Ice-creamator

I got this idea a few yrs ago at my dads lab. we were wathcing this vietnam movie while freezing stuff in liquid nitrogen and smashing 'em with a hammer. The movie had flamethrowers and so i got to thinking. Why not take the same basic idea and fuction of a standard flamethrower and convert the idea over to spray an area with liquid nitrogen. so heres how it goes... You carry a refrigerated container filled with liquid nitrogen on your back. A hose connects it to a rife-like device that channels it into a short hard spray (much like a pressure washer). Then when the target is frozen, another component beneath the liquid nitrogen port, fires a ball bearing at a few hundred mph into the frozen mass effectivly shattering it. It could also be used to break through obstacles such as barricades, metal doors, barbed wire, walls etc.. It could even be utilized as an "anti-mine" device. By simply freezing the ground ahead of you, any active explosives would be rendered useless by the intense cold. The user of a weapon such as this would need to wear a protective suit capable of withstanding extreme temperatures; yet, at the same time, granting some level of protection against bullets, shrapnel and heat. IMO the hardest parts would be: a). Designing a container capable of keeping the liquid nitrogen cold for long periods of time while in the field. b). Finding a way to refill the containers safly. And c). Minimizing the risk of accidents to allies and innocents.