Big mess with Aluminum reaction in my AR

[epx]

Hi Im a new rockie from South the border in Mexico City.

A friend of mine offered me 100 pounds of gold plated connectors at 80usd each. So I bought 2 pounds for testing.

I decided to go with the 2 step process of Nitric Acid and then Aqua Regia to speed up the process.

First step went smooth however as an amateur overload my AR with water ending up with 3 gallons of emerald liquid.

So I heated it to 120 f for 3 days to reduce water and at the same time I was adding urea. Please dont laugh but I spent 12 pounds of urea because the mix kept "fissing".

So decided it was time to cool down the mix in order to add SMB/water, I poured 12 oz of it and nothing happened.

To make the story short I put an aluminum rod and a heavy reaction took place heating the liquid to 130f. Copper I beieve was the first thing appearing as flakes going down the AL rod filling the bottom of the container, then a black powder appeared that I believe is the gold...

I was very very happy but then the liquid became red !!

Even though a careful inspection to the liquid has shown its green light color, but contains a very tinny red dust supended on it, it is so fine it will clog any filter. I would bet that could be the infamous Aluminum Compound I read about later on the forum.

I am a beginner I would appreciate any help. Should I heat to dry the liquid and start all over again?

Should I add HCL or H2SO4 to dilute the compound?. Thanks again for your help.

Just to update...

If I put HCL in a sample of this mix, there appears a "crystal like" solid at the bottom maybe the urea.

If I add Nitric acid at another sample the red material fades and appears a substance like white yogourt and the remaining liquid becomes green.

Regards Raul

 

[butcher]

If all else fails you can add zink precipitating all values as powder and start over. I would not use aluminum.

Do not use more nitric than nessasary.

Eleminate nitric to get a pricipitant (I boil to concentrate solution but not to a salt,just thick syrup, add Hcl to keep wet, doing this three times, and I may use a few prills of urea to test for nitric in solution).

it would of been much easiier if you hadn't added the aluminum, the aluminum probably has already dropped your gold and copper if enough has dissolve to replace them, this powder can be reprocessed, but dont use more acids than nessasary.
a few drops of dish soap will help drop the floating powder.
the white yogart sounds like silver.


nitric should have eliminated most all of copper or silver if there was any when you used it

 

[Harold_V]

A friend of mine offered me 100 pounds of gold plated connectors at 80usd each. So I bought 2 pounds for testing.

Your comment is not clear. How much did you pay for two pounds, and how much of the two pounds is actually gold plated?

I decided to go with the 2 step process of Nitric Acid and then Aqua Regia to speed up the process.

That makes no sense. In order for your comments to have much meaning, you must detail what you did, and when you did it. If you started out with nitric and shifted to AR mid-stream, everything you've done is wrong.

First step went smooth however as an amateur overload my AR with water ending up with 3 gallons of emerald liquid.

Describe what you did, and do NOT leave out details, no matter how insignificant you may think they are.

The balance of your comments may be meaningless. It's important for readers to understand what you actually did. I don't think you understand that you may not have put any gold in solution, in spite of having used AR. Describe exactly what you did with the first solution, and what you had after you had created the three gallons of diluted AR. It is important to note if there was anything left un-dissolved. At any point in time, have you removed any of the solution, so the dissolved base metal was not combined with the AR?

Do not discard anything. Not even solutions, until you can determine where your gold is, and in what form.

Do you have stannous chloride for testing?

Have you read Hoke's book?

Do you understand why AR is used, and why it should NOT be used on base metals, with rare exception?

Raul, answer the questions then I'll try to give you instructions to recover your gold, but, most importantly, to get you to use accepted practice instead of doing what you think you should do.

Harold

 

[epx]

Thanks all, specially today that is Thanks Giving.

Harold, I got 2 pounds of heavy gold plated connectors of all kinds, my friend does buy and sell electronic scrap he needs some money and offered me his best "gold savings".

I put them in 63% nitric acid to get rid of as much copper, and I thought I did completly. Got the gold flakes that looked at maybe few nice grams (over 4 grams) and put them in AR (800ml HCL)+(200ml Nitric Acid) .

The gold disolved completly and that was the last time I saw it..

So far everithing was ok, then I noticed that there were some more gold still in some undisloved parts at the nitric solution so I stupidly poured the left connectors (mostly gold plated on copper ones) into the AR solution

It disolved them and the substance became dark green, please don't ask me how I end up with 3 gallons of this solution but I did.

I wanted to get rid of a little bit of water so I heated the solution, I was so exited that I started to put urea and the solution eated it right away with fizzing, so the more I poured the solution keep fizzing..... 3 days and 12 pounds later I tought something was not right.

I stop heating the solution to pour the SMB, which I made with 1/2 gallon and aproximatly Metabisulfite 100 grams. I poured the whole thing and no precipitation. I tried another half gallon of SMB and nothing.

