Processed Foils with HCL/Bleach, dropped with SMB, OOPS!

[kkmonte]

So I learned something today and figured i'd share my experience with everyone (maybe save someone some time who reads this, we all learn from our mistakes!).

I processed a pound of fingers in AP, cleaned foils in HCL, dissolved foils in HCL/Bleach (like i've done 4-5 other times before), everything went great. I diluted my Auric Chloride, heated it for a bit to help get rid of excess chlorine, let it sit overnight, and then added my SMB, let that go overnight, come back the next morning and all my gold was precipitated on the bottom like I expected. ( I still feel like a magician when I add my SMB and give it a stir and the color changes from yellow to clear/brown).

I tested my solution for gold, after 5 minutes, q-tip was still white, good to go! Then I thought, hey i'll save myself some acid and give it it's first boil in this same container! So I throw the beaker on the hotplate, put it on medium heat, cover it with a watch glass, I was neatening up my garage, picking up some tools, etc. Checked on it after about 5-7 minutes. The solution wasn't boiling yet, but it turned back to yellow! I was lack AH! Then I figured what happened was that I had some chlorine still in the solution and heating it forced it out and dissolved some of the newly precipitated gold. I tested for gold, and sure enough positive!

Do you guys think that is what happened? Is it possible to precipitate the gold with some free chlorine or chlorine in the solution? I know there was chlorine there because when I added some SMB it all fizzled. I then let it cool down and waited 8-10 hours, then went back and added some more SMB. (Most of the gold was still sitting at the bottom of the beaker, I think only some of it got re-dissolved).

So tomorrow morning i'll check it again and it should be clear again with (i'm hoping) all of the gold at the bottom. i'll test solution for gold and if no gold in solution, i'll definitely pour off all the acid before I heat it up again!

-Ken

 

[Geo]

either you had free chlorine or there has been nitric in the container before.when you heat an acid solution, it will squeeze all of the oxidizing power it can from whats left. ive seen this happen to gold powder being washed in fresh hcl.the container was contaminated with nitrates.it only takes a small amount of nitrates to dissolve an amazing amount of gold when heated.

 

[kkmonte]

Well must have been the free chlorine, i've never owned any nitric and never used any in my glassware. THanks Geo.

 

[giannitsa]

hi and sorry to speak.
i wand to tell you what i done.

i dissolve ceramic dishes and plates with gold around . its dissolve very good. but i MAKE IT ALL WRONG. I use CL like idiot and the same with SMB. the gold its not go down.
now i put lye (sodium hydroxide) and now i see in the bottom of my jar yellow/orange powder . i use only gold.

its gold hydroxide ?? and now what i do??? i take away the powder and dissolve again with HCL+CL or i burn it to make metal???? or i go to watering my neighbor tree :lol: ... i make joke. :twisted:

please help me............

 

[butcher]

I know you make joke about watering neighbors tree, but I do not find it funny, as we both know we could poison the neighbor and ourselves with that kind of joke.



Here is how I would try to deal with your problem:

Separate the solution from the yellow orange powders.

First I would test the solution, take a very little bit of the solution, add HCl to make it acidic again, it up, A test tube would be best, let it cool off then do a stannous chloride test, if you have no gold this solution then treat the solution for waste properly, if this test show gold in the solution then you will need to treat it also for gold.

The yellow orange powder, I would add back HCl,to bring the acidity back up, after initial reaction I would add some heat, you may see it going back to a brown powder, or it may just dissolve again, once it is acid again, and the reaction slows add low heat raise the heat more until it fumes, but do not make it boil, let some of the water vaporize off, this will also vapor off any chlorine gas, SO2...

After solution concentrates some lower heat, but keep it warm (low heat), begin adding water, add about 3 time water, turn off heat, put into a clean jar, cover and let it sit overnight, in the morning you may, or may not see a brown powder.

If brown powder decant solution from the powder, test solution for gold with the stannous chloride test, if gold is in solution precipitate it out with SMB, using the stannous tests to Know when all of the gold is reduced, so that you do not add too much SMB again.