US3791636A

US3791636A - Steel mill melt shop arrangement

Info

Publication number: US3791636A
Authority: US
Inventors: C Anderson
Original assignee: Pennsylvania Engineering Corp
Current assignee: Pennsylvania Engineering Corp
Priority date: 1971-11-15
Filing date: 1971-11-15
Publication date: 1974-02-12
Anticipated expiration: 1991-02-12

Abstract

The duty cycle of electric furnaces is improved by locating each furnace in an individual bay. Each furnace bay has an overhead crane which runs on tracks that are parallel with the tracks of a similar crane in a juxtaposed bay. The corresponding ends of each set of tracks extend respectively across scrap and service bays the latter two of which are at right angles to the furnace bays. The service bay also serves as a melt transfer bay. The arrangement is such that each individual furnace bay crane can service its own furnace in respect to scrap input and melt output and other services without interference by the other. The duty cycle of each furnace is thereby maximized because none of the services required by one furnace is ever delayed by reason of waiting for a crane that is servicing the other furnace.

Description

United States Patent 1 Anderson 1 STEEL MILL MELT SHOP ARRANGEMENT Charles H. Anderson, McMurray, Pa.

[73] Assignee: Pennsylvania Engineering Corporation, Pittsburgh, Pa.

[22] Filed: Nov. 15, 1971 [21] Appl. No.: 198,573

[75] Inventor:

[52] U.S. Cl. 266/13 [51] Int. Cl. C2lc 5/52 [58] Field of Search.... 164/281; 212/1, 10, 11, 125;

13/9; 214/18 R, 18 SC; 266/13 Feb. 12, 1974 McFeaters et a1. 2 66/35 Rinesch 266/13 [57] ABSTRACT The duty cycle of electric furnaces is improved by 10- cating each furnace in an individual bay. Each furnace bay has an overhead crane which runs on tracks that are parallel with the tracks of a similar crane in a juxtaposed bay. The corresponding ends of each set of tracks extend respectively across scrap and service bays the latter two of which are at right angles to the furnace bays. The service bay also serves as a melt transfer bay. The arrangement is such that each individual furnace bay crane can service its own furnace in respect to scrap input and melt output and other services without interference by the other. The duty cycle of each furnace is thereby maximized because none of the services required by one furnace is ever delayed by reason of waiting for a crane that is servicing the other furnace.

7 Claims, 5 Drawing Figures FIGJ PAIENIEU FEB 1 21974 SHEET 10F 4 INVENTOR CHARLES H ANDERSON INVENTOR CHARLES H. ANDERSON w/wm s ATTORNEY PATENTEDFEB! 2 3.791.636

sum 3 OF 4 INVENTOR CHARLES H. ANDERSON zum w w 44 4 1 7 ATTORNEY PAIENTEUFEBIZIW 3.791.636

' SHEEN-0P4 JNVENTOR CHARLES H. ANDERSON STEEL MILL MELT SHOP ARRANGEMENT BACKGROUND OF THE INVENTION Traditionally in multiple electric furnace steel mill melt shops all melting furnaces are in a single bay. One overhead crane runs on tracks over the furnaces and performs all services required by each furnace such as scrap metal charging, additive handling, handling the discharged molten metal and providing the maintenance services and other functions incidental to melt shop operation. The purpose of having more than one melting furnace is, of course, to have a continual supply of molten metal available to supply casting machines or other molten metal utilizing apparatus. Experience has demonstrated that this purpose is often defeated because the crane is committed to performing a service for one furnace when conditions are right for it to be performing a service for another. Thus rechargingor handling the melt of a furnace is often delayed because it is necessary to wait for the crane. This reduces the potential duty cycle of each furnace so that the productivity of the melt shop is far below that which is expected for a multiple furnace shop.

