tek4g63,
I work a late shift, and know how one can burn his candle from both ends.
I will try to post a process, that may cover more than what your dealing with, but that can help you or others when dealing with these solutions, tin and lead can be troublesome, and since we deal with a lot of these metals from electronic scrap, we need to understand how to deal with them. You may not need all of these steps below depending on the conditions of your material, and I may add some details that are irrelevant, or you may not wish to use, also I have put in a long day so I do not know i this post will come out as just one long rambling on.
If tin is involved, (like if you had trouble filtering the previous solutions), I would neutralize the powders with sodium hydroxide, wash in hot water to remove the salts that form from this reaction. this would help to remove chlorides that with silver or gold can become volitile during the inceneration process,
NaOH + HCl --> NaCl + H2O
(Notice in the reaction above the strong acid and the strong base (caustic), gives a neutral salt water you could drink, or put on french frys, when either of the two starting ingredients would burn your skin).
Dry the powders and incinerate red hot, to oxidize the tin and other base metals. Cool the powders, then a hard boil in HCl, adding just a little water at the end, (not too much), lower heat but keep hot to let the insoluble powders settle, and decant the HCl wash with the dissolved metals, water washes till no more color, (depending on conditions the HCl and water washes may need repeated). (if tin is not a problem this step can be skipped when dealing with your white salts).
Copper I chloride (if you did not dissolve it out earlier in the incineration and boiling HCl wash's, we used to get rid of the tin problem above), (this copper I chloride can be removed before the lead or after the lead) the copper I chloride can be dissolved in hot HCL, the color of the solution will be very dark brown if you have a lot of this powder, a less saturated solution will look green, and very little copper in solution can look blue, I would use HCl till most of the copper chloride is removed and then do hot water washes until clear, (these hot washes will also dissolve lead and the Nacl salts the lead will precipitate when cooled the salt will stay in solution as long as solution is not saturated).
The salts should be somewhat acidic to begin with (if you have neutralized them previously bring the pH towards the acid side with a little HCl), if they came from acid solution previously just proceed with the washes.
I would boil in water, lower heat to let powders settle, but keep solution as hot as possible, this will dissolve lead chloride and any table salts NaCl. When powder settles (silver chloride is fluffy, gold can be small flakes that will swirl in solution, and takes time to settle, silver chloride you can see it, the silver chloride will look white a fluffy powder cottage cheese or like milk in solution, silver will not be clear in the solution like the lead chloride, or table salt in the hot water wash, decant this hot solution into a cooling jar, I use the suction bulb tool to decant, a trick is to cut a pipette and to fit it on the end of the suction bulb, this gives a small opening, able to pick up drops of solution) and a longer reach when getting down into the bottom of a tall vessel), you can decant your solutionand then through a filter into your cooling jar, filtering of these washes should be done hot(you can forget the filter and go straight into the jar also, much depends on conditions of solutions and how you wish to work, (in this jar when cooled you will see the lead chloride precipitate, the salt NaCl will remain dissolved even when this water wash cools), you may also see some color from copper or some other base metal in this solution, repeat these washes until you get no more lead chloride forms when the decanted solution cools.
Copper I chloride (if you did not dissolve it out earlier can be remove after the lead and NaCl.
Sometimes I will use two cooling jars and return the cooled liquid back to the boiling pot to pick up more lead (to lower my waste volume), one jar is cooling of while the other is taking the hot solution, this is only needed if your dealing with large volumes of these white powders, if you use this the later washes should use fresh water.(this is not necessary just one trick I will use), (on another note: as solutions of most metals will dissolve more metals in solutions and saturate when hot, and precipitate the metal salts when cooled, I will sometimes use this to remove metals from a solution using the same solution and temperatures to transfer the metals, or even dissolve and precipitate them from the same solution , like using saturation points to do a job), (if this paragraph if confusing just disregard it).
Now where am I ?
We have removed the NaCl, PbCl2, and CuCl, and some other base metals, that should leave us with silver chloride and gold, well lets not use the ammonia here this time to dissolve silver as it can be dangerous if we do not understand all the dangers, we can use HCl and bleach to dissolve the gold from our silver chloride powders, I will not go into all the other details on this, except to say the silver chloride is insoluble for the most part in this solution, also I can add that the remaining powders we separated can be
re-crystallized for higher purity, and I save my lead salts (figure I will use them some day), and also remember that the silver chloride will need cleaned up and converted to metal silver powders before melting, if you only have small amounts of these powders label jars and store them until you get a jar full to process, the silver chloride should be kept wet, just a little wash water covering them in the jar and a plastic lid (so rust will not become a problem).
Hope this rambling on makes sense, as I am very tired, I also hope his is somewhat useful.
Read Hoke's, do her experiments, that is where you can learn the things I have tried to explain here, for me almost every recovery and sometimes refining is can be different and how I may deal with it can change, but the principles do not change, so learning the principles Hoke's teaches lets you know how to adapt your process to circumstances or challenges your faced with at that moment.
Read it until it is as clear as the blue sky, after recovering and refining for a while if you going back to reread her book you will see things you never saw the first few times you read that.
Well it’s off to bed with a good book for me,
You have a good night.
I'll say 3+oz :roll:
