# SMB



## rich_2137 (Apr 21, 2014)

Hi all
Just wondering if gold be dropped with SMB if excess nitric it in the solution?
As I've just dissolved some gold powder with AR and then dropped the gold using SMB, left it a day or so and now it's redisolved!? but I thought SMB wouldn't work if you have free nitric in the first place? Any help would be great!

Cheers 
Richard


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## solar_plasma (Apr 21, 2014)

> but I thought SMB wouldn't work if you have free nitric in the first place?



Well, actually it didn't work, if the gold redissolved, right?


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## rich_2137 (Apr 21, 2014)

solar_plasma said:


> > but I thought SMB wouldn't work if you have free nitric in the first place?
> 
> 
> 
> Well, actually it didn't work, if the gold redissolved, right?


Thanks that was really helpful!


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## joubjonn (Apr 21, 2014)

i have seen it re-dissolve when i thought i had used up all the nitric. it looks like a nice drop and then you see it dissolve. especially if you have a big volume of fluid your working with. it only take's 1ml of nitric to dissolve a gram of gold. i try and remember that. a little pinch of sulfamic will take care of it. or sometimes even another addition of SMB.


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## Pantherlikher (Apr 21, 2014)

You've been a member this long and have not read about redissolving gold drop?

SMB drops gold, Excess nitric + HCL redissolves it. You could do that back and forth untill nitric runs out is my guess. Or add more gold untill no more dissolves.
Or, evaporate to a syrup, add HCL, evaporate, add...etc. just like described in alot of posts on here.

B.S.


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## solar_plasma (Apr 22, 2014)

I didn't realize, that you wrote, you ask for help in your last sentence, sorry for my short answer above. It was just in my eyes a valid answer to one of your questions.

How much excess nitric do you expect to have in your solution? If it is only a little, I would prefere gold button method. If it is a lot, I'd use sulfamic or evaporation. Going on with additions of smb would not be a good option. This will co-precipitate impurities, the last gold comes very slowly down and itis wasting smb.


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## rich_2137 (Apr 22, 2014)

Pantherlikher said:


> You've been a member this long and have not read about redissolving gold drop?
> 
> SMB drops gold, Excess nitric + HCL redissolves it. You could do that back and forth untill nitric runs out is my guess. Or add more gold untill no more dissolves.
> Or, evaporate to a syrup, add HCL, evaporate, add...etc. just like described in alot of posts on here.
> ...



Hi 
Yes I have been a member hear for a while and no I haven't heard of it otherwise I wouldn't of posted this!
I'm only just starting to understand the AR process as I usually only us AP and HCL/CL as I'm am very confident in process and have been successful in my yields!


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## rich_2137 (Apr 22, 2014)

solar_plasma said:


> I didn't realize, that you wrote, you ask for help in your last sentence, sorry for my short answer above. It was just in my eyes a valid answer to one of your questions.
> 
> How much excess nitric do you expect to have in your solution? If it is only a little, I would prefere gold button method. If it is a lot, I'd use sulfamic or evaporation. Going on with additions of smb would not be a good option. This will co-precipitate impurities, the last gold comes very slowly down and itis wasting smb.



I don't think there is much as it's took several days to redissolve,the gold powder plus the solution was left a week or so before adding SMB 
I'll try adding sulfamic first, thanks for the advice

Rich


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## Pantherlikher (Apr 22, 2014)

So...you're saying you have not done and research on AR?
A simple search of "excess nitric" brings up alot of results. The first bunch I just found indicate ways of testing and ridding the solutions of excess nitric acid.

Not being mean or snobbish or anything but it's a question a "newbie" that does not bother to read and learn would ask.

Following the directions exactly...4HCL- 1Nitric acid ratio is too much. Several posts state it's better to add nitric alittle at a time and wait for reaction to stop...

As well as the answer to rid excess nitric...

B.S.
...I'm still reading and learning the AR process and wont attempt it yet...


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## rich_2137 (Apr 22, 2014)

I'm not saying I haven't done it before , I've been successful s few times with AR and I do understand the process I've just never came across this before so I've had no need to research it, Sorry if I'm not allowed to ask for a little help and you seem to be going off what my original question was but in don't matter now anyway!


