Mining for Hematite

Thursday, September 10, 2015

Today we moved southwest about 50 miles to Tettegouche State Park.  This is one of the largest state parks in Minnesota.  It started out as a logging camp, as it’s location with several lakes and along the Baptism River made it ideal for logging the white and Norway Pines in the area.  In 1910 the land was acquired as a fishing retreat by some Dutch business men.  It was named the Tettegouchi Club.  In 1971 it was sold to the State of Minnesota.

There are lots of hiking opportunities, but we chose it for it’s location.    There are a few trails we plan to check out later in our stay.  

Friday, September 11, 2015

We took a journey today to the Soudan Underground Mine State Park.  The mine is located between the towns of Soudan and Tower, about 25 miles west of Ely.  The park was 85 miles from our campground.  While underground mines are not new to us, this is unique because they mined iron ore.  Most iron ore mines are open pit.

Soudan has the largest and richest veins of Hematite Fe₂O₃ which is the highly desirable version of iron ore in this area due to the higher oxygen content.  At its peak, it produced a million tons of ore per year and operated between 1892 and 1962.  US Steel gave it to the State of Minnesota in 1967.  The ore is embedded in rock, really hard rock, called Ely Greenstone.  Miners, three to a team, would drill and dynamite to free the ore.  In the early days, the only lights were candles.  One guy held the star drill and the other two alternated blows with a sledge hammer.  The drill would be rotated 1/4 turn between blows. Imagine that operation, in near darkness.  Pneumatic drills and battery powered headlamps came in use much later.

Our tour went to the 27th level, the deepest point,  2341 feet below the surface, using a hoist in operation since 1924.  We then travelled 3/4 mile to where they were mining when the operation shut down.  There were 18 men per shift, three shifts and they were employed as contractors, paid by the ton of ore produced.  A cubic foot of hematite weighs about 300 pounds. Soudan was one of the best mines to work in.  Relatively safe and dry.

This is the hoist.  The towers and cable run to the engine house, where an electric motor operates the winch.

Here is the large cable drum.  The small dial toward the center top indicates the level the skip car is at and the red circular gizmo in the lower right is a governor that controls the speed.  The operator’s position is toward the left, behind all the pipes and stuff.

This is the skip car entrance.  18 workers would be crammed into that little space for the ride down or up.

This is tram that took us back into the mine.  In the day, the miners walked this; there were no electric lights, only their headlamps using candles or carbide and later batteries.

The rail cars would be pushed by men, later hauled by donkeys, to the shaft for uploading to the top.

As you can imagine, this was incredibly hard and dangerous work.  And yet in the orientation movie many of the workers interviewed said this mine was the “Cadillac” of mines and actually enjoyed working here.

Since about 1994 they have operated a physics lab on the 27th level.  An area was newly excavated at the same 1/2 mile depth as the mine.  They are studying neutrinos and dark matter.  The location provides them to study these things without the background interference from the sun’s solar particles.

We’re not going to get into much details about this, mainly because we don’t understand it.  You can find out more by searching MINOS and CDMS.  Also http://www.soudan.umn.edu

The project is a joint Fermi and Univ of Minn effort and paid for by the Dept of Energy.  One of the cool things is that neutrinos are tiny, smaller than electrons and pass through anything.  So Fermi lab in Chicago runs these guys through an accelerator and fires them here to Soudan.  And they do get here, through all the rock! 

This is the receiving end for catching the neutrinos from Fermi Chicago.  This thing weighs like 6 tons, brought down here in pieces and assembled on the spot.

While this is all very abstract, as this type of research often is, imagine if neutrinos could be the transmission media of the future. Now, instead of bouncing radio waves off satellites, you fire neutrinos through the earth’s core. Probably a ways off in the future, but maybe possible?

All in all an interesting day!