Method for automatically adding and mixing auxiliary materials of up-drawing furnace

Abstract

This invention relates to the field of metallurgical auxiliary material preparation and application technology, and discloses an automatic addition and mixing method for auxiliary materials in an upward-drawing furnace. The method includes uniformly mixing flake graphite, phosphor bronze pellets, anhydrous borax, rosin, and azodicarbonamide to obtain a dry mixture; transferring the dry mixture to a double-arm kneader for main shaft kneading, followed by heating to trigger a foaming reaction, and then reducing the rotation speed to agitate and foam, resulting in a sponge-like porous plastic agglomerate; discharging and cooling the porous plastic agglomerate to solidify the internal pore skeleton into a porous plate, which is then crushed into solid porous agglomerate particles; mixing a measured amount of porous agglomerate particles with anhydrous borax in an automatic mixing chamber, while simultaneously atomizing and spraying polyethylene glycol 400 to coat and mix, thus obtaining a composite auxiliary material; finally, conveying and adding it to the surface of the molten metal pool. This invention utilizes a solidified pore skeleton to overcome the segregation of multi-component materials and alleviate thermal splashing, while the outer coating structure helps to isolate oxygen.

Description

Technical Field

[0001] This invention relates to the field of metallurgical auxiliary material preparation and application technology, specifically a method for automatic addition and mixing of auxiliary materials for upward drawing furnaces. Background Technology

[0002] The upward continuous casting process is often used in the production of oxygen-free copper and copper alloy wire. During production, in order to prevent the molten metal pool from oxidizing and to reduce the metal oxides that have been generated, a protective auxiliary material needs to be continuously covered on the surface of the molten metal pool. Conventional upward furnace auxiliary materials are generally made by simple mechanical mixing of powdery and granular materials with different functions such as flake graphite, phosphor bronze pellets and borax, and are transported to the surface of the molten pool by the factory's automated feeding system.

[0003] The method of directly mixing bulk powder has certain process limitations in actual continuous production. Due to the significant differences in density and particle size between components such as flake graphite and phosphor bronze pellets, density segregation will occur during the storage of bulk powder in the silo and the transportation of it through pipelines. This will result in an unstable proportion of auxiliary components that finally enter the molten pool. As a result, the mixture of powder particles of different forms will experience stagnation and blockage in the automatic feeding pipeline.

[0004] When powdered additives come into direct contact with the surface of a high-temperature molten metal pool, the volatiles inside the powdered additives are rapidly heated and vaporized at high temperatures. The accumulation and release of gas on the surface of the molten pool often causes material splashing. The splashing phenomenon will destroy the additive covering layer originally established on the surface of the molten pool, causing the underlying high-temperature molten metal to be exposed to the air and generate secondary oxygen absorption, resulting in excessive oxygen content inside the casting, which in turn affects the processing performance of the continuously cast products. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides an automatic addition and mixing method for auxiliary materials in an upward-drawing furnace. This method solves the problems of segregation and pipeline blockage caused by significant differences in component density of existing powdery auxiliary materials during transportation, as well as material splashing caused by the instantaneous expansion and vaporization of internal volatiles when the auxiliary materials come into contact with the high-temperature molten metal pool, which leads to damage to the molten pool covering layer and secondary oxygen absorption by the molten metal.

[0006] To achieve the above objectives, the present invention provides the following technical solution: an automatic addition and mixing method for auxiliary materials in an upward-drawing furnace, the method comprising the following steps: Flake graphite, copper phosphate pellets, anhydrous borax, rosin, and azodicarbonamide are mixed evenly to obtain a dry, homogeneous mixture. The dry, homogeneous material is transferred to a double-arm kneader with a heated jacket. First, the main shaft kneads the material. Then, the jacket temperature is increased to the temperature that triggers the foaming reaction, and the rotation speed is reduced to allow the material to tumble and foam, resulting in a sponge-like porous plastic mass. The sponge-like porous plastic agglomerate is discharged and cooled to solidify the internal pore skeleton to obtain a solid porous board. The solid porous board is then crushed into solid porous agglomerate particles. By driving a loss-in-weight weighing feeder, the quantitatively conveyed solid porous agglomerates and anhydrous borax are stirred in an automatic mixing bin, while polyethylene glycol 400 is sprayed in an atomized manner for coating and mixing, thus obtaining the upper furnace composite auxiliary material. The composite auxiliary materials for the upward drawing furnace are automatically conveyed and added to the surface of the molten metal pool in the upward drawing furnace through a conveying device.

[0007] By adopting the above technical solution, the following effects are achieved: The technical approach of this invention improves the segregation and splashing of traditional powdered excipients by changing the structural morphology of the materials. During the heating, kneading and foaming stages, the heated and molten rosin encapsulates the flake graphite, phosphor bronze pellets and anhydrous borax. As the temperature of the kneading system rises to the decomposition point of azodicarbonamide, the azodicarbonamide undergoes thermal decomposition. The gas produced by the decomposition expands outward in the viscous rosin matrix to form multiphase foam. After cooling, the rosin matrix undergoes phase transformation and solidifies to form a sponge-like porous board. The generated porous skeleton can lock powder particles of different densities in the network structure, which helps to overcome the density segregation phenomenon that occurs when bulk materials are mixed.

[0008] After the composite auxiliary material for the upward drawing furnace is added to the surface of the molten metal pool, the increased pore size inside the porous agglomerates increases the thermal resistance of heat transfer from the outside to the inside of the material. This allows the volatile gases generated by the vaporization of rosin inside the porous agglomerates to be released relatively slowly along the reserved pore channels. This can alleviate the splashing caused by the instantaneous accumulation and expansion of volatile gases to a certain extent. Meanwhile, the anhydrous borax adhering to the outer layer of the composite auxiliary material for the upward drawing furnace is the first to be heated and melted to form a covering liquid film. This film, together with the phosphorus copper pellets and flake graphite, plays a corresponding deoxidation and reduction protection role.

