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Bert
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It is not a bad thing to suggest an inexperienced amateur choose a lower friction method from the spectrum of those possible.
Someone just starting out and mixing a few grams of a (new to them) EM might use a natural bristle paint brush to stir and a paper to diaper. Probably
won't have a friction issue, can judge degree of mixing by color-
If you have some experience and a feel for the sensitivity of a mixture, you might choose to use ingredients previously screened separately through 40
mesh, briefly diaper mix them on a large sheet of paper and then run the full mix through a 20 mesh screen into a receiver three times.
If you were REALLY experienced, and had the barrier space and equipment- You could dump the chemicals into a "Y" mixer and run that remotely for
however long your manufacturing experience had shown to be adequate.
Rapopart’s Rules for critical commentary:
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4. Only then are you permitted to say so much as a word of rebuttal or criticism.
Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
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ecos
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Hmm , most of the caps i found were made of rubber and as i read here it still won't help a lot if spark happens !
I think plastic bags would work ? I think it is more weaker than rubber and would cause deflagration instead of explosion
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PHILOU Zrealone
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Quote: Originally posted by hissingnoise  | | Quote: | | Afterwards you may mix two powders (fuel(s) and oxydizer(s) (or unbalanced Fuel (+) Oxydizer (-) and unbalanced Oxydizer (+) and Fuel (-)) by the
Rolling paper method. |
Diapering PHILOU? Jeez, it's a propellant ─ not a fucking primary?
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Some mixes are very prone to initiation...
1°)I had the case with a big spark-flash in my electric coffee grinder (11000 rpm) by grinding dry NH4NO3 prills...due to the friction some of the
inox had intimately mixed with the NH4NO3...resulting in a bright flash and spark inside the grinder. Hopefully it was just NH4NO3 and only a very
tiny % of metalic dust...thus highly unbalanced.
2°)In the beginning I used coffee grinding of my black powder (KNO3/S/C) but once I did it on a small quantity to test for ultrafine BP and it took
fire in less than 3 seconds...propelling the top of the grinder away in a big fire ball...the quantity was low like one coffee spoon and the mixing
was not 100% acheived.
3°)Afterwards I was working with much more powerfull mixes involving chlorates...so from now on with a new coffee grinder I remain on the safe side
even if the mix does seem safe...I don't want to take the 1 on 1000 chances for the mishaps.
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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MineMan
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Coffee Grinder
I second that. I was once grinding magnesium in a coffee grinder and saw about a 1 inch diameter flash. Decided to stop right there.
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ecos
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I found a nut in the same size of the glass pall i presented before , The Nut is 3.2 times heavier than the glass ball and almost the same volume.
I put the glass ball over the nut to present the idea :
the nut is 69 grams. would that size fit well or I need a smaller nut ?
I found a smaller one but it was 21 grams weight. the larger nut is 121 gram but really big !
any suggestions ?
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hissingnoise
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You need non-sparking antimony-hardened lead balls if you're intent on grinding ingitible mixtures!
Steel and ceramic media will spark and are dangerous ─ glass is essentially useless . . .
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ecos
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Thx for the link and the info.
I plan to grind Al only in the current time. I would use 6" X 8 " jar. I need to fill 50% of it with media "milling balls". Therefore I would need
large amount of balls.
the webiste offers 2.5lb of Hardened Lead for $25. of course I would need more, I still need to pay for shipping cost !
I think metal will not spark till it become so hot or hit with a strong force.
I found some videos on youtube that use similar nuts as media :
https://youtu.be/nA94uHqUQvg?
picture for the media :
[Edited on 1-4-2015 by ecos]
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hissingnoise
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| Quote: | | I plan to grind Al only in the current time. I would use 6" X 8 " jar. I need to fill 50% of it with media "milling balls". Therefore I would need
large amount of balls. |
A good Al flake can be produced from light Al foil using lead media, given time!
Steel balls are too prone to sparking in combination with Al and steel nuts that might contain traces of Fe3O4 on their threads
even more so!
In an air-tight mill-jar freshly exposed Al will use up the contained oxygen as milling progresses so that when the run is complete you have Al which
is potentially pyrophoric.
