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flintgreasewood

Virgin Ground to Mine

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I'm looking for someone to mine roughly 2 miles of virgin permafrost placer stream valley close in to Fairbanks.  The overburden ranges from about 45' to 80' so it would require an operation not afraid of going deep.  Pay gravels are 8' to 10' and contain gold for nearly the entire horizon.  Though the ground has not been drilled, there are several prospect shafts that indicate values of a minimum of 1 oz per 30 yds..  The history of the creek below my claims is rich and much research has been done re. geology and production.   Ground is a mile from major highway and town  is less than 1/2 hour distant.   A prospective operation will need to drill the ground and have large dozers w/rippers, rock trucks or dragline and excavators.  There is a large spring that can  supply sufficient water for processing.  If interested contact Kurt

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Hey Kurt,

Yes, as Chris puts it, interesting proposal. Unusually, not even a single query has come forward about the how and why of this Project so let's start the ball rolling by throwing out a few ideas. Firstly, I know you like a challenge and so do I. This Project represents a number of expensive challenges so one would need to have a sizeable Bank Account and a willingness to throw it at something you can't see or touch. At least in Las Vegas, I get to see and hold the Cards or Dice and physically place my Chips on the Numbers whilst throwing down free Drinks all night as fast as I can.

But getting back to the Project you mentioned. First thing that scares most people off would be the significant amount of Overburden. I recall years ago that the Geologist I work with said that I would have a field day around Fairbanks because I have a lot of Underground experience and there are a lot of deep Placers that remain untouched for obvious reasons. So the challenge would be whether or not this ground can be worked economically.

In my book, stripping that much Overburden is out of the question. I only Drill to 20ft. in the permafrost. If I'm not in Pay at 20ft. it's out and move. My Geo. reckons 12ft. is his cut-off. Everybody will have a different idea about what can and cannot be economically Mined at any depth and of course there are a lot of variables, particularly Grade.

So here's a suggestion. Rather than stripping the entire Stream Valley, what about opening up one end down to Bedrock by way of a Ramp. Open an area large enough to load either a Rock Truck/s or a Conveyor System to move Pay. The sides would of course have to be cut back to prevent Slides, Rock falls etc etc. but it's a faster way of exposing Pay. The next question is then how do you Mine the exposed Pay ?

More tomorrow.

Steve.                  

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I would not use a ramp because of the large percentage of the overburden that is just muck. Allow muck to melt and it flows like toothpaste. A ramp built through toothpaste is a problem.

It would almost certainly require shaft access. You could install an upper shaft and a lower one then mine the gold bearing gravel like a coal mine - room and pillar method. Its been used to mine ancient placers in California. I could be done, I am just not sure that 0.033 ounces per yard would pay for underground mining. Doubtful it would pay for stripping and where would you put the striped muck anyway.

An interesting proposal but I think a difficult one. If anyone else has other ideas, please feel to speak up.

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You are right, Chris, about the thawing muck.  It certainly presents problems but there are mining operations in the Fairbanks area that routinely tackle frozen overburden as deep or deeper than my ground.  Frozen muck rips easily, so you do all your overburden removal beginning in the fall after freeze up. Take a break in December and January and get back with it till June when it really warms up. There's plenty of room in the valley to stack overburden.  So by June you have a patch of pay gravel 150 to 200' wide by, say 200 feet deep by 10' thick,  That's about 15,000 cu yds.  Based on historical reports of gold produced downstream on Vault Creek I'm convinced the pay could easily run over $100. per yd.  That would come out to around  , $1,500,000.  Of course drilling first is essential, and what I find in my drift tunneling will enable us to put some numbers where up to now there is only speculation. 

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Hello Harry,

Sorry about the slow response. I've been on a 40T Rock Truck these past few days and it's been bouncing the hell out of me to the point where I can't even think straight. I hope there's Gold in that dirt.

But moving on to your questions -

1. Exposing new Pay is by way of removing the existing Pay exposed by the initial excavation.

2. As for the Overburden, it stays where it is for the most part.

In a nutshell, I am talking about going under it. Exactly how that might be achieved is open to suggestions. Chris is getting closer to the mark in that there are similarities to Coal because we would be trying to remove a Flat-lying Orebody.    

