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]

Rant on.....
I just don't understand why people seem to think that reinventing the wheel is so necessary especially reinventing the wheel with inferior components.
You are dealing with iron ores, quartz, as well as other hard elements and gold particles all of which will require HARD surfaces to accomplish the desired results.... CRUSHING & FRACTURING ore.

Not sure I would want to be around your lab during some of your experimental chem. projects.........
Rant off.....

Maybe you should use the signature line that Golly mr. science uses over on another forum ..... "Why don't we just keep adding stuff to this till it blows up or just smells really bad...."

Why? Because I don't have the $2000 Clarkson said it took to build what he has. So why not try a smaller alternative? The desired results are not "CRUSHING & FRACTURING ore" only but also to flatten the gold. You don't need overkill since you can feed classified cons to it. The desired result is to grind the non-gold cons a bit; it you had 60 mesh, you want it smaller so it passes through the 60 mesh screen, but the parallel result is to flatten the gold so it does not go through. If you crush them both so they pass through 60 mesh, you have failed.

Seems like a rock tumbler might be a reasonable low cost alternative to the $2000 dollars for the one we know for sure works. No one is trying to improve on Randy Clarkson's machine or reinvent it; just trying to use the principles involved to provide a low cost set up that might also work....

 

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[GoldpannerDave]

If I tore up the treadmill for the motor, what would my wife use to hang clothes on?

I am not removing the motor. I am going to put the rod mill on the treadmill conveyor belt and let the treadmill run, turning the round container as it does. I have to rig up a bracket to hold the contain in place while letting it turn.

However, with or without a motor, I would think your wife could still hand clothes on it!

 

[johnedoe]

Why? Because I don't have the $2000 Clarkson said it took to build what he has. So why not try a smaller alternative? The desired results are not "CRUSHING & FRACTURING ore" only but also to flatten the gold. You don't need overkill since you can feed classified cons to it. The desired result is to grind the non-gold cons a bit; it you had 60 mesh, you want it smaller so it passes through the 60 mesh screen, but the parallel result is to flatten the gold so it does not go through. If you crush them both so they pass through 60 mesh, you have failed.

Seems like a rock tumbler might be a reasonable low cost alternative to the $2000 dollars for the one we know for sure works. No one is trying to improve on Randy Clarkson's machine or reinvent it; just trying to use the principles involved to provide a low cost set up that might also work....

Tell us how much money you waste on the experiments that don't work OK?...
As to the $2000 bucks I think that is a bit high.... I think they went out and bought new materials and cement mixer.
Do some shopping around and I bet you could put the Clarkson machine together for $500 or less if you are really intent on building one.
Which brings us to another point..... Do hobby/recreational miners really need to goto this extent to capture the small amounts of gold they get?
I sure as hell don't..... And yes I am a "hobby/recreational miner" it gets me out for some fresh air and exercise from my normally physically sedate profession.

 

[DizzyDigger]

" And yes I am a "hobby/recreational miner" it gets me out for
some fresh air and exercise from my normally physically sedate profession.

Really? Does that mean you put all the gold you find back in the river?

Of course you don't. You keep it, and gold is worth money. Since you
are getting paid for your efforts (gold) that puts you in the "non-amateur"
category.

You may have fun while you're obtaining the gold, however in reality you
are a small-scale miner that truly enjoys his work, and loves being outdoors.

Not trying to start a debate...it's JMHO...

 

[johnedoe]

Really? Does that mean you put all the gold you find back in the river?

Of course you don't. You keep it, and gold is worth money. Since you
are getting paid for your efforts (gold) that puts you in the "non-amateur"
category.

You may have fun while you're obtaining the gold, however in reality you
are a small-scale miner that truly enjoys his work, and loves being outdoors.

Not trying to start a debate...it's JMHO...

Your right..... I forgot one... "hobby/recreational/small scale" miner..... there fixed it .

 

[Disfunctional]

The problem likely would be burning out the tumbler motor. The weight of the iron rods might make it too heavy to easily rotate. Still, why not try it? Yes, the inside liner is rubber (which are replaceable), but I think most of the grinding comes from the rods themselves.