In existing melt shop arrangements, productivity is also reduced by delays in transferring raw materials such as scrap metal and additives to the furnace bay so as to make them available to the furnace bay crane. A comparable situation exists in respect to handling the molten metal which must be transferred by the crane and routed to its point of use before the crane can be available to perform other functions. One of the reasons for these impediments at the input and output ends of the furnace bays was that special transfer means had to be used to bring scrap metal in or molten metal out of the accessibility range of the furnace bay crane. In other words, the furnace bay crane was dependent on activities outside of the furnace bay in which case the latter had to wait for other functions to be performed independently before it could be used to service a furnace.

SUMMARY OF THE INVENTION A general object of this invention is to improve the productivity of a multiple furnace steel mill melt shop by an equipment arrangement that is dedicated to maximizing the duty cycle of the melting furnaces.

A specific object of this invention is to locate the melting in individual bays each of which has its own overhead crane so that each crane can service its own furnace including pickingupraw materials from a common bay and delivering molten metal to a hot metal transfer bay simultaneously with the occurrence of similar activity in other furnace bays.

A still further object of this invention is to maximize the duty cycle of and make the most diverse use of other apparatus that contribute towards the primary objective of shortening the processing time of each furnace heat.

How the foregoing and other more specific objects are achieved will appear from time to time throughout the course of the forthcoming description of embodiments of the invention.

The new melt shop arrangement is generally characterized by having at least two elongated furnace bays adjacent and parallel with each other in a common building. Each furnace bay has an electric furnace located in it. Each furnace bay also has overhead crane tracks which extend longitudinally of the bay in opposite directions from the furnace area. The longitudinally disposed opposite ends of the furnace bays and their crane tracks into a scrap bay at one end and a hot metal transfer and service bay at the other end. The scrap bay and service bay are at right angles to the furnace bays and each is provided with its own crane so that deliveries can be made to a point where they are accessible to the individual furnace bay cranes. The furnace bay cranes are all at the same elevation and ei ther above or below the scrap bay and service bay cranes so that the paths of all of the cranes may cross over each other to facilitate materials handling and exchange without the use of auxiliary equipment.

Illustrative embodiments of steel mill melt shop arrangements incorporating the concepts mentioned above will now be described in greater detail in reference to the drawings.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a plan view of a steel mill melt shop arranged in accordance with the invention, the roof of the building being removed for the sake of clarity;

FIG. 2 is a vertical sectional view taken on the offset section line 2--2 in FIG. 1;

FIG. 3 is a vertical transverse section taken on the section line 33 in FIG. 1;

FIG. 4 is a plan view of an alternative steel melt shop incorporating the invention; and

FIG. 5 is a longitudinal vertical section taken on the line 55 of FIG. 4.

DESCRIPTION OF A PREFERRED EMBODIMENT The FIG. 1 plan view shows that the new melt shop arrangement comprises longitudinally extending furnace bays l0 and 11 which are parallel and juxtaposed to each other. Right angularly arranged with respect to these furnace bays and intersecting them at their respectively opposite ends are a scrap bay 12 and a service bay 13. The various bays are generally defined by parallel pairs of crane tracks most of which are overhead. For instance, elongated longitudinally disposed furnace bay 10 is defined by a pair of

overhead crane tracks

14 and 15 and furnace bay 11 has a pair of over

head crane tracks

16 and 17. Right angularly arranged scrap bay 12 has

overhead crane tracks

18 and 19. Service bay 13 is parallel with scrap bay 12 but is at the opposite end of the melt shop. Service bay 13, in this example, has one overhead crane track 22 and another crane track 23 so that this pair of tracks can accommodate a crane of the semi-gantry type.

Longitudinally oriented furnace bay 10 has an overhead crane which is symbolized by a dashed line rectangle marked with the reference numeral 24. Crane 24 runs on

overhead crane tracks

14 and 15 so that it can service the entire length of furnace bay 10. Furnace bay 11 is similarly provided with an overhead crane 25 which runs on

tracks

16 and 17 and services furnace bay 1]. The

furnace bay tracks

14, 15 and 16, 17 all have the same elevation but they are higher than the scrap

bay crane tracks

18, 19 and the service

bay crane tracks

22, 23. Thus, the cranes which run over the furnace bays 10 and 11 can cross the path of the crane which runs over scrap bay 12 and service bay 13.

