# I bought some scrap on eBay



## lasereyes

I won about a pound of this type of aviation computer pin gold plated scrap on eBay, it is in the mail right now. A rough estimate based on surface area tells me that there should be several grams of gold in this lot. I payed about 60 dollars with shipping. Did I get a good deal? Here is a link to the auction in question: http://cgi.ebay.com/ws/eBayISAPI.dl...witem=&sspagename=STRK:MEWNX:IT#ht_1617wt_936


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## samuel-a

How do you know the plated surface area?

These type of electrical connection pins are usually high grade plating...


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## lasereyes

samuel-a said:


> How do you know the plated surface area?
> 
> These type of electrical connection pins are usually high grade plating...



There is a picture of a few pins next to a ruler, so I guesstimated the surface area based on a 1/2inch long cylinder with a 1.5 mm thickness. I did a rough estimate of how many pins there are in the picture, then used the methods on this forum to estimate gold content. I think the plating's grade could be millspec.


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## samuel-a

we'll be smarter once you finish them...

milspec.... don't fall in love with this term, this is mainly a fleebay promoting "power word" for scrap...
There are lot's of civilian applications that use thicker plating then some military applications...

once you receive the pins, digest a sample in nitric acid (50/50) and see if there's one complete foil left after digestion or is it brakes apart into gazillion pieces... this will help you ballpark the plating thickness...


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## lasereyes

samuel-a said:


> we'll be smarter once you finish them...
> 
> milspec.... don't fall in love with this term, this is mainly a fleebay promoting "power word" for scrap...
> There are lot's of civilian applications that use thicker plating then some military applications...
> 
> once you receive the pins, digest a sample in nitric acid (50/50) and see if there's one complete foil left after digestion or is it brakes apart into gazillion pieces... this will help you ballpark the plating thickness...



No beans, nitric is too expensive, I will probably be partially digesting the pins in poor man's AR. When I'm finished with the process I will be sure to post the yield here.


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## Barren Realms 007

lasereyes said:


> samuel-a said:
> 
> 
> 
> we'll be smarter once you finish them...
> 
> milspec.... don't fall in love with this term, this is mainly a fleebay promoting "power word" for scrap...
> There are lot's of civilian applications that use thicker plating then some military applications...
> 
> once you receive the pins, digest a sample in nitric acid (50/50) and see if there's one complete foil left after digestion or is it brakes apart into gazillion pieces... this will help you ballpark the plating thickness...
> 
> 
> 
> 
> No beans, nitric is too expensive, I will probably be partially digesting the pins in poor man's AR. When I'm finished with the process I will be sure to post the yield here.
Click to expand...


You might consider slowing down till you know what you are doing. And take the suggestions of the forum members. It will save you a lot of grief and headaches.


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## lasereyes

Barren Realms 007 said:


> lasereyes said:
> 
> 
> 
> 
> 
> samuel-a said:
> 
> 
> 
> we'll be smarter once you finish them...
> 
> milspec.... don't fall in love with this term, this is mainly a fleebay promoting "power word" for scrap...
> There are lot's of civilian applications that use thicker plating then some military applications...
> 
> once you receive the pins, digest a sample in nitric acid (50/50) and see if there's one complete foil left after digestion or is it brakes apart into gazillion pieces... this will help you ballpark the plating thickness...
> 
> 
> 
> 
> No beans, nitric is too expensive, I will probably be partially digesting the pins in poor man's AR. When I'm finished with the process I will be sure to post the yield here.
> 
> Click to expand...
> 
> 
> You might consider slowing down till you know what you are doing. And take the suggestions of the forum members. It will save you a lot of grief and headaches.
Click to expand...


Well I think it will work out alright, but I don't think that I can justify the cost of nitric acid when nitrates are so much cheaper. Money can be tight some times, especially while going to school, so this seems like an ideal hobby that also has a potential to deliver a return on investment.


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## lazersteve

You can process a small sample of the scrap with 35% H2SO4 (battery acid) and NaNO3 (nitrate of soda, sodium nitrate) to get the base metals out leaving the foils behind. 

The process is the same as Modified Poorman's AR, except you use sulfuric acid instead of muriatic. The solid sodium sulfate (by product) rinses out of the gold foils with hot water.

No need to buy technical grade nitric for the test.

Steve


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## lasereyes

lazersteve said:


> You can process a small sample of the scrap with 35% H2SO4 (battery acid) and NaNO3 (nitrate of soda, sodium nitrate) to get the base metals out leaving the foils behind.
> 
> The process is the same as Modified Poorman's AR, except you use sulfuric acid instead of muriatic. The solid sodium sulfate (by product) rinses out of the gold foils with hot water.
> 
> No need to buy technical grade nitric for the test.
> 
> Steve



Unfortunately I do not have any sulfuric acid around to do this sort of test. The hcl that I bought was from ace hardware store. Am I correct to assume that drain cleaner would be suitable due to its sulfuric acid content? I think I have seen it at lowes.