His tumbler looks to be about 8-10 inches in diameter. A rock tumbler is about 6" and generally not as long. Still, I think it might be worth a try. I am sure with all the research Clarkson did, his dimensions are better, but you just might get pretty good recovery with a rock tumbler. Some testing would be required to see if you need longer times (likely) and if it actually will work.

Actually a rod mill is considered more efficient than a ball mill and reduces the material size more evenly. The design used by Mr. Clarkson isn't typical of rod mills, but the effect is the same, (based on my research, due to my personal interest in the concept).

Besides this design, there are at least three others that include continuous feed such as the; pass through version, the center and end periphery versions. Normally commercial units have a liner to reduce wear and let the rods take the abuse. Im not sure what the normal lining is, but there has been at least one pvc rod mill built and apparently it worked well. Stronger materials like HDPE High Density Polyethelene, and UHMW Ultra High Molecular Weight, actually have a much higher abrasion resistance than steel.

I hope to build one using pvc later this summer to test and modify into a 2 or 3 stage unit with different size screens between them. Having a continuous feed setup would mean not having to load, screen, reload, rescreen, etc... Just run several loads through and if the screens get clogged with gold, shut down and clean out the gold.

 

[AuSomeness]

Actually a rod mill is considered more efficient than a ball mill and reduces the material size more evenly. The design used by Mr. Clarkson isn't typical of rod mills, but the effect is the same, (based on my research, due to my personal interest in the concept).

Besides this design, there are at least three others that include continuous feed such as the; pass through version, the center and end periphery versions. Normally commercial units have a liner to reduce wear and let the rods take the abuse. Im not sure what the normal lining is, but there has been at least one pvc rod mill built and apparently it worked well. Stronger materials like HDPE High Density Polyethelene, and UHMW Ultra High Molecular Weight, actually have a much higher abrasion resistance than steel.

I hope to build one using pvc later this summer to test and modify into a 2 or 3 stage unit with different size screens between them. Having a continuous feed setup would mean not having to load, screen, reload, rescreen, etc... Just run several loads through and if the screens get clogged with gold, shut down and clean out the gold.

I can only wish for such problems

 

[Disfunctional]

In my previous post I neglected to mention that by using a continuous feed rod mill, a person running a small mining operation with just a sluice, or just panning, could get away with a rod mill as small as 6" in diameter by 9" or longer. If you've looked at a commercial end peripheral rod mill, the screens they use are removable without having to remove the rods, (a feature I like), so you could run your cons through once, change to a finer screen and repeat.

As for the rod mill that was developed by Mr. Clarkson, its size is larger than most small scale operations might need. The miners in the Yukon run tons of material and have lots of cons.

If I can get to this project of building my own rod mill soon, I planned to use 6" PVC, because I have some. hope to be able to use a windshield wiper motor with its gear reduction to turn it. A windshield washer pump would feed water in. The idea being to allow its use with any 12 volt source. I run most everything off of the solar panel and battery of my travel trailer now, so it makes sense for my situation.

 

[GoldpannerDave]

Actually a rod mill is considered more efficient than a ball mill and reduces the material size more evenly. The design used by Mr. Clarkson isn't typical of rod mills, but the effect is the same, (based on my research, due to my personal interest in the concept).

Besides this design, there are at least three others that include continuous feed such as the; pass through version, the center and end periphery versions. Normally commercial units have a liner to reduce wear and let the rods take the abuse. Im not sure what the normal lining is, but there has been at least one pvc rod mill built and apparently it worked well. Stronger materials like HDPE High Density Polyethelene, and UHMW Ultra High Molecular Weight, actually have a much higher abrasion resistance than steel.

I hope to build one using pvc later this summer to test and modify into a 2 or 3 stage unit with different size screens between them. Having a continuous feed setup would mean not having to load, screen, reload, rescreen, etc... Just run several loads through and if the screens get clogged with gold, shut down and clean out the gold.

