Aluminium Smelter Crust—Phase Distribution and Structure Analysis of Top Zone Layer

Anode cover material (ACM) partly fuses at the bottom where it interacts with anode and bath in the aluminium reduction cell. This consolidated material is defined as the top crust in the cell, and plays a crucial role in maintaining heat balance, protecting the carbon anode from air-burning and absorbing the fluorides evaporation in the cells. Previous studies have been conducted to illustrate the crust formation and properties. However, there is rarely a systematic structural analysis of crust in the vertical direction due to the complexity and inhomogeneity of industrial crust. In the present study, the phase composition of crust was systematically analysed in the vertical direction, and five zones were identified based on the phase composition. Furthermore, two types of particles are identified in top zone (1) namely: smelter grade alumina (SGA) and crushed bath particles (CBPs). A systematic analysis on CBPs have shown four types of structural features.