The sap is oozing because the living cambium of the tree is exposed to the air and probably damaged. Small wounds may heal, but this sounds alittle bigger. The bark will not grow back, because bark is actually dead material that is pushed outwards by new (living) material in the cambium. If the cambium dies, you will have a wound. If a lot of cambium dies, you will have a chicot.
Grafting wax may be useful here. Pine sap is engineered to help seal and keep wounds moist, but if the area is extensive, the sap may dry and crack, letting the cambium dry and die. Try a layer (1/4" thick) of grafting wax. You may want to wrap the trunk with a cloth to keep the direct sun from drying the wound further.
Deer do this all the time - it's their business. Too bad, but the tree was not too old at this point, it should be easy to replace if it does become too badly wounded.