# Please help estimating Au content for these



## hestati86 (May 13, 2017)

Friends, though it's my first post here, I really need your help. I just discovered this board :roll: 

We are trading e-waste in South East Asia, and recently we are getting many unpopulated, production scrap (pics attached on the bottom). 

We need to offer our price for it, but it's tough for us to estimate the content. We're given the sample, but it's too small to do the actual test.

So, what I'm trying to do is get a very conservative estimation of Au content. Would you please quickly go through my estimations below? Do they make sense? Again, I can underpay for this material, so if I'm too conservative somewhere it's ok. I need to make sure I'm not too optimistic... Thanks!

Here's how I go about it:

1. *12* little rectangular boards per set, conservative assumption that each board is *10%* gold plated on both sides. Weight of each set is *122g*.

2. Each little board is* 6.4cm by 4.4cm*, therefore gold plated area is 6.4*4.4*0.1*2=*5.632cm^2* of gold plating per little board or 5.632*12=*67.58cm^2* of gold plating per set, including both sides.

3. Assume that this is class 00 (is it still the lowest?), so 20 micro inches thickness of the coating. In cm it gives me 0.0000508cm. Therefore volume is 67.58*0.0000508=*0.00343cm^3*. Since each cm^3 of gold is 19.3 grams, we have *0.0633* grams of gold per set.

4. Since each set is 122g and 1 ton is 1000000 grams, I have 1000000/122=8196 sets per ton. Therefore I have 8196*0.0633=*519g* of gold per ton of this material. To add a safety factor of 0.8, I get roughly *400 grams per ton.*


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## anachronism (May 14, 2017)

Double check the gold itself and make sure that they are not engineering samples or production failures with a dusting of gold instead of the normal layer.


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## hestati86 (May 14, 2017)

Thanks! these are in fact production failures OR terminated product. I doubt it is engineering sample, they have 2 tons of these. What do you mean by dusting? Any picture? To me, it looks ok layer of gold, definitely thin though. How thin would that dusting be?

Apart from this, do you agree that approx 10% is covered by gold on both sides?

Also, I'm wondering if there's software or maybe Photoshop plugin, where I load and it can tell me % of the color. Would be nice, anything with yellow is highlighted and % of the area is given.

Thanks again!


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## anachronism (May 14, 2017)

If they are production failures then you cannot assume the gold content can be calculated using the normal formula for gold thickness/surface area. That dusting literally can be dusting. GSP will probably be able to expand on this in a more coherent manner than me. I've run some of these and had very little return. 

Not all are the same of course, I am just sharing my own experiences with these but I wouldn't pay more than a few hundred per tonne unless you are 100% convinced these have the full plating amount. 

I hope that helps 

Jon


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## hestati86 (May 14, 2017)

It does help. I will try to do the lab test, even though I probably don't have enough. But to be honest, it looks like normal plating, not dust, but again I need to make sure.


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## kernels (May 14, 2017)

Your estimation for plating thickness may be off by a factor of 10. Those pads are meant to be soldered to, so they will be ENIG plating. That can be as low as 2 to 5 micro inch thickness. 

You can use some dilute Nitric acid to see the difference between ENIG and hard gold plating pretty easily. A drop of 35% nitric acid on hard gold plating just sits there and does nothing. ENIG is basically porous, so when looking through a microscope you will see a clear reaction happening as the Nitric acid attacks the Nickel and Copper 'through' the ENIG plating.


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## justinhcase (May 14, 2017)

One of the main reasons such boards are rejected after an inspection is nonuniformity of plating.
Even if you take test samples you will find it hard to make a dent on a ton of material. so as to get a representative sample.
I would class it more as a copper recovery, then have a fire assay.
Take five to ten kilo's one board at a time, from equal point within the lot, Ash Smelt for copper.
Then test what you have.
That would give you a rough idea of content.
The bigger your random sampling the better idea you will have.


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## hestati86 (May 14, 2017)

kernels said:


> Your estimation for plating thickness may be off by a factor of 10. Those pads are meant to be soldered to, so they will be ENIG plating. That can be as low as 2 to 5 micro inch thickness.
> 
> You can use some dilute Nitric acid to see the difference between ENIG and hard gold plating pretty easily. A drop of 35% nitric acid on hard gold plating just sits there and does nothing. ENIG is basically porous, so when looking through a microscope you will see a clear reaction happening as the Nitric acid attacks the Nickel and Copper 'through' the ENIG plating.



