Simple solution to fine gold recovery

[johnedoe]

This was developed by Randy Clarkson, an expert in gold recovery designs.

A simple gizmo to help miners snag lost gold..... New gizmo could help placer miners snag lost gold | Yukon News

Also this by Randy Clarkson on fine gold recovery which is somewhat misleading in that this is mostly about commercial ops and 1" minus classification is considered fine....... The Clarkson Study Fine Gold Recovery

Here is a PDF presentation of the process....... http://www.geology.gov.yk.ca/pdf/141114_Nov1014_Grinding_for_Gold_Presentation.pdf ....... Thank you arizau for finding that PDF

Enjoy the learning.

 

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[GoldpannerDave]

Steel is really best in principle. In practice it probably doesn't matter. I'm sure you could also use brass or even stone rods.

The pros run wet, I didn't know that and ran dry. Both work I guess.

I plan to try it both ways (wet and dry) with iron or steel (whatever they gave me yesterday). And as arizau mentioned, I should have a mix of diameters of rods. Will try that also. Then use those new screens as stuff gets smaller, but I will probably start with +20 or +30 or something like that; maybe even +10. Those new screens are much smaller mesh.

 

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[GoldpannerDave]

I had hoped to get to tumbling some gold this weekend; sorry guys, no report. The course director of the chemistry course I teach moved up the deadline for grades and I spent 8 hours this weekend finishing grading last lab reports. I also spent 4 hours helping cadets prepare for chem finals. Then I spent 4 hours at a Hail and Farewell departmental functional (there was a lot of change-over) and 4 hours at another social function. On top of that, my 6 year old granddaughter had a birthday.

Plus, the garage was freezing and too cold to work in, even if I had any spare time--due to the snow and hail we have been having here in Colorado Springs. So I should have time next weekend to post results of tumbling gold in a rod mill using the rods I pictured above. For now, I have to go grade finals, give finals, grade some more, make grade cuts, for the majority of the rest of the week.

Again, sorry, I really did hope to get some results, but there are only so many hours in a weekend.

 

[arizau]

Any excuse is better than none I always say but, so many? I hope semester end will give you more free time especially to go find some gold rather than to concentrate on concentrates (pun intended).

 

[mytimetoshine]

Unexceptable. Your fired. Good day.

 

[GoldpannerDave]

Any excuse is better than none I always say but, so many? I hope semester end will give you more free time especially to go find some gold rather than to concentrate on concentrates (pun intended).

Thanks; I sincerely hope to hit the creeks for some gold soon. Even if I had had time to work a creek this last weekend, the weather here was absolutely miserable. GrizzlyGremlin might have gotten out in it, though.

 

[GoldpannerDave]

OK, now that I have finished turning in grades, I decided to get out my rock tumbler and try it as a rod mill. While I did find it after I went through all the boxes from the move last year, it is a tad smaller than I thought. It is a 1950-60's model from Sears. In my mind, I thought it was Lortone; they are 4.5" diameter and 5" long. Mine is 4 3/8 " diameter and 4 5/8" long, but the internal length is more like 4 3/16 " and so the 4 3/8" length rods will not fit. Arrgh! My daddy always said measure twice, cut once.

So I need to snip the ends off; probably do it with a bolt cutter. This is very aggravating since I did not have time to find the tumbler during the last week of class so I checked the specs online--not remembering that it was a Sears model. Oh well, this report is a comment on doing ALL your homework before embarking on a new adventure.

More after I shorten the rods. Sorry, I really thought I could run an hour or two and see what I got. Well, maybe I can add a couple more rods, some with different diameters by the time I actually do the milling.

 

[KevinInColorado]

Quick work with a hacksaw right Dave?

 

[GoldpannerDave]

Quick work with a hacksaw right Dave?

Yes, but now I have to find the hacksaw, but that will be easier to find than the bolt-cutter. Nothing is where is used to be before we moved. I hate just having a garage now and no basement to work in. And because we moved during the academic year, everything was just stored. At least I know where the vise is.

When the boys leave, I will start looking for the hacksaw and try to get a run or two today.

 

[GoldpannerDave]

I have looked again at Clarkson's parameters.
-Approximately 40% of the volume taken up by rods
-Cons are about 5-10% of total volume (do not overload)
-Use 1:1 ratio of cons to water (by volume it seems)
-Run less than 10-15 for first run to determine time needed for cons (and for our modified mills)
-Run at 75-80% of critical speed; basically you should run as slow as you can and still get the gold flattened.

So other than having a mix of rods and an 8" barrel, I will be using my rock tumbler (Sears called it a gem tumbler) and there is only one speed, so hopefully, with the load it will run between 90 and 110 rpm.

Not having rods that make up 40% volume of the tumbler, I will reduce the amount of cons I add to avoid overloading. I will try to get additional rods next week.

 

[GoldpannerDave]

I have looked again at Clarkson's parameters.
-Approximately 40% of the volume taken up by rods
-Cons are about 5-10% of total volume (do not overload)
-Use 1:1 ratio of cons to water (by volume it seems)
-Run less than 10-15 for first run to determine time needed for cons (and for our modified mills)
-Run at 75-80% of critical speed; basically you should run as slow as you can and still get the gold flattened.

