US3479438A - Apparatus and method for preheating of metal scrap for furnace charging - Google Patents

Apparatus and method for preheating of metal scrap for furnace charging Download PDF

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US3479438A
US3479438A US3479438DA US3479438A US 3479438 A US3479438 A US 3479438A US 3479438D A US3479438D A US 3479438DA US 3479438 A US3479438 A US 3479438A
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scrap
silo
metal
furnace
preheating
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Levi S Longenecker
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    • C—CHEMISTRY; METALLURGY
    • C21—METALLURGY OF IRON
    • C21C—PROCESSING OF PIG-IRON, e.g. REFINING, MANUFACTURE OF WROUGHT-IRON OR STEEL; TREATMENT IN MOLTEN STATE OF FERROUS ALLOYS
    • C21C5/00—Manufacture of carbon-steel, e.g. plain mild steel, medium carbon steel or cast steel or stainless steel
    • C21C5/56—Manufacture of steel by other methods
    • C21C5/562—Manufacture of steel by other methods starting from scrap
    • C21C5/565—Preheating of scrap
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F27—FURNACES; KILNS; OVENS; RETORTS
    • F27D—DETAILS OR ACCESSORIES OF FURNACES, KILNS, OVENS, OR RETORTS, IN SO FAR AS THEY ARE OF KINDS OCCURRING IN MORE THAN ONE KIND OF FURNACE
    • F27D17/00—Arrangements for using waste heat; Arrangements for using, or disposing of, waste gases
    • F27D17/001—Extraction of waste gases, collection of fumes and hoods used therefor
    • F27D17/003—Extraction of waste gases, collection of fumes and hoods used therefor of waste gases emanating from an electric arc furnace
    • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P10/00—Technologies related to metal processing
    • Y02P10/20—Recycling

Definitions

  • the invention deals with an improved method of land apparatus for handling and conditioning charge materials in connection with the refining and processing of molten metal.
  • An important phase of the invention deals with a system or apparatus for -an improved preheating of the metal scrap portion of a furnace charge.
  • While the invention may be employed in a variety of systems, it is particularly applicable to a ferrous metal or steel refining process employing a conventional type of furnace such as a tiltable arc-heated electrical furnace, and to the effective employment of a maximum quantity or percentage of relatively low cost ferrous scrap metal in the charge.
  • Another object has been to make effective utilization of scrap charges in a furnace
  • Another object has been to develop apparatus and procedure in accordance with which waste furnace gases are passed through and most effectively employed to preheat a scrap charge, and a hotter portion of the preheated scrap may be provided at a temperature and in an amount sufficient to fully meet the requirements of one operation of the furnace;
  • a further object has been to provide a preheating apparatus of improved efficiency 'and one which may bev fice employed to preheat a scrap charge in a progressive manner4- by passing hot gases upwardly therethrough;
  • a still further object has been to provide a preheating silohthat will enable hotter portions of a preheated charge therein to be removed therefrom ⁇ and the other portions to be retained therein for further preheating and, at the saine time, to provide for and permit the addition of cold scrap to take the place of the hotter removed portions;
  • FIGURE 1 is a top plan view showingta system which utilizes exhaust gases from an electric melting furnace for supplying hot exhaust gas to each of a pair of preheating silos; this view also shows an auxiliary hot gas supply means;
  • FIGURE 2 is 4a side section in elevation on the scal of and taken through melting furnace and gas collection apparatus shown in FIGURE 1;
  • FIGURE 3 is a side view in elevation on the scale of FIGURES l and 2, showing a scrap preheater or silo of the" invention in a horizontally-tilted, cold scrap-receiving and hot scrap delivering position.
  • a swingable, cupshaped, bottom door or lid on the lower end portion of the preheater or silo apparatus is in an open position to deliver preheated scrap to a chute of a conveyor, and a crane or hoist supported scrap bucket is in an overheadaligned position with a side-positioned charging mouth opening adjacent the upper end of the preheater that is provided with a swing charging door.
  • the charging door is in an open position for permitting the introduction of cold scrap into an upper end portion of the preheater;
  • FIGURES 3A and 3B are fragmented side views in elevation showing an alternate type of cold scrap metal feed and a combined gas outlet and Scrap introducing open portion of a preheating silo; these views are on the scale of FIGURE 3.
  • FIGURE 3C is a fragmental vertical section on the scale of FIGURE 3 illustrating a scrap capacity adjusting plate means for a swingable bottom door of a preheating silo;
  • FIGURE 4 is an end View in elevation on the scale of FIGURE 3 and of a portion of the apparatus shown in FIGURE 3, particularly illustrating hot scrap conveying me-ans and a furnace charging scrap bucket assembly positioned on a rotatable weighing machine.
  • FIGURE. 5 is a slightly enlarged side view in elevation of a scrap preheater or silo of the invention; means is shown for opening its swingable bottom door and for providing an oscillating action to facilitate the delivery of hot scrap therefrom;
  • FIGURE 6 is a view on the scale of and of the apparatus of FIGURE 5, taken at right angles thereto, and further illustrating mechanism for pivoting the scrap preheater or silo and for opening and closing the upper, sidemounted, swing charging door;
  • FIGURE 7 is a greatly enlarged fragmental horizontal section taken through the body portion of the preheater or silo apparatus of FIGURES 5 and 6 to illustrate details of its main body or wall construction;
  • FIGURE 8 is a top plan view on an enlarged scale that is intermediate between the scale of FIGURE 6 and of FIGURE 7; it particularly illustrates the construction of an upper end wall or closure portion of the preheat-er or silo of FIGURES 5 and 6;
  • FIGURE 9 is a bottom plan View of the preheater or silo of FIGURES 5 and 6 on the scale of FIGURE 8; it particularly illustrates the construction of a lower end wall of and the mounting of the swingable bottom door structure thereof;
  • F'IGURE 10 is a fragmental view in elevation on a slightly enlarged scale with respect to FIGURE 9; it is taken through a lower portion of a modified embodiment of the invention in which the preheater or silo is of hexagonal shape in section rather than circular or cylindrical;
  • FIGURE 11 is a bottom plan view on the scale of and looking up from the bottom of FIGURE 10.
  • the bottom swing door has been omitted for clarity of disclosure of an oscillating structure or frame;
  • FIGURE 12 is an enlarged fragmental vertical section taken on the structure of FIGURE 10 and showing details of the mounting of an oscillating frame shown in FIGURES 10 and 11;
  • FIGURE 13 is a horizontal section taken through the body of the modified construction of FIGURE 10, looking downwardly thereof, and on the scale of FIG- URES 8 and 9.
  • the procedure or apparatus arrangement herein set forth may -be employed in preheating various raw materials, but is primarily illustrated and applicable to the preheating of scrap metal before its introduction into a melting and refining furnace vessel. It thus deals with the charging of a furnace and making possible the maximum use of scrap metal with hot metal or pig iron in charging a furnace. IIf scrap metal, which is readily available and inexpensive is to be the sole source of the metal content of the furnace charge, electric furnace operation is indicated. If the charge is to be mad-e up of scrap metal and molten metal or pig iron, then an oxygen blow may be employed and electrodes used for supplementing the melting operation in the sense of finishing or holding the metal to complete its processing and pouring.
  • an electric furnace G is somewhat diagrammatically shown in FIGURES 1 and 2 that is provided with an electrode-carrying roof H.
  • Generated hot exhaust gases are collected by the roof H and passed through its discharge duct or snorkel 10 and through a gas inlet duct or snorkel 11 of and into the chamber of an exhaust gas collecting column or tower I.
  • the tower J is shown as refractory-lined, and its snorkel 11 may be connected in a sealed relation with the snorkel 10 through the agency of a sealing flange 10a carried by the latter.
  • the collecting column or tower J is also shown as having a removable cover 12 in its roof that may be used when the gases are to be tempered by the introduction of atmospheric gas before they are passed through a duct system into a preheater or silo B.
  • the hot gases collected in the chamber of the tower J may flow downwardly along a refractory down-How duct 13 into a checkerwork chamber portion 14 of a slagcollecting and gas distribution chamber unit K.
  • the hot gases ow over a slag collecting pocket 15 and into an outow ductwork 16 which may be underground, into a cross-extending, distribution manifold or duct 17.
  • the ductwork 16 delivers gases centrally to the manifold 17 and that the manifold 17 is provided with an inner, cross-extending pair of outlets 17a and 17b adjacent each of its ends.
  • the outlets are adapted to align with and deliver hot exhaust gases into preheaters or silos B through inlet port pairs 20a and 20h; see particularly FIGURE 1 of the drawings.
  • An oppositely-positioned, cross-extending auxiliary distribution manifold or duct 22 is shown located adjacent an opposite side of a pair of the preheaters or silos B for, if desired, supplementing the supply of hot gas provided by the manifold 17.
  • auxiliary combustion chamber or hot gas furnace source L that may be oil or gas-tired by burners 25 is shown connected centrally to the auxiliary manifold 22.
  • the manifold 22 also has a pair of side-positioned outlet portions 22a and 22b adjacent its opposite ends for 4 cooperating with the inlet port pairs 21a and 2lb of the preheaters B.
