# Black cement with copper



## metatp (Sep 23, 2009)

Well, I guess I am experimenting too much again. I came up with a situation I wasn't expecting. I was experimenting with different type of electrical contacts I bought. I separated the ones that appeared to be made of Tungsten (based in posts from this forum). I took 25g and placed the them in 50/50 nitric and water for about a day. There was some dark grey powder like material and a tannish color sludge. After filtering and rinsing, the solution was a very light bluish tint (probably from the leftover solder). The contacts were basically still the same shape, but now dark gray and brittle.

All of this I expected. Where it get weird is when I tried to cement the silver to estimate the percent silver content. I place a piece of copper pipe (well at least I this it was pure copper) that is used for supplying water to a dishwasher. It immediately started to react, and black (maybe dark gray) flakes started to precipitate off. Did I say the reaction was very fast. Some of the black cement start dissolving as well. I am sure I had some left of nitric. After letting it sit for 15 hours, the entire jar was filled with this spongy black stuff (about 150ml).

What can this stuff be? I estimate only having 10-15g of silver. Is my copper piping really some copper alloy? I dissolved some in nitric as a test, and it seems like all copper. I am adding a little more nitric to dissolve it all again and try the stand copper I've used in the past.

This is so interesting, but I don't know what is going on.

Tom


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## butcher (Sep 24, 2009)

what is your nitric homade? (homade can have some sulfate in it if not distilled)
contact points can have alot of other metals besides silver.and if the arms or other switch part's were also included.
although copper pipe is not pure copper, it is very high percentage,
blue copper or nickel, were there brass or copper arms from points dilsolved?
the contacts were they removed from the arms? which contain base metals.
I suspect you have alot of base metals disolved. even the points can be base metals with precious metals
silver will plate out onto copper from nitrate solution as gray to blackish, so will any gold or PGM's from contacts


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## Harold_V (Sep 24, 2009)

butcher said:


> although copper pipe is not pure copper, it is very high percentage,


Take this with a grain of salt, for I have nothing to provide in the way of evidence that I'm right. 

It's unlikely pipe is made from anything less than electrolytic pure copper, much the same as used for making copper wire. 

Reason?

It is heavily worked in the process of producing pipe. Traces of impurities tend to degrade the material, reducing ductility. 

Electolytic parting of primary copper is pretty much routine, considering that's where the precious metals are recovered. These precious metals are harvested along with copper, from ores. If secondary copper is used in making pipe, I may be wrong. 

Can anyone contribute facts to this subject? 

Harold


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## metatp (Sep 25, 2009)

Most places I seen say they meet an ASTM standard which I've seen from 99.85% (from China) to 99.99% Copper.


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## metatp (Sep 25, 2009)

butcher said:


> what is your nitric homade? (homade can have some sulfate in it if not distilled)


No. It is ~70% nitric cut 50% with water.


butcher said:


> were there brass or copper arms from points dissolved? the contacts were they removed from the arms?


No. Just some solder. 


butcher said:


> I suspect you have a lot of base metals dissolved. even the points can be base metals with precious metals
> silver will plate out onto copper from nitrate solution as gray to blackish.


When I dissolve the contacts which I believe are tungsten with silver and some solder, the solution only had a slight blue tint. Most of the metal appears not to dissolve. The reaction was similar to when I dissolve brass. The resultant solution after cementing with copper was transparent, dark blue. I tested for silver, and it all dropped. I filter and the cement is a silvery black. It seems that the black stuff is coating the silver. It is a finer like powder that can even pass through the coffee filters if I am not careful. What is interesting is that this black dissolves in nitric.

I am drying it now, but it appears to be more than 10g. It should be less based on the weight of the leftover material that did not dissolve in the nitric. I will weigh it tomorrow and maybe take a picture.

I tested the same copper piper material to cement another solution of silver nitrate, and it cemented that same silver gray color I am used to.


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## lazersteve (Sep 25, 2009)

Sounds like the brittle gray stuff is tungsten (very heavy) , the light gray powder is silver, and the black nitirc soluble powder is palladium.

Dissolve some of the black stuff and test for Pd with stannous.

