Help regarding Agua regia concentrations please <3

[Lenmiscate]

Hi friends

Thanks for you time first, im not a chemist, but i want to make some Aqua regia, i red how but the concentrations i have on my acids are different, my hydrochloric acid is at 30% and my nitric acid is at 55% so the question is what is the right volumes or proportions i should combine please to make Agua regia?

Thanks in advance friends.

 

[goldsilverpro]

In most cases it is better to add the 2 acids separately rather than premix them. What do you want to dissolve with the aqua regia? In what quantity?

 

[Lenmiscate]

Thanks for your answer, I want to dissolve gold, but I see everyone is using hydrochloric acid at 35% and nitric acid at 65% but my acids are 30% and 55% respectively, so not sure what adjustments I need to do, or if the proportions 4:1 will work for me. And i want to test with 10 grams of gold, is there a formula or something where play with the concentrations?

Thanks

 

[lanfear]

What goldsilver pro is saying, is that the concentrations dondt matter. You will use a bit more acid but the jobb will be done.

Dont premix your AR.

If you tell us wath you want to dissolve we can help a bit more.

But the standard way to do it is to cover you material in hcl. Heat it up to it steams and then add a few ml of nitric.
Cover the beaker and when the red NOX GAS die downs the nitctric is almost gone. Check the leftover materil. If there is still metalls then add some more nitric.
Continiue this uintill there is no reaction when you add nitric. Add more hcl/ distilled water as needed. Then it is done..

 

[Lenmiscate]

Oh i see now, i will try then, i want to dissolve gold, let me try the way you are saying, thanks again.

 

[FrugalRefiner]

i want to dissolve gold

That's a broad statement. Do you want to dissolve karat gold from jewelry, gold from ewaste, gold in ore? They might all need different handling.

Dave

 

[goldsilverpro]

Actually, most people use muriatic acid, which is about 30-31% HCl, along with technical grade 67% HNO3. Both of your acids are about 75% of the strength that typical technical grade would be. It you truly want to pre-mix them, I would use about a 4 to 1, HCl to HNO3, by volume, although anything close to that is fine. It would take approximately 130ml of your 30% HCl and 35ml of your nitric to dissolve 1 troy ounce of gold - these numbers can vary slightly. Try to use only as much nitric as needed without adding any excess. Any excess can cause problems when you try to precipitate the gold.

Study the forum before attempting this.

 

[kurtak]

Study the forum before attempting this.

This is the best advice given so far in this thread :!:

Along with that I "highly" recommend you read C. M. Hokes book which you will find the links to here

:arrow: http://goldrefiningforum.com/phpBB3/viewtopic.php?f=54&t=19798#p201558

The reason for the above is that it is not as simple as make up AR (Aqua Regia) in a ratio of 3/1 or 4/1 hydrochloric acid/nitric acid --- although those ratio's will certainly dissolve gold --- mixing your AR in those ratio's can & most likely will lead to problems

The biggest problem can be ending up with having "free nitric" after you have dissolved your gold which will then result in problems precipitating the gold back out of your solution (getting your gold back)

In other words - free nitric means all the nitric is NOT used up - in order to precipitate you gold back ALL the nitric MUST be used up

Another problem is base metals - if you are trying to dissolve gold that is alloyed with base metals the ratio of 3/1 or 4/1 will not dissolve all your gold --- that is because it takes MORE acid (nitric) to dissolve a gram of base metal then a gram of gold

Also - the conditions under which you dissolve your gold can make a difference on how much nitric you use - conditions such as heat - no heat - open vessel - closed vessel - vacuum - no vacuum etc. etc.

The "general" rule of thumb is that it takes 3 or 4 ml of 31.45 % Hydrochloric acid along with 1 ml of 70 % nitric acid to dissolve 1 gram of "pure" gold --- however that rule is NOT an absolute because of the above reasons

When base metals are involved - it takes 3 - 4 times more nitric to dissolve a gram of base metal then it takes to dissolve a gram of gold (the HCl also needs to be increased)

So its not as simple as asking --- what is the "ratio" of HCl/nitric if the percentage of my acid is different then the normal 31.45 % HCl & 70 % nitric

That's why as goldsilverpro said - you need to read/study the forum before diving into refining (dissolving) gold & why I in addition say to read Hokes book

Failing to take this advise will only result in otherwise running into problems/questions that can at least to some degree be avoided - & the first problem/question you will run into is likely to be --- where did my gold go when I tried to precipitate (drop) it - I added SMB but no gold

You will run into problems anyway - & we are here to help you with those problems --- BUT - many problems can "first" be avoided by taking some time to read/study the forum & read/study Hokes book FIRST

Kurt

 

[kernels]

Everyone 'wants to dissolve Gold' . . .

There is a massive difference in the process of dissolving old jewellery vs. E-waste, if you are more specific with your questions you will get better answers.