Excessive black sand

[exhail]

The creek that I currently have access to has some reasonable gold in it. Most of the gold is ultra fine, around 200 mesh and down. There is the odd small flake and small nuggets about the size of a grain of raw sugar. The really fine stuff there is plenty of but the problem is the amounts of black sand. To give you an idea of what I mean is if I was to fill a 10L bucket with material classified down to -4mm the bucket would be 3/4 black sand. With this much black sand it makes the gold very time consuming to recover.

I have just done a run with my Keene A52 which has mm but have found that it looks like all the gold dust didn't stick in the sluice. I tried different water speeds but if I went to slow the riffles wouldn't clear at all and if I increased the flow the riffles cleared but didn't retail the fine stuff blows out the back of the sluice.

[Deleted]

Maybe a blue bowl or gold wheel?

[dezman]

Im surprised the keene missed the gold when you tried changing settings.
Maybe a mercury riffle like the old timers did, if your seeing a lot of fine
gold then my guess thete is just as much gold that is to small to see with with
our eyes.
I did try a new riffle setup yesterday based on the old time way of placing
them 2" apart! 14in all, however my water pump was to slow to push unclasifired
mattrial though. Thought i had angle to high to catch the flood gold i was chasing,
i was very surprised at how much fine gold it held!
Hmmm,that black sand must be clogging the riffles in yours. Its heavy
stuff and i find it hard to pan it out, knowing Im losing gold i cant see.

[exhail]

I am thinking of putting another sluice that is 6 foot long behind it to try to catch the small stuff by giving it more time to settle.

I have never seen a creek with so much black sand it makes for an unusual issue.

[exhail]

thanks for the replys

[redmanti]

Gold Hog mats handle the black sand.

Far less black sand on clean ups.

[donnybrook]

The Gold Hog mats do work well. I have heard others say this. Also try a gold wheel for cleaning up. Once you get the adjustments right it should be a piece of cake. Make sure you are not throwing silver out. It is normally found as a black oxide. If you are sure it is not magnetic and you know someone with a furnace,smelt it. But add flour to your standard flux (30 parts borax, 20 parts soda ash, and another 30 parts flour) which is carbon to convert the oxide to metal.
donny

[rc62burke]

Hey Donnybrook
In your flux recipe where you mention "parts" this unit of measure, is it say measured in grams or in teaspoon or cups?
In the above mix what part black sand?
cheers
Lee

[rc62burke]

Hey Donny
Do you have any flux mixes for smelting tin?
cheers
Lee

[donnybrook]

Lee, Re fluxes parts and weights. What is meant by parts differs from weights. For example if you had ten cups of gold you would add 3 cups of borax and two of soda ash. With pure gold when I smelt it I only add borax (about 50%). In respect of weights of fluxes; for example silver chloride. If you had 100 grams of silver chloride you would add 2 1/2 parts by weight (250 grams) of soda ash. This is because silver chloride is in an atomic form it takes on a chloride (several). What happens here is the chloride factor is expelled as a white plume or salt (sodium) and the silver converts to a pure metal. If you don't have the correct weight you will lose silver.

You drop your silver chloride as a white curd from nitric with salt or a small amount of hydrochloric acid. I prefer salt. Just dissolve a few spoons in warm water and add. Keep adding until no more curd forms. Filter this off with a plastic food sieve and wet tissue papers. Dry in your corning ware dish. If you want to produce sterling silver take the curd up with 30 %ammonia (bought from cleaning suppliers). It should go blue. Filter again and add a few drops of nitric acid (whatever is required) and it will drop your silver again. Then filter,dry and weigh. Also ensure it has been thouroughly washed with distilled water. Not tap water which contains chlorine. Add 2 1/2 parts by weight of soda ash then smelt. Presto silver.

Concerning flour it is a carbon. You can use charcoal also a carbon but flour is simpler. Add 30 parts. I have used this method to recover silver in its native oxide form (black) and also with old burnt x-ray ash (the older type) and photographic films.

With some tin it can be an oxide. For example tin can look like small gemstones (party stone or cassiterite). Add flour as above with the same borax and soda ash. If it does get a bit thick add more borax to make it slightly fluid. Flour will not harm your flux mixture. It pays to be careful. If you were trying to recover platinum in a graphite crucible using silver as a carrier you would not use flour as you would finish up with a loss as platinum carbide.

[rc62burke]

Hey Donny
Thanks for that info, a lot to learn.
How do you know all this stuff?
Do you have any books you can recommend?
cheers
Lee

[Flying Scott]

Black Sand. I have used mercury in a potato, also find that if you use an air brush to blow away the sand is ok, or simply use a drinking straw, a great pastime on a Sunday afternoon to whittle away the hours.
Flying Scott

[thedigger]

Hi Lee
There is a book "Recovery and refining of precious metal" by C.W.Ammen
It has a lot of information,I bought it in the US,might find it on the net.

Regards Frank

[rc62burke]

Hey Frank
Cheers for that, I will check it out.
Lee

[rc62burke]

Oct 10, 2013 20:30:59 GMT 10 Flying Scott said:

Black Sand. I have used mercury in a potato, also find that if you use an air brush to blow away the sand is ok, or simply use a drinking straw, a great pastime on a Sunday afternoon to whittle away the hours.
Flying Scott

Hey Scott
I have tried many a method including the use of a feather to wipe away the black sand when it is laid out on white paper dry, the biggest problem is it takes so long.
cheers
Lee