Steve


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## butcher (Sep 25, 2009)

here is some good info on copper impurity,

http://www.copper.org/publications/pub_list/pdf/copper_tube_handbook.pdf

http://www.copper.org/publications/newsletters/innovations/1997/12/wiremetallurgy.html

http://www.copper.org/publications/newsletters/innovations/how/howdo_tube.html


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## Anonymous (Sep 25, 2009)

Harold, 
From what I have heard at the yard, #2 copper and old plumbing copper go to makeing pipe, it is not re-electrorefined.
Not there first hand though so I can not swear to it.
Jim


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## qst42know (Sep 25, 2009)

I would suspect it is just like gold, refined to pure and alloyed as desired. 

I would also think the price at the yard has more to do with the refining required. Solid heavy pieces bring higher prices being cleaner than a drum full of chips which may have cutting tool fragments and almost anything that might get swept off the floor.


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## metatp (Sep 26, 2009)

Here is a picture of the final cemented material. It is 10g just as expected. It appears to be much more when wet, but I guess it was just very spongy. I don't have tin yet, so I haven't tested any in nitric with Stannous. I did take a couple of the suspect contact and soak them in nitric acid over night. The solution is yellow. Once I get so tin I will test it. 

What is the best way to separate Palladium from silver. I saw one method on this forum the had me convert the silver nitrate to form silver chloride and then use copper to cement the Palladium. I was hoping not to deal with silver chloride. Does anyone know another way? Since palladium melts at a higher temperature, can I melt the silver without melting the palladium? (pardon me if this is a dumb questions)

Can't seem to add a picture right now. maybe later.


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## Harold_V (Sep 26, 2009)

HTPatch said:


> The solution is yellow. Once I get so tin I will test it.


Palladium in solution forms a dark color, leaning towards coffee in appearance. That, of course, depends on the amount of palladium in solution. If you have very little present, it could be yellow, but that wouldn't explain the amount of black you're recovering. Very mystifying. Any reason to suspect platinum? It is much lighter in color when in solution. 



> Since palladium melts at a higher temperature, can I melt the silver without melting the palladium?


That won't work. Molten metals tend to be strong solvents of other metals. When you get the silver to the molten state, it will readily dissolve the palladium (or even platinum), in spite of being more than 1,000°F cooler than palladium's melting point. 

While you could part the elements chemically, there's nothing faster and better than a silver cell. Besides, you end up with pure silver for your trouble. 

Harold


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## metatp (Sep 26, 2009)

Harold_V said:


> Palladium in solution forms a dark color, leaning towards coffee in appearance. That, of course, depends on the amount of palladium in solution. If you have very little present, it could be yellow, but that wouldn't explain the amount of black you're recovering. Very mystifying. Any reason to suspect platinum? It is much lighter in color when in solution.


Platinum? I guess. I have some trapezoidal shape contacts. Some were tungsten with silver, but there were some that after nitric appeared to dissolve somewhat, but don't leave the same brittle dark gray stuff. It seem very hard to dissolve in nitric. I will pick up some tin tomorrow to test the solution. I am very tempted to put a piece of copper in the solution and see what happens. 



Harold_V said:


> Molten metals tend to be strong solvents of other metals. When you get the silver to the molten state, it will readily dissolve the palladium (or even platinum), in spite of being more than 1,000°F cooler than palladium's melting point.


That's what I thought, but thought I would ask.



Harold_V said:


> While you could part the elements chemically, there's nothing faster and better than a silver cell. Besides, you end up with pure silver for your trouble.


Well, I guess that will be my next project. A silver cell. Need to do some homework, but it appears to be worth it.

Here is a second attempt to upload a picture. Didn't work again. Don't know what is wrong.

Thanks again Harold. I will let you know what I find.


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## Harold_V (Sep 27, 2009)

HTPatch said:


> Here is a second attempt to upload a picture. Didn't work again. Don't know what is wrong.


Two things possible. The format is not compatible with the forum software, or the picture is oversized. Make sure it is no larger than 800 pixels in width, and 600 pixels in height. It's also a good idea to restrict file size, so you don't post pictures that are so large that folks with a dial-up connection won't read your posts. Perfectly acceptable pictures can be posted with file sizes as small as 50kb. 



> Thanks again Harold. I will let you know what I find.


I'll be watching to read what you learn. 

Harold


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## metatp (Sep 27, 2009)

I found out what was wrong with uploading pictures. It was my browser. I use firefox, and for some reason it doesn't work. I am able to send it via Internet Explorer. Please see the picture attached. 

