From Newsgroup: rec.crafts.metalworking

Success a few days ago, after more than a month of "chafing", trying
to find the right thing to do:

http://weldsmith.co.uk/tech/minerals/250709_sa_rm10gran/250709_sa_rm10gran.html Particle Size Analysis on rod-mill "mis-grind" of 10mm granite chippings

There was no recognisable connection between "You just ..." and the
path when you try it.

I got several minutes of detailed discussion with someone from an area
not known for conversation who is an acknowledged expert on minerals processing.
Many of you will know this - sieving:
* if you start wet sieving, you have to stay wet sieving
* likewise dry sieving
Etc.

Question - have any of you used "air elutriation"?
Given you do get some "very fines" when grinding rock and ores which
on several grounds would be good to separate first...
I sketched a device with a zig-zag for downward "clattering" material
flow / upward air flow.
The search-engine seeing my searches served-up ads. for exactly such
device - but much bigger and during recycling shredded plastic.
The idea is - where the problem is fine silica dust floating around in
the air - which is a health issue - you use the "fines floating in
air" to advantage and separate them that way.
How you'd recover the floating-in=air fines? Electrostatic
precipitation? If so, how would you drive it? There has to be a
neater solution than running a var de Graaf generator...

Anyway, gathered my thoughts after that campaign

http://weldsmith.co.uk/tech/minerals/250713_reffeed-mill-psa/250713_reffeed-mill-psa.html
"Significance : reference-feed=>mill=>particle-size-analysis"


Regards,
Rich S
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: rec.crafts.metalworking

"Richard Smith" wrote in message news:m14ivfnpw6.fsf@void.com...
...

What you are doing is very important in the dry food, pharmaceutical and laundry detergent industries. The difficulty may be getting them to reveal their methods.

Another way to separate by size for analysis is by settling time in a
viscous liquid like olive oil. Diamond dust is separated by size for lapping that way, and a topsoil sample from sand.

https://en.wikipedia.org/wiki/Vertical_roller_mill

--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: rec.crafts.metalworking

"Richard Smith" wrote in message news:m1ecuj0wma.fsf@void.com...

This si the "air-elutriation" idea as best as can ASCII-sketch

That is how goose down is separated into grades for high performance winter outerwear.

https://www.kunc.org/business/2015-12-29/frostline-kits-may-be-history-but-the-diy-gear-is-still-beloved-in-colorado

I made many of their kits as-is and then began customizing them for higher performance. Eventually I could camp warm in a blizzard with about 5 Lbs of tent and sleeping bag. While there on a hunting trip I visited the factory. They cut the kit pieces in batches of 500 on the rotary tables with a knife blade in a saber saw, crawling on their knees over the cloth and patterns.
The first step of assembling a kit was melting the edges of the nylon cloth
by passing it by a candle flame, otherwise it would unravel, especially in
the laundry. With practice that step went quickly. We were the free labor
that enabled the savings. A hot knife would have stuck the layers together.

I had learned to join thin polyethylene sheets on a hot light bulb to make
hot air and hydrogen balloons and UFOs that I and others flew over Exeter
NH. I had no part in the famous one though I had made smaller hot air models of tissue paper with flame coloring such as road flare contents. A few cells taken from a 9V battery could briefly power blinking Christmas bulbs. The instructions and patterns for balloon panels (gores) had been printed in
Boy's Life magazine. At low angles the otherwise nearly invisible clear plastic reflected the sun and clouds like calm water or a windshield and may have looked like a shiny flying saucer. The most saucer-like for their flat tops were dry cleaners bag parachutes with minimal ballast that rose on warm moist thermals from our field.

https://en.wikipedia.org/wiki/Exeter_incident

It was near the house of the Physics professor from Phillips Exeter Academy and my guess is that his students were trying to impress him. Toy hot air balloons have little extra lift until their fuel burns down, so unlike
Helium balloons they meander horizontally in ground turbulence before
rising.

One evening I saw someone else's UFO drifting past the stars, like but not quite right for a plane, more a candle. I triangulated its altitude by
pacing perpendicular to its path until it was at 45 degrees, it was only 100 feet up. Just looking at it without a reference it could have been at any distance and size.

Eyewitness testimony on TWA 800 shows how the eye misjudges the unfamiliar. The reported antiaircraft missiles were actually the flaming fuselage after the center fuel tank exploded and blew off the front end, unbalancing the
rest into a steep climb.

--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: rec.crafts.metalworking

Carl <carl.ijamesXX@YYverizon.net> writes:

On 7/14/25 4:22 AM, Richard Smith wrote:

Question - have any of you used "air elutriation"?
Given you do get some "very fines" when grinding rock and ores which
on several grounds would be good to separate first...
I sketched a device with a zig-zag for downward "clattering" material
flow / upward air flow.
The search-engine seeing my searches served-up ads. for exactly such
device - but much bigger and during recycling shredded plastic.
The idea is - where the problem is fine silica dust floating around in
the air - which is a health issue - you use the "fines floating in
air" to advantage and separate them that way.
How you'd recover the floating-in=air fines? Electrostatic
precipitation? If so, how would you drive it? There has to be a
neater solution than running a var de Graaf generator...

