# Aqua Regia Method- Supervision Needed



## etam (Nov 29, 2010)

Dear forum members!

I'm Matthew from Hungary an original rookie in refining altough I'm intrested in gold panning since years. Yes, I konw
that panning doesn't equal refining but this forum and all the pictures and tutorials here made a great imperssion on me!
The basic situation is that I really love that yellow-brownish shiny metal and the way how I recover it! Unfortunatley the
mother nature isn't kind in wintertime here in Eastern- Europe so I can't get my "daily dose of gold" on its usual way. 
Thatswhy I turned to the sience of recovering and refining precoius metals from e-scrap! It's so wonderful!!!
I read Hoke's book and I searched a lot in this forum and tried to pick up the most importatnt informations and directions.
All of these were very useful for me and now I think so I'm relatively close to the realization, but in some steps I need
your guidance and advices. And of course, I got a lot of stupid questions! (please excuse me)
So, here I come; (I prefer the AR method, but I'm intrested in othe methods like AP or HCL-CL or Poor Man's AR)

Please supervise all my steps

- I got about 50 pcs. Intel Celeron 466 CPUs, nitric acid, hydrocloric acid, SMB, Urea 
-I crush the CPUs 
-I dissolve the base metals with nitric acid, and when the reaction is over I pour it to an other container (no more fumes=no more base metals)
-I rinse the CPUs with tap water
-I add first HCL and than HNO3 in small doses nad let the acid to work
- After every gold is dissolved and the reaction ended I can: (I know that at this point I can add H2SO4 to get rid of lead)
- evaporate the nitric acid with heating but not boiling to a syrupy condition, add HCl and evaporat again 2x
(if necessary 'cause I read when I use just enough (adding small amounts) from the HNO3 there won't be any excess)
OR
- knock out the nitric with Urea

-Filtration
- If I choosed the evaporation method: dillute the "syrup" with hot water and after that I add SMB to precipitate gold
-With Urea: I simply add SMB

-I let the brownish powder to settle down and pour the the unwanted fluid
-Rinse the powder 2 times with tap water than dry it and melt

OK! I think I'm ready, but I know I did a lot of mistakes! Please help me and correct my steps!

And now the numbers: (The following calculation is just theoretical, the prices are real, but I know that I never can get $1367/oz)
1 liter of 65 m/m% HNO3 costs: $28 $0.028/ml
1 liter of 37 m/m% HCl costs: $18 $0.018/ml
1 kg SMB and 1 kg Urea cost: $5
1 pc. of Intel Celeron 466 costs: $1 (50x1= $50)
--------------------------------------------------------------
Total: $101
1 oz of fine gold: $1367
1367/31= $44,1/g ---> 101/44,1=2.29g ----> 2.29/50= 0.046g/CPU

Under these circumstances; (I used all of my chemicals[I know that this amount of stuff enough for much more CPUs] and I can sell my gold for $1367/oz)
I have to extract 0.046g/CPU to cover all my expenses! Nice but not true! But possible?

So, I used the search button a lot on the forum when I was looking after the description of the AP method and the HCl-Cl method, but I didn't find them! 
I would highly appreciate if somebody show me where can I find any further infos about them! And of course, the most important, please commnet my post,
and help me to be better in refining! I'm very curious about your opinions!
Many thanks...

Matt

P.S.: Sorry for my Eastern-European english


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## aflacglobal (Nov 29, 2010)

Try looking thru the forum book. It has links to most everything your asking.
http://goldrefiningforum.com/phpBB3/download/file.php?id=3815


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## aflacglobal (Nov 29, 2010)

http://goldrefiningforum.com/phpBB3/viewtopic.php?t=1445&start=0&postdays=0&postorder=asc&highlight=

http://goldrefiningforum.com/phpBB3/viewtopic.php?t=328&start=0&postdays=0&postorder=asc&highlight=

http://goldrefiningforum.com/phpBB3/viewtopic.php?t=4249&start=0&postdays=0&postorder=asc&highlight=

http://goldrefiningforum.com/phpBB3/viewtopic.php?t=4392&start=0&postdays=0&postorder=asc&highlight=

http://goldrefiningforum.com/phpBB3/viewtopic.php?t=1645&start=0&postdays=0&postorder=asc&highlight=


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## etam (Nov 29, 2010)

Thank You aflacglobal! It's very useful! I don't know how the forum book escaped my attention??? :|


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## lazersteve (Nov 30, 2010)

The forum book is a compilation of many posts you can find here. Some of those posts are updated peridoically (like the General reaction list and Rough Draft Guide to the Forum). You should also take the Guided Tour Link to see the most up to date versions of these threads.

