Synthesis method and application of desulfurization-spheroidization-inoculation integrated high-efficiency spheroidizing agent

Abstract

The application discloses a synthesis method and application of a desulfurization-spheroidization-inoculation integrated high-efficiency spheroidizing agent and belongs to the technical field of spheroidizing agents for producing nodular cast iron. The spheroidizing agent is prepared from the following components in parts by mass: rare earth magnesium alloy 45-60 parts, composite desulfurizer 20-30 parts, composite inoculant 12-20 parts, synergistic doping agent 2-5 parts, composite binder 1-3 parts and pig iron 5-8 parts. The spheroidizing agent adopts a gradient functional composite structure, the component distribution ratio is optimized by doping synergistic elements, the efficient synergy of desulfurization, spheroidization and inoculation functions is realized, and the problems of low bonding strength, layered peeling, insufficient desulfurization efficiency, easy recession of spheroidization and inoculation and the like of the existing integrated spheroidizing agent are solved. The spheroidizing agent simplifies the production process, reduces energy consumption and production cost, is suitable for the treatment requirement of high-sulfur raw molten iron and realizes green and efficient casting.

Description

Technical Field

[0001] This invention belongs to the technical field of spheroidizing agents for ductile iron production, specifically a synthesis method and application of an integrated desulfurization-spheroidizing-inoculation high-efficiency spheroidizing agent. Background Technology

[0002] Ductile iron, with its excellent mechanical properties, wear resistance, and machinability, is widely used in machinery manufacturing, automotive parts, and construction machinery. In the production of ductile iron, spheroidization and inoculation are core processes. However, sulfur in molten iron can severely impair the spheroidization effect, leading to graphite nodule distortion and a decrease in the spheroidization rate. Therefore, desulfurization is a necessary step before spheroidization.

[0003] Currently, the production of ductile iron commonly employs a step-by-step process: desulfurization, spheroidization, and inoculation. This involves first desulfurizing the molten iron with desulfurizing agents such as limestone or calcium carbide. After desulfurization meets standards, spheroidizing agents such as rare earth magnesium alloys are added for spheroidization. Finally, inoculating agents such as ferrosilicon are added for inoculation to prevent graphite nodules from growing and to avoid the formation of white cast iron. This step-by-step process has the following inherent drawbacks: cumbersome operation; high reagent consumption and production costs; existing integrated spheroidizing agents are prone to inoculation decline and uneven spheroidization; limited applicability due to the inability to flexibly adjust according to the molten iron composition; and it does not align with the development trend of green casting.

[0004] While some integrated spheroidizing agents have been reported in existing technologies to address the aforementioned issues, they all suffer from poor functional synergy, low desulfurization efficiency, unstable spheroidization and inoculation effects, and narrow compatibility. These shortcomings fail to fundamentally resolve the drawbacks of step-by-step processing and cannot meet the demands of large-scale production of high-sulfur molten iron. Therefore, developing an integrated, high-efficiency spheroidizing agent and its synthesis method that achieves efficient synergy in desulfurization, spheroidization, and inoculation, with high bonding strength, wide compatibility, and environmental friendliness, has become an urgent technical problem to be solved in the current ductile iron production field. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art and provide a synthesis method and application of an integrated high-efficiency spheroidizing agent for desulfurization, spheroidization and inoculation. This spheroidizing agent adopts a gradient functional composite structure and optimizes the composition ratio by doping with synergistic elements to achieve efficient synergy of desulfurization, spheroidization and inoculation functions. It solves the problems of low bonding strength, delamination and detachment, insufficient desulfurization efficiency and easy decline of spheroidization and inoculation in existing integrated spheroidizing agents, simplifies the production process, reduces energy consumption and production costs, adapts to the treatment needs of high sulfur molten iron, and achieves green and efficient casting.