If the jar-cap is removed suddenly the inrush of fresh oxygen can cause ignition of the Al which will result in a quick, very hot and long flare ─
and for this reason the cap should be removed slowly so that air may be allowed seep in, rather than rush in!
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ecos
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| Quote: Originally posted by hissingnoise | | Quote: | | I plan to grind Al only in the current time. I would use 6" X 8 " jar. I need to fill 50% of it with media "milling balls". Therefore I would need
large amount of balls. |
A good Al flake can be produced from light Al foil using lead media, given time!
Steel balls are too prone to sparking in combination with Al and steel nuts that might contain traces of Fe3O4 on their threads
even more so!
In an air-tight mill-jar freshly exposed Al will use up the contained oxygen as milling progresses so that when the run is complete you have Al which
is potentially pyrophoric.
If the jar-cap is removed suddenly the inrush of fresh oxygen can cause ignition of the Al which will result in a quick, very hot and long flare ─
and for this reason the cap should be removed slowly so that air may be allowed seep in, rather than rush in!
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wouldnt the 5% carbon i added to Al prevent the oxidation?
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hissingnoise
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When Al is first exposed to oxygen, oxidation occurs and the oxide forms a thin surface-layer!
It's worth bearing in mind, and no, it isn't preventable by ordinary means . . .
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Hennig Brand
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Not to interrupt the ball mill talk, but I found a couple of igniter compositions that I thought might be interesting. The following is a copy/paste
from, "A MANUAL FOR PYROTECHNIC DESIGN, DEVELOPMENT AND QUALIFICATION", which is a NASA Memorandum report from 1995.
TABLE V.- Properties of Boron/Potassium Nitrate (B/KN03)
- Gas generating material
- Burn rate minimally affected by ambient pressure
- High-temperature combustion, hot particles
- Thermally stable
- Vacuum stable
- Long shelf life
- Application as rocket motor igniter and gas generator
References 11 and 12
TABLE V1.- Properties of NASA Standard Initiator (NSI) Mix Zirconium/potassium perchlorate (Zr/KCl04)
- Burn rate of hundreds of feet per second
- Rapid pressure rise Output = hot particles, little gas
- Electrostatically sensitive Good hotwire initiation interface
- Thermally and vacuum stable
- Long shelf life
- Application as an initiator and as an energy source
Edit:
I see where Bert has already mentioned the Boron/Nitrate igniter mix in another thread.
| Quote: Originally posted by Bert |
Use something that makes a hot flame, and/or something that leaves hot molten dross. Not something normally used to provide shock!
Elemental Boron and Potassium nitrate is a good high temperature gas/flame igniter.
Elemental Silicon and Potassium nitrate will also burn hot, and leave white hot glass slag stuck to the surrounding areas, which will continue to
transfer heat to a pyrotechnic fuel for a good long time-
Black Copper oxide/Aluminum thermite is a popular igniter for high power rocketry amateurs as well-
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[Edited on 3-4-2015 by Hennig Brand]
"A risk-free world is a very dull world, one from which we are apt to learn little of consequence." -Geerat Vermeij
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Bert
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I have made & used the Boron/Potassium nitrate mix, it's a reasonably well mannered and effective ignition mixture from personal experience. And
can even be ordered ready made from Firefox, shipped as a flammable solid. True enough shipping description, if a bit understated.
I have learned to respect the sensitivity of mixtures containing fine Zr powder, they are NOT overstating the sensitivity to ESD in use with typical
pyrotechnic oxidizers. Best reserved for applications requiring this, Ti is a bit more forgiving in handling from my personal experience- Also cheaper
& more available. Finely powdered Zr metal by itself is not to be trifled with either.
Opening a jar of very fine Zr, supposedly packed safely with sufficient water, using a stainless steel lab scoop to dig out a few grams... And
discovering it settled to the point of excluding sufficient water from the lower layer. By having the stuff ignite in your face from steel/Zr friction
on scooping it out.
Ah memories... We will enjoy them.
Rapopart’s Rules for critical commentary:
1. Attempt to re-express your target’s position so clearly, vividly and fairly that your target says: “Thanks, I wish I’d thought of putting it
that way.”
