Rotary hearth furnace with charge slot air shield

An apparatus for charging feed material through an opening into a furnace comprising:

• a fixed structure oriented at an acute angle to the vertical;
• and
• a moveable door which, together with the fixed structure, defines the opening, the moveable door being mounted for movement toward and away from the fixed structure to widen and narrow the opening, the movable door being pivotally mounted at a pivot point, and the movable door comprising a first leg and a second leg, the first leg being joined with the second leg at approximately the moveable door pivot point, with the weight of the first leg biasing the movable door toward the fixed structure;
• wherein the moveable door and the fixed structure create a V-shaped downwardly pointing channel to direct the feed material being fed through the opening by gravity.