Theoretical Yield of Metallic Fe by COG in a Shaft Furnace in the Case of O₂ Pyrolysis

Abstract

Reduction shaft furnace is an effective process to produce Direct Reduced Iron (DRI), in which natural gas is used as reducing agent and heat source. Recently, in some countries lacking natural gas resources, Coke Oven Gas (COG) was proposed to be used in shaft furnace process instead of natural gas. In the present work, the effect of COG consumption on the yield of metallic Fe in shaft furnace was thermodynamically calculated. Both the chemical equilibrium and heat balance were considered. The main findings include, in shaft furnace process, the COG consumption as heat source is more than that as reducing agent. In the case of directly supplying reformed COG, the yield of metallic Fe decreases with increasing formation temperature of metallic Fe. For a coke oven with capacity of 600 000 tons, as the formation temperature are 850°C and 900°C, the corresponding annual yields of shaft furnace are 253.58 × 10 3 tons/year and 249.48 × 10 3 tons/year. In the case of ZR technology followed by supplying extra COG, the yield of metallic Fe first increases and then decreases, and there is a peak value. For a coke oven with capacity of 600 000 tons, as the formation temperature are 845°C and 900°C, the corresponding annual yields of shaft furnace are 283.44 × 10 3 tons/year (maximum value) and 278.38 × 10 3 tons/year. The findings from this work may provide guidelines for choosing optimal parameters for an actual shaft furnace process.

Fundamentals of reduction of CaO·Fe2O3 in CO/CO2 gas at 1000°C

“…The remaining unreacted Fe 2 O 3 appears as 2CaO·Fe 2 O 3 . The reaction equation is,

Figure 14. Equilibrium phase diagram among Fe 2 O 3 , Fe 3 O 4 , FeO, Fe and CO/CO 2 mixture gas [26].

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Thermodynamic Analysis of the Reduction of Vanadium-titanium Magnetite by Gasification Gas

“…The gas-based reduction process combined with the electric furnace melting process does not require the use of coke or the addition of calcium oxide and has the advantages of a high recovery rate of precious metal elements in iron ore, low-cost, high-energy efficiency, and low environmental pollution [14][15] . Natural gas is currently the main gas-reducing agent used in the gas-based reduction process around the world 16) . However, China's natural gas reserves are insufficient, and resources are unevenly distributed 17) , which severely limits the development of China's gas-based reduction.…”