Patent CA-2988472-A1 (CA)
Inventor: NABI GHULAM
IPC: C10B33/12
Filed: 2017-12-11
Abstract: A zigzag route of making a mistake and then correcting it is practiced in the major route of integrated steel production. Impurities (sulfur and metallic residues) containing Coke is produced and is charged into blast furnace. An impure inferior product is produced. Gases containg charge particles are produced because of high blast requiring recovering and agglomerating these in sintering plant. Next two processes namely BOF and Ladle Metallurgy are to rectify the previous mistake in iron making. Steel is cast in large size ingots and blooms having internal and external defects so surface scarfing and reheating and size reduction, scale disposing is done until the product becomes appropriate for next operation of rolling. Lot of cutting and re-joining is done producing defective portions. The rolling operation is done in air and then storing in air. The rusted surface has to be prepared by annealing and pickling for next operation of coating. Pickling creates deep defects and non uniformity in steel structure. Cold rolling is liable to produce micro-cracks in the internal structure of metal. Against this back ground; In the presence process, steel is produced directly using high purity gases and iron ore .Unwanted ingredients in iron ore are slaged off. Alloying elements when desired are added some in ores and some after steel is formed. Liquid steel is changed into micro particles, unwanted metals are separated by magnetic separation. Nickel and cobalt may be separated by carbonyl treatment. Steel produced is interfacial free steel. Near net size products are produced which are given on line finishing and heat treatment in controlled atmosphere. Strip steel may be diverted for coil formation. Other products may undergo further treatment cold rolled and coated. Final mechanical operations are performed and steel is marked for shipment. Top gases from blast furnace (which is now a Direct Steel Making Reactor) are led to an regeration scheme which comprises the steps of: 1. Changing oxidized gases (CO2, H2O) back to reducing gases CO, H2. Top gases are made to react with hydrocarbon reductant. The reductant could be coal, or crude oil or gaseous condensate, fossil fuels (annual crops residues), house hold garbage. Any of these could be alone or an appropriate mixture of more than one, selected with special consideration of their composition. The reactor used should be able to go to 1200 C with a jacketed heating system carrying high temperature heating media which can supply heat to the inside process of the generating reactor. This could be new set-up, but a modified coke oven is appropriate for this purpose. This modification is shown in the attached illustration. 2. The re-generated gases undergo suffer removal. 3. Nitrogen is removed from the gaseous stream. The purified gases go to a holding system from where gases are provided to: (i) Reheating system (stoves) to bustle pipe to tuyers (ii) To heat the stoves and exit of the stove heating system go to coke oven under firing. (iii) Under firing of coke ovens. (iv) CO,H2 gases are combined for various uses Figure 2, A Blast Furnace changed into high intensity direct steel making apparatus and process. Figure 2 . A Blast furnace changed into high intensity direct steel making apparatus. 3 A continuous process Steel Mil This above named invention is of far reaching consequences for integrated Blast furnace Bof steel making technology. It will create a more precise, straight forward, continuous process from start to finish liable to automation and control, without generation solid or gaseous waste. Most of the present heavy set up will be utilized for this new technology with some external modifications. Units which become redundant will be by-passed. Present unit operations of Sintering plant, Steelmaking, De-oxidation, Ingots, Blooms, Slab casting, reheating furnaces, scale disposal and much of cutting and welding will give way to the point operations with introduction new on line operations which will make the product better in mechanical