Determination of cuprous ions in the presence of ferrous ions

Scope:

Determination of cuprous ion in the presence of ferrous ion in electrochemical copper leach solutions

Principle:

Acidified aliquots of electrochemically-derived copper leach feed solution containing iron are titrated against standard potassium dichromate to a second exothermic endpoint. The presence of ferrous ion appears to protect the cuprous ion against oxidation. The cuprous content is determined from the difference between the first (ferrous) and second (cuprous) endpoints

Cr2O72− +14H+ +6e− ⇔2Cr3+ +7H2O [Cu+ ⇔Cu2+ +e−]×6

Cr2O72− +14H+ +6Cu+ ⇔6Cu2+ +2Cr3+ +7H2O