Cigar Leach Hydrogen Mitigation Project

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.

Challenges

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.