[0006] This invention is implemented as follows:

[0007] A method for synthesizing an integrated desulfurization-spheroidizing-inoculation high-efficiency spheroidizing agent, characterized in that, by weight, it is prepared from the following components: 45-60 parts rare earth magnesium alloy, 20-30 parts composite desulfurizing agent, 12-20 parts composite inoculation agent, 2-5 parts synergistic dopant, 1-3 parts composite binder, and 5-8 parts pig iron; the method is as follows:

[0008] Step 1: Raw material pretreatment;

[0009] Step 2: Gradient Composite Molding

[0010] 1) Bottom layer forming: The pretreated rare earth magnesium alloy particles are placed in a granulator, a small amount of composite binder is sprayed, and the mixture is stirred for 5-8 minutes to make the surface of the rare earth magnesium alloy particles uniformly covered with a thin layer of binder as the spheroidization core layer.

[0011] 2) Intermediate layer molding: Slowly add the pretreated composite inoculant to the granulator and stir continuously for 8-12 minutes to make the composite inoculant evenly adhere to the surface of the spheroidized core layer, forming an inoculation transition layer. Control the thickness of the inoculation transition layer to be 0.8-1.2 mm.

[0012] 3) Surface forming: Continue to slowly add the pretreated composite desulfurizing agent and synergistic dopant into the granulator, while simultaneously spraying the composite binder. Continue stirring for 10-15 minutes to ensure that the composite desulfurizing agent and synergistic dopant are evenly mixed and adhered to the surface of the inoculation transition layer, forming a desulfurization functional layer. Control the thickness of the desulfurization functional layer to be 1.5-2.0 mm.

[0013] 4) Initial shaping: Adjust the granulator speed to 30-40 r / min and continue granulation for 5-10 min to obtain initial granules with a particle size of 8-12 mm;

[0014] Step 3: Low-temperature curing and high-temperature sintering;

[0015] Step 4: Cooling and post-processing.

[0016] Furthermore, the chemical composition of the rare earth magnesium alloy, by weight percentage, is: Mg: 8-12%, Re: 3-5%, Si: 38-45%, Al: 0.5-1.5%, Ti: 0.3-0.8%, with the remainder being Fe.

[0017] Furthermore, the composite desulfurizing agent is composed of the following components mixed in the following weight ratio: active lime powder: calcium carbide powder: dolomite powder = 5:3:2; wherein, the active lime powder has a CaO content ≥ 92% and a particle size of 80-100 mesh; the calcium carbide powder has a CaC2 content ≥ 85% and a particle size of 100-120 mesh; and the dolomite powder has a CaCO3+MgCO3 content ≥ 90% and a particle size of 80-100 mesh.

[0018] Furthermore, the composite inoculant is composed of the following components mixed in the following weight ratio: ferrosilicon powder: barium silicon powder: graphite powder = 6:2:2; wherein, the ferrosilicon powder has a Si content ≥75% and a particle size of 120-150 mesh; the barium silicon powder has a Ba content ≥15% and a Si content ≥60% and a particle size of 120-150 mesh; and the graphite powder has a fixed carbon content ≥99.5% and a particle size of 200-300 mesh.

[0019] Furthermore, step 1 specifically includes:

[0020] The rare earth magnesium alloy is crushed into particles with a size of 5-8 mm, placed in a vacuum drying oven, and dried at 105-110℃ for 20-30 minutes to remove surface moisture and impurities. The components of the composite desulfurizer, composite inoculant, and synergistic dopant are mixed evenly according to the formula, placed in a drying equipment, and dried at 110-115℃ for 30-40 minutes for later use. The components of the composite binder are mixed according to the formula, an appropriate amount of deionized water is added, and stirred until a uniform paste is formed for later use.

[0021] Furthermore, step 3 specifically includes:

[0022] 1) Low-temperature curing: Place the pre-formed particles into a curing oven and cure at 80-100℃ for 60-90 minutes;

[0023] 2) High-temperature sintering: The low-temperature cured particles are placed in a tunnel kiln, and an inert protective gas (nitrogen or argon) is introduced. The heating rate is controlled at 5-8℃ / min, and the temperature is raised to 850-900℃. The temperature is held for 2-3 hours for high-temperature sintering. During the sintering process, the composite binder undergoes a carbonization reaction to form a dense carbonaceous binder layer, which further enhances the bonding force of each functional layer. At the same time, the synergistic dopants are uniformly diffused to each layer to achieve functional synergy.

