Determination of the Reaction Rate Controlling Resistance of Goethite Iron Ore Reduction Using CO/CO2 Gases from Wood Charcoal

Abstract

In the present work, an attempt is made to use non-contact charcoal in the reduction of run-off mine goethite ore at heating temperatures above 570 °C. The reduction mechanism was adopted, following Levenspiel’s relations for the shrinking core model at different stages of reduction. The non-contact charcoal reduction approach is adopted to maximize the benefit of using CO/CO2 gases from charcoal for reduction without the need for beneficiation and concentration. The rate-controlling steps for the reduction kinetics of average particle sizes 5, 10, 15, and 20 mm at 570, 700, 800, 900, and 1000 °C were studied after heat treatment of the ore-wood charcoal at a total reduction time of 40 min using activated carbon reactor. Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray (EDX) analyses were done to investigate the spectrometric phase change and metallic components of the ore sample after reduction, respectively. The average percentage of the metallic iron content (56.6, 60.8, and 61.7%) and degree of metallization (91.62, 75.96, and 93.6%) are achieved from the SEM/EDX analysis of the reduced ore sample at reduction temperatures of 570, 800, and 1000 °C, respectively. The results indicate the tendency for high carbon deposit at the wustite stage of the reduction process at the lowest of temperature 570oC and the residence time of at 10 min. This study demonstrates that diffusion through the ash layer is the controlling resistance of the overall reduction process.

Recent Trends in the Technologies of the Direct Reduction and Smelting Process of Iron Ore/Iron Oxide in the Extraction of Iron and Steelmaking

“…This approach tends to also bypass the idea of pelletization, communition, and hot briquette preparation of iron ore-reductants composites which have shown to have high economic implications, are energy-demanding, time-consuming, etc. Ogbezode et al [29] introduce the concept of the ironmaking technique the NDR method by investigating the reduction behavior of goethite ore using carbon monoxide gas from the wood charcoal atmosphere. The result revealed a DRI with a metallization degree of over 93% was achieved at an overall reduction temperature of 1000°C.…”

“…The result revealed a DRI with a metallization degree of over 93% was achieved at an overall reduction temperature of 1000°C. Ogbezode et al [30] also performed an NDR process on selected goethite-hematite ore under isothermal conditions using CO/CO 2 atmosphere from wood charcoal. The kinetics of the reaction and rate-controlling resistances of the process was monitored at different roasting temperatures and reaction rate.…”

“…The quest for the production of iron and steel under clean energy evolution cannot be overemphasized. The negative impact of carbon emissions released from the [31].…”

“…Li et al [53] studied the reaction kinetics by carbothermic reduction of fayalite under nonisothermal conditions. Ogbezode et al [29] performed reduction runs on goethite iron ore under non-isothermal conditions using charcoal. Ogbezode et al [30] also performed carbothermic reduction and investigated the kinetics behavior of goethite-hematite ore in the CO/CO 2 atmosphere.…”

“…Ogbezode et al [29] performed reduction runs on goethite iron ore under non-isothermal conditions using charcoal. Ogbezode et al [30] also performed carbothermic reduction and investigated the kinetics behavior of goethite-hematite ore in the CO/CO 2 atmosphere. Man et al [42] also examined changes in iron/ore pellet composite during the carbothermic DR process.…”