Theory and Practice of Sintering of Iron ore Nov25

Theory and Practice of Sintering of Iron ore...

Theory and Practice of Sintering of Iron ore Sintering of iron ore is a generic term which is used to describe the process whereby a sinter mix (raw mix or green mix) of iron ore fines, fluxes, fuel (coke breeze) and plant return fines (e.g. mill scale, blast furnace dust, and returned sinter fines etc.) are converted into a particular form of agglomerate. It consists of heating the sinter mix with a particle size of less than 10 mm to such a temperature that surface of each grain of the charge mix starts to melt and the formed melt creates liquid bridges between grains, which, after solidification, ensure formation of a solid porous material called sinter having a screened size normally of 5 mm to 30 mm (upper size can go upto 50 mm to suits local requirements), and which can withstand operating pressure and temperature environment inside the blast furnace (BF). The process of sintering is a thermal operation involving melting and assimilation reactions. The first stage of the sintering process is the formation of the melt which involves the reaction between fine iron ore particles and fluxes. The initial melt is generated from adhering fines during heating via reaction between iron ore and fluxes. Then, nucleus particles are partially assimilated or dissolved into the primary melt to form more melt. Before complete melting is achieved, the sintering temperature drops due to the short residence time at the maximum temperature and then the melt solidifies and mineral phases precipitate, resulting in the formation of the bonding phases. During the sintering process, the chemical reactions are taking place at high temperature and the iron ore and fluxes are combined together and form a sinter cake composed of iron ore, silico-ferrites of calcium and aluminum...