# Aqua Regia 1:4 VS Aqua Regia 1:3 which one is stronger?



## nattawat

Hello
I like to say that I am not a chemistry and I just wonder about this for a long time because I have someone said in this board about the ratio of Aqua Regia some say 1:3 and some say 1:4. So, I like to know which ratio is stronger and faster to dissolve a gold.

Thank you


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## 4metals

In reality the Nitric acid in aqua regia bumps a chlorine molecule off the hydrochloric acid and the chlorine and the hydrochloric solution dissolve the gold. If you mix up 3:1 acid mixture you will have a "hotter" solution which will more aggressively attack the gold. 4:1 has less nitric available so it is less aggressive. I prefer to do aqua regia reactions in closed condensed reactors and I mix up the acid at 5:1 because the effect of the condenser recycles some of the nitric.

The best method is to use as little nitric as you possibly can. Since you must use up any free nitric before you can drop the gold out of solution any extra nitric requires extra steps. So being conservative up front is the best way.


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## stihl88

Strongly dissolving the gold with a strong batch of AR is usually not the issue, making sure you use the correct amount of AR for the amount of PM you are dissolving is the key.

If you have excess Nitric in your AR solution after you have dissolved all of the PM then you will need to eliminate the excess Nitric somehow.
Some do this by adding Urea which is not recommended others do it by evaporating the excess nitric from the AR solution.

But the best way to avoid this and the preferred method to use is to have the ARM ratio correct before dissolving the said PM. Remember, you can always top up the AR solution to dissolve excess PM's by adding very small amounts of Nitric or HCL to the AR solution (1-2ml at a time) watch for a reaction to the remaining PM and keep adding small amounts of Nitric and HCL independently until the PM has been dissolved this way you ensure you have no excess Nitric to deal with after the PM has been dissolved.

I guess to answer your Question, i usually use 1:4 ratio to play it safe.
*-It Takes* *30mL* of _*70% HNO3*_ added to *120ml* of _*30% HCL*_ to dissolve *1T℥ of pure Gold* (31.1034768 grams)
*-It Takes * *1.22 ml* of _*70% HNO3*_ and *1.22 ml* of _*100% H2O*_ to dissolve *1g of pure Silver*

I will adopt this as my new signature for now :mrgreen:


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## 4metals

In practice I have found that it takes 1 liter of aqua regia (3:1 or 4:1) to digest 7.5 ounces of karat jewelry. With the issues most have of acquiring nitric, I would go with 4:1.


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## nattawat

Thank you for your helpful information. I have another question. I have seen the refining machine from the Italy. It has condenser. I like to know why they have to use condenser. In my belief, the condenser is used to convert the NOX to become a dilute nitric. Is it correct? Is it possible that gold can evaporate and the condenser is used to convert the gold back into the vessel.

Thank you


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## 4metals

The acid which condenses in the condenser is very high in nitric and has some HCl in it as well. It does contain some gold, very little, barely staining with stannous chloride. The benefit is it re-uses a percentage of the nitric acid and because the NOx load is less, the scrubber requirements are less. This results in a smaller, lower CFM, and less costly scrubber.


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## freechemist

In refining-industry-practice gold is not dissolved in aqua regia. Instead HCl and HNO3 are used in predetermined stoichiometric amounts to assure that HNO3 in final solutions is no more present in too big amounts.
Practically the process looks like this:
1.) The calculated amount of concentrated HCl (usually 32% technical grade), the raw gold (or other material), and a volume of water equal to the volume of HCl added are placed into the dissolution reactor, equipped with reflux-condenser and a line-in for adding nitric acid.
2.) The gold/HCl suspension is stirred and heated to 70-80oC. Only then a small portion of the calculated amount of 62-65%, technical grade HNO3 is added. Usually reaction begins in a few minutes, clearly visible by the evolution of brown fumes of NOx.
3.) Only then, after beginning of the dissolution-reaction the remaining amount of HNO3 is added in portions, so that the reaction never becomes too violent.
4.) After complete addition the mixture (solution) is boiled for several hours until practically no more NOx is visible in the whole reactor. The thus obtained solution containes comparatively small amounts of HNO3 and can directly be processed further on, without addition of urea or expelling the remaining amount of nitric acid.

