# Chip value estimation



## pinwheel (Jun 20, 2011)

Can anyone estimate the value per pound in these chips? They appear to have lead copper wires and a small square gold plated (over copper) chip inside.


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## Anonymous (Jun 20, 2011)

These are almost worthless,as are most "plastic packaged" chips.I have broken plastic chips in almost every package ever available,and have found very few with any gold to speak of.......ceramic is a different story.Goldsilverpro has some good stories about his days with ceramics.


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## Claudie (Jun 20, 2011)

I think they have gold wires inside but I believe you need a microscope to see them. The subject of which chips have gold and which do not is somewhat confusing here I think. Some members say they have no gold, others say they do. I am sure that some of them do, but some may not. I suppose this should be a project for someone to find out about PM content and end the confusion. I think the best way to process them might be to incinerate them, then crush them, separate the magnetic parts out, then maybe go with AP. Suggestions?


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## pinwheel (Jun 20, 2011)

They are certainly not worthless, nor are these plastic. I have real quotes in hand so by these I can tell for sure there is gold in them. I did a nitric test and ate the gold off the copper chip etc. Its gold for sure.


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## patnor1011 (Jun 20, 2011)

pinwheel said:


> I did a nitric test and ate the gold off the copper chip etc. Its gold for sure.



I dont understand this. I would think that nitric will dissolve copper and leave gold no?


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## pinwheel (Jun 20, 2011)

well it was just a gold test kit.


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## Anonymous (Jun 20, 2011)

pinwheel said:


> They are certainly not worthless, nor are these plastic. I have real quotes in hand so by these I can tell for sure there is gold in them. I did a nitric test and ate the gold off the copper chip etc. Its gold for sure.


First off,I did not say worthless! I said "almost" worthless,and I was referring to the gold content in each chip.Given the fact that you asked for the value on a per pound basis,
Secondly, there are primarily 2 types of substrate......ceramic,and what we call plastic.Those ARE NOT ceramic.
Thirdly,if you have quotes in hand,then what is the purpose of this thread?
Fourthly,and most important, if you ate the gold off with nitric,you may want to sell them to the highest offer as soon as you can.
And finally,by contradicting an answer to a question that you yourself asked,you are likely to put a bad taste in peoples mouth about trying to help you.
You asked a question.....I answered.Others have answered since and I promise more members will answer after this.I would suggest you read all of the answers and form your own oppinion based on all of the answers given.


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## pinwheel (Jun 20, 2011)

If you look at it on a single chip basis, then yes, they are not worth much. But I happen to have a lot of them so it adds up quickly. In any case, all I am really after is to see if anyone has processed these. I want to make sure my quotes are not way off by an order of magnitude.


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## jimdoc (Jun 20, 2011)

Maybe you should share your quotes?

Jim


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## samuel-a (Jun 20, 2011)

I ball park the black IC's at <0.001% , gold wise.

The package material is not composed from ceramics as mic mentioned. calling it plastic might not be very accurate term as well (though much more relevant term).
The molding materail composed mainly from a resin of sort (organic material of course) that act as binder and fused silica powder cured togather with high heat.

There are other element (either organic or non) added to the molding material to effect the physical behavior of the package. This info is not really shared in full by manufacturers though.

Edit:
If you have a very large amount and relatively homogenous, you'd be better off pay to assay them before selling them.


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## patnor1011 (Jun 20, 2011)

I would not put any estimate on mixed IC. There is more types of them than you have types of shoes. If you need to have estimate to set price on them and you have quantity of the same product at hand you have to do test/sample batch. Otherwise you will be guessing like Samuel is. 
Estimate of 0.01g of gold in 1 kilogram of IC? I don't know....


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## samuel-a (Jun 20, 2011)

patnor1011 said:


> Otherwise you will be guessing like Samuel is.



Hi Pat
This is not a guess actually. 



patnor1011 said:


> Estimate of 0.01g of gold in 1 kilogram of IC? I don't know....



I wrote <0.001%, meaning one thenth of a percent and even less.



patnor1011 said:


> There is more types of them than you have types of shoes.



Exactly the reason why i said it's my ball park, rather then stating exact numbers.
And that he probably be better assay them if he have big homogenous amounts.


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## patnor1011 (Jun 20, 2011)

samuel-a said:


> I wrote <0.001%, meaning one thenth of a percent and even less.



