Effect Of Fe ₂ O ₃ On The Combustion - Supporting Process Of Blast Furnace

Pulverized coal injection (PCI) is a recognized method with the characteristic such as improving energy efficiency, reduction in the amount of coke consumption, enhancement the stability of operation and has been widely practiced to improving the economics of hot metal production from blast furnace (BF). However, with the increase of PCI rate, many unburned pulverized coal (PC) particles may be produced in the BF and this could have negative effects on BF operation including reducing gas permeability in the burden layer or causing an obvious drop of combustion temperature in the raceway. Therefore, improving the pulverized coal combustion efficiency within the raceway is important for increasing the PCI rate.In the paper, the mill scales and roasting product of siderite with microwave heating are employed as additive. The effects of additive addition content on combustion rate of bituminous coal and anthracite are investigated with static combustion method. In addition, the combustion characteristics of pulverized coal under the optimal addition are conducted by thermogravimetric analysis method. The main conclusions are as follows:(1) The effects of material amount and microwave power on heating behavior of siderite are indicated that the heating rate of siderite decreases with material amount increasing, and increases with microwave power increasing. It can be found that the roasting product of siderite has the positive role on catalytic combustion rate of bituminous coal and anthracite, and the trends are similar. The combustion rate is increased at first and then decreased with holding time increasing, and the optimal holding time is 30 min.(2) The optimal addition amount of siderite roasting product for bituminous coal and anthracite are 1.5% and 0.5%, respectively. The combustion rate of bituminous coal and anthracite are found to increase by 42.5% and 9.13% with siderite roasting product under the optimum amount. The TG-DTG results showed that ignition temperature is decreased, other combustion characteristic parameters are improved, and the combustion and burnout index of bituminous coal are increased by 10.7% and 49.2%, respectively.(3) The optimal addition amount of mill scales for bituminous coal and anthracite are 1% and 1.5%, respectively. The combustion rate of bituminous coal and anthracite are found to increase by 21.31% and 7.53% with mill scales under the optimum amount. The TG-DTG results indicated that the combustion characteristic parameters are also improved. The heat release of bituminous coal is increased from 4.54 kJ/mg to 4.73 kJ/mg, and increased from 4.3 kJ/mg to 4.63 kJ/mg for anthracite.(4) The DSC curves showed that the pyrolysis and semi-coke combustion process of bituminous coal and anthracite are improved with siderite roasting product. The semi-coke combustion process of bituminous coal is promoted with mill scales, in addition, the pyrolysis process of anthracite can be promoted with mill scales.