So other than having a mix of rods and an 8" barrel, I will be using my rock tumbler (Sears called it a gem tumbler) and there is only one speed, so hopefully, with the load it will run between 90 and 110 rpm.

Not having rods that make up 40% volume of the tumbler, I will reduce the amount of cons I add to avoid overloading. I will try to get additional rods next week.

OK, I have two runs. I cut the rods with a hacksaw, but left the little pieces in the tumbler with the larger rods. I could only get about 1/3 critical speed (about 45 rpm) vs the numbers above. I calculated the total volume and 2.7 Tbs was 5%, so I went with 3 Tbs of cons and 3 Tbs of water. You can see the picture of the tumbler with rods and then with rods and cons.


I thought I was running +60 mesh, but in fact ran +40. When I ran the first sample 60 minutes and put it though the 60 mesh screen, a fair fraction went through!! So the rod mill had reduced the size of the particles. Not knowing that I used +40, I ran the next sample 2 ½ hours. Then I discovered my mistake.

So, I am sorting through the results, but a couple of things for sure—the rod mill did reduce the size of the black sands. Also, I have flattened gold that floats very easily because it is so thin. Jet Dry was mandatory because even the larger pieces you see here floated without it.

 

[GoldpannerDave]

Two more pictures, maybe they are easier to see. I tried to spread out the gold rather than make it a line at the top of the pan. I hope you can see it OK.

 

[KevinInColorado]

Victory! (Right?)

Bet you could shorten the run time...lots of experiments to run now.

Where was the cons sample from?

 

[arizau]

OK, I have two runs. I cut the rods with a hacksaw, but left the little pieces in the tumbler with the larger rods. I could only get about 1/3 critical speed (about 45 rpm) vs the numbers above. I calculated the total volume and 2.7 Tbs was 5%, so I went with 3 Tbs of cons and 3 Tbs of water. You can see the picture of the tumbler with rods and then with rods and cons. View attachment 1163532 View attachment 1163533


I thought I was running +60 mesh, but in fact ran +40. When I ran the first sample 60 minutes and put it though the 60 mesh screen, a fair fraction went through!! So the rod mill had reduced the size of the particles. Not knowing that I used +40, I ran the next sample 2 ½ hours. Then I discovered my mistake.

So, I am sorting through the results, but a couple of things for sure–the rod mill did reduce the size of the black sands. Also, I have flattened gold that floats very easily because it is so thin. Jet Dry was mandatory because even the larger pieces you see here floated with it.

View attachment 1163535

Are the panning results just from the remaining larger fraction material or a combination of plus and minus?

 

[GoldpannerDave]

Victory! (Right?)

Bet you could shorten the run time...lots of experiments to run now.

Where was the cons sample from?

Well, I thought since the majority did NOT go through the 40 mesh screen, I would run the 2nd batch longer. Of course, it was a 60 mesh screen, not 40. And so, the 2 1/2 hours is likely way too long; I want to examine the 1 hour sample in more detail. I have not run the original sample through the 40 mesh screen yet. I plan to run them through the 40, 60, 100, 112 (120 microns) and the 170 (90 microns) all in a stack and see what happens. I am interested how small the smallest material is from the 1 hour rod mill sample that I mistakenly put through the 60 mesh screen.

These are Clear Creek cons.

What I want to find out is how long to run the material (given the mesh size and origin) to get mostly only gold in the + fraction with very little black sand. In theory, if you get it right, the vast majority of the black sand goes through the screen leaving nice gold behind. See the photograph of before and after from Clarkson's presentation.

 

[GoldpannerDave]

Are the panning results just from the remaining larger fraction material or a combination of plus and minus?

This is some of the +60 material. I don't have the parameters right yet, so I do have to pan it down to see the gold. I have lots of panning to do yet, so this only represents some of the results. I will not combine the + and - fractions but do them all separately.

 

[KevinInColorado]

Love this...can't wait to get home and build a new one myself! We're inspiring each other :-D

 

[GoldpannerDave]

That is great, Kevin; the more folks doing testing, the sooner we know generally what works and what doesn't.

I would like to try to run my tumbler faster than 45 rpm but maybe I should stay at its regular speed (other than a couple of tests) since I would guess most folks that might use a rock tumbler would be using it at its regular speed. At that speed, an hour may do it--I need to pan results from the first batch I ran (after I screen it properly) to determine that.

 

[Duckwalk]

If you are building a rod mill from scratch with random motors. You can try reducing the gear size close to the container to create more rpm. I run more voltage through series wired 12v batteries to increase my speed. I run 4 and it gives me the same amps as 1 battery but 51v output. I need to measure it adding one battery at a time to determine what my increase of rpm is.

Also if you are looking for a 12 wall power source, grab a power supply from and computer and look up the wording diagram, there are 12v wires all through it. I usually keep it intact and add on a cable extender that I can mess with so I don't ruin the power supply. I'll add pics tomorrow

 

[KevinInColorado]

I just use the power supply that came with the printer I tear apart. That works fine

 

[johnedoe]

I wanted to stop back in here and congratulate you guys on the progress you have made with your experimentation with the original equipment concept.
I tend to be a bit ridged in my thinking sometimes as some of you may have noticed earlier in the thread.
Anyway ... Good work guys on making great contributions to the concept..... keep up the good work.