2. List any points of agreement (especially if they are not matters of general or widespread agreement).
3. Mention anything you have learned from your target.
4. Only then are you permitted to say so much as a word of rebuttal or criticism.
Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
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Hennig Brand
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Boron is something that I have seen many times sitting on drugstore shelves as well as agricultural and garden supply outlets IIRC. Bert, can the
B/KNO3 mix be bound with a bit of NC lacquer and easily ignited by low voltage bridge wire?
"A risk-free world is a very dull world, one from which we are apt to learn little of consequence." -Geerat Vermeij
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Bert
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It would not be the fastest /most sensitive first fire coating, but will work if the bridge wire is robust enough. Crude igniters made by taking a
piece of multi strand 18ga insulated copper hook up wire, stripping approx. 3/16" and cutting away all but one strand (the high resistance element!)
and bending double at the stripped part, then dipping in pyrogen have worked with the composition. It is not the kind of device that is reliable in
series shots, or lights off in 10 micro seconds- But it's easy to make.
(Edit) You have probably seen BORIC ACID and/or BORAX in the places you mention. Elemental Boron is not a common OTC chemical-
[Edited on 6-4-2015 by Bert]
Rapopart’s Rules for critical commentary:
1. Attempt to re-express your target’s position so clearly, vividly and fairly that your target says: “Thanks, I wish I’d thought of putting it
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3. Mention anything you have learned from your target.
4. Only then are you permitted to say so much as a word of rebuttal or criticism.
Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
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Hennig Brand
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Ah yes, now that you mention it that is what I think I have seen, not boron. I have a good memory, it's just awful short. 
Here are a couple of YouTube videos that show how elemental boron can be made starting with boric acid or borax, producing B2O3 which is reduced in a
thermite type reaction to produce elemental boron the same way silicon dioxide can be reduced to produce silicon. There are many more videos also.
https://www.youtube.com/watch?v=0QBCyOrjR2o
https://www.youtube.com/watch?v=niTY6ImAFyk
From Wiki:
"Boron trioxide is produced by treating borax with sulfuric acid in a fusion furnace. At temperatures above 750 °C, the molten boron oxide layer
separates out from sodium sulfate. It is then decanted, cooled and obtained in 96–97% purity.[2]
Another method is heating boric acid above ~300 °C. Boric acid will initially decompose into water steam and metaboric acid (HBO2) at around 170 °C,
and further heating above 300 °C will produce more steam and boron trioxide. The reactions are:
H3BO3 → HBO2 + H2O2
HBO2 → B2O3 + H2O
Boric acid goes to anhydrous microcrystalline B2O3 in a heated fluidized bed.[8] Carefully controlled heating rate avoids gumming as water evolves.
Molten boron oxide attacks silicates. Internally graphitized tubes via acetylene thermal decomposition are passivated."
"The earliest routes to elemental boron involved reduction of boric oxide with metals such as magnesium or aluminium. However the product is almost
always contaminated with metal borides. Pure boron can be prepared by reducing volatile boron halides with hydrogen at high temperatures. Ultrapure
boron for use in the semiconductor industry is produced by the decomposition of diborane at high temperatures and then further purified with the zone
melting or Czochralski processes.[22]"
[Edited on 7-4-2015 by Hennig Brand]
"A risk-free world is a very dull world, one from which we are apt to learn little of consequence." -Geerat Vermeij
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Bert
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Goldschmidt reaction product should be serviceable for a pyrotechnic hot prime composition in display fireworks, probably not advised for critical
applications such as gas less delay elements though.
The grades of Boron and Silicon used in pyrotechnic igniters are NOT semiconductor grade- Way too expensive. I recall buying powdered Silicon from
Skylighter claimed at 80% purity, years ago. No idea what the Boron used in the ignition granules is, but really pure Boron would be far too expensive
to sell in this mixture at the product's advertised price.
Rapopart’s Rules for critical commentary:
1. Attempt to re-express your target’s position so clearly, vividly and fairly that your target says: “Thanks, I wish I’d thought of putting it
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3. Mention anything you have learned from your target.
