Direct reduction method and rotary hearth furnace

A rotary hearth furnace comprising:

• a rotary hearth rotatable for moving objects thereon in a direction of rotation from an object feeder toward an object collector;
• burners located above the hearth at at least two locations spaced in the direction of rotation, to provide flames to thereby heat and reduce the objects which release a combustible gas;
• means for feeding a gas for secondary combustion above the objects on the hearth and below at least one of the burners to combust the combustible gas;
• and
• partitions dividing the furnace into a plurality of combustion compartments, said partitions being arranged such that the objects on the hearth move sequentially through the combustion compartments, wherein said means for feeding a gas for secondary combustion are not located in a downstream most one of said compartments.

A rotary hearth furnace comprising a rotary hearth rotatable for moving objects thereon in a direction of rotation from an object feeder toward an object collector;

• burners located above the hearth at at least two locations spaced in the direction of rotation, to provide flames to thereby heat and reduce the objects which release a combustible gas;
• means for feeding a gas for secondary combustion above the objects on the hearth and below at least one of the burners to combust the combustible gas;
• and
• partitions dividing the furnace into a plurality of combustion compartments, said partitions being arranged such that the objects on the hearth move sequentially through the combustion compartments, wherein said means for feeding a gas for secondary combustion are not located in a downstream most one of said compartments, further including a flue for discharging gas from the furnace, wherein the flue is not located in a downstream most one of said compartments.

A direct reduction method comprising the steps of:

• feeding objects including a metal oxide and a reductant onto a rotary hearth of a rotary hearth furnace at an object feeder;
• moving the objects through the rotary hearth furnace in a direction of rotation from an object feeder to an object collector;
• discharging the objects from the rotary hearth at the object collector;
• applying flames from burners located above the objects on the hearth at at least two locations spaced in the direction of rotation, to thereby heat and reduce the objects which release a combustible gas;
• and
• feeding a gas for secondary combustion above the objects on the hearth and below at least one of the burners to combust the combustible gas, and not feeding a gas for secondary combustion above the objects on the hearth and below a downstream most one of said burners.