jgourlay
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How to identify beryllium in copper alloys?
Gents, I have some old bronze/copper parts coming from a facility that made parts from bronze, and parts from BeCu.
Instead of selling them for scrap, I want to cast them into this and that and then machine the castings. I have 1 bar that is positively identified
as BeCu, and it's color is not that different from some other bronze parts that I know are not BeCu.
That leaves me with a bucket of parts of unknown content. On the one hand, the bucket is too large a pile of metal to sell for pennies on the pound
knowing that I need that quantity of metal. On the other hand, I'm not so totally stupid as to melt it without being sure I'm not going to kill
myself or my kids with fumes.
Is there any way I can tell if this stuff has beryllium content?
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Hydragyrum
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Not sure, but I'd start with dissolving a sample of alloy in acid (use excess alloy so final solution is not acidic) - the beryllium is not volatile
so won't be dangerous unless you get the solution onto your skin. From here you might try adding ammonia solution - the copper will dissolve as
[Cu(NH3)4]2+ while the beryllium should form insoluble Be(OH)2 - which apparently looks a lot like Al(OH)3.
By the way, assuming that your other bronze parts are really bronze, you will have CuSn and Sn may also give a precipitate of Sn(OH)2 with ammonia.
Both Sn(OH)2 will dissolve in excess NaOH giving [M(OH)4]2- (M = Be or Sn). So, they should react the same up to this point, but you probably can tell
Sn(II) apart from Be(II) by a redox reaction - Sn(II) is a reducing agent, Be(II) is not.
If you take the white precipitate (which may be either Be(OH)2 or Sn(OH)2) and acidify so as to redissolve, the tin solution should reduce Fe(III) to
Fe(II), ie., yellow to green, while the beryllium solution will have no effect.
Note that I have not done this myself - it is just a suggestion.
Also note that if your CuBe has Sn in it too, you will show positive for Sn. Just be sure that the CuBe only contains Cu and Be.
[Edited on 6-6-2009 by Hydragyrum]
Chemistry is life (and a whole lot more)
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watson.fawkes
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Oh, the number
of copper alloys called bronze, but without tin, is just enormous nowadays. You just can't assume Sn in present. Al and Si are common alloying agents,
for example.
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not_important
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Be(OH)2 is soluble in alkali, and alkali and ammonium carbonate solutions. It is precipitated from its solution in ammonium carbonate by boiling,
which brings down a basic carbonate.
Beryllium tends to follow aluminium and chromium in the standard wet analytic methods. Attempting to separate it from copper using ammonia will
likely give an incomplete separation as strong NH4OH is likely to dissolve some Be(OH)2 along with the copper, while dilute NH4OH will not dissolve
much of the Cu(OH)2
Journal of Hazardous Materials
Volume 93, Issue 3, 5 August 2002, Pages 271-283
Beryllium colorimetric detection for high speed monitoring of laboratory environments
Tammy P. Taylor and Nancy N. Sauer
doi:10.1016/S0304-3894(02)00031-6
J. Am. Chem. Soc., 1928, 50 (2), pp 393–395
THE DETECTION OF TRACES OF BERYLLIUM AND THE COLORIMETRIC DETERMINATION OF THIS ELEMENT
I. M. Kolthoff
DOI: 10.1021/ja01389a022
A SIMPLE TEST FOR THE DETECTION OF THE BERYLLIUM MINERALS
www.minsocam.org/ammin/AM31/AM31_82.pdf
Colorimetric Wipes are Specific, Sensitive, and Fast
http://www.nextteq.com/docs/Articles/Colorimetric%20Wipes%20...
[Edited on 7-6-2009 by not_important]
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JohnWW
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Quote: Originally posted by watson.fawkes  | | Oh, the number
of copper alloys called bronze, but without tin, is just enormous nowadays. You just can't assume Sn in present. Al and Si are common alloying agents,
for example. |
There also also aluminium bronzes, which are more reddish and lustrous than other "bronzes". (I have worked with them). They would probably resemble
beryllium bronzes.
In World War 2, the Germans were short of tin (except for what they could get from the Japanese, using cargo submarines, after they occupied Malaya in
early 1942), but had lead and copper (and zinc) mines, so they made lead bronzes and brasses instead of the normal tin bronzes and brasses.
Other copper alloys include cupro-nickel, containing about 25% nickel, used mostly for coinage; and "German silver", containing copper alloyed with
zinc and nickel, with a lustrous white color, commonly used as base metal for silver-plating of cutlery etc..
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