How to estimate the amount of gold in electronics and jewelry

[jocelynholmes192]

This is really an informative post but the chemicals used are very dangerous and should not be performed without proper knowledge and equipment.

 

[cyberdan]

This is really an informative post but the chemicals used are very dangerous and should not be performed without proper knowledge and equipment.

Jocelyn, 95% of our member are well aware of that. Some have even written the book on chemical safety. That is why I do not recycle at that level (I live in an apartment) I am a middleman. I track down old electronics and sell to the melters. The worst toxic fumes I have to put up with are 500 cellphones sitting in my car on a hot day. :lol: (just imagine these phones old and someone talked and spit into the phone for years and then multiply that by 500 and multiply that by 100* heat. it was worse last month, I had 1500 phones)

 

[rawtuff]

Hi all,

i came in possession of high volume of card adapters (about 70k, total weight of metallic parts is around 21 kg ) , they are all the same brand and model, here is a pic:



I need to estimate the gold percentage in a unit in order to decide what to do with them.

I've tried XRF analysis in a dedicated lab which gave an unreasonably high result - 8% gold. I only later realized that XRF is probably not the best methodology for this kind of estimation since it probably only analyses the surface and not through the whole sample.
I then tried to melt several units for additional XRF testing, but the melted material doesn't look homogeneous enough - turned black on one side and yellow-red on the other with clearly visible strings of different melted metals.

Can anyone advise a better method to go with this? Maybe a different type of spectral analysis that is fit for plated material or something else?

Thanks!

 

[goldsilverpro]

Fire assay is the only way I would even think about doing it. I like fire assay mainly because all the final gold (which is pure) ends up as a solid that you could hold in your hand if you wanted to. In other words, it's real gold and not just a number. When you weigh this gold, you know absolutely that this weight is not too high. There are other gravimetric methods one could use but fire assay has been the accepted standard in the industry for centuries. A fire assay from a decent lab, preferably in triplicate, will probably cost at least $100.

XRF is worthless for the value of plated gold, with no exceptions. You would think a lab would understand this.

You could probably get a ball park idea of the value of the fingers (large plane areas at the top in the photo) by measuring them fairly accurately (I prefer digital calipers), and then calculating the area from the measurements, in square inches, that is covered with gold, and then doing a calculation. These are inserted many times during their lifespan, so I would guess the gold thickness would be about 30 millions of an inch (same as pins or circuit board fingers) and I have already put that as the 1st term in the equation below. Just plug in the number of square inches and the spot daily gold price into this equation and that will give you the $ value per unit. The .000030" is 30 millionths of an inch written as inches. The 10.18 is just a factor that is always the same. Actually, for math people, it's the number of troy ounces of gold in one cubic inch.

.000030" X 10.18 X number of square inches X gold spot price per troy ounce

I just measured the exposed gold on the card in my camera, which looks identical to your photo and came up with about 0.11 sq.in. The gold price at this moment is $1310

Therefore: .000030 X 10.18 X.11 X 1310 = $.043 or 4.3 cents per unit. Note: this is a guess, but an educated one (hopefully). Also note that this is the amount of gold you would probably get if you kept the cards as is, without grinding them up, and stripped the exposed gold off with some chemical.

If the pins at the bottom are precious metals (points? plating?), that could add to the value, but probably not much. Also, I didn't take into consideration the gold plating on the fingers that is covered with the plastic, since I didn't want to destroy my own card. I would break off all the plastic on the card on the left of the photo and measure all of the gold plating.

Another note: In general, especially when you're doing an evaluation for the buying of scrap, you can be a little on the low side but you never want to be on the high side. A low evaluation wouldn't hurt you unless you lost the deal. A high evaluation, though, could cost you a lot of money if you paid too much for it.

All in all, you would be best off with a fire assay.

 

[rawtuff]

Thank you, appreciate your advise!

 

[goldsilverpro]

Thank you, appreciate your advise!

You might re-read my post. I added some things.

 

[rawtuff]

You might re-read my post. I added some things.

Wow, thank you very much for the detailed info!

I've read the first page of this thread prior to posting my query and took note of the measurement method you used above, but was absolutely unsure about what thickness to assign to the plating of this particular material.

Now, these are branded adapters (sandisk) and old stock (circa 2007) and I was wondering about the thickness, but 30 micro inches is probably about right and I'll use that as a ballpark, but to be sure will have to look for fire assay company.

