# smb



## arthur kierski (Apr 12, 2009)

latelly i am having some trouble in precipitating gold with smb---(last 3 batches)--i bought some sodium bisulfite and added to the already solution which had smb and gold precipitated fine----is it possible that my smb is not working? i am also thinking of using copperas(i used it many years ago with good results) which seems very reliable---any big objections?please thanks for replies


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## butcher (Apr 12, 2009)

I like copperas, sometime if you have oxidizers like nitric left in solution the SMB will have a hard time as gold powder re disollves, if not in too high excess sometimes a little more sulfite will overcome the oxidizer, could this be your trouble?


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## arthur kierski (Apr 12, 2009)

butcher, i really do not know the reason of the smb failure but i am always afraid of not getting rid of the nitric(i use urea and i am never sure if the urea did its job)--so i am thinking of using copperas(it indicates better if the urea worked)if it did not work the solution stays green or yellow(add more urea and then more copperas)


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## oldtimmer (Apr 13, 2009)

I have had the same problem in the past. From one of the older post that I read they stated that when using SMB, if you headed your gold solution up that the gold would drop better. I heat mine until I just begin to see steam coming off and do not get to the boiling point. The last four or five times that I have done this, I have not had any problems dropping gold with SMB.

I use the AP and HCl+CL process and do not use AR.


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## shyknee (Apr 13, 2009)

arthur
for us to get a better understanding of what went wrong please give more details don't assume smb is not working
give us quantities like type of waste
how much AR ,ratio ,temp
urea- was it dissolved before u added to AR
did you dilute the whole thing if so how much
where there bubbles still coming up from the urea
how much time did you wait before adding smb
what where the reactions did the gold redissolve ? 
colors are important 
this is all important or the suggestions members give are just suggestions
if you detail the steps you take, a member might see what went wrong and be able to advise you properly !
a little extra typing can save you a lot of time instead of going back and forth assuming


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## arthur kierski (Apr 13, 2009)

shyknee;i will pass the details asked tonight---thanks for the advice


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## KCGreg (Apr 13, 2009)

Arthur, I would encourage you to practice evaporation. For some reason it took me a long time to catch on to it too. Hoke's book said to evaporate to a syrup, I was thinking like maple syrup and it's more like cough syrup. Once you get the evaporation down though, you will have alot less problems with precipitation. As one learned forum member stated "there's no need to add in unnecessary constituents when my objective is to purify". Kinda hard to argue with that kind of logic. Also, when precipitating gold from solution make sure you do the following: 1) keep it hot but not boiling. 2) make sure your solution has been diluted somewhere between 3-4 times with water and 3) make sure you dissolve your SMB completely in hot water before precipitating. Reason being, there's no need to boil it, that will undoubtedly cause a boil over and loss of values when you precipitate and also, gold precipitates much better when hot and dilute vs cold and concentrated. 

Take a known amount of gold and use the minimum amount of AR necessary to dissolve it and practice evaporation. When you get it, you'll get it and you'll nail it every time.


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## Juan Manuel Arcos Frank (Apr 17, 2009)

Arthur:

Sodium bisulfite is not the same thing than sbm,both are gold precipitants.Probably the problem is in AR´s pH..if it is near 0 the precipitant reacts with nitric acid, not with gold chloride,so gold never precipitates.

Add enough urea until no fizzes or use pH paper to get pH to 1 or more,you can add tap water too,but never add the precpitant agent until pH is 1 or higer.

Regards.

Manuel


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## leavemealone (Apr 17, 2009)

Hi arthur.
You didnt by chance purchase your SMB from "Chemistry Store" did you? I purchased a 10 pound bucket from them about 2 years ago and had the worst time with it.I called them several times,and they swear theres no way it could have been anything else but smb.Heres my issue......I ran several batches,the exact same way I had done them before,and nothing dropped out.I never was able to drop anything with the entire bucket.I would be willing to bet every piece of gold I have ever had that the stuff I purchased was NOT smb.It got so bad that I was using stannous and zinc to drop my gold.
Hope this helps.


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## lazersteve (Apr 17, 2009)

I also bought a 10 pound bucket at the chemistry store and it works perfectly every time, perhaps you got a bucket that was mixed up with something else? What did it smell like when you opened the bucket?

