DEVELOPMENT OF PARTICLE BREAKDOWN AND ALUMINA STRENGTH DURING CALCINATION

Since the replacement of rotary kilns with stationary calciners, the impact from hydrate properties and calcination technology on the quality of Smelter Grade Alumina (SGA) have been studied frequently. F.L. Smidth is studying the complex interaction between calcining conditions, particle breakdown and development of alumina particle strength in both Pilot-scale and industrial calcination units using conventional analytical techniques. The pilot-scale units is simulating the pre-calcination step at 320-380oC, common to all stationary calciners and the final calcination stage at 1070oC in Gas Suspension Calciners without Holding Vessel. The calcining capacity of the full scale units are ranging from 2200-4500 TPD of SGA and cover stationary calciners with and without Holding Vessel. Representative hydrate samples from eight (8) different alumina refineries are fl ash calcined and compared. The first results of the above work will be presented with focus on how the calcining conditions impacts the properties of calcined industrial hydrates with respect to alumina strength and particle breakdown.