Production of copper cathode from oxidized copper ores by acidic leaching and two-step precipitation followed by electrowinning

A step by step hydrometallurgical process for the production of copper cathode was developed after a two-step precipitation from leaching solution of copper oxidized ore, followed by copper concentrate leaching and electrowinning. The copper oxidized ore was primarily comminuted to a size below 100 μ, followed by acidic leaching at 25 °C for 40 min in H2SO4 solution, in which recovery of copper and iron were 95.95% and 12.63%, respectively. To remove iron impurity, at the first step of precipitation, NaOH was added to increase pH from about 1.5 to the optimum pH of 3.8 at 60 °C for 60 min; thus iron precipitation with recovery of over 80% was achieved. Copper precipitate as concentrate was obtained in the same method from iron-removed solution. The optimum condition of copper precipitation was found to be pH of 5.5, 25 °C and 45 min with 98.69% recovery. One of the advantages of this process was production of Na2SO4 with 99.1% purity after vaporization of the remaining solution from two-step precipitation. The obtained copper concentrate was leached at approximately the same condition of the first leaching step, and then the provided pregnant solution proceeded to an electrowinning cell with lead alloy anode contained antimony and steel sheet cathode under the following condition: temperature of 50 °C, reaction voltage of 2 V and current density of 300 Am− 2. Finally, a scale-up experiment was carried out and the copper cathode with 99.99% purity produced.

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► A systematic process for production of copper cathode is developed.
► Copper cathode is obtained after leaching, precipitation and electrowinning steps.
► Each step of the process is optimized by design of experiments methods.
► A scale-up experiment is carried out and the copper cathode purity reaches 99.99%.
► Na2SO4 as a co-product is produced with 99.1% purity.