Is it permissible for a benevolent loan fund to accept usurious money, and can some administrative fees be added to the loan?

Usurious funds whose owners are unknown should be spent on good deeds. They should not be left to the bank, as this would strengthen sin, nor should they be destroyed, as that would be a waste of money. As for follow-up and administrative expenses charged to the borrower, they are permissible if they are equivalent to the actual costs and are known to the borrower.