Is drift mining a practical way to mine nowadays?

[PishonRiverGold]

I’ve always had an interest in drift mining and I am looking for any experiences with it. I have read a little on this forum about it, I’ve read historical articles on it, and recently I have watched a couple hardworking guys on YouTube sinking a shaft. This post is more a series of questions on it.
Are there some areas left in Alaska or the lower 48 with deep pay streaks that it would be worth sinking a shaft on?
Do you drill first or just start digging?
I have done lots of research on this mining technique in permafrost and also lower 48 type alluvial soils ,there isn’t tons of info out there. I wish the old timers would have documented their techniques more. I’m sure that was the last thing on their mind though while they were just trying to survive.
I haven’t really found anything on practical depths that could be mined, anybody have knowledge on that? I suppose it depends on your motivation and technique. I did read that the deeper your drift mine in permafrost the more swelling in the floor of your drifts you get from relieving the pressure of the overburden.
Also after going to all the work sinking a shaft is it only good for one season? It seems like the old timers abandoned their shafts and dug new ones the next winter.
I have read a few documents on using blasting in permafrost drift mining. One was an experimental permafrost drift or tunnel and the other was on the soviets drift mining in Siberia with powder. Does anybody have any other information on using powder to drift mine nowadays? There are some hoops to jump through legally but it seems like blasting would make this type of mining much more enjoyable. The techniques I read about are basically hard rock blasting techniques with some adjustments. The powder factor was reasonable especially using frozen plugs for stemming in your blast holes. I can provide links to different drift mining documents I’ve found online if anybody wants them.

[Geowizard]

Is it practical?

It's safe to say, every mineral deposit has a completely different set of variables that control the "practicality" of mining.

The variables require a book to cover all of the different possibilities and many books have been written on the subject. Volumes of books have been written on the subject of underground mine design, engineering, and all of the related means and methods of digging, ventilating, drilling, blasting, shoring, shoveling, mucking and hauling.

I bought a library of AIME hard-bound "symposia" representing over one hundred years of the body of knowledge on every aspect of mining with detailed examples of mines from all over the world. There are subjects and subject matter that is no longer found in the curriculum in colleges and universities today. So, for the above average GOLD prospector, I suffices to say, the questions and almost infinite number of answers exceed the scope of this or any forum but it's a good place to start.

It's a good question!

- Geowizard

[Geowizard]

One example;

I used to own and operate the largest privately owned underground mine in Arizona with over five miles of tunnels, drifts, and raises on four levels. No, it wasn't a GOLD mine. It was a lead, zinc, silver mine with several pages of accessory metals and minerals.

Was it practical?

It had a good Forest road for access, over a hundred years of development with another hundred years of potential production all at eye-ball level. I began the process of spending "money" - my "after tax income" on years of exploration, planning, mapping, assays, market research, potential mill-sites, smelters, international brokers, shipping and running computer based economic simulations on many different mining scenarios.

While, all of the time watching metals prices going up and down.

Initially operating below the permitting level and within the "letter of intent" level, I hired workers and began clearing fallen debris on fault lines inside the mine. I received a certified letter from the Forest Service District Ranger "Ordering" me and my men out of the Coronado National Forest.

- Geowizard

[Geowizard]

By the way,

Welcome to the Forum! Feel free to ask questions and enter into discussion!

- Geowizard

[chickenminer]

Pishon ... good to see you posting!
I have sunk many shafts over the years during winters prospecting but my intention was never to drift mine any of them, only for prospecting.
Is there still areas left ? Well I'd say there is lots of areas left to prospect but worth mining you won't know until you get to the bottom!
I'd say it was every prospectors dream to have a fancy sonic drill rig and unlimited budget so we could drill first.
Not always an option though.

No, a shaft doesn't have to be abandoned after one season but a lot depends on the ground. Here in Alaska if you are in a permafrost area you usually only have to worry about water seepage from the top and only crib the first 4-5' to keep the top from sloughing in.

I've never done any blasting in a shaft, only used wood fires and/or steam for thawing.

There is a good older book on Alaska prospecting techniques by Ernie Wolff called "Handbook for the Alaskan Prospector".
Not sure it is available any longer but worth trying to find a copy.

[Joe S (AK)]

PRG, Hope springs eternal when it comes to drift mining.

