Patent Abstract:
A combined arc furnace, ladle metallurgical furnace and vacuum degassing system having the flexibility to produce at least non-vacuum arc remelt, vacuum arc remelt, vacuum oxygen decarburized non-vacuum arc remelt, and vacuum oxygen decarburized vacuum arc remelt steels from one off to continuous casting end uses in steady state or randomized order which utilizes only a minimum of energy attributable to preheating hot metal contacting components of the system followed by heat loss reduction of the components and use of a carryover heel in the arc furnace, in which the throughput of the system is limited solely by the melting capacity of the arc furnace.

Full Description:
BACKGROUND OF THE INVENTION 
       [0001]    This invention relates generally to electric arc furnace steel making and specifically to such systems having a ladle metallurgical furnace therein, which systems require decreased energy input per unit of steel produced compared to similar systems. It is particularly directed to making alloy steel at a rate limited only by the maximum melting capacity of the arc furnace. In addition the invention, without modification, is adaptable to nearly every end use found in the steel industry today from continuous casting to unique, one of a kind melts of widely varying compositions in a randomized production sequence. 
         [0002]    For example, the invention enables the production of up to four different types of steel (as distinct from grades of steel) in a single electric arc furnace system without slowdown or delay in the processing sequence of heats regardless of the number or randomized order of the different types of steel to be made in a campaign. Thus the system will produce at least non-vacuum arc remelt steel, vacuum arc remelt steel, vacuum oxygen decarburized non-vacuum arc remelt steel and vacuum oxygen decarburized vacuum arc remelt steel. 
         [0003]    For some years extending up to about the last decade and a half the vacuum arc degassing system was practiced throughout the world for the production of steel having alloy, gas, grain size and inclusion contents within narrowly defined ranges. In this system steel tapped from an electric arc furnace was thereafter subjected to the combined effects of a low vacuum, a purging gas, and alternating current heating arcs struck between graphite electrodes and the wildly boiling surface of the molten steel while it was subjected to the combined effects of a low vacuum and the purging gas. This system is usually referred to as the vacuum arc degassing system. Millions of tons of steel have been produced by this method and significant tonnage continues to be produced at this date. This method has advantages unachievable by the prior competitive systems including the ability to teem at plus or minus 10° F. at any desired time extending for as long as at least eight hours from furnace tap. Thus a 100 ton ingot could be produced from a system having only one 50 ton arc furnace, and ample time was always available to compensate for planned, or unexpected, downstream delays, thereby avoiding return of a melt to the arc furnace. 
         [0004]    However, during normal operations in such systems the throughput of the system is governed by the processing time in the arc furnace and, in most installations, the processing time for a single heat can be upwards of four to four and one half hours due to the extensive steel making which takes place in the arc furnace; in other words, the steel resides in the arc furnace long after the scrap charge has melted and reached tapping temperature. 
         [0005]    With increasing pressures on the steel maker to lower costs and increase throughput using conventional arc furnace technology the lengthy, by comparison, arc furnace steel making technology has had to be abandoned in favor of shorter cycles which achieve the same end result. 
         [0006]    For approximately the past 15 years the ladle metallurgical furnace system has begun supplanting traditional arc furnace and vacuum arc degassing steel making technology. In the ladle metallurgical furnace system the arc furnace has been confined to being almost solely a melting unit, with most steel making deferred to downstream operations. For the arc furnace in such a system this has resulted in a much shorter dwell time of the scrap charge in the furnace since raw scrap (and early lime and carbon additions) can be brought to tapping temperature in about two hours, or less, compared to the four to four and one half hours required in conventional arc furnace steel making in the same size furnace. The use of larger electrodes has also contributed to decreased furnace dwell time. In a specific example which will be described in greater detail hereafter, the furnace dwell time from the beginning of charging to the end of tapping will be decreased from four to four and one half hours to two hours or less. 
       BRIEF SUMMARY OF THE INVENTION 
       [0007]    In this invention, the increased throughput will be achieved by reducing heat sink in the molten steel contacting components of the system, the use of carryover heat from melt to melt and the prompt placement of a stripped ingot, while it is still hot, into a heating furnace to heat the initially partially heated ingot to deformation temperature for the subsequent forging operation. 
         [0008]    The decrease of heat loss due to heat sink will be achieved by preheating a selected component or components of the metal contacting units. For example, by preheating the tapping ladle until the refractory lining will be in the vicinity of about 2000° F., and then slowing the cooling rate of the tapping ladle by use of a refractory cover which is applied to the upper open end of the ladle until moments before tapping, the tapped metal will be minimally cooled during the tapping step. 
         [0009]    Heat input to the system will be further decreased by carryover of a minor, but effective, quantity of molten steel from one tap to the next. Thus, for example, assuming start up from an empty arc furnace, and with an aim of teeming 75 tons of molten metal, approximately 80-85 tons of solid scrap will be charged into the arc furnace. After melting, a melt consisting of seventy-five tons of molten metal will be tapped into a tapping ladle. 
         [0010]    Upon completion of tap, and return of the arc furnace to an upright position, the furnace cover will be moved away from the furnace bowl and approximately seventy-five tons of solid scrap will be charged into the approximately ten tons of molten steel carried over from the immediately preceding melt. The carryover melt plus the turnings from the scrap charge bucket in the succeeding heat will form a reservoir of hot metal which will engulf and thereby melt the scrap hot tops and other large pieces in the arc furnace charge at a much faster rate than if the furnace bowl was totally empty before the first scrap charge bucket was emptied into the arc furnace; the carryover metal will surround and transfer conductive heat to the large pieces of scrap much sooner than would occur if the bushelings and other small pieces of scrap had to change from solid to liquid state before conduction heating of the large pieces could begin. 
         [0011]    The invention ensures that at least four different steel making processes may be practiced in any day and in any sequence, the specific process performed depending only on the sequence in which the different types of steel are ordered to be made. This hitherto unattainable flexibility in end use will be attainable in a single plant which will be adaptable to carry out steel making processes which are currently recognized as separate and distinct but which are seldom, if ever, found in existing plants. 
         [0012]    Thus, for example, the steel maker may have a sufficient number of orders for low alloy steel that one or more successive heats of steel need only be subjected to the basic processing steps of melting, refining in the ladle metallurgical furnace, degassing at the vacuum degassing station, teeming and solidification. 
         [0013]    However if the steel maker&#39;s next customer desires a vacuum arc remelt (VAR) product, the steel maker, after melting, ladle metallurgical refining, vacuum degassing and teeming a succeeding melt to form an ingot, may divert the solidified vacuum degassed ingot to a vacuum arc remelt unit in which the solidified vacuum degassed ingot will be converted into a VAR electrode, the VAR electrode remelted in the VAR unit to form a VAR ingot, and the resultant VAR ingot thereafter processed as required, such as forging and heat treatment. 
