What would cause my AR solution to only drop part of the gold powder?

[Mountain Man]

Alliedft

No, that is not what I meant. What I was saying is that in the past I have only used SMB to drop gold from my solutions and the result has been that I have not been able to recover all the gold. That being said when I was talking with Kurt and Shark about it they suggested I use copper. Either plate or powder. My comment was that I was glad over the fact the I did not discard all the solutions for the last 3 years and just stored them in 55 gal plastic drums and when I get a chance to go back to them I am going to use copper to recover the gold that I know is still in the solutions.

I am now using copper. I have tried the plate copper and the powder and I prefer the powder. It is dropping all the gold for me now. The hard part I am with now is how to separate the excess copper from the gold powder. I tried boiling the gold and excess copper powder in HCL but it did not dissolve the copper like I expected it to. Do you have any idea's or thoughts on how to remove the excess copper powder?

 

[Mountain Man]

Any thoughts on how to remove the excess copper powder from the gold powder? I am using copper powder to drop the gold and it works great but, separating the excess copper from the gold is proving to be some what difficult. I have tried boiling the copper/gold powder mixture in HCL but it is not removing all copper. I thought I cleaned it all out but my 1.6 ounce nugget is holding copper too. I don't want to smelt the rest of the powder with copper hitchhiking on my gold nugget.

Kirk

 

[GreenEWaste]

Alliedft

Do you have any idea's or thoughts on how to remove the excess copper powder?

Please forgive me if I have missed something, still fairly new to this and have yet to try my hand at doing it physically but could you not use some hot dilute nitric acid to dissolve the excess copper instead of hcl?
Regards,
Brody.

 

[Mountain Man]

The problem that I have is the size of the button. It weighs in at 1.4 ounces. The hot nitric or hcl, are not reaching the inside of the nugget do to the gold content. I am thinking that perhaps I will put it back into a new aqua regia solution and dissolve it all, then drop the gold again with smb first and then see where I am at. This technique of using copper I like very well but only if I can separate the gold from from the powder.

 

[jarlowski1]

The problem that I have is the size of the button. It weighs in at 1.4 ounces. The hot nitric or hcl, are not reaching the inside of the nugget do to the gold content. I am thinking that perhaps I will put it back into a new aqua regia solution and dissolve it all, then drop the gold again with smb first and then see where I am at. This technique of using copper I like very well but only if I can separate the gold from from the powder.

You would be on the right track but I would suggest to melt the gold and pour it into water to make smaller bbs aka. shot or cornflakes, the flatter the better. This way when you re-dissolve the gold it won't take as long, it will still take a while though. Then precipitate with smb and wash the gold really well following the wash procedures outlined in the forum.

 

[Shark]

To get it really clean it will need to be in the fresh dropped powder form. Then low boil the powders in HCl, using just enough heat to get small bubbles forming slowly. It may take several minutes to do the job as well as several times. Trying to do this to a button will only clean the outside, and not deep enough to pass a good XRF machines test.

If it were mine, I would put the button into solution in AR and fully dissolve it. The smaller the pieces, the faster it will get done. Melting and pouring it to shot or flakes will speed it up a good bit. Filter it until perfectly clear. It may take several filtering's to get it done right.

http://goldrefiningforum.com/phpBB3/viewtopic.php?f=61&t=26820

Dissolve ferrous sulfate in water With a tiny bit of HCl and heat it and the AR (separately) to a medium heat, I use the medium mark on a hot plate. Very slowly add the dissolved ferrous sulfate into the AR, it WILL boil over if added to fast, and more so if dirty. Keep the heat on until it fully drops and settles out. (don't forget to test, test and test)

Remove the excess by decanting or siphoning off the now barren of gold solution, leaving the powders undisturbed.

Once done, use water to rinse any excess acid residues from the powders. Bringing the water to a low simmering boil for several minutes, several times.

Using HCl bring the powders to a simmering boil several minutes. Remove the HCl and use water to repeat the boiling again. Keep alternating between hot water and hot HCl washs until the HCl has no color change and the water steps show no cloudiness of any kind.

If at any point I had doubts, I would start over by putting it back into solution with AR, and using another precipitant, such as SMB, sodium nitrite, oxalic acid or ascorbic acid. SMB is what I have on hand right now so that would be my choice. Then repeat all the same steps of washing over again.

Do you have a picture of the gold button your working on?

 

[Mountain Man]

Thank you for your help.
I do not have a picture but I can get one. It will be later today though. I have a Dr's appointment I have to leave for very soon. When I get back I will post a picture. When I smelted this I only did half the powder I have. The other half is still in powder form and still has copper powder in the gold powder.

I will get back on the forum as soon as I get back from the Dr.'s office.

Thanks again for your help. I value the wealth of knowledge, experience and all of your willingness to help.

Mtnman.

 

[Alliedft]

Copper powder works good unless you put to much and you end up with ,copper mixed with the gold that you dropped like you are experiencing. The best way I have found is the old way of taking copper ground bar bending it into a triangle, set it in the bucket and put a fish aquarium air bubbler in it and no excess copper will fall into the drop. It will only use the amount of copper needed. Get an aquarium air bubbler and it will do all the work for you