Improving reducibility of iron ore pellets by optimization of physical parameters

Abstract

Reducibility of iron bearing material is an important property which represents its suitability of reduction in iron making furnaces. It has direct influence on improving productivity and lowering energy consumption in iron making process. The reducibility of iron ore pellets of a specific chemistry can be improved by the optimization of physical parameters such as induration temperature, improving size distribution of fines, improving apparent porosity etc. In this study, the reference pellet is prepared in a typical plant condition and the properties of the reference pellet are considered as base value to improve reducibility index (RI) maintaining other properties at the acceptable limit without altering pellet chemistry. Optimization of induration temperature at the 1250-1275 ºC shows around 74 % RI, which is 5 points more than the base value of 69.5 %. Furthermore, on optimizing additives size, such as limestone fines and anthracite coal fines at-350 mesh and induration temperature of 1250-1275 ºC, RI is improved to 77 %, i.e., 8 points improvement is achieved with respect to the base value.

Innovative Development on Agglomeration of Iron Ore Fines and Iron Oxide Wastes

“…Investigators have tried to improve the reducibility by changing different parameters mainly through the change in chemistry and phase formation by different additives and fluxes. However, in our study reducibility index (RI) of hematite ore pellet has been increased with respect to the current level at the plant (Tata Steel, India) (Pal et al 2017b). However, other properties were maintained in the acceptable limit.…”

“…Optimum values of parameters have been found as induration temperature: 1275°C, lime stone size: below 350 mesh, coal size: below 350 mesh, for the iron ore Blaine fineness of 2855 cm 2 /g. The properties of pellets with these optimized values are shown in Table 7 (Pal et al 2017b). It is obvious from the table that reducibility index (RI) could be improved by 7-8% point and other properties viz.…”

“…This has been done by optimizing the physical parameters of pelletizing such as induration temperature, size distribution of fines, and improving apparent porosity without changing any chemistry of green pellets or additives (Pal et al 2017b). The effect of induration temperature on reducibility of iron ore pellet is shown in Figure 15 (Pal et al 2017b) that it decreases with increasing induration temperature. However, too much decrease in induration temperature may hamper the strength and other properties of pellet.…”

A Numerical Study on the State of the Blast Furnace Thermal Reserve Zone under Different Starting Temperatures of Coke Solution Loss Reaction

“…A method to weaken the unfavorable kinetic effect of the TRZ state change after decreasing the CSLR starting temperature on the indirect reduction is to improve the kinetic conditions of the indirect reduction, except temperature. In this study, the kinetic conditions of the indirect reduction are improved by increasing the reducibility of iron ore [18][19][20][21][22] or increasing the furnace top pressure. [23][24][25] Increasing the reducibility of iron ore to improve the kinetic conditions of indirect reduction is based on the principle that, according to the definition of iron ore reducibility, [26] the higher the reducibility of iron ore, the easier it is to lose the oxygen combined with iron in the iron ore by a gas-reducing agent, which implies a higher the reduction rate of the iron ore. For example, Yokoyama reported that when the ratio of carbon composite iron ore with high reducibility was 10%, the indirect reduction degree increased from 70.3% to 75.4%, and the CO utilization efficiency increased from 54.6% to 55.2% in a BF inner reaction simulator test.…”

Preparation of MgO added iron ore pellets and effects on a pilot scale blast furnace operation

“…Iron ore pellets as the indispensable burden of blast furnace show many benefits, such as high iron grade(> 63%TFe), high physical strength and uniform and size distribution, high and even porosity, less loss on ignition or volatiles, easy reducibility, and lower abrasion during transportation and use [1]. In recent years, under the pressure of energy saving and emission reduction in the iron and steel industry, the proportion of pellets charging into the blast furnace increase, and higher requirements were put forward for the quality and metallurgical performances of the pellets [2][3][4][5][6][7]. By increasing the content of MgO in iron ore pellets, not only the metallurgical performances of pellets are improved, but also the MgO content in sinter (another burden of blast furnace) decrease, because the excess MgO in sinter causes many negative effects such as the sintering rate, the fuel rate, and the sinter strength and reducibility deteriorate [8][9][10][11].…”