Aluminum electrolysis in the KF–AlF3–Al2O3 melts and suspensions

A.Yu. Nikolaev, A. S. Yasinskiy, A. V. Suzdaltsev, P. V. Polyakov, Yu. P. Zaikov

ABSTRACT:

The cathode polarization of tungsten in the KF–AlF3–Al2O3 melts and suspensions was studied.  The effects of the process temperature (670, 715, 750, and 800°С), [KF]/[AlF3] ratio (1.3 and 1.5 mol/mol), Al2O3 content (melt, saturated with Al2O3 and suspensions with 30 and 45 wt % Al2O3) on the cathodic overvoltage and the limiting current density of the aluminum electrowinning from the KF–AlF3–Al2O3 melts and suspensions were defined. The data analysis  revealed that  adding  the solid particles of Al2O3 into the KF–AlF3–Al2O3 melt hampers the diffusion of the electroactive ions to the tungsten cathode surface. Optimal parameters were established and a possibility of the aluminum production during the electrolysis of the KF–AlF3–Al2O3 suspension with 45 wt % Al2O3 in the solid phase at a temperature of 710–720°C was shown.

KEYWORDS:

 melt, KF–AlF3, suspension, polarization, diffusion, electrolysis, aluminum