US1245183A - Process of sintering. - Google Patents

Description

A. l. BOYNTON & A. EfSANDS. PROCESS 0F SIITERING.

Armcmo mtu was. m1.

2 SHEETS-SHEET l- 1,245,183. A Pand Nov. 6, 1917.

FIG. 1

WITNESSES INVENTQR aj@ .ff/M@ N,

A. 1. sovmou a. A. E. SANDS.v

Pnocsss or summa. unicum min Aus. a. m1.

Fatemi Nov.6,1917. 4

2 SHEETS-SHEET 2.

mvzqrron wrrmzssts UNITED sTATEs PATENT oEEIoE.

7' AMHUB .1. BoYN'roN, or LOEAIN. AND ALBERT n, SANDS, or comme', oH'ro.

PROCESS F SINTERING.

Specification of Letters Patent.

Patentedl Nov. 6, 1917.

yApplication filed Aug-ust 3, 191?1 Serial Noy 184,296.

To all whom t may concern Be it known that we, ARTHUR J. BoYNToN and ALBERT E. SANDS, citizens of the United States, and residents, respectively, of Lo rain, in the county of Lorain and State of Ohio and Akron, in the county of Summit Aand tate of Ohio, have invented a new and useful Process 'of Sintering, of which the following is a. specicati'on,

Ourinvention relates to sintering blast furnace 'Hue dust, iron ores, and similar linel divided materials which are combustible or to which a combustible is added in preparation for sintering. While not necessarily limited to such apparatus, our improved process is particularly adapted for use with sintering apparatus embodying .a sintering pan 4having a porous hearth formed of refractory material, and having means for causing a vcurrent of air to pass through a body of the sintering material positioned in such pan in quantities suincient to-support combustion and cause the materials to sinter. n

In the sintering processes heretofore used in connection with apparatus such that shown, a, quantityI of flue 'dust or other com bustiblematerial `in a finely divided state is placed in the sintering pan; Usually, and

referably, the grate bars forming the peri orated` bottom of the sintering pan are cov- 'ered with a layer of'crushed limestone or siniilar refractory material to form a porous hearthY within the sintering pan upon which the material being sintered 1s supportede After the upper surface of such body of lue'dust in the sintering pan is leveled, a

gas burning igniter is Wheeled or otherwise moved into position above the material, or above a portion ofthe material, in the sintering pan. Anexhaust fan, which is con?v nected to the bottom of the sintering pau in. any suitable manner, is then started in operation and the li hted,-` .Y

4fgas burning igniter is he'igniter 'then -lires the 'upper surface l of the material Within the panthat is' covered byl the igniter, the exhaust fan with; drawing `thelgroducts of combustion from the pan andcausin 'la current of air to pass through the maternal in the pan in quantities suilicient #to support combustion vand 'causethefformation of sinter.' After` he upper vsurfacelof thamaterial ,withinhe sintering pan is thoroughly ignited and the sintering operation is started, the :gniter is moved away from above the pan. The exhaust. fan continues to withdraw' the products of combustionfrom the pan and r by suction, draws `yuiiicient rair into` or through the body ofmaterials in .the sintering pan to gradually propagate the sinterlng operation throughout the mass or body of material Within the .sintering pan.

The sintering of Hue dust and fine ores is only made possible by reason of the 4carbon or asimilar combustible in the material being sintered, carbonaceous material `being added to the iron ore when such ore is the material to be sintered.

The amount of carbon in the material to f be sintered, unless carefully re ulated-so as to be but slightly in excess o Vthe amount required to support combustion, causesa very intense heat. Such high temperatures necessitate a long time to be taken .in cooling the sinter, While it is a generalrule that the greater thel amount of carbon in 1 the material the larger will be the amount of cinder formed in the sintering opera-tion.

lt is not practicable to maintain the carbon content of the materials Within the close range between that necessary to support combustion and that required in order to prevent a large increase in the temperature'of the 4sintered material and the formation of large quantities of cinder that' results from an excess amount of carbon, Without such frequent and careful sampling and analyses as will make the cost prohibitive. It, heretofore, has beennecessaryto consume' a considerable part of the time in' cooling the sintered mass after the sintering operation is completed from the high temperature at which it is completed and thereby delay the sintering operations, while the molten cinder formed in the sintering o sus` eration clogs and chokes up the voids in t e' porous hearth and seriously interferes with the completion of the sinteringoperation,

in the last stages of each sintering 0pera- It frequently occurs that owing to tion'. tothe shutting olf of the air supply inthis way, as muchV time is required to slnter'the last ten per cent. of the material inthe sin? tering pan as is necessary to sinter the first One object ,of our invention lis the provision of ya vel method of sintering whereby the siiitering operation is facilitated, the

time lrequired inl cooling -the sinter is re and Indre uniformly cooled and the hard-A ness and porosity are equalized and made uniform throughout the sintered mass.

