What mount system is this Hanimex zoom lens?

This lens was manufactured in the Canon FD (and new FD), Nikon F, Minolta M/MD, Pentax K, Fujika FX, CONTAX/Yashica (C/Y or Y/C), Konica AR, Olympus OM, and M42 mounts. Your lens is not any of those.

It is not the Sigma SA, Contaflex, Exacta , Praktica PB, Praktina, Icarex, Ricoh XR, Leica M, or Leica R mount.

It appears to have been modified at some point to be compatible with a changeable mount system like the Tamron Adaptall or T4-TX system. But it isn't either one of those systems, either.

The Arri PL mount for cinema cameras looks similar, but isn't a match.

Perhaps it has a missing part?¹

Perhaps, but there are no obvious attachment points for anything behind it other than the three locking tabs and the single pin tab. No open screw holes and no threads on the protruding rear lens group. I think it has been modified to fit in an obscure 8mm or 16mm movie camera.

_{¹ From a comment by @Rafael}

This lens is likely missing the part that connects directly to the camera body (as suggested by @Rafael). This may be an in-house connector used to attach different mount types. The reasons for this assessment follow:

• The lens appears to be intended for use with a 35mm SLR body. This is consistent with @MichaelClark's description of the mounts for which this lens was produced.

• If this lens were to be connected to camera body, as is, the deeply recessed rear element would break the mirror.

• I cannot find a mount that uses hook/claw shaped tabs. (Doesn't mean one doesn't exist.) However, this shape is commonly used to connect components internally.

You may be able to confirm the above if you can obtain and disassemble another copy of the lens in a different mount.

Photos of the body/side of the lens, clearly showing the focus and aperture rings, along with measurements of the diameter and length of different parts of the "mount", along with measurement of the "flange-focal distance" may be helpful.