The complex comprises iron ore production and power-generation plants, it said.
Under the deal signed on Saturday in Riyadh, the Korean party will be responsible for the planning, engineering, procurement, construction, operation and management of the plants to be built in the Wadi Sawawin district of Saudi Arabia's northwestern city of Tabuk, STX said in a statement.
The Saudi project also involves pelletizing and desalination plants that are required to complete the proposed industrial complex, according to STX.
STX said it will produce 5 million tons of iron ore annually from the Wadi Sawawin mine owned by National Mining Co., a venture firm that Saudi Arabia's Al-Sharif Group and UK-based mine developer London Mining Plc established.
The iron ore mine is estimated to have more than 125 million tons of commercial reserves, STX added.
An STX spokesman declined to give further details about the project, including capabilities of the other plants.
