Patent GB-747584-A (GB)
Title: Treatment of pulverulent iron oxides
IPC: C01B31/30
Filed: 1953-11-06
Abstract: Iron carbide mixed with iron oxides and/or iron is produced by reacting iron oxides, e.g. oxidic iron ores or roasted pyrites in a fluidized bed containing a major proportion of iron carbide and smaller proportions of iron oxides, usually FeO, and/or Fe with a fluidizing reducing gas, containing CO as the main reducing constituent and in which the H2 content, if any, does not exceed 50 per cent of the CO content, at 400 DEG C. and above, but not exceeding the temperature at which the bed tends to become sticky e.g. 400-900 DEG C., preferably 570-690 DEG C.  Fe2O3, as roasted pyrites size 0.03-0.25 mm., is fed to a bed of 66 per cent Fe3C and 29 per cent FeO at 615 DEG C. and is fluidized and reduced by a 90 : 10 CO : CO2 mixture preheated to 675 DEG C. flowing at 0.4 meters/sec.  The overall reaction is 2.050 Fe2O3 + 28.575 CO + 3.175 CO2 = 1.100 FeO + 1.000 Fe3C + 21.525 CO + 9.225 CO2.  The powder mixture formed may be discharged intermittently or continuously to a rotary kiln at 800 DEG C. where iron is produced according to the equation 1.1 FeO + Fe3C = 4.1 Fe + 0.9 CO + 0.1 CO2. Gases consisting of a 90 : 10 CO : CO2 mixture from a carburetter at 1000 DEG C. are fed to the iron production kiln with resultant cooling of the gases to 800 DEG C. and resulting gases pass through a heat exchanger, where they are cooled to 675 DEG C., to the fluidization bed.  Gases consisting of 70/30 CO/CO2 mixture are withdrawn and pass through the heat exchanger and are heated to 750 DEG C.  These off-gases may be used to reduce the Fe2O3 or Fe3O4 to FeO in a preliminary fluidized bed at 600-850 DEG C.  A combined preheating and desulphurizing furnace may be provided, and lime or coal powder may be added to the carbide forming bed.  The Specification refers to the formation in the bed of Fe2C.ALSO:Iron carbide mixed with iron oxides and/or iron from which iron may be prepared is produced by reacting iron oxides e.g. oxidic iron ores or roasted pyrites in a fluidised bed containing a major proportion of iron carbide and smaller proportions of iron oxides, usually FeO, and/or Fe with a fluidizing reducing gas, containing CO as the main reducing constituent and in which the H2 content, if any does not exceed 50 per cent of the CO content, at 400 DEG C. and above, but not exceeding the temperature at which the bed tends to become sticky e.g. 400 DEG -900 DEG C., preferably 570 DEG -690 DEG C., Fe2 O3, as roasted pyrites size 0,03-0,25 mm., is fed to a bed of 66 per cent Fe3C and 29 per cent FeO at 615 DEG C. and is fluidized and reduced by a 90 : 10 CO : CO2 mixture preheated to 675 DEG C. flowing at 0,4 meters/sec.  The overall reaction is 2,050 Fe2 O3+28,575CO+3,175 CO2=1,100 FeO+1,000 Fe3 C+21,525+9,225 CO2.  The powder mixture formed may be discharged intermittently or continuously to a rotary kiln at 800 DEG C. where iron is produced according to the equation 1,1 FeO+Fe3C-4,1 Fe+0,9 CO+0,1 CO2.  Gases consisting of a 90 : 10 CO : CO2 mixture from a carburetter at 1000 DEG C. are fed to the iron production kiln with resultant cooling of the gases to 800 DEG C. and resulting gases pass through a heat exchanger where they are cooled to 675 DEG C. to the fluidization bed.  Gases consisting of 70/30 CO/CO2 mixture are withdrawn and pass through the heat exchanger and are heated to 750 DEG C.  These off-gases may be used to reduce the Fe2 O3 or Fe3 O4 to FeO in a preliminary fluidized bed at 600-850 DEG C.  A combined preheating and desulphurizing furnace may be provided, and lime or coal powder may be added to the carbide forming bed.  The Specification refers to the formation in the bed of Fe2C.