Gold precipitate washing queiry

[Thomascorley]

Hi all,

I have recently purchased some ceramic CPU's. I tried to remove the pins with a blow torch but with no success. They very rapidly heat up like filaments from a light bulb and do not release from the ceramic body.

Having already done some research about processing them I have seen nearly all users dissolving them in AR. This seems a little daft because you are mixing base metals with the gold (in solution). I am already aware that precipitated gold can be washed in dilute Hydrochloric acid to remove base metals. How effective is this?

Reading through this forum I have noticed quite a few people struggling to get the gold to drop out of solution. Most likely because of nitric acid still being in solution. I am also wondering if it also because their are too many base metals present in the AR solution?? So will too many base metal prevent gold from precipitating?

Many thanks for reading.

 

[Bigwood247]

Hi all,

I have recently purchased some ceramic CPU's. I tried to remove the pins with a blow torch but with no success. They very rapidly heat up like filaments from a light bulb and do not release from the ceramic body.

Having already done some research about processing them I have seen nearly all users dissolving them in AR. This seems a little daft because you are mixing base metals with the gold (in solution). I am already aware that precipitated gold can be washed in dilute Hydrochloric acid to remove base metals. How effective is this?

Reading through this forum I have noticed quite a few people struggling to get the gold to drop out of solution. Most likely because of nitric acid still being in solution. I am also wondering if it also because their are too many base metals present in the AR solution?? So will too many base metal prevent gold from precipitating?

Many thanks for reading.

The best and only way to process ceramic cpus is breaking them in at least 5-10 small pices the directly dissolving them in aqua regia if done properly most of the base metals will stay in the solution and then remove excess nitric acid ither by boiling the gold soultion down to a syrup and adding fresh hcl and then boil it down at least two more times and that will get rid of excess nitric or u can buy sulfamic acid and dissolve sulfamic acid crystals in warm water and add to the nitric rich gold solution this will remove all the nitric bye proudcing Nitrus oxide aka laughing gas keep adding the sulfamic solution until it stops reciting then drop gold with smb u may want to refine the gold powder to get pure gold hope this helps Sean

 

[Bigwood247]

Hi all,

I have recently purchased some ceramic CPU's. I tried to remove the pins with a blow torch but with no success. They very rapidly heat up like filaments from a light bulb and do not release from the ceramic body.

Having already done some research about processing them I have seen nearly all users dissolving them in AR. This seems a little daft because you are mixing base metals with the gold (in solution). I am already aware that precipitated gold can be washed in dilute Hydrochloric acid to remove base metals. How effective is this?

Reading through this forum I have noticed quite a few people struggling to get the gold to drop out of solution. Most likely because of nitric acid still being in solution. I am also wondering if it also because their are too many base metals present in the AR solution?? So will too many base metal prevent gold from precipitating?

Many thanks for reading.

The best and only way to process ceramic cpus is breaking them in at least 5-10 small pices the directly dissolving them in aqua regia if done properly most of the base metals will stay in the solution and then remove excess nitric acid ither by boiling the gold soultion down to a syrup and adding fresh hcl and then boil it down at least two more times and that will get rid of excess nitric or u can buy sulfamic acid and dissolve sulfamic acid crystals in warm water and add to the nitric rich gold solution this will remove all the nitric bye proudcing Nitrus oxide aka laughing gas keep adding the sulfamic solution until it stops reciting then drop gold with smb u may want to refine the gold powder to get pure gold hope this helps Sean

Ohh and don't use urea to nuturalize nitric acid no matter what anyone says use sulfamic or the boil down method
Urea is best kept for use on your lawn as a fertlizer lol

 

[jeneje]

Do Not Boil your solution, boiling your solution will cause loss of values. Instead evaporate the filtered solution to a syrup add HCL brown fumes will come off, depending on how much HNO3 you used you will have to do this process several times until there is no more brown fumes coming off. If you have a PH tester test the PH it should be between 1 and 2 no higher. Add SMB and your gold will drop.

Ken

 

[Bigwood247]

Do Not Boil your solution, boiling your solution will cause loss of values. Instead evaporate the filtered solution to a syrup add HCL brown fumes will come off, depending on how much HNO3 you used you will have to do this process several times until there is no more brown fumes coming off. If you have a PH tester test the PH it should be between 1 and 2 no higher. Add SMB and your gold will drop.

