Inert gas bottom blowing smelting process for red copper slab

Abstract

This invention relates to the field of copper flat ingot smelting technology, and in particular to an inert gas bottom-blowing smelting process for copper flat ingots. Copper raw materials are placed in a smelting furnace and melted at a constant temperature. The resulting molten copper is then transferred to a holding furnace; a composite anti-seepage ventilation component is pre-installed at the bottom of the holding furnace. Inert gas is blown into the bottom of the molten copper through the composite anti-seepage ventilation component, dispersing it into microbubbles. Dissolved hydrogen continuously diffuses into the bubbles under partial pressure and is effectively carried out as the bubbles rise. After the inert gas rises to the surface of the molten copper, it forms a continuous, sealed protective gas layer, preventing air from contacting the molten copper. After temperature compensation, the molten copper is fed into a casting machine and cast into copper flat ingots according to a preset process. Through the combined effect of the slow rise of microbubbles and the inert gas layer on the liquid surface, the molten copper is thoroughly purified and has high purity, eliminating porosity defects in the ingots at their source and ensuring that the resulting copper flat ingots have a dense structure and are free of porosity defects.

Description

Technical Field

[0001] This invention relates to the field of copper flat ingot smelting technology, and in particular to an inert gas bottom-blowing smelting process for copper flat ingots. Background Technology

[0002] During the smelting and casting process of copper flat ingots, the molten copper readily absorbs gases such as hydrogen. When solidified, the released gas will form pores inside the ingot, which can easily lead to defects such as peeling and bubbles after subsequent pressure processing such as rolling and extrusion.

[0003] Traditional copper smelting typically involves covering the surface of molten copper with charcoal powder for protection. This method only isolates the surface of the molten copper from the air and cannot remove the dissolved hydrogen inside the copper. As a result, the degassing and purification effect is poor, and it is difficult to fundamentally solve the porosity problem.

[0004] To achieve degassing and purification of molten copper, the industry has attempted bottom-blowing purification using inert gas. However, due to the limitations of conventional aeration devices, it is difficult to form uniform and stable microbubbles in the molten copper. The gas rises rapidly, has a short mass transfer time with the melt, resulting in insufficient degassing and easily causing melt agitation and oxidation. Especially under conditions of high raw material moisture and high gas content, it is still impossible to reliably eliminate ingot porosity defects.

[0005] Therefore, it is urgent for technical personnel to solve the above problems. Summary of the Invention

[0006] The purpose of this invention is to provide an inert gas bottom-blowing smelting process for copper flat ingots, which aims to solve the problems in existing copper smelting processes where charcoal powder covering cannot remove hydrogen from the inside of the copper liquid, and where inert gas bottom blowing is limited by the ventilation device, making it difficult to form uniform microbubbles and resulting in insufficient degassing.

[0007] This invention relates to an inert gas bottom-blowing smelting process for copper flat ingots, comprising the following steps: S1. Put the copper raw material into the smelting furnace, keep it at a constant temperature and melt it to obtain copper liquid with uniform composition; S2. Transfer the molten copper to the holding furnace, and fix the bottom of the holding furnace with a composite anti-seepage and ventilation component consisting of a gas amplifier and permeable sand. The temperature of the molten copper in the holding furnace is maintained at 1120-1180℃. S3. Inert gas is blown into the bottom of the copper liquid through the composite anti-seepage and ventilation component. After being dispersed by the component, the inert gas forms microbubbles and floats slowly in the copper liquid. S4. Inert gas rises to the surface of the molten copper and forms an insulating layer; S5. Before sending the purified copper liquid into the casting machine, perform temperature compensation on the copper liquid to raise the temperature of the copper liquid to 1180-1200℃. S6. The copper liquid after temperature compensation is sent into the casting machine and cast according to the preset process to obtain copper flat ingots.

[0008] As a further improvement to the technical solution disclosed in this invention, in S2, the gas amplifier is preferably a ceramic sintered porous body with three-dimensional interconnected capillary channels formed inside, and the pore size is controlled between 12 and 18 μm.

[0009] As a further improvement to the technical solution disclosed in this invention, the gas amplifier is preferably fixed to the bottom of the heat preservation furnace by an embedded installation method, with its upper end face flush with the refractory layer of the bottom of the heat preservation furnace, and arranged in two staggered rows along the width direction of the bottom of the heat preservation furnace.

