I made a mistake - refining Au with AR

[WillGreen]

Dear All,


I have been reading the Gold refining handbook (vol. 1) and the more I read the more nervous I get.
Instead of giving a long explanation, I thought it is better to write down what I did and let you comment on it.
The last couple of weeks have not been very good to me. First I had the problem with the crucibles and second, I have an apprentice (for three weeks) who studied jewellery making for three years but does not seem to know what he is doing.
I had to refine gold, so this is what I did so far - I stopped because I do not have enough sodium meta bisulphate to precipitate everything.
The gold is appr. 18 karat (750), containing copper and silver for the rest, nothing else. I inquartated it with copper (I know that silver is better), and made ‘cornflakes’ by casting the alloy in a bucket of water.
I put the flakes in a jar with nitric acid, which I did not dilute (the nitric is 69-70 % pure). I let it work overnight and then I poured the nitric acid of (I saved it because there is some silver in it), I cleaned the brownish mud with distilled water (no boiling, just spraying). I then took a flask, put the mud into it, covered it HCL and added nitric acid (undiluted), until there was a vigorous reaction. I then let the flask stand overnight. The following day, I filtered the solution, using a Buchner funnel, Whatman paper and a vacuum. I then started the precipitation by adding sodium meta bisulphate to the solution - this process was interrupted because I ran out of sodium meta bisulphate. Reading the handbook, I realise that I made a mistake. To begin with, I am pretty sure that I used too much nitric acid to begin with. I also did not neutralise it. I didn’t know one had to neutralise the nitric acid with urea or by heating.
At the moment, all the gold is in one flask. Some of it dropped already. Some of it is still in the solution. How should I proceed now? Should I ignore the nitric acid problem and just go on precipitating with sodium meta bisulphate or should I do something else? If so, what should I do?


Thank you for reading and with best regards,


Will

 

[butcher]

You can cement every thing using a large bar of clean copper metal, collect any powders, these will be much higher in gold than the base metal, wash these powders well with water, testing all remaining solution for values with stannous chloride.

The copper bar used to cement gold from solution, will not add copper to the powders, but will dissolve into solution as it forces gold to cement out of solution by giving the gold in solutions electrons, stirring of solution with the copper bar helps to get good contact with the copper and gold ions in solution, this is important as this is a contact process, most of the gold powders formed will fall to the bottom of the vessel, but some may stick to the copper bar, this can be brushed off into solution, (when done wash and dry, save the copper bar for using for this purpose as there may be a tiny amount of gold plated to the bar).

Here I wash the powders in a solution of sodium hydroxide, to help convert remaining chloride salts to salt water, and rinse this salt water out of the powders very well, I do this to try to remove chlorides from the powders before incineration.

Incinerate the powders to red hot keeping powders crushed and stirred with good air exposure so that any base metals can oxidize, this will also help to drive off any chlorides (if these salts were added to nitric we would dissolve gold in latter steps when we do not want to).

At this point I would suggest storing the powders until you understand Hokes book better.

These powders can be treated in dilute nitric acid and proceeding to recover and refine the gold, using the normal methods

 

[goldsilverpro]

You need sodium metabisulfite

NOT sodium metabisulfate

 

[WillGreen]

Sodium meta bisulphite, indeed, my mistake.
I am thinking about what Butcher told me. I am not sure I completely understand.

 

[leelandbullock]

also go to any hardware store and just get STUMP-OUT it percipitates out gold too. and cheaper

here is what i did when i learned. i fused gold and silver corn flaked it. then i covered the flakes in distilled water just to cover them not to drown them. then i calulated to get the correct ammount of nitric acid. 3% distiled water to nitic..

your also sopposed to calc the gold silver flakes. but i dont. and then i waited on reaction. then placed on hot plate medium heat. only added nitric acid if all the base metals were not disolved.

after the reaction. i filtered it out...left the gold in flask to see of any silver crystals formed if so i washed with distilled water and put into filer to dilute solution of silver stock.. then i washed a few more times to be sure. and started to make

AR solution. start with hydrocholoric ad the nitric in small amounts until reaction started. then let it disolve completely. here is where i think i might differ from most i dilute the AR with hydrocloric and not distilled like i do with silver stock i use water on that. then i use my stump out to percip the gold off. then filter that off and test for platinum. if its positive i add to plat stock pot and wait till there is enough for me to percip it off.

but oh i forgot. before you parcip the gold off..add only a few a FEW!!! drops of sulfuric acid to it this will get rid of any Lead that might come out with gold.

