US2650161A - Production of iron in a blast furnace - Google Patents

Description

2 Sheets-Sheet 1 F. TOTZEK PRODUCTION OF IRON IN A BLAST FURNACE INVENTOR. DRICH 751'ZEK arroeiygsr w v 6 z Q 6 a 1 2 Filed Jan. 21, 1950 Aug. 25, 1-953 F. To'rzEK 2,650,161

PRODUCTION OF IRON IN A BLAST FURNACE Filed Jan. 21, 1950 2 Sheets-Sheet 2 INVENTOR. P22509104 707-2511 Patented Aug. 25 1 953 2,650,161 PRODUCTION OF IRON IN A BLAST FURNACE Friedrich Totzek, Essen (Ruhr), Germany, as-

signor to Koppers Company, Inc., Pittsburgh, Pa., a corporation of Delaware Application January 21, 1950, Serial No. 139,849

In Switzerland February 5, 1949 6 Claims.

The present invention relates in general to the production of molten iron in a blast furnace and, more specifically, to the production of molten iron in a blast furnace into which the employed solid, fuel is introduced partly in the form of lumps and partly in a finely-divided state.

. In the following description, the word iron is employed to include both pig iron and ferrous alloys.

Very early in the development of the blastfurnace art it was attempted to meet the requirements of a blast furnace as to its demands q for solid fuel by charging a part of the fuel in a lumpy state along with the ore and the fluxing compounds at the top of the blast furnace and to supply the remainder by introducing pulverized, solid fuel into the hearth of i the blast furnace along with the blast. The purpose of these earlier attempts was to reduce the required amount of expensive lump fuel by its partial subhearth hardly reacted at all with the blast. Only heat was removed from the hearth by the introduction of the coal dust which had to be compensated for by an increased consumption of the lump fuel in the hearth.

In order to avoid these difliculties it has been.

proposed to preheat the finely-divided fuel before its introduction into the hearth in an externally heated pipe without admission of air. But also this method did not lead to success.

An object of the present invention is to provide improvements which, without disturbing the normal reactions in the blast furnace, permit the replacement of a considerable part of the required lump solid fuel by a finely-divided solid fuel.

Another object of the present invention is the production of iron in a blast furnace by means of lump solid fuel and to produce at the same time a blast-furnace gas which is suitable for carrying out chemical reactions; e. g., the synthesis of hydrocarbons or for other purposes.

Another object of the present invention is to produce iron in a blast furnace with the consumption of only relatively small amounts of lump fuel having a comparatively low crushing strength.

Another object ofthe present invention is to provide such improvements in the construction of a blast furnace as permit the introduction of large amounts of finely-divided fuels into the hearth thereof.

Solid fuel asemployed in the blast furnace serves four different functions, namely:

(1) The solid fuel provides the amount of carbon which reacts with the reduced iron in order to produce molten pig iron of the usual quality.

(2) The solid fuel provides the carbon required in the hearth of the blast furnace to effect the so-called direct reduction which isunderstood to (4) In the lower parts of the blast furnace .the solidjfuel must also form a sort of grate on which the furnace-charge rests and which is percan be blown into the furnace and it finally must also make the total furnace-charge sufficiently permeable for the blast furnace gas leaving the top of the furnace.

Of the above-mentioned four functions of solid fuel in the blast-furnace substantially only one can be filled by pulverized fuel; that is, the

supplying of therequiredheat.

and method of operation requires about 800-1000 kg. of cokeper ton of pig iron produced, depending upon the characteristics of the ore.

The amount of lump fuel that is required for the formation of the gas-permeable grate and for securing a sufiicient permeability of the furnacecharge depends of course on the properties of the ore andon the design of the blast furnace. Un-

could not lead to an 7 oxygen or air with a oxygen, preferably a gas (air) with a content of hearth along dioxide andhydrogenand/or necessary manner der optimum conditions it is possible that the amount of lump fuel required fOr the direct reduction and for the reaction with the molten iron is sufficient to secure the necessary permeability of the charge in the hearth and in the stack of the blast furnace.