  • each preheater or silo B has a bottom swing door or cup-shaped lid 40 which, on its opposite sides, is provided with inlet port pairs 20a and 20b and 21a and 2lb to, as shown in FIGURES 1 and 6, align with the outlet port pairs 17a, 17b and 22a, 22h when the preheater or silo B is being operated in an upright position.
  • the bottom swing door 40 is closed to receive and pass hot gases upwardly through a column of scrap material within the silo during a scrap metal preheating operation.
  • the system or layout illustrated in FIGURE 1 enables the alternate supplying of preheating gas to each of a pair of silos B.
  • the manifold 17 is provided with a pair of slide gate valves 18 and 18' and the manifold 22 is provided with a pair of slide gate valves 23 and 23'.
  • slide valves 18 and 23 are closed and valves 18 and 23 are open, the full ilow of hot gas will -be into the left-hand positioned silo B of FIGURE 1. If the auxiliary source L is not being used, then both the slide valves 23 and 23' are preferably closed.
  • a cross-over or cross-connecting duct 19 is shown connected underground centrally between manifolds 17 and 22 and provided with a slide valve 24.
  • the duct 19 and the valve 24 give further ilexibility to operation of the system, in that both manifolds may be supplied with hot exhaust gas from either source or the gases from both sources may be mixed and supplied to both sides of a silo B.
  • FIGURES 1 and 2 illustrate a hot gas flow system and FIGURES 3 and 4 illustrate scrap ow which may be employed utilizing a preheater or silo B or B of the invention.
  • Cold scrap metal may, as shown in FIGURE 3, be delivered by a conventional scrap bucket or dump -box A into the upper or empty end portion of the silo B by aligning the bucket A by means of a conventional overhead hoist or crane (not shown) with a side-positioned, feed opening or mouth in the silo adjacent its upper, slightly converging end portion.
  • a charging door 95 is of a shape conforming to the side Wall shape of the silo B and is mounted for swinging or pivotal movement from an outer open position (shown in FIGURE 3) to a closed, scrap preheating position (shown in FIGURES 5 and 6).
  • a reversible electric motor M4 is secured on an outer metal plate wall 30 ⁇ of the silo B to drive a gear reduction unit which, in turn, actuates a drive shaft 99 through the agency of a coupling 101.
  • a set of three, spaced-apart, mounting hinge brackets 97 are shown in FIGURE 6 secured to the charging door 95 to project therefrom for secure mounting at their extending end portions on the shaft 99.
  • the shaft 99 is carried by and journaled in a group of three bosses 98 that are mounted to extend from the outer wall 30 of the silo B and that also serve as guide mounts for the extending portions of the hinge brackets 97.
  • FIGURE 3 illustrates that cold scrap is simultaneously fed into one end of the silo B while hot, preheated scrap is being delivered from an opposite end thereof, after the silo has been swung to a substantially horizontal position on its pair of centrally-located side extending trunnions or stud shafts 81.
  • a suicient amount of hot exhaust gas is flowed upwardly om an extension chamber defined by the bottom swing door 40 through interstices of the column of the scrap material when the silo B is in its vertical position of FIGURES 5 and 6, until lower hotter portions of the scrap material reach a maximum temperature of about 1700" F. (for ferrous metal scrap) above which they tend to become sticky or tacky.
  • the gases may be introduced into the bottom of the silo B at about 2000 to 2200 F.; they will drop-off in heat towards the top of the silo, normally to about 300 to 400 F. at a top exhaust duct 36.
  • they may be directly connected to dust removing yapparatus of an exhaust stack. In this manner the gases impart what would normally be waste heat to the scrap material before it is charged into a furnace, such ⁇ as G, and minimize the heat that has to be imparted to scrap in melting it down in the furnace.
  • the progressive upward movement of the gas tends to melt or volatilize lower melting point metals, such as non-ferrous metals in the nature of lead, zinc and copper contaminants carried by the scrap, to either carry them off through the stack or deposit them in a dust collector, if they are volatilized, or collect them in the bottom of the door 40 from which they may be bled-off or otherwise removed.
  • the scrap material also tends to collect valuable metal oxides, etc. from the hot furnace gas that is moving through its interstices.
  • preheater silo or container B is of the same general construction as the silo B of FIGURES 3, 5 and 6, but cold scrap metal is shown fed over magnetic separator apparatus A (see FIGURE 3B) to discard non-magnetic materials and lfeed ferrous metal material along a semi-circular inclined scraper chute 28 that is positioned about and immediately adjacent and is carried by a combined cool gas outlet duct and scrap lcharging open portion or port 29 of preheater silo or container B.
  • the separator A may include a continuous belt conveyor 26 and a rotating flanged wheel 27 having an offset magnetic surface 11a.
  • the duct 29 is shown used as an outlet for cooled exhaust gases when the silo B is in its upright scrap preheating position. In this position, the duct is connected to a stack or waste duct 29a.
  • the hotter scrap portions may be delivered from the lower end of the silo B into an inclined chute (shown in FIGURE 3) that is carried 4by a portable wheeled conveyor C.
  • the conveyor C as also illustrated in FIGURE 4, has a motor driven belt that, as indicated by the arrows, carries the scrap material upwardly on an inclined plane and into a hot scrap receiving bucket assembly D.
  • the assembly D may be a conventional charging bucket or a multi-compartment type, such as illustrated in my copending application, Ser. No. 660,095 of Aug. 11, 1967, when hot met-a1 is to be used with the scrap charge.
  • the assembly D is shown supported on a base E having a weighing scale that indicates when a sufficient quantity has been delivered for a particular charging operation.
  • FIGURES 5 to 9 illustrate the general shape and construction of circular or cylindrical silo B.
  • the silo B has a continuous, plate-like sheet metal outer wall 30 that is mounted in a spaced relation with respect to a similar plate-like metal inner wall 33 by means of yI-bearn spacers 31 and a pair of spacer bars 32.
  • the pair of -bars 32 is shown secured between the base portion of an inner flange of each I-beam 31 and the inner wall 33.
  • the inner metal wall 33 is shown protected by a heat-resistant plate-like metal wall 34 that may be removably-secured thereto, as by bolt and nut assemblies 35.
  • This constructon enables the use of insulation between the inner and outer walls 33 and 30 in such a manner as to protect the insulation from the scrap material and, at v the same time, provide an inner heating chamber which is relatively smooth for better movement of the scrap material into, along and out of the elongated chamber of the silo B.
  • the trunnion or stud shafts 81 extend from a pair of reinforced, oppositely-positioned mounts on the outer wall 30 of the silo B at a location that corresponds substantially to its center of gravity or balance when the bottom swing door 40 is in its closed position.
  • the trunnions or shafts 81 are pivotally-positioned within bearing mounts 82 that are carried lby a pair of structural cross members 83 of a stationary support frame 84. Swinging movement is imparted to the silo B by a reversible electric motor M3 that, with a gear reduction unit 90, is mounted on a concrete pier 91 to extend inwardly therefrom.
  • the pier 91 at its upper end serves as a limit support for the silo B when in its horizontal coldscrap charge-receiving and hot-charge-delivering position of FIGURE 3.
  • the motor M3 and gear reduction unit 90 drive a winding drum 88 through the agency of an actuating shaft 89 on which it is mounted and which extends from the reduction gear unit 90.
  • a cable or chain 87 is anchored on the drum 88 and at one end is secured by an eyelet 85 to the outer wall 30 adjacent an upper portion of the silo B and at its other end is secured by an eyelet 86 on the outer wall 30 adjacent a lower end of the silo.
  • a reversible electric motor M1 is secured on a stand or platform 46 that extends from a side of the outer wall 30 to drive a gear reduction unit 47 that is also positioned on the same mount, see particularly FIGURES 5 and 6.
  • the output shaft of the gear reduction unit 47 has a sprocket wheel thereon which actuates a gear and sprocket drive 48 and a cross-extending drive shaft 49.
  • the shaft 49 is journaled in a pair of spaced-apart mounting stands 50 and, at each of its opposite ends, has a chain and sprocket gear reduction drive 52 for actuating a ily or cam wheel 55.
  • Each cam wheel 55 is rotatablyjournaled on a stud shaft 53 extending from the wall 30, and has an eccentrically-positioned drive pin 56 thereon adapted to actuate a swing leg 57 that at its upper end is pivotally mounted on the pin 56.
  • an eccentrically-positioned drive pin 56 thereon adapted to actuate a swing leg 57 that at its upper end is pivotally mounted on the pin 56.
  • the swingable Ibottom door 40 which has been termed a cup-shaped door structure to generally indicate its hollow, extension-chamber-deiining structure, has a pair of outwardly-projecting hinge brackets 41 secured thereto and pivotally-mounted on a support shaft 44.
  • the shaft 44 as shown particularly in FIGURE 6, is mounted at its opposite ends by a pair of spaced-apart brackets 43 on the outer wall 30 of the silo B.
  • the shaft 44 serves as a pivot support for swing door 40 in its movement between opened and closed positions, as effected by actuation of the motor M1.
  • FIGURE 3C illustrates means for adjusting the effective scrap carrying capacity of the delivering door structure 40, in order that the scrap content of the silo B, B or B" may be proportioned to the actual requirements of a particular furnace.
  • a bottom plate member 40a is positioned in the closed end of the door and is provided with hollow mounts 40a for a group of spacedapart adjustment screws or bolts 45.