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## necromancer (Apr 22, 2014)

rich_2137 said:


> I'm not saying I haven't done it before , I've been successful s few times with AR and I do understand the process I've just never came across this before so I've had no need to research it, Sorry if I'm not allowed to ask for a little help and you seem to be going off what my original question was but in don't matter now anyway!




Hi rich, dont be discouraged, try the sulfamic acid to get rid of the extra nitric, then try drop with smb again
remember that it only takes about 1ml to dissolve 1 gram of gold of excess nitric in AR

the next time you make your AR ad the nitric slowly with a pipette or eye dropper


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## arsenic123 (Apr 22, 2014)

rich_2137 said:


> solar_plasma said:
> 
> 
> > > but I thought SMB wouldn't work if you have free nitric in the first place?
> ...



The best way to remove excess nitric acid is :
Put the aqua regia solution into a big evaporating dish. Now add a little sulphuric acid, stirring all the time, and working slowly, as it might spatter. Use about an ounce or less of the sulphuric acid to each quart of liquid. Now boil the solution down gently, to a syrup, being careful not to spatter. 

As per the great Hoke.


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## FrugalRefiner (Apr 22, 2014)

arsenic123 said:


> The best way to remove excess nitric acid is :
> Put the aqua regia solution into a big evaporating dish. Now add a little sulphuric acid, stirring all the time, and working slowly, as it might spatter. Use about an ounce or less of the sulphuric acid to each quart of liquid. Now boil the solution down gently, to a syrup, being careful not to spatter.
> 
> As per the great Hoke.


Do NOT boil. You will lose values. If you check the introduction in either of the copies in my signature line, youll find a discussion of evaporating vs. boiling.

Dave


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## butcher (Apr 22, 2014)

Hoke used the word boil, when evaporation should have been used, if you read Hoke's carefully you will see that she did not actually mean to bring the solution to a boil, actually she warns against it, She used a steam bath (which was not hot enough to boil the aqua regia solution, pay attention to page 227 Hoke's book (Losses), where she warns against boiling the solution.

Even where she uses the word boil she cautions against spatter of the liquid, (which happens when you boil), on page 44 she talks about the evaporation process and says to lower the heat (before you get to the point of boiling) or spattering the solution, page 55 she says a steam bath is advised (the solution would not get hot enough to boil), page 119 she gives advice on a good temperature (that would not boil aqua regia) and warns do not let it spatter (boil), again on page 147 she advices a large evaporating dish and a steam bath to evaporate (not boil the solution), page 175 evaporation of solution...

Basically evaporate the solution, do not boil the solution where you will spatter your gold all over the lab.


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## arsenic123 (Apr 23, 2014)

butcher said:


> Hoke used the word boil, when evaporation should have been used, if you read Hoke's carefully you will see that she did not actually mean to bring the solution to a boil, actually she warns against it, She used a steam bath (which was not hot enough to boil the aqua regia solution, pay attention to page 227 Hoke's book (Losses), where she warns against boiling the solution.
> 
> Even where she uses the word boil she cautions against spatter of the liquid, (which happens when you boil), on page 44 she talks about the evaporation process and says to lower the heat (before you get to the point of boiling) or spattering the solution, page 55 she says a steam bath is advised (the solution would not get hot enough to boil), page 119 she gives advice on a good temperature (that would not boil aqua regia) and warns do not let it spatter (boil), again on page 147 she advices a large evaporating dish and a steam bath to evaporate (not boil the solution), page 175 evaporation of solution...
> 
> Basically evaporate the solution, do not boil the solution where you will spatter your gold all over the lab.



Wow, thanks Butcher. It seems you have by hearted the hoke books with page numbers..  

Thanks for the info. So what if we boil the AR solution to a very low heat?? At very low heat it won't boil and its as good as evaporation, right?? We can always keep an eye on AR to make sure it doesn't reach boiling level.


