# Half gold chloride didn't drop gold



## chrisjames (Aug 18, 2015)

Hi guys,

I think I need a bit of help if possible.
I have been refining various k jewellery and have followed instructions to the letter. All has gone fine apart from the final gold drop. I had a large jug of gold chloride which I allowed settle for 24 hours before filtering (using coffee filters as I had no lab ones) I then divided the solution into two coffee pots to precipitate. This is where I messed up...
I put a spoonful of smb in a cup of distiller water and added it to pot one then did the same to pot two, however added two tea spoons of smb (I think) the first pot started to drop immediately but the second one only partially dropped then stopped, the solution is still yellow where as the first pot is mostly clear minus some blue from copper (I did enquart however there was some 22k gold that I didn't bother with so assume that's where the copper came from)
The solution has around 40g of gold in so I'm keen to get it dropped.

I've read hoke previously and trawled smb questions but can't find this exact question asked.
I've left the solution for 24 hours but it still hasn't changed. My first thought was to lightly boil the solution and reduce it as I put some water in with a second load of smb (I know I messed up) there's way too much smb in solution I know but when I put smb in it almost goes to precipitate then re-absorbs the gold.

My feeling is that the solution is way to alkaline from the smb so should I boil to reduce, add Hcl and try to drop?

Any help would be great, thanks in advance.

Kind regards,

Chris


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## MarcoP (Aug 18, 2015)

Weird, it's the same solution. But just out of curiosity, did you denoxed? Did you test with stannous chloride?

Marco


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## jason_recliner (Aug 18, 2015)

Is there a possibility that you have confused your SMB powder with Sodium Nitrate powder?


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## chrisjames (Aug 18, 2015)

I didn't denox as I was pretty sure it had completely stopped reacting and I tested a small bit to see if it would drop and it did you I did it to the entire batch. It was definitely sodium metabisulphite. They were in the same jug, I separated them out and then added the smb, one dropped and the other started to then drew back in the gold.
I'm actually waiting for the stannous chloride to be delivered but if one went clear I don't see why the other one didn't. I've been going over it in my head and the only difference is that I added two scoops of smb to the pot that didn't react. I think I need to reverse what I've done there but I'm not entirely sure how! It really has me scratching my head. I'm assuming it must have become alkaline from the smb and unable to react.
That's why I thought if I add Hcl it would acidity it and then be able to drop with smb?

It's the weirdest thing!


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## MarcoP (Aug 18, 2015)

If I was in you I would cement with copper, wait for the stannous to arrive and the go with HCl/CL. Maybe seniors have a different/better way to go.

Marco


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## chrisjames (Aug 18, 2015)

I was afraid of that. I'm not too au fait with that process. I know the Aqua Regia process pretty well but that's a new load of learning to do :|
I was hoping there was a way of saving it the way it is. I was most likely going to re-dissolve in AR and then precipitate again to clean it up a bit but was hoping to avoid adding too many more steps!


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## chrisjames (Aug 18, 2015)

Can I cement with copper then do a 50/50 nitric then dissolve in AR again??


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## jason_recliner (Aug 18, 2015)

The two pots are not the same quantity of solution. If you have not diluted the yellow one further, and if you put the same amount of SMB into each jug, then you have put a lesser concentration of SMB into the yellow pot.



> I know the Aqua Regia process pretty well


Alas, not well enough. You have excess nitric in solution; of this there is little doubt. Partial precipitation followed by immediate redissolving is a dead giveaway.
A little excess nitric can be swamped by more SMB, within limits. Before you start over, you have little to lose by adding another spoon of SMB directly to the yellow solution. I would not predissolve the SMB.

If by two spoons you see no effect, I'd stop adding it and move to cementing on solid copper.


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## chrisjames (Aug 18, 2015)

At the time the reaction froze the pots contained the same amount of solution. It's only since then I added the second smb with distiller water, that's why there's more solution in the second pot.

