Jiangyu Yu

Study on the thermal decomposition of aluminium chloride hexahydrate

ABSTRACT This paper presents a preliminary study on the thermal decomposition process of aluminium chloride hexahydrate (AlCl3·6H2O) crystal with non-isothermal thermal kinetic analysis and static calcination experiments. The ‘kinetic triplets’ including activation energy, pre-exponential factor and mechanism function for the decomposition reaction were determined through thermal analysis from Differential Scanning Calorimetry–Thermos Gravimetric Analysis results. It is found that the average activation energy and pre-exponential factor were 59.668 kJ mol−1 and 6.67 × 105 min−1, respectively, and the most suitable conversion function was . The emission rates of the gaseous products, water (H2O) and hydrogen chloride (HCl), were calculated from the chlorine content evolution obtained from the static calcination tests, respectively. The phase transformation and the change of particle morphology during the decomposition process were also investigated through X-ray diffraction and scanning electron microscope technologies.

Discussion on Alumina Dissolution and Diffusion in Commercial Aluminum Reduction Cell

Dissolution model for smelting grade alumina (SGA) in the commercial reduction cell should take into account both thermodynamic and kinetic factors because of the specific dissolution environment in the cell referring to bath chemistry condition and feeding strategy. Earlier dissolution model are mainly focused on the dissolution mechanism and laboratory kinetics, while few considerations on the effects of industrial dissolution kinetics. This paper presents measurements on the velocity (by adding traceable element—strontium ‘Sr’) of the bath were carried out on two 400 kA commercial cells, and the effects on the SGA dissolution rate are discussed to support an initial investigation for the establishment of an advanced dissolution model for alumina.