Are you on 10 or 25 man? Mages aren't the best class to apply slows to the mines anyway, and definitely not as Arcane. If you're on 25 then it should be being taken care of by other classes and you just focus on killing them quickly. You can put out decent damage to the mines (decent compared to most classes not named LOLCHAINLIGHTNING).
If you're on 10 man and you don't have a great comp for slows, then you may be better off switching to frost. Better slows, better burst on them through frozen orb, you have the water ele freeze and just more overall control. And if you mainly play Arcane then you will basically be geared for it already.