# Q on neutralising nitric acid in AR



## JanOlivier (Dec 14, 2017)

Hi people sorry bit confused about neutralising nitric acid out of AR read in the form that some members use sulfumic acid to neutralise nitric acid out of AR but also read in Hoke's book see used sulfuric acid to do so. 

So my qeastion is can you use both if so what is the benefits and differences of each? 

I know you can use urae. But it is difficult to get here. I haven't started any thing yet just asking questions as i tray and figure out how to go about everything


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## anachronism (Dec 14, 2017)

Jan

Please use the correct chemical terms. It's Sulphamic or Sulfamic, and Urea. It might seem a little strange for me to sound particular on this however you need to be accurate in what you are working with.

Sulphamic acid (the Brit and correct spelling 8) ) reacts with the Nitric acid and forms a by product of Sulphuric Acid. Sulphuric Acid is used to precipitate Lead from your AR if any is present. 

Personally I would use the Sulphamic Acid. I hope that helps.

Jon


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## cosmetal (Dec 14, 2017)

anachronism said:


> Jan
> 
> Please use the correct chemical terms. It's Sulphamic or Sulfamic, and Urea. It might seem a little strange for me to sound particular on this however you need to be accurate in what you are working with.
> 
> ...




*"Sulphamic acid (the Brit and correct spelling 8) )*

:shock: Gadzooks! :shock:

Jon, 

I just did a Google search for "Sulphamic" acid and everything that came back was "Sulfamic" acid! I wonder if that's because my search initiated in the USA and not from a "Brit" location? 

Remember, the Queen said that if us Yanks spell it correctly - we get to use the word.  Does this mean I have to stop using my Sulfamic acid?  

In jest only,
James

(Note to self - why do I feel like I just poked a tiger with a sharp stick? :shock: :? :shock: )


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## anachronism (Dec 14, 2017)

Heck no, not at all. 8) 

You're right though- your Goggle search results are very dependent upon the part of the world you're in. On a side note you can even SEO a website to work best for a County let alone a State or a Country these days too.


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## JanOlivier (Dec 14, 2017)

Page 44 Hoke's book Removing exis nitric acid "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."

Please can we keep to the topic. Both spellings are correct debentent where you are in the world. If i wanted an English lesson i whould have asked for one


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## jimdoc (Dec 14, 2017)

JanOlivier said:


> Please can we keep to the topic. Both spellings are correct debentent where you are in the world. If i wanted an English lesson i whould have asked for one


 

Famous first steps to the way out the door.


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## Lino1406 (Dec 14, 2017)

Before adding sulphamic acid dilute your nitric acid otherwise the reaction will not end. Let it an hour or more with occasional steering.


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## JanOlivier (Dec 15, 2017)

Lino1406 said:


> Before adding sulphamic acid dilute your nitric acid otherwise the reaction will not end. Let it an hour or more with occasional steering.



Thanks for giving me a nice answer. When I find sulphamic acid will tray it. But want to know if you can use sulphuric acid. As Hoke's does in her book? Cose sulphamic acid is hard to come by in South Africa (a lot of chemicals though) and if you do find it you pay trough ur a** or the company doesn't sell to the public


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## g_axelsson (Dec 15, 2017)

On this forum we stress correct spelling, if you don't spell it correct we assume you didn't find anything when doing a search. Correct spelling can be the difference between success (sulfite) or failure (sulfate) in refining.

The correct answer here would have been "Thank you!" and not a snide remark. Not insulting people that is trying to help you often results in more help... just saying.
Just look at this answer, I rather wrote a comment about your attitude than giving you some help. I could have done that but I don't feel it would be appreciated based on your previous reply.

Göran


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## Lino1406 (Dec 15, 2017)

I think Ms. Hoke referred to sulphamic acid, so the letter setter is the one to blame (in this case). A hint for that is "use an ounce for a quart of liquid". By the way, hydrochloric acid addition, followed by evaporation is the "classic" way of "neutralizing nitric acid" (2-3 times)


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## anachronism (Dec 15, 2017)

JanOlivier said:


> Page 44 Hoke's book Removing exis nitric acid "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."
> 
> Please can we keep to the topic. Both spellings are correct debentent where you are in the world. If i wanted an English lesson i whould have asked for one



I answered your question you ungrateful oik. If anyone else wants to help you them the they can but I'm done with helping rude people.


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## nickvc (Dec 15, 2017)

JanOlivier
You do need to pay attention to your spelling as we deal with some very nasty reactants and when mixed even worse and we have members whose first language is not English so to help them and others we stress correct spelling of reactants to save possible disasters.
If you do not premix your AR and only add small amounts of nitric to your Hcl you should not need to worry about excess nitric, easier said than done when you are new but it saves money, chemicals and problems.


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## JanOlivier (Dec 15, 2017)

Just wanted to apologise to people I've been rude too. It's not my intention I can be sometime a bit fowerd and I apologise for it. Spelling is a bit of a problem as English isn't my home language. And sometimes really relay on the spell check. 

For those who still helped me and still answered. I thank you and I really appreciate it. Will go work on my spelling and do more learing in the processes available


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## anachronism (Dec 15, 2017)

Jan

Apology accepted. 

