NorZinc Ltd. (TSX: NZC) has launched a preliminary economic assessment for a 2,400 t/d production plan for the 100%-owned Prairie Creek silver-zinc-lead project in the Northwest Territories.
The underground mine and mill, 200 km west of Fort Simpson, NWT, is fully permitted for 1,000 t/d. A 2017 feasibility study suggested a mining rate of 1,600 t/d. NorZinc initiated a mine enhancement program in 2020 to optimize all aspects of the project, and based on the results of this program, the company determined that a 50% increase in the mining rate to 2,400 t/d is optimal.
The PEA is to be completed in the second quarter next year with Ausenco as the lead consultant. The measured, indicated and inferred resources will be updated prior to that time.
NorZinc is conducting additional metallurgical studies to determine the variability of mercury in the ore that could be expected throughout the mine life. The metal is found in all three types of mineralization at the project. Mercury content of the concentrate will affect the price customers are willing to pay for it.
The company has applied to the Mackenzie Valley Land and Water Board (MVLWB) for a new land use permit and water licence reflecting the increased size of the project. The MVLWB indicated that it will not require an additional environmental assessment for the larger project. The Mackenzie Valley Review Board had until September 7 to initiate a new assessment, but that date has passed without triggering further actions.
A public hearing is scheduled for late November, and the permitting process should be complete early in the second quarter 2022. Meanwhile, NorZinc will retain the permits originally received in 2013 and renewed in 2020 for a 1,600 t/d operation and planned access road.
The start of mining and concentrate production is scheduled to begin in 2024.
When last updated in 2017, the resource estimate was 8.7 million measured and indicated tonnes grading 9.5% zinc, 8.9% lead and 137 g/t silver plus 7 million inferred tonnes at 11.3% zinc, 7.7% lead and 164.5 g/t silver. A cut-off grade of 8% zinc-equivalent was used.
(This article first appeared in the Canadian Mining Journal)