Keeping fingers crossed for this deal (pictures)

So a while back I revealed to my co-worker that I was into processing and refining precious metals. He was very fascinated with the science. He eventually told me that his father actually works for a company that constructs components that use many gold plated parts and that the company would throw away parts that were excess or obsolete So his father and his boss would take the items and sell them to someone (legally). I asked how they all determined how much to pay for the material. My co-worker told me that the guy would take small samples and have them assayed. I was a bit thrown off by this as plated material is kind of tough to assay accurately in small quantities. At least in my opinion. So I told my co-worker that his father and boss were basically riding blind and could be getting ripped off royally.

After a bunch of harassment and lecturing my co-worker finally convinced his father to give me a try. I think this finally happened because his father and boss were becoming more and more skeptical of the returns. They can actually calculate the gold content as this is true mil-spec material. The particular sample I received were center pin conductors used in satellites! The sample contained 107.3 grams of these pins. They are solid copper with what I believe to be 24k gold plating inside and out. You will see why I think this.

I was pleased the pins were non-magnetic because I knew my options were wide open on processing them. I didn't go with the obvious H2S04 cell as it was such a small sample and I wanted to get a more precise yield. I decided to go with nitric. After a quick and I mean quick incineration I threw them in a beaker with a 50/50 70% nitric/water solution. The solution got very hot and did nothing! I had to decant the acid and incinerate again. I had to really damage the outer layer to get to the copper underneath. Even after the second incineration I was only able to digest about half the pins. I got a bit impatient so after the nitric was used up I decanted and went straight to AR so sorry there are no pictures of all the foils after complete digestion.

After following standard operating procedure I gave the necessary washes and melted. The final yield for 107.3 grams of pins was .6 grams! Very impressive. The scale was actually teetering between .6 and .7 and after all done I realized I had missed about 15 pins in my pocket that were never processed. So I'm calling it .7 grams. Now I just have to compare numbers with my co-workers father. Hopefully we can strike up a deal 8)




Incoming weight












Here you can see the foils starting to float as the pins come to total digestion with nitric.




After first precipitation.








After first wash




Dried

The sulfuric stripper may not have worked very well, anyway. Most all electrolytic systems don't "throw" current well into inside areas. The same with electroplating solutions. In order to meet the gold thickness spec on the inside, they probably had to overplate the outside areas. The acid had problems penetrating the thicker outside gold and, therefore, the attack likely started on the inside and worked its way outward. Had you agitated the parts often, in order to force fresh acid solution into the inside, and, had you run the nitric longer, near boiling, they probably would have completely finished.

GSP,

I think I may have been unclear when I talked about the incomplete digestion. It wasn't due to the acid not reaching the insides of the pins but insufficient incineration (both of them). After the first incineration I did indeed get the nitric up to boiling with no affect. After the second I suppose I damaged the shells of about half of them and they completely dissolved leaving only the shells behind. I do understand what you mean about agitation as it would break the air pockets that prevent acid from reaching the insides but these pins lend themselves very well to acid reaching the inside of them. They actually have a hole on the end as well as one on the side. And of course the tulip like opening on the front and sides.

With this being said do you think a stripper cell would still be insufficient even though the acid can easily make its way to the inside of the pins? It would be very expensive using nitric considering the possible volumes I would be processing and cyanide is not an option. What might be another alternative? I've tried thio before with no success.

so if you get a big batch you will need a ball mill or some way to scratch each part before digesting.

2" k-lock nuts would work well or something with a sharp edge

http://www.americanfastener.com/nuts/

necromancer said:

so if you get a big batch you will need a ball mill or some way to scratch each part before digesting.

2" k-lock nuts would work well or something with a sharp edge

http://www.americanfastener.com/nuts/

Click to expand...

That's an idea and I could definitely think of many other ways to damage the pins but my main concern is the process that will be used recover the gold. Nitric would get expensive rather quickly as my co-worker is talking about drums full of parts. Not only that but it would seem a waste to digest these type of parts being that they are solid copper. They would be in sellable form if something like a stripper cell was used and can add to profits.

smelting ? or is there not a way to electrolytically remove copper only ?

GSP has made some great posts & i think 4metals also

if smelting is not good for you a home made electrolytic process may be in order, i have no experience with this maybe the pros will weigh in.

if its 100% gold plated copper could it not be cut up / milled, put through the electrolytic process, leaving the plated gold behind ??

