Alguém pode ajudar AR travada

[Simonides]

Olá boa noite , sou novo no fórum, fiz alguns processos e a maioria deu certo, tenho estudado bastante. Porém aqui no Brasil não temos muito conhecimento do processo de refino. Iniciei um processo de CPU cerâmicos 500g chapeados, minha água regia AR foi 200ml de acido clorídrico 37% , HCI + 35ml acido nitrico 53%, filtrei bem a solução, fiz Dnox com sulfamico procurando neutralizar acido nítrico. Adicionei gelo a solução pois estava bem verde no pensamento de precipitar algum metal de base quando coloquei o gelo adicionei sulfamico junto, precipitou um pó preto mais muito pouco. No outro dia adicionei mais sulfamico pequena quantidade... esqueci a solução 90°c , coloquei metabissulfito MBS, a solução continuou da mesma cor um esverdeado claro :roll: sei que a solução estava bastante contaminada com metais diversos. Não estou desesperado pois vou conseguir recuperar com ajuda dos amigos. Tenho que traduzir o livro de Hoke pois só falo português :wink: O que deveria estudar para concertar esse erro? Teste de cloreto estanhoso deu tom de marrom , mas depois de um tempo apagou. O que posso fazer para recuperar a solução, quais seriam os primeiros passos além da leitura.

Obrigado Simonides Brasil

 

[butcher]

The black powder, may be your gold.

The Brown reaction from testing the solution with stannous chloride, could be a brown reaction of copper, not a purple reaction of colloidal gold.

 

[Simonides]

my friend the black powder precipitated with sulfamic and ice, as it can be gold I think it could be iron or copper. However, the black powder did not react to the nitrile. sulfamic acid with ice precipitating gold? I believe it is unlikely, but you may be right.
Thank My grind.

 

[Simonides]

Thank My frend

 

[butcher]

That is assuming you even had gold in solution to begin with.

In the picture, I see a beaker full of base metals, so I am assuming you are trying to recover gold from those base metals.
Then you speak of using aqua regia (which normally used in a refining process, and not a good choice for recovery of gold), which leads me to believe you are trying to recover gold using aqua regia, which is normally not a good idea and something someone unfamiliar with recovery and refining would attempt.

Even if you seen the acids dissolve the gold with your own eyes, it does not mean the gold is in solution, as if there were any remaining metal more reactive than the gold, then that metal can displace your gold in solution.


Now how do you know you even had gold in solution?
Your brown reaction of the stannous chloride test is not showing any gold in solution, a violet color would have given you a clue that you had gold in solution. So at this point you have no proof that there was gold in solution and the gold may still remain with the scrap material you leached a beaker of base metals from.

 

[Simonides]

Hello my friend I assume that the gold is in the solution, because the material left the scrap completely clean. Before wrongly adding water the solution was very viscous and yellow, the tin test I did earlier indicated gold turned purple, what do you think? the solution is heavily contaminated with heavy base metals free in the solution, this may also have hindered precipitation. gold has to have for the quality of the large CPU material of the telephone tower. Thank you for your help .

 

[butcher]

If you done the stannous test and it turned purple (indicating gold in solution) then later done you again done the stannous test and the test was absent of the violet color, then you do have an indication you previously had some gold in solution.

Base metals even if are hidden from your sight ( under layers of fiber glass, plastics, or inside layers of ceramic, inside chips...) these are the places your gold can also cement back onto the remaining metals.

Unless all of the base metals are dissolved completely when leaching the electronic scrap, and the gold remains in solution having no other hidden elemental metal left to trade places with hidden inside the electronic components, you may have left some gold behind.

You used almost enough nitric acid to put an ounce of gold into solution, although you did not have enough HCl to do so.

I would put a bar of copper into solution and heat it, stirring the copper, collect anything the copper produces (black powders), then add iron to the solution to recover copper and a few other toxic metals, then treat the solution for waste.

Any salts or powders recovered can then be refined, Start with washing the salts, some will be water soluble, since some will be chloride salts (you do not want to wash them in nitric as that would dissolve any gold), so washing the salts in HCl will dissolve those soluble in that acid leaving gold insoluble.

Silver and lead will also be insoluble as chlorides, although boiling hot water washes will help to remove the lead chloride from the other salts or metals, if kept hot while letting the fluffy insoluble silver chloride time to settle before decanting the clear lead chloride wash water, moving that wash water to another vessel to cool and much of the lead to precipitate as needle like crystals this water can then be reused with heat to dissolve more lead chloride in another wash using the same water (saving us on creating volumes of waste solution contaminated with lead and other toxic metal salts that we need to deal with responsibly).

Basically after washing your gold, you may notice the little bit of black powder turning more of a brown color.
Now you can add about 4ml or more of HCl to every of powder you have remaining.

From here, you could use sodium hypochlorite (household bleach) to dissolve the gold, making things more simpler to remove oxidizer), or drops of nitric and heat, to dissolve gold and other base metals leaving silver...

Basically everything you need to know to recover your gold from this mess can be found when you study how we deal with waste and recover gold or other values in that process, or how to deal with your stock pot...

 

[Simonides]

THANKS a lot my friend certainly helped me a lot this mistake is already serving as a learning experience for me, I will dedicate myself to this recovery of the solution and I will learn more thanks for the class I hope to help you someday.

 

[butcher]

Study these for a better understanding.

Dealing with the waste, the elephant in the room.

Beginning with the experiments in Hokes book, giving you a better understanding of how metals react in these acids, while studying her book which underlays the principles of recovery and refining.

Learning about the basic principles of how to displace metals from solution using a more reactive metal like copper or iron, what happens and how the reactivity series of metals works.

Study the difference in recovery of gold and refining of gold, which are normally two very different operations.
these should help to get you pointed in a direction to better understand what we have been discussing.

 

[Simonides]

THANK YOU SO MUCH for the guidance I will follow these steps for sure and learn more and more.

 

[Simonides]

Before the problem arose, the solution was exactly like this.

 

[butcher]

Colors although somewhat helpful, do not really tell you much at all, the yellow color could be from many things, not necessarily gold.

Gold can tint a solution yellow, or even red, but a yellow solution can come from other metals like iron, iron can fool you looking like gold in solution, or looking like gold powders, color may give some clues, but it will not tell you which you have.
Hokes page 100 gives you a couple of different tests that tells you how to determine if the yellow comes from iron, and your stannous will tell you if you have gold in solution.

Iron can range from yellow, green to brownish red, depending on its valence it can be of several different colors.

Seeing the yellow solution turn green ( under different oxidation states of the solution) make me suspect iron.
At first I thought the green looked like it maybe from a source of copper, but if it came from a yellow solution I now think Iron may be giving you the colors you see, well testing is always better than guessing.

 

[Simonides]

Identifying the predominant metal that is excessively contaminating the solution will help me to try to eliminate it so that I can precipitate. I will separate a little of this solution and make possible tests, I thought about evaporating a little of this excess water and leaving the solution more consistent or cement with a copper bar and treat the residues, one by one that is precipitating. washing, cleaning, attacking HCI when necessary. Thanks for the help, my friend, but I still believe that it was not just iron, most of it was gold because before entering with regular water I attack with nitrite in the leaching materials before using AR, I believe that there was still a little iron and copper . Thanks for the help I will continue with the tests. Thank