Classification (need your pro's on this)

[Deleted]

Most of us when hitting the gold at the end of the day classify down to a 12 and pan it. Alot of people through their black sands and so forth away, don't even bother to save them. I am asking information from the guys that classify down to -200 to chime in on this conversation and show us their ways of getting all the gold from their concentrate.

If you have a step by step way of doing it, please share it with us. I believe we all work hard for our gold, and we should reap the rewards from even the super fine gold.

[samburgin]

Classification is the key to efficient and effective gold recovery. But that assumes that you captured the gold in the first place. All dredge tailings that I've tested contain, for me, an uncomfortable amount of fine gold.

On balance, however, dredging is a much more effective way to capture placer gold than most any method available to recreational prospectors. Longer sluices, more classification, and slower through-put would capture more fines, but at the expense of volume.

If you are working with concentrates, not panning below 12 mesh is a waste of money, your money.

Without getting into a fluid mechanics discussion, I will remind you that all recreation recovery systems that you use involve water and gravity, and depends on specific gravity to sort the gold from the gangue.

A 12 mesh piece of gangue has a maximum volume of 515.63 times the maximum volume of a 70 mesh piece of gold. Gold has an approximate 5:1 specific gravity advantage over black sand gangue of the same size. Gold with a sg of around 20 and black sand with a sg of 4. So the interpolated results of mixing 12 mesh gangue and 70 mesh gold is as follows: 515/5=31, which means that each piece of gold in the concentrates that is 70 mesh or smaller, is fighting with gangue that is at most, 31 times heavier than the gold.

The only to assure that the gold will ALWAYS be the heaviest thing in the pan is to make everything in the pan the same size, then specific gravity will really go to work for you.

When I was first learning how to recover the fines, I spent a lot of time at Thermal City, I always recovered enough gold at campsites to pay for my stay there. People would spend a week there and clean up at their campsites, they would leave their tailings, and I would finish cleaning up after the left.

Classify, classify, classify. Most of the commercial gold we recover is 325 mesh and smaller.

Sam

[daubster]

Great question ywevis.

Great response Sam.

While at the recent GPOC outing I took some of
the rejects from a gold cube. I classified these
and panned the -70 to +100 and the -100 material.

The results: I found no gold in the 70-100 fraction
and 3 pieces of gold well below 100 in that fraction.

So, why did I find so little small gold?

Answer: The recovery equipment used, feed rates,
water flow and the presence of clay were not conducive
to fine gold recovery.

This does not mean that there was no fine gold in the
material. We just were not set up to recover it.

IMHO,
Bruce

[WILL-D]

When I finish dredging I like to classify thru a 1/4" and pan out the +1/4" quickly, then classify thru a #12 into a bucket to take home. The +12 can be panned back into the water quickly. I would advise panning the big stuff. I did that in the past thinking there are no nuggets around here. Kev NC changed my thinking real quick on the Catawba one day.
I then take the cons home, set up a tub with Jet Dry and pan down to the black sand throwing them into a small bucket. The blond sand goes into my driveway unless I need to sand blast something I screen to -20 mesh and save.When I finish this I spread the black sand on some aluminum lunch trays like you find in school lunch rooms. Set them in the sun to dry out. After they are dry I run a strong magnet over them to take out the magnetite. Don't touch the black sand just skim the top to pick up. If you touch the black sand with the magnet you will likely trap gold with it. Then I run them thru a series of 8" lab screens that are 16 mesh,20 ,40 ,60 ,80 and 100 mesh. I then pan each size separately. 16 to 40 in my hex pan. 60 to 100 in my small finish pan with no riffles.
When your cons are classified to these sizes and separated every thing is close to the same size and pans out much easier.
My favorite pan is the Hex pan because I can use one corner on the slick side with an up and down motion in the panning tub to clean all the black out.
This is a little time consuming but it is the only way I've found ( outside of spending $40k on a centrifuge )To get all the gold.
Any super fine gold is not likely to drop out in a dredge unless you spend a lot of time tuning your dredge, that's why I just classify no smaller than 100 mesh.

Edit to add
while I was spending so much time hunting and pecking this poor old keyboard to tell you all this, Sam posted and I think I said the same thing Sam did but with much less edukation

[Deleted]

I was wondering if you all had any video.. like a complete step by step for idiots type of video lol.. I know it's a pain staking process, but it's easier for most to watch it in action..

I searched on youtube.. can't find anyone classifying down like y'all say to do it.. they all have gimmicks, like a sluice or magnets. I would like to see it in action

[victory]

This makes me glad I saved all my tailings from my recirculating sluice box. Sounds like it's worth the effort to me.

[samburgin]

Aug 26, 2013 20:55:19 GMT -5 @ywevis said:

I was wondering if you all had any video.. like a complete step by step for idiots type of video lol.. I know it's a pain staking process, but it's easier for most to watch it in action..

I searched on youtube.. can't find anyone classifying down like y'all say to do it.. they all have gimmicks, like a sluice or magnets. I would like to see it in action

Mercury Free Recovery of Gold From Black Sands Concentrates is available from any JOBE dealer, or directly from the person who made the video, Jeff Pickett from Cotton Patch.

Sam

[Matt]

This is how I classify my con's. But I'm no pro only been prospecting for a year now.