CA1062428A - Method and apparatus for continuous passivation of sponge iron material - Google Patents
Method and apparatus for continuous passivation of sponge iron materialInfo
- Publication number
- CA1062428A CA1062428A CA313,551A CA313551A CA1062428A CA 1062428 A CA1062428 A CA 1062428A CA 313551 A CA313551 A CA 313551A CA 1062428 A CA1062428 A CA 1062428A
- Authority
- CA
- Canada
- Prior art keywords
- compacting
- feed
- rolls
- hot
- sponge iron
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Expired
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B30—PRESSES
- B30B—PRESSES IN GENERAL
- B30B11/00—Presses specially adapted for forming shaped articles from material in particulate or plastic state, e.g. briquetting presses, tabletting presses
- B30B11/18—Presses specially adapted for forming shaped articles from material in particulate or plastic state, e.g. briquetting presses, tabletting presses using profiled rollers
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B22—CASTING; POWDER METALLURGY
- B22F—WORKING METALLIC POWDER; MANUFACTURE OF ARTICLES FROM METALLIC POWDER; MAKING METALLIC POWDER; APPARATUS OR DEVICES SPECIALLY ADAPTED FOR METALLIC POWDER
- B22F1/00—Metallic powder; Treatment of metallic powder, e.g. to facilitate working or to improve properties
- B22F1/14—Treatment of metallic powder
- B22F1/148—Agglomerating
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B30—PRESSES
- B30B—PRESSES IN GENERAL
- B30B15/00—Details of, or accessories for, presses; Auxiliary measures in connection with pressing
- B30B15/30—Feeding material to presses
- B30B15/302—Feeding material in particulate or plastic state to moulding presses
- B30B15/308—Feeding material in particulate or plastic state to moulding presses in a continuous manner, e.g. for roller presses, screw extrusion presses
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- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/0086—Conditioning, transformation of reduced iron ores
-
- C—CHEMISTRY; METALLURGY
- C21—METALLURGY OF IRON
- C21B—MANUFACTURE OF IRON OR STEEL
- C21B13/00—Making spongy iron or liquid steel, by direct processes
- C21B13/0086—Conditioning, transformation of reduced iron ores
- C21B13/0093—Protecting against oxidation
-
- C—CHEMISTRY; METALLURGY
- C22—METALLURGY; FERROUS OR NON-FERROUS ALLOYS; TREATMENT OF ALLOYS OR NON-FERROUS METALS
- C22B—PRODUCTION AND REFINING OF METALS; PRETREATMENT OF RAW MATERIALS
- C22B1/00—Preliminary treatment of ores or scrap
- C22B1/14—Agglomerating; Briquetting; Binding; Granulating
- C22B1/24—Binding; Briquetting ; Granulating
Landscapes
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Mechanical Engineering (AREA)
- General Life Sciences & Earth Sciences (AREA)
- Environmental & Geological Engineering (AREA)
- Geochemistry & Mineralogy (AREA)
- Geology (AREA)
- Manufacturing & Machinery (AREA)
- Life Sciences & Earth Sciences (AREA)
- Materials Engineering (AREA)
- Metallurgy (AREA)
- Organic Chemistry (AREA)
- Manufacture And Refinement Of Metals (AREA)
- Manufacture Of Metal Powder And Suspensions Thereof (AREA)
- Manufacture Of Iron (AREA)
- Powder Metallurgy (AREA)
Abstract
) ABSTRACT OF THE DISCLOSURE
A method and apparatus for continuous passivation of hot sponge iron material, the method consisting of feeding hot sponge iron material to a compactor, compacting the material to a high density elongated strip-like mass, cutting the mass longitudinally into a plurality of strips while simultaneously compacting the freshly cut longitudinal edges, cutting the strips transversely of their longitudinal dimensions while simultaneously compacting these freshly cut transverse edges. The apparatus consists of a feeder, a roll compactor for forming a high density continuous elongated mass and longitudinal and transverse shearing devices, along with the requisite control and transporting mechanisms.
A method and apparatus for continuous passivation of hot sponge iron material, the method consisting of feeding hot sponge iron material to a compactor, compacting the material to a high density elongated strip-like mass, cutting the mass longitudinally into a plurality of strips while simultaneously compacting the freshly cut longitudinal edges, cutting the strips transversely of their longitudinal dimensions while simultaneously compacting these freshly cut transverse edges. The apparatus consists of a feeder, a roll compactor for forming a high density continuous elongated mass and longitudinal and transverse shearing devices, along with the requisite control and transporting mechanisms.
Description
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- ` ~06242~
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This application ls a di~ision.o~ co-pendlng 252 920 ~i~ed ~ay 20, 1976.
Canadian Application No, CKGROUND OF THE INVENTION
Sponge tron, metali ked pellets or reduc~d metal materials are ~, proiuced by the dtrect retuctton o~ ores. "Metallized" ;n this sense r.~. ~ ~ doos not mean coa~ed with metai, but means nearly complete!y ~duced to - ~ ~etal, f.e., always tn excess of 75~, metal, and normally in excess o~ 8~L
~ctal In the praduct. Tht5 metalli~ed product ;s suitable for charging dlrectly to a me~al refining furnace as the feed matertal. In ferrous ;~ metallurgy, the product refcrred to Ts m~talltzed iron material, which Is ehargcd dlrectly to a steelmaklng Furnace, such as an clectric arc furnaça.
Stc~l ptants whlch utlltzQ mct~lllz~d Iron as a feed matcrial have no necd ~ for ~etallurglcal coal or coke. Further, such plants are economtcal at ;r,~ ` ~' , SH11 capacTtles and thus do not require the blgh capltal Investment of ~ A~ en P ~ t ~
~ 1~ 6Z~28 One of the prob1ems assoclated with the use of sponge Iron as a raw materlal In steelmaklng is Tts inherent tendency to reoxtdTze upon exposure to atmospheric condTtions. Hot sponge iron is extremely reactTve and oxidlzes spontaneously If contacted by oxygen Tn any form~ Thus, sponge Iron must be cooled in a reducing or neutral atmosphere. At room temperature, - . sponge iron ts so reactTve that It oxTdkes even when stored tn the open air.
Contact with water, likewise, causes rapld oxidation, which is commonly termed rustTng. STnee the oxidatTon of sponge iron i5 an exothermic reaction, thTs oxidatlon can result Tn spontaneous heatTng and ignition of -tO the sponge iron durTng storage or transport. For this reason, metallized sponge Tron has been classified a hazardous mat~rTal by the U~S. Coast 6uard, and Its bulk shipment tn the unstabilized condltion is prohibited.
~1 in some tnstances, reduced Iron in such form as sponge Iron or metallized iron pellets is produced in an Tntegrated steel plant as a raw rnaterial for the steelmaking furnaces. If it were possible to feed the hot ¦ reduced tron, at a temperature above 500 C ~about 930 F), dtrectly tnto ¦ the steelmakTng furnace, thls would result in a more economlcal steelmiaklng¦ process, inasmuch as the energy requTrelr.ents would be groatly reduced and - 1 ¦ hlgher producttvity would be obtained. it would be Imporative that hot 2C I spo~ige iron materTal be transported and handled In a controlled atmosphere, I as ~posure to atmospherTc aTr would result Tn an extremely hazardous ¦ sltuation. If the hot sponge tron could be passlvated sufftciently that it could b- transported by conventlonal equlpment wTth a mlnimal heat 1055, the steelmaklng process for whtch It sorves as a raw materlal could reallze ¦ the full beneflt of its heat content with attendant savings In onergy ~ ¦ eonsumptlon.
3 I Passlvi3tlon of sponge Iron is also desirablo becau~ oxldatTon¦ of sponge Tron, aftor havlng once been raduced, requTres a socond I reductton wlth an attendant Increase In energy consumptlon and C05t.
I Many att mpts have been made In the past to overcome, or . I ~ . .
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¦ plotseh ~ -1 ~ ~ . ,.
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~ lB6Z428 . . i, reduce, the rèoxidatlon of metalllzed pellets and to passîvate spongo Iron, ~ I
Illustratlve examples include the proposal to cover a bulk shlpmont of sponge lron wlth a thln polyurethane foam coating or other type of plastlc I, film to prevent oxygen or molsture from contactlng the spongo iron. It has also been suggested to cover such a bulk shipment with a thtn glass coating. U.S. Pa~ent No. 3 125 437 teaches a process for pass;vatlng sponge iron agalnst oxldatton in air by creating a thln protectlve skin on the sponge iron surface. Hot briquetting with roll type briquetting machTnery are taught ln U.S. Patents 3 116 996 and 3 174 846 to densify the , sponge iron, thereby mintmizing the suriace area of the reduced iron orc exposed to the oxldlzlng elements. These illustratlve, but ~ot exhaustivo examples demonstrate the many attempts to solve the prob1em.