[0010] As a further improvement to the technical solution disclosed in this invention, the breathable sand is made of alumina and zirconium oxide in a mass ratio of 85:15 to 95:5. During preparation, the alumina and zirconium oxide raw materials are mixed evenly, pressed into shape, and covered on top of the gas amplifier. After molding, the thickness of the breathable sand is distributed in a gradient, with a thickness of 60 to 80 mm in the central area and a thickness of 30 to 50 mm in the edge area.

[0011] As a further improvement to the technical solution disclosed in this invention, an organic pore-forming agent and a high-temperature stabilizer are added to the mixed raw materials of alumina and zirconium oxide; the amount of organic pore-forming agent is 0.5% to 2% of the total mass of the mixed raw materials, and the amount of high-temperature stabilizer is 0.1% to 1% of the total mass of the mixed raw materials; after addition, the mixture is uniformly mixed, pressed into shape, and then sintered at a high temperature of 1400 to 1520°C to form gradient micro-pores.

[0012] As a further improvement to the technical solution disclosed in this invention, in S3, the bottom-blown argon gas adopts a segmented gas supply control mode: the initial pressure is 4-5 bar and the flow rate is 3-5 L / min, the later pressure is 3-4 bar and the flow rate is 1-2 L / min, and the total heat preservation and standing time is 20-45 min.

[0013] As a further improvement to the technical solution disclosed in this invention, the hydrogen content of the copper liquid is monitored in real time during the bottom blowing process. When the hydrogen concentration drops below 0.1 ml / 100 g Cu, the gas supply is stopped and the copper liquid enters the constant temperature stabilization stage.

[0014] As a further improvement to the technical solution disclosed in this invention, in S6, the casting adopts a multi-stage temperature control and variable speed method: the initial temperature is 1180~1200℃ and the casting speed is 80~120mm / min, and the later temperature is 1130~1160℃ and the casting speed is 50~80mm / min.

[0015] In practical applications, the inert gas bottom-blowing smelting process for copper flat ingots disclosed in this invention can achieve at least the following beneficial technical effects, specifically: 1) A composite seepage-proof and ventilated component consisting of a gas amplifier and permeable sand can uniformly disperse inert gas into a large number of microbubbles. Furthermore, the relatively high density of inert gases (e.g., argon) causes the bubbles to float slowly in the molten copper, significantly extending the gas-liquid contact and mass transfer time. Additionally, the partial pressure of dissolved hydrogen in the molten copper is higher than that inside the bubbles, causing dissolved hydrogen to continuously diffuse and migrate into the bubbles. As the bubbles rise, they continuously collect hydrogen and carry it out of the melt, achieving deep degassing and purification of the molten copper. 2) After the inert gas rises to the surface of the molten copper, it forms a continuous and stable inert gas layer, which can effectively isolate the air and prevent the melt from absorbing gas and oxidizing. In addition, with precise temperature control of the holding furnace and pre-casting temperature compensation, the purity and casting fluidity of the molten copper can be effectively maintained, and finally, a dense, non-porous, and excellent machinable copper flat ingot can be obtained. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic diagram of the structure of the heat preservation furnace disclosed in this invention.

[0018] 1-Furnace lining; 2-Electric heating element; 3-Composite anti-seepage and ventilation component; 31-Gas amplifier; 32-Permeable sand; 4-Gas supply pipe. Detailed Implementation