Scrap bay 12 is provided with an overhead crane 26 which runs on

tracks

18 and 19 and, as can be seen in FIG. 1, this crane is adapted for crossing the ends of both furnace bays l and 11.

Service bay 13 is provided with a semi-gantry type crane 27 the leg of which runs on floor-mounted track 23 and the bridge truck of which runs on overhead track 22 as can be seen particularly well in FIG. 2. The bridge height of gantry crane 27 is less than the height of the cranes in furnace bays and 11 to facilitate crossover of the semi-gantry crane by the two

furnace bay cranes

24 and 25. Because one of the gantry tracks 23 is at floor level, it is possible for the

furnace bay cranes

24 and 25 to carry a load into the service bay 13 at a low level and without any interference by a crane track or other structural members.

Furnace bay 10 accommodates a floor-mounted conventional electric furnace which is generally designated by the numeral 28. The lower end of the furnace is in a pit 29. The furnace is constructed in a wellknown manner so that its body may be tilted on an axis which is transverse to longitudinally disposed furnace bay 10. The furnace is provided with a pouring spout 31 so that molten metal which is processed in the furnace may be poured into a ladle or other molten metal receptacle. Note that pouring spout 31 is directed along the longitudinal dimension of furnace bay 10.

Furnace bay 11 also has an electric furnace 35 located in it. Furnace 35 has a pouring spout 36 which is oriented the same as spout 31 of furnace 28 in the adjacent bay. Furnace 35 is also conventional and need not be described in any greater detail.

The electrical transformer for providing power to the arc electrodes of electric furnace 28 is accommodated in a transformer room 37 which is outside of furnace bay 10 but should be as near to the furnace as possible. Similarly, the transformer for furnace 35 is in a room 38 which is outside of bay 1 1 which accommodates this furnace.

Remote control of both

furnaces

28 and 35 is carried on from a control room which is outlined in broken lines and is designated by the reference numeral 39. Control room 39 and some other apparatus which is to be described is located in a service aisle 40. This service aisle 40 is longitudinally disposed and defined generally by the space between crane track 15 from furnace bay 10 and crane track 16 from furnace bay 11.

Attention is now invited to scrap bay 12 which is disposed transversely to furnace bays l0 and 11. As mentioned earlier, the floor and air space of scrap bay 12 is generally defined by its crane tracks 18 and 19 on which its crane 26 runs. In order to have scrap metal available for being delivered to

electric furnaces

28 and 35 by their

respective service cranes

24 and 25, a plurality of open-topped scrap bins 44 51 are provided. Scrap bay crane 26 is available for transferring scrap from the outside bins to the

inside bins

47, 48 and 49, 50 to make the scrap available to either

furnace bay crane

24 or 25. Substantially coextensive with the scrap bay 12 is a pair of railroad tracks 52 which allow scrap and other materials to be delivered to the scrap bay such as by, for example,

railroad cars

53 and 54 which are shown as broken lined rectangles. Scrap bay crane 26 may be used to transfer scrap steel from cars such as 53 and 54 to the various scrap storage bins 44 51. Scrap steel and other material may also be delivered by means of trucks, one of which is marked 55 and is shown parked for unloading in the extension of service aisle 40 which intersects scrap bay 12. There are other truck unloading pits 43 at the right end of scrap bay 12 as viewed in FIG. 1.

In line with each of the furnace bays 10 and I1, scrap bay 12 is provided with several bins 56 and 57 which are used for storing additives for the melt in the electric furnaces. The additive bins may be filled by the scrap bay crane 26 and material may be drawn out of them by either

furnace bay crane

24 or 25 without interference or delay. Additives may also be stored in an additive bin 58 which is located in service aisle 40. As can be seen in FIG. 3, additives may be brought in overhead through service aisle 40 on a conveyor such as 59. The plant may also be adapted to deliver high iron content pellets and the like through service aisle 40 with a conveyor 60. Ducts such as 61 may run directly to the

furnaces

28 and 35 through the service aisle 40.

