# Help on dirty Aqua Regia solution with Clorox



## robertpdickson (Jul 31, 2012)

First off....I read Hoke so I am asking for advice and not being lazy.

Stupid me; I tried removing gold plating from CPUs and plated pins from circuit boards. My first batch is small to allow for errors like this. First I added HCL and sodium hypoclorite to the beaker of scrap. Second I added Nitric Acid and let it react. I let it react for 24 hours and removed the garbage scrap. Third I added 1 part water to solution and I am left with a dark blue-green solution with dark sediment in the bottom of the beaker. Does anyone have a suggestion on how to rid the solution of the unwanted base metals and convert to a clear yellow auqa regia solution to drop the gold? Thanks in advance for any help.


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## gold4mike (Jul 31, 2012)

First question:

When you removed the "garbage scrap" was there any metal left undissolved?


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## maynman1751 (Jul 31, 2012)

Where did you get the idea to run HCl/Cl and then add nitric? HCl/Cl is a refining process and not for recovery. You could have used the nitric by itself to start and been farther ahead. I'll let the more seasoned members handle it from here.


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## robertpdickson (Jul 31, 2012)

GoldMike: When I removed the scrap there was very little metal not dissolved. 99% was gone.

Maynman: Because I took someone's advice and didn't listen to my own brain.


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## jimdoc (Jul 31, 2012)

What exactly was in this small batch? 

Jim


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## robertpdickson (Jul 31, 2012)

RAM chip "fingers" and CPU and several cell phone keypad contacts.


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## maynman1751 (Jul 31, 2012)

I suppose that you could try cementing with copper. Take all of your solutions and add a piece of copper sheet or busbar to see if any values will cement out. Do you know if all of the nitric was used up. Depending on the quantity of materials you may not have much to recover!
Use the advice that you get here and you won't go wrong!


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## gold4mike (Jul 31, 2012)

Since you had some undissolved metal your gold is most likely no longer in solution. It has most likely cemented back out.

Question #2: Have you made Stannous Chloride yet? If so, what did the test of your liquid show?

If you haven't made it yet - why not?

You're working blind if you don't have Stannous Chloride.


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## jimdoc (Jul 31, 2012)

robertpdickson said:


> RAM chip "fingers" and CPU and several cell phone keypad contacts.



I should of worded that "and how much of that stuff?" grams a pound?

Jim


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## Geo (Jul 31, 2012)

i hope you didnt throw away the "garbage scrap". there was no gold in the solution you were working on. the first thing you should have learned about the way metals dissolved (if you did read Hoke's book) is that the most reactive metal will dissolve first. if you have an excess amount of oxidizer in solution, gold will dissolve alongside the base metal. as soon as a point is reached where the oxidizer is depleted enough, gold with stop being dissolved and will start cementing out of solution on whatever base metal is left. this happens faster in a warn solution. when you dissolve PM bearing scrap that has mixed metal (which should never be done unless you understand what i just typed) all of the metal has to be dissolved to completion.


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## robertpdickson (Jul 31, 2012)

I will test with Stannous Chloride tonight. The amount that I "practiced" on was a small amount because I was suspicious of the "ease" to remove gold plating via this method. I really appreciate the feedback and help. Thank you.

Yes, I did retain the "garbage" as well just in case it did cemet to the scrap. The amount of scrap total was 50.15 grams.


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## robertpdickson (Jul 31, 2012)

Okay guys this is unbelievable but....It seems that there was some method to the gentleman's madness in the HCL Clorox bleach foil removal. To answer some questions posed by the folks on here. A Stannous Chloride check of the solution proved to be negative for gold. I poured off the mixture and left the fine mud at the bottom of the beaker....which low and behold contains the gold foil from the computer parts....undissolved. At this point I will further clean the mud then apply the Aqua Regia process and drop the gold with sodium bisulphite.

Apparantly for dirty computer parts the HCL and Clorox releases the foil from the pins, cpus, and plated fingers without dissolving the plating. My fault was adding Nitric to the solution before I neutralized the solution and poured it off.

Fascinating stuff and will I continue this thread until the end of my processing for you info. Again, thanks all for your help and advice.


