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 Cast House Equipments May16

Blast Furnace Cast House Equipments...

Blast Furnace Cast House Equipments The cast house floor of a blast furnace has always been one of the most dangerous working places in a blast furnace. Apart from working in an atmosphere which includes toxic gases, fumes, and dust, the operators have to perform hard and heavy manual work close to hot metal and slag runners and ladles filled with hot metal. Before the invention and installation of cast house equipment, the tapholes were opened and closed manually. Opening was done by means of steel bars and sledgehammers, whereas the taphole was closed by repeatedly ramming small amounts of clay or refractory material into the taphole, again with the help of long, heavy bars. In addition, on blast furnace, the blast had to be stopped, since it was impossible to close the taphole properly against the blast furnace pressure. This stoppage of the blast resulted in regular losses of production. Samuel W. Vaughen of USA invented the first mud gun in 1895. His pneumatic mud gun machine operated with steam, had a detachable nozzle that had to be swung open to load the taphole mass. In 1901 there was another big change in taphole practices when Ernst Menne of Germany invented the oxygen lance. By blowing oxygen through a 1/8 inch pipe and igniting it, it was now possible to open the taphole very quickly compared to the pure manual method. The first records of taphole drills is found around 1921 when Edgar E. Brosius and Joseph E. Judy of USA suggested a method of drilling the taphole for its opening. Brosius even invented a combined drilling and lancing apparatus in 1924. An excellent cast house setup is an important necessity for a low cost, high productivity blast furnace since an effective operation...

Blast Furnace and its Design Dec03

Blast Furnace and its Design...

Blast Furnace and its Design The design of a blast furnace (BF) plays a fundamental role in its reliable operation, metallurgical performance, sustained high productivity and long campaign life. The design of a modern BF is generally based on the concept of a free standing unit with a surrounding building structure, providing access to the furnace and support for the BF gas system. BF design is to provide for the optimization of the burden and gas flow with a consideration of the potential raw material and operating conditions for the furnace throughout its campaign. BF design is required to integrate the properties of the shell, the cooling elements and refractory lining in order to ensure the well balanced overall operation of the BF complex. The choice of the right refractories and cooling systems at each zone of the BF is critical for successful, economic and, above all, safe operation of the BF. All the equipment necessary for smooth BF operation are to be integrated while designing a blast furnace. Major of these equipments are top charging equipment, cast house equipment (clay guns, tap hole drills, trough cover manipulators, tilting runners for iron and slag, bar changers, and jack dam drills etc.), tuyere stocks, various type of valves (e.g. hot blast valves, snort valve, bleeder valves, equalizing/relief valves, flow control valves, and isolation valves etc.), Different probes (e.g. above burden temperature probes, and sub-burden gas probes etc.), mechanical stock line recorders, moveable and fixed throat armor, stock line ignition lances, and profile meters etc. The design of BF should provide for equipment which has a proven reputation for reliability, durability, and high performance in the arduous conditions of the BF environment. The operation of a modern BF is quite complex and it needs necessary automation...

Blast Furnace Cast House and its Operation Jun06

Blast Furnace Cast House and its Operation...

Blast Furnace Cast House and its Operation  The blast furnace (BF) cast house is the working area where hot metal and liquid slag are tapped from the blast furnace and either poured into ladles (torpedo car or open top ladle) or led off for solidification (pig casting and slag granulation) or treatment (cast house desulphurization). A good trouble free cast house operation is an important requirement in a high productivity blast furnace for low cost operation. The cast house functional design, operational practice, refractory technology, automation and environmental requirements are important issues which are required to be looked into to meet the demands for greater reliability and output from the cast house. In any blast furnace cast house is the most labour intensive area in the entire BF operation. Its design must be fully integrated with the expected hot metal production, hearth volume, and tapping practice whilst minimizing use of labour, maintenance, materials and improving working environment. The prime objective is to remove the liquid iron from the blast furnace at a casting rate and through a number of casts per day that is determined by the smelting rate, effective hearth volume, and the desire to maintain the hearth in a ‘dry’ condition rather than by the availability of the cast house troughs, runners and cast house equipment. Typical lay out of a BF cast house is shown in Fig 1 Fig 1 Typical layout of a BF cast house  The design and operation of the cast house must improve the efficiency of BF operation with respect to the following parameters. Improvement in the working conditions for workmen engaged in tapping of the hot metal and liquid slag Reduction in the losses of heat from the hot metal by maintaining its temperature Reduction in...

Blast furnace slag granulation at cast house May05

Blast furnace slag granulation at cast house...

Blast furnace slag granulation at cast house Blast Furnaces normally generate 250 to 350 Kg of liquid slag for every ton of hot metal produced. This molten slag is at around 1400 – 1550 deg C temperature.  Till seventies blast furnace (BF) slag was considered a waste product and was being dumped at a convenient place away from the blast furnace.  During early seventies granulation of molten slag with high pressure water started near the slag dumps. The processes of granulation of molten slag were developed during late seventies and early eighties. The processes differ in the method of dewatering of the wet granulated slag. Today granulation of molten BF slag is the well accepted technology and is being used in most of the blast furnaces around the world. In India the credit of commissioning the first cast house slag granulation plant goes to Visakhapatnam Steel Plant when the first blast furnace of the plant was commissioned on 28th march 1990. Major slag granulation processes presently under operation are OCP granulation system, Gipromez designed plants, Rasa system and INBA slag granulations plants of Paul Wurth, modified INBA process or IDE process etc. Concept of slag granulation The process of slag granulation involves pouring the molten slag through a high pressure water spray in a granulation head, located in close proximity to the blast furnace. Granulation process is the controlled quenching of the slag in cold water which does not give time for crystalline growth to take place. Large volume of water is required (10 parts of water to 1 part of molten slag being optimum). During this process of quenching, the molten slag undergoes accelerated cooling under controlled water flow condition and gets converted into glassy sand with 97 % of the solid granulated...