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## arsenic123 (Apr 23, 2014)

FrugalRefiner said:


> arsenic123 said:
> 
> 
> > Do NOT boil. You will lose values. If you check the introduction in either of the copies in my signature line, youll find a discussion of evaporating vs. boiling.
> ...



Thanks Frugal. I will definately check it.


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## g_axelsson (Apr 23, 2014)

arsenic123 said:


> Wow, thanks Butcher. It seems you have by hearted the hoke books with page numbers..
> 
> Thanks for the info. So what if we boil the AR solution to a very low heat?? At very low heat it won't boil and its as good as evaporation, right?? We can always keep an eye on AR to make sure it doesn't reach boiling level.


I think the word you should use is "heat" not boil, and the temperature you should aim for is almost simmering. When there is vapor formed right above the liquid surface but no bubbles formed or reaching the surface that's the sweet spot. When bubbles breaks the surface small droplets are formed and brings small amounts of values with them into the air. There's an interesting story on the forum where one person made a purple stain on the side of his trailer when boiling gold chloride...

Göran


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## steyr223 (Apr 23, 2014)

I hate to be the guy who keeps asking the
Same question, but there is a very divided 
Group about boiling or evaporating

Now i know not to splatter my gold all over the place
I mean i realized all those purple spots on the corningware
Ment something :roll: 

Seriously can you boil if you cover with a watch glass so no values splash out,can you loose values any other way.other than splashing out from boiling

I have asked this before amd have read 100's of threads
With both topics some say yes some say no

I think free chemist did an experiment witha large amount
Of au in an enclosed transparent chamber, after boiling the gold you could see the gold all over the chamber very far from the actuall boiling solution

To me it did not look like it was just from splatter but maybe something else 

I have put many paper towls over my solution while steaming and tested they have never shown positive 
But i am still leary

Thanks steyr223 rob


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## g_axelsson (Apr 23, 2014)

Rob, why are you so eager to boil? Show me a thread where someone is telling it's okay to boil when denoxing without anyone correcting them.

When denoxing a solution we want to get rid of the nitric through evaporation. If we boil the solution there are a lot of small droplets that is created and drifts away as a mist, taking gold with it. It isn't just the big splashes that transports off the gold.
To put a lid on the vessel would let the nitric flow back into the vessel and that isn't what we want to do.

Boiling is a tool that has it's place but not when denoxing. We usually boil AR for dissolving problematic alloys and mixed scrap. This is done because boiling agitates the solution and the added heat makes reactions go faster. But then it is recommended to do it in a boiling flask, a reactor or in a beaker with a watch glass as a lid. AR condenses on the lid or in the neck and flows back into the vessel, keeping the gold in the vessel.

Göran


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## butcher (Apr 23, 2014)

Read Hoke's she discusses this very question.
15 minutes reading the page numbers I gave above for Hoke's book, with what we have discussed here will give you a better understanding of the process.


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## FrugalRefiner (Apr 23, 2014)

From the introduction in my versions of Hoke's book:



> Evaporation - Hoke discusses reducing the volume of solutions in various
> chapters throughout the book. This process is known as evaporation. In
> other areas, she writes about boiling solutions for various reasons. It is
> important to understand the difference. Boiling is used in processes like
> ...


Dave


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## steyr223 (Apr 24, 2014)

Exactly whay i mean

Evaporation - Hoke discusses reducing the volume of solutions in various
chapters throughout the book. This process is known as evaporation. In
other areas, she writes about boiling solutions for various reasons. It is
important to understand the difference
Boiling is used in processes like
dissolution and washing.

----------***************
When a solution containing values is being
boiled, the vessel should be covered with a watch glass or be otherwise
similarly contained
----------***************

. Boiling creates tiny eruptions at the surface of the
solutution as bubbles pop, and can propel values out of the vessel. The
watch glass captures these minute droplets and causes them to drop back
into the vessel. When evaporating a solution to reduce its volume, the
solution must be kept below the boiling point to avoid any bubbling
which could cause a loss of values, as the vessel is not covered during
evaporation. Do not boil when evaporating. (page 44, 57)