Steve


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## etam (Nov 30, 2010)

Thank You lazersteve! I'll check that topics and try to get the informations!


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## martyn111 (Nov 30, 2010)

Just a small comment on your washing proceedure, you state that you wash twice with water then dry and melt. Have a search for Harold-v's washing proceedure, Boil with water, this will remove any lead sulphide remaining in your powder, Boil with hcl, this will remove any base metals remaining in your powder, and boil with ammonia (not exactly sure why, but if harold says it then there is a reason for it). Then re dissolve your remaining powder and re precipitate it and go through the wash proceedure again. It may seem a lot of washing but your end product will be of a much purer quality as a result. Then you can dry and melt your gold.
Keep up the good work and reading, you will not be given any bad advice here.


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## aflacglobal (Nov 30, 2010)

Harold's washing procedure :arrow: 
http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?t=325&start=0&postdays=0&postorder=asc&highlight=

It has everything to do with how you're refining. 

There are NO shortcuts. If you want pure gold, you MUST follow accepted practice. Remember, those that went before us have gone through this time and again----and have perfected a process that will yield good quality------so if you're interested in achieving that level, follow instructions that are at your disposal. Don't experiment-----leave that for others with time on their hands that are content to re-invent the wheel. This is particularly important for you, considering you're trying to establish a refining service. 

Depending on what you're starting with, you may have a hard time achieving a good level of purity the first time through. That's to be expected. Part of the problem is mechanical drag-down, where you're working with very heavily contaminated solutions, part of which follow the gold. They're not always easy to wash out, even when boiling with HCL. 

My advice to you is this: 

Process your gold the first time, using conventional means. Allow as little in the way of contaminations (metals) as is humanely possible, to be included with the gold. Use only clean vessels. Wash them well between operations-----and use BonAmi cleanser if necessary to remove stubborn stains. Do not use other cleansers, for they scratch the glass. Filter before precipitating, and insure that the filter does not allow particulate matter to pass. If it does, re-filter, or go to a better filter grade. A Whatman #2 does an outstanding job for first refined metals, although they are not cheap. I used them exclusively for filtering first run gold chloride. I felt they were worth the extra money. At all times, keep your beaker covered with a watch glass of appropriate size, to prevent contamination from other sources. 

Precipitate your gold using conventional methods, collect it and wash it well. It's best to use a precipitant that does not add contamination. I preferred SO2, but there are others that work equally as well, I'm sure. 

First wash should be in boiling HCL and tap water. Boil for a prolonged period of time. Take up the solution with tap water, decant after the gold has settled, then rinse with tap water, which should again be brought to a boil. After it has boiled for a period of time, add more tap water to cool the lot, then decant as before. Rinse again, and do it until the wash water comes off clear. Next, wash the gold with ammonium hydroxide and tap water. Heat it until it boils. You'll notice that the solution gets discolored. How much is determined by how dirty your gold was when you started. The ammonia evaporates fairly quickly, so you can't boil very long. Add tap water to cool, decant, and follow up with a tap water rinse, again, boiling the water. Add tap water to cool, then decant. You now repeat the HCL and tap water wash. You'll be amazed that suddenly more contaminants will come off. Boil well, add water to cool, decant, repeat the water rinse, decant, then, and this is important-------start the refining process all over again by dissolving the well washed gold powder in aqua regia. I'll talk about that in a minute, but these are indicators you should have observed along the way, aside from the fact that you could see contaminants being washed from your gold powder. 