0.1 is one tenth of 1
0.01 is one hundredth of 1
0.001 is one thousandth of 1


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## samuel-a (Jun 20, 2011)

http://www.google.com/search?q=one+...gc.r_pw.&fp=e2cdbf82a93ada0c&biw=1280&bih=709


But, i guess we understand each other :mrgreen: 

Just in case some one didn't, what i meant to say my ball park numbers are: per 1000 grams of chips, there's less or equal to 1 gram of gold.


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## Anonymous (Jun 20, 2011)

samuel-a said:


> what i meant to say my ball park numbers are: per 1000 grams of chips, there's less or equal to 1 gram of gold.


I can see that as being a relatively accurate estimate.


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## pinwheel (Jun 20, 2011)

OK so if I have 700 pounds of these at 1g per 1000g then I should expect a net result of over 10 ounces of Au which certainly warrants a trip to the assayer. This also makes my existing quotes way too low.


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## Anonymous (Jun 20, 2011)

That would be over 26 ounces,and yes.....IF you had 700 pounds of them,then yes it would be worth taking them to an assayer,like Samuel suggested.


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## pinwheel (Jun 20, 2011)

26 ounces? I estimated 10.2 oz based on his estimate of 1gram per 1000g. Is my math funny?


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## trashmaster (Jun 20, 2011)

I also would like to know how you came up with 26oz ????? 

I came up with the same number 10.2 ????????????????


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## Claudie (Jun 20, 2011)

I did it twice & came up with 11.2 both times. :|


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## pinwheel (Jun 20, 2011)

I think the confusion is converting troy ounces, but starting out with regular pounds and grams and not troy pounds. I am not sure if I am doing this right.

700 pounds x 453.44g = 317,408g / 1000 = 317.40g net weight. 317.40 / 31.1 = 10.2 oz troy.

Or more simply put: 700 lb = 10208.333 oz(troy) divided by 1000


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## Claudie (Jun 20, 2011)

I took 700 pounds X 16 Ounces per pound = 11,200. Then took 11,200 ounces X 28.39 grams per ounce for a total of 317,968 grams. Then I divided that by 1000 for a total of 317.968, then I divided that by 28.39 grams per ounce for a total of 11.2 ounces. :|

Edit: You're right, if I divide by troy ounces it comes to 10.2


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## Anonymous (Jun 20, 2011)

Nope you guys are right.I was doing ounces to pounds,not grams to ounces......don't forget it is still monday.
So yes if someone had 700 pounds of these,and they yielded 1 gram of AU per kilo,then it would yield 10.2 ounces TR.


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## Militoy (Jun 20, 2011)

OK - so if 10.2 ozT per 700 lb was a good estimate - that would make them worth around $22.46 / lb for gold alone, at today's spot. I've crushed a bunch of this kind of chip package up, trying to get an idea of PM value. I would guess the value to be considerably less than this - but I haven't actually processed any of them - so it's just a gut feeling I get picking the gold bond wire out of the rubble using a microscope. Remember that the copper in the mix makes up a good proportion of the weight - copper has a density 13% greater than iron.



samuel-a said:


> I ball park the black IC's at <0.001% , gold wise.
> 
> The package material is not composed from ceramics as mic mentioned. calling it plastic might not be very accurate term as well (though much more relevant term).
> The molding materail composed mainly from a resin of sort (organic material of course) that act as binder and fused silica powder cured togather with high heat.
> ...



I would say your description is a very accurate one for - plastic. Most structural plastics, or ones that have to withstand thermal cycling - as a chip does - are reinforced with ceramic binders such as tabular alumina or some form of silica, as cab-o-sil, microspheres, glass fiber, etc.

With so many pounds of the material - your advice to assay is a sound one. Otherwise, at any price he sells at, he'll forever wonder if he ripped himself off. With that kind of volume, it's likely that there's more coming from the same supply stream. An assay may very well pay for itself in the first batch sold.


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## goldsilverpro (Jun 21, 2011)

> I ball park the black IC's at <0.001% , gold wise.



Not to beat a dead horse but, to eliminate confusion, 0.1% = 0.001, as Pat said, whereas 0.001% = 0.00001. Therefore, at .001%, they would only contain 454 x .00001 = .0045 g of Au/pound = $0.22/pound, based on a $1545 market. At the actual 0.1%, the value is $22/pound



> what i meant to say my ball park numbers are: per 1000 grams of chips, there's less or equal to 1 gram of gold.



