# aqua regia and alluminum foil



## john_paok (Nov 8, 2012)

I made AR to refining gold from 500mg black sand and I put aluminum foil in it (after filtering) 15 grams but it can't disolving complete. I can't precipitate with SMB. I'm not sure how much gold my material has. The AR is 80ml Hcl acid and 20ml HNO3 because I suppose black sand contain 3% gold. 

I upload pic after boil. May it is gold? I have and pic with dust of gold after pannig. Can I do something with this to ensure if it's gold???

Thanks


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## butcher (Nov 8, 2012)

John,
The pictures really help in understanding how to reply.

If you had not shown the lower picture of your gold with black sand, and I all I saw was the top picture with your description of what you did, I would say all you had was iron with some gold dissolved in the broken beaker.

Because many people take a lot of black sand with minor amounts of gold and try to process them, I see that is not what you are doing; it looks like you have gold concentrate with minor impurity of black sands involved.

Your picture on the bottom of gold with minor amounts of black sand changed my mind, now I say you have gold with minor amounts of iron, the aluminum will reduce the iron from solution with your gold.

Looks like you cooked the solution too hard, remember gold chlorides are volatile and you could fume off gold this way.

Chemistry glass is expensive; I would use a corning casserole dish from a second hand store. That with a hot plate (solid iron top) to heat the corning wares dish to do the reactions in, and a few canning jars to hold solutions.

I would not have used aluminum in the reaction.

You had gold and iron in solution, if you would have removed free nitric acid from the aqua regia, diluted, and filtered off the solution, and then have used ferrous sulfate (iron sulfate) to precipitate gold, you would have left most of the iron in solution and ended up with a more pure gold precipitate. You should not have trouble precipitating gold from this solution if you removed free nitric acid using proper procedures, but if you did have trouble precipitating cementing on copper would have been a much better idea, this way iron and copper stay in solution as the gold with minor contamination would cement out.

Using only the amount of nitric needed and no more to dissolve the gold in your aqua regia can save you many problems.

For each gram of gold use 3.8ml HCl and 0.95ml HNO3 (you may not need to use this much nitric acid so add it in increments as you heat and evaporate solution), excess HCl is no problem.

When you cemented with aluminum you cemented all metals below aluminum in the reactivity series of metals, in with your gold including iron from the black sands.

You have some nice gold there, I am afraid you are going to loose some of that gold, if you do not study some more before trying processes on it.

After studying you can put this gold back into solution and separate the iron,

I suggest studying some more in Hoke’s book before trying this again.


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## john_paok (Nov 8, 2012)

thanks,

the book is toooo much 

the jar broken when I put dist. water  in this prossece.

I know the problem with nitric acid moreeee now!!!

the AR disolve and iron? if I put sulfuric acid to disolve some iron is good idea? the problem is the iron only?

I melt this powder with borax but I can't take some gold-iron or something mettal. it was a black like carbon.
how can I calculate how much gold my material has??? every solution it had more nitric acid and I drop it every time. 
if I put little mitric 3ml in 500mgr of black sand? I had put 20ml in 500mgr of black sand and then I put 150 ml dist. water and I supposed neutrualize nitric acid.


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## butcher (Nov 8, 2012)

Iron and gold will amalgam in a melt.

Sulfide from black sand can cause problem in melt (or acids), roasting the material red hot with iron can help to remove sulfide as SO2 gas, then a smelt with a flux to make iron oxides go into slag glass. The gold would still need refined in acids.

You already have gold flakes, easier to dissolve in acid (roasting the gold to remove sulfides can help improve it before using acids).

The Hoke's book may be hard but not losing your gold, and getting your gold pure is well worth the trouble.

Black sands are normally iron and sulfide compound, this is why some black sands stick to a magnet (magnetite), while hematite is also an iron oxide.

How are you separating the gold flakes from the black sand? From panning the concentrated material?
The reason I ask is to be able to get an idea if it your gold is heavier than the black sands and stays in your pan when sand is panned off.


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## john_paok (Nov 8, 2012)

I read the book fast especially in gold and cement methode after A.R. yes, with cooper is best choise becouse I'll remove copper with nitric acid yessss!!! 

yes, the gold is not heavier than the black sand (this is a problem?) But it has and gold flakes heavier and dust also. I put on it nitric acid, boil little, wash it and leach.


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## butcher (Nov 8, 2012)

John,
If gold is not heavier than black sand it most likely is not gold, Iron sulfides can look like gold, they will float off in a gold pan, where gold will stay behind in the pan after the black sand floats away, Iron sulfide Pyrite is called fools gold, because many people have been fooled thinking it is gold.

