Density and Viscosity Coefficients of Acidic Copper Sulfate Solutions Containing Added Impurities

Abstract

Density and viscosity coefficients were determined for acidic copper sulfate solutions and those containing one of the sulfates such as NiSO4, FeSO4, Fe2(SO4)4, and As 2O3 over a temperature range of 20 to 70°C. These four compounds were taken as typical impurities affecting the physical properties of the electrolyte solutions forelectrolytic refining and winning of copper. The concentration of the sulfates investigated in this work ranges asfollows: H2SO4, 0-225g/l; Cu, 0-70g/l; Ni, 0-30g/l; Fe (II), 0-15g/l; Fe (III), 0-15g/l; As, 0-10g/l.Empirical equations were developed to describe the variation of density and viscosity coefficient with the solution composition and temperature. The following expression fits all the observed values of density with a sufficiently small standard deviation of 0.0007g/cm3.ρ(9/cm3) =1.0087-(4.1×10-4+1.0×10-4 [H2SO4] +1.4×10-4 [M]) t+ (6.26×10-2-5.7×10-3 [M])[H2SO4] +0.1570 [M][M](mol/l) =[Cu] +0.98 [Ni] +0.93 [Fe (II)] +1.15 [Fe (III)] +0.5 [As (III)]where [M] is a modified concentration of the sulfates and calculated from the analytical value (mol/l) for each metal ion in the solution at 20°C and t is temperature in °C.Dependence of the viscosity coefficient on the solution composition is expressed by a quadratic function of the acid concentration and a modified concentration of the coexisting sulfates at each temperature. The variation of viscosity coefficient is presented by a 3-dimensional diagram covering the whole range of the concentrations of sulfuric acid and copper sulfate under consideration.The temperature dependence of viscosity coefficient is described by η(cP) =η cm3;0 exp (Ev/RT)where η0 (cP) and Ev (J/mol) are given as follows:η0=0.00209+0.0005 [H2SO4] + (0.00013-0.00051 [H2SO4])[Cu] Ev=14920+(1440+398 [H2SO4])[Cu]