The gold powder, which started out quite dark, is now much lighter in color. 

It may have been rather loose and flocculent, but now is eager to agglomerate, so it forms lumps and settles quickly. 

While these instructions sound like a lot of wasted time, when you process what you think is pure gold, you'll see evidence in the remaining solutions that it was not. The evidence of which I speak will be in your solution when you've extracted the gold for a second time. It's a lot of work which is why I re-refined my gold in large lots, often as much as 200 ounces at each refining, so the time spent yielded a large return. 

When you precipitate for a second time, one of the things that you can do to help eliminate unwanted elements is to use a different precipitant than the first time. I never bothered with that, but it's good advice if you're fighting with a given contaminant and can't get rid of it by other means. That was never a problem for me. 

Wash the gold powder the second refining by the same methods and sequences as the first refining. Make sure all your equipment is scrupulously clean. Force dry the gold when it's washed by heating the beaker at a very low heat for a long period of time. Avoid allowing the beaker to achieve boiling temperature---you get minor steam explosions that blow gold out of the container. As the gold dries, it's a good idea to swish it around the beaker occasionally, which prevents the gold from bonding to the beaker. The residual matter in water tends to form around the gold and bond it to the beaker. While it's a contaminant of sorts, it does NOT alloy with your gold, so it is not a source of lowering the fineness unless you have strange elements in your water. For me, it was not a problem. 

Once dry, you can then melt your gold. A clean, never used for anything but pure gold, dish can be used. It should be covered with a coating of borax, but nothing else. DO NOT USE ANY SODA ASH. If there are any oxides present, they'll be reduced and absorbed by the molten gold instead of locked in the flux. 

Your torch should be cleaned of loose crud before melting your gold. Run fine abrasive cloth over it until it's very clean, then wipe it down with a damp cloth to remove any traces of dust. Think clean every inch of the operation-----otherwise you undo all the hard work you've done getting your gold pure. 

Your other option is to operate a small gold cell, but you must have several ounces of pure gold for the electrolyte.. That is likely not a viable choice for you at this point in time. 

Harold


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## etam (Nov 30, 2010)

Thank You martyn111 and aflacglobal again! Awesome posts, and the rule is just the same; learn and think before you act! I think all of these responses saved a ot of time and of course money for me!


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## etam (Dec 8, 2010)

...I made my first experiment today and I result was very surprising for me. Today I just wanted to dissolve base metals so I used a tiny amount of 65% nitric acid and three different "yellow colored" pins. Two of these are from a PC and the other one is from other source. First I put the pin from the PC into the nitric acid and the reaction went fine-> hevay fizzing, brown fumes, the acid's color turned green, gold flakes (I think they are) appeared and then the reaction was over. The next thing I put in it was the pin from the different source-> NOTHING at all!!! I heated the pot but it happend nothing as well. The last pin i processed was a "leg" of a CPU Intel Celeron 366 I pulled out with a pliers. I threw the leg in and it happend nothing again! Now I"m very- very disappointed. I got a lot of different types of CPUs and after this experiment I think I can't process them!  What kind of material are this undissolvable pins made of? Are they some kind of alloys or what else? As I know the nitric acid have to dissolve all kind of metals expect gold and platinum group metals. 
What do you think abou that? What's the problem? Don't hesitate if You have a good advice fro me!!! Thanks...
(it was just an experiment with nitric acid in the future I'd like to use the AP method)


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## goldsilverpro (Dec 8, 2010)

Try diluting the 65% nitric with an equal amount of water and then heat it. On most metals, the nitric works much better when diluted.

If this doesn't work, it is possible that the gold is too thick to allow penetration of the acid. Thinner gold is more porous and will allow penetration.


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## Barren Realms 007 (Dec 8, 2010)

If you have a couple of the pins that you have not put in nitric, put a couple in HCL and put some heat on it.


