How to save R "clean" sessions in BATCH mode?

Thanks a lot for all of you that have reply me about opening and ending R
workspaces in BATCH mode. However replies were a king general and I?m afraid
I could not take the entire message from them. Therefore I chose to expose
here a representative fraction of my work.

I have 50 Rdata files (F1,F2,F3,F4,?,F50) with objects inside.
I need to:

open F1:
? - perform some simple operations with the objects
? - export the solution with write.table
? - end F1 session
open F2
? repeat procedures as F1
?
open F50
? repeat procedures as F1
?

My difficulty here is to end a workspace and open one from the scratch to
avoid mixing files from consecutive worksessions, and thus using R memory
unnecessarily. I could use rm() to delete objects from the previous sessions
but it seems not an efficient task.
Any suggestions on how to perform this in Batch Mode? An examplified help
would be nice!

Diogo Andr? Alagador
http://www.biochange-lab.eu/people/diogo-alagador
Biodiversity and Global Change Lab, Museo Nacional de Ciencias Naturales,
CSIC, Madrid, Espa?a
Forest Research Centre, Instituto Superior de Agronomia, UTL, Lisboa,
Portugal