Natsuo Ishiwata

Investigation of Reduction and Smelting Mechanism in the Hi-QIP Process

A new coal-based reduction and smelting process for production of high quality iron pebbles in a rotary hearth furnace (Hi-QIP Process) was developed. The reduction, carburization, smelting, and separating mechanism of the Hi-QIP process were investigated. The experiments were carried out in a graphite heater furnace under rapidly heating up to 1773 K. A mixture of coal and ore produced molten metal and slag, which were held on the coal and did not come into contact with the refractory located under the coal layer. It is confirmed that the reduction of wettability between the iron and slag promotes the separation of them, when the content of FeO slag decreases. High productivity of the process is expected when using iron ore with small particle diameter and low gangue content. Favourable operating results were obtained in a pilot test using a rotary hearth furnace with a diameter of 7 m and a width of 1.5 m. This test demonstrated the possibility of continuous production of iron pebbles with high productivity (15t-iron/d).