External hard drive does not eject
As long as your volume is unmounted, whether or your drive is spinning doesn't matter.  The drive will usually spin down on its own depending on when it's set to "go to sleep."

When you eject, you have successfully unmounted the drive.

If you wish to confirm, in terminal, just issue the command mount.  If you don't see the volume name of the drive you had mounted previously, you can consider it unmounted.