Where is my gold? The gold is missing!

[[AuCl4]-]

Hello, I need help with this please.

I have a batch of fingers, cpus and pins that I dissolved with AR. I boiled the batch until all metal was dissolved. I didnt treat with HNO3 first because I didnt have that knowledge when I started this batch. When I poured the solution off, there was a green crystalline covering everything............It was quite beautiful but didnt take a picture but it looked like this........... http://en.wikipedia.org/wiki/File:Cupric_chloride.jpg

I then gently boiled down to a syrup and added a little HCl to get rid of HNO3 and added water.

I then filtered and put into 3 bottles and left overnight. The solution was very dark green almost black in the jars. I then pored off the solution leaving the white sediment in the jar. I then boiled lightly the solution and the cloudiness went to more sediment. I then left it overnight and the solution is dark green but very clear and no cloudiness.

I filtered the solution and now I have 3 jars and all 3 test negative for gold with SnCl2. The SnCl2 was old so I made a fresh batch and tested again.........Negative for gold.

I then thought that I messed up the test solution so I tested it on some left overs from the first batch before this botched one and it is nice and black..........positive!

So now here I am thoroughly confused staring at my 3 bottles.

What happened to my gold? Where is it? Did I boil it away with the steam?

 

[Geo]

its not a good thing to process all those mixed materials at once. when you did the dissolution, was there ANY base metal left undissolved? also, what kind of CPU's? if it was the fiber type, theres copper plates between the sheets of fiberglass. gold can cement to this copper and be trapped in the fiberglass sheets.the first thing to do when doing a dissolution on mixed material, is testing. make sure the gold is in solution before you continue. your gold could still be in the material left from the dissolution.

you said copper chloride crystal was on everything. put this in a container and cover with hcl and warm. im betting the gold is on base metal under the crystals.

 

[patnor1011]

Your 3 bottles can go to stock pot. Your gold is on and in whatever was left when you made them 3 bottles - container, bits of undissolved metal, filters, sediments....

 

[[AuCl4]-]

Hello, Thanks for replying!

what kind of CPU's?

I had 1 ceramic and 3 or 4 fibre plus north and south bridge chips.

was there ANY base metal left undissolved?

When I was boiling in AR I saw tiny metal swirling around but I kept boiling until I couldnt see any more metal.

the first thing to do when doing a dissolution on mixed material, is testing. make sure the gold is in solution before you continue. your gold could still be in the material left from the dissolution.

That was a mistake that will never happen again!

you said copper chloride crystal was on everything. put this in a container and cover with hcl and warm. im betting the gold is on base metal under the crystals

Oops, that poses a problem. When I saw the green crystals on everything that was left in the pot, I added water and swirled it around till it went into solution and poured it in a bottle. This bottle is aqua blue colour and the other two are dark green

I then put all the leftover cpus, chips......in a funnel wth filter and put it on a rinse bucked to get it out of the way but it fell into the bucket!

When I did filter the solution, I had white sediment, grey sediment and this fine black sediment with it. I never saw the grey and black in the first batch that I did successfully by pure blind luck.

Here is the sediment............

Here are my bottles...........#1 is more blue than green and it froze in the freezer. Too much water?
#2 is green
#3 is direct pour after AR...........No other treatments -it looks black but dark dark green it is.


So shall I follow your HCl procedure on these sediments? Could the black sediment be gold?

Many Thanks!

 

[[AuCl4]-]

Your 3 bottles can go to stock pot. Your gold is on and in whatever was left when you made them 3 bottles - container, bits of undissolved metal, filters, sediments....

Thanks for the reply...I was afraid that would be the outcome.

I inspected most of the large cpus and other pieces after AR and swirling to get the green crystals off. There was nothing stuck to the outside of any of the pieces. They were clean.
Do you think the black sediment might be gold?

Thanks............

 

[patnor1011]

More than likely yes. If solutions in bottles are negative in stannous test and your leftover cpus are rinsed clean, whatever sediment is left after may contain your gold. But from breakdown of your material I do not expect any sizeable amount of gold, in fact amount of gold powder resulted will be hardly visible.

 

[Geo]

the first picture of the white and dark precipitate is where the gold would be hiding. throw nothing away until you find it.

rinse the sediment in water until the water stays clear. then give it a good boil in water to remove any water soluble salts. remove the water and cover the sediment with hcl and observe. did the color change? it should turn green from copper contamination. test this solution with stannous chloride.if its negative, decant and add to your stock pot. add hcl to cover the material and add bleach by a few ml's at at time and wait a few minutes between additions and stir until all the dark sediment dissolves. the white sediment that didnt dissolve with the first addition of hcl will remain as is.test the solution with stannous. NOTE: the solution will have alot of chlorine and the color may not last but a fraction of a second. just watch for the color change as the stannous hits the swab.

 

[patnor1011]

I would incinerate sediment first. He used AR so there might be nitric present. If he just rinse with water he may dissolve some values - gold if it is there is super fine and some of it may get lost in rinse water.

 

[Geo]

exactly, thats why i told him to test the hcl rinse. if its positive, he can just add the Cl then and finish the dissolution.