 

[WillGreen]

Hello Leeland,

Thank you.

Butcher, thank you, you too.

Leeland, this is sort of a joke - Americans will always direct you to your local Loewe’s, but I live in Ireland. We do not have such stores over here. There is no Stump Out here.
In fact, if I could find a trustable refiner over here who doesn’t ask an arm and a leg, I would not refine my own metals.
You say that you dilute your nitric acid with 3 % distilled water? Do you perhaps mean 30 %?

Butcher: you give me the advice to drop everything with copper.
What will happen otherwise?
Will I not be able to get all the gold out of my solution?
Will I be able to get all the gold out of my solution on the condition that I use a lot of sodium meta bisulphite?
Will I be able to get all the gold out of my solution but the fineness will be lower than what can expected?

The two last possibilities are acceptable to me - I can just start over. The first is not.

Could you please be so kind to comment?

Thank you.

Will

 

[butcher]

Cementing onto was only one option, Hoke's book describes using metals to replace gold in solution, I suggested using copper to cement the gold because of the free nitric in solution, and not knowing how pure your gold solution is at this stage.
Cementing using copper metal will use up the nitric in solution before gold cements out of solution as powers, your gold you will most likely need to refine it more than once with whichever process you choose, if there is something you do not understand about this process ask and we can help you with that.

Another option is to add a piece of gold to the solution and heat, the free nitric will be consumed by the added gold as long as you have enough HCl in solution, the heat somewhat concentrating the solution and making the solution attack the gold easier, heat until the nitric is consumed and no more gold will dissolve, stannous chloride tests can also help you to see when most of the free nitric is consumed (or using a prill of urea and watching for a fizzing reaction). after nitric is consumed you can dilute solution and let it sit overnight to precipitate silver chloride, decant and filter solution and then add more SMB to precipitate gold if needed.

Since you have already added SMB you may get some gold that will precipitate possibly with the silver.

You can recover all of your gold with either method above.
Cementing onto copper is easy and you can recover all of the gold, the impurity of the gold will be a little higher than if you precipitated from solution with SMB, but not so bad that good washing procedures and a re-refining would not easily clean it up.
Precipitating with SMB as long as you can get the free nitric out of the way, will give a higher quality gold powders but may also be more difficult than cementing on copper at this point.
Using more SMB without removing excess nitric at this point is a bad idea.

 

[g_axelsson]

Here I wash the powders in a solution of sodium hydroxide, to help convert remaining chloride salts to salt water, and rinse this salt water out of the powders very well, I do this to try to remove chlorides from the powders before incineration.

Hi Butcher, can you explain why you wash the gold powder with sodium hydroxide and exactly what chloride salt it is ment to remove?

You add NaOH to a mixture of metal chlorides and HCl creating metal hydroxides and NaCl. NaCl is soluble in water but so is HCl too. In incineration the NaCl isn't volatile but HCl would have gone away as gas. Many metal chlorides are soluble in water but many metal hydroxides are not.
Two of the most common contaminants is copper and silver. Copper chloride is weakly soluble in water but copper hydroxide is even worse. To get rid of copper chloride or copper hydroxide you would need to wash it in concentrated HCl. Silver chloride isn't soluble in water but adding NaOH only converts it to silver oxide which isn't soluble either. It would be better to wash it with ammonia to get rid of silver chloride.
I can only see a more contaminated end product as a result of a NaOH wash.

/Göran

 

[qst42know]

If some of your gold is on the bottom I would expect the free nitric acid is used up. This solution will keep until you can get more SMB to finish.

