Open AccessTHERMODYNAMIC ANALYSIS OF IRON OXIDES REDUCTION USING CARBON AND WATER VAPOUR
Author(s) -
Ю. С. Кузнецов,
О. И. Качурина
Publication year - 2019
Publication title -
izvestiâ vysših učebnyh zavedenij. černaâ metallurgiâ
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.3
H-Index - 7
eISSN - 2410-2091
pISSN - 0368-0797
DOI - 10.17073/0368-0797-2019-5-394-406
Subject(s) - wüstite , carbon monoxide , chemistry , hydrogen , oxide , water vapor , atmospheric temperature range , carbon dioxide , isothermal process , water gas , carbon fibers , inorganic chemistry , dissociation (chemistry) , analytical chemistry (journal) , materials science , syngas , thermodynamics , catalysis , organic chemistry , physics , composite number , composite material
Thermodynamic analysis was performed for complete reduction of iron oxide during heating the initial system «Fe 3 O 4 (e o mol) – H 2 O (b o mol) – C (excess) » with isothermal exposure. By the nature of ongoing reactions, processes in the system can be divided into four stages. Carbon gasification by water vapor at temperatures below 880 K activates water gas reaction and CO dissociation to form black carbon. Composition of the resulting H 2 – H 2 O – CO – CO 2 gas mixture depends only on the temperature. The consumption of carbon at 880 K is ~0,4446 moles on 1 mole of water. Reduction of Fe 3 O 4 to wustite FeO 1+x with varying degrees of oxidation occurs in the temperature range 880 – 917 K. Hydrogen reduces oxide at temperatures above 888 K. The percentage part of a whole oxide Fe 3 O 4 reduced by hydrogen into this temperature range increases from zero to ~63 %. The total number of Fe 3 O 4 , reduced to wustite at 917 K is ~123 moles for 1 mole of water. It is possible only with repeated regeneration of reductants CO and H 2 according to the reactions of carbon gasification by water vapor and by dioxide CO 2 . The carbon expense is about 78 moles. Wustite FeO 1.092 formed at 917 K can be reduced by monoxide CO only at temperatures of 917 – 955 K to wustite FeO 1.054 with a lower degree of oxidation. Carbon is gasified only by dioxide CO 2 , the carbon expense is approximately 18 moles. When isothermal exposure is ~955 K, wustite is reduced to iron. Wustite can be reduced only by carbon monoxide. The carbon expense is approximately 257 mol. For full reduction of 123 mol of Fe 3 O 4 in a mixture with an excess of carbon in a closed system at 1 atm, 1 mole of water is sufficient. The total carbon consumption is ~353 moles for obtaining 368 moles of Fe, or ~0.21 kg/kg iron.