; it improves production efficiency and optimizes the order of adding raw and auxiliary materials; the molten ferrosilicon produced by the reduction furnace (submerged arc furnace) can be directly used for the production of additives such as spheroidizing agents, shortening the production process and simplifying the production steps, and can also be used in electric furnace production processes; compared with the traditional "magnesium pressing method" production process, the production process of additives such as spheroidizing agents in this invention does not require mechanical magnesium pressing, reducing the loss of the main raw material, metallic magnesium, simplifying the process, reducing losses and production costs, reducing hazardous sources, and reducing factors affecting product quality fluctuations. The cast iron additives prepared using the method of this invention have low magnesium oxide content, uniform product quality, and good product quality.

[0107] To further illustrate the present invention, the apparatus and method for preparing additives for cast iron provided by the present invention will be described in detail below with reference to examples, but these should not be construed as limiting the scope of protection of the present invention.

[0108] According to each embodiment Figure 1 , Figure 2 , Figure 6 , Figure 7 The prepared apparatus shown produces the corresponding additives for cast iron. The composite ingot (cubic in shape, including an inner ingot and a shell enclosing the inner ingot; the inner ingot is made of iron, and the shell is made of magnesium; the top of the shell has a frustum-shaped opening) is made of... Figures 3-5 The ingot was prepared using the mold shown, and the resulting molten alloy was poured into... Figures 8-9 It cools and solidifies in the ingot pan shown.

[0109] Example 1: Production of spheroidizing agents by electric furnace smelting

[0110] Electric furnace smelting was chosen to produce the spheroidizing agent of grade N01. The grade was defined as N01, and the designed composition is shown in Table 1.

[0111] Table 1 Design composition of spheroidizing agent (balance: Fe)

[0112]

[0113] All raw materials except for the composite ingots are added to the electric furnace for smelting. The raw materials for smelting the ferrosilicon liquid are hard 72 ferrosilicon (measured composition Si: 73.28%, Ca: 1.13%, Al: 0.98%), calcium silicon (measured composition Si: 53.76%, Ca: 32.3%), rare earth ferrosilicon (measured composition Si: 52.11%, Ce: 28.5%, La: 4.22%), and scrap steel (Q235 scrap steel); the raw materials used to prepare the composite ingots are metallic magnesium, steel ingots (Q235 steel), ductile iron ingots (QT400 grade), and pig iron (Q10 pig iron).

[0114] Overall logic: X can be calculated according to formula (3). max %, X can be calculated by combining formulas (1), (2) and (4). min %. This allows us to design X%, let X min %≤X%≤X max % is sufficient.

[0115] In this embodiment, the iron element in the raw materials inside the furnace is added as scrap steel, and the iron element in the composite ingot is added as Q10 pig iron.

[0116] Step 1: Input design components:

[0117] 1) Median design composition of the spheroidizing agent: Si: 45%, Mg: 6.3%, RE: 1.0%, Ca: 3.0%, Fe: balance, Al is inherent in the raw materials and will not exceed 1.0%. Note: The Si content is designed at 45% because the furnace body will infiltrate silicon during production, and in continuous production, some ferrosilicon will adhere to the furnace wall from the previous batch. In actual production, the silicon content will be slightly higher than the design value, so the design uses the lower-middle limit.

[0118] 2) Raw material design composition:

[0119] 72% ferrosilicon: Si: 72%, Ca: 1.2%;

[0120] Calcium-silicon ratio: Si: 50%, Ca: 30%;

[0121] Rare earth ferrosilicon: Si: 50%, RE: 30%, Ca: 1.2%;

[0122] Magnesium metal: Mg: 100%, density 1.78 g / cm³ 3 ;

[0123] Scrap steel: Fe: 100%, density 7.8 g / cm³ 3 ;

[0124] Steel ingot: Fe: 100%, density 7.8 g / cm³ 3 ;

[0125] Ductile iron ingot: Fe: 93%, density 7.2 g / cm³ 3 ;

[0126] Pig iron (Q10): Fe: 95%, density 7.1 g / cm³ 3 .

[0127] Step 2: Calculate the ingredient ratios by weight percentage.

[0128] Magnesium addition of 6.83%: When calculating the addition of other raw materials, magnesium is calculated based on the upper limit of 6.5% (not the median); when calculating the addition of magnesium, a 5% margin needs to be added, that is, 6.5% × 1.05 = 6.83%. The reason for the above calculation is that magnesium will undergo a large amount of gasification and oxidation during production, resulting in significant losses. Based on experience, a certain amount of burn-off loss is added.

[0129] Rare earth ferrosilicon addition of 3.33%: spheroidizing agent rare earth content ÷ rare earth content of rare earth ferrosilicon × 100%, 1.0% ÷ 30% × 100% = 3.33%.

[0130] Calcium silicon addition amount 7.64%: When calculating the calcium silicon addition amount, it is necessary to consider that ferrosilicon and rare earth ferrosilicon also contain calcium, as shown in the first step, calculated according to Ca%=1.2%. Here, it is necessary to assume that the total addition amount of ferrosilicon and rare earth ferrosilicon is a single value, for example, 59%. After calculating the addition amount of ferrosilicon, a judgment is made. If the difference is ≤1%, the assumed value is considered valid; if the difference is greater than 1%, a closer value needs to be re-entered for judgment. Calcium silicon addition amount = (3.0% - 1.2% × 59%) ÷ 30% = 7.64%.