The pots were almost exactly identical at the time of reaction. The only difference was that I added more smb. I know it seems that it's because of excess nitric but I don't know why one worked and one didn't. That's the weird thing. After the reaction froze I tried a few more spoonfulls of smb but it fizzed and then nothing.

would heating and reducing the solution make any difference do you think? I tried a light boil for a short time last night but not enough to start reducing. I assumed if I concentrated it that may make a difference?


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## jason_recliner (Aug 18, 2015)

chrisjames said:
 

> would heating and reducing the solution make any difference do you think? I tried a light boil for a short time last night but not enough to start reducing. I assumed if I concentrated it that may make a difference?


Stop guessing and experimenting, unless you know the expected outcome and the reason for it. Playing will compound your mess.

Boiling is not a good idea. We gently evaporate solutions down, but except in specific circumstances, we don't boil them. We don't even like the word. The last thing you want is your gold splattering all over the place.

If a few more spoonfuls of SMB did nothing, my best advice is to cement on copper. Stannous chloride will tell you when it's finished.
Start over. Add nitric slowly.


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## jason_recliner (Aug 18, 2015)

On the other hand, if you want try experimenting with evaporating it down, or even more SMB, added HCl; take a small sample, say 10ml or whatever is convenient. Rather that is, than play with a batch that has perhaps 20 grams of gold in it.

Record everything you do, in weight and measure. If it works, you can transfer it to larger scale.

You can also get up to speed with cementing on copper that way.


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## chrisjames (Aug 18, 2015)

I'm not guessing or experimenting. I've read on here from other members that heating the solution can help push out the gold. As I said I tried, it didn't work so I'm asking. I get it to a gentil boil, barely enough to have bubbles break the surface.
All of the things I've mentioned I've seen on other posts on here apart from adding the extra H2o, that ones on me.

I guess I'll have to go down the copper came ting route then. Thanks


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## Palladium (Aug 18, 2015)

Wait on the stannous and test it if theirs gold then I would add dry smb stirring vigorously until it dropped. The smb will eventually kill the nitric. The stannous will tell the tell.


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## 4metals (Aug 18, 2015)

I agree with Ralph, the SMB will drop the gold, and if there is free nitric in solution it will re-dissolve the gold and you will produce the red fume, this will continue as you slowly add SMB until the free nitric is consumed, then the gold will remain at the bottom of the flask. 

What you risk is adding too much SMB, but it will dissolve in hot water after the gold is down and sitting in a pile of excess SMB (try to avoid this). You also may precipitate copper as a chloride from excess SMB but it is still better than cementation at this point. You can always cement with copper if all else fails. 

I agree with Ralph in adding the SMB as a dry powder. I never dissolved it before using it, no sense making more waste. Just add it slowly with stirring. 

This entire issue is further complicated by lack of stannous. The stuff is worth having around! Ya think?


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## chrisjames (Aug 18, 2015)

I went for more smb. I think I've gone over the top with it. It must be 6 tea spoons full. It reacts by fizzing but then dies down within seconds and goes back to clear yellow. No gold is dropping out.

What happens if I've added too much smb and what's the recommended next step.

Also I must say that I'm doing his as a one off project to make some jewellery from the recovered gold so I'm by no means well read on the subject so any help to get me through this would be much appreciated. Thanks guys


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## Anonymous (Aug 18, 2015)

Chris have you got Stannous Chloride there? 

Jon


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## chrisjames (Aug 18, 2015)

Hi Jon, no I'm waiting for the delivery.

I've just put 100g of smb into the solution and it has started to precipitate the gold, very very slowly whilst giving off the tell tell brown/red smoke. The solution still reacts to the smb so I'll have to get more in the morning and keep adding small amounts until it stops reacting.

I'm still confused as to why one dropped instantly with only 1 teaspoon and the other needs so much when it's from the same batch. The only thing I can think of is that the pot that precipitated instantly was from what I poured off of the solution first. Does nitric in solution sink to the bottom? That may cause concentrated nitric in one and not the other??!

Regards

Chris


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## Barren Realms 007 (Aug 18, 2015)

chrisjames said:


> I'm still confused as to why one dropped instantly with only 1 teaspoon and the other needs so much when it's from the same batch. The only thing I can think of is that the pot that precipitated instantly was from what I poured off of the solution first. Does nitric in solution sink to the bottom? That may cause concentrated nitric in one and not the other??!
> 
> Regards
> 
> Chris



It's not likely that the nitric separated. 