An electrolytic process would probably be even more wasteful than the nitric. Remember, you have to keep making the electrolyte which means acid. And now you have to monitor the electrolyte. Then there is the fuel cost for melting and longer turn around time. I could see for a greater quantity of gold like karated but then an electrolytic process wouldn't be needed anyhow. And again the copper would then be in unsellable form. A cyanide procedure is a no brainer but there's no way I can get ahold of it. I'm hoping that someone will weigh in on the stripper cell given the new parameters but if I have to go the nitric route then so be it.

If you have volumes that make nitric (as cheap as it is) not a reality. What about a copper cell? you could melt and plate out the Cu and leave the gold in the bag.

Eric

etack said:

If you have volumes that make nitric (as cheap as it is) not a reality. What about a copper cell? you could melt and plate out the Cu and leave the gold in the bag.

Eric

Click to expand...

Eric,

Where do you obtain this "cheap" nitric The best deal I can find for a home refiner that will actually ship it to you is here.
http://www.sierrachemicalcompany.co...rd=nitric+acid&option=com_virtuemart&Itemid=2
This is with a $400 dollar drum deposit. And of course minus the shipping and applicable hazmat fees. If you have a better source please let us know.

Where are you located? If you're in the US, there is surely a Univar (or other large industrial chemical supplier) fairly close that that will sell drum quantites for $3 to $4 per gallon (plus about a $900 drum deposit which you get back when you return it). A gallon of nitric will dissolve 2 pounds of copper. You can use 300 series stainless steel containers for the dissolving. Your main problems will be fume control and waste disposal.

Any electrolytic system, such as the sulfuric stripper, will probably not "throw" current well into that tiny hole, if at all. If you applied 10 amps, you might get 1/100 amps applied inside the hole. It may take hours or days (or never) to strip the inside. The current flux applied is never distributed evenly on any part and it follows the paths of least resistance. The hole is physically blocked by the pin body itself and thus is the point of highest resistance to the current flux.

Melting into bars and then using a copper cell is a "dream" way to do it. The copper base is likely not pure copper and any alloying metals will cause big problems when attempting to plate out the copper in a solid form onto the cathode. Sounds good on paper but very difficult to accomplish. You could block cathode deposition with a large cathodic sheet membrane but you would end up with a lot of waste solution that you would have to deal with.

If I had this material, there's only one way I would do it, with no exceptions. I would use sodium cyanide/30% hydrogen peroxide in a small cement mixer. Essentially no fumes. A 55 gallon drum of pins could be easily run by 1 person in an 8 hr day. You could have all the gold the next day, in pure bar form. Also, you would still have the copper in solid form.

To me, you have only 2 good possibilities: #1 cyanide stripping or #2 nitric dissolving.

http://greenwayproductsinc.com/ Depending on where you are, you can pick up for about $3 per gallon.

etack said:

If you have volumes that make nitric (as cheap as it is) not a reality. What about a copper cell? you could melt and plate out the Cu and leave the gold in the bag.

Eric

Click to expand...

this is was what i meant, (thanks Eric)

My thought, my opinion, would be to use the base side of stripping, and selectively remove the Gold. It may be these pins, " and they look like it " are plated to 125 micro meters of plating. the ones i am use to, fully gold, are 75 micro meters plated, and net .4 to avg. .48 to .5 percent by weight. a good recovery value, for even 1 kilo gram. Ten Kg. might get you 45 Grams plus of pure gold.

that being said, i have run into dis-continuity of plating thickness, which give errors, of .015 percent by weight of each sample, , " varying thickness of samples "

One error i come across quite often, in valuing samples, is the over estimates, given to providers of material to be refined. My recent trip to California, a seller of chips was promised 125 per pound, and on 100 lbs provided. LOST over 5 ,000 , that he was promised on returns. So be careful in over talking recover values. i spent a day, and revalued various types of materials, and it was the inconsistencies overlooked by the refiner, that the error was attributable to.

So you may want to review a business model of .025 percent by weight recovered, with bearing the costs of refining, or splitting the refining costs 50 / 50 .. Be prepared, is what i am saying, to have a working relationship that contractually works. i have been doing contracts and settlements for some time,

We are in a Gold price decline mode. and it may continue, so overvaluation, will do us all no good. Fair and equatable, is contract language, along with security and timely payments. i wish you good luck with this. " but i think your doing a lot of costly over work " my opinion. Cheers.