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## etam (Dec 9, 2010)

Thank You for your help and advices I'll make a try soon. Maybe the main problem was the temperature, because I made this outdoors and it was only 9°C! 
As I know it's not too optimal for the nitric acid to work! Anyway I left the pins and the CPU leg in the acid and in the morning I realised that the pins undissolvable pins are dissolved and a lot of foils floating all over the pot. Wow! BUT, the only leg from the CPU is totally intact!(I really have to heat it)
The color of the solution turned blue and white and blue salts???? appeared and the most of the foils settled down.(or something) I hope if I heat and dillute the problem with the CPU leg will be solved
Thanks...

Click for original size


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## Goldfinger4 (Jan 12, 2011)

Heating will accelerate the reaction but also waste HNO3 (it will decompose faster to NO2). Waiting several days will bring the same results and save HNO3.

When I'm experimenting I'm mostly impatient and heat


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## etam (Mar 6, 2011)

Hello again!

My next experience was a Nitric acid bath for an Intel Pentium I CPU. The steps I made were very simple, I poured off 50 ml of 65% nitric acid in a measuring-glass than added 25 ml of distilled water and put the CPU in it after the lower lid was removed. I made it outdoors and the temperature was very low max. 8°C by daylight (but not every day) and -1°C at night so it took a lot of time (1 week) until all legs falled down. And now I feel like I got lodged in the process because just a few legs stripped off the "golden dress" but the majority still got it on and it happens nothing at all. At this point I really don't know what I should have to do! Should I put some heat on, or just wait for warmer days or... is the base of those pins dissolvabe ???
Thanks in advance,
Matt


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## etam (Mar 6, 2011)

... sorry, I meant----> *undissolvable?*


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## patnor1011 (Mar 6, 2011)

Mate, did you try to swirl solution around in beaker? Your pins maybe already done and base metals dissolved they may be just hollow gold foils - like pipe.


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## etam (Mar 7, 2011)

Hi patnor1011!
Yes, I made the swirl many times, and the only result was; the lighter foils without their base, so the hollow pipes, accumulated in the very middle of the whirl and they were floating, and the heavier ones just settled down and they showed no sign of any change. It seems just like some of the base pins don't want to let off the golden cover... :shock: And one more intresting thing, yesterday when I heated the solution, that pins wich have the gold cover still on turned black but after a several seconds they turned gold coloured again, I got frightend a bit... :| and yeah, it's 6 AM (CET) and -5°C so I don't think so that any change occured durin the night!
Thank you patnor for your advice!
Matt


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## patnor1011 (Mar 7, 2011)

I am using AP on processors which do not have goldplated heat spreaders and gold alloy braze. They usually need 10-20 days to dissolve. I agitate solution every day.


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## qst42know (Mar 7, 2011)

I remember a post a long while back along the same line. Some indigestible washers or rings remaining after the pins were digested. It was part of the conductive ceramic and remained even when the gold was dissolved.

From your photo I think your pins look good to go.


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## etam (Mar 7, 2011)

Thank You qst42know!
I think you're right, because I heated the nitric 1 hour long, and it happend nothing expect the dissolution of the pins wich haven't got gold cover. The other pins look like they would have a plug on their end wich doesn't allow the acid to penetrate under the gold shield, or I really don't know.... Anyway, I'm waiting now for the replies from colleauges who have some experience with the interaction between nitric acid and a PI CPU! Oh, and dear patnor! I'm very curious to know your AP process for a CPU! Are there any significant differences between your and Lazersteve's AP method?
Thanks,
Matt


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## qst42know (Mar 7, 2011)

Hi Matt.

Found the old thread.

http://www.goldrefiningforum.com/phpBB3/viewtopic.php?f=37&t=5007&p=42973#p42973


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## patnor1011 (Mar 8, 2011)

No, I learnt everything from him. I have a lot of time so I dont use any ratio like. I just use enough of HCl to cover material and I add H2O2 in small doses, feww ml at a time. Nowhere near 4:1,it is rather 10-20:1. It depend what H2O2 I use. Sometimes it is 3% (20:1) sometimes 6% (10:1)


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## etam (Mar 8, 2011)

Thank you guys again for your helpfulness! 
And finally my problem with the legs was solved! It was not as hard as it looked at the first sight. There were no undissolvable plugs or parts from the ceramic body to block the nitric. I put that nasty HNO3 resistant legs into a 30% HCL bath put some heat on and they started to fizz, the colour of the solution turned yellow, and hollow pipes were floating around! The light grayish legs turned black and even thinner and thinner until they disappeared! Sweet VCITORY! (It took more than 3 hours at near to 90°C! :shock: )


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## qst42know (Mar 8, 2011)

Some of your gold will be in that solution if you didn't incinerate the nitric away. Test with stannous.