Yes i have read this many times
Sorry if this is interrupting the original thread 
This brings up a whole new subject 
When asked mutiple times if covering during evaporating impedes the process the answer has been no but she says not to cover
I will attempt yo find the thread but one of the major contributors of this form says many a times it is ok if you cover 
I am not trying to be difficult i am just ttrying to understand :mrgreen: 

Göran it's not that i want to boil this is not a problem anymore as i add only the right amount of nitre now( i only 
Needed to evaporate once for 26 hrs to never whant to again) 
But it is much easier to turn up the flame and walk away
Thanks steyr223 rob


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## g_axelsson (Apr 24, 2014)

steyr223 said:


> ...
> When asked multiple times if covering during evaporating impedes the process the answer has been no but she says not to cover
> I will attempt yo find the thread but one of the major contributors of this form says many a times it is ok if you cover
> I am not trying to be difficult i am just trying to understand :mrgreen:
> ...


To cover up while evaporating is totally wrong, it diminishes the evaporation.
Instead of cranking up the heat, remove the cover, use a low and wide vessel (for example an evaporating dish) and put a fan blowing air past the opening of the vessel and it will go a lot faster.

Göran


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## steyr223 (Apr 24, 2014)

Thanks Göran
I do exactly that or did exactly that even though i was
Confused i considered it a more logical approach
But thanks now idont have to wonder

Back on track sorry  
Thanks steyr223rob


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## freechemist (Apr 24, 2014)

Can you remember the loud, whistling sound, created by the boiling contents of a overheated teapot, the softly simmering sounds of the same pot, heated cosily on a stove? - Both sounds originate from gaseous water (water-vapour), escaping through a small opening at the top. Hearing them, means becoming aware of an ongoing process of evaporation.

The boiling point of a liquid is defined as the temperature, e.g. displayed by a thermometer, placed in the gas-phase over a boiling liquid substance, in equilibrium with 100% of the given substance in the gas-phase, at a given pressure. Thus:

-The process, creating the sounds of the teapot, is commonly called "evaporation".
- Covering e.g. a beaker with a watch glass, while boiling it's contents minimizes losses due to splashing, but does not make evaporation impossible.


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## Pantherlikher (Apr 24, 2014)

I see both points...To boil or not...
Boiling as Harold said a few times allows bubbles to burst, atomizing PMs which can escape with the evaporating liquids. 

I don't know about you but if there is a possibility of loss, I'd rather go the safe route. 

I'm also working on using a projection screen TV lense as a heat magnifier.
Experimenting with solar heat. I'm building a heater for the swimming pool as well as evaporation. Depending on how much heat I can generate at the focal point using mirrors.

B.S.


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## steyr223 (Apr 25, 2014)

Freechemist. Hows the projecting going (seems like you
Always have something goin on  

Pantherlikher




I have 2 more. With stands so they can spin as to track
The sun

I attempted to heat up borax in a dish 
It worked but only kept one part molten while
The rest was not

I guess if i had a melting dish the size of a dime and
Actually put it exactly at the focal point...........46inch,,,,........

I am also working on a microwave gun :mrgreen: 

Steyr22 . Rob


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## Pantherlikher (Apr 25, 2014)

Nice...
Automatically tracking the sun is what stumps me. I can't afford to go buy something so I'm deep in thought about a substitute.

I also have thoughts about using mirrors from the focal point to a centralized burn spot. 
Just ideas bouncing around the vast emptiness of the brain pan.

B.S.


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## Anonymous (Apr 25, 2014)

For excess Nitric I either use a pre weighed amount of gold to use up Nitric and/or I use Sulfamic acid.

Frankly the Sulfamic acid works pretty effectively so I don't have to evaporate down, use sulphuric, or any other other methods mentioned. I add Sulfamic until there is no reaction even on vigorous stirring and then leave for half an hour. Don't worry if there are crystals left over in the bottom because you'll then be filtering it before dropping it.

It's a right royal pain in the behind learning to get the right amount of Nitric especially if you're trying to dissolve your product rapidly and don't have days to wait but it does come with experience OP so don't worry. I would guess that every single guy on this forum has overcooked it on the Nitric more than once so do you're not alone.

