The White Pine North Project is a brownfield copper-silver mine in Michigan, the US, being developed by a joint venture (JV) of Kinterra Copper USA and Highland Copper.
The JV partners, Kinterra Copper USA and Highland Copper, hold 66% and 34% interests in the project, respectively.
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A Preliminary Economic Assessment (PEA) and mineral resource estimate for the project was issued in September 2023.
The PEA estimates the copper-silver mine to have a life of 21.8 years at a processing rate of 15,000 tonnes per day (tpd).
The initial capital costs, including direct, indirect and contingency costs, are estimated to be $880.4m. However, the expenditure is expected to reduce to $615.2m after gaining a pre-production revenue of $265.2m.
The partners are working to advance the White Pine North project toward permitting and feasibility study.
In April 2024, the joint venture partners completed the winter drilling programme at the property. The campaign primarily involved collecting samples for metallurgical and geological testing for feasibility study work.
White Pine North Project Location
The White Pine North Project, which is the extension of the historical White Pine mine, is located approximately 7.5km south of Lake Superior in Ontonagon County in Michigan.
The site is situated in the historical copper range district of the Upper Peninsula, which has well developed infrastructure.
Overall, the project covers approximately 4,500 hectares (ha) of surface rights and approximately 11,990ha of mineral rights.
The project site is accessible via Michigan State Highway 64, and is near several communities. The Ironwood, Hancock, and Marquette airports are the nearest airports with commercial services.
White Pine North Project History
In 1865, copper-bearing Nonesuch shale was first discovered in the bed of the Little Iron River resulting in the opening of the Nonesuch Mine, around 3.2km west of the White Pine Mine.
The original White Pine Mine started in 1879 on the bank of the Mineral River.
The properties were purchased by Calumet and Hecla Mining (C&H) in 1907. It conducted diamond drilling and built a railroad spur and 1,000-short tonne-per-day capacity ball mill.
The mine produced 18 million pounds of copper and 260,000oz of silver from 1915 to 1920.
Construction of the White Pine Mine commenced in March 1952 and the first ore was brought to the surface in March 1953.
The construction of the mill was completed in 1954 and the first pour of copper in the smelter was achieved in January 1955. It was expanded in 1965 with an additional mine shaft, a mill section, and a second furnace in the smelter.
The mine was acquired by Louisiana Land & Exploration in 1977 with CRC becoming a subsidiary of the company. The property was put on sale in 1982 due to low copper prices and increasing production costs.
It went through a series of ownership changes until Highland subsidiary Upper Peninsula Copper Holdings announced interim closing of the acquisition of the White Pine Project in 2014. The deal achieved final closure in 2021.
White Pine Copper, then a subsidiary of Highland Copper, received rights, obligations, and responsibilities of CRC as a part of the agreement stipulated in a Judicial Consent Decree of 1997. The company signed a 20-year lease agreement for mineral rights in the White Pine North project area in April 2015.
A joint venture agreement was signed between Highland Copper and Kinterra Copper in July 2023 for the project. The partners also agreed to invest $30m to advance the project through permitting, infill drilling and feasibility study.
Geology and Mineralisation
In the area of the former mine, copper is present at the bottom 6m of the Nonesuch Formation.
In the lower part of the Nonesuch Formation, the shale and siltstone are divided into two mineralised shale units- the Upper Shale and the Lower (Parting) Shale.
With mineralised units laterally present over a stretch, the Parting Shale and the Upper shale have an average thickness of 2.2m and 3m respectively.
The copper mineralisation in the project occurs as fine-grained sulphide (chalcocite) and native copper.
The sulphide mineralisation accounts for 85-90% of the copper in the deposit, while native copper mineralisation occurs as sheet copper and mineralised sandstone.
Mineralisation of the White Pine North Project was determined as a reduced facies stratiform sediment-hosted copper deposit.
White Pine North Mineral Resource Estimate
The total (indicated + inferred) mineral resource estimate of the White Pine North Project is 247.1Mt.
Indicated mineral resource estimate is 150.7 million tonnes (Mt) containing 3,497Mlbs copper at a grading of 1.05% and 65.5Moz silver at a grading of 13.5g/t.
Inferred mineral resource estimate of the mine is 96.4Mt containing 2,183Mlbs copper at a grading of 1.03% and 27.8Moz silver at a grading of 9g/t.
Based on the resource estimate, the mine plan includes a mineralised material of 115.8 million tonnes at 0.97% Cu and 11.09 g/t Ag, containing 2.47 billion pounds of copper and 41.3 million ounces of silver.
Mining and Ore Processing
The White Pine North Project is planned to be mined via continuous mining and conventional jumbo-driven room-and-pillar mining methods.
The methods will include the extraction of entries and crosscuts in the mineralised zone leaving pillars to support the back. The mineralised zone has a thickness ranging from 2m up to 7.7m.
According to the PEA, the mine will produce at a rate of 5.475Mt per year. To achieve the target, up to 21 mining panel should be mined simultaneously.
The mining cycle will include drilling, blasting mineralised material mucking, transportation to a feeder breaker and the stope conveyor, scaling and ground support, for jumbo panels.
The continuous miners’ panels will involve face mining, followed by mineralised material transportation to a feeder breaker and the stope conveyor to finally ground support.
The processing plant will have a nominal throughput of 15,000tpd with a planned availability of 92%.
Ore will be grinded, classified, and roughed to produce a rougher concentrate. The rougher concentrate will be re-grinded and cleaned using three stages of cleaning with flotation cells and columns.
These cleaning stages will produce a cleaned concentrate which will be thickened and filtered to produce a final copper concentrate. The tailings will be pumped and disposed in the Tailings Disposal Facility (TDF).
Copper recovery is estimated to be 88% with a concentrate grade of 30.5% Cu, while silver recovery would be around 73.4%.
Considering a mine life of 21.8 years, average annual life of mine (LOM) payable copper production will be 93.5 million pounds and 1.2 million ounces of silver.
White Pine North Mine Infrastructure
Key elements of the copper-silver mine infrastructure will include roads, stockpiles, surface pads, an event pond, water treatment plant, communications, fuel storage, TDF and on-site and off-site buildings among others.
A new 69kV transmission line of approximately 1km in length will be required to power mining operations. Upper Michigan Energy Resources (UMERC) is expected to connect the line to the existing network.
The combined power capacity is estimated at 38MW. As the power limitation is 30MW on the 69 kV network, a natural gas-fired power plant will be required to supply full average power to the mine. Three generator sets are also planned for the project.
The project will receive water supplies from an existing Lake Superior pump station.
Contractors Involved
The 2023 PEA and mineral resource estimate for the White Pine North Project was prepared by G Mining Services.
The winter drilling programme, which concluded in April 2024, was conducted by Timberline Drilling with geological support from Dahrouge Geological Consulting.
