Duluth has big plans for Minnesota mining – by John Chadwick (Mineweb.com – October 3, 2012)


According to the miner, truly magnificent orebodies are being revealed in an area that has already played a very important role in the US mining industry.

LONDON (INTERNATIONAL MINING) – Ore riches that built America have much more to offer. Minnesota’s Iron Ranges to the west of Lake Superior – Vermilion, Mesabi and Cuyuna from the northeast of Duluth down to the south-southwest – have been the most important ore deposits in US history, and continue to be so, providing well over 90% of the iron ore the country needs. Just a few of the great historical landmarks include the establishment, in 1901, of the world’s first multi-billion dollar corporation, US Steel.

Before that, in May 1890, Edmund Longyear (founder of one of the companies that was to become, much later, Boart Longyear) brought the diamond drill to the Iron Ranges. This exploration tool was to be a key to unlocking the riches of the region.
William Boeing made profits from the Mesabi Range and just a few other great names with Iron Ranges associations include Henry Bessemer, Frederick Weyerhaeuser, Andrew Carnegie, John D. Rockefeller, Kelsey D. Chase, and J.P. Morgan.

Of the known US mineral resources, Minnesota accounts for 99% of the nickel, 90% of the iron, 88% of the cobalt, 51% of the platinum and 48% of the palladium, 40% of the manganese and 34% of the copper. America’s third largest mining state may be poised to take the lead. In work pioneered by Duluth Metals, its Senior Vice President, Exploration, Dean M. Peterson and his innovative team, truly magnificent orebodies are being revealed in an area that has already played such an important role in the US mining industry.

Meanwhile, the iron ore is still going strong. The value of iron ore projects on the Mesabi Range (130 years of iron mining in the state) amount to some $4 billion. There are new open-pit mines being developed by ArcelorMittal and Essar Resources. The latter is initially aiming at 4.1 Mt/y of pellets by Q3 2013, and 7 Mt/y by January 2014. There is also the Keewatin Taconite upgrade and US Steel’s Minntac recently completed a six-year, $50-million upgrade of its concentrator facility. There are also the United Taconite and Northshore upgrades and the Mesabi Nugget iron nugget plant. In power there is the Excelsior Energy power plant proposal and the Minnesota Power wind generators.

There are other companies involved in the Duluth Complex, such as Teck’s Mesaba deposit and Polymet with its NorthMet deposit, but Duluth is the only one with a real exploration team on the ground, undertaking extensive work. Peterson considers that the team has advanced the understanding of the Duluth Complex well beyond the norm, and has gained insight into the magmatic system and copper-nickel-PGM deposits that rivals any company in the world.

This has resulted in a joint venture with Antofagasta to form Twin Metals Minnesota (Duluth 60%, Antofagasta 40%) and the start of a very detailed prefeasibility study for an underground copper, nickel, platinum and palladium mine, with Bechtel Mining & Metals as the lead consultant. The study is based on a vertically integrated mining complex, with a large-scale phased underground mine plan. It is evaluating different scenarios for both on- and off-site surface facility alternatives, including options in milling capacity up to some 80,000 t/d in throughput. The planned hydrometallurgical plant will likely have the minimum capability of producing copper cathode, nickel hydroxide and a PGM concentrate.

Contained metals in TMM’s June 2012 NI 43-101 Indicated resource estimate total of 8,000 Mlb of copper (another 13,500 Mlb Inferred), 2,500 Mlb of nickel (4,600 Mlb Inferred) and 12.1 Moz (15.8 Moz Inferred) of TPM (total precious metals – platinum, palladium and gold).

For the rest of this article, please go to the Mineweb.com website: http://www.mineweb.com/mineweb/view/mineweb/en/page103118?oid=159605&sn=Detail&pid=102055