*Stoichiometry*: Dissolution of gold affords at least 4 moles of HCl per gram-atom-equivalent of gold. In practice a 50% excess (6 moles per gram-atom of gold) is used. The gold in solution exists as the complex anion AuCl4-. Nitric acid oxidizes Au(0) to Au(III). Regardless of the composition of it's reduction products, it is best to assume that N(V) over all is quantitatively reduced to N(III). Thus a simplified redox-equation reads like this: *4 Au(0) +16 HCl + 6HNO3 => + 4 HAuCl4 + 3 NO + 3 NO2 + 9 H2O*


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## 4metals

Freechemist, 

I welcome your knowledge and background to the forum. Unfortunately the majority of our members lack the ability to calculate the proper ratio's as you stated. For them, a formula like 3:1 or 4:1 with the caveat that the nitric be added slowly as needed is the best we can do. I know for a fact that most small to medium sized refiners in the US also fit into this category. 

The analytical requirements of determining the exact proportions of the gold and silver alone is too much for some, let alone the other base metals. 

I appreciate the fact that you have listed your profession, your location, and interests on your profile page. This is not often done. I suspect that we have other professionals who monitor this forum and wish to have their background kept a secret. While there is no need to know whom you work for or when and where, it would be nice if more professionals fessed up. Then we could take some of these discussions to new heights. 

Again welcome, I hope you have seen enough to stick around.


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## Barren Realms 007

4metals said:


> Freechemist,
> 
> I welcome your knowledge and background to the forum. Unfortunately the majority of our members lack the ability to calculate the proper ratio's as you stated. For them, a formula like 3:1 or 4:1 with the caveat that the nitric be added slowly as needed is the best we can do. I know for a fact that most small to medium sized refiners in the US also fit into this category.
> 
> The analytical requirements of determining the exact proportions of the gold and silver alone is too much for some, let alone the other base metals.
> 
> I appreciate the fact that you have listed your profession, your location, and interests on your profile page. This is not often done. I suspect that we have other professionals who monitor this forum and wish to have their background kept a secret. While there is no need to know whom you work for or when and where, it would be nice if more professionals fessed up. Then we could take some of these discussions to new heights.
> 
> Again welcome, I hope you have seen enough to stick around.



That dosen't mean more of us would not like to be at the same advanced degree as the 2 of you are but we have to pass the 1st grade before we can get to the college level. 8)


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## goldenchild

freechemist,

What is the significance of adding an equal volume of water and HCL? My first instinct is to simply create more working room for the reaction. Similar to how most on the forum cut HNO3 in half by adding an equal amount of water.

Thanks and welcome 8)


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## samuel-a

Mario

By increasing the volume of the solution with water and using only the required amount of nitric they eliminate entirely the chance of not having a complete drop of the gold.

We do the same, as you know, in my inquarting tutorial it is suggested to triple the HAuCl4 volume with water to precipitate AgCl, this serves as well to combat any nitric acid left over in stu.


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## 4metals

Samuel,

I believe freechemist is talking about reactions carried out in a glass lined pressurized reactor and the acid is heated. 

The dilution you mentioned on your tutorial (well done by the way) will tend to generate more waste than most have the ability to deal with. 

I have always skipped the water and chilled the completed reaction with ice. It does melt and end up as water but the quantity of ice added is not enough to double the volume. The silver chlorides are much less soluble in cold acid and are effectively precipitated with less waste to deal with.


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## goldenchild

4metals said:


> I have always skipped the water and chilled the completed reaction with ice. It does melt and end up as water but the quantity of ice added is not enough to double the volume.



I agree with this. I never triple or even double my solutions volume. The only water introduced is the water from spraying down filters and any glassware I may have used. I would estimate it wouldn't equal enough to be even half the volume of the AR. I always get a complete drop also. If you saw my youtube video of the gold drop that was once refined gold with a very small amount of water.


