US2375510A - Apparatus for producing a form of pig iron of low carbon content - Google Patents

Description

8, 1945- A. D. WILLIAMS 5, APPARATUS FOR PRODUCING A FORM OF PIG IRON OF LOW CARBON CONTENT Filed A ril 15 1943 2 Sheets-Sheet 1 V stacksis frequently hlsher than 4%;

Patented May 8,1945

arranarus on r'aonucme A FORM or no IRON or LOW cannon com'rm'r Amos Denison Williams, Philadelphia, lPa. Application April 15, 1943, Serial No."483,182

11 Claims. (01. 266-25) The principal object of this invention is to pro- 7 melting zone hearth located immediately vide an improved apparatus for producing slag:

free low carbon pig iron suitable, forexample, for

use to materi l advantage in the manufacture of steel and for foundry purposes.

In the conventional iron smelting blast furpace, the ore or iron bearing materials are reduced to sponge iron in the shaft of the furnace and in the bush above the fusion zone. metal is low in carbon content because the solid solution of carbon by the cementation process 'is very slow and the time during which this sponge ironis in contact With'the fuel carbon or deposited carbon at temperatures sufliciently high for cementation or the solid solution of carbon to occur is so short that only a very slight and extremely superficial impregnation. ofthe sponge iron-can take place. This low-carbon and between the tuyeres and above the decanter crucible of the furnace from which the cast is made. Upon this hearth-practically all of the fuel carbon is consumed, and the hearth is formed so that the molten iron and slag may drain free- 1y into the crucible where theironis segregated from the fuel carbon and where gravity separabelow tion of the iron and slag takes place; Any fuel carbon that may be carried into the crucible willbe supported on the molten slag above the level bf the molten iron and Will remain in thisp0Si-- tion until consumed. By of the molten iron from prompt separation e fuel carbon solution of carbon in the iron is kept to a as the contact of the molten iron with the fuel carbon is limited to the relatively short distance from E the point. where it melts'to the combustion and metal is melted in the fusionzone and frequently freezes and accumulates on the water cooled wall at the top of the hearth and the lower portion of the bash. It is this intermediate low carbon product of the blast furnace which by use of my invention becomes the end or final product.-

In the conventional blast furnace this low carbon metal is melted in contact with fuel carbon and remains in contact with the carbon, dissolving'it,

until withdrawn from the fumace. In accordance with my invention, the contact of the molten iron is limited entirely to that which occurs in the fusion zone, and immediately after leaving this zone the molten'metal is segre ated fromcontact with carbon until withdrawn from the furnace. This procedure results in a new blast furnace metal which has hitherto been unobtainabler" 4 In conventionaliron smeltingblast furnace operation, a mass of unburned fuel carbon accumulates in the hearth below the tuyeres; This mass is continuously built up by accretions from the descending column of stock, and the-lower portion of the mass is immersed in and permeated by the molten iron accumulating in the bottom of the crucible or hearth between the casts. -At

the casts, this mass or raft probably rests on the bottom of the hearth, while for a part of the timebefore a cast it is probably floating on the molten iron with adepth of immersion proportional to the unbalanced weight of the superimposed stock column. This fuel carbon is gradually-passing into solution in the ironand in the conventional Practice the iron carries a carbon content when cast that is rarely below 3.5% and'in the larger In accordance with myinvention, the blast furnace is provided with a built-in combustionand 'fEig. 2isa Fig.1;

melting zone hearth and thereon to the point where it falls into the decanter crucible. The invention will be more readily understood by reference to the attached drawings, wherein,

Fig. 1 is a vertical sectional view of-the lower portion of an iron smelting blast furnace. equipped with a combustion and melting zone hear-thin accordance with my invention;

sectional view on the line Fig. 3 is a fragmentary view in perspective showing details of the combustion and melting 'zone hearth, and,

' tisaview in sectional element of the hearth structure.

with reference to the drawings, the hon smelt-' ing blast furnace therein illustratedis circular in horizontal cross-section, but it will be understood that the invention is readily adaptable to blast furnaces of rectangular orother cross-section. For purposes of clarity, structural supports the.