Unfortunatly I had some aluminum sticks on hand I because I read somwhere it would precipitate everything I tried.

So I put so many sticks until the thing practically stopped reacting.

The first hour looks like copper dropped.
Then a black sticky powder appeared ( I believe the gold)
Then the solution became very red and saturated however most of the 2 first precipitates went to the bottom althought some still keep floating.

I have removed the solids and I am decanting them since there most be some of the copper and a % of the gold. The rest of the liquid remains red...

regards Raul

 

[SapunovDmitry]

The first thing is that if you had 2 pounds (aprx. 900 gr.) of gold plated artilces (let's say 0,5% by mass) you would end with 4,5 gr. of gold.
You don't need to use 100 gr. of SMB to pour 4,5 gr. of gold.
The second is that you don't need to wait 3 days and make 12 pours of urea. When the first portion of urea (try to make them smaller) ends bubbling you cn drop another one until it doesn't bubble.
The whole operation can last about 6-10 hours min. if you just want some gold(in case you never did it before and you will just put the nugget on the shlelf above your bed and forget about it) and don't mind about losses.
The third thing is that heating during AR process is not necessary.It is optional. Try not to use more opertions than it is needed to get your gold.
If you got rid of the copper during nitric stage how can you get copper in your solution?
Can this be an iron? I once ruined my batch because of the iron.
Was the solution red or of a dirt color?
P.S. I wouldn't buy 1 pound of gold plated stuff for 80 bucks unless it is VERY heavy plated.

 

[epx]

Thanks Dmitry for your information and advice.

I agree I should be paying less money, around 1/2 of the gold value for all the effort it may require. I would not mind 1 or 2 thousand dollars extra per month so I will offer 50 to 60 us/ pound.


On the other hand It seems I got the beginners "adding much is better" syndrome.


To answer your question of why copper on the AR, I got rid of most the copper at the nitric stage, however when I noticed there were some unsolved connectors on the nitric acid hidden under plastic parts I added this unfinish connectors directly to de AR and thats how I got copper on it.


I hope with the help from friends in the forum I will try to save as much values from this bath and move on for the next connector purchases to sulfuric cell since it is all gold plated stuff.

Regards Raul

 

[Harold_V]

For starters, don't pay that much for gold that is still in connectors. Your "friend" isn't treating you very well. He's more like your enemy. You most likely are paying more for scrap than the gold is worth, so you'll lose money.

Here's what I'd recommend at this point. If you have any of the aluminum left, and it has a deposit on it that may contain values, place it in a container and add a little HCl and water. That should dissolve more of the aluminum, freeing any traces of values that may be present.

Combine any of the recovered solids from this operation with the recovered solids from the application of aluminum. If you have precipitated copper from your solution by adding aluminum, any gold that may have been in solution will have precipitated on not only the aluminum, but the copper. In the end, all of the copper you had in solution will now report in the solids, along with your values. Because you used aluminum, you will not be able to filter this mess-----so it's a good idea to get it all in a large container (plastic isn't the best choice because it will trap some of the values). Add a great deal of water, stir well, then allow to settle. Decant, and repeat. After you've done this a few times, you will have eliminated enough of the dissolved aluminum that prevents filtration, so you can get everything in a filter. Once it's dry, incinerate to remove unwanted substances, then go after the remaining solids with nitric once again. This time don't stop until you have nothing that remains as a solid except for fine black particles, or identifiable bits of gold plating. Aluminum will not dissolve, even if you boil. You will find black powder remains----that should be your gold. When there is no further action with nitric, add water, stir well, and allow the solids to settle before decanting. Do this no less than two times, to insure that your rinse water is virtually free of any color. Do not remove the solids from the container, which should be some kind of glassware that will withstand heating. I preferred beakers, but anything that can be heated and is not metallic will serve.

At this point you should be able to dissolve the solids with AR----but do not use any more than would be required to dissolve the entire mess. Several drops of nitric acid may prove to be enough, along with four times as much HCl. Allow the acid to work until is stops before you consider adding any more, and heat the solution to insure that it is working quickly. When action ceases, add a few drops of HCl alone. If you see no reaction, but you still have some solids, add a couple drops of nitric. Excess HCl does no harm, unlike excess nitric.

One word of caution. Because you have used aluminum, if any of it remained in the solid state, it will still be a solid after the nitric process. aluminum is not dissolved by nitric. Getting it in solution with AR is NOT a good idea. If you have any doubts about having removed all of the solid bits of aluminum, after you have processed the recovered solids with nitric, incinerate them again, then do a wash in dilute HCL, which will remove traces of aluminum and make filtration of the gold chloride possible.