That would be 1 part per thousand = 0.1% or, expressed as a decimal, 0.001. To convert the decimal to a percent, you always move the decimal point 2 places to the right (or, multiply by 100). To convert percent to a decimal, move it 2 places to the left (or, divide by 100).




To make math easier, I would highly recommend memorizing as many relevant conversion factors as possible or, keep a list handy and keep adding to it. Of course, this must be done with understanding. Personally, I hate those online plug-in type calculators and rarely use them unless the math is extremely involved and I don't want to take the time to figure it out. Why? Because I don't learn anything by using them. Also, on some of them, it's easy to get a wrong answer if you don't know exactly what values to plug in where. When I grind out the math, I can truly visualize what is really happening. Also, I often try to find at least one other way to do the math to double check my answers, as in the 2 examples immediately below. Also, think about your answer. I've learned that, if the answer doesn't sound right, it usually isn't right. Remember that there are many different ways to approach each problem and still get the same correct answer. Probably, the more correct ways you can think of, the better you understand what you are doing. On this problem alone, we, as a group, have come up with about half a dozen good, workable methods.

One of the convenient conversions I've always remembered is that an avoirdupois pound (a standard US pound) contains 14.583 troy oz. Therefore, 700# @ 0.1% = 700 x 14.583 x .001 = 10.2 tr oz.

Another conversion permanently implanted in my mind is that a 2000 avoirdupois pound ton contains 29,166 tr oz. Therefore, for 700# @ 0.1%, (700/2000) x 29166 x .001 = 10.2 tr oz. 

Forgive me, this is off the track of the thread but, the reason I've memorized this last conversion is that, when assaying such things as ores or low grade pulps, a sample size of 29.166 g is commonly used to make the final calculations easier. This weight is called an "assay ton (AT)". When using a 1 assay ton sample weight of 29.166 grams, the final result, in milligrams, is equal to the number of troy oz of gold (or, whatever) per 2000 avoirdupois pound ton of material. For example, with a 29.166 g sample, a final gold weight of 0.003 g is equal to 3 tr oz/ton. I had a set of AT weights that ranged from .05 AT to 1 AT - the smaller weights were used for richer materials. The sample weighings were made on a special small 2 pan swing balance called a "pulp balance." With AT weights and a pulp balance, the weighings went very fast. Probably less than a sample per minute. Probably faster than a modern digital scale, unless you could program it to directly weigh in assay tons.

When you need to know the answer in tr oz/metric ton, the same logic can be used but, in this case, an assay ton sample would weigh about 32.15 grams.



pinwheel said:


> 700 pounds x 453.44g = 317,408g / 1000 = 317.40g net weight. 317.40 / 31.1 = 10.2 oz troy.
> 
> Or more simply put: 700 lb = 10208.333 oz(troy) divided by 1000



Correct answer on both counts. The first method is excellent and very logical. Of course, instead of dividing by 1000, you could have multiplied by .001, the decimal equivalent of 0.1%. Same thing.

I don't think the 2nd example is simpler to the reader, since you didn't explain where you got the 10208.333 and the way you wrote it could be confusing. I know what you're saying, but others may not. To make more mathematical sense, you could have said something like: 700 lb = 10208.333 oz(troy); 10208.33 divided by 1000 = 10.2 tr oz., based on a 0.1% yield.



I hope everyone will excuse me for the long boring math posts. I must admit that, when I see math being done, especially when there are errors made, it draws me like a moth to a flame and I start blathering (as my wife adroitly calls it). To prevent making costly errors in this complex PM field, it is imperative that everyone can somehow do the math (or use the correct internet calculators correctly). I really do try to make the math I present as simple and logical as possible, although I often fail in this. If I say anything that confuses anyone, let me know and I'll try to simplify it. I also can make mistakes, so please correct me when I'm wrong.


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## pinwheel (Jun 21, 2011)

Thanks for that last paragraph. The assay office is going to give me back a reading in milligrams and I was wondering how to reverse engineer that into something usable for larger weights.


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## goldsilverpro (Jun 21, 2011)

pinwheel said:


> Thanks for that last paragraph. The assay office is going to give me back a reading in milligrams and I was wondering how to reverse engineer that into something usable for larger weights.


If you're talking about my direct response to what you wrote, please note that I changed that paragraph a bit.

And that is x number of milligrams per WHAT - per ton (if per ton, what kind of ton?), per pound, per gram, per unit, per WHAT? You must know per WHAT.


