Understanding Blast Furnace Ironmaking with Pulverized Coal Injection Nov04

Understanding Blast Furnace Ironmaking with Pulverized Coal Injection...

Understanding Blast Furnace Ironmaking with Pulverized Coal Injection Injection of pulverized coal in the blast furnace (BF) was initially driven by high oil prices but now the use of pulverized coal injection (PCI) has become a standard practice in the BF operation since it satisfies the requirement of reducing raw material costs, pollution and also satisfies the need to extend the life of ageing coke ovens. The injection of the pulverized coal into the BF results into (i) increase in the productivity of the BF, i.e. the amount of hot metal (HM) produced per day by the BF, (ii) reduce the consumption of the more expensive coking coals by replacing coke with cheaper soft coking or thermal coals, (iii) assist in maintaining furnace stability, (iv) improve the consistency of the quality of the HM and reduce its silicon (Si) content, and (v) reduce greenhouse gas emissions. In addition to these advantages, use of the PCI in the BF has proved to be a powerful tool in the hands of the furnace operator to adjust the thermal condition of the furnace much faster than what is possible by adjusting the burden charge from the top. Pulverized coal has basically two roles in the operation of a BF. It not only provides part of the heat required for reducing the iron ore, but also some of the reducing gases. For understanding the HM production in a BF with the injection of pulverized coal, it is necessary to understand what is happening inside the BF as well as the chemical reactions and the importance of permeability within the furnace and how the raw materials can affect this parameter. The BF is essentially a counter-current moving bed furnace with solids (iron ore, coke and flux), and later molten...

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...