OPTIMIZING THE PROCESS PARAMETERS IN THE PRODUCTION OF ALUMINA

Abstract

The calcined clay was treated using HCl (32%) to obtain aluminum chloride hexa- hydrate. Three parameters were optimized using response surface methodology approach. Alumina recovery of 83.2% was predicted on using 1.4 stoichiometric acid to solid ratio, a reaction temperature of 104oC and a reaction time of 3 hours. This result was then assessed experimentally. The obtained hexa hydrate was prepared in crystalline form through injection of hydrogen chloride in the saturated solution of aluminum chloride. The hexahydrate crystals obtained were subsequently purified in a three stage process to increase their purity to 99.961%. Roasting of these crystals up to 800oC under flow of argon steam then roasting the produced amorphous aluminum oxide at 1250oC in a continuous flowing of Ar gas and keeping at this temperature for 4 hours, then cooling down to room temperature. Highly crystalline alumina was produced with purity 99.9%.