# precipitating with sodium sulfite



## teclu (Jul 21, 2009)

Hello, 

I believe that I’ve reached the precipitating stage. I have a sample of 150 ml clear yellow AR (diluted 1x3 water, filtrated ). It contains 8 gr foils, the nitric necessary in dissolving these was added in small amounts (until it was completely dissolved), I even tried to use Harold's trick, only that instead of the button I used a few foils. A part of them dissolved slowly, the others remained intact, this made me think, that "excess nitric" is ok. I diluted and filtrated. My Berzelius with the AR stays uncovered of two days. 

I got today this sodium sulfite, here are it's characteristics: http://www.inorganics.basf.com/p02/CAPortal/en_GB/portal/Bleichmittel/content/Produktgruppen/Bleichmittel/Produktinformationen/Natriumsulfit-Sorten

My question is: 
Which would be the SS ration for the AR solution that contains 8 gr foils (estimated 7 gr gold), does the water need to be warmed up?

I know that those with experience guide themselves after data/signs, eg. for GSP one of the signs of a succesfull precipitating is the smell of sulfur, but this is possible only by having a long practice. Unfortunately I don't have this, reason why I wouldn't want to add more than it is necessary. By the way, how serious are the consequences for adding excess SS (or any other reducing)? 

Thank you in advance,

teclu


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## dick b (Jul 21, 2009)

Hello teclu:

I think you have the wrong sulfite.

You have sodium sulfite Na2SO3.
You need sodium metabisulfite Na2S2O5.
I'm not sure what you have will drop gold. Better wait for one of the more experienced refiners to advise you.


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## goldsilverpro (Jul 21, 2009)

dick b said:


> I think you have the wrong sulfite.
> 
> You have sodium sulfite Na2SO3.
> You need sodium metabisulfite Na2S2O5.
> I'm not sure what you have will drop gold. Better wait for one of the more experienced refiners to advise you.



dick b,

No offense, but what you've said is not correct. I most always used sodium sulfite, Na2SO3, for 30 years to drop gold. With great success, I might add. I have also used SMB and the techniques, quantities, and resulting gold purities, for both, are essentially the same. There are several different sulfites that can be used.


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## dick b (Jul 21, 2009)

Chris:

Thanks for the heads up. I wasn't sure and the MSDS sheets didn't show me the answer. 

Just didn't want to see it go bad.

dick b


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## teclu (Jul 21, 2009)

dick b said:


> Hello teclu:
> 
> I think you have the wrong sulfite.
> 
> ...



Hi dick b!

I've already said and admitted, that I'm beginner at gold plated items, but to get that experience you are talking about, there has to be a point from where to start, this is the reason why I want to proceed with small but safe steps. Eg. I have a few oz of foils, but I use AR process and precipitating only on a sample of 8 gr. Anyway, thanks for your opinion.

teclu




goldsilverpro said:


> dick b said:
> 
> 
> > I think you have the wrong sulfite.
> ...




GSP Hi!

You're wright, I've chosen sodium sulfite reading your posts. I hope that I understood the part with the smell of sulfur, I know about stannous chloride, but please tell me what happens if I add too much sodium sulfite. Can you "convert" your tablespoons and cups in grams and mililiters for me? Only if you want to, of course. I'm reading Hoke as well as many posts every day on this forum, but in the same time to assure myself, that I've understood the theory, I have to put it in practice. 

Thanks!

teclu


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## goldsilverpro (Jul 21, 2009)

teclu said:


> You're wright, I've chosen sodium sulfite reading your posts. I hope that I understood the part with the smell of sulfur, I know about stannous chloride, but please tell me what happens if I add too much sodium sulfite. Can you "convert" your tablespoons and cups in grams and mililiters for me? Only if you want to, of course. I'm reading Hoke as well as many posts every day on this forum, but in the same time to assure myself, that I've understood the theory, I have to put it in practice.



I think I used Stauffer brand Photo Grade sodium sulfite. I liked Photo grade because it is fairly pure, yet not too expensive. I bought it in 50# bags, but you used to be able to buy Kodak Photo grade, in 1# packages, from camera stores that sell film processing chemicals (if they still exist).

The smell of SO2 is only a guide that I use. If gold is still in the solution after adding some sodium sulfite and stirring well, you probably won't smell SO2. You should always use stannous chloride to prove any of the sensory guides that I spoke of.

