Author Topic: Possible Mg from pencil sharpeners  (Read 986 times)

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  • Guest
Possible Mg from pencil sharpeners
« on: July 24, 2003, 04:27:00 AM »

This has been mentioned before by

Post 91756 (missing)

(Dr. Joy: "Plentiful OTC source of Magnesium.", Chemicals & Equipment)
back in '99.

Check this url:

If one carefully looks around in his environment , then one will be astonished of how often pure chemical compounds can be found. An example is the pencil sharpener, that apart from the variants from plastics, usually exists completely from magnesium. Magnesium belonged to the lightest metals (after beryllium) and exhibits some remarkable characteristics.

In this attempt the special characteristic is to be examined as strong reducing agent. Thus magnesium burns not only in air, but e.g. also in a CO2, SO2, NO2 or water vapour atmosphere.
Tigelzange (?), Bunsen burner or lighter, fibre glass, test tube (unfusable), glass tube with point, perforated plug, fibre glass, steel wool, burner, 2 candles, stand material
Magnesium (either as a whole or in the form of splinters, e.g. of a pencil sharpener), damp sand


  • Guest
Tigelzange (?) Zange = tongs ;-)
« Reply #1 on: July 24, 2003, 06:05:00 AM »
Tigelzange (?)

Zange = tongs  ;)


  • Guest
epsom salts
« Reply #2 on: July 24, 2003, 07:52:00 AM »
I don't know if this is relevant or not, but recently learning about how to turn magnesium sulphate into magnesium hyroxide and magnesium oxide made me think that epsom salts could be a source for magnesium if one can find a way to get it attached to something one wants to use it together with (like maybe aluminium perhaps). I'm pulling things out of my hat here, but I would think that a kiln would probably turn magnesium sulphate into elemental magnesium if one could surround it by an inert atmosphere (argon or something similar).

I had no idea pencil sharpeners were made largely of magnesium. I'm going to put one on a piece of metal on a fire soon and see what happens just for fun.


  • Guest
will not work
« Reply #3 on: July 24, 2003, 10:48:00 AM »
I'm pulling things out of my hat here

Yup, but it ain't elemental magnesium!  :)

Elemental Mg is usually prepared by electrolysis of a molten mixture of MgCl2 and KCl, whereto a small % of CaF2 is added.

Compare this to the preparation of Na (Downs cell), K, Ca ; this is the normal way of reducing an alkali (earth) metal salt to the metal.
Mg salts cannot be reduced to the element by Al or Zn!


  • Guest
Reduction to Magnesium by Zinc
« Reply #4 on: July 24, 2003, 07:42:00 PM »

Mg salts cannot be reduced to the element by Al or Zn!

F Lauterborn claimed in

Patent DE39915

to have heated magnesium ferrocyanide mixed with sodium carbonate to produce a double cyanide, which was then reduced by heating with zinc to magnesium metal  :)


  • Guest
Grignard ?
« Reply #5 on: July 24, 2003, 08:31:00 PM »
If the pencil sharpeners are pure enough for a Grignard I want to doubt. For small amounts I raid my elements collection but for bigger ones I wouldn´t know......


  • Guest
Magnesium casting alloys...
« Reply #6 on: July 25, 2003, 04:53:00 AM »
That pencil sharpener is not pure magnesium! It's an alloy which probably contains 3.5 - 5.0% zinc, 0.4 - 1.0% zirconium about 1% of some rare earth. Probably not pure enough for whatever you had in mind.


  • Guest
« Reply #7 on: July 26, 2003, 04:08:00 AM »
I was thinking too that a pencil sharpener of pure Mg would be a rather soft one, no?  :)

If it has a high Mg content (~90% as you imply) maybe it could still be used for some reductions?


  • Guest
Possible Mg from pencil sharpeners
« Reply #8 on: July 26, 2003, 06:05:00 AM »
How about those fire starting devices they sell in the camping supply departments of department stores. One is to scrape or whittle magnesium off a block. Attached to the block is a flint-like rod, with which one can strike sparks.
In my part of the country these retail for about $5, and seem to contain a hefty number of grams of magnesium. Don't know how pure.


  • Guest
Thank you chimimanie ;-D
« Reply #9 on: July 26, 2003, 07:58:00 AM »
As you may or may not know, the humble metal pencil sharpener (circled below) is made of Magnesium. In case you're wondering, the thing it is sat apon is a spray-painted, sledgehammered old computer case...

Magnesium Pencil Sharpeners



  • Guest
« Reply #10 on: July 26, 2003, 03:01:00 PM »
I weighted a pencil sharpener, without the blades (made of steel), it is near 7g, or a little more than 250 mmol  :) .

Another source for US bee could bee the Flameless Ration Heater used by army.

sadly it is mixed with iron :( ...


Flame test is positive, i heated it with a burner, then it melted and white sparks came, finally the whole mass became shining white, beautiful. It burned alone for a few minutes, and now it is white MgO powder...


  • Guest
« Reply #11 on: July 26, 2003, 03:03:00 PM »

How about those fire starting devices they sell in the camping supply departments of department stores.

These fire starters are made from ordinary magnesium metal, and thus aren't pure enough for the Grignard reaction  ;)  Only magnesium metal of the highest grade can be used, such as sublimed metal, or that purified by electro refining  :)  It's very doubtful if those pencil sharpeners or that heating unit are made from such high purity magnesium, it's usually quite expensive compared to ordinary magnesium  ::)


  • Guest
Well, I guess all of those sources of ...
« Reply #12 on: July 26, 2003, 03:38:00 PM »
Well, I guess all of those sources of magnesium wouldn't be adequate for performing Grignard reactions, but they could still be used for hydrogen production, such as if someone was going to do some catalytic hydrogenation.

Mg + 2H2O -delta T-> Mg(OH)2 + H2

I think that this reaction should be the preferred method of H2 production, for several reasons.

1. The reaction can be controlled merely by adjusting heat.

2. It's cheaper than most metal/acid procedures, perhaps with the exception of Al/acid.  But we'll get to that later.  And the grade of Mg required for this is much easier to get than say Zn dust.

3. Al/acid is a cheap and easy way to produce hydrogen, but it's a very hard reaction to control.  And not only that, if the catalytic reduction you were doing was pH sensitive, then this definately wouldn't be the method of choice.  Because contrary to what some bees around here say, the addition of aqueous HCl to Al produces HCl gas along with the hydrogen.


  • Guest
Don't forget you could pass the H2/Acid gas...
« Reply #13 on: July 27, 2003, 06:03:00 AM »
Don't forget you could pass the H2/Acid gas mixture through a wash bottle - or what about the old Al/NaOH instead, with controlled addition.
It just seems to me that the Mg/H2O is a slightly less viable prospect for hydrogen production in this instance unless you have a really cheap supply of metal pencil sharpeners. Also pencil sharpeners don't have the largest of surface areas for a given mass.

There must be a better use for this grade of magnesium shurely.


  • Guest
I'm not really saying that the pencil ...
« Reply #14 on: July 28, 2003, 12:18:00 AM »
I'm not really saying that the pencil sharpeners  should be used as a source of magnesium for H2 prodduction, I'm just saying that for Mg to be able to be used in a Grignard, it has to be pretty fuckin' pure, or at least purer than most Mg found OTC.  But there is a lot of Mg metal that can be found OTC with sufficient purity to be used for H2 production.