Rubicon Minerals has released updated resources for its Phoenix gold project in Red Lake, Ontario with 811,000 oz. of gold in the measured and indicated category and 464,000 inferred oz.
The update features 3.9 million measured and indicated tonnes at 6.45 g/t gold with an additional 2.1 million inferred tonnes at 6.97 g/t gold, which represents a global increase in tonnes as well as a modest increase in grades compared to the 2019 resource.
The growth of the measured and indicated resource is due to infill drilling completed last year. The drill program was aimed at upgrading resources above the 976 metre level; the entirety of this resource class sits above this elevation.
The current measured and indicated resources are near existing underground infrastructure.
“The expansion of the measured and indicated mineral resource estimate above 800,000 oz. has given us the confidence to begin mine planning and engineering work at the Phoenix gold project, with the goal of demonstrating the project’s commercial viability,” George Ogilvie, the company’s president and CEO, stated in a news release. “We have accordingly initiated a feasibility study on the project and anticipate its completion in the second half of this year.”
The drill program was aimed at upgrading resources above the 976 metre level; the entirety of this resource class sits above this elevation
Current resources are contained within the F2 zone, which covers a strike length of approximately 1,200 metres and extends down to the 1,403 metre level and remains open on strike and at depth.
The main elements of the geological and structural model for the project developed in 2018 remain valid at depth at the F2 zone. The company has updated its structural model with a remodeling of one of the primary fault zones in the Red Lake district, which extends along the western part of the F2 zone.
In addition to completing a feasibility study this year, work is also ongoing on surface to upgrade the existing tailings facility, as well as to analyze tailings for paste backfill design. There is also an operational hoist, camp and water treatment plant at the site.
The company sees additional upside potential from infilling and upgrading 190,000 oz. of inferred resources between the 976 metre and 1,098 metre levels, which could be added to the feasibility study mine plan. Drilling at depth has started. Additional target areas have been identified which the company plans to drill in the future.
Last year, Rubicon released a preliminary economic assessment for Phoenix which outlined an underground mine producing an average of approximately 80,000 oz. of gold annually at all in sustaining costs of $882 per oz. with head grades of 5.31 g/t gold.
The project would feature ramp access and ore skipping from the 610 metre level; mining would be done predominantly with bulk methods. The initial capital costs were estimated at C$101 million with an associated C$135 million project net present value, at a 5% discount rate and a 40.2% associated internal rate of return.
In the past, the geological understanding of the deposit was a challenge for the company. Test mining of the deposit commenced in 2015, based on a resource update issued in 2013. At the time, Rubicon skipped the feasibility stage and the mining scenario was based on a preliminary economic assessment. After it ran into trouble with grade reconciliation, the company decided to re-analyze the deposit.
Mining was suspended by late 2015. Ogilvie, stepped in as CEO in late 2016 and Rubicon started a reinterpretation of the deposit in 2017 (as a Riedel shear system). After months of validating its model against underground data, it arrived at a more continuous deposit model which could now potentially allow extraction through bulk mining methods.
In 2018, the company extracted a 32,551 tonne bulk sample with processing results indicating a positive reconciliation to the 2018 mineral resource estimate. The sample was mined using the bulk sublevel longhole stoping method.
Oligvie was the CEO of Kirkland Lake Gold between 2013 and 2016 where he led the operational improvement at the Macassa mine.
(This article first appeared in the Canadian Mining Journal)