Coatings on sponge iron require the use of a forelgn material which contaminates sponge iron without guaranteeing passivationO Such coatings are easily damaged, for ;nstance, a mere shiftlng of the materlal in Its contalner durlng transit may rupture the coat7ng. Although a protectlve oxlde skin ls a proven inhibitor to oxldation ln alr, It is subject to rustlng to hydrated ferric oxlde. Thus, such skln doos not prevent further oxldatlon by rusttng.
Heretofore, the hot briquetting of sponge iron has been a very ; promtsing process for passivation Inasmuch as It can be used to passivate bulk shlpments to a htgh degree, as well as to passivate hot sponge lron :
with temperatures as high as 900 C (about 1650 F), so that ;t can be transported on conventlona1 hot convoylng systems at hlgh temperature wtth-~ ~S out elther a prohlbitlvely high loss of m~tallizatlon or spontaneous !gnltlon.
; ~ens7flcatlon of sponge Iron, at least on tts surface, ls accompllshed by hot brlquettlng. The extorlor of the brlquet Is compressed to a denso layer whlch Is stable or passlvated. The Interlor of the brlquet remains less dense, I.e., spongy, and thus Is actlve and readily oxidtzed, but ls protectod by the more dense surface layer.
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Pletsch ',,- ;l . .
': ...... '..... .~,, ' '' "~' " . "' , , 106Z~Z8 Hot briquet~ing encounters certain mechanical problems.
Before the briquetting rolls start to wear, single briquets are easily produced. As soon as wear beings, briquets become connected to each other by webs, which requires that they be broken apart prior to shipment or handling. As roll ~ear lncreases, the problem of-breaking the briquets apart becomes more and more di~ficult. In addition, the breaking procedure produces fines and exposes the less densified interior of each briquet to oxidation, particularly if the breakage occurs through the briquet rather than through the ` 10 web. With increasing web thickness due to increasing wear, this occurs more and more frequently, Thus, although the greater pro-portion of each briquet is passivated, there is still a sufficient proportion of the briquet which is less passivated and subiect to reoxidation with a high loss of ~etallization.
For known strip breaking mechanisms, see German Patent 1,533,827.
- OBJECTS OF THE INVENTIO~
It is an obJect of this invention to provide a simpli~ied ' ~ and efficient method and apparatus for the passivation of sponge iron.
BRIEF SUMMARY OF THE I~V~TIO~
; The aforesaid ob~ects o~ this invention, and other ob~ects ~'~ which will become apparent as this de~cription proceeds, are achieved ; by providing hot 8pon~e iron compacting apparatus ~ollowed by a shearing apparatus. The hot compacting apparatus rolls the sponge iron into an elongated mass. The shearing apparatu~ cuts the mass across its longitudinal dimension, compacting the newly exposed edge~, and creating.small "compacts" which are easily handled, - tran8ported, and used in subsequent processes.
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il/J~ 4-:-` 1062~28 Where the compacting apparatus produceæ a relatively wide strip, ap~aratus may be provided for slittlng the elongated mass longi~udinally to produce a plurality of elongated masses.
In one particular aspect the parent application, afore-mentioned Canadian Application No. 252,920, is concerned with the.
provision of a method for forming a plurality of small, passi- .
vated, compact products from hot reacti~e particulate sponge iron comprising:
a) feeding said particulate sponge iron at a temperature of at least 600~C to a compacting apparatus;
b) compac~ting said particulate.sponge iron to form a continuous densified elongated metal strip;
c) longitudinally cutting said densified elongated strip si into a multiplicity of Iongitudinal strips; and d) further dividing said multiplicity of longitudinal strips at regular intervals by shearing them transversely to their longitudinal dimension and simultaneously densifying the newly . created surfaces normal to the longitudinal dimension, thus pro-ducing a plurality of small compacted sponge iron products, each 20 . having a dense skin on all faces, whereby the products are . resistant to atmospheric oxidation and suitable for bulk handling, storing, and shipping without additional passivating steps.
In another particular aspect the parent application, afore-mentioned Canadlan Application No. 2521920, i9 concerned with the provision of a compactedt passivated, metallized lron product useful as a feed material for a steelmaking process, said product having dense, substantially pore-free faces with a densified surface layer on each face, a less dense center with an average .. : . . .
. ~ . density of , . ~
~'~ '' . ' ~ `
06Z~4Z~3 `~ at l~ast 4.5 ~/cct and whereln from abou~ 75X to about 96~ of the total iron present is in the metallic state.
The present application, a division of aforementioned ~':" , . .
~` Canadian Application No, 252,9~0, is particularly concerned with ," the provision of an apparatus for continuously passivating hot, reactive particulate metal material comprising: a) means for feeding ... .
said particulate metal material to a compacting apparatus, said feeding means including means for excluding substantially all ; ., ! ~
~~ atmospheric air therefrom; b) means for compacting said particulate .....
~ lO metal to form a dense elongated metal mess; c) means for longi-:j ~ tudinally cutting said mass while simultaneously passivating its 'k". ` .' ~` newly cut edges immedlately after said compacting apparatus; and d) shearing means comprising t~o opposed cutting edges of metal .~ coacting along a shear plane ~or simultaneously dividing said . ~ .
~ elongated metal mass substantially normal to its longitudinal ~ , .
~ dimension and densifying the newly created surface by induced high :............... .
shear forces, whe~eby a completely passivated product is produced suitable for bulk handling, storing and shipping.
-~ While this invention is described in terms of sponge iron, it will be readily understood~by those skilled in the art that the ~: . .
.
invention is equally applicab}e to the compaction of metallized iron material in other forms such as pellets or fines, as well as other I metals whlch have been directly reduced from their oxides, or ores ,.
and which metals react in the same ~anner as and have comparable properties to sponge iron under oxidizing conditions.
.1 BRIEP DESCRIPTION OF THE DRAWINGS
For better understandlng of this invention, reference should be had to the accompanylng drawlngs, wherein:
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~ ~ Figure 1 ls an elevatlonal view of the preferred embodiment . . .~ - .
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of my lnvention with some parts removed.
' Figure 2 is a plan view of a pair of slitter rolls showing ..
t their interfltting configuration.
. Figure 3 is a plan view similar to Figure 2 on a larger ,....
; scale taken through the workpiece.
Figure 4 is a sectional view taken along the line IV-IV
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:~ of Figure 3.
, ;. .,:~, . .
~' Figure 5 is an end view of the compactor rolls and their e associated parts.
Figure 6 is a sectional view taken along the line VI-VI
of Figure 5, -,;'f'! Figure 7 is a schematic cross-sectional view of a workpiece about to be sheared longitudinally.
~`~ Figure 8 is a schematic view of a workpiece undergoing ,1 longitudina~ shearing and concomitant densification of its sheared edges.
; Figure 9 is a schematic elevational view of a workpiece 1 about to be sheared transversely, .. . .
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Figure 10 Ts a schematic elcvational vi~w of a workplece undor-;~ golng transverse shearing and concomltant denslflcat70n of Its shearod , edges.
DETAILED DESCRIPTION
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With speciflc reference to the form of the Inventlon iilustrated tn the drawings and referring particularly to Figure 1, apparatus for continuously passivating hot reactive particulate metal materlal conslsts i essentially of three bas1c parts, a material accumulator 10, a compactor ¦ 12 and a divider-d~nslfier 14. ~ ;~
1 Accumulator 10 may take the form of a surge bin 15 having slids valve 16 at ths bottom thereof positioned above a feed hopper 18, which hopper is adapted both to con~ain hot feed materlal 20 and to control the rate of feed of the materlal to the compactor apparatus 12. The feed material 20 may be sponge iron, pellets or tump or~, or a combinatlon ~i~ 15 thereof, which material has been reduced In an assoclated direct reductlon ^~ furnace 8. Feed hopper 18 Includes cheek plates 22, sho~wn In Figure 7 and 8, whlch bear against the ends of the bodtes of power drlven, large diameter , $ ¦ compactor rolls 24 and 26 to seal the Tnterlor of the hopper 18 against atmospherlc air. As shown, roll 24 is fixed in its chocks 28 wheraas roil ¦ 26 is movably mounted in horizontally movable roll chocks 30, the movement ~, I of which is controlled by hydrauiic cylinders 32. Rolls 24 and 26 may ¦ have a fiat contour or may have a sma11 collar at each end of the roll ¦ body~
~ ¦ The region from slide valve 16 to the nip of rolls 24 and 26 Is ;~ 25 ¦ deslgnated hereunder as the feedlng and compactlon zone.