It is also true that there has been quite a bit of Gold recovered from 'em in the past - but - in the end I'm reminded of the two instances of them that I have personally been acquainted with, one in Northern California (dry country) and one in Alaska's +- permafrost.

The California one was quite an experience for me. Jim Foley (the creator of this forum and no longer with us) asked me on one of my trips to Alaska, and while visiting him at his home in Northern California, to accompany him to an old hydrauliced area to study it, scratch our heads and do a little brainstorming on just how it had been worked way back in the day.

So we drove to this site from his home (next to the Klamath River) and studied this old hydrauliced area, spending a full day puzzling out it's secrets.

We were leaving at the very end of the day when I noticed something unusual on a side hill right next to that site. We clambered up the side of this small hill (which joined up with a big hill) and began to look at a very small hole in the side of that 20 foot high, small, side hill. The hole was about the size of a rabbit or wood chuck hole but it was, curiously, in a vertical opening in the side of the hill, with a seemingly large interior void just inside the entrance -- and -- with a very curious small, perpendicular-to-the-hillside, bench. That "bench" was what initially caught my attention since the top was very flat and about two wheel barrows wide, 20 + feet long and with very steep sides. That "bench" joined the small hill where the 8 or 10" wide "Rabbit Hole" was located 2 feet above the bench.

It was quite some physical effort for we two old guys to climb up there on hands and knees but we did the climb in record time. Curiosity fueled our efforts and we were young again.

So we looked at the hole and then, slowly, started enlarging it with just our hands, alternately sticking our heads in. Finally we determined that the original, excavated entrance had been closed over long ago and that settling, through weathering, had allowed the dirt to slip down both inside and outside - creating the small "Rabbit Hole" appearing entrance at the top of the old portal. What a curious thing we both thought.

Since we were unprepared for the new circumstances in our explorations (and it was almost dark) we chose to go back to Jim's house to better outfit ourselves for a good running start the next morning.

The next day we returned with a shovel, a 1/4" classifier, a couple of 5 gallon buckets, flashlights and other "stuff" and carefully, slowly, opened up the entrance only enough to properly look inside. WOW! what an even more curious thing it was.

The hole was at the very top of a prior entrance way (a Portal (?)) where miners had dug into the side of the hill on, probably then, hydraulically exposed, bedrock pay streak heading straight into the hill, following the top of the bedrock.

Just inside the Rabbit Hole was the original 12 foot high portal which was dug into and down to provide a 20' wide protected entrance area about 12+ feet high. Straight in from the back of the portal was the "main shaft" or tunnel which went so far in as to outdistance the strongest flash light we had.

Every 15 or 20 feet there were "sort of side excavations" also down to bedrock but only 10 feet or so into both sides of the main tunnel and across from each other. We thought they were probably made to check side wanderings of the pay. NO SHORING of any sort had been used, although the side walls were very, very solid and dry even after all this time. (I know all that because I was the designated "Rabbit".) I shouted and then smacked the walls and curved ceiling with that True Temper #2 shovel using a lot of determination and effort but with not a pebble being dislodged. I crept in about 15 or 20 feet and every foot or so I attacked the walls to check them for soundness. Solid as could be.

So, what to do now? Well, we conferred back at the entrance (Jim was the designated Safety Superintendent there at the entrance) while I was the careful Rabbit inside) and we chose proper prudence in excavating down into the floor near the entrance until I was stopped by a little ground water. I handed 1/2 buckets of floor material up to Jim using a rope and he classified them into other buckets for processing back at his home. The digging was really awkward because the floor was narrow and (Oh Yeah!) the digging was mighty tough. So with both knees splayed sideways, ending up bent over at the waist so that I was almost exactly standing on my head throughout the digging operation I awkwardly dug as deep as I could.

So, what did we find? Nothing, nada, zilch. Those other guys got it all and at the end they brought overburden from the face and filled in the floor and portal as they left.
*****
And the other one? It was North of Fairbanks a hand full of miles from Manley Hot Springs. A traditional, vertical, cribbed shaft with a side ladder going straight down (like a hand dug well). After a quick look from the surface that one was not of interest because it was scary, scary, scary.

In talking with "the locals" I found out that the miner who dug that vertical shaft and drifted below it would every few months, over the years, go into town for supplies and possibly a little internal lubricant. Suddenly he stopped those periodic resupply trips and no one ever heard from him again. Upon curious concern the locals found that he had left all his 'stuff' in his camp as though he would be right back in a few hours. The logical conclusion was that death had come in an instant due a cave in and that trying to recover the body would be just an exercise in aimless underground futility. Dangerous work, very deadly dangerous work.