[0009] Preferably, the dry homogeneous material is prepared by mixing raw materials comprising the following parts by weight: Flake graphite: 35 to 45 parts by weight; Phosphorus copper pellets: 40 to 50 parts by weight; Anhydrous borax: 12 to 15 parts by weight; Rosin: 12 to 16 parts by weight; Azodicarbonamide: 1.2 to 1.6 parts by weight.

[0010] By adopting the above technical solution, the set raw material ratio helps to maintain the gas-liquid balance during the foaming process. The amount of flake graphite and phosphor bronze pellets added is mainly used to adapt to the deoxidation and reduction requirements in the upper drawing furnace. Adding an appropriate amount of azodicarbonamide can control the solid porous agglomerates to have a reasonable porosity, which not only reduces the probability of solid porous agglomerates breaking during the spiral conveying process due to excessive porosity, but also prevents the problem of insufficient porosity to provide a buffer channel for gas release.

[0011] Preferably, when preparing the composite auxiliary material for the upper furnace, the material being coated and mixed comprises the following parts by weight: Solid porous agglomerated particles: 90 to 110 parts by weight; Anhydrous borax: 10 to 20 parts by weight; Polyethylene glycol 400: 3 to 7 parts by weight.

[0012] By adopting the above technical solution, in the coating and mixing process, polyethylene glycol 400 forms a liquid film on the surface of solid porous agglomerates and adsorbs anhydrous borax powder by relying on surface tension. Adjusting the amount of polyethylene glycol 400 can reduce the risk of material sticking and clumping caused by excess liquid, which is beneficial to maintaining the flowability of the composite auxiliary material in the automatic mixing bin and screw conveyor of the upper furnace.

[0013] Preferably, when mixing to obtain a dry homogeneous material, the material is put into a mixer at 25°C, the speed is set to 15 to 20 rpm, and the mixing is continued for 10 to 15 minutes.

[0014] By adopting the above technical solution, dry premixing at a low speed under room temperature conditions can avoid the generation of intense frictional heat while dispersing raw material particles, thereby reducing the occurrence of premature decomposition of azodicarbonamide or premature softening of rosin.

[0015] Preferably, when kneading the main shaft in the double-arm kneader, the jacket temperature is controlled at 140 to 150°C, the main shaft speed is 30 to 40 rpm, and kneading is continued for 15 to 20 minutes; when tumbling and foaming, the jacket temperature is increased to 215 to 220°C and the material temperature in the kneading chamber is increased to 205 to 210°C, the main shaft speed is reduced to 5 rpm, and foaming is continued for 3 to 5 minutes.

[0016] By adopting the above technical solution, the temperature and speed settings at different stages enable the kneading operation to utilize the shear force of the spindle to complete the solid-liquid phase dispersion in conjunction with the molten rosin; when the temperature is increased to trigger the decomposition reaction of azodicarbonamide, the spindle speed is reduced to tumble and foam, which helps to protect the developing bubble structure from damage by strong shear force and facilitates the formation of an internal porous skeleton in the material.

[0017] Preferably, when discharging and cooling the sponge-like porous plastic agglomerate, it is spread flat on a crawler conveyor belt with forced cold air cooling and cooled to 30 to 40°C within 3 to 5 minutes; when crushing the solid porous board, a toothed roller crusher is used to crush the solid porous board into solid porous agglomerate particles with an average particle size of 4.5 to 8 mm.

[0018] By adopting the above technical solution, the forced cold air is used to accelerate the cooling process, which promotes the rapid solidification of the liquid rosin matrix and stabilizes the internal pore volume. The toothed roller crusher with low compressive stress is used for crushing, which can reduce the situation where the internal porous structure of the solid porous board is crushed due to mechanical pressure while obtaining the material of the required particle size.

[0019] Preferably, the stirring speed in the automatic mixing hopper is 25 to 35 rpm, and the atomized spraying of polyethylene glycol 400 is completed within 1 to 3 minutes by a liquid metering pump. After spraying, the coating and mixing continues for 5 to 10 minutes. When automatic conveying and adding, the pneumatic discharge valve at the bottom of the automatic mixing hopper is opened, and the composite auxiliary material for the upper furnace is automatically conveyed and added through a closed screw conveyor.

[0020] By adopting the above technical solution, the atomized spraying method enables polyethylene glycol 400 to be relatively evenly dispersed in the churning material particles. The subsequent continuous stirring action uses the collision between particles to coat anhydrous borax on the outer layer of the liquid film, thereby obtaining a relatively stable physical morphology of the upward furnace composite auxiliary material, which helps the pneumatic discharge valve to discharge material smoothly and the airflow to transport.

[0021] Preferably, by coating and mixing, the liquid adhesion force of polyethylene glycol 400 is used to adhere anhydrous borax to the surface of solid porous agglomerated particles, thereby obtaining an upper furnace composite auxiliary material with an anhydrous borax surface adhesion structure.

[0022] By adopting the above technical solution, the anhydrous borax coating absorbs heat and melts preferentially into a borate glassy film when in contact with high-temperature molten metal. This surface film can prevent ambient oxygen from directly contacting the molten metal below, thus providing relatively stable physical oxygen barrier protection.

[0023] Preferably, during the agitation, foaming, and cooling processes, the material undergoing the foaming reaction is made into a sponge-like porous plastic agglomerate, and the internal pore skeleton of the sponge-like porous plastic agglomerate is solidified to obtain a solid porous board with a solidified pore skeleton structure.

[0024] By adopting the above technical solution, through the foaming and cooling curing process, the mixture is prepared into a block-shaped whole with a solidified pore skeleton structure. The components of different densities in the original raw materials can be relatively fixed in this structure, reducing the probability of secondary segregation and separation of the dry homogeneous material in the subsequent crushing and conveying pipeline.