Check your first solution with stannous when you get it and see if you don't have a positive test for gold. If you don't have a positive test still take a piece of copper and put into the solution and see if anything cements onto the copper.


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## FrugalRefiner (Aug 18, 2015)

Just a quick thought, but have you tried adding a bit of HCl? Sounds like you've added enough SMB, but without some excess HCl, your gold won't drop.

Dave


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## Palladium (Aug 18, 2015)

He mentions adding hcl earlier on in the thread, but I'm not sure if he did or not. I've had super saturated silver solutions that would not start to drop from copper until you add a little free nitric to kick it off. That usually happens with concentrated solutions though and not so much with diluted. Sort of like vapor lock. Lol


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## chrisjames (Aug 19, 2015)

I haven't added any Hcl yet, in my head it seemed like a good idea but I was warned against it as 'experimenting' but to me it made some sense. The solution is about .75l and contains about 40g AU. There's obviously about 100g+ of smb and it's still producing brown vapours. The delivery date on the stannous is 26-29th Aug so this is becoming a massively drawn out thing (I should have ordered it sooner) :|
All I can do is wait for that it. I'll try some Hcl for the second solution and see if that helps the drop.

Edit: It's closer to 1.25l. From other threads I've read would it maybe be worth while concentrating the solution slightly then adding Hcl?

Edit 2: I managed to find a company online and got some Tin (II) Chloride. I'll prepare it later and test the solutions. I'll let you know what I find out,

Thanks guys.

Chris


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## jason_recliner (Aug 19, 2015)

Regarding "experimenting"...
To have good reason to do something, with have an expected outcome, is one thing. Experimenting is when you start thinking "I wonder what would happen if I...". And then it is definitely better to ask before you do something potentially counterproductive.

Everyone who answers is genuinely trying to help you. But you see, you also asked a question about whether you should boil, then later revealed you'd already previously done it anyway. So we're not really sure where you're up to.

Now, adding HCl will cause no harm, but excess does lead to more waste to deal with. You have said you have read Hoke's book. Her evaporation method actually requires adding HCl. She talks about evaporating down excess nitrate, you should find it around page 45 - that's from memory, I don't have it handy but I have spent a bit of time there myself in the past. It's a time consuming process. I used a stripped down coffee maker.

If you have 100g of SMB in there, you'd have to have one heck of a lot of nitric in solution. That's why I thought you could have mixed SMB with sodium nitrate. Don't SNIFF it, obviously, but does your solution have a "smell" of sulphur dioxide / rotten eggs at all?

Concentrating, slowly, gently, will not harm your solution. You've about an ounce and a half (?) of gold in that 1.25 litres of solution. Hoke also says that each ounce of gold you need 4oz HCl + 1oz HN03. So you can safely reduce it by a fair bit.


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## chrisjames (Aug 19, 2015)

Thanks for all your help guys. The ideas have been invaluable!

I mixed up a batch of stannous chloride and tried it on both pots. The one I thought had dropped was all clear and the yellow pot went black.

I've since cleaned off the gold from solution from the clear pot and started driving off some of the liquid from the other.

Hi Jason, the smell is slightly 'eggy'. When I add the smb which is definitely smb (otherwise the brewery have got it wrong) thee is a small puff of brown and the gold tries to precipitate but is drawn back into solution. I still don't understand why two pots that were divided from the same batch have worked so differently.

As for too much nitric I think I can answer that as a rookie I thought that not all o the gold had dissolved... I've since learned that it was probably rhodium that was on a cross pendant in the batch (it looked like gold, doh)

Chris


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## jason_recliner (Aug 20, 2015)

chrisjames said:


> I mixed up a batch of stannous chloride and tried it on both pots. The one I thought had dropped was all clear and the yellow pot went black.


You did what?! :shock: 
Oh man, you really have to read a lot more before doing. What were you expecting to happen?