 

[butcher]

Here I wash the powders in a solution of sodium hydroxide, to help convert remaining chloride salts to salt water, and rinse this salt water out of the powders very well, I do this to try to remove chlorides from the powders before incineration.

Hi Butcher, can you explain why you wash the gold powder with sodium hydroxide and exactly what chloride salt it is ment to remove?

You add NaOH to a mixture of metal chlorides and HCl creating metal hydroxides and NaCl. NaCl is soluble in water but so is HCl too. In incineration the NaCl isn't volatile but HCl would have gone away as gas. Many metal chlorides are soluble in water but many metal hydroxides are not.
Two of the most common contaminants is copper and silver. Copper chloride is weakly soluble in water but copper hydroxide is even worse. To get rid of copper chloride or copper hydroxide you would need to wash it in concentrated HCl. Silver chloride isn't soluble in water but adding NaOH only converts it to silver oxide which isn't soluble either. It would be better to wash it with ammonia to get rid of silver chloride.
I can only see a more contaminated end product as a result of a NaOH wash.

/Göran

My intent here is not to remove metals from solution, with the sodium hydroxide wash (these metals are removed later in the process with acids), but to convert and remove as much chlorides as possible in a water soluble solution before the incineration of these powders, as far as the base metals we will remove them later in the process, and it does no harm to convert their chloride to oxides before the incineration process, and we are roasting these metal powders for several reasons, besides removing oils or carbon-ous trash, to remove the previous acids used or salts of those acids used on, or which formed these powders, in this case chloride salts, these could be in the form of silver chloride, lead chloride, copper chloride, or just other forms of residual acid or chloride salts in our metal powders, the other reason for incineration is to help oxidize base metals, this can be oxidizing the tin which is such a problem in solution or other base metals in the powders, oxidizing the base metals will help later when we are using acids to dissolve these base metals from our more valuable metal powders.

Gold chloride as well as silver chloride can be volatile when heated strongly, as in the roasting of the powders.

The hydroxide wash and rinses I believe can help to convert and oxidize silver helping to keep our losses down in the roasting process.
This treatment I also believe will help to convert chloride salts (like silver chloride copper chloride Etc), to oxides and at the same time help to make a water soluble sodium chloride salt easily washed away in hot water rinses. Helping us to remove most of the chloride as water soluble salts, which if left in these powders could vapor off some of our gold in the incineration process.

As you know we can have chlorides or residual acid in the powders after using an acid like HCl, as you said the salt NaCl is easily soluble and washed away with hot water, where lead or silver chloride may have formed in these powders can cause some loss of gold in the chloride fumes of the roasted materials

 

[leelandbullock]

hey, stump out.....lol

AMAZON sells it..and that site is good for anyone. i would imagin anyways. and ireland, thats cool always wanted to go there. been everywhere else. i also think comet, or ajax cleaner has what you are looking for the percipitate...i cant remember.

trying to think of anything else.

Sodium bisulfate is an acid salt with chemical formula NaHSO4. This acid salt is also known as bisulfate of soda, sodium hydrogen sulfate, sodium acid sulfate, monosodium salt and monohydrate. Sodium bisulfate has both industrial and food applications and uses in many products, including as a cleaning agent and preservative; it has the ability to lower pH levels in chemical processing for industrial applications.


Read more: http://www.livestrong.com/article/517642-what-products-contain-sodium-bisulfate/#ixzz29EzjmVEl

 

[jimdoc]

i also think comet, or ajax cleaner has what you are looking for the percipitate...i cant remember.

I don't think so.

Your link (http://www.livestrong.com/article/517642-what-products-contain-sodium-bisulfate/#ixzz29EzjmVEl) is for sodium bisulfate. We use sodium bisulfite or sodium metabisulfite.

Please spend some time studying before dispensing advice.