[0025] Preferably, the phosphorus-copper pellets used in the dry homogenized material have a phosphorus mass fraction of 8.0% to 15.0% and an apparent density of 7.8 to 8.2 g / cm³. 3 The particle diameter is 1.5 to 3.0 mm; the rosin used in the dry homogeneous material is industrial resin rosin.

[0026] By adopting the above technical solution and selecting phosphorus copper pellets with specific mass fraction and particle diameter, it is beneficial to match the self-melting and deoxidation reaction rate of the phosphorus copper pellets after entering the molten metal pool with the process requirements of continuous casting production; industrial rosin can release reducing gas when it decomposes at high temperature, which synergistically plays the role of protecting the surface of the molten metal pool.

[0027] This invention provides an automatic method for adding and mixing auxiliary materials in an upward-drawing furnace. It has the following beneficial effects: 1. This invention involves heating and kneading raw materials with large density differences, such as flake graphite and phosphor bronze pellets, with rosin, and then using azodicarbonamide for foaming followed by cooling and solidification to obtain solid porous aggregated particles with an internal pore skeleton structure. The solidified pore skeleton physically locks each component in the matrix network, improving the density segregation that occurs during the storage and transportation stages of bulk powdered auxiliary materials after mixing, maintaining the material uniformity of the composite auxiliary materials in the automatic mixing bin and screw conveyor equipment, and helping to reduce the risk of blockage in the discharge pipeline.

[0028] 2. In this invention, when the composite auxiliary material of the upward furnace contacts the surface of the high-temperature molten metal pool in the upward furnace, the pore structure inside the solid porous agglomerated particles increases the thermal resistance of external heat conduction to the material interior, slows down the rate of internal rosin vaporization, and the pre-formed pore structure also provides a channel for the volatiles generated by vaporization to be discharged outward, which helps to alleviate the material splashing phenomenon caused by gas accumulation and expansion, reduces the possibility of the auxiliary material covering layer on the surface of the molten metal pool being damaged by splashing, and maintains the relative stability of the deoxidation environment on the surface of the molten pool.

[0029] 3. In the coating and mixing stage, the present invention utilizes the liquid adhesion of polyethylene glycol 400 to adhere anhydrous borax powder to the surface of solid porous agglomerated particles. When the composite auxiliary material of the upper drawing furnace is added to the molten metal pool, the anhydrous borax on the outer layer is heated and melted first and spreads on the surface of the molten metal to form a liquid oxygen barrier film. The liquid oxygen barrier film physically blocks the direct contact between the ambient air and the molten metal below. Together with the phosphor bronze pellets and flake graphite that subsequently enter the molten pool, it provides a relatively long-lasting anti-oxidation and reduction protection environment for the molten metal pool of the upper drawing furnace. Attached Figure Description

[0030] Figure 1 This is a schematic diagram of the differential scanning calorimetry curve of the present invention; Figure 2This is a schematic diagram of the apparent viscosity change curve of the present invention; Figure 3 This is a schematic diagram of the mass fraction distribution curve of copper element along the height of the feed column in this invention; Figure 4 This is a schematic diagram of the mass fraction distribution curve of carbon element along the height of the material column in this invention; Figure 5 This is a schematic diagram of the acoustic emission amplitude envelope curve of the present invention; Figure 6 This is a schematic diagram of the spread coverage evolution curve of the present invention; Figure 7 This is a schematic diagram of the evolution curve of oxygen mass fraction in copper liquid according to the present invention; Figure 8 This is a schematic diagram of the cumulative carbon element oxidation burn-off rate curve of the present invention. Detailed Implementation

[0031] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] The main raw materials and reagents used in the following examples and comparative examples have the following sources and specifications. Reagents not specifically mentioned are all commercially available analytical grade or higher grade products.

[0033] Flake graphite, CAS number 7782-42-5; Phosphorus copper pellets, with a phosphorus mass fraction of 8.0% to 15.0% and an apparent density of 7.8 to 8.2 g / cm³. 3 The particle diameter is 1.5 to 3.0 mm; Anhydrous borax, CAS number 1330-43-4; Rosin, CAS number 8050-09-7, in this embodiment the rosin refers to industrial resin rosin; Azodicarbonamide, CAS number 123-77-3; Polyethylene glycol 400, CAS number 25322-68-3.

[0034] In this invention, the units of measurement for all materials and solvents are uniformly referred to as parts by weight. Example

[0035] This embodiment provides a method for automatically adding and mixing auxiliary materials for an upward-drawing furnace, including the following steps: At 25°C, 40 parts by weight of flake graphite, 45 parts by weight of phosphorus copper pellets, 15 parts by weight of anhydrous borax, 14 parts by weight of rosin and 1.4 parts by weight of azodicarbonamide were added into a V-type mixer and mixed at 18 rpm for 12 minutes to obtain a dry homogeneous mixture.

[0036] The dry, homogeneous material was transferred to a double-arm kneader with a heat transfer oil jacket temperature of 145°C and kneaded at a spindle speed of 35 rpm for 18 minutes. Then, the heat transfer oil jacket temperature was increased to 218°C. After the material temperature in the kneading chamber reached 208°C and the foaming reaction was triggered, the spindle speed was reduced to 5 rpm and low-shear tumbling foaming was maintained at 208°C for 4 minutes to obtain a sponge-like porous plastic agglomerate.

[0037] The sponge-like porous plastic agglomerate is discharged and spread evenly on a crawler conveyor belt with forced cold air cooling. It is cooled to 35°C within 4 minutes to solidify the internal pore skeleton of the sponge-like porous plastic agglomerate to obtain a solid porous plate. The solid porous plate is fed into a toothed roller crusher and crushed into solid porous agglomerate particles with an average particle size of 5mm.