You test for presence of gold with stannous chloride. Hoke calls it testing solution A. The idea is to use it on a sample of your solution, e.g. a cotton bud. The dissolved tin forces the gold out of solution as a colloid, which looks purple/black. You don't mix it into your solution.
Item 10: http://goldrefiningforum.com/phpBB3/viewtopic.php?t=562
You certainly have a positive reaction.

I think I am unable to help you recover it from here. Adding stannous chloride to the gold has taken it beyond the scope of my pitiful knowledge in breaking colloids.
Depending on how much SnCl2 you have put in, it may be possible and worthwhile trying to redissolve it with sulphuric (a stronger acid), or cutting your losses on a small amount of gold that has become a colloid. Do NOT just blindly add sulfuric acid! Don't do ANYTHING yet.

It now requires someone more expert than I, before you do anything else to your solution.

I expect these things will need to be known:
1: Exactly how much SnCl2 did you mix in?
2: If you take a cotton bud (q-tip) sample of your now black solution, does it still give a reaction for gold, when tested properly with stannous chloride.



> As for too much nitric I think I can answer that as a rookie I thought that not all o the gold had dissolved... I've since learned that it was probably rhodium that was on a cross pendant in the batch (it looked like gold, doh)


As a side note, did you by any chance add your nitric AFTER you divided the jug into two pots?


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## chrisjames (Aug 20, 2015)

Reading your long post made me panic Jason thinking I had messed up. Don't worry when I say I tested it on both pots I mean used my glass rod to drop a tiny amount onto a glass tile and add a small drop of the stannous. I also used the recipe I got off here which worked great. :lol:

I've only gone as far as heating the solution to draw off some h2o but it's taking its time as I only have a few hours of light after work (plus if I'm in the shed all evening my fiancé isn't too happy!!)

All the additions were done prior to filtration. I finished the reaction of the ar, added a few drops of sulphuric and let settle over night. I then filtered the solution and divided the pots into 2. I then took off a small amount to test with the smb which worked instantly so I used it on pot one which reacted immediately and dropped all of the gold. I immediately put in smb to pot 2 and... Well we know what happened after that.

I've been over the pictures I've taken and there really are no more steps.

Thanks for your concern Jason 

Chris


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## jason_recliner (Aug 20, 2015)

Way to freak me out Chris. But you did say you tried it on the pots and the yellow _pot_ went black.
Ok, all happy then.

Your process of adding a touch of sulfuric, waiting overnight, then filtering; it looks spot on to me.


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## chrisjames (Aug 20, 2015)

I think I need to be careful how I phrase things 

I've followed as closely as I can the indeeditdoes YouTube channel. I believe the guy from it is on here. Very informative!!

It's my fault that I messed it up as I added the extra nitric when I saw what I thought was gold not dissolving which I now think was the rhodium!

I'm going to reduce and possibly try hoke's hcl reduction. I'm just having to learn to be patient, which isn't easy! 

I'll let you know what happens, I was hoping to have the watch cast by my birthday tomorrow but that's never going to happen so at least I can relax about it now.

Kind regards,

Chris


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## Palladium (Aug 20, 2015)

Happy birthday brother!! Tomorrow is my birthday also.


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## jason_recliner (Aug 20, 2015)

Evaporation really does take ages. Rate is somewhat proportional to surface area so do use the widest mouthed container you can find. For me it was only 200ml at a time, so salsa jars were excellent. Your existing pot is probably pretty good. And as your pot gets lower, the surface area will increase. A gentle breeze will speed things up. You want a zephyr, rather than a squall.

This is what I did myself, about a year ago, to avoid cementing. Now, I'd just go with cementing on copper with stannous testing to tell me when it's done.

Your birthday present will be late. But it will come!


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## chrisjames (Aug 20, 2015)

Thank you, you too palladium (Sorry I don't know your real name)  

I've just been reading on cementing to make sure I have all the facts. It may just be the way to go if it doesn't drop soon.
Funny you should say about surface area as I was thinking about dividing the solution into my two pots to increase the surface area a bit but we've been here before haven't we! :roll: 
I was going to clean up my gold and then do the process with AR again to make sure I have as pure as I can gold to then alloy to 18k rose so when it goes to the assay office I have a better idea that it's 18k and not under.

