Are the various nitrates equal in the AR Solution

[79Aurum]

For a proper Aqua Regia Solution to dissolve and recover pure gold from unrefined Au nuggets and flakes, does the choice of nitrate utilized matter?

HNO3 Sodium Nitrate
Ca(NO3)2 Calcium Nitrate
KNO3 Potassium Nitrate

 

[Yggdrasil]

For a proper Aqua Regia Solution to dissolve and recover pure gold from unrefined Au nuggets and flakes, does the choice of nitrate utilized matter?

HNO3 Sodium Nitrate
Ca(NO3)2 Calcium Nitrate
KNO3 Potassium Nitrate

This is not "proper" AR but poor mans AR.
I would guess that Calcium Nitrate would have higher yields, but I can't say if the Ca will have issues down stream.

 

[vgecas]

I would go with Sodium either Potassium nitrates, because Calcium may form insoluble salts.

 

[vgecas]

a copy from some pdf from google:

The Solubility Rules

1. The nitrates, chlorates, and acetates of all metals are soluble in water. Silver
acetate is sparingly soluble.
2. All sodium, potassium, and ammonium salts are soluble in water.
3. The chlorides, bromides, and iodides of all metals except lead, silver, and
mercury(I) are soluble in water. HgI2 is insoluble in water. PbCl2, PbBr2, and PbI2
are soluble in hot water. The water-insoluble chlorides, bromides, and iodides are
also insoluble in dilute acids.
4. The sulfates of all metals except lead, mercury (I), barium, and calcium are
soluble in water. Silver sulfate is slightly soluble. The water-insoluble sulfates are
also insoluble in dilute acids.
5. The carbonates, phosphates, borates, sulfites, chromates, and arsenates of all
metals except sodium, potassium, and ammonium are insoluble in water but soluble
in dilute acids. MgCrO4 is soluble in water; MgSO3 is slightly soluble in water.
6. The sulfides of all metals except barium, calcium, magnesium, sodium, potassium,
and ammonium are insoluble in water. BaS, CaS, and MgS are sparingly soluble.
7. The hydroxides of sodium, potassium, and ammonium are very soluble in water.
The hydroxides of calcium and barium are moderately soluble. The oxides and
hydroxides of all other metals are insoluble.

Notes

1. Bismuth and antimony salts hydrolyze in water to give basic salts. These basic
salts are soluble in dilute acids but are not soluble in water.
2. Solutions of iron(III), lead, tin, mercury(II), copper, and aluminum salts, when
boiled, may hydrolyze to give precipitates of the hydroxides or basic salts of these
metals.

 

[Yggdrasil]

I would go with Sodium either Potassium nitrates, because Calcium may form insoluble salts.

If one uses the Nitrates to make poor mans Nitric, the Calcium Nitrate creates Calcium Sulfate aka Gypsum.
Which can hold some liquid but is insoluble in the liquids.
Which means you do not have to freeze it to precipitate the salts.
So for that use Calcium Nitrate has an advantage, besides having two Nitrate ions per Calcium ion.

 

[79Aurum]

I read that it is the ion transfer and sum total of the ion charge which produces the Au precipitation out of solution. Also, the sodium vapor is Toxic while the Calcium is not, I read.

Pls explain further: "So for that use Calcium Nitrate has an advantage, besides having two Nitrate ions per Calcium ion."

 

[Yggdrasil]

I read that it is the ion transfer and sum total of the ion charge which produces the Au precipitation out of solution.

Pls explain further: "So for that use Calcium Nitrate has an advantage, besides having two Nitrate ions per Calcium ion."

That has nothing to do with precipitating Gold or other metals.
All salts a made out of an Ion pair.
Search Google for Ion. to create Nitric from any nitrate you add Sulfuric acid, the Sulfuric acid will grab the Na, K or Ca ion and create its counterpart Sulfate.
Replacing it with a H+ Ion effectively making Nitric HNO₃ from NaNO₃/ KNO₃ or Ca(NO₃)₂
The beauty of Ca(NO₃)₂ is that it create CaSO₄ which is a solid and can be filtered out without freezing.