From the aforesaid it follows that any important replacement of the lump fuel by coal dust,

or the like, can be only effected when considerable amounts of the finely-divided fuel are introduced into the hearth itself. Itis not generally possible to state the amountof coaldust that can be introduced into the hearth but when one considers that it is necessary 'to introduce at least 600-800 kg. of coal, or coke dust, per ton of pig iron into the hearth of the blast furnace in order to obtain a proper operation with the smallest possible consumption of lump fuel, it follows that the hereinbef-ore mentioned earlier proposals effective improvement.

The present invention comprises introducing into the tuyeres of, .a blast furnace a mixture of oxygen and finely-divided solid fuel which is as homogeneous as possible and which has been preformed at a relatively low temperature, said mixture'being introduced into the tuyeres in such a wayand undersuch conditions that the reaction between oxygen and the finely-divided solid fuel yields substantially only carbon monoxide and that thi reactionis started at the outlet of the tuyeres and 'is com leted before .the reaction mixture comes into, contact with the solid or fluid and/ or pastycharge of the hearth.

In this description and in the following claims the term oxygenis understood .to comprise pure highly increased content of more-thanfiO of oxygen.

The amount o f-oxygen which according to the present invention is to be introduced into the with the finely-divided solid fuel depends on several factors. In no case can the amount of oxygen be so great that stoichiometrically only carbon dioxide is formed by the reactionbetween the pulverized solid fuel and oxygen when the amountof hydrogen and hydrocarbons 'in the fuel are also. taken into consideration in the calculation. On the otherhand, in general, atleast so much oxygen must be introduced that the 'finely-divided'fuel which is to be added is utilized and convertedinto carbon monoxide and hydrogen.

From .agpractical point of view the most advantageous method of operation is to produce a reaction gas. that consists of carbon monoxide, containing a fixed amount of carbon steam. When calculating the amount of carbon dioxide which may be permissible 'it must be remembered that, because of the temperature prevailing in the hearth, the carbon dioxide will react with the lump fuel in the hearth andthe consumption of lump fuelis thereby increased. In practical operation, moreover, a definite amount'of carbon dioxide can be required in order to use up sufiie cient of the solid lump fuel in the hearth that the charge of the blast furnace descends in the I and this is especially so if the consumption of the lump fuel for the direct reduction and for the carbon used for the reaction with the metallic iron is inadequate to permit the charge to descend properly.

The concentration of oxygen in the gas (air) containing oxygen which along with the finelydivided fuel isv introduced into the hearth of the furnace depends on the properties of the ore to out-according to the be used and on the properties desired in the pig iron to be produced.

If the ore is difficult to reduce the concentration of oxygen must be higher because the temperature in the hearth must be higher. larly the concentration of oxygen is to be increased if a pig iron of a higher melting point or a ferro-alloy is to be produced; such a case may for instance exist if a pig iron with a higher content of silicon i to be produced, While for the production of an open-hearth pig iron 2. lower temperature in the hearth is to be preferred in order to produce as little silicon as possible by reduction'of the slag.

If the operation of a blast furnace is carried present invention it is possible to reduce considerably the consumption of lump solid fuel in the blast furnace but it must be remarked that the total requirement of finelydivided fuel for the blastv furnace can be higher than in the case when'the same blast furnace is operated'only with lump solid fuel. But this additional consumption of solid fuel which may happen under certain circumstances, with the process according to this invention, affects'only the amount of finely-divided fuel, the price of which usually is only a fraction of that for a lump fuel having a high crushing strength. It must also be considered that with the process according to the invention a valuable blast-furnace gas is produced" which without further treatment, can be used for the synthesis of valuable hydrocarbons, or'for other purposes. With the process according to this invention the whole of ore, fluxing agents and fuel, in the, furnacestack and-in thehearth of the blast furnacaand which also has sufficient crushing strength. In general, there can be-considered, for example, coke from bituminouscoal, charcoal, anthracite and 'other' non-coking coals.