[0131] Ferrosilicon addition of 54.88%: When calculating the amount of ferrosilicon (containing 72% silicon), it is necessary to consider that both calcium silicon and rare earth ferrosilicon also contain silicon, as shown in the first step, calculated based on Si%=50%. Ferrosilicon addition = (45%-50%×3.33%-50%×7.64%)÷72%=54.88%. Returning to the previous judgment, 59%-(54.88%+3.33%)=0.79%, which is less than 1%. This indicates that the previously set total addition amount of ferrosilicon and rare earth ferrosilicon at 59% is appropriate.

[0132] Iron-containing raw material addition amount 27.65%: The remainder is all iron-containing raw material. Mg is calculated as 6.5%, and burn loss compensation is not considered. Iron-containing raw material addition amount = 100% - 6.5% - 3.33% - 7.64% - 54.88% = 27.65%. This iron-containing raw material consists of two main parts: one is the scrap steel added to the electric furnace, and the other is the inserts within the composite ingot.

[0133] Summary of ingredient proportions: Ferrosilicon 54.88%, iron-containing materials (total of scrap steel, steel ingots, cast iron, or pig iron) 27.65%, Calcium silicon 7.64%, Magnesium metal 6.83%, Rare earth ferrosilicon 3.33%. (Note: In actual production, the ingredients are not proportioned to 100% because different furnace materials have different degrees of loss, with Mg having the greatest loss. Based on experience, a 5% loss is added.)

[0134] Step 3: Calculate X max %.

[0135] Once the ingredient ratios are determined, X can be calculated using formula (3). max %.

[0136] =27.65%÷(27.65%+6.83%)=80.2%.

[0137] Step 4: Calculate the silicon content and density of the molten ferrosilicon in the furnace.

[0138] 1) First, a value of X% needs to be set, for example, let X% = 65%. Then, the density D of the molten ferrosilicon in the furnace is calculated. 标液and composite ingot density D 复块 After that, it is necessary to determine D. 复块 >D 标液 Moreover, the difference is less than 0.1 g / cm³. 3 That is, 0. <D 复块 - D 标液 ≤0.1;

[0139] 2) Calculate the proportion of iron introduced into the composite ingot to the total amount of raw materials added: Magnesium content (6.5%) × X% × Iron content of Q10 pig iron (95%) ÷ (1 - X%) = 12.04%;

[0140] 3) Calculate the amount of scrap steel added into the furnace = 27.65% of the amount of iron-containing raw materials added - 12.04% of the amount of iron element brought in by the composite ingot block = 15.61%;

[0141] 4) Calculate the silicon content in the molten ferrosilicon in the electric furnace: Si% = (54.88% × 72% of ferrosilicon addition + 7.64% × 50% of calcium silicon addition + 3.33% × 50% of rare earth ferrosilicon addition) ÷ (54.88% of ferrosilicon addition + 15.61% of scrap steel added to the furnace + 7.64% of calcium silicon addition + 3.33% of rare earth ferrosilicon addition) = 55.24%;

[0142] 5) Calculate the density D of the molten ferrosilicon in the furnace. 标液 According to formula (1), = 5.5 - 3.75 × 55.24% = 3.428 g / cm³ 3 .

[0143] Step 5: Calculate and determine the density of the composite ingot.

[0144] The insert is made of Q10 cast iron with a density of 7.1 g / cm³. 3 The outer shell is made of metallic magnesium with a density of 1.78 g / cm³. 3 The density of the composite ingot can be calculated according to formula (4).

[0145] =(7.1×1.78)÷(7.1-(7.1-1.78)× 65%)=3.47g / cm 3 ;

[0146] Make a judgment, D 复块 -D 标液 =3.47-3.428=0.042, therefore hypothesis X%=65% passes.

[0147] Step 6: Calculate X min %.

[0148] Calculate X according to formula (2) min %

[0149] = (7.1 - 7.1 × 1.78 ÷ 3.428) ÷ (7.1 - 1.78) = 64.17%;

[0150] Step 7: Prepare composite ingots.

[0151] When preparing composite ingot 12, Q10 pig iron is selected for the inner insert 7, and the mass fraction X% is controlled at the lower limit, prepared according to X%=65%. According to formula (5), the corresponding volume fraction V is calculated. x %=31.77%, calculated density D of composite ingot 复块 =3.47g / cm 3 D 标液 =3.428 g / cm 3 After being prepared in batches according to the above design, the measured density of the composite ingots was 3.45~3.47 g / cm³. 3 between.

[0152] Step 8: Producing the spheroidizing agent.

[0153] A domestically produced 2-ton electric furnace (industry standard calculated based on steel density) was used to melt ferrosilicon, with an actual maximum molten ferrosilicon weight of 1 ton. 549 kg of ferrosilicon, 156 kg of scrap steel, 76 kg of silicon-calcium alloy, and 33 kg of rare-earth ferrosilicon were added to the furnace. After melting, the measured ferrosilicon composition was 55.4% Si. A 195 kg composite ingot was placed in the reaction vessel. The ferrosilicon was tapped from the furnace at 1300℃ and poured into transfer vessel 1 (cooled by 30-50℃), then poured into the reaction vessel lid to react with the composite ingot 12. After the reaction stabilized, it was poured into ingot tray 11 for cooling, yielding 995 kg of spheroidizing agent ingots.