  • Each screw 45 has an enlarged circular head 45a that is rotatably-positioned in an associated mount 4Gb and has a threaded stem that is adjustably-carried within a threaded bushing 45C.
  • Each bushing 45C is secured to extend across the wall section of the door 40.
  • oscillating or agitating mechanism which facilitates the delivery of hot scrap from the silo. In a sense, it permits the scrap to be heated where desired to a slightly higher temperature at which it may become somewhat sticky and, at the same time, eliminates difficulties in delivering or discharging it away from an end portion of the preheater.
  • the oscillator apparatus is driven by an electric motor M2 and a gear reduction unit 61 that are mounted on a stand 60 that projects from the outer wall 30 of the preheater vessel B (or B), see particularly FIGURES and 6.
  • the output shaft of the gear reduction unit 61 drives a sprocket and chain drive 62 and a cross-extending drive shaft 63 that is journaled within a pair of mounts 63a.
  • a small cam or fly wheel 64 is mounted on each end of the drive shaft 63 and has an eccentrically-mounted pin extending there- 'from on which one end of a swing arm 65 is pivotallysecured.
  • Each swing arm 65 is pivotally-connected at its other end to a centrally-pivotally-mounted reciprocating arm 66.
  • the arm 66 is centrally-pivotally-mounted by a mounting pin 68 projecting from the outer wall 30 and is pivotally-connected at its lower end to a reciprocating finger that is, at its other end, pivotally-secured on or to an oscillator member or U-shaped agitator frame or plate, such as 70 shown in FIGURE 11.
  • an oscillator member or U-shaped agitator frame or plate such as 70 shown in FIGURE 11.
  • Agitator or oscillator frame 70 is slidably-mounted over the open bottom portion of the preheater silo such as B and, in this connection, is provided with a series of elongated and spaced-apart slots or slotted portions 70a that extend therethrough and that receive pin 76 therein.
  • the pins 76 are secured to and project upwardly from an upper face of an annular bottom support plate or spacer part 7.5 that is suspended and secured by the pins 76 as a flange in a spaced relation from a bottom end closure wall 39 (See FIGURE 12) of the wall structure of the silo.
  • Actuation of the motor M2 thus imparts a back and forth movement of the oscillator frame or plate 70 moving the slots 70a back and forth endwise along the pins 76 in such a manner as to not only provide a back and forth oscillating action of the frame 70, but also an oscillation or agitation of the lower end portions of the silo such as to shake and clean-off any lodged or sticking scrap material from the pouring edge and end closure wall 39.
  • This is important to enable the door structure 40 to be tightly closed on the lower open end portion of the silo or container.
  • each pin 76 at its upper end is secured in an end closure metal face plate 39 and, in turn, is secured to and supports the spacer frame or plate 75 in a suspended relation therefrom in such a manner as to define a slide spacing between the members 39 and 75 for the oscillator frame 70.
  • Each pin 76 (see FIGURE 12) has a central, enlarged or sleeve portion 76 that extends between the members 39 and 75.
  • the charging upper swing door (correspondng to will be planar and positioned over a mouth opening in one panel portion of the silo B".
  • the wall construction of the silo B is provided with an insulating lining 106 between inner and outer metal plated walls and has a slightly different form of connecting structure -for such walls.
  • I-beams 107 extend along the outside panels or wall portions between corner pieces; the I-beams 107 are spaced-apart longitudinally or vertically of and are secured to the outer wall of the silo B".
  • hot gases issuing from the furnace G are passed through the collecting column or tower l in order that they may be tempered as desired and are then passed through a distribution chamber K such that slag may be removed before the gases are flowed into a distribution ductwork 16 and then into one of a pair of adjacently positioned preheating silos such as B, B or B.
  • Each of the silos is substantially lled with scrap metal such as scrap steel, e.g., in the silo B or B" to a level up to the opening for the scrap charging door 95 and, when in a vertical position, its inlet ports 20a and 20b are in gas-receiving alignment with outlet portions or ports 17a and 17b of a cross-extending gas manifold 17.
  • auxiliary chamber or furnace unit L If, for some reason, the quantity or the temperature of the exhaust gas is insufficient or substantially nil as supplied from a furnace such as G or a group of furnaces (not shown), then supplementation may be accomplished through the agency of auxiliary chamber or furnace unit L. If the auxiliary unit L is not being used, then it is preferred to close both of the slide valves 23 and 23'. Although it is possible to preheat a pair of scrap silos B, I prefer to operate on an alternate ybasis whereby one silo is being subjected to a preheating operation while the other is delivering hot scrap and receiving a new charge of cold scrap. In this Way, gases from a furnace can be continuously and highly efficiently withdrawn.
  • cross-extending or cross-over duct 19 as connected between manifolds 17 and 22 and as provided with slide valve 18, enables supplying hot exhaust gas from either or both the furnaces G and L to both sides of the bottom end portion of each silo B.
  • hot exhaust gas may be supplied entirely from either furnace G or L, or may be supplied as a mixture from both furnaces.
  • an upper half ofthe scrap column contained in the preheater In employing a preheater or silo B, B', B, an upper half ofthe scrap column contained in the preheater. Coldl scrap will be fed or charged into the upper end portion of the kpreheater in an amount substantially equal to the amount of hot scrap that is removed from the bottom end thereof, assuming that the Same size of hot scrap charge is to be used on the next operation.
  • the swing door 95 of either the silo B or B" in its open position serves as a guide chute against which the cold scrap metal may be directed and thereby guided during its introduction into the preheater silo. It is contemplated that the lower preheated one-half portion of the scrap column will be used as the furnace charge, and that the remaining half portion will have an intermediate temperature.
  • the upper one-third portion is empty, and the lower one-third contains the hotter scrap to be delivered to the charging bucket assembly D.
  • the intermediate one-third contains partially heated scrap that ibecomes the bottom layer when the hotter scrap is discharged from and cold scrap is introduced into the chamber as an upper layer.
  • the preheater silo When the upward flow of hot gases is accomplished through the preheater silo, then the lower portion will be heated up to the furnace charging temperature and thereafter delivered to means such as the conveyor C for charging a furnace. If, for example, the preheater charge i's 150y tons, then the lower portion removed will be 75 tons when operating on a half and half scrap basis, occupying two-thirds of the elongated silo chamber.
  • the silo in its vertical preheating position contains a scrap column that will occupy about two-thirds of the height ofthe chamber. Since the melting furnace exhaust gases are made available to the preheating operation before they are passed through a dust collector, they may be passed directly to the dust collector without further cooling. They normally have a temperature of about 300 to 400 F. at the top vent or outlet duct 36.
  • the furnace L may be used where necessary to make up any deficiency incident to the utilization of the furnace exhaust gases.
  • the fume utilization and collecting equipment can function continuously and without interruption and maximum utilization will be made of the full heat of the exhaust gases.
  • the agitator or oscillator means is particularly useful at the end of the pouring of hot scrap and is eifective in dislodging and scraping off any scrap lodged on the pouring edge. This enables cleaning the face of the bottom edge of the silo so that the bottom swing door 40 can be closed with a gas-tight seal.
  • silo B, B or B In operating a silo B, B or B", it is charged with cold scrap through its top end portion after it has been swung to a substantially horizontal position. At the same time, the bottom swing door 40 is opened and the preheated, hottest portion of the charge is removed from its bottom or opposite end portion and from the extension compartment of the swing door structure. It is desirable to leave an empty space extending from the top end of the silo that substantially represents the amount of cold scrap to be introduced and the amount of hot bottom scrap that is to be removed.
  • a scrap metal preheated comprising; a longitudinally-extending container defining an elongated scrap metal receiving chamber therein, a gas outlet port in an upper end portion of said container, said container having an open bottom end portion, a cup-shaped door structure swingably-mounted on said open bottom portion for opening and closing it off, said door in its closed position defining a continuation of the elongated chamber of said container, inlet port means at a lower end portion of said container for introducing hot gases into the elongated chamber and upwardly through scrap metal positioned therein for preheating the scrap metal, and a frame structure swingably-mounting said container for movement between a substantially vertical scrap preheating position and a substantially horizontal hot scrap delivering position.
  • inlet port means being carried by and being open through said door structure to the elongated chamber of said container.
  • said inlet port means of said door structure comprising, at least a pair of side inlet ports for introducing hot furnace gases through said door structure into and along the elongated chamber towards said gas outlet port of said container.
  • said inlet port means also comprising, a second pair of side inlet ports on an opposite side of said door structure.
  • said means operatively-connected to said cup-shaped door structure comprising, fly wheel mechanism operatively-connected to said door structure, and motor actuating means operatively-connected to said iiy wheel mechanism for swinging said door structure between its closing and opening positions.
  • said last-mentioned means comprising, an open mouth portion in the upper end portion of said container, and a swing charging door for opening and closing ofi said open mouth portion.
  • actuating means operatively-positioned on said container and connected to said charging door for moving it to an open position when said container is in its substantially horizontal hot scrap delivering position and for maintaining it in a closed position when said container is in its substantially vertical scrap preheating position.
  • actuating means carried by said frame structure and operatively-connected to said container for swinging itv between its substantially vertical and substantially horizontal positions.
  • said actuating means comprising, a rotatable drum operatively-carried by said frame structure, and a cable secured on said drum and connected at its opposite ends to opposite end portions of said container.
