GOLD PRECIPITATION WITH MILKY WATER AS RESIDUE

[Baktanoosh]

Hi dear members. i am here to seek expert opinion about the following images. a friend of mine sent me these pictures. the story is that in picture 1, one Gram of gold was dissolved in aqua regia ( 10 ml nitric acid, 20 ml hydrochloric acid), then evaporated the mixture and then 3 times 5ml HCl was evaporated and then diluted with pure water. and were reduced with an unknown reagent. In picture 2 & 3 you can see the gold being precipitated out with a milky solution left behind.
If anyone have knowledge about that specific kind of reducing agent which have reduced the gold particles as reddish brown precipitate with milky water then please help me figure out what actual reagent did he use.

 

[Yggdrasil]

Hi dear members. i am here to seek expert opinion about the following images. a friend of mine sent me these pictures. the story is that in picture 1, one Gram of gold was dissolved in aqua regia ( 10 ml nitric acid, 20 ml hydrochloric acid), then evaporated the mixture and then 3 times 5ml HCl was evaporated and then diluted with pure water. and were reduced with an unknown reagent. In picture 2 & 3 you can see the gold being precipitated out with a milky solution left behind.
If anyone have knowledge about that specific kind of reducing agent which have reduced the gold particles as reddish brown precipitate with milky water then please help me figure out what actual reagent did he use.

Welcome.
I see no Gold in there.

What kind of Gold did he dissolve?
Did all dissolve?
What about asking him what he used?
The AR was made the wrong way, HCl to cover it then Nitric by the drop.

Here is something to study if you are going to use chemicals.


1. Read C.M. Hokes book on refining jewelers scrap, it gives an easy introduction to the most important chemistry regarding refining.
It is free here on the forum: Screen Readable Copy of Hoke's Book
2. Then read the safety section of the forum: Safety
3. And then read about "Dealing with waste" in the forum: Dealing with Waste

Suggested reading: The Library

https://goldrefiningforum.com/threads/gold-refining-forum-rules.31182/

 

[Baktanoosh]

Welcome.
I see no Gold in there.

What kind of Gold did he dissolve?
Did all dissolve?
What about asking him what he used?
The AR was made the wrong way, HCl to cover it then Nitric by the drop.

Here is something to study if you are going to use chemicals.


1. Read C.M. Hokes book on refining jewelers scrap, it gives an easy introduction to the most important chemistry regarding refining.
It is free here on the forum: Screen Readable Copy of Hoke's Book
2. Then read the safety section of the forum: Safety
3. And then read about "Dealing with waste" in the forum: Dealing with Waste

Suggested reading: The Library

https://goldrefiningforum.com/threads/gold-refining-forum-rules.31182/

Thanks for nice suggestions & recommendations. Actually the gold was filtered out and in last image the leftover solution with milky tinge can be seen. yes all the gold ( 24 c) was dissolved you can see in the attached file which was unintentionally failed to be uploaded in previous post. He refused to tell so that's why I am here and eager to know what did he do with it.

 

[Lino1406]

One possibility is stannic oxide from using stannous chloride as a reducer

 

[Yggdrasil]

Thanks for nice suggestions & recommendations. Actually the gold was filtered out and in last image the leftover solution with milky tinge can be seen. yes all the gold ( 24 c) was dissolved you can see in the attached file which was unintentionally failed to be uploaded in previous post. He refused to tell so that's why I am here and eager to know what did he do with it.

Hmm.
This image indicates a lot of undissolved something, which means a significant portion of the Gold could have cemented out.


And this has a lot of black stuff still in the bottom.
So things do not quite add up.


Any special reason he do not want to tell you what he did?

Do you have a picture of the Gold?
Before and after preferably.
What did he dissolve? Nuggets, karat or something else?

 

[Baktanoosh]

One possibility is stannic oxide from using stannous chloride as a reducer

I also have a feeling that he might have used SnCl2 as reducing agent but how to justify that milky solution? what it could be?. if someone could share his experience with tin chloride in gold reduction would be much appreciated.

 

[Baktanoosh]

Hmm.
This image indicates a lot of undissolved something, which means a significant portion of the Gold could have cemented out.
View attachment 57837

And this has a lot of black stuff still in the bottom.
So things do not quite add up.
View attachment 57838

Any special reason he do not want to tell you what he did?

Do you have a picture of the Gold?
Before and after preferably.
What did he dissolve? Nuggets, karat or something else?

the images might be failing to elaborate much about the whole process but he told me the gold was completely dissolved in aqua regia. in last step he decanted out the precipitated gold and was left with the solution only. he used a piece cut from a pure 24 karat gold strip. sorry i dont have the gold picture. image 1 was taken right when he started droping that solution of reagent on aqua regia and you can see the reaction was quite spontaneous. May be he just want me to explore what it was but how can i try with every possible reagent(s). i dont wanna make things messed up but i'm eager to learn from the community as well.