Here is another photo.

I would call a tree horticulturist and get an opinion. Depends on if grinding is all the way around if more than 40% of bark is peeled i would say its gone. You will have to seal the wombs somehow for it to heal i hope it helps.
Trace

This post was edited by Tcamp30144 on Wed, Oct 29, 14 at 23:41

We have one that looked a lot like that - bark about half-peeled off and mostly dead. Then it ended up in the middle of my veggi garden and was well-watered. It's back from the dead!
Can you get to the dead stuff and prune it off? Next spring, start to evaluate the leafy branches and see where to prune them for best shape.

The trunk NEEDS sun protection. I let the branches droop to shade ours, and had a sun shade set up until it was better shaded.

We never sealed the "wounds" because by the time the bark peels, there's no "wound". It's dry wood underneath.

One problem to look out for with citrus around these here parts is they tend to sucker viciously after a near-death frost experience, especially if denuded of leaves, and those suckers often are very weakly "attached" to the main growth. They break off easily and usually don't grow large at all.

If you feel you should prune (with citrus many people never do no way no how no matter what) to correct a badly half-killed tree, be very prudent and very light handed about what you cut. Relying on growth from today's rapid suckering to sustain the tree a few years down the line usually doesn't work, especially with an old tree.

Then again it could live longer than you and I combined!

I would remove peeling bark and seal the dry wood to keep tree from lossing moister. If wood dryies out will cause more stress and loss of more bark. If u seal it and stop moister loss tree can heal.
Trace

This post was edited by Tcamp30144 on Fri, Oct 31, 14 at 0:09

Do not seal anything.
Artificially "sealing" wounds has been shown to be of no value.
Do not remove loose bark. It is providing a tad of protection to the stem until the new wood will cover the wound.

Didnt mean pull bark off the tree wow i ment the lose bark that is curling off the tree. Just giving advice from experience of my trees but do as u wish good luck with that.
trace

Thanks for all the responses. I painted the trunk to protect it then it peeled. I think it was just aggressively pruned before we moved in. I guess I could try shade cloth instead, but all the shade cloth we put on higher branches didn't last long due to all the sun exposure.

You are probably going to have to paint the trunk routinely, like maintenance. I paint my tree trunks twice a year but they're still growing and the paint peels because the trunk is expanding. Are you diluting the paint 50/50 with water? Unfortunately, whoever hacked your tree did not know what they were doing and treated it as any other tree, I think it will be ok but it will take some time to recover.
Evan