Jason if I were to cement with copper could I then go straight to my 50/50 nitric followed by AR or would I have to enquart, 50/50 and AR? It isn't a massive issue it just adds a few annoying steps.

regards,

Chris


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## g_axelsson (Aug 20, 2015)

Evaporation takes a long time, heat makes it go faster and so do larger surface area.

But the coffeepots are not a suitable vessel to evaporate from. The narrow neck hinders the moist air from leaving the pot and evaporation slows down to a crawl. You need a wide vessel with a low rim to increase the exchange of air.
Forcing air above the surface also removes the saturated air and replaces it with dry air which easily absorbs new moisture. Guess why we blow on a cup of hot coffee?

So to recap, coffeepots are really bad for evaporation, the narrow neck is designed to minimize evaporation and keep the saturated air inside. You want a wide and low vessel instead and a draft speeds it up even more.

Göran


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## jason_recliner (Aug 21, 2015)

I offer the opinion that coffee pots are less than ideal, rather than unsuitable. By all means a wide mouthed dish is better if you have something handy*, but your existing pot will work if it's all you have. It just takes longer (possibly even much longer). You do at least have a decent surface area going for you.
Droplets may form near the top of the pot and these are testament to the inefficiency of the pot shape. But if you have air flowing, you will also have air currents eddying in the pot, helping you out.

Moving your solution around from vessel to vessel is also less than ideal and should be avoided wherever possible (rather than disallowed). You either leave a tiny bit behind, or you add more water each time you properly flush out the old vessel. Or both.

I can't and won't speak for inquartation processes. But I can tell you that after taking your gold powder out of one acid, you don't want to drop it straight into another. Even after washing in water, residual HCl + nitric = AR = dissolution of gold. You would need to incinerate your powders red hot first when changing between acids. Harold_V has an excellent post on incineration. And washing.

* Don't use kitchen items for refining and expect to use them in the kitchen again.


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## g_axelsson (Aug 21, 2015)

Correct, except when the next step is AR. There is no need for incineration between inquartation and dissolving the remaining gold in aqua regia. The only thing you will see is a small cloud of silver chloride that is formed from the silver nitrate. To wash away all silver chloride is virtually impossible, it will sit inside the gold sponge.

Göran


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## Anonymous (Aug 21, 2015)

Also, we've covered making Stannous Chloride a million times. Geo has a pretty good video about it. Use HCl and tin solder and you've got your test solution. Geo's video below in case that simple combination is a tad complicated...

https://www.youtube.com/watch?v=659G75Kc3F0

Oh, and coffee pots? Buy some lab glass online it really isn't expensive.


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## Mad Oshea (Sep 6, 2015)

Add Cyonide to water, and install to liquid. It will form. Use a gas mask! After gold has formed, it will be a problem with evacuation the of the cyonide and chems.. It will drop.. Mad-


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## Mad Oshea (Sep 6, 2015)

You know AU, Gold will float? Silver will sink? Platinun will explode with an HHo derivative??????


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## butcher (Sep 6, 2015)

Mad Oshea,
I am having a hard time understanding your comments, I have not seen much of anything you have posted so far that makes any sense.


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## chrisjames (Sep 13, 2015)

In the end I cemented with copper (which turned out to be really easy) I just wish I had done it sooner. I then re dissolved in AR with the rest of my gold precipitate from the other pot and then precipitated the entire thing. I figured it would be purer which it did.

I've now alloyed it with copper and silver to make 18k rose. It's a great colour!! I'm currently in the garden with my homemade kiln and burnout oven trying to cast my watch (that was the purpose of the refining) I'm just doing a practice cast now out of silver to make sure I get it right but I'll hopefully be casting the gold watch in the next day or two. I'll post pictures if anyone's interested?!

Thanks for your help on this guys, I really couldn't have got it done without you all!

Kind regards,

Chris


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## bswartzwelder (Sep 14, 2015)

Can't wait to see those pictures.