         [0014]    And should a third customer order a vacuum degassed and vacuum oxygen decarburized steel, that third customer&#39;s order may be started without delay in the arc furnace without alteration of the first two stages—the melting and ladle metallurgical refining stages—and then subjected to vacuum oxygen decarburization in the vacuum degassing unit, to be followed by teeming and solidification. 
         [0015]    And, further should the steel maker&#39;s fourth customer order specify a vacuum oxygen decarburized vacuum arc remelted steel, the processing of such a special steel may be incorporated into the production sequence without delay and without alteration of either of the first two processing stages—arc furnace melting and ladle metallurgical furnace refining—which steps require the longest blocks of time as will be seen hereafter. 
         [0016]    It is accordingly an object of the invention to provide, in a system having a single arc furnace, a single ladle metallurgical furnace and a single vacuum treatment station, the ability to carry out at least four dissimilar steel making processes in randomized order, namely high volumes of standard grades of vacuum degassed steel, vacuum arc remelted steel, vacuum oxygen decarburized extra low carbon steel, and vacuum oxygen decarburized vacuum arc remelted extra low carbon steel. 
         [0017]    Another object of the invention is to carry out the above described steel making processes in which the vacuum treatment common to all four processes cannot be compromised by unintended degradation of the vacuum integrity of the system attributable to utilizing the metal containing vessel as a component of the vacuum system. 
         [0018]    A further object of the invention is to decrease the heat energy required per unit, such as a ton, of steel produced as contrasted to conventional ladle metallurgical furnace refining systems. 
     
    
     
       BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING 
         [0019]    The invention is illustrated more or less diagrammatically in the accompanying drawing in which 
           [0020]      FIG. 1 , consisting of sub-parts  1 A,  1 B and  1 C, is a plan view of a system, with certain parts indicated schematically or by legend, for carrying out the processes of the invention; 
           [0021]      FIG. 2 , consisting of sub-parts  2 A,  2 B and  2 C, is a side view of the system of  FIG. 1 , with certain parts indicated schematically or by legend, for carrying out the processes of the invention; 
           [0022]      FIG. 3  is an elevation with parts in section, and others in phantom, of the arc furnace and the system ducting; 
           [0023]      FIG. 4  is a view similar to  FIG. 3  but to a larger scale and illustrating particularly the ducting connection between the furnace and the stationary ducting system; 
           [0024]      FIG. 5 , consisting of positions  5 A,  5 B and  5 C, is a schematic illustration of the operating, tapping and slag off positions of the bowl of the electric arc furnace; 
           [0025]      FIG. 6  is a partly schematic half section of the ladle metallurgical furnace portion of the system illustrating particularly the use of a sub-surface oxygen lance; 
           [0026]      FIG. 7  is a partial schematic view of the temperature and sampling features of the ladle metallurgical furnace component of the invention; 
           [0027]      FIG. 8  is a view of the alloy wire feed feature of the ladle metallurgical furnace; 
           [0028]      FIG. 9  is a section through the roof of the ladle metallurgical furnace with one half of the roof rotated 60° illustrating particularly the alloy and other charge material addition system of the LMF; 
           [0029]      FIG. 10  is a vertical section through the combination vacuum degassing and vacuum oxygen decarburization treatment features of the vacuum treatment station showing the station in vacuum degassing mode; 
           [0030]      FIG. 11  is a top section through the tank of the combination vacuum degassing and vacuum oxygen decarburization station showing a ladle in position for vacuum treatment therein; 
           [0031]      FIG. 12  is a perspective view of the vacuum treatment station with parts omitted for clarity and the cover elevated and rolled away preparatory to the reception of a ladle to be treated; 
           [0032]      FIG. 13  is a top plan view of a ladle of steel in a teeming car; 
           [0033]      FIG. 14  is a side view of the ladle of  FIG. 13  in an elevated position in the teeming car preparatory to teeming into a pouring trumpet; and 
           [0034]      FIG. 15  illustrates the mold stripping area adjacent to the teeming pit. 
       
    
    
       [0035]    Like parts will be used to refer to like or similar parts from Figure to Figure of the drawing. 
       DETAILED DESCRIPTION OF THE INVENTION 
       [0036]    The system of this invention, which system enables at least four separate and distinct inventive steel processes to be carried out, is indicated generally at  10  in  FIGS. 1 and 2 . The invention can be best understood by reading each of  FIGS. 1 and 2  from right to left commencing with  FIG. 1 . 
         [0037]    A scrap house is indicated generally at  11  and scrap suitable for making any desired type of steel from extra low carbon stainless to low alloy is indicated at  12 . Scrap stocking means, here a rail system, is indicated at  13 . The rail system will be constructed so as to be able to transfer system scrap, such as hot tops and pyramid ingots, from downstream collection points in the system and, also, fresh scrap received from outside the system. Scrap may arrive by non-rail transport such as truck. Scrap charging cars are indicated at  14 ,  15 , each scrap car traveling on an associated set of rails  16 ,  17  each of which extends from the scrap house to a terminus  18 ,  19  adjacent an arc furnace indicated generally at  30 . Scrap cars  14 ,  15  carry charging buckets  20 ,  21  respectively which receive scrap from the scrap house by any suitable means, such as a mechanized crane, not shown for purposes of clarity. Each of scrap buckets  20 ,  21  includes a bail  22 ,  23  respectively mounted on trunnions located on each side of the scrap buckets, and U-shaped lifting brackets  24 ,  25  respectively. 
         [0038]    A spare charging bracket is indicated at  26  having a bail  27  and lifting bracket  28 . 
         [0039]    The arc furnace includes a bowl indicated generally at  31 , best seen in  FIG. 2 . The furnace is rockable in a vertical plane, best seen in  FIG. 5 , by means of a toothed rack  32  and pinion  33  system, see  FIGS. 2 and 5 , mounted on a rocker pedestal  34 . A cover is indicated generally at  35 . In  FIG. 1A  the cover is shown in its closed, operative position by solid lines and in its open, charging position by phantom lines. The cover swings from the charging to open position about pivot  36 . Cover  35  is rigidly carried by left and right cover suspension arms  38 ,  39  extending from a base structure which swings about pivot  36 . Three electrode feeds are indicated at  42 ,  43  and  44  which terminate at graphite electrodes  45 ,  46  and  47  respectively. For a system capable of melting about 75-115 tons the electrodes are preferably 16″ in diameter and capable of generating about 75 MVA during a melting sequence. 
