Aluminum (Al) is a light metal whose compounds are widely distributed in nature. The resource of aluminum in the earth's crust is about 40 to 50 billion tons, ranking third only after oxygen and silicon. It is the first major category of metals in the metal category. Aluminum has special chemical and physical properties, not only light weight and strong texture, but also good ductility, electrical conductivity, thermal conductivity, heat resistance, and nuclear radiation resistance. It is an important basic raw material for the development of the national economy.