means for ,water cooling, and the means which provides for renewal and replacement of the partswhich are subject to wear and erosion, are not shown in the drawings since these details are not immediately pertinent to the invention and -willbeapparenttothoseskilledintheart. T9

this'extent, thereforiathe drawings may be considered diagrammatic. A

perspective of an" The conventional decanter crucible in'the'bottom of the furnace in which the molten iron and slag accumulate for gravity separation and from r Y which the iron is cast and the slag flushed is in-' dicated by the reference character A; B desishates the iron notch through which theiron is cinder cast at sultable intervals; and C designates the V through which the slag is flushed, also at suitable intervals, both in accordance ing E but leavingthe lower ends of the troughs H ,in the drawings.

with the conventional practice. It should be understood that the lines indicating the molten iron 'level and molten slag level" are'for purposes of illustration only, and the actual and relative elevations of these levels may vary widely from those shown during the periods between the casts 1 and flushes.

The combustion and melting} Zone hearth con sistsgenerally of anannular structure 8, the upper surface of which is formed so as to provide an annuiar series of interspersed ridges G and ,tr'oughs H radiating from the lip L of a' central opening E. From this opening the troughs andridges extend outwardly and, upwardly to. the

tion of the bottoms of the troughs is such as to hearth to the crucible by way of the opening E.

' Proiectin g through the wall M into the upper [and outer end of each ofthe ,troughs I-I' is a tuyere J through which the blast is forced into the furnace to form an intensely hot combustionzone above the hearth structure 8. Kdesignates the 4 lower portion ofv the bosh slope by which the walls the crucible, and servealso as emergency drains in event of obstruction ofthe' troughs. In this respect; it is to be noted that with the relative arrangement of the hearth and tuyeres described above, the molten iron is maintained in a zone of high temperature until it actually leaves the hearth through the notch B sothatpossibility of obstruction due. to freezing of the low carbon metal on the surfaces of the hearth is minimized. In this manner the well known difficulties experienced in conventional blast furnace operation due to the high freezing temperature of low cari enclosing .wall M of the furnace. The 'inclina- 15 insure a free flow of molten iron and slag fromthe ture and supported in no'nobstructing relation to i said troughs. I

M of the furnace are drawn into the tuyere circle.

In the .outer portion of the structure S and extending, upwardly .from the top -of the crucible chamber A to the outer and-upper endof each of the troughs H is a passage D, these passages hearth, said hearth having a central apert 2. An iron smelting blast furnace having a combustion and melting zone hearth forming a support for the stock column, a crucible be] saidand ' a plurality of tro 'ghs radiating outwardly and having a dual function hereinafter described.

mg cone F. This cone covering the centralio'penunobstructed. 5

In operation, the descending stock column is defflected outwardly by the cone 1} into the tuyeres region in" which the iron will be-melted and the j slag formed and also melted. The ridges G which 'occupythe dead space between the tuyeres serve 40 to guide the descending stock and fuel-into-the. active zones in front of the tuyeres. Within the intensely hot combustion zones, the iron is melted,

and the gangue of theore combines with the flux and forms the molten slagdmafree running con- Supported at the top ofthe hearth structure's upon the upper edges of the ridges G is a deflectupwa'rdly'from s d aperture, and having also a central member overlying the aperture and supported in non-,-obstructing relation to said troughs, and a tuyere at the upper end of each of said troughs.

3. An ironsmelting blastfurnace having-a coinbustion and. melting zone hearth forming a support for the stock column, a crucible below said dition. The ,troughs H conduct the streams of molten iron and molten slag to-thecentral opening E where'they flow into the decanter crucible opening communicating-with the rL-rucible-ai plu A. In case of'any obstruction in thetro'ughs H aperture E, the troughs will actto divert the :fiow

i 1 ,preventing the stream of molteh iron'and'slag from flowing freely in the normal way intotheq hearth, said hearth having a central aperture and a plurality of troughs radiating-outwardly and-upwardly from saidaperture, and having also a cen-. tral member'overlying the aperture and supported in non obs'tructing relation to-said troughs, and l a tuye're at the upper end and directed longitudinally of each of said troughs.

,4. 'An iron smelting blast furnace having a combustion and melting zone-hearth forming a support for the stock column, a crucible below said hearth} .said" hearthcomprising a-central rality of troughs radiating outwardly from said opening, and a cover for said central opening supported in non-obstructing relation with said.

