In theory, after refining in the furnace, online degassing system and slag removal, the purity of the aluminum alloy melt should reach a high level. But the actual results are often not ideal. One of the important reasons is secondary pollution in molten aluminum as it passes through a launder or a casting plate. At this time, the aluminum melt is in the “unprotected” state. The absorbed gas and the generated non-metallic inclusions are more likely to flow into the casting rod, forming secondary pollution. The longer the flow cell, the greater the probability and degree of secondary pollution.
Method for Controlling Purity of Aluminum Melt
In response to the above problems, three measures can be taken when uses online designing system the purification system:
- Shorten the length of the flow cell. From the casting water outlet into the crystallizer, the length of the flume shall not exceed 2m. When dealing with the drop of the flow cell, the method of overlapping of two flow slots replaces the method of excessive inclination. In order to ensure the maximum liquid level and prevent the aluminum melt from tumbling and slagging.
- Integrated design of filtration and online degassing system, save the transfer process, and shorten the length of the launder as much as possible.
- The filter plate of the secondary filtration is directly laid on the crystallizer. So that the molten aluminum directly enters the casting after being filtered, which can reduce the incidence of secondary pollution. In addition, when refining in the furnace, the amount of refining agent is sufficient, and ensure the refining time. Strictly implement the baking system of the casting system. These measures will have a positive impact on purity control.
In order to make aluminum rods with higher purity, we need to pay attention to several points:
- When the alloy grade is changed, drain the aluminum liquid in the purification device and clean it up.
- The runner die must be thoroughly baked.
- Covering agent is used to prevent inhalation during melting in the furnace.
- The flow through is made of light-weight refractory insulation material with good air permeability, which is conducive to thorough drying and prevents air inhalation.
- Blow out the surface scum before installing the ceramic foam filter.
- The environmental factors are an important reason for the purity of the melt. Melt purification is not a problem that can be solved only by advanced equipment. It needs comprehensive consideration from production management, equipment maintenance, process specifications and other aspects.