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## jeneje (Jul 31, 2012)

robertpdickson said:


> Okay guys this is unbelievable but....It seems that there was some method to the gentleman's madness in the HCL Clorox bleach foil removal. To answer some questions posed by the folks on here. A Stannous Chloride check of the solution proved to be negative for gold. I poured off the mixture and left the fine mud at the bottom of the beaker....which low and behold contains the gold foil from the computer parts....undissolved. At this point I will further clean the mud then apply the Aqua Regia process and drop the gold with sodium bisulphite.
> 
> Apparantly for dirty computer parts the HCL and Clorox releases the foil from the pins, cpus, and plated fingers without dissolving the plating. My fault was adding Nitric to the solution before I neutralized the solution and poured it off.
> 
> Fascinating stuff and will I continue this thread until the end of my processing for you info. Again, thanks all for your help and advice.


Why would you use AR to process the foils, It would be better to wash with water to remove any contaminates and then disolve in HCL/CL then drop i would think, if i'm wrong here i will be corrected.
Ken
edited; if you use AR you will have to denox your solution, using the HCL/CL you only have to allow the CL to evaporate from the solution say 24hrs.


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## NobleMetalWorks (Aug 1, 2012)

Sounds like to me you didn't have enough oxidizer in solution so the gold foil was never able to dissolve fully, and whatever might have dissolved ended up cementing out again, thus your "mud". As Geo said, other metals will dissolve before Au, and if this is the case, the base metal under the gold foil could have dissolved before the Au, but there was not enough oxidizer to then attack the Au. Not having the base metal to hang onto, it then foils off. This does not mean that HCl/Cl will foil gold, it means if you don't have enough oxidizer, there is a possibility that Au will foil off without dissolving. But this is only a possibility, and you would have to have the perfect amount of oxidizer to do this without dissolving Au into solution. It almost sounds like you expect the HCl/Cl method to act like AP, but even AP will dissolve gold if there is enough oxidizer present in the solution. It's all about observation, understanding, and craft work.

I try to use HCl/Cl for as much recovering as possible, with the exception of things I can enter into an AP tank. Like people have posted before, you just have to drive off the Cl. HCl/Cl readily dissolves Au so long as you have enough Cl to complete the process. If you have a piece of china, or a glass, coffee mug, etc with gold around the rim, make up a small batch of HCl/Cl then put your item with the gold trace in the solution and watch how incredibly fast it dissolves right off. It works perfectly so long as you have enough oxidizer ( Cl ).

If I were you, I would wash everything you have, really well, retaining and testing the rinse solution for values with Stannous Chloride before wasting it. Then I would make up a fresh batch of HCl/Cl and enter your material into the solution, or rather carefully and slowly pour without splashing, your HCl/Cl solution into your cleaned/washed material. Then observe, half of what we do when recovering and refining is observing. If you have read Hoke, and you have done your familiarity tests, you will have learned how to observe reactions, and if you have read enough about HCl/Cl, you will be able to observe and understand what your solution is doing, and how much more oxidizer you need to add, in small increments, to achieve a total dissolution of the Au. It is the same exact thing when you use AR, and you slowly add Nitric Acid. You would make small additions of Nitric waiting and observing the reaction, until you observe that all the PMs have been dissolved into solution. Nitric acts as the oxidizer, the same as bleach does in HCl/Cl.

Scott


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## robertpdickson (Aug 3, 2012)

Well sadly I must say I am now stumped. I took my Au solution used UREA and distilled water at 1 parts to 2 and tried to drop....no success the sodium bisufite dissolves. So I added more until the solution would no longer take anymore and let it sit.

The next day I filtered the solution again to rid the white colored sodium bisulfite out and retested with stannous. With a more highly diluted solution it turn dark brown to almost purple. 

I've included a photo of the solution. If there is any hope of recovery; I would appreciate any advice? A picture of the solution is attached.

Thanks again all!


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## butcher (Aug 3, 2012)

The solution looks to contain gold (although iron compounds can also be yellow),

Your stannous chloride may not be able to tell you much if there is excess oxidizer in solution (the stannous chloride reduces the gold dissolved in solution to metal, to give the violet color, if there is oxidizer in solution like chlorine gas or nitric acid, then the stannous chloride cannot reduce the gold to the violet looking metal),

Too much SMB can also give a brown reaction to the stannous chloride test.

At this point you have several options to try and determine if oxidizers are involved (use the evaporation method to remove nitric in solution,using Harold's trick of adding a gold button will help here you would not have to evaporate the solution so much), or if all else fails you can always cement the values from the acidic solution using a copper buss bar. 

