Peninsula Energy Ltd (ASX:PEN) (OTCMKTS:PENMF) (FRA:P1M) is progressing with the MU1A low-pH field demonstration at its flagship, 100%-owned Lance Uranium Project in Wyoming, USA.
Further changes to the configuration of the injection and recovery well patterns have been implemented with the intention of reducing response times for assessing and adjusting chemical parameters.
The company has also commenced the evaluation of several alternative uranium recovery process options with the object of reducing downstream processing costs.
Peninsula’s project transformation initiative at the project is aimed at changing from an alkaline ISR operation to a low-pH ISR operation to align the operating performance and cost profile of the project with industry-leading global uranium production projects.
Plan to restart commercial production
The field demonstration of low-pH In-Situ Recovery (ISR) is designed to generate comprehensive site-specific data on the influence of certain development and operational parameters ahead of a final investment decision to restart production at the project.
Peninsula managing director and chief executive officer Wayne Heili said: “The field operations team at Lance continue to apply innovative thinking and solutions to the low pH field demonstration.
“Our demonstration design was conceived with the flexibility to implement changes as we progress and this month we made additional changes which we believe can help deliver the completed test in an accelerated timeframe.
“The field demonstration continues to perform within expectations and the information gained from it will be invaluable, as the company progresses the Lance Project toward a return to commercial production.”
Improving key chemical parameters
Achieving and maintaining the correct operational pH and Oxygen Reduction Potential (ORP) for the process solutions is critical to successful uranium low-pH ISR operations.
Changes in oxidant and pattern configurations have delivered strong improvements in key chemical parameters.
With the original pattern configuration having longer than typical distances between injection and recovery wells, more than one month of operations is generally necessary to observe the impacts of operational adjustments.
Notably, the pH of each recovery well has continued moving modestly downward toward the target level during the last month.
In addition, free acid concentrations - another measure of acidity - have improved in two out of the three recovery wells.
At around 400 millivolts, the recovery stream ORP has also moved closer to the target range of 450 to 600 millivolts during the past month.
After a doubling of uranium grade to between 20 and 25 parts per million the grade has remained within this range during the past month.
Increasing uranium grades
The company has adjusted the original pattern configuration of 10 injection wells fully surrounding three recovery wells by installing and activating two new internal injection wells that are located between each pair of recovery wells.
To further reduce the expected response time for chemical parameter adjustments, the company has subsequently switched off selected perimeter injection wells that were more distant to the recovery wells, creating a pattern design with the average injector to recovery well distance reduced from 135 feet to around 80 feet.
These supplementary pattern configuration changes should accelerate the upward movement of uranium grades.
Recovery process flowsheet options
With increasing field demonstration grades, the company activated the pilot ion exchange uranium recovery circuit in early March.
Within the current range of uranium concentrations, ion exchange systems have limited capacity to capture and retain uranium, and minimal actual recovery of uranium has occurred thus far, however, the ion exchange processes are concentration driven and the system performance is expected to improve with increasing uranium grades.
Mindful of the widely understood limitations of ion exchange processes in low pH applications (including those at successfully operating commercial facilities) the company has identified and begun evaluating several innovative uranium recovery process flowsheet options.
The alternative process technologies are being evaluated progressively with desktop, benchtop and potentially pilot-scale demonstrations that can be run in conjunction with the current field demonstration.
These advanced technologies have the potential to significantly enhance downstream processing performance while reducing operating costs.