Microstructure and Properties Analysis of Aluminium Smelter Crust

As a protective top layer of an aluminium reduction cell, crust is a consolidation of anode cover materials which are made of a mix of crushed bath and alumina. Crust through its strength and barrier properties (air, HF) plays a vital role in maintaining overall heat balance, protecting anode and controlling fluoride loss. Numerous studies have investigated the crust formation. However, there is currently a significant knowledge gap regarding the microstructure and mechanical properties of crust. The mechanical properties of crust are important for the recycling of the material as crushed bath which will then become new cell crust. This research has conducted the microstructure and compressive deformation analysis on a range of crust samples for the first time. The crust samples from industrial cells have been divided into two categories: drop and shattered (DS) and uncrushable (U) crust samples. Both DS and U crust samples have shown brittle fracture, but the compressive deformation of U samples shows unique plateau deformation and hardening stages, which is due to well-developed corundum and its well-spread interlocking network with bath structure.