Ar will tolerate some small amounts of base metal contamination without complicating your recovery.


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## Harold_V (Mar 9, 2011)

qst42know said:


> Some of your gold will be in that solution if you didn't incinerate the nitric away. Test with stannous.


Yep! I agree, but if there was a sufficient amount of base metal present, even without incineration, what little gold that may have been dissolved was likely cemented on the base metal, so the gold will be in the solids, although it may not look like gold. Testing is always a good idea, even when you're *sure* there's nothing of value in a solution. 

Harold


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## etam (Mar 10, 2011)

Well, my experiment with the Pentium 1 CPU came to an end. The hot mutriatic acid did its job and dissolved the base of the pins. All I got know are just hollow pipes like trumpets and a greenish-yellow coloured solution. According to your advices I tested it with stannous chloride, but as I put a drop stannous on the yellow cotton-wool head after I dipped that into the solution, it lost its yellow colour and happend nothing else. 

Anyway, the result is here in pictures!
Take a look and comment please!


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## Harold_V (Mar 11, 2011)

etam said:


> Take a look and comment please!


Well done!

Harold


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## etam (Mar 11, 2011)

Thank You Harold!


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## etam (Mar 11, 2011)

My very next experience is going to be a P1 CPU in poor man's aqua regia, because the 65% Nitric acid in Hungary is an expensive "plaything" (1000ml cca.$28) while 1000g of NaNO3 is just $5. I made a survey among the posts of lazersteve,GSP, Harold and many others wich relate to this topic. I learnt a lot, but I still have some questions and now I try to explain these :roll: 
As I learnt in this process is very importatnt the dosage of nitric and HCl, it should happen in very small increments to avoid the the excess nitric wich blocks the precipitation. I red the post of GSP who says, this is a kind of art to reach the right ballance beetween nitric and HCl.., and you need to estimate the amount of nitric you will use during the refining process...

I'll deduce this example with the data come from my first experience,

Gross weight of P1 CPU: 29.12g
Net. weight of P1 CPU: 27.5g (without the legs and solder and with the lower lid)
(Net. weigt of the gold outcome: 0.04 g)

All dissolved material: 29.12-27.54= 1.58 g
In poor man'a AR I'll dissolve the gold too so the total weight of material is 1.62g. According to lazersteve's calculations 3,2 ml of HNO3 70% dissolve 1g of copper. And 1,34g NaNO3 = 1ml HNO3 70%. Here I have 1.62g of metal so could my calculation right if I say that I need 7.01g of NaNO3 to dissolve all the metals of the CPU and end the process with the most smallest amount of excess nitric?...and... can I estimate How much HCl I need to this amount of NaNO3?
Thank You!

Matt


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## qst42know (Mar 11, 2011)

I think most recommend 4 times the nitric as the right ratio. But a modest surplus of HCL does not interfere with the precipitation of your gold.


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## nickvc (Mar 12, 2011)

If nitric is so expensive why not use the chlorox method to dissolve your foils? The added advantage is that bleach is cheap and easily available and works well on powders and foils.


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## etam (Mar 12, 2011)

nickvc said:


> If nitric is so expensive why not use the chlorox method to dissolve your foils? The added advantage is that bleach is cheap and easily available and works well on powders and foils.



I use nitric only for dissolving base metals, but I think so this is not the most cost efficient way to get rid of unwanted elements. OK, the AP method is cheap and seems easy to use and I'll try it too after I'm done with this poor man's AR experiment. 8) 
Thanks fo your replies!

Matt


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