Continuous casting and rolling has the advantages of short process, energy saving, low production cost, etc., and has been accepted and applied by more and more countries. The electrolyzed aluminum liquid undergoes a high-throughput continuous casting machine and hot three continuous rolling to directly form a slab of 2 mm to 8 mm, in which the flow of aluminum melt can be as high as 50 t/h. The casting tip and nozzle serves as the “throat component” of the high-throughput continuous casting and rolling mill as the aluminum melt, and its role is very important. Once problems such as clogging of the casting nozzle occur, the machine can only be shut down for replacement, resulting in production interruption, waste of manpower and material resources, and reduced production efficiency.
With the development and progress of science and technology, remarkable progress has been made in the treatment of aluminum melt. In the production process, a series of purification and filtration treatments are carried out on the electrolytic aluminum liquid to remove the inclusions in the electrolytic aluminum liquid, and a cleaner aluminum liquid can be obtained. To a certain extent, to ensure that the melt passes smoothly through the casting tip and nozzle, but the castertip is still blocked. It is the main problem faced in the production process of aluminum alloy.
Alkali metal elements such as Li and Na have strong activity and are easy to oxidize. The presence of trace alkali metals can accelerate the oxidation of molten aluminum, which is very harmful in aluminum casting and requires strict control. The alkali metal generated in the side reaction of alumina electrolysis, in the very long time refining agent and chlorine refining process, the chloride or fluoride formed by the reaction has a low melting point and exists in the form of eutectic salt and is soluble in aluminum In the liquid, a large amount of precipitation occurs on the surface of the casting nozzle due to the temperature drop. Among the dross, the highest content of Li accumulates on the surface of the nozzle very seriously. Its chloride melting point is 613°C, and its liquid density is 1. 5 g/cm3. The presence of other elements such as F, Cl, Na, K, and Ca indicates that there are fluoride salts added in the electrolytic cell and chlorides generated during the refining process to accumulate on the surface of the nozzle. The existence of a large number of Al2O3 particles may be caused by the long-term contact reaction between the aluminum melt and the refractory base material of the nozzle at high temperatures.