properties and resistant to external damages. I will first describe the basic unit namely coke ovens which is base of all this change. It is the production of high purity high energy gases CO,H2 in oven operation which make all this possible. Further separating these gases into CO and H2 and joining with these O2 and N2 from air will make the foundation of new chemical world. While fulfilling the needs for new requirements from these ovens; these will also provide some petrochemicals which use to be provided by coking process which is now stopped. Coke oven complex produces coke, byproducts, and coal gases from coal .The coke oven byproduct plant is designed for production solid fuel for process needs to cover the steel mill's own requirement and some excess coke for foundry purposes. The requirements for the steel mill in solid fuel for process needs are made up of the blast furnace demand for the metallurgical coke. There is an additional demand for coke breeze for sintering plant refractory making (fire clay), coke oven and by product plant is also part of coke production plant. For all these requirements the coke and breeze is 960 thousand tons per annum, for a steel mill of one million tons of steel per annum. The coke oven and by product plant has been designed as follows: -coal handling plant -coke oven plant -by-products plant-Auxiliary facilities: water supply, sewerage, steam supply, electric power supply, repair posts, laboratory, recoveries plant facilities, communication and signaling facilities The cove oven plant consists of two coke oven batteries, 49 ovens in each, their carbonizing chambers having 30.4 cu.m effective capacity; the coal tower 3200 tons capacity and two 80 meter stacks having 3.6 m upper inner diameter. On the coke side, running along the ovens, there are quenching car tracks, the coke wharf for discharging the quenching coke from the quenching car, and the quenching station with facilities for settling and delivery of water for coke quenching. On the pushing side of the coke oven battery are coke pusher tracks and stacks with collecting and common flues. Coke ovens of under jet and control of coke oven gases and air with twin heating flues and recirculation of waste heat gases. Coke ovens to be heated with coke oven gas. Dimension of carbonization chamber. Length =15000 mm 4 Height = 5200 mm Width =410 mm Effective volume of carbonization chamber cu.m =30.3 Number of charging holes pcs =3 Number of gas off-take holes, pcs =2 Single charge 3-5 mm =22 ton Oven cycle, hours =15 By ¨ Products Recovery Plant The by product recovery plant consists of the following sections and facilities: Tar condensation and gas cooling station, Machine room Ammonium sulfate section Section of final gas cooling and purification of gas from naphthalene Sulfuric acid storage Tar and solar oil storage Gas Bleeder The following are usually produced at the by-product recovery plant: Tar Ammonium sulphate Solar oil used for generation. Gas is cooled through tubular heat exchangers, and then through electrostatic precipitator. This technology of coke production is changed to a new technology of producing high purity CO,H2 gases and hydrocarbons gases and chemicals. Changing coke production to gases production This new technology is to produce high purity CO,H2 gases ,after removal of sulfur and nitrogen from oven gases. The inputs to the oven are spend top gases, low quality coal, house hold garbage (biomass. annual crop residues) This changed technology and small changes in setup is described below and illustrated with figure 1. Ovens are changed coal or mixed hydrocarbons (coals and garbage) gasifier. The operation of coal charging machine is stopped and small charge hoppers are made over every ovens one for coal and two for mix charge. From these hoppers the materials are charged by screw feeders continuously into the oven. The gas off takes is used for gases inlet one for oxygen and one for steam or CO2. The material is gasified in side oven and bottom of the oven is made slanting so that ash is its self gathered at the exit pipe. At the exit pipe product gases which are