Edit: This is a simplified explanation for this discussion.

 

[79Aurum]

OK, but.. "Aqua regia is primarily used to produce chloroauric acid, the electrolyte in the Wohlwill process for refining the highest purity (99.999%) gold."

Google:

Dissolving gold[edit]​

Pure gold precipitate produced by the aqua regia chemical refining process
Aqua regia dissolves gold, although neither constituent acid will do so alone. Nitric acid is a powerful oxidizer, which will actually dissolve a virtually undetectable amount of gold, forming gold(III) ions (Au3+). The hydrochloric acid provides a ready supply of chloride ions (Cl−), which react with the gold ions to produce tetrachloroaurate(III) anions ([AuCl4]−), also in solution. The reaction with hydrochloric acid is an equilibrium reaction that favors formation of tetrachloroaurate(III) anions. This results in a removal of gold ions from solution and allows further oxidation of gold to take place. The gold dissolves to become chloroauric acid. In addition, gold may be dissolved by the chlorine present in aqua regia. Appropriate equations are:

Au + 3 HNO₃ + 4 HCl ↽−⇀ [AuCl₄]−+ 3 NO₂ + H₃O++ 2 H₂O

or

Au + HNO₃ + 4 HCl ↽−⇀ [AuCl₄]−+ NO + H₃O++ H₂O.

Solid tetrachloroauric acid may be isolated by evaporating the excess aqua regia, and decomposing the residual nitric acid by repeatedly heating the solution with additional hydrochloric acid. That step reduces nitric acid (see decomposition of aqua regia). If elemental gold is desired, it may be selectively reduced with reducing agents such as sulfur dioxide, hydrazine, oxalic acid, etc.[5] The equation for the reduction of oxidized gold (Au₃+) by sulfur dioxide (SO₂) is the following:

2 [AuCl4]−(aq) + 3 SO₂(g) + 6 H2O(l) → 2 Au(s) + 12 H+(aq) + 3 SO₂−4(aq) + 8 Cl−(aq)

Edit by Moderator:
I fixed the formulas

 

[Shark]

To cool poormans nitric we need a freezer or at least a refrigerator. No one would want to use their home unit to do this in. (Some can do it outside at the right time of the year). With calcium nitrate we have no need for a cooling system and it produces a larger volume or strength of acid at the same time.

If a very high purity gold is desired then the use of poormans nitric is not the way to go. 3N gold can be made with poormans but getting higher purity is an effort, but doable. Targeting 5N or higher is near, if not impossible out side a lab environment, and even then chemical purity is a major factor. For 5N plus everything is a major factor.

 

[Yggdrasil]

OK, but.. "Aqua regia is primarily used to produce chloroauric acid, the electrolyte in the Wohlwill process for refining the highest purity (99.999%) gold."

Google:

Dissolving gold[edit]​

Pure gold precipitate produced by the aqua regia chemical refining process
Aqua regia dissolves gold, although neither constituent acid will do so alone. Nitric acid is a powerful oxidizer, which will actually dissolve a virtually undetectable amount of gold, forming gold(III) ions (Au3+). The hydrochloric acid provides a ready supply of chloride ions (Cl−), which react with the gold ions to produce tetrachloroaurate(III) anions ([AuCl4]−), also in solution. The reaction with hydrochloric acid is an equilibrium reaction that favors formation of tetrachloroaurate(III) anions. This results in a removal of gold ions from solution and allows further oxidation of gold to take place. The gold dissolves to become chloroauric acid. In addition, gold may be dissolved by the chlorine present in aqua regia. Appropriate equations are:

Au + 3 HNO
3 + 4 HCl ↽−⇀

[AuCl
4]−
+ 3 NO
2 + H
3O+
+ 2 H
2O
or

Au + HNO
3 + 4 HCl ↽−⇀

[AuCl
4]−
+ NO + H
3O+
+ H
2O.
Solid tetrachloroauric acid may be isolated by evaporating the excess aqua regia, and decomposing the residual nitric acid by repeatedly heating the solution with additional hydrochloric acid. That step reduces nitric acid (see decomposition of aqua regia). If elemental gold is desired, it may be selectively reduced with reducing agents such as sulfur dioxide, hydrazine, oxalic acid, etc.[5] The equation for the reduction of oxidized gold (Au3+) by sulfur dioxide (SO2) is the following:

