The purification technology of aluminum alloy smelting furnace can be divided into adsorption purification treatment technology and non-adsorption purification treatment technology according to the purification mechanism.
The adsorption method mainly relies on the refining agent to produce the adsorption and oxidation inclusions, and at the same time removes the oxidation inclusions and the hydrogen attached to the surface to achieve the purpose of purifying the liquid aluminum.
The non-adsorption method relies on other physical and chemical effects to achieve the goal of purification of liquid aluminum. The refining action of the adsorption method only occurs at the adsorption interface, and the non-adsorption method acts on all of the liquid aluminum at the same time. Adsorption purification treatment technology mainly includes inert gas purge, active gas purge, mixed gas purge, chlorine salt (hexachloroethane) purification, non-toxic refining agent purification, refining flow, etc.
In adsorption purification treatment technology, the refining of chlorine gas is used and aluminum trichloride is formed with liquid aluminum, and hydrogen chloride is generated by hydrogen gas, which has effects physical and chemical purification, and the refining effect is obvious.
It causes serious damage to the environment and to equipment, and chlorine is the main culprit in destroying the ozone layer in the atmosphere.
Later, it was replaced by nitrogen refining, and even high purity nitrogen refining was used, which not only increased the cost, but also had a poor refining effect.
Although people have realized the seriousness of the problem and are striving to improve the process, many years of efforts are still unsatisfactory. Non-toxic and non-polluting refining processes (such as refining with inert gases such as nitrogen and argon) often cannot achieve so seriously The refining effect can be achieved by processing of chlorine refining contaminated by the environment.
In recent years, mixed gas refining is widely used in foreign countries, that is, adding a small amount of active gas in high purity nitrogen or argon, while enhancing the melting of the aluminum alloy to remove the hydrogen, it is advantageous to remove the inclusions inside the molten aluminum alloy and The surface of the molten aluminum alloy causes dry slag, which can achieve good refining effect, and can artificially control the amount of mixed chlorine gas, which has little impact on the environment.
In the adsorption-free purification processing technology, the rare earth hydrogen storage method (hydrogen chemical attachment method) uses the special electronic structure and physical and chemical properties of the rare earth element.
And the formation of high melting point compound dispersion particles, the absorption of a large amount of hydrogen in the molten aluminum alloy in solid form, is playing an increasingly important role in the purification of the molten aluminum alloy.
At the same time, rare earth elements have also been widely used in metamorphic processing. Therefore, the rare earth solid-hydrogen chemical purification technology of aluminum alloy melt has become a development direction of new aluminum alloy melt refiner.