I would try to rid nitric and then retest, if you wish you can take a small portion from the main batch in a test tube and experiment with it on a small scale, add a foil of gold and heat solution to use up any nitric acid (if the gold foil dissolves add another until it does not dissolve the gold with heating), then the try the stannous test, if the stannous chloride test then works, you know several things gold will reduce to metal, you did have gold in solution, oxidizers were the problem.


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## goldpete (Aug 4, 2012)

my comment is to robert.
at no time have i seen you say you have evaporated the nitric or cl . i was having the same problem youve had , and i had the same result youve had , untill i learned that i needed to add sulfuric aid then evaporate using the proess in hokes book.

i am now getting fine black sediment which i assume is gold but i wont know until i try to melt it , im waiting till i get enough because i only do small batches at a time


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## robertpdickson (Aug 4, 2012)

To the last post....the sulfuric acid and evap. Going back over my notes I realize now that I did not use sulfuric after adding more Nitric to speed reaction. (Suffering from newbie acid usage I guess) I will add about 10 drops of sulfuric and evaporate in a sand bath and post the results.

Again thanks for everyone's help. It is much appreciated.


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## goldpete (Aug 4, 2012)

ok buddy , good luck .and please becareful you dont add too much nitric because it is the nitric you need to evaporate off.

id like to also find out , when you evaporating off the nitric , did you let it heat untill it becomes a syrup , then add some hcl and evaporate again? and repeat that adding hcl untill you get nop reaction ?
then adding 3 times your solution in water ?

also you might need more than a few drops of sulfuric , you need one ounce of sulfuric to each quart of solution.
please be careful because as soon as you begin to add it , it will violently react and splash back at you

do you remember i said to you earlier that i have made your mistakes before ? . well here is a pic of my solution at that time , i hope this helps you.
this pic is a solution that had been evaporated but i didnt have any sulfuric at the time . i had added SMB and gold didnt drop , i didnt know why , but a week later when i got some sulfuric , i pour some in there and the sediment you can see dissapeared and i was left with gold at the bottom


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## robertpdickson (Aug 5, 2012)

Man that is/was identical to my solution. I filtered off the excess SMB and washed the powder with water.

I'm now going back to add Sulfuric and evaporation to rid the solution of Nitric acid. I will perform the HCL addition(s) to the syrup and then water and report back.

Thanks again!!!

Well, I just don't know what to say. After using the sulfuric to burn off the nitric I condensed the solution to a syrup and added HCL and repeated until I observed no more reaction. The last batch of syrup I added a 10mL amount of HCL and no reaction. I diluted the syrup with a 3 to 1 ratio with distilled water and I now have a clear green solution...not the golden yellow which I started with. And now my tests with Stannous are negative which leads me to believe that my test on the original AR solution was reacting to other metals vs. gold. I assume I lost the gold in my various washings and unorthox ways that I approached this. Now I will back up and try again. Practice makes perfect.

Any thoughts or advice?

UPDATE: It seems to have worked. Because my processes were a bit backwards the murky green solution (I made a mistake above) the sediment has settled into the black gold powder. Unbeilieavable.

Thanks again.


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## butcher (Aug 5, 2012)

How does your stannous chloride test react now?

Iron can give a yellow and green to a brown chloride in solution, usually on strong heating you will see a red brown powder of iron hydroxide which becomes insoluble in solution.

Hoke's book talks of how you may be fooled into thinking iron is gold in solution, and describes how to test for iron on page 100.

I do not know if you have iron, but as yellow as your solution looked in the photo it did not look like you had much copper in solution (copper will give solutions a green color very easily).

Was there iron in your original materials?


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## goldpete (Aug 5, 2012)

yes buddy , all seems like it still might be ok . what you have to do now is filter the solution. dont be concerned about the colour.............the last solution i heated turned black , i thought i had burnt it but when i filtered it , a beautiful golden colour came out ,, it was like magic. i couldnt believe gold coloured liquid could come from black horrible looking liquid


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## robertpdickson (Aug 7, 2012)

Well guys; it did turn out good. Wow was that a learning curve! Again I really appreciate everyone's help.

The final result was a black powder (I thought I had burnt it as well) but filters nicely to a bit of gold cake.


