Gold Recovery Help(Sodium Bisulphite not doing its thing)

[Innos]

Hello everyone,first post here,sorry its a cry for help...

As the title suggests,Ive added 25 grams of sodium bisulphite in aqua regia that consisted of 600 ml of water and 600 ml of hcl(33%) and about 20 ml of nitric acid.

This is my first attempt at a gold recovery process so the amounts and possibly method is off but you can never be sure when it comes to internet info so I sorta winged it.

I boiled it and it dissolved stuff pretty well,especially the gold.

I expect the yield to be between 5-15,but i added 25 grams to be on the safe side.

The "metal eating" process with copper 2 chloride was done pretty well in my very uninformed opinion so I don't think any left over metals are causing an issue,except maybe rhodium or platinum thats also in the solution.


The problem is,nothing is precipitating....please help.

"""But you must add your nitric to HCl in VERY TINY AMOUNTS with plenty of PATIENCE, or you will find it impossible to precipitate the gold out of an excessively-nitric solution.
""""
Is this my problem?its a quote from a forum member.

 

[everydayisalesson]

It very well could be your problem but you really didn't give that good of a description as to what you did to get here.
What was your starting material
Do you use heat to put your gold in solution
Did you test your solution with stannous chloride
After dissolving your material did you evaporate your solution
We need to know more about your situation before anyone can help you. Also, please use the search function for CM Hokes book as every answer you need is in there and can help you get started while your waiting for replies. Your gold is not going anywhere, just make sure it is in a safe location.

 

[kernels]

Nitric acid left in the solution is almost certainly your problem. You didn't specify how you denoxxed your solution, so I assume you didn't do anything to remove the excess nitric ?

I've tried every way under the sun and always return to evaporation to a syrupy consistency (as per Hoke), followed by HCl addition (x3)
I also like to add whatever gold buttons I have lying around into the evaporating mixture to consume the excess nitric (by putting more gold into solution). When you gain a bit of experience, you can basically cut the process down to a single evaporation with gold.

 

[jason_recliner]

Was that sodium bisulfite (NaHSO₃), or sodium metabisulfite (Na₂S₂O₅)?

Please would you confirm for us?

 

[Innos]

Wow,so many helpful replies in one day,truly an amazing community I must say!Props to you guys.

Anyway,I'll describe the whole process as concisely possible.

I tore apart 180 phones,of which 150 had gold plated keyboards,discarded the 30 with no gold,separated even the tiniest gold plated pins.Also I separated gold plated stuff from other electronic scrap,around 10 hard drives and 20 other computer components.
The reason I expect such a high yield is most of the phones were very old,even ancient,back then I assume gold plating techniques were not so advanced.
Also fyi I removed all the other components on the phones so I don't contaminate the process too much.I removed them by heating them up and scrapping off the components with the flat back of a butter knife(so I don't scrape off the gold)
Since I had a bunch of thick pins and whatnots I placed all the stuff in a bucket with copper chloride and hcl for 14 days with lots and lots of oxygen for the reaction.
I got all the gold filtered together with the debris and put it all in the aqua regia I described above.
P.S. i heated the aqua regia to boiling point and added lots of nitric because some of the plastic wasn't giving in.After it reached boiling I tapered it down just a little bit and kept it there.

The solution is currently stored in a garage,in a beaker with a watchglass over it.The garage is connected to my apartment so I vent it out everyday,just to be on the safe side.(The tempetures in the garage reach up to 30 C during the day,I hope thats not an issue)

Now the questions,No I didn't denoxx my solution...Considering my situation,what do you guys think the best denoxxing process?
I have some gold pieces I was going to sell or purify myself,theyre 14 carrat however.Would they do?
I could always remove the other metals with copper chloride afterwards.

I didnt test my solution with stannous chloride nor I have any....
I did not evaporate my soluton after dissolving it.

I used sodium metabisulfite (Na2S2O5) to precipitate,is that good,or a total fiasco?


Thanks again for all the help!

 

[everydayisalesson]

OK Innos, you have a mess. The first issue I see that you should try to figure out is your solution really needs to be outside. You could slowly be poisoning yourself and your family and probably damaging everything in your garage. I have only three years in this so I cannot really give you the advice you need except that you need to read Hokes book. Hopefully one of our guys will jump in and help.

Mike

 

[Topher_osAUrus]

You're using the right precipitant, unless its gone bad. My supplier told me, if it smells bad then its good, but if it starts to smell good it has gone bad.. Woft a small smell, dont just go straight to face with it.

You need to denox, it is a requirement.
Evaporate, or dissolve more gold, or use sulfamic acid. There are a great number of threads on each of those options.

 

[kernels]

Hi Innos, from above, it sounds like you had plastic parts in there and were trying to attack them with nitric acid ? Roughly how much nitric acid did you use all-up ? What does the solution look like now ? a Picture would be good for us.

 

[Innos]

As far as the slowly poisoning part,hopefully not,It is a huge garage and I left a hatch open a little bit.It is a risk,so I'd like to end this process as fast as possible.

