Modeling the Effect of Composition and Temperature on the Conductivity of Synthetic Copper Electrorefining Electrolyte

Abstract

Abstract:The physico-chemical properties of the copper electrolyte significantly affect the energy consumption of the electrorefining process and the quality of the cathode product. Favorable conditions for electrorefining processes are typically achieved by keeping both the electrolyte conductivity and diffusion coefficient of Cu(II) high, while ensuring low electrolyte viscosity. In this work the conductivity of the copper electrorefining electrolyte was investigated as a function of temperature (50-70˝C) and concentrations of copper (Cu(II), 40-60 g/L), nickel (Ni(II), 0-20 g/L), arsenic (As(III), 0-30 g/L) and sulfuric acid (160-220 g/L). In total 165 different combinations of these factors were studied. The results were treated using factorial analysis, and as a result, four electrolyte conductivity models were built up. Models were constructed both with and without arsenic as the presence of As(III) appeared to cause non-linearity in some factor effects and thus impacted the conductivity in more complex ways than previously detailed in literature. In all models the combined effect of factors was shown to be minor when compared to the effect of single factors. Conductivity was shown to increase when copper, nickel and arsenic concentrations were decreased and increase with increased temperature and acidity. Moreover, the arsenic concentration was shown to decrease the level of conductivity more than previously suggested in the literature.

Modelling the Effect of Solution Composition and Temperature on the Conductivity of Zinc Electrowinning Electrolytes

“…According to Aalto-I, increases in both temperature and H 2 SO 4 have a positive effect on conductivity, whereas the presence of metal ions (Zn, Mn, Mg) has a negative impact on solution conductivity. These findings are in agreement with earlier studies of Zn electrowinning conductivity [15,[24][25][26], and are similar to the behavior found for Cu, Ni, and As, in copper electrowinning electrolytes [22].…”

“…According to Aalto-I, increases in both temperature and H2SO4 have a positive effect on conductivity, whereas the presence of metal ions (Zn, Mn, Mg) has a negative impact on solution conductivity. These findings are in agreement with earlier studies of Zn electrowinning conductivity [15,[24][25][26], and are similar to the behavior found for Cu, Ni, and As, in copper electrowinning electrolytes [22]. From Figure 3, it can be seen that model Aalto-I clearly has valid coefficients throughout the parameters tested, whereas Aalto-II shows that there are valid correlations between both Zn and H 2 SO 4 with temperature.…”

“…Nevertheless, the previously published models have two major weaknesses: Firstly, the exclusion of minor impurities [15][16][17], and secondly, the utilization of a single coefficient value to represent zinc and other impurities [18,19]. Recent conductivity modelling studies in copper and silver electrolytes have demonstrated that every metal element ion present has an independent coefficient that can affect the electrolyte conductivity [20][21][22]. As a result, the main objective of this study is to develop an improved zinc electrolyte conductivity model, increasing prediction accuracy by taking into account the independent effects of metal impurities-such as Mn and Mg-along with the typical process parameters of zinc concentration, acidity, and temperature.…”

Copper Cathode Contamination by Nickel in Copper Electrorefining

“…A majority of the nickel dissolves into the electrolyte, increasing the resistivity of the electrolyte. Consequently, this increases the electricity consumption of the process [2,5]. In the anode, nickel exists primarily as NiO and kupferglimmer [3], and it has been suggested that nickel increases the porosity of the slime layer on the anode surface and causes a layered structure.…”

Analysis of a centreline failure of a lead alloy anode used in the copper electro-winning process

“…In addition to the electrical conductivity and the economic price of lead alloys, a continuous protective layer of lead dioxide is formed on the surface of the anode that is sufficiently conductive for circuit requirements and has the advantage of improving the corrosion resistance of the anode [3][4][5][6]. Since the introduction of the electro-winning technique into commercial use to produce copper, in the middle of the 19 th century [7], many improvements have been introduced to both the corrosion resistance and mechanical properties of lead anodes. Cast anodes were replaced by rolled anodes and antimonial alloys were superseded by calcium additions to the lead to increase the strength of the anode, while tin was found to have a beneficial effect on improving corrosion resistance, conductivity and oxygen evolution [4].…”