reducing gases flow to an exit pipe upward going to previous gases collection mains and pipes, The ash is made to flow trough a controlled screw to a collecting hopper. The ash from this collecting hopper is taken away by previously coke carrying trolley. The coke gate is closed with refractory, small pipe for out going of ashes and gas is made Each oven is heated at the outside by burners using small percentage of purified product gases produced by the oven, A simplified chemical process taking place inside the oven is described as following. Assume coal as Carbon. And biomass as Carbon and H20 2C +CO2 =2CO .DELTA.H = +46,000 Kcal. C + H2O = CO +H2 .DELTA.H = + 32,000 K.cal To carry the exit gases and ash at a temperature of about 1100 C heats through the oven walls is used; this heat is supplied by the under firing of coke ovens at about 1300C. The process is not restricted by kinetics of the process but by material transport. Previously coal was used at an average of 1,5 ton per hour. Now the combine mass is processed at about 2 tons per hour. About 10 % of the product gases are recycled for energy need of the process. The operation of the coke pusher and coke receiving is stopped. The process ash from coal and biomass is taken by the coke trolley to the previous quenching stating which is used now for ash process. This ash is cooled to approx, 400 C and its iron contents and separated by a magnet separator. The rest of the ash is dissolved in caustic soda. The products are used for the preparation of zeolites. The insoluble calcium maximum salt and other are used for their separation and recovery. Nothing is thrown away. The product gases from the ovens are collected and hot gases are taken to previously by-product area. Hear first some heat energy from these is used for electricity production .These gases at about 500 C taken to impurities removal by caustic soda. Sodium sulfide is produced for market. This is explained on figure 5. Nitrogen is removed by pressure swing absorption using K type zeolite. These gases can be further changed to: CO,H2 CO2 + H2 (shift reaction) Carbon di-oxide is liquidified and transported. CO is separated by union carbides' molecular sieves SiO2/Al2O3 Production of C from CO Production of porous graphite from C Gases CO,H2 have about 30% more calorific value than natural gas. CaO, and MgO are used to establish new processes. CaO, MgO ,Al2O3 ,Na2O are in cyclic role. . Heat balance 15CaO +10Al = 5Al2O3 + 15Ca +.DELTA.H = 295 .000 Kcal 18Mg O +12 Al = 6Al2O3 +18 Mg +.DELTA.H = 174, 000 // 3[ 3SiO2+ 4Al =2Al2O3 + 3Si ] -.DELTA.H =3x 149,000 // Thus for 100 kg moles of CaO+MgO approx.35 mole silica is used to balance the energy requirement. This energy also includes energy require to volatile the Ca, Mg Na, and heat the circulating H2. Ca, Mg, which are volatilized are made to under go reaction to reduceCO, CO2 and H2O to produce C2H2and C3H4 gases which being highly unsaturated can lead to self condensation, mutual condensation and saturation reaction with H2 thus starting the whole new field of petro-chemicals, gasoline, diesel, waxes and polymers in more systematic and controlled manner than crude oil cracking technology. Energy recovery from off gases and conversion of CO2 and H2O to hydrocarbon gases is shown in figure 6 page 1 and 2. Calculations for Ca and Mg are parallel. Basic data for Ca ,CaO, Mg and MgO is given in the following -.DELTA.H f K.cal/kg.mol m.point C b.point C C p K.cal/kg.mol.0 Ca 839 1484 26 CaO 157.5 2615 - 12 Mg 649 1000 7.8 6 MgO 143 2825 3200 11.7 Mg2C3 19 - -10 Using Ca and recycling of CaO 2 CO2+ Ca = CaC2 + 4 CaO - .DELTA.H= 440 K.cal This is large amount of heat and partially this heat to be carried away for electricity generation. Circulating nitrogen will take out this heat to gas turbine. Nitrogen is 50 kg mole per minute. The product charge (CaC2 + 4 CaO ) is at about 1000 C is taken to the next reactor. CaC2 is reacted with H2O CaC2+ H2O = C2H2+CaO -.DELTA.H =-25 K.cal this heat is also taken to gas turbine Heat with CaO to recycle pipe =5 CaO @ 1000 C is going to reduction reactor C2H2 goes out and is reacted