Direct-fired stratified atmosphere furnace system

A method for heating or melting a charge of material in a direct-fired furnace, comprising:

• (A) introducing said charge into said furnace to expose said charge to radiant heat from a direct-fired burner placed above said charge;
• (B) providing fuel and oxidant into the furnace from said direct-fired burner at a mass average velocity not exceeding 50 feet per second, and combusting the fuel and oxidant within the furnace to generate heat and to produce combustion gases;
• and
• (C) introducing a charge-proximal gas into the furnace between said direct-fired burner and said charge at a point at least 50 percent of the vertical distance from the burner to the charge at a velocity not exceeding 50 feet per second wherein said charge-proximal gas has a higher density than said fuel and oxidant to create charge-proximal atmospheric stratum that contains a substantially reduced amount of said combustion gases, thereby exposing said charge to a furnace atmosphere of oxidative properties that are different from those that exist in the absence of said charge-proximal gas, and exhausting combustion gases from the furnace from an exhaust located above the burner.