A Modern Take On Old Time Drift Mining

[Flintgreasewood]

Micropedes. Thawing of the permafrost takes place to a limited extent only at the surface. However, my biggest problem is, as Jim points out, melt water, not from thawing muck, but from seep from snow melt and rain. I lost my first shaft ( a reopened old peospect) to meltwater and sluffing muck and now in the new one I am continually dealing with icing on the shaft walls, dripping and muck falling from just below the cribbing at the thaw zone. What water that does make it to the shaft floor is pumped out. Periodically I have used my elevator to chip the encroaching ice away with a small hammer drill. And I have tried mitigation of the seep with a trench away from the shaft. Nothing, yet, has worked. Last sommer the ice buildup got so bad I could scarcely raise and lower the bucket. After much deliberation I have brought in a large Frost Fighter heater with which I will send down a tremendous volume of hot air to thaw most of the ice. (I’ll leave several inches in place for stability). More on how that turns out.
Jim, are you familiar with shaft capping? If the shaft had surface water issues spring capping was a procedure often employed. Just below the frost line poles were laid across the shaft. Successive layers moss, snow, water sprinkled on the snow, more snow and water, were layered till everything was frozen solid and finally insulated by much moss. The cap or plug effectively sealed off summer melt water and the miners could return in the fall to a dry or relatively dry shaft.

[Jim_Alaska]

Kurt, I am not at all familiar with shaft capping. Any of the old shafts I came upon were always filled with frozen water, otherwise known as ice. But it makes sense in that the lower levels of the shaft would remain frozen. As you pointed out, the real problem comes from melt water. This is extremely difficult in places that are in low areas of muskeg, which is always wet anyway.

[Flintgreasewood]

Ok, I'm at the bottom of a 64' deep shaft and I need to change directions and begin drifting. The old timers first used fires and then steam to run their drifts, but steam presents a host of problems, not the least of which is that you can't safely operate alone. At first I tried using my jack hammer and though it worked, progress was painfully slow and tiring. A friend and fellow underground miner was experimenting with an industrial version of an electric blanket to thaw his gravel and was achieving some success. It sounded good but the cost for one was out of reach for me, so I set to work designing and fabricating my version of a thawing blanket. With a bit of research I stumbled upon carbon fiber heat cable and ordered some from a company in China. I salvaged some large sheets of tyvec type sheeting that are used to cover bunks of plywood from the factory. High temperature silicone held the carbon fiber cable in place and a "space blanket" with its reflective surface was placed on one side to help keep the heat directed toward the gravel face.
As I was completing the blanket I began thinking of possibly more efficient uses of the carbon fiber wire. To make a long story short I developed heating rods that would be placed in parallel in pre drilled holes in the face. Even my first attempts worked though much refining lay ahead. At least five iterations later I had a system that quite effectively and inexpensively could thaw a block of frozen gravel four feet by five feet, three feet deep in ten hours of run time. I used a beefy Bosch hammer drill with a 42" by 3/4" carbide tipped bit to drill the holes. Leaning on the drill to drive the bit was not difficult except for the upper holes where nearly all the force came from arm strength. Fifteen or twenty minutes of holding up and pushing at the same time a 20 lb drill and bit overhead was wearing me out. There had to be a better way.

[Slatco]

More please lol

[Geowizard]

Flint,

Underground mining is a mature art. I operated the Hilltop Mine in Arizona. It is an underground mine with over five miles of tunnels, drifts, raises and shafts on four levels. It's slightly different because it is in limestone - not permafrost. I had a copy of the detailed mine maps with all of the fault zones, mineralization and production at every raise and stope.

You have at your disposal, hundreds of years of development of underground mining technology!

I looked up the mining Engineer (he lived in Tucson) that worked at the Hilltop Mine back in the 1950's during the last years of production. He did a Masters Degree Thesis on the Economic Geology of the mine. The operation (then) used a Mule (named Smokey) to pull six ore cars out of the mine. Spanish speaking miners climbed up a raise with a box-work of timbers over 100 feet vertically to drill 2 inch blast holes in the rock and shoot with Dynamite (ask me how) . Getting a personal tour from him is an experience I will never forget. He would walk along... Slap his hand on the side of the drift... This is "Naco"... This is "Martin"... This is "Abrigo"... This is "Hilltop Quartzite"... The rocks all had names.

The mine was fully developed back in the 1920's, running 3000 feet through the Chiricahua Mountains and developing the mine to over five miles on four levels.

Here's how...

The mine originally had an outdoor steam plant. Equipment, including rock drills ran on steam power. As the mine was developed, the boiler remained outside with a steam pressure tank centered in the mine. Steel pipe was used to deliver steam to all of the working areas.

- Geowizard

[Flintgreasewood]

I needed not only a way to hold up the drill but also apply horizontal pressure. After a few design changes I came upon a good working system and that is currently what I use in the drift. It consists of a frame to which the drill is clamped and it travels on two parallel pipes. At one end of the pipe track is a hand operated winch with a divided drum wound with two lengths of nylon cord, one wrapped clockwise and the other counterclockwise. One cord stretches the length of the track and through a pulley and back to where it attaches to the front of the drill frame. The second cord attaches to the rear of the frame. When the winch is cranked the drill bit is pulled into the drift face as the second cord unwinds. When the drill hole is finished the winch is reversed and the drill is pulled back out. Two other important features are the rear backup and support post and the front set up support poles. At the rear is a 4x4 post with an electric jack fixed to the base and with a heavy pointed pin in the top. The post is positioned and tightened between the floor and roof and the drill “carrier” is positioned by a pin in the end onto any one of many holes drilled in the post. Until pressure is applied the carrier is supported by two spring poles between the walls. Once drilling is commenced the support poles are removed to allow free travel of the drill carrier. Depending on the hardness of the rock I’m drilling through it takes between 10 and 20 minutes to set up and drill a 3’ x 7/8” hole. I’ll try to get a YouTube video of the unit on operation.

[Geowizard]

Flint,

Are you on bedrock?

- Geowizard

[Flintgreasewood]

Certainly am

[chickenminer]

Kurt,
Glad to see you back at it.
I am intrigued by your "heating rods". Can you please go into more detail.
That is an impressive block of ground to thaw in 10 hrs. How close do you have to place holes
to thaw that block in that time frame?
I'm with you, I quit using steam while working alone after I got the bejesus scared out of me !

I have no intention of ever drifting, my winter prospecting has always been just shaft sinking
and pretty much resigned to just using wood fires. But wood fire thawing is a struggle after you get
so deep, so I'd really like to see your setup with these heating rods.

[Flintgreasewood]

Hi, Dick
The rods I use consist of nichrome wire sheathed in fiberglass sheathing and looped inside a 3' length of 1/2" electrical conduit threaded on the inside and plugged with a 3/8" galvanized plug. The wire is connected to a short length of heavy electrical cord with an electrical plug on the opposite end. The tube is filled with fine sand and the end filled with glass wool insulation. A compression fitting combined with a strain relief fitting caps the tube.
It is 120v powered and I use 15 rods spaced about 14" apart. The temp gets up to around 600 degrees. if it is something you really want to pursue I can put together a list of parts and where to get them. I can also explain how to thread the nichrome into the sheathing. I think each rod costs about $16.00. The cable that connects the rods is set up with pigtails in parallel. I am sure I'll continue to refine the rods, but the current iteration does work
Sam Skidmore builds 5' rods out of stainless tube with higher wattage nichrome which takes a much bigger generator. He gets a 3' diameter thaw.