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## samuel-a

4metals said:


> Samuel,
> 
> I believe freechemist is talking about reactions carried out in a glass lined pressurized reactor and the acid is heated.
> 
> The dilution you mentioned on your tutorial (well done by the way) will tend to generate more waste than most have the ability to deal with.
> 
> I have always skipped the water and chilled the completed reaction with ice. It does melt and end up as water but the quantity of ice added is not enough to double the volume. The silver chlorides are much less soluble in cold acid and are effectively precipitated with less waste to deal with.



Sure, i agree there's more then one way to skin that cat. 
On the other hand (end?), with small scale refining i do not see it as a major factor to consider. If one does get the luxury of dissolving more then 2-3 ounces at a time then it will be essential to monitor solution volumes. We are on the same page on that.

On first refining i always take the necessary steps to eliminate AgCl, on second refining i as well do not dilute gold solutions.

Thanks for the comment.


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## lazersteve

Ever since 4Metals suggested ice to precipitate the silver chloride I've been doing it this way exclusively and will never go back to diluting regardless of the scale.

The interesting thing about water is that it takes up more volume when it is frozen, so the overall soluiton volume when comparing the volume after the ice is added to the volume after it melts actually goes down.

It's obvious the ice is getting the silver chloride out as the solution's invariably have a cloud of white powder form when the ice is stirred in. The filtered solutions are 100% free of sediment and the resulting gold is free of silver without the need for any ammonium hydroxide treatment in the clean up stage.

The key factor to removing the silver chloride is to allow the solution temperature to get around 0C before filtering. If you filter while the solution is cooling down, you'll get silver chloride salt in the bottom of your filtered solution and have to repeat the process. This trick and much more is all demonstrated on my new Testing and Refining Karat Gold DVD that will be released in a few more days.

Thanks again 4Metals !

Steve


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## freechemist

@goldenchild

Adding an equal volume of water to the volume of 32% technical grade HCl means to dilute the acid to about half it's original concentration. On heating 32% HCl loses HCl-gas by evaporation, until a concentration of about 20% HCl is reached, corresponding to the constantly at about 110oC boiling azeotropic mixture of HCl and water. Thus beforehand dilution of the 32% HCl leads to elimination of unnecessary HCl-losses through heating in the following processing.


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## HAuCl4

Nice tip there freechemist!. Thanks. 8)


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## goldenchild

freechemist said:


> @goldenchild
> 
> Adding an equal volume of water to the volume of 32% technical grade HCl means to dilute the acid to about half it's original concentration. On heating 32% HCl loses HCl-gas by evaporation, until a concentration of about 20% HCl is reached, corresponding to the constantly at about 110oC boiling azeotropic mixture of HCl and water. Thus beforehand dilution of the 32% HCl leads to elimination of unnecessary HCl-losses through heating in the following processing.



This makes sense now and is very good to know. Now I understand why after a certain point AR stops working and more HCL has to be added :idea: When I first started refining I would sometimes add HNO3 when the AR reaction stopped thinking the nitric was spent. Not much would happen. But then when I added the smallest amount of HCL there would be a violent reaction sometimes creating foam overs. Really frustrating at times. Not to mention the extra time it would take to get rid of the excess nitric(one way or another). This is another example of why its good to know the "why" and not just the "how". When you know the "why" you can then come up with your own procedures that best fit you through experimenting. Thanks for sharing this with us freechemist.


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## freechemist

@4metals

To succeed in precious metals (not only gold) refining in general a sound knowledge of the chemistry behind it and the reactions going on is equally important to an in depth reading of the frequently cited "Hoky Bible" and constant learning. With your reply on my post you let me understand that I am actually wrong in this forum, because a lot of people lack this chemical background and even are not able to do the basic calculations, namely what reagents it needs to dissolve a certain quantity of gold or scrap or different metal. With this attitude of your answer the lack of fessed up professionals in the forum is no wonder.

regards, freechemist


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## lazersteve

For those of you interested in the numbers associated with freechemist's aqua regia balanced equation:

4 Au(0) +16 HCl + 6HNO3 => + 4 HAuCl4 + 3 NO + 3 NO2 + 9 H2O

4Au(0) = 4moles x 197 g/mole = 788g

32% HCl = 10.2 moles per liter

16 HCl = 16moles /10.2moles/L = 1.57L x 1000mL/L = 1570 mL

70% HNO3 = 15.8 moles per liter

6 HNO3 = 6moles / 15.8moles/L = 0.38L x 1000mL/L = 380 mL

For each gram of gold we have:

32% HCl per gram of Au:

1570 mL / 788g = 1.99 mL/g =~ 2 mL/g

70% HNO3 per gram of Au:

380 mL / 788g = 0.48 mL/g =~ 0.5 mL/g

The ratio of HCl to HNO3 =


2 / 0.5 =~ 4 parts HCl to 1 part HNO3 


Of course, in reality one must consider the base metal and silver content of the scrap. It is a simple matter of using the above equations substituting the base metal molar mass for gold and using the appropriate balanced equation for the reaction of the base metal with aqua regia.

Steve


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## Palladium

freechemist said:


> @4metals
> 
> To succeed in precious metals (not only gold) refining in general a sound knowledge of the chemistry behind it and the reactions going on is equally important to an in depth reading of the frequently cited "Hoky Bible" and constant learning. With your reply on my post you let me understand that I am actually wrong in this forum, because a lot of people lack this chemical background and even are not able to do the basic calculations, namely what reagents it needs to dissolve a certain quantity of gold or scrap or different metal. With this attitude of your answer the lack of fessed up professionals in the forum is no wonder.
> 
> regards, freechemist



......................


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## FrugalEE

Thank you Freechemist for that proceedure and explaination, particularily that part about why you diluted the HCL. Steve's numbers were also a big help. With one year of college chemistry back in '58 and some recent refreshing in my text book I was able to follow all of this thread. I find my old text "College Chemistry" by Frey to be a lot better than the newer texts I find in the library. It goes into metals a lot more. I also had Frank's Qualitative Analysis for lab. That is a cook book for identifying metal and other common ions in solution. That book has first copyright at 1917 and it look's to me like Hoke adopted parts it in her book.

FrugalEE


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## Harold_V

freechemist said:


> @4metals
> 
> To succeed in precious metals (not only gold) refining in general a sound knowledge of the chemistry behind it and the reactions going on is equally important to an in depth reading of the frequently cited "Hoky Bible" and constant learning. With your reply on my post you let me understand that I am actually wrong in this forum, because a lot of people lack this chemical background and even are not able to do the basic calculations, namely what reagents it needs to dissolve a certain quantity of gold or scrap or different metal. With this attitude of your answer the lack of fessed up professionals in the forum is no wonder.
> 
> regards, freechemist


Do I sense a little attitude developing here?

Let me give you something to ponder. 

I was a miserable student, all through school. I was fortunate to graduate from the 12th grade, and didn't know if I would until it happened. I have virtually no formal education beyond high school. (I accept full responsibility for what I am---no need for a lecture). 

As an example of my attitude through the school years, I was tested in the 5th grade, with the idea that I was unable to learn. Those responsible got the shock of their lives when the results indicated I was performing at a 9th grade level. 

So then, back to high school. I took no math classes, no science classes, no chemistry classes. I didn't know SO2 from H2NO3. I failed history and had to take a repeat class in my senior year. I slept through English class and hated physical education. I excelled in machine shop and did very well in electricity and stage craft. Not quite as well in radio and electronics (the days prior to solid state). 

At age 31 I got interested in owning pure gold (illegal in the US at that point in time). I got a copy, thanks to the kindness of a local jeweler, of Hoke's book. From that book I went forward to found an (unintentional) refining business that I sold when I retired, at age 54. 

Do I consider myself a chemist? 

Hardly.

Can I describe in fine detail how gold and other metals are refined, explaining the reactions?

Hardly.

Was I able to function as a refiner for more than 21 years? 

You do the math. 

While it does no harm to understand reactions, and I certainly endorse the process of learning, it is no more a requirement for refining than a requirement to understand how an internal combustion engine functions in order to drive a car. I dare say precious few truly understand how they operate, yet everyone drives. 

You are likely not aware, but this forum is unlike virtually all other fora on the net. Here, you are not permitted to behave like a spoiled brat. Do not come to this forum and disparage Hoke's book. That work is a masterpiece for those of us that lack formal chemical education. It was written expressly for the novice, who most likely would not benefit from more technical writing. 