No experience with this but since you have the dust already entrained
in flowing air would a cyclonic dust collector like used in
woodworking shops be effective for this? Even as a first stage if it
dealt with a significant mass fraction it would make later stages of filtration that much cheaper and easier.

Thanks for this idea for recovery of the "dust" which is actually part
of the sample.

Yes, take what wins you can as soon as you can.
You remind me of these "cyclone" machines in woodworking shops.

The "very very fines" which form a "smoke" are unlikely to contain
values? Which would be denser and be cycloned-out into another
fraction? So if the "normal density" "very very fines" end up in a
filter whose "with dust weight" - "original weight" is taken to be the
mass of those very very fines, that would work. Unlikely to need to
recover them.

I will look into this.
I can start with using a "wet&dry" workshop vac. to start "concept" experiments. Mine you can connect the hose to the "blow" side, which
should help.
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: rec.crafts.metalworking

"Richard Smith" wrote in message news:m1freyj9zg.fsf@void.com...

I will look into this.
I can start with using a "wet&dry" workshop vac. to start "concept" experiments. Mine you can connect the hose to the "blow" side, which
should help.

---------------------------

You can measure the pressure rise or drop related to air flow with a clear tube containing colored water. If sloped at six degrees the height of water
is amplified 10x. As long as your setup gives repeatable numbers it needn't
be accurate, you can compare readings to results.

--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: rec.crafts.metalworking

"Jim Wilkins" <muratlanne@gmail.com> writes:

"Richard Smith" wrote in message news:m14ivfnpw6.fsf@void.com...
...

What you are doing is very important in the dry food, pharmaceutical
and laundry detergent industries. The difficulty may be getting them
to reveal their methods.

Another way to separate by size for analysis is by settling time in a
viscous liquid like olive oil. Diamond dust is separated by size for
lapping that way, and a topsoil sample from sand.

https://en.wikipedia.org/wiki/Vertical_roller_mill

"Richard Smith" wrote in message news:m14ivfnpw6.fsf@void.com...
...

What you are doing is very important in the dry food, pharmaceutical
and laundry detergent industries. The difficulty may be getting them
to reveal their methods.

Another way to separate by size for analysis is by settling time in a
viscous liquid like olive oil. Diamond dust is separated by size for
lapping that way, and a topsoil sample from sand.

https://en.wikipedia.org/wiki/Vertical_roller_mill

Hi there

Thanks for affirming words.

Separation by falling through fluid column
- on a trivial level there is a "cheat" (it isn't actually) you can do
when manually wet sieving.

Because the sieve "blinds" with just above sieve sze particles - makes
it a lot quicker to deal with those last.
If you stir you sample mix in the water, if you leave it for a few
seconds, if you ladle from near the surface you will catch only fines,
which will drop straight through the sieve.
You can ladle into the sieve shorter and shorter times after stirring,
to get coarser and courser particles.
Finally you have the larger "drops straight to the bottom" sizes -
with no "clay" and/or other fines - so the tendency to bind on/in the
sieve is much much less.
Hence "blinding" of the sieve only happens at the end, and then with
nothing left to bind thus reducing the tendency to "blind".

That was a point my not-notably-talkative contact nodded about with a
general "you are well on the way" body-language.


This si the "air-elutriation" idea as best as can ASCII-sketch


^
^ air-flow
^
\ \
/ /
\ \
/ /
\ \
/ /
\ \
/ /
^
^ air-flow
^

--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: rec.crafts.metalworking

On 7/15/25 1:31 AM, Richard Smith wrote:

Carl <carl.ijamesXX@YYverizon.net> writes:

On 7/14/25 4:22 AM, Richard Smith wrote:

Question - have any of you used "air elutriation"?
Given you do get some "very fines" when grinding rock and ores which
on several grounds would be good to separate first...
I sketched a device with a zig-zag for downward "clattering" material
flow / upward air flow.
The search-engine seeing my searches served-up ads. for exactly such
device - but much bigger and during recycling shredded plastic.
The idea is - where the problem is fine silica dust floating around in
the air - which is a health issue - you use the "fines floating in
air" to advantage and separate them that way.
How you'd recover the floating-in=air fines? Electrostatic
precipitation? If so, how would you drive it? There has to be a
neater solution than running a var de Graaf generator...

No experience with this but since you have the dust already entrained
in flowing air would a cyclonic dust collector like used in
woodworking shops be effective for this? Even as a first stage if it
dealt with a significant mass fraction it would make later stages of
filtration that much cheaper and easier.

Thanks for this idea for recovery of the "dust" which is actually part
of the sample.

Yes, take what wins you can as soon as you can.
You remind me of these "cyclone" machines in woodworking shops.

The "very very fines" which form a "smoke" are unlikely to contain
values? Which would be denser and be cycloned-out into another
fraction? So if the "normal density" "very very fines" end up in a
filter whose "with dust weight" - "original weight" is taken to be the
mass of those very very fines, that would work. Unlikely to need to
recover them.