I do not know if you have pyrite or real gold, try roasting some of it red hot and then use acids to remove iron, sulfuric acid would dissolve iron, although some iron oxides sulfuric will not, but these would not be a problem in further test, anything left rinse it in water well, dry and weigh then, use HCl, and a little bleach (sodium hypochlorite), (used to wash white clothes), heat this to remove chlorine gas, this will dissolve gold, test a drop of this solution on paper towel, add a drop of stannous chloride solution (made from tin and HCl), if violet purple color there is some gold, filter solution, and add SMB to precipitate gold, do not add too much more SMB than the weight of gold, using your stannous test to tell when no gold is in solution, no violet color, if there is still much iron the color of solution could remain yellow or green even with no gold dissolved, your test will tell where gold is or is not.

John,
Reading and understanding Hoke's book is very important why would a man have a treasure map like this book and not get that valuable map read? Even if I could not read or was blind, I would hire some young boy or girl to read that book to me so I would know where the treasure was.


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## john_paok (Nov 9, 2012)

ok I'll try to take more of this flakes and test it.

thanks.


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## butcher (Nov 9, 2012)

Put flake in gold pan add some sand pan the material if flakes flow out of pan before sand it is not gold, gold is very heavy, compared to sand, pyrite flakes are lighter than sand.

If you can just get some of the suspected gold flakes with no sand, torch them they should melt into gold, if they are gold, but if they are pyrite you will smell sulfur dioxide gas from them and they will not melt to gold.

When roasting gold it will still look like gold after being red hot, pyrite will not look like gold.

Try smashing them gold is malleable and will smash, pyrite will not it will break apart as flakes.

Put a several flakes in a spot plate or white plastic spoon, add several drops of HCl, add a drop of bleach, let spoon sit in sun for a while, add stannous chloride let sit and watch for violet color (even pyrite can have some gold in it).

A Field test for gold, where you may not want to carry acids with you, in an old table spoon add 2 parts dry ammonium chloride powder, 1 part ammonium nitrate, add about half as much suspected gold powder ( do not need too much of this mix), heat spoon over a flame till the dry mix melts and fuses into a syrup, keep heat till mixes well but does not dry out, wash this syrup into a small jar like a baby food jar or test tube, add several drops of HCl, now use your stannous chloride to test for gold.


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## shaftsinkerawc (Nov 9, 2012)

Pyrites are brittle and will crush into smaller bits then to powder. Mica's will seperate into flakes and move around in the pan very easily. Some fine flat gold will wash and stay on top of the sands as it has too much surface area to settle. Also you have to be careful if you have any rounded gold as it will move very easily during panning.


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## john_paok (Nov 9, 2012)

I put HNO2 acid in black sand boil it a little and I had see the gold color. then I put H2SO4 acid and boil again and the gold flakes disapear.

*result*:
my material does not contains gold. (I' hope this is good test)


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## butcher (Nov 9, 2012)

John, 
very good test.
This test saved you much wasted time and money trying to get gold from iron.


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## patnor1011 (Nov 9, 2012)

john_paok said:


> I put HNO2 acid in black sand boil it a little and I had see the gold color. then I put H2SO4 acid and boil again and the gold flakes disapear.
> 
> *result*:
> my material does not contains gold. (I' hope this is good test)



HNO2 is Nitrous acid
HNO3 is Nitric acid


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## john_paok (Nov 10, 2012)

patnor1011 said:


> john_paok said:
> 
> 
> > I put HNO2 acid in black sand boil it a little and I had see the gold color. then I put H2SO4 acid and boil again and the gold flakes disapear.
> ...



sorryyy tes...is nitric acid HNO3


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## john_paok (Nov 10, 2012)

butcher said:


> John,
> very good test.
> This test saved you much wasted time and money trying to get gold from iron.



thank butcher,

In which step? after reaction HNO3 (nitric acid) with my material? when I see the iron-gold flakes? and how can I do that? 
If I put H2SO4 (sulfuric acid) my iron-gold flakes disappear.


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## john_paok (Nov 10, 2012)

May the material which collect the gold is stainless.

I put stainless item in my material with nitric acid and I can't see stainless item draw gold.

More over I test flakes with SnCl (tin cloride) and I see flakes hardly changed.
May it is gold with some other metal?

Must I going in goldsmith and test my flakes to find if these flakes contain gold or not?


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## Geo (Nov 10, 2012)

SnCl only test for gold in solution. it will not effect solids much more than hcl would. i believe you tried to process more than you can handle at one time. try again, but instead of doing many liters at a time, try a test tube this time. take a small sample of your flakes and place them in a test tube or other small glass container. add enough hcl to cover the material. add nitric acid 1 drop at a time. after each drop, shake the container and look at the material to see if any of it is dissolving or you have a color change. stop adding nitric acid when you get a nice yellow color. now you can test this solution with SnCl and watch for a deep purple color. if it turns purple, Eureka, you have found gold.


