Domestic aluminum melt purification materials and equipment technology trends

On June 11, 2020, the "Fifteenth China International Aluminum Processing Summit" hosted by SMM was held in Yantai, Shandong. At the meeting, Xiong Xuejun, general manager of Henan Ivans Metallurgical Materials Co., Ltd., shared the current domestic advanced aluminum alloy melt purification process, introduced the technical trend of aluminum alloy melt purification materials and equipment, and pointed out the existing process applications and equipment Insufficient, the main way and development direction of aluminum alloy melt to improve the purification effect are analyzed. He said that efforts should be made to realize the localization and penetration rate of melt purification materials and equipment, so as to improve the overall level of my country's aluminum alloy industry.
The gas hydrogen content and solid inclusions in the aluminum alloy melt are the main factors affecting the quality of aluminum alloy products.
The presence of inclusions and gaseous hydrogen destroys the continuity of the metal. Due to the different elastic modulus and expansion coefficient between the inclusions and the metal matrix, the sharp corners of the inclusions are prone to stress concentration and become the source of fracture in the material. And corrosion sources, it is easy to produce various defects during the processing and deformation of aluminum alloy materials.
In order to improve the processing performance and market competitiveness of the finished product, in addition to the purification of the aluminum melt and the purification of the static process, the purification casting system outside the furnace is more important.
 
Development trend of wrought aluminum alloy application
After the reform and opening up, China's aluminum industry has entered a stage of rapid development, and aluminum alloy materials are more widely used, such as: civil profiles, industrial profiles, food packaging, aerospace aluminum alloy materials, etc.
 
Classification and control of hydrogen and inclusion purity of aluminum alloy final products
1. Divide according to user requirements and measured data using online hydrogen and slag measurement methods:
For products such as first-class purity ultra-thin aluminum foil and can material, the hydrogen content is determined to be no more than 0.10ml/100gAl, and the slag content is determined to be no more than 2K/kg;
For important use products such as aerospace, high-speed rail, double zero foil, can cover material, CTP board, automobile board, rail transportation and other important products with secondary purity, the hydrogen content is determined to be not more than 0.12ml/100gAl, and the slag content is determined to be not more than 2 -5K/kg;
For ordinary aluminum alloy products such as curtain wall decorative panels with grade 3 purity (except for special requirements), the hydrogen content is determined to be no more than 0.2ml/100gAl, and the slag content is determined to be no more than 5-80K/kg.
 
2. Production control of the purity of aluminum alloy melt
First-grade purity products: can add first-grade waste and use master alloy or aluminum-type additives---gas refining (Ar2 gas or mixed gas) for remelting flux protection and alloying protection---configuration of rotating degassing/vacuum degassing Gas---use foam ceramic filter + tube type;
Secondary purity products: secondary waste materials and metal additives can be added---gas refining (N2 gas) for flux protection and alloying protection---equipped with rotating degassing/vacuum degassing---using two-stage ceramic foam Filter sheet/foam ceramic filter sheet + tubular or deep bed for filtration;
Three-level purity products: third-level waste, aluminum shavings and metal additives can be added ---gas refining (N2 gas) for flux protection ---using foam ceramic filters.
 
Technical changes to improve the quality of melt purification materials and equipment
The method of improving the quality of deformed aluminum alloy-furnace refining, online degassing, filtering and diversion protection of non-wettable materials.
1. Replace the chlorine in the furnace and online refining.
2. Smokeless refining, zero emission of fluoride, and fully meet the emission standards established by environmentally harmful air pollution.
3. A small amount can control the burning loss caused by the compound reaction.
4. Effectively remove alkali metals (Na, Ca, Li) and non-metallic inclusions, with a removal rate of 40%-70%。