UNIMIN OPERATOR WAS DRIVING LOADER W/SHOVEL LOADED ADN ELEVATED OVER 6 FT. CONSEQUENTLY, THE SHOVEL IMPAIRED HIS VISION. HE DROVE DIRECTLY INTO OUR MACK DUMP TRUCK, PLOWING INTO CAB OF TRUCK A ND ABOVE THE CAB. MY DRIVER HAD RIGHT-OF-WAY ANDBLOWED HORN ETC. THE LOADER CRUSHED CAB OF TRUCK, SEVERLY INJURING MY DRIVER.