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## john_paok (Nov 10, 2012)

can I calculate this amount for gold? it's 24karat gold? but whay if I make AR in my material after HNO3 nitric acid can't take some gold? in the last pics may the powder has gold?
may is tooo little?


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## Geo (Nov 10, 2012)

john_paok said:


> can I calculate this amount for gold? it's 24karat gold? but whay if I make AR in my material after HNO3 nitric acid can't take some gold? in the last pics may the powder has gold?
> may is tooo little?



after you do this experiment, you will know how much gold you have in a certain amount of material. 

weigh the sample of material. dont pick through it, just take a general sample from the middle. weigh a certain amount whether its 10g or 10 ounce's. digest it in AR and precipitate the gold. it will precipitate as 24K if theres no base metal. rinse, wash, dry and weight whatever precipitates out. now you have numbers you can use to calculate how much gold is in a certain amount of material.


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## Geo (Nov 10, 2012)

another thing, try to obtain some sodium bisulfite, sodium sulfite, sodium meta bisulfite. SO2 gas will also precipitate gold.


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## john_paok (Nov 10, 2012)

Geo said:


> SnCl only test for gold in solution. it will not effect solids much more than hcl would. i believe you tried to process more than you can handle at one time. try again, but instead of doing many liters at a time, try a test tube this time. take a small sample of your flakes and place them in a test tube or other small glass container. add enough hcl to cover the material. add nitric acid 1 drop at a time. after each drop, shake the container and look at the material to see if any of it is dissolving or you have a color change. stop adding nitric acid when you get a nice yellow color. now you can test this solution with SnCl and watch for a deep purple color. if it turns purple, Eureka, you have found gold.



Geo,

The process completted, the results is on the pic


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## Geo (Nov 10, 2012)

there may be a slight color change but nothing dramatic like one would expect if the flakes was truly gold.


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## john_paok (Nov 10, 2012)

what can I do? may it contain gold? may I do AR with equal amount of these flakes and cement with copper and boil until become powder?


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## Geo (Nov 10, 2012)

the stannous test you showed in the photo showed little to no gold. if you did the dissolution on the test batch correctly, the stannous test should have been some shade of purple. i dont know what to tell you but that you should repeat the sample test. another negative should lead you to consider there may not be any gold in your material.


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## butcher (Nov 10, 2012)

John, it is a little hard to follow everything here in this thread there seems to be a bit of language difficulty,

If I understand this thread, so far it looks like you have pyrite fool’s gold.
Where did this material come from the river? And how did you collect it and separate it from the sands?

Real gold is easy to tell if it is gold.

It is very hard to prove pyrite is real gold.

I think sometimes it is hard for Gold miners to believe what they know or see, as they easily are blinded by the sparkle of gold. 

Try the different tests discussed in this thread, if this is gold it should be easy to tell, if not then believe what you see, do not let that sparkle of this material blind you.


I have taken people panning, who have been thinking pyrite was gold, some places in our rivers are full of pyrite from decomposed granite, These people see tons of these flakes of pyrite and try to separate it from the sand (I think that would be harder than panning gold),they think they are going to be rich, as the rivers are full of pyrite.

I show them how to find gold and how to pan, then they see how the tiny piece of gold is all that is in the pan after the rocks, gravels and sand is panned from the pan, the gold is heavy it stays in the bottom of the pan (yes a fine flat flake may float from oils or an air bubble but that is rare), gold density is around 19.3g/ml, sand has a density of around 2.3g/ml, and pyrite around 5g/ml, lead has a density of about 11g/g/ml.

They also learn there is much more pyrite than gold.

Try this shave off some lead with a pocket knife about the size of your golden color flakes, put both of these in an old pie pan,put a little water in, roll the water around in the dish, to see which one of these materials are carried around the dish by the moving water, if the gold moves before the lead throw it away it is not gold, if the lead floats around before your golden flakes then it is gold keep it.


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## john_paok (Nov 12, 2012)

I didn't pay this material. I'll try to find other material with river. 

other question is that, How much Urea in grams must I put before put SMB to neutralize HNO3 68% nitric acid on Aqua Regia to be sure the nitric acid is completly neutralize? What happen if I put each gram Urea for each ml HNO3 nitric acid  68% which I use?

my Aqua regia is made with HCl acid 37%
and HNO3 acid 78%


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## butcher (Nov 13, 2012)

Limit the use of nitric acid to dissolve gold.

Add 3.8Ml HCl per gram of gold.
Cover gold in HCl measured and heat medium.
Measure out in another jar, 0.95ml HNO3 per gram of gold. (We will add this slowly to dissolve gold, and only use as much as we need).
Add a little HNO3 with a pipette; let it react, when reaction stops add another pipette full.
Stop adding nitric acid before the last of gold dissolves, concentrate solution (more gold will dissolve as solution concentrates), and evaporate to thick red solution.

