Mathematical Model of Air Flow during Iron Ore Sintering Process

摘要

Sintering of iron ore fines is carried out by first agglomerating iron ore fines, coke breeze, limestone, dolomite or dunite or olivine, some revert materials generated in steel works and sinter fines with addition of lime and water. The agglomerated material is layered on a sinter strand in a packed bed. The bed is ignited to initiate sintering process. During the ignition, hot gases (generated by combustion of coke oven gas) are drawn into the bed raising the temeprature of top layer. By the time ignition is finished, the coke particles in the top layer of the bed attain ignition temperature. From this point onwards, air is sucked down through the bed to sustain combustion of coke to supply heat energy for sintering process. The air drawn through bed gets first preheated by its passage through the upper layers of the bed, then sustains combustion of hot coke breeze particles, and finally gets cooled by evaporating the water from the bed immediately below the combustion zone. The gases leave the bed and pass as waste gas. The combustion zone moves down through the bed as sintering proceeds and at the conclusion of the process, all the fuel has been consumed and whole mass on the bed has been sintered. During the process of sintering several physico-chemical phenomena pertaining to the flow of gases through the bed of packed granules take place which govern the heat transfer and thereby temperature profile in the bed. Depending on the nature of temepratuer profile in the bed and the composition of raw materials, rate of sintering process (formation of various phases and texture development) gets decided which is correlable with the quality and productivity of sinter. The typical temperature profiles as measured in laboratory pot sinter and commercial sinter plant are shown in Figs. 1 & 2 respectively.