 

[patnor1011]

I reacted to this - I would incinerate before starting with this 8)

the first picture of the white and dark precipitate is where the gold would be hiding. throw nothing away until you find it.

rinse the sediment in water until the water stays clear. then give it a good boil in water to remove any water soluble salts. remove the water and cover the sediment with hcl and observe. did the color change? it should turn green from copper contamination. test this solution with stannous chloride.if its negative, decant and add to your stock pot. add hcl to cover the material and add bleach by a few ml's at at time and wait a few minutes between additions and stir until all the dark sediment dissolves. the white sediment that didnt dissolve with the first addition of hcl will remain as is.test the solution with stannous. NOTE: the solution will have alot of chlorine and the color may not last but a fraction of a second. just watch for the color change as the stannous hits the swab.

 

[[AuCl4]-]

Hello,

I would incinerate sediment first. He used AR so there might be nitric present. If he just rinse with water he may dissolve some values - gold if it is there is super fine and some of it may get lost in rinse water.

I did the boil to syrup and add hcl and do it again- twice ---Nothing but white steam
I also put 3-8 grains of urea in as per Lasersteve(I think) suggestion -- no reaction

I followed all procedures to rid HNO3........

So shall I continue with the HCl + Cl procedure?

Thanks to all..........

 

[Geo]

patnor makes a good point. if you incinerate the sediment before the hcl wash, it will reduce the copper to an oxide plus any stannic acid that may be present. then the hcl wash would be more effective.

 

[[AuCl4]-]

Hello, I followed your instructions Geo...

Add Water...........Stannous test negative

Boiled with water and decant

Add HCl to cover sediment.................colour change was olive green



Tested again.............negative

Add Cl bleach 3ml at a time...........added total of 25ml

Test with stannous.............



YOU FOUND MY GOLD!! Im so happy again.

I have never tested any solution and got this colour...........A deep Purple almost black but it didnt disappear and the swab is still black after 30 minutes!

Thank You Geo and patnor X 1000

I'm gonna let this sit overnight(that wont hurt anything will it?).

And tomorrow if you would be so kind to help me, I will get the gold out!!

Later.................

 

[Geo]

very good job. you are most welcome, glad i could help.

 

[[AuCl4]-]

Hello, thanks for the help!

I am ready to proceed now. So from the forum search I have to remove Cl from the solution by heating with a cover but not boiling.

Do I filter the solution to remove the sediment before heating?
I have to heat for over an hour?
How will I know when Cl is gone?
Do I add water to solution if it gets too low?

Thanks.............

 

[patnor1011]

I would add fresh HCl few times, if you heat slowly there will not be much of solution lost during heating. I would heat for about hour. Then I will leave everything to settle overnight, decant in the morning. Wash sediment with small bit of HCl and test with stannous. If negative then all gold is safely in decanted solution. Filter well, use funnel packed with some toilet paper tissue under coffee filter if you do not have proper filter papers. Drop with SMB.
Your solution looks dirty so I would wash dropped gold with HCl and refine that again. On that second step your filtered solution will be nice yellow crystal clear and dropped gold powder should be tan brown colour.

 

[patnor1011]

One more thing - when heating solutions with some amount of sediment do it in a catch pan of some sort and stir well. That will prevent too much of heat being build where sediment is, your container if glass may break from that temperature. Catch pan is there to ensure you will not lose values in case of break. I am using big stainless steel pan with cloth on bottom, my glass container sit on that cloth and I always have 1-2 cm of water inside pan.

I quickly draw what I mean, I am not good at drawing but you will get a picture of what I mean.

 

[[AuCl4]-]

Ok ,Thanks for the instructions patnor.

I will start and post my progress..............

Thanks again..........

 

[Geo]

the reaction that actually dissolved the gold in the sediment was this : sodium hypochlorite (bleach) is dissolved and then decomposed by the hcl. this releases chlorine gas in the solution. chlorine gas will dissolve gold.

chlorine gas (being a gas) will not stay suspended in solution at normal atmospheric pressure, it "gasses off" or the gas is actually under pressure in the solution. if left uncovered long enough undisturbed, the chlorine will leave the solution and the solution will be chlorine free. its hard to determine if all the chlorine is dissipated by looking at it. when you start to pour the solution into the filter, thats when you will know if theres chlorine left because there will be a strong smell of bleach. chlorine gas is heavier than the air and will fill a container without flowing out over the top, if you tip the container the gas will pour out like water.once its disturbed by pouring the liquid into a funnel, you will be able to smell the gas.

before you precipitate the gold : after you filter the AuCl solution and you are ready to precipitate, double the volume of solution with water. wait fifteen to twenty minutes and observe. did any white powder precipitate? if yes, filter again.if no, add a spoon full of SMB to 50 ml's of warm water and stir. it will dissolve quickly.add this to the solution and stir with a non-metallic utensil. the color should change within a minute and darken. stir again. wait for the powder to settle. since it was a dirty solution, it may take an hour or more. test with stannous chloride. if its positive at all, add half as much SMB as before and stir. if negative, you have precipitated all the gold.leave the solution uncovered and do not disturb until the solution is crystal clear.

 

[[AuCl4]-]

Hello Geo, I am heating as I write. I just got back from the store and was thinking of the chemical reaction of NaClO and HCl while driving. I go into the 'lab' (garage), logon and you have explained it. What are the chances of that happening?

Thanks for the info..........that clears up quite a lot.

Patnor, great suggestion about the fail safe drop pan. I have been thinking of rigging a water/liquid bath to heat evenly. Essentially, that is what your design is!!

Not only are you two steeped with refining knowledge, your mind readers too!! :lol:

This forum just gets more amazing every day!!!