1 ¦ ~ 5crapers 44a and 44b are plvotally mounted beneath the compacting rolls at pivot points 46a and 46b respectively, each of which is w~11 below ~ the center of gravity of Its respective scraper. Thus, the upper edge `r; of each scraper tends to maintain con~act wlth Its respectlve compactlng ~; roll. A tenslon sprlng 48 blases each scraper against Its compactlng ` ? -7-¦ ~ Pletsch ',', ' '. ' ~ . i, ~ , o~a428 ,¦ ~
~; roll to ensure sure contact, `, i~eneath the compactor rolls and aligned with the psss-11ne thereof are a palr of hor;zontally opposed shearing or slTtting rolls 34 and 36 for ~ longltudina1 s!ltting of wtde strip. Roll 34 is mounted In ftxed chocks 38 t ;; whlle roll 36 Is mounted In horizontally movable chocks 40 the` motion of ~!~ ~hich Is controlled by hydraullc cylinders 4~tt~ The shearlng rolls advantageously have a configuration as shown Tn Figures 2 and 3.
s A doctor device 50 which may also be known as a roll stripper or guide is located on the discharge side or bottom of each roll 34 and ~; 10 36. Such a guide may have the full contour of the roll, extending compietely ~ , across the roll body. Alternatively, the device may constst of a number æ . of guides each of whi~h fits into a recess 34a or snto a collar 34b (Figure 3) of the roll, respectively.
~ Aligned wtth the pass-lines of the compactor rolls and the slitter ;,. t5 rolls is anvil ~ er54, whlch likewise may have a horlzontal ~ j/c4/~
contour matching that of roll 34. A rotatiny shear 56, contatning a number of blade holders 58 with thetr assoclated blades 59, ts moùnted beneath ~ ;
the anvll 54 in such manner that the shear blades transversely cut the workpieces by shearlng them against the anvll. ~lades 59 preferably have a flat shearing face 60. A feed chute 61 may be provided beneath the rotary c ~ shear to collect the metallized iron compacts 62 and direct them into a ~, cooling tank 64 which is fl11ed with water. An apron conveyor 66 removes the compacts from the coollng tank, transferr7ng them to a belt conveyor 68 ~,~ for transshipment to a stockpile 70, The small amount of flne mater7al that may be produced by the shearing and abrasion of the compacts falls through the perforattons in the apron conveyor and co71ects in a funnel 72 which has a lock valve 74 at its lower extrem7ty, The funnel can be emptled Into ~n a trough car 76 per70d7cally to remove the f7nes from the system.
In operatlon, hot sponge Tron, pe71ets and/or lump material, ~;~ 30 Includtng flnes, 7s charged Into surge bln 12. Level control devlces ~ `; . ~ . ' . ' ~'.n` -8- PIetsch , . , . .
~ ¦ ; 31062 42~3 RJJ
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¦ 80 ~such as a C-E Invalco Nuclear Level Control manufactured by C-E Invalco ¦ DivTsTon of Com~ustion Engineering, IncO, Tu1sa, Oklahoma, U.S.A.) may b~
,~ ¦ interlocked with the speed control on the roll drives for rolls 24 3nd 26 ¦ to ensure sufficient volume of material to maintain a constant wldth of ¦ the elongated strips (Flgure 1).
: ¦ The hot sponge iron has a te~perature of at least 600 C
¦ preferably 700 to 800 C and an average metal!Tzation of at least about ¦ 75%, but normally at least 8~%, and preferably at least 9CP~O meta!llzed.
The hot sponge iron passes from the surge bln 12 through the region of the `~ 10 ¦ 5 lide valve 16 into feed hopper 18. The slide valve is in the open positlon ¦ during operation of the apparatus, and is closed only wnen the machinery ¦ is shut down. The feed hopper, slide valve and surge bin must be gas tight ¦ to prevent ambTent atr from contacting the hot, extremely reactive material.
;iX` ¦ The flow rate of hot sponge iron to the nip of the two compactlng rolls 24 1 15 ¦ and 26 may be controlled by a movable feed tongue mechan7sm 86. This ~ , I controls the volume of sponge iron reaching ~ne rolls, and thus the thick-;~, ¦ ness and density of the strlp produced by compactlon. If too great a volu~e :; ` ¦ of materTal is fed into the ~olls, they will open, producing a thicker strip ;hl; ¦ havlng an unfavorable density distribution or gradient. The feed tongue ô8 1 Ts pivotally attached to the feed hopper, and has an adjustlng arm 90 whtch ¦ extends outside the hopper. The tongue may extend the full width of the ¦ hopper, or a number of narrower tongues may be employed.
¦ Hot sponge tron is fed to the compactlng rolls by gravity. An alternative feeder arrangement such as a screw feeder may be used whlch wlll ¦ exert a positive feed pressure on the material enterlng the roll ntp. Thls ;; I wlll control both the rate and voiume of flow of the feed mater~al. .`
After entrainment of the hot sponge Iron Into the roll nlp, tha ij ¦ sponge Iron is contlnuously denslfled by the counterrotatlng ro11s 24 and " 26 whlch exert large compressive forces on the sponge iron causing formàtlon ;`1 30 of an Increa51ngly compacted Iron mass untll It reaches the narrowest gap ;.",,~ . ~ _g_ . ; ' ~ Pletsch .,,;,li ~ - ' - ' . .
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i at the hori~ontal center!tne of the rolls. During this denslfTcatlon procedure, the indlvldual pellets or lumps are deformed and the spongy structure of the iron is destroyed by the pressure of compaction exerted by the compacting rolls, and the flnes 0re asslmilated into the densTfied mass.
; ~ 5 The gas which has been in the interstices between the hot pellets as well as in the pores of the pellets, is foreeab1y expelled therefrom and escapes ~`; from the hopper 18 through gaps between the ends of the compacting rolls ~` and the cheek plates 22 as well as through gaps between the roll boiy and , the base of feed hopper 18. This gas, which remained in and around the 0 pellets on discharge from the direct reduction furnace 8 is reducing in character, and provides a steady stream of non-oxldizing gas to protect the feeding and compaction zone against contact by the surrounding atmoshor7c air. Thus it is unnecessary to provide a sophisticated sealTng system. At Startup a nltrogen purge is used. Nitrogen or other non-oxidizlng gas is Introduced to the feed hopper through orifice 92 ~Figures 5 and 6) in the -~ cheek plates 22 near the nip of the rolls. ~fter a few feet of compacted strlp has been formed, the nttrogen purge is stopped, as the reduclng gas ~ f orced out of t~e pores wlll displace the nitrogen and matntain a reduclng !~' '. ' atmosphere.
~; 20 Compaction of the hot sponge iron forms a continuous strtp or sheet S (Flgure 1~ having such high density that the formerly very high affinlty of the iron for oxygen is so far reduced that it is no longer subject to 'l catastrophic reoxidation. In fact oxldation of the surface of thls extremely dense materlal will now result In a very small loss of metalllzatlon The mean denslty of the strip depends on the thlckness of the : strlp. A pronounced density gradlent toward the less dense center of tho i strlp reduces the mean denslty wlth IncreasTng strlp thlckness. The mean i ~ density must be at least 4.5 grams per cubic centimeter, and preferably should be between 5 and 6 grams per cubtc centimeter. Below a density of 4.5 grams per cublc centlmeter, passlvatton Is insufflclent for long-term -tO- Pletsch ~"" . . .
,,'',.. ~ . . , . , . .
~: ,,, .. . .,, . - ,' , `` I lOtiZ4;~8 open bulk storage wlthout slgnlflcant loss of metalllzatlon. Note that whlle themean density of a thick strtp may be only 4.5, the surface contacted by the surrounding atmosphere has a very high densTty with an attendant high degree of passlvatlon.
During compaction, the compactlng rolls 24 and 26 become heated due to conduction of heat from the hot feed material Z0, ~he temperature of ; which has been increased by the extremely great amount o~ energy input that has been transformed into heat and is absorbed by the feed materTal. Exhaust fans 100 (Figures 5 and 6) may be employed to remove excess heat from the rolls~ For the exhaust fans to work efficiently, the compacting rolls 24 and 26 should be surrounded by an enclosure 102 best shown In Figurc 5.
