CN100471969C - A kind of 3104 aluminum alloy flat ingot casting furnace ventilation degassing and slag refining method - Google Patents

Abstract

The invention relates to a smelting exhaust slag removal method, in particular to a 3104 aluminum alloy flat ingot casting furnace ventilation degassing and slag removal refining method. The method for refining 3104 aluminum alloy flat ingot casting furnace by ventilation, degassing and slag removal comprises a tiltable holding furnace, 13 ventilation bricks built on the furnace bottom refractory material structure, and 13 ventilation pipelines arranged at the bottom of the furnace. The ventilation degassing and slag removal refining method is to introduce an inert gas or an inert mixed gas into the holding furnace through the ventilation pipeline installed under the 13 ventilation bricks at the bottom of the furnace, and the inert gas absorbs impurities in the aluminum liquid and floats up with the bubbles Exhaust to the surface of molten aluminum to obtain the refined product of the present invention. The invention has the advantages of improving the efficiency of degassing and slag removal, improving the refining effect in the furnace, improving the product quality of aluminum alloy slabs, reducing the casting defects of slabs, reducing the production cost of slabs, increasing productivity and reducing the use of slabs. gas flow. The invention is applicable to the aluminum and aluminum alloy casting industry.

Description

A kind of 3104 aluminum alloy flat ingot casting furnace ventilation degassing and slag refining method

technical field

The invention relates to a smelting degassing and slag removal method, in particular to a 3104 aluminum alloy flat ingot casting furnace ventilation degassing and slag refining method.

Background technique

In the production process of aluminum alloy ingots in the electrolytic aluminum plant, due to the large inclusions of the furnace charge and electrolytic primary aluminum, and the gas absorbed by the aluminum liquid during the transfer, smelting, and pouring process, the purity of the alloy liquid is reduced and the fluidity is deteriorated. It will cause a variety of casting defects in castings (ingots), mainly manifested as large inclusions, diffuse inclusions, subcutaneous pores and pores at the concentrated riser inside the ingot, which affects the mechanical and processing properties of the ingot, as well as corrosion resistance. Airtight performance, anodic oxidation performance and appearance quality. In the production of aluminum alloy slabs, the existing refining technology in the furnace is mainly based on artificial blowing, using two blowing pipes to directly blow the refining gas from the furnace door into the molten aluminum. The blowing time is long, the burning loss of alloy elements is large, the degassing and slag removal effects are poor, the labor intensity is extremely high, the product quality is low, the product yield is only about 60%, there are many casting defects, and the crack tendency of the flat ingot is large, which is not conducive to mass production. Automated manufacturing.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art, and provide a method of using inert gas such as nitrogen or argon as a carrier to absorb and refine the aluminum alloy slab before casting, so that the hydrogen bubbles float to the surface of the aluminum liquid to achieve A refining method for air-breathing, degassing, and slag removal in a 3104 flat ingot casting furnace for improving the purity of aluminum alloy liquid by degassing and slag removal.

The refinement method of the 3104 aluminum alloy flat ingot casting furnace with ventilation, degassing and slag removal is realized by the following technical scheme: the refining method of the 3104 aluminum alloy flat ingot casting furnace with ventilation, degassing and slagging removal includes a tiltable holding furnace, It is composed of 13 air-permeable bricks built on the furnace bottom refractory structure and 13 ventilation pipes are arranged at the furnace bottom. Inert gas or inert mixed gas is introduced into the furnace. The inert gas absorbs the oxidized slag, harmful gas and other impurities in the molten aluminum, and then adheres to the surface of the bubbles and rises to the surface of the molten aluminum with the bubbles to exhaust. The waste slag in the liquid is scraped out, and the technological conditions are as follows: the air flow rate of each air-permeable brick is 3-45Nl/min, the air-permeable pressure is 3Pa, and the refining time is 15-40 minutes.