Since I haven't added too much sodium sulfite for many years, I can't exactly remember what happened. I know that, with a great excess, some will sit on the bottom, undissolved, and will get mixed with the gold powder. This can be removed in the filter with hot water. I also seem to remember that a copper compound can precipitate. It can probably be removed with HCl.

If there is no free nitric left in the solution, it will take about the same weight of sodium sulfite as you have gold, or a little more. I would dissolve about that much in a minimum amount of hot water, add some of it, stir well, and test with stannous chloride. Add some more, stir, and test. At some point, it will test negative. If you have free nitric left, it will take more. Having much free nitric can be a killer. A little nitric can consume a lot of sodium sulfite. One time, when I was a noobie, I remember adding pounds of sodium sulfite and still couldn't get the gold to drop. I probably ended up cementing the gold on copper and starting over. You must effectively get most of the nitric out - whether using urea, boiling down, or using my minimum nitric method - before using sodium sulfite or SMB, or you can have problems. For a noobie, boiling down the aqua regia is the most guaranteed method.

I have assumed you are using aqua regia. If you used HCl/bleach to dissolve the foils, there is no nitric to worry about. Just add the sodium sulfite or SMB, pretty much as I've outlined above, and test often with stannous chloride. However, I've never had a need to use HCl/bleach, so I may be talking through my hat. The gold concentrations in these solutions tend to be much lower and I still don't know whether it should be done hot or cold. Maybe, Steve or someone else should chime in here.


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## dick b (Jul 21, 2009)

Hello teclu:

I too am a newbe to refining and just didn't want you to mess up your gold. I've been here for around a year and learn something new every day by reading and asking questions. 

There are plenty a experienced members who are more that willing to pass their experience to those that want to learn. We all make mistakes and have to correct them, but its way better to not make them, instead of trying to fix them afterwards.

Good luck with your refining and I hope you get a nice button.


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## lazersteve (Jul 21, 2009)

Either SMB or Sodium Sulfite, or even sulfur dioxide gas will work fine for reducing gold in HCl-Cl solutions. When highly concentrated the solution will lean towards deep orange to deep red when highly concentrated.

I use dry SMB exclusively now days and never have had to heat the solution to get the gold to drop. I've precipitated gold in cold weather also (35 F), but the reaction is slower to begin. The solution will heat on it's own if enough gold is present.

To much SMB or sulfite will convert soluble copper II chloride into insoluble copper I chloride. As GSP mentioned, copper I chloride will wash out with HCl.

If you add your sulfite and the gold appears then redissolves (begins fizzing) you have too much residual oxidizer (nitric, chlorine, or peroxide) which needs to be removed via boiling or one of the other methods previously mentioned before the gold will precipitate.

I go by the visual indicators of the color of the solution to guide me as to when the gold is finished precipitating. I confirm my visual findings with a quick stannous test.

Steve


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## teclu (Jul 21, 2009)

GSP, Steve Hello!

Many thanks for your time and for your patience which you are consumed on those like me.


teclu


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## teclu (Jul 22, 2009)

I dissolved 10 grams of Na2SO3 in 45 ml water, and I added this in 150 ml of diluted AR (which contains 8 grams of foils). The precipitating began instantly and the bottom of the Berzelius started to get brown with very small and shiny particles (a few of these particles were floating on the top; by the way, how wrong is this?). I let it to settle down aproximately 2 h, meanwhile I tested with stannous chloride, no sign of purple. I decanted slowly, washed twice with hot water, and after the last decantation I applied on the exterior side of the Berzelius 150 Celsius degrees with a hot air blower until the powder began to move freely (compactly). I prepared it for the picture, and here it is 6,84 gr of brown powder: 

http://i28.tinypic.com/2aj5y9k.jpg
http://i26.tinypic.com/22upl4l.jpg

I didn't washed it with hot HCl, I guess that is why the powder is dark. I hope it isn't too late yet to do the washing.

I'm waiting for you opinion and advices.

Thanks

teclu


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## goldsilverpro (Jul 22, 2009)

It's never too late to leach the powder with HCl. Use Harold's method, it you can find it.

