Electrowinning presentation, Slides of Chemical Separation Processes

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• Introduction
• Fundamentals and engineering
• Significance and applications
• Industrial examples
• References 2

Content

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Location in the process chain

ROM ore Mineral Processing (crushing/ screening...) Leaching Purification Electro- winning Refining

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Electrowinning vs Electrorefining

Electrowinning Electrorefining

• Electrolysis with insoluble anodes
• High purity metal cathodes obtained out of concentrated solution
• Inert anodes to form oxygen from water dissociation
• Should not have noble impurities and ignoble ones must be removed - Electrolysis with soluble anodes - Impure metal anode is refined by depositing high purity metal cathodes - Impurities can form "anode slime" or remain in solution

Faraday’s Law Mass change ∝ charge transfer Q: Total charge passed through the substance n: number of electrons transferred per molecule or atom F: Faraday’s constant (96.485 C/mole) M: Mole of the substance 7

Theoretical Fundamentals

When normalized, i: Current density I: Current, charge spent per unit time n: number of electrons transferred per molecule or atom F: Faraday’s constant (96.485 C/mole) M: Mole of the substance SINReM Wiki 2019 - Electrowinning

Current Efficiency: 𝐼𝑝𝑟𝑜𝑑𝑢𝑐𝑖𝑛𝑔 𝑚𝑒𝑡𝑎𝑙 / 𝐼𝑎𝑝𝑝𝑙𝑖𝑒𝑑 𝑡𝑜𝑡𝑎𝑙 Practically: 8

Theoretical Fundamentals

Heavily affected by side reactions! Current efficiency of:

• Direct EW: ≈65%
• Post SX: ≈95% SINReM Wiki 2019 - Electrowinning

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Practical Fundamentals

Resource Recovery and Recycling Techniques Lecture Notes Tankhouse arrangement:

• Electrolyte feed parallel to all cells
• Barren solution exits from center

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Significance and applications

Difficult Electrowinning Easy Molten salt electrowinning Electrowinning Cr Electroplating

Thank you! 13

Werner, J. M., Zeng, W., Free, M. L., Zhang, Z., & Cho, J. (2018). Modeling and Validation of Local Electrowinning Electrode Current Density Using Two Phase Flow and Nernst–Planck Equations. Journal of The Electrochemical Society , 165 (5), E190–E207. https://doi.org/10.1149/2.0581805jes Abbey, Charles Ebenezer, "Improving base metal electrowinning" (2019). Doctoral Dissertations.

2770. https://scholarsmine.mst.edu/doctoral_dissertations/ Electrowinning. (2021). Metso Outotec Electrowinning Capital Equipment. https://www.mogroup.com/products-and- services/plants-and-capital-equipment/hydrometallurgy/electrowinning/ P. E. Aqueveque, E. P. Wiechmann and A. S. Morales, "System for the Measurement of Cathodic Currents in Electrorefining Processes That Employ Multicircuital Technology," in IEEE Transactions on Industry Applications, vol. 46, no. 5, pp. 1764-1768, Sept.-Oct. 2010, doi: 10.1109/TIA.2010.2057496. Zaldívar copper mine annual reports and open-source data: | Production Process Minera Zaldívar (minerazaldivar.cl) 14

References