Thermodynamic and Mineralogical Aspects of Injecting LPG, Coke Oven Gas, and Oxygen into Goethitic Iron Ore Sintering Process

摘要

The effect of substituting the fossil fuel partly with gaseous fuels on CO2 emission in sinter plants was assessed. Fuel gases such as coke oven gas (COG) and liquefied petroleum gas (LPG) were injected into the sinter pot, to see the effect on sintering speed and quality parameters. Densification was predominant in the case of COG and LPG, leading to an increase in both cold and hot strength. Acceleration of the sintering process was noticed when oxygen was injected. The various phases formed as a result of injecting COG, LPG, and oxygen were identified with the help of X-ray diffractometer (XRD). Dicalcium silicate, a detrimental phase, was found in the range of 16-25% when COG and LPG were injected and was absent when oxygen was injected. Magnetite (Fe3O4) and silico ferrite of calcium and aluminum (SFCA) formation got enhanced with oxygen injection. Injection of oxygen along with COG and LPG reduced dicalcium silicate and resulted in acceleration of the sintering process as well as superior quality parameters. The presence of manganese in the iron ore up to 2% resulted in MnFe2O4, a spinel phase that enriched the magnetite. No adverse effect of goethite was noticed due to gas injection. A reduction of 0.65 million tons in CO2 emissions per annum was envisaged by substituting 10 kg solid fuel with gaseous fuel per ton of sinter. After successful pot tests and encouraging results therein, a COG injection system was designed and installed in an industrial-scale sinter plant.