[0019] The technical solution disclosed in this invention will be further described in detail below with reference to specific embodiments. The copper flat ingot is smelted using an inert gas bottom-blowing process with multi-step process synergistic control to achieve deep degassing of the copper melt, uniform temperature and composition, absence of secondary oxidation, and absence of porosity defects. Specific embodiments are as follows: Example 1 The inert gas bottom-blowing smelting process for copper flat ingots specifically includes the following steps: S1. Put the copper raw material into the smelting furnace, keep it at a constant temperature and melt it to obtain copper liquid with uniform composition; S2. Transfer the molten copper to a holding furnace (e.g., Figure 1 As shown in the figure, the heat preservation furnace has a furnace lining 1 as the main structure, and an electric heating element 2 is provided on the outer wall of the furnace lining 1. The temperature is controlled by the electric heating element 2 to maintain the temperature of the copper liquid in the heat preservation furnace at 1120℃. The furnace bottom is completely sealed, and a pre-embedded composite anti-seepage and ventilation component 3 consisting of a gas amplifier 31 and a permeable sand 32 is pre-fixed; and neither the gas amplifier 31 nor the permeable sand 32 is in direct contact with the molten copper. Among them, the gas amplifier 31 is a ceramic sintered porous body with three-dimensional interconnected capillary channels inside, with a pore size of 12μm. Its upper end face is flush with the refractory layer at the bottom of the furnace and is arranged in two staggered rows along the width direction of the bottom of the furnace. The permeable sand 32 is made of alumina and zirconium oxide in a mass ratio of 85:15, with 0.5% organic pore-forming agent and 0.1% high-temperature stabilizer added by total mass. The organic pore-forming agent is activated carbon, and the high-temperature stabilizer is yttrium oxide. After being mixed evenly, it is pressed into shape and sintered at 1500℃ to form a gradient micro-air gap structure. The permeable sand 32 covers the gas amplifier 31, with a thickness of 60-80mm in the central area and 30-50mm in the edge area. The gradient thickness design is adopted to adapt to the requirements of seepage prevention and gas dispersion. The upper surface of the permeable sand 32 is coated with a high-temperature seepage prevention coating to prevent copper liquid from seeping and clogging. The bottom blowing system is equipped with a pulse backflushing device, which can periodically perform pulse backflushing to clean the permeable sand and gas amplifier. S3. Argon gas is supplied to the composite anti-seepage ventilation component 3 through the gas supply pipe 4, and argon gas is blown into the bottom of the copper liquid. The argon gas is dispersed in multiple stages to form uniform microbubbles. The bubbles float slowly in the copper liquid to prolong the gas-liquid mass transfer time. A segmented gas supply control mode is adopted: the pressure is 4 bar and the flow rate is 3 L / min in the early stage, and the pressure is 3 bar and the flow rate is 1 L / min in the later stage. The total heat preservation and standing time is 20 min. The hydrogen content of the copper liquid is monitored in real time during the bottom blowing process. When the hydrogen concentration drops below 0.1 ml / 100 g Cu, the gas supply is stopped and the copper liquid enters the constant temperature stabilization stage. S4. Argon bubbles continuously rise to the surface of the molten copper, forming a continuous and sealed inert gas isolation layer, which effectively isolates air and prevents the molten copper from absorbing gas and oxidizing again; the furnace maintains a slight positive pressure of 100-300 Pa to enhance the stability of the inert gas layer. S5. Before sending the purified copper liquid into the casting machine, the copper liquid is heated to compensate by resistance heating or induction heating at a rate of 5-15℃ / min, so that the temperature of the copper liquid is raised to 1180-1200℃, and held for 5-10 minutes for homogenization. S6. The copper liquid after temperature compensation is fed into the casting machine and cast using a multi-stage temperature control and variable speed method: the initial temperature is 1180~1200℃ and the casting speed is 80~120mm / min, and the later temperature is 1130~1160℃ and the casting speed is 50~80mm / min, to obtain copper flat ingots.

[0020] Example 2 The process steps in this embodiment are basically the same as those in Embodiment 1, with the only differences being as follows: In S2, the temperature of the molten copper in the holding furnace is maintained at 1150℃; the three-dimensional interconnected capillary channels inside the gas amplifier 31 have a pore size of 15μm; the permeable sand 32 is made of alumina and zirconium oxide in a mass ratio of 90:10, with 1.2% organic pore-forming agent and 0.5% high-temperature stabilizer added by mass; the organic pore-forming agent is activated carbon, and the high-temperature stabilizer is yttrium oxide; gradient micro-air gaps are formed by high-temperature sintering at 1500℃; the thickness of the permeable sand 32 in the central area is 60-80mm, the thickness of the edge area is 30-50mm, and the upper surface is coated with a high-temperature anti-seepage coating; the bottom blowing system is equipped with a pulse backflushing device; In S3, the segmented gas supply control mode is adjusted as follows: initial pressure 4.5 bar, flow rate 4 L / min, subsequent pressure 3.5 bar, flow rate 1.5 L / min, total heat preservation and settling time 30 min; In S4, a slight positive pressure of 100-300 Pa is maintained inside the insulation furnace to enhance the sealing effect of the inert gas layer.