In FIG. 1, the region where the furnace bays 10 and 1 l intersect the scrap bay 12, there are located in each furnace bay sets of scrap buckets such as 62 and 63. These scrap buckets may be filled with scrap metal and any necessary additives by the scrap bay crane 26 when it is free to do so or by their associated

furnace bay cranes

24 or 25 when they are not performing some other duty that is imperative to proper cycling of the furnaces.

When a melt is ready to be poured from a furnace such as 28, a ladle is, of course, positioned under pouring spout 31 and furnaces are tilted. It is imperative that a ladle be in readiness well in advance of pouring. A ladle such as 64 is therefore held in a preheating station where it needs to be only moved a short distance to line it up with the pouring spout 31. Furnace bay 11 also has a stored ladle 65 which is held in a state of readiness for pouring from furnace 35.

As mentioned earlier, scrap buckets 62 and 63 are usually precharged with scrap metal and additives well in advance of their delivery time to the furnaces. The contents of these buckets is usually weighed so they are on scale platforms, not shown in detail. A bucket elevator 66 is also provided in service aisle 40 in non interfering relationship with the other apparatus in the furnace bays l0 and 11.

The near ends of furnace bays 10 and 11 in FIG. 1 which are intersected by service bay 13 provide areas that can be serviced by the

respective cranes

24 and 25 of the furnace bays and by semi-gantry crane 27 in the service bay 13. The rectangular service area for furnace bay 10 is marked with the reference numeral 67 and the rectangular service area for furnace bay 11 is marked with the numeral 68. These service areas are for storing items such as slag pots 69 or prepared ladles 70 or they may be used for such maintenance functions as relining furnace roofs that are symbolized by circles marked 71 or for relining ladles as in the pit 77. Semigantry crane 27 in service bay 13 is used to transfer articles along service bay 13 to make them accessible to the cranes in the furnace bays 10 and 11.

The primary objectives of the melt shop arrangement described above is to get the maximum melt output from each of the

furnaces

28 and 35. It has been found impossible in the past to synchronize the service requirements of two or more furnaces which are located in the same furnace bay. One or morecranes in the same bay cannot act in a non-interfering manner to meet the service requirements of each furnace at the correct time. In accordance with the new melt shop arrangement described herein, however, it is evident that the individual

furnace bay cranes

24 and 25 will always be available to handle a melt when it is ready for pouring and to immediately thereafter begin recharging of the furnace to begin the next melting cycle. Thus, the furnaces can be operating continuously and molten steel output need only be limited by the capacity of the furnace.

As implied earlier, another important feature of the arrangement is the provision of a service aisle 40 between the furnace bays and 11. Besides providing a space for truck unloading, additive bins, scales, furnace control room and other equipment, this service aisle 40 also provides overhead space for running normally interfering equipment such as

ducts

72 and 73 which conduct dust and" gases from

furnaces

28 and 35 to a main conduit 74 and to a dust collector and air treatment equipment, not shown. A slag pot such as 69 which is visible in FIG. 2 may also be accommodated in a pit in the bays for transfer by means of a cart to alignment with the furnace when slag removal is desired.

Service bay 13 with which furnace bays 10 and 1 1 intersect, is also used to transport molten metal to the next stage of the steel mill where it is cast into billets or otherwise utilized. The operating cycles of

furnaces

28 and 35 can be controlled in such manner that each completes a melt at a different time. Thus, the

furnace bay cranes

24 and 25 alternate in delivering ladles of molten metal to service bay 13 where they are put to rest momentarily on the floor. Semi-gantry crane 27 then transports the ladles toward the left as viewed in FIG. 1 where they are deposited on suitable trucks, not shown, for transfer on floor tracks 76 or other suitable means into the next stage of the steel mill.

An alternative embodiment of the new steel mill melt shop arrangement is shown in FIGS. 4 and 5. This embodiment, like the one formerly discussed, has electric furnaces in separate bays each of which has their own furnace bay service crane. At least one end of the furnace bays intersects a bay that is transverse to the furnace bays and in which molten metal is either utilized or transported to an area of utilization.

