Liquid aluminum degassing equipment
Liquid aluminum degassing equipment is a crucial equipment in the smelting process of aluminum and aluminum alloys. It is mainly used to remove hydrogen, inclusions, and other harmful gases in molten aluminum to improve the density and mechanical properties of castings or rolled products. The following is a comprehensive analysis of liquid aluminum degassing equipment:
The necessity of liquid aluminum degassing
1. Hydrogen hazards
Liquid aluminum absorbs hydrogen (mainly from water vapor decomposition) during the smelting process. When solidified, hydrogen precipitates to form pores, resulting in loose materials and reduced strength.
2. Inclusions
Inclusions such as oxides (such as Al?O?) and flux residues will reduce the ductility and fatigue life of the material.
3. Process requirements
High-end aluminum materials (such as aerospace and automotive parts) have strict standards for hydrogen content (usually <0.1ml/100g Al).
Types and principles of aluminum liquid degassing equipment
Principle: The inert gas (Ar, N?) is dispersed into tiny bubbles through a high-speed rotating rotor, and the bubbles are used to absorb hydrogen and inclusions and float to the liquid surface.
Structure:
Rotor: Graphite or ceramic material, high temperature and corrosion resistant.
Gas injection system: Control gas flow and pressure.
Lifting mechanism: Adjust the rotor immersion depth.
Advantages: High efficiency, strong applicability, widely used in large and medium-sized furnaces.
Disadvantages: The rotor is easy to wear and needs to be replaced regularly.
2. Gas Injection System
Principle: Inert gas is sprayed to the bottom of the aluminum liquid through a porous spray gun to form a bubble flow to absorb impurities.
Applicable scenarios: small furnaces or continuous casting production lines.
Advantages: Simple structure and low cost.
Disadvantages: Uneven gas distribution and degassing efficiency is lower than that of the rotary type.
Principle: Reduce the surface pressure of aluminum liquid in a vacuum environment to force hydrogen to escape.
Application: Deep degassing of high-end aluminum materials (such as aviation aluminum plates and electronic aluminum foils).
Advantages: Thorough degassing (hydrogen content can be reduced to below 0.05ml/100g).
Disadvantages: Complex equipment, high investment, suitable for small batch production.
4. Combined degassing technology
For example: rotary degassing + flux purification, or vacuum degassing + gas injection, can further improve the purification effect.
Key parameters and selection of equipment
1. Core parameters
Processing capacity: Select the equipment model according to the furnace capacity (such as 1-50 tons/hour).
Rotor speed: Usually 300-600 RPM, the higher the speed, the finer the bubbles.
Gas flow rate: Ar/N? flow rate is generally 5-20 L/min·ton, and excessive flow should be avoided to cause aluminum liquid oxidation.
Temperature control: The temperature of aluminum liquid is recommended to be controlled at 720-750℃ (to avoid overheating and oxidation).
2. Selection recommendations
Small and medium-sized foundries: rotary degasser (cost-effective).
Continuous casting line: a combined system of injection + filtration.
High-purity aluminum production: vacuum degassing equipment.
领英推荐
Operation process and precautions
1. Standard operation steps
Preheating equipment → immerse the rotor to 1/3 of the depth of aluminum liquid → start rotation and pass inert gas → process for 10-20 minutes → detect hydrogen content.
2. Precautions
The purity of inert gas must be ≥99.99% to prevent the introduction of moisture or oxygen.
Clean the slag on the surface of the rotor regularly to avoid clogging the pores.
Control the flux coverage on the surface of the aluminum liquid to reduce oxidation.
Detection and effect evaluation
1. Hydrogen content detection method
Decompression solidification method: measure the density change after sampling and solidification.
Telegas method: calculate the hydrogen content by hydrogen partial pressure (high accuracy, suitable for laboratories).
Online hydrogen analyzer: real-time monitoring of melt hydrogen content.
2. Inclusion detection
PoDFA (Porous Filtration Analysis): Analyze the composition of the filter residue after filtering the aluminum liquid.
LiMCA: Use conductivity changes to detect inclusion concentration online.
Technology Frontiers and Development Trends
1. Intelligent Control
Integrated sensors and AI algorithms to adjust the speed and gas flow in real-time to optimize energy consumption and degassing efficiency.
2. Environmental protection and energy saving
Develop low gas consumption technologies (such as microbubble generators) and renewable rotor materials.
3. Composite purification technology
Combine new methods such as electromagnetic purification and ultrasonic degassing to improve purification effects.
Common faults and maintenance
Fault phenomenon: Decreased degassing efficiency
Possible cause: Rotor wear/blockage
Solution: Replace the rotor or clean the air holes
Fault phenomenon: Unstable gas flow
Possible cause: Gas leakage or pressure-reducing valve failure
Solution: Check pipeline tightness and replace pressure pressure-reducing valve
Fault phenomenon: Severe oxidation of aluminum liquid
Possible cause: Insufficient flux coverage or impure gas
Solution: Add flux and test gas purity
Main equipment suppliers:
Economic and cost analysis
Equipment investment: The rotary degasser is about 100,000-500,000 yuan, and the vacuum equipment is more than 1 million yuan.
Operation cost: Inert gas consumption accounts for 60%-70% of the total cost, and an energy-saving design can reduce energy consumption by 30%.
Summary
The selection of aluminum liquid degassing equipment needs to comprehensively consider production scale, material requirements, and budget. As the aluminum industry develops towards high precision and lightweight, efficient and intelligent degassing technology will become the mainstream. During operation, process parameters must be strictly controlled, equipment must be maintained regularly, and detection methods must be combined to ensure that the quality of aluminum liquid meets standards.