Do not mock those of us that lack your education. Each of us has chosen our own course in life, and we do the best we can with that which we have at our disposal. Just as I am lost in your chemical world, I expect you would be lost in the world that I chose, that of a precision machinist working with small parts for the aero-space, pharmaceutical and defense industries. 

I demand your respect_* if you wish to have mine*_. 

I expect that you will not be handing out any further insults about the quality of those that subscribe to this forum. That is a ready recipe for trouble with me. 

Harold


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## Palladium

Reminds me of a fellow named Sue.


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## Harold_V

Palladium said:


> Reminds me of a fellow named Sue.


He will suffer the same fate without an attitude change. 

Harold


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## nickvc

As I have said before we need a like button Harold 8)


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## freechemist

@Harold

You have my respect. If it were not the case, I would not give you an answer on your reply. Your way of approaching excellence in refining and my way of doing the same are not very different. Both are based on the same virtue, namely a lot of respectable hard work which leads to abundant richness of practical experience and expertise. Besides, it's true, I am an academically spoiled brat and not only behaving like one. But you can be sure, even a lot of years at universities, performing a lot of studies and theoretical learning does not guarantee for success in refining. This,in general is not teached in academy, at least in the places, where I became my chemical education. To accomplish this there exists only the hard way, like you did it, too. You are right, everybody is able to drive a car, without knowing it's detailed functioning, but in case of malfunction it is an advantage for every driver even to know a little something about it.
Thus, I stay with that I have written in my post, based on my whole own
experience. It has never been my intention to insult any person, included yours.

Regards, freechemist


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## Harold_V

Freechemist,
My sincere appreciation for your thoughtful and respectful reply. 

I'm sure it's difficult for a person that has succeeded in the pursuit of their choosing to try to rub shoulders with those that haven't a similar background. I offer, as an example, your making reference to Hoke's book as the Hokey Bible. I get the humor, but from the position of one that lacks the education, I fully realize the importance of that book, dumbed down as it may be. That, in fact, is exactly why it is an excellent text for those that desire to learn how to refine. 

My comment about the value of her book seems a bit out of place, considering the focus of this forum tends to be in work-arounds in processing e scrap, neither of which are covered by Hoke. However, she teaches the basics that are true in almost all cases, so those that are foreign to the use of chemicals can become familiar with how they are to be applied, but especially in becoming familiar with testing procedure, including making and using test and standard solutions. Without this ability, a person is lost in the process of refining.

I worked for 26 years in the machining industry, primarily in the aero-space, defense and pharmaceutical industries, with 16 of those years running my own commercial shop. I also moderate a forum that is machine shop related. I make mention of this because I fully understand the degree of frustration you must feel when you read many of the posts on this forum. Here, just as on the forum of which I speak, there are readers that don't have a clue, therefore they must have the simplest things explained to them in terms they can understand. That's the price we must pay if we wish to share that which we know with those that have a desire to learn. It's a price well worth paying when you see the results some of these guys achieve. 

Again, thank you for your kind response.

Harold


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## 4metals

Freechemist,

From the standpoint of a chemist, you are absolutely correct in stating to be successful in the precious metal refining business you need the sound knowledge of chemistry. I completely agree, and the companies that will hire people who have a grasp on the chemistry, as you obviously do, are held to a higher standard. They are being shipped samples that have been thoroughly analyzed and in most cases also have been witnessed to produce umpire samples to settle any disputes. These prime refiners also are in competition with each other for market share and work very close to their margins. In short there is no room for error. In that scenario a sound chemical background is imperative.

Then there is an entire other world where the materials shipped to the refiners I have described above are generated. The so called collectors of the refining world. These are the people who I am talking about when I talk about professionals who keep their background a secret. I have met and worked with these collectors over the years and while some are talented chemists, others opened up a business after working for another refiner for a year or so and have succeeded. This level of the business rarely requires the level of sophistication of a prime refiner as the people sending their materials in often do not know what it is really worth. In short there is room for profit at this level. This is the so called grey area which GSP has named it. For them, mixing up aqua regia at 3:1 or 4:1 is perfectly fine, they routinely go on outside assays without ever setting up in house, they operate in a world where close enough is profitable. 

