Using nitric acid on pins - help!

[glorycloud]

I ran a little over a pound of pins of various types in some nitric acid.

I made the nitric from 1 cup of sodium nitrate in 1 cup of distilled water. I let that sit for over an hour and them added 1 quart of battery acid from the auto parts store and I let that sit over night. I poured the liquid over the pins into a crock pot that I let simmer on low for a couple of hours in a well ventilated area. Geez - BFRC for sure! :shock:

The solution got an interesting lighter blue color and a salt wanted to keep forming. I just kept stirring it until the salt disappeared and it appeared that the gold was gone off of the pins for the most part. I poured off the bluish solution with the gold flakes into a bucket. Rinsed the pins in the crock pot with water and poured off the solution into the bucket a second time. I rinsed probably four times until it appeared no more gold flakes were left (I decided to stop wasting my time chasing them around the crock pot!)

I filtered the bluish solution through coffee filters but it was a very slow process as a white to grey paste seemed to clog up the filters right away.
The filtered nitric solution has a light blue color and doesn't seem to have any of the white pasty / powder in it.

I guess I said ALL that to ask - what now?? The gold flakes are with the pasty substance in the filter. Any suggestions?? 8)

Thanks for the help!!

 

[Anonymous]

if there was solder on the pins or in the process you will have lead sulfate and or stannic acid(name could be wrong but you get the idea) from tin in the solder, or it could be silver sulfate if there was silver in the solder.

It is a real mess to seperate, I had to use AR with the impurities included drop gold and reprocess.

you have a tough job ahead, but someone else may come along that may be able to tell you a better way.

jim

 

[qst42know]

That's not the recipe for poormans nitric.

Was there solder on your pins?

 

[glorycloud]

I don't remember seeing solder on the pins. Most looked to be older bigger cylindrical connectors and a lot of pins that I cut off of boards. There weren't any headers with the boards still attached.

Any ideas about how to treat what is in the filter?

 

[Harold_V]

Any ideas about how to treat what is in the filter?

Incinerate the entire lot, heating to a high temperature (dull red if possible), but not hot enough to melt anything. I used to do that in a discarded stainless frying pan, heated on a gas hot plate. Once everything was hot, I'd use a rosebud torch to add additional heat.

Be sure to stir, so all of the contents get well exposed to air. Afterwards, screen, crushing any large pieces using a mortar and pestle, then boil the material in HCl. After a hard boil, fill the vessel with tap water and allow to settle. Siphon off when it has, then repeat until the rinse water is clear of color. You can then process with the solvent of choice (I used AR).

Incineration and a HCl boil will make a serious change in how things process. You may still have some material included that you don't want, but the resulting solution should filter well, so you can eliminate it before precipitation.

Harold

 

[glorycloud]

Harold,

I haven't incinerated anything yet but I can try. First times are always the "scariest".

Should I let the filter with the flakes and pasty powder dry first before incinerating or does it matter?

I am such a visual learner. It would be great if there was a simple how to incinerate video for the forum to refer beginners like me to. 8)

Thanks for all the help!!

 

[lazersteve]

I recorded an incineration video (bench sweeps), but I have not done all the final edits on it yet. My Gold Filled DVD demonstrates incineration on gold filled scrap also.

Steve

 

[glorycloud]

i saw that on your Pt / Pd DVD (which was great by the way!). You used your torch on the karat scrap.

should i use my camp propane stove with an old pan after the filter dries or should I force it drive in the pan?

THX!

 

[glorycloud]

hey - I received this response from my sodium nitrate vendor. What sayest thou, O faithful forum participants??

I would take the paste and the flakes and put them in a blender with a lot of distilled water.
If you cannot separate the stuff from the filter paper just put the whole filter in.
Blend it on max , stop and see if the pulp or lighter stuff floats to the top.

Then add a drop or 2 of dawn dishsoap and blend it some more.
Then let the gold dust settle and pour about 1/2 the liquid off.
Refill with distilled water,blend,settle,pour off and repeat until you are left with just soapy water and gold dust.

Rinse the gold into a gold pan to finish up.

If the pasty stuff does not want to dissolve in the soapy water then try HCL. That should dissolve the paste and clean the gold.

The blender trick is good for all typed of flake or foil gold.
It will grind the gold to dust and the gold will not float or stick to everything and is much easier to concentrate away from the other stuff.

 

[Harold_V]

There are no doubts in my mind----the blender trick would be worthless. You are dealing with gold that is so finely divided (thin, in this case) that it tends to defy the rules of gravity----much the same way flour gold does when a guy pans. It will mix and float along with the lighter substances, so you risk losing too much, and it's not necessary.

If your material comes from a nitric process, the combustibles will burn even when wet. That doesn't mean drying is a bad idea, but it's not necessary. I can't tell you the number of times I incinerated filters the moment they were empty of fluids. They are somewhat slower to get started, but burn perfectly well. I recall that the drier portions would burn rapidly, then stop when conditions were too wet. The forced heating removes the residual moisture quite rapidly, so it doesn't take long until the entire lot is dry and well heated. Still, if you are not in a hurry, it does no harm to allow the filter to dry naturally. I had a tendency to avoid that, because once dry of water, they give off a lot of fumes that are corrosive to everything in the room. Outside----no big deal. As an alternative, they can be force dried under the burners, in a fume hood, in the same pan that would be used for incineration.

Using your camping burner may not be in your best interest if you cherish the thing. Because you overheat the pan, the radiated heat tends to degrade everything in the near proximity. Valves on my burners had a somewhat limited lifespan, so I always kept spares on hand. Also, be wary of incinerating for prolonged periods when you have combustible substances under the hot plate . Even well covered surfaces get heavily charred, so you risk starting a fire (from experience). My (last) setup had a heavy asbestos board that supported the hot plate, which was spaced by a six inch (or slightly greater----I'm trusting to memory here) distance between the board and any wood beneath. That seemed to prevent risk.

Don't let this operation intimidate you. The only real risk, if you have addressed the fire hazard, is the risk of losing values to dusting. It is for that reason my fume hood had a filter. The amount of values recovered as a result was staggering, but do keep in mind, I refined on a daily basis, handling thousands of ounces of material.

Harold

 

[Anonymous]

I have experience the fluffy stuff with the gold mixed, it will not seperate by gravity as Harold stated.

The blender will just make more of a mess, period.

sorry,
Jim

 

[glorycloud]

Thanks - I appreciate the feedback everyone!!

 

[nicknitro]

Harold great advice as always,

If anything, I would of thought your vendor would have told you to use the soap to float the gold to the top for seperation, as many gold mines do with air and water. LOL

I suggest you ask him if this is dishwasher safe. LOL

GloryCloud, I would have to say the simplest way to avoid this in the future is to use a sulfuric acid cell to strip the gold from the pins, much like the ones on LazerSteve's website. It may require a little more attention, but is much less time consumeing in the long run. I'd save the nitric for cleaner materials like karat jewelry or close cut fingers.

I also ponder this question. In an effort to be even lazier,LOL, could one skip the incineration process, by boiling the filtered remnant with water and excess urea to remove the nitrates? Then skip on to an HCL wash or possibly a straight H20 wash then HCL? I am still deathly afraid of incineration, LOL.

Regards,
Nick

 

[glorycloud]

Yeah - I wish I had the copper mesh and the electrolytic cell. That would have made life a lot easier with these pins.

I apprecate the kind feedback!

 

[glorycloud]

You know, as strange as it may sound, the soapy water in the blender trick actually worked to get rid of the white pasty substance left over after using nitric on some pins! After about six or seven times of blending / pouring off / adding more water, all that was left was the gold dust and flakes in the bottom of the blender!

Just be careful as the gold dust wants to cling to the foam generated by the blending and the Dawn dish soap. If you just rap on the side of the blender real hard you will see the gold powder drop down to the bottom. I filtered off the rinse water and I did get some gold dust trapped in the filter. (I may not have been careful on the first few rinses and the dust was poured off with the foamy stuff.)

One day, I will get brave and incinerate my filters and I will keep all my notes and suggestions from Harold and the other kind folks!

But - the blender trick did work!!

 

[Harold_V]

But - the blender trick did work!!

I stand corrected!

Harold