4. Only then are you permitted to say so much as a word of rebuttal or criticism.
Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
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PHILOU Zrealone
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Boron nitride (BN) might also be a good fuel...with regard to its high positive heat of formation.
Apprently it can be done from B2O3 and NH3 or NH2-CO-NH2 and despite its positive H°f it is quite stable up to 1000°C and above 
PH Z (PHILOU Zrealone)
"Physic is all what never works; Chemistry is all what stinks and explodes!"-"Life that deadly disease, sexually transmitted."(W.Allen)
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ecos
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For the ball mill, I have to run it for 7-11 days to have a very fine AL powder
it is a time/power consuming process !
I think the motor would burn due to the long run-time!, wouldn't it?
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hissingnoise
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| Quote: | | I think the motor would burn due to the long run-time!, wouldn't it? |
Heat sink ─ cooling fan ─ thermal cut-out . . .
A thermal cut-out is the most reliable!
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Bert
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I have a couple of ball mills. They were made to be rock polishing tumblers- This process usually runs for weeks, the motors were specified to take
that kind of use. I have had belts wear out, bearings wear out or become corroded, but not burned out a motor yet.
If you make your own mill, pick a motor suitable for the load- A thermal cutout is a good safety feature too.
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4. Only then are you permitted to say so much as a word of rebuttal or criticism.
Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
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ecos
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Ok , I am planning to use pulleys to get the desired RPM.
it should be something like that (just skip the ratios on the figure):
pulley A is driver pulley. pulley D is the mill jar.
This mean the motor would not have any electronic speed control. it will run with maximum speed and the pulleys will take care of speed control due to
the diameter ratios.
any advice before I start ?
[Edited on 6-5-2015 by ecos]
[Edited on 6-5-2015 by ecos]
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ecos
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Hi All,
I am in the last state of finishing my ball mill.I couldn't find any steal/lead balls nearby. I decided to use the 1" steal Nuts. I think Nuts have
more vacuum in its volume compared to balls.
I need to calculate my material charge percentage according to this statement :
do i need to add excess amount of Al to compensate the full empty space inside the Nuts or just a certain ratio ?
[Edited on 3-6-2015 by ecos]
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ecos
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The nuts are jumping inside the milling jar in a funny way, i think it doesn't work well!!
I prefer now to buy the milling media from the internet ! , any suggestions for good price source and acceptable material?
I made some search on amazon and ebay :
These are lead balls , the amount is nice but the size is not mentioned
http://www.ebay.com/itm/Lead-Balls-Milling-Media-5-lbs-12-an...
sounds good but price is an issue for 6" X 8" milling jar :
http://www.ebay.com/itm/Ball-Mill-Grinding-Media-Yittrium-St...
also
http://www.ebay.com/itm/Ceramic-Balls-Cylpebs-White-Milling-...
[Edited on 3-9-2015 by ecos]
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Bert
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I have used Coors ceramic milling media for grinding pyrotechnic chemicals, particularly oxidizers such as Barium nitrate that like to cake up rock
hard (never a fuel/oxidizer mixture).
http://m.ebay.com/sch/i.html?_nkw=Ball+mill+media&isNewK...
400 series stainless would be a good choice for milling Aluminum to powder.
The Tungsten carbide balls certainly look pretty- At 35.00 US$ EACH for a 20mm ball, I don't think I will be finding out how well they work!
Rapopart’s Rules for critical commentary:
1. Attempt to re-express your target’s position so clearly, vividly and fairly that your target says: “Thanks, I wish I’d thought of putting it
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2. List any points of agreement (especially if they are not matters of general or widespread agreement).
3. Mention anything you have learned from your target.
4. Only then are you permitted to say so much as a word of rebuttal or criticism.
Anatol Rapoport was a Russian-born American mathematical psychologist (1911-2007).
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greenlight
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I've never got around to buying any actual media from the internet.
What are you going to be using your mill to make?
I only mill black powder in mine and have found that round fishing sinkers do fine for this purpose. Plus they are 99% non-sparking.
I have made a fair few batches with them and haven't had any trouble.
The only use for an atomic bomb is to keep somebody else from using one.
George Wald
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