problem with refining gold

[amt]

hello miners friends
I have two problems refining the gold one is that when done sulfamic acid to neutralize the nitric acid reaction does not make me, I tried it with sulfamic acid and urea and neither does my reaction.
then I made sodium metabisulfite and if it reacts and gets dark solution.
I wash and dry after the gold dust but I see q of the dust gets brown one yellow and one black part.
then made the dust in the furnace and heat up, but noted that begins dating a kind of orange pulp when hot with gold and black and hard when cooled, after 3 hours heating and removing the paste that I form Nugget Golden .
I could say some mining because the solution does not precipitate me when I made the sulfamic acid?
and it may be that dark paste that prevents me form the nugget in a reasonable time?
the paste has left me both gold dust extracted from printed circuits and the plates extracted from mobile phones.
A greeting and thanks to all

 

[amt]

Photo of the cursi le with this black paste

 

[bswartzwelder]

What were the results after you tested the solution with stannous chloride?

 

[Lino1406]

No reaction with sulphamic acid/urea - no excess of nitric/chlorine was left

 

[amt]

I did not test, but in this crusible had 1.9 grams of gold but had to be three hours by heating the crusible so that the nugget was formed because of the black paste that prevented nugget is not formed of where the black paste exits.

lino1406. OK thanks

 

[butcher]

amt,
I cannot understand much of what you have written, most likely because of the language differences, and things getting lost in the translation.

It can be hard to tell if you have excess nitric acid in solution, sometimes when adding HCl acid we may see the brown fumes of the nitrogen oxide, and oxygen vapors forming NO2 gas, or see the brown fumes of the nitrogen dioxide gas, and other times we may not know for sure if we have excess nitric or nitrates in solution.

The stannous chloride test can be helpful here, to not only verify if gold is in solution, but also to see if we can reduce the gold, the reduction of gold by the tin solution, the purple reaction, can helpful to verify a lack of free nitric acid in solution, that could hinder the reduction of gold by the sodium metabisulfite, or other gold reducing agent.

You may not see a reaction when adding the sulfamic acid, so it may be hard to tell if anything is happening there or not.

As you learn more and get better at recovery and refining you will learn how not to overuse the acids, the better you get at using just as much as needed, the easier it is in later stages of recovery or refining.
There are several ways to remove excess nitric from solution, learning these are very helpful, the best is not to overuse nitric in the first place.

It looks to me, from your picture your gold was not refined, looks like a lot of base metals were involved in the melt, I do not know what you were heating the crucible in (type of furnace), or if you were using a torch (and what type of torch and gas...), the crucible will absorb a lot of heat, and if you were not using a furnace you may not have had a large enough heat source, to get the gold melted, a good choice for melting refined gold is a dish and a good torch.

I also noted you had a lot of borax, or other flux involved (this and the base metals formed the slag glass).

My suggestion is to keep studying the forum, learn to eliminate the base metals to get your gold more pure before refining it, learn more how to use the acids without overuse, and when you do refine the gold, refine it twice. learn more about the melting process and what works best.

Basically just keep working hard in your studies, there are many tricks of this trade you have yet to learn, welcome to the forum.

 

[amt]

Butcher thanks very much, i am going to learn to much!!