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## escrap (Jun 21, 2011)

Me too Claudie..lol


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## samuel-a (Jun 21, 2011)

Thanks Chris.
When you put it that way i see where i was wrong.




patnor1011 said:


> samuel-a said:
> 
> 
> > I wrote <0.001%, meaning one thenth of a percent and even less.
> ...



I stand corrected Sir.


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## dtectr (Jun 21, 2011)

Claudie said:


> I think they have gold wires inside but I believe you need a microscope to see them. The subject of which chips have gold and which do not is somewhat confusing here I think. Some members say they have no gold, others say they do. I am sure that some of them do, but some may not. I suppose this should be a project for someone to find out about PM content and end the confusion. I think the best way to process them might be to incinerate them, then crush them, separate the magnetic parts out, then maybe go with AP. Suggestions?


 FWIW 
Lets not confuse the types of chips we're discussing - the only ones I remember that we have established PM content on are these http://goldrefiningforum.com/phpBB3/viewtopic.php?f=34&t=4383 which are a 2-part BGA (Ball Grid Array) with foils (the geometric patterns) in the green fiberglass part and gold bonding wire imbedded in the thermoset plastic top. See my photo in the thread.

Those are not what pinwheel is displaying - his is upside down, BTW - the usual package looks like this, in situ 
- I'm a little dubious of the gram per kilo yield, or are we already past that? I had to go take a picture.


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## Anonymous (Jun 21, 2011)

I will be running some BGA's with a new contest soon.Then we can all see a current yield record.Of course it won't be extremely accurate because of the different manufacturers.But I'll show a pic and weight to begin with and go from there.
P.S. Detectr can you grab me some peter pan peanut butter from that ad paper?Thanks I'll paypal you the $. :mrgreen:


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## Claudie (Jun 21, 2011)

_About 90 percent of today’s chips are still packaged via wire bonding using gold wiring. The projections are all over the map, but gold is quickly losing its luster, as some believe that about 70 percent of all devices packaged via wire bonding will use copper instead of gold by 2013 or so. _



http://www.eetimes.com/electronics-news/4207542/Copper-turns-to-gold-in-IC-packaging-


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## patnor1011 (Jun 21, 2011)

samuel-a said:


> Thanks Chris.
> When you put it that way i see where i was wrong.
> 
> 
> ...




The only thing which was confusing is that you used % symbol where I marked it red. That confused me, and gave different meaning to numbers. 8)


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## dtectr (Jun 21, 2011)

"[la-la-la!] Shop Hy-Veeeee - where - there's - a -- *Helpful smile* in evr'y aisle!"

It'll be waiting for you at the bus station !!! :lol: :lol: :lol: But truly *choosy* moms choose *Jif*!

I'll be interested in your processing - I've run the bottoms thru a shredder, burnt (I can't honestly call it incineration - I used a reducing rather than oxidizing atmosphere, before I knew better. I was worried about the neighbors getting PO'd) then to Poor Man's AR. The excessive carbon crap made filtration a mess.

I've had good luck with them (green bottoms) in AP, though.


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## goldsilverpro (Jun 21, 2011)

Since the assaying of these parts was mentioned a few times, I would like to put my 2 cents worth in. 

Please note that, in this discussion, I am assuming that the parts are all the same. By this, I am talking about the package and not necessarily the chip contained in the package. In general, for most ICs, whatever value is there is mostly in the package and bonding wires and not the chip. The part number is determined by the chip. Therefore, you could have different part numbers but, if the package is the same, the values in each part should be in the same ball park. If there is a mix of different packages, it is a different story and a much more involved sampling method is needed than the one I am suggesting.

There's a lot of talk about assaying on the forum but little about sampling. Assaying is easy but sampling is difficult. No matter how accurately you perform the assay, if the sampling is done poorly, the results are next to worthless. The assay only tells you what is in the sample. 

If the parts are the same, I would strongly advise not grinding them up before sampling, unless your assay involves recovering all the PMs from the *entire* amount that you ground up. Once ground, the material tends to segregate (especially stuff like those tiny wires) and the sampling becomes more inaccurate. If you do grind and run fire assays, you will need to split the ground material down with a sample splitter and then run a whole bunch of duplicate assays, especially when you have 700# of material.