Practically any chosen solid fuel can be used as the finely-divided fuel if it has the necessary small" size of grain. Preferably the invention uses a finely-divided solid fuel which leaves not m-ore than 10% residue ona-4900 mesh sieve; Itis unimportant whether the finely-divided solid fuel is of the coking or non-coking variety.

The ratio of the reactivity of the finely-divided solid fuel to that'of' the-lump solid fuel is of no significancewhen applying this invention. Into a blast furnace which is operated for instance with an easily reactive charcoal as the lump fuel, there can'be charged a 'finely-divided-fuel of poor reactivity, for instance pulverized bituminous coal. Such utilization of poorly and easily reactive fuels simultaneously has beforethe present invention not been possible in theoperation of a blast furnace.

,The present invention design of the blast furnace production of 1 molten iron.

According to an essential feature of the present invention one onmoreiso-called gasi'fying heads are provided in the walls of, the 'hearthhf the also provides a novel.

to be used for the fying heads that one or several continuous rows of gasifyingheads are formed along the whole circumference of thehearth. Q j

The single gasifying' head is ,designed almost like a common water cooled tuyre or nozzle which usually serves to introduce the blast into the hearth of the blast furnace. But towards the inner part of the hearth the gasifying head is enlarged as compared with the common tuyre or nozzleso that an essentially conical space is formed which opens intothe hearth with its wider end.

The homogeneous mixture of oxygen and finely-divided fuel which has been preformed outside the furnace is introduced at the narrowest point of this conical space and axially thereof in the form of a jet. I

Advantageously the gasifying head is provided with water-cooled walls. Preferably, according the water-cooled walls can, according to the invention, beprovided with a refractory lining The size and arrangement of the 'gasifying heads is so chosen that the conical space of the gasifying heads cannot be filled-in by the charge in the hearth during operation of the blast furnace. In this manner, according to the invention, a row of gasifying niches or chambers is formed each .being sufficiently large that the reaction between oxygen and solid finely-divided fuel can practically be finished before the prodnets of this reaction meet the solid or pasty charge in the hearth.

A preferred embodiment of the invention is to provide the hearth of the blast furnace with a greater diameter than the stack and to arrange the gasifying heads in the arch-like space between the stack and hearth. This design is shown on the attached drawing.

According to the invention it is also possible to line the gasifying heads with carbon bricks. In order to counteract attack of the carbon bricks View showing the structure from the mixing device I to the water jacket 9 in greater detail.

Figure 4 is an enlarged view of the mixing de-.

vice l5.

frame 3.

The lower end of the stack 1 opens into a tapered portion 5, the smallest diameter being adjacent the stack, as shown in Figure 1.

The hearth 4 formed by refractory walls 6 is of greater diameter than-the tapered portion 5. In the arch-like wall 1 between stack and hearth a continuous row of gasifier heads 8 is arranged as can be seen from Figure 2.

As shown in Figure 1, the gasifier heads 8 comprise each a water-cooled jacketed body 9 provided with a refractory lining Ill. The refractory lining l0 forms a reaction space H which is essentially conical and which opens with its enlarged end into the hearth 4. At the narrower end of the reaction space I I there is a watercooled nozzle or tuyre I2 adapted to introduce a mixture of finely-divided solid fuel and oxygen in the form of a jet 1nto said reaction space.

The mixture of finely-divided solid fuel and oxygen are introduced into the nozzle I 2 at a fuel passes into a transporting worm l4 through which it is conveyed continuously into a mixing 4 the mixture flows from a said device [5 through a pipe Hi to an individual nozzle l2 connected orific I7 is preferably so arranged that the gas leaving through the annular orifice I! is forced to flow along. the walls of the conical reaction chamber H. l

The molten pig iron produced in the blast furace is tapped off at 21 and the molten slag at 22.

value of theblas't-furnace gas drawn off at 23.

j The possibility offalso using a lump fuel of relathe blast furnace in the usual manner.