As you well know the refining world is full of secrets, this forum is unique in that we openly discuss these secrets. If you and I were to have an open discussion about a process it would sound very different than an open forum discussion where the participants are refining in everything from buckets to coffee pots. Here everyone gets a place at the table. 

As I stated earlier, I would love to have a more open participation by refiners operating on a large scale, but those discussions will be monitored and participated in by those operating on a small scale, and that is also a value in its own light. If you stay on this forum, and I would hope you will, you will find there is more here than noticed at first glance. The refining industry encompasses a huge array of materials and processes, I will be the first to admit I have learned quite a bit here on the forum from the input of those who see things a bit different than I do.


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## HAuCl4

In my country there is a saying that goes something like this: "There are some people that have a lot of university and too little of whorehouse, others have a little university and a lot of whorehouse, and yet others that have a lot of university and a lot of whorehouse".

IMO in today's world having whorehouse experience is more important than a lot of university, but welcome to the forum as I believe I can do better in both departments!. :lol:


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## goldenchild

whorehouse?


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## HAuCl4

Slang/euphemistic for "worldly experience". 

I didn't invent it, but you wouldn't believe how much of the gold mining world in south america revolves around bars and whorehouses. :shock:


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## qst42know

So there are precious metals in boob glitter? :lol: :mrgreen:


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## zachy

lazersteve said:


> For those of you interested in the numbers associated with freechemist's aqua regia balanced equation:
> 
> 4 Au(0) +16 HCl + 6HNO3 => + 4 HAuCl4 + 3 NO + 3 NO2 + 9 H2O
> 
> 4Au(0) = 4moles x 197 g/mole = 788g
> 
> 32% HCl = 10.2 moles per liter
> 
> 16 HCl = 16moles /10.2moles/L = 1.57L x 1000mL/L = 1570 mL
> 
> 70% HNO3 = 15.8 moles per liter
> 
> 6 HNO3 = 6moles / 15.8moles/L = 0.38L x 1000mL/L = 380 mL
> 
> For each gram of gold we have:
> 
> 32% HCl per gram of Au:
> 
> 1570 mL / 788g = 1.99 mL/g =~ 2 mL/g
> 
> 70% HNO3 per gram of Au:
> 
> 380 mL / 788g = 0.48 mL/g =~ 0.5 mL/g
> 
> The ratio of HCl to HNO3 =
> 
> 
> 2 / 0.5 =~ 4 parts HCl to 1 part HNO3
> 
> 
> Of course, in reality one must consider the base metal and silver content of the scrap. It is a simple matter of using the above equations substituting the base metal molar mass for gold and using the appropriate balanced equation for the reaction of the base metal with aqua regia.
> 
> Steve



do not see where you get 10.2 moles per liter to 15.8 HCl and HNO3 for me please explain why values.


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## FrugalRefiner

zachy said:


> do not see where you get 10.2 moles per liter to 15.8 HCl and HNO3 for me please explain why values.


Those are the molar values for concentrated HCl and HNO3. You can find them listed in standard tables, or you can calculate them yourself from the density of the acids.

Dave


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## zachy

FrugalRefiner said:


> zachy said:
> 
> 
> 
> do not see where you get 10.2 moles per liter to 15.8 HCl and HNO3 for me please explain why values.
> 
> 
> 
> Those are the molar values for concentrated HCl and HNO3. You can find them listed in standard tables, or you can calculate them yourself from the density of the acids.
> 
> Dave
Click to expand...


Dave was not able to thank you very much, but finding tables with those values, and densities of these two acids are very far from those values for HCl is 1.165 g / cm3 and the HNO3 is 1.4 g / cm3, or operation it is done with the density will be with the number of Avogadro? or other equation.

I did the same proportion to refine platinum (Pt), and gives me a ratio of 5/1, but I'm not sure those two values, not on where they were taken, using the reaction.

3Pt + 4HNO3 + 12HCl ==== 3PtCl4 + 8H20 +4NO


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## FrugalRefiner

It's been a while since I've calculated acid molarity, so I googled "calculate molarity from density". The first result, Calculations involving density, percent concentration, molality, has some good examples. Problem #2 calculates the molarity of 37.7% HCl.