Thanks! I didn't think about it. Though when I place it in acid, the flakes of gold are quite large, so this is definitely not dusting, but at the same time, I suppose that even 2 micro in can be in a form of flake, so yes... we will have to think what price to offer, maybe copper price... Thanks!

Edited... I made a mistake. It can be ENIG, it's not dusting.


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## anachronism (May 17, 2017)

Ash smelting for copper is a complete waste of time an effort. Don't waste your time doing it. Stupid advice.


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## justinhcase (May 17, 2017)

anachronism said:


> Ash smelting for copper is a complete waste of time an effort. Don't waste your time doing it. Stupid advice.


Rather Rude and inflammatory.
Pretty much underlines why I decided to walk away politely once I understood you better and reaffirms every day what a good decision that actually was.
Also, underlines our differing methodology.
I can not afford to gamble so test everything, metals, relationships, business models.
That is how I come to conclusions.
You do very well judging everything by eye, good on you. your clients do not ask questions why should I waste my time doing so.
Anyone can put out a silly lowball price and know they will always be in profit.
It takes a slightly differing proclivity to take an agreed upon fee in a transparent manner.
Or to accurately value a 1000 kilogram lot with only a 5-10 kilo test cross-section.


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## anachronism (May 17, 2017)

It's still a waste of time.


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## 4metals (May 17, 2017)

Ashing and smelting the copper is usually done on a larger scale than your sample and to do the smelting work just to assay the copper for PM's is not the approach I would use, still it is not stupid, but it wouldn't be my choice for a sample. 

I would granulate the entire lot, take multiple samples from a well mixed pile of granulated boards, and digest the metals in Aqua regia. Multiple samples, a few ounces each tops. The granulating will expose any gold hidden in layers to the acid if you granulate to 1/8 to 1/4" size and multiple analyses will give you a range of concentrations. From that you figure what you are willing to pay for this material. If these boards are not high end boards, the aqua regia will need to be run on an AA to detect gold in the PPM range in the acid. 

If the gold concentration warrants, and the lot is large enough, and you want to refine yourself, then ashing and a copper cell becomes an option if you take in the entire load. But remember, you pay on out-turn unless you properly sample the entire bulk batch that comes in.


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## justinhcase (May 18, 2017)

I would love a granulator that could chew through a ton of boards at a time.
That would give you a very well mixed sample.
Sadly I have to gas off and ash before they will mill down.
Would not copper be the main cash cow followed by nickel and Au thus get the best return from a copper processor who pays out on trace impurities?
4Metals method would be the most effective way to estimate a content, but as the operational word is "Estimated" or in other words an approximate calculation or judgment of the value, number, quantity, or extent of something, that leaves the possibilities wide open.
There was no indication of how accurate an estimate was required so even judging by eye and weighing it in your hand would technically fall within the borders of this post.
Personally, I try to base my purchases on as concrete a set of numbers as I can. estimates especially other peoples tend to be affected by personal predispositions.
This is why such methodology have been eradicated from informed inquiry for several centuries.


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## 4metals (May 18, 2017)

With copper as the main cash cow, you need a large operation and efficient handling. and as much as it sounds like a wonderful concept to talk about transparency, often what comes in the door as a sample and what comes in the door as the job, differ. So transparency is a 2 way street. 

It is better to get a good sample, multiple assays, and set your estimate on the lower end of your results. But the reason turn around time is so long in refining of boards is they have to wait for the lot to be homogeneous and sampled. That means burned or pyrolyzed, and smelted into bars that can be accurately assayed before payment.

It is a huge mistake to promise a firm payment amount based on a sample you didn't take which you do not leave yourself room for variation. There are plenty of guys who were once in the refining business that tried that business model.


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## hestati86 (May 18, 2017)

Guys, you are forgetting. I am in Asia...

I normally have about 5 hours to offer the price. That's right. Material comes in at 10am, by 4pm already gone, Chinese buyers offer a price and take it.

This time was an exception, they gave us 2 weeks because they want to start doing business with us. But they warned us, best case scenario we will have 1 day.

This material sold for 7 USD per kilo. I do not know how, I do not know why. Chinese came and offered this price.


I honestly have no idea how they do it. I know for sure that we can offer better price than Chinese, but at the same time since I dont know the content, I dont know how much to offer. Somehow Chinese seem to know...


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## g_axelsson (May 18, 2017)

hestati86 said:


> Guys, you are forgetting. I am in Asia...


