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Author Topic: Gold Cradle.  (Read 10466 times)

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Offline rockpup

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Gold Cradle.
« on: April 28, 2009, 10:39:30 PM »
Ok I made what I call a Gold Cradle.It may look like something you seen before,but it is not.This has a few things never seen before,until now.I made What I call a Apan,not Apron.Its is what its name implies,a apron with a pan.Someone thought it be cool to build a gold pan into a Rocker,well i put one in my Gold Cradle.I personaly have never seen this before.The bottom has a special miners matt(green) which will catch any course gold.The layuering is the key to my Gold Cradels sucess,nothing will escape its clutchs.The miners matt gets the big stuff,the stainless steel miners moss insures fine gold recovery,if any is missed the carpet below will trap that.I will try both a wider spaced carpet and a finer space carpet.It would depend on gold type and gravel type.I just need to install hold downs,which will take 5 minutes.




Offline PlacerPal

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Re: Gold Cradle.
« Reply #1 on: April 28, 2009, 11:37:12 PM »
Don't know anything about rockers other than what I read about them.
Your rocker looks very innovative and I can relate your apan innovation
to what I have seen elsewhere on new generation rockers pans.

After you put a few yards through your rocker from your claim(s) over
in the Cranbrook area, collect and save some of your black sand tailings cons.
Get a qualitative assay to get an idea if you are losing the fines.
You would have to keep records on whether there is fine gold
in the apron, in the apron pan, the riffles and mats. No gold in any of
them but gold in the black sand tailings - back to the drawing board!  <-yes_>

 

Offline GollyMrScience

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Re: Gold Cradle.
« Reply #2 on: April 29, 2009, 07:08:23 AM »
You should have fun running and testing something you have built yourself.

Certainly recovery testing is in order but don't forget that any gravity recovery device has a lower practical limit in the sizes of gold it will recover.

There are significant values locked into sulphides and some of the black sands that will NEVER settle in a gravity system of this type so be careful on how you test your tailings.

If in an area with a lot of very fine gold you will see some of that show up in the tails - by its nature a unit like this will not save gold finer than 150 mesh without starting to lose gold finer than that. Depending on black sands loading etc you will see more or less recovery in the finer sizes.

The point being that when running gravity concentrators you have to accept a percentage loss and your job is to minimize those losses as best you can.
I have seen operators freak out seeing five 100 mesh flakes of gold in a pan of tailings yet when translated back to actual weight recovery versus recovery in their operation they were saving 94% of all available gold in the plus 200 mesh sizes. The cost to recover the extra 6% (and you will never get it all) was just too much for the money invested.

What you might try as a rough and ready experiment is to run the unit for a period of time and then do screen classified tailings tests.
Classify fairly large samples of your tailings into some narrow size fractions. ie 1/4 to 1/8, minus 1/8 plus 1/16, then screen on the 20 mesh, 50 mesh, 80 mesh and 100.
You can go finer but for larger tests it gets real slow.

Each fraction is carefully panned and the gold (if any) from each fraction is dried and weighed. Don't get worried if you see a few fine flakes because the next step will tell you where you really stand. You now take your concentrate from the unit and do the same thing. The gold from your screened cons is dried and weighed and then you can do some analysis of recovery.

As an example:

You find no gold in all of the tailings fractions in the plus 30 mesh sizes. But you find plenty in your cons then you can state that you recovered 100% of plus 30. You find a couple of flakes in the -30 to plus 50 mesh fraction but its the weight that counts so when compared to the actual weight of the -30 plus 50 from the cons you discover that you only lost 2% of that fraction. You can see the direction this is going.

At the end of the day you will be able to plot a recovery curve for the machine with the proviso that the curve applies to that machine on that day in that place under such and such operating conditions.

A few of those and you will be able to get a good handle on the recoveries you can expect on average and you can also see when a change actually makes a difference in recovery.

This is the labour intensive method but it keeps you from getting caught by analytical methods that catch gold that you cannot even hope to recover.

I once had to work with a group of miners who were using a gravity recovery circuit but having their tailings assayed by both fire and bottle roll leaching.
The fire assay results were all over the map but way higher than what they were getting in the unit they were running. It took some explaining for them to realize that one milligram of gold in a standard fire assay of 29.17 (rounded number) grams is equal to one ounce of gold per ton!!