[0038] By driving a loss-in-weight weighing feeder, 100 parts by weight of solid porous agglomerates and 15 parts by weight of anhydrous borax are quantitatively fed into an automatic mixing hopper. The automatic mixing hopper is turned on and stirred at 30 rpm. At the same time, 5 parts by weight of polyethylene glycol 400 are atomized and sprayed into the automatic mixing hopper within 2 minutes by a liquid metering pump. After the polyethylene glycol 400 atomization and spraying is completed, stirring continues for 8 minutes. The liquid adhesion force of polyethylene glycol 400 is used to adhere the anhydrous borax to the surface of the solid porous agglomerates, thus obtaining the upper furnace composite auxiliary material.

[0039] Open the pneumatic discharge valve at the bottom of the automatic mixing hopper, and the composite auxiliary material for the upper furnace will be automatically conveyed and added to the surface of the molten metal pool of the upper furnace through a closed screw conveyor. Example

[0040] This embodiment provides a method for automatically adding and mixing auxiliary materials for an upward-drawing furnace, including the following steps: At 25°C, 35 parts by weight of flake graphite, 50 parts by weight of phosphorus copper pellets, 15 parts by weight of anhydrous borax, 12 parts by weight of rosin and 1.2 parts by weight of azodicarbonamide were added into a V-type mixer and mixed at 15 rpm for 10 min to obtain a dry homogeneous mixture.

[0041] The dry, homogeneous material was transferred to a double-arm kneader with a heat transfer oil jacket temperature of 140°C and kneaded at a spindle speed of 30 rpm for 15 minutes. Then, the heat transfer oil jacket temperature was increased to 215°C. After the material temperature in the kneading chamber reached 205°C and the foaming reaction was triggered, the spindle speed was reduced to 5 rpm and low-shear tumbling foaming was maintained at 205°C for 3 minutes to obtain a sponge-like porous plastic agglomerate.

[0042] The sponge-like porous plastic agglomerate is discharged and spread evenly on a crawler conveyor belt with forced cold air cooling. It is cooled to 30°C within 3 minutes to solidify the internal pore skeleton of the sponge-like porous plastic agglomerate to obtain a solid porous plate. The solid porous plate is fed into a toothed roller crusher and crushed into solid porous agglomerate particles with an average particle size of 4.5mm.

[0043] By driving a loss-in-weight weighing feeder, 90 parts by weight of solid porous agglomerates and 10 parts by weight of anhydrous borax are quantitatively fed into an automatic mixing hopper. The automatic mixing hopper is turned on and stirred at 25 rpm. At the same time, 3 parts by weight of polyethylene glycol 400 are atomized and sprayed into the automatic mixing hopper within 1 minute through a liquid metering pump. After the polyethylene glycol 400 atomization and spraying is completed, stirring is continued for 5 minutes. The liquid adhesion force of polyethylene glycol 400 is used to adhere the anhydrous borax to the surface of the solid porous agglomerates, thus obtaining the upper furnace composite auxiliary material.

[0044] Open the pneumatic discharge valve at the bottom of the automatic mixing hopper, and the composite auxiliary material for the upper furnace will be automatically conveyed and added to the surface of the molten metal pool of the upper furnace through a closed screw conveyor. Example

[0045] This embodiment provides a method for automatically adding and mixing auxiliary materials for an upward-drawing furnace, including the following steps: At 25°C, 45 parts by weight of flake graphite, 40 parts by weight of phosphorus copper pellets, 15 parts by weight of anhydrous borax, 16 parts by weight of rosin and 1.6 parts by weight of azodicarbonamide were added into a V-type mixer and mixed at 20 rpm for 15 minutes to obtain a dry homogeneous mixture.

[0046] The dry, homogeneous material was transferred to a double-arm kneader with a heat transfer oil jacket temperature of 150°C and kneaded at a spindle speed of 40 rpm for 20 minutes. Then, the heat transfer oil jacket temperature was increased to 220°C. After the material temperature in the kneading chamber reached 210°C and the foaming reaction was triggered, the spindle speed was reduced to 5 rpm and low-shear tumbling foaming was maintained at 210°C for 5 minutes to obtain a sponge-like porous plastic agglomerate.

[0047] The sponge-like porous plastic agglomerate is discharged and spread evenly on a crawler conveyor belt with forced cold air cooling. It is cooled to 40°C within 5 minutes to solidify the internal pore skeleton of the sponge-like porous plastic agglomerate to obtain a solid porous plate. The solid porous plate is fed into a toothed roller crusher and crushed into solid porous agglomerate particles with an average particle size of 8mm.

[0048] By driving a loss-in-weight weighing feeder, 110 parts by weight of solid porous agglomerates and 20 parts by weight of anhydrous borax are quantitatively fed into an automatic mixing hopper. The automatic mixing hopper is turned on and stirred at 35 rpm. At the same time, 7 parts by weight of polyethylene glycol 400 are atomized and sprayed into the automatic mixing hopper through a liquid metering pump within 3 minutes. After the polyethylene glycol 400 atomization and spraying is completed, stirring continues for 10 minutes. The liquid adhesion force of polyethylene glycol 400 is used to adhere the anhydrous borax to the surface of the solid porous agglomerates, thus obtaining the upper furnace composite auxiliary material.

[0049] Open the pneumatic discharge valve at the bottom of the automatic mixing hopper, and the composite auxiliary material for the upper furnace will be automatically conveyed and added to the surface of the molten metal pool of the upper furnace through a closed screw conveyor. Example

[0050] This embodiment provides a method for automatically adding and mixing auxiliary materials for an upward-drawing furnace, including the following steps: At 25°C, 42 parts by weight of flake graphite, 46 parts by weight of phosphorus copper pellets, 12 parts by weight of anhydrous borax, 15 parts by weight of rosin and 1.5 parts by weight of azodicarbonamide were added into a V-type mixer and mixed at 18 rpm for 13 minutes to obtain a dry homogeneous mixture.

