Sunday, August 21, 2011

"There's Gold in Them Thar Hills!"

"Gold in them thar hills"...despite the crude language, that phrase has sparked many a rush into the wilderness in the quest for the most precious of metals.  Gold has always kept its allure, which is especially evident in the recent days of record prices...almost $1,900 for an ounce!  Is it no wonder gold production is booming? 

Last week I had the privilege of visiting an operating gold mine near Elko, Nevada.  I say privilege, because the hoops through which I had to jump in order to be allowed to enter were nothing short of tortuous...though for good reason, which I found out after spending time there.  The other reason I would say privilege is that I actually got paid to be there, which is always a cool thing. 

I won't bore you with the details of what I did, but let it suffice that it involved checking out almost every building and structure in the mill area...lots of walking and climbing many, many stairs. 

Yes, that's me in front of a 350-ton truck...and that's not even the biggest one!  Those can carry 440 tons.  These babies haul the ore out of the pit and to the processing mill...which is where I spent most of my time. 


A view from the autoclave mill (the object of this week's trip) towards the roaster mill (in the middle distance) and the head of the underground shaft (towards the right, in the distance).  The roaster and the autoclave are two methods of processing the ore and separating the gold from the surrounding rock.  The mountain on the right, with the dark area at the top is a pile of the stuff removed to get to the gold-bearing ore and forms a dam behind which the tailings are deposited.  Tailings are the materials left over after the gold has been removed...and yes it contains some nasty stuff.  A rubber lining is used to prevent it from entering the ground.

It starts here, at the crusher where the ore is mechanically crushed into smaller pieces that are then carried by a conveyor belt to the mill.

Samples of the ore that fell off the conveyor belt.  Was I tempted to take a souvenir?  Sure, but security was understandably strict and one wouldn't even want to appear as if trying to put one in one's pocket...so a photo will suffice. 
 View from the Crusher towards the Autoclave building (on the left in the background)...

 ...and the mill building.  Everything from the Crusher goes to the mill building where the ore is rolled in large mills, and the powder is mixed with water and other chemicals to form a slurry.
Imagine a giant drum filled with rocks and in some cases steel balls, and then rotate.  Does your imagination give you an idea of the noise? 
 Imagine a room...no, a building full of rotating drums with rocks.  Yes, hearing protection was required.

After the slurry is formed, it goes to the Autoclave Building,  An autoclave is simply a pressure cooker where the slurry is mixed with steam and oxygen (and sulphuric acid, hydrogen peroxide and later with sodium cyanide), and exposed to heat and pressure.  With all those nasty chemicals, it is no surprise that one is required to take more than 16 hours of safety classes before one is allowed onto a mine site.

Image of one of the six autoclaves in this building  


One cannot imagine the sheer size of these buildings, even from these photos.  We climbed stairs equivalent of 5 stories, 6 times...once for each autoclave.

As impressive as these machines are, perhaps what is more impressive are the steps the mining companies take in environmental protection and restoration of the land.  I have to confess to a crisis of conscience when the offer to bid came into our office.  Having recently read articles about mining and recent accidents where many miners were killed, I wasn't so sure I wanted to be involved in this industry.  However, a little research showed me how modern mining techniques significantly reduce the adverse impacts and a shift in the attitudes of the mining companies showed a strong commitment to the protection of workers.  This was made very apparent in the mine safety classes I was required to take, which were followed by additional classes on-site to become familiar with the site's specific hazards.  Having met and worked with a number of people directly involved in the extraction of the minerals out of the ground, as well as those most involved with the protection of archeological and cultural resources, I felt much better about the process...though I have a very healthy respect for the nasty things some of those chemicals can do!

By the way, did you know that Nevada is the largest gold producing state?  Did you also know that Nevada has the largest open-pit gold mine in North America?  Yes...both are true.

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