Enclosure 102 has at least one, but preferably a multiplicity of air intakos -104 along ea h slde of its bottom face. The suction cr~ated by exhaust fans 100 will circulate amblent air through intakes 104 around compactlng ~1 15 rol ls 24 and 26 and out of enclosure 102 through the exhaust fans 100.
;, These fans may be associated with a dust coliector, bag house or precipltator to remove particulate material from the exhaust air.
~! Scrapers 44 act as roll gutdes for the compacting rolls 24 and ~, - 26 to prevent the elongated strip from wrapplng around one of the rolls.
In additTon the scrapers assist in guiding the strip into the slitting rolls 34 and 36. The scrapers 44 are b7ased against the compacting rolls by springs 48 and guide the strip into the pass-line of the slitting rolls~
,: Since the workplece is a wide strTp A upon exiting the densiflca-iS; ~ tion rolls, it is cut into narrower S strips (Figure 4) by the roll slltter 34, 36 which forces the hot, hlghly malleable strlp S Into the alternating grooves in each roll. This process creates sufflclent compres-,~ slve forces on the edges of the newly sl7t strips S to Increase the denslty of the material on the strtp edges sufftclently to accompllsh the desired passlvation along the longltudtnal edges. Deformation of the workpleces by sllttlng is shown in Flgures 7 and ô.
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The strTps S produced Tn the sllttlng apparatus are subsequently subdivided into small, completely passlvated pieces or corlpacts 62 which ~ -can be handled, stored and shlpped in bulk without degradation, using o~ly conventional equipment. The outer surface of each compact must be high1y densified to achieve complete passivatlon. Since the center of the strlp - is less dense than the strip surface, the dlviding process must sufficiently densify the newly created transverse surfaces to obtain complste passivation.
The temperature of the strip at this point in processing is sufficiently , ~ htgh to maintain the lron strip in a highly malleable rondition, particularly ?i 10 since the strip density is only about iO to 80% of its theoretical density.
- An alternative method of achieving simultaneous diviston and densiflcation of passivated pieces of material is high speeci cutting in ~r ~ ~ whTch so much energy Is introduceci locally that the resulting heat melts a i ~ thin layer of the metallic materialO Soltdification of the material forms .~, 15 dense protective skin on the new surfaces.~, Simultaneous division and densification of the strlp Is accompllsh-ed by moving the strlp p~st anvil 54 while drivlng blades 59 of rotary shear . 56 against the strlp. This action and the deformatlon of the sheared faces ~, of the resulting compacts are shown in Flgures 9 and 10. The stresses from deformation actually cause densification of that portton of the materlal ~,~ comprising the sheared faces. In fact, hot shearing compresses the matarlal at each face, rendering the sheared dimension less than that of the normal workpiece thickness.
If the compacts have been produced for shipment, they must be cooled to amblent temperature. Slnce the compacts are completely passlvated .;
cooling can be accomplished by quenching In or by water, or by any other ~' ; avai!able means. Sultable apparatus for water quenchlng has been tllustrated in Ftgure t and descrtbed above.
- Upon shearing, the compacted products rematn hot. If these , 3 compacts are to be used In an adjacent steel productng mlll, the inherent Pletseh ,,, ,. . , , . .
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heat In the compacts may bq utllized to reduce the energy Tnput required In ~; ¦ the m~lt shop and Increaso productlvlty, To accompllsh thls, the compacts ; ¦ are transferred without quenchtng or cooltng to a heavy-duty steel apron ¦ conveyor to be transported directly to a melting furnace. Since the compacts j ¦ ~ ¦ are In a passivated condttion, they can be transported with no speclal precautions in ambient air. It is deslrable, however, to protect the compacts I ~
; ¦ from cooling by wind, raln, snow, etc. Thus, the conveyor may be enclosed ¦ to protect it from cooling effects of the elements, and the conveyor may ~&~ ¦ be insulated to prevent heat loss from the compacts, particularly by con-. 10 ¦ vec~ionO If waste gas is available having a temperature greater than 700 C
; I From elther the steel mlll or from the direct reduction facTlity, thls gas may be introduced to the enclosure surroundtng the apron conveyor to -~ ¦ minlmize heat loss of the compacts durTng transpore. Suitable gases are ~; ¦ blast furnace gas, waste gas or spent reducing gas from a dTrect reducelon ~5 ¦ furnace, off gas from a metal refining furnace such as an electrlc furnace, ¦ and gaseous hydrocarbons. It is preferable that the gas be non-oxidizTng ¦ in character, but this ts not necessary due to the passlvatlon of the ~; ¦ eompacts.
¦ In its simplest form, my method for continuously passlvating a hot ; 20 ~ reactlve particulate metal comprehends feeding the partlculate metal 20 to ~ ¦ a compacting apparatus such as compacting rolls 24 and 26, compacting the 6~s~ ¦ partlculate metal material to form a dense elongated metal mass, followed ~ i~ ¦ by the slmultaneous divisisn of the elongated metal mass by cutting It ;r;~. ¦ across Its longitudinal dimension by apparatus such as shear 56 and anvil 54, ,~ 25 ¦ whlle s7multaneously denslfylng the newly created surfaces caused by such ; ¦ cutting, thus producing a completely passivated product sultable for bulk ¦ handllng, storlng and shlpplng without addltional passlvatlng steps, ¦ The iron compacts produced by this process have generally ¦ rectangular faces which form a substantlally rectangular paraileleplped.
,II 30 l It Is clear from the foregolng that I have overcor~ the ~,,',,.',,'~,, I . ' .
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¦ dlfficulties of prior art practices and have invented a method and appar2tus ~ ` ¦ for passlvating metalllc materials which are highly reactive and readlty sub-;i ¦ ject to oxidation. t have provided a slmplified and efflcient method and , ¦ apparatus for the passivation of sponge metal, the product of whtch has ¦ eonsistently high quality and which epparatus requires a minlmu~ of matn-- ¦ tenance. ~y passivating system produces a hot product that can be dtrectly x I transported to a metal reftning facility at the high temperature at whtch It ¦ completed the passtvatton process whereby the Inherent heat content of the ,~;; ¦ product w;ll reduce the energy tnput required Tn the metal refining process and reduce the melting time. A1ternatPvely the hot passivated product can be cooled for safe storage, handllng and tulk shtp~ent.
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This application ls a di~ision.o~ co-pendlng 252 920 ~i~ed ~ay 20, 1976.
Canadian Application No, CKGROUND OF THE INVENTION
Sponge tron, metali ked pellets or reduc~d metal materials are ~, proiuced by the dtrect retuctton o~ ores. "Metallized" ;n this sense r.~. ~ ~ doos not mean coa~ed with metai, but means nearly complete!y ~duced to - ~ ~etal, f.e., always tn excess of 75~, metal, and normally in excess o~ 8~L
~ctal In the praduct. Tht5 metalli~ed product ;s suitable for charging dlrectly to a me~al refining furnace as the feed matertal. In ferrous ;~ metallurgy, the product refcrred to Ts m~talltzed iron material, which Is ehargcd dlrectly to a steelmaklng Furnace, such as an clectric arc furnaça.
Stc~l ptants whlch utlltzQ mct~lllz~d Iron as a feed matcrial have no necd ~ for ~etallurglcal coal or coke. Further, such plants are economtcal at ;r,~ ` ~' , SH11 capacTtles and thus do not require the blgh capltal Investment of ~ A~ en P ~ t ~
~ 1~ 6Z~28 One of the prob1ems assoclated with the use of sponge Iron as a raw materlal In steelmaklng is Tts inherent tendency to reoxtdTze upon exposure to atmospheric condTtions. Hot sponge iron is extremely reactTve and oxidlzes spontaneously If contacted by oxygen Tn any form~ Thus, sponge Iron must be cooled in a reducing or neutral atmosphere. At room temperature, - . sponge iron ts so reactTve that It oxTdkes even when stored tn the open air.
Contact with water, likewise, causes rapld oxidation, which is commonly termed rustTng. STnee the oxidatTon of sponge iron i5 an exothermic reaction, thTs oxidatlon can result Tn spontaneous heatTng and ignition of -tO the sponge iron durTng storage or transport. For this reason, metallized sponge Tron has been classified a hazardous mat~rTal by the U~S. Coast 6uard, and Its bulk shipment tn the unstabilized condltion is prohibited.