  • said open bottom portion of said container having a closing end face, and means operatively-carried by said container for agitating scrap metal adjacent said open bottom portion to facilitate the delivery of hot scrap material therefrom and to clean-off said closing end face.
  • said last-mentioned means comprising, an actuating motor, a rocker arm and an oscillator plate, and said oscillator plate being operatively-mounted in a suspended relation with respect to Said closing end face.
  • a support plate positioned below said oscillator plate, a spaced group of elongated slot portions in said oscillator plate, and a spaced group of pins each extending through one of said slot portions and being secured at its opposite ends between said closing end face and said support plate, whereby said oscillator plate may be freely moved on said pins towards opposite ends of said slot portions.
  • said container having a continuous wall configuration thereabout provided wit-h a relatively smooth metal plate-like inner wall along said elongated chamber for receiving and positioning the scrap metal therein, a metal plate-like outer wall, an insulating wall portion positioned between said inner and outer walls, and peripherally spaced-apart cross-extending connecting members between said inner and outer walls.
  • said container having a hexagonally-shaped -wall construction, said wall construction having spaced-apart inner and outer metal plate member walls, insulating material between said inner and outer walls, and cornerpositioned cross-extending connecting members between said inner and outer walls.
  • a scrap metal preheater which comprises, a longitudinally-extending container defining a scrap metal receiving chamber therewithin, a gas outlet port through said container adjacent an upper end thereof, said container having an open bottom portion, a cup-shaped door pivotally-mounted on said open bottom portion of said container for opening and closing it olf, said door defining a scrap metal receiving chamber forming a continuation of the chamber of said container when said door is in its closing-off position and having side ports for introducing hot gases into the chamber continuation and upwardly through scrap metal positioned therein for preheating the scrap metal, a frame structure centrally-pivoting said container for swinging movement between a vertical scrap metal preheating position and a substantially horizontal position, actuating means for moving said container between said positions, actuating means operatively-connected to said door for swinging said door from its closing position to an open scrap metal discharging position when said container is swung from its vertical to its substantially horizontal position, and a scrap metal introducing chute carried by said container and cooperating with said gas outlet port
  • a pair lof scrap preheating silos in an adjacent longitudinally spacedapart relation with respect to each other, each of said silos having an elongated scrap-receiving chamber and hot gas inlet means at its lower end portion and a cooled gas outlet and cold scrap charging opening at its upper end portion, a gas manifold connected at its opposite ends to said inlet means of each of said silos, the melting and refining furnace having a hot combustion gas outlet duct, ductwork connecting said gas outlet duct of the furnace substantially centrally to said manifold, and Valve means in said manifold for closing-olf flow of hot combustion gas from said manifold into one of said silos and for opening hot combustion gas flow to the other of said silos and vice Versa.
  • each of said silos having a second side-positioned gas inlet means in an oppositely-positoned relation with respect to said firstmentioned inlet means, an auxiliary manifold connected at its opposite ends to said second gas inlet means of said silos, a hot gas supplying combustion chamber connected substantially centrally to said auxiliary manifold, and valve means operatively-positioned in said manifold for opening and closing off gas fiow from said combustion chamber to each of said silos.
  • a cross-over duct connected between said gas and auxiliary manifolds, and valve means in said cross-over duct for opening and closing off gas fiow therethrough.
  • a method of utilizing hot gases in preheating scrap metal that is to be charged into a melting and refining furnace the steps of continuously providing hot exhaust gases and introducing them into a lower end portion of a preheating silo, flowing the hot exhaust gases upwardly through scrap metal in the silo and preheating it, after at least a lower portion of the scrap metal has been preheated to a hot furnace charging temperature, discharging such hot lower portion from the preheating silo for introduction into a melting and refining furnace; while discharging such hot lower portion from the first-mentioned preheating silo, shutting off the fiow of hot exhaust gases thereto and introducing them into a lower end portion of a second preheating silo; flowing the hot exhaust gases upwardly through scrap metal in the second-mentioned silo and preheating it, after at least a lower portion of the scrap metal has been preheated to a hot furnace charging temperature, discharging such hot lower portion from the second-mentioned silo

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Description

Nov. 18, 1969 f L. s. LoNGENEcKl-:R 3,479,438
APPARATUS AND METHOD FOR PREHEATING OF METAL SCRAP FOR FURNACE CHARGING Filed Nov. 25, 1968 '7 Sheets-Sheet l ammi; 112m l 23 INVENTOR. Levi S. Longenecker zmkwazfm Hfs ATTORNEYS NOV- 18, 1969 1 s. LONGENECKER 3,479,438
APPARATUS AND METHOD FOR PREHEATING OF' METAL SCRAP FOR FURNACE CHARGING Filed NOV. 25, 1968 7 Shee'CS-Sheell 2 INVENTOR. Levi S. Longenecker HIS` ATTORNEYS Nov. 18. 1969 L. s. LONGENECKER 3,479,438
APPARATUS AND METHOD FOR PREHEATING OF' METAL SCRAP FOR FURNACE CHARGING 7 Sheets-Sheet .'5
Filed Nov. 25, 1968 INVENTOR. Levi S. Longenecker BY w, M#
HIS ATTORNEYS Nov. 18. 1969 L. s. LoNGl-:NECKER 3,479,438
APPARATUS AND METHOD FOR PREHEATING OF METAL SCRAP FOR FURNACE CHARGING 7 Sheets-Sheet 4.
Filed Nov. 25, 1968 INVENTOR.
Levi S. Longenecker BY l HIS ATTONE YS N0v 18, 1969 L. s. LONGENECKER 3,479,438
APPARATUS AND METHOD FOR PREHEATING OF METAL SCRAP FOR FURNACE CHARGING 7 Sheets-Sheet Filed Nov. 25, 1968 fahr:
H/s ATTORNEYS Nov. 18, 1969 L. s. LONGENECKER l 3,479,438
APPARATUS AND METHOD FOR PREHEATING OF METAL SCRAP F'iled Nov. 25, 1968 FOR FURNACE CHARG'ING 7 Sheets-Sheet 6 INVENTOR; Lew S. Longenecker um (im,
HIS ATTORNEYS Nov. 18, 1969 l.. s. LONGENECKER 3,479,433
APPARATUS AND METHOD FOR PREHEATNG OF METAL SCRAP FOR FURNACE CHARGING 7 Sheets-Sheet Filed NOV. 25, 1968 F ig. /3
40h 45h Levi S. Lo
INVENTOR Ilm 45 45C l|||| ngenecker /pwadf HIS ATTORNEYS vBY United States Patent 3,479,438 APPARATUS AND METHOD FOR PREHEATING F METAL SCRAP FOR FURNACE CHARGING Levi S. Longeneckei, 61 Mayfair Drive, Pittsburgh, Pa. 15228 Continuation-impart of application Ser. No. 660,095, Aug. 11, 1967. This application Nov. 25, 1968, Ser.
Int. Cl. H05b 7/18 U.S. Cl. 13-9 25 Claims ABSTRACT OF THE DISCLOSURE This application is a continuation-in-part of my copending application Ser. No. 660,095 of Aug. 1l, 1967, now Patent No. 3,444,304, entitled Making Basie Oxygen Steel in an Electric Arc Furnace System.
The invention deals with an improved method of land apparatus for handling and conditioning charge materials in connection with the refining and processing of molten metal. An important phase of the invention deals with a system or apparatus for -an improved preheating of the metal scrap portion of a furnace charge.
While the invention may be employed in a variety of systems, it is particularly applicable to a ferrous metal or steel refining process employing a conventional type of furnace such as a tiltable arc-heated electrical furnace, and to the effective employment of a maximum quantity or percentage of relatively low cost ferrous scrap metal in the charge.
It is recognized by those skilled in this art that while electric arc furnaces are practical for refining of relatively special steels such as lalloys, the production cost per ton of refined basic metals is significantly greater than that incurred, for example, with a BOF o'r oxygen blow system. The large amount of electricity used in the electric arc process and particularly in melting a scrap charge and the time necessarily utilized in charging the furnace has contributed to this relatively high operating cost. Although the invention has features applicable generally to furnaces, for the purpose of illustration, I have illustrated it in connection with an electrical furnace utilization.
It has been an object of the invention to develop an improved procedure and apparatus arrangement that will make practical or economical the utilization of van electric arc furnace for melting and refining of low grade ferrous metals and alloys;
Another object has been to make effective utilization of scrap charges in a furnace;
Another object has been to develop apparatus and procedure in accordance with which waste furnace gases are passed through and most effectively employed to preheat a scrap charge, and a hotter portion of the preheated scrap may be provided at a temperature and in an amount sufficient to fully meet the requirements of one operation of the furnace;
A further object has been to provide a preheating apparatus of improved efficiency 'and one which may bev fice employed to preheat a scrap charge in a progressive manner4- by passing hot gases upwardly therethrough;
f A still further object has been to provide a preheating silohthat will enable hotter portions of a preheated charge therein to be removed therefrom `and the other portions to be retained therein for further preheating and, at the saine time, to provide for and permit the addition of cold scrap to take the place of the hotter removed portions;
These and other objects will appear to those skilled in the art from the illustrative embodiments and the descriptioi which follows:
`In the drawings, FIGURE 1 is a top plan view showingta system which utilizes exhaust gases from an electric melting furnace for supplying hot exhaust gas to each of a pair of preheating silos; this view also shows an auxiliary hot gas supply means;
-FIGURE 2 is 4a side section in elevation on the scal of and taken through melting furnace and gas collection apparatus shown in FIGURE 1;
FIGURE 3 is a side view in elevation on the scale of FIGURES l and 2, showing a scrap preheater or silo of the" invention in a horizontally-tilted, cold scrap-receiving and hot scrap delivering position. A swingable, cupshaped, bottom door or lid on the lower end portion of the preheater or silo apparatus is in an open position to deliver preheated scrap to a chute of a conveyor, and a crane or hoist supported scrap bucket is in an overheadaligned position with a side-positioned charging mouth opening adjacent the upper end of the preheater that is provided with a swing charging door. At this time, the charging door is in an open position for permitting the introduction of cold scrap into an upper end portion of the preheater;
FIGURES 3A and 3B are fragmented side views in elevation showing an alternate type of cold scrap metal feed and a combined gas outlet and Scrap introducing open portion of a preheating silo; these views are on the scale of FIGURE 3.