The solution in nitric doesn't even seem yellow anymore. It is almost crystal clear. I could not fight the temptation, so I placed a piece of copper in the solution for a couple of seconds. It too start cementing a black substace, but I did not see any silver being cemented this time. I can't wait until I test the solution tomorrow or Monday.


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## Harold_V (Sep 27, 2009)

HTPatch said:


> The solution in nitric doesn't even seem yellow anymore. It is almost crystal clear. I could not fight the temptation, so I placed a piece of copper in the solution for a couple of seconds. It too start cementing a black substace, but I did not see any silver being cemented this time. I can't wait until I test the solution tomorrow or Monday.


Once you have stannous chloride, a good idea would be to dissolve a tiny sample of the black precipitate, starting with a drop of HCl. If that does nothing, add a drop of nitric. Use no more nitric than is necessary to dissolve the sample, or a good portion of the sample. Too much sample would be better than not enough, so you'd consume all of the nitric that was applied. If you find you need more HCl, add it accordingly. It doesn't matter if you use too much HCl, as long as you don't use unneeded nitric. Once action has ceased, you should test a drop of the solution. I always used a spot plate, but you can use a cotton swab, or even put a drop of solution on a piece of white paper. Apply a drop of stannous chloride and look for a color to develop. If no color does, the black material isn't anything worth pursuing. Make sure the stannous is good by testing with a drop of gold chloride. 

Edit: When you attempt to dissolve the black sample, it might pay you to use heat. If, by chance, you have platinum present, while the black mud will dissolve much easier than a solid piece, it is slow to dissolve, unlike gold. 

Harold


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## T3sl4 (Sep 27, 2009)

Tungsten can be dissolved in H2O2 and NaOH, as I recall. It should remain oxidized pretty well, I don't know if the metal can even be deposited from aqueous solution, certainly not with something as unreactive as copper.

Tim


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## metatp (Sep 27, 2009)

Harold,

The results of the tests are more confusing. When added HCL to a sample of the back powder, there was a reaction, and the solution was yellow with gray cement still at the bottom. I tested that solution with stannous chloride, and it turned a bright yellow.

I took another sample of the black powder and added HCL and a couple of drops of nitric. Once the reaction stopped, the solution was a neon greenish semiclear color with the gray cement still at the bottom. When I tested that solution with stannous chloride, it immediately turned a dark royal blue and after a few minute in air (outside), it turned to a bright neon green.

I have not tried just nitric acid to dissolve some of the sample.

My next check will be to soak the black cement in HCL. After filtering and rinsing the HCL solution, I might test new cement again.

Tom


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## Anonymous (Sep 27, 2009)

did you try to melt any of it? that may be interesting to see what if anything forms.

Jim


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## metatp (Sep 27, 2009)

james122964 said:


> did you try to melt any of it? that may be interesting to see what if anything forms.


the problem is that there is silver in the mix. If I can separate the two substances, I may try to metal or incinerate.


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## Harold_V (Sep 28, 2009)

HTPatch said:


> Harold,
> 
> The results of the tests are more confusing. When added HCL to a sample of the back powder, there was a reaction, and the solution was yellow with gray cement still at the bottom. I tested that solution with stannous chloride, and it turned a bright yellow.


Not exactly a common reaction, but yellow can be the sign of platinum, although rather dilute. Heating the sample would dissolve more if it is, indeed, platinum, assuming there is a little nitric present, and enough HCl. If it does not, I'm inclined to think of as being silver, perhaps chloride. Does it dissolve in a drop of ammonium hydroxide? If, after dissolving the sample, what does a drop of DMG show?



> I took another sample of the black powder and added HCL and a couple of drops of nitric. Once the reaction stopped, the solution was a neon greenish semiclear color with the gray cement still at the bottom.


I'm still inclined to think of the gray material as silver and/or chloride. Neon greenish? Don't have a clue, although if there is nickel or copper present, that could be influencing the color. 



> When I tested that solution with stannous chloride, it immediately turned a dark royal blue and after a few minute in air (outside), it turned to a bright neon green.


Palladium is a bit of a chameleon, and will yield color combinations in keeping with what you experienced. If you have any DMG, test a drop of the solution. This test will be conclusive. Palladium yields a deep canary yellow precipitate, and it takes very little in solution for the precipitate to develop and be visible. If you get no reaction, you don't have palladium. 