The easiest and, probably, most accurate way on identical parts (at least, in appearance), such as these, is to fire assay the whole parts separately. To sample them, since they all appear to be identical, I would probably just grab a part here and a part there - I can't see how splitting down the lot by coning and quartering or using a sample splitter would give much improvement. In this case, you can probably run 2 parts per fire assay but, if the total copper and nickel is more than about 2 grams, you may only be able to run 1 part per assay. Since organics are involved, the parts must be incinerated before fluxing. This is easily done by weighing the 2 parts and placing them in an empty assay crucible. Then put them in a hot (say, 1850F) assay furnace, with the door opened just a crack to let in a little oxygen, and burn them until they fall apart into white ash. This might take 45-60 minutes. or more. Occasionally, you might have to pull the crucible out and give it a stir with a small diameter steel rod. If they aren't burned completely and any carbon remains, you'll probably end up with a too large lead button. After incineration, pre-mix the flux in a separate crucible, pour it onto the ash, stir it all up, and run a normal fire assay.

A big question is how many samples should you assay to get reliable results? For 700#, using the methods above and assuming the parts are all the same in appearance and size, I would probably start with at least 6 samples, which may be adequate. This is only a guess. The 6 assay results can be simply entered into the standard deviation part of the statistical mode on most any $20 scientific calculator. From this, you can compute the probabilities of the correct answer being between a certain range of values. If this isn't good enough for you, you need to run additional samples for better accuracy. Actually, from the results of the 6 samples, you can compute approximately how many samples you need to get a desired reliability. Please note that, no matter how you sample or how many samples you run, you'll *NEVER* know exactly what you have unless you refine the entire 700#. With samples, all you can do is get close. The more samples you run, the closer you'll be 

There are many other ways to sample this lot. Probably the best way is to incinerate the entire 700#, then ball mill it, screen it, melt the metallics and drill the bars, and sample the ash with either a sample splitter or a grain sampler.

Then, of course, you have to deal with the refiner. He could care less what your assay results are or how you got them. The refiner is usually your biggest stumbling block to getting what you should get.

And you thought the assaying process was easy. What I have outlined is a simple case. Ores are probably the worst, since they are the most heterogeneous. In any case, you can't just grab 1 sample and assay it with any expectation of reliability whatsoever. Even with karat golds, you need to run at least 2 samples taken intelligently and most pros prefer 3. Refining is probably as much art as it is science, but sampling is almost pure science and it's not very intuitive. Correct sampling and assaying is where the money is made. It puts you a step above the person you're dealing with. Whether buying or selling, he who knows the true value of the material best, most always wins - old GSP proverb.

Chris


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## glondor (Jun 21, 2011)

That information on sampling from GSP Is worth more than all the gold in the 700 pounds of chips. Thanks for putting that out there GSP.


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## arthur kierski (Jun 21, 2011)

i do a lot of these types of chips-----never obtained less then 1gram per kilo and most of the time also silver. some of these black chips that i refined have more then 5grams of gold per kilo;
i might get in conflict with some members of the forum but i do not wish to disclose from what type of scrap comes these high yeald black chips
regards
Arthur


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## Oz (Jun 21, 2011)

arthur kierski said:


> I might get in conflict with some members of the forum but I do not wish to disclose from what type of scrap comes these high yield black chips


It is perfectly understandable and acceptable in my opinion that you wish to keep a unique high yield scrap source private. Often I am in the same position as it is a clients material I have processed. They consider the scrap source and yields proprietary trade secrets. 

Thank you for sharing your minimum and maximum yields from this type of scrap.


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## arthur kierski (Jun 21, 2011)

thanks Oz, for understanding my position.
just wanted to say that the yeald is 1 or more grams per kilo
Arthur


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## goldsilverpro (Jun 21, 2011)

Glondor said:


> That information on sampling from GSP Is worth more than all the gold in the 700 pounds of chips. Thanks for putting that out there GSP.


Thanks a lot for the compliment. It's always gratifying to know I haven't wasted my time.


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## pinwheel (Jun 22, 2011)

To be clear, there are 700 pounds and every chip is identical.


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## samuel-a (Jun 22, 2011)

Chris.