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## goldpete (Aug 9, 2012)

robertpdickson said:


> Well guys; it did turn out good. Wow was that a learning curve! Again I really appreciate everyone's help.
> 
> The final result was a black powder (I thought I had burnt it as well) but filters nicely to a bit of gold cake.


good job buddy


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## tomiyet (Sep 29, 2012)

Hello seniors, I stumble on this forum while searching for a solution to my problem on recovery gold from aqua regia
I soaked scrap cell phones boards in aqua regia over nite and I filter it but I was left
a cloudy yellowish solution. I try to decant after some time but still thick yellowish, I added urea but
d color remain d same. Pls any way out. 140 pieces of boards were soaked


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## butcher (Sep 30, 2012)

tomiyet,
If this were whole cell phone board you could have a mess in aqua regia, normally you would want to remove other base metals before using aqua regia.

The tin in solution from the solder on the circuit boards can rob you of your gold.

Base metals will cement gold from solution if there is any metal remaining un-dissolved, it can leave gold as fine black powder, or if everything dissolves it can make recovery of gold more difficult to remove from solution, by normal means, also you say nothing about removing nitric acid from the solution, or testing your solution for dissolved values.

At this point you have a problem and want help, the best help you will get is to be able to understand how to recover and refine properly, it would take a thousand answers to tell you everything you need to learn, but you are lucky there is a book free download in the book section that can help you begin to understand the many things you need to know it is called Hoke's book, it is very easy to read and understand, she will not tell you how to do cell phones but she will teach you everything you need to know to work on any materials you run across as long as you understand the principles she teaches.

At this point you need to put a thick bar of clean copper metal into the solution let it sit in a safe place cover it but do not seal it so gas can escape, this will cement anything of value out of solution, do not throw anything away (at this point you do not know where the values are).

Go to the book section and download Hokes book (links are also in many of the members signature lines), and start reading Hoke's (you will read about cementing with metals in her book), also read the safety section and dealing with waste.

Do not expect to get gold for a while, spend time studying and collecting scrap materials to recover the values from after you understand how, other wise you will just lose your money or values by not knowing how to recover or refine, we can help but first you need an understanding of how and why, this you will get after a lot of homework, we cannot tell you how to take every step you will need to take in this journey, but after you learn to walk we can help with the things that can trip you as you walk, and after you begin to learn to walk the forum will help you run.

Also be prepared this can be a longer journey than you think it is at this point.
there is a lot to learn in the art of recovery and refining of metals, it is not hard but takes time to learn, there are many small details that can trip you if you do not understand them, Hokes book will teach you how to recover or refine without tripping all of the time and throwing away the gold or other precious metals, and what to do any why, and how to refine what you recover to high purity, and how to keep from losing the values in your solutions, and teaches you how to tell when there is or is not values in the solutions.


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## tomiyet (Sep 30, 2012)

I've downloaded the hokes book. I will try and read


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## butcher (Sep 30, 2012)

when you come to the experiments, work on them they will teach you many of the things you need, notice how she pre-treat's materials, or sometimes uses different processes for different types of materials, eliminates troublesome metals like tin, and removes base metals before dissolving values, practice the testing of metals in solution like testing for gold using stannous chloride.

In her book she may say to boil nitric (this is a misuse of the word), notice she uses a steam bath which would not get hot enough to boil a solution of aqua regia, the correct word should have been evaporate not boil, as boiling an aqua regia solution would waste values, with evaporation the metals stay in the heated reaction pot.

tomiyet, 
Good job beginning to study, you will be getting closer to melting a nice pure gold button, than you would stumbling in the dark and asking questions.
If you do not understand something and need help the forum will be happy to assist where we can.


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## gold4mike (Oct 1, 2012)

Butcher said "Iron can give a yellow and green to a brown chloride in solution, usually on strong heating you will see a red brown powder of iron hydroxide which becomes insoluble in solution."

I believe I have a solution that now contains iron hydroxide and gold as powders on the bottom.

Is there a way to remove the iron hydroxide or can I simply dissolve the gold away from it?


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## butcher (Oct 1, 2012)

I find the brick red iron hydroxide powders almost impossible to dissolve into acid and will not go into solution much at all, while the gold will.


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## tomiyet (Oct 2, 2012)

Many thanks. I've been reading the book and quite interesting. Kudos to people in this forum, since my 17yrs of recycling this forum is the best I have come across.I wish I've not soaked my whole cell phones in the aqua regia. Nevertheless I believe I've come to a place of learning where resourceful people are.