Ken

Sorry didnt mean boil I meant evaporate thank for that !

 

[Bigwood247]

And I was told when I first started if u have to nuturalize large quantities of nitric to use sulfamic acid instead of urea that's y I added that

 

[butcher]

Bigwood247,
How about writing out the words and dropping the text language, it will make what you say easier for us to understand, using texting shortcuts on the forum is frowned upon.

When working with electronic scrap the use of sulfamic acid has an added benefit, the side reaction from using it to remove the free nitric acid from solution, the sulfamic acid in solution forms some sulfuric acid, this will help to precipitate the lead from your solution, as an insoluble lead chloride.

 

[Bigwood247]

I'm just so use to using my texting lingo sorry this was my first time trying to help someone on this fo and besides a couple of mistakes I think I did a good job explaining the process thanks for your input and ill correct the stuff that u have said thanks alot Sean wood

 

[Thomascorley]

Some nice little nuggets of information.....

Ironic how being a "wanna-be prospector" trying to scavenge some gold, I am finding lots of gold in the form of information on this site.

''When working with electronic scrap the use of sulfamic acid has an added benefit, the side reaction from using it to remove the free nitric acid from solution, the sulfamic acid in solution forms some sulfuric acid, this will help to precipitate the lead from your solution, as an insoluble lead chloride.''

Very interesting.... So after introducing the sulfamic acid to the AR, Lead is dropped..... Sounds like a nice time to give the AR a good filtering.

I have to admit I got suckered into buying some Urea...... I'm sure I read some where that Urea was effective at neutralising the Nitric acid. So will have to go shopping for some sulfamic acid.


Just found it! The following passage is from the Gold refining hand book Volume 1 (found at this website recommend by another user)
I have tried using urea, It didn't work. So really glad I have stumbled upon that little nugget.


AR Recipie 2= Poor Man’s AR = 8 oz Sodium Nitrate, 480 ml water, 960 ml Muriatic Acid plus heat. Used to dissolve high karat gold, gold powder, gold foils, dissolves Platinum when hot. Excess nitric must be neutralized with Urea to pH 1 +/- 0.4, then drop gold with SMB.

 

[butcher]

Urea will destroy the NO2 gas in solution, but does not really destroy the HNO3, or nitrates in solution, yes the HNO3 decomposes to NO2 and other NOx gas, so if enough urea is added, and there is not too much excess of nitrates or nitric acid the urea will remove the NO2 as the HNO3 decomposes, so it can work(somewhat), in fact when they make very strong nitric acid and want it pure and clear they will add urea to the pure nitric acid to destroy the NO2 in the strong acid that colors the solution yellow, the added urea does not decompose the pure nitric acid it just removes the decomposed gas in the pure nitric acid.

The problem is with urea you can form dangerous ammonium nitrates and other amine compounds, these can impose dangers during the processes or even in your waste treatment, including risks of explosive mixes being formed, urea or any ammonia or ammonium compound can also complicate the recovery of metals in the platinum group, even if these compounds are added to your stock pots, urea is just another contaminate if added to your solution in my opinion, of course people have differing opinions, and when urea has been promoted for such a long time, people or the intranet keep recommending it, and repeating so often what they read, most people do not know any other way to deal with nitric acid and believe that urea is somehow the magic answer to the problem, when I believe it just creates its own set of problems.

 

[Thomascorley]

Thanks Butcher,

is their any truth in the "Ph level 1" being a clear indicator that all the nitric acid has been removed ? From what I have seen removal of the nitric is essential.

 

[jeneje]

Thanks Butcher,

is their any truth in the "Ph level 1" being a clear indicator that all the nitric acid has been removed ? From what I have seen removal of the nitric is essential.

I am going to try to answer this in a simple way for you. Removing HNO3 from your solution by denoxing, (evaporation method) adding HCL back into the solution does two things. One it helps expel the excess HNO3 in the form of brown fumes. Two it is raising the concentration of the HCL back to 30%, At 30% HCL has a PH of 1.0 at this point the gold can be released out of the solution and free to drop with ferrous sulfate or SMB. Is all the nitric out I don't know but I do know if the solution is at 1.0 ph your gold will fall.