The invention as hereinabove set forth is embodied in particular form and manner but may iron, from iron ore'ina blast furnace by'th-e introduction of pulverized solid fuel at :thehearth of said blast furnace containing saidore, said process comprising: introducing the furnace charge of iron-fore and; flux along with l'ump solid carbonaceous fuel for direct reduction, for reaction withthe metallic iron itself,;and for gaseous permeability of the :chargelinto the'blast furnace through. the. throator lthe furnace; introducing the solid fuel for supplying?the heat fort-he: process by preforurn'n'g outside the blast furnace hearth and at relatively temperature'afluidized mixtureoi gas comprising more than-comer cent, free oxygen and: .pulverizedsolidt fuel. with the oxygen in amountiisuh to yield. by reaction with the solid fuel substantially only fc'arbon monoxide -=but in amoun such' 'thattlthe pulverized fuel of the mixture ise substantially all utilizedzin conversion to carbon monoxide, flowing. s-a'i'd' mixture axially inthe formofa jet into tuyeres-that communicate With-"thehearth 'of said blast-furv nae-e and initially igniting the mixture at the inlet of the tuyercs and completing the thermal reaction tocarbon monoxide ofthe reactants of said mixture in the Ltuyres in advance of emission from the. tuyres-into-the.hearth protecting the walls of the tuy eresby' surrounding thehaxial jet of the thermal reaction mixture, during its flow through the--tuyres with a-surrounding flow of a gaseous reducing medium in direct'con'tact therewith in the-formcf a reducing' medium while:

the thermal-reaction nI-ix-i'nn'e i s issuing into: the tuyere-p'ath flows through the tuyerepath-to the hearth; thereafter bringing the resultant thermal reaction mixture into contact with the ironore at-said blast furnace hearth, and passing the gases thereof upwardly through the furnace shaft through the furnace-charge of iron ore, fzux, and carbon-introducedtherewith as aforesaid through thet-hroat of thefurnace; and withdrawingtheso produced blastigas'from theupp'er part of the furnaceshaft.

2; method claimed in claim ihand lII'WhliJh the tuyere path is of gradually increasing cross- 7 sectional"area-in the "direction of the-hearth for effecting substantiar completion of the, thermal reaction of the reaction mixturegtherein before the mixture 'issu'es'jinto the hearth "charge from the tuyere pathfand which thesurrounding 7 flow of another cooling medium is'ca'rbon monoxide. 7

3. An improved process for"producing-metallic iron from iron orein a blast furnace by introduction of pulverized solid fuel at the hearth of said blast furnace containing said ore, said process comprising: charge of iron ore and flux along. with lump solid carbonaceous-fuel for direct reduction; for reaction with the metallic iron itself, and'for gaseousperm'eability 'of the" charge, into the blast furnace through the throat of the furnace; in-

'troducing the solid fuel for supplying the heat for the process by preforming outside. the. blast furnace hearthxa'nd at a: relatively "low temperature" a fluidized: mixture f a gas comprising more than601percetit'free oxygen and pulverized 7 solid fuel with the oxygeniinramountfinsufiicient introducing the furnace to oxidize the carbon of said fueltolmainly carbon dioxide but in amount such that thepulverized solid fuel of the mixture is all utilized in con-' version to .gas by the oxygen of the mixture; flowing said mixture axially in the form of a jet through tuyeres that communicate with. the hearth of said: blast furnace and initially'igniting at the inlet of the tuyeres and completing the thermal reaction of the reactants of said mix-'- ture to oxide of carbon in the tuyeres in advance of emission from the tuyeres'into the hearth charge; simultaneously flowing an annular stream-of carbon-monoxide through the tuyres from the inlet to the outlet of. the tuyres and so as to form an annular envelope, along. the tuyre walls that surroundthe jets of fuel and oxygen therein; thereafter bringing said thermal reaction products into contact with iron ore of said. blast furnace hearth: and passing the gases thereof upwardly through the furnace charge of iron ore, flux, and carbon introduced therewith as aforesaidthroughthe throat of the furnace: and withdrawing' the so-produced blast gas from the upper part of the furnace shaft.