~1 in some tnstances, reduced Iron in such form as sponge Iron or metallized iron pellets is produced in an Tntegrated steel plant as a raw rnaterial for the steelmaking furnaces. If it were possible to feed the hot ¦ reduced tron, at a temperature above 500 C ~about 930 F), dtrectly tnto ¦ the steelmakTng furnace, thls would result in a more economlcal steelmiaklng¦ process, inasmuch as the energy requTrelr.ents would be groatly reduced and - 1 ¦ hlgher producttvity would be obtained. it would be Imporative that hot 2C I spo~ige iron materTal be transported and handled In a controlled atmosphere, I as ~posure to atmospherTc aTr would result Tn an extremely hazardous ¦ sltuation. If the hot sponge tron could be passlvated sufftciently that it could b- transported by conventlonal equlpment wTth a mlnimal heat 1055, the steelmaklng process for whtch It sorves as a raw materlal could reallze ¦ the full beneflt of its heat content with attendant savings In onergy ~ ¦ eonsumptlon.
3 I Passlvi3tlon of sponge Iron is also desirablo becau~ oxldatTon¦ of sponge Tron, aftor havlng once been raduced, requTres a socond I reductton wlth an attendant Increase In energy consumptlon and C05t.
I Many att mpts have been made In the past to overcome, or . I ~ . .
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~ lB6Z428 . . i, reduce, the rèoxidatlon of metalllzed pellets and to passîvate spongo Iron, ~ I
Illustratlve examples include the proposal to cover a bulk shlpmont of sponge lron wlth a thln polyurethane foam coating or other type of plastlc I, film to prevent oxygen or molsture from contactlng the spongo iron. It has also been suggested to cover such a bulk shipment with a thtn glass coating. U.S. Pa~ent No. 3 125 437 teaches a process for pass;vatlng sponge iron agalnst oxldatton in air by creating a thln protectlve skin on the sponge iron surface. Hot briquetting with roll type briquetting machTnery are taught ln U.S. Patents 3 116 996 and 3 174 846 to densify the , sponge iron, thereby mintmizing the suriace area of the reduced iron orc exposed to the oxldlzlng elements. These illustratlve, but ~ot exhaustivo examples demonstrate the many attempts to solve the prob1em.
Coatings on sponge iron require the use of a forelgn material which contaminates sponge iron without guaranteeing passivationO Such coatings are easily damaged, for ;nstance, a mere shiftlng of the materlal in Its contalner durlng transit may rupture the coat7ng. Although a protectlve oxlde skin ls a proven inhibitor to oxldation ln alr, It is subject to rustlng to hydrated ferric oxlde. Thus, such skln doos not prevent further oxldatlon by rusttng.
Heretofore, the hot briquetting of sponge iron has been a very ; promtsing process for passivation Inasmuch as It can be used to passivate bulk shlpments to a htgh degree, as well as to passivate hot sponge lron :
with temperatures as high as 900 C (about 1650 F), so that ;t can be transported on conventlona1 hot convoylng systems at hlgh temperature wtth-~ ~S out elther a prohlbitlvely high loss of m~tallizatlon or spontaneous !gnltlon.
; ~ens7flcatlon of sponge Iron, at least on tts surface, ls accompllshed by hot brlquettlng. The extorlor of the brlquet Is compressed to a denso layer whlch Is stable or passlvated. The Interlor of the brlquet remains less dense, I.e., spongy, and thus Is actlve and readily oxidtzed, but ls protectod by the more dense surface layer.
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': ...... '..... .~,, ' '' "~' " . "' , , 106Z~Z8 Hot briquet~ing encounters certain mechanical problems.
Before the briquetting rolls start to wear, single briquets are easily produced. As soon as wear beings, briquets become connected to each other by webs, which requires that they be broken apart prior to shipment or handling. As roll ~ear lncreases, the problem of-breaking the briquets apart becomes more and more di~ficult. In addition, the breaking procedure produces fines and exposes the less densified interior of each briquet to oxidation, particularly if the breakage occurs through the briquet rather than through the ` 10 web. With increasing web thickness due to increasing wear, this occurs more and more frequently, Thus, although the greater pro-portion of each briquet is passivated, there is still a sufficient proportion of the briquet which is less passivated and subiect to reoxidation with a high loss of ~etallization.
For known strip breaking mechanisms, see German Patent 1,533,827.
- OBJECTS OF THE INVENTIO~
It is an obJect of this invention to provide a simpli~ied ' ~ and efficient method and apparatus for the passivation of sponge iron.
BRIEF SUMMARY OF THE I~V~TIO~
; The aforesaid ob~ects o~ this invention, and other ob~ects ~'~ which will become apparent as this de~cription proceeds, are achieved ; by providing hot 8pon~e iron compacting apparatus ~ollowed by a shearing apparatus. The hot compacting apparatus rolls the sponge iron into an elongated mass. The shearing apparatu~ cuts the mass across its longitudinal dimension, compacting the newly exposed edge~, and creating.small "compacts" which are easily handled, - tran8ported, and used in subsequent processes.
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il/J~ 4-:-` 1062~28 Where the compacting apparatus produceæ a relatively wide strip, ap~aratus may be provided for slittlng the elongated mass longi~udinally to produce a plurality of elongated masses.
In one particular aspect the parent application, afore-mentioned Canadian Application No. 252,920, is concerned with the.
provision of a method for forming a plurality of small, passi- .
vated, compact products from hot reacti~e particulate sponge iron comprising:
a) feeding said particulate sponge iron at a temperature of at least 600~C to a compacting apparatus;
b) compac~ting said particulate.sponge iron to form a continuous densified elongated metal strip;
c) longitudinally cutting said densified elongated strip si into a multiplicity of Iongitudinal strips; and d) further dividing said multiplicity of longitudinal strips at regular intervals by shearing them transversely to their longitudinal dimension and simultaneously densifying the newly . created surfaces normal to the longitudinal dimension, thus pro-ducing a plurality of small compacted sponge iron products, each 20 . having a dense skin on all faces, whereby the products are . resistant to atmospheric oxidation and suitable for bulk handling, storing, and shipping without additional passivating steps.
In another particular aspect the parent application, afore-mentioned Canadlan Application No. 2521920, i9 concerned with the provision of a compactedt passivated, metallized lron product useful as a feed material for a steelmaking process, said product having dense, substantially pore-free faces with a densified surface layer on each face, a less dense center with an average .. : . . .
. ~ . density of , . ~
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06Z~4Z~3 `~ at l~ast 4.5 ~/cct and whereln from abou~ 75X to about 96~ of the total iron present is in the metallic state.
The present application, a division of aforementioned ~':" , . .
~` Canadian Application No, 252,9~0, is particularly concerned with ," the provision of an apparatus for continuously passivating hot, reactive particulate metal material comprising: a) means for feeding ... .
said particulate metal material to a compacting apparatus, said feeding means including means for excluding substantially all ; ., ! ~
~~ atmospheric air therefrom; b) means for compacting said particulate .....
~ lO metal to form a dense elongated metal mess; c) means for longi-:j ~ tudinally cutting said mass while simultaneously passivating its 'k". ` .' ~` newly cut edges immedlately after said compacting apparatus; and d) shearing means comprising t~o opposed cutting edges of metal .~ coacting along a shear plane ~or simultaneously dividing said . ~ .
~ elongated metal mass substantially normal to its longitudinal ~ , .
~ dimension and densifying the newly created surface by induced high :............... .
shear forces, whe~eby a completely passivated product is produced suitable for bulk handling, storing and shipping.
-~ While this invention is described in terms of sponge iron, it will be readily understood~by those skilled in the art that the ~: . .
.
invention is equally applicab}e to the compaction of metallized iron material in other forms such as pellets or fines, as well as other I metals whlch have been directly reduced from their oxides, or ores ,.
and which metals react in the same ~anner as and have comparable properties to sponge iron under oxidizing conditions.
.1 BRIEP DESCRIPTION OF THE DRAWINGS
For better understandlng of this invention, reference should be had to the accompanylng drawlngs, wherein:
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~ ~ Figure 1 ls an elevatlonal view of the preferred embodiment . . .~ - .
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of my lnvention with some parts removed.
' Figure 2 is a plan view of a pair of slitter rolls showing ..
t their interfltting configuration.
. Figure 3 is a plan view similar to Figure 2 on a larger ,....
; scale taken through the workpiece.
Figure 4 is a sectional view taken along the line IV-IV
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~' Figure 5 is an end view of the compactor rolls and their e associated parts.
Figure 6 is a sectional view taken along the line VI-VI
of Figure 5, -,;'f'! Figure 7 is a schematic cross-sectional view of a workpiece about to be sheared longitudinally.
~`~ Figure 8 is a schematic view of a workpiece undergoing ,1 longitudina~ shearing and concomitant densification of its sheared edges.
