Extracting gold from heavily plated RF connectors

[arie_pk]

Hi
I received 3 pounds of 24k plated rf connectors. In order to assay the value, i put 60grams in AR, and got 0.6G of gold powder. I decided to use nitric acid and get the gold foils on the rest of the 3 pounds, and use AR on the foils to get pure gold. (I do not have a deplating cell yet). So after the nitric acid I got the following in the same container:
1. A bunch of beatifull gold foils.
2. Some of the connectors were stainless still gold plated, so were unaffected by the nitric and remained intact together with the gold plating.
3. Some of the connectors had plastic parts, so the plastic pieces were also inside entangled with the foils.

I poured AR an the lot (1 part 68% nitric and 3 parts 30% muriatic) and put on a heating plate on very very low heat (to compensate for the cold weather). The reaction was slow at first, but after few minutes it become extremly violent. Everithing started to boil and about 1/3 of the solution overflew from the container. I could not approach until it settled down, (it only took a few minutes, and when it stopped, i had a thick (texture of fat unskimmed milk thickness), brown reddish or brown orangy sollution. I removed to solution to another container, and what was left on the bottom was the stailess still conectors minus the gold plating, and some pieces of plastic. I let it sit for a day and the brown orangy cloud settled down to about one third of the whole solution (see attached picture ).
The upper part of the container is very dark color almost black. I tested the upper part for gold, and it came negative, so obviously the gold is in the orangy lower part of the container (can not test it).
The question is:
1. What did I do wrong
2. How do i continue and get what is left of my gold?

Thank you very much

 

[arie_pk]

I mean, how can this orange cloud happen in AR. It was all pretty sraight forward staff here. Gold flakes, stailess steel. The only out of the ordinary thing was the pcs of plastic (and or small pcs of rubber). How come i do not detect any gold in the upper part of the container?

 

[JustinNH]

I don't know the exact reason, but im 95% sure this question was asked somewhere on here since it sounds so familiar... I think it has to do with the stainless.

I know you shouldn't have done AR on the stuff since theres so much base metal vs. the plated gold. You probably should have waited to set up the cell, but I'm no expert, just basing it off things I read here. I stay away from plated stuff for now.

 

[lazersteve]

Arie,

Your cell parts are on the way.

The orange brown powder is likely a mix of compounds including iron nitrate, iron chloride, and possibly some gold powder.

The color I see in the photo is exactly like what I see when nitric is used on steel materials.

You should have dissolved all the base metals before moving to AR.

The overflow should have been contained in a deep flat bottomed corning ware casserole dish under your reaction vessel.

The gold is likely in the bottom of the beaker and/or all over the ground where the reaction took place.

Add the nitric slowly, in small increments to your HCl to avoid boil overs. Especially when the solution is hot. Never fill your beakers more than 1/2 full when working with reactions that off gas violently.

Filter out the sludge and remaining solids, wash with water, then HCl, then water again. If any large pieces of steel remain remove them and treat the solids with AR. Don't forget the corning ware dish under your beaker this time.

Steve

 

[arie_pk]

Any suggestions how to deal with the current situation, and recover some of the gold from this strange mixure?

 

[JustinNH]

I think the last line of Steve's response answers your last post...

 

[Harold_V]

Any suggestions how to deal with the current situation, and recover some of the gold from this strange mixure?

Assuming the solution is barren, I'd use the same trick I always used. I'd decant the solution, then rinse using tap water until the resulting solution was relatively free from color, having decanted by siphoning each rinse. Then I'd get the lot in a filter to remove residual traces. Your objective here is to eliminate the barren solution from the solids, so discard the solution by acceptable means. Be certain to test with stannous before discarding.

Once the filtered solids are dry, I'd incinerate, then I'd put the resulting solids in a mortar and grind them well, so they could pass a sieve. I would remove anything that was magnetic, putting it in the stock pot in case there were traces of values included.

I would then boil the solids in HCl to remove unwanted substances (I expect there is a serious amount of iron (rust) in the mix at this point). I expect this process would reduce the volume of material substantially.

I would then rinse the material well with tap water, siphoning off the rinse after it has settled well, until the rinse was absent color, although it may be cloudy.

Lastly, I would attack the remaining solids with AR to dissolve values. I would apply the AR to the still wet material, I would not filter.

I would rinse the material, adding the rinse to the decanted values. I would then filter the solids to recover traces of solution that contain values.

I would likely incinerate the solids after filtration, and place them in my waste materials for future processing by furnace. They will contain traces of values, and may contain silver chloride.

That's exactly how I'd deal with what you have. YMMV.

Harold