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...

Technologies for Improving Blast Furnace Operating Performance Oct03

Technologies for Improving Blast Furnace Operating Performance...

Technologies for Improving Blast Furnace Operating Performance A blast furnace (BF) is an investment in the future. Hence it is necessary that there is the proper dimensioning of all equipment, systems and components as well as incorporation of technologies which assure the desired production and quality so that improved performance of the blast furnace can be achieved. This is particularly true when blast furnace goes for capital repairs. During capital repairs incorporation of technologies for the improvement of blast furnace operating performance also meet the new demands placed on the performance of the blast furnace, personnel safety, lower maintenance requirements and environmental compliance. A key challenge for blast furnace operators has always been to assure a continuous and reliable supply of hot metal for the steel melting shop at uniform quality and at the lowest possible costs. Any interruption in the production of hot metal can lead to potential standstills in the downstream production and processing facilities. Downtime must be kept to a minimum while the blast furnace campaign life must be extended for as long as possible. Fluctuations in blast furnace operating parameters must be avoided for uniform hot metal quality, which is only possible through the application of proper technologies as well as sophisticated automation and process control solutions. There are several technologies (Fig 1), which when adopted greatly improve blast furnace operating performance and increase its efficiency both with respect to productivity and fuel consumption. This results into improved hot metal production rate per unit of volume of blast furnace and reduced consumption of BF coke. Some of the major technologies are described below. Fig 1 Technologies for improving BF operating performance Increase in furnace internal volume By using advanced technologies for furnace refractory lining and furnace cooling, it is possible...

Generation of Hot Air Blast and Hot Blast Stoves Apr18

Generation of Hot Air Blast and Hot Blast Stoves...

Generation of Hot Air Blast and Hot Blast Stoves            A hot blast stove is a facility to supply continuously the hot air blast to a blast furnace. Before the blast air is delivered to the blast furnace tuyeres, it is preheated by passing it through regenerative hot blast stoves that are heated primarily by combustion of the blast furnace top gas (BF gas). In this way, some of the energy of the top gas is returned to the blast furnace in the form of sensible heat. This additional thermal energy returned to the blast furnace as heat reduces the requirement of blast furnace coke substantially and facilitates the injection of auxiliary fuels such as pulverized coal as a replacement for expensive metallurgical coke. This improves the efficiency of the process. An additional benefit resulting from the lower fuel requirement is an increase in the hot metal production rate. All of these have a significant effect in terms of reducing the hot metal cost. History of hot blast stoves The use of blast furnaces dates back as far as early as fifth century B.C. in China. However, it was not until 1828 that the efficiency of blast furnaces was revolutionized by preheating them using hot stoves in conjunction with the process, an innovation created by James Beaumont Nielson, previously foreman at Glasgow gas works. He invented the system of preheating the blast for a furnace. He found that by increasing the temperature to 300 deg F (149 deg C), he could reduce the fuel consumption from 8.06 tons to 5.16 tons with further reductions with higher temperatures. In 1860, the cooperative use of hot stoves with blast furnaces was further transformed by Edward Alfred Cowper by recycling the top gas...

HIsmelt process of Ironmaking Jul02

HIsmelt process of Ironmaking...

HIsmelt process of Ironmaking  HIsmelt is short for high intensity smelting. It is a direct smelting process for making liquid iron straight from the iron ore.  The process has been developed to treat iron ore fines with minimum pretreatment, making the process more flexible in terms of the quality of iron ore it can treat.  The process allows the use of non coking coal and iron ore fines with significant impurities. The core of the HIsmelt process is the smelt reduction vessel (SRV) which has a refractory lined hearth and water cooled upper shell. The process is carried out in this vessel. The refractory hearth contains the molten iron bath and liquid slag. The main product of the process is liquid iron or hot metal which can be used in steel melting shop or cast in pig casting machine to produce pig iron. The byproduct of the process is slag and the off gas. Main features of the process HIsmelt process has the following unique features. The method of solid injections using high speed lances ensure that the capture efficiency in the melt is high and even ultra fines can be used directly. The ‘natural’ 5 % to 6 % FeO level in the slag in conjunction with the metal carbon at 4 % creates conditions for strong partition of phosphorus from metal to slag. Typically around 80 % to 90 % of phosphorus goes to slag. Coal performance has virtually no dependence on particle morphology, since the coal is ground fine for injection. Historical process development  The origin of the HIsmelt process is traced back to the bottom blown oxygen converter process (OBM) and the evolution of the combined blowing steel making process developed by Klöckner Werke at their Maxhütte steel works.  CRA (now Rio...