I know some rod mills in South Africa used rubber liners but some rod mills use steel. I am not sure it matters that much. On a site about mills in general, I found the following, "Grinding action is by line contact between the rods extending the length of the mill. Rods tumble and spin in roughly parallel alignment simulating a series of roll crushers. This results in preferential grinding of coarse material and minimizes production of slimes."


So please let us know how the PVC for the mill works out.

 

[Disfunctional]

GoldpannerDave;
I'm hoping someone else will have built one before I can get to it. The next couple of months are going to be hard. Can't go into details but I'm not optimistic about a certain situation I have to deal with. Will know more if the fat lady sings....

 

[KevinInColorado]

I built a mini version of this using the paper handling mechanism from an inkjet printer (for free!). I used a coffee can as the drum and some random pieces of chain and rod as the crushers. It worked until the motor burned out in one of my experiments...next time I'll add a cooling fan for the electric motor!

I was pleased by how it made particles smaller except the gold which got flattened and therefore "bigger"... Certainly easier to see in the pan!

 

[GoldpannerDave]

GoldpannerDave;
I'm hoping someone else will have built one before I can get to it. The next couple of months are going to be hard. Can't go into details but I'm not optimistic about a certain situation I have to deal with. Will know more if the fat lady sings....

As soon as I get time to go find some scrap steel rods, I am going to try my rock polisher as a rod mill. I also now have two formulas for the critical speed of a rod mill.

Using Clarkson's formula, for their 8 "mill, the critical speed is 98.6 rpm. He says run the mill at 75-80% of the critical speed, which is ~74-79 rpm. For the other formula (which used feet, Clarkson's used inches and a functional inside diameter vs just inside diameter), the numbers are 94 rpm critical speed giving a range of 70-75 rpm. They are close.

Using a 5 3/4 " inside diameter rock tumbler with 1/2" and smaller rods, the Clarkson numbers for the 75% -80% speed are ~87-93 rpm and the other calculation gives ~83-89 rpm.

For your 6" PVC mill, the numbers are similar. The critical speeds are (Clarkson calc.) 116 rpm and 108 rpm for the other value calc. using feet. Then using the 75% to 80% of the critical speed, you get ~87-93 rpm (Clarkson) and ~81-87 rpm. I used max rod size of 3/4 " for your mill.

I had another idea for turning the mill (already mentioned rock tumbler and treadmill). A short, squat ice cream freezer! You have to turn it sideways (not the Sherry method) and support it level and the motor might not be strong enough (I suspect it won't). Also, you'd probably have to add a liner inside to seal the "mill" tightly.

For motors, if the ice cream one is not enough, there is your idea of a windshield wiper motor. I am not sure about that one any more than I am about the rock tumbler motor. The smallest cement mixer I could find with a quick search was $170. There would be shipping. But maybe you could get lucky with a garage sale used one!

Anyone have other ideas of motors?

 

[GoldpannerDave]

I built a mini version of this using the paper handling mechanism from an inkjet printer (for free!). I used a coffee can as the drum and some random pieces of chain and rod as the crushers. It worked until the motor burned out in one of my experiments...next time I'll add a cooling fan for the electric motor!

I was pleased by how it made particles smaller except the gold which got flattened and therefore "bigger"... Certainly easier to see in the pan!

Yeah, I thought about using a metal coffee can for a larger diameter than my rock tumbler so I could use 3/4 " rods in it. Nice that you tried it. Of course, the problem seems to be the motor more than the material the mill is made of. Interesting you used chain also. I think I will stick to rods for now, but your feedback is invaluable. It likely means the 6 " PVC or the 5 3/4 rock tumbler will work as a mill. Now for that motor problem. The ink jet printer probably has a weaker motor than the rock tumbler or the ice cream freeze idea I mentioned (which could be a garage sale find). That is encouraging; you still got flattened gold and the other material became smaller--just like it should have!! YES!

