By adopting molten metal melt purification methods, equipment, and management measures, the quality of casting and rolling melts can be further improved. Molten Metal Purification can be realized through the following ways and methods.
Molten Metal Purification Methods
Melt transfer mode: Improve the melt transfer mode from melting furnace to static furnace, and replace the drop mode with slope form, so as to avoid the increase of oxidation and the aggravation of air suction caused by the drop. At the same time, cancel the siphon box mouth to avoid large areas of melt exposed to the air at the siphon box, and increase the oxidation suction.
Static furnace refining: by improving the refining tube or controlling the flow and pressure of degassing medium, avoid the influence of excessive bubble on degassing effect. For the production of high-quality aluminum foil, the following methods are recommended to replace the current single inert gas refining to improve the purification effect of melt.
a. Gas flux mixed refining: a small amount of flux powder is blown in to form a liquid salt film on the surface of the bubble. The oxide film on the surface of the bubble is broken, adsorbed and dissolved. The hydrogen in the melt is diffused into the bubble and the degassing effect is improved.
b. CCl4: CCl4 reacts with aluminum to produce AlCl3, HCl, Cl2 and other active gases. Hydrogen in the melt is removed by physical and chemical actions, which improves the refining effect.
c. Refining with mixed gas of fluorine refrigerant and argon: chlorine and fluorine generated by decomposition of Freon (CCL2F2) can react with aluminum alloy elements to form molten salts such as HCl, AlCl3 and AlF3, which play the role of bubble flux mixed refining.
a. At the same time, a protective gas is introduced into the chamber to reduce hydrogen absorption and oxidation.
b. By optimizing the rotating speed and improving the air outlet of the rotor, the bubbles are finer and the degassing effect is improved.
c. For the production of high-quality aluminum foil wool, a coarse filter (such as 10-20ppig filter) is added before degassing to improve the purity of melt, increase the diffusion rate of hydrogen in melt and improve the on-line degassing effect.
d. For the production of high-quality aluminum foil stock, the degassing medium was improved, and the mixture of fluorine refrigerant and argon gas was used instead of single inert gas refining. A small amount of fluorine refrigerant had no impact on the environment, but the degassing effect was remarkable.
Flow supply system: improve the thermal insulation of the chute, adopt new materials, increase the thickness of the chute or cover the chute.
Temperature control: find out a reasonable melting temperature to avoid burning in the chute due to too low melt temperature, so as to increase the oxidation and gas absorption of the melt.
Filtering effect: Strengthen the cleaning and replacement of the CFF filter box to ensure the shape and size of the inner chamber of the box and ensure the filtering effect.