Four methods of preparing alumina

1. Preparation of high purity alumina by carbonization method

Using carbon dioxide and sodium aluminate as raw materials, pseudo-boehmite is obtained by precipitation, which is calcined at high temperature to obtain alumina. A large amount of washing is used to remove impurities such as sodium, iron and silicon in the product. The carbonization method has been widely studied due to its advantages such as low raw material cost, simple operation, and easy control of key points. But it is only suitable for large-scale production, the variety is relatively single, the purity is low, and the crystal phase is unstable.

2. Preparation of high purity alumina by double aluminum method

Using aluminum sulfate and sodium aluminate as raw materials, pseudo-boehmite is obtained by precipitation, which is calcined at high temperature to obtain alumina. The double aluminum method has relatively low cost, flexible production scale and diverse varieties. However, the purity of the product is not high, the stability of the product is poor, and the by-products need to be processed.

3. Preparation of high-purity alumina by hydration of metal aluminum

Using high-purity aluminum foil as raw material, it reacts in water (adding catalyst) to produce high-purity gibbsite, which is calcined at high temperature to obtain high-purity alumina. The process product has high purity and diverse varieties. However, the price is higher and the flexibility of production scale is poor.

4. Preparation of high purity alumina by alkoxide hydrolysis

Using high-purity aluminum foil and alcohol (isopropanol used by Sumitomo and Yangzhou Zhongtianli in Japan, n-butanol used by Sasol in Germany) as raw materials, aluminum isopropoxide is obtained by reaction, and pseudo-boehmite is obtained after hydrolysis (this reaction process The alcohol can be recycled, and the current recovery rate of Yangzhou Zhongtianli is 80%-90%). After high-temperature calcination, high-purity alumina is obtained. The process product has high purity, diverse varieties, near zero discharge of three wastes, high environmental friendliness, suitable for large-scale production, and flexible production scale. But the production cost is relatively high.