EVALUATION OF SMELTER GRADE ALUMINA QUALITY WITH SPECIAL REFERENCE TO PARTICLE MORPHOLOGY

Satpathy, B.K. and Seth, M.M.

Factors responsible for the alumina quality are broadly process based and to some extent method of calcination. While presence of impurities in alumina is undesirable to the smelting of the same, the major parameter of concern is particle size. The attrition in alumina particles is dependent on the particle morphology and distribution pattern of particle size, which govern the strength of the particles.

In the present study efforts have been made to statistically analyse the important quality parameters of NALCO alumina over the years with reference to the particle morphology. Efforts have also been made to analyse the reasons for varying attrition values of alumina through experimentation. The study has been supported with Scanning Electron Micrographs of alumina hydrate obtained under different conditions of precipitation. The paper describes the formation of a Pseudo mosaic type crystal structure in growth-based precipitation at relatively higher temperature, tending to yield lower strength particles. However, a stable precipitation condition at lower temperature results in a relatively lower attrition product with acceptable particle size.