Gold out of filters

[gary492]

so i took cell phone boards and did ap and i filtered it with coffee filters and let the filter dry for 2 days now what do i do with the 10 filters how do i get the gold out of them im not going to burn them so dont say it

 

[Geo]

if the filters are completely dry, take them one at a time and turn them upside down on a clean sheet of paper and slowly and gently tap the bottom of the filter. this will dislodge the foils, also you can use a clean 1" paint brush and gently brush the foils onto the paper. any finely divided pieces will be very light, so any puff of wind will make you have a bad day. after each filter has been brushed, crease the paper on one end and dump the foils into a glass container with a screw on lid and move to the next.

after you are done with all the filters. place them in a ziplok bag so you can process (burn) them later when you have enough to warrant it.

 

[samuel-a]

Whenever i have filters which holds a significant amount of gold (foils/powder) i do the following:

• - I fold the filter (either dry or wet) to quaters and then to eights.
  - Then, with scissors, cutting small pieces and let them fall in to an empty beaker.
  - Then cover the shredded paper with HCl to about 1/2 in above the paper line.
  - Add few ml of nitric acid and bring the solution to a boil, usually for about 30 miutes.

It is very inportant that you cover the beaker with a watch glass or have some sort of refluxing since gold chloride does tend to steam away upon boiling.
Covering an open mouth beaker with watch glass isn't bulletproof methode, but will limit the loss to an acceptable minimum.

While heating, the solution will gain colors and the paper should loose colors. Keep at it until you see the paper clean of powder, foils and stains.
The extremely acidic and oxidizing environment of boiling AR will break down the cellulose transforming the paper into a gelatinus like pulp.

• - When completely cooled down, the pulp will rest at the bottom, so i filter the bulk of the solution first, let it all drain through before proceeding.
  - Then add water to cover the pulp, mix vigorously and pour the pulp+water+left over solution into the filter. Let it drain for few minutes and add water to the filter until the pulp is clearly white without any hint of the yellow/green solution.
  - Proceed as usuall and treat this solution as any gold chloride solution, De-NOxx if needed (though, it is better not to use too much nitric to begin with).

Filtering and washing this pulp is easy and the filter paper does not get clogged by it.

 

[jeneje]

Whenever i have filters which holds a significant amount of gold (foils/powder) i do the following:

• - I fold the filter (either dry or wet) to quaters and then to eights.
  - Then, with scissors, cutting small pieces and let them fall in to an empty beaker.
  - Then cover the shredded paper with HCl to about 1/2 in above the paper line.
  - Add few ml of nitric acid and bring the solution to a boil, usually for about 30 miutes.

It is very inportant that you cover the beaker with a watch glass or have some sort of refluxing since gold chloride does tend to steam away upon boiling.
Covering an open mouth beaker with watch glass isn't bulletproof methode, but will limit the loss to an acceptable minimum.

While heating, the solution will gain colors and the paper should loose colors. Keep at it until you see the paper clean of powder, foils and stains.
The extremely acidic and oxidizing environment of boiling AR will break down the cellulose transforming the paper into a gelatinus like pulp.

• - When completely cooled down, the pulp will rest at the bottom, so i filter the bulk of the solution first, let it all drain through before proceeding.
  - Then add water to cover the pulp, mix vigorously and pour the pulp+water+left over solution into the filter. Let it drain for few minutes and add water to the filter until the pulp is clearly white without any hint of the yellow/green solution.
  - Proceed as usuall and treat this solution as any gold chloride solution, De-NOxx if needed (though, it is better not to use too much nitric to begin with).

Filtering and washing this pulp is easy and the filter paper does not get clogged by it.

Hey samuel-a, just a quick question here, want HCL+CL do the same thing without boiling the solution. Just curious here.
Thanks
Ken

 

[gary492]

ya could i use hcl=cl instead

 

[Claudie]

I had a few filters that had quite a bit of visible Gold powder trapped in them. I used those filters, one at a time, to filter a solution of HCL/Clorox that I was using to filter some solder mask from dissolved Gold foils. As the solution filtered, it dissolved the Gold that was trapped in the filters. I rinsed the filters, then put them with my other used filters to incinerate later. The filters looked pretty clean after rinsing.

 

[goldsilverpro]

If they're mostly a gold proposition, I just incinerate them to a white ash and then use aqua regia. About a year ago, I got 5.8 oz out of a fairly well-packed bucket of filter papers and paper towels that were used to mop up drips or spills or for such things as wiping out gold powder stuck on the insides of a bucket (using a folded up damp paper towel).

I have incinerated by placing the heat underneath the steel pan, skillet, etc. I have also incinerated by adding some flammable solvent (not too much - you don't want puddles) directly to the papers, etc., and lighting it. They both work well but the solvent requires less setup. Either way, it helps to stir it and keep turning it over - I often used a long big stainless spoon for this (restaurant supply). When using a solvent, I often used a 50/50 mix of gasoline and diesel. In Loewen's book, he uses charcoal starter fluid. You need something that will burn slow. Whatever, when using a solvent, I let everything burn out and add some more solvent and re-light it. It might take several solvent additions to completely burn out all the black carbon. I usually put a screen over the pan until the flames die down somewhat. Then I remove the screen and start gently stirring.

After the flame is out and there are still embers, I have seen people use straight oxygen from a torch (turned real low), with stirring, to burn that last bit of carbon. This also works when you're heating from underneath.

 

[nickvc]

Chris can I be your trash man :lol:

I use the same method, never found 5+ ounces but it works and works well and dissolution and filtering is very easy.

 

[Geo]

i incinerate almost every thing thats non metalic. i may be wrong, but i was assuming he wanted the foils so he could show them off.

 

[nickvc]

I'm with you on incinerating everything non metallic, it all adds up over time and the prices right now makes it even more worthwhile. I'm a great believer in keeping low grade waste in a tradable state as turnaround on low grade can be slow, working through my copper cement right now, I'm sure it will have some Au and almost certainly PGMs, stannous test on small dissolved sample was a lovely red / orange colour, might even find the rhodium that seems to dissapear, should prove interesting only about 30 kilos of copper to remove :roll:

 

[goldsilverpro]

Chris can I be your trash man :lol:

I use the same method, never found 5+ ounces but it works and works well and dissolution and filtering is very easy.

I must admit that a lot of that 5.8 oz came as the result of a disaster. A 4 liter beaker containing hot aqua regia plus some gold powder that hadn't all dissolved decided to break all on its own. It was simply lifted up to move it and the bottom fell off.

 

[nickvc]

Been there done that too Chris....very annoying to be polite!
Good catchment is a saviour but you never get it all back at the time...

 

[Harold_V]

I must admit that a lot of that 5.8 oz came as the result of a disaster. A 4 liter beaker containing hot aqua regia plus some gold powder that hadn't all dissolved decided to break all on its own. It was simply lifted up to move it and the bottom fell off.

I experienced the bottoms fracturing on several occasions---all attributed to thermal shock. For me, it happened when I would be doing a digest of polishing wastes with HCl. If the material wasn't stirred until boiling kept it in suspension, where it settled firmly would get superheated, then any stirring would move the hot mass, resulting in rapid cooling of beaker where it was superheated. I usually heard the crack. I was lucky, though, don't recall any coming apart. I'd get them changed before they did.

Scratched beakers have that potential, too, and those I used for this operation were scratched.

Harold