It amaze me time and again, how you (and the other "veterans") seems to have the bigger picture in mind and are willing to share your point of view with such detail. For that i pesonally would like to thank you.



goldsilverpro said:


> The easiest and, probably, most accurate way on identical parts (at least, in appearance), such as these, is to fire assay the whole parts separately. To sample them, since they all appear to be identical, I would probably just grab a part here and a part there - I can't see how splitting down the lot by coning and quartering or using a sample splitter would give much improvement. In this case, you can probably run 2 parts per fire assay but, if the total copper and nickel is more than about 2 grams, you may only be able to run 1 part per assay. Since organics are involved, the parts must be incinerated before fluxing. This is easily done by weighing the 2 parts and placing them in an empty assay crucible. Then put them in a hot (say, 1850F) assay furnace, with the door opened just a crack to let in a little oxygen, and burn them until they fall apart into white ash. This might take 45-60 minutes. or more. Occasionally, you might have to pull the crucible out and give it a stir with a small diameter steel rod. If they aren't burned completely and any carbon remains, you'll probably end up with a too large lead button. After incineration, pre-mix the flux in a separate crucible, pour it onto the ash, stir it all up, and run a normal fire assay.



What flux composition will be needed for such material?
According to spec sheets, about 60-70% of package matrix is composed of fused silica with the rest being mostly epoxy of some sort (which wouldn't matter since incinerated)


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## goldsilverpro (Jun 22, 2011)

samuel-a said:


> Chris.
> 
> It amaze me time and again, how you (and the other "veterans") seems to have the bigger picture in mind and are willing to share your point of view with such detail. For that i pesonally would like to thank you.
> 
> ...




That's a lot more silica than I expected, but since silica is usually used in assay fluxes, it may not cause a problem unless there is so much that it won't allow the epoxy to burn out. If the silica melts in the 1850F heat and coats the epoxy and prevents it from burning out, you might try incinerating at a much lower temperature - say, 1000F, for a longer period of time. It might also help to crush up the part in a cast iron mortar and pestle before incinerating. This won't work, though, if any of the gold sticks to the cast iron. It probably won't.

You might have to experiment with the flux mixture but, to start with, here's what I would try for these parts.

60-70 g litharge
30 g anhydrous borax or borax glass
20-30 g anhydrous soda ash
Sugar or flour
A little fluorspar (try 2-5 grams) if the molten flux is too thick. If you use too much, the crucible can be severely attacked and you can leak flux onto the furnace floor.

Except for the sugar or flour, the amounts of the ingredients are not that super critical and can vary somewhat.

Bismuth trioxide can be used instead of litharge and is much safer (and more expensive). I haven't used it so I can't comment on it. If you use litharge, make sure you have excellent furnace exhaust. You don't want to breathe that crap.

The purpose of the sugar or flour (I use sugar) is to reduce part of the litharge (lead oxide) to lead metal, which is formed in droplets wherever a sugar particle contacts a litharge particle and these rain down through the mixture to collect the PMs. The remaining unreduced litharge acts as an important part of the flux. The sugar or flour is burned to carbon and that's what reduces the lead. Ideally, about a 25 gram lead button is formed. For the brand of granulated sugar I was using, that took about a level 1/2 teaspoon. Since sugar and flour can vary tremendously, you'll have to experiment with the amount. In general, it takes less flour than sugar. If the epoxy doesn't burn out completely, a lot more lead can be reduced and you may need no sugar or flour at all. If way too much lead is formed, you can either use a huge cupel or split 1 part into 2 pieces and run it in 2 crucibles.

If you're interested in both Au and Ag: cupel the lead button, weigh the Au/Ag bead, wrap the bead in lead foil along with enough silver to give about a 4-6/1 silver/gold ratio, cupel, part, weigh the gold, calculate the silver from the 2 weighings. If you're only interested in the gold: add the silver to the flux mixture, cupel the lead button, part, weigh the gold.

Were I doing this, I would probably run a few experimental assays before settling on the method I would use. The high silica could cause problems and change the whole approach. I sold my assay equipment so I have no way to play with it. Good luck!


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## Harold_V (Jun 23, 2011)

Keeping in mind I have never assayed, my experience in processing waste materials taught me that silica is not melted (about 3,300° F required to melt silica), but dissolved by soda ash. If there's an excessive amount of silica present, more soda ash should handle it in stride. I can't address the issue of the epoxy, but I certainly would recommend full incineration before any attempt at melting. A slag cover may preclude full incineration, otherwise. 

I certainly agree with the comments about fluorspar. It does an amazing job of thinning slag--and is, indeed, very aggressive in dissolving things, including furnace lining. 

