Processing Black Sands

[SchoolOfHardRocks]

I've heard that prospector's "would be surprised, & never discard black sands again if they knew how much gold is in it"...Well, with my 2nd season coming to a close I think I have stock piled enough to think about processing it.

I have about 2 gallons of black sands and am wondering, what's the most efficient way to process it? I've heard about the crushing method & the heat & freeze method...but what is the best way? Are there other ways??

My plan is to document this process from beginning to end on this thread once I have determined which processing method will work best for me..who knows someone else may benefit from seeing my trial and error with black sands. Plus it will keep me busy while I'm patiently waiting for spring

 

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[goldenIrishman]

I agree with John on that. Having looked at what I thought were clean cons under the microscope I can tell ya that there IS more gold in them. Looking at samples both before and after grinding I have seen that a lot more gold is released by grinding. I'm not sure about other areas but out here in the desert a lot of the small gold is coated with other junk. Grinding gets that junk off the gold so you can see it for what it really is.

I ran that small test batch for an hour or so and while quite a bit of it was reduced to under 100 mesh, there was still quite a bit of it that still wouldn't go through the screen. Looking at a sample under the scope I could see quite a bit of gold. As to why the rest of the sample didn't crush I can't say quite yet. There are several different reasons that I can think of. These range from the weight of the rods, the number of the rods, the heavy rubber barrel etc etc etc. Only trying different methods and setups will give me that answer. I have a feeling that the size of the material going in is going to determine just how long you're going to have to run them. Even though I've still got more experimenting to do to get it dialed in, I think it will prove to be worth in in the long run. I just need to gather the data and then use it to streamline my processing so I can get the most gold out for the least amount of effort in.

 

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[johnedoe]

I am thinking the cons you run should be of fairly consistent size as well.... Ultimately we are looking at cons in the -70 range which are the sizes that start becoming difficult to separate the gold from the heavies.

 

[mu50stang]

The cons have been screened through 30,50,70,100 mesh screens as I was going to blue bowl them. Once I get the rods cut I will run them as separate sizes and see what happens. I did order a USB camers today but not sure when it will be here.

Goldenirishman do you have a picture of your rods in the barrel. Im curious how full it is?

 

[goldenIrishman]

I can get a pic of it tomorrow. I'd estimate it's about 1/4 full. I've got more rod stock that I can cut up for it but I was getting a bit worried about the weight. I've got a twin barrel tumbler so if I run one at a time I might be able to get away with more rods. The tumbler instructions say no more than 3 Lbs per barrel. I used a mix of 1/4 and 1/2 inch diameter rods. Somewhere around here I've got some other sizes of rod I could throw into the mix. I still haven't found everything after moving. Need to build a shop so I can get all my tool and materials organized again. I hate moving!!!

Another thing I'm concerned about it that my classifiers currently stop at 100 mesh. I've been looking for a couple that are finer to I can size the materials after grinding. I may have to go to a fireworks/pyrotechnics supply to get the mesh sizes I want/need.

 

[chlsbrns]

From our newest black sands vortex. A member here sent the sands saying that there was no gold.

 

[goldenIrishman]

Must of been pretty clean since I don't see any picture of the take.

 

[johnedoe]

From our newest black sands vortex. A member here sent the sands saying that there was no gold.

That's pretty amazing........

 

[goldenIrishman]

Had some things come up yesterday so I wasn't able to get any pics of the rod mill setup for you Mu50stang but I haven't forgotten ya. I'm going to cut up the rest of the rods and give it a try with all the rods in a single tumbling barrel and see if the drive unit can handle the weight. One thing I have noticed one this tumbler is that it will start off a little slow and as the material is ground down it picks up some speed. It may just be me but to figure out if this is actually happening I'm going to put a mark in sharpie pen on the side of the lid so I can count the RPMs at the start and finish of a run. Not that it's really all that important, but it would be nice to know if it's actually happening or if I'm going crazier than usual....

 

[Goldwasher]

From our newest black sands vortex. A member here sent the sands saying that there was no gold.

so the sand is really clean?.....is there gold in the picture? im confused

 

[johnedoe]

From our newest black sands vortex. A member here sent the sands saying that there was no gold.

I would like to know more about this vortex gizmo you are using.

 

[GoldpannerDave]

It's all cool.... I'm done with that conversation.
Also as Mytimetoshine said the run times are generally only a few "10-15 minutes.. ya just have to play that one by ear though as I am sure the size of the drum and composition of the drum will certainly make a difference.