My suggestion is to research about drift mining as much as you want, for as long as you want, thoroughly scratching that itch --- and then go find somewhere else to work in a stream because life is more certain in the sunshine.

Joe

[PishonRiverGold]

Thanks for the reply’s. I’m in the lower 48 now but have been thinking about getting back up to Alaska. I never really got into prospecting up there because I was more interested in trapping and hunting. Now that I’ve been in the lower 48 for a few years I think of the opportunities I might have had looking for gold. We were in “bush” Alaska and have a cub so I saw a few remote mining operations.
I do have a few prospects here. Some may need some deep digging done on them so I’ve been looking up everything I can on this type of mining. It appealed to me because it something that can be done in the winter. I hate waiting for the the next prospecting season. I checked out Arizona this year to see if that was an option for winter gold hunting. The weather was great but there were thousands of people and pounded goldfields. The northern part of the states gets winter so some of the goldfields haven’t been worked as extensively as the southwest. Also the desert is wide open to help in finding deposits. In a lot of the northern goldfields the ground cover is heavy enough that it is still hiding things.

Geo that is a real bummer on your mine in Arizona. That sounded like a good experience to have no matter the cost.
From reading some of your other posts you sound like you have done lots of research on geology and mining. I like doing research on anything mining and geology related.

ChickenMiner thanks for the feedback. I will google that book. I have a good collection of mining and geology books. Looks like I need one more.

Joe thanks for the sharing your experiences. That sounds like fun finding those old diggings. I would have thought there would have been a few crumbs in there to get. The old timers didn’t leave gold without good reason I suppose. It seems like the best you can hope for nowadays is finding a deeply buried deposit they missed. That’s why I was interested in drift mining. Man the drift mine story in Alaska has me wondering about all this. I haven’t read much about the old timers dying from cave ins but I’m sure it happened more than maybe anybody knew. I have heard about bad air accidents and that but not much on cave ins. Some of those guys working by themselves could have disappeared and nobody would have know. Seems like a bad way to go.

[Geowizard]

Drift mining;

Obviously mineralization is found underground! It requires that someone dig a hole. The first requirement is having discovered mineralization of sufficient value to warrant the expenditure of time and money. Not a good idea to go through the effort those guys in Alaska are going through to sink a shaft in the winter with NO GOLD. Let alone prove it to your viewers.

Drift mining is a process that involves the right combination of planning and execution of a plan. The plan has by necessity to include the appropriate tools. The drift begins with an Adit or Portal that has the required shoring and support members - steel or wooden to prevent caving. It doesn't take much understanding to realize the importance of "engineering" to support the drift. Advancing a drift underground is a mature science at this point in history!

It involves a process that includes an understanding of all of the possible hazards both seen and unseen to avoid becoming a statistic. To that end, it behooves anyone contemplating working underground to enlist the services of a professional underground miner. That profession is passing by the wayside as modern culture moves to things that are more pleasant and fuzzy that require little work and no risk. Miners represent a special breed. Miners represent a limited group that can apply above average thought and muscle toward a single purpose.

Long winters offer an excellent time for "planning the plan" for the coming season. It actually takes eight or nine months to plan the plan, sort out the tools needed, find the tools, ship the tools and get the stage set for mining.

A new mine in a remote part of Alaska has to be foremost "ON THE GOLD". The reason is because the COST involved is up front and that cost eventually has to result in sufficient return. Nobody is ever successful in any kind of mining when it's a haphazard - well, I think I will poke a hole here or maybe over there approach!

Prospecting in the world today is foremost to mining. That is the process that leads to discovery. Discoveries are getting harder to make because we are preceded by hundreds of thousands of prospectors that have combed the earth looking for the same things we are looking for! Looking for GOLD in all of the easy places on flat ground - out in the desert, near a shade tree. That isn't realistic. GOLD is found in areas that have "structure". That involves mountains. It involves hydrothermal intrusives - hydrothermal, geothermal, volcanogenic massive sulfides and twenty more possible deposit models. Alaska is rich in GOLD because it is rich in "Structure".

Stick around! there's more!

- Geowizard

[Geowizard]

What is a drift mine?

