Kanji Takeda

Experimental and numerical investigation of the effect of buoyancy force on solid flow

This paper presents an experimental and numerical study of solid flow under conditions related to an ironmaking blast furnace where the flow of particles is driven by the downward gravitational and upward buoyancy forces. Physical experiments were conducted with a water model and wooden balls. The results showed that the flow pattern and stagnant zone profile, strongly affected by the level of liquid and the position for solid discharging, are more complicated than those obtained when the gravitational force is the only driving force. Numerical experiments were performed by means of discrete element method that considers explicitly the key forces involved, including the gravitational, buoyancy, and various interparticle forces due to the collision and contact between particles. It was shown that the simulation model proposed can reproduce the experimental results well. The analysis of the numerical results indicates that the flow pattern observed under given conditions can be related to the packing and force structures. An attempt had also been made to simulate the solid flow in a blast furnace hearth.

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).