Relationship Between Electric Conductivity and Ion Structure of Sodium Aluminate Solution

A better understanding of the relationship between transference number of aluminate anions(t) and the structure of sodium aluminate solutions is of great significance for strengthening and optimizing the alumina production technologies.Combining with the characterization of FTIR analyses of the solution,the intrinsic relationship between the electric conductivity and the structure of sodium aluminate solutions was investigated by measuring the electric conductivity of the solution and calculating t in the solution of different alkali concentration and molar ratio of Na2O to Al2O3.The results show that in the solution of low concentration of c(Na2O)175 g/L,the aluminate anions dominantly exist in the form of Al(OH)-4 and t is approximately 0.6;that in the solution of medium concentration of c(Na2O) from 175 g/L to 330 g/L,the aluminate anions mainly exist in the form of Al(OH)-4 and [Al2(OH)8(H2O)2]2-,in which t is approximately 0.2;and that in the solution of high concentration of c(Na2O)330 g/L,aluminate anions exist dominantly in the form of Al2O(OH)2-6 and [Al2(OH)8(H2O)2]2-with a little Al(OH)-4,where t is almost zero.This illustrates that the electric conduction ability of the aluminate anion in the sodium aluminate solution is closely related to its structure.