[0024] Furthermore, step 4 specifically involves: after sintering, shutting off the tunnel kiln heating device, maintaining the inert protective gas supply, and allowing the particles to cool to room temperature with the furnace; after cooling, an integrated high-efficiency spheroidizing agent for desulfurization-spheroidization-inoculation is obtained.

[0025] The advantages of this invention compared to the prior art are as follows:

[0026] This invention adopts a gradient composite structure of spheroidized core layer, inoculation transition layer, and desulfurization functional layer, which is different from the simple adhesion and delamination of the prior art. By combining composite adhesive with high-temperature sintering, each functional layer forms a dense overall structure, significantly improving the bonding strength. Delamination and peeling will not occur at high temperatures, ensuring the continuous and synergistic performance of desulfurization, spheroidization, and inoculation functions.

[0027] The present invention simplifies the process and reduces energy consumption and costs: it integrates the three-step process of desulfurization, spheroidization, and inoculation, eliminating the need for separate addition of reagents, simplifying the furnace operation process, reducing operational intensity, and minimizing iron temperature loss (40-50°C lower than the step-by-step process), while reducing energy consumption by 15-20%. At the same time, the absorption rate of spheroidizing and inoculating elements is increased by 25-30%, and reagent consumption is reduced by more than 20%, significantly reducing production costs.

[0028] This invention effectively controls the spheroidization reaction rate through gradient structure design and synergistic element doping, avoiding excessively vigorous reactions that lead to element burn-off and the generation of large amounts of harmful gases. The sintering process uses an inert protective gas to reduce oxidation burn-off and simultaneously reduce waste residue and exhaust gas emissions, which meets the development requirements of green casting.

[0029] The process of this invention is stable and easy to scale up for production: the synthesis method of this invention has clear steps and is easy to operate. The pretreatment, gradient molding, sintering and other processes all use conventional equipment and do not require special customization. It has high production efficiency, good product quality consistency and can realize large-scale mass production. Detailed Implementation

[0030] To make the objectives, technical solutions, and effects of this invention clearer and more explicit, the following examples provide a more detailed description of the invention. It should be noted that the specific embodiments described herein are merely illustrative and not intended to limit the scope of the invention.

[0031] Example 1

[0032] Based on mass parts, the integrated high-efficiency spheroidizing agent for desulfurization-spheroidization-inoculation in this embodiment is prepared from the following components: 43 parts rare earth magnesium alloy, 27 parts composite desulfurizer, 19 parts composite inoculator, 4 parts synergistic dopant, 2 parts composite binder, and 7 parts pig iron. The specific legal method is as follows:

[0033] Step 1: Raw material pretreatment; crush the rare earth magnesium alloy into particles with a size of 5-8mm, place them in a vacuum drying oven, and dry them at 105-110℃ for 20-30 minutes to remove surface moisture and impurities; mix the components of the composite desulfurizer, composite inoculant, and synergistic dopant according to the specified ratio, place them in a drying device, and dry them at 110-115℃ for 30-40 minutes, and set aside; mix the components of the composite binder according to the specified ratio, add an appropriate amount of deionized water, and stir until a uniform paste is formed, and set aside;

[0034] Step 2: Gradient Composite Molding

[0035] 1) Bottom layer forming: The pretreated rare earth magnesium alloy particles are placed in a granulator, a small amount of composite binder is sprayed, and the mixture is stirred for 5-8 minutes to make the surface of the rare earth magnesium alloy particles uniformly covered with a thin layer of binder as the spheroidization core layer.

[0036] 2) Intermediate layer molding: Slowly add the pretreated composite inoculant to the granulator and stir continuously for 8-12 minutes to make the composite inoculant evenly adhere to the surface of the spheroidized core layer, forming an inoculation transition layer. Control the thickness of the inoculation transition layer to be 0.8-1.2 mm.

[0037] 3) Surface forming: Continue to slowly add the pretreated composite desulfurizing agent and synergistic dopant into the granulator, while simultaneously spraying the composite binder. Continue stirring for 10-15 minutes to ensure that the composite desulfurizing agent and synergistic dopant are evenly mixed and adhered to the surface of the inoculation transition layer, forming a desulfurization functional layer. Control the thickness of the desulfurization functional layer to be 1.5-2.0 mm.

