To finely grind crystaline powders I have been using various types and sizes of mortar and pestle,
which work well enough for my purposes,
but can be rather tedious and tiring.
I would like an electrically powered powdering device,
for quantities in the 10's of grammes range.
I guess that a coffee grinder would suffice,
a spice mill may be ok.
What gives the finest powder at low cost?
Any suggestions?
(preferably based on experience) B(a)P - 3-1-2022 at 00:35
I find a coffee grinder works well, you can get a very fine powder, but decontaminating them between chemicals is a bit of a challenge. If cross
contamination is potentially an issue I go with mortar and pestle. Fyndium - 3-1-2022 at 01:37
Ball mill.
You can get rotary tumblers from eBay and others for 50$. They come with SS ball bearings, which will grind down any organic substance in minutes down
to fine powder.
They also come in handy when you need to mix, grind or polish something.
I've been running one of those transparent polycarbonate drums for a hundred hours with aluminum oxide grit for polishing and it only has some little
surface scratching. Get a big carton box and line it with sound damping material and you can run it without noise issues.
EDIT: Ah, in order of 10's of grams. Pestle and mortar it is, then.macckone - 3-1-2022 at 23:13
coffee grinder is probably most practical for 10s of grams.
most spice mills are not 'fine' grinding.
look for one that says it will do espresso which is a very fine grind.
As others have stated contamination is an issue.
You can get flour mills as well in small varieties both hand crank and electric.
Most are stainless steel but some are cast iron or aluminum (avoid aluminum).
A few even use granite for the grinding surfaces but I think those are overpriced.
If you design your own ball mill, you can use what ever size bottle and grinding media suits the load and you can designate a chemical for each
container.
The biggest problem with designing your own is finding a motor that is slow enough and will last.
The stock motors on tumblers in the $50 range wear out rather fast (couple of months).ManyInterests - 4-1-2022 at 00:19
Quote:
I find a coffee grinder works well, you can get a very fine powder, but decontaminating them between chemicals is a bit of a challenge. If cross
contamination is potentially an issue I go with mortar and pestle.
I second that. Though the only thing I've ground up in my coffee grinder is potassium nitrate, because of how non-toxic it is and how soluble in water
it is, making it easy to wash away.
One suggestion I would have is to look at 2nd hand stores were people dump their old clothes and electronics. I got my fan that i use for a makeshift
fumehood and a few other electronics from there for next to nothing. It's a potluck, however and you may not find exactly what you're looking for, but
when you do, they tend to be worth it. Sulaiman - 4-1-2022 at 06:43
I think I'll look for a used coffee grinder as suggested above
and use mortar and pestle until then.
ThanksFantasma4500 - 5-2-2022 at 21:14
when processing materials in a coffee grinder, you wanna dry it out well first, if theres moist lumps in it the grinder just clogs up
the easiest to fix this, even very hard lumps is to take a glass bottle with concave bottom, press firmly down on a lump and go in circular motions,
they usually break within half a motion even rather hard lumps
then you wanna sift this into a steel pot and dry it out a bit more and finally coffee grind it
i believe if you grind for long enough you get what you want, otherwise you may have to construct a sifting machine, or manually sift through
stainless steel mesh sieves- rinse&repeat. with this method its possible to produce pitch black metal powdersDr.Bob - 7-2-2022 at 08:40
If you really want to pulverize some large samples then go to the energetics thread. There are lots of things there that can do it. :-)
But I would agree with used coffee grinder and ball mills. Both have their places. A really big mortar and pestle can do a lot however, I have
ground up many inorganics that way.
Flour Mill
MadHatter - 7-2-2022 at 11:45
This is my best grinder yet. If you buy 1 of these make sure it 's stainless steel.
They cost more than aluminum or cast iron models. Mine is a hand crank model,
easy to disassemble and clean. I had a model made of cast iron but it rusted out
after grinding oxidizers in it. Aluminum I wouldn't trust with many compounds -
(per)chlorates in particular. I agree with macckone on aluminum. I use to have a
ball mill(rock tumbler) but it was very slow. I use the grinder if I need a lot of
powder. Other than that it's the mortar and pestle.
