While pulling 54"" steel cable conveyor belt on conv#Y34 - approx. 200' belt had been secured for pulling with 6"" C-Clamps. EE was standing at the approx 230' from roll end where c-clamps were connected to roll. Both clamps released and flew the 230' to strike him on both the right and left upper thigh. He sustained bruising and abrasions on both thighs.