Issues with neutralizing nitric acid in my aqua regia solution

[Mostafa Ali]

I have quartz stone and I'm sure it contains gold but I'm unaware of the percentages of the minerals in it. I crushed the stone to small granules. I cleaned the crushed resultant using nitric acid with heating then I executed another cleaning process using normal tab water. Then again I cleaned the mixture with sulfuric acid then washed the mixture with water.
Finally after all this cleaning process, i prepared my aqua regia solution using the percentage of 1 nitric acid to 3 HCL in a glass container and then added my mixture of crushed granules to the glass container of aqua regia solution and then I heated the solution just before the solution boils, let the solution cool down a bit then heat again.
After the dissolving process, i filtered my mixture to remove the impurities and have a clean aqua regia.
Then I neutralized the nitric acid in the aqua regia using urea with heat.
My issue is that when I neutralize, the solution takes up so much urea until the reaction stops.
Then I try to precipitate using SMB but there is no gold precipitation and the color of the solution dims.
Then when i leave the solution and check it after a day, the solution's color sometimes lightens up a little bit.
Can you please advise us on what we could be doing wrong in any of the steps above?

 

[Yggdrasil]

I have quartz stone and I'm sure it contains gold but I'm unaware of the percentages of the minerals in it. I crushed the stone to small granules. I cleaned the crushed resultant using nitric acid with heating then I executed another cleaning process using normal tab water. Then again I cleaned the mixture with sulfuric acid then washed the mixture with water.
Finally after all this cleaning process, i prepared my aqua regia solution using the percentage of 1 nitric acid to 3 HCL in a glass container and then added my mixture of crushed granules to the glass container of aqua regia solution and then I heated the solution just before the solution boils, let the solution cool down a bit then heat again.
After the dissolving process, i filtered my mixture to remove the impurities and have a clean aqua regia.
Then I neutralized the nitric acid in the aqua regia using urea with heat.
My issue is that when I neutralize, the solution takes up so much urea until the reaction stops.
Then I try to precipitate using SMB but there is no gold precipitation and the color of the solution dims.
Then when i leave the solution and check it after a day, the solution's color sometimes lightens up a little bit.
Can you please advise us on what we could be doing wrong in any of the steps above?

Welcome
First of all, I have deleted your other post as we do not allow double posting.

Since you are sure you have Gold, what do the assay say?
I do assume you have an assay as that is the only way to know that you have Gold?

How did you concentrate it?

And the next wrong is that you really do not use AR or other acids on ore.

 

[Mostafa Ali]

Welcome
First of all, I have deleted your other post as we do not allow double posting.

Since you are sure you have Gold, what do the assay say?
I do assume you have an assay as that is the only way to know that you have Gold?

How did you concentrate it?

And the next wrong is that you really do not use AR or other acids on ore.

Thank you for your response. To clarify why I’m certain there’s gold:
1. After dissolving the material in aqua regia, I tested the solution with **stannous chloride (tin chloride)**, and it turned **black**, indicating the presence of gold.
2. I can **visibly see gold veins** within the quartz stone.

Could you advise what might be going wrong in the precipitation step based on this?

What do you mean by “how did you concentrate it?”?
I did no concentrate anything

 

[4metals]

Welcome to the forum.

What you do not mention is the quantity of crushed quartz you processed or the size you reduced the pieces to. Your method of using aqua regia is good to give you a stannous chloride indication of gold but if your sample processed was too small, the recovery process is difficult. Some information of the quantities you tested as well as the potential quantities you have to process will give us the information needed to help you proceed properly.