         [0040]    A chute system for adding charge materials such as carbon and lime to the furnace is indicated at  49 . A sampling device is indicated at  50 , the sampling device accessing the heat in the furnace through flapper  51 . A slag off door is indicated at  52 . An oxygen and carbon injection lance system is indicated at  53 . When the arc furnace cover  35  is in operating position on top of the arc furnace bowl, the bottom surface of the rim  37  of the cover  35  makes contact about its entire periphery with the top surface of the rim of the bowl  31  as best seen in  FIG. 2A . Although the fit is close, it is not vacuum tight. 
         [0041]    The arc furnace ducting system is indicated generally at  55  in  FIGS. 1A and 3 . The ducting system includes an offtake elbow  56  which connects, at its inner end, with an opening in the cover  35 , and terminates, at its discharge end, in a circular flange  57 . The stationary portion of the ducting system includes an intake elbow  58  terminating in a circular flange  59 . When the cover is closed, circular flange  57  of the cover offtake elbow  56  is in closely spaced relationship with flange  59  of intake elbow  58  of the ducting system. From  FIGS. 1A and 3  it will be noted that the clearance between the flanges  57  and  59  is very small with the result that very little, if any, of the fumes generated during furnace operation will escape from the slight space between the flanges. Ducts  60  and  61  convey the fumes collected from the furnace to the bag house indicated in  FIG. 1A . 
         [0042]    From  FIG. 2A  it will be seen that, with the cover  35  swung to the open position of  FIG. 2A  (and the phantom position of  FIG. 1A ), a scrap crane indicated generally at  63  having a hook  64  will lift first charging bucket  21  off scrap car  15  and position the bucket over the open furnace bowl  31  from whence the scrap in the bucket is loaded into the bowl  31  of furnace  30 . 
         [0043]    The three electrodes  45 ,  46  and  47  are moveable by a gantry type lifting assembly  66 , see  FIG. 3 , from the operating positions shown in solid lines in  FIGS. 3 and 4  to the retracted position of  FIG. 3 , shown in phantom, so that the cover  35  can be swung to the charging position of  FIG. 2A . The cover is water cooled by inlet and outlet piping  67  and  68 , see  FIG. 4 . Each of electrodes  45 ,  46  and  47  are composed of separate sections which are screwed together as seen in  FIG. 3 . A spare electrode section is indicated at  69  in  FIG. 3 . 
         [0044]    A tapping ladle car is indicated at  70  which runs on track  71  which track extends, in this instance, from just beneath the arc furnace  30  at its upstream end to a position just short of the next treatment station shown in  FIG. 2B . A tapping vessel, here a tapping ladle is indicated at  72  in  FIG. 2A  on the tapping car  70 , the tapping ladle having trunnions  73 ,  74  by which the ladle may be transported by crane. In  FIGS. 1A and 2A  the tapping car  70  and ladle  72  are positioned just beneath the tap hole  75  of arc furnace  30 . 
         [0045]    Although only one tapping car  70  and tapping ladle  72  are used, a second tapping car and ladle has been shown in  FIG. 2A  to represent the location of the car and ladle during an important preceding operation to be described hereafter. 
         [0046]    While a melt is being made in the arc furnace  30 , a tapping ladle  72  will undergo preheating to at least about 2000° F. by a preheat lance  76 . Immediately upon preheating the tapping ladle to a desired temperature, the preheat lance is turned off and removed, and a shield, indicated generally at  77  in  FIG. 2A  is placed directly on the rim of the ladle. The shield  77  is composed of a backing plate  78  and an insulation layer  79  formed from a high temperature resistant fibrous refractory. The shield is raised and lowered as indicated by the vertical arrow by crane hook  80  which hooks into lifting bracket  81  of the shield. As soon as the melt in the furnace  30  is ready for tap, the shield  77  is raised. At this time, and if required by the heat instructions, charge materials, such as alloys, may be added to the tapping ladle  72  from alloy feed assembly  82 . The tapping car  70  and preheated tapping ladle  72  are then positioned beneath the arc furnace tap hole  75  as seen in  FIG. 2A . 
         [0047]    A slide gate for the arc furnace is indicated at  84 . In  FIG. 5 ,  FIG. 5C  represents the arc furnace in melting or empty condition,  FIG. 5B  represents the furnace in slag off position and  FIG. 5A  represents the furnace in tapping position. 
         [0048]    Referring now to  FIG. 2B , the tapping ladle car  70  together with its now filled ladle  86 , containing anywhere between 75 and 115 tons of tapped metal, is shown near the downstream terminus of its track  71 . At this point the filled ladle  86  is lifted by crane  85  from its position at the terminus of track  71  to a ladle metallurgical furnace (LMF) car  87  located at the upstream terminus of its associated LMF track  88 . Tapping car  70  now returns to its preheat position shown in  FIG. 2A  to receive the next tapping ladle and then await the next melt to be tapped from the arc furnace  30 . 
         [0049]    The LMF station includes a roof, indicated generally at  90 , through which three electrodes  91 ,  92  and  93  project downwardly in its center region. The electrodes receive power from a power source  94  and power leads  95 ,  96  and  97  shown in  FIG. 1B . The electrodes are snugly received in opening  98  in the center plate  99  as best seen in  FIGS. 8 and 9 . A flapper  100  shown best in  FIG. 1B  in roof  90  will permit temperature sampling by the system of  FIG. 7  and chemical sampling by the system of  FIG. 6 . Bulk alloys are added as required through alloy chute system indicated generally at  101  in  FIG. 1B , and in greater detail in  FIG. 9 . The bulk alloy chute system  101  includes a feed conduit  102  which is connected to a number of hoppers, not shown, each hopper containing a desired alloy material. An inclined chute  103  passes into the chamber beneath the LMF roof through opening  104 , which opening can be sealed by a plate  105  when required. An electronic chute control system indicated generally at  106  in  FIG. 9  will be operable to regulate the order and quantity of alloy and slag materials to be added to the heat at any desired time or times. 
         [0050]    An alloy wire addition system is indicated generally at  108  in  FIG. 1B  and in greater detail in  FIGS. 8 and 9 . The system includes drive rollers  109  which, working through appropriate controls, will drive alloy feed wires  110 ,  111  downwardly toward a funnel  112 ,  FIG. 8 , from whence the particular alloy wire desired to be added to the heat enters feed tube  113 . Feed tube  113  enters the chamber inside the LMF cover through opening  114  in the cover. In  FIG. 8  only wire  110  is being added to the heat in ladle  86 . 