[0154] The spheroidizing agent was found to contain the following components: Si: 45.7%, Mg: 6.05%, Ce: 0.92%, La: 0.11%, Ca: 3.02%, and Al: 0.71%.

[0155] In actual mass production, many estimated values ​​are used to facilitate worker production, as follows:

[0156] 1) The spheroidizing agent was designed with a Si content of 45% because the furnace body will infiltrate silicon during production, and in continuous production, some ferrosilicon will adhere to the furnace wall from the previous batch. In actual production, the silicon content will be slightly higher than designed, so it was designed to be at the lower end of the range.

[0157] 2) When calculating the amount of rare earth silicon-calcium alloy added, the total amount of other alloys, excluding silicon-calcium alloy, is calculated based on the upper limit of 64%. These other alloys typically include ferrosilicon and silicon-calcium alloy; sometimes, barium silicon is also added based on market demand (based on practical experience, this also includes residual Ca from previous furnace runs). The 64% total addition, with a silicon content of 1.2%, is an empirical value. Furthermore, Ca is easily oxidized into slag during the formation process, resulting in losses. Based on empirical design, the Ca content in silicon-calcium alloy is calculated at 28%, while the actual calcium content in silicon-calcium alloy needs to be greater than 30%.

[0158] 3) Calculation of ferrosilicon addition: According to production practice, for hard 72 ferrosilicon (silicon content greater than 72%), the silicon content is calculated as 72%. For silicon-calcium and rare earth ferrosilicon, the converted silicon content is calculated as Si% = 60%. The actual silicon content of silicon-calcium and rare earth ferrosilicon is between 50% and 60%, and the upper limit can be used in the design; when calculating the silicon content of the alloy liquid during smelting, the lower limit can be used. These can be used as a safety factor based on the practices of each factory.

[0159] 4) Calculate the amount of Mg to be added. The Mg addition amount is calculated based on the upper limit to coordinate with the proportions of other raw materials. However, when Mg is actually added in production, an additional margin of about 5% is needed. This is to account for magnesium loss due to burning and gasification.

[0160] 5) When using scrap steel and steel ingots as raw materials, the Fe% content is calculated as 100%, while when using ductile iron and pig iron, the Fe% content is calculated as 93% and 95% respectively. In reality, ductile iron and pig iron also contain silicon, but the content is limited and can be ignored (when considering other factors mentioned above, there are positive and negative compensations based on statistical experience).

[0161] For automated factories with electronic computing capabilities, production can be precisely calculated and corrected in real time according to the formula in Example 1. This can further improve and control quality while saving costs. For most manufacturers that still produce according to standard process flow instructions, fine-tuning can be done based on the overall logic and actual experience parameters.

[0162] Example 2: Reaction process and test results of spheroidizing agent production:

[0163] In the spheroidizing agent production process of Example 1 above, after the molten ferrosilicon produced by smelting is poured into transfer bag 1, the electric furnace can continue to add raw materials and begin smelting. This separates the reaction process of spheroidizing agent production from the smelting process, ensuring the continuity of smelting and improving work efficiency. Simultaneously, the reaction is placed in a dedicated safety protection area, with a dust extraction system installed above the reaction bag, reducing safety risks and environmental pollution. The smelting time for one batch of molten ferrosilicon is 35-40 minutes (hot furnace). Once a new batch of molten ferrosilicon is completed, the reaction process can begin immediately, and the cycle repeats continuously.

[0164] Most of the slag in the furnace remained in transfer bag 1, with a small portion remaining in the water inlet area of ​​the reaction bag cover. The ferrosilicon entering the reaction bag was virtually slag-free. The magnesium outer shell 8 and the inner insert 7 (Q10 pig iron) in the composite ingot 12 reacted simultaneously with the ferrosilicon liquid. The process was rapid; after all the ferrosilicon liquid had flowed out of the water outlet area of ​​the reaction bag cover, the reaction bag stopped vibrating violently after about 10-20 seconds, but some residual, discontinuous magnesium flashes remained. Throughout the reaction process, some white smoke emerged from the junction of the reaction bag cover and the reaction bag, but this was significantly reduced compared to traditional production methods.

[0165] After the reaction vessel stabilized, the molten alloy was poured into ingot tray 11 for cooling. A total of two ingot trays 11 were used. After the spheroidizing agent ingots cooled, samples were taken and analyzed using XRD fluorescence spectroscopy. The measured composition of the spheroidizing agent was found to be Si: 45.7%, Mg: 6.05%, Ce: 0.92%, La: 0.11%, Ca: 3.02%, and Al: 0.71%. Simultaneously, samples were taken for microscopic analysis of the spheroidizing agent, and the results are as follows. Figure 10 and Figure 11 As shown, Figure 10 The image shows a scanning electron microscope (SEM) metallographic image of the spheroidizing agent. Figure 11 The images show the scanning electron microscope (SEM) metallographic images and energy dispersive spectroscopy (EDS) results of the spheroidizing agent.