One interesting thing is the XRF testing came up with nearly the same percentage of Au for both sides of the fingers at the top - the contacting area and the flip side (double side plated). The pins at the bottom look plated as well, though probably thinner than the upper pins. The area covered with plastic has plating as well, if I'm going to extract the gold myself (which is starting to seem more and more probable, though it wasn't my intention initially) I wonder if I could burn out that plastic because manually removing it for every single unit will be quite tedious - i'ts pretty tight, like capsuled there.

P.S. I've found a local company which does fire assay and will contact them.

 

[aggemologist]

Dear folks, I am new in this forum. but really very nice information shared in this forum.

with regards

HUK

 

[ettran]

hi , what is the diferance from gold plated from gold filled. ed

 

[butcher]

https://en.wikipedia.org/wiki/Gold_plating

https://en.wikipedia.org/wiki/Gold-filled_jewelry

 

[Grelko]

The 10.18 is just a factor that is always the same. Actually, for math people, it's the number of troy ounces of gold in one cubic inch.

Is this accurate? I've seen 10.16 and 10.18 depending on where I look.

Edit - I've seen 10.17 and 10.13 also

 

[goldsilverpro]

Grelko,

If you look up the specific gravity in a variety of sources. you'll find a variety of different numbers. To get 10.18, I used 19.32 for the S.G. I also used 2.54³ as the number of cm³ in a in³ and 31.1 as the number of grams in a troy oz. Whatever, 10.18 is close enough. Considering significant figures, I probably should have rounded it off to 10.2 to be more correct.

 

[Grelko]

Grelko,

If you look up the specific gravity in a variety of sources. you'll find a variety of different numbers. To get 10.18, I used 19.32 for the S.G. I also used 2.54³ as the number of cm³ in a in³ and 31.1 as the number of grams in a troy oz. Whatever, 10.18 is close enough. Considering significant figures, I probably should have rounded it off to 10.2 to be more correct.

That works, thank you. I was wondering which math you used. I've seen the 19.32 as 19.3 etc.

So much easier than using 31.1034768. Doesn't really make that much of a difference unless you're in the 10s or 100s of pounds/kilos.

 

[ChemGeek]

Interesting thread but largerly theoretical one.
Much is said about assays etc to determine value of stock.
For small time guy it is of little relevance though.
Lets say I am buying motherboards or cell phone bords etc. In December last year I have sourced substantial quantity of very cheap motherboards ($0.3 each) and sold to scrap at ~$6/kg after a little cherrypicking (it seems that this particular scrap yard is not too mean about it, as long as it is done within reason - perhaps they have decided to suffer some nuisance in exchange of steady flow of slightly downgraded boards from different goldbugs. Then these are mixed with full value ones and resold as finest cut. Alternatively employees responsible of purchases are morons). So I have made a very nice fast buck.
However this low hanging fruit is gone and won't come back.
Now I have to buy over mail smaller lots (say 20kg or so), pay about 70-80% of scrap yard price, cherrypick a bit and resell the rest to scrap with hope that they wont downgrade and if so, then only a little bit.
Any assays of such small lots are plain waste of money as the assay would often cost more than purchased lot is worth. It is also impossible to run assay if you buy online/via mail (no, I do not buy on eBay due to an unreasonable pricing but there are other outlets as well).
Neither scrap yard runs any assays wile buying few hundred lbs lots.
So from where these assays stories are coming?
It seems that with e-scrap they may become relevant when refinery is buying few tons and more or if one is dealing with carat stock.
Now lets say, we have few tons of motherboards in a pile. How to take an representative sample out of such a mixed mess only gods of refining know and peoples who are actually doing it most likely don't.
So my question is:
Is there any smalltimer here dealing in e-scrap who usually relies on assays while buying 20-200kg lots or all what is done is a guesswork based on average content data, regardless, how inaccurate or contested these might be?