 

[Disfunctional]

I'm going into town Wednesday to get some grub and see if I can locate a wiper motor. I like the wiper motors from trucks due to normally long service life and I think they would be strong enough and fast enough without additional gearing. Thanks for the number crunching. I had thought that about 80 rpm would be a good target to shoot for. If the motor is too fast, a dimmer switch should work to slow it down, otherwise if its too slow, different pulleys may work.

If I use PVC, I'm not sure where to find flat material for the ends? I wonder if I can super glue a lexan, (plexiglass) disk on the end? i have lots of scraps but cutting them in circles is a pain.

 

[GoldpannerDave]

Truck wiper motors! I was thinking car, which are all I have used in the past. Good idea.

I think you could use almost any type flat plastic since there is not too much wear and tear on the ends (at least not as much on the tube itself). You can get PVC sheet, but it is expensive; perhaps you can find scrap. Then you can use PVC glue on the one end that stays closed.

You are welcome for the numbers; I just took Excel and fixed it up so I can add in any diameter and any size rod and do the calculations in a zip. So if you try another diameter and want to know speeds, let me know.

How are you planning to keep the other end sealed while rotating the mill yet easy to open to load and empty?

 

[arizau]

Truck wiper motors! I was thinking car, which are all I have used in the past. Good idea.

I think you could use almost any type flat plastic since there is not too much wear and tear on the ends (at least not as much on the tube itself). You can get PVC sheet, but it is expensive; perhaps you can find scrap. Then you can use PVC glue on the one end that stays closed.

You are welcome for the numbers; I just took Excel and fixed it up so I can add in any diameter and any size rod and do the calculations in a zip. So if you try another diameter and want to know speeds, let me know.

How are you planning to keep the other end sealed while rotating the mill yet easy to open to load and empty?

Maybe center drill the end caps, insert threaded rod and tighten with wing or regular nut? Rubber gasket for seal.

Good luck

 

[KevinInColorado]

They sell pressure test plugs for just this sort of thing. They inflate to seal and are made for each pipe size. Original purpose is to pressure test a buried sewer line to check for leaks.

 

[Disfunctional]

Truck wiper motors! I was thinking car, which are all I have used in the past. Good idea.

I think you could use almost any type flat plastic since there is not too much wear and tear on the ends (at least not as much on the tube itself). You can get PVC sheet, but it is expensive; perhaps you can find scrap. Then you can use PVC glue on the one end that stays closed.

You are welcome for the numbers; I just took Excel and fixed it up so I can add in any diameter and any size rod and do the calculations in a zip. So if you try another diameter and want to know speeds, let me know.

How are you planning to keep the other end sealed while rotating the mill yet easy to open to load and empty?

The idea I have, is to seal one end and make a partial circular piece that's flaired out with a round opening for continuous loading and water injection. About an inch from the closed end, I was going to use a 1 1/2" hole saw to make an opening for a second short piece of PVC with threads. A threaded pvc cap with a hole in the end, or plain threaded pipe, would have screen covering the opening, allowing crushed material an water to pass through as the unit spins on its axis.
I was thinking is using wheels from roller blades as the surface of the rod mill to roll on, with a thin belt around the rod mill and motors pulley to drive it.
If I can't find flat scraps of PVC for the ends, I'll try the lexan plus glue and some tiny screws to hold it together.
As I vaguely alluded too, the one end would remain open during operation, allowing for the continuous feed of cons and water but a splash guard may be needed.
As for the spinning slightly protruding pipe that allows the screened discharge to exit, a guard would be needed to catch materials and direct them into a container that let's excess water to drain off.

At least that's the general idea.

 

[FC-Treasure]

eBay has a huge number of electric motors, every size/shape you can imagine. Here I have setup a search and sorted by lowest price. Note the Horse Power filters on the Left Hand Side so that you can dial in the power that you think you will need. You will need power/speed control as well. Seems like you could find a motor for around $20 bucks, up to 1/3rd a horse power.

hp electric motor in Electric Motors | eBay

 

[Disfunctional]

Thanks!

Doodled a sketch to try saving on the thousand words. A 5 inch screen isn't ideal for drawing.