Use of Iron Ore Pellets in Blast Furnace Burden Jun13

Use of Iron Ore Pellets in Blast Furnace Burden...

Use of Iron Ore Pellets in Blast Furnace Burden  Pelletizing is a process that involves mixing very finely ground particles of iron ore fines of size less than 200 mesh with additives like bentonite and then shaping them into oval/spherical lumps of 8-20 mm in diameter by a pelletizer and hardening the balls by firing with a fuel. It is the process of converting iron ore fines into ‘uniformed sized iron ore pellets’ that can be charged directly into a blast furnace. Fig 1 shows iron ore pellets. Fig 1 Iron ore pellets  There are several iron ore pelletizing processes/technologies available. However, currently, straight traveling grate (STG) process and grate kiln (GK) process are more popular processes. The physical properties of iron ore pellets are given below. •     Size – 8-20 mm •     pH (40 gm/L, 20 deg C; slurry in water) – 5.0 – 8.0 •     Melting point – 1500-1600 deg C •     Bulk density –  2.0 -2.2 t/Cum •     Tumbler index (+6.3 mm) – 93-94 % •     Abrasion index (-0.5 mm) – 5-6 % •     Compression strength (daN/p) – Around 250 •     Porosity – > 18 % The chemical analysis of iron ore pellets is given below. BF grade                     DRI grade Fe                                            %         63 – 65.5                       65 -67.8 SiO2 + Al2O3                         %              < 5                                 <5 CaO + MgO                            %           Up to 3                      Up to 0.10 P, max                                     %              0.05                              0.05 S, max                                     %              0.01                              0.01 Basicity, min                           %              0.5 Disintegration (-3.15 mm)   %                                                     2 Swelling Index                        %            13-18 Reducibility                             %                65 Different ISO standard tests for pellets are given in Tab 1 Tab 1 ISO standard tests used for BF pellets ISO standard test Measurement values Purpose ISO 4700 /Crushing strength  daN Pellet cold strength ISO 3271 /Tumble strength Fractions +6.3 mm...

Iron ore pellets and Pelletizing processes Feb23

Iron ore pellets and Pelletizing processes...

               Iron ore pellets and Pelletizing processes Pelletizing is a process that involves mixing very finely ground particles of iron ore fines of size less than 200 mesh with additives like bentonite and then shaping them into oval/spherical lumps of 8-16 mm in diameter by a pelletizer and hardening the balls by firing with a fuel. It is the process of converting iron ore fines into “Uniformed Sized Iron Ore Pellets” that can be charged directly into a blast furnace or into a furnace used in the production of Direct Reduced Iron (DRI). The pellets are shown in Fig 1 Fig 1 Iron ore pellets The typical properties of the pellets is given in Table 1 Table 1 Properties of Pellets Chemical analysis(On dry basis) Unit Value Tolerance Fe % 65 Minimum FeO % 0.3 Maximum SiO2 + Al2O3 % 5 Maximum CaO % 0.03 ± 0.01 MgO % 0.06 ± 0.01 Basicity % 65 Maximum Phosphorus % 0.05 Maximum Physical properties       Bulk Density t/Cum 2.2 ± 0.2 Tumbler Index % 93 Minimum Abrasion Index % 3 Min ± 0.5 % Cold Crushing Strength (Avg) Kg/P 250 Minimum Size analysis   8 – 16 mm 94 Minimum -5 mm % 2 Maximum +16 mm % 4 Maximum Metallurgical properties   Porosity % 18 Minimum Reducibility % 62 Minimum\ Process technology There are four stages involved in the production of pellets. They are: Raw material preparation. Formation of green balls or pellets Induration of the pellets Cooling, storage and transport of pellets During the process for pelletization iron ore concentrate from iron ore beneficiation plant is dried and heated to about 120 deg C. The dried material is fed to the ball mill for grinding. Concentrate / ground iron ore of typical size...