[0166] Figure 10 The spheroidizing agent produced through the above process was placed under a scanning electron microscope (SEM) and the results were detected using backscattered electrons as the signal source at a magnification of 50x. It was observed that at low magnification, the phases in the spheroidizing agent were uniformly distributed, and the phase grains were relatively fine. Further magnification to 300x was used for energy dispersive spectroscopy (EDS) analysis. Figure 11 As shown ( Figures 12-17 In order Figure 11 (Enlarged view of the energy dispersive spectroscopy results at positions 8.1-8.6). The spheroidizing agent is mainly composed of six phases: Mg2Si phase (8.1), magnesium-rich rare earth phase (8.2), rare earth silicon-calcium phase (8.3), magnesium-silicon-calcium phase (8.4), Si-Fe phase (8.5), and high-silicon Si-Fe phase (8.6).

[0167] As seen in the image, the phases exhibit irregular morphology and no obvious directional arrangement, representing a typical multiphase mixed structure. The bright white phases (magnesium-rich rare earth phases and rare earth silicon-calcium phases) mostly exist in discrete, isolated states or are distributed along the boundaries of other phases; the dark gray and light gray phases constitute the matrix, interwoven with each other, forming the main alloy phases and solid solutions. All phases are evenly distributed.

[0168] Example 3: Production of spheroidizing agents by reduction furnace smelting

[0169] Reduction smelting is chosen to produce the spheroidizing agent of grade N01. All raw materials except molten ferrosilicon and composite ingots (i.e., the molten material in the reaction vessel) are added to the reaction vessel for reaction. This embodiment uses an 8000KVA reduction furnace, with a single tapping weight of 3-5 tons. Both the selected transfer vessel 1 and the reaction vessel are 5-ton ferrosilicon capacity vessels. Since the final alloy liquid density is greater than 75% ferrosilicon, there is sufficient space and margin in actual production.

[0170] Based on the furnace temperature estimated for the day's production, the Si% content of the ferrosilicon exiting the furnace is approximately 68%. For safety, the calculation is performed using ferrosilicon with a Si% content of 70%. The density D of the molten ferrosilicon exiting the furnace can be calculated using formula (1). 标液 =2.875g / cm 3 .

[0171] According to the grade setting, based on the original ferrosilicon liquid with an expected silicon content of 70%, the mass percentage of all raw materials selected is as follows: ferrosilicon 57.5%, iron-containing materials (the sum of scrap steel, steel ingots, cast iron, or pig iron) 24.69%, silicon-calcium 7.97%, metallic magnesium 7.0% (for high furnace temperatures, the loss should be appropriately increased), and rare earth ferrosilicon 3.33%. X can be calculated according to formula (3). max %=77.91%.

[0172] Considering production costs and convenience, different types of inserts 7 are selected. For those prioritizing standardization, ductile iron is preferred; for those prioritizing cost, pig iron is preferred; and for those prioritizing compromise, steel is chosen. Different inserts 7 have different densities, and the minimum mass fraction X of insert 7 is calculated according to formula (2). min The percentages are shown in Table 2 below.

[0173] Table 2 Minimum mass fraction X of inlay 7 min %

[0174]

[0175] In this embodiment, Q10 pig iron is still used, so the range of the mass fraction X% of the inner insert is 50.83~77.91%.

[0176] In reduction furnace smelting, the weight of each tapped iron cannot be determined in advance; a minimum tapped iron weight is estimated beforehand. The raw materials corresponding to this estimated weight, excluding molten ferrosilicon and composite ingots, are added to transfer bag 1. Here, scrap steel, calcium silicon, and rare earth ferrosilicon are used for direct reaction. Composite ingots are added to the reaction bag; after the actual tapped iron weight is weighed, any additional raw materials are also added to the reaction bag.

[0177] The silicon content in ferrosilicon produced by reduction furnaces fluctuates significantly, but is generally greater than 70%. Design Judgment D 复块 >D 标液When preparing composite ingots, the mass fraction (X%) of the inner inserts is controlled within the center line, and preparation is carried out according to X% = 65%. The corresponding volume fraction (V) is then calculated. x %=31.77%, calculated density D of composite ingot 复块 =3.57g / cm 3 After being prepared in batches according to the above design, the measured density of the composite ingots was 3.55~3.58 g / cm³. 3 This allows for the use and adjustment of ferrosilicon liquids with different silicon contents.

[0178] Based on a minimum ferroalloy output of 3 tons, 658 kg of scrap steel, 416 kg of silicon-calcium alloy, and 174 kg of rare-earth ferrosilicon were initially placed in transfer bag 1. 995 kg of composite ingots were pre-placed in the reaction bag. Sufficient raw materials were prepared and divided into small packages for later use. After the reduction furnace finished smelting and tapping, the molten ferrosilicon flowed from the bottom of the furnace into transfer bag 1. Weighing was performed using a crane scale, and the produced molten ferrosilicon weighed 3.36 tons. 119 kg of composite ingots, 79 kg of scrap steel, 50 kg of silicon-calcium alloy, and 21 kg of rare-earth ferrosilicon were quickly added to the reaction bag, and the bag was then covered. The tapping temperature of the reduction furnace is relatively high, generally around 2000℃. The molten ferrosilicon flowed into transfer bag 1 and reacted with the alloys inside, cooling to the target temperature. Simultaneously, a sample was taken from the middle section of the molten ferrosilicon, cooled, crushed, and powdered. The composition was then analyzed using an XRD fluorescence spectrometer, and the measured ferrosilicon content was Si: 69.86%, Ca: 1.12%, and Al: 1.23%. After the molten ferrosilicon in transfer package 1 is cooled to about 1300℃ (actually measured at 1305℃), it is poured into the reaction package cover. After the reaction settles, it is poured into ingot tray 11 for cooling, and 5830 kg of spheroidizing agent ingots are actually obtained.