> I have not tried just nitric acid to dissolve some of the sample.


 Frankly, that may be a wise test, although you may already have some silver chloride, which won't dissolve. It should, however, shift color until it is a creamy white once boiled in dilute nitric. I think you have more than one element present, so the signs are confusing. 

It would be dead simple to determine what you have if you had a few testing chemicals. This is the very reason why I recently suggested to yvonbug that she is running blindly by not having stannous chloride. It's very common to end up with solutions that can't be identified. With a few fundamental tests, you can either conclude what you do have, or what you don't have. 

If you intend to stay with recovering silver, it's only a matter of time until you come across palladium, or even platinum. Becoming familiar with the tests will do you a world of good in answering questions that are now confounding. Besides, it's actually quite interesting!

In order to satisfy the unknown, you should have the following:
Schwerter's solution
nitric acid
HCl
stannous chloride
DMG
Standard gold solution
ammonium hydroxide

With these, you should be able to identify copper, nickel, platinum, palladium, gold, silver, brass/bronze, even aluminum and magnesium. 

It would pay you to read Hoke's books on testing, too. 

Keep the reports coming. Some pictures of the reactions would be helpful. 

Harold


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## metatp (Sep 28, 2009)

Harold_V said:


> I'm inclined to think of as being silver, perhaps chloride. Does it dissolve in a drop of ammonium hydroxide? If, after dissolving the sample, what does a drop of DMG show?


Sadly, i do not have ammonium hydroxide or DMG. Can you point me to any sources? I do have a pool supply store near by if it is something they use for pools. 



Harold_V said:


> I'm still inclined to think of the gray material as silver and/or chloride. Neon greenish? Don't have a clue, although if there is nickel or copper present, that could be influencing the color.


I know there is silver, and it was cemented with copper so there may be some copper present.



Harold_V said:


> Palladium is a bit of a chameleon, and will yield color combinations in keeping with what you experienced. If you have any DMG, test a drop of the solution. This test will be conclusive. Palladium yields a deep canary yellow precipitate, and it takes very little in solution for the precipitate to develop and be visible. If you get no reaction, you don't have palladium.


I am pretty sure i know what contacts are creating this situation. Problem is that I thought they were silver tungsten contacts so I put them all together. I did dissolve the rest (with a little silver) in nitric, but there is a lot of extra nitric in the solution. Will DMG be ok with excess nitric acid? 



Harold_V said:


> Besides, it's actually quite interesting!


That it is.



Harold_V said:


> In order to satisfy the unknown, you should have the following:
> Schwerter's solution
> nitric acid
> HCl
> ...


Have everything but the DMG and ammonium hydroxide.



Harold_V said:


> It would pay you to read Hoke's books on testing, too.


I have read this section, but have not played around with any of the testing she mentions.

I will reproduce what testing i did and take pictures tomorrow.


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## eeTHr (Sep 28, 2009)

HTPatch;

See first paragraph, 12th sentence---
http://en.wikipedia.org/wiki/Ammonia

So you can get it at a grocery or drug store. 8)


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## Anonymous (Sep 28, 2009)

Harold,
Am I missing something? I have been under the impression that copper can only replace precious metals. 
And if thats the case then he should only have precious metals in that black mix.

I have used copper for shotgun replacement of precious metals when I had to dissolve everything from IC chips.
That was before I was able to get nitric only, so I had to use a variation of the poors mans AR to recover the metals.
Jim


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## metatp (Sep 28, 2009)

Here are the pictures where the sample was soaked in HCL. It appears that the color change is disappearing over time.


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## metatp (Sep 28, 2009)

Here are the pictures where the sample was soaked in a little NO3 and HCL. It appears that the color change is disappearing over time as well.


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## metatp (Sep 28, 2009)

I took some of the suspect contacts and put it in some nitric acid for a few days. They did start to dissolve, but very slowly. There was no noticeable fizzing. There should be no silver (in don't think). The solution was clear with some reddish brown residue (same color as the final contacts) that was filtered out.

Stannous chloride test of the solution is a pale blue.


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## Harold_V (Sep 29, 2009)

james122964 said:


> Harold,
> Am I missing something? I have been under the impression that copper can only replace precious metals.
> And if thats the case then he should only have precious metals in that black mix.