with H2 C2H2 + H2 =C2H4 .DELTA.H=- 72 K.cal C p-10 K.cal/kg.mol C .DELTA.H f ethylene= -17.K.cal/kg.mole Temperature of ethylene =1000 C Heat from ethylene reactor is taken to gas turbine Heat released by Ca =700 * 26 * 5= 91000 K.cal Heat from hydrogen cooling 10 *7* 800 =56,000 147,000 Kcal From nitrogen 50*8 * 800 =320,000 Electricity generated from all exit streams is 156 Kwh in one minute A scrap melting plant of 60 tons per hour will produce 9.MW hr. Using Mg and recycling of MgO 3 CO2+ 8Mg = Mg2C3 + 6 MgO - .DELTA.H= 567 K.cal This is large amount of heat and partially this heat to be carried away for electricity generation. Circulating nitrogen will take out this heat to gas turbine. Nitrogen is 60 kg mole per minute. The product charge (Mg2C3 + 6 MgO ) is at about 1000 C is taken to the next reactor. Mg2C3 is reacted with H2O Mg2C3 + 2H2O = C3H4+2MgO -.DELTA.H =-189 K.cal (approx) this heat is also taken to gas turbine Heat with MgO to recycle pipe =8 CaO @ 1000 C is going to reduction reactor C3H4 goes out and is reacted with H2 C3H4 + H2 =C3H6 .DELTA.H=- 72 K.cal C p-10 K.cal/kg.mol C .DELTA.H c4h6 = -19 K.cal/mol Heat of reaction is taken to turbine Cp MgO=12 K.cal /kg.mol Mg m.point = 653 b.point =1000 C Heat released by Mg =27700 K.cal Heat from hydrogen cooling =20,000 47,000 Kcal From nitrogen 60*8 * 800 =384,000 7 Electricity generated from all exit streams is 143 Kw in one minute Obtaining of Al from Al2O3 A special furnace which will work at 2200 C is shown in the attached figure 6 The CO, CO2, H2, H2O ,N2 gases in the flue gases can be recovered as hydrocarbon gases (C2H4 and C3H6 ) adding benefit to process. Flue gases from the exhaust chimney of the coke oven battery are assumed to the following composition. CO,CO2,H2,H2O,N2. These gases are 10% of the total gases product of charge gasified from the coke-Ovens. We assume that each oven gasifies the charge mix (50% coal +50% household garbage) 25% of these gases are mixed with topgases of blast furnace Charge mix is C=72,H=12, N=4,O =2,S=3 Ash 7 kg per 100 kg of charge. Kg mole per ton of the gasified charge is C=60 kg.mole, H2=60 kg mole, N2=15 Kg.mole O2 =6 kg.mole S=1 kg.mole. Chemical analysis coke ash, per cent Silica Alumina CaO MgO Fe2O3 Mn O SO3 P2O5 TiO2 Alkalies Total 63.1 19.63 2.44 1.22 8.0 0.3 0.3 1.08 0.14 1.9 100 % of the this per hour is CO =60x.2=12 kg.mole H2= 60x.2 =12 // N2= 15x2 =3 // These gases when burnt with stoichiometric amount of air The product amount is. CO2= 12 Kg.mole H2 = 12 Kg.mole N2 =3 +48=51 Kg.mole Heat generated =1392,000 K.cal Heat gone out with flue. Flue exit temperature =350C.x 84x 8.5 (Cp)=249900 K.cal. Heat transferred to gasification mass =11421,00 K. cal. Flue gases when mixes with 25 of the gases produced CO2= 12 Kg.mole, CO= 30 Kg.mole H2 O = 12 Kg.mole,H2=30 // N2=12 +48=51 Kg.mole +0.75=51.75 Total gases CO,CO2,H2,H2O,N2. =135.75 Kg.mole These gases are divided 40% to be treated with Ca and 60% treated with Mg. In the first step H2O,N2. are removed by absorption. The remaining gases are CO, CO2, H2= 30,+12,+ 30 Kg mole Treated with Ca =28.8 kg .mole CO+CO2 + H2 + Ca = CaC2 +CaO + H2 .uparw. CaC2+ H2O = C2H2 + CaO 8 CO+CO2 + H2 + 4Ca + H2O = C2H2 + 4CaO + H2~ .DELTA.H =- 426 K,cal C2H2 + H2~ = C2H4 .DELTA.H = - 67 K.cal Total energy released = -493 K.cal Equivalent electricity obtained= 163 Kwh Product 15 C2H4 = or 420 Kg per hr. OR Benzene 5 kg.mole and H2 Thus a basic series is started. CaO is regenerated. 6CaO +4A1 = 2 Al2O3 + 6Ca +.DELTA.H = 100 .000 Kcal 3SiO2+ 4A1 = 2 Al2O3 + 3Si -.DELTA.H =149,000 // Thus for 6 kg moles of CaOapprox.3 mole silica is used to balance the energy requirement. This energy also includes energy require to volatile the Ca, and heat the circulating H2 Ca formed is volatilized and re-start the reduction cycle The 4 Al2O3 + 3Si formed go to the lower reactor Si is liquid but not volatile Si is filtered off the line and 4 Al2O3 is reduced to Al and is recycled. Energy is recovered as electricity =500 Kwh H2, CO are used to reduce 4Al2O3.which is then recycled, Thus gain is C2H4, 420 kg. Si 80 Kg. Electricity =500 Kwh The Other 60 % gases are used by Magnesium cycle. CO,CO2,H2= 30,+12,+ 30 Kg mole Treated with Mg =34.2 kg .mole 2C0+CO2 + H2 +6 Mg = Mg2C3 +4MgO + H2~ Mg2C3+ 2H2O = C3H4 + 2MgO --------------------------------------------------2CO+CO2 + H2 +6Mg +2 H2O = C3H4 + 6MgO + H2~ .DELTA.H =- 591 K,cal C3H4 + H2~ = C3H6 .DELTA.H = - 67 K.cal -13.4 +0.0 =-5 K.cal =.DELTA.