This is my understanding and it should not be considered to be fact, but it does work.

Ken

 

[jeneje]

This will help, I hope some of the new members, through the day I will show and post pics of the denoxing raising the PH to 1.0 before adding my ferrous sulfate to drop the gold. This solution came from my gold cell, it was washed five times in DH20 and then dissolved in AR, I left the excess HNO3 to show how important denoxing and raising the PH is.

This pic is where it Started this morning, note the PH 0.1

Ken
edited, for spelling

 

[goldsilverpro]

The accuracy from a pH meter is best when the pH you're testing is between the calibration standards. You are probably using 4, 7, and 10 standards and using these 3 would make it most accurate between 4 and 10. Outside these limits, you start introducing error and the closer you get to 0 or 14, the greater the error. You can buy or make lower or higher standards. A 1.0 standard can be made with 25ml of 0.2M KCl + 67ml of 0.2M HCl. That would provide more accuracy when trying to measure 0.1 but there would still be error.

For low range pH measurement, I prefer short range pH papers. pHydrion comes in a 0.0-1.5 range paper

 

[jeneje]

Update, it has been two hours, with hot plate on high, the evaporation is coming along great, Note the paper tab, that is where the solution level was and now it is coming down. As the level comes down I will adjust the heat to keep it from boiling. DO NOT BOIL your solution.

GSP, you are correct I am using 7 to calibrate the meter. I too use the PH paper. For this thread I wanted to show the numbers instead of color. Thank you for giving me the information on making a lower standard solution to calibrate the meter I will try that on my next process. I use the meter mainly when I am neutralizing my wastes to check the PH.

Ken

 

[jeneje]

Update, It has been almost three hours since I started, the solution has thickened up to a syrup, (see pic), I added 50ml of 32% HCL and got a tiny puff of brown fumes, indicating HNO3, after the addition of my HCL to the solution it wanted to boil, I turned the hot plate completely off and covered the dish with a watch glass so not to lose any gold. After cooling I tested the PH (see pic) Now showing 1.0, I tested the solution with stannous chloride (see pic) and got a deep dark purple almost black positive test (see pic).

Once completely cool I will filter the solution and test PH again, then double the volume with H2O and drop with ferrous sulfate.

Ken

edited for spelling

 

[jeneje]

I have filtered the gold solution and added the ferrous sulfate here is the result, the first pic shows the filtering and the second the gold.
Hope this is some help to all, to the question "are there any truth to the PH being 1" well...I will you the reader decide.

Ken

 

[g_axelsson]

Great post Ken!

Nice to see the evaporation process in pictures, the wide and low vessel makes it a lot faster than a narrow high vessel would make.

I guess that the yellowish green colour comes from the ferrous sulphate?

I have only used SMB to drop gold and when there are no PGM:s in the solution I usually get a pale blue solution left after the gold have dropped (blue from copper traces).

Göran

 

[jeneje]

Great post Ken!

Nice to see the evaporation process in pictures, the wide and low vessel makes it a lot faster than a narrow high vessel would make.

I guess that the yellowish green colour comes from the ferrous sulphate?

I have only used SMB to drop gold and when there are no PGM:s in the solution I usually get a pale blue solution left after the gold have dropped (blue from copper traces).

Göran

Thanks Goran,
I just hope it helps out somebody. The yellowish/green is from the ferrous sulfate, I have always got that color when using it. As you know hokes recommends it for gold only and it does do a great job, but...here on the forum they recommend SMB and in my way of thinking each does a great job. So it is up to the person, which they choose.

The point here was to try and explain the value of having the HNO3 out of the AU/CL, Buy checking the PH as you begin the denoxing, then you can see where you are at and where you have come from.

There are other way to remove the excess HNO3, Harold suggest using a gold button and for one I have done that and it works great. I have seen posts where members can't get there gold to drop and the main reason is the PH is to low or they had none to start with.

Anyways, remember ph of 1.0 will free up the gold and it should drop without any problems.

Ken

 

[Thomascorley]

Ken,

Thanks for the epic reply! I did wounder about getting an electric Ph testing kit. They are pretty cheap to get a hold of, not really being an expert on chemistry equipment, I bought litmus paper. Surley can't go wrong?

Many thanks again