Iron Mining and Iron Resources: Western Gogebic Range,

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Prepared by Bruce A. Brown of Wisconsin Geological and Natural History Survey, this presentation is for the Jan 19, 2011 public meeting on the proposed iron mine in northern Wisconsin.

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IRON MINING AND IRON RESOURCES;WESTERN GOGEBIC RANGE, WISCONSIN : 

IRON MINING AND IRON RESOURCES;WESTERN GOGEBIC RANGE, WISCONSIN Bruce A. Brown WISCONSIN GEOLOGICAL AND NATURAL HISTORY SURVEY MADISON, WI

MAJOR IRON MINING DISTRICTS : 

MAJOR IRON MINING DISTRICTS

IRON RESOURCES OF WISCONSINLocations in Wisconsin where iron reserves have been mined or are known to exist R.W. Marsden estimated the western Gogebic range contained up to 3.7 billion tons of ore : 

IRON RESOURCES OF WISCONSINLocations in Wisconsin where iron reserves have been mined or are known to exist R.W. Marsden estimated the western Gogebic range contained up to 3.7 billion tons of ore

WHAT DOES TACONITEIRON ORE LOOK LIKE? : 

WHAT DOES TACONITEIRON ORE LOOK LIKE? Banded iron formation originated as sedimentary rock. Red bands: iron-rich silica (chert or jasper) Gray bands: iron oxides (hematite or magnetite)

GOGEBIC MINING HISTORY : 

GOGEBIC MINING HISTORY Iron ore discovered mid-1800s, mining began in 1880s and continued through 1965. Nearly all mining was underground, with larger mines reaching nearly a mile deep. Ore was secondary iron oxides (up to 60% iron). Known as natural or direct shipping ore, it required no on-site processing beyond crushing. Natural ore depleted in WWII, technology changed to take advantage of large resources of low-grade ore. The taconite process is used for turning siliceous ore (20% iron) into pellets containing 60% iron.

MINING IN THE OLD DAYS (pre-1965) : 

MINING IN THE OLD DAYS (pre-1965) At deep underground mines, head frames such as this (right) were used to lower miners and equipment and hoist ore. Ore was loaded directly into rail cars for shipment to the docks at Ashland with little or no on-site processing. Aerial view of the Cary site (1950s?) shows minimal surface footprint. Newport Mine Cary site

HOW IS TACONITE MINING DIFFERENT FROM THE NATURAL ORE MINES OF THE PAST? : 

HOW IS TACONITE MINING DIFFERENT FROM THE NATURAL ORE MINES OF THE PAST? Mining costs dictate that taconite is mined by open pit method, leading to a larger environmental footprint and higher reclamation costs. Taconite concentration requires a mill and pelletizing plant, and produces fines or tailings which require management as a waste product. Ore processing uses significant amounts of water and produces waste water. Taconite has never been mined on the Gogebic, but Wisconsin has experience regulating and reclaiming similar mines. Underground mines predated current mining regulations.

R.W. MARSDEN’S 1978 PIT DESIGN57degree pit slope, 300-foot pit floor width : 

R.W. MARSDEN’S 1978 PIT DESIGN57degree pit slope, 300-foot pit floor width

WHAT DOES A TYPICAL MODERN TACONITE MINE LOOK LIKE? : 

WHAT DOES A TYPICAL MODERN TACONITE MINE LOOK LIKE? The Empire and Tilden Mines now operating in the Marquette District of Michigan are large open pit mines. Ore is concentrated in a mill and processed into pellets, which are hauled by rail to ore docks and loaded on ships for transport to the steel mills.

WHAT EXPERIENCE DO WE HAVE WITH TACONITE MINING IN WISCONSIN? : 

WHAT EXPERIENCE DO WE HAVE WITH TACONITE MINING IN WISCONSIN? The Jackson County iron mine, a small magnetic taconite operation, was active from 1969 until the early 1980s. The mine and mill site have since been reclaimed as a county park.

WILL IRON MINING RETURN TO THE GOGEBIC? : 

WILL IRON MINING RETURN TO THE GOGEBIC? There is plenty of iron, but steep dip limits the depth to which open pit mining is economically practical. Environmental regulations and aesthetic factors will play a large role in the permitting process. This will be a “green field” project, requiring significant new infrastructure and upgrades to existing infrastructure. The future of this proposed mine ultimately depends on the economics of the world iron ore market and the future of the domestic iron and steel industry.

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