Denox was not done after Aqua Regia

[OroMontalban]

Best regards to all I'm new to the group and refining and would like to seek your valuable comment in the following or direct me to where I can find my answer to what I think is a typical problem.
I performed Aqua Regia in a soil sample and got positive result with Stennous Chloride on cooling. I continue with electrolysis to precipitate the gold and the process was stopped at 20 minutes with 5 Volts and 1 Amp producing a good amount of the dark brown/black precipitate. After about an hour or two I noticed that the amount of particles at the bottom of the beakers were disappearing and the dark cloud was changing from being opaque to clear. At that time I realized that I did not denox the solution so the gold went back into solution again. My question is do I denox and re perform electrolysis or denox and start again with Aqua Regia or denox and reduce the 200 mls with heat and then start the Aqua Regia process followed by denox and then electrolysis. The second question is since I'm dealing with small quantities once the precipitate is formed how long can the precipitate be saved in liquid form or do I need to dry it first then save
Thank you so much

 

[Yggdrasil]

Best regards to all I'm new to the group and refining and would like to seek your valuable comment in the following or direct me to where I can find my answer to what I think is a typical problem.
I performed Aqua Regia in a soil sample and got positive result with Stennous Chloride on cooling. I continue with electrolysis to precipitate the gold and the process was stopped at 20 minutes with 5 Volts and 1 Amp producing a good amount of the dark brown/black precipitate. After about an hour or two I noticed that the amount of particles at the bottom of the beakers were disappearing and the dark cloud was changing from being opaque to clear. At that time I realized that I did not denox the solution so the gold went back into solution again. My question is do I denox and re perform electrolysis or denox and start again with Aqua Regia or denox and reduce the 200 mls with heat and then start the Aqua Regia process followed by denox and then electrolysis. The second question is since I'm dealing with small quantities once the precipitate is formed how long can the precipitate be saved in liquid form or do I need to dry it first then save
Thank you so much

First:
Do you have an assay of the "Soil"?
Soil is a very wide and little specific term.
Next why have you chosen electrolysis (electro winning) to get your Gold out in stead of the proven SMB, Ascorbic acid, Ferrous Sulfate or Oxalic acid route?
Electro winning is not straight forward and will drop more or less all metals.

So I suggest deNOx and precipitate with SMB or Cement on Copper.

 

[4metals]

Did you do any pre-treatment of your soil sample, crushing or roasting? Do you know anything about the soil in terms of mineralization? Unless you are seeing physical gold that can be separated by density usually the gangue is panned off and then one method could be aqua regia. But on a larger scale some type of leach procedure is typically used because aqua regia is not practical on large quantities of soil that have not been concentrated in some way.

In terms of your concerns about de-noxing, when the excess nitric dissolves the metal you have electrowinned from solution it is actually consuming some of the excess nitric in the process and eventually it will de-NOx itself. Of course if you used way too much nitric, it will repeat itself for some time before the free nitric is consumed.

 

[OroMontalban]

First:
Do you have an assay of the "Soil"?
Soil is a very wide and little specific term.
Next why have you chosen electrolysis (electro winning) to get your Gold out in stead of the proven SMB, Ascorbic acid, Ferrous Sulfate or Oxalic acid route?
Electro winning is not straight forward and will drop more or less all metals.

So I suggest deNOx and precipitate with SMB or Cement on Copper.

I apologize next time I will include more detail in my question. Wife and I been doing this for a couple of yrs and since my lower back is a bit busted she brings samples in the form of rocks, sand from 3 creeks we have in the property and soil/dirt samples. We have tested rocks and sand by RF from different areas in the property and 90% of them comes up positive for Au. I was not interested in soil/dirt because our dirt has a little clay and I assumed most of the micro gold was going to be lost during panning because of the clay plus I did not wanted to spend time in developing a flocculation technique but it looks now I need to play with it meaning a flocculationprocess. OK why soil? my wife been pushing me to test soil/dirt for the longest because since we bought this property in SD mountains when she walks she can feel temperature changes from one area to another by 3 to 5 degrees she states it just feels hotter and in fact now that it's winter and it's a bit cold she tested just a couple of areas with a laser temperature gun and she was right. Don't ask me how can she do that she even smells Sulfides after it rains. Any way few days ago she comes with a small panning tray a small amount of soil/dirt so I had to doit for her effort and after cleaning the sample to remove some of organics in the sample I did not wanted to spend the time on panning the small sample and loosing what ever gold was on the panning tray. I did end up heating the sample with water and decanted just the top layer very carefully and I did this 3 times to a boil for 4 to 5 minutes hoping to release some of the gold from the clay, I read that it's not an ideal method for flocculation but gold has been known to be dropped in some types of clays. I used a 200 ml beaker and soil sample was at the 50 ml level and continued with the Aqua Regia process. After cooling the sample by placing the beaker in cold water I end up performing the electrolysis. I choose electrolysis over SMB because of the small sample SMB is not going to precipitate tiny amounts of Au i tried tat before. After electrolysis I pipette out sample from bottom of beakers and was able to see the gold and other metals either silver and bronze colors under the microscope under 10X and 40X. After I went back to check the sample the color of the precipitate changed from opaque to clear brown and the gold particles disappeared I assumed the particles when back into solution because I did not deNox the sample. I appreciate your comments and guidance and right now there's nothing I can play with since today is the third day with out electricity due to the Einsteins at our local electric company due to the wind they decided to cut the grit off in our area. Best regards

 

[OroMontalban]

Did you do any pre-treatment of your soil sample, crushing or roasting? Do you know anything about the soil in terms of mineralization? Unless you are seeing physical gold that can be separated by density usually the gangue is panned off and then one method could be aqua regia. But on a larger scale some type of leach procedure is typically used because aqua regia is not practical on large quantities of soil that have not been concentrated in some way.

In terms of your concerns about de-noxing, when the excess nitric dissolves the metal you have electrowinned from solution it is actually consuming some of the excess nitric in the process and eventually it will de-NOx itself. Of course if you used way too much nitric, it will repeat itself for some time before the free nitric is consumed.

Thank you so much for your comment.
Did you do any pre-treatment of your soil sample, crushing or roasting?
No did not maybe you can see on my previous responce ( new on the site and don't know how the threads look) all I did was to heat up the sample in water to remove some of the organic material and did not concentrate by panning since it is a very small sample but I did see microscopic gold in the microscope at 10X and 40X previous to the Aqua Regia process. My intentions right now is to develop a method to test qualitative the presence of gold and Aqua Regia sounded like the right method but on this particular sample the gold was more predominant that any other sample from Quartz, creek sand and rocks plus the small sample size and wife saying I TOLD YOU SO" I went and took it a step further but totally forgot to deNox sample. Samples previously tested contain Iron, Pyrite, Calcopyrite, Biotite mica, black sand and creeks have tons of magnetic rocks just hope we could sell the magnetic rocks.
Thank you for your help
Best regards

 

[4metals]

My intentions right now is to develop a method to test qualitative the presence of gold and Aqua Regia sounded like the right method but on this particular sample the gold was more predominant

That is a good qualitative approach not quantitative. For quantitative you need fire assays. But collecting material with a positive result for gold until you have enough for a small CLS type leach and recovery would be one option. Check out Action mining for CLS leaches and bucket sized electrolytic recovery cells.

and wife saying I TOLD YOU SO"

My best innovations come when working in the greenhouse and my wife saying "I told you so" to which I always respond "Yes dear". Makes for a good working relationship, don't knock it!

CLS leaching manual

5 gallon electrolytic recovery system for CLS leaches