FIGURE 3C is a fragmental vertical section on the scale of FIGURE 3 illustrating a scrap capacity adjusting plate means for a swingable bottom door of a preheating silo;
FIGURE 4 is an end View in elevation on the scale of FIGURE 3 and of a portion of the apparatus shown in FIGURE 3, particularly illustrating hot scrap conveying me-ans and a furnace charging scrap bucket assembly positioned on a rotatable weighing machine.
FIGURE. 5 is a slightly enlarged side view in elevation of a scrap preheater or silo of the invention; means is shown for opening its swingable bottom door and for providing an oscillating action to facilitate the delivery of hot scrap therefrom;
FIGURE 6 is a view on the scale of and of the apparatus of FIGURE 5, taken at right angles thereto, and further illustrating mechanism for pivoting the scrap preheater or silo and for opening and closing the upper, sidemounted, swing charging door;
FIGURE 7 is a greatly enlarged fragmental horizontal section taken through the body portion of the preheater or silo apparatus of FIGURES 5 and 6 to illustrate details of its main body or wall construction;
FIGURE 8 is a top plan view on an enlarged scale that is intermediate between the scale of FIGURE 6 and of FIGURE 7; it particularly illustrates the construction of an upper end wall or closure portion of the preheat-er or silo of FIGURES 5 and 6;
FIGURE 9 is a bottom plan View of the preheater or silo of FIGURES 5 and 6 on the scale of FIGURE 8; it particularly illustrates the construction of a lower end wall of and the mounting of the swingable bottom door structure thereof;
F'IGURE 10 is a fragmental view in elevation on a slightly enlarged scale with respect to FIGURE 9; it is taken through a lower portion of a modified embodiment of the invention in which the preheater or silo is of hexagonal shape in section rather than circular or cylindrical;
FIGURE 11 is a bottom plan view on the scale of and looking up from the bottom of FIGURE 10. In these figures, the bottom swing door has been omitted for clarity of disclosure of an oscillating structure or frame;
FIGURE 12 is an enlarged fragmental vertical section taken on the structure of FIGURE 10 and showing details of the mounting of an oscillating frame shown in FIGURES 10 and 11;
And, FIGURE 13 is a horizontal section taken through the body of the modified construction of FIGURE 10, looking downwardly thereof, and on the scale of FIG- URES 8 and 9.
The procedure or apparatus arrangement herein set forth may -be employed in preheating various raw materials, but is primarily illustrated and applicable to the preheating of scrap metal before its introduction into a melting and refining furnace vessel. It thus deals with the charging of a furnace and making possible the maximum use of scrap metal with hot metal or pig iron in charging a furnace. IIf scrap metal, which is readily available and inexpensive is to be the sole source of the metal content of the furnace charge, electric furnace operation is indicated. If the charge is to be mad-e up of scrap metal and molten metal or pig iron, then an oxygen blow may be employed and electrodes used for supplementing the melting operation in the sense of finishing or holding the metal to complete its processing and pouring.
For simplicity of illustration, an electric furnace G is somewhat diagrammatically shown in FIGURES 1 and 2 that is provided with an electrode-carrying roof H. Generated hot exhaust gases are collected by the roof H and passed through its discharge duct or snorkel 10 and through a gas inlet duct or snorkel 11 of and into the chamber of an exhaust gas collecting column or tower I. The tower J is shown as refractory-lined, and its snorkel 11 may be connected in a sealed relation with the snorkel 10 through the agency of a sealing flange 10a carried by the latter. The collecting column or tower J is also shown as having a removable cover 12 in its roof that may be used when the gases are to be tempered by the introduction of atmospheric gas before they are passed through a duct system into a preheater or silo B.
The hot gases collected in the chamber of the tower J may flow downwardly along a refractory down-How duct 13 into a checkerwork chamber portion 14 of a slagcollecting and gas distribution chamber unit K. The hot gases ow over a slag collecting pocket 15 and into an outow ductwork 16 which may be underground, into a cross-extending, distribution manifold or duct 17. It will be noted that the ductwork 16 delivers gases centrally to the manifold 17 and that the manifold 17 is provided with an inner, cross-extending pair of outlets 17a and 17b adjacent each of its ends. The outlets are adapted to align with and deliver hot exhaust gases into preheaters or silos B through inlet port pairs 20a and 20h; see particularly FIGURE 1 of the drawings. An oppositely-positioned, cross-extending auxiliary distribution manifold or duct 22 is shown located adjacent an opposite side of a pair of the preheaters or silos B for, if desired, supplementing the supply of hot gas provided by the manifold 17.
An auxiliary combustion chamber or hot gas furnace source L that may be oil or gas-tired by burners 25 is shown connected centrally to the auxiliary manifold 22. The manifold 22 also has a pair of side-positioned outlet portions 22a and 22b adjacent its opposite ends for 4 cooperating with the inlet port pairs 21a and 2lb of the preheaters B. As particularly shown in FIGURES 3, 5, 6 and 9, each preheater or silo B has a bottom swing door or cup-shaped lid 40 which, on its opposite sides, is provided with inlet port pairs 20a and 20b and 21a and 2lb to, as shown in FIGURES 1 and 6, align with the outlet port pairs 17a, 17b and 22a, 22h when the preheater or silo B is being operated in an upright position. At this time, the bottom swing door 40 is closed to receive and pass hot gases upwardly through a column of scrap material within the silo during a scrap metal preheating operation. The system or layout illustrated in FIGURE 1 enables the alternate supplying of preheating gas to each of a pair of silos B. In this connection, the manifold 17 is provided with a pair of slide gate valves 18 and 18' and the manifold 22 is provided with a pair of slide gate valves 23 and 23'. For example, when slide valves 18 and 23 are closed and valves 18 and 23 are open, the full ilow of hot gas will -be into the left-hand positioned silo B of FIGURE 1. If the auxiliary source L is not being used, then both the slide valves 23 and 23' are preferably closed.
A cross-over or cross-connecting duct 19 is shown connected underground centrally between manifolds 17 and 22 and provided with a slide valve 24. The duct 19 and the valve 24 give further ilexibility to operation of the system, in that both manifolds may be supplied with hot exhaust gas from either source or the gases from both sources may be mixed and supplied to both sides of a silo B.
FIGURES 1 and 2 illustrate a hot gas flow system and FIGURES 3 and 4 illustrate scrap ow which may be employed utilizing a preheater or silo B or B of the invention. Cold scrap metal may, as shown in FIGURE 3, be delivered by a conventional scrap bucket or dump -box A into the upper or empty end portion of the silo B by aligning the bucket A by means of a conventional overhead hoist or crane (not shown) with a side-positioned, feed opening or mouth in the silo adjacent its upper, slightly converging end portion. A charging door 95, see also FIGURES 5 and 6, is of a shape conforming to the side Wall shape of the silo B and is mounted for swinging or pivotal movement from an outer open position (shown in FIGURE 3) to a closed, scrap preheating position (shown in FIGURES 5 and 6). For this purpose, a reversible electric motor M4 is secured on an outer metal plate wall 30` of the silo B to drive a gear reduction unit which, in turn, actuates a drive shaft 99 through the agency of a coupling 101. A set of three, spaced-apart, mounting hinge brackets 97 are shown in FIGURE 6 secured to the charging door 95 to project therefrom for secure mounting at their extending end portions on the shaft 99. The shaft 99 is carried by and journaled in a group of three bosses 98 that are mounted to extend from the outer wall 30 of the silo B and that also serve as guide mounts for the extending portions of the hinge brackets 97. When the motor M4 is actuated for rotation in a clockwise direction (referring to FIGURE 6), the charging door 95 will be swung to the open position of FIGURE 3, and when the motor M4 is actuated in a counterclockwise direction the door will be swung to the closed position of FIGURE 6.