Yes, I agree, but if there was any copper oxide present, or if the material wasn't washed well, it's entirely possible that there would be traces of copper included. Just trying to cover all of the bases. Right now, I'm totally confused. I'm reading about (and seeing) reactions that I never experienced. 

Edit:

I have never seen the bright green reaction, pictured above. The blue reaction I am inclined to attribute to tungsten. I recall that when washing silver cemented from contacts that came down quite dirty that the HCl solution turned a dark blue color. I do not recall testing with stannous in this case, secure in the knowledge that I didn't have any precious metals present. If the blue reaction is the result of a test with stannous, I'm still just as lost as I have been from the outset. _(a second edit here: Now that I've had time to think on this, if the sample was tested with a stannous solution that has an excess of HCl, and the solution contains traces of tungsten, the blue reaction could well be attributed to the presence of tungsten, and has nothing to do with the fact that stannous chloride was introduced. That could be determined by adding a drop of HCl alone to the test sample to see if it reacts accordingly._) I clearly don't have a clue what the hell is going on at this point. 

I wonder if GSP has followed this thread? He has a lot more experience than I do with silver, and may have seen these reactions before. 

At this point in time, if there's the least question that the reaction may be palladium, a DMG test is a great idea. 

Fading color reactions are often the result of an excess of nitric. There are instances where the reaction takes place and fades almost instantly. That may account for the slow degradation being experienced. Dunno! 

Harold


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## qst42know (Sep 29, 2009)

Cobalt blue was a common potent colorant for early pottery, however I don't have a clue how it would react to acids or stannous. As I remember reading it took very little cobalt to produce a deep blue glaze.

What say the chemists of the forum?


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## lazersteve (Sep 29, 2009)

I've never seen blue with stannous tests. I've worked with gold plated tungsten/ copper alloy once and the result was a yellow powder and a orange yellow liquid.

Cobalt is another option I was considering, but I don't have any experience with stannous and it to say for sure.

I'm wondering if the orange/ green reaction may be a result of Pd, the only odd part is that the reaction typically starts orange and changes to green-blue with a minute or so depending on the concentration. The azure blue color on the stannous swab looks like copper nitrate or a cobalt compound to me.

Here's a few more test you can perform:

1) Rinse and dry a small sample of the material then try to melt is and see what happens.

2) Take a sample of the green acidic liquid and add in some solid copper, see if you get a cementation reaction.

This one is a new one to me also.

Steve


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## metatp (Sep 29, 2009)

Harold_V said:


> The blue reaction I am inclined to attribute to tungsten. I recall that when washing silver cemented from contacts that came down quite dirty that the HCl solution turned a dark blue color.


The blue ocurred with the nitric, not the HCL. the HCL only was yellow. I thought tungsten did not dissolve in nitric or HCL. The HCL does appear to remove the black and turn the solution to a yellowish green. There is definitely tungsten in the mix that was dissolved. The precipitant maybe a dark blue not black. Why would it cement on copper? I have another sample that I am cementing the black stuff with copper right now. There should be little or no silver in this batch. i will then redissolve making sure there is not excess nitric and test again to see if the same blue appears.



Harold_V said:


> Now that I've had time to think on this, if the sample was tested with a stannous solution that has an excess of HCl, and the solution contains traces of tungsten, the blue reaction could well be attributed to the presence of tungsten, and has nothing to do with the fact that stannous chloride was introduced. That could be determined by adding a drop of HCl alone to the test sample to see if it reacts accordingly.


HCL does react. It formed a yellow solution that tended toward grean over time. I deffinitely get different results when HCL only or HCL with a drop on nitric. I will take the solution that was hcl and nitric and just add a drop of 32% hcl to see what happens

What about a contact with tungsten and some material other than silver? Has anybody seen a different alloy with tungsten for a contact?



Harold_V said:


> At this point in time, if there's the least question that the reaction may be palladium, a DMG test is a great idea.


This appears to be key. I will persue getting some DMG. I only have one contact left that is giving these results, so all this learning may just be for learning sake. I will try to find the source of these contacts, but the guy I got them from says he collected them over the course of the last 25 years. 



Harold_V said:


> Fading color reactions are often the result of an excess of nitric.


 Could this be true with excess HCL also? I know I had excess HCL.

Thanks again,
Tom


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## qst42know (Sep 29, 2009)

I was doing some digging and tungsten is sintered with Co, Ni, Fe, Mo, Cu. In a variety of combinations and ratios for the desired properties.

