Electrolytic Aluminum Liquid Characteristics, Aluminum Purification

In the entire production process of using electrolytic raw aluminum liquid as a raw material to produce round aluminum rods, the purification of aluminum melt has become a key factor in the production process, which is determined by the characteristics of electrolytic raw aluminum liquid and the requirements of round aluminum rods. It is decided that the quality of the purification process will directly affect the production process of round aluminum rods, and will have a serious impact on the quality of subsequent products. Therefore, a suitable purification process must be adopted according to the characteristics of the original aluminum liquid and the requirements of the round aluminum rod.

Electrolytic Aluminum Liquid

The aluminum liquid in the electrolytic cell has the following characteristics:

(1) The temperature is high. The electrolysis process is usually carried out at a temperature of 950 ℃ ~ 970 ℃, which is determined by the properties of cryolite-alumina composed of electrolyte and alumina, so the temperature of the molten aluminum in the electrolytic cell is at least 940 ℃.

(2) There are many oxidation inclusions. Although there is a certain density difference between the molten salt electrolyte composed of cryolite-alumina and the molten aluminum at the same temperature, it is sufficient to ensure that the molten aluminum and the electrolyte are stratified. But because the difference is very small, it is inevitable that a small amount of electrolyte will be inhaled when processing with a vacuum bag. The stirring and circulation of the electrolysis process and the rapid movement of the molten aluminum cause the aluminum to be oxidized again in the anode space, resulting in an increase in oxidation and inclusions in the aluminum melt.

(3) Fe and si content are high. In the electrolysis process, the reduced impurity elements such as Fe and si directly enter the aluminum liquid, which reduces the aluminum grade. They mainly come from raw material alumina, carbon anodes and iron tools.

(4) High hydrogen content. Due to the particularity of the aluminum electrolysis process, it is inevitable that the aluminum liquid contains gas, and the main component of the gas is hydrogen. Hydrogen generated by the thermal decomposition of the anode hydrocarbons is electrochemically dissolved on the anode, and the generated H migrates to the cathode and discharges on the anode to generate hydrogen. In addition, the hydrogen reduced from the water vapor in the surrounding environment is dissolved in the aluminum liquid together, and the saturation content of hydrogen in the liquid aluminum will increase with the increase of temperature.

According to the characteristics of the electrolytic aluminum liquid, it is necessary to strictly purify the aluminum liquid from each process.

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