Melting and Reduction Behaviour of Individual Fine Hematite Ore Particles

Hlsarna is a new alternative ironmaking process of ULCOS program, which is under intensive development at EU. It uses coal and fine iron ore directly as raw materials instead of coke and pellet. In this context, the melting and pre-reduction behaviour of hematite ore in the smelting cyclone of Hlsarna process was studied in the laboratory scale. The experimental study which used the typical reaction conditions of smelting cyclone in the pilot plant supplies a good reference to the Hlsarna process and the results are helpful on determining the temperature range, gas composition and particle size in the smelting cyclone. All the experiments were performed in a High-temperature Drop Tube Furnace. The experimental temperature was varied from 1 550 K to1 750 K. A series of experiments have been conducted with different reaction time which was varied from 210 ms to 2 020 ms, thus enabling the characterization of partially reduced samples. It was found that the reduction degree increases with the increase of temperature and residence time, while decreases with the increase of particle size. The maximum reduction degree at the studied conditions is approximately in the range of 23-30%. Both solid sample and molten sample were obtained at the current experimental conditions. The completely gas-solid particle reduction took place at 1 550 K, 1 600 K for the residence time up to 2 020 ms. Fully molten particles can only be obtained at the temperature higher than 1 700 K.