I had a couple of broken sun lounger and before throwing them away I tried to save all the useful components I was able to get.
Step 1: Unscrew
Start unscrewing all the unscrewable with screwdrivers, wrenches or hex keys.
In my case there were few things to unscrew:
1) the sun shade can be removed unscrewing just 2 bolts
2) a couple of triglide buckles
3) legs crossbars
4) small screws in the legs (preventing the plastic elbows from coming out from aluminium tubes)
the remaining, especially the frame structure was all joined by solid(actually semi-tubular) rivets
Step 2: Remove Rivets
To disassemple the structure there are a lot of rivets to be removed.
In theory you could saw the rivets, but this would probably damage the aluminium tubes, or use a grinder to remove one of the heads but again risking a damage to the aluminium tubes.
The best way to remove the rivets was to drill the expanded head with a power drill
Step 3: Drill the Dents
Some plastic elbows and corners are secured in place by dents
then I drilled the dents and disassembled the joints
Step 4: Remove End Caps
remove the end caps from the pipes, if necesssary with the help of a flat screwdriver, and then remove the textile
Step 5: Results
From 2 broken sun loungers to throw away I obtained:
2 complete sun shades
6 circular bars
8 slotted bars(short)
8 slotted bars (long)
4 cross bars(smaller circular bars with end joints for perpendicular pipes with threads)
8 curves 90° for slotted bars
12 joints 90° for circular bars
8 folding legs
4 pivoting joints
12 end caps
4 triglide buckles
So basically there is not much left to throw away except for a few pieces of broken plastic, the removed rivets and the torn textile.