We are sorry, but we have to inform you that that’s a hard ‘no’. Free spins can only be used as free spins (and of course on slots) and nothing else. An online casino will not allow you to exchange your free spins for chips. What you need to look for is a deposit bonus instead. Such a bonus will match your deposit with bonus cash, and you should be able to use that bonus cash at the online casino however you wish, including playing blackjack!