PROPERTIES OF THE SYSTEM H2O-NAOH-ZNO .1. DENSITY, VISCOSITY AND BOILING-POINT

Citation
J. Stpierre et Aa. Wragg, PROPERTIES OF THE SYSTEM H2O-NAOH-ZNO .1. DENSITY, VISCOSITY AND BOILING-POINT, Hydrometallurgy, 35(2), 1994, pp. 161-177
Citations number
49
Categorie Soggetti
Metallurgy & Mining
Journal title
ISSN journal
0304386X
Volume
35
Issue
2
Year of publication
1994
Pages
161 - 177
Database
ISI
SICI code
0304-386X(1994)35:2<161:POTSH.>2.0.ZU;2-0
Abstract
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).