Toowong Process Pilot Plant Toowong Process Pilot Plant

Toowong Process Pilot Plant

This page is about the 2012 pilot plant trial of the Toowong Process.  For more information on the Toowong Process itself, please visit this page.


In late 2012, Core carried out a $4.5m integrated pilot Float-Leach-Pressure Oxidation (POx)-Precipitation flowsheet to demonstrate a new process for removing arsenic from copper concentrates – known as the Toowong Process. The process was developed by Core’s engineers to address a key challenge facing copper operations globally. A number of smaller pilot trials were carried out during the development of the process, culminating in a large integrated pilot programme.

Arsenic Removal From Copper Concentrate

The hydrometallurgy pilot treated approximately 1,600 kg of flotation concentrate across a 34 day period of continuous operation. Flotation concentrate was prepared and milled by Core ahead of the leach pilot programme. A customised leach feed system enabled a low feed rate of 1-2 kg/h to a train of 6 high caustic, anaerobic leach tanks. A bank of custom automatic filtration vessels (to minimise handling of hot caustic solutions) processed leach slurry, with filtrate being passed to a 18.75 L batch autoclave. Oxidised liquor from the autoclave passed arsenic in solution to a train of 7 precipitation tanks, where arsenic was removed and fixed in a disposable form. Liquor from the precipitation train passed through an evaporator to concentrate the caustic solution before being recycled back to the head of the leach train.

All components of the feed, leach and precipitation circuits were on weigh scales, and fully integrated into an onsite data acquisition and PFD display system.

All data, including plant data, analytical results and metallurgical accounting were reviewed on site with the client at daily operational meetings.

Analytical methods to support the pilot campaign were developed and conducted by our in-house laboratory. The laboratory’s HPLC instrument was acquired during this period to enable specialist method development for very high ionic strength leach streams, and for arsenic, antimony and sulphur speciation.

The pilot successfully demonstrated the Toowong Process, achieving in excess of 90% reduction in arsenic levels in the treated concentrate.

Read More About The Toowong Process


Key to this programmes success were:

  • The advanced flowsheet development expertise of Core’s senior engineers to develop a viable processing solution to successfully remove arsenic from copper concentrate.
  • The process design expertise of Core’s engineers to design, fabricate, commission and execute a complex pilot flowsheet operated at a low flow rate and including integration of batch POx between a continuous leach and continuous precipitation circuit.
  • Core’s specialist method development assay laboratory, who were able to provide sophisticated analysis of process streams, a critical factor in understanding and controlling the chemistry of the As leach procedure.

  • Successful management of significant hazards (very high caustic solutions at high temperature, and autoclave work) with no serious safety incidents.
  • The quality and dedication of Core’s technical staff, enabling Core to carry out a very complex integrated process flowsheet pilot plant at very low flow rates.
  • Satisfying our client’s technical needs for a collaborative approach to the design of the pilot.