Jim

 

[butcher]

Ferrous sulfate (FeSO4) also called copperas is easily made by heating clean Iron in a dilute 10% sulfuric acid solution (H2SO4).

you can cut the welds from a small transformer, separate the iron core laminates, torch them to burn off shellac. store the iron dry in a plastic bag to keep it from rusting, rinse them before use and cut into small pieces then dissolve them in the heated dilute sulfuric acid, the green ferrous sulfate solution can be filtered and then heated to crystals, re-dissolved in water and a little bit of acid, and re-crystallized for higher purity of green copperas crystals, store these wet with a little sulfuric acid keep from air. a plastic bottle is what I use.

these nice green crystals can be used to test for gold in solution in a spot plate, brown ring around the copperas crystal if a drop of solution contains gold, or these crystals can be used to precipitate gold from a gold chloride solution like aqua regia or HCl/bleach solution (after oxidizer is removed of course).

http://en.wikipedia.org/wiki/Iron%28II%29_sulfate

 

[leelandbullock]

i also think comet, or ajax cleaner has what you are looking for the percipitate...i cant remember.

I don't think so.

Your link (http://www.livestrong.com/article/517642-what-products-contain-sodium-bisulfate/#ixzz29EzjmVEl) is for sodium bisulfate. We use sodium bisulfite or sodium metabisulfite.

Please spend some time studying before dispensing advice.

Jim

my bad and please be friendly, ive never had much patients for people who belittles others intelligents when they make mistakes. i was trying to help someone and i made a mistake in something i read up on the internet. its not grounds for you to demean me.


as for the poster..my apologies. actually though SODIUM METABISUFITE i think is in some cleaners. not all are going to list their ingrediants. but read and see if it contain it..



Sodium Metabisulfite is found in...

Hair Color and Bleaching (448)
Sunless Tanning (39)
Skin Fading/Lightener (39)
Anti-Aging (28)
Hair Spray (13)
Facial Moisturizer/Treatment (11)
Bronzer (9)
Eye Cream & Treatment (9)
Foundation with SPF (8)
Facial Cleanser (7)
Conditioner (6)
Moisturizer with SPF (4)
Mask (4)
Acne Creams and Gels (3)
Deodorants (General) (2)
Fabric Treatment (2)
Skin Toners (2)
After Shave (2)
Scar Treatment (2)
Hand Cream (2)
Laundry Detergent (2)
Depilatories (Women's) (2)
Sunscreen SPF 15 and Above (2)
Hair Perm (1)
Bar Soap (1)
Bath & Shower Cleaner (1)
Hand Dishwashing (1)
Foot Moisturizer (1)
Facial Wipes (1)
Lip Plumper (1)
Makeup (General) (1)
Air Fresheners (1)
Men's Grooming (General) (1)
After Sun Product (1)
Peels (1)
Facial Powder (1)
Shampoo (1)
Body Wash & Cleanser (1)
Concealer (1)
Styling Gel/Lotion (1)
Styling Mousse/Foam (1)
Acne Treatment Kits (1)
Lip Balm (1)



More information on Sodium Metabisulfite...

From Wikipedia


Sodium metabisulfite or sodium pyrosulfite (IUPAC spelling; Br. E. sodium metabisulphite or sodium pyrosulphite) is an inorganic compound of chemical formula Na2S2O5. The name is sometimes referred to as disodium (metabisulfite, etc). It is used as a disinfectant, antioxidant and preservative agent....

Read more at Wikipedia »


maybe this will help you out..so you can find something readily available to you that contains what you need at a cheap price...so it makes it affordable.

 

[qst42know]

leelandbullock

None of those products you listed have sodium metabisulfite in a useful quantity or purity. Granted as a preservative it has wide spread applications.

The problem wasn't finding SMB the original poster simply ran out.

