Purpose and methods of aluminum liquid refining

Purpose of aluminum liquid refining:

Aluminum liquid often contains impurities such as hydrogen and aluminum oxide. These impurities will affect the physical and mechanical properties of aluminum products, causing problems such as pores, shrinkage cavities, inclusions, etc. in the use of aluminum products, seriously affecting their quality and durability.

To remove gases, non-metallic compounds, and other harmful elements in aluminum liquid to make aluminum liquid purer. Through refining (filtration and degassing), impurities such as hydrogen and oxide inclusions in aluminum liquid can be removed, the generation of pinholes can be reduced, and the performance of aluminum alloy materials can be improved.

Common impurities in aluminum liquid and their effects:

Common impurities in aluminum liquid include hydrogen and aluminum oxide. The presence of hydrogen will cause pores in aluminum products, affecting their sealing and appearance; aluminum oxide will cause the formation of inclusions, reducing the strength and corrosion resistance of aluminum products.

Methods of aluminum liquid purification:

Common aluminum liquid purification methods include electrolytic purification, filter filtration, solvent (refining flux) purification,

and gas purification. Electrolytic purification removes impurities through the electrolytic process; filter filtration uses physical barriers to remove inclusions (ceramic foam filter);

solvent purification uses solvents to adsorb oxides; gas purification forms bubbles to remove impurities by introducing gases such as chlorine or nitrogen.

Purification effect and application:

Through effective purification treatment, the impurity content in the aluminum liquid can be significantly reduced, and the density and uniformity of aluminum alloy castings can be improved, thereby improving their physical and mechanical properties. This is particularly important in fields with high material requirements such as cables, aerospace, and automobile manufacturing.

Specifically, inert gases (such as nitrogen) are used to blow off impurities during the refining process to form fine bubbles, and inclusions float to the surface with the bubbles and are removed. In addition, flux is used to cover the aluminum liquid during the refining process to prevent oxidation and air inhalation, thereby ensuring the quality of the aluminum liquid. This purification method generally uses an aluminum degassing unit to degas the aluminum liquid using a rotary spray method.

The main methods of aluminum liquid purification include:

1 Cooling degassing method: Remove the gas in the aluminum liquid by lowering the temperature, usually combined with stirring, the effect is better.

2 Stirring and standing degassing and slag removal method: Remove gas and impurities by stirring the aluminum liquid and standing for some time. Stirring can accelerate the floating of gas and impurities.

3 Solidification-remelting purification method: Remove impurities through the process of solidification and remelting. Impurities will float up and be removed during the remelting process.

4 Solvent purification method: Use solvent (aluminum refining flux) to form fine droplets, adsorb and dissolve oxides in aluminum liquid, and form slag removal.

5 Gas purification method: Use inert gas (such as nitrogen or argon) or mixed gas to purge aluminum liquid to remove gas and non-metallic inclusions.

6 Flux jet refining method: Refine aluminum liquid by spraying flux, and the flux adsorbs and dissolves oxides to form slag removal.

7 Ceramic foam filter method: Use alumina ceramic foam filter to filter and remove impurities. Ceramic filter plates can filter and adsorb impurities in aluminum liquid.

8 Glass cloth filtration method: Use glass cloth to filter and remove impurities in aluminum liquid, suitable for small batch production.

9 Adsorption method: Including inert gas purging, active gas purging, mixed gas purging, chloride salt purification, non-toxic refining agent purification, etc., purifying aluminum liquid by adsorbing oxidized inclusions and hydrogen attached to the surface.

10 Non-adsorption method: Including vacuum purification treatment, ultrasonic purification treatment, electromagnetic purification treatment, pressure crystallization method, rare earth element solid hydrogen method, etc., remove impurities in aluminum liquid through physical and chemical effects.