Referring to the plan view FIG. 4, it is apparent that one furnace bay 80 is defined by parallel crane tracks 81 and 82 and that the other service bay 83 is defined by parallel crane tracks 84 and 85. Furnace bay 80 has a tilting electric furnace 86 whose pouring spout 87 is directed in the long dimension of bay 80. A crane 88 runs on

overhead tracks

81 and 82 for servicing furnace 86 and performing other functions. Furnace bay 83 also has an electric furnace 89 with a pouring spout 90 oriented in the same direction as pouring spout 87 in the juxtaposed bay. An overhead crane 91 runs on

tracks

84, 85. The crane 91 services furnace 89 and performs other functions.

Between the two

furnace bays

80 and 83 is a service aisle 92 which has various uses. For instance, the control room 93 for the electric furnaces may be located at one end of service aisle 92 so that both furnaces may be controlled conveniently from a single location. This optimizes personnel protection. The transformer room 94 for the furnace in bay 83 is located outside of bay 83 as shown. Transformer room 95 for the furnace in bay 80 is similarly located so that it does not interfere with the main furnace bay operations.

The service aisle 92 between the

main furnace bays

80 and 83 may also accommodate a degassing station 96. A degassing receptacle which is adapted for being sealed and for accommodating molten metal is marked with the reference numeral 97. This degassing unit is preferably mounted on trucks which run on rails 98. It should be evident that either crane 88 or 91 from the adjacent furnace base may pour molten metal into the degassing receptacle 97 when it is parked in the corresponding furnace bay after which it may be shifted on rails 98 to degassing station 96 where it is temporarily connected with vacuum lines. After degassing, the mo]- ten metal may be transported down crane track 84 to a metal utilization bay 100. For this reason, it will be noted upon inspection of FIG. 4, furnace bay crane tracks 81, 82 and 84, extend into transversely oriented utilization bay 100.

Bay 100 is provided with spaced apart crane tracks 101 and 102 on which a high crane 103 is adapted to run substantially coextensive with the length of bay 100. Note that in the FIG. 4 and 5 embodiment, the crane tracks 81, 82 in furnace bay 80, and crane tracks 84 and 85 in furnace bay 83 are at a different elevation than the

tracks

101, 102 for the utilization bay crane 103 so that the cranes 88 and 91 of the furnace bay may run into utilization bay 100.

Bay 100, which is transverse to

furnace bays

80 and 83, may have in it molten metal utilization equipment such as one or more continuous casting machines which are generally designated by reference numerals 105 and 111. The illustrated casting machines are of the vertical type although the horizontal type could be used. Molten metal that is taken by either of the furnace bay cranes 88 or 91 in ladles may be deposited on the floor of bay 100 after which the ladles may be picked up by crane 103 and poured into the tundishes 106 of the casting machines. A hot billet or strand is formed in a mold such as 107 after which the strand follows a curved guide 108 which changes the direction of the strand from vertical to horizontal. The strand runs out of the building which contains bay 100 in a runout bed 109 where the billets are sheared to length and transported with a crane 110 into another building for storage or for further processing. As suggested by the FIG. 4 plan view, there may be one or more casting machines such as 111 in addition to casting machine 105 because the two

furnaces

89 and 86 can be serviced independently by their cranes 88 and 91 and a supply of molten metal is always available to each casting ma chine. In prior melt shops, where both electric furnaces were located in the same bay, the process was often interrupted or delayed because the furnace bay service crane was often otherwise occupied when a furnace was ready for pouring its melt.

The transverse utilization bay 100 may also be devoted to other functions connected with servicing the

furnace bays

80 and 83. For instance, ladles and furnace tops may be relined with refractory material and otherwise serviced as indicated by the reference numeral 114 applied to the items which symbolize these functions in bay 100. In any event, it should be evident that when a furnace bay crane such as 88 exchanges objects between furnace bay 80 and bay 100 that the other furnace bay crane may carry on its normal function of serving its bay 83. This means that both bay service cranes 88 and 91 can be in the right place at the right time for recycling the

electric furnaces

86 and 89 without any delay due to waiting for a crane.