It would be easier to remember if you added your location in your profile, now we only see USA as country of origin.

Göran


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## hestati86 (May 18, 2017)

g_axelsson said:


> hestati86 said:
> 
> 
> > Guys, you are forgetting. I am in Asia...
> ...



Good point. But my point was that nowadays Chinese anywhere in the world will not allow you to sample, choose, select and bla bla bla. Mee to I'd love to run lab analysis on it, but suppliers just ignore buyers like that. Buyers from China come with bag of cash and pay. And they must be profitable too, because they keep on coming back...


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## 4metals (May 18, 2017)

Let me get this straight, normally you will get to look at the boards, do some math or look up some history (which you don't have) and within 5 hours give them a price. 

Well Jon, (Anachronism) said;


> I've run some of these and had very little return.



And the Chinese guy's are paying $7,000 per ton but your surface area calculation says it has 400 grams per ton. So your calculation says there is $15,000 worth of gold and you built in a 20% safety factor. 

So the Chinese buyers are doing what most do and giving themselves plenty of room. The seller is the loser here and he needs to be educated. 

But if you are a middle man and not putting this material into a sample-able form before shipping, you will be subject to the same screwing the Chinese are giving the seller. 

Profitable refiners sample and assay before bidding. Some can develop histories which allow them to bid based on the content and their experience. But they give themselves room. Without this experience or the facilities to do the sampling and assays, you are in a position to take a leap of faith. So it's either jump in or go home.


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## justinhcase (May 18, 2017)

hestati86 said:


> Guys, you are forgetting. I am in Asia...
> 
> I normally have about 5 hours to offer the price. That's right. Material comes in at 10am, by 4pm already gone, Chinese buyers offer a price and take it.
> 
> ...


 It was much the same as when I use to run a navigation course on Dartmoor.
Most chaps would be impatient and want to run off in the first direction that came to their mind.
Notably, fewer would sit and think for an hour or two before quietly setting off straight line for their target.
The first set would also eat all their chocolate on the first night and run out of energy by mid week.
If someone is impatient and insists on a gut valuation good for you, you have no choice but to value it at the bottom end.
You then take your time and you are going to at least be in profit maybe even make a killing if the wind is good.
But you should also offer the better route rather than use manipulative or cajoling methods to get them to accept such an offer.


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## hestati86 (May 18, 2017)

4metals said:


> Let me get this straight, normally you will get to look at the boards, do some math or look up some history (which you don't have) and within 5 hours give them a price.
> 
> Well Jon, (Anachronism) said;
> 
> ...




Sorry, I don't understand. Yes, my surface calc based on 20 micro inch layer gives me 400 grams, but if this is in fact 2 micro inch? Then we are talking 40 grams, right?

Unless they have a way to measure how thick the layer is, are they just gambling? But they seem to be coming back, means they're making profit.

BTW, seller has really no idea. He bought it for say USD 2 and wants to sell for more, that's it.


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## 4metals (May 18, 2017)

So the seller is a middle man too? So you will just add another layer of middleman or are you the refiner? 

I didn't check your math on the plating value, I was using your number.

Considering your time constraints, the ENIG is a very thin layer of gold and will not resist being "burned" through by nitric acid. Add a drop of nitric acid cut 50% with water to the board to see if the gold (or the electroless nickel under the gold) reacts. If it does, immersion gold is only a very thin layer and the boards are of considerably less value.


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## hestati86 (May 18, 2017)

4metals said:


> So the seller is a middle man too? So you will just add another layer of middleman or are you the refiner?
> 
> I didn't check your math on the plating value, I was using your number.
> 
> Considering your time constraints, the ENIG is a very thin layer of gold and will not resist being "burned" through by nitric acid. Add a drop of nitric acid cut 50% with water to the board to see if the gold (or the electroless nickel under the gold) reacts. If it does, immersion gold is only a very thin layer and the boards are of considerably less value.



This!

Thank you so much! 

So if it doesn't react, is there any "minimum guaranteed" layer thickness? From what level it will not react?

For the middle man... We have a contract with Aurubis, my seller gets the waste as a part of a total waste management contract he has with many companies. So no, there are no extra re sellers in between


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## 4metals (May 18, 2017)

ENIG General Applications The minimum immersion gold thickness shall be 0.05 µm [2.0 µin] at -4 sigma (standard deviation) from the process mean as measured on a pad size of 1.5 mm x 1.5 mm [0.060 in x 0.060 in] or equivalent area; the typical range is 0.075 µm to 0.125 µm [2.96 µin to 4.93 µin].