2 [AuCl4]−(aq) + 3 SO2(g) + 6 H2O(l) → 2 Au(s) + 12 H+(aq) + 3 SO2−4(aq) + 8 Cl−(aq)

I'm a bit curious, what is the intent with this post?
It is not directly related to your original question, which revolved around poor mans AR.
And the formulas are unreadable in this form.
AR is used not only for dissolving Gold but also Pt and to some degree Pd even if Nitric alone will do that.

 

[Lino1406]

Notes
To create poor man aqua regia you can spare sulfuric acid, hydrochloric acid is enough, hence no issue with calcium sulfate.
In the above formulas, replace SO2-4 with SO4-2
To dissolve gold, Cl2 is needed besides Cl- and it is provided by aqua regia

 

[Shark]

Notes
To create poor man aqua regia you can spare sulfuric acid, hydrochloric acid is enough, hence no issue with calcium sulfate.
In the above formulas, replace SO2-4 with SO4-2
To dissolve gold, Cl2 is needed besides Cl- and it is provided by aqua regia

My lack of chemistry knowledge being what it is I would like to hear more details on the use of hydrochloric for making nitric.

 

[Lino1406]

My lack of chemistry knowledge being what it is I would like to hear more details on the use of hydrochloric for making nitric.

H+ from HCl + NO3- from any nitrate give HNO3. Equilibrium reaction

 

[Yggdrasil]

My lack of chemistry knowledge being what it is I would like to hear more details on the use of hydrochloric for making nitric.

Not Nitric but AR.
Just add Nitrates to the HCl.

Edit.
Lino beat me to it

 

[Shark]

My bad. I miss read that it was for AR. I was thinking for making poormans nitric acid.

 

[Yggdrasil]

My bad. I miss read that it was for AR. I was thinking for making poormans nitric acid.

I think I accidentally derailed the thread by mentioning that Calcium Nitrate is good for poor mans Nitric.
It was just meant as an extra piece of information.

 

[79Aurum]

All,
My intent with the AR nitrate issue is to lessen the chance of accidental mishap hence the Calcium Nitrate. The chosen method will be conducted by others in the Philippines with little knowledge other than a recipe of method and supplied materials and equipment.
Also, smelting the unrefined Au Dust, Flake and Nugget with a borax flux first to get a gold button below a lead mat prior to any AR process also seems correct. Yes?
Thx

 

[FrugalRefiner]

I can appreciate your intent, but I would urge caution. No one wants to be responsible for someone else's injury.

Dave

 

[Yggdrasil]

All,
My intent with the AR nitrate issue is to lessen the chance of accidental mishap hence the Calcium Nitrate. The chosen method will be conducted by others in the Philippines with little knowledge other than a recipe of method and supplied materials and equipment.
Also, smelting the unrefined Au Dust, Flake and Nugget with a borax flux first to get a gold button below a lead mat prior to any AR process also seems correct. Yes?
Thx

We try to educate people here so they don’t injure themselves or others.
I really don’t like your idea much at all.
If we were discussing this with the ones that are going to do this hands on, it would be ok.
But with someone not at site at all!

Why melt/smelt it in the first place?
It is better and faster treated as Gold dust and nuggets.

 

[79Aurum]

We try to educate people here so they don’t injure themselves or others.
I really don’t like your idea much at all.
If we were discussing this with the ones that are going to do this hands on, it would be ok.
But with someone not at site at all!

Why melt/smelt it in the first place?
It is better and faster treated as Gold dust and nuggets.

"It is better and faster treated as Gold dust and nuggets." Rest assured, considering options here. If such Au is capelled in Portland Cement, could lead be added at that stage? To sell refined.
BTW, they have Chemists and Pharmacists in Asia too. AR is from the 15 Century.
And as to the quoted, what methods are you suggesting?