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## butcher (Oct 3, 2012)

tomiyet,

Keep reading the forum is a gold mine full of good nuggets of valuable information.


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## cableman (Apr 6, 2013)

Sorry to get off subject but I am new at this and was reading your thread since it applied to me. I ended up with the same yellow solution but I know I had about 14 ounces of gold in it because it tested real black with stannous and I started with about 7 of the older ceramic cpu's. My main problem was ignorance. Instead of using nitric to dissolve everything off--filter the liquid off---then mix aqua regia to melt the remaining gold and then precipitating with SMB; I wanted to do it all at once so I mixed up muriatic acid (from Lowe's in place of hydrochloric), ammonium nitrate pellets in the place of nitric acid since it is so expensive to get with hazmat shipping and all, then I heated it all together with the broken up cpu's. I just knew that I would end up with a few good grams of gold even if I had to experiment a little but ignorance knows no bounds. I ended up with crystals that I didn't know what they were or what to do with and the whole thing goaded me because I could see gold flakes all around in the coffee pot I was using. The crystals got real bad and since I didn't know what to do I set it aside for a while until I could figure it out and started working on loosening up plated foils. Well, about the time I figured out what to do I had used my hot plate earlier and I guess it hadn't cooled down enough because when I put that glass jar on that burner I heard a crack and knew what was coming. Luckily none of those acids are flamable you just don't wan
't to breathe them and I had a bucket of sand directly under the bench where it happened. As soon as I picked up that jar by the top, the bottom fell out and about a quart of liquid with all my gold filled into my hot plate and all over a rug I keep on the wood table to help with spills. I was sick to lose that much gold and still had a mess to clean up and another hot plate to get. I learned my lesson good that day but what I wanted to ask you guys about is if you do manage to screw up a batch, what is the best way to just let it all come back to metal so you can start again? Throw a piece of copper or steel in or what? Once the nitric is exhausted then you won't have any chemicals there to make a reaction. Don't sweat the answer too much if you don't know right off, I just want to know for future knowledge. Seems like we always make the same mistake twice before it's all over with.

Another tip I heard about. If you were dissolving cpu's that salt you thought you had might have been silver. It looks more cloudy like and is hard to pin down like to filter or pour off. Just precipitate it with some table salt or ammonium hydroxide---just a bit mind you. It can also be that God awful anhydrous copper(II) sulphate crystals which happens a lot because of all the copper you are dissolving. If you catch the white flakes first starting just add a little more HCL. Sometimes you can add a good bit of warm water and heat it up to dissolve but that kind of decision is made on what all is still in there and what you still want to do with it. If It happens to you again and you get the nice yellow looking liquid and are just sure it's got dissolved gold in it but won't drop; it is probably still some acid around in it. Let it sit out in the warm sun all morning and see if you don't start seeing some gold precipitation with nothing but the help of the sun. If you think of a real simple method for me to drop all my metal back into one piece so I can start over please send me a note. I would be most appreciative. Good luck with your gold. I have been doing real well with gold fingers and pins but I am looking into a way to get the gold off the boards easier. I know there is an easy way I just cant remember it and it won't come to me.


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## butcher (Apr 6, 2013)

cableman, 

I know you already know what I normally say read Hokes and then do the experiments, keep studying the forum, it takes time and there are many things to learn, you will make many mistakes (and have a few broken pots).

a catch basin can catch a spill.

If you have a pot crack on the stove do not move it, grab your suction tool and remove the solution to a holding jar.

Getting the values back out of sand and dirt is a long hard task, you can recover some of it, one of the problems is that the iron or other metals in the sand or dirt will cement out the gold, the material needs collected dried crushed to powders and incinerated, leached of base metals, if your dirt is high in iron as mine is (you have a costly chore), after iron and other base metals have been removed then you can put gold into solution and separate it from the sand, you will still most likely have a leach loaded with base metals in solution that you will need to use copper to cement your gold from...


Keep ammonia or ammonium hydroxide out of any of your solutions, unless you truly understand the chemical reactions, explosive compounds could result from one mistake.

ammonia solutions will not precipitate silver.


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## solar_plasma (Apr 6, 2013)

> I know I had about 14 ounces of gold in it because it tested real black with stannous and I started with about 7 of the older ceramic cpu's.



Just trying to understand....you got 14 ounces out of 7 cpu's and you knew, it was 14 ounces, because your stannous test was black?


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