Understanding Sinter and Sinter Plant Operations Mar15

Understanding Sinter and Sinter Plant Operations...

Understanding Sinter and Sinter Plant Operations               Sintering is a process of agglomeration of fine mineral particles into a porous and lumpy mass by incipient fusion caused by heat produced by combustion of solid fuel within the mass itself. The sintering process is a pre-treatment step in the production of iron, where fine particles of iron ores and also secondary iron oxide wastes (collected dusts, mill scale etc.) along with fluxes (lime, limestone and dolomite) are agglomerated by combustion.  Agglomeration of the fines is necessary to enable the passage of hot gases during the blast furnace operation. Sintering has been referred to as the art of burning a fuel mixed with ore under controlled conditions. It involves the heating of fine iron ore with flux and coke fines or coal to produce a semi-molten mass that solidifies into porous pieces of sinter with the size and strength characteristics necessary for feeding into the blast furnace. Although simple in principle, sintering plant requires that a number of important factors in its design and operation be observed to attain optimum performance. A simplified schematic flow diagram of sintering process is at Fig 1.  Fig 1 Simplified flow diagram of a sintering process  There are basically the following three types of sinters. Non flux or acid sinters – In these sinters no flux is added to the iron ore in preparing the sinter mix. Non flux sinters are very rarely being produced these days. Self fluxing or basic sinters – These are the sinters where sufficient flux is added in the sinter mix for producing slags of desired basicity (CaO/SiO2) in blast furnace taking into account the acidic oxides in the blast furnace burden. Super flux sinters – These are the sinters where sufficient flux is added in...

The Sintering Process of Iron Ore Fines Mar09

The Sintering Process of Iron Ore Fines...

                   The Sintering Process of Iron Ore Fines  Sintering plants are normally associated with the production of hot metal in blast furnaces in integrated steel pants.  The process of sintering is basically a pre-treatment process step during iron making to produce charge material called sinter for the blast furnace from iron ore fines and also from metallurgical wastes (collected dusts, sludge and mill scale etc.). The sintering technology was originally developed for the purpose of using the iron the metallurgical waste of a steel plant and iron ore fines in the blast furnace. But currently the focus has changed. Now the sintering process aims to produce a high quality burden for the blast furnace. Today sinter is the main metallic burden for a large blast furnace.  The Principle of sintering  The principle of sintering involves the heating of iron ore fines along with flux and coke fines or coal to produce a semi-molten mass that solidifies into porous pieces of sinter with the size and strength characteristics necessary for feeding into the blast furnace. It is basically an agglomeration process achieved through combustion. The Product Sinter The product of the sintering process is called sinter and is having good following quality characteristics Chemical analysis Grain size distribution Reducibility Sinter strength Typical properties of sinter are given in Tab 1   Tab 1  Typical properties of sinter Item Unit Value Fe % 56.5 to 57.5 Feo % 6.0-8.0 SiO2 % 4.0 to 5.0 Al2O3 % 1.8 to 2.5 CaO % 7.5 to 8.5 MgO % 1.6 to 2.0 Basicity (CaO/SiO2) 1.7 to 2.9 ISO Strength  (+6.3mm) % >75 RDI (-3 mm) % 27-31 The product sinter is shown in Fig. 1.  Fig 1   Sinter Advantages of adding flux to sinter Sinters are classified into...

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...