Before we put some ideas out there on how to Mine the Pay, it looks like I need to clarify that I would think this type of Project would have to be Winter Mining for Pay extraction which would then be Stockpiled and washed once you had thawed water. I could not imagine MSHA allowing us to Mine under it whilst it is thawing.  

As for thawing muck, yes it does turn to slop as Chris pointed out above and a way would have to be found to manage that around the Ramp to keep access open. During Winter when most of the Mining activity would have to take place I would not expect that keeping the muck at bay should be that much of a problem.  

Shafts are good for access and exploration but I think they can present just as many problems as cleaning up the thawed muck which has run down the Ramp during Summer. The biggest problem with the Shaft is removing large volumes of Pay to the surface for washing.

The other question which needs to be answered is where do we start ? Do we start at the deep end or do we start at the shallow end ? I am thinking we start at the deep end where the deepest gravels lie which I am assuming would probably be downstream. Reason being is that we use the natural fall or gravity by working our way higher from Downstream to Upstream. 

More soon. More dirt to move tomorrow. Must rest.

 

 

 

 

 

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I believe at the operation adjacent to Nome, they are removing 50 feet of overburden and 10 feet or so of pay.

Mine in the winter, process in summer.

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I will have a look around when I get there in June. That's a lot of Overburden so the Grade must be good. I think economy of scale would also make a difference if that Operation is Nome Gold for example who have literally thousands of Acres to play with.

Getting back to the Plan. Kurt has a very good point. Drill before you dig. I can't argue with that. Let's assume though for a minute that we as a group are seriously considering forming a Syndicate or other to actually Mine this ground. Don't laugh. There is probably a significant amount of experience right here on this Forum that could eventually come up with the right answers, economically. 

So Drill or Dig ? I would say Drill 9 times out of ten but it is deep ground which is expensive Drilling. I say get Quotes on both options. Drilling is generally per foot plus Mobe / De-Mobe. Maybe Kurt can make some enquiries and get back to us. My Geo. lives in Fairbanks. I will see him in Nome in June. He will know the current Drilling rates. As for the Ramp, I would say Hire an Excavator for a Month and of course a Rock Truck or two just so we can get the initial excavation done and get a look at the Pay. We'll talk a deal with Volvo and maybe even get on TV. But seriously, getting back to the Ramp for access. Let me ask this. Wouldn't that ground have to be stripped anyway to get at that Pay ? Wouldn't that access also give us ground to Bulk Sample ? Wouldn't we then have costs on how much it is to move a Yrd/3 ? Compromising on the Drilling, if we had Pay exposed at ground level, why not Drill it Horizontally / Slightly Inclined from the bottom of the Ramp ? Yes, of course that also presents new problems like potential caving in the Hole etc etc. so we would probably have to case it but there are sizes ( PQ Triple Tube ) which could give us almost the same representative Sample as a 4" Surface hole. As one of my old Bosses used to say at Work, he is not interested in problems. Whilst he will recognize and understand there are difficulties, he is only ever interested in hearing our solutions to the various issues, which of course in Mining are guaranteed to arise on a daily basis.

This Job sort of reminds me a bit of an Exploration Shaft we had to sink on a base Metals Project ( Silver / Lead / Zinc / Copper ) where we had to put down a Circular Shaft about 150 ft. to hit the Orebody. From there we put in Drifts in 3 x directions about 100 ft. long. Then we brought down Diamond Drills, set them up and Drilled out from the end of the Drifts in a Fan pattern to look at what was in front of and around us. If Kurt is saying 150 ft. to 200 ft Wide, then Holes on 25 ft. centers should do the trick.

 More soon.            

