Cigar Leach Hydrogen Mitigation Project

Process Hazard Analysis, Feasibility Study, Basic and Detailed Engineering, Commissioning

Orano Canada Inc. (AREVA Resources Canada Inc.) | Saskatchewan, Canada | May 2013 – September 2014

15-month condensed schedule from initial PHA to commissioning.

Leaching circuit upgraded to process high-grade uranium ore.

Project completed on-schedule and on budget with excellent safety record.


  • Orano’s McClean Lake facility is an existing uranium processing plant located in Northern Saskatchewan, Canada.
  • As a result of changing the uranium ore feed to a high-grade material, Orano’s laboratory testing program identified in the potential risk hydrogen evolution during leaching.
  • As a consequence, to hydrogen evolution, Orano became concerned that the existing leaching equipment may not be equipped with adequate safeguards to manage the hydrogen, which posed a safety risk.



  • Orano approached Hatch to assist with evaluating the design modifications for the McClean Lake leach circuit to ensure that it would be able to safely process the Cigar Lake high-grade uranium ores.
  • Hatch’s High Pressure Metallurgy (HPM) practice commenced support with a process hazard assessment (PHA) review with the McClean Lake operations team, including process, operations, maintenance and engineering members.
  • The project required several trade-off studies to determine the best solutions to repurposing the existing process equipment and resolving the hydrogen concern.



  • The results of the PHA resulted in HPM completing a feasibility study (FEL3) and immediately progressing to basic engineering and detailed engineering (FEL4) for the proposed circuit upgrades.
  • Commissioning of the upgraded leach circuit was achieved in September 2014.
  • This was a brownfield, schedule driven project that included repurposing of existing process equipment, limited space for new process equipment, demolition of existing infrastructure, and effective design considerations to help optimize the overall schedule.
  • The modifications to the process equipment included:
    • Upgrading seven leach vessels with new agitators to provide adequate solid suspension and blending.
    • Design enhancements to enable slurry feed forward control.
    • Installation of hydrogen and oxygen analyzers.
    • Installation of dilution air and vent gas exhaust systems.
    • Installation of emergency back-up systems including repurposed diesel generators, uninterrupted power supply, and a passive nitrogen purge system.

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