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38 AUGUST 2017 MATERIALS PERFORMANCE NACE INTERNATIONAL: VOL. 56, NO. 8 FIGURE 2 E g (dashed lines) and i g (continuous lines) vs. time from ZRA measurements at different mineral/metal surface ratios. –200 mV vs. SHE to apparently the E corr potential shown in Table 3, which is equiva- lent to –289 mV vs. SHE at 1,200 rpm . Because of the high i g values, which are sig- nificantly higher than i corr for CS, a signifi- cant oxide build-up on the SRDE surface was noticed in all experiments. Accord- ingly, using 30 min as a time interval for the experiments was considered adequate to avoid an excessive oxide build-up. The reproducibility of these replicate experiments with 1 and 4 M/S values indi- cates a percentage error interval for i g on the order of ±30%. As expected for M/S = 1, the i g values are like those predicted from Equation (7). Conclusions • Polarization curves of copper con- centrate supported on a wax-graph- ite mixture in seawater can be mod- eled under a mixed potential theory in terms of two partial reduction and on e oxi d ation reactions that are kinetically like those of CS in sea- water. • The electrochemical kinetic param- et er for th e min eral in seawat er exhibits a high er variability than those for CS in seawater. This vari- ability is attributed to the experi- m ental pro cedure to prepare th e mineral electrodes. • The galvanic corrosion rate values predicted from experimental polar- ization curves agree with those mea- sured from the ZRA method. • The measured galvanic corrosion rate density values for the mineral in seawater ranged between 3 to 13 A/m 2 and are up to more than 10 times higher than those of i corr for steel in seawater conditions. Acknowledgments The financial support from Projects C O N I C Y T 2 1 1 2 0 8 0 3 a n d F O N D E C Y T 1070933 developed in the Chemical Engi- neering and Mineral Processing Depart- ment at the Universidad de Antofagasta, Chile is greatly appreciated. The authors are also grateful for the C SIRO (Commonwealth S cientif ic and Industrial Research Organization) Interna- tional Research of Excellence in Mining and Mineral Processing Scholarship Doctoral Program. References 1 C.M.V.B. Almeida, B.F. Giannetti, "A New and Practical Carbon Paste Electrode for Insolu- ble and Ground Samples," Electrochem. Com- mun. 4 (2002): pp. 985-988. 2 A.C. Carlos de Oliveira, S.X. dos Santos, É.T.G. Cavalheiro, "Graphite-Silicone Rubber Com- posite Electrode: Preparation and Possibili- ties of Analytical Application," Talanta 74 (2008): pp. 1,043-1,049. 3 L. Cáceres, T. Vargas, M. Parra, "Study of the Variational Patterns for Corrosion Kinetics of CS as a Function of Dissolved Oxygen and NaCl Concentration," Electrochim. Acta 54 (2009): pp. 7,435-7,443. 4 H.J. Flitt, D.P. Schweinsberg, "A Guide to Po- larisation Curve Interpretation: Deconstruc- tion of Experimental Curves Typical of the Fe/H 2 O/H + /O 2 Corrosion System," Corros. Sci. 47 (2005): pp. 2,125-2,156. 5 A. Bard, L. Faulkner, Electrochemical Meth- ods, Fundamentals and Applications, 2nd. ed. (Hoboken, NJ: John Wiley & Sons, Inc., 2001), pp. 337-340. 6 W. Yuehua, S. Wei, D. Wuang, Electrochemis- try of Flotation of Sulphide Minerals (Beijing, China: Tsinghua University Press, 2009), pp. 168-200. 7 T. Güler, et al., "Electrochemical Behaviour of Chalcopyrite in the Absence and Presence of Dithiophosphate," Int. J. Miner. Process. 75 (2004): pp. 217-228. 8 D. Rand, "Oxygen Reduction on Sulphide Minerals: Part III. Comparison of Activities of Various Copper, Iron, Lead and Nickel Mineral Electrodes," J. Electroanal. Chem. 83 (1977): pp. 19-32. 9 R.W. Revie, Uhlig's Corrosion Handbook, 2nd ed. (Hoboken, NJ: John Wiley & Sons, Inc., 2005), pp. 154-160. GENNY LEINENWEBER has an M.Cs degree in chemistry and is a Ph.D. student at the Universidad de Antofagasta, Antofagasta, Chile, email: gennyleinenwe- ber@gmail.com. She conducts laboratory work on internal corrosion using mainly API 5LX65, the most commonly used steel in Chile in the mining industry for pipes that transport water, seawater, and slurry. She also works in the area of pipeline integrity in the mining industry. LUIS CÁCERES is an associate professor at the Department of Chemical Engineering in Mineral Processing, Universidad de Antofagasta, Antofagasta, Chile in the field of electrochemistry and corrosion. CATHODIC PROTECTION