=+ 8 K.cal Total energy released = -583 K.cal Equivalent electricity obtained= 194 Kwh Product 11C3H6 = or 462 Kg per hr. OR C2H4+ C3H6 = C5H10 + H2 = C5H12 a saturated proposed motor gasoline m.pt =36C Thus a new basic series is started. MgO is regenerated. 6MgO +4Al = 2Al2O3 + 6Mg +.DELTA.H = 40 .000 Kcal 3SiO2+ 4Al = 2Al2O3 + 3Si -.DELTA.H =149,000 // Thus for 6 kg moles of Mg approx.3 mole silica is used to balance the energy requirement. This energy also includes energy require to volatile the Mg, and heat the circulating H2. Mg formed is volatilized and re-start the reduction cycle 9 The 4Al2O3 + 3Si formed go to the lower reactor Si is liquid but not volatile Si is filtered off the line and 4Al2O3 is reduced to Al and is recycled. Energy is recovered as electricity =500 Kwh H2, CO are used to reduce 4Al2O3 which is then recycled, Thus gain is C3H4 , 440 kg. Si 80 Kg. Electricity =533 Kwh SiO2 , Al2O3, MnO TiO2 are separated on treating with more Na2O Fe2O3 is separated magnetically The following CaO = 0.504 MgO = 0.336 SO3 = 0.042 P2O5 = 0.084 are changed into Ca2SiO4, Mg2SiO4, CaSO4, Ca3FO4. Of the SiO2 , Al2O3, MnO TiO2 Each one is separated individually And then the base zeolite of SiO2 , Al2O3, is formed in to this composition CaO is added for N2 adsorbing resin. In to SiO2 , Al2O3, base CuO is added for CO adsorbing zeolite. There many varieties of zeolite all bases on SiO2 , Al2O3, Annually from each oven 1000 Kg zeolite is made and from 49 ovens 49000 kg This gives revenue of about.98000 U.S $ Alternatively all ash is made water soluble by treating with acids and then complexed with EDTA. This is micro nutrient fertilizer and much required those soils using urea fertilizer. This will sell at about $5 per kg. A hydro gel of sodium Aluminate sodium silicate is prepared in appropriate ratio. It is age few hours at about 100 C. The product is characterized by XRD, SEM, and FT-IR techniques. The crystal structure of the product was determined as zeolite X by XRD. The morphology of SEM image for zeolite X is octahedron shape and FT-IR bands are in accordance with the other characterization results. Top gases Per oven per hour gases produced are 260 kg mole which contain which contain 2 kg.mole sulfur. It will be changed to Na2S a useful and valuable product. Also heat is extracted from gases these are cooled from 1100C to 500 C. The electricity generated is =1.Mw in one hour per oven. Second Case: when gases from coke oven are supplied to thermal power plant and turbo-blower station. Total gases produced: Each oven is producing 195 Kg.mole per hour. The battery of 49 ovens is producing 195x49=10,000 Kg mole The capacity of the blast furnace is doubled. To 120 ton per hour. It will require 4000 Kg.mole of CO,H2 gases. Some of the remaining 6000 kg.mole is used for stove firing, under firing of coke ovens. Production of C,H2 and production of C2H2,C3H4 gases. Hydrogen is used in new process for the production of Aluminum and silicon. This explained in figure 6, figure7. For comparision aluminum production is given in figure 8. Input raw materials are Coal per battery per hour 49 ton City garbage is 49 ton per hour Garbage or annual crops residue must contain 50% moisture. Oxygen plants 3500 cu,meters per hour N2=200 tons per hour. Out put Ethylene 420 kg Propylene 440 Hydrogen used It is more appropriate to treat coke ovens steelmaking, and power system TTP-TBS( Thermal Power Plant, Turbo-Blower Station) as one working complex. The power extracted from blast furnace off gases is used locally and plant actually do not need power from Tpp. Power produced from tpp is used in rolling mills. Iron making Plant A general set up of a conventional small size blast furnace BOF steel making route with apparatus units is shown in the following table.