[0051] The dry, homogeneous material was transferred to a double-arm kneader with a heat transfer oil jacket temperature of 145°C and kneaded at a spindle speed of 35 rpm for 18 minutes. Then, the heat transfer oil jacket temperature was increased to 218°C. After the material temperature in the kneading chamber reached 208°C and the foaming reaction was triggered, the spindle speed was reduced to 5 rpm and low-shear tumbling foaming was maintained at 208°C for 4 minutes to obtain a sponge-like porous plastic agglomerate.

[0052] The sponge-like porous plastic agglomerate is discharged and spread evenly on a crawler conveyor belt with forced cold air cooling. It is cooled to 35°C within 4 minutes to solidify the internal pore skeleton of the sponge-like porous plastic agglomerate to obtain a solid porous plate. The solid porous plate is fed into a toothed roller crusher and crushed into solid porous agglomerate particles with an average particle size of 6mm.

[0053] By driving a loss-in-weight weighing feeder, 105 parts by weight of solid porous agglomerates and 18 parts by weight of anhydrous borax are quantitatively fed into an automatic mixing hopper. The automatic mixing hopper is turned on and stirred at 32 rpm. At the same time, 6 parts by weight of polyethylene glycol 400 are atomized and sprayed into the automatic mixing hopper through a liquid metering pump within 2.5 minutes. After the polyethylene glycol 400 atomization and spraying is completed, stirring continues for 8 minutes. The liquid adhesion force of polyethylene glycol 400 is used to adhere the anhydrous borax to the surface of the solid porous agglomerates, thus obtaining the upper furnace composite auxiliary material.

[0054] Open the pneumatic discharge valve at the bottom of the automatic mixing hopper, and the composite auxiliary material for the upper furnace will be automatically conveyed and added to the surface of the molten metal pool of the upper furnace through a closed screw conveyor.

[0055] Comparative Example 1: Compared with Example 1, the difference is that: when feeding into the V-type mixer, no azodicarbonamide was added, and no obvious foaming and expansion phenomenon was observed after the same heating treatment. After cooling and crushing, low-porosity consolidated agglomerate particles were obtained. Everything else is the same.

[0056] Comparative Example 2: Compared with Example 1, the difference is that no rosin was added when the mixture was fed into the V-type mixer. After the same mixing, heating and cooling crushing process, no continuous solid coating matrix was formed, and loose mixed particles were obtained. Everything else was the same.

[0057] Comparative Example 3: Compared with Example 1, the difference is that after the material is kneaded in a double-arm kneader at 145°C for 18 minutes, it is directly discharged for cooling and crushing, without going through the stage of raising the temperature of the heat transfer oil jacket to trigger the foaming reaction, resulting in dense agglomerated particles without pre-foaming. All other aspects are the same.

[0058] Comparative Example 4: Compared with Example 1, the difference is that all the anhydrous borax fed into the V-type mixer and the automatic mixing hopper is replaced with sodium tetraborate decahydrate in equal amounts. Sodium tetraborate decahydrate undergoes dehydration and releases water of crystallization at high temperature. After the equal amount replacement, the effective anhydrous borate film-forming component is reduced, while the rest are the same.

[0059] Comparative Example 5: Compared with Example 1, the difference is that in the automatic mixing chamber, polyethylene glycol 400 is not sprayed in an atomized manner, and the solid porous agglomerated particles are simply stirred with anhydrous borax in a pure dry state, while the rest are the same.

[0060] Test Example 1: Dry homogeneous materials from Examples 1 and 2, after being mixed in a V-type mixer, were taken, pulverized at low temperature, and passed through a 60-mesh sieve. The uniform powder passing through the sieve was then taken as the sample to be tested.

[0061] Take 5 mg to 8 mg of the sample to be tested and place it in an alumina crucible. Place the alumina crucible in a thermogravimetric-differential scanning calorimeter. Under a nitrogen protective atmosphere, set the nitrogen flow rate to 50 mL / min and raise the temperature from 25 °C to 250 °C at a heating rate of 5 °C / min. Record the heat flow change data and mass loss data in the range of 100 °C to 230 °C.

[0062] A suitable sample was placed in the high-temperature test chamber of the parallel plate rotational rheometer. The parallel plate spacing was set to 1.5 mm. The temperature was continuously increased from 100 °C to 230 °C at a heating rate of 5 °C / min in a pure nitrogen atmosphere. The temperature was then applied for 10 seconds during the parallel plate rotational rheometer test. -1 At a constant shear rate, the apparent viscosity was recorded as a function of temperature.

[0063] Table 1: Test Results of Material Phase Change and Thermodynamic Parameters Temperature at the center of the rosin melting endothermic peak (°C) 142.3 144.1 Temperature at the center of the exothermic peak during foaming decomposition (°C) 206.8 204.2 Weight loss rate (%) during the foaming reaction zone 1.48 1.27 Apparent viscosity (Pa·s) at 150℃ 1845.6 2102.4 Apparent viscosity (Pa·s) at 215℃ 42105.3 39856.7 According to Table 1 and Figure 1 and Figure 2 It can be seen that the test sample exhibits a segmented thermal response and corresponding rheological state changes during the heating process. The curves in the figure provide a continuous trend of the heating process. As a supplement to the discrete node data in Table 1, the endothermic peaks that appear near 142.3℃ and 144.1℃ correspond to the phase change melting state change of industrial rosin from solid to liquid. Combined with the rheological curve data recorded in the test, the apparent viscosity decreases to 1845.6 Pa·s and 2102.4 Pa·s at 150℃, respectively. The rosin is transformed into a liquid phase, which facilitates the encapsulation of flake graphite and phosphor bronze pellets, providing steric hindrance conditions and physical coating basis for material kneading.

[0064] When the temperature rises above 204°C, an exothermic peak appears in the heat flow curve. The peak center temperature of the exothermic peak corresponds to 206.8°C in Example 1 and 204.2°C in Example 2, respectively. Within the range corresponding to the exothermic peak, there are mass losses of 1.48% and 1.27%. The thermodynamic behavior of the temperature range above 204°C mainly corresponds to the process of azodicarbonamide decomposition to produce gas, and is accompanied by the volatilization of a small amount of low-boiling components in rosin.