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## lazersteve

NAPA auto parts carries the 35% stuff for batteries, cost is around $15 for 5 gallons. It's very clean compared to the drain opener.

ACE carries the Rooto acid drain opener, but it is in the high 90% concentration so you can dilute it (1:3, acid:water) for the test.

Steve


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## lasereyes

lazersteve said:


> NAPA auto parts carries the 35% stuff for batteries, cost is around $15 for 5 gallons. It's very clean compared to the drain opener.
> 
> ACE carries the Rooto acid drain opener, but it is in the high 90% concentration so you can dilute it (1:3, acid:water) for the test.
> 
> Steve



Sounds like a good deal, but a shame, since there used to be a napa store about 10 blocks from where I live, but it closed a while ago. I will look around for the drain opener and report back here with the test results soon.


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## samuel-a

lasereyes,

Steve gave here great alternatives to nitric.
If finding sulfuric turns out to be a problem, don't forget that you can always put your sample in straight HCL and wait a week or so.


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## qst42know

Lowes was expensive $32 for 2.5 liter box. Check other auto parts stores. OReillys (Murray's) also carries battery acid. They had it in stock 5gal box for $25, I didn't price the smaller container.


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## lasereyes

qst42know said:


> Lowes was expensive $32 for 2.5 liter box. Check other auto parts stores. OReillys (Murray's) also carries battery acid. They had it in stock 5gal box for $25, I didn't price the smaller container.



Lowes and shucks/oriellys are equidistant from where I live so I might check the acid there.


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## lasereyes

samuel-a said:


> lasereyes,
> 
> Steve gave here great alternatives to nitric.
> If finding sulfuric turns out to be a problem, don't forget that you can always put your sample in straight HCL and wait a week or so.



I wish I had the patience to wait a week...


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## lazersteve

Here's the meat of a 'Dry poor man's nitric acid' reaction.

I can post the long version of this post with math and equations if anyone wants to see it.

*The Reaction:*


Place 50 grams of copper based scrap in a 1.5 Liter beaker.
Cover the scrap with 253mL of distilled water.
Add in 253g of anhydrous NaHSO4 (sodium bi-sulfate) and cover with a watch glass.
Heat the reaction to 100C.
Allow enough time for the NaHSO4 to dissolve completely.
Reduce heat until temperature is 90C.
Slowly add 10g of NaNO3 (sodium nitrate) being careful of foam overs.
Cover and allow to react until all red-brown fumes are gone and no more fizzing is seen.
Repeat steps 7 through 9 until all of the copper scrap is dissolved, you *should not* add over 180 g of NaNO3.
Reaction is complete when the gold foils float freely when stirred. A white powder may also be in the bottom of the beaker (Na2SO4). 
The solution will turn dark blue from dissolved copper sulfate crystals (CuSO4). 
Pour off the blue solution while still hot. 
Add in 700 mL of water and bring to boil.
Heat until all of the white powder (Na2SO4 = sodium sulfate) dissolves and the gold foils are free of white powder.
Pour off the liquid while hot, don't pour off any of the gold foils.
Rinse with enough water to remove all traces of blue and white powder.
Process the gold foils as typical.
Steve


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## lasereyes

lazersteve said:


> Here's the meat of a 'Dry poor man's nitric acid' reaction.
> 
> I can post the long version of this post with math and equations if anyone wants to see it.
> 
> *The Reaction:*
> 
> 
> Place 50 grams of copper based scrap in a 1.5 Liter beaker.
> Cover the scrap with 253mL of distilled water.
> Add in 253g of anhydrous NaHSO4 (sodium bi-sulfate) and cover with a watch glass.
> Heat the reaction to 100C.
> Allow enough time for the NaHSO4 to dissolve completely.
> Reduce heat until temperature is 90C.
> Slowly add 10g of NaNO3 (sodium nitrate) being careful of foam overs.
> Cover and allow to react until all red-brown fumes are gone and no more fizzing is seen.
> Repeat steps 7 through 9 until all of the copper scrap is dissolved, you *should not* add over 180 g of NaNO3.
> Reaction is complete when the gold foils float freely when stirred. A white powder may also be in the bottom of the beaker (Na2SO4).
> The solution will turn dark blue from dissolved copper sulfate crystals (CuSO4).
> Pour off the blue solution while still hot.
> Add in 700 mL of water and bring to boil.
> Heat until all of the white powder (Na2SO4 = sodium sulfate) dissolves and the gold foils are free of white powder.
> Pour off the liquid while hot, don't pour off any of the gold foils.
> Rinse with enough water to remove all traces of blue and white powder.
> Process the gold foils as typical.
> Steve



Does it also work to just dissolve the gold in solution with a portion of the base metals in poor mans AR, or is removing all of the base metals necessary? Also, is it ok to use poor mans AR at room temperature or should it be heated?


