Mini Blast Furnace and Iron making Oct10

Mini Blast Furnace and Iron making...

Mini Blast Furnace and Iron making Mini blast furnaces (MBF) are generally viewed as miniature versions of the conventional large blast furnaces (BF). These furnaces are ideally suited for small scale operations. In fact, they are basically the forerunner to modern conventional last blast furnaces and hence they have operated for a longer period of time. MBFs are located in many countries but the majority of the MBFs are located in China, India, Brazil and Indonesia. Plant availability as well as the perfection achieved in this technology has made MBF an accepted route for iron making. Further, these days, most of the technologies of design, burdening and operation which have become the norm for today’s modern large furnaces have also been adopted in MBFs. MBF is a vertical shaft furnace with a crucible like hearth. Burden materials consisting of iron ore, coke or charcoal used as a reducing agent as well as fuel, and fluxes, usually limestone or dolomite, are charged into the top of the furnace. The furnace works on the principle of a counter current reactor. As the burden descends through the shaft, it is preheated and pre-reduced by the hot gases ascending from the furnace bottom. The gases are generated by introducing hot air blast enriched with oxygen through tuyeres. The hot blast burns the reducing agent, producing reducing gases and heat required for the reduction process taking place in the furnace. The reduced burden material melts to form HM (liquid iron) which becomes saturated with carbon and descends to the hearth. The fluxes combine with the impurities in the burden materials to produce a molten slag which accumulates on top of the liquid iron in the hearth. Liquid iron and liquid slag are periodically tapped from the furnace. MBF exhibits...

Blast Furnace Top Charging Systems Oct11

Blast Furnace Top Charging Systems...

Blast Furnace Top Charging Systems In earlier days, blast furnace (BF) top used to be open with the gas from the furnace escaping into the atmosphere and burning, causing environmental issues while wasting considerable energy. By 1850 as the furnace size increased, the furnace top could be closed. A single bell and hopper arrangement could be used for charging the furnace that kept the top of the furnace closed and sealed. The single bell and hopper system permitted large quantity of gas to escape every time the bell was opened. Soon a second bell and hopper was added above the first so that a gas tight space could be provided between the two bells to prevent the blast furnace gas escaping when the small bell was opened. The upper bell and hopper did not have to be as large as the lower one because several charges could be deposited through it on the lower bell and the upper bell could be closed before the lower bell was opened for dumping the charges in the furnace The two bell system continued to be the only charging system for the blast furnaces around the world till S.A. Paul Wurth in Luxembourg, developed bell less top (BLT) charging system and the first successful industrial application of BLT charging system was in 1972. Soon BLT charging system took over from two bell charging system since it provided a number of advantages to BF operators. During 2003, Siemens VAI introduced Gimbal concept of charging. This charging system has been successfully used for Corex and Finex processes for charging. The first application of Gimbal for charging a blast furnace was in 2009, when it has been used for C blast furnace of Tata steel. Two bell charging system The two...