 

[niks neims]

Interesting thread but largerly theoretical one.
Much is said about assays etc to determine value of stock.
For small time guy it is of little relevance though.
Lets say I am buying motherboards or cell phone bords etc. In December last year I have sourced substantial quantity of very cheap motherboards ($0.3 each) and sold to scrap at ~$6/kg after a little cherrypicking (it seems that this particular scrap yard is not too mean about it, as long as it is done within reason - perhaps they have decided to suffer some nuisance in exchange of steady flow of slightly downgraded boards from different goldbugs. Then these are mixed with full value ones and resold as finest cut. Alternatively employees responsible of purchases are morons). So I have made a very nice fast buck.
However this low hanging fruit is gone and won't come back.
Now I have to buy over mail smaller lots (say 20kg or so), pay about 70-80% of scrap yard price, cherrypick a bit and resell the rest to scrap with hope that they wont downgrade and if so, then only a little bit.
Any assays of such small lots are plain waste of money as the assay would often cost more than purchased lot is worth. It is also impossible to run assay if you buy online/via mail (no, I do not buy on eBay due to an unreasonable pricing but there are other outlets as well).
Neither scrap yard runs any assays wile buying few hundred lbs lots.
So from where these assays stories are coming?
It seems that with e-scrap they may become relevant when refinery is buying few tons and more or if one is dealing with carat stock.
Now lets say, we have few tons of motherboards in a pile. How to take an representative sample out of such a mixed mess only gods of refining know and peoples who are actually doing it most likely don't.
So my question is:
Is there any smalltimer here dealing in e-scrap who usually relies on assays while buying 20-200kg lots or all what is done is a guesswork based on average content data, regardless, how inaccurate or contested these might be?

I've found companies in Germany offering analysis of boards for roughly about ~500 EUR (Au, Ag, Pd, Cu, per lot of ~1kg), largest cost being the "sample preparation fees" (read: milling, grinding).

I`d guess 99.99% of traders don't assay each small lot, just relying on somewhat universal categories of different boards (small socket motherboards, gold-edge RAM, etc.), that is why I'd say it is dishonest to remove anything (other than batteries and waste materials (plastic, Fe, Al)) from the board - that is not cherry-picking - if you remove IC or BGA or any other value bearing material and then sell the boards as "untouched" from the same category - that is cheating. You should not do that! Heck, I've heard horror stories from Russia about pre-leached boards being sold as untouched, that is very, very not cool...

 

[ChemGeek]

@nicks_neims,
These are sold as "used, conditions unknown, an odd part might be missing".
It is responsibilty of buyer to assess what it is worth under such circumstances, particularly that I sell face to face and not over a mail.
Scrap man probably purchases it with full consciousness, secured in knowledge that final Asian refiner (or Umicore) will foot the bill.
It is also a sad truth that "cheating", whatever it might be, became to be a standard operating procedure in Western culture in last decade or so.
Skilled lawyers have already worked out, how to rebrand "cheating" as "expressing your intentions in sophisticated, complex manner in increasingly challenging business environment".
Politics, business, interpersonal relations are all affected by it. Evidence of pending decay of white man culture.
No, I do not run Russian style fraud you have described.
By my standards it would be beyond what one can consider "reasonable".
Btw, another smalltimer whom I know have purchased one lot of BGA chips over internet auction. Came from France, I think. Tops of these BGA were peeling off in a different manner than other lots. Soon enough he have realized that worthless pieces of shaped black plastic were glued to base of chip with superglue.
Seller explained that he is only a trader and bought this lot from someone else on another auction and refused to reimburse my friend.
So buyers beware!
There are guys determined to cheat you out there.
And because it is sold as used, not working and with no specification of Au content, you can do absolutely nothing about it. Even negative reference on eBay is problematic.
I have also purchased few processors with pins leached of gold. Only tops were presented on photo
But the seller was otherwise so nice and helpful , that I have decided not to pursue it further. On other occassion he have sold me a good stuff.

 

[niks neims]

Btw, another smalltimer whom I know have purchased one lot of BGA chips over internet auction. Came from France, I think. Tops of these BGA were peeling off in a different manner than other lots. Soon enough he have realized that worthless pieces of shaped black plastic were glued to base of chip with superglue.

Oh that's a good one, have not heard of that before

Scrap man probably purchases it with full consciousness, secured in knowledge that final Asian refiner (or Umicore) will foot the bill.

They won`t, - final refiners pay out based on yield or assay - because of this. Also, this is one of the reasons (that e-scrap can be messed with) why pricing are so muddied... for better or for worse

you can do absolutely nothing about it.

