Black cement with copper

[metatp]

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

 

[butcher]

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

 

[Harold_V]

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

 

[metatp]

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

 

[metatp]

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

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

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

No. Just some solder.

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.

 

[lazersteve]

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

 

[butcher]

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

 

[Anonymous]

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

 

[qst42know]

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.

 

[metatp]

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.

 

[Harold_V]

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

 

[metatp]

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.

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.

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.

 

[Harold_V]

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

 

[metatp]

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.

 

[Harold_V]

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

 

[T3sl4]

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

 

[metatp]

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

 

[Anonymous]

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

Jim

 

[metatp]

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.

 

[Harold_V]

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