ELECTRODEPOSITION BEHAVIOUR OF COPPER FROM ORE LEACHATE AND ELECTROLYTE SOLUTION OF COPPER AMMONIUM SULPHATE

Abstract

The electrodeposition behaviour of copper from ore leachate and synthetic copper ammonium sulphate solutions was investigated using cyclic voltammetry with a platinum electrode. The work is carried out to understand the deposition behaviour of copper from the ore for hydrometallurgical and electrowinning application. The chemical reduction and deposition of copper from both solutions consisted of two reversible electrochemical processes, each involving the transfer of a single electron. The Cu(NH3)4 complex in the copper leachate is first reduced to Cu(NH3)4  before being reduced to metallic copper. With synthetic copper ammonium sulphate (Cu(NH3)4SO4), the reduction to metallic copper is a ligand-coupled electron transfer reaction which proceeds as two sequential, single-electron transfer processes. The Cu/Cu(NH3)42+  redox reaction during electrodeposition of copper from the leachate is fast compared to that of the Cu/Cu2+ redox reaction in the Cu(NH3)4SO4 synthetic solution. Investigation of the electrochemical kinetics shows that the cathodic peak current varied linearly with the square root of the scan rate. This indicates that the Cu(NH3)4 and Cu(NH3)4SO4  reduction to Cu proceeds through a 4 diffusion-controlled process. KEYWORDS: Copper ore, Electrolyte, Cyclic voltammetry, Electrodeposition, Electrowinnin