In addition to the ratio of electrolytic aluminum liquid and solid material that will affect the internal quality of the cast-rolled plate, aluminum melt refining fluxes are the key. In addition to the chemical composition, the inherent quality of cast-rolled aluminum plates is mainly affected by grain size, gas, and slag inclusion.
Before the furnace is poured, the aluminum melt refining fluxes are sprayed and refined. The refining time is 20 min-25min, the amount of refining agent is 3 kg/t, and it is left standing for 20 min after refining. The aluminum melt refining makes the gas and slag in the molten aluminum have sufficient time to float from the lower part of the molten pool to the surface of the molten aluminum, and then remove the slag. In the powder spraying refining process, the refining agent should be sprayed evenly into the aluminum liquid and the purity of nitrogen should be ensured. The nitrogen purity can be controlled at 99.9995% or more.
An online processing system is adopted between the holding furnace and the front box. The online processing system includes degassing system and filtering system.
The online degassing system uses a graphite rotor in the degassing box to re-refine the molten aluminum in the degassing box and carry out the slag and gas.
The plate filtering unit is used to filter and purify the molten aluminum, matching with the ceramic foam filter. It can filter the inclusions and tiny particles in the molten aluminum. Especially suit for the casting high purity aluminum and high precision aluminum alloy. It has the advantages of thermal resistance, anti-oxidation, corrosion resistance, warming up quickly, long lifetime, and acid resistance.
After passing through the online processing system, the hydrogen content in the molten aluminum can be controlled at 0. Within 12 mL/(100 gAl), the slag content above 5 μm can filter out more than 90%, and effectively control the grain size of the cast-rolled sheet, which provides good internal quality for the production of PS plate base, double zero foil, and other cast-rolled coils.