Actually there is - you can make a decision to be honest for yourself . Or at-least stop trying to morally justify a scam.... after all we all live in the world we ourselves create and deserve

Full disclosure - I kind of feel where are you coming from - about 1-1.5 year ago that is exactly how I started - I bought up computer boards, removed fingers, BGAs and ICs and re-sold them to a larger "facecless" local scrap cooperation, processed chips & fingers myself and got a nice button, but after scratching the first of the gold fever itch I found that this can't be viable business model - mostly because it gave me no moral satisfaction at all... I made a decision to change direction - not to remove anything from the boards and rather focus my energy finding a partner that can recycle my honest material fairly to a mutual benefit...
That being said I do still purchase seperated BGA IC chips & gold-fingers from time to time - and this conversation got me thinking - obviously they don't grow on trees, if there are seperated BGA then there also are the original boards from which those chips have been peeled-of... and most likely in the end those particular significantly devalued boards will be used in some scam on someone unsuspecting... So basically it is perpetuating the same ethically dubious cycle...
In any case I`d suggest you stop selling devaluated boards to any partner you wish to have a long term relationship with, if not for ethical then for logical reasons

 

[ChemGeek]

@niks_neims,
Many members here are priding themselves with "depopulating boards partially and selling remains to bigger boys who can go and chase pins and MLCCs".
If your business model works now, it is very good but as you say, you are still participating in BGA purchases etc.
Somehow I feel no remorse in selling downgraded boards to *the faceless*, and anyway I am indicating that an odd part may be missing. It is job of their employees to assess what they buy but if these are judged base on monthly purchases in tons and competition is fierce... you know the rest.
Faceless is just that - faceless. Not more and not less.

I have seen *the faceless* selling in their stores copper pipes proudly labelled "1mm wall thickness", when actual thickness, as I have measured with caliper was 0.75mm. This between countless other frauds what *the faceless* perpetuate every day on most of us with no challenge and no punishment.
I have challenged manager about this practice and he have shrugged me off by saying that these are made by more modern technology and so they are as good as older 1 mm versions, so they are nominally 1mm thick and if I don't like it, I may not buy.
There is also a phrase in recycling comunity stating that "refiner is a final liar".
We have to know where we stand. As I have said - decay of white man's culture is alive and kicking.

Btw,
I understand, you are smalltimer as well so you won't have multitonnage lots necessary to deal with *the faceless* refiner.
Yet it is entirely unprofitable to process motherboards, if you neglect reclaiming Cu, Ag, Ta/Nb or small amounts of Pd and instead concentrate on Au only.
For small company reclaiming these values is too tedious and essentially a loss making proposal due to lack of benefits of economy of scale.
How do you get around of this problem?

 

[snoman701]

I`d guess 99.99% of traders don't assay each small lot, just relying on somewhat universal categories of different boards (small socket motherboards, gold-edge RAM, etc.), that is why I'd say it is dishonest to remove anything (other than batteries and waste materials (plastic, Fe, Al)) from the board - that is not cherry-picking - if you remove IC or BGA or any other value bearing material and then sell the boards as "untouched" from the same category - that is cheating. You should not do that! Heck, I've heard horror stories from Russia about pre-leached boards being sold as untouched, that is very, very not cool...

Find a better buyer.

My buyers have plainly stated...they have to put their hands on each board to sort it, make sure there is no battery, make sure there are no mercury relays, and so on...I can dip the whole board in a cyanide leach and give it to them, it's going to be obvious that the surface gold is gone. I can remove components, it's going to be obvious.

Simple fact of the matter is that if I can refine it and get 90-98% of the value instead of selling it and getting 50%, that's business...and my buyers respect that. In fact, they do the opposite...they sell stuff they pay scrap prices for as refurbished.

Now, some buyers will seriously downgrade material if it's been "molested". I've found that if your buyer uses the term "molested"...you best find another buyer...and just be up front with your buyer, you cherry pick your boards. There are plenty of buyers that can grade a board that has been selectively depopulated.

I will say...I'm not talking about taking N/S bridges off motherboards. In that case, you might as well just throw the rest of the board out.

 

[snoman701]

Somehow I feel no remorse in selling downgraded boards to *the faceless*, and anyway I am indicating that an odd part may be missing. It is job of their employees to assess what they buy but if these are judged base on monthly purchases in tons and competition is fierce... you know the rest.
Faceless is just that - faceless. Not more and not less.

Idk...I get your point, but I don't like the idea that these corporations are "faceless".

Most of them are relatively new, and built from the ground up. I'm a little guy and still communicate with the owner, or president, or whathaveyou.

If I can teach them, I try. If they are willing to teach me, I listen.