Harold


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## goldsilverpro (Jun 23, 2011)

Harold_V said:


> Keeping in mind I have never assayed, my experience in processing waste materials taught me that silica is not melted (about 3,300° F required to melt silica), but dissolved by soda ash. If there's an excessive amount of silica present, more soda ash should handle it in stride. I can't address the issue of the epoxy, but I certainly would recommend full incineration before any attempt at melting. A slag cover may preclude full incineration, otherwise.
> 
> I certainly agree with the comments about fluorspar. It does an amazing job of thinning slag--and is, indeed, very aggressive in dissolving things, including furnace lining.
> 
> Harold



You're right, of course, about the melting point. I don't know what I was thinking.


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## samuel-a (Jun 23, 2011)

Thank you Chris for that detailed answer.
Looks like a promising point to start with. At the moment i don't have assaying equipment and my knowladge about fluxes and smelting is somwhere at 2 out of 10, but was very interested to know how one would fire assay them IC's.
I'm saving this post for when the time comes and it will be relevant.



Harold_V said:


> silica is not melted (about 3,300° F required to melt silica), but dissolved by soda ash.



Thaks Harold for pointing this out, i had a hunch this might be the case. I guess it's good you point that out for those that know about smelting even less then i do.

With this amount of soda ash melted, i assume the clay/fused silica dish will probably be a disposable one, right?
What would you use in case smelting large volumes is part of the process rather then assaying in small disposable crucibles?


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## Anonymous (Jun 23, 2011)

Silicon Carbide would work well.
This is a good place http://www.budgetcastingsupply.com/Crucibles.php
They also have a 5 pack of carbon stirring rods (12" long x 1/2 "thick) for $30,which is an excellent deal.
Their prices include shipping,and they have an option where you can be emailed for every step of the shipping/delivery process.
I have always had my stuff delivered quickly,and packaged well.
The A10 silicon carbide crucible is a very good deal at $55.70,and should be large enough to handle most "backyard" refiners.


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## Harold_V (Jun 24, 2011)

mic said:


> Silicon Carbide would work well.


You did pay attention to my mention that soda ash dissolves silica, yes?

Food for thought:

When I melted my (cement) silver, I used flux. Using a #8 silicon carbide crucible, I could get about eight heats from each one before it was thinned beyond reasonable use, and often sprung a leak at the flux line. Fluxing in a crucible is a recipe for very short lifespan. 

When I processed my waste materials, I knew they were high in silica, but I still added silica sand to each lot. The results I achieved in my tilting furnace were outstanding. I was fortunate to land on a flux recipe (my own) that served the purpose perfectly well. An assay of the flux revealed a content too low to justify further processing, so I was elated. 

That being said, I did my melting directly in the furnace, no crucible. In spite of using a 94% alumina lining, erosion was severe. Were it not for the extremely high value of the material in question, it would have been a mistake to process the material because of wear and tear on the furnace. I shudder to think of the cost of the crucibles I'd have destroyed instead. 

Harold


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## samuel-a (Jun 24, 2011)

Harold.
From your words, i understand that the higher the alumina content the more resistant it will be to the carbonate erosion, am i correct with that thinking?

I do have a pure alumina crucible.
Thing is, dou to it's cost i shutter from thinking it might become a one timer...


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## Anonymous (Jun 24, 2011)

mic said:


> Silicon Carbide would work well.





Harold_V said:


> You did pay attention to my mention that soda ash dissolves silica, yes?


Actually I did pay close attention....I just didn't make the connection between silica and silicon carbide.I'm not sure why it didn't register in my head,I should have known that.
Do you think graphite would work better?If so that would be better for me,because of the price.I have some magnesium oxide,I also have fireclay.Maybe lining the insides of the crucible would help?
Please advise,because this is something I will be starting as soon as next week(weather permitting).


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## macfixer01 (Jun 25, 2011)

In general I don't find anything in these PLCC type chip packages. However make sure you crack open any of them made by Rockwell. I have found several different part numbers (usually on modems or communications boards) that have a hybrid design with a ceramic wafer inside that has gold traces. I know there is at least one thread already here on the forum that talks about them.

macfixer01


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## patnor1011 (Jun 25, 2011)

Steve posted picture with rockwell chip opened and I did the same with chip from zip drives board. I would say most or nearly all chips contain gold but mostly in form of super thin bonding wires which are not visible with naked eye. You can see them when you crush package to fine dust, remove wires with magnet (80-90%). 10-20% are copper. Try to pan that crushed powder and as you will do that this gold wires will accumulate so you can see them. I like to look for them with help of watch repairer or jewelers magnifying glass.


