Thiosulfate leach

[budzag]

Hi Guys, I am new here this place looks like a great place to share ideas and gain knowledge.
Anyhow I have a issue and would like to know if anyone could help.

I have leached my heavy gold cons using Sodium Thiosulfate and water mix. I had left them in the glass container for approximately 2 weeks stiring every so often and adding more crystals
Every few day to make sure the leach was strong. After the 2 weeks I filtered the solution using a coffee filter and i could see the colour had a slight yellow orange hue so I am assuming the gold an sliver salts had leached into solution? Now I have been trying to find a way to cement the gold out of the mix as it is not hydo or nitrc acid as water was used with the Thiosulfate. I am trying to stay away from acids if possible?. I was thinking electrowinning the solution with to stainless steel sheets. One as the anode an 1 as cathode would this work? I have attached a pic of solution does this look like gold particles floating around? I also put a piece or aluminum in the solution as it though it might drop the gold haha.

Any help would be awesome on trying to recover the metals

 

[Yggdrasil]

Hi Guys, I am new here this place looks like a great place to share ideas and gain knowledge.
Anyhow I have a issue and would like to know if anyone could help.

I have leached my heavy gold cons using Sodium Thiosulfate and water mix. I had left them in the glass container for approximately 2 weeks stiring every so often and adding more crystals
Every few day to make sure the leach was strong. After the 2 weeks I filtered the solution using a coffee filter and i could see the colour had a slight yellow orange hue so I am assuming the gold an sliver salts had leached into solution? Now I have been trying to find a way to cement the gold out of the mix as it is not hydo or nitrc acid as water was used with the Thiosulfate. I am trying to stay away from acids if possible?. I was thinking electrowinning the solution with to stainless steel sheets. One as the anode an 1 as cathode would this work? I have attached a pic of solution does this look like gold particles floating around? I also put a piece or aluminum in the solution as it though it might drop the gold haha.

Any help would be awesome on trying to recover the metals

Welcome to us.
What kind of research did you do before you decided to go for Thio Sulfate?
It is one of the things that haunt us from time to time.
It puts Gold into solution all right, but it do not want to let it go.
Are you sure the Thio/water way is the way to go?
Do you even know if it works?
I did one little search and it seems it is slightly more involved than Thio/water, here is a link to one article.
https://www.sciencedirect.com/science/article/abs/pii/S0892687500001722

Anyway since you are already using chemicals I want you to study these links:
We ask our new members to do 3 things.
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: https://goldrefiningforum.com/phpBB3/viewtopic.php?f=54&t=19798
2. Then read the safety section of the forum: https://goldrefiningforum.com/forums/safety.47/
3. And then read about "Dealing with waste" in the forum: https://goldrefiningforum.com/threads/dealing-with-waste.10539/

Suggested reading:
https://goldrefiningforum.com/forums/the-library.101/
https://goldrefiningforum.com/threads/when-in-doubt-cement-it-out.30236/
https://goldrefiningforum.com/threa...le-read-this-before-you-post-about-ore.33333/


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

 

[budzag]

Hi Yggdrasil,
Thank you for your reply.
I have done a little bit of research on using sodium Thiosulfate as the leaching solution. I wanted to go down the greener way rather than using acids ect. I do also have copper sulfate crystals but I was going to try without using those first as it would be one less thing I would have to deal with. I am not fussed about the leach rate as time is not a factor. As I understand copper sulfate is used to speed up the leaching rate. I think I will try electrowinning the solution onto stainless sheets. I was going to try pour Zinc powder into the solution to drop the gold but not sure if that only works in acid not a water concentrate? Also I am having issues trying to purchase zinc powder as it is classed as a dangerous goods and I am not approved handler and not registered.