[0179] The measured composition of the spheroidizing agent was Si: 44.8%, Mg: 6.10%, Ce: 0.94%, La: 0.10%, Ca: 2.97%, and Al: 0.82%.

[0180] Example 4: Production of vermicularizing agents by duplex smelting:

[0181] The vermicularizing agent is produced by dual melting in a reduction furnace and an electric furnace, and its grade is defined as NO2. The designed composition is shown in Table 3.

[0182] Table 3. Design composition of the vermicularizing agent

[0183]

[0184] The molten ferrosilicon produced by the reduction furnace is directly poured into the electric furnace for composition conditioning, and then used to produce vermicularizing agent. The ferrosilicon produced by the reduction furnace that day had a Si% content of about 72%. Since it can be conditioned, the calculation is based on ferrosilicon with a Si% content of 72%. The mass percentage of all raw materials used is as follows: molten ferrosilicon 43.72%, scrap steel 18.48%, silicon-calcium 7.97%, metallic magnesium 6.8%, and rare earth ferrosilicon 23.33%. X can be calculated according to formula (3). max %=73.1%.

[0185] The raw materials, except for composite ingot 12, are added to the electric furnace for smelting. These include silicon-calcium (measured composition: Si: 52.43%, Ca: 31.5%), rare earth ferrosilicon (measured composition: Si: 52.37%, Ce: 28.42%, La: 4.5%), and scrap steel (Q235 scrap steel). The raw materials used to prepare composite ingot 12 are metallic magnesium and pig iron (Q10 pig iron).

[0186] Therefore, the density of the molten ferrosilicon in the electric furnace needs to vary according to the change in X% in the composite ingot, and the design judgment D is required. 复块 >D 标液 X is calculated by combining formulas (1), (2) and (4). min %=58.97%. When preparing the composite ingot, Q10 pig iron was selected for the inner insert 7, and the mass fraction X% was controlled at the lower limit, prepared according to X%=60%. The corresponding volume fraction V was calculated. x %=27.33%, calculated density D of composite ingot 复块 =3.32g / cm 3 D 标液 =3.25 g / cm 3 After being prepared in batches according to the above design, the measured density of the composite ingots was 3.30~3.33 g / cm³. 3 between.

[0187] The reduction furnace produces approximately 4 tons of molten ferrosilicon per cycle, which is poured into two domestically produced 5-ton electric furnaces (calculated based on steel density). A total of 800 kg of scrap steel, 730 kg of silicon-calcium alloy, and 2135 kg of rare-earth ferrosilicon are also added to the two furnaces. After smelting, the measured molten ferrosilicon composition is 57.05% Si. After tempering in the electric furnaces, the power is reduced and the furnace is kept at a constant temperature, and the molten ferrosilicon is poured out in 10 batches. A 192 kg composite ingot is placed in a 2-ton reaction bag. The molten ferrosilicon is poured out at 1300℃ and injected into transfer bag 1 (cooled by 30-50℃), then poured into the reaction bag cover. After the reaction has calmed down, it is poured into ingot tray 11 for cooling, yielding 1140 kg of vermicularizing agent ingots.

[0188] The measured composition of the vermicularizing agent was Si: 46.3%, Mg: 6.05%, Ce: 6.52%, La: 0.77%, Ca: 3.12%, and Al: 0.92%.

[0189] Subsequent crushing and screening will yield the vermicularizer of the target particle size.

[0190] Example 5: Production of spheroidized wire core material from molten ferrosilicon in a reduction furnace

[0191] Spheroidized wire core material is produced by smelting ferrosilicon liquid in a reduction furnace, and the material is produced by using an electric furnace for heat preservation, heating, transfer and subcontracting. The grade is defined as N03, and the design composition is shown in Table 4.

[0192] Table 4 Design Composition of Spheroidized Wire Core Material

[0193]

[0194] The production of spheroidized wire core material requires ferrosilicon liquid with the highest possible silicon content. Ferrosilicon liquid produced in a reduction furnace is selected for production in batches with Si% > 77%. Calculations are based on ferrosilicon with a Si% content of 78%, D. 标液 =2.57 g / cm 3 All raw materials except molten ferrosilicon and composite ingots are added to the reaction vessel for reaction. The total percentage of raw materials by mass is as follows: molten ferrosilicon 49.74%, steel 15%, silicon-calcium 7.26%, metallic magnesium 22%, and rare earth ferrosilicon 6%.

[0195] When preparing composite ingot 12, Q235 steel blocks are selected for the inner insert 7, with all 15% of the steel blocks added to the composite ingot. This yields an X% = 40.54% preparation percentage, corresponding to the calculated volume fraction V. x %=14.6%, corresponding to D 复块 =2.59g / cm 3 After being prepared in batches according to the above design, the measured density of the composite ingots was 2.59~2.62 g / cm³. 3 between.

