Carbothermic Reduction of Ore-Coal Composite Pellets in a Tall Pellets Bed

Abstract

Recently, increasing attention has been paid to alternative ironmaking processes due to the desire for sustainable development. Aiming to develop a new direct reduction technology, the paired straight hearth (PSH) furnace process, the carbothermic reduction of ore-coal composite pellets in a tall pellets bed was investigated at the lab-scale in the present work. The experimental results show that, under the present experimental conditions, when the height of the pellets bed is 80 mm (16–18 mm each layer, and 5 layers), the optimal amount of carbon to add is C/O = 0.95. Addition of either more or less carbon does not benefit the production of high quality direct reduced iron (DRI). The longer reduction time (60 min) may result in more molten slag in the top layer of DRI, which does not benefit the actual operation. At 50 min, the metallization degree could be up to 85.24%. When the experiment was performed using 5 layers of pellets (about 80 mm in height) and at 50 min duration, the productivity of metallic iron could reach 55.41 kg-MFe/m2·h (or 75.26 kg-DRI/m2·h). Therefore, compared with a traditional shallow bed (one or two layers), the metallization degree and productivity of DRI can be effectively increased in a tall pellets bed. It should be pointed out that the pellets bed and the temperature should be increased simultaneously. The present investigation may give some guidance for the commercial development of the PSH process in the future.

Conversion Termoquímica Y Análisis Microestructural De Briquetas Auto-Reductoras Hechas De Cáscarilla Resultante De La Laminación Proveniente Del Proceso De Conformado Del Acero en Caliente (Mill Scale), Y Grafito Reciclado

“…-1050ºC -20.7% de grafito y 90 min -90 min -20.7% de grafito; llega a valores de 99.9, 95.9 y 94.4%, respectivamente. El proceso de reducción es más eficiente e incrementa el grado de conversión a altas temperaturas debido a una alta transferencia de calor y a la presencia de una atmósfera rica en gases de CO que evita la re-oxidación del material reducido [20]. Jiang, X, et.…”

Preparation of MgO added iron ore pellets and effects on a pilot scale blast furnace operation

“…Iron ore pellets as the indispensable burden of blast furnace show many benefits, such as high iron grade(> 63%TFe), high physical strength and uniform and size distribution, high and even porosity, less loss on ignition or volatiles, easy reducibility, and lower abrasion during transportation and use [1]. In recent years, under the pressure of energy saving and emission reduction in the iron and steel industry, the proportion of pellets charging into the blast furnace increase, and higher requirements were put forward for the quality and metallurgical performances of the pellets [2][3][4][5][6][7]. By increasing the content of MgO in iron ore pellets, not only the metallurgical performances of pellets are improved, but also the MgO content in sinter (another burden of blast furnace) decrease, because the excess MgO in sinter causes many negative effects such as the sintering rate, the fuel rate, and the sinter strength and reducibility deteriorate [8][9][10][11].…”