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## lazersteve

This is not for gold, it is for base metals.

I always heat the reactions. 

I can't guarantee results for those of you who choose not to follow the directions as given.

Steve


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## lasereyes

lazersteve said:


> This is not for gold, it is for base metals.
> 
> I always heat the reactions.
> 
> I can't guarantee results for those of you who choose not to follow the directions as given.
> 
> Steve



Does it work on all base metals or only copper?


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## lazersteve

It will work for any base metal that dissolves in nitric acid.

The numbers given are for copper based scrap, adjust according to base metal type molar mass relative to copper and it's respective nitrate compound formula.

Steve


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## lasereyes

lazersteve said:


> It will work for any base metal that dissolves in nitric acid.
> 
> The numbers given are for copper based scrap, adjust according to base metal type molar mass relative to copper and it's respective nitrate compound formula.
> 
> Steve



Do you think that I could use the acid-peroxide method instead of nitric acid or sulfuric acid and nitrates? I have some hydrogen peroxide somewhere, it is in the concentration for medical applications I guess.


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## lazersteve

Acid Peroxide works for copper based scrap, and not other base metals.

Steve


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## lasereyes

lazersteve said:


> Acid Peroxide works for copper based scrap, and not other base metals.
> 
> Steve



What is the proper ratio of the 35% sulfuric acid to sodium nitrate for the regular version of poor mans nitric acid?


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## lazersteve

With 98% sulfuric acid the required volume 57 mL per 170 g or NaNO3.

Since you want to know what volume of 35% H2SO4 to use simply do the math:

35% / 98% = 0.357

57 mL / 0.357 = ~ 160 mL 35% H2SO4

or

160 mL H2SO4 / 170 g NaNO3 = 0.94 mL of 35% sulfuric acid per 1 g of nitrate.

Don't forget the water need for the reaction.

Steve


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## lasereyes

lazersteve said:


> With 98% sulfuric acid the required volume 57 mL per 170 g or NaNO3.
> 
> Since you want to know what volume of 35% H2SO4 to use simply do the math:
> 
> 35% / 98% = 0.357
> 
> 57 mL / 0.357 = ~ 160 mL 35% H2SO4
> 
> or
> 
> 160 mL H2SO4 / 170 g NaNO3 = 0.94 mL of 35% sulfuric acid per 1 g of nitrate.
> 
> Don't forget the water need for the reaction.
> 
> Steve



How much H2SO4 and sodium nitrate should I use for each gram of scrap? Do I add water if I am using dilute acid?


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## lazersteve

Return to page one of this thread and read it again.

Steve


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## lasereyes

The first pages mentions 50 grams of copper. does this mean that I will need to use half a liter of acid and multiple kg of nitrates just to dissolve a pound of copper? I only have 370g of NaNO3 and about a liter of 98% HSO4. Also, my largest beaker only holds 1 liter. If I cannot get a hold of sodium nitrate, should I just use the acid peroxide method instead?


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## lazersteve

The math for dissolving copper with nitric has been shown in several places on the forum.

Search my posts for 'copper sodium nitrate' (without the quotes) and you will see the math for nitrate and copper.

It's a lot of nitrate per pound of metal.

Steve


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## lasereyes

lazersteve said:


> The math for dissolving copper with nitric has been shown in several places on the forum.
> 
> Search my posts for 'copper sodium nitrate' (without the quotes) and you will see the math for nitrate and copper.
> 
> It's a lot of nitrate per pound of metal.
> 
> Steve



Thanks, I suppose these things are easier to understand when put into terms of basic chemistry and equations, I remember doing stoichiometry like this in high school and college. It seems as if all of the methods of base metal dissolution that requires nitrates is impractical for me (I don't want to have to repeat the process 10+ times in a 1 liter beaker to process a pound of scrap).


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## infinatesorrow

now im assuming anhydrous sodium bi-sulfate would be just your basic pool treatment since its without water in salt form?


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## lazersteve

infinatesorrow said:


> now im assuming anhydrous sodium bi-sulfate would be just your basic pool treatment since its without water in salt form?



Not necessarily so, plenty of salts contain water in their crystalline structure. The only way to know for sure is to dehydrate it by heating to the point where is no longer gives off water. If your salt appears to melt t 58.5C you have the type with water in it's structure. If it melts at 315C it's the anhydrous type.

Steve


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## dtectr

I thought I'd bump this topic, as I was in Lowe's recently & they are changing vendors for pool supplies. Therefore, they are "Clearance"-ing some of the chemicals we use, including sodium bisulfate, used in the "Dry Poor Man's Nitric" described here. 

The large container of 95% sodium bisulfate, "Ph Decreaser", was less than $4 US.
EDIT: clarity/accuracy


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