You may be leaching binders for your base colors. If that helps any.


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## metatp (Sep 29, 2009)

lazersteve said:


> Cobalt is another option I was considering, but I don't have any experience with stannous and it to say for sure.


I was wondering about cobalt. I thought I read somewhere that it would show blue, but i can't remember if that was the solution or the stannous chloride test.



lazersteve said:


> Here's a few more test you can perform:
> 
> 1) Rinse and dry a small sample of the material then try to melt is and see what happens.


I am preparing a new sample that should have little of no silver in it. Copper is cementing the black stuff as we speak. I will redissolve some in a small amount of nitric and test with Stannous again. I will also dry it and try to melt it (though I only have MAPP).



lazersteve said:


> 2) Take a sample of the green acidic liquid and add in some solid copper, see if you get a cementation reaction.


I started this with the sample that is in HCL. There was not cementation reaction imediately. I will check when I get home.



lazersteve said:


> This one is a new one to me also.


It is probably just me. I probably messed something up and the information is not getting on this forum. I am new, so maybe there is an important piece of information I am not aware of.


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## T3sl4 (Sep 29, 2009)

Tungsten, in the form of carbide cutting tools, is essentially powder brazed together with a matrix of cobalt. Something like 80% WC or W2C, balance cobalt. You can safely assume WC is insoluble: the damn stuff melts at 6000 degrees.

I've taken some carbide grindings, soaked in HCl and got a lovely pink solution: the color of cobalt chloride hydrate. That, and a lot of black sludge (the WC, and any Co that didn't dissolve). The solid salt might be recognized from dessicators, as it turns pink when hydrated, blue when dehydrated.

Stannous chloride is a reducing agent, right? Cobalt is already reduced, in the +II state, and it's somewhat unwilling to go any higher (though some complexes take it up to +4, as I recall). It's typically a pink color in chloride solution. The strength of color is typical of chlorides, including iron, copper, etc., and not overwhelming like the color of potassium permanganate. Only when cobalt is fused into a glassy substance does it get insanely blue (I think cobalt glass is to the tune of 2% Co).

Tim


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## qst42know (Sep 29, 2009)

The color ranges of the different states of cobalt oxide are mentioned in these links. 

http://en.wikipedia.org/wiki/Cobalt_oxide


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## metatp (Sep 29, 2009)

OK. Here's what I think is happening. I preface this with I am not a chemist and don't know what I am talking about.

I think the black stuff is not really cementing with copper. I think that silver is cementing, and the black stuff is going for the ride. I think it is coating the silver powder. I also think that the black stuff is actually very very dark blue. 

I just placed some copper in a nitric acid solution containing very little silver (just maybe some left overs). The blackish stuff started dropping off, but when i came home from work, the solution was black. After filtering and rinsing, the solution was still very dark with almost no powder left in the filter. After dipping a Q-tip in the solution, it is actually a dark blue. Stannous chloride did not change the solution color much. just made it a little bluer.

Warm water does not seem to remove all the dark blue/black material from powder. I don't this it is very water soluble. I am going to try a quick rinse of the silver rich black powder with dilute nitric acid of maybe dilute sulfuric acid to see if the black dissolved off. I see that it comes off in HCL, but appears to make silver chloride at the same time (it did not redissolve very well in nitric).

I don't think there is any values other than the silver. After I get some DMG (somewhere) and confirm no Palladium, i will abandon this learning experience. i will try a quick melt of the black powder first.

FYI. I read from I-Shor that Iridium turns blue-black when Stannous chloride is added.

Thanks all. It has been a fun ride.


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## metatp (Sep 30, 2009)

This almost feel like I am blogging.

I rinsed and rinsed and rinsed. I still could not get the filter solution totally clear. i took a sample of the powder and add just water and nitric acid. After sitting for some time, the solution had only a slight green tint. Tested with Stannous and it turned a faint blue. the left over powder looks like silver. Tried to melt the rest. I got a small silver button that tested as a high purity silver with some black encrustation on it that would not melt (only got red hot with mapp). Tried to melt the left over contact that did not dissolve yet in nitric, and it would not melt as well. It is not like the tungsten/silver alloy contacts where they break easy after the silver is dissolved. Except for the really thin sections, I cannot break them by hand.


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