Fine α-alumina with low alkali: new approach for preparation

Thermal decomposition of fine aluminium hydroxide, synthesized by intercalation–deintercalation of lithium salts into gibbsite, was studied. It is demonstrated that thermal decomposition of fine hydroxide at 1180–1200°C results in the formation of fine α-alumina (10 m2/g) with low alkali content, forming pseudomorph with respect to the initial hydroxide. This allows to propose a new method to synthesize fine α-alumina, based on thermal decomposition of fine aluminium hydroxide obtained by intercalation–deintercalation of lithium salts into gibbsite. The major advantages of this method are the absence of wastes at the stage of the synthesis of fine hydroxide, relatively low temperature of α-alumina synthesis (1200°) at the absence of any fluorinating agents, and the absence of the necessity for thorough grinding of the synthesized α-alumina.