The employee was working with another coworker in the process of charging a furnace (place scrap metal into the furnace). The injured worker's coworker was on a PIV that had a hopper on the lifts. In the hopper were briquetted radiators (compressed radiators in bales). As the hopper was being moved on the PIV, the hopper latching mechanism malfunctioned causing the hopper to tip and the briquetted radiators to fall out and roll into the injured employee's leg.