4. A method as claimed in claim '3, and in which the thermal reaction mixture of the: axial jet and the stream of carbon monoxide flow charge is centrally superimposed on the hearth portion of the charge and the tuyere burning paths are disposed: over the marginal topportions of the hearth of the charge that surround the lower portion of the stack portion of the charge centrally superimposedon the hearth vportion. r 6. A method as claimed: in claim 4, and in which bhe tuylere paths are insulated with elemental carbon and in which the tuyere insulation isprotected from thewaxial jet by a cooling medium comprising a. reducing medium of carbon monoxide, which issues into the ':hearth along with the issue of the thermal reaction mixture from the tuyre paths.v r

FRIEDRICH TOTZEK.

References Cited in the file of this patent UNITED STATES PATENTS crime REFERENCES The Iron Age; Nov. 21, 1946, pagees.

Claims (1)

1. AN IMPROVED PROCESS FOR PRODUCING METALLIC IRON, FROM IRON ORE IN A BLAST FURNACE BY THE INTRODUCTION OF PULVERIZED SOLID FUEL AT TE HEARTH OF SAID BLAST FURNACE CONTAINING SAID ORE, SAID PROCESS COMPRISING: INTRODUCING THE FURNACE CHARGE OF IRON ORE AND FLUX ALONG WITH LUMP SOLID CARBONACEOUS FUEL FOR DIRECT REDUCTION, FOR REACTION WITH THE METALLIC IRON ITSELF, AND FOR GASEOUS PERMEABILITY OF THE CHARGE, INTO THE BLAST FURNACE THROUGH THE THROAT OF THE FURNACE; INTRODUCING THE SOLID FUEL FOR SUPPLYING THE HEAT FOR THE PROCESS BY PREFORMING OUTSIDE THE BLAST FURNACE HEARTH AND AT RELATIVELY LOW TEMPERATURE A FLUIDIZED MIXTURE OF GAS COMPRISING MORE THAN 60 PER CENT, FREE OXYGEN AND PULVERIZED SOLID FUEL WITH THE OXYGEN IN AMOUNT SUCH AS TO YIELD BY REACTION WITH THE SOLID FUEL SUBSTANTIALLY ONLY CARBON MONOXIDE BUT IN AMOUNT SUCH THAT THE PULVERIZED FUEL OF THE MIXTURE IS SUBSTANTIALLY ALL UTILIZED IN CONVERSION TO CARBON MONOXIDE, FLOWING SAID MIXTURE AXIALLY IN THE FORM OF A JET INTO TUYERES THAT COMMUNICATE WITH THE HEARTH OF SAID BLAST FURNACE AND INITIALLY IGNITING THE MIXTURE AT THE INLET OF THE TUYERES AND COMPLETING THE THERMAL REACTION TO CARBON MONOXIDE OF THE REACTANTS OF SAID MIXTURE IN THE TUYERES IN ADVANCE OF EMISSION FROM THE TUYERES INTO THE HEARTH PROTECTING THE WALLS OF THE TUYERES BY SURROUNDING THE AXIAL JET OF THE THERMAL REACTION MIXTURE, DURING ITS FLOW THROUGH THE TUYERES, WITH A SURROUNDING FLOW OF A GASEOUS REDUCING MEDIUM IN DIRECT CONTACT THEREWITH IN THE FORM OF A REDUCING MEDIUM WHILE THE THERMAL REACTION MIXTURE IS ISSUING INTO THE TUYERE PATH AND FLOWS THROUGH THE TUYERE PATH TO THE HEARTH; THEREAFTER BRINGING THE RESULTANT THERMAL REACTION MIXTURE INTO CONTACT WITH THE IRON ORE AT SAID BLAST FURNACE HEARTH, AND PASSING THE GASES THEREOF UPWARDLY THROUGH THE FURNACE SHAFT THROUGH THE FURNACE CHARGE OF IRON ORE, FLUX, AND CARBON INTRODUCED THEREWITH AS AFORESAID THROUGH THE THROAT OF THE FURNACE; AND WITHDRAWING THE SO PRODUCED BLAST GAS FROM THE UPPER PART OF THE FURNACE SHAFT.

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