 

[Geo]

when refining metals, the very act along with the term "refining" means to make the metal more pure. therefore, when you refine, you should use the purest forms of all the materials you will use. some things are vitally important for it to be of high purity while others can be less pure to achieve the desired effect. as a refiner, its up to you to learn what you can use and for what application. there are several ways to learn. the least productive is through trial and error. the most productive is through study of others who have already done the trial and error part.when you precipitate gold, whatever precipitant you use needs to be of the purest form you can get.

when you recommend using a chemical or compound, spelling correctly as well as listing the right ingredient is essential for safety reasons as well as the fact the person taking the advise could be working with their life savings or retirement fund.

all stump out is not the same. there are different formulas for chemical stump removers.you must check labels and never trust what you heard from someone else.make sure for your self. the correct chemical in stump out you are looking for is sodium sulfite,sodium bisulfite or sodium metabisulfite and even sodium pyrosulfite.

 

[leelandbullock]

leelandbullock

None of those products you listed have sodium metabisulfite in a useful quantity or purity. Granted as a preservative it has wide spread applications.

The problem wasn't finding SMB the original poster simply ran out.

they do contain it but in low ammounts, yes you are correct that the best should be used. but this has gone off topic now. but reguardless i got this off the internet directly but him being form ireland he dosent have hardware stores with this available.

also you can buy the best in the best form. but your also going to pay the prices. so sure you will get the most gold yeild but can you say you made a profit when your operation cost is outweight or matching your profit margin.

if with stump out i achive pure gold. then i am happy. because my operation cost is low while my profit margin is high. so for every 2000 i spend on chemicles, i yeild 15-20 thousand in gold and other metals thats a profit margin i can live with..

like if i am in a pince i go buy muractic acid at hardware store instead of waiting for hydrochloric acid to be shipped to me. same thing diffrent name. diffrent price.

but for the poster.

sorry its off topic this si the site i use to get most of my chemicls in bulk cheaper site than most i have found.

http://www.dudadiesel.com/contact.php this is the site i go to to get most of what i need to do what i need to do.. shipping rates for me are high but i am not sure what its going to be for you. if he can ship to you at all but its worth a try.

 

[jimdoc]

i also think comet, or ajax cleaner has what you are looking for the percipitate...i cant remember.

I don't think so.

Your link (http://www.livestrong.com/article/517642-what-products-contain-sodium-bisulfate/#ixzz29EzjmVEl) is for sodium bisulfate. We use sodium bisulfite or sodium metabisulfite.

Please spend some time studying before dispensing advice.

Jim

my bad and please be friendly, ive never had much patients for people who belittles others intelligents when they make mistakes. i was trying to help someone and i made a mistake in something i read up on the internet. its not grounds for you to demean me.

I was not demeaning you or belittling your intelligence, I was merely pointing out that your information is wrong. Here on the forum it is not like a casual conversation, where you say oops I made a mistake and it is forgotten. All the mistakes are saved in print, and it seems like those mistakes are what new members seem to find and believe. I understand that you are trying to be helpful, but truth is members should be using the search box, just about everything has been covered on this forum. When you study the forum some more, I am sure you will find some of the things you have learned elsewhere on the internet are simply wrong.

And around here you better have patience when someone gives you advice, because bad attitudes will get you the boot from the forum. If someone is belittled around here a moderator will take care of it, believe me.

Jim

 

[WillGreen]

Dear Butcher,

Thank you for your clarification.
Tomorrow, I will do as you told me, using copper to cement the gold.
After that, I will refine it again, this time using the right amount of nitric acid to make the aqua regia.
I am only curious. You say that using more SMB without removing excess nitric is a bad idea at this point. Could you please explain why this is so? I would like to understand this - this was exactly what I was going to do before I read your posts (and the handbook).

Thank you again and with best regards,


Will

 

[butcher]

Sodium metabisulfite can react with small amounts of nitric in solution, and overcome the nitric acid and precipitate the gold in solution.

I believe that adding more of a chemical that can already be in excess to a solution, is a bad idea in my view, if I added even more and then use a gold button to remove nitric or heat of evaporation, then I would have powders of excess chemicals and base metals salts mixed with the little bit of gold I recovered, it just makes more sense to me to rid nitric first (reacting with added gold and heating of solution) then see if I need any more SMB to finish the job, or if my gold would precipitate with what was in solution already.