         [0051]    From  FIGS. 8 and 9 , and also in  FIG. 6 , it will be noted that the LMF roof  90  includes a bottom flange  116  which rests upon top flange  117  of the ladle  86 . Since metal to metal contact is made a vacuum tight seal does not occur. It will be understood that the operation of the arcs and the chemical reactions which take place during the formation of the heat during the arcing period of the LMF will generate a large volume of fumes. The fumes so generated will follow a path indicated by the arrows in  FIGS. 8 and 9  to a large offtake duct  118 ,  FIG. 1B , and then to the duct system  55  and the bag house  115  shown in  FIG. 1A .  FIGS. 6 ,  7 ,  8  and  9  also show the water cooling system of the LMF roof indicated generally at  119  in  FIG. 9 .  FIG. 9  also shows, in connection with wire feed system  108 , a slide plate system  120  which includes flap plate  121  actuated by control system  122  for uncovering an opening in the LMF roof for a sufficient period of time to feed in the required pounds of wire alloy. Although any alloy in wire form may be added it will be understood that Al is most frequently added. The dwell time of the ladle  86  in the LMF will vary with the size of the heat and the required degree of superheat. For a heat size of approximately 75 tons the arcs may be turned off when the temperature of the heat is about 3000° F. 
         [0052]    Following extinguishment of the arcs the LMF roof and electrodes  95 ,  96  and  97  are raised to a position in which they clear the upper rim  117  of the LMF ladle. The LMF car  87  is then moved to its downstream terminus  123  of the LMF track  88 , shown best in  FIGS. 1B and 2B , which is closely adjacent, upstream, to the vacuum treatment station indicated generally at  126 . 
         [0053]    Vacuum treatment station  126  includes a stationary vacuum tight tank base  127 , here shown as embedded in the ground in  FIGS. 2B and 10 , and a tank cover assembly indicated generally at  128 . The tank cover assembly includes tank top  129  which is mounted to and carried by a wheeled gantry type superstructure  130 . Lift jacks  131  raise and lower the tank top  129 . The gantry type superstructure, shown best in  FIG. 12 , is comprised of a platform  132  mounted on wheels  133  and  134  which roll on tracks  135  and  136  respectively. In the illustrated embodiment the tracks  135  and  136  are at different elevations with respect to a reference base but it will be understood that, to accommodate space limitations, the tracks could be at a common height, as is implied from the schematic showing in  FIG. 1B . In any event, the tank top must be moved a sufficient distance to provide unimpeded access to the tank bottom from above so that a ladle to be treated can be dropped therein by crane. 
         [0054]    The vacuum tank base  127  includes a pair of ladle saddles, one of which is indicated generally at  138 . Each ladle has a pair of projections indicated at  139 , see  FIGS. 2B and 4 , which rest on mating saddles  138  when the ladle is lowered into the vacuum tank base  127 . 
         [0055]    Vacuum tank cover assembly  128  carries a sight port  140 , a bulk alloy and charge material dispenser  141 , a wire feed assembly indicated generally at  142 , and a temperature and sampling port  143 . Again, although the illustrated structure indicates the flexibility of adding up to four wire alloys, aluminum will be the most often added since it will have its maximum grain refinement effect at this time in the cycle. A central port, which is covered by a vacuum tight cover plate  144  during non-vacuum decarburization cycles, is illustrated best in  FIG. 1B . 
         [0056]    The vacuum system, which functions during straight vacuum degassing and vacuum oxygen decarburization cycles, and also the gas purging system, are illustrated best in  FIGS. 10 and 11 . 
         [0057]    In  FIG. 10  it will be seen that the lower rim of vacuum tank top  129  includes a tank top rim plate  146  whose flat undersurface is machined to form a close fit around its entire periphery with a mating surface on a rim plate  145  at the top of tank base  127 , which top rim plate  145  has been similarly machined. A seal means, here represented by an O-ring seal  147 , which functions in conjunction with the mating, close fitting rim plates, forms a vacuum chamber which is effective to create a vacuum pressure of one ton and less in continuous operation. This arrangement in this system wherein the entire ladle containing the molten metal is entirely within the vacuum environment has a distinct advance over systems in which the ladle itself forms part of the vacuum chamber. In such systems the possibility of leaks is constantly present due to the exposure of the upper rim of the ladle to degradation due to conditions in a melt shop, such as dribble of molten steel onto the upper exposed rim of the ladle, or the presence of hard particles, which are ever present in a melt shop environment, landing on the rim and thereby compromising the metal to metal seal. Further, in the instant system the outer metal wall of the ladle will have weep holes drilled therein so that gases contained in, primarily, the ladle refractory, may escape. In systems in which the ladle, before entering the vacuum tank, is exposed to ambient air for long periods of time (as contrasted to the short exposure to ambient atmosphere before teeming in the rapid cycle of the present invention) weep holes will permit the ladle refractory to becoming loaded with moisture containing air. 
         [0058]    The ambient atmosphere in the present invention is removed through an offtake duct  149  which is part of a multistage steam jet ejector system, preferably a four or five stage system. 
         [0059]    It will be noted from  FIG. 10  that the filled ladle  86  rests upon an elevating base structure indicated generally at  151 , here a plurality of beam cross sections. Should a breakout occur during operation, the elevating base structure ensures that the ladle base will not weld to the runaway metal so that the ladle can be lifted out of the tank to expedite clean up. 
         [0060]    In vacuum oxygen decarburization cycles, including both vacuum arc remelt and non-vacuum arc remelt cycles, the vacuum treatment station is, in effect, modified to include oxygen lance blowing. Referring to  FIG. 10 , and during the oxygen addition portion of the operation, an oxygen lance  153 , which is moved vertically up and down by guide structure  154 , enters the tank chamber after the central port cover plate  144  is removed. The oxygen lance  153  passes through an auxiliary refractory heat shield  156  which is needed due to the extra heat generated by the carbon and oxygen reaction. The refractory cover plate  157 , which has a central opening  158  to accommodate the lance  153 , will have been placed on the top edge of the ladle after ladle left the LMF station. The lance housing  155  and the lance  153  move through vacuum tight seals so that the steel may be simultaneously subject to the vacuum and the oxygen blow. Should it not be possible, due to system parameters, to maintain a vacuum on the order of one torr or below during lance operation, the melt may be subjected to the vacuum in the absence of the lance for a short period after lancing, since the lancing operating will superheat the melt to a temperature above the desired teeming temperature. 
         [0061]    The melt is subjected to the action of a purging gas during treatment, preferably at all times the tank is sealed, though the purging gas may be interrupted if, at any time, an operator observing the boil through the sight port  140  decides the boil is momentarily too heavy. The purging gas system is indicated best in  FIG. 11 . A stationary purging gas supply line  159  is connected upstream of the direction of gas flow with a suitable source of gas which is inert with respect to the metal undergoing treatment, such as argon. Stationary gas line  159  connects by a conventional slide coupling, not shown, to a feeder line carried by the ladle, indicated generally at  160 , the connection of the feeder line  160  to the supply line  159  occurring as the ladle is lowered onto the ladle saddles  138  as a crane drops the ladle in place following the removal of the ladle from the LMF car and into the vacuum treatment station  126 . Feeder line  160  branches to form a first plug feeder  161  and a second plug feeder  162  whose exit ends are embedded in refractory purging plugs  163  and  164 , respectively, located in the refractory bottom  169  of the ladle. A slide gate on the bottom of the ladle  86  is indicated at  165  which opens and closes a ladle teeming nozzle  166 . 
