Purple mud and solution

[Yggdrasil]

When you neutralize a solution, you add acid or base until the PH is 7, it is then neutral.
You can not neutralize one acid alone in a mix, when you mix them you create a complex, PH wise and what you do to the complex will affect both.

If you are deNoxing a solution as we call it, you have a few options:

Urea will form UreaNitrate and such "lock" some of the free nitric/Nox but the nitrates are still there.

You can evaporate the liquid to a syrup and add more HCl a couple of times.

You can use Sulfamic acid and it will convert the nitric to Sulphuric acid (killing two birds with one stone) which is the preferred method in here for the time beeing.

Or you can cement out the PMs with a copper bar (or copper powder as you have done), which may be the best method for dirty or diluted solutions since it will consume the free nitric in the process. Make sure you have good circulation.

If you already have a clean solution you may add a gold button to consume the free nitric.


The precipitation will be a brownish cinnamon colored mud if clean, to dark brown mud if its dirty.
This is your actual gold. :wink:

As to the purple mud, I hope what has been proposed already will fix your challenges.

Edited a typo

 

[Mountain Man]

When I said I was going to neutralize the solution I am speaking of the nitric. I still have not done anything with all the purple mud that I have. I can say with confidence that I feel like the gold from the materials I processed must be trapped in the purple mud or is the gold and something is trapped in with it causing it to be purple. Otherwise the yield for the material I processed is way lower than expected.

This particular batch is a 6 lb batch of military grade gold plated fittings and connectors. I used reverse electrolysis to strip them. The black mud yield was very high. I followed the instructions exactly for letting it sit for 24 hours. Actually more than 24 hrs. I then rinsed many multiple time and washed to remove the sulfuric residue. Once I reached the point where I felt it was truly washed and had no sulfuric residue left I the subjected it (black mud) to AR solution and dissolved it all. I then neutralized the remaining nitric with urea until the ph was right. Once that was done, I then took the solution and filtered it to remove any urea residue and any other foreign materials until the solution was clean. At this point I added copper powder to drop the gold. I let is set overnight and the next day I was very happy to see the amount of mud on the bottom of my glass container. I siphoned the excess water off and was ready to start my final washing and saw that all the mud that had dropped with the copper powder was purple. The excess copper was normal colored but the gold mud had turned purple and still is to this day. I have not gone beyond this point. Still needing your expertise to
save the gold. I have not done anything else to it except clean water washes. Lots, of washes. I still have a large amount of purple mud. The glass jar is 12 inches across the bottom of the jar so it is a big jar and has in upwards of 1/2 inch at least that is settled on the entire bottom of this jar. There is a lot of purple mud or gold and something I can not identify. I am at a loss but I never give up.

Please understand that I value all of your suggestions, ideas and experience. I read all your comments over and over and value every one of them. I know, more than anyone that I have a lot more to learn to become expert in the venture of mine, but I am not and have never been a quitter.

Thank you All For Your Willingness to Help.
Mountain Man
Kirk

 

[butcher]

Could it be silver chloride? what happens when you take a small sample of the mud in a test tube and add HCl does the violet color go white or the violet color goes away...?

A small sample in ammonia, and then that solution acidified with HCl, is the solution colored blue with copper or other, do the powders or some dissolve in solution, does the mud change colors, does acidifying the solution produce a change in color, milky solution, or a precipitate?

We can continue coming up with different ways we can test a solution, but these will probably give you clues to what you are or are not dealing with.

 

[Mountain Man]

So, I took a small sample of the purple mud today and put it in a cup or so of water. Keep in mind that this is after many many rinses. I then mixed a very small amount of HCL and Nitric acid. Less than a 1/2 cup combined and poured the AR solution in with the small amount of purple mud. Small meaning a teaspoon full.

Anyone care to guess on what happened? Maybe I should wait to see your answers and see what you all think. No, just kidding, but here is what happened.

It dissolved the purple mud. The solution turned a canary yellow and was transparent however I could see a small amount of suspended very light colored white cloud. So clearly I have something in the mix that I did not get out in the rinsing process. Then after that instead of using urea to denox it I used the copper powder to denox it and so I slowly added small amounts until the nitric was used up and I know it was used up because the gold started dropping due to the copper powder. When the copper stopped denoxing the solution the gold started attaching to the copper powder and so I kept adding copper until the solution tested negative and the copper was starting to accumulate on the bottom without any gold.

So, I still don't know what is causing it to turn purple but I am thinking that Kurt may have hit it when he said stannic tin being present. He specifically said to look for a white cloud that will be hard to spot if I am not looking very closely for it.

However, it may still have other factors that have been mentioned for example silver chloride, direct sunlight, and others as well. I can not discount the fact that when I process a batch and it is time to let it settle I typically set the container I use which is clear in the window sill of my gold recovery building.

So, my friends, That is my report as of today. I have also been trying the other suggestions that have been mentioned and do not and will not disregard your expertise and comments so please keep them coming. I am more than appreciative for all of your willingness to share your time, experience and offer to help with my apparent slow learning process. It seems the more I do this, the more I realize just how little I know.

Thank you all again. I sincerely mean it and if I have not commented on some of your suggestions it does not mean that I have not read them. I read every word of every one of your comments, multiple times before I make any kind of decision on what to try first.

Sincerely,
Mountain Man
Kirk