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## anachronism (May 18, 2017)

This is how we often have to trade too. Offering a fast price so being safe is the name of the game. That product hasn't in my experience even got multiple layers of copper within it but that's not to say it's all the same. 

Incidentally using a pencil eraser on the gold is also a good way to determine ultra thin flash plating. I've got some of that product so when I get back I'll use an eraser on it and show the difference.


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## hestati86 (May 18, 2017)

Eraser will take off ENIG?


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## anachronism (May 18, 2017)

It can cut through thin flash plating. Try on a normal piece of ewaste plate like a finger, then on this material and see if there is a difference.


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## 4metals (May 18, 2017)

An eraser is a much user friendly test for sure, Jon, would you have any pictures to give an example?


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## goldsilverpro (May 18, 2017)

I have done the pink pencil eraser thing probably a 1000 times. It's probably been 25 years since I've done it but, at the time, I was pretty good at distinguishing between thick, thin, or in-between plating and also whether it was solid or plated. I wound imagine that it would take very few strokes (say, 2) to remove 3-5 u" of immersion gold (IG), which by nature would have to be quite soft. Use moderate pressure and don't use a coarse ink eraser. The soft pink erasers on a good quality pencil, like a Ticonderoga, is what I always used. For fingers, I'm thinking it took 10-15 strokes. It's very subjective unless you've done it a jillion times.

A story. In L.A. in the 80's, there were lots of guys in parking lots selling gold chains and other jewelry that they claimed to have come from looting during the Newark riots. We were approached by a guy with a heavy chain. The markings said 14K and the price was about 1/3 of spot for solid 14K. I happened to have a pencil with me and asked the guy if I could use the eraser on the gold. I told him that, if the gold was solid, it wouldn't damage the chain. He said OK. After 2 strokes, a 1/2" streak of white nickel was exposed. Super thin color gold plated.

All of these estimate things are interesting but, if I were thinking about buying a ton of this stuff, I would want a true, well-sampled, group of fire assay analyses. I assume these "sets" are all the same. If so, sampling would be simpler. My gut feeling is, however, that this is very lo-grade crap and the gold thickness is nowhere near 20 u".


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## hestati86 (May 19, 2017)

Thank you for eraser test suggestions.

I am out to buy an eraser, but this "low grade crap" cannot be scratched off easily. I tried with a key and it take s a lot of effort to scratch through gold.

Getting my nitric and eraser. So nitric should be 50% concentration and just make a drop?


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## kernels (May 19, 2017)

I'm a believer in the 50% (of 70%) Nitric too, but I find it helps to look at the reaction through a microscope. With ENIG you can see the little bubbles form 'through' the gold very quickly. On hard gold plating there is no reaction.


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## kurtak (May 19, 2017)

hestati86 said:


> I honestly have no idea how they do it. I know for sure that we can offer better price than Chinese, but at the same time since I dont know the content, I dont know how much to offer. Somehow Chinese seem to know...



Per the underlined - just wondering what makes you so "sure" that you can offer a better price then the China buyers ?

I ask because there are a couple things to consider here (with China buyers) 

One is that China is a HUGE source of counterfeit products - so it is entirely possible that a China buyer could/would buy production failure (gold plating does not meet spec) boards for counterfeit product production - in which case they would not be concerned about gold recovery & therefor able to offer "a bit" more then gold recovery price - or in other words "buy blind" when it comes to gold recovery - because gold recovery is not the end intent - but rather re-use in (counterfeit) product production 

Also - is the China buyer "the smelter/refiner" --- if so - then (1) they can offer more then a middle man buyer as the middle man is cut out - and (2) as the smelter/refiner (&/or even a LARGE volume middle buyer) - they have run enough LARGE LOT material through their operation (they have seen it ALL) that they already have a recovery data record & all they have to do is look at their data speed sheet on any given product (as mentioned by Jon & 4metals) to make there buy price offer --- its hard to compete with such buyers - unless you also have handled LARGE volumes of material & have a good data reference for buy pricing

Bottom line - you are playing in a VERY competitive market - especially if you are working in a market of sellers - selling to multiple "bidding" buyers (even is its a one day/one bid opportunity) --- in which case the best you can do is know your material - make your best offer on any given lot - & know you are going to win some & loose some - &/or even let some go if/when its material you don't know

Kurt


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## 4metals (May 19, 2017)

> So nitric should be 50% concentration and just make a drop?