As can be seen in the FIG. 4 and 5 embodiment, steel scrap and other raw materials may be brought into the

respective furnace bays

80 and 83 on scrap transfer cars 115 and 1 16 which run on

tracks

117 and 118. The cars may be switched between

tracks

117 and 118 if desired by means of a switching track 119. It will be evident that the scrap transfer cars may' be admitted into the ends of the

respective furnace bays

80 and 83 where their contents are made accessible to furnace bay servicing cranes 88 or 91. Thus, it is possible to completely service electric furnace 86, for instance, with its crane 88 without having to wait for a crane while it may be servicing the other furnace 89.

There may also be

elevated tracks

120 and 121 for a yard crane, not shown. If desired, the building can be so constructed that the crane tracks of the

furnace bays

80 and 83 are above or below the yard crane tracks 120, 121 and the latter may extend into the building or the former may be extended out of the building so that the crane tracks overlap to facilitate exchange of materials from inside to outside without use of the scrap transfer cars on tracks.

Note that a number of auxiliary functions may be carried on in close proximity with

furnace bays

80 and 83 but outside of them so as to avoid any interference and preserve the safety of personnel. Thus, next to furnace bay 80 an electrode storage housing 122 is located adjacent an office 123 and a laboratory 124. On the other side, clear of furnace bay 83 may be located another electrode storage housing 125 and a water or air cooler or other apparatus such as 126 which is symbolized by a rectangle. Service aisle 92 also permits keeping the furnace bays clear of undesired obstructions and provides a space for the future installation of overhead conveyors which may be used to convey pellets that are ready for processing directly to the electric furnaces. A cooler and dust collector arrangement 127 may be located outside of the furnace bays and there may be a duct such as 128 running overhead and down through the service aisle 92 to make connection with the furnaces for exhausting dust and other noxious gases.

In summary, two embodiments of a new metal melt shop arrangement have been described. Each has the common characteristic of juxtaposed furnace bays with one furnace in each bay. Overhead cranes run parallel along the furnace bays and at such elevation that they can intersect with areas that have transverse crane tracks at another elevation. The arrangement is such that the functions associated with one electric furnace bay can be carried on coincidentally with a similar function in the other furnace bay because of the use of independent crane in the service bays. This means that the duty cycle of the individual electric furnaces can be maximized and that the production of molten steel with the furnaces in the juxtaposed bays will be greater than the production from furnaces arranged in accordance with the prior where they were in the same bay and subject to lengthening their cycles because of waiting for the service crane.

Although preferred embodiments of the invention have been described in considerable detail, such description is to be construed as illustrative rather than limiting, for the invention may be variously embodied and is to be limited only by interpretation of the claims which follow.

I claim:

1. A steel melt shop comprising:

a. at least two nominally longitudinal substantially coextensive and generally parallel furnace bays each of which has a metal melting electric furnace located entirely within the confines of its own bay, respectively,

b. crane tracks disposed longitudinally of each furnace bay at a predetermined elevation above the furnace in said bay, said crane tracks extending beyond at least one end of the furnace bays,

c. a crane extending across the width of each of said furnace bays and adapted to run on the crane tracks in each furnace bay, each furnace bay crane being for servicing the furnace in its bay exclusively,

d. a service aisle between said two parallel bays, the

width of said service aisle being defined substantially by the distance between a crane track in one furnace bay to the nearest crane track in the other adjacent furnace bay,

e. a bay that is located transversely to the corresponding ends of said furnace bays and is in such proximity therewith so that the aforesaid furnace bay crane tracks extend into said transverse bay, an end of said service aisle junctioning with said transverse bay,

f. crane tracks disposed along the transverse bay transversely to the crane tracks of the furnace bays but at other than said predetermined elevation,

g. a crane adapted to run on said transverse crane tracks, the said furnace bay cranes being movable on the part of their tracks which extends into said transverse bay so as to enable exchange'of materials between the path of the transversely movable crane and the paths of the furnace bay cranes.