Compared with the prior art, the present invention has the following beneficial effects in the ventilating and degassing and deslagging refining method in the 3104 aluminum alloy flat ingot casting furnace: 13 ventilating bricks for removing liquid aluminum gas are arranged at the bottom of the holding furnace of the present invention. After that, the hydrogen rises rapidly, passing through the argon gas with a purity of ≥99.99%, and its pressure is 0.2-0.6MPa. In addition to the exhaust purpose, the breathable bricks also have three functions: 1) a certain space is formed in the process of removing temperature and alloy stratification, and they also affect the movement of solid particles in the molten pool; Vigorously drives to metal surfaces. The molten pool movement created by the permeable brick reduces the molten metal surface temperature (745°C), which advantageously reduces the formation of residues, and at the same time obtains an aluminum alloy melt with low hydrogen and low solid particles; 3) Each furnace is seeded 45 minutes before casting Refined for 15 minutes, cast for production after standing for 30 minutes. In order to prevent the melt from absorbing hydrogen again, the degassing should be completed as close as possible to the casting time. The use of breathable technology reduces the labor intensity of employees. The original old-fashioned casting process uses small bottled gas, manual stirring and purging, which greatly increases the labor intensity of workers. During refining, workers work in front of the high-temperature furnace for a long time, which deteriorates the working environment of workers. After using furnace bottom refining, the entire refining process is completed independently by the PLC operating program, eliminating the above unfavorable factors. The use of ventilation technology shortens the refining time in the furnace and improves the degassing efficiency. The original old-fashioned box refiner needs to refine each furnace door for 15 minutes, and the three furnace doors need to be refined for 45 minutes. The long-term partial refining method causes secondary hydrogen absorption and burning loss of the melt. Improve the degassing quality, improve product quality and product yield. The method of distributing 13 breathable bricks at the bottom of the furnace can be beneficial to solve the problem that artificial blowing cannot fully achieve uniform gas distribution, and it is easy to leave dead corners in the furnace body. The degree of blowing refining is completely affected by human factors, and the blowing pressure is difficult to control The influence of unfavorable factors such as secondary impurity pollution is caused, and the degree of melt refining is greatly improved.

The advantages of the present invention are: 1. Improve the degassing efficiency, reduce the hydrogen content of the melt by 40%; 2, improve the refining effect in the furnace, reduce the slag content of the melt by 25%; body temperature of 745°C) and the ventilation pressure of each ventilation brick, the ventilation pressure of each ventilation brick is 3Pa. 4. Reasonably determine the ventilation sequence and time (15min/heat). 5. Improve the product quality of aluminum alloy flat ingots and reduce casting defects of flat ingots. 6. Reduce the labor intensity of workers and improve the work efficiency of workers. 7. The production cost of flat ingot is reduced, and the economic benefit is improved. The production cost of flat ingot is reduced by 30 yuan per ton. 8. The refining process is safer. 9. The refining time in the holding furnace is reduced by 30-50%, which increases productivity and reduces the flow rate of gas used. 10. The service life of the breathable brick is extended. The invention is applicable to the aluminum and aluminum alloy casting industry.

Description of drawings

The air-permeable degassing and slag removal refining method in the 3104 aluminum alloy flat ingot casting furnace of the present invention has the following drawings:

Figure 1 is a flow chart of the refining process in a 3104 aluminum alloy flat ingot casting furnace with ventilation and degassing and slag removal. Among them: 1. Argon gas storage tank; 2. Argon gas pipeline; 3. Chlorine gas storage tank; 4. Nitrogen gas pipeline; 5. Chlorine gas pipeline; 6. Gas mixing cabinet; 7. Gas flow control cabinet; 8. Tilting holding furnace; 9. Breathable brick; 10. Mixed gas pipeline; 11. Operation panel; 12. Nitrogen generator unit; 13. Manual control valve.

Detailed ways

In the following, the technical scheme of the method for refining the 3104 aluminum alloy flat ingot casting furnace with ventilation, degassing and deslagging will be further described in conjunction with the accompanying drawings and examples.

