Chemical HELPP Aqua regia turned dark muddy yellow

[COOKIENUGGET]

i need help.I put 68 cpu's into an Aqua Regia solution then it turned muddy green i put some urea after 2hours of waiting for the solution to settle of just aqua regia and the cpus.I added some water after filtering the solution,then some urea, but the solution didnt bubble up or sizzle like its supposed to so i added some sodium metabisulfite,and the aqua regia was still green and "foggy" after a while nothing happened so i added more sodium metabisulfite and then more then some more until it turned muddy yellow!!!!!Nothing is settling at the bottom only the sodium metabisulfite??????Can i still save the gold and how ??help please i added a lot of sodium metabisulfite and water help how do i get the gold HELPP

 

[Geo]

Did you test the solution with stannous chloride AFTER the dissolution and BEFORE trying to precipitate? If not, why not? Now you can go hunting for the lost gold. I could go on a huge round and round trying to explain. Take my word for it, the gold was not in the solution. The urea didn't fizz because the nitric acid/nitrate was depleted and the gold cemented back out of solution on the metal left on the CPU bodies. And dark powder or dark cloud when you decanted the solution from the bodies is part of your gold. Put all the solids back in the container (unless you threw it out) and complete the dissolution. Make or buy some stannous chloride and learn how to use it. If you had, you would know that your gold was still on the CPU bodies.
Good luck.

 

[anachronism]

Geo raises a great point that many many people miss. I certainly missed it in my early refining days too.

If you have any kind of dark cloudiness in your AR solution then your reaction is not complete. There are values floating around in it. For it to be complete the solution needs to be clear of particles in suspension. Yes it can appear dark, or brown or green instead of yellow- that's down to the contaminants in the base material but it needs to be a clear liquid.

Thanks Geo.

Jon

 

[jeneje]

Here is another example of why we invest in standardized solutions and Stannous Chloride. Use the standard to test your Stannous to make sure it is good, and use the Stannous to test your unknown solution. So many people think they can refine precious metals from the seat of their pants, so to speak. You have to test to see where your (Gold) is along the way. If you don't have the testing solutions, or you can not make them, buy them. It will make your life way easier, and you won't have to guess, where is my gold? You're know! :idea:

Ken

 

[aga]

There are 'values' floating around in it

Does 'values' just mean precious metal ions ?

 

[Geo]

There was no gold in the solution. I noticed that you left the large copper heat spreaders on the CPU's before starting. The gold cemented out of solution as fast as it dissolved. Remove the bases that still has the copper heat spreader. Rinse these in fresh HCl and set the wash aside. Rinse the base with clean water and remove the copper heat spreader. It's not hard as they are glued down. Use a blunted knife such a butter knife to pry them off. Put the copper in a container and save for cementing values. After all the heat spreaders are off, replace the material to the container that you were working with. Start the dissolution over using the HCl rinse from before. Add more fresh HCl if needed to cover the material about an inch over the top of the material. Start adding the nitric acid or nitrate as usual. Make sure all the metal is dissolved this time. ALL the metal has to dissolve before the gold will dissolve and stay in solution. When you do this, post back here for the next step.

 

[g_axelsson]

Geo is right, all that copper green on the CPU:s tells me that there are a lot of base metals left.

Aqua regia on fiber processors are nothing I would recommend, there are too much buried copper that the gold can cement back onto... been there, done that
http://goldrefiningforum.com/phpBB3/viewtopic.php?f=60&t=17697

Your gold is most probably with the solids.

Göran

 

[COOKIENUGGET]

Just to clarify.
Step 1:Wash the CPU's in Hydrochloric Acid
Step 2:Separate the CPU and copper heat spreaders
Step 3:Rinse the copper heat spreaders and the CPU bases in Hydrochloric Acid.
Step 4:Then put the Copper heat Spreaders and CPU's in a separate glass and add fresh Hydrochloric Acid and Wait till the Heat Spreaders dissolve and then add aqua regia.
Is that correct???

 

[Geo]

Once you rinse the copper heat spreaders, they will be clean and gold free. They are just scrap copper. The process for them is over. They can be rinsed and dried and kept to cement values from your stock pot or sold for scrap copper. Once this is completed, post what happened here.

 

[patnor1011]

You are looking at less than 1g of gold estimated yield from 68 of this kind of CPU. That gold is now spread all over every bit of undissolved metal in form of super fine black powder hardly visible in mix of other metal salts present.