[0065] The range of thermodynamic exothermic peaks overlaps with the range of apparent viscosity increases. Due to the decomposition of azodicarbonamide producing a large number of microbubbles, the molten rosin system is transformed into a gas-liquid-solid multiphase foam structure, resulting in an abnormal increase in the apparent viscosity of the system.

[0066] At 215℃, the apparent viscosity increased to 42105.3 Pa·s and 39856.7 Pa·s, respectively. The increase in apparent viscosity helps to limit the rapid escape of decomposition gases, allowing the gases to expand in the matrix and form a porous framework. The test data shows that the foaming reaction range matches the viscosity increase range of the rosin matrix. By setting the kneading temperature and the foaming reaction triggering temperature, the corresponding thermodynamic and rheological properties can be obtained.

[0067] Test Example 2: The composite auxiliary materials for the upward drawing furnace prepared in Example 1, Comparative Example 2 and Comparative Example 5 were used as test samples.

[0068] Weigh 500g of each of the test samples from Example 1, Comparative Example 2 and Comparative Example 5, and put the different test samples into a transparent acrylic cylinder with an inner diameter of 100mm and a height of 400mm. Place the transparent acrylic cylinder on a standard vibration table, set the vibration frequency of the standard vibration table to 50Hz and the amplitude to 2mm, and vibrate continuously for 30min.

[0069] After the continuous vibration program ended, the material column inside the transparent acrylic cylinder was divided into three parts: upper, middle and lower. 10g samples were taken from each of the upper, middle and lower layers, and semi-quantitative normalized elemental distribution analysis was performed on the samples using X-ray fluorescence spectrometry. The normalized relative contents of copper and carbon elements in different layers were recorded to characterize the interlayer segregation trend of different density components after vibration.

[0070] Two kg of test samples from Example 1, Comparative Example 2, and Comparative Example 5 (which did not undergo vibration testing) were weighed respectively. The test samples that did not undergo vibration testing were allowed to fall freely from above a sealed drop pipe with a height of 3 m into the bottom collection bin. A dust concentration detection probe was set on the side wall of the bottom collection bin at a distance of 0.5 m from the bottom, and the peak data of PM10 suspended dust concentration during the dropping process were recorded.

[0071] Table 2: Results of Material Mechanical Vibration Segregation and Dust Concentration Tests Example 1 upper layer 40.2 36.8 12.4 Example 1 Middle layer 41.5 35.2 - Example 1 lower level 42.1 34.6 - Comparative Example 2 upper layer 12.5 68.3 345.8 Comparative Example 2 Middle layer 38.6 34.1 - Comparative Example 2 lower level 74.2 15.6 - Comparative Example 5 upper layer 37.6 39.2 86.5 Comparative Example 5 Middle layer 41.8 36.4 - Comparative Example 5 lower level 45.3 31.5 - According to Table 2 and Figure 3 and Figure 4 It can be seen that the distribution uniformity of different materials after forced vibration varies. The middle and lower layers of PM10 values ​​in Table 2 are marked with - because the dust concentration of falling material is a single environmental peak obtained by macroscopic spatial measurement of the entire falling material process, without distinguishing specific material column levels.

[0072] For Example 1, the normalized relative content fluctuations of copper and carbon in the upper, middle, and lower layers were minimal, indicating that the solid matrix formed by the rosin phase transition encapsulates the flake graphite and phosphor bronze pellets, limiting the relative displacement of components with different densities during vibration; simultaneously, the overall PM10 peak value was as low as 12.4 mg / m³. 3 In contrast, Comparative Example 2, which did not contain rosin, exhibited a clear gravitational stratification, with a significantly higher normalized relative content of copper in the lower layer and a significantly higher normalized relative content of carbon in the upper layer. Furthermore, the peak PM10 concentration increased to 345.8 mg / m³. 3 This indicates that granular materials may experience component migration and powder shedding.

[0073] In Comparative Example 5, after omitting polyethylene glycol 400, the normalized relative content range of the upper and lower layers increased compared to Example 1, and the PM10 peak value rose to 86.5 mg / m³. 3 The results show that the lack of external liquid assistance will cause the attached borax to peel off during collisions, which will reduce the stability of the distribution of anhydrous borax on the outer layer of the particles. Based on the comprehensive data test results, the method of using an internal phase change matrix combined with external liquid bridge coating has shown technical effectiveness in maintaining the consistency of the macroscopic proportion of materials and reducing dust from falling materials.

[0074] Test Example 3: The composite auxiliary materials for the upper drawing furnace prepared in Example 2, Example 3, Comparative Example 1 and Comparative Example 3 were taken as test samples respectively.

[0075] A high-purity graphite crucible with an inner diameter of 200 mm is placed in a protective atmosphere induction furnace. 15 kg of oxygen-free copper is melted in the high-purity graphite crucible, and the temperature of the copper liquid is maintained at 1150℃. A high-temperature resistant waveguide rod is rigidly connected to the upper part of the outer wall of the high-purity graphite crucible. A broadband acoustic emission sensor is connected to the end of the high-temperature resistant waveguide rod. The broadband acoustic emission sensor is connected to the acoustic emission signal acquisition system.

[0076] Before each test, the surface of the molten copper in the high-purity graphite crucible was cleaned, and then 50g of test sample was placed into the surface of the molten copper at 1150℃ through a directional feed tube. The moment the test sample came into contact with the surface of the molten copper was taken as the starting point of the timing. The acoustic emission signal acquisition system was used to continuously record the acoustic emission signal within 60 seconds, and the maximum acoustic emission amplitude and the cumulative acoustic emission energy value were extracted. The acoustic emission data were used to characterize the degree of melt impact caused by the vaporization expansion of the material.

