Electrolytic magnesium production using coaxial electrodes

By admin

Main reason for the current losses in electrolytic magnesium production is the
reaction between electrode products. Present study was devoted to effective
separation of chlorine gas from the electrolysis environment by a new cell design
and thus reducing the extent of back reaction between magnesium and chlorine to
decrease energy consumption values. The new cell design was tested by changing
temperature, cathode surface, current density, anode cathode distance and
electrolyte composition.

Both the voltages and the current efficiencies were considered to be influenced by
the amount and hydrodynamics of chlorine bubbles in inter-electrode region. Cell
voltages were also found to be affected from the nucleation of magnesium droplets
and changes in electrolyte composition that took place during the electrolysis. A
hydrodynamic model was used to calculate net cell voltage by including the
resistance of chlorine bubbles on anode surface to theoretical decomposition
voltage during electrolysis. Good correlations were obtained between experimental
and calculated voltages. The same model was used to calculate current efficiencies

iv
by considering chlorine diffusion from bubble surfaces. A general agreement was
obtained between calculated and experimental current efficiencies.

Desired magnesium deposition morphology and detachment characteristics from
cathode were obtained when MgCl2-NaCl-KCl-CaCl2 electrolytes were employed.
Current efficiencies higher than 90% could be achieved using the above
electrolyte. The cell consumes around 8 kWh·kg-1 Mg at 0.43 A·cm-2 as a result of
high chlorine removal efficiency and capability of working at low inter-electrode
distances. Furthermore, the cell was capable of producing magnesium with less
than the lowest energy consumption industrially obtained, at about double the
commonly practiced industrial current density levels.

Gökhan Demirci
Electrolytic magnesium production using coaxial electrodes · 2006 · 170 sayfa.
Danışman: Prof.Dr. İshak Karakaya
Bu araştırmanı devamına: http://tez2.yok.gov.tr/tez.htm adresinden ulaşabilirsiniz.