The essence of Molten Aluminum Refining Agent is to use the difference of wettability between inclusions and melts when liquid flux is used to purify melt, so that inclusions move spontaneously from melt to flux. At the same time, gas diffusion and dissolution adsorption are used to remove impurities and remove hydrogen. According to the purification mechanism, purification flux can be divided into refining agent, covering agent, slag cleaning agent, and wall cleaning agent.
Molten Aluminum Refining Agent
The traditional molten aluminum refining agent is based on the bubble floating. When it enters the aluminum melt, it decomposes or reacts with the aluminum melt to generate gas, such as HCI. The hydrogen atom in the melt diffuses into these bubbles and is taken away. At the same time, the bubble catches the inclusion scum in the process of floating, so as to play the role of purification.
At present, three in one refining fluxes and powder spraying fluxes are widely used in the market, and their main components are CCl4, NaCl, KC, NaF, and CaF2. In addition, the non-toxic fluxes with chlorine and NaNO3 + C as the main body and chlorine salts and chlorides which can generate active gases are refining agents. In addition to these impurities, the refining flux has a better purification effect on the basis of rare earth.
The density of covering agent is smaller than that of aluminum melt. Covering on the melt surface, it can isolate the contact between aluminum melt and air, and produce a series of physical and chemical reactions with aluminum melt, so as to prevent aluminum melt from gettering, remove hydrogen and impurities, and improve the cleanliness of the melt.
Generally speaking, slag remover has spreading and separating properties. Its function is to improve the surface tension between aluminum melt and slag, and promote the separation of aluminum and slag layer. When it melts into aluminum melt, dissolved and adsorbed inclusions float up to the surface of aluminum solution and form dry slag, so as to achieve the purpose of impurity removal.
The wall cleaning agent is generally composed of exothermic substances. Its main function is to reduce the formation of oxide residue on furnace wall or crucible wall, and prevent the mixture of flux and slag from sticking or agglomerating on the wall or bottom of the molten furnace.