Hydrogen gas and its use in Iron and Steel industry...

Hydrogen gas and its use in Iron and Steel industry Hydrogen is a chemical element, ranking first in the periodic table with element symbol of ‘H’. The (atomic number of hydrogen element is 1 and atomic weight is 1.008. It is the smallest atom in the universe and the simplest element in nature. Its molecule consists of two hydrogen atoms. It is the lightest gas, being about 1/14 times as dense as air. It has three isotopes named (i) protium, (ii) deuterium, and (iii) tritium. Pure hydrogen is odourless, colourless and tasteless. Hydrogen has lowest atomic weight of any substance and therefore has very low density both as a gas and a liquid. The vapour density of hydrogen at 20 deg C and 1 atmosphere pressure is 0.08376 kg/cum. The specific gravity of gaseous hydrogen is 0.0696 and hence, it has around 7 % the density of air. The density of liquid hydrogen at normal boiling point and 1 atmosphere pressure is 70.8 kg/cum. The specific gravity of liquid hydrogen is 0.0708 and is thus, it has around 7 % the density of water. Hydrogen is a liquid below its boiling point of -253 deg C and a solid below its melting point of – 259 deg C at atmospheric pressure. It is non-toxic but can act as a simple asphyxiant by displacing the oxygen in the air. When hydrogen is stored as a high-pressure gas at 250 kg/cum and atmospheric temperature, its expansion ratio to atmospheric pressure is 1:240. The molecules of hydrogen gas are smaller than all other gases, and it can diffuse through many materials considered airtight or impermeable to other gases. This property makes hydrogen more difficult to contain than other gases. Leaks of liquid hydrogen evaporate very quickly since the...

Midrex Process for Direct Reduction of Iron Ore Apr09

Midrex Process for Direct Reduction of Iron Ore...

Midrex Process for Direct Reduction of Iron Ore Midrex is an ironmaking process, developed for the production of direct reduced iron (DRI). It is a gas-based shaft furnace process is a solid state reduction process which reduces iron ore pellets or lump ore into DRI without their melting using reducing gas generally formed from natural gas. The principle of the reduction process using reducing gas is shown in Fig 1. Fig 1 Principle of reduction process using reducing gas The history of the Midrex process goes back to 1966 when Donald Beggs of the Surface Combustion Corporation conceives the idea for the Midrex direct reduction process.  The original process was developed by the Midland-Ross Co., which later became Midrex Technologies, Inc. It is now a wholly owned subsidiary of Kobe Steel. A pilot plant was built in Toledo, Ohio in 1967. The first commercial plant, having a production capacity of 150,000 tons per year, was built in Portland, Oregon, in 1969. The genius of the Midrex process is its simplicity. Donald Beggs’ concept of combining stoichiometric natural gas reforming with shaft furnace direct reduction of iron ore was a breakthrough innovation which has stood the test of time. Since 1969, DRI production through Midrex process has crossed 500 million tons. Production from many of the Midrex plants exceeds their design capacity. Each year since 1987, DRI production through Midrex process is over 60 % of the total global production of DRI. The process was immature in 1978, when Kobe Steel began the construction of a plant with a production capacity of 400,000 tons/year in the State of Qatar. Kobe Steel significantly modified the design, exploiting the company’s technologies developed through blast furnace operation, and stabilized the then new process. On the other hand, Midrex...