tailieunhanh - Extractive Metallurgy of Copper 4th ed. W. Davenport et. al. (2002) Episode 10

Tham khảo tài liệu 'extractive metallurgy of copper 4th ed. w. davenport et. al. (2002) episode 10', kỹ thuật - công nghệ, cơ khí - chế tạo máy phục vụ nhu cầu học tập, nghiên cứu và làm việc hiệu quả | Electrowinning 337 Future Developments Copper electrowinning s most important need is a truly inert anode Dattilo and Lutz 1999 Delpancke et al. 1999 . Today s lead alloy anode is satisfactory but it corrodes slowly and slightly contaminates the electrowon copper. In 2002 the leading candidate for an inert anode is the iridium titanium lead sandwich. Fig. . The IrO2 and titanium layers provide inertness. The Pb-alloy center provides toughness. The potential advantages of this anode Hardee and Brown 1999 Hiskey 1999 are a minimization of Pb contamination b reduced need for cell cleaning c a to volt decrease in oxygen overpotential. Advantage c lowers electrowinning energy consumption and decreases the need for Co additions to electrolyte. The disadvantages of the new anode are its cost and its need for gentle handling to avoid penetrating the IrO2 Ti surface layer . Full-size anodes have been given 6-month trials in industrial copper electrowinning cells Hardee and Brown 1999 . Full-scale industrial tests are expected. Summary Electrowinning produces pure metallic copper from leach solvent extraction electrolytes. About million tonnes of pure copper are electrowon per year. Electrowinning entails applying an electrical potential between inert Pb-alloy anodes and stainless steel occasionally copper cathodes in CUSO4-H2SO4-H2O electrolyte. Pure copper electroplates on the cathodes. 02 is generated at the anodes. The copper is stripped from the cathode and sold. The o2 joins the atmosphere. The Cu depleted electrolyte is returned to solvent extraction for Cu replenishment. Electrowon copper is as pure or purer than electrorefined copper. Its only significant impurities are sulfur 4 or 5 ppm and lead and iron I or 2 ppm each . Careful control and attention to detail can decrease these impurity concentrations to the low end of these ranges. 338 Extractive Metallurgy of Copper Suggested Reading Dutrizac . Ji J. and V. Ramachandran 1999 Copper