 

[gentleman5926]

Did you not remove anything from the processors? Looks like MLCCs in there as well. I learned a lesson with mine today re: Copper I Chloride.... that whitish powder confused me at first, then after some reading fresh HCl solved the problem. It is definitely a learning process, but if you only ask questions instead of reading and practicing in small batches you lose many chances to figure out what works for you. Never jump in with large batches if you are new to it. On another note: NEVER throw anything away if you are unsure of it's lack of Precious Metals (PMs). For 5 months I have had what I thought to be 'lost' / ruined gold. It sat in the glass measuring cup in the shed because I had not gotten to throwing it away and felt there might be something I could do with it. I put water in it and that is where I got the white Copper I Chloride powder showing. I rinsed with water and filtered off the rinse water and Copper I Chloride. Then I added HCL through the filter and it dissolved the white powder immediately and cleared the solution showing floating gold flakes then. Re-Filtered it and folded up the filter into a jar with lid and have the watered down solution in a plastic coke bottle on the side. NEVER GIVE UP, just don't rush and do lots of reading! It does help. Good luck!

 

[FrugalRefiner]

Gentleman, welcome back to the forum. I do want to issue one caution:

Re-Filtered it and folded up the filter into a jar with lid and have the watered down solution in a plastic coke bottle on the side.

I wouldn't use a plastic coke bottle for two reasons. First, someone might mistake it for something to drink leading to a horrible accident. Second, the plastics used for those bottles may not hold up well to the solutions we use.

Dave

 

[upcyclist]

I wouldn't use a plastic coke bottle for two reasons. First, someone might mistake it for something to drink leading to a horrible accident. Second, the plastics used for those bottles may not hold up well to the solutions we use.

Indeed! I just finished up a bottle of white vinegar (descaling the coffee maker, well, the one I actually drink from) and noticed that even a weak acid like acetic/vinegar is sold in glass. And you can bet your butt I saved that bottle!

Mason jars are also good storage options, especially with the white plastic lids--the acid vapors will eat the metal lids*. But remember (or learn the hard way like many of us): canning jars and vinegar bottles are not reaction vessels. Even putting them on a hotplate will likely shatter them. Use pyrex/pyroceram/borosilicate glass for heating and reacting!

*and if you actually have old zinc lids, you can sell those to collectors for enough to keep yourself in plastic lids for a long time, haha.

 

[aga]

I wouldn't use a plastic coke bottle for two reasons.

A 3^rd reason is that some materials stick to some plastics very well, refusing to budge even with copious and repeated washings with hot/cold water or acid(s).

 

[gentleman5926]

All great ideas and input. Much appreciated. That being said, what of the Home Depot buckets? I know they are thicker, but will they hold up as 'stock pots'. I am getting ready to do my first dissolution of gold via the HCl/Chlorine method. Reading and learning. Glad to be back! RE: the pyro ware, I am looking around at the thrift shops, but money is too tight for even that purchase.

 

[nickvc]

You can use old Pyrex glassware but be careful not to put hot solutions into them or put hot dishes on cold surfaces.
Rigid plastic buckets are usually good for the stockpot but do not add active nitric to it, this should not be a problem if you denox your solutions .

 

[rickbb]

If you are going to buy buckets, get HDPE food grade. They are thicker and more resistant to chemicals.

 

[Geo]

A stock pot is for solutions that you have precipitated precious metals from. After precipitating the precious metals, you should evaporate the solution down to concentrate any trace PM's left in the solution. Stop short of crystals forming. If crystals do form, add enough water to dissolve them. If the solution gets cloudy, add a little HCl until it clears. This is what goes in the stock pot. If you need a five gallon bucket, you are either processing a lot of material or you are doing something wrong. Waste solutions such as old AP or washes and rinses, should be treated as waste and disposed of. There is no need to put this solution in your stock pot. Rinses and washes can be evaporated to the point of crystals forming. In other words, rinses and washes can be evaporated very nearly gone leaving very, very little behind. Old AP should have the copper cemented out of solution and then the solution should be evaporated to just before crystals begin to form and then neutralized. Decant the salty water and discard while the solids goes to the chemical dump. You cemented copper will hold any PM's, how ever unlikely there is that any PM's will be in it. A true to the word stock pot should only hold small to medium amounts of solution at a time. You keep solid copper in it all the time or add fine iron filings to remove any PM's at one go. Empty and process when it nears a certain point whether half full or three quarters full. Clean it up and start over. If you have room for buckets of solution to just hang out over extended periods of time, disregard everything I just typed.