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## FiP (Jan 11, 2016)

Hello to all,

I came here while doing research and reading the thread and various comments, i have a question for those that have worked with ferrous sulfate.

I have had a solution with excess nitric in the past. Tried to drop with potassium MB. It kept redissolving. 

I then did nothing more and switched to adding ferrous sulfate (from a funnel with a filter, so slowly) and did eventually drop.

I'm mentioning it since i think in time it pushed out the excess nitric and someone has mentioned in the thread adding a few drops of sulfuric acid, and ferrous sulfate is produced using sulfuric acid. 

So my question is: for a excess nitric solution, would dropping with ferrous sulfate after SMB (or PMB for that matter) failed, bring benefits as pushing out exess nitric and adding benefits in connexion to sulfuric acid (which i don't understand at this point).

Curious to know.
And i look forward to pic of the casting of the watch too

My best to all!


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## butcher (Jan 13, 2016)

The little bit of added sulfuric acid is normally used to help remove lead from solution as the insoluble lead sulfate.

Actually if you had nitrates in solution adding an acid like HCl or H2SO4 would convert the nitrate salts in solution to nitric acid, Hydrogen from the acid, and the nitrate salt would make nitric acid.
H + NO3 ---> HNO3
nitric acid which can decompose as NOx gas (normally with added heat, or a reducing agent like a metal copper for example), or even excess SMB...

The sulfuric acid would not decompose excess nitric acid, both would be in solution.

You may have just added enough reducing agent to overcome a small excess of nitric acid, which may have happened if you had just added a bit more SMB or potassium metabisulfite.

The sulfite salt and ferrous sulfate both can reduce gold from solution, but the chemistry and how they do so is completely different, sulfites produce SO2 gas with the acid, it is actually the SO2 gas that is the reducing agent that gives gold ions the missing electrons to become atoms of gold which join together to form a heavy enough powder to precipitate from solution.

A few chemical formula’s using reagents to precipitate gold

Sodium bisulfite and gold chloride solution
2 HAuCl4 + 2 NaHSO3 --> 2 Au + 8 HCl + Na2SO4 + SO2
or 
2AuCl3 + 3NaHSO3 + 3H2O --> 2Au + 3NaHSO4 + 6HCl

sodium metabisulfite and HCl
Na2S2O5 + 2 HCl → 2 NaCl + H2O + 2 SO2

gold chloride and sulfur dioxide gas
2AuCl3 + 3SO2(g) + 3H2O --> 2Au + 3SO3 + 6HCl


Sodium metabisulfite in gold solution:
Na2S2O5 + H2O --> 2 NaHSO3

Notice we actually make sodium bisulfite
Then
2 AuCl3 + 3 NaHSO3 + 3 H2O --> 2 AU + 6HCL + 3 NaHSO4

Ferrous sulfate (iron sulfate) (copperas) (FeSO4) and gold in chloride solution:
2 AuCl3 +6 FeSO4 --> 2 AU +2 Fe2(SO4)3 + Fe2Cl4
(Note we do not make sulfuric acid above). 

potassium metabisulfite and HCl acid 
K2S2O5 +2HCl --> 2KCl + H2O + SO2(g)

Adding SMB (or K2S2O5), and ferrous sulfate in the same reaction to precipitate gold, there is no benefit, and would complicate matters for the most Part, and would be recommended.
just because it happened to work for your particular circumstance or one certain reaction (which may be because you finally decomposed the excess nitric acid redissolving your gold with excess reagents, does not mean it will not complicate the next batch in another circumstance, there is no benefit, and it is not recommended...

There are ways to deal with excess nitric acid in your gold chloride solutions.

Do not use more than needed.

Sulfamic acid can be used to destroy the excess HNO3 in solution.

Dissolving a metal like (an added button of gold) to consume the nitric in solution (with heat), (Harold's method).