FIGURE 3 illustrates that cold scrap is simultaneously fed into one end of the silo B while hot, preheated scrap is being delivered from an opposite end thereof, after the silo has been swung to a substantially horizontal position on its pair of centrally-located side extending trunnions or stud shafts 81. A suicient amount of hot exhaust gas is flowed upwardly om an extension chamber defined by the bottom swing door 40 through interstices of the column of the scrap material when the silo B is in its vertical position of FIGURES 5 and 6, until lower hotter portions of the scrap material reach a maximum temperature of about 1700" F. (for ferrous metal scrap) above which they tend to become sticky or tacky. The gases may be introduced into the bottom of the silo B at about 2000 to 2200 F.; they will drop-off in heat towards the top of the silo, normally to about 300 to 400 F. at a top exhaust duct 36. By reason of the relatively low temperature of the issuing gases, they may be directly connected to dust removing yapparatus of an exhaust stack. In this manner the gases impart what would normally be waste heat to the scrap material before it is charged into a furnace, such `as G, and minimize the heat that has to be imparted to scrap in melting it down in the furnace. The progressive upward movement of the gas tends to melt or volatilize lower melting point metals, such as non-ferrous metals in the nature of lead, zinc and copper contaminants carried by the scrap, to either carry them off through the stack or deposit them in a dust collector, if they are volatilized, or collect them in the bottom of the door 40 from which they may be bled-off or otherwise removed. The scrap material also tends to collect valuable metal oxides, etc. from the hot furnace gas that is moving through its interstices.
In FIGURES 3A and 3B, preheater silo or container B is of the same general construction as the silo B of FIGURES 3, 5 and 6, but cold scrap metal is shown fed over magnetic separator apparatus A (see FIGURE 3B) to discard non-magnetic materials and lfeed ferrous metal material along a semi-circular inclined scraper chute 28 that is positioned about and immediately adjacent and is carried by a combined cool gas outlet duct and scrap lcharging open portion or port 29 of preheater silo or container B. The separator A may include a continuous belt conveyor 26 and a rotating flanged wheel 27 having an offset magnetic surface 11a. In FIGURE 3A, the duct 29 is shown used as an outlet for cooled exhaust gases when the silo B is in its upright scrap preheating position. In this position, the duct is connected to a stack or waste duct 29a.
With the bottom door structure 40 in the open position of FIGURE 3, the hotter scrap portions, usually about the one-half of the total scrap column that is represented by about a two-thirds lower portion of the total extent of the chamber provided by the silo and its door structure 40, may be delivered from the lower end of the silo B into an inclined chute (shown in FIGURE 3) that is carried 4by a portable wheeled conveyor C. The conveyor C, as also illustrated in FIGURE 4, has a motor driven belt that, as indicated by the arrows, carries the scrap material upwardly on an inclined plane and into a hot scrap receiving bucket assembly D. The assembly D may be a conventional charging bucket or a multi-compartment type, such as illustrated in my copending application, Ser. No. 660,095 of Aug. 11, 1967, when hot met-a1 is to be used with the scrap charge. The assembly D is shown supported on a base E having a weighing scale that indicates when a sufficient quantity has been delivered for a particular charging operation.
FIGURES 5 to 9 illustrate the general shape and construction of circular or cylindrical silo B. With reference to FIGURE 7, the silo B has a continuous, plate-like sheet metal outer wall 30 that is mounted in a spaced relation with respect to a similar plate-like metal inner wall 33 by means of yI-bearn spacers 31 and a pair of spacer bars 32. The pair of -bars 32 is shown secured between the base portion of an inner flange of each I-beam 31 and the inner wall 33. The inner metal wall 33 is shown protected by a heat-resistant plate-like metal wall 34 that may be removably-secured thereto, as by bolt and nut assemblies 35. This constructon enables the use of insulation between the inner and outer walls 33 and 30 in such a manner as to protect the insulation from the scrap material and, at v the same time, provide an inner heating chamber which is relatively smooth for better movement of the scrap material into, along and out of the elongated chamber of the silo B.
6 Upper and lower ends of the silo construction, as particularly illustrated in FIGURES 8 and 9, are reinforced by cross-extending beam members 37 and 38. It will be Anoted that the beam members 37 are located at the top of the silo B above the swing charging door 95 and the charging mouth opening, and that the beams 38 are carried at the bottom end of the cup-shaped swingable door 40 which is hollow and in this sense forms an extension Ichamber when it is in a closed position on the main body of the preheater or silo B.
Again referring to FIGURES 3, 5 and 7, the trunnion or stud shafts 81 extend from a pair of reinforced, oppositely-positioned mounts on the outer wall 30 of the silo B at a location that corresponds substantially to its center of gravity or balance when the bottom swing door 40 is in its closed position. The trunnions or shafts 81 are pivotally-positioned within bearing mounts 82 that are carried lby a pair of structural cross members 83 of a stationary support frame 84. Swinging movement is imparted to the silo B by a reversible electric motor M3 that, with a gear reduction unit 90, is mounted on a concrete pier 91 to extend inwardly therefrom. It will be noted that the pier 91 at its upper end serves as a limit support for the silo B when in its horizontal coldscrap charge-receiving and hot-charge-delivering position of FIGURE 3. The motor M3 and gear reduction unit 90 drive a winding drum 88 through the agency of an actuating shaft 89 on which it is mounted and which extends from the reduction gear unit 90. A cable or chain 87 is anchored on the drum 88 and at one end is secured by an eyelet 85 to the outer wall 30 adjacent an upper portion of the silo B and at its other end is secured by an eyelet 86 on the outer wall 30 adjacent a lower end of the silo. Thus, an actuation of the motor M3 in a counterclockwise direction, referring to FIGURE 3, will move the silo B from its vertical position of FIG- URES 5 and 6 to its horizontal position of FIGURE 3, and a clockwise rotation will move the silo B from the position of FIGURE 3 to the position of FIGURES 5 and 6.
A reversible electric motor M1 is secured on a stand or platform 46 that extends from a side of the outer wall 30 to drive a gear reduction unit 47 that is also positioned on the same mount, see particularly FIGURES 5 and 6. The output shaft of the gear reduction unit 47 has a sprocket wheel thereon which actuates a gear and sprocket drive 48 and a cross-extending drive shaft 49. The shaft 49 is journaled in a pair of spaced-apart mounting stands 50 and, at each of its opposite ends, has a chain and sprocket gear reduction drive 52 for actuating a ily or cam wheel 55. Each cam wheel 55 is rotatablyjournaled on a stud shaft 53 extending from the wall 30, and has an eccentrically-positioned drive pin 56 thereon adapted to actuate a swing leg 57 that at its upper end is pivotally mounted on the pin 56. As particularly i1- lustrated in FIGURES 3 and 5, it will be apparent that when each wheel 55 is rotated, it will impart a swinging movement to each leg 57 such as to impart an opening and closing movement at its lower end through the agency of a pivot pin 58 that is securely mounted on the bottom swing door 40.
The swingable Ibottom door 40 which has been termed a cup-shaped door structure to generally indicate its hollow, extension-chamber-deiining structure, has a pair of outwardly-projecting hinge brackets 41 secured thereto and pivotally-mounted on a support shaft 44. The shaft 44, as shown particularly in FIGURE 6, is mounted at its opposite ends by a pair of spaced-apart brackets 43 on the outer wall 30 of the silo B. Thus, the shaft 44 serves as a pivot support for swing door 40 in its movement between opened and closed positions, as effected by actuation of the motor M1.
FIGURE 3C illustrates means for adjusting the effective scrap carrying capacity of the delivering door structure 40, in order that the scrap content of the silo B, B or B" may be proportioned to the actual requirements of a particular furnace. A bottom plate member 40a is positioned in the closed end of the door and is provided with hollow mounts 40a for a group of spacedapart adjustment screws or bolts 45. Each screw 45 has an enlarged circular head 45a that is rotatably-positioned in an associated mount 4Gb and has a threaded stem that is adjustably-carried within a threaded bushing 45C. Each bushing 45C is secured to extend across the wall section of the door 40.
Although not employed in an earlier version of the silo or preheater, such as illustrated in my above-mentioned copending application, I have now devised and provided an oscillating or agitating mechanism which facilitates the delivery of hot scrap from the silo. In a sense, it permits the scrap to be heated where desired to a slightly higher temperature at which it may become somewhat sticky and, at the same time, eliminates difficulties in delivering or discharging it away from an end portion of the preheater. The oscillator apparatus is driven by an electric motor M2 and a gear reduction unit 61 that are mounted on a stand 60 that projects from the outer wall 30 of the preheater vessel B (or B), see particularly FIGURES and 6. The output shaft of the gear reduction unit 61, in turn, drives a sprocket and chain drive 62 and a cross-extending drive shaft 63 that is journaled within a pair of mounts 63a. A small cam or fly wheel 64 is mounted on each end of the drive shaft 63 and has an eccentrically-mounted pin extending there- 'from on which one end of a swing arm 65 is pivotallysecured. Each swing arm 65 is pivotally-connected at its other end to a centrally-pivotally-mounted reciprocating arm 66.
The arm 66 is centrally-pivotally-mounted by a mounting pin 68 projecting from the outer wall 30 and is pivotally-connected at its lower end to a reciprocating finger that is, at its other end, pivotally-secured on or to an oscillator member or U-shaped agitator frame or plate, such as 70 shown in FIGURE 11. Although the details of the oscillating mechanism have been applied to the silo embodiment B of the invention illustrated particularly in FIGURES 10, l1 and 13, the operating mechanism may 'be exactly the same as applied to the 'circular silo embodiments of FIGURES 3A and 3B and of FIGURES 5 and 6, except that the frame and spacer elements or parts are circular-shaped rather than hexagonally-shaped.