 

          

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Hi, Steve, Harry, Chris and other interested miners,

My first reaction in response to Steve's last post is: where does the money come from to drill, rip with a dozer,  excavate, haul material, build access road, site grade, etc?  It's going to take someone or some operation that has a very good knowledge of the immediate area and its potential and, therefore, is willing to take the risk to get some firm numbers.  Next, frozen muck drills fast, but 80' holes are still not cheap.  I'll try to get some costs.  Working with a dragline is probably the most cost effective way to remove overburden and currently there is a good possibility of a 2 1/2 yarder available.  If operations were to begin at the furthest downstream point that would be just past where the two feeder creeks joined, thereby combining two pay steaks.  That would surely be the richest ground. Drilling might best begin at the division of the creeks.  I'd like to think that by summer's end I'll have good knowledge of the pay on the upper end of Vault [more than 1/2 mile above the junction] from drifting out of the shaft I've put down.  So, how serious are you about my ground, Steve?  What could you bring to a venture?  How similar is a "syndicate" to a partnership?

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Hi Kurt,

Apologies for the delay. I have to Work long hours at the moment which pays for my long hours of messing around in Nome during the Summer. Firstly, O.K. yes money is always an issue but not one that I would think should stop us from crunching some real numbers to see whether or not the entire thing is even feasible. It shouldn't cost us much at all to have an actual Plan of attack which is why I am trying to encourage thoughts and suggestions from other Forum Members who may have more experience on various aspects of a similar style of Project. And if somebody asked me where does the money come from to Drill, well I couldn't even answer that because first and foremost I don't even know how much I need to Drill. I haven't set out a Drilling Program, I haven't settled on a Hole Size, I don't know how many feet I am planning to Drill etc etc. i.e. How long is a piece of String ? The same goes for Hauling Material. How much Material and how far ? We fill in some blanks then all of a sudden some firmer numbers start appearing.  

There is a lot of work to be done before we could even estimate what it would cost to get a Bulk Sample done. As soon as I get time I'll work on some Volume estimates to see what sort of volumes we are talking to open up the Pay by way of Ramp. At least if we can open up some Pay then there is the chance of recovering some costs via the Bulk Sampling.    

We'll talk about the other questions later when we know more. Maybe more specific info. may entice more interest from other Miners or prospective Miners. At the moment, it would appear to be just the two of us.

.                

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I'm still a green bean when it comes to mining and have been in a underground hardrock mine a couple months. The other day I was bored mucking and somehow this popped into my mind. I wonder if you could mine it underground cheaper per yard of pay than you could removing 50' of over burden.

 

A lot of our older workings have steel arches every 3-4' and then the voids are filled with concrete to create a solid tunnel. What about doing a hualage ramp/ tunnel with steel arches filled with concrete and then a concrete ramp floor going down? Basically you would be making a big steel and concrete culvert going down and then continue the haulage tunnel down the valley. Possibly timber and use your existing shaft as a secondary escapeway and intake or exhaust vent shaf tied into the main haulage tunnel.  Mine pay gravel in the winter when it's frozen either drifting or using room and pillar with temporary ground support if necessary. At the end of the underground season pull the temporary ground support and close off access to the exhausted workings. I'm guessing during the summer you would have to dewater the tunnel but that water could be used for processing.


If you have 10-12' of pay you might be able to get away with conventional surface equipment though underground equipment is stupid tough. I run a cat r1600 LHD and there's no way it's surface equivalent would hold up to the abuse of bouncing off the rib and moving around rocks all day. Though you could buy a used loader every year for what a used 1600 costs. Your pay might be easier on equipment than hardrock is on equipment. Would a breaker on a small excavator work on the pay to break it up? I think you could run a pretty efficient operation with an excavator breaking up pay, a loader loading it or possibly even hauling it to the surface, and then if it's worth it a couple rock trucks. So between 2-5 guys a shift and not dealing with much if any overburden.

This method could be "modular" and you could have several crews working on several faces at the same time all using the same tunnel with some traffic controls in place.

 

Any idea on how to start crunching the numbers? Your initial startup costs would be high putting in your ramp and haulage tunnel. It would involve pumping in 1000's of yard of concrete and lots of steel. You would also have your power, ventilation, and dewatering to deal with. At the same time buying a couple d9's or 10's, a large excavator, a couple haul trucks and moving 50'+ of overburden isn't cheap either. Once you were on the pay you would have higher wages being an underground operation but lower fuel costs.and equipment maintenance not having to have huge equipment.

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Part of the problem here is the need for capital - and thats a problem for miners everywhere. You can't get into serious scale mining for cheap. Many small miners are undercapitalized.

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