[Rockhounds] Elutriation

[pmodreski at aol.com]

Kreigh & Jim, & the List,

Just wanted to say, I tried searching on our USGS website to see if I 
could locate a report or paper on this, but have not had any luck.  I 
also tried looking in the older, printed volumes we have listing and 
giving subject indices to USGS published reports (I thought the 
old-style printed index might find it for me, when the online searching 
failed), one volume for pre-1962 and one for 1962-1970, but I don't see 
anything resembling what you are looking for.

I would think that this technique,  requiring seperatory funnels & 
U-tubes with stopcocks (not that you couldn't improvise with simpler 
equipment), might work for relatively small quantity samples of mineral 
grains, but might not be too workable for separating large quantities 
of material (of silicon carbide grit, such as Kreigh is talking about), 
as it would be likely to clog the tubes or valves.

Pete



-----Original Message-----
From: Kreigh Tomaszewski <Kreigh at tomaszewski.net>
To: Rockhounds at drizzle.com: A mailing list for rock and gem collectors 
<rockhounds at lists.drizzle.com>
Sent: Tue, 6 Jan 2009 9:34 pm
Subject: Re: [Rockhounds] Elutriation


Jim, 
 
Your description was clear enough I'm sure I could build something that 
worked, but I would still like to see the paper as I am sure it would 
save me a lot of time experimenting to make things work right. 
 
Kreigh 
 
 


On Tuesday, Jan 6, 2009, at 22:35 America/Detroit, Jim Murowchick 
wrote: 
 
> Hi Kreigh. 
> 
> I'm still looking for the paper--it's one of those that I keep > 
finding 
> when I don't need it, but when I want it, I can't remember where I > 
stashed 
> it. I can probably draw a sketch of the system, though, if I can't > 
find the 
> paper. I'll look for it for a few more days, then I'll make a sketch. 
> 
> I was going to make the system a few years ago, but found I didn't > 
need it. 
> Now, I have a student looking at soils in the Bahamas, and we might > 
start 
> separating out the very fine materials to determine the source of the 
> airborne dust components. I think the elutriation system might be > 
modified 
> to make that separation. 
> 
> Jim 
> 
> 
> On 1/6/09 9:29 PM, "Kreigh Tomaszewski" <Kreigh at Tomaszewski.net> 
wrote: 
> 
>> Jim. 
>> 
>> That is pretty cool. I use a single stage to recycle tumbling grit 
and 
>> have to make multiple passes with decreasing water flow. I would 
like 
>> to see the paper. Being able to separate multiple grit sizes in a 
>> single pass would save me a lot of time. 
>> 
>> Kreigh 
>> 
>> 
>> On Tuesday, Jan 6, 2009, at 12:40 America/Detroit, Jim Murowchick >> 
wrote: 
>> 
>>> For anyon
e interested, there was a USGS paper, probably from the 
>>> 1960's, 
>>> that described an elutriation system for mineral separation. It 
>>> consisted 
>>> of a series of tall (10-15"?) U-shaped glass tubes (oriented 
>>> vertically), 
>>> each with a stopcock at the bottom of the U. Each glass tube had a 
>>> smaller 
>>> inside diameter than the one upstream, and they were connected in 
>>> series 
>>> with a rubber tube. At the start, a separatory funnel with a >>> 
stopcock 
>>> at 
>>> the bottom held water, and was at the highest elevation. At the 
>>> outflow 
>>> end, a rubber tube from the last U drained into a collection flask. 
>>> 
>>> With a slow stream of water flowing through the system (feeding 
>>> into the 
>>> separatory funnel, a slurry containing the sample was drizzled into 
>>> the 
>>> separatory funnel. The heavies collected at the bottom of the first 
>>> U, 
>>> lighter minerals moved on to the second or third U, and the 
lightest 
>>> ended 
>>> up in the collection flask at the end. Fine-tuning of the water 
flow 
>>> and 
>>> gradient controlled the separation efficiency, and the separates 
were 
>>> then 
>>> emptied through the stopcock at the bottom of each U tube. 
>>> 
>>> I'll try to find the paper, in case anyone wants the specifics, but 
>>> if 
>>> anyone
 can provide the reference info, I'd appreciate it. 
>>> 
>>> Jim Murowchick 
>>>