[Rockhounds] Elutriation

[Jay Bates]

Kreigh,

I know you have tried elutriation to separate grit from rock dust 
resulting from using using the grit to grind down rocks. I am wondering 
if you obtained any useful grit as I know grit breaks down into smaller 
sizes with use. I use 60/90 grit continuously to  make spheres. Some  
people seem to think they can reuse the grit after they separate it from 
the rock dust. I maintain that you can recover the grit but it is of a 
smaller size and not much use in sphere grinding.

pmodreski at aol.com wrote:
> 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 
>>>>  
>