[0196] After smelting in the reduction furnace, the molten iron was tapped into transfer ladle 1 and weighed to 4.32 tons. The temperature of the molten ferrosilicon was 1873℃. It was first poured into an electric furnace for heat preservation, and then poured into several 2-ton reaction ladles. Based on weight calculations, composite ingots and other raw materials, mainly silicon-calcium and rare-earth ferrosilicon, were added to the reaction ladles and pressed onto the prepared composite ingots. When the molten ferrosilicon in the electric furnace was controlled at around 1300℃, the molten iron was tapped into the reaction ladles. After the reaction stabilized, it was poured into ingot tray 11 for cooling, yielding 8610 kg of spheroidized wire core ingots.

[0197] The measured composition of the spheroidized wire core material was obtained as follows: Si: 44.7%, Mg: 21.1%, Ce: 1.44%, La: 0.21%, Ca: 2.89%, Al: 0.72%. The spheroidized wire core material ingot was then subjected to a series of crushing, sieving, crushing, and sieving processes to obtain the spheroidized wire core material with the target particle size.

[0198] Comparative Example 1: Comparison of molten magnesium production processes

[0199] There are two existing methods for producing spheroidizing agents for ductile iron: the molten magnesium method and the pressing magnesium method.

[0200] Among them, the molten magnesium method is currently the most widely used process, accounting for more than 80% of the market.

[0201] Magnesium smelting process: Metallic magnesium is added to the melting furnace at the initial stage of smelting, while scrap steel is added at the final stage. The smelting process for producing spheroidizing agents can only be performed using an electric furnace. First, a layer of ferrosilicon is placed at the bottom of the furnace, then magnesium ingots are added. Rare earth ferrosilicon alloy, silicon-calcium alloy, ferrosilicon, and powder sieved off during the previous spheroidizing agent production are then added on top of the magnesium ingots. Scrap steel is placed at the furnace side and not added initially. Once all the alloys in the furnace have liquefied and the temperature has risen to approximately 1200℃, the scrap steel is added, and the furnace is quickly removed, with the molten alloy poured into ingot pan 11.

[0202] The advantages of this method are that it is more efficient and relatively less dangerous than the magnesium pressing method. Its disadvantages include: it is still very dangerous, causes serious pollution, has large fluctuations in product quality, especially in magnesium content, suffers severe magnesium loss due to burning, requires highly skilled operators, is highly hazardous, cannot remove or avoid slag, and contains many impurities in the product.

[0203] First, magnesium is a highly reactive metal. When added at the beginning of the smelting process, it is constantly at risk of oxidation and loss during the 20-40 minute smelting time (depending on furnace size). Magnesium has a boiling point of approximately 1090℃, and during the smelting process to 1200℃, it undergoes a violent reaction and vaporization. This manifests in the smelting process as a crust forming on the molten alloy in the electric furnace, primarily composed of oxides. This crust then bulges into a large bulge due to the vaporization of magnesium, producing a large amount of magnesium vapor. At this point, a worker needs to use an iron rod to break through the crust while simultaneously stirring the metal for approximately 1-3 minutes. This process produces intense white light and large amounts of white vapor within the furnace, accompanied by violent churning and splashing of the molten metal, indicating significant magnesium vaporization and loss. This not only results in severe magnesium loss and safety hazards but also constitutes serious environmental pollution. Workers must continuously stir the metal in this dangerous, high-temperature environment until complete smelting. At this point, scrap steel must be quickly added, and the molten metal immediately tapped out. The entire process requires a high level of skill from the workers.

[0204] Secondly, the composition and quality are unstable. As mentioned above, the stirring time after the worker breaks through the hard shell is inconsistent, depending on whether the alloy inside the furnace is completely liquefied. During this time, the worker must continuously stir to promote the homogenization of the alloy liquid and the absorption of metallic magnesium (because metallic magnesium has a low density and floats on the surface, stirring helps it mix with the alloy liquid below). This hard shell must be broken through by the worker, otherwise an explosion will occur. After breaking through, metallic magnesium begins to vaporize and burn violently. Therefore, even if the raw materials added are pre-designed, the violent losses during the process are uncertain, resulting in significant fluctuations in the final product composition.

[0205] Secondly, slag removal is impossible. Because metallic magnesium floats to the top during the later stages of smelting, slag removal is impossible. All the slag produced during the smelting process, along with oxides generated from the intense oxidation of magnesium, will be carried into the finished product. Figure 18 As shown in (a), this is the slag produced during the molten magnesium process for producing spheroidizing agents. For comparison, as... Figure 18 As shown in (b), the spheroidizing agent produced in Example 1 has a clean fracture surface free of impurities.

[0206] The method of this invention for producing spheroidizing agents can effectively solve several major problems associated with the molten magnesium method.

[0207] First, it is safe and produces minimal pollution. In this invention, molten ferrosilicon and composite ingots react within a reaction vessel, which can be placed in a safe, fixed location with dust and ventilation systems. Transfer vessel 1 is simply poured into the reaction vessel; no manual intervention is required. Workers can stay away from hazardous, polluting, and high-temperature sources. Magnesium vapor produced during the reaction can be discharged through environmental protection facilities.

