hard drive component recycling

[cwg_]

i recently disassembled 250 SCSI hard drives from various HP server/storage units, drive sizes ranging from 9Gb-300GB, i am curious as to what components are individually recyclable, i would imagine most metallic components, but i'm curious about the magnets, counterweights and platters. i've read that the platters are aluminium covered in a thin coat of platinum/palladium/gold, but i found little information regarding the sand like substance inside the counterweights.

i have separated out the following components:

aluminium frames (base casting/hda)
steel/stainless steel frame covers
printed circuit boards (logic board)
platters (disc)
actuators (arm/head/coil/axis)
spindle motors
voice coil head contacts with ribbon cable (to logic board)
counterweights (ferrous ??, activated carbon pellets ??)
actuator magnets (neodymium)

 

[popatim]

The logic bds usually sell well on auction sites as do the magnets - and not well at all at scrap yards.
The platters can be made from various alloys but the trend for quite some time was to put the thin magnetic layer on a glass/ceramic platter. If you can snap the platter in half its glass and worthless.