Regards

Jon


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## steyr223 (Apr 25, 2014)

Curios
I had always just added a pinch of sulfumic
But spaceships you say add till reaction is done
When do you add when still hot on the burner

What would the actuall chemical reaction be for this
I mean what actually happens 
H2s04 +Hn03

Thanks steyr223 rob


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## goldsilverpro (Apr 25, 2014)

steyr223 said:


> Curios
> I had always just added a pinch of sulfumic
> But spaceships you say add till reaction is done
> When do you add when still hot on the burner
> ...


Theoretically, it takes about 1.54g of sulfamic acid to treat 1ml of 70% HNO3. Sulfuric acid and nitrous oxide (laughing gas) are produced.

http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=51&t=10799&p=105096&hilit=sulfamic+acid#p105096


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## rich_2137 (Apr 25, 2014)

Thanks for all the advice guys! :-D


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## steyr223 (Apr 25, 2014)

Thats a lot of sulfumic
So i take it, spaceships,
You would have to be getting pretty darn
Close 

Thanks gsp
Steyr223 rob


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## goldsilverpro (Apr 25, 2014)

Thanks, Rob.

It's all on here Rob. You just have to look for it.


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## jason_recliner (Apr 26, 2014)

I'm still in the process of recovering my first solution(s).
I've added SMB to one of my more recent AuCl attempts, and watched nothing happen at all. I know it probably has way too much NO3 in it. But not even an initial drop. I kind of expected that anyway, having read about excess nitrate, and was surprised to read the above post about it dropping and slowly redissolving.

Now, will the added SMB (or part of it) slowly evaporate out at room temperatures? That is, either the sulphur leaves and the sodium remains, or does it all go, or all stay? I ask because it has a smell, which suggests it's slowly leaving.

Also on the subject of evaporating nitrate. I have a Goran/Jason coffee maker but don't currently have anything resembling a watchglass. Why the watchglass if not boiling it? If hot (say 80-90°C) vapours hit the colder watchglass, will they not just condense and drop back into my solution? Wouldn't it be better to let it all out, as long as I'm not also boiling away my gold?

There's talk about both sulfamic and sulphuric. I have ready mixed sulphuric battery acid tucked away somewhere. Is a few drops of that useful?

[Edit: Oops. Didn't realise there was more than one page of forum replies when posting this. Some questions already answered. Don't use watchglass. Sulphamic, not sulphuric. Still interested about the SMB.]


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## solar_plasma (Apr 26, 2014)

@jason


> Still interested about the SMB



Maybe there are more factors,I don't see right now, but those different observations can be explained by the speed of reaction, which increases with concentration and temperature. So, higher concentration of excess nitric and higher temperature might redissolve the gold before it is even visible. Also the concentration of gold, contaminants, the amount of smb and even sunlight will influence the speed and quality of reaction.

I think until now I had only few precipitations, that looked completely similar. Typically only, if the solutions are quite clean, really free of oxidizers and have comparable concentrations of gold.


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## g_axelsson (Apr 26, 2014)

If you need a watch glass (not for this occasion though) then just use a saucer, preferably a glass one. Great to keep the nitric in when dissolving gold or platinum. Just as you say, it condenses and drops back into the reaction. A type of reflux process.

Göran


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## Clneal2003 (Jul 31, 2014)

necromancer said:


> rich_2137 said:
> 
> 
> > I'm not saying I haven't done it before , I've been successful s few times with AR and I do understand the process I've just never came across this before so I've had no need to research it, Sorry if I'm not allowed to ask for a little help and you seem to be going off what my original question was but in don't matter now anyway!
> ...



Odd question. I just got my first bottle of CP Nitric and before I get busy... I wanted to know if Nitric will dissolve a plastic pipette? I know it doesn't play nice with some plastics.


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## Geo (Aug 1, 2014)

High density polymers hold up better to nitric acid than just plain rubber. HDP is the material trash bags are made of. Most clinical pipettes are made of HDP so unless it's something I have never seen before, any clinical pipette will work for nitric acid usage.

As an aside, spaceX's "space ship 1" uses ground up rubber tires and hot nitric acid as its main fuel source.


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