We had the same problem with 2 roosters and 22 hens. We had 3 birds scalped. Two of them I managed to stitch the skin back in place, but the feathers never grew back. The third died after a few miserable days since she had been wounded several hours before we found her and could do nothing to repair the damage. The first one was hurt by a silver sebright roo that was wonderful with people. It didn't even look like he was trying to mate, just like he was trying to rip her head off. He ended up beheaded as soon as I could leave the poor girl alone. His replacement, another bantam, but a frizzle cochin, was just as bad. Now he's gone too. I hope his son has better manners when he gets to mating age.
Separation may well just cause a more frenzied attack when they do get to the girls. It did with us.
Life is better without evil birds in the flock, just ask my two bald combless girls.