# How much SMB



## bswartzwelder (Dec 19, 2012)

When using SMB to precipitate gold from AR, can anyone tell me approximately how much SMB is required for say 1 ounce of gold? Is it better to dissolve the SMB in water or use it straight? I will be processing a little over an ounce of gold in the near future and would just like an educated guess.


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## Pantherlikher (Dec 20, 2012)

Hey...
I've read that rescently on the forum several times... The search box is your friend...

BS...
Damn, gotta find more movies to watch while scrapping...


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## maynman1751 (Dec 20, 2012)

One gram or a little over for each gram of expected gold.


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## g_axelsson (Dec 20, 2012)

It's been mentioned quite often, about 1:1 ratio gold:SMB. But you need to remove all nitric acid from the AR (aqua regia) before dropping the gold.

If you are in doubt, just test your solution with stannous chloride. Purple you added too little (rarely the case), colorless it's enough, brown you added too much and is now getting a false positive for precious metals in solution.

I have tried both dry and SMB dissolver in water and I prefer to dissolve it. But that's a personal choise. Other people prefer to add it dry. Try and see what you prefer.

My biggest mistakes has been to not denoxing the solutions before dropping the gold and adding too much SMB so I spent a lot of time chasing that last bit of gold where there were none, only that brown stain when testing. It's so easy to think you have more gold than you really have when working with thinly gold plated e-scrap.  

Good luck!

/Göran


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## bswartzwelder (Dec 20, 2012)

I did do a search using SMB and nothing came up. I then searched with sodium metabisulfite and got a ton of responses. Evidently I didn't read through enough of them to find the answer. I also looked on the general reaction list under the general chat tab. The amount of SMB for the amount of gold didn't seem to jump out at me. Thanks for the replies. The information will be added to my Microsoft Word notes for future reference.

On a different subject, haven't heard much from Harold V lately. Is everything ok with him? He is one of the nicest and most colorful people on the forum and his absence has been noted. If you read this, Harold V, we miss you.


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## bswartzwelder (Dec 20, 2012)

Hey, i was also wondering which is better. Use SMB as a powder and drop into the AR by the small spoonful or dissolve it in water before you mix it into the AR solution? I know they will both work. Is one method preferred?


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## jimdoc (Dec 20, 2012)

bswartzwelder said:


> Hey, i was also wondering which is better. Use SMB as a powder and drop into the AR by the small spoonful or dissolve it in water before you mix it into the AR solution? I know they will both work. Is one method preferred?



I like using SMB as a powder. When you mix it with water it seems to be wasting it, as whatever is mixed must get used.

Jim


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## g_axelsson (Dec 20, 2012)

jimdoc said:


> I like using SMB as a powder. When you mix it with water it seems to be wasting it, as whatever is mixed must get used.
> 
> Jim


I premix it into water of the same reason and to keep the level of SO2 gas released to a minimum.
Maybe I just have too much HCl in my solution but when I added dry SMB to a solution it started to fizz a lot and most SO2 never made it into the solution, but with premixed I got no bubbles but it started to drop the gold instantly.

I use a small scale, put a small beaker on, tare and then measure up just a tiny amount more than the gold I expect. Even if I would just use half of what I mixed I would have lost only $2 in SMB for each pound of gold. Okay, I admit I also paid $20 for postage, but it's still a cost I can take in the long run to avoid smelling too much SO2.

:mrgreen: 

Göran


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## patnor1011 (Dec 20, 2012)

I can get it to you (200g) for 4e postage from Ireland to sweden - small package.
200g will cost here little over 3euro I think. Let me know when you run out I can help you out Goran.


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## g_axelsson (Dec 20, 2012)

Thanks Partnor, I'll remember you when I run out of SMB but I don't think there is a crisis yet. I have at least 400g left and it should be enough to cover my needs for a couple of years.
I think that all my gold plated e-scrap will not yield more than 100g of gold, probably a lot less as everybody is an optimist whenever they try to calculate how much gold they have. :mrgreen: 

Göran


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## Moo (Dec 21, 2012)

Somebody please correct me if Im wrong but if your precipitating that much gold, id be dissolving your smb in water and freezing them into ice cubes.


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## Indunil (Feb 16, 2021)

Hello every one , I am new here , thought that anyone could help me I got a situation here ,
I do have a problem that in a ore i have worked on . These were the steps I followed ,
I have washed the ore with water , then few minutes with hcl , then again with water ,
Again few minutes with hno3 ..
And again with water ..
Then I made aqua regia .
So it seems it was okay . The problem was ,

When I put a small drop in to a tissue paper and test with stannus chloride it didnt gave any difference .
I thought it was the end , eventually 
I put a drop in to the beaker the color (like a black ink drop ) appeared ,

And I tried to precipitate it with smb ,reaction happened the solution went little bit darker and again it s disappearing . No precipitate . Can anyone help please .


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## Martijn (Feb 16, 2021)

The problem probably was that you made Aqua Regia. Did you pre-mix it? 4 parts HCL to one part HNO3? 
Too much free nitric is a much seen problem new members face. Sounds like that's (one of) your problem(s). 
How much acid did you use on how much ore?
What kind of ore? So many kinds of ore out there. How much are you planning on processing? Steady amounts every week, or just this one time one batch? 
Did you have a sample assayed? Knowing what is in there is the starting point to determine the best way of extraction. And thus the cheapest way.
Acid leaching of ores is not recommended often here, mostly discouraged for a couple of reasons, Cyanide leaching can be used sometimes, it depends on what the ore is made up of. Need input from others in that field. 
Martijn


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