My initial education on Pd points occurred in the early 70's when we got in about 50,000# of wire relays. That weight included the steel racks and the wiring bundles. All the tiny rectangular shaped points were pure Pd. The value overall ended up to be about $1/pound, with Pd at about $60/oz. We cut off the blades as close as possible with a small reciprocating alligator shear.
I did a lot of experiments looking for something that would dissolve the copper without touching the Pd. The only thing I could find was a solution containing 4# of chromic acid and 2900ml of conc. sulfuric acid. A nasty mix. I don't remember the total volume this was diluted to but I'm thinking it was 2-4 gallons (I'm thinking it was 2 gal). I also don't remember if the solution was heated or not - maybe not, since the copper dissolving generated much heat. After this treatment, there was still a thin layer of nickel on the back of all the points. If the nickel was still there, you could pick up the points with a magnet. The nickel was removed selectively with hot conc. HCl, leaving the pure Pd. I assume the Pd was pure because that's what we sold it for on a continual basis to the same large buyer. However, Lou and I talked about this once and he didn't think they were pure.
The last Pd relay banks I processed, about 5000# gross weight, were found in a small forgotten room about 10 years ago on the empty 3rd floor of a place I worked. The building (about 750,000 ft2) was originally built and used by a large metal fabricating company. When the phone companies started to convert to electronic switching in the 70's, this scrap was everywhere and was readily snapped up by the refiners. Now, about the only place you can find it is in old buildings (maybe, abandoned buildings) that had switching rooms to operate the 100's of phones in the plant.
There are many different Pd relay configurations. The most common good ones were long and skinny. The plastic boxes were about 1" x 3/4" x 3 or 4" tall. Instead of flat blades, the points were mounted on long wires, probably phosphor bronze . The photo is about the closest thing I could find in appearance, although it seems to be a later version. It was on eBay - 1st link. The 2nd link shows banks of relays.
http://www.ebay.com/itm/Western-Electric-Telephone-Relay-Vintage-Wire-Spring-/280512060964?pt=LH_DefaultDomain_0&hash=item414fd25e24
https://encrypted.google.com/search?as_st=y&tbm=isch&as_q=vintage+telephone+switching+relay&as_epq=&as_oq=&as_eq=&imgsz=&imgar=&imgc=&imgcolor=&imgtype=&cr=&as_sitesearch=&safe=images&as_filetype=&as_rights=#facrc=_&imgdii=_&imgrc=hGRMA1blpI07DM%253A%3BQQyDF5clYO800M%3Bhttp%253A%252F%252Fthumbs1.ebaystatic.com%252Fd%252Fl225%252Fm%252FmwzQOTXlR3C_HcQpE6okMiA.jpg%3Bhttp%253A%252F%252Fwww.ebay.com%252Fsch%252Fi.html%253F_kw%253DWestern%252BElectric%252BRELAY%3B224%3B165
