Why did slave holders support settlement of freed slaves in Africa?

Remember that the slaves were freed by force, as a result of the Civil War, and not because their former slave masters had a change of heart and decided voluntarily to free their slaves. This creates a certain amount of hostility. The freed slaves had legitimate reasons to resent their former owners for having enslaved them, and the former slave owners resented the former slaves for having been freed, which they regarded as a form of theft, since slaves were valuable property, who in many cases had been purchased from slave dealers for a great deal of money. If the freed slaves were to return to Africa, a lot of social awkwardness could therefore be avoided.