From Wikipedia:

"Drift is a more general mining term, meaning a near-horizontal passageway in a mine, following the bed (of coal, for instance) or vein of ore. A drift may or may not intersect the ground surface. A drift follows the vein, as distinguished from a crosscut that intersects it, or a level or gallery, which may do either."

https://en.wikipedia.org/wiki/Drift_min ... o%20either.

Wiki derives their definition from many sources as cited in their references to glossaries of mining terms and dictionaries of mining.

A good reference is:

What Is a Mining Drift? A Beginners Guide:

https://anundergroundminer.com/blog/wha ... ning-drift

Some people confuse drift mining with shaft mining. Shaft mining refers to a vertical or nearly vertical.

What is the difference between shaft mining and drift mining?

"There are three types of underground mines: shaft mines use a vertical shaft to reach the coal seam; slope mines employ shafts dug at an angle when it is too dangerous to dig straight down; drift mines rely upon horizontal tunnels, or drifts, to reach coal found in the side of a mountain or large hill."

http://history.alberta.ca/energyheritag ... rge%20hill.

Other references:

https://www.greatmining.com/drift-mining.htm

All of that took about three minutes!

Prospecting leads to mining;

So it is for a prospector, when he or she discovers a deposit of GOLD or Silver or other precious metal or valuable commodity emanating from the earth, a decision is made to mine it.

If the deposit lies in a horizontal or nearly horizontal plane, there is no choice on which direction to mine.

The same decisions are made today as they were 5000 years ago in Greece.

https://en.wikipedia.org/wiki/Mining_industry_of_Cyprus

Hydrothermal deposits are generally vertical. The mineralization is mined through open pit mining or by a shaft.

Coal is most often found in horizontal deposits called seams. GOLD on the other hand is found in hydrothermal and related vertical deposits. Placer deposits are not the issue here. Placer deposits are not vertical deposits but are often mined using vertical methods often referred to as "drift mining".

Witwatersrand in South Africa is a unique case that represents potentially a placer deposit that has been mined vertically for over 3000 feet.

How deep is the gold mine in Witwatersrand?

"Today some of the mines in the Witwatersrand are the deepest in the world with operations at 4 km below surface. Ambient temperatures underground are well in excess of 50 °C."

"The hydrothermal model states that the sediments that washed into the basin contained very little or no gold. Instead, gold-rich hot fluids emanating from deep within the Earth's crust, and traveling along faults and fractures, added gold to the basin long after the sediments consolidated into rock."

Two theories abound;

"The origin of Witwatersrand gold can be explained by metamorphic devolatilisation to generate auriferous fluids beneath and outside the Witwatersrand Basin, followed by passage of these fluids along large structures and into the Basin."

Gold is frequently found in sediments. Sediments form sedimentary deposits. Sedimentary rock deposits can be subjected to heat and pressure - forming metamorphic rock.

Ore Deposits 101:

https://www.youtube.com/watch?v=LRKk1HYTlH8&t=1s

In summary, the means or method used to access a mineral deposit depends on the direction of the mineralization and the origin of the entry into or towards the deposit.

The question of practicality is a matter of what the variables are related to economic and physical constraints.

Don't go away. There's more!

- Geowizard

[Geowizard]

Is drift mining practical nowadays?

Drift mining is timeless. It isn't like "Bell bottom pants". Although there are practical applications for Bell bottomed pants!

It isn't a fashion that comes and goes - it's a method.

The question of "nowadays?" makes the question awkward in terms of whether drift mining is a thing of the past and modern miners have a new method of mining "nowadays".

Because new GOLD deposits are discovered all over the world everyday, from an historical view, mining of every deposit is based on a combination of best practices, the laws of physics and economic variables - all of which enter into the discussion of pre-feasibility.

I encourage all GOLD prospectors to read every available pre-feasibility study they can get their hands on. The studies form a "practical" and "rational" third party view of whether a mining project could or should move forward. Although a formal pre-feasibility study (PFS) is in most cases out of the reach of a small miner, the principles involved apply to everyone. A PFS takes the question of a prospect to a higher level. Every prospector that ever lived has had to do the "soul searching" involved with whether or not to pull the trigger and dive into the mining phase.

Miners whether individuals or with families or other dependents have a responsibility to themselves and others to "do the right thing". All too often, decisions are made without an adult discussion of the relevant topics.

What are the relevant topics?

Stick around and find out!

- Geowizard