         [0062]    Following vacuum treatment at the vacuum treatment station  126  as shown in  FIG. 1B , and removal of the vacuum tank top  129 , see  FIG. 12 , the ladle  86  is lifted by crane, which grips ladle  86  at its trunnions  167 ,  168 , and lifts the ladle with its treated heat and places it on a teeming car indicated generally at  170 , see  FIGS. 1C ,  13  and  14 . Teeming car  170  includes a ladle positioning frame structure, indicated generally at  171 , which includes a pair of slightly V-shaped transverse cradle members  172 ,  173 , which are fast at their ends with longitudinal cradle anchor members  174 ,  175 . The longitudinal cradle anchor members  174 ,  175  are, in turn, fast with two main transverse struts  176 ,  177 . The anchor members form a rigid sub-frame which is fast with a vertically moveable base frame having longitudinal sides  178 ,  179 . 
         [0063]    The base frame is raised and lowered by jack means, only two of which,  180 ,  181 , are labeled. The jack means are secured to vertical posts  182 ,  183 ,  184  and  185 . A rigid wheeled frame formed by the longitudinal sides  178  and  179 , and cross members  186 ,  187  receive the ladle in the position shown at the right side of  FIG. 1C , the wheeled frame riding on track  190 . The ladle  86  will have been crane lifted from the vacuum treatment station on to the wheeled frame of the teeming car  170 . Lateral movement of the frame with respect to the track  190  is attained by operation of screw jacks, two of which are indicated at  188  and  189 . 
         [0064]    From the foregoing it will be seen that the teeming car, and a teem ready ladle  86  carried by it, can be moved in six directions to precisely align ladle teeming nozzle  166  with the flared end  195  of pouring trumpet  199 . Thus the ladle teeming nozzle  166  on the bottom of the ladle can be positioned exactly above the upper flared end  195  of the pouring trumpet as seen in  FIG. 2C  by virtue of the six directions of movement of the teeming car carriage. As soon as the ladle is lifted from the LMF car, the LMF car returns to a location just downstream from the vacuum treatment station  126  preparatory to receiving the next vacuum treated ladle. 
         [0065]    Teeming car  170  moves downstream to the teeming station, which includes a teeming pit area indicated generally in abbreviated form at  192  in  FIGS. 1C and 2C . Teeming pit  192  will contain as many sizes of ingot molds as the steel making facility is designed to provide. In this instance a first cluster of three molds is indicated generally at  193  and a second cluster at  194 . 
         [0066]    First ingot bottom pouring means includes a primary receptacle or mold, here ingot mold  196 , which rests on mold stool  197 . Stool  197  in turn rests on runner base  198 . The central bore of pouring trumpet  199  connects with an aligned vertical hole in the mold stool  197 , which hole connects to horizontal runner  202  which in turn communicates with an ingot entry hole  200  in mold stool  197  to thereby enable the interior of ingot mold  196  to be filled from the bottom up. It will be understood that the pouring trumpet  199 , the mold stool  197 , and the runner base  198  are formed of strong pressure resistant ceramic material, and are discarded after each use. Ingot mold  196  may have flux material placed in its bottom prior to pouring for the purpose of lubricating the mold walls to facilitate mold stripping. A removable and reinstallable hot top is indicated at  201 . 
         [0067]    A solidified vacuum degassed ingot  205  is shown in  FIG. 2C  in transit by crane to the mold stripping area shown in  FIGS. 1C and 15 . In the expanded view of  FIG. 15  the stripped ingot  205  is shown laying on its side with its associated ingot mold  196  also laying on its side. 
         [0068]    A crane carrying a ladle with several tons of carryover steel and slag is shown poised above the mold stripping area where, after having teemed the heat into ingot mold  196 , it is preparing to teem the few remaining tons of steel in the ladle into the small pyramid mold  207 , and the slag into the slag dumping area  206 , either by using the ladle slide gate or tipping the ladle while resting on its side on the ground using hook eye  208  of  FIG. 10  as a raising point. Following solidification in pyramid mold  207  the individual pyramid ingots, here six in number if all individual molds are filled, will be crane lifted onto transfer car  209  for transfer by rail  13  to the scrap house  12 . 
         [0069]    In like manner, the still hot ingot  205  will be placed on the transfer car  209  and conveyed to a heating furnace to heat the hot ingot to deformation temperature in the forge department preparatory to going to the forge press. 
         [0070]    Referring now to  FIGS. 1C ,  2 C and  15 , a stripped ingot  205 , which has cooled to room temperature in the mold stripping area, has its hot top sawn off and the outside oxidized surface removed by grinding or machining to form a VAR electrode ingot in preparation for further processing at the vacuum arc remelt station shown in detail at the left end of  FIG. 2C . Thereafter an attachment stub  210  is welded to the smooth cut off end, thereby forming a vacuum arc remelt electrode  211 . A copper crucible  212  is placed into the water jacket tank portion  218  of a vacuum arc remelt unit shown in  FIG. 2C . The exposed end of the VAR electrode is clamped to the lower end  213  of the VAR ram. The VAR ram is connected to a DC power source  214  with the ram sliding in a vacuum tight opening in the cover  215  of the VAR unit. When the DC current is turned on the bottom end of the VAR electrode  211  melts and forms a shallow pool  216  which rapidly solidifies from the bottom up as the cooling water  217  conveys away the heat from the molten pool of steel in the VAR crucible. The melting of the VAR electrode continues until the VAR electrode has been entirely consumed and a VAR ingot formed from it. At this time the VAR ingot indicated at  212  is further processed, usually by forging and required heat treatment. 
         [0071]    The use and operation of the invention is as follows. 
         [0072]    It will be assumed that a first heat of steel is to be made at the start of a campaign. (It will be understood that the word campaign is used in the sense it is generally understood in the steel industry, that is, the number of heats which can be made in an arc furnace before relining of the furnace is required.) It will also be assumed that a vacuum oxygen decarburized vacuum arc remelt product has been ordered by a customer. Further, it will be assumed that a vacuum oxygen decarburized vacuum arc remelted ingot of about 75 tons is the required end product of the melt shop portion of a full production sequence; that is, melting followed by subsequent processing which concludes in an ingot ready for the next phase of the steel making process, usually forging. 
