Geoff,
I am not aware of anyone doing a specific study on the heating
produced by grinding. It sure would be interesting to see how hot
things get in the pulveriser. I suspect they don't get mush past
50°C or so: things are moving pretty quickly in there. Temperatures
in the jaw crusher are probably much lower.
There are a number of studies that have looked at short-term
transient heating in controlled laboratory conditions. These studies
(mostly those on annealing conditions) indicate that the temperatures
have to be pretty high for hours or longer before annealing occurs.
As such, most feel this short-lived, low temperature effect is not
important. If it was, we would probably see more scatted in unknown
ages vs. age standards.
Good luck with your work!
John Garver
At 10:02 AM +0100 01/26/2003, Ruiz, Geoffrey wrote:
>Hi,
>
>happy new year! Let's start this new year by a methodological question:
>
>During separation, most of us (is not it?) commonly used first the
>jaw crusher and secondly the vertical grinder/mill. For the latter
>one, heating may occurred. Is it really problematic for apatite
>using FT analysis or U/Th-He?
>
>Did anyone already investigate this? Grinding progressively the
>sample with the vertical mill was a solution I used for FT to avoid
>heating, any other practical solution?
>
>Thanks for any contribution
>
>Geoffrey Ruiz
>Geol. Inst.
>Sonneggstrasse, 5
>ETH Zentrum
>8092 Zurich
>
>>From the 1st of February:
>
>Faculteit der Aardwetenschappen
>Vrije Universiteit
>de Boelelaan 1085
>1081 HV Amsterdam
--
_____________
John I. Garver
Department of Geology
Union College
Schenectady NY 12308-2311, USA
518-388-6517
518-388-6770 (main office)
518-388-5417 (fax)
http://idol.union.edu/~garverj/garver/garver.htm
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