Or the 3 evaporation process ( discussed in Hoke's book) where a little HCl acid is added towards the end of each of the three evaporation's in which you concentrate the gold chloride solution to the point of driving off the excess nitric acid as NOx gas, (where HNO3 decomposes to gas before most of the HCL or gold chloride decompose.
A few drops of sulfuric also have the benefit here. if you happen to get carried away by mistake or inexperience, with the evaporation process, and go to far with the evaporation, where you can form salts of the gold chloride or cook those salts, (driving off too much of the HCl or chloride salts as gas by mistake) the sulfuric aids in helping to keep the gold salts in solution, sulfuric acid is less volatile and will not decompose even after the HCl has or the chloride salts decompose to gas...


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## FiP (Apr 7, 2016)

butcher said:


> The little bit of added sulfuric acid is normally used to help remove lead from solution as the insoluble lead sulfate.
> 
> Actually if you had nitrates in solution adding an acid like HCl or H2SO4 would convert the nitrate salts in solution to nitric acid, Hydrogen from the acid, and the nitrate salt would make nitric acid.
> H + NO3 ---> HNO3
> ...



Thank you Butcher! Very clear and hélpful. Thank you for the time you put into this!


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## au-artifax (Nov 24, 2021)

chrisjames said:


> I didn't denox as I was pretty sure it had completely stopped reacting and I tested a small bit to see if it would drop and it did you I did it to the entire batch. It was definitely sodium metabisulphite. They were in the same jug, I separated them out and then added the smb, one dropped and the other started to then drew back in the gold.
> I'm actually waiting for the stannous chloride to be delivered but if one went clear I don't see why the other one didn't. I've been going over it in my head and the only difference is that I added two scoops of smb to the pot that didn't react. I think I need to reverse what I've done there but I'm not entirely sure how! It really has me scratching my head. I'm assuming it must have become alkaline from the smb and unable to react.
> That's why I thought if I add Hcl it would acidity it and then be able to drop with smb?
> 
> It's the weirdest thing!


I may be wrong, but I don't think SMB would make your solution more "base". As far as I know it creates another acid when it mixes with H2O and reacts with an acid.


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## au-artifax (Nov 24, 2021)

chrisjames said:


> I'm not guessing or experimenting. I've read on here from other members that heating the solution can help push out the gold. As I said I tried, it didn't work so I'm asking. I get it to a gentil boil, barely enough to have bubbles break the surface.
> All of the things I've mentioned I've seen on other posts on here apart from adding the extra H2o, that ones on me.
> 
> I guess I'll have to go down the copper came ting route then. Thanks


Heating doesn't help "push out the gold". What heating does is help fine particles in a cloudy suspension coalesce and drop to the bottom. But of the gold isn't "reduced", it won't coalesce.


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## au-artifax (Nov 24, 2021)

FrugalRefiner said:


> Just a quick thought, but have you tried adding a bit of HCl? Sounds like you've added enough SMB, but without some excess HCl, your gold won't drop.
> 
> Dave


This true... you need an acid to release the sulfur from the SMB (via the formation sulfamic acid). It is not the SMB that precipitates the gold..... it is the byproduct of its reaction with an acid, which releases sulfur (to which gold has an affinity for).


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## VK3NHL (Nov 24, 2021)

Always de-nox even if you think you don’t need to. Use Sulfamic acid Not Urea. (Urea is for the garden)
Always STANNOUS test you solutions before & after your drop.
We are all learning all the time.
Good luck..


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## cejohnsonsr1 (Nov 25, 2021)

Precipitation with SMB produces an exothermic reaction. What you need to do is cool it down with ice made from distilled water. You should do this the 1st time right after you remove it from the heat after the AR has dissolved all of the gold. Cooling this way at this point will precipitate any residual silver chloride and other solids which are removed by filtration. Then use more ice to keep the solution cool during precipitation with SMB. The SMB will denox a good bit of excess Nitric because whatever is precipitated will simply redisolve until the excess Nitric is consumed (up to a point). Much better to use small, incremental doses of Nitric when dissolving so there isn't any excess to worry about/deal with. You'll know when you've used enough SMB because it will foam up on top. Double check with stanis. I've mentioned this in a couple of other threads, but Sreetips has some excellent videos showing this process in great detail. He just released a new one today. I highly recommend checking him out on YouTube.


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