Reagents for Desulphurization of Hot Metal...

Reagents for Desulphurization of Hot Metal Sulphur (S), present in solid steel as iron sulphide (FeS) inclusions, has several detrimental effects on steel processing and on steel’s physical properties. During deformation, the iron sulphide inclusions act as crack initiation sites and zones of weakness. Such inclusions from sulphur adversely affect steel’s toughness, ductility, formability, weldability, and corrosion resistance. An increase in manganese (Mn) however, helps prevent formation of iron sulphide, which is highly detrimental to steel’s hot workability and also leads to severe cracking. Sulphur is such an undesirable element in steel that its removal is desired. The ever increasing requirements to steel properties and the growing demand for steel qualities and quantities with lowest sulphur contents of down to 0.001 %, has made it necessary for the steel makers to carry out the desulphurization of hot metal. Presently hot metal is regularly being desulphurized to below 100 ppm, and in some steel plants, to 10 ppm. Besides the increased requirements of steel quality, other reasons which necessitate desulphurization of hot metal are reduced scrap quality and increasing cost of high quality iron ores. In the desulphurization process, powdered desulphurization reagents are injected into the hot metal through an immersed lance using an inert carrier gas such as argon or nitrogen, as shown in Fig 1. Since desulphurization is a diffusion-controlled reaction, and related to the reactive surface area available for reaction, the desulphurization reagents are to be as fine grained as possible. However, flowability is reduced with very fine grains and hence it is necessary to find an optimum between efficiency and conveying ability. In order to obtain good flow characteristics, normally a fluxing agent is added during the grinding operation, so that pneumatic transport during injection does not pose any problems. Fig...

Coke Oven Gas Injection in a Blast Furnace Jul19

Coke Oven Gas Injection in a Blast Furnace...

Coke Oven Gas Injection in a Blast Furnace  The iron and steel industry is one of the main consumer of energy and hence responsible for high emissions of carbon di oxide (CO2). Despite remarkable decrease in specific CO2 emissions by most of the steel plants, the total amount of CO2 emissions is growing across worldwide due to the continuous increasing of steel production which has reached to a level of 1606 million tons in 2013. Nowadays the steel industry is facing an increasing demand to minimize the energy consumption and gas emissions especially from ironmaking processes. The efficient use of byproduct gases is essentially important for the profitability of steel plant operation due to the high energy volumes and the costs involved. The injection of coke oven gas (COG) into the modern blast furnace is one of effective measures for steel industry to achieve low carbon ironmaking, energy saving and emission reduction. Coke is an essential input to the iron making process and is produced by heating coal in coke ovens. To make coke, coal is heated in the absence of oxygen to drive volatile matter from it. COG is produced as a byproduct of the process in case of byproduct coke oven batteries normally installed in steel plants. The specific amount of COG generated during coke making in the byproduct coke ovens is in the range from 290 to 340 N cum/t of coal charge depending on the volatile matters in the coal charge. The COG is currently used after its cleaning from tar, naphthalene, raw benzene, ammonia, and sulfur for heating of blast furnace stoves, ignition furnaces in sintering plant, heating furnace in rolling mills and electric power generation in power plant. The COG has a composition which consists of around 55...