2. The invention defined in claim 1 wherein:

a. said transverse bay has scrap metal storage means which are between the furnace bay crane tracks where they extend into-the transverse bay, whereby the furnace bay cranes may individually and independently move scrap metal from said transverse bay to each of the furnaces in said furnace bays.

3. The invention defined in claim 1 wherein:

a. said transverse bay has molten metal utilization means located in said bay, whereupon molten metal that is delivered by any of the furnace bay cranes to the path of said transversely movable crane may be transferred directly to said utilization means by said last named crane.

4. The invention defined in claim 3 wherein:

a. said metal utilization means is a continuous casting machine.

5. The invention defined in claim 1 wherein:

a. said transverse bay has floor mounted tracks extending in the lengthwise direction thereof, said tracks accommodating cars for delivering scrap metal and other materials into said transverse bay for accessibility by the crane therein.

6. The invention defined in claim 1 including:

a. a second bay that is transverse to said furnace bays at the end opposite thereof from the aforesaid transverse bay,

b. said second transverse bay having crane tracks extending lengthwise thereof and a crane adapted to run on said last mentioned tracks in a path that crosses the crane tracks of the furnace bays and is at a different elevation than the furnace bay cranes.

7. The invention defined in claim 1 including:

a. exhaust ducts extending through said service aisle to the respective furnaces in the adjacent furnace bays.

Claims

1. A steel melt shop comprising: a. at least two nominally longitudinal substantially coextensive and generally parallel furnace bays each of which has a metal melting electric furnace located entirely within the confines of its own bay, respectively, b. crane tracks disposed longitudinally of each furnace bay at a predetermined elevation above the furnace in said bay, said crane tracks extending beyond at least one end of the furnace bays, c. a crane extending across the width of each of said furnace bays and adapted to run on the crane tracks in each furnace bay, each furnace bay crane being for servicing the furnace in its bay exclusively, d. a service aisle between said two parallel bays, the width of said service aisle being defined substantially by the distance between a crane track in one furnace bay to the nearest crane track in the other adjacent furnace bay, e. a bay that is located transversely to the corresponding ends of said furnace bays and is in such proximity therewith so that the aforesaid furnace bay crane tracks extend into said transverse bay, an end of said service aisle junctioning with said transverse bay, f. crane tracks disposed along the transverse bay transversely to the crane tracks of the furnace bays but at other than said predetermined elevation, g. a crane adapted to run on said transverse crane tracks, the said furnace bay cranes being movable on the part of their tracks which extends into said transverse bay so as to enable exchange of materials between the path of the transversely movable crane and the paths of the furnace bay cranes.

2. The invention defined in claim 1 wherein: a. said transverse bay has scrap metal storage means which are between the furnace bay crane tracks where they extend into the transverse bay, whereby the furnace bay cranes may individually and independently move scrap metal from said transverse bay to each of the furnaces in said furnace bays.

3. The invention defined in claim 1 wherein: a. said transverse bay has molten metal utilization means located in said bay, whereupon molten metal that is delivered by any of the furnace bay cranes to the path of said transversely movable crane may be transferred directly to said utilization means by said last named crane.

4. The invention defined in claim 3 wherein: a. said metal utilization meaNs is a continuous casting machine.

5. The invention defined in claim 1 wherein: a. said transverse bay has floor mounted tracks extending in the lengthwise direction thereof, said tracks accommodating cars for delivering scrap metal and other materials into said transverse bay for accessibility by the crane therein.

6. The invention defined in claim 1 including: a. a second bay that is transverse to said furnace bays at the end opposite thereof from the aforesaid transverse bay, b. said second transverse bay having crane tracks extending lengthwise thereof and a crane adapted to run on said last mentioned tracks in a path that crosses the crane tracks of the furnace bays and is at a different elevation than the furnace bay cranes.

7. The invention defined in claim 1 including: a. exhaust ducts extending through said service aisle to the respective furnaces in the adjacent furnace bays.