Next time, avoid combining anything that is still a solid with a solution of gold chloride. When you introduce traces of solids to such a solution, if they are metal (in this case they were), they will precipitate the gold. Also, don't combine things like pieces of board with gold chloride solution. It complicates filtration and traps some of the values. Keep connector bodies out of the refining process as much as you can. Never use AR for recovering except in very unusual cases. It's always better to eliminate as much of the base metals as you can before dissolving the values.

Harold

 

[epx]

Thanks Harold, I owe you.
Two doubts before decanting as adviced.


By the way the red color of the solutution that I was mentioning before was from I believe the excess of urea, since a small layer of "urea like" crystals forms at the edge of the container when it dries. Once the Aluminum was added a reaction took place where the red color faded giving to a new brown murky colored solution that don't settle at the bottom.Only a black powder (gold) and a red mud (I think copper) settled.

Doubt 1
Second, this light brown mud that appeared right after the aluminum reaction started and grow in consistence and floating around, is this the AL chroride that I should get rid off?

if you think it is, I am planning watering the solution as adviced and get rid of this mud (I will save the mud+water for later Stanous Clhroride testing)

Doubt 2
Just to learn how AR behaves... on a theoretical AR solution contaning Paladimum,Platinum,Rodium,Tin, Copper and Gold if you use zinc to precipate what would be the order of the metals that will fall? Will the zinc react first with the unused HCL and once the acid wears will continue with the metals in an specific order?

regards
Raul

 

[Harold_V]

By the way the red color of the solutution that I was mentioning before was from I believe the excess of urea, since a small layer of "urea like" crystals forms at the edge of the container when it dries.

Where urea is concerned, I am no help. I never used it, always evaporated. I am not familiar in the least, so you may wish to hear from others that have that experience.

Once the Aluminum was added a reaction took place where the red color faded giving to a new brown murky colored solution that don't settle at the bottom.Only a black powder (gold) and a red mud (I think copper) settled.
Doubt 1
Second, this light brown mud that appeared right after the aluminum reaction started and grow in consistence and floating around, is this the AL chroride that I should get rid off?

Correct. However, in view of the unwanted precipitated metals, I think I'd be inclined to add some HCl and boil the material before adding more water. That would dissolve some of the unwanted substances and, hopefully, keep them in solution so they would be discarded with the solution that is decanted. As long as you test with stannous chloride, I can't see a way you can get in trouble by doing so. If, on the outside chance, there's still some free nitric present and any values were dissolved, you'd detect them with the stannous chloride.

if you think it is, I am planning watering the solution as adviced and get rid of this mud (I will save the mud+water for later Stanous Clhroride testing)

For clarity, anything that is not in solution should be re-processed after incineration. You may have some colloidal gold hitching a ride with other substances, so you'd lose it otherwise. Don't discard anything that is a solid, not at this point.

Doubt 2
Just to learn how AR behaves... on a theoretical AR solution contaning Paladimum,Platinum,Rodium,Tin, Copper and Gold if you use zinc to precipate what would be the order of the metals that will fall? Will the zinc react first with the unused HCL and once the acid wears will continue with the metals in an specific order?

Raul, I am one of the morons on this board. I do not have a chemical background, although I have years of refining behind me. I stuck with known procedures and am unable to make decisions based on chemistry. However, I think it's safe to say that if you consult the electromotive series chart, you'd find that all metals below a given base metal will be precipitated by that particular base metal. By selectively choosing the right one, you can cement only the values. Copper will do that, but I am not aware of another that will. Sorry, I am unable to answer your question. I simply don't know!
Rule of thumb with AR------use ONLY that which you need, no more. Heat your solutions so they work quickly----that way you know when the acid is exhausted. Working with cold AR, in my opinion, is not a good idea unless you are trying to selectively digest gold in the presence of platinum. YMMV!

Harold

 

[epx]

After 2 weeks of cleaning my mess and tons of decanting, filtering, and rinsing and then start all over again with Nitric and AR. I finally recover about 3 grams of values (out of probably 6 grams).

It has been a great experience, I have learned a lot about Acids, metals, reactions, Colors, Textures I have even made some stannous Choride that acually works.

Probably spent 30 hours on the weekends and 300usd in glassware, toarches, chemicals etc.

So I am happy I was able to make my first 3 dirty but good grams of gold, and it has been wothwhile to have made so many mistakes, I consider it as a membership ticket.

So I want to thanks every one specially to Harold for the support.

Now I will move on into learning Electrolitic Sulfuric Cell to deplate golden connectors and pins in volume, seems I can get few pounds every other week.

Thanks again !!

 

[Harold_V]

Very nice report!

Continued success, epx.

Harold

 

[dialortz]

I really appreciated this conversation guys. I feel like I learned a lot. Thanks to Harold, Dimitri and Raul.
You were an excellent example of how a forum like this should function.
HooRah!