Jon


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## g_axelsson (Dec 15, 2017)

Thats better!  

We didn't complain on the spelling, we tried to help you with it.

Just like you, English isn't my first language, so spelling that I think is perfect English is probably way off. I just hope all my friends here on the forum would correct me when I make too ghastly mistakes.

The complains were about your attitude, which seems to have changed to the better. :mrgreen: 

I'm not very fond of the expression "neutralizing the nitric acid" as neutralize in chemistry is to bring the pH to 7. I prefer to say "removing the nitric acid" or even better, denoxing. There are a number of ways to remove the nitric acid from aqua regia...
http://goldrefiningwiki.com/mediawiki/index.php/Denoxing

Welcome to the forum, I hope you will learn a lot here.

Göran


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## JanOlivier (Dec 15, 2017)

Thanks Göran will definitely learn a lot from you guys


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## goldsilverpro (Dec 15, 2017)

Nick gave the correct answer.

First, you cover the material you want to dissolve with a little excess HCl and, if the material is high gold or high iron or other slowly dissolving metal, you heat it to about 150F. If high copper, the reaction, itself, will heat it. Use a big beaker to help prevent foamovers - I usually use a beaker that will hold at least 5 times more that my estimate of the total volume of acids I will use. Then, you add the nitric in increments, waiting for each increment to quit reacting before adding more, and then stop adding nitric when you get no reaction with an addition, you won't ever use excess nitric and will, therefore, never have to de-NOx the solution before dropping the gold. During the last 30 years, I have never used urea (hate it) and the only time I used sulfamic acid was in a special solution that was 50% nitric. I have also never evaporated the solution, as in Hoke - well, maybe once or twice, when I had partied the night before and really overadded the nitric. 

The nitric increment method above becomes second nature after doing it a few times. More details are on the forum. About 10 years ago, when I first introduced this nitric method to the forum (over and over until it took), it took people (except lazersteve) about a year before they tried it. Now, only the newbies that have been watching lousy Youtube videos premix their AR. The nitric in increments method is now standard forum practice. It would behoove anyone to master this method. I forgot to mention that, by using the nitric in increments, you also have more control over foamovers and the rate at which the red-brown NO2 fumes are produced. Also, for each 30g of gold or base metals, it will take about 125ml of HCl or muriatic acid and 25ml of nitric. This is only ballpark. I usually start with 150ml of HCl per 30g because excess HCl doesn't cause any problems. Also, if you use up all the HCl, it will stop dissolving gold no matter how much nitric you add. Extra HCl is a safety net. This whole discussion assumes your HCl is at least 30% by weight and the nitric is, at least 67% by weight. Muriatic acid is usually about 30.45% HCl, by weight.

I also have found that tap water dilution of the AR solution tends to reduce or eliminate the adverse effects of too much nitric. I automatically add 3 times water to my AR solutions before filtering the solution, as preparation for dropping the gold. This 3 to 1 dilution also drops out essentially all of the silver as chloride. This allows the silver to be filtered out and then enables all the gold to drop out, usually with no extra SMB (I use sodium sulfite) needed. This dilution also makes it easy to produce a crystal-clear filtered solution. This creates a little more waste but, to me, since it makes everything go much smoother, it is worth it.


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## g_axelsson (Dec 15, 2017)

GSP's approach with incremental additions is great, especially when working with a known amount of gold, like lots of carat gold. Sometimes it is hard though to know how much gold you have, like when you have wet gold foils. Just take it easy and let the reactions take it's time.

I have a similar approach as GSP but with a twist. When I work with a known amount of gold I usually calculate 3-4 ml HCl per gram of gold and 0.75 ml nitric acid. I start with all HCl and up to 2/3 of the nitric acid if I'm working with solid pieces. For foils or fine powder I carefully add the nitric in small additions to avoid a boilover.
When the initial 2/3 of the nitric acid has been added and the reaction dies down it is usually just small pieces of undissolved gold left on the bottom of the beaker. I aim to dissolve around 90% of the gold in the first run.
Now I pour off the gold chloride into another beaker and add fresh HCl to the rest of the gold, the amount I use is depending on how much gold there is still undissolved. 

This avoids the problem of having very weak aqua regia at the end and it is easy to see if I have a reaction or not before adding more nitric acid. All that gold chloride solution is diluting the aqua regia at the end and makes it easy to add too much nitric acid. With less volume and stronger AR it's easier to control the reaction and see if there still is nitric acid working.

Göran


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## Shark (Dec 15, 2017)

Sulfamic acid will react with the nitric acid, which causes the neutralization of the nitric while converting the sulfamic acid to sulfuric acid. The sulfuric acid produced causes the lead to drop out of the solution as lead sulfate. This in effect allows you to use only one chemical addition to accomplish both reactions. 

Urea doesn't actually neutralize the nitric acid the way sulfamic acid does. When using urea you will still need to add sulfuric acid at a later stage to drop the lead out, as the urea won't create the sulfuric acid. 