[0038] 4) Initial shaping: Adjust the granulator speed to 30-40 r / min and continue granulation for 5-10 min to obtain initial granules with a particle size of 8-12 mm;

[0039] Step 3: Low-temperature curing and high-temperature sintering;

[0040] 1) Low-temperature curing: Place the pre-formed particles into a curing oven and cure at 80-100℃ for 60-90 minutes;

[0041] 2) High-temperature sintering: The low-temperature cured particles are placed in a tunnel kiln, and an inert protective gas (nitrogen or argon) is introduced. The heating rate is controlled at 5-8℃ / min, and the temperature is raised to 850-900℃. The temperature is held for 2-3 hours for high-temperature sintering. During the sintering process, the composite binder undergoes a carbonization reaction to form a dense carbonaceous binder layer, which further enhances the bonding force of each functional layer. At the same time, the synergistic dopants are uniformly diffused to each layer to achieve functional synergy.

[0042] Step 4: Cooling and post-treatment. After sintering, turn off the tunnel kiln heating device and keep the inert protective gas flowing in to allow the particles to cool to room temperature with the furnace. After cooling, a high-efficiency spheroidizing agent integrating desulfurization, spheroidization and inoculation is obtained.

[0043] Example 2

[0044] Based on mass parts, the integrated high-efficiency spheroidizing agent for desulfurization-spheroidization-inoculation in this embodiment is prepared from the following components: 60 parts rare earth magnesium alloy, 30 parts composite desulfurizer, 20 parts composite inoculator, 5 parts synergistic dopant, 3 parts composite binder, and 8 parts pig iron. The specific legal method is as follows:

[0045] Step 1: Raw material pretreatment; crush the rare earth magnesium alloy into particles with a size of 5-8mm, place them in a vacuum drying oven, and dry them at 105-110℃ for 20-30 minutes to remove surface moisture and impurities; mix the components of the composite desulfurizer, composite inoculant, and synergistic dopant according to the specified ratio, place them in a drying device, and dry them at 110-115℃ for 30-40 minutes, and set aside; mix the components of the composite binder according to the specified ratio, add an appropriate amount of deionized water, and stir until a uniform paste is formed, and set aside;

[0046] Step 2: Gradient Composite Molding

[0047] 1) Bottom layer forming: The pretreated rare earth magnesium alloy particles are placed in a granulator, a small amount of composite binder is sprayed, and the mixture is stirred for 5-8 minutes to make the surface of the rare earth magnesium alloy particles uniformly covered with a thin layer of binder as the spheroidization core layer.

[0048] 2) Intermediate layer molding: Slowly add the pretreated composite inoculant to the granulator and stir continuously for 8-12 minutes to make the composite inoculant evenly adhere to the surface of the spheroidized core layer, forming an inoculation transition layer. Control the thickness of the inoculation transition layer to be 0.8-1.2 mm.

[0049] 3) Surface forming: Continue to slowly add the pretreated composite desulfurizing agent and synergistic dopant into the granulator, while simultaneously spraying the composite binder. Continue stirring for 10-15 minutes to ensure that the composite desulfurizing agent and synergistic dopant are evenly mixed and adhered to the surface of the inoculation transition layer, forming a desulfurization functional layer. Control the thickness of the desulfurization functional layer to be 1.5-2.0 mm.

[0050] 4) Initial shaping: Adjust the granulator speed to 30-40 r / min and continue granulation for 5-10 min to obtain initial granules with a particle size of 8-12 mm;

[0051] Step 3: Low-temperature curing and high-temperature sintering;

[0052] 1) Low-temperature curing: Place the pre-formed particles into a curing oven and cure at 80-100℃ for 60-90 minutes;

[0053] 2) High-temperature sintering: The low-temperature cured particles are placed in a tunnel kiln, and an inert protective gas (nitrogen or argon) is introduced. The heating rate is controlled at 5-8℃ / min, and the temperature is raised to 850-900℃. The temperature is held for 2-3 hours for high-temperature sintering. During the sintering process, the composite binder undergoes a carbonization reaction to form a dense carbonaceous binder layer, which further enhances the bonding force of each functional layer. At the same time, the synergistic dopants are uniformly diffused to each layer to achieve functional synergy.