[0077] While the test sample was being placed in the container, a high-temperature resistant timing device was used to record the time taken from the moment the test sample came into contact with the copper liquid surface until it dispersed and covered 80% of the copper liquid surface area in the high-purity graphite crucible. The time taken was recorded as the spreading and covering time.

[0078] Table 3: High-Temperature Kinetics and Acoustic Emission Test Results of Materials Example 2 43.6 1.15 6.4 Example 3 45.2 1.28 5.7 Comparative Example 1 91.8 8.64 36.2 Comparative Example 3 104.5 11.37 24.8 According to Table 3 and Figure 5 and Figure 6 It can be seen that the internal structure of the material has a direct impact on the contact reaction when it is put into the high-temperature melt. The test samples of Examples 2 and 3 showed low maximum acoustic emission amplitudes, such as 43.6dB and 45.2dB, after being put into molten copper at 1150℃. The acoustic emission waveforms were smooth, and the spreading coverage reached 80% within 6.4s and 5.7s, respectively.

[0079] The data above indicate that the pre-constructed porous structure provides an exhaust channel for the internal gas, mitigating the transient impact of the gas release process on the melt. The continuous gas flow also promotes the horizontal sliding and spreading of the material on the surface of the copper liquid.

[0080] In Comparative Example 1, which did not add foaming agent, due to the lack of pre-made porous channels, the volatile gases generated by the rosin matrix and organic components such as polyethylene glycol 400 under high temperature after being added to the copper liquid were difficult to be discharged in time, resulting in a sudden high amplitude peak of 91.8dB. There was a phenomenon of internal gas accumulation and rapid release through the outer shell, and the spreading time was extended to 36.2s. The material would agglomerate and clump on the liquid surface.

[0081] The test sample of Comparative Example 3 contained azodicarbonamide that did not trigger the foaming reaction in advance. After being heated, it underwent concentrated decomposition, producing a delayed burst peak of up to 104.5 dB. The test results show that the process design of the pre-fabricated porous structure can reduce the tendency of molten pool splashing during high-temperature feeding and improve the liquid surface spreading efficiency of the auxiliary materials.

[0082] Test Example 4: The composite auxiliary materials for the upward furnace prepared in Examples 1, 3, 4, 2, and 4 were used as test samples.

[0083] A silicon carbide graphite crucible with an inner diameter of 300 mm was placed in a medium-frequency induction melting furnace. 50 kg of high-purity cathode copper raw material was melted in the silicon carbide graphite crucible. The heating power was adjusted to maintain the temperature of the copper liquid at 1180℃. A trace amount of oxygen was slowly introduced into the copper liquid so that the initial oxygen mass fraction of the copper liquid reached the reference range of 60 ppm to 65 ppm.

[0084] 500g of test sample was evenly added to the surface of molten copper in a silicon carbide graphite crucible, and the time point when the test sample was added was recorded as the starting point of timing. At 15 minutes, 30 minutes, 45 minutes and 60 minutes after the test sample was added, quartz vacuum sampling tubes were used to extract molten copper samples from a depth of 100mm below the liquid surface, and the extracted molten copper samples were quickly quenched with water.

[0085] The oxygen mass fraction in the water-quenched copper sample was determined using an oxygen, nitrogen, and hydrogen analyzer, and the oxygen mass fraction values ​​inside the copper liquid at different time points were recorded. In addition, a water-quenched copper sample was taken at 60 minutes, and the residual phosphorus mass fraction in the copper sample was determined using an inductively coupled plasma atomic emission spectrometer, and the conductivity of the copper sample was determined using a conductivity meter. After the sampling procedure is completed at 60 minutes, the remaining cover residue on the liquid surface is collected, cooled, weighed, and the carbon element mass in the cover residue is tested. Combined with the initial total carbon element mass when the test sample is put in, the carbon element oxidation loss rate under 60 minutes of continuous heat preservation is calculated.

[0086] Table 4: Test Results of Material Melt Deoxidation Performance, Coating Layer Consumption, and Copper Sample Quality Indicators Example 1 63.2 14.5 8.7 12.4 1.8 101.6 Example 3 61.5 13.8 7.8 11.2 2.1 101.5 Example 4 62.1 13.2 7.4 10.8 2.5 101.5 Comparative Example 2 64.1 42.6 58.4 54.3 <1.0 100.8 Comparative Example 4 62.8 25.4 35.2 38.6 1.2 101.0 According to Table 4 and Figure 7 and Figure 8 It can be seen that the composition structure of the composite auxiliary material directly affects the deoxidation effect and coverage durability of the high-temperature copper liquid. In Examples 1, 3 and 4, after the copper liquid was added, the oxygen mass fraction of the copper liquid dropped to below 15 ppm within 15 minutes and stabilized below 9 ppm after 60 minutes. Moreover, the carbon element oxidation loss rate was controlled within 13%. The data shows that anhydrous borax melts at high temperature to form a liquid film, filling the physical pores between the flake graphite particles and restricting the diffusion of air into the melt. The above-mentioned barrier effect reduces the oxidation consumption of carbon elements and provides a relatively stable reducing liquid surface environment for the sedimentation and deoxidation of phosphorus copper pellets.

[0087] By comparing with the comparative examples, Comparative Example 2, which did not add rosin matrix, was in a loose powder state and would be pulverized and consumed after addition. The carbon element oxidation and burn-off rate reached 54.3% after 60 minutes, making it difficult to maintain the deoxidation and covering functions. Comparative Example 4 used sodium tetraborate decahydrate to replace anhydrous borax in an equal amount. At 60 minutes, obvious secondary oxidation occurred, indicating that sodium tetraborate decahydrate removes crystal water and releases water vapor at high temperature. On the one hand, it reduces the effective amount of anhydrous borates to form a film under the same addition conditions. On the other hand, it destroys the continuity and stability of the covering layer, causing the flake graphite to be oxidized and consumed, resulting in a thinner physical covering layer and a weakened oxygen barrier function.