; Figure 9 is a schematic elevational view of a workpiece 1 about to be sheared transversely, .. . .
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Figure 10 Ts a schematic elcvational vi~w of a workplece undor-;~ golng transverse shearing and concomltant denslflcat70n of Its shearod , edges.
DETAILED DESCRIPTION
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With speciflc reference to the form of the Inventlon iilustrated tn the drawings and referring particularly to Figure 1, apparatus for continuously passivating hot reactive particulate metal materlal conslsts i essentially of three bas1c parts, a material accumulator 10, a compactor ¦ 12 and a divider-d~nslfier 14. ~ ;~
1 Accumulator 10 may take the form of a surge bin 15 having slids valve 16 at ths bottom thereof positioned above a feed hopper 18, which hopper is adapted both to con~ain hot feed materlal 20 and to control the rate of feed of the materlal to the compactor apparatus 12. The feed material 20 may be sponge iron, pellets or tump or~, or a combinatlon ~i~ 15 thereof, which material has been reduced In an assoclated direct reductlon ^~ furnace 8. Feed hopper 18 Includes cheek plates 22, sho~wn In Figure 7 and 8, whlch bear against the ends of the bodtes of power drlven, large diameter , $ ¦ compactor rolls 24 and 26 to seal the Tnterlor of the hopper 18 against atmospherlc air. As shown, roll 24 is fixed in its chocks 28 wheraas roil ¦ 26 is movably mounted in horizontally movable roll chocks 30, the movement ~, I of which is controlled by hydrauiic cylinders 32. Rolls 24 and 26 may ¦ have a fiat contour or may have a sma11 collar at each end of the roll ¦ body~
~ ¦ The region from slide valve 16 to the nip of rolls 24 and 26 Is ;~ 25 ¦ deslgnated hereunder as the feedlng and compactlon zone.
1 ¦ ~ 5crapers 44a and 44b are plvotally mounted beneath the compacting rolls at pivot points 46a and 46b respectively, each of which is w~11 below ~ the center of gravity of Its respective scraper. Thus, the upper edge `r; of each scraper tends to maintain con~act wlth Its respectlve compactlng ~; roll. A tenslon sprlng 48 blases each scraper against Its compactlng ` ? -7-¦ ~ Pletsch ',', ' '. ' ~ . i, ~ , o~a428 ,¦ ~
~; roll to ensure sure contact, `, i~eneath the compactor rolls and aligned with the psss-11ne thereof are a palr of hor;zontally opposed shearing or slTtting rolls 34 and 36 for ~ longltudina1 s!ltting of wtde strip. Roll 34 is mounted In ftxed chocks 38 t ;; whlle roll 36 Is mounted In horizontally movable chocks 40 the` motion of ~!~ ~hich Is controlled by hydraullc cylinders 4~tt~ The shearlng rolls advantageously have a configuration as shown Tn Figures 2 and 3.
s A doctor device 50 which may also be known as a roll stripper or guide is located on the discharge side or bottom of each roll 34 and ~; 10 36. Such a guide may have the full contour of the roll, extending compietely ~ , across the roll body. Alternatively, the device may constst of a number æ . of guides each of whi~h fits into a recess 34a or snto a collar 34b (Figure 3) of the roll, respectively.
~ Aligned wtth the pass-lines of the compactor rolls and the slitter ;,. t5 rolls is anvil ~ er54, whlch likewise may have a horlzontal ~ j/c4/~
contour matching that of roll 34. A rotatiny shear 56, contatning a number of blade holders 58 with thetr assoclated blades 59, ts moùnted beneath ~ ;
the anvll 54 in such manner that the shear blades transversely cut the workpieces by shearlng them against the anvll. ~lades 59 preferably have a flat shearing face 60. A feed chute 61 may be provided beneath the rotary c ~ shear to collect the metallized iron compacts 62 and direct them into a ~, cooling tank 64 which is fl11ed with water. An apron conveyor 66 removes the compacts from the coollng tank, transferr7ng them to a belt conveyor 68 ~,~ for transshipment to a stockpile 70, The small amount of flne mater7al that may be produced by the shearing and abrasion of the compacts falls through the perforattons in the apron conveyor and co71ects in a funnel 72 which has a lock valve 74 at its lower extrem7ty, The funnel can be emptled Into ~n a trough car 76 per70d7cally to remove the f7nes from the system.
In operatlon, hot sponge Tron, pe71ets and/or lump material, ~;~ 30 Includtng flnes, 7s charged Into surge bln 12. Level control devlces ~ `; . ~ . ' . ' ~'.n` -8- PIetsch , . , . .
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¦ 80 ~such as a C-E Invalco Nuclear Level Control manufactured by C-E Invalco ¦ DivTsTon of Com~ustion Engineering, IncO, Tu1sa, Oklahoma, U.S.A.) may b~
,~ ¦ interlocked with the speed control on the roll drives for rolls 24 3nd 26 ¦ to ensure sufficient volume of material to maintain a constant wldth of ¦ the elongated strips (Flgure 1).
: ¦ The hot sponge iron has a te~perature of at least 600 C
¦ preferably 700 to 800 C and an average metal!Tzation of at least about ¦ 75%, but normally at least 8~%, and preferably at least 9CP~O meta!llzed.
The hot sponge iron passes from the surge bln 12 through the region of the `~ 10 ¦ 5 lide valve 16 into feed hopper 18. The slide valve is in the open positlon ¦ during operation of the apparatus, and is closed only wnen the machinery ¦ is shut down. The feed hopper, slide valve and surge bin must be gas tight ¦ to prevent ambTent atr from contacting the hot, extremely reactive material.
;iX` ¦ The flow rate of hot sponge iron to the nip of the two compactlng rolls 24 1 15 ¦ and 26 may be controlled by a movable feed tongue mechan7sm 86. This ~ , I controls the volume of sponge iron reaching ~ne rolls, and thus the thick-;~, ¦ ness and density of the strlp produced by compactlon. If too great a volu~e :; ` ¦ of materTal is fed into the ~olls, they will open, producing a thicker strip ;hl; ¦ havlng an unfavorable density distribution or gradient. The feed tongue ô8 1 Ts pivotally attached to the feed hopper, and has an adjustlng arm 90 whtch ¦ extends outside the hopper. The tongue may extend the full width of the ¦ hopper, or a number of narrower tongues may be employed.
¦ Hot sponge tron is fed to the compactlng rolls by gravity. An alternative feeder arrangement such as a screw feeder may be used whlch wlll ¦ exert a positive feed pressure on the material enterlng the roll ntp. Thls ;; I wlll control both the rate and voiume of flow of the feed mater~al. .`
After entrainment of the hot sponge Iron Into the roll nlp, tha ij ¦ sponge Iron is contlnuously denslfled by the counterrotatlng ro11s 24 and " 26 whlch exert large compressive forces on the sponge iron causing formàtlon ;`1 30 of an Increa51ngly compacted Iron mass untll It reaches the narrowest gap ;.",,~ . ~ _g_ . ; ' ~ Pletsch .,,;,li ~ - ' - ' . .
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i at the hori~ontal center!tne of the rolls. During this denslfTcatlon procedure, the indlvldual pellets or lumps are deformed and the spongy structure of the iron is destroyed by the pressure of compaction exerted by the compacting rolls, and the flnes 0re asslmilated into the densTfied mass.
; ~ 5 The gas which has been in the interstices between the hot pellets as well as in the pores of the pellets, is foreeab1y expelled therefrom and escapes ~`; from the hopper 18 through gaps between the ends of the compacting rolls ~` and the cheek plates 22 as well as through gaps between the roll boiy and , the base of feed hopper 18. This gas, which remained in and around the 0 pellets on discharge from the direct reduction furnace 8 is reducing in character, and provides a steady stream of non-oxldizing gas to protect the feeding and compaction zone against contact by the surrounding atmoshor7c air. Thus it is unnecessary to provide a sophisticated sealTng system. At Startup a nltrogen purge is used. Nitrogen or other non-oxidizlng gas is Introduced to the feed hopper through orifice 92 ~Figures 5 and 6) in the -~ cheek plates 22 near the nip of the rolls. ~fter a few feet of compacted strlp has been formed, the nttrogen purge is stopped, as the reduclng gas ~ f orced out of t~e pores wlll displace the nitrogen and matntain a reduclng !~' '. ' atmosphere.