Also if you do the small additions of nitric acid to your AR as GSP suggests, you may not even need the sulfamic acid. It is still nice to have on hand so you can test for excess nitric if the need should arise. I bought two pounds of sulfamic acid three years ago, I used one pound in the first year after learning about sulfamic acid. I have used less than half a pound in the past two years while producing 5 times the amount of gold since following GSP's method. 

With Urea you still need the sulfuric acid (two chemicals). With sulfamic acid, you accomplish two steps with one chemical.

I hope that makes sense.


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## goldsilverpro (Dec 15, 2017)

You don't need to know how much gold you have. Louie, the guy I learned it from and the best refiner I've ever known, kept a gallon of nitric and a gallon of HCl under the hood and added a little of each back and forth, directly from the jugs until it was finished. He really has a knack for knowing what was needed. I do the same thing except i always have an excess of HCl to start with, so I don't run out of the HCl. I don't really care about how much nitric I need - I just add it out of the jug in increments until it doesn't react. If you don't add an excess or, at least, just the perfect amount of HCl, the reaction will stop when it is used up, even if you use more nitric. Therefore, there can be a short period of confusion until you figure out that you need more HCl and, during that period, you may have thought you needed more nitric and dumped in too much. This happened to me a couple of times when I had 10 other things going on. Since then, I make sure I start with plenty (a definite excess) of HCl. In my past posts, I have told people to calculate both, because I know if they don't, they'll end up using too much nitric.

A neat thing about aqua regia, is that it takes about the same amount to dissolve a gram of many common metals we run up against. A gallon of AR will dissolve about 2 pounds of gold, 2 pounds of iron,2 pounds of nickel, or 2 pounds of copper. Easy to calculate what is needed, ball park wise, and refining is a ball park art/science, in most cases. That's my humble opinion, of course. You have you learn what you can get away with and what you can't get away with.


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## snoman701 (Dec 15, 2017)

I know that sulfamic is preferred by others, but I now prefer to transfer the liquid (if it was a leach of computer chips) then use copper powder. A little excess copper simply begins the precipitation of the gold. I doubt it will be 99.9 though, so if that is your goal, a secondary refine will likely be necessary.


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## snoman701 (Dec 15, 2017)

g_axelsson said:


> GSP's approach with incremental additions is great, especially when working with a known amount of gold, like lots of carat gold. Sometimes it is hard though to know how much gold you have, like when you have wet gold foils. Just take it easy and let the reactions take it's time.
> 
> I have a similar approach as GSP but with a twist. When I work with a known amount of gold I usually calculate 3-4 ml HCl per gram of gold and 0.75 ml nitric acid. I start with all HCl and up to 2/3 of the nitric acid if I'm working with solid pieces. For foils or fine powder I carefully add the nitric in small additions to avoid a boilover.
> When the initial 2/3 of the nitric acid has been added and the reaction dies down it is usually just small pieces of undissolved gold left on the bottom of the beaker. I aim to dissolve around 90% of the gold in the first run.
> ...



I really like this method and have used it quite a few times. 

The only thing I like more is using a gold button to consume the last bit of free nitric.


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## Shark (Dec 15, 2017)

snoman701 said:


> I know that sulfamic is preferred by others, but I now prefer to transfer the liquid (if it was a leach of computer chips) then use copper powder. A little excess copper simply begins the precipitation of the gold. I doubt it will be 99.9 though, so if that is your goal, a secondary refine will likely be necessary.
> 
> 
> Sent from my iPhone using Tapatalk



I am working on a lot now that I am using copper pipe to cement out the PM's. I ran into a problem and could not get the last bit to drop out of the solution. (it was a mix of many different types of materials) While it cemented out, it took on the shape of the copper pipe it was replacing. I really wish I had taken more pictures of it, as I have never had this same problem before. Even the cemented residues has a different look a to it than normal. 



goldsilverpro said:


> A neat thing about aqua regia, is that it takes about the same amount to dissolve a gram of many common metals we run up against. A gallon of AR will dissolve about 2 pounds of gold, 2 pounds of iron,2 pounds of nickel, or 2 pounds of copper. Easy to calculate, ball park wise, what is needed, and refining is a ball park art/science, in most cases. That's in my humble opinion, of course. You have you learn what you can get away with and what you can't get away with.



I never thought about it in that manner, but very useful to know those numbers.


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## JanOlivier (Dec 15, 2017)

Thanks everyone for the great feed back. I realy like GSP's aprouch and going to try it as soon as my lab is up and running. Will then post of the progress 

At the moment I'm still busy building my lab and depopulating circuit boards and learning on this forum 

I work at a printing company and we have wat whe call the grave yard where all our copier machines go if thay beyond repair. The main boards are quite nice and some have up to 5 BGA chips and hundreds of ic chips on one main board. And lots of ics on the rest of the boards. Of 2 machine I have scraped about 2kg of different kinds of chips mostly look like old memory chips from Ram cards and just under 1kg of gold plated pins will post pic asoon as i can. 

I'm still learning to find the best way of processing it all and before i get started. Like most of the chemicals are hard to find or so dam expensive like 55% nitric acid cost me ZAR500 for 2.5L So i dont just want to jump into thing before i waste


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