Thanks
Aaron

​

 

[Yggdrasil]

Hi Yggdrasil,
Thank you for your reply.
I have done a little bit of research on using sodium Thiosulfate as the leaching solution. I wanted to go down the greener way rather than using acids ect. I do also have copper sulfate crystals but I was going to try without using those first as it would be one less thing I would have to deal with. I am not fussed about the leach rate as time is not a factor. As I understand copper sulfate is used to speed up the leaching rate. I think I will try electrowinning the solution onto stainless sheets. I was going to try pour Zinc powder into the solution to drop the gold but not sure if that only works in acid not a water concentrate? Also I am having issues trying to purchase zinc powder as it is classed as a dangerous goods and I am not approved handler and not registered.

Thanks
Aaron

​

If you are going to use Zinc it has to be either acidic or caustic.
There will be no energy to drive the ion exchange unless it has a pH that is sufficiently off center (7).
Did you read the paper I sent a link to? They used Ammonia if I'm not mistaken.
We have many threads on the forum regarding Thio Sulfate leaching and I think that most if not all are in the "help me" category.
Which means they are failed and most are not resolved.
Regarding "green" the moment a leach has dissolved metal ions it no longer are "green" and will be considered toxic to life.

 

[budzag]

Ok thanks, I guess that's what the copper nitrate was used in studys for as it would cause the solution to turn more acidic and then the zinc would drop the gold I am guessing? The copper nitrate also degrades the Thiosulfate more rapidly. That's what the Ammonia is ment to combat. Bugger I not wanting to use Ammonia. I might try add some copper sulfate if this doesn't cement to the stainless. I am aware that any solutions containing waste/metals are toxic and will be delt with proper procedure.

 

[Yggdrasil]

Ok thanks, I guess that's what the copper nitrate was used in studys for as it would cause the solution to turn more acidic and then the zinc would drop the gold I am guessing? The copper nitrate also degrades the Thiosulfate more rapidly. That's what the Ammonia is ment to combat. Bugger I not wanting to use Ammonia. I might try add some copper sulfate if this doesn't cement to the stainless. I am aware that any solutions containing waste/metals are toxic and will be delt with proper procedure.

Why not go for something that actually work?
As I said, we have had this discussion multiple times in the past and I can't remember it going well any of those times.

 

[Yggdrasil]

Ok thanks, I guess that's what the copper nitrate was used in studys for as it would cause the solution to turn more acidic and then the zinc would drop the gold I am guessing? The copper nitrate also degrades the Thiosulfate more rapidly. That's what the Ammonia is ment to combat. Bugger I not wanting to use Ammonia. I might try add some copper sulfate if this doesn't cement to the stainless. I am aware that any solutions containing waste/metals are toxic and will be delt with proper procedure.

Have you found any reference what so ever that any of the major companies using this?
That is what we consider a litmus test in this community, if the major companies use it, it works.
If not, there are some snags to it.
Price, dealing with waste and practical use primarily.

 

[budzag]

Have you found any reference what so ever that any of the major companies using this?
That is what we consider a litmus test in this community, if the major companies use it, it works.
If not, there are some snags to it.
Price, dealing with waste and practical use primarily.

 

[budzag]

The main reason the company's don't use it is the rate of Thiosulfate consumption i think I read somewhere it was 24kgs to the ton of ore so it is not really viable for the big companies at this stage. There is alot of research being put into this as it could potentially faze out cyanide use as a cleaner method. There is a issue with recovery on the activated charcoal for the big companys. But for the small scale miner it could work better price wise as I am only dealing with the heavy cons so there are not tons or ore to deal with. The big problem as you have been saying is finding a recovery method that works and not overly complicated

 

[Yggdrasil]

The main reason the company's don't use it is the rate of Thiosulfate consumption i think I read somewhere it was 24kgs to the ton of ore so it is not really viable for the big companies at this stage. There is alot of research being put into this as it could potentially faze out cyanide use as a cleaner method. There is a issue with recovery on the activated charcoal for the big companys. But for the small scale miner it could work better price wise as I am only dealing with the heavy cons so there are not tons or ore to deal with. The big problem as you have been saying is finding a recovery method that works and not overly complicated

If the concentrates are good it may be more sensible to smelt them.