(About a million tons steel .per annum). Main Products: Coke, Pig Iron, Billets, Hot Rolled Sheets, Cold Rolled Sheets, Galvanized Sheets 11 A zigzag route of making a mistake and then correcting it should be noticed. Impurities containing Coke (Sulfur) is produced and when this is charged into blast furnace an impure inferior product is produced. Gases and charge are processed counter current in the blast furnace creating large blown out material so requiring the need of sintering (agglomeration) Next two steps namely BOF and Ladle processing are to rectify the previous mistake of iron making. Steel is cast in large size ingots and blooms having internal and external defects so surface scarfing and reheating and size reduction, scale disposing is done until the product becomes appropriate for next operation rolling. Lot of cutting and re-joining is done producing defective portions. The rolling operation is done in air and then storing in air. The rusted surface has to prepare by annealing and pickling to next operation of coating. Pickling creates deep defects in steel structure. Cold rolling is liable to produce micro-cracks in the internal structure of metal. Against this Back ground in the presence process steel is produced using high purity gases and from iron ore steel is produced directly .Unwanted ingredients in iron ore are slaged off. Alloying elements when desired are added after steel is formed in blast furnace. Energy is recovered from liquid steel and it is directly made into appropriate forms next operation. Near net size products are produced which are given on line heat treatment in controlled atmosphere. The steel is brought in to air after required after required forming operations have been performed. On line heat-treatment can be performed.. Intermediate cutting is seldom performed, where there is need of certain relaxation between two operation closed atmospheres exit doors are provided, Briefly stated conventional iron making in blast furnace process is changed to steel making. Most of the virgin liquid steel is made through this route consisting of agglomeration (sintering), blast furnace, basic oxygen furnace to continuous cast. Our aim is to describe these conventional processes and then and describe a new short cut route of direct steel making to casting and rolling. A Blast Furnace is iron making process in which iron ore in the form of sinter or pallets or graded lump iron are charged in binary or tertiary combinations. Mostly a combination of sinter and graded lump iron ore is used. Fuel is coke made from metallurgical coal. Most of the slag forming flux is added during the sintering operation such but balancing additions (limestone plus dolomite) are made in the blast furnace along with charge. It is reduction smelting operation where certain degree of pre-reduction of the charge is achieved before it reached in the melting zone. Most of the metals are reduced and join with the liquid iron accumulated in the bottom of the furnace. A preheated blast of air is introduced in the furnace for the purpose of reduction smelting. To reduce coke rate natural gas is added in the furnace, and air blast is enriched with oxygen. The following information of the blast furnace operation is given to design new apparatus Blast Furnace operating conditions Table 4.2 Hot Blast Temperature 1100 C Blast Moisture 8 g/ cu.m Oxygen contents 21 % by Volume Blast Pressure 1.5 bar Air required 1570 cu.m / steel Top gas Temperature 300 C Pressure 3.5 bars Melting rate of furnace in terms of tons of coke (w.b.) burnt per 1 cu.m of furnace effective volume per day is 0.96 Top gas analysis Carbon dioxide % 16 CO 24 Nitrogen " 5 H2 5 Top gas volume 2070 cu.m /thm Approximate technical Characteristic of Blast Furnace melt. Table Description Unit Value Consumption of raw materials (w.b.): Skip Coke kg/ton of hot metal 564 Fluxed sinter Lump ore " 657 Hot Metal Analysis Fe % 93.45 Silicon % 0.7 Manganese " 1.2 Phosphorus " 0.11 Sulfur " 0.03 Carbon " 4.5 Copper, etc. " traces Temperature C 1530 Slag Analysis Silica % 37.2 Alumina " 10.5 Titanium dioxide " 0.8 Calcium Oxide " 39.1 Magnesium Oxide " 8.0 Manganese Oxide " 1.3 Manganous oxide " 0.3 Ferrous oxide " 0.5 Alkalies " 0.5 Sulfur " 0.6 Rated slag weight Kg/ton hot metal 428.6 13 Table 4.5 Flue dust production (recovered) Kg. / ton hot metal 25 Scrap production '' 10 Effective volume utilization factor .tau./day 1750 Out put of iron making plant thou. .tau.. / yr. 1,250 In modern blast furnace producing about 10,000 ton of hot metal per day on charge of sinter and acidic pellets ((90,10%) the coke rate is about 478 kg./hot metal and slag volume is 279 Kg.. Their top pressure is 1.5. bar and top temperature is 150 C. These have energy recovery by turbines from top gases. Every bit of energy recovery is made, simultaneously increasing equipment input. The small size iron making plant comprises following facilities. Set up of Iron Making Plant. The small size plant under discussion consist of two 1033 cum internal volume furnaces with related ancillaries (cast houses and bottom houses, block of hot blast stove, dust catchers, top skip hoists, b.f. control pulpit buildings, etc.). Large size furnaces have conveyor charging and bell type charging replaced with continuous charging system. They have energy recovery from high pressure at the top exit. The systems under discussion have: -Burden bins with skip pits over bin conveyor gallery of raw materials delivery system and equipment for fine sinter and coke breeze removal. -Substation of blast furnace 1 and 2. Hot metal relining and slag dressing ladles. .-Air supply and aspiration system -Oil supply system Administration building and laboratory. -Hot metal ladles 20 and slag ladles about 15. Top Construction. For repair or erection top plat form has 100 ton electric crane supported on the furnace top and top of the dust catcher. It can carry the full assembly and place it on exact coordinates with auxiliary winches. The main equipment on the furnace top are: -Charging device with large bell of 4600 mm diameter and 36 cu.m space between the bells. - burden distribution with the revolving hopper effective volume of 8. cu.m and the small bell diameter of 2200 mm. - bell beams and four 300 mm diameter equaling values with build-in electric drives designed for pressure equalizing in the space between the bells before they are levered. -Two chains tests for measuring stock line level. Passage are provided for connecting the furnace top with the lift, inclined bridge and dust catcher. Cast House and Bottom House Building. It consists operating platform of the building and four railway tracks for hot metal, slag and auxiliary cargo. The building has 30 ton E. O.T. cranes operating over the cast house. And 10 ton crane in the slag area. A runner for hot metal two runners for slag. Slag and hot metal ladle may be remote operated. 14 Tapping of the furnace 1750 tons per day times 8 tapping of hot metal will require three 140 tons hot metal ladles three 16 cu.m slag pot cars. For slag tapping through slag notch two slag cars are required. All furnace operation opening and closing of taps and operation of snort valve are done from the control room. Blast Furnace and Hot blast Stove Control Center Three storey 12 m wide control building is directly connoted with operating platform of furnace and the stoves. On the third storey which is at same elevation as furnace operating platform are located main control board with control and measuring instruments, furnace charging light signal, operating board of the furnace panel for natural gas feed to tuyres. Here are also located the winch as operating the dust catcher shut-off valve, the furnace bleeder valves and the dust catcher bleeder and dust valves. On the second storey at the elevation of 6500 mm are hot blast stoves control panel boards, grease lubrication stations, coolant supply inlets, laboratory, repair room for control and measuring instruments. On the first storey are at floor level are filters, with gate valves for cleaning the water facilities to the furnace. And section for transformer substation supplying to b.f and stoves. Operation and equipment changes in the blast furnace for direct production of