GOLDbuyerCA said:

My thought, my opinion, would be to use the base side of stripping, and selectively remove the Gold. It may be these pins, " and they look like it " are plated to 125 micro meters of plating. the ones i am use to, fully gold, are 75 micro meters plated, and net .4 to avg. .48 to .5 percent by weight. a good recovery value, for even 1 kilo gram. Ten Kg. might get you 45 Grams plus of pure gold.

that being said, i have run into dis-continuity of plating thickness, which give errors, of .015 percent by weight of each sample, , " varying thickness of samples "

One error i come across quite often, in valuing samples, is the over estimates, given to providers of material to be refined. My recent trip to California, a seller of chips was promised 125 per pound, and on 100 lbs provided. LOST over 5 ,000 , that he was promised on returns. So be careful in over talking recover values. i spent a day, and revalued various types of materials, and it was the inconsistencies overlooked by the refiner, that the error was attributable to.

So you may want to review a business model of .025 percent by weight recovered, with bearing the costs of refining, or splitting the refining costs 50 / 50 .. Be prepared, is what i am saying, to have a working relationship that contractually works. i have been doing contracts and settlements for some time,

We are in a Gold price decline mode. and it may continue, so overvaluation, will do us all no good. Fair and equatable, is contract language, along with security and timely payments. i wish you good luck with this. " but i think your doing a lot of costly over work " my opinion. Cheers.

Click to expand...

Are you sure you got those micrometers right? If the plating is 125 micrometers thick, it takes surface or about 4cm2 for 1 gram. That would then take only few pins for 1 gram of gold.

Are you sure you got those micrometers right? If the plating is 125 micrometers thick, it takes surface or about 4cm2 for 1 gram. That would then take only few pins for 1 gram of gold.

this discussion so far, is percent by weight. explain your calculation, how a few pins are 4cm2 " four square centimeters? 16 sq. centimeters?

the diameter is very small, place out your pins side by side, and work out your surface area, and be careful in sq. centimeters, gold recovery at 125 micrometers. i don't see that NO. on my charts. Cheers.
Let us work from ambiguity to measurable facts. quick reasoning by some one else's tables, may cause overvaluation.
You can plate a lot of pins with one gram. fifty or more 2 Cm. pins tiny diameter, at heavy plating, to more than a hundred, by diameter on medium plate, " find that in the books if you can "

there is some selective reasoning going on with pin recovery. " by many of us "

Rough estimate according to photos: pins look about 1cm long and about 2mm diameter. That would make around 0.3 cm2 each pin only of outside plating. and with plating 0.125mm (125micrometer) ... 0.3 x 0.0125 = 0.00375 cm3
0.05 cm3 of gold is just under 1 gram... 0.05 / 0.00375 = 13.3
So according to your thickness and my math it would take around 13 pins for 1 gram of gold of outside plating only.

GoldbuyerCA,

shmandi is right on.

A micro meter, micrometer, or micron (all the same thing), is one millionth of a meter.
125 micrometers = .0125cm
1cm2 at that thickness = .0125cm3 of gold
Therefore, .0125 X 19.32 = .2415g/cm2
Therefore, 1cm2 = US$10.10. This would be US$65.16 per in2
ABSURD NUMBERS!!!

I doubt if it is even possible to deposit gold at that thickness from an hard acid gold bath without the deposit becoming corrupted, extremely stressed, brittle, and probably cracked.

What did you really mean to say? 1.25 micrometers? That would be 50 microinches, which is much, much more realistic. Or, did you mean 125 microinches?

What did you mean when you said, "use the base side of stripping?" Cyanide?

i had pulled data from my records on gold plating on Satellite parts. which looking again is 125 micro inches " i have made error before on this forum as i work in Metric, and this Forum is generally in English units. i can converse in both, but in my haste / zeal, i erred. and from checking what Chris GOLD Silver Pro,, wrote back in 2011, i can not find a mil. spec to that value in micro inches.

the values used are :> What does the term Mil-Spec mean?

