Effect of Calcination Condition on Thermal Activation of Ibere Clay and Dissolution of Alumina

Abstract

Bauxite deposits for production of alumina are lacking in Nigeria and there is an aluminium smelter plant in the country which requires alumina for its operation. Development of alternative alumina resource using clays that are abundant in the country is the focus of this paper. The thermal activation of Ibere clay from southeastern Nigeria for optimal leaching of alumina was investigated. The clay assayed 28.52% Al2O3 and 51.6% SiO2, comprising mainly kaolinite mineral and quartz or free silica. The alumina locked up in the clay structure was rendered acid-soluble by thermal activation which transformed the clay from its crystalline nature to an amorphous, anhydrous phase or metakaolinite. The clay samples were heated at calcination temperatures of 500˚C, 600˚C, 700˚C, 800˚C, and 900˚C at holding times of 30, 60, and 90 minutes. Uncalcined clay samples and samples calcined at 1000˚C (holding for 60 minutes) were used in the control experiments...