As shown in Fig. 1 , the ventilation and degassing and slag removal refining method in the 3104 aluminum alloy flat ingot casting furnace of the present invention comprises a tiltable holding furnace 8, 13 ventilation bricks 9 built on the furnace bottom refractory material structure, 13 ventilation pipelines 10 are arranged, and the described ventilation degassing and slag removal refining method is to introduce inert gas or inert mixed gas into the holding furnace 8 through the ventilation pipeline 10 arranged under the 13 ventilation bricks 9 at the bottom of the furnace, The inert gas absorbs the oxidized slag, harmful gas and other impurities in the molten aluminum, and then adheres to the surface of the bubbles, floats and rises to the surface of the molten aluminum to exhaust, and uses a slag scraper to remove the waste slag in the molten aluminum. The process conditions are: The ventilation rate of each ventilation brick is 3-45Nl/min, the ventilation pressure is 3Pa, and the refining time is 15-40 minutes.

The production air flow of each air-permeable brick is 20-45Nl/min.

The inert gas is argon; the inert mixed gas is an inert mixed gas of argon and chlorine or argon and nitrogen.

The purity of the passing nitrogen is ≥99.99%, its pressure is 0.2-0.6MPa, and the purity of argon is 99.996%.

Example 1.

The method for refining 3104 aluminum alloy flat ingot casting furnace by ventilation, degassing and slag removal comprises a tiltable holding furnace 8, 13 ventilation bricks built on the furnace bottom refractory material structure 9, and 13 ventilation pipes are arranged at the furnace bottom Road 10 constitutes, and the distribution of the 13 ventilation bricks at the bottom of the tilting holding furnace 8 is shown in Figure 1, which is divided into 3 rows and distributed in a staggered manner; the 13 ventilation pipes at the outlet of the gas flow control cabinet 7 have 10 ends Parts are respectively provided with manual regulating valves 13; the described refining method of ventilating degassing and slag removal is through the ventilating pipeline 10 provided under 13 ventilating bricks 9 at the bottom of the furnace, which is controlled by the SIEMENS PLC system through the gas flow control cabinet 7 to the holding furnace 8. Introduce argon gas for degassing. The argon gas absorbs the oxidized slag, harmful gas and other impurities in the molten aluminum, and then adheres to the surface of the bubbles, floats and rises to the surface of the molten aluminum to exhaust, and uses a slag scraper to remove the waste slag in the molten aluminum. The process conditions are: The ventilation rate of each ventilation brick is 3-45Nl/min, the ventilation pressure is 3Pa, and the refining time is 15-40 minutes.

The production air flow of each air-permeable brick is 20-45Nl/min.

The inert gas is argon; the inert mixed gas is an inert mixed gas of argon and chlorine or argon and nitrogen.

The purity of the passing nitrogen is ≥99.99%, its pressure is 0.2-0.6MPa, and the purity of argon is 99.996%.

use gas selection

Since the 3104 alloy is a high-magnesium alloy, the magnesium content reaches more than 1.2%, and magnesium reacts with nitrogen to form magnesium nitride. Therefore, nitrogen is used as a degassing carrier when producing 3104 series aluminum alloys, which can also achieve the purpose of furnace refining.

Gas flow calculation

The stirring flow rate of each breathable brick is 3-90Nl/min. A 50-ton tiltable holding furnace 8 is installed in the casting workshop, and 13 breathable bricks 9 are installed on the furnace bottom refractory structure, so the total flow rate is 39-1170Nl/min. . Porous permeable bricks require very little pressure. In order to achieve the operating flow rate, the pressure of permeable bricks with a length of 2.5cm is required to be 0.1kg/m ² .

Gas flow distribution

There are 13 air-permeable bricks 9 under the holding furnace, and the flow of each brick can be selected to open or terminate work by a manual regulating valve 13. Under normal circumstances, 13 air-permeable bricks work at the same time, and the refining coverage reaches more than 90%, which can eliminate refining dead angles and achieve the goal of complete refining.

gas flow control

There are five sets of refining process schemes for the breathable bricks in this workshop, as follows:

The first process plan: the flow rate is 3Nl/min, which is mainly used for purging the air-permeable bricks when the furnace is empty.