I will look into this.
I can start with using a "wet&dry" workshop vac. to start "concept" experiments. Mine you can connect the hose to the "blow" side, which
should help.

I know YOU want the fines which hopefully a cyclonic filter can capture
a signifcant portion of, but everyone else wants the final exhaust air
to be dust free, especially free of those pesky sub-PM10 particles which
don't play nice with lungs. I thought a cyclonic filter might be a
win-win :-). If crude sieving is useful and you build it yourself you
could have two stages of cyclones, the first a "bad" one to only get the
big chunks, then a "good" one to get the mid-range down to some target
fine size, and then a normal flow-through paper air filter element to
get the really fine stuff before exhausting the air.

There are lots of plans and videos online to build your own to go on top
of a 5 gallon bucket, along with molded plastic models.
--
Regards,
Carl (who mostly lurks and learns)
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: rec.crafts.metalworking

On 7/14/2025 1:22 AM, Richard Smith wrote:

Success a few days ago, after more than a month of "chafing", trying
to find the right thing to do:

http://weldsmith.co.uk/tech/minerals/250709_sa_rm10gran/250709_sa_rm10gran.html
Particle Size Analysis on rod-mill "mis-grind" of 10mm granite chippings

There was no recognisable connection between "You just ..." and the
path when you try it.

I got several minutes of detailed discussion with someone from an area
not known for conversation who is an acknowledged expert on minerals processing.
Many of you will know this - sieving:
* if you start wet sieving, you have to stay wet sieving
* likewise dry sieving
Etc.

I must misunderstand. I thought sieving was just for grading by size.
Having done a little placer mining I can well understand why once you
start processing wet you need to keep processing wet. Even a long
period of time may not be adequate to dry material in a high humidity environment.

Question - have any of you used "air elutriation"?

As defined, not exactly. I have used a dry washer, which is
functionally a course sieve followed by a "sluice" using air and
vibration as the means to keep material moving instead of water. Since
our only net desired material was gold I noticed that there was less
ultra fine "flour" gold in material handled by dry washer as opposed to material run through a proper sluice with water. In either case obvious nuggets were picked out, and final processing was wet panned by hand,
where small and tiny nuggets were picked out, and then finally that run through a spiral concentrater if panning indicate enough fines to be
worth the effort.

Given you do get some "very fines" when grinding rock and ores which
on several grounds would be good to separate first...
I sketched a device with a zig-zag for downward "clattering" material
flow / upward air flow.

I've seen a few things used for ridges on dry washer separators.
Expanded metal which I didn't think worked very well was one. Another
was catch angle pieces of metal straight across the bed resting on what
looked like a course cordura mat that was easily permeable to air. The
bars where typically part of an assembly, that was hinged on pins at one
end to allow for easy clearing of captures into a container. When
hinged down it pinch the mat or carpet material. I've seen similar mat material used behind the same catch angle metal bars on wet sluices.
--
Bob La Londe
CNC Molds N Stuff

--
This email has been checked for viruses by AVG antivirus software.
www.avg.com
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: rec.crafts.metalworking

"Richard Smith" wrote in message news:m1freyj9zg.fsf@void.com...

Thanks for this idea for recovery of the "dust" which is actually part
of the sample.
...
The "very very fines" which form a "smoke" are unlikely to contain
values? Which would be denser and be cycloned-out into another
fraction? So if the "normal density" "very very fines" end up in a
filter whose "with dust weight" - "original weight" is taken to be the
mass of those very very fines, that would work. Unlikely to need to
recover them.
...
---------------------------------

In chemistry practice such filtrates are collected on filter paper which is either very low ash when burned, or the ash weight percentage has been measured. The paper and filtrate is burned out in a previously weighed crucible and the crucible and residue weighed without trying to scrape it
out. The residue can be analyzed to see if it contains metals, perhaps with the blowpipe and charcoal.

https://www.coleparmer.com/i/cole-parmer-low-form-crucible-with-cover-porcelain-50-ml/6310046?
"withstands temperatures to 2102#F (1150#C)"

--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: rec.crafts.metalworking

Carl <carl.ijamesXX@YYverizon.net> writes:

I know YOU want the fines which hopefully a cyclonic filter can
capture a signifcant portion of, but everyone else wants the final
exhaust air to be dust free, especially free of those pesky sub-PM10 particles which don't play nice with lungs. I thought a cyclonic
filter might be a win-win :-). If crude sieving is useful and you
build it yourself you could have two stages of cyclones, the first a
"bad" one to only get the big chunks, then a "good" one to get the
mid-range down to some target fine size, and then a normal
flow-through paper air filter element to get the really fine stuff
before exhausting the air.

There are lots of plans and videos online to build your own to go on
top of a 5 gallon bucket, along with molded plastic models.

Thanks
--- Synchronet 3.21a-Linux NewsLink 1.2

From Newsgroup: rec.crafts.metalworking

Thanks everyone.
Good ideas here, and concepts opened-up here.
--- Synchronet 3.21a-Linux NewsLink 1.2