aqua regia and alluminum foil

[john_paok]

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

 

[butcher]

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.

 

[john_paok]

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.

 

[butcher]

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.

 

[john_paok]

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.

 

[butcher]

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.

 

[john_paok]

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

thanks.

 

[butcher]

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.

 

[shaftsinkerawc]

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.

 

[john_paok]

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)

 

[butcher]

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

 

[patnor1011]

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

 

[john_paok]

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

sorryyy tes...is nitric acid HNO3

 

[john_paok]

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.

 

[john_paok]

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?

 

[Geo]

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.

 

[john_paok]

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?

 

[Geo]

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.

 

[Geo]

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

 

[john_paok]

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