The second process plan: the flow rate is 6Nl/min, which is applied to the purging of the ventilation bricks in the furnace during the production interval.

The third process plan: the flow rate is 30Nl/min, which is applied to the refining of 30 tons of charge.

The fourth process plan: the flow rate is 45Nl/min. It is applied to the refining when 50 tons of molten metal is fully loaded.

The degassing time required for a holding furnace refining depends on many factors, but generally speaking, if a furnace wants to achieve a hydrogen content in the range of 0.12-0.15cc H ₂ /100gm Al, the refining time can be fully achieved within 15-40 minutes The effect of exhaust slag reduction. The production capacity of each furnace of 3104 series is about 36 tons, and the refining time is set at 15-30 minutes to fully achieve the refining effect. At the same time, the goal of energy saving can be achieved.

Each furnace is refined for 15 minutes 45 minutes before casting, and cast for production after standing for 30 minutes. In order to prevent the melt from absorbing hydrogen again, the degassing should be completed as close as possible to the time of casting.

The refining situation of the applicant in the 8 furnaces of the 10# holding furnace in the trial production of the 3104 aluminum alloy casting production line:

1. Gas preparation: 99.99% nitrogen, 99.996% high-purity argon.

2. The total gas pressure is 0.7MPa. The pressure of the breathable brick is 3Pa.

3. The material in the furnace is 3104 series alloy with a total tonnage of 36 tons.

4. Implement technical parameters

5. The refining time is from 9:02 to 9:17, which takes 15 minutes.

6. Check the refining effect: 1250Kg of slag is removed after refining, and the amount of slag removed is 25% higher than that of the aluminum ingot furnace for remelting without refining process. The measured hydrogen content is 0.21mL/100gAl, which is 40% lower than that of the aluminum ingot furnace for remelting without refining process. The ventilation technology in the furnace was tested in the second electrolysis plant. The refining time of each charge was reduced by 30 minutes, the number of refining times was reduced by 3 times on average, the alloy burning loss was reduced by 3% on average, and the production cost was reduced by 30 yuan per ton. The product quality is stable, the finished product rate is increased by 33%, and the labor intensity of workers is reduced.

Claims (4)

1, ventilative degasification deslagging refining method in a kind of 3104 aluminium alloy flat bloom foundry furnaces, but comprise kettle furnace (8), 13 gas permeable bricks (9) of on the bottom refractory structure, building by laying bricks or stones, at furnace bottom 13 vent lines (10) being set constitutes, it is characterized in that: described ventilative degasification deslagging refining method is to feed inert gas or inert mixed gas by the vent line (10) that 13 gas permeable bricks of furnace bottom (9) below is provided with in holding furnace (8), oxide slag inclusion in the rare gas element Al adsorption liquid, adhering to bubble surface behind obnoxious flavour and other impurity swims with bubble and rises to the exhaust of aluminium liquid surface and with forklift for slag the waste residue in the aluminium liquid is clawed, its processing condition are: the Air permenbility of described each gas permeable brick is 3-45Nl/min, ventilative pressure is 3Pa, and refining time is 15-40 minutes.

2, ventilative degasification deslagging refining method in the 3104 aluminium alloy flat bloom foundry furnaces according to claim 1 is characterized in that: described 13 gas permeable bricks (9) are that 3 rows are interspersed at furnace bottom, and the production Air permenbility of each gas permeable brick is 20-45Nl/min.

3, ventilative degasification deslagging refining method in the 3104 aluminium alloy flat bloom foundry furnaces according to claim 1, it is characterized in that: described rare gas element is an argon gas; Described inert mixed gas is argon gas and chlorine or argon gas and nitrogen blended inert mixed gas.

4, according to ventilative degasification deslagging refining method in claim 1 or the 3 described 3104 aluminium alloy flat bloom foundry furnaces, it is characterized in that: the described nitrogen gas purity that passes through is 〉=99.99%, and its pressure is 0.2-0.6MPa, and purity of argon is 99.996%.

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