Dimensional Analysis Applied to the Dissolution and Disintegration of Alumina Rafts: The Riddle of Dissolving Alumina Rafts Solved

With increasing concerns about environmental performance and workplace security, the production of primary aluminum encounters many challenges. Among them is the introduction, dissolution, and distribution of large quantities of alumina into a small volume of electrolyte with a large horizontal surface using only a limited number of discrete injection points. Typically, one kilogram of alumina is injected at each location every minute or so, which agglomerates and creates rafts limiting the dissolution rate. More importantly, to prevent instability, the rafts must disappear from the rafts injection point before the next addition, either as a result of dissolution, transport, or disintegration. The work presented uses a dimensional analysis to quantify the dissolution and disintegration rate of alumina raft. A theoretical approach is proposed to understand the key behaviors observed from extensive experimental work on the dissolution of different macroscopic forms of alumina. Finally, the potential application of the model proposed is also presented.