[0208] Secondly, the quality is stable. The entire reaction process only involves the time it takes for the molten ferrosilicon to flow into the reaction vessel, which varies from 1 to 3 minutes depending on the size of the vessel. The reaction between the magnesium-containing composite ingot and the high-temperature molten ferrosilicon is also limited to this time, far shorter than the smelting time of the magnesium melting method. This short reaction time results in less magnesium loss and oxidation. Furthermore, the composite ingot sinks to the bottom of the alloy liquid, while the metallic magnesium on the surface liquefies and vaporizes before floating to the surface. During this rising process, it reacts with the ferrosilicon alloy liquid, rather than vaporizing on the surface. The vaporization and explosion reaction during the rising process also stirs the alloy liquid inside the vessel, starting from the bottom, further promoting magnesium absorption. The vessel lid increases the pressure inside, enhancing the magnesium absorption rate and concentration. Moreover, the entire process is unaffected by human intervention or other influencing factors, and is not affected by individual operator skill or experience.

[0209] Secondly, the molten alloy is clean. Before flowing into the reaction vessel, the ferrosilicon molten metal undergoes three slag-blocking and slag-avoidance processes, making it significantly cleaner than the molten magnesium method. This further improves product quality and stability.

[0210] Comparative Example 2: Comparison of Magnesium Pressing Process

[0211] Another existing method for producing spheroidizing agents is the magnesium pressing process.

[0212] Magnesium pressing process: Metallic magnesium is added at the final stage of smelting, either inside the furnace or in a ladle. Scrap steel is added at the beginning of smelting. Magnesium pressing can produce spheroidizing agents using electric furnace smelting or a reduction furnace with quenching and tempering. However, in China, electric furnace smelting is now the most common method. In the magnesium pressing process, pre-designed alloys such as ferrosilicon, rare earth ferrosilicon alloys, and silicon-calcium alloys are directly added to the electric furnace. Once the alloys in the furnace are completely liquefied and the temperature reaches 1200-1250℃, pre-assembled (or bundled) magnesium ingots are pressed into the molten ferrosilicon using external force. This is mostly done mechanically, but sometimes manually using simple equipment. This process involves a very violent reaction, producing a bright white light and thick smoke, and the molten alloy splashes everywhere. After the pressed magnesium has completely reacted, it is removed from the furnace, and the molten alloy is poured into ingot pan 11.

[0213] The advantages of this method are more stable quality compared to the molten magnesium method, and relatively less magnesium loss and waste. Its disadvantages include: severe pollution, low efficiency, and a higher risk factor, especially in manually operated plants, where there is still room for improvement in reducing magnesium loss and waste.

[0214] First, there are safety and pollution concerns. Currently, domestic magnesium pressing production all takes place inside a furnace, a process involving violent reactions and splashing that affects the entire smelting area. This smelting area contains numerous circuits and electronic components, as well as a relatively large number of workers. Furthermore, because the magnesium pressing equipment occupies a large space and the process is constantly in motion, dust and fume removal are very difficult. Therefore, most domestic manufacturers of spheroidizing agents using the magnesium pressing method have not adequately addressed environmental protection issues.

[0215] Secondly, there's the issue of efficiency. As mentioned above, currently in China, magnesium is pressed in an in-furnace process, meaning the electric furnace is unnecessarily occupied during the entire pressing process. If an operational error occurs and the furnace is damaged, it will disrupt normal operations. This is why the production efficiency of the pressing method for magnesium in China is generally lower than that of the molten magnesium method.

[0216] Finally, regarding quality. The magnesium pressing process is an open-loop process, and there is room for further improvement in magnesium absorption rate. Additionally, the magnesium pressing process for producing spheroidizing agents involves slag removal, which is done after the ferrosilicon melt has been smelted in the furnace. However, this method is inefficient, and adding slag-forming agents introduces new quality risks; without them, the slag cannot be completely removed.

[0217] The three problems of the magnesium pressing method can also be well solved when using the method of this invention to produce spheroidizing agents.

[0218] First, it is safer and less polluting. This has already been explained in Example 1. The magnesium metal reacts entirely inside the ladle, which is always covered, so it is much better at preventing splashing and light pollution than the magnesium pressing method. Furthermore, the composite ingot is submerged below the ferrosilicon alloy liquid, and the reaction and splashing begin from inside the ferrosilicon alloy liquid. Therefore, the magnesium vapor produced by the reaction mainly stirs the alloy liquid rather than splashing, so the intensity is much lower than that of the magnesium pressing method.

[0219] Secondly, efficiency is improved. As mentioned earlier, after the smelting is completed using the method of this invention, it is poured into transfer bag 1, and the electric furnace can then enter the next cycle to begin smelting. The efficiency is far higher than that of the magnesium pressing method.

[0220] Finally, quality is improved. As explained earlier, the high reaction pressure inside the reactor vessel leads to a high magnesium absorption rate; the ferrosilicon liquid undergoes three slag-blocking and slag-avoidance processes before flowing into the reactor vessel, ensuring a simple, clean process and preventing secondary contamination. This further improves product quality and stability.

[0221] The differences between the preparation method of this invention and the processes of the molten magnesium method and the pressing magnesium method are shown in Table 5.

