Characterization and Reduction Behavior of Cold-Bonded Composite Pellets for Direct Reduction Using an Organic Binder


Cevik E., Ahlatci H., Sun Y.

METALLURGIST, cilt.57, ss.468-477, 2013 (SCI İndekslerine Giren Dergi)

  • Cilt numarası: 57
  • Basım Tarihi: 2013
  • Doi Numarası: 10.1007/s11015-013-9757-2
  • Dergi Adı: METALLURGIST
  • Sayfa Sayısı: ss.468-477

Özet

The purpose of this study was to investigate the reduction behavior of cold-bonded composite pellets produced from low-grade hematite iron ore using molasses solution at various concentrations, as well as their physical and chemical properties. Direct-Reduction Iron (DRI) technology makes it possible to assess low-grade iron ores and convert them into scrap at facilities that have electric arc furnaces. The reductant used was coke with fixed carbon of 86.04%. The alkalinity rate was adjusted to 0.7 by adding calcium carbonate. In the composite pellets produced, the 300 N/pellet compression strength recommended in the literature was achieved with a Fe-tot/C-fix ratio of 2.5 and 3 using a 50% concentrated molasses solution. Composite pellets prepared with a Fe-tot/C-fix ratio of 3.5 using a 40% concentrated molasses solution reached a compression strength of 496 N/pellet. The porosity is inversely proportional to the increase in compression strength and binder concentration. Reduction experiments were conducted by applying different temperatures and durations to samples possessing optimum conditions for each Fe-tot/C-fix ratio: the best result was achieved with a 88% reduction rate in composite pellets with a Fe-tot/C-fix ratio of 3.5 at the end of 1 h. Pig iron nuggets were characterized using an optical microscopy (LOM) and a scanning electron microscopy (SEM) with energy dispersive spectroscopy (EDS).