purple(pink)color liquid

[arthur kierski]

after dissolving solder fillings containing pd ,ag,sn,pb and little au with hcl for 1or 2hours and filtering ,i end up with a pinkish purple solution ----this solution after cooling, plate the container with this pinkish collor------could it be colloidal gold? or is just sncl2(stanous chloride ) solution---
note:in the botton of the container one sees a lot of brilliant crystals which i suppose that is lead chloride-------

 

[butcher]

Arthur,it sure sounds like gold colliods from tin HCl, and gold, similar to testing with stannous chloride, mixed with other junk.

unoxidized tin will not dissolve in HCl well and it likes trying to precipitate your gold making purple of casius.

many of the metals you mentioned are insoluble as chlorides in water, lead can be insoluble in cold water and slightly soluble in hot water, silver insoluble as chloride in hot or cold water, as long as it can settle, and fine powder can take time to settle.

with this batch all these metals soup and muds, even fairly insoluble metals can be held in solution, even to the point of being a mush mix mess of metal soup, and dragged down precipitants mix of metals,it is unlikely anything will seperate easily and clean.

you will need your tool bag of tricks now,
inceneration, tin is a problem for nitric so eliminating it first , after inceneration, HCl will attack the oxide of tin and other base metals, settle well decant, now you need to rid all chlorides from these powders I would rinse well and incenerate again to rid chlorides, and then 50/50 nitric acid & heat, (settle decant and filter insolubles save for aqua regia), adding HCL to silver and lead nitrate, to convert them to chlorides,and precipitate them as lead and silver chloride, silver chloride is insoluble hot or cold in water, lead chloride is slighty soluble in boiling hot water, but lead chloride insoluble in cold water (you will have to let silver settle after boiling,while keeping solution hot just below boiling water(not fun it can take time for fine silver powder to settle) (I would use the same water for large batch of these two metals, as it will generate less waste [lead contaminated water] (boil water let AgCL settle, decant syphering with suction bulb helps, move 1/2 of hot PbCl water to another container, to cool, this cold outside helps here, once crystals of lead precipitate out return cooled water to heat to grab more lead repeat till as much lead as possible removed, you will also most likely have some lead following your gold into solution, here a little sulfuric can help if added to the end 3rd and last boiling while you are denoxxing your aqua regia as lead sulfate is insoluble. all of your metals recovered will need refined again at least one more time
all this work can lead you to wish you listened to Harold and Hoke.

{another option I suppose, would be to eliminate chloride and smelt and cupel a button.}

if at all possible removing your values from base metals should be practiced, it is does not take as much time is more efficient, better products, less loss, easier, how else can we say this? its a ell of alot easier.

more expierienced members may have better options or suggestions.

 

[arthur kierski]

thanks Butch for the reply and recomendations----tomorow i will have another batch of this material and will(incinerate ) oxidise the base metals and then hcl for at least one hour boiling--the material left as solid will be incinerated again and then hno3--- to the solution(chloride solution)i will look for pd (dmg) ----as it is a chloride solution it is obvious that no silver chloride will be present and if gold coloid is present it will be as purple(pink )color liquid because the stanous chloride test cannot be done in a solution containing stanous chloride already(formed by the boiling of the tin oxide with hcl)------if the solution becomes purple pink color i will try to precipitate the gold +pd and sncl2 with zn or hidrazine---then i will continue the process on the solids left by the nitric leaching, with ar----what happens with this experiment will be passed to you for further discussions----thanks for the moment from
Arthur

 

[Harold_V]

I had limited experience with that problem, but found I could easily recover the values by incinerating, as butcher suggested, then a boil in HCl. Rinse well (tap water is perfectly acceptable), then go after the values with AR. The resulting solution will filter, which it would not do without the HCl boil and rinsing. The remaining solids may contain traces of values (silver, as silver chloride, if nothing else), but in my case, they were simply incinerated and stored for future processing by furnace.

Those of us that have processed a large amount of gold filled (eye glasses in particular) face the problem you mentioned on a regular basis. It was for that reason I developed the process I recommend. I applied it to e scrap a time or two, although I processed e scrap only for myself, and then very infrequently.

Harold

 

[arthur kierski]

Harold,i understood that you are sugesting that i jump the nitric stage and after the chloride leach go to the ar -----am i correct?

 

[Harold_V]

Harold,i understood that you are sugesting that i jump the nitric stage and after the chloride leach go to the ar -----am i correct?

I found no need for it, but your case may be different. It would be very wise to follow the suggestion set forth by butcher, to insure that problematic substances are eliminated.

What I'd suggest is two small pilot batches, one run by each method. Which one works best would be what I'd pursue. You may find that the HCl wash alone will suffice, especially if your materials have already been subjected to a nitric digest. That was the case in my examples.

For the record, a couple of my customers were chiefly silversmiths. Their polishing wastes contained primarily silver, with traces of gold, at best. In their case, I'd incinerate, screen, digest with nitric, incinerate, then digest with HCl. Only after a good rinse would I attempt to recover any gold that might be present. Otherwise the solution bordered on impossible to filter.

I'm of the opinion that regardless of the processes one uses, values that are recovered from grossly dirty solutions will never be acceptable in quality, so I often insured the resulting solution would filter, and ignored any of the residual problems, simply to recover the values, which were then purified by a second refining.

Do keep in mind, I am not a chemist, so some of my processes may have been elementary and basic, but they were strangely effective, and I rarely processed volumes large enough (aside from re-refining my own gold) that a little inefficiency was troublesome. Lou, with his vast knowledge and understanding of chemistry, may be able to provide better guidance.

Harold