[0222] Table 5. Differences between the preparation method of this invention and the molten magnesium method and the pressing magnesium method.

[0223]

[0224] The above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention in any way. It should be noted that those skilled in the art can make various improvements and modifications without departing from the principles of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An apparatus for preparing an additive for cast iron, wherein the additive for cast iron comprises a spheroidizing agent, a vermicularizing agent, or a spheroidizing wire core material, characterized in that: It includes a feed container and a reaction container arranged sequentially from top to bottom, with the feed container located at the top opening of the reaction container; The feeding container includes a baffle, a bottom plate, a first baffle, and a second baffle. The edge of the bottom plate, both ends of the first baffle, and both ends of the second baffle are respectively sealed to the inner wall of the baffle. A leakage hole is provided on the bottom plate. The second baffle is located between the first baffle and the leakage hole. There is a gap between the bottom end of the first baffle and the bottom plate. The bottom end of the second baffle is sealed to the bottom plate, and the top end of the second baffle is lower than the top end of the baffle. The vertical length of the first baffle exceeds half the height of the water outlet and water inlet areas and is less than 80% of the height of the water outlet and water inlet areas. The top end of the second baffle is higher than the bottom end of the first baffle. The bottom of the reaction vessel is provided with a reaction pit, the top of the reaction pit and the inner wall of the reaction vessel form an arc-shaped concave surface, and the arc-shaped concave surface is located directly below the leakage hole; The reaction pit is used to place a composite ingot block, which includes an inner ingot block and a shell that encloses the inner ingot block. The inner ingot block is made of iron and the shell is made of magnesium. The shell has an opening on one side, which exposes the inner ingot block.

2. The apparatus for preparing additives for cast iron according to claim 1, characterized in that: The bottom of the feed container is provided with a plug-in tube, which is inserted into the top opening of the reaction container and fits into the top opening of the reaction container.

3. The apparatus for preparing additives for cast iron according to claim 1, characterized in that: The top of the first baffle is flush with the top of the enclosure.

4. The apparatus for preparing additives for cast iron according to claim 1, characterized in that: The composite ingot is made by an ingot preparation mold, which includes an ingot container. The ingot container has a receiving cavity with an open top, and a boss is provided in the middle of the bottom surface of the receiving cavity. The bottom edge of the boss is spaced apart from the inner sidewall of the receiving cavity.

5. A method for preparing an additive for cast iron, wherein the additive comprises a spheroidizing agent, a vermicularizing agent, or a spheroidizing wire core material, characterized in that, The preparation apparatus according to any one of claims 1 to 4 comprises the following steps: A composite ingot is placed in the reaction pit. The composite ingot includes an inner ingot and a shell that encloses the inner ingot. The inner ingot is made of iron and the shell is made of magnesium. The shell has an opening on one side, which exposes the inner ingot. Molten ferrosilicon is fed into the feeding container. The molten ferrosilicon passes through the first baffle and the second baffle in sequence, and enters the reaction container through the leakage hole and the arc-shaped concave surface to react with the composite ingot to obtain alloy liquid. After the alloy liquid is discharged, it is cooled and solidified to obtain the additive for cast iron.

6. The preparation method according to claim 5, characterized in that, The mass content of Si element in the ferrosilicon liquid is 40-78%, and the temperature of the ferrosilicon liquid is 1250-1350℃.

7. The preparation method according to claim 6, characterized in that, The molten ferrosilicon is poured into the feed container from the transfer bag. The transfer bag is a container with a slag baffle plate on its top plate and a discharge port on its top. The slag baffle plate is close to the discharge port, and there is a discharge channel between the bottom end of the slag baffle plate and the inner wall of the transfer bag for the material in the transfer bag to flow to the discharge port.

8. The preparation method according to claim 5, characterized in that, The iron material is steel, cast iron, or pig iron, and the magnesium material is metallic magnesium or magnesium alloy.

9. The preparation method according to claim 5, characterized in that, The additive for cast iron comprises the following components in weight percentage: Si 30~50%, Mg 3.5~35%, RE 0~10%, Ba 0~5%, Ca 0~5%, Al 0~2%, and Fe balance; wherein RE is rare earth.

10. The preparation method according to any one of claims 5 to 9, characterized in that, The compositions of the ferrosilicon melt and the composite ingot are obtained according to formulas (1) to (5): Formula (1), Formula (2), Formula (3), Formula (4), Formula (5), In formulas (1)~(5), D 标液 The density of the molten ferrosilicon; Si%: The mass percentage of silicon in the molten ferrosilicon; X%: The mass percentage of the inserts in the composite ingot; X min %: The minimum mass percentage of the inserts in the composite ingot; X max %: The maximum percentage of the mass of the inserts in the composite ingot; D 内 The density of the inlay; D Mg The density of the shell; M Fe %: The percentage by mass of all iron materials added to the raw materials used in the preparation of additives for cast iron; M Mg %: The percentage by mass of magnesium in the raw materials added to the additives used in the preparation of cast iron; D 复块 The average density of the composite ingot; V x %: Volume percentage of the inserts in the composite ingot; X min %≤X%≤X max %, when X min %>X max When %, take X%=X max %D 复块 ≥D 标液 .

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