[0054] Step 4: Cooling and post-treatment. After sintering, turn off the tunnel kiln heating device and keep the inert protective gas flowing in to allow the particles to cool to room temperature with the furnace. After cooling, a high-efficiency spheroidizing agent integrating desulfurization, spheroidization and inoculation is obtained.

[0055] Example 3

[0056] According to the mass fraction, the integrated high-efficiency spheroidizing agent for desulfurization-spheroidization-inoculation in this embodiment is prepared from the following components: 45 parts rare earth magnesium alloy, 20 parts composite desulfurizer, 12 parts composite inoculator, 2 parts synergistic dopant, 1 part composite binder, and 5 parts pig iron. The specific legal method is as follows:

[0057] Step 1: Raw material pretreatment; crush the rare earth magnesium alloy into particles with a size of 5-8mm, place them in a vacuum drying oven, and dry them at 105-110℃ for 20-30 minutes to remove surface moisture and impurities; mix the components of the composite desulfurizer, composite inoculant, and synergistic dopant according to the specified ratio, place them in a drying device, and dry them at 110-115℃ for 30-40 minutes, and set aside; mix the components of the composite binder according to the specified ratio, add an appropriate amount of deionized water, and stir until a uniform paste is formed, and set aside;

[0058] Step 2: Gradient Composite Molding

[0059] 1) Bottom layer forming: The pretreated rare earth magnesium alloy particles are placed in a granulator, a small amount of composite binder is sprayed, and the mixture is stirred for 5-8 minutes to make the surface of the rare earth magnesium alloy particles uniformly covered with a thin layer of binder as the spheroidization core layer.

[0060] 2) Intermediate layer molding: Slowly add the pretreated composite inoculant to the granulator and stir continuously for 8-12 minutes to make the composite inoculant evenly adhere to the surface of the spheroidized core layer, forming an inoculation transition layer. Control the thickness of the inoculation transition layer to be 0.8-1.2 mm.

[0061] 3) Surface forming: Continue to slowly add the pretreated composite desulfurizing agent and synergistic dopant into the granulator, while simultaneously spraying the composite binder. Continue stirring for 10-15 minutes to ensure that the composite desulfurizing agent and synergistic dopant are evenly mixed and adhered to the surface of the inoculation transition layer, forming a desulfurization functional layer. Control the thickness of the desulfurization functional layer to be 1.5-2.0 mm.

[0062] 4) Initial shaping: Adjust the granulator speed to 30-40 r / min and continue granulation for 5-10 min to obtain initial granules with a particle size of 8-12 mm;

[0063] Step 3: Low-temperature curing and high-temperature sintering;

[0064] 1) Low-temperature curing: Place the pre-formed particles into a curing oven and cure at 80-100℃ for 60-90 minutes;

[0065] 2) High-temperature sintering: The low-temperature cured particles are placed in a tunnel kiln, and an inert protective gas (nitrogen or argon) is introduced. The heating rate is controlled at 5-8℃ / min, and the temperature is raised to 850-900℃. The temperature is held for 2-3 hours for high-temperature sintering. During the sintering process, the composite binder undergoes a carbonization reaction to form a dense carbonaceous binder layer, which further enhances the bonding force of each functional layer. At the same time, the synergistic dopants are uniformly diffused to each layer to achieve functional synergy.

[0066] Step 4: Cooling and post-treatment. After sintering, turn off the tunnel kiln heating device and keep the inert protective gas flowing in to allow the particles to cool to room temperature with the furnace. After cooling, a high-efficiency spheroidizing agent integrating desulfurization, spheroidization and inoculation is obtained.

[0067] Example 4

[0068] Based on mass parts, the integrated high-efficiency spheroidizing agent for desulfurization-spheroidization-inoculation in this embodiment is prepared from the following components: 50 parts rare earth magnesium alloy, 28 parts composite desulfurizer, 15 parts composite inoculator, 3 parts synergistic dopant, 2 parts composite binder, and 6 parts pig iron. The specific legal method is as follows:

[0069] Step 1: Raw material pretreatment; crush the rare earth magnesium alloy into particles with a size of 5-8mm, place them in a vacuum drying oven, and dry them at 105-110℃ for 20-30 minutes to remove surface moisture and impurities; mix the components of the composite desulfurizer, composite inoculant, and synergistic dopant according to the specified ratio, place them in a drying device, and dry them at 110-115℃ for 30-40 minutes, and set aside; mix the components of the composite binder according to the specified ratio, add an appropriate amount of deionized water, and stir until a uniform paste is formed, and set aside;

[0070] Step 2: Gradient Composite Molding

[0071] 1) Bottom layer forming: The pretreated rare earth magnesium alloy particles are placed in a granulator, a small amount of composite binder is sprayed, and the mixture is stirred for 5-8 minutes to make the surface of the rare earth magnesium alloy particles uniformly covered with a thin layer of binder as the spheroidization core layer.

[0072] 2) Intermediate layer molding: Slowly add the pretreated composite inoculant to the granulator and stir continuously for 8-12 minutes to make the composite inoculant evenly adhere to the surface of the spheroidized core layer, forming an inoculation transition layer. Control the thickness of the inoculation transition layer to be 0.8-1.2 mm.

[0073] 3) Surface forming: Continue to slowly add the pretreated composite desulfurizing agent and synergistic dopant into the granulator, while simultaneously spraying the composite binder. Continue stirring for 10-15 minutes to ensure that the composite desulfurizing agent and synergistic dopant are evenly mixed and adhered to the surface of the inoculation transition layer, forming a desulfurization functional layer. Control the thickness of the desulfurization functional layer to be 1.5-2.0 mm.

[0074] 4) Initial shaping: Adjust the granulator speed to 30-40 r / min and continue granulation for 5-10 min to obtain initial granules with a particle size of 8-12 mm;

[0075] Step 3: Low-temperature curing and high-temperature sintering;

[0076] 1) Low-temperature curing: Place the pre-formed particles into a curing oven and cure at 80-100℃ for 60-90 minutes;

[0077] 2) High-temperature sintering: The low-temperature cured particles are placed in a tunnel kiln, and an inert protective gas (nitrogen or argon) is introduced. The heating rate is controlled at 5-8℃ / min, and the temperature is raised to 850-900℃. The temperature is held for 2-3 hours for high-temperature sintering. During the sintering process, the composite binder undergoes a carbonization reaction to form a dense carbonaceous binder layer, which further enhances the bonding force of each functional layer. At the same time, the synergistic dopants are uniformly diffused to each layer to achieve functional synergy.

[0078] Step 4: Cooling and post-treatment. After sintering, turn off the tunnel kiln heating device and keep the inert protective gas flowing in to allow the particles to cool to room temperature with the furnace. After cooling, a high-efficiency spheroidizing agent integrating desulfurization, spheroidization and inoculation is obtained.

[0079] Example 5

[0080] Based on mass parts, the integrated high-efficiency spheroidizing agent for desulfurization-spheroidizing-inoculation in this embodiment is prepared from the following components: 48 parts rare earth magnesium alloy, 21 parts composite desulfurizer, 16 parts composite inoculator, 3 parts synergistic dopant, 2 parts composite binder, and 7 parts pig iron. The specific legal method is as follows:

[0081] Step 1: Raw material pretreatment; crush the rare earth magnesium alloy into particles with a size of 5-8mm, place them in a vacuum drying oven, and dry them at 105-110℃ for 20-30 minutes to remove surface moisture and impurities; mix the components of the composite desulfurizer, composite inoculant, and synergistic dopant according to the specified ratio, place them in a drying device, and dry them at 110-115℃ for 30-40 minutes, and set aside; mix the components of the composite binder according to the specified ratio, add an appropriate amount of deionized water, and stir until a uniform paste is formed, and set aside;

[0082] Step 2: Gradient Composite Molding

[0083] 1) Bottom layer forming: The pretreated rare earth magnesium alloy particles are placed in a granulator, a small amount of composite binder is sprayed, and the mixture is stirred for 5-8 minutes to make the surface of the rare earth magnesium alloy particles uniformly covered with a thin layer of binder as the spheroidization core layer.

