Abstract:
Gel-derived crystalline alumina containing at least 40 percent pseudoboehmite and having low cationic and anionic impurity levels is partially dehyrated to an LOI of 22-34 percent, ground to at least 85 percent minus 325 mesh, shaped into spheres by conventional agglomerating devices while adding sufficient water to rise the total water content to 52-65 percent. These shaped spheres, without any ageing treatment, are then heated to a temperature in the range of 350*-650*C for a time necessary to produce the desired strength. The resultant spheres are strong and have a high total porosity, at least 20 percent of which consists of pores in the 120-800 A size range. They are useful as desiccants, active alumina and catalyst supports.
Abstract:
Alumina hydrates of improved purity and enhanced whiteness are recovered from impure alkali aluminate liquor by contacting the liquor with an active alumina to remove by sorption undesired color bodies and metallic impurities.