Recovering gold from cell phones

[bswartzwelder]

I have quite a larger batch of cell phones which I will be processing to recover the gold. All (or almost all) components have been removed by using a heat gun and melting the solder holding them in place. Now I have the basic bare boards with some solder still on them where the parts were connected. Do I need to soak these boards in HCl to remove the solder and then process in AP, or can I skip the first step and just process in AP with a bubbler? It would seem a waste of time to soak in HCl and THEN process in AP if processing in AP alone will accomplish the desired end result.

 

[Geo]

cell phone gold gets lost in AP. it doesn't come off in flakes but rather very fine particles like powder.as long as you know what to expect, it shouldn't be a problem. don't go straight to AR because of the tin.if you dissolve the solder in hcl first, you can go to AR but be warned : gold will not look like gold after that process.

 

[arthur kierski]

i never did it----but i am thinking of using hcl-clorox to recuperate the gold from the bare cell phones boards------ i would like some opinions about using the hcl-cl method----i used othe methods like cianide stripping--- ap------ or hno3 35% and was never satisfied--
thanks and regards
Arthur

 

[thorins]

hi all ive been using hcl - h202 (40) and am very satisfied. i do cell phones memory cpu and mother boards. the thing is i only stip off the steel and alum and screens. and drop the rest in the solution. no problems so far. only issue is the ashing from the spare coatings on the boards. so filtering is a bit of a pain..... but the pay off right now is worth it

 

[hciic]

well i have the same question I have 65% hno3 should i put first in the hno3 to remove the tin and some other base metals after that should i use the AR Process. Please just answer this question thanks.

 

[butcher]

Tin in HNO3 is a just a big mess it makes a thick gelatin in solution.

Actually tin in solution with HCl (and an oxidizer to dissolve gold) is not good either if you have gold dissolved in solution, it forms gold colloids that you cannot test for the gold in solution (reduced to colloids by the tin), the solution will not filter worth a darn, will not precipitate the gold colloids, and a major reason for you to loose your gold in the recovery and refining process.

To deal with tin it should be eliminated before dissolving the gold, or before using nitric acid, it will break down into solution in HCl alone, somewhat faster with heat, before you dissolve the copper or gold, if solder the lead chloride from the solder would be a white powder of lead chloride, the tin will stay in the acidic solution of HCl (as stannous chloride solution).

If you have used HCl on a material, you would need an incineration before treating your material in nitric acid (if you do not wish to dissolve gold), as any chloride in the nitric would form a form of aqua regia, even it was just a dried chloride salt on your material, the hydrogen in the nitric would form HCl in solution from those dried chloride salts.

If tin and dissolved gold is in a chloride solution, the tin reduces the gold, forming colloids, these colloids repel each other and will not precipitate, you cannot use the stannous to test for this gold that is held in solution as colloids because the gold is already reduced, the solution will not filter well, and if this solution is loaded with other base metals the problem just compounds this mess, tin is a demon that robs you of your gold, learn to deal with it, and keep more of your gold.

Colloids are worse in solutions that are less acidic, or dilute, heat and High acid can help some.

If your powders contain tin and gold incineration of the tin to oxide and boiling HCl, and hot water washes can help, to remove the tin, and if you are going to use nitric acid after you will need to incinerate again to remove the chlorides prior to nitric treatment unless your goal is to dissolve the gold, see Harold’s many great posts on this subject.

 

[publius]

Butcher, et al;

If the subject powder is small (say a few grams) in volume, could the powder be incinerated to turn the tin to an oxide then use a borax flux to collect/capture it (the tin oxide) while making a ball of Impure gold?

 

[Harold_V]

Butcher, et al;

If the subject powder is small (say a few grams) in volume, could the powder be incinerated to turn the tin to an oxide then use a borax flux to collect/capture it (the tin oxide) while making a ball of Impure gold?

My opinion?

Trusting borax to remove all of the tin is a long shot, most likely to fail.

Assuming I was in a situation where I had tin combined with precipitated gold (I didn't have that happen), I'd incinerate, then I'd do a hard boil in HCl, to remove the tin. I would then re-refine the gold.

Harold

 

[dtectr]

harold Actually helped me with this one - I had beautiful thick foils trapped in a white sticky paste. after a good roasting, i washed using hot, concentrated Hcl. The bright yellow indicated the dissolution of the tin oxide. a word of caution - it takes several washes so donmt get stingy. color of wash is good indicator, so use good lighting, when you see no more change, do one more wash.
from my "dumbphone" i can't link to it, but the result was the lovely 15g button I posted a pic of last year.
just my dos centavos.
dtectr