[0084] 2) Intermediate layer molding: Slowly add the pretreated composite inoculant to the granulator and stir continuously for 8-12 minutes to make the composite inoculant evenly adhere to the surface of the spheroidized core layer, forming an inoculation transition layer. Control the thickness of the inoculation transition layer to be 0.8-1.2 mm.

[0085] 3) Surface forming: Continue to slowly add the pretreated composite desulfurizing agent and synergistic dopant into the granulator, while simultaneously spraying the composite binder. Continue stirring for 10-15 minutes to ensure that the composite desulfurizing agent and synergistic dopant are evenly mixed and adhered to the surface of the inoculation transition layer, forming a desulfurization functional layer. Control the thickness of the desulfurization functional layer to be 1.5-2.0 mm.

[0086] 4) Initial shaping: Adjust the granulator speed to 30-40 r / min and continue granulation for 5-10 min to obtain initial granules with a particle size of 8-12 mm;

[0087] Step 3: Low-temperature curing and high-temperature sintering;

[0088] 1) Low-temperature curing: Place the pre-formed particles into a curing oven and cure at 80-100℃ for 60-90 minutes;

[0089] 2) High-temperature sintering: The low-temperature cured particles are placed in a tunnel kiln, and an inert protective gas (nitrogen or argon) is introduced. The heating rate is controlled at 5-8℃ / min, and the temperature is raised to 850-900℃. The temperature is held for 2-3 hours for high-temperature sintering. During the sintering process, the composite binder undergoes a carbonization reaction to form a dense carbonaceous binder layer, which further enhances the bonding force of each functional layer. At the same time, the synergistic dopants are uniformly diffused to each layer to achieve functional synergy.

[0090] Step 4: Cooling and post-treatment. After sintering, turn off the tunnel kiln heating device and keep the inert protective gas flowing in to allow the particles to cool to room temperature with the furnace. After cooling, a high-efficiency spheroidizing agent integrating desulfurization, spheroidization and inoculation is obtained.

[0091] The spheroidizing agent in Example 1 above was tested and treated under the same high-sulfur molten iron (S=0.08%). The test results are shown in the table below:

[0092] Example 1 Desulfurization efficiency 85% S content (%) in molten iron after desulfurization 0.012 Spheroidization rate (%) 96 Graphite sphere level Level 1 Tensile strength (MPa) 680

[0093] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements can be made without departing from the principle of the present invention, and these improvements should also be considered within the scope of protection of the present invention.

Claims

1. A method for synthesizing a highly efficient spheroidizing agent integrating desulfurization-spheroidizing-inoculation, characterized in that, Prepared from the following components, by weight: 45-60 parts rare earth magnesium alloy, 20-30 parts composite desulfurizer, 12-20 parts composite inoculant, 2-5 parts synergistic dopant, 1-3 parts composite binder, and 5-8 parts pig iron; The method is as follows: Step 1: Raw material pretreatment; Step 2: Gradient composite molding 1) Bottom layer forming: The pretreated rare earth magnesium alloy particles are placed in a granulator, a small amount of composite binder is sprayed, and the mixture is stirred for 5-8 minutes to make the surface of the rare earth magnesium alloy particles uniformly covered with a thin layer of binder as the spheroidization core layer. 2) Intermediate layer molding: Slowly add the pretreated composite inoculant to the granulator and stir continuously for 8-12 minutes to make the composite inoculant evenly adhere to the surface of the spheroidized core layer, forming an inoculation transition layer. Control the thickness of the inoculation transition layer to be 0.8-1.2 mm. 3) Surface forming: Continue to slowly add the pretreated composite desulfurizing agent and synergistic dopant into the granulator, while simultaneously spraying the composite binder. Continue stirring for 10-15 minutes to ensure that the composite desulfurizing agent and synergistic dopant are evenly mixed and adhered to the surface of the inoculation transition layer, forming a desulfurization functional layer. Control the thickness of the desulfurization functional layer to be 1.5-2.0 mm. 4) Initial shaping: Adjust the granulator speed to 30-40 r / min and continue granulation for 5-10 min to obtain initial granules with a particle size of 8-12 mm; Step 3: Low-temperature curing and high-temperature sintering; Step 4: Cooling and post-processing.