Nitric usually comes 68 to 70% (at least here in the states) and by 50% I mean half of the volume is distilled water and half of the volume is nitric acid, so it is not truly 50% but it is not critical either. But do not use the concentrated acid as the water helps get the reaction going.


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## hestati86 (May 19, 2017)

kurtak said:


> hestati86 said:
> 
> 
> > I honestly have no idea how they do it. I know for sure that we can offer better price than Chinese, but at the same time since I dont know the content, I dont know how much to offer. Somehow Chinese seem to know...
> ...




Counterfeit is out of question.

China now cannot offer good prices UNLESS they go for reusing of chips. Actually, China is ACTIVELY moving their refineries outside of the country. They have an issue with bringing e-waste to the country, it's simply not allowed. Now, of course it's still possible, mainly through HK, but it makes things a lot more expensive (pay the customs, pay the middle man in HK, pay for storage and so on). Their process is far from perfect, they lose way too much. The ONLY reason they still can compete is the chip recovery, but we are also working on it now, to get the chips off, sell to China and send material to Europe. 

To finish it up, our labor cost is cheaper than China, so we can sort here and then send to Europe. Bottom line, head to head they have no chance.

Actually, here we win any bidding war for populated boards, unless we hit the "chip recovery" territory. In that case, the price will shoot up like crazy and goes way over metal value. The unpopulated board is different though, I'm yet to meet ANYONE who has ANY rough idea how much value is in it.

It is funny actually how I met one buyer from China today, we discussed this board and he said he would not offer more than $1.5, which is half of what we offered and even with that price we didn't get it.

Hey it's Asia after all. There was a guy selling good boards but at almost 20 USD per kg, while the actual price is maybe 10. 3 months later, he still has these boards in his warehouse, even Chinese didn't buy it for chip recovery. He is just waiting for the next sucker in line and you see MANY cases like that here.


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## 4metals (May 19, 2017)

And you're a middleman and willing to jump into that mess?

Do you, or does someone from your company, witness the sampling at Arubis? If you could set yourself up to work as an agent of the generator of these scrap parts, and sell yourself as a service to witness and assure the sampling of the material at Arubis is fair and transparent and you get paid a percentage of the value. That way you have little risk and the generator will maximize their payout for the scrap because they will be paid on assay (since Arubis pays on sampling and assay)
so their payment would be the actual value, less refining charges (which are reasonable), less your percentage for your service. 

Are you hiring?  

By the way, 


> To finish it up, our labor cost is cheaper than China, so we can sort here and then send to Europe.


Where are you located?


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## g_axelsson (May 20, 2017)

I almost got a feeling that someone have read this thread...

A video about different plating in nitric acid, viewed through a microscope.
[youtube]http://www.youtube.com/watch?v=iav_KH0PEZY[/youtube]

Successful Engineer, if you read this thread, thanks for the video.

Göran


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## hestati86 (May 20, 2017)

4metals said:


> And you're a middleman and willing to jump into that mess?
> 
> Do you, or does someone from your company, witness the sampling at Arubis? If you could set yourself up to work as an agent of the generator of these scrap parts, and sell yourself as a service to witness and assure the sampling of the material at Arubis is fair and transparent and you get paid a percentage of the value. That way you have little risk and the generator will maximize their payout for the scrap because they will be paid on assay (since Arubis pays on sampling and assay)
> so their payment would be the actual value, less refining charges (which are reasonable), less your percentage for your service.
> ...



A bit off topic here. I lived in US and Canada and had the same thinking and mentality when I first got here, to SEA. No offense, it's good, just not applicable here.

Chinese and Asians in general (except Japanese and MAYBE Koreans) do not think long term. $10 today is more important than potential $10,000,000 tomorrow. How are those total waste tenders are obtained? Money under the table. How do we export when it's not allowed? Money under the table. The person in charge wants to get $10 from you TODAY, because maybe tomorrow he's fired, he will never get his share from you.

I mean it sounds like a total mess, but it's not when you know people. I was even invited to few "meetings" that went something like that (very politely)

- sir, do you know that we have Mr. Loh from Department of Industry as a partner. We would ask you not to participate in this and spoil our market
- Yes, but my partner is a good friend of Mr. Mahdi, city council deputy and vice-mayor so please kindly f-off
- oh, sorry sir, please kindly continue your business


Back on topic, thanks for the video on nitric acid!!!


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