[0021] Example 3 The process steps in this embodiment are basically the same as those in Embodiment 1, with the only differences being as follows: In S2, the temperature of the molten copper in the holding furnace is maintained at 1180℃; the furnace bottom is completely sealed to prevent furnace leakage and gas leakage; the three-dimensional interconnected capillary channels inside the gas amplifier 31 have a pore size of 18μm; the permeable sand 32 is made of alumina and zirconium oxide in a mass ratio of 95:5, with 2% organic pore-forming agent and 1% high-temperature stabilizer added by mass; the organic pore-forming agent is activated carbon, and the high-temperature stabilizer is yttrium oxide; it is sintered at 1500℃ to form gradient micro-gaps; the thickness of the permeable sand 32 in the central area is 60-80mm, the thickness of the edge area is 30-50mm, and the upper surface is coated with a high-temperature anti-seepage coating; the bottom blowing system is equipped with a pulse backflushing device; In S3, the segmented gas supply control mode is adjusted to: initial pressure 5 bar, flow rate 5 L / min, later pressure 4 bar, flow rate 2 L / min, and total heat preservation and static time 45 min; after the argon gas is dispersed by the composite anti-seepage ventilation component 3, a large number of uniform microbubbles are formed. The bubbles slowly float to achieve deep mass transfer, which can adsorb hydrogen, oxygen and oxidative impurities and carry them to the liquid surface for removal. In S4, a slight positive pressure of 100-300 Pa is maintained inside the insulation furnace to ensure a continuous and stable inert gas layer and prevent air entrapment.

[0022] Comparative Example 1 This comparative example uses a traditional charcoal powder covering and smelting method, and the specific steps are as follows: S1. Put the copper raw material into the smelting furnace, keep it at a constant temperature and melt it to obtain copper liquid with uniform composition; S2. Transfer the molten copper to a holding furnace and cover the surface of the molten copper with charcoal powder; S3. Let the copper liquid stand for 30 minutes. S4. Heat the molten copper to 1180-1200℃ before sending it into the casting machine; S5. Copper flat ingots are produced using conventional casting parameters.

[0023] Comparative Example 2 This comparative example uses a standard industry-standard aeration device for bottom-blowing argon treatment. However, due to the limitations of this device's structure, it's difficult to form uniform and stable microbubbles in the molten copper. The gas rises rapidly, has a short mass transfer time with the melt, resulting in insufficient degassing and potential for melt agitation and oxidation. The specific steps are as follows: S1. Put the copper raw material into the smelting furnace, keep it at a constant temperature and melt it to obtain copper liquid with uniform composition; S2. Transfer the molten copper to a holding furnace. A standard industry-standard ventilation device is installed at the bottom of the holding furnace to maintain the temperature of the molten copper at 1150℃. The standard ventilation device is a single ceramic vent plug structure, made of alumina ceramic sintered at 1200℃. It is cylindrical in shape, with a diameter of 30mm and a height of 50mm. The lower end is welded and fixed to the air inlet pipe, and the upper end protrudes 10mm from the refractory layer of the furnace bottom, directly contacting the molten copper. The internal capillary channels of the vent plug have a diameter of 25-30μm and are arranged in a single row along the width of the furnace bottom, with an 80mm spacing between adjacent vent plugs. S3. Argon gas is blown into the bottom of the copper liquid through a conventional ventilation device, and conventional gas supply parameters and holding time are used. S4. Argon bubbles rise to the surface of the molten copper and form a gas layer. S5. Before sending the molten copper into the casting machine, the temperature is increased to 1180-1200℃; S6. Copper flat ingots are produced using conventional casting parameters.

[0024] The performance of the copper flat ingots prepared in Examples 1-3 and Comparative Examples 1 and 2 was tested. The test standards and results are shown in the table below: Test results show that the copper flat ingots prepared in Examples 1 to 3 are significantly superior to Comparative Example 1 and Comparative Example 2 in terms of degassing effect, internal quality, and mechanical properties. The optimization effects of each indicator are clear and logically consistent, as shown in the following details: In terms of degassing effect, the hydrogen content of the copper flat ingots prepared in Examples 1 to 3 was consistently reduced to below 0.1 ml / 100g Cu, which is much lower than 0.82 ml / 100g Cu in Comparative Example 1 and 0.45 ml / 100g Cu in Comparative Example 2. The degassing efficiency and effect were significantly improved. In terms of internal quality, the porosity level of the copper flat ingots in Examples 1 to 3 was consistently controlled at level 2. Compared with level 5 in Comparative Example 1 and level 3 in Comparative Example 2, defects such as internal porosity were greatly improved, effectively reducing the internal defect rate of copper ingots. In terms of mechanical properties, the copper flat ingots of Examples 1 to 3 all have a tensile strength of over 210 MPa and an elongation of over 32%, which are significantly improved compared to Comparative Example 1 (tensile strength 185 MPa, elongation 20%) and Comparative Example 2 (tensile strength 202 MPa, elongation 27%). The overall mechanical properties are better and can better meet the needs of subsequent processing and use.

