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| Electrorefining of Metals |
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| "Electrorefining of metals is a process of obtaining pure metal from the impure one by the process of electrolysis." |
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| Process |
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| The process of electrorefining of metals involves the following steps: |
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 The electrolyte is usually an aqueous solution of the salt of the metal with some corresponding acid, if necessary. |
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A thick block of impure metal is made the anode. |
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A thin rod/sheet of pure metal is made the cathode. |
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The metal cations being positive migrate towards the cathode and get discharged. |
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At anode the atoms of the metal lose electrons, form cations and enter the solution. |
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The less electropositive impurities in the anode, settle down at the bottom and are removed as anode mud, while the more electropositive impurities pass into the solution. |
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| Uses |
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Metals like silver, nickel, lead, zinc and copper are refined by this method. |
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The electrolytic method sometimes yields valuable metals in the form of anode mud e.g., silver and gold are collected in the anode-mud during the electrolytic refining of copper. |
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| a) Electrorefining of Copper |
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Electrolyte - Aqueous copper sulphate solution (acidified) |
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Cathode - Pure copper metal (thin rod) |
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Anode - Impure copper metal (thick block) |
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Dissociation of copper sulphate - |
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