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Iron Control

Approximately 50% of the world’s copper is produced by Solvent Extraction and Electrowinning. During the solvent extraction process, copper is transferred, via an oxime extractant from the leach solution, to the copper electrowinning electrolyte. Small amounts of iron are also transferred with the copper, due to a small degree of chemical loading and physical entrainment of iron-containing leach solution in the loaded organic. This iron accumulates in the electrowinning circulation and must be controlled.

The conventional method of iron control at most sites is to bleed a volume of electrolyte from electrowinning to the leach circulation. This bleeding is effective in controlling the accumulation of iron but had a number of drawbacks. The bleed from electrowinning results in loss of acid, copper and cobalt sulphate. This has to be made up by addition of cobalt sulphate, high purity water and makeup acid as well as cobalt sulphate to electrowinning and re-extraction of copper.

At acid generating production facilities, the bleed volume increases the volume of leach solution and increases the requirement to bleed from the leach solution (due to a positive water balance). The leach solution bleed is neutralized with lime, and sent to tailings. Bleeding from the leach solution increases costs for neutralization and decreases the steady state iron levels in leach.

Process flow before Iron Control

Process flow using Iron Control









The FENIX Iron Control system replaces the bleed system of iron control. The FENIX unit loads iron from the electrowinning solution on a sulphonated monophosphonic acid resin followed by stripping using a novel cuprous sulfate elution solution. The FENIX system delivers significant savings in reagent consumption (acid and cobalt sulphate for electrowinning, lime for neutralization of the raffinate bleed) and has the potential to deliver higher current efficiencies in copper electrowinning, leading to increased copper production.

Current efficiency vs Fe in Electrolyte

FENIX Iron Control plant major equipment items

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Mount Gordon – 1st commercial installation

Fenix Hydromet installed the world’s first Iron Control system at the former Western Metals’ Mount Gordon site; the plant was designed to remove a nominal 220kg/day of iron from the site copper electrowinning solutions.  Ausenco Engineers conducted the system engineering and the majority of the equipment (skid, tanks, control cabinets – excluding the air receiver) …

FMI Morenci Arizona – Iron Control Demonstration project

The FENIX Iron Control system was transported from Australia to FMI’s Morenci operation in Arizona, USA for a successful demonstration trial in mid 2008.    

Iron Control Benefits

The operation of the FENIX Iron Control System can deliver the following benefits: Improved Copper production through reduced iron levels increasing the Electrowinning plant current efficiency Reduced losses of reagents, cobalt and high purity acid, water and anti misting surfactants Reduced burden on Solvent Extraction through reducing the amount of copper reprocessed due to a …

Awards & Papers

Fenix Hydromet were recipients of the 2005 EPD Extraction & Processing Science Award Paper Title: “The Commercialization of the FENIX Iron Control System for Purifying Copper Electrowinning Electrolytes” D. Richard Shaw, FENIX Hydromet David B. Dreisinger, University of British Columbia Thomas Lancaster, Straits Whim Creek Pty, Ltd Geoffrey D. Richmond, Amtec Limited Marcus Tomlinson, AMEC Americas published in JOM in July 2004. …