         [0073]    The invention will be applicable to virtually any size commercial steel making process. For purposes of description, and solely by way of example, it will be assumed that the capacity of the arc furnace will be about 75 to 115 tons. For specific descriptive purposes a heat size of on the order of about 75 tons will adequately describe the invention. 
         [0074]    Referring first to  FIG. 1A , a first scrap charging bucket  21  which sits on scrap car  15  which runs on rails  17  has scrap  12  loaded into it by any suitable conventional means, such as a temporary magnet on a scrap crane. While bucket  21  is being loaded, arc furnace cover  35  of arc furnace  30  will be swung to the dotted position of  FIG. 1A . As soon as cover  35  is swung about its pivot  36  into the above described open position, the arc furnace bowl  31 , shown best in  FIG. 2A , will be open to receive scrap. At this time scrap crane  63 ,  FIG. 2A , lifts first scrap charging bucket  21  with the crane hook  64  hooked into lifting bracket  25  of bail  23 , which bail is rotatably connected to bucket  21  at pivots  29 . The scrap crane lifts first charging bucket  21  to the elevated position shown in  FIG. 1A . When the bottom of bucket  21  is opened scrap  12  is charged into the bowl  31  of the arc furnace  30 . 
         [0075]    It will be understood that in the first charge of the arc furnace in a heat the scrap  12  will include small pieces such as flashings and bushelings so that the bottom refractories in the furnace bowl  31  will not be damaged from heavy piece such as hot tops in the dropped scrap charge. There will be a heel of molten steel in the furnace left over from the preceding heat, said heel comprising sufficient tons of hot metal to, firstly envelop the scrap charge including large pieces and, secondly, to cushion the impact of large pieces of solid scrap on the refractory bottom of the furnace. The large pieces will have been transported back to the scrap house by the scrap rail system  13 , which rail system includes transfer car  209 , from completed downstream steps of the process. The solid pieces will include large cut off hot tops following solidification of the ingots in both VAR and non-VAR heats and small ingots from pyramid molds  207 . 
         [0076]    After the first charge of scrap  12  from first charging bucket  21  is charged into the open bowl  31  of the furnace the scrap crane will move from its elevated  FIG. 2A  position upstream to engage the lifting bracket  24  on the second charging bucket  20  which runs on rails  16 . 
         [0077]    Immediately after the second charging bucket  20  is emptied into the furnace the arc furnace cover  35  will move to the arc-operative position shown by the solid lines of  FIG. 1A  and an arc struck between the furnace electrodes  45 ,  46  and  47  and the metal in the furnace bowl. In the arc operating position, the stationary intake elbow  58  of the arc furnace ducting system  55  will be aligned with, though spaced from, the off take fume elbow  56  from the top of cover  35  as best seen in  FIGS. 1A and 3 . From  FIG. 1A  it will be seen that the slightly curved, discharge end flange  57  of fume off take elbow  56  will be directly aligned with the flat intake circular flange  59  of the stationary intake elbow  58  of the ducting system  55 . Powerful blowers, not shown, in the ducting system  55  will ensure that all the fumes in the arc furnace  30 , including chemical reaction fumes in the bowl  31  and any inward seepage from around the cover  35  and bowl  31 , will be directed into the ducting system  55  so the melt shop environment will not be contaminated by furnace fumes. Indeed, a slight pressure drop will occur within the furnace. 
         [0078]    As soon as the scrap from first charging bucket  21  is melted, the arcs are terminated, and then the electrodes are elevated to the clearance position shown in phantom in  FIG. 3  and the cover  35  swung out to its open position shown in  FIG. 1A . While the cover is being swung to the open position scrap crane  63  will lift the second scrap bucket  20  from its position on scrap car  14  in  FIG. 1A  to the charging position of  FIG. 2A , and then the scrap in scrap bucket  20  will be charged on top of the molten metal in the furnace. Thereafter the arc furnace cover  35  will be swung from the charging, phantom line position of  FIG. 1A  to the solid line, closed position of  FIG. 1A , the electrodes  45 ,  46  and  47  lowered to the operating position shown in solid lines in  FIG. 3 , and the arcs and ducting system  55  restarted. 
         [0079]    Both before and after charging from second charging bucket  20  occurs, samples will be taken from sampling device  50 , and also temperature. In this phase of processing, carbon and slag forming materials, particularly lime, will be added along with desired alloys depending on the values reported from samples. Further, oxygen and carbon will be added to the melt in the furnace by the carbon and oxygen injection system  53 . 
         [0080]    During all the above described operations a spare scrap charge bucket  26  will be loaded and waiting for transference to an open scrap car and thence to the furnace should the need arise. 
         [0081]    Referring now to  FIG. 1A  and, particularly,  FIG. 2A , a tapping ladle car  70 , which rides on tracks  71 , and carries an empty, unheated tapping ladle  72 , which includes trunnions  73 , is there shown. The ladle  72  is positioned beneath the furnace tap hole  75 , which tap hole is controlled by the furnace slide gate  84 . To tap the melt in the furnace into the tapping ladle  72 , the furnace rocker piston  83 ,  FIG. 2A , is actuated to tilt the furnace  30  from the arc operative position of  FIG. 5C  to the tapping position of  FIG. 5A  via rack and pinion  32 ,  33 , which tapping position is about 15° counterclockwise from the operating position of  FIG. 5C . After tapping the furnace  30  may be tilted clockwise to the position of  FIG. 5B  and the furnace slag removed through the furnace slag off door  52 . Since the slide gate permits nearly all the molten metal to be tapped (if desired) there will be little metal lost at slag off though, as stated above, preferably at least about 5-15 tons of metal are left in the furnace to form a heel. In any event the great bulk of the weight of the steel which will eventually be teemed is formed in the arc furnace. 
         [0082]    Tapping ladle  72 , prior to tapping, is heated by a preheat lance  76  so that the tapped metal from the furnace melt will not be unduly cooled when it contacts the tapping ladle. The increased wall temperature of the tapping ladle  72  is prolonged by a preheat shield indicated generally at  77  on the top of the ladle. The preheat shield is formed from a backing plate  78  to which a high heat resistant refractory insulation layer  79  is attached. The preheat shield  77  is raised and lowered as required by the hook  80  of a crane, hook  80  engaging shield bracket  81 . The preheat shield  77  is placed over a tapping ladle  72  for the maximum of time that the tapping ladle is required to wait for tap to begin. As a consequence the tapping ladle  72  will cool only minimally during its wait time before tapping begins. In a tapped heat size of about 75 tons approximately 1½ tons of lime, and sufficient pounds of alloys to bring the alloy content up to about 60% of the final required alloy content in many heats, will be made from the alloy feed assembly  82  directly into the tapping ladle  72 . 