I just searched for "mil-spec gold" on eBay and got 44 hits. This is one of my pet peeves so, please excuse my long rant. The term Mil-Spec, for gold plating, is often tossed around, erroneously, to indicate that the parts are of very high quality, as far as the gold thickness is concerned. That is absolutely not true. I'm not saying you're guilty of this, refinitman. I am curious, though, why you used the term and what you mean by it.

It was put into place, originally by the Defense Dept., I believe, to standardize the plating call-out for particular parts as far as thickness, purity, and hardness of the gold plating is concerned (also, it includes such things as what metal and how much of it will be applied under the gold - say, .000050" of nickel). For example, if the designer, whether military or commercial, decides that only .000020" (20 microinches) of gold is required, he will call out the thickness as Class 00 (see below). Mil-spec call-outs are used industry wide, both for military and commercial parts. It's just a way to make sure the parts are plated the way the designer wants them to be plated - that's all it means, period. Although many military components are plated thicker, for higher reliability, the term mil-spec doesn't mean these parts were made for the military, and it certainly doesn't mean that the gold is extra thick.

Mil-G-45204C Specifications
Type I: 99.7% gold minimum (Grades A, B, or C).
Type II: 99.0% gold minimum (Grades B, C, or D)
Type III: 99.9% gold minimum (Grade A only).

Grade A: 90 Knoop maximum.
Grade B: 91-129 Knoop.
Grade C: 130-200 Knoop.
Grade D: 201 Knoop and over.

Class 00: .00002" minimum thickness
Class 0: .00003" minimum thickness
Class 1: .00005" minimum thickness
Class 2: .00010" minimum thickness
Class 3: .00020" minimum thickness
Class 4: .00030" minimum thickness
Class 5: .00050" minimum thickness
Class 6: .00150" minimum thickness

Actually, I believe that the Mil-G-45204C Specs are officially out of date, although they are still widely used in industry. I think the spec that is now officially used is ASTM B488 which, incidentally, starts its list at .000010" (10 microinches). Also, I believe that other thicknesses can be spelled out, other than those on the list, and it would still be considered mil-spec if the Type and Grade were spelled out as by the spec. For example, you could call out Type II, Grade C, .000005" (or .000025", or whatever) - still mil-spec.

To summarize. The mil-specs concerning gold plating are simply an organized way for the manufacturer (or the military) to communicate to the plater, in a concise manner, the characteristics and thickness of gold they want applied to their parts - nothing more, nothing less.

Besides gold, there are ASTM and Mil specs for all types of plating, anodizing, etc. http://goldrefiningforum.com/~goldrefi/phpBB3/viewtopic.php?f=34&t=10882#p105945

.............................................................................................

with above set as reference. Class 2 100 micro Inches, would seem the plating.

..............................................................................................

Yes i would use Cyanide on these Pins, after a degreasing wash.

..............................................................................................
with my conversion error, it makes "Rough estimate " look like accuracy, which we all should strive to be better than rough estimate.

measuring the actual product, using the correct plating thicknesses, and using some accurate, plating area calculations, , the latter, i find suspect, on your calculations, do them again.

...........................................................................................

we are held to accuracy by our actions, as we are results orientated, and practitioners of precious metal recovery.

GOLDbuyerCA said:

So you may want to review a business model of .025 percent by weight recovered, with bearing the costs of refining, or splitting the refining costs 50 / 50 .. Be prepared, is what i am saying, to have a working relationship that contractually works. i have been doing contracts and settlements for some time,

Click to expand...

No offense intended but I sometimes have problems following you. Are you saying that those pins only ran .025%? That's $4.72/lb. He said he got .6 to .7g of gold from 107.3g. Calling it .65g, that would be 0.61% or $115/pound, at a $1296 gold spot.

goldenchild,

I didn't realize fully how those pins were made. I thought that small hole ran all the way through. If it stops where the side hole is, you might be able to use the sulfuric stripper. I'm thinking that, maybe, one purpose of the side hole was to allow solution exchange and to allow current to be applied to the inside during the gold plating. Many types of parts are designed so as to make them more plateable. I would try the sulfuric stripper on a few pins. After stripping, rinse them well and put them in nitric to dissolve the copper. If there are no gold flakes after dissolving the copper, the sulfuric stripper worked.

In production, you could run much larger quantities with greater efficiency using a commercial plastic plating barrel (tumbler) rather than with a rinky-dink mesh basket. You would have a better chance of getting all of the inside gold with a tumbler.