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At the time it was established, Kennecott served the richest known concentration of copper in the entire world… Many think that Kennecott was the name of a mine, but, to be clear, Kennecott is the name of the abandoned mining camp that was the center of activity for five Alaskan mines: the Bonanza, Jumbo, Mother Lode, Erie and Glacier. The Glacier, which is really an ore extension of the Bonanza, was an open-pit mine and was only mined during the summer. The Bonanza, Jumbo, Mother Lode and Erie mines all connected underground.
How rich was the ore coming out of the mines around Kennecott? Some of the ore was so rich that the miners did not even bother to run it through the mill, but simply ran it down a chute by the mill to be shipped directly to Tacoma, Washington. I have seen reports that initial ore shipments from Kennecott contained 72% copper (in other words, the rock was almost pure copper) and 18 ounces of silver per ton of ore.
Shipping ore to Tacoma was expensive and, usually, required copper ore to be concentrated for maximum profitability. The most economical process for rich ore was gravity concentration. Ore was delivered to the 14-story mill from the five remote mine sites via tramways at a rate of up to 1,200 tons per day. Once in the mill, the ore went through a series of crushers and sorters using gravity and water to move the rock from one process to the next. Once waste was removed, the concentrated ore was loaded into burlap bags and stacked on open rail cars to be shipped to the coast. Construction of the mill evolved over 20 years as new milling processes were developed. Over time, deteriorating ore quality at the mines around Kennecott demanded different processing techniques, continual equipment modifications and additions to the mill structure, which resulted in the current unusual roof line and jumbled appearance of the iconic red building (You may be wondering why all of the buildings are red? Apparently, red was the cheapest color of paint back then... This is supported by the fact that almost all of the mine buildings we encounter from this era in California, Alaska, Nevada and elsewhere were painted red).
Back to milling… Gravity concentration is only efficient for high grade ore. To process lower grade ore, new techniques were needed. Thus, the ammonia leaching process was developed (the first ammonia leaching plant in the world). Overall, 25-30% of Kennecott’s ore was processed through ammonia leaching, increasing the profitability of the site. As ore concentrations further continued to decline, a flotation process was installed in 1923.
1916 was the peak year for production at the mines and by the early 1930s, the richest grades of ore were mostly played out. The Glacier Mine closed in 1929. The Mother Lode was next, closing at the end of July 1938. The final three, Erie, Jumbo and Bonanza, closed that September. The last train left Kennecott on November 10, 1938, leaving it a ghost town.
From 1939 until the mid-1950s, Kennecott was deserted except for a family of three that served as the watchmen. Imagine being in that position and having the run of this entire site - as well as the mines - to yourself. There were more buildings then and everything was perfectly intact. That would be a mine explorer’s dream!
Sharp-eyed viewers may think I made a typo in labelling the Kennicott Glacier with an “I” rather than with an “E.” Have more faith in me… Yes, the Kennecott site is named after the Kennicott Glacier in the valley below the famous mining camp. The glacier was named after Robert Kennicott during an 1899 US Army survey. Whether the name was slightly altered by “clerical error” (the official explanation) or simple pettiness, we will never know.
The information and photographs in this video are courtesy of the National Park Service.
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All of these videos are uploaded in HD, so adjust those settings to ramp up the quality! It really makes a difference.
You can see the gear that I use for mine exploring here: bit.ly/2wqcBDD
And a small gear update here: bit.ly/2p6Jip6
You can see the full TVR Exploring playlist of abandoned mines here: goo.gl/TEKq9L
Thanks for watching!
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Growing up in California’s “Gold Rush Country” made it easy to take all of the history around us for granted. However, abandoned mine sites have a lot working against them - nature, vandals, scrappers and various government agencies… The old prospectors and miners that used to roam our lonely mountains and toil away deep underground are disappearing quickly as well.
These losses finally caught our attention and we felt compelled to make an effort to document as many of the ghost towns and abandoned mines that we could before that colorful niche of our history is gone forever.
I hope you’ll join us on these adventures!
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