> Problem #2: Concentrated hydrochloric acid is usually available at a concentration of 37.7% by mass. What is its molar concentration? (The density of the solution is 1.19 g/mL.)
> 
> Solution Path #1:
> 
> 1) Determine moles of HCl in 100.0 g of 37.7% solution:
> 
> 37.7 g of this solution is HCl
> 37.7 g / 36.4609 g/mol = 1.03398435 mol
> 
> 2) Determine volume of 100.0 g of solution:
> 
> density = mass / volume
> 1.19 g/mL = 100.0 g / x
> 
> x = 84.0336 mL
> 
> 3) Determine molarity:
> 
> 1.03398435 mol / 0.0840336 L = 12.3 M


Note that the density and concentration are higher than the example lazersteve used.

Hope that helps.

Dave


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## zachy

Thank you Dave,

And I remembered, while not doing that, I forgot, it's very easy, as did all the calculations for platinum, but this refining if it is a little more complex, I'm working him 150 grams of alluvial Pt, if someone It is a good method to do or a guide will show you the results soon.

a hug


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## FrugalRefiner

zachy, please be very careful! Refining platinum is very dangerous. When you dissolve platinum, you create very toxic platinum salts . We've had at least a couple of members develop serious illness and have to abandon ever dealing with it again. 

My advice would be to send it off to a refinery that's equipped to deal with it.

Dave


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## zachy

thank you very much for your advice Dave, I'm taking all appropriate action, I do everything in a fume hood with escrubber, wear gloves and respirators for acids, I'm way ahead with the process. that diseases given to friends? but they are still alive? or given a temporary allergy?


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## FrugalRefiner

zachy said:


> that diseases given to friends? but they are still alive? or given a temporary allergy?


The allergy is NOT temporary. Arthur kierski is one of the members I mentioned.


Arthur kierski said:


> the platinum salt is very dangerous to me---it gives me lung trouble as soon as it is dried


You can read a bit more in the precipitating pd from an ar solution wth copper thread. Pay close attention to Lou's warning. He knows what he's talking about.

Dave


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## zachy

Dave and thank you very much to all of the forum,
one last question, you better do against evaporation to flow? or just with the container uncovered? platinum lost you there while the evaporation takes place? or if you lost platinum while the reduction is? platinum can be evaporated? or it happens like gold in a state of auric chloride evaporates easily. I have not lost precious metal.

thank you. :mrgreen:


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## FrugalRefiner

zachy said:


> Dave and thank you very much to all of the forum,
> one last question, you better do against evaporation to flow? or just with the container uncovered? platinum lost you there while the evaporation takes place? or if you lost platinum while the reduction is? platinum can be evaporated? or it happens like gold in a state of auric chloride evaporates easily. I have not lost precious metal.
> 
> thank you. :mrgreen:


I'm not sure if I really understand your question, but I'm guessing you're concerned about losses in your processes. 

Since I'm not equipped to deal with platinum, I've followed my own advice and not processed any, so my knowledge of platinum is based on what I've read. 

I don't know if you might lose any platinum in the process of evaporating a solution, but I would suspect it's possible, as those who have become sensitized can have problems if they get near the salts in solution. If you precipitate the salts, then calcine them, it is very easy to lose some due to volatilization.

Dave


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## zachy

and I could achieve melt platinum, in a very controlled way, so I refined, it is somewhat complicated but I've managed to end up happy, and very low or even no losses, I mounted the casting process Platinum for jewelery, alloyed iridium.


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## FrugalRefiner

zachy, glad to hear from you again on this thread. It's been a while. I'm glad you're enjoying success. Please continue to be careful with the PGMs. Their effect is cumulative. Glad to hear you're doing well!

Dave


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## nickvc

I'm going to add my own warning to Daves.

Be very very careful when refining PGMs as Dave pointed out the effects are cumulative and no two people have the same tolerance to their effects, you will not realise your ill until too late.
Although you are working with a fume hood I hope you also have good scrubbing systems to scrub the fumes which are just as toxic as the solutions, you really need to have the proper equipment to refine PGMs safely so if you are making money spend some on keeping you and everyone around you healthy.


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