Series of questions I've been saving up for 1 post [AP].

[n3vrs0br]

This forum is friggin awesome! I've been reading through so many threads here that I had to start jotting written notes! I love it! I just have a few questions. I didn't feel they were quite "Help Needed" material, so I'll post them here:

#1. SMB. How selective is it in precipitating? I may have a scant amount of Cu in my AuCl3. I base this on color of the solution. only under florescent light does it has an ever-so-slight greenishness to it. If there IS Cu in my auric chloride, will the SMB drop it too?

#2. H2O2. If I use the higher percentage solution from my local Beauty Supply World, can I merely adjust the amount used in solution based on the apparent math? (i.e. 300ml 3% = 30ml 30%?)

#3. I'm kicking myself for asking this because I KNOW I read a thread detailing it here, but I can't find it again. How to clean the base metals from spent AP solution and make it fit to be re-used?

#4. Fe. After scouring my workshop for containers, I found quite a few containers of perfect size for my reactions. They were used to store sets of old tire chains for the past 10 years and the white plastic pails are now rather rust-stained. Will this effect my results?


So my first batch, which is currently 200ml AuCl3, awaiting SMB via UPS, I'm predicting at least 1 troy scruple fine Au, based on the amount of foils from 1lb trimmed milspec pinboard. Photos I'll post in the Gallery!




Mike

 

[lazersteve]

#1. SMB. How selective is it in precipitating? I may have a scant amount of Cu in my AuCl3. I base this on color of the solution. only under florescent light does it has an ever-so-slight greenishness to it. If there IS Cu in my auric chloride, will the SMB drop it too?

Use no more than 2 grams of SMB per gram of gold expected. Start with a 1 to 1 ratio of SMB to gold, test with stannous chloride, and add more if the solution is still pregnant. Properly wash all gold by boiling in HCl until the HCl no longer darkens or changes color. Rinse well with water, then rinse in hot ammonium hydroxide, and finish up with three water washes. DO NOT mix spent ammonium hydroxide washes with HCl washes. TEST ALL acid washes with stannous before discarding.

Incinerate to red heat, redissolve, precipitate and wash a second time for higher purity.

#2. H2O2. If I use the higher percentage solution from my local Beauty Supply World, can I merely adjust the amount used in solution based on the apparent math? (i.e. 300ml 3% = 30ml 30%?)

Dilute the peroxide down to 3% before adding to the AP. This prevent the gold from dissolving rapidly like it would if exposed to the higher concentration peroxide without dilution.

#3. I'm kicking myself for asking this because I KNOW I read a thread detailing it here, but I can't find it again. How to clean the base metals from spent AP solution and make it fit to be re-used?

These are two different steps.

Removing the base metals is only required when you are ready to dispose of your AP solution (it grows as you use it, so disposal is inevitable).

To reuse AP, simply bubble air through it for 24 hours then reuse.

#4. Fe. After scouring my workshop for containers, I found quite a few containers of perfect size for my reactions. They were used to store sets of old tire chains for the past 10 years and the white plastic pails are now rather rust-stained. Will this effect my results?

Rust stains wash out very easily with diluted HCl, like they we never there. You may need a brush on very thick deposits. Don't forget your safety gear and good ventilation.

I'm predicting at least 1 troy scruple fine Au, based on the amount of foils from 1lb trimmed milspec pinboard.

That sounds like some very high hopes for a pound of pins, it will be interesting to see your actual yields.


Steve

 

[n3vrs0br]

Removing the base metals is only required when you are ready to dispose of your AP solution (it grows as you use it, so disposal is inevitable).
To reuse AP, simply bubble air through it for 24 hours then reuse.

So I would be well served to invest in a few ceramic aerators? I have a "stone" for carbonating keg beer, but I think it won't be well suited for this purpose as it seems to be metallic.
Also, I read reference to AP solutions that are completely saturated with base metals (usually copper) as resembling chocolate milk (spent,) and solutions that are still effective at pepsi-brown. Is this by using an aerator?

That sounds like some very high hopes for a pound of pins, it will be interesting to see your actual yields.

Yes, I know. But after a good bit of research, (mostly here) the boards I'm processing are what yall call "primo" grade scrap.
Since I don't have a press to remove the pins from the board, I used the table saw with a metal-cuttin blade to basically chunk 'em up (carefull not to knick the pins.) From 16"x8" boards to 1"x2-5" pieces for feed. My biggest obstacle is the sheer copper content of the feed. The boards are covered on the tops with thick copper track, and the underside is a veritable rat's nest of fine-gauge insulated copper wire.

What's more, I get these boards fully populated with ceramic ICs. Some are gold capped, gold pinned... Heck, there's even a few hand-soldered custom built ICs!
I weighed it out as roughly 15lbs ICs per 10 boards. I'm lookin forward to my AR experiments!

Speaking of AR, it segues nicely to another question:

#5. I have a 25lb bag of ammonium nitrate. 34-0-0, prilled, agro grade. Is this economically viable to produce nitric acid, and if so, how?

Feel free to post just a link, cause lord knows I've searched!


Mike

 

[n3vrs0br]

Ok. Steve, I followed Harold's washing guide to a tee(except for boiling the ammonia after the 2nd precip.)

Yield for 1lb of this particular type board = 11.55 grains clean, autumn-tan powder.

My issue is now:
The ammonia I have has a surfactant in it, causing MUCHO sudsing upon boiling, which in turn causes a fair amount of gold powder to become stuck to the side of the beaker, well above the waterline. This won't rinse off, so I've decided that this beaker will next be used to contain AuCl3 and I'll reclaim it that way. Fine. My question is this: Do I need to boil the NH3 for any period of time or will merely hot NH3 suffice?

Answered. Sorry!


Mike