2. The method for synthesizing a highly efficient spheroidizing agent integrating desulfurization-spheroidizing-inoculation according to claim 1, characterized in that, The chemical composition of the rare earth magnesium alloy, by weight percentage, is as follows: Mg: 8-12%, Re: 3-5%, Si: 38-45%, Al: 0.5-1.5%, Ti: 0.3-0.8%, with the remainder being Fe.

3. The method for synthesizing a high-efficiency spheroidizing agent integrating desulfurization-spheroidizing-inoculation according to claim 1, characterized in that, The composite desulfurizing agent is composed of the following components mixed in the following weight ratio: active lime powder: calcium carbide powder: dolomite powder = 5:3:2; wherein, the active lime powder has a CaO content ≥92% and a particle size of 80-100 mesh; the calcium carbide powder has a CaC2 content ≥85% and a particle size of 100-120 mesh; and the dolomite powder has a CaCO3+MgCO3 content ≥90% and a particle size of 80-100 mesh.

4. The method for synthesizing a high-efficiency spheroidizing agent integrating desulfurization-spheroidizing-inoculation according to claim 1, characterized in that, The composite inoculant is composed of the following components mixed in the following weight ratio: ferrosilicon powder: barium silicon powder: graphite powder = 6:2:2; wherein, the ferrosilicon powder has a Si content ≥75% and a particle size of 120-150 mesh; the barium silicon powder has a Ba content ≥15% and a Si content ≥60% and a particle size of 120-150 mesh; and the graphite powder has a fixed carbon content ≥99.5% and a particle size of 200-300 mesh.

5. The method for synthesizing a highly efficient spheroidizing agent integrating desulfurization-spheroidizing-inoculation according to claim 1, characterized in that, Step 1 specifically includes: The rare earth magnesium alloy is crushed into particles with a size of 5-8 mm, placed in a vacuum drying oven, and dried at 105-110℃ for 20-30 minutes to remove surface moisture and impurities. The components of the composite desulfurizer, composite inoculant, and synergistic dopant are mixed evenly according to the formula, placed in a drying equipment, and dried at 110-115℃ for 30-40 minutes for later use. The components of the composite binder are mixed according to the formula, an appropriate amount of deionized water is added, and stirred until a uniform paste is formed for later use.

6. The method for synthesizing a high-efficiency spheroidizing agent integrating desulfurization-spheroidizing-inoculation according to claim 1, characterized in that, Step 3 specifically includes: 1) Low-temperature curing: Place the pre-formed particles into a curing oven and cure at 80-100℃ for 60-90 minutes; 2) High-temperature sintering: The low-temperature cured particles are placed in a tunnel kiln, and an inert protective gas (nitrogen or argon) is introduced. The heating rate is controlled at 5-8℃ / min, and the temperature is raised to 850-900℃. The temperature is held for 2-3 hours for high-temperature sintering. During the sintering process, the composite binder undergoes a carbonization reaction to form a dense carbonaceous binder layer, which further enhances the bonding force of each functional layer. At the same time, the synergistic dopants are uniformly diffused to each layer to achieve functional synergy.

7. The method for synthesizing a high-efficiency spheroidizing agent integrating desulfurization-spheroidizing-inoculation according to claim 1, characterized in that, Step 4 specifically involves: after sintering, shutting off the tunnel kiln heating device and maintaining the inert protective gas supply to allow the particles to cool to room temperature with the furnace; after cooling, an integrated high-efficiency spheroidizing agent for desulfurization-spheroidization-inoculation is obtained.

8. The desulfurization-spheroidizing-inoculation integrated high-efficiency spheroidizing agent prepared by the synthesis method according to any one of claims 1 to 7.

9. The application of the integrated desulfurization-spheroidizing-inoculation high-efficiency spheroidizing agent as described in claim 8 in the production of ductile iron.