The goal is to use up all of the nitric acid, and not have any free nitric is solution before all of the gold is dissolved, and concentrate the solution, (if gold not completely dissolved at this point you can add couple of drops of HNO3, and a ml of HCl and evaporate some more, I will usually leave a little gold remaining and dissolve it in the next batch, I also add a small sprinkle of sulfamic acid (H3NSO3), just to insure all nitric is gone, the sulfamic reacts with nitric acid leaving a little sulfuric acid in solution and nitrous oxide gas.

HNO3 + H3NSO3 → H2SO4 + N2O + H2O 

The sulfuric acid formed in this reaction can help to remove lead from solution as lead sulfate.

This way I only have one evaporation and no free nitric.


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## john_paok (Nov 20, 2012)

how much sulfamic acid add on your solution? (ex. each ml of nitric acid?) yes and I. After too much solutions !!! I add as little as possible, only what I must add to disolve gold. And then you add SMB or boil-evaporate your solution?

thanks for all info butcher


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## goldsilverpro (Nov 20, 2012)

To neutralize 1 ml of excess 70% nitric, it takes about 1.5 grams of sulfamic acid, preferably dissolved in water first. Hot 80C water will dissolve about 470g of sulfamic acid per liter. Room temp water will dissolve about 150g/l.


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## Palladium (Nov 20, 2012)

Just for the sake of knowing, how much urea does it take to accomplish the same? Also smb would be a good one to know just for scientific purpose of showing waste.


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## butcher (Nov 20, 2012)

Fools gold, Iron Pyrite can fool a new miner into thinking he has found his wealth in gold, if the miner is uneducated in how to tell the difference in pyrite or gold.

Pyrite can also fool a new refiner into thinking he has gold dissolved in solution it can give a nice yellow color looking like pure gold dissolved in solution.

Iron can give several colors to solutions yellow, green, brown, and red.

An educated refiner will test his solution to see if gold is in solution stannous chloride (violet color for gold in solution) or ferrous sulfate crystal (brown precipitate ring if gold in solution).

This refiner will also test the solution for iron, Hokes book on page 100 she gives instructions to test for iron in solution, using ammonium or potassium thiocyanate (blood red test for iron in solution), and potassium ferro cyanide (prussian blue dye color with iron in solution).


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## goldsilverpro (Nov 20, 2012)

Palladium said:


> Just for the sake of knowing, how much urea does it take to accomplish the same? Also smb would be a good one to know just for scientific purpose of showing waste.


There probably is some known relationship, maybe, with urea but I don't know what it is. I do know that I tried to neutralize a solution, using urea, that had a large nitric percentage (50% v/v) and ended up with 3 or 4 inches of crystals on the bottom and about 2" of crystals floating on top, in a bucket. Very undesirable. I switched to sulfamic and, lots more volume but everything worked smooth.


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## john_paok (Nov 21, 2012)

Palladium said:


> Just for the sake of knowing, how much urea does it take to accomplish the same? .



yes but I'll try with sulfamic acid (H3NSO3). This method is better because....

*I also add a small sprinkle of sulfamic acid (H3NSO3), just to insure all nitric is gone, the sulfamic reacts with nitric acid leaving a little sulfuric acid in solution and nitrous oxide gas.

HNO3 + H3NSO3 → H2SO4 + N2O + H2O

The sulfuric acid formed in this reaction can help to remove lead from solution as lead sulfate.*

butcher explain very good... 

2 in 1 neutralize nitric acid and leave lead.



> To neutralize 1 ml of excess 70% nitric, it takes about 1.5 grams of sulfamic acid, preferably dissolved in water first. Hot 80C water will dissolve about 470g of sulfamic acid per liter. Room temp water will dissolve about 150g/l.



if I neutralize all nitric acid (HNO3) with 1.5 sulfamic acid it is correct method? Because I'm not sure how much nitric acid is the "excess" in my solution.

the sulfamic acid is only as a powder?


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## nōnāgintā trēs (Dec 11, 2012)

I'm still trying to understand how the man cracked his boiling flask?


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## Geo (Dec 11, 2012)

i wasnt there and cant say with certainty, but from the description, i would say it was thermal shock due to the high heat generated from adding aluminum foil to a solution high in hcl.


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## Palladium (Dec 11, 2012)

I have some aluminum based parts i was running just yesterday. Had them in a 4000 ml beaker sitting in water to help slow it down some. The water got so hot from the beaker and the reaction it was almost boiling to. Whole lot of heat generated with aluminum and it's fast to happen.


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