EE WAS ASSISTING IN SETTING STEEL ARCHES AT THE RETURN AIR SHAFT. HE WAS GUIDING THE 3 1/2 SCOOP INTO THE LEG ON THE ARCH TO INSTALL THE SPREADER PIPE AND BOLT. AS THE LEG WAS MOVED IN, HE PLACED HIS R. MIDDLE FINGER BETWEEN THE PIPE AND ARCH, RESULTING IN THE TIP OF HIS FINGER BEING AMPUTATED. EE WAS TRANSPORTED TO THE HOSPITAL AND THE FINGERTIP WAS REATTACHED.