[0025] The above description of the disclosed embodiments enables those skilled in the art to make or use the invention. Various modifications to these embodiments will be readily apparent to those skilled in the art, and the general principles defined herein may be implemented in other embodiments without departing from the spirit or scope of the invention. Therefore, the invention is not to be limited to the embodiments shown herein, but is to be accorded the widest scope consistent with the principles and novel features disclosed herein.

Claims

1. An inert gas bottom-blowing smelting process for copper flat ingots, characterized in that, Includes the following steps: S1. Put the copper raw material into the smelting furnace, keep it at a constant temperature and melt it to obtain copper liquid with uniform composition; S2. Transfer the molten copper to the holding furnace, and fix the bottom of the holding furnace with a composite anti-seepage and ventilation component consisting of a gas amplifier and permeable sand. The temperature of the molten copper in the holding furnace is maintained at 1120-1180℃. S3. Inert gas is blown into the bottom of the copper liquid through the composite anti-seepage and ventilation component. After being dispersed by the component, the inert gas forms microbubbles and slowly floats to the top of the copper liquid. S4. Inert gas rises to the surface of the molten copper and forms an insulating layer; S5. Before sending the purified copper liquid into the casting machine, perform temperature compensation on the copper liquid to raise the temperature of the copper liquid to 1180-1200℃. S6. The copper liquid after temperature compensation is sent into the casting machine and cast according to the preset process to obtain copper flat ingots.

2. The inert gas bottom-blowing smelting process for copper flat ingots according to claim 1, characterized in that, In S2, the gas amplifier is a sintered ceramic porous body with three-dimensional interconnected capillary channels inside, and the pore size is controlled between 12 and 18 μm.

3. The inert gas bottom-blowing smelting process for copper flat ingots according to claim 2, characterized in that, The gas amplifier is fixed to the bottom of the heat preservation furnace by an embedded installation method. Its upper end surface is flush with the refractory layer of the bottom of the heat preservation furnace, and it is arranged in two staggered rows along the width direction of the bottom of the heat preservation furnace.

4. The inert gas bottom-blowing smelting process for copper flat ingots according to claim 3, characterized in that, The breathable sand is made of alumina and zirconium oxide in a mass ratio of 85:15 to 95:

5. During preparation, the alumina and zirconium oxide raw materials are mixed evenly, pressed into shape, and covered on top of the gas amplifier. After molding, the thickness of the breathable sand is distributed in a gradient.

5. The inert gas bottom-blowing smelting process for copper flat ingots according to claim 4, characterized in that, An organic pore-forming agent and a high-temperature stabilizer are added to the mixed raw material of alumina and zirconium oxide; the amount of the organic pore-forming agent is 0.5% to 2% of the total mass of the mixed raw material, and the amount of the high-temperature stabilizer is 0.1% to 1% of the total mass of the mixed raw material; after addition, the mixture is uniformly mixed, pressed into shape, and then sintered at a high temperature of 1400 to 1520°C to form a gradient micro-pore.

6. The inert gas bottom-blowing smelting process for copper flat ingots according to claim 1, characterized in that, In S3, the bottom-blown argon gas adopts a segmented gas supply control mode: the initial pressure is 4-5 bar and the flow rate is 3-5 L / min, the later pressure is 3-4 bar and the flow rate is 1-2 L / min, and the total heat preservation and standing time is 20-45 min.

7. The inert gas bottom-blowing smelting process for copper flat ingots according to claim 6, characterized in that, During bottom blowing, the hydrogen content of the copper liquid is monitored in real time. When the hydrogen concentration drops below 0.1 ml / 100 g Cu, the gas supply is stopped and the copper liquid enters the constant temperature stabilization stage.

8. The inert gas bottom-blowing smelting process for copper flat ingots according to claim 1, characterized in that, In S6, the casting adopts a multi-stage temperature control and variable speed method: the initial temperature is 1180~1200℃ and the casting speed is 80~120mm / min, and the later temperature is 1130~1160℃ and the casting speed is 50~80mm / min.

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