The best alternative for improving the energy efficiency of the conven
tional zinc electrowinning process is to use alkaline solutions. For t
his process, since the use of alkaline solutions means that higher cur
rent densities can be used, more heat needs to be removed from the cel
ls to avoid the electrolyte boiling and zinc redissolution may become
important at high temperatures. Control of the solution alkalinization
is essential and this has the effect of increasing the cell voltage a
nd may favor corrosion of the cell components or zinc product. Modelli
ng of alkaline electrowinning cells is not possible, however, since va
lues for the chemical, electrochemical and physical properties are not
available. The viscosity and density of aqueous solutions of sodium h
ydroxide and zinc oxide (solutions prepared at 303 K with 160-280 g/l
NaOH and 3-50 g/l Zn) were determined over a range of temperatures fro
m ambient to boiling point. Boiling point values ware also determined.
Correlations are given for the most common units of concentration (mo
lar, molal and weight percentage).