~; 20 Compaction of the hot sponge iron forms a continuous strtp or sheet S (Flgure 1~ having such high density that the formerly very high affinlty of the iron for oxygen is so far reduced that it is no longer subject to 'l catastrophic reoxidation. In fact oxldation of the surface of thls extremely dense materlal will now result In a very small loss of metalllzatlon The mean denslty of the strip depends on the thlckness of the : strlp. A pronounced density gradlent toward the less dense center of tho i strlp reduces the mean denslty wlth IncreasTng strlp thlckness. The mean i ~ density must be at least 4.5 grams per cubic centimeter, and preferably should be between 5 and 6 grams per cubtc centimeter. Below a density of 4.5 grams per cublc centlmeter, passlvatton Is insufflclent for long-term -tO- Pletsch ~"" . . .
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~: ,,, .. . .,, . - ,' , `` I lOtiZ4;~8 open bulk storage wlthout slgnlflcant loss of metalllzatlon. Note that whlle themean density of a thick strtp may be only 4.5, the surface contacted by the surrounding atmosphere has a very high densTty with an attendant high degree of passlvatlon.
During compaction, the compactlng rolls 24 and 26 become heated due to conduction of heat from the hot feed material Z0, ~he temperature of ; which has been increased by the extremely great amount o~ energy input that has been transformed into heat and is absorbed by the feed materTal. Exhaust fans 100 (Figures 5 and 6) may be employed to remove excess heat from the rolls~ For the exhaust fans to work efficiently, the compacting rolls 24 and 26 should be surrounded by an enclosure 102 best shown In Figurc 5.
Enclosure 102 has at least one, but preferably a multiplicity of air intakos -104 along ea h slde of its bottom face. The suction cr~ated by exhaust fans 100 will circulate amblent air through intakes 104 around compactlng ~1 15 rol ls 24 and 26 and out of enclosure 102 through the exhaust fans 100.
;, These fans may be associated with a dust coliector, bag house or precipltator to remove particulate material from the exhaust air.
~! Scrapers 44 act as roll gutdes for the compacting rolls 24 and ~, - 26 to prevent the elongated strip from wrapplng around one of the rolls.
In additTon the scrapers assist in guiding the strip into the slitting rolls 34 and 36. The scrapers 44 are b7ased against the compacting rolls by springs 48 and guide the strip into the pass-line of the slitting rolls~
,: Since the workplece is a wide strTp A upon exiting the densiflca-iS; ~ tion rolls, it is cut into narrower S strips (Figure 4) by the roll slltter 34, 36 which forces the hot, hlghly malleable strlp S Into the alternating grooves in each roll. This process creates sufflclent compres-,~ slve forces on the edges of the newly sl7t strips S to Increase the denslty of the material on the strtp edges sufftclently to accompllsh the desired passlvation along the longltudtnal edges. Deformation of the workpleces by sllttlng is shown in Flgures 7 and ô.
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The strTps S produced Tn the sllttlng apparatus are subsequently subdivided into small, completely passlvated pieces or corlpacts 62 which ~ -can be handled, stored and shlpped in bulk without degradation, using o~ly conventional equipment. The outer surface of each compact must be high1y densified to achieve complete passivatlon. Since the center of the strlp - is less dense than the strip surface, the dlviding process must sufficiently densify the newly created transverse surfaces to obtain complste passivation.
The temperature of the strip at this point in processing is sufficiently , ~ htgh to maintain the lron strip in a highly malleable rondition, particularly ?i 10 since the strip density is only about iO to 80% of its theoretical density.
- An alternative method of achieving simultaneous diviston and densiflcation of passivated pieces of material is high speeci cutting in ~r ~ ~ whTch so much energy Is introduceci locally that the resulting heat melts a i ~ thin layer of the metallic materialO Soltdification of the material forms .~, 15 dense protective skin on the new surfaces.~, Simultaneous division and densification of the strlp Is accompllsh-ed by moving the strlp p~st anvil 54 while drivlng blades 59 of rotary shear . 56 against the strlp. This action and the deformatlon of the sheared faces ~, of the resulting compacts are shown in Flgures 9 and 10. The stresses from deformation actually cause densification of that portton of the materlal ~,~ comprising the sheared faces. In fact, hot shearing compresses the matarlal at each face, rendering the sheared dimension less than that of the normal workpiece thickness.
If the compacts have been produced for shipment, they must be cooled to amblent temperature. Slnce the compacts are completely passlvated .;
cooling can be accomplished by quenching In or by water, or by any other ~' ; avai!able means. Sultable apparatus for water quenchlng has been tllustrated in Ftgure t and descrtbed above.
- Upon shearing, the compacted products rematn hot. If these , 3 compacts are to be used In an adjacent steel productng mlll, the inherent Pletseh ,,, ,. . , , . .
, , , ' , ' , `: ,, . ~ ,~ . , , , . .. ',: . " , . ..
~ I l mJJ
; ~- I ~0~2428 ~',' I . . . .
heat In the compacts may bq utllized to reduce the energy Tnput required In ~; ¦ the m~lt shop and Increaso productlvlty, To accompllsh thls, the compacts ; ¦ are transferred without quenchtng or cooltng to a heavy-duty steel apron ¦ conveyor to be transported directly to a melting furnace. Since the compacts j ¦ ~ ¦ are In a passivated condttion, they can be transported with no speclal precautions in ambient air. It is deslrable, however, to protect the compacts I ~
; ¦ from cooling by wind, raln, snow, etc. Thus, the conveyor may be enclosed ¦ to protect it from cooling effects of the elements, and the conveyor may ~&~ ¦ be insulated to prevent heat loss from the compacts, particularly by con-. 10 ¦ vec~ionO If waste gas is available having a temperature greater than 700 C
; I From elther the steel mlll or from the direct reduction facTlity, thls gas may be introduced to the enclosure surroundtng the apron conveyor to -~ ¦ minlmize heat loss of the compacts durTng transpore. Suitable gases are ~; ¦ blast furnace gas, waste gas or spent reducing gas from a dTrect reducelon ~5 ¦ furnace, off gas from a metal refining furnace such as an electrlc furnace, ¦ and gaseous hydrocarbons. It is preferable that the gas be non-oxidizTng ¦ in character, but this ts not necessary due to the passlvatlon of the ~; ¦ eompacts.
¦ In its simplest form, my method for continuously passlvating a hot ; 20 ~ reactlve particulate metal comprehends feeding the partlculate metal 20 to ~ ¦ a compacting apparatus such as compacting rolls 24 and 26, compacting the 6~s~ ¦ partlculate metal material to form a dense elongated metal mass, followed ~ i~ ¦ by the slmultaneous divisisn of the elongated metal mass by cutting It ;r;~. ¦ across Its longitudinal dimension by apparatus such as shear 56 and anvil 54, ,~ 25 ¦ whlle s7multaneously denslfylng the newly created surfaces caused by such ; ¦ cutting, thus producing a completely passivated product sultable for bulk ¦ handllng, storlng and shlpplng without addltional passlvatlng steps, ¦ The iron compacts produced by this process have generally ¦ rectangular faces which form a substantlally rectangular paraileleplped.
,II 30 l It Is clear from the foregolng that I have overcor~ the ~,,',,.',,'~,, I . ' .
- I -t3-, ~ - I Pletsch -',~'.. ':''' ''' , I ' .
i' . ! ; ' ' ,, ,' ! ` ' 106Z4Z8 1 ~
¦ dlfficulties of prior art practices and have invented a method and appar2tus ~ ` ¦ for passlvating metalllc materials which are highly reactive and readlty sub-;i ¦ ject to oxidation. t have provided a slmplified and efflcient method and , ¦ apparatus for the passivation of sponge metal, the product of whtch has ¦ eonsistently high quality and which epparatus requires a minlmu~ of matn-- ¦ tenance. ~y passivating system produces a hot product that can be dtrectly x I transported to a metal reftning facility at the high temperature at whtch It ¦ completed the passtvatton process whereby the Inherent heat content of the ,~;; ¦ product w;ll reduce the energy tnput required Tn the metal refining process and reduce the melting time. A1ternatPvely the hot passivated product can be cooled for safe storage, handllng and tulk shtp~ent.
.' . , . ., ~'''``' . " .
. .
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. .
,' .
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.'' . ~ , . .' ;`i ~ -14- PietsCh ., ., , ~ . .