And the proper speed of rotation! That was one problem I could not fix with just the rock tumbler, because I could not get it to rotate at the proper percent of the critical speed. Not being in Arizona, it is a winter project.

 

[GoldpannerDave]

The cons have been screened through 30,50,70,100 mesh screens as I was going to blue bowl them. Once I get the rods cut I will run them as separate sizes and see what happens. I did order a USB camers today but not sure when it will be here.

Goldenirishman do you have a picture of your rods in the barrel. Im curious how full it is?

Mine was about 1/4 when I was running my experiments, but the original was about 40%. I think goldenIrishman was also about 1/4

 

[goldenIrishman]

here you go Mu50stang....



Like I said I've got more stock to make up more rods. Just haven't taken time to do so yet.

 

[goldenIrishman]

Ok guys. I got the rest of the rods cut and I ended up with 9 each 1/2 and 1/4 inch rods. With all of them in the barrel it fills it up about 30%. I tossed them all in one barrel with some black sands and water and the tumbler doesn't seem to be having any problem turning it. Now we'll see if more actually is better or not. As for myself, I'm feeling like someone nailed me in the small of the back with a 2X4. Been a long day and I can hear that Guinness a callin me name lads!

 

[KevinInColorado]

Ok guys. I got the rest of the rods cut and I ended up with 9 each 1/2 and 1/4 inch rods. With all of them in the barrel it fills it up about 30%. I tossed them all in one barrel with some black sands and water and the tumbler doesn't seem to be having any problem turning it. Now we'll see if more actually is better or not. As for myself, I'm feeling like someone nailed me in the small of the back with a 2X4. Been a long day and I can hear that Guinness a callin me name lads!

#GuinessForStrength!

 

[goldenIrishman]

Doing a little research on-line I found some suppliers for finer screens ranging from 1/2 down to 1/325. I also happened across the following chart/table that gives us a good idea of the sizes we re dealing with as related to mesh sizes.

Mesh to Micron Conversion Chart

Kind of interesting if you ask me. Not that I'd want to be working with the sizes at the bottom end of the chart mind you. Those would pretty much make Talcum powder feel like 60 grit sandpaper. I remember using 5 micron wet or dry sanding film to polish the ends on fiber optic connectors and it almost felt like plain plastic.

I'd like to run some of the materials I've been working with through a 325 mesh just to see what is going on under the scope, but at $30 a sq/ft for unmounted screen I think I'll pass.

 

[goldenIrishman]

Rolled Gold !

Well after running some -70 sands that had been cleaned in the rod mill I managed to find even more gold in them. I had checked this batch under the scope before running them and could only see a tiny bit of gold in it sticking out from some of the particles. I ran about 1/8 of a cup using all of the rods and it did a great job of crushing the gold out of the sands and flattening it out so it became visible. Sure they're still tiny pieces, but at least I could see them without needing my glasses and a magnifying glass. The scope and cell phone camera setup was being a pain this morning but I managed to get these shots of some of the take. LOTS of silver in the mix as well.



That's not all the gold I got from this batch but some of the best looking pieces. There is also some little crystals that survived crushing. I'm thinking maybe garnets but they've got to be tough to make it through the cycle without getting crushed with everything else.

I'm now running some -70 magnetic sands to see if I get more out of them as well. The mix this time consists of 1/4 cup -70 magnetic sands, all 11 of the rods and 3/4 of a cup of water. It seems that I have to use more water than the PDF calls for to get a smooth action on the tumbler. Using the 1:1 (by volume) caused the barrel to hop around. Soon as I added more water the action smoothed right out. If this gives me more gold, I've got a couple of coffee cans full of magnetic sands I can run.

 

[goldenIrishman]

I've decided to build up a miller table following AzVipers instructions and us it to recover the gold after grinding. It will be both faster and easier than panning it out. Once I have it set up, I can turn Jan loose on it and let her do the cleanups while I work on moving and processing the larger stuff.

 

[chlsbrns]

Must of been pretty clean since I don't see any picture of the take.

so the sand is really clean?.....is there gold in the picture? im confused

The picture consists of a pan a dime and gold. Gold that was obtained from about 50 pounds of black sands in about 30 minutes. Most of the gold is about the size of talcum powder. It was sent to me by a member who processed it with a final process thru a miller table. In other words the miller table and his other processes missed the gold shown in the pictures.

 

[Goldwasher]

Must be the lighting