The smell of metabisulphite is very strong but not bad in any way....Nostrils kinda burn when inhaled so I guess its still good?heh

""Hi Innos, from above, it sounds like you had plastic parts in there and were trying to attack them with nitric acid ""
Definitely,
I used about 20 mililiters of nitric acid,not more,on 1200 mls of water/hcl solution.

I will deliver a picture tomorrow.It is dark green.

I will dennox it then,however is my situation and procedure changed,since ive already added 25 grams of metabisulphite?

 

[kernels]

OK, so a few mistakes, but not the worst we've seen, you should still be able to recover some gold.

Firstly, everything you do from now on will create fumes, these fumes will corrode anything metal and can damage you health, if you can smell it when you walk into your workshop, you need better ventilation.

So, this is what I would do . . .

1. Filter the solution through at least 2 coffee filters to get rid of any debris, the SMB already used will not be a problem, but I have no idea what the results of dissolving plastic with nitric is, this may gunk up your filter and make filtering take a long time.

2. Get a large, wide-mouth evaporation dish and start evaporating off the solution. You want to keep the temperature around the 75-90 degree C range. Don't boil the solution. I use a hot-plate and 2000mL pyrex (kitchen) jug for this. Obviously, anything that touches the solution will never be used for kitchen duties again.

3. The evaporation will take a whole day, when the solution gets down to the bottom, there will be lots of crystals forming from your used SMB and whatever else might be in there. When it gets down to the bottom, keep swirling the solution every 2 minutes to prevent a hard crust from forming.

4. When the solution becomes viscous (gooey, syrupy), add a small amount of concentrated HCl and swirl it around, there should be some bubbles forming for a short time. Maybe around 50mL HCl

5. Repeat the evaporation and HCl addition at least 2 more times.

6. Now, you should have a solution with some gold in it that no longer has nitric in it. After the last evaporation, add about 100mL of HCl and about 10 ice cubes. Wait for the ice cubes to melt and start filtering the solution slowly through 3 coffee filters. Filter the solution back and forth between two beakers at least 3 times, this should remove most of the smaller particles.

7. Your solution should now be very clear, warm your solution to around 30 degree C

8. In a separate beaker, dissolve 10g of SMB in 100mL boiling water.

9. Stir your solution and add the SMB, within about 2 to 20 seconds, the solution should change color and then turn dark, this is the gold dropping out of solution.

Good luck!

 

[kernels]

And I would almost guarantee you won't get anywhere near 15g of gold, maybe 5g if you're lucky.

 

[goldsilverpro]

What type phones are you talking about? Crank? Dial? Push button? Cell? The term "antique" is a subjective one. I've been doing this since 1966 and, at that time, gold plating was about the same thickness as it is today. Like today, this mainly depends on whether or not it's a wear surface. Fingers and pins were plated with about 30 microinches of gold in 1966 and they are plated with 30 microinches of gold in 2016. Also, the chemistry of the gold plating solutions back then was, essentially, the same as it is today. And, as today, they didn't waste gold in 1966 - they knew how much they needed for a particular application and they didn't exceed that. A big difference today is that equipment has improved so that gold can be plated only where it is needed. For example, many pins are gold plated only on the contact point.

Get some tin solder or stannous chloride and make up a stannous chloride solution?

After AR was used, if there was ANY base metal remaining, there is always the possibility that the dissolved gold cemented onto the base metals and is still with the solids.

At one point, you said you only used 20ml of nitric in 1200ml of AR solution but, elsewhere, you said you used a lot of nitric. Which is right? I don't really consider 20ml a lot in 1200ml of solution. Assuming you've tested the solution and know that it contains gold, I would first try adding another 25g of SMB or, better still, measure out 1/10 of the solution and add 2.5g of SMB. If that drops the gold, add 22.5g of SMB to the remaining 9/10 of the solution.

 

[Innos]

I put 20 ml of nitric,I thought thats a lot since people are going crazy over the amounts of nitric but thats what I I calculated is the least amount for around 5-10 grams of gold and 1200 ml of aqua.

As far as the age of the phones,that is excellent information,that the layer is the same thickness back in 1966 as in 2016,but it is as you said,today very little gold is used because they use it exactly where they need it.

With older phones however,youve got gigantic keyboards plated very well with gold,also some other stuff,pins and such.Some older phones had this squareish pin that was very clearly plated with a lot more gold than other stuff,unfortunately I have no more of them,id post a picture otherwise.

One of the phones was a benefon with a gigantic battery,so it must have been pre 90s I guess,other phones were a bit "younger" thought,between this benefon and nokia 3310.

I did not test the AR solution for gold,but since i put in a lot gold stuff in it,and now its a clear liquid,id say testing is unneccesary.

Excellent idea goldsilverpro I will try that first,takes the least effort and second,if it doesnt work,I will try kernels recipe,sounds very well thought out(Already written it down in my chem book),thank you very much for the info,everyone.

I will keep you guys posted so that even if its all solved and good,someone else has the benefit of knowing how to fix this exact situation.Tomorrow youll get a picture

One question thought,what about denoxxing with sulfamic acid and 14carat gold,which I later purify with a treatment of copper chloride?

