EMPLOYEE WAS USING A CUTTING TORCH TO CUT A STEEL HOOK OFF OF A SET OF CABLE SPREADERS CONNECTED TO THE LIFTING HOLE OF A 988 CAT LOADER AND A PIECE OF CRUSHING EQUIPMENT. THE CABLE HAD TENSION ON IT WITH NO WAY TO RELEASE THE TENSION. THE EMPLOYEE POSITIONED HIMSELF TO SAFELY CUT THE HOOK. WHEN THE HOOK WAS CUT A PIECE FLEW BACK STRIKING HIS LEFT KNEE CAUSING A MINOR CONTUSION.