It does not take much gold to get a milligram but the real kicker was that they were not only getting a nugget effect from the odd piece of free gold they were also getting ALL the gold which includes the gold locked into other minerals and just not gonna be recovered unless the operation sets up to do so. For many its not worth it once the costs of recovery versus the returns are plotted.

The bottle roll analysis was an attempt to run larger samples to overcome the nugget effect in fire assay but the bottle rolls cyanides were still recovering a lot of the locked in values.

A careful screen test on a bulk sample of the tailings - plotting size of gold and weights in each fraction showed they were recovering 92% of the gold that was recoverable as free gold from the area they were working. There was very little minus 100 gold in the raw gravel. Perhaps 3% of total free gold available in the 400 mesh plus fractions. The cost to chase that was totally out of the ballpark compared to the returns and everybody settled down and got back to mining.

If they had gone by their fire assay or bottle roll testing they were convinced that the equipment was not working. It was doing all that gravity equipment could do within the economic constraints they had.

Now you might think that screening and panning all that material is a bit much for you so if that is the case I would suggest you refer to the placer testing method invented by Alexandar Gudenov. Periodically pan your tailings to check for gold losses. If you are not seeing much in the way of losses compared to what you are catching then its Gud-enov for you.
What the heck - lets just keep mixin' stuff together till it blows up or smells REALLY bad!

Offline rockpup

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Re: Gold Cradle.
« Reply #3 on: April 29, 2009, 03:17:26 PM »
LOL thnaks golly.This will help put the gold cradle to the test.I would like the best recovery possible.I will have to see what classfiers i can get a hold of and do some tests.I hope to  be able to recovery fine gold from my area at home. the gold is real fine alberta godl with alot of black sand.

I was not sure on the pan Idea,but In my mind it should work as a good place for the heavies to settle.

Isfog suggested that I shouls make a refletor for my rails.I think that is a good idea will direct flwo better. oever my expanded metal.


Offline rockpup

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Re: Gold Cradle.
« Reply #4 on: May 03, 2009, 03:33:55 PM »
Ok testing results are in.First test 88% recovery rate.Mostly in the bottom half(30% of test lead,but the fine gold was sure in there)lost 2 pieces of larger lead also concernes me.The apron I first made I did not test with any of my lead pieces,duh.It did catch a piece that was not panned out by me.All this material is tailings, worked over at least once.I am getting alot of dust which lets me know the fine gold is getting trapped.It is removing fine gold I could not before.

I will need to test the first apron again.Further testing should improve my rocker skills.I removed the kick stand and handle.It feels better without it.I feel it was just my operation that lost most of the gold.I did manage to surge the water a fwe times most likely washing that gold(lead) out.

I do like the normal apron with out the cup.I will give it another test.This time I hope to get around 92%.
No surges.I can see the skill in the operator being a majour factor in the sucess of a rocker.
I have more of a feel for its now.Kinda like panning.I need less water and agatate more.

I have decided the miners moss is not needed too much cons.I will pan the test with miners moss to see if the fine gold is more.

Overall I feel its recovery rate wiil be better once i learn how to use it.I was surprised to recover as much as  I did.18 out of 22 test pieces.Plus some fine gold.

Offline rockpup

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Re: Gold Cradle.
« Reply #5 on: May 13, 2009, 05:32:41 PM »
Remade the apron for the 5th Time!!Boy it is hard to get that part right.It would be nice for easier cleanup.As far as I can tell the bottom of the rocker gets allmost everything.If the apron will improve recovery bonus,I will test again and see if my results are better.I also found out pre-screening is the way to go.Keep the gravel in a water like sludge state and feeds way better.The holdowns work in conjuction with the grizzly to keep the apron in.It fits snug and I am able to adjust the angle.

Offline HPowell

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Re: Gold Cradle.
« Reply #6 on: August 09, 2009, 06:23:29 AM »
I like your rocker. I'm in the works on one for an upcoming trip. I have used the fuzzy, kind of loose bathroom mats before in a sluice and it did real well for catching the fine gold.

Offline rockpup

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Re: Gold Cradle.
« Reply #7 on: August 10, 2009, 11:32:35 AM »
Hey cool i know the matts your talking about!Those might work good!
I will have to try to get some old ones and try them out.

 


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