Another object of our invention is to provide an improved method of sintering whereby wide variations in the carbon content of the material being sintered are rendered negligible without interference with the sintering operation'or lessening of the qualitfy of the sinter.

A urther object of our invention is to vide an improved process of sintering having a novel series of steps whereby the sintering operation is facilitated and whereby the character of the sinter as to porosity and hardness is rendered much more uniform.

A still further object of this invention -is to provide a` novel process of sintering whereby the molten cinder formed in the sintering operation is drained oil' as formed from the body of the materials being sintered, and choking ofthe passages for the air and products of combustion during the sintering operation, is 4avoided and prevented. Y

A further object of the invention is to provide an improved process of sint'ering havinga novel series of steps whereby'interference w-ith and delays in the completion of the sintering operation by the formation of molten cinder during the sintering operation, are lessened and overcome.

Referring now to the drawings, forming part of'this specification, Figure 1 is a diagrammatic plan showing one embodiment of sintering apparatus which is constructed and arranged and adapted for use in carrying out our improved process.

Fig. 2 is a diagrammatic side elevation .of the apparatus shown in Fig.' 1. Y

Fig. 3 is a diagrammatic end elevation of the apparatus shown in Figs. 1 and 2.

Fig. 4 is a sectional end elevation show-Jl ing details in the construction and arrangement.,pf`the tilting sintering'pan formin part ofthe apparatus shownin the prece in'jigures of 'thedrawings ig. 5`s a sectional plan showing a detail' irll the construction of the connection between the stationary exhaust conduits and tilting sintering pan of the apparatus shown' in the preceding figures of the drawings.

In the accompanying drawings, the numeral 2 designates asintering pan which is arranged to tilt or rock about a horizontal "axis, opposite ends of this pin being ypro-- videdwlth hollow trunnions 3, 3,'by which the pan is rotatably mounted in suitable trunnion'bearings.

."Ihe pan 2 has a bottom 5, sides 6, 6, andintegrally formed ends 7, the hollow trunnio` ns 3, 3, opening into the pan through the end. walls of the pan. At an intermediate point in the height 'ofthe side walls of the a rotary mixer.

pan is a series of perforatedfgrate bars 8, these :grate bars being fastened in place within the pan 2 in any desired manner, and loosely positioned on top of the grate bars is a. porous hearth 9 formed of a thin layer of crushed limestone or similar refractory material.

The outer' ends of the hollow trunnions 3- are connected to one end of pipes which form conduits 10, 10, for leading thev gaseous products of combustion from beneath the grate bars 8 in the pan V2 into-the exhaust blower or fan 11 to which o ne-,endfof` each of the pipes 10, 1Q, are connected. The exhaust blower or fan 11 which, as shown, has two inlets, has a single discharge outlet which is connected by a branch pipe 12 to the lower end of a stack 13, the stack being of sufficient height to carry off the products of combustiondischarged thereinto bythe exhaust fan.

IThe tilting sintering pan2 is' elevated above the ground level and is arranged to be rotated on the trunnion bearings'through an arc of at least degrees, in -arder that it can be positioned horizontally to receive' Y `successive quantities of material tobe' [sinwv tered and to enable the igniter 14 tti-"be moved into and out of position above the] pan, and also to permit of the. pan' beingf tilted at an angle to the horizontal-after the sintering` operation is commenced and to be inverted so as to discharge the' sinter from:

ositioned onjthej the pan 2 into a car 15 track 16 located inl line'wlth and below the elevated sinterin'g pan 2..` n

A suitable turning mechanism will beprovided for the tilting pan as well as means for tempering and mixing the finely dividedv materials to be sintered, and means for delivering or discharging the materials into the sintering pan.

In the operation of our improved processi'.`

the flue dust or other material to be sintered -will be placed Vin an overhead bin or bunker, Weigliod quantities vof the materialwill bewithdrawn from the bunker and placed in added to the weighed materials, either before or afterbeing placed in the mixer', ai 1d the materials will be thoroughly mixed a tem ered. 4

Sufficient water will-bev T e materials'are then removed from mixer and placed in the sinteringpan, pref.- erably a chute being employed to dellver the materials into the pan by gravity. The ma terials i'n the pan are then leveled, after I i l' which the gas burning igniter is-moved into sintered. The exhaust position above. the pan of materials to be si #1p1-2 fan l1 is then .started and the igniter 14 is lighted. The'fan createstion within the an-2 and draws au' and thel products of com ustion' through the of materials and the porous. hearth 9 in 'he Ien lng pan and the sintering opera-tion is allowed to progress.