Agitator or oscillator frame 70, see particularly FIG- URES 5, and 11, is slidably-mounted over the open bottom portion of the preheater silo such as B and, in this connection, is provided with a series of elongated and spaced-apart slots or slotted portions 70a that extend therethrough and that receive pin 76 therein. The pins 76 are secured to and project upwardly from an upper face of an annular bottom support plate or spacer part 7.5 that is suspended and secured by the pins 76 as a flange in a spaced relation from a bottom end closure wall 39 (See FIGURE 12) of the wall structure of the silo. Actuation of the motor M2 thus imparts a back and forth movement of the oscillator frame or plate 70 moving the slots 70a back and forth endwise along the pins 76 in such a manner as to not only provide a back and forth oscillating action of the frame 70, but also an oscillation or agitation of the lower end portions of the silo such as to shake and clean-off any lodged or sticking scrap material from the pouring edge and end closure wall 39. This is important to enable the door structure 40 to be tightly closed on the lower open end portion of the silo or container.
Referring particularly to `FIGURE 12, the periodic back and forth movement of each pin 76 with a cooperating slot portion 70a and between its ends imparts an agitation to and a cleaning, scraping-off of scrap material from the open bottom end of the silo, such that the door 40 can be swung to a fully closed position with respect to the open bottom end of the silo. It will be noted that each pin 76 at its upper end is secured in an end closure metal face plate 39 and, in turn, is secured to and supports the spacer frame or plate 75 in a suspended relation therefrom in such a manner as to define a slide spacing between the members 39 and 75 for the oscillator frame 70. Each pin 76 (see FIGURE 12) has a central, enlarged or sleeve portion 76 that extends between the members 39 and 75.
Referring to FIGURES 10, 1l and 13, I have used the same reference numerals for this embodiment of the invention represented `by the silo or preheater B" which is of hexagonal shape or section, as compared to the circular or cylindrical shape of the silo B of FIGURES 5 to 9. In this connection, the charging upper swing door (correspondng to will be planar and positioned over a mouth opening in one panel portion of the silo B". As shown in FIGURE 13, the wall construction of the silo B is provided with an insulating lining 106 between inner and outer metal plated walls and has a slightly different form of connecting structure -for such walls. As shown, I-beams 107 extend along the outside panels or wall portions between corner pieces; the I-beams 107 are spaced-apart longitudinally or vertically of and are secured to the outer wall of the silo B".
In operation of the device, hot gases issuing from the furnace G are passed through the collecting column or tower l in order that they may be tempered as desired and are then passed through a distribution chamber K such that slag may be removed before the gases are flowed into a distribution ductwork 16 and then into one of a pair of adjacently positioned preheating silos such as B, B or B. Each of the silos is substantially lled with scrap metal such as scrap steel, e.g., in the silo B or B" to a level up to the opening for the scrap charging door 95 and, when in a vertical position, its inlet ports 20a and 20b are in gas-receiving alignment with outlet portions or ports 17a and 17b of a cross-extending gas manifold 17. Since about a one-third empty space is left in the upper end portion of the silo from the standpoint of its full upright capacity with the cup-shaped door 40 and since the door provides carrying capacity, no difliculty is encountered in delivering a hot scrap portion from one end of the silo and for introducing cold scrap into its s other end as accomplished after the silo has been swung to its substantially horizontal position of FIGURE 3.
If, for some reason, the quantity or the temperature of the exhaust gas is insufficient or substantially nil as supplied from a furnace such as G or a group of furnaces (not shown), then supplementation may be accomplished through the agency of auxiliary chamber or furnace unit L. If the auxiliary unit L is not being used, then it is preferred to close both of the slide valves 23 and 23'. Although it is possible to preheat a pair of scrap silos B, I prefer to operate on an alternate ybasis whereby one silo is being subjected to a preheating operation while the other is delivering hot scrap and receiving a new charge of cold scrap. In this Way, gases from a furnace can be continuously and highly efficiently withdrawn. In FIG- URE 1, underground, cross-extending or cross-over duct 19 as connected between manifolds 17 and 22 and as provided with slide valve 18, enables supplying hot exhaust gas from either or both the furnaces G and L to both sides of the bottom end portion of each silo B. Thus, hot exhaust gas may be supplied entirely from either furnace G or L, or may be supplied as a mixture from both furnaces.
By preheating the scrap to a suitable furnace charging heat, the load on the furnace is greatly decreased, the time is decreased, and the efficiency of the melting and refining operations are increased and it is possible to increase or augment the maximum quantity of scrap material for providing the most economical charging of metal.
In employing a preheater or silo B, B', B, an upper half ofthe scrap column contained in the preheater. Coldl scrap will be fed or charged into the upper end portion of the kpreheater in an amount substantially equal to the amount of hot scrap that is removed from the bottom end thereof, assuming that the Same size of hot scrap charge is to be used on the next operation. The swing door 95 of either the silo B or B" in its open position serves as a guide chute against which the cold scrap metal may be directed and thereby guided during its introduction into the preheater silo. It is contemplated that the lower preheated one-half portion of the scrap column will be used as the furnace charge, and that the remaining half portion will have an intermediate temperature. Employing a one-third chamber basis, the upper one-third portion is empty, and the lower one-third contains the hotter scrap to be delivered to the charging bucket assembly D. The intermediate one-third contains partially heated scrap that ibecomes the bottom layer when the hotter scrap is discharged from and cold scrap is introduced into the chamber as an upper layer. When the upward flow of hot gases is accomplished through the preheater silo, then the lower portion will be heated up to the furnace charging temperature and thereafter delivered to means such as the conveyor C for charging a furnace. If, for example, the preheater charge i's 150y tons, then the lower portion removed will be 75 tons when operating on a half and half scrap basis, occupying two-thirds of the elongated silo chamber. It has been found desirable that the silo in its vertical preheating position contains a scrap column that will occupy about two-thirds of the height ofthe chamber. Since the melting furnace exhaust gases are made available to the preheating operation before they are passed through a dust collector, they may be passed directly to the dust collector without further cooling. They normally have a temperature of about 300 to 400 F. at the top vent or outlet duct 36.
The furnace L may be used where necessary to make up any deficiency incident to the utilization of the furnace exhaust gases. By employing the preheating silos in pairs, the fume utilization and collecting equipment can function continuously and without interruption and maximum utilization will be made of the full heat of the exhaust gases. The agitator or oscillator means is particularly useful at the end of the pouring of hot scrap and is eifective in dislodging and scraping off any scrap lodged on the pouring edge. This enables cleaning the face of the bottom edge of the silo so that the bottom swing door 40 can be closed with a gas-tight seal.
In operating a silo B, B or B", it is charged with cold scrap through its top end portion after it has been swung to a substantially horizontal position. At the same time, the bottom swing door 40 is opened and the preheated, hottest portion of the charge is removed from its bottom or opposite end portion and from the extension compartment of the swing door structure. It is desirable to leave an empty space extending from the top end of the silo that substantially represents the amount of cold scrap to be introduced and the amount of hot bottom scrap that is to be removed. Thus, to charge the silo withvcold scrap, it is not necessary to move the heated scrap material towards the bottom end thereof when the silo is in its horizontal position, although the remaining portion is thus moved and the introduced cold scrap portion is moved behind it to again leave an upper empty space when the silo is tilted or swung back to its vertical preheating position.
Although the invention has been illustrated with respect to particular application embodiments, it will be apparent to those skilled in the art that various changes, modifications, additions and subtractions may be made without departing from the scope of the invention as indicated in the appended claims.
I claim:
1. A scrap metal preheated comprising; a longitudinally-extending container defining an elongated scrap metal receiving chamber therein, a gas outlet port in an upper end portion of said container, said container having an open bottom end portion, a cup-shaped door structure swingably-mounted on said open bottom portion for opening and closing it off, said door in its closed position defining a continuation of the elongated chamber of said container, inlet port means at a lower end portion of said container for introducing hot gases into the elongated chamber and upwardly through scrap metal positioned therein for preheating the scrap metal, and a frame structure swingably-mounting said container for movement between a substantially vertical scrap preheating position and a substantially horizontal hot scrap delivering position.
2. In an improved scrap metal preheater as delined in claim 1, said inlet port means being carried by and being open through said door structure to the elongated chamber of said container.
3. In an improved scrap material preheater as defined in claim 2, said inlet port means of said door structure comprising, at least a pair of side inlet ports for introducing hot furnace gases through said door structure into and along the elongated chamber towards said gas outlet port of said container.
4. In an improved scrap preheater as defined in claim 3, said inlet port means also comprising, a second pair of side inlet ports on an opposite side of said door structure.
5. In an improved scrap preheater as defined in claim 1, means operatively-connected to said cup-shaped door structure for swinging it from its closing position to its opening position for discharging hot scrap metal therefrom, and means for introducing cold scrap metal within the upper end portion of said container.
6. In an improved scrap preheater as defined in claim 5, said means operatively-connected to said cup-shaped door structure comprising, fly wheel mechanism operatively-connected to said door structure, and motor actuating means operatively-connected to said iiy wheel mechanism for swinging said door structure between its closing and opening positions.
7. In an improved scrap metal preheater as defined in claim 5, said last-mentioned means comprising, an open mouth portion in the upper end portion of said container, and a swing charging door for opening and closing ofi said open mouth portion.
