Cementation
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Cementation Cathodic precipitation of a metal ion of a metal from solution by passing the solution over a more anodic (less noble) metal Cu 2+ +2e = Cu (cathodic precipitation Fe = Fe 2+ + 2e (anodic dissolution) Cementation is less selective than gaseous reduction
description
Cementation. Cathodic precipitation of a metal ion of a metal from solution by passing the solution over a more anodic (less noble) metal. Cu 2+ +2e = Cu (cathodic precipitation Fe = Fe 2+ + 2e (anodic dissolution). Cementation is less selective than gaseous reduction. - PowerPoint PPT Presentation
Transcript of Cementation
Cementation
Cathodic precipitation of a metal ion of a metal from solution by passing the solution over a more anodic (less noble) metal
Cu2+ +2e = Cu (cathodic precipitation
Fe = Fe2+ + 2e (anodic dissolution)
Cementation is less selective than gaseous reduction
Isolation techniques
Ion exchange: organic resins on to which either cations or anions have been loosely bounded
Solvent extraction: organic compounds – ethers, esters, ketones- provide high solubility of some metallic and complex metal ions
Reverse osmosis: concentration of metal ions by passage of water from a dilute to a more concentrated solution through a semipermeable membranes
Electrowinning
Electrowinning of a metal is based on the electrolysis of aqueous solutions or melts of metal salts with insoluble anode
Electrowinning
Electrowinning
Electrowinning
Electrorefining
Electrorefining
Electrorefining
Caron processs: laterite ore : 50% Fe - FeO.OH,
1-2% Ni - NiO, 0,1% Co - CoO
Laterite ore
Drying, Grinding
Reduction roasting
Ammoniacal leaching
Partition Ni/Co
Ni- liquor
Boiling up/filtration
NiCO3.Ni(OH)2
Calcination
NiO
Preparation of electrolyte
Electrolysis
Ni 99,9%
H2, CO
NH3 aq. (NH4)CO3
Residue Na2S
CoS
H2SO4
NH3
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