[0088] Based on the comprehensive test results, the structural design of using anhydrous borax to form a film and flake graphite to form a composite barrier, combined with the chemical deoxidation of phosphorus copper pellets, can reduce the oxygen content of the copper liquid while extending the melt protection time. Combined with the residual phosphorus mass fraction maintained below 3 ppm and the copper sample conductivity maintained at 101.5% IACS or above, it can be seen that the auxiliary material preparation and addition method provided in this application can reduce the probability of excessive phosphorus elements negatively affecting the high conductivity of oxygen-free copper while achieving deep deoxidation.

[0089] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A method for automatically adding and mixing auxiliary materials in an upward-drawing furnace, characterized in that, The method includes the following steps: Flake graphite, copper phosphate pellets, anhydrous borax, rosin, and azodicarbonamide are mixed evenly to obtain a dry, homogeneous mixture. The dry, homogeneous material is transferred to a double-arm kneader with a heated jacket, where it is first kneaded by the main shaft. Then, the jacket temperature is increased to the temperature that triggers the foaming reaction, and the rotation speed is reduced to allow for tumbling and foaming, resulting in a sponge-like porous plastic mass. The sponge-like porous plastic agglomerate is discharged and cooled to solidify the internal pore skeleton to obtain a solid porous plate. The solid porous plate is then crushed into solid porous agglomerate particles. By driving a loss-in-weight weighing feeder, the quantitatively conveyed solid porous agglomerates and anhydrous borax are stirred in an automatic mixing bin, while polyethylene glycol 400 is sprayed in an atomized manner for coating and mixing, thus obtaining the upper furnace composite auxiliary material. The composite auxiliary material for the upward furnace is automatically conveyed and added to the surface of the molten metal pool in the upward furnace using a conveying device.

2. The method for automatic addition and mixing of auxiliary materials for an upward-drawing furnace according to claim 1, characterized in that, The dry homogeneous material is prepared by mixing raw materials comprising the following parts by weight: Flake graphite: 35 to 45 parts by weight; Phosphorus copper pellets: 40 to 50 parts by weight; Anhydrous borax: 12 to 15 parts by weight; Rosin: 12 to 16 parts by weight; Azodicarbonamide: 1.2 to 1.6 parts by weight.

3. The method for automatic addition and mixing of auxiliary materials for an upward-drawing furnace according to claim 1, characterized in that, When preparing the composite auxiliary material for the upper drawing furnace, the material undergoing coating and mixing comprises the following parts by weight: Solid porous agglomerated particles: 90 to 110 parts by weight; Anhydrous borax: 10 to 20 parts by weight; Polyethylene glycol 400: 3 to 7 parts by weight.

4. The method for automatic addition and mixing of auxiliary materials for an upward-drawing furnace according to claim 1, characterized in that, When the material is mixed evenly to obtain a dry homogeneous mixture, it is put into a mixer at 25°C, the speed is set to 15 to 20 rpm, and the mixture is continuously mixed for 10 to 15 minutes.

5. The method for automatic addition and mixing of auxiliary materials for an upward-drawing furnace according to claim 1, characterized in that, During the main shaft kneading process in the double-arm kneader, the jacket temperature is controlled at 140 to 150°C, the main shaft speed is 30 to 40 rpm, and the kneading continues for 15 to 20 minutes. During the tumbling and foaming process, the jacket temperature is raised to 215 to 220°C and the material temperature in the kneading chamber is raised to 205 to 210°C. The spindle speed is reduced to 5 rpm and foaming continues for 3 to 5 minutes.

6. The method for automatic addition and mixing of auxiliary materials for an upward-drawing furnace according to claim 1, characterized in that, When the sponge-like porous plastic agglomerate is discharged and cooled, it is spread flat on a conveyor belt with forced cold air cooling and cooled to 30 to 40°C within 3 to 5 minutes. When crushing the solid porous plate, a toothed roller crusher is used to crush the solid porous plate into solid porous agglomerated particles with an average particle size of 4.5 to 8 mm.

7. The method for automatic addition and mixing of auxiliary materials for an upward-drawing furnace according to claim 1, characterized in that, The stirring speed in the automatic mixing chamber is 25 to 35 rpm, and the atomized spraying of polyethylene glycol 400 is completed within 1 to 3 minutes by a liquid metering pump. After the spraying is completed, the coating and mixing continues for 5 to 10 minutes. During the automatic conveying and addition process, the pneumatic discharge valve at the bottom of the automatic mixing hopper is opened, and the composite auxiliary material for the upper furnace is automatically conveyed and added via a closed screw conveyor.

8. The method for automatic addition and mixing of auxiliary materials for an upward-drawing furnace according to claim 1, characterized in that, By performing the coating and mixing process, the anhydrous borax is adhered to the surface of the solid porous agglomerated particles using the liquid adhesion force of polyethylene glycol 400, thereby obtaining the upper furnace composite auxiliary material with an anhydrous borax surface adhesion structure.

9. The method for automatic addition and mixing of auxiliary materials for an upward-drawing furnace according to claim 1, characterized in that, During the agitation and foaming process and the discharge and cooling process, the material undergoing the foaming reaction is formed into a sponge-like porous plastic agglomerate, and the internal pore skeleton of the sponge-like porous plastic agglomerate is solidified to obtain the solid porous board with a solidified pore skeleton structure.

10. The method for automatic addition and mixing of auxiliary materials for an upward-drawing furnace according to claim 1, characterized in that, The phosphorus-copper pellets used in the dry homogenized material have a phosphorus mass fraction of 8.0% to 15.0% and an apparent density of 7.8 to 8.2 g / cm³. 3 The particle diameter is 1.5 to 3.0 mm; the rosin used in the dry homogeneous material is industrial resin rosin.

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