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## samuel-a (Jun 25, 2011)

mic,

what are planing to smelt?


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## Harold_V (Jun 25, 2011)

mic said:


> Please advise,because this is something I will be starting as soon as next week(weather permitting).


Frankly, the only thing that provides longevity is not using flux. High alumina, and similar products offer decent resistance to dissolution, but even they have a finite life. Remember, the purpose of using flux is to do exactly what it does---liquefy solids, at which time it also absorbs oxides and other contaminants. Samual will have to balance his needs and decide if using his alumna vessel is a wise decision. It will hold up better than silicon carbide or graphite, but it will slowly dissolve. 

Harold


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## samuel-a (Jun 25, 2011)

OK Harold thank you.

That's sound like the resonable thing to do.

If i could pull at least 10 melts from that crucible i think i'll be fine, the capacity is about 500 ml and have a lid. I guess using the lid will help reduce damage to surrounding refactory.

I'll post a new thread once it become more relevant.


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## Anonymous (Jun 25, 2011)

Harold_V said:


> Frankly, the only thing that provides longevity is not using flux.


Since I am using litharge(lead oxide) ,couldn't I use glass as my gathering medium?I am not sure what to call it other than that,since I technically cannot call it flux.
Either way,Since I will be using borax and soda,I guess the only thing to do is use graphite,as opposed to silicon carbide,or fused silica.


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## qst42know (Jun 25, 2011)

What is it you are working on mic?

A crucible will produce a lead alloy button, cover over with a very fluid lead borosilicate slag at temperature and pretty much stop reacting. Disposable or what they consider to be disposable fire clay crucibles are sold for this use.


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## Anonymous (Jun 30, 2011)

qst42know said:


> What is it you are working on mic?





samuel-a said:


> mic,
> 
> what are planing to smelt?


Sorry guys,I have been hurt(yet again),and I've had to coordinate the rest of that big shipment from that company last week.And on top of all of that I have a very large shipment coming in tomorrow.
I have not had time to breathe,much less coordinate what the next project will be.I am very sorry,and I will try to get something ready for you guys next week.My litharge came in today,so I should be ready to go on the new melting/smelting project,as soon as I can catch up on everything else.


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## Harold_V (Jul 1, 2011)

mic said:


> Since I am using litharge(lead oxide) ,couldn't I use glass as my gathering medium?


No. Glass will absorb prills and may keep them in suspension. When you gather, a metal is desirable, so it will alloy with the prills, making them larger, encouraging them to combine instead of remaining in suspension in the flux (glass). By the way, common glass is nothing more than silica dissolved in soda ash. 

Harold


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## Anonymous (Jul 1, 2011)

Sorry Harold,
what I meant was,couldn't I just use glass,instead of borax and soda?
I have tons of borosilicate glass here,and just thought I could use it for this purpose.
I was definitely using the litharge as my "gatherer".Sorry again,just having an off-day.


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## Harold_V (Jul 1, 2011)

Borosilicate glass melts at a much higher temperature. If you're inclned to use glass, don't use borosilicate. I don't know if adding soda ash would be helpful, however. It may dissolve that way. Dunno! 

Harold


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## samuel-a (Jul 1, 2011)

Harold_V said:


> Borosilicate glass melts at a much higher temperature. If you're inclned to use glass, don't use borosilicate. I don't know if adding soda ash would be helpful, however. It may dissolve that way. Dunno!
> 
> Harold



Isn't Borosilicate glass = borax + silica dissolved in soda ash ??


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## Harold_V (Jul 1, 2011)

samuel-a said:


> Harold_V said:
> 
> 
> > Borosilicate glass melts at a much higher temperature. If you're inclned to use glass, don't use borosilicate. I don't know if adding soda ash would be helpful, however. It may dissolve that way. Dunno!
> ...


Don't think so ---I think the boro relates to boron, but I don't know that. 

I'll see if I can learn something from Google. 

Harold

Edit:

Ok, here's a link that helps explain borosilicate glass, which has boron oxide as part of its makeup. 

http://www.5fishdesigns.com/whatisboro.htm


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## celticsfan (Jul 7, 2011)

Borosilicate glass is highly desirable for making telescope mirrors because of its' low expansion and thermal qualities. Maybe Mics' "tons of borosilicate" would have a higher purpose than flux.
John


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