8. In an improved scrap metal preheater as defined in claim 7, said open mouthrportion extending through a side of said container, and means on said container for swinging said charging door between opening and closing positions with respect to said open mouth portion.
9. In an improved scrap metal preheater as deiined in claim 7, actuating means operatively-positioned on said container and connected to said charging door for moving it to an open position when said container is in its substantially horizontal hot scrap delivering position and for maintaining it in a closed position when said container is in its substantially vertical scrap preheating position.
10. In an improved scrap preheater as defined in claim 1, actuating means carried by said frame structure and operatively-connected to said container for swinging itv between its substantially vertical and substantially horizontal positions.
11. In an improved scrap preheater as defined in claim 10, said actuating means comprising, a rotatable drum operatively-carried by said frame structure, and a cable secured on said drum and connected at its opposite ends to opposite end portions of said container.
12. In an improved scrap metal preheater as defined in claim 1, said open bottom portion of said container having a closing end face, and means operatively-carried by said container for agitating scrap metal adjacent said open bottom portion to facilitate the delivery of hot scrap material therefrom and to clean-off said closing end face.
13. In an improved scrap metal preheater as dened in claim 12, said last-mentioned means comprising, an actuating motor, a rocker arm and an oscillator plate, and said oscillator plate being operatively-mounted in a suspended relation with respect to Said closing end face.
14. In an improved scrap preheater as defined in claim 13, a support plate positioned below said oscillator plate, a spaced group of elongated slot portions in said oscillator plate, and a spaced group of pins each extending through one of said slot portions and being secured at its opposite ends between said closing end face and said support plate, whereby said oscillator plate may be freely moved on said pins towards opposite ends of said slot portions.
1S. In an improved scrap metal preheater as defined in claim 1, said container having a continuous wall configuration thereabout provided wit-h a relatively smooth metal plate-like inner wall along said elongated chamber for receiving and positioning the scrap metal therein, a metal plate-like outer wall, an insulating wall portion positioned between said inner and outer walls, and peripherally spaced-apart cross-extending connecting members between said inner and outer walls.
16. In an improved scrap metal preheater as defined in claim 1, said container having a hexagonally-shaped -wall construction, said wall construction having spaced-apart inner and outer metal plate member walls, insulating material between said inner and outer walls, and cornerpositioned cross-extending connecting members between said inner and outer walls.
17. A scrap metal preheater which comprises, a longitudinally-extending container defining a scrap metal receiving chamber therewithin, a gas outlet port through said container adjacent an upper end thereof, said container having an open bottom portion, a cup-shaped door pivotally-mounted on said open bottom portion of said container for opening and closing it olf, said door defining a scrap metal receiving chamber forming a continuation of the chamber of said container when said door is in its closing-off position and having side ports for introducing hot gases into the chamber continuation and upwardly through scrap metal positioned therein for preheating the scrap metal, a frame structure centrally-pivoting said container for swinging movement between a vertical scrap metal preheating position and a substantially horizontal position, actuating means for moving said container between said positions, actuating means operatively-connected to said door for swinging said door from its closing position to an open scrap metal discharging position when said container is swung from its vertical to its substantially horizontal position, and a scrap metal introducing chute carried by said container and cooperating with said gas outlet port for introducing scrap metal into said container when said container is in its substantially horizontal position.
18. In a system for preheating scrap metal before charging it into a melting and refining furnace, a pair lof scrap preheating silos in an adjacent longitudinally spacedapart relation with respect to each other, each of said silos having an elongated scrap-receiving chamber and hot gas inlet means at its lower end portion and a cooled gas outlet and cold scrap charging opening at its upper end portion, a gas manifold connected at its opposite ends to said inlet means of each of said silos, the melting and refining furnace having a hot combustion gas outlet duct, ductwork connecting said gas outlet duct of the furnace substantially centrally to said manifold, and Valve means in said manifold for closing-olf flow of hot combustion gas from said manifold into one of said silos and for opening hot combustion gas flow to the other of said silos and vice Versa.
19. In a system as defined in claim 18, each of said silos having a second side-positioned gas inlet means in an oppositely-positoned relation with respect to said firstmentioned inlet means, an auxiliary manifold connected at its opposite ends to said second gas inlet means of said silos, a hot gas supplying combustion chamber connected substantially centrally to said auxiliary manifold, and valve means operatively-positioned in said manifold for opening and closing off gas fiow from said combustion chamber to each of said silos.
20, In a system as deiined in claim 19, a cross-over duct connected between said gas and auxiliary manifolds, and valve means in said cross-over duct for opening and closing off gas fiow therethrough.
21. A method of utilizing hot gases in preheating scrap metal that is to be charged into a melting and refining furnace, the steps of continuously providing hot exhaust gases and introducing them into a lower end portion of a preheating silo, flowing the hot exhaust gases upwardly through scrap metal in the silo and preheating it, after at least a lower portion of the scrap metal has been preheated to a hot furnace charging temperature, discharging such hot lower portion from the preheating silo for introduction into a melting and refining furnace; while discharging such hot lower portion from the first-mentioned preheating silo, shutting off the fiow of hot exhaust gases thereto and introducing them into a lower end portion of a second preheating silo; flowing the hot exhaust gases upwardly through scrap metal in the second-mentioned silo and preheating it, after at least a lower portion of the scrap metal has been preheated to a hot furnace charging temperature, discharging such hot lower portion from the second-mentioned silo for introduction into a metal melting and refining furnace and, at this time, repeating the operation of passing hot exhaust gases into the firstmentioned silo and upwardly through the scrap metal therein.
22. In a method as defined in claim 21, charging cold scrap metal into each silo while discharging the hot lower portion therefrom, and while retaining partially preheated portions of the scrap metal therewithin.
23. In a method as defined in claim 22, supplying the hot exhaust gases from a metal melting and refining furnace and from an auxiliary furnace.
24. In a method as defined in claim 23, introducing gases from the metal melting and refining furnace into one side of the lower end portion of each of the silos, and introducing gases from the auxiliary furnace into an opposite side of the lower end portion of each of the silos.
25. In an improved scrap preheater as defined in claim 1, said cup-shaped door structure having a bottom plate member positioned therein, and means cooperating with said plate member for adjusting the effective scrap carrying capacity of said door structure.
References Cited UNITED STATES PATENTS 2,794,631 6/1957 Becker et al 266--13 3,163,520 12/1964 Collin et al. 13-33 X 3,269,827 8/1966 Arnesen et al. 13-33 X 3,336,020 8/1967 Palzak 266-5 3,379,815 4/1968 Parker 13 2 BERNARD A. GILHEANY, Prima-ry Examiner H. B. GILSON, Assistant Examiner U.S. C1. X.R. 13-1, 33
US3479438D 1968-11-25 1968-11-25 Apparatus and method for preheating of metal scrap for furnace charging Expired - Lifetime US3479438A (en)

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Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
FR2478289A1 (en) * 1980-02-29 1981-09-18 Daido Steel Co Ltd PREHEATING METHOD AND PREHEATER FOR MATERIALS FOR STEEL PREPARATION
US4328388A (en) * 1980-02-11 1982-05-04 Longenecker Levi S Electro furnace feeding and furnace fume utilization and control
US4383678A (en) * 1981-10-01 1983-05-17 Longenecker Levi S Electric furnace scrap handling mill layout
US20190024980A1 (en) * 2017-07-18 2019-01-24 Amerifab, Inc. Duct system with integrated working platforms

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US2794631A (en) * 1953-03-18 1957-06-04 Becker Ernst Combined steel producing and heat generating apparatus
US3163520A (en) * 1960-12-27 1964-12-29 Elektrokemisk As Process and apparatus for preheating and pre-reduction of charge to electric furnace
US3269827A (en) * 1962-03-08 1966-08-30 Elektrokemisk As Process for preheating the charge to an electric smelting furnace
US3336020A (en) * 1964-10-23 1967-08-15 Koppers Co Inc Furnace for heating scrap metal
US3379815A (en) * 1965-09-08 1968-04-23 Lectromelt Corp Electric arc furnace having two hearths and interchangeable roofs therefor

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2794631A (en) * 1953-03-18 1957-06-04 Becker Ernst Combined steel producing and heat generating apparatus
US3163520A (en) * 1960-12-27 1964-12-29 Elektrokemisk As Process and apparatus for preheating and pre-reduction of charge to electric furnace
US3269827A (en) * 1962-03-08 1966-08-30 Elektrokemisk As Process for preheating the charge to an electric smelting furnace
US3336020A (en) * 1964-10-23 1967-08-15 Koppers Co Inc Furnace for heating scrap metal
US3379815A (en) * 1965-09-08 1968-04-23 Lectromelt Corp Electric arc furnace having two hearths and interchangeable roofs therefor

Cited By (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4328388A (en) * 1980-02-11 1982-05-04 Longenecker Levi S Electro furnace feeding and furnace fume utilization and control
FR2478289A1 (en) * 1980-02-29 1981-09-18 Daido Steel Co Ltd PREHEATING METHOD AND PREHEATER FOR MATERIALS FOR STEEL PREPARATION
US4383678A (en) * 1981-10-01 1983-05-17 Longenecker Levi S Electric furnace scrap handling mill layout
US20190024980A1 (en) * 2017-07-18 2019-01-24 Amerifab, Inc. Duct system with integrated working platforms

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