 

[Innos]

What type phones are you talking about? Crank? Dial? Push button? Cell? The term "antique" is a subjective one.

Mobile phones,like the one in your pocket ,just old,with lots of gold.

 

[Innos]

2. Get a large, wide-mouth evaporation dish and start evaporating off the solution. You want to keep the temperature around the 75-90 degree C range. Don't boil the solution. I use a hot-plate and 2000mL pyrex (kitchen) jug for this. Obviously, anything that touches the solution will never be used for kitchen duties again.

3. The evaporation will take a whole day, when the solution gets down to the bottom, there will be lots of crystals forming from your used SMB and whatever else might be in there. When it gets down to the bottom, keep swirling the solution every 2 minutes to prevent a hard crust from forming.

Honestly,I dont like the idea of evaporating a solution that has dissolved gold in it,it sounds like losses to me,and Im already pessimistic about the possible gold amount so I will do this as a last chance,however it does seem to me ill do it nevertheless,not many better options.

 

[UncleBenBen]

I did not test the AR solution for gold,but since i put in a lot gold stuff in it,and now its a clear liquid,id say testing is unneccesary

Testing your solutions is always necessary!

Example: I place an amount of gold plated boards in a vessel. I add HCl and heat. I then add nitric acid to create aqua regia. The solution is at a light boil as I watch the gold dissolve. Once the gold is gone I remove from heat and allow to cool. Once the boards are removed, I heat it back up and test with a pinch of sulfamic acid and get no reaction.

Since I saw the gold dissolve and know there is no free nitric I cool, filter and add SMB and nothing. Yet I saw the gold dissolve so I didn't test with stannous.

What happened? As the last of the nitric was used up the boiling solution loosened the layers of the boards exposing plenty enough copper to cement all the values inside the boards....

This may be what happened it may not be. My point is always test. Make it a habit. Make it standard procedure. But always test your solutions!

 

[kernels]

2. Get a large, wide-mouth evaporation dish and start evaporating off the solution. You want to keep the temperature around the 75-90 degree C range. Don't boil the solution. I use a hot-plate and 2000mL pyrex (kitchen) jug for this. Obviously, anything that touches the solution will never be used for kitchen duties again.

3. The evaporation will take a whole day, when the solution gets down to the bottom, there will be lots of crystals forming from your used SMB and whatever else might be in there. When it gets down to the bottom, keep swirling the solution every 2 minutes to prevent a hard crust from forming.

Honestly,I dont like the idea of evaporating a solution that has dissolved gold in it,it sounds like losses to me,and Im already pessimistic about the possible gold amount so I will do this as a last chance,however it does seem to me ill do it nevertheless,not many better options.

And this is why it's hard to get a nice detailed answer to a question on this forum. Someone with zero experience asks a question, you give them a detailed step-by-step answer, then they decide that they actually know better. :lol:

 

[Topher_osAUrus]

OP whay do you mean by use 14k then purify with copper chloride later?

How do you know there is even gold to prexipitate without a stannous test?
-you said your solution is green, that means heavy base metal contamination, which usually means the gold is trying to cement out while base metals go into solution.

And there is a good way besides evaporation.
-sulfamic acid. Its quick, cheap, and easy.

 

[jason_recliner]

Honestly,I dont like the idea of evaporating a solution that has dissolved gold in it,it sounds like losses to me,and Im already pessimistic about the possible gold amount so I will do this as a last chance,however it does seem to me ill do it nevertheless,not many better options.

And this is why it's hard to get a nice detailed answer to a question on this forum. Someone with zero experience asks a question, you give them a detailed step-by-step answer, then they decide that they actually know better. :lol:

I don't have a problem with questioning what he doesn't understand. I've certainly been there myself.

Innos,
Boiling the hell out of it will splatter it all over the place. But evaporating at a moderate temperature as directed will not lose your gold.
Gold does not vaporise at 90°C.

The intent is to gently evaporate, not boil, to concentrate the syrup to the point where fresh HCl will react with any existing nitric; this releases NOx as gasses.
Slow and steady wins this race.

 

[g_axelsson]

This thread made me feel ancient, I'm too is pre 90s. :lol:

I did not test the AR solution for gold,but since i put in a lot gold stuff in it,and now its a clear liquid,id say testing is unneccesary.

Testing is vital. I admit that I don't test regularly myself while refining, only when I suspect there might be gold in the wrong place. But on the other hand I don't have any problem with precipitating my gold either and anything with possible precious metals in solution goes to my stock pot. The two areas where I use testing the most is to check anything that I move to the waste stream and to test some incoming materials for precious metals.

Innos, if you have a problem you should test. Making stannous isn't hard and you have everything needed at home already. Even solder from electronic scrap can be used. I've done it.
If you are too lazy to make the effort to test your solution people might feel less motivated to help you, you have to put some effort into it yourself.

With nitric acid and some gold plated scrap it's just an hour to make some gold standard solution to test your stannous too.

Göran