Claims (14)
PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:
1. Apparatus for continuously passivating hot, reactive particulate metal material comprising:
a) means for feeding said particulate metal material to a compacting apparatus, said feeding means including means for excluding substantially all atmospheric air therefrom;
b) means for compacting said particulate metal to form a dense elongated metal mass;
c) means for longitudinally cutting said mass while simultaneously passivating its newly cut edges immediately after said compacting apparatus; and d) shearing means comprising two opposed cutting edges of metal coacting along a shear plane for simultaneously dividing said elongated metal mass substantially normal to its longitudinal dimension and densifying the newly created surface by induced high shear forces, whereby a completely passivated product is produced suitable for bulk handling, storing and shipping.
a) means for feeding said particulate metal material to a compacting apparatus, said feeding means including means for excluding substantially all atmospheric air therefrom;
b) means for compacting said particulate metal to form a dense elongated metal mass;
c) means for longitudinally cutting said mass while simultaneously passivating its newly cut edges immediately after said compacting apparatus; and d) shearing means comprising two opposed cutting edges of metal coacting along a shear plane for simultaneously dividing said elongated metal mass substantially normal to its longitudinal dimension and densifying the newly created surface by induced high shear forces, whereby a completely passivated product is produced suitable for bulk handling, storing and shipping.
2. Apparatus according to Claim 1 wherein said feed means includes means for controlling the rate of feed of said particulate material to said compacting means.
3. Apparatus according to Claim 1 wherein said feed means is a hopper therefrom.
4. Apparatus according to Claim 3 wherein said feed means is a gravity flow hopper.
5. Apparatus according to Claim 1 wherein said compacting means is a pair of compression rolls,
6. Apparatus according to Claim 5 wherein said compression rolls are horizontally opposed.
7. Apparatus according to Claim 6 wherein said feed means includes a feed tongue for directing and controlling the amount of particulate metal material fed to the nip of the rolls.
8. Apparatus according to Claim 2 wherein said means for controlling the rate of feed is a screw feeder.
9. Apparatus according to Claim 1 wherein said shearing means comprises a stationary anvil and a shear knife mounted for angular rotation about a horizontal axis.
10. Apparatus according to Claim 1 wherein said longitudinal cutting means is a pair of horizontally opposed slitter rolls having opposed collars and recesses.
11. Apparatus according to Claim 1 further comprising means for cooling said product to ambient temperature.
12. Apparatus according to Claim 1 further comprising means for transporting said product at high temperatures, directly to a metal refining furnace.
13. Apparatus according to Claim 12 further comprising an enclosure around said transporting means.
14. Apparatus according to Claim 13 wherein said enclosure is substantially gas-tight and includes means for introducing hot gases into the interior thereof to maintain the temperature of the hot product at least about 700°C.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US58418475A | 1975-06-05 | 1975-06-05 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA1062428A true CA1062428A (en) | 1979-09-18 |
Family
ID=24336244
Family Applications (2)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA252,920A Expired CA1063835A (en) | 1975-06-05 | 1976-05-20 | Method and apparatus for continuous passivation of sponge iron material |
| CA313,551A Expired CA1062428A (en) | 1975-06-05 | 1978-10-17 | Method and apparatus for continuous passivation of sponge iron material |
Family Applications Before (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA252,920A Expired CA1063835A (en) | 1975-06-05 | 1976-05-20 | Method and apparatus for continuous passivation of sponge iron material |
Country Status (12)
| Country | Link |
|---|---|
| JP (1) | JPS51148610A (en) |
| AR (1) | AR208785A1 (en) |
| AU (1) | AU501229B2 (en) |
| BR (1) | BR7603290A (en) |
| CA (2) | CA1063835A (en) |
| DE (1) | DE2625223C3 (en) |
| EG (1) | EG12017A (en) |
| FR (1) | FR2313450A1 (en) |
| GB (1) | GB1504088A (en) |
| KE (1) | KE3139A (en) |
| MY (1) | MY8100378A (en) |
| ZA (1) | ZA762594B (en) |
Families Citing this family (15)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE2852964A1 (en) * | 1978-12-07 | 1980-06-26 | Krupp Polysius Ag | METHOD AND SYSTEM FOR REDUCING ORES |
| JPS55119116A (en) * | 1979-03-02 | 1980-09-12 | Agency Of Ind Science & Technol | Preventive method for re-oxidation of reduced iron powder and its device |
| JPS56160900A (en) * | 1980-05-16 | 1981-12-10 | Mitsubishi Heavy Ind Ltd | Briquette machine |
| DE3509616A1 (en) * | 1985-02-27 | 1986-09-04 | Korf Engineering GmbH, 4000 Düsseldorf | METHOD FOR COMPACTING IRON PARTICLES AND THE FOLLOWING BREAKAGE OF THE COMPACT IRON STRIP AND DEVICE FOR CARRYING OUT THIS METHOD |
| DE3732351A1 (en) * | 1987-09-25 | 1989-04-06 | Metallgesellschaft Ag | METHOD FOR PRODUCING BINDERLESS BRIQUETTES FROM STEEL DUST |
| AT404361B (en) * | 1995-01-23 | 1998-11-25 | Voest Alpine Ind Anlagen | METHOD AND DEVICE FOR COOLING HOT IRON SPONGE |
| DE10156735C2 (en) * | 2001-11-19 | 2003-10-30 | Koeppern & Co Kg Maschf | Process for the hot granulation of metal-containing material particles, such as sponge iron, metallurgical dust, metallurgical residues etc. |
| JP4966200B2 (en) * | 2004-10-19 | 2012-07-04 | ポスコ | Apparatus for producing agglomerates of reduced product containing reduced iron powder and pig iron production device provided with the same |
| DE102005006492A1 (en) * | 2005-02-12 | 2006-08-24 | S&B Industrial Minerals Gmbh | Process and apparatus for producing swellable coarse grains |
| KR101429643B1 (en) * | 2012-12-07 | 2014-08-13 | 주식회사 포스코 | Apparatus for separating plate-shaped hbi particles |
| JP5971141B2 (en) * | 2013-02-01 | 2016-08-17 | 新東工業株式会社 | Briquette machine |
| CN109093107B (en) * | 2018-08-27 | 2021-11-02 | 陕西安康三航纳米科技股份有限公司 | Rotary superfine/nano powder passivation device |
| RU2735086C1 (en) * | 2020-04-03 | 2020-10-28 | Федеральное государственное бюджетное образовательное учреждение высшего образования "Алтайский государственный аграрный университет" (ФГБОУ ВО Алтайский ГАУ) | Pelletizing roller press |
| CN114230215A (en) * | 2021-12-09 | 2022-03-25 | 南京广兰建材科技有限公司 | Preparation method for producing concrete by using production wastewater |
| DE102022101419A1 (en) * | 2022-01-21 | 2023-07-27 | Maschinenfabrik Köppern Gmbh & Co. Kg | Device for cutting up a strand of briquettes |
-
1976
- 1976-04-30 ZA ZA762594A patent/ZA762594B/en unknown
- 1976-05-03 AU AU13573/76A patent/AU501229B2/en not_active Expired
- 1976-05-14 AR AR263292A patent/AR208785A1/en active
- 1976-05-19 GB GB20757/76A patent/GB1504088A/en not_active Expired
- 1976-05-20 CA CA252,920A patent/CA1063835A/en not_active Expired
- 1976-05-22 EG EG301/76A patent/EG12017A/en active
- 1976-05-25 BR BR7603290A patent/BR7603290A/en unknown
- 1976-06-03 FR FR7616767A patent/FR2313450A1/en active Granted
- 1976-06-04 JP JP51065469A patent/JPS51148610A/en active Granted
- 1976-06-04 DE DE2625223A patent/DE2625223C3/en not_active Expired
-
1978
- 1978-10-17 CA CA313,551A patent/CA1062428A/en not_active Expired
-
1981
- 1981-07-06 KE KE3139A patent/KE3139A/en unknown
- 1981-12-30 MY MY378/81A patent/MY8100378A/en unknown
Also Published As
| Publication number | Publication date |
|---|---|
| KE3139A (en) | 1981-07-24 |
| JPS51148610A (en) | 1976-12-21 |
| DE2625223C3 (en) | 1981-03-19 |
| DE2625223B2 (en) | 1980-07-31 |
| MY8100378A (en) | 1981-12-31 |
| BR7603290A (en) | 1977-02-15 |
| AU1357376A (en) | 1977-11-10 |
| AR208785A1 (en) | 1977-02-28 |
| EG12017A (en) | 1978-06-30 |
| DE2625223A1 (en) | 1976-12-09 |
| FR2313450B3 (en) | 1979-02-23 |
| FR2313450A1 (en) | 1976-12-31 |
| JPS563881B2 (en) | 1981-01-27 |
| AU501229B2 (en) | 1979-06-14 |
| ZA762594B (en) | 1977-04-27 |
| GB1504088A (en) | 1978-03-15 |
| CA1063835A (en) | 1979-10-09 |
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