Use of residual iron within granulated metallic unit production facilities, and associated systems, devices, and methods

A method for producing granulated metallic units (GMUs), the method comprising:

• receiving a first supply of molten iron from a blast furnace and/or a basic oxygen furnace;
• producing GMUs by granulating the molten iron poured onto a target material of a reactor;
• removing residual iron as a byproduct of producing the GMUs, the residual iron comprising one or more of thin pig, steel, skulls, sinter, slag, scrap, or iron dust;
• mixing at least a portion of the residual iron with scrap metal to produce a blend;
• and
• providing at least a portion of the blend to the blast furnace and/or the basic oxygen furnace to produce a second supply of molten iron, different than the first supply of molten iron, to produce additional GMUs.