Electrolytic aluminum liquid pretreatment process includes aluminum alloy melting, temperature control, melt purification, and grain refinement.
Electrolytic Aluminum Liquid Pretreatment Process
Aluminum Alloy Melting
Ingredients and composition control in the production, 20%-30% of solid cold materials (including aluminum ingots for remelting or primary scrap and master alloys of this alloy) are generally added for batching. First, aluminum ingots for remelting or primary alloy of this alloy are added. The waste material is added to the intermediate alloy, and finally the electrolytic aluminum liquid is injected. The high-temperature heat of the electrolytic aluminum liquid is used to quickly melt the solid materials added to the furnace and reduce the temperature of the electrolytic aluminum liquid, and at the same time increase the nucleation rate of the molten metal.
Melting temperature: the normal smelting temperature is controlled at 740-780℃, refining temperature: the degassing and slagging are controlled at 740-760℃.
Converter temperature: The molten aluminum temperature in the smelting furnace is kept within the range of 740-760℃ before the converter can be started.
Casting temperature: usually controlled in the range of 690-740℃.
The temperature of the electrolytic aluminum solution is as high as 950℃, and it contains metal impurities such as silicon, iron, sodium, calcium, phosphorus, boron, titanium, vanadium, zinc, and non-metallic inclusions such as aluminum oxide, aluminum fluoride, carbon, aluminum carbide, and aluminum nitride. The gas content is high, and the hydrogen content can reach 0.6ml (100gAl)-1.29ml/(100gAl) when the temperature of the electrolytic aluminum liquid in the ladle is 760℃-840℃. The presence of gas in the melt and various metallic and non-metallic inclusions can cause structural defects in the ingot, which in turn affects the structural properties of the processed products. Therefore, the aluminum alloy must be melted when producing aluminum alloy slab ingots with electrolytic aluminum liquid ingredients. The body adopts a more stringent purification process to ensure the purity of the aluminum melt. In production, through six times of molten aluminum purification, slagging and degassing, to ensure the effect of melt purification.
The imported aluminum-titanium-boron wire is added online outside the furnace to refine the product particles, and the adding position of the refiner is located in the launder between the outlet of the stationary furnace and the metal inlet of the rotating degassing device. Here the melt temperature is higher, the refiner is easy to fully dissolve, and is fully stirred in the degassing box, so that the heterogeneous crystal nuclei are more evenly distributed in the entire melt, and the refinement effect is good.