The Whyalla Steelworks receives iron ore mined at various sites along the Middleback Range. Iron ore mining in this region dates back to at least 1900. Prior to the steelworks' construction, the ore was shipped from Whyalla (then known as Hummock Hill) to Port Pirie for use as a flux in smelters. It was later supplied to steel-making facilities at Port Kembla, New South Wales. The first shipment of iron ore by sea for Port Pirie departed Whyalla in 1903. The first mines to be developed were Iron Knob and Iron Monarch, with later developments including Iron Baron, Iron Knight, Iron Princess, Iron Chieftain and Iron Duke. The mines were developed by the Broken Hill Proprietary Company (BHP), which went on to develop the steelworks and shipyards.