The School of Materials Science and Engineering of Shanghai Jiaotong University has the first set of ultra-high purity aluminium purification process and equipment with full independent intellectual property rights in China, and has produced 5N5 and 6N ultra-high purity aluminium ingots for the first time in China. This has provided a solid foundation for the mass production of "5N high-purity alumina" raw materials. High-purity alumina with purity exceeding 5N (alumina content >99.999%), prepared by hydrolysis of high-purity aluminium, is mainly used in sapphire crystals, lithium battery separator materials, high-end fluorescent powder, catalysts, semiconductor ceramics, etc. 5N high-purity alumina is the main raw material for the production of sapphire single chips for LED backing, and 90% of LED enterprises worldwide use sapphire as backing material. With the continuous development of the LED industry and the popularity of smart terminals, the demand for sapphire continues to expand.