of the material in the sintering pan and the material 1s sintered toa sufficient extent to form a crust on the outer surface of the materal in the' pan, the pan is tipped or tilted until the upper surface of the materials inthe pan is at an angle somewhat less than a right angle to the horizontal. The sintering operation is then allowed to propagate throughout the mass until the entire body of materials Within the p'an is formed into sinter. i

' As the pan is tiltedatan angle to thehorizontal during the major portion of the time required in sintering, any molten cinder formed during the sintering operation will trickledownwardly at an angle to the horizontal or approximately horizontal path or direction of travel of the column of air used in supporting combustion, and when suilicent quantities are formed, will flow out of the pan. The flow of molten cinder will befurthered by punching a series of holes in the-sintered 4crust on the mass 'of "sintering material in the pan 2 ad'acent'to what forms the lower edge of the'tilted pan 2 during the sintering operation. The po- -V rous hearth 9 in the sintering pan, extendi ing at an angle to the horiaonta t,

during the time molten cinder is formed in the mate- ,rals being sintered, freezing of the cinder in the voids in the orous hearth and in the adjacent surfaces ci) the materials being sintered sprevented, and clogging of the voids by the cmder and the resulting retardation Vor shutting ol of the air supply due to Aai choking up of the voidsin thel poroushearth as occurs 1n the prior processes, is avoided and overcome.`

As the latter ypart of each sintering operatio'n is not retarded by clogging of the poaby rous hearth, the material'in the pan is uniformly sintered'throughout the thickness of the mass, and spots or patches of unsin- .tered `materials are not found on the bottom surface of the mass, as inthe case of the processes 'heretofore known. The air supply `not being lessened by clogging of the porous hearth .by cinder freezing thereon, currents of'air' vare freely drawn through the sintered mass which isiporousafter the completion 'of the sintering operation so as to hastencooling of the mass-and prevent 'i the long'delays inthe completion of the .has been`l cooledgto 4 the dgsirede.;y

sntering operation* heretofore `caused A1n cooling the sinte'i-,

After the ofisinter inthe pan 2 After the sintering opi eration has extended over the upper'surface pan is further 'tilted so' as to be inverted i and the sinter is thereby discharged into the car15 positioned on the track 16 beneath the sintering pan. The sinter having been cooled to the desired extent, the last sintered portions of the mass will not break up into pieces smaller than is desired in the use to which the sinter is put.

, The above described operations are then carried out with successive quantities of sintering material.

l The advantages of our improved process, which will be ap reciated by those skilled in the artarise rom the use of a process Where-in the cinder is drawn olf as formed from vthe materials being sintered, and is removed from the sintering mass so as to prevent shutting oil' of the air supply and avoid'forming sinter which is not uniform in hardness and porosity. By removing the cinder as formed from the sintering mass, the use of materials have large va'- riations in the amount of carbon or other combustible material is made possible without the necessity of frequent and. correspondingly costly sampling and analyses of the materials.

Modifications in the steps of our improved I process may be made without departing` from the spirit of the invention as defined in the claims', and various types of apparatus'may be employed in carrying out our invention. We cla1m1-y L The process oi sintering flue dust and similar combustible materials `which con- Vsiete ,in igniting a body of the material, forcing air through the ignited mass to sup--` port combustion and propagate the sintering operation throughout the mass, and tilting the ignited mass to drain the molten cinder as 'formed therein. 4 2. The process of sntering flue dust and similar combustible materials lwhich consists, in supporting a bed of the 'materials on a porous hearth, igniting one face of the 'so-.Eormedmbed, forcing suflicient air into the bed `to promote combustion and propagzte the sintering operation throughout othe d, .and tilting the bed during the sintering operation-to' drain moltenl cinder as formed combustion and propagate the 'smtering thereof, and tilting the bed of material dur-` lng the sintering'operation to drain molten cinder fomedrtherein duringlth'e sintering i,

operation; v 4. p The process in forming aw bed of combustible sintering of sintering which consists i material, igxiiting one horizontal face-cf. 130

said bed, assing air through the ignited bed in a, direction at right angles to the ignited face of the bed to support combustion and form crust on said ignited face, and then tilting the bed and thereb)1 drawing ol 'molten cinder downwardly 1n a dilrection substantially parallel to the plane of the ignited face of said bed of material in completingV the sintering operation.v

5.. The process of sintering which consists l in forming a', -bed of combustible sintering material, igniting the upper horizontal face of said bed, passing air through the ignited 'ignited face of thi*I bed to su port oombus- 15 tion and form a crust onsei g I lgnited face, and then tilting the bed and ,thereby drawing-oli' molten! cinder downwardly 1n a direction subs ntiallyparallel to the ,plane of the i ite face yof said. bed of material 20 in comp eting the sintering operation.

In testimonywhereof we have hereunto Set our hands.

l. y/RTHUR J. BoYNToN.

ALBERT E. SANDS.

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