EMPLOYEE STATED THAT HE HAD HIS CHAIN COME ALONGS HOOKED TO THE CABLE SLED & IN THE EYE OF A ROOF BOLT PLATE. HE WAS PULLING THE CABLE FROM THE END OF THE TRACK WHEN THE EYE ON THE BOLT PLATE BROKE CAUSING THE HOOK TO FLY BACK & STRIKE HIM RIGHT BELOW THE RT. SHOULDER BLADE.