' troughs. v v

to the vent passages D which leadto thecrucible '-A as previously described. vent passages Dserve, therefore, as emergency drains in that; I event that the free flow of molten 1103, 16 $1 8- Idown the troughsH and into\the crucibleis'obfg structed. by freezing of the low carbon iron or from any other cause.- Thepassa'ges D' function" "also as vents for the crucible permitting escape to vtherefrompf gases carried in withthe inf-lowing :metalands'lag;

' 'Inoperation the hearth S supports .the stoclri I column and in effect defines the lower endof the: combustion andlr'nelting fzone. The molten iron (i5 and slag forming in this zone. drains --fre.ely

- through the aperture Einto the decanter crucible I 41' wherein gravity separation occursas indicated Any fuel carbon carried down 'withithe molten'stream will float at the top ame slag untilQit isj'gassifjied' or burned. Extended, contact of the-molten -iron withthe fuel carbon g is avoided and a sla jl'ee low' carbon-ironresults;

5.- iron smelting -=blast fumace'havinga combustion and melting 'zoneheartir forming a "support for the stock colum'njand a crucible below ,said' hearth, the upper-surface of said hearth being inclined downwardly .i toward the z... j center and terminating in an opening. communicating with the crucible, and a central member overlying said aperture and supported in spaced relation to the uppersurface of the hearth so as is provide therebetweena'n opening for. passage ofmolten metal and slag to the crucibles. an iron'ismelting 'blastjurnace having a combustionand melting zone hearth-forming a .support'for ,the. stock column, and a crucible ;below' said hearth, 'saidhearth having a central aperture communicating-with the crucible, and

an'annulai-v series of ports at the outer.

' periphery also communicating with the crucible,.,-

of said'hearth' extending from each r "said pt as troughlikei'de'prssionjn the upper suriace inwardly and downwardly to said vcentral s a f As previously set forth, thepassages-D'provide-u ""t i s tlivre:at'lthe;.upper.-end' of each of said T vents for any blast or other gasesthatlmay enter tro ghs a- .central-jmember overlying aperture and the inner terminal ends of said troughs.

7. An iron smelting blast furnace having a combustion and meltingzone hearth forming a sup port ,for the stock column, and a crucible below said hearth, the upper surface of said hearth being inclined downwardly toward the center and terminating in an opening communicating with the crucible, ports in the outer peripheral area of the hearth also communicating with the crucible, and. a centrallmember overlying-saidcentral aperture and supported in spaced relation to the upper surface of the hearth.

8. An iron smeltingblast furnace comprising tuyeres and a crucible and an intermediate combustion and melting zone hearth supported by the wall of and bridging thecruclble and on which the stock column in the bash and shaft of the furnace is carried, said hearth being adapted to receive and to direct the molten metal and slag to the crucible for gravity separation,

whereby the molten metal in the crucible is protected from contact with the fuel carbon.

metal and'sla'g 9. An iron smelting blast 'fumace a crucible for reception and gravity separationof the molten metal and slag, a superimposed hearth, and tuyeres operatively associated with said hearth, said hearth constituting a. support for 7 and shaft 01 the the stock column in the iurnaceandcomprising means for guiding the stock into the active zone immediatelyin front I comprising means for gravity flowof molten metal and slag 'tmthe crucibleysaid means comprising a lip on the hearth from which the said molten metal and slag may'pass'freely and directly into the crucible, means for guiding the Y, said molten elements to the lip, and means for establishing an active melting zone at the top of the hearth embracing said guide means.

11. An iron. smelting blast furnace having a; crucible for reception and-gravity and shaft of the furnace is carried, -'.said hearth having also a discharge arealfrom'which molten u may 'pass. freely and directly into the. crucible,-

establishing an tive melting zone at the-top ofthe'hearth, ,and means for thestoch into the active zone of said tuyeres and'for direct the flow or discharge area.-- N

f AMOS: DENISONYWHJ Hans;

v k blast -furnace having ,a

crucible forreception and gravity separation of separation of the molten metal slag, a superimposed hearth supported by the wall of and bridging the cruc- I ible and on which the stock column in the bosh means including tuyeres for 1 molten metal and'slag to ng

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