Steve


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## arthur kierski (Apr 17, 2009)

leave me alone , and manuel,. i read in ammen that oxalic acid and copperas precipitates from free nitric aqua regia gold. from nitric aqua regia so2 (smb or na2so3 or nahso3) precipitates gold ----as you see there are many different opinions on how to precipitate gold from ar--- gsp in one of his threads says that if you elevate the ph of the ar to 2 or 3,you will precipitate the gold with smb without the need of urea or evaporating the solution to eliminate the nitric----i use a method which might look complicated but i obtain for sure all the gold that was dissolved in the ar----the ar + naoh to ph 7 to 8---filtrate and to the hidroxides formed add hcl and a chloride solution is formed---to the chloride solution add smb or sodium bisulfite and the gold is precipitated---i do a little diferent---to the chloride solution i put iron powder and the gold is precipitated with copper and other metals ---to this (copper and other metals) i add hno3 and the gold is precipitated---to the nitric solution i add salt for silver and then naclo3 for paladium---this is done for solutions that contain gold or pt ---not gold +pt----if gold +pt , to the chloride solution one must add nh4cl for precipitating the pt and then iron for the gold and other metals


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## joehast (Apr 28, 2009)

When dropping my Cell mud, after rinsing good with water I dissolve w/ HCl-CL. Then drop w/SMB. I can not seem to fully drop. I drop most of it but MY HCl-CL still has some color. I do not have this problem with my Finger foils. Any advice would be helpful. Is it better to dilute my HCl-CL with about half water before attempting to drop..? Add SMB in powder form or dissolve in water first.. Thanks


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## lazersteve (Apr 28, 2009)

Have you tested the solution with stannous? If it tests positive try heating the solution to drive off any chlorine.

Steve


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## Harold_V (Apr 29, 2009)

oldtimmer said:


> I have had the same problem in the past. From one of the older post that I read they stated that when using SMB, if you headed your gold solution up that the gold would drop better. I heat mine until I just begin to see steam coming off and do not get to the boiling point. The last four or five times that I have done this, I have not had any problems dropping gold with SMB.
> 
> I use the AP and HCl+CL process and do not use AR.


Considering that the process of precipitation is an exothermic reaction, it is my opinion that the warm solution isn't what is helping----what is helping is the expulsion of chlorine from the solution, which is accelerated by heat. Were you to allow the heated solution to cool to ambient temperature, then precipitate, you would achieve the same results. 

If you were to heat a solution that was heavily concentrated with gold, you would not achieve complete precipitation. I experienced that very thing countless times when precipitating high concentrations. 

Harold


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## goldsilverpro (Apr 29, 2009)

> If you were to heat a solution that was heavily concentrated with gold, you would not achieve complete precipitation. I experienced that very thing countless times when precipitating high concentrations.



From my experiences, I agree. Of course, you and I almost always had high concentrations, unlike these guys. I always precipitated at room temperature, or close to it.


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## nicknitro (Apr 29, 2009)

Harold & GSP,

Right on, the heating process should be for de-chlorinating and de-noxing.

JoeHast, I'm sure Harold would say "Incineration, Double Incineration" LOL Might be the sulphuric is still in your cell mud causeing issues.

Arthur, if your process works for you in a certain refining process, more power to ya. Like LazerSteve suggests though, become very familiar with stannous chloride tests, and do it with all your washes and solutions. Keeping certain pm scraps seperate, and recording values from these pm scraps would be a great help for future refining processes.

One thing I would like to remind you of though, adding iron and copper is the long way around getting your values. It is usually considered the panic button in refining as you are trying to eliminate these elements from your gold. Then useing nitric again to redissolve the precipitant is ok, however, I wonder how much copper comes down with your gold. 

May I ask what materials you are refining, It escapes me at the moment.


Good Luck,
Nick


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## Oz (Apr 29, 2009)

Hearing GSP and Harold talk about concentrated gold solutions I though this worth putting up. I recently had someone ask me about gold chloride getting to a concentration where it was red so I processed a known mass of gold with that in mind for them. Here is a picture of gold chloride concentrated until a deep red. Notice the picture title says warm, at room temperature this would be a crystalline gold chloride. I would not suggest from my experience that you want it much over 20 troy ounces per liter if you wish for it to stay a liquid at room temperatures.


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## goldsilverpro (Apr 29, 2009)

Perfect color, Oz. 

Besides dropping silver as a chloride, dilution with 3 parts water will prevent crystallization.


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## joehast (May 10, 2009)

OK got that solved thanks for advice guys. 
Another question,
I just dropped my AR in coffee pot, I dissolved heavy gold plated pins with AP. The reaction came slow but it did get very dark brown. Well this morning it is a Milky green..weird :shock:


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## lazersteve (May 10, 2009)

Say hello to the poorly understood copper I chloride.  

The good news is your gold is likely a dark powder in the bottom.

Add HCl until the light green all dissolves and the white goes away, then let the solution settle and siphon off the liquid. 

Test the liquid to be sure it's barren, then process the dirty gold as if you had just precipitated it from AR. 

I also advise a second refining for purity sake.

Steve


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