DEVELOPMENT OF A FLUIDIZED BED CALCINATION PROCESS FOR ALUMINUM NITRATE WASTES IN A TWO-FOOT-SQUARE PILOT PLANT CALCINER PARTⅡ: FACTORS AFFECTING THE INTRA-PARTICLE POROSITY OF ALUMINA

摘要

A seven- to twenty-fold volume reduction can be obtained from fluidized bed calcination of aqueous aluminum nitrate wastes, depending on the operating conditions employed and their effect on the intra-particle porosity and absolute density of the calcined alumina. Among the calcin¬ing variables, only the bed temperature and the feed aluminum concentra¬tion had a significant effect on the intra-particle porosity of alumina generated during studies conducted primarily in a two-foot-square fluidized bed calciner. A quantitative correlation of the effect of these variables is presented. Alumina with an intra-particle porosity as low as five per cent can be generated by employing a suitable combination of low bed temperature and dilute aluminum feed concentration. Feed sodium concentration and product alpha alumina content were found to have minor effect on intra-particle porosity.nResults obtained incidental to the main purpose of the study show that an inverse relationship exists between the nitrate content of the calcine and the calcination temperature.