Floating gold usually occurs from traces of oil that are present. Cleanliness is important. Sometimes, it can occur from microscopic bubbles that are attached to the gold. I usually kept a fine misting spray bottle filled with water. Often, but not always, a fine mist of water on the surface will cause the floaters to sink. It sometimes helps to add a drop of dishwashing soap to the water.


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## surshot (Jul 22, 2009)

teclu

I don't know, the color just seems a little off, Why don't you send it to me and I'll test it for you. :lol: No really it looks great can't wait to see your picture of it melted.
I've got some AuCl that I can't wait to drop the gold out but have to wait untill I can afford to get some SMB greai pic thanks Ed


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## Harold_V (Jul 22, 2009)

teclu said:


> I didn't washed it with hot HCl, I guess that is why the powder is dark. I hope it isn't too late yet to do the washing.


It is NEVER a good idea to skip the HCl wash, even if your exhausted solution is free of color. The wash insures the best possible quality, and rarely fails to brighten the color of the resulting gold. 

If ferrous sulfate is used to precipitate, it is obvious that iron oxide will be included in the yield without the HCl wash. If that be the case with iron, it most likely will also be true of other base metals. 

It is never too late to apply the wash, not until the gold has been melted. It makes more sense to do so immediately after decanting the solution from which the gold came. I never did a water rinse prior to the HCl wash, ----I could see no benefit. As far as I'm concerned, it's wasted motion. The boil in HCl generally (not always) allows the precipitated gold to agglomerate much better, so little, if any, of the fine particles are suspended in the wash solution, allowing for rapid decanting. 

Nice job. Next time, use the HCl wash. When you do so, it will become apparent why it's so important in that you will see, from the color of the resulting wash solution, that you are removing substances that, otherwise, would have followed your gold to the melting process. 

There are NO shortcuts to achieving a good end product. 

Harold


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## teabone (Jul 22, 2009)

Your powder is pretty high quality from looking at your pictures. To ensure even better quality , I would take Harold's recomendation and do the washes in hcl. Good job , by the way.


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## teclu (Jul 23, 2009)

goldsilverpro said:


> It's never too late to leach the powder with HCl. Use Harold's method, it you can find it.
> 
> Floating gold usually occurs from traces of oil that are present. Cleanliness is important. Sometimes, it can occur from microscopic bubbles that are attached to the gold. I usually kept a fine misting spray bottle filled with water. Often, but not always, a fine mist of water on the surface will cause the floaters to sink. It sometimes helps to add a drop of dishwashing soap to the water.





Hello GSP,
Many thanks for your advice in "floating gold". It is posible to exist some traces of oil, even if the pins was without oil or another grease, and even if I tried to work in all stages clean.

teclu






surshot said:


> I don't know, the color just seems a little off, Why don't you send it to me and I'll test it for you. :lol: No really it looks great can't wait to see your picture of it melted.
> I've got some AuCl that I can't wait to drop the gold out but have to wait untill I can afford to get some SMB greai pic thanks Ed



Hello surshot,


Good joke, thanks. Anyway, I have a few steps to the first button.


teclu






Harold_V said:


> teclu said:
> 
> 
> > I didn't washed it with hot HCl, I guess that is why the powder is dark. I hope it isn't too late yet to do the washing.
> ...





Hello Harold

Sir, many thanks for your detailed information. Now I understand that in this work are not cuts.

teclu




teabone said:


> Your powder is pretty high quality from looking at your pictures. To ensure even better quality , I would take Harold's recomendation and do the washes in hcl. Good job , by the way.




Hello teabone,

Thanks for your advice, I’ll take Harold's recommendation.

teclu.


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## goldsilverpro (Jul 23, 2009)

Teclu,

You definitely did well. Not many have done as well with their first batch. You studied, took your time, were patient, and asked good questions. I'm sure you learned a lot.

Melting is next.

Congratulations!


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## teclu (Jul 23, 2009)

goldsilverpro said:


> Teclu,
> 
> You definitely did well. Not many have done as well with their first batch. You studied, took your time, were patient, and asked good questions. I'm sure you learned a lot.
> 
> ...




GSP,


Thanks for the appreciation, it means a lot to me. Your answers and the other's as well were very usefull for me. Actually this forum is a great source of information of good quality. You have to be patient in looking it, you have to ask, listen and than apply it, of course.

teclu


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