It says in the faq:
If you do not award your bounty within 7 days (plus the grace period), the highest voted answer created after the bounty started with at least 2 upvotes will be awarded half the bounty amount. If there's no answer meeting that criteria, the bounty is not awarded to anyone.
Then why I did not get half of bounty for this question: How to use Callback function to get language in Tizen?
I need to mention that the author accepted the answer and then declined it; might have something to do with that.