         [0083]    After the heat in arc furnace  30  has been tapped into tapping ladle  82 , tapping ladle car  70  with the tapped melt is moved downstream to its terminus shown at the right side of  FIG. 2B . At this point the filled ladle, now indicated at  86 , will be lifted by crane  85  from the tapping car  70  onto a ladle metallurgical furnace (or LMF) car  87 . 
         [0084]    The LMF car  87  will be preheated by a preheat lance  89  shown in the upstream position of LMF car  87  in  FIG. 1B . Slag will be added through the slag chute  65  which is also located in the LMF upstream position of  FIG. 1B . 
         [0085]    While necessary conditioning will be taking place at the LMF upstream position of  FIG. 1B , the LMF will be prepared for LMF processing. The LMF electrodes  91 ,  92  and  93 , shown best in  FIG. 1B , are retracted a distance sufficient to permit ladle  86  and LMF car  87  to move into position in the LMF station under the electrodes  91 ,  92  and  93 . 
         [0086]    LMF roof  90  is shown best in  FIGS. 8 and 9 . The electrodes  91 ,  92  and  93  receive from power source  94  power through leads  95 ,  96 , and  97  shown best in  FIG. 1B . The electrodes snugly but movably reciprocate in the openings  98  in LMF center plate  99 . Both vertical and horizontal portions of the roof  90  are water cooled as shown best in  FIG. 9 . The lower structural portion of roof  90  terminates in a circular bottom flange  116  which mates with, and rests upon, a circular upper flange  117  on ladle  86 . A large volume of fumes are generated in the space between the ladle  86  and the LMF roof  90  and these fumes will be conducted by a path indicated by the arrows in  FIGS. 8 and 9  to the off take ducting of the system which connects into the bag house  115  shown in  FIG. 1A . A flapper is indicated a  100  in  FIG. 2B  which will enable temperature and chemical analyses to be made of the heat in ladle  86  at one or more times in the processing at the LMF station. 
         [0087]    Chemical additions, temperature and sampling systems are shown best in  FIGS. 6 ,  7 ,  8  and  9 . 
         [0088]    In  FIG. 6  an oxygen lance for the sub-surface addition of oxygen in the melt is indicated at  107 , which Figure shows the lance inoperative position in solid lines and in the retracted, or in operative, position in phantom lines. 
         [0089]    In  FIG. 7  temperature or, alternatively, a sampling system indicated generally at  124 , is shown in operative position in solid lines, and in retracted position in phantom lines. 
         [0090]    In  FIG. 8  the alloy wire addition system  108  will be seen to include, in this instance, two alloy feed wires  110  and  111  which are moved into the alloy wire feed funnel  112  by wire drive rollers  109 . The elongated spigot of the feed wire funnel  112  directs an alloy feed wire, here wire  110 , through wire feed tube  113  toward the melt in ladle  86 . A flapper valve in cover  90  (not shown) will open to enable the wire feed tube  113  to pass through opening  114  in cover  90 . 
         [0091]    Solid alloy materials in particulate form will be made by the bulk alloy chute system indicated generally at  101  in  FIG. 9 . Collecting chute  102  is a feed conduit from one or more overhead alloy hoppers. Collecting chute  102  empties into inclined chute  103  which in turn passes through inclined chute opening  104  in cover  90  whereby bulk alloys will be charged directly onto the melt. An alloy chute opening seal plate is indicated at  105 , which plate can be sealed by any suitable means to cut off communication between the space beneath the cover  90  and the bulk alloy chute system  101  so that processing can occur without significant fume diversion into the bulk alloy chute system  101  when seal plate  105  is opened to admit alloys to the melt. 
         [0092]    The cover  90  has a roof water cooling system indicated at  119 . A wire feed slide plate system is indicated generally at  120 , the slide plate system having a flap plate  121  under the control of a flap plate control system  122  which, when opened, permits the wire feed take  113  to enter the cover  90  so that the exit end of the wire feed tube  113  can be brought close to the surface of the melt to ensure contact of the alloy wire, which may be aluminum for example, with the melt. 
         [0093]    After alloy additions have been made to the LMF and the temperature of the melt brought to a desired level, which will, for example, be on the order of about 3000° F., the cover  90  and electrodes  91 ,  92  and  93  will be elevated so that LMF car  87  and ladle  86  carried by it will be moved to the downstream terminus position represented by stop  123  in  FIG. 2B  which is just next to the vacuum treatment station indicated generally at  126 . The vacuum treatment station includes a vacuum tank base  127  and a vacuum tank cover assembly indicated generally at  128 . The cover assembly  128  includes a tank top  129  which is movable in the vertical direction by tank top lift jacks  131  as represented by the vertical arrow in  FIG. 2B . Tank top  129  and its associated top lift jacks  131  are carried by a wheeled gantry top support indicated generally at  130  shown in greater detail in  FIG. 12 . The gantry top support includes a gantry platform  132 , see  FIG. 12 , having wheels  133 ,  134  which roll on gantry tracks  134 ,  135  best shown in  FIG. 12 . One of two oppositely positioned ladle saddles are indicated generally at  138  in  FIG. 12  which Figure shows the vacuum tank indicated generally at  125  in an open, empty, downstream condition. Ladle projections are indicated at  139 , see  FIG. 2B , on opposite sides of ladle  137 , the ladle projections being arranged to rest upon the ladle saddles  138  while ladle  137  is in the vacuum treatment station phase of the process. A vacuum tank sight port is indicated at  140 , see  FIGS. 1B and 10 , which penetrates the tank top  129  at a position which permits an operator to observe the intensity of the CO boil in ladle  137 , see  FIG. 10 . An alloy and charge material system is indicated at  141  and a wire feed system at  142  in  FIG. 1B , which system  142  may be similar to the wire addition system  108  of  FIGS. 1B ,  8  and  9 . A temperature and sampling port is indicated generally at  143  in  FIG. 1B . A central port cover plate is indicated at  144 , which cover plate will be in very tight sealed engagement with the tank top  129  during low vacuum operation. In this context low vacuum operation is considered to be an absolute pressure of less than 1 ton during a significant portion of the vacuum degassing portion of the cycle. Tank top  129  has a bottom flange  145  at its lower edge, which bottom flange is smoothly machined to mate with a similarly machined top flange  146  which surrounds the upper edge of vacuum tank base  127 . An O-ring seal  147  between smooth fitting flanges  145  and  146  will enable the vacuum tank  125  to routinely establish an absolute pressure of less than 1 ton on a continuous operating basis. The very low absolute vacuum will be preferably generated by a multistage steam jet ejector system which connects to vacuum tank  125  through tank atmosphere off take duct  149 . 
         [0094]    Ladle  137  is completely contained within the vacuum tank  125 , as seen in  FIG. 10 , thereby exposing the entire periphery of the ladle, as well as the surface of the heat to the vacuum, and, in addition, is elevated a substantial distance above the bottom of the tank by a structural base indicated generally at  151 . The height of the base is so selected that if a breakout occurs during treatment of a maximum heat size, the ladle will not be welded to the bottom of the tank and can thus be lifted up and out of the way while the tank bottom is repaired. 
         [0095]    Should the steel maker wish to make a vacuum oxygen decarburized heat of steel, either VAR or non-VAR quality, the tank top  129  is modified to receive an oxygen lance  153 . The lance  153  enters the tank  125  through a port which is opened when cover plate  144  is removed. The lance passes through a slide structure  154  with a tight fit so that the steam jet ejector system will be able to maintain a sub-atmospheric pressure in the system, thus presenting entry of ambient air into the tank enclosure in an amount sufficient to counteract to any appreciable degree contact of the melt with ambient atmosphere. 
         [0096]    An auxiliary heat shield is indicated at  156  for use particularly during processing which will require vacuum oxygen decarburization. A refractory cover plate  157  having a central opening  158  will contain the vigorous bail during vacuum oxidation decarburization cycles. It will be understood that cover plate  157  will usually not be needed in heats which do not call for vacuum oxygen decarburization. It will be noted that the metal shell of the ladle will contain weep holes  155  so that any moisture in the refractory will be pulled out of the refractory by the very low vacuum. The combination of the very smooth cover and tank flanges  145 ,  146  and the O-ring seal  147  and the exposure of the weep holes to the very low vacuum will ensure that no significant moisture which would contain deleterious hydrogen will be present in the system, thus making possible final hydrogen gas contents of less that 2.2 ppm, and often less than 1.0 ppm so that ultra clean steel suitable for airplanes and space application will always result. This is in contrast to systems in which the vacuum station includes only a cover which is placed on the upper rim of a ladle, thus making the ladle a portion of the vacuum tank enclosure. In such systems an absolute vacuum seal cannot be guaranteed between the cover and upper rim of the ladle due to the presence, often unnoticed, of particles on these surfaces which prevent a high vacuum seal from being formed. And, in addition, the possibility of moisture containing air remaining in the refractory due to the absence of weep holes which permit such moisture to enter the refractory is always present. 
         [0097]    Referring now to  FIG. 11 , it will be seen that a vigorous boil derived from gas purging is provided. A line  159  from a source of purging gas, preferably argon, connects at a junction indicated generally at  160  to a first plug feeder line  161  and a second plug feeder line  162  which terminate at first and second refractory purging plugs  163  and  164  respectively located in the bottom of the ladle. It will be understood that when the molten metal is stirred by the volumetric expansion of the purging gas, which will be on the order of about 1400 times due to the effect of the Charles and Boyles laws of gas expansion, a current will be sent up in the molten steel having an upward component above the purging plugs and a downward component on the opposite side of the ladle roughly indicated by the location of the teeming nozzle  166  in  FIG. 11 . As molten metal from locations remote from the surface reach the surface, the included deleterious gases in the molten metal such as hydrogen, oxygen and nitrogen, will be exposed to the very low pressure in the vacuum tank and will be discharged from the system through the off take duct  149 . 
         [0098]    The duration of the vacuum treatment will depend on the temperature of the metal at the start of treatment, the intensity of the boil and, during vacuum oxygen decarburization cycles, the quantity of oxygen added by lance  53  to the melt. 
         [0099]    Following treatment at the vacuum treatment station  126  and removal of vacuum tank cover assembly  128  to the tank open position of  FIG. 12 , the ladle  137  will be crane lifted out of the vacuum treatment station  126  and placed on the ladle positioning frame structure  171  carried by the teeming car, indicated generally at  170 , whose four wheels  191  ride on teeming track  190 . Teeming car  170  moves downstream, to the left as seen in  FIG. 1C , to the teeming pit station indicated generally at  192  preparatory to teeming into ingot molds  196 , see  FIG. 1C . 
         [0100]    With the ladle  137  on the ladle positioning frame structure  171 , the ladle is capable of movement in six directions in order to precisely position the ladle teeming nozzle  166  over the upper open flared end  195  of pouring trumpet  199  which projects upwardly above the level of track  190  as follows. 
         [0101]    Teeming car  170  consists of a rigid base frame composed of two longitudinal side frames  178 ,  179  and two transverse cross members  186 ,  187 . Vertical jack posts  182 ,  183 ,  184  and  185  extend upwardly from the four junctions of the longitudinal side frames  178 ,  179  and the transverse cross members  186  and  187 . 
         [0102]    The ladle positioning frame structure  171  consists of two longitudinal cradle base members  174 ,  175  and two transverse base cradle members  176 ,  177 . The four sided ladle base so formed is moved upwardly and downwardly by jack means, two of which are indicated at  180 ,  181 , the jack means being mounted on the vertical jack posts  182 ,  183 ,  184  and  185 . Two slightly V-shaped transverse cradle members  172 ,  173  extend between longitudinal cradle base members  174 ,  175 . The slightly V-shaped transverse cradle members  172 ,  173  are contoured to matingly receive the ladle projections  139  (not shown in  FIGS. 13 and 14 ) so that ladle  137  is held stationary with the ladle base  174 ,  175 ,  176  and  177 . Horizontal transverse positioning jack means  188  and  189  enable the cradle base  174 ,  175 ,  176  and  177  to be moved transversely with respect to the track  190 . 
         [0103]    Thus, by actuation of vertical jack means  180 ,  181  and transverse jack means  188  and  189 , together with the movement of the teeming car  170  via the wheels  191  along track  190 , the ladle pouring nozzle can be moved in six directions to precisely position the nozzle  166  over the pouring trumpet  199 . 
         [0104]    The teeming pit is shown best in  FIGS. 1C and 2C . 
         [0105]    Ingot mold  196  rests on mold stool  197  which in turn rests on runner base  198 . The channel in pouring trumpet  199  connects with runner base entry hole  203 , which in turn connects with runner  202  in runner base  198 , which in turn connects with ingot entry hole  200  in the mold base  197 . A hot top is indicated at  201 . A suitable mold coating material may be present in the ingot mold prior to teeming for the purpose of coating the inside surface of the ingot mold. 
         [0106]    Following teeming, the ladle  137 , which may have three to five tons of hot metal and about three tons of slag, will be crane lifted to the mold stripping area  204 , see  FIG. 1C , where the metal will be poured into pyramid mold  207  and the slag dumped into the deslagging area  206 . The empty ladle will then be crane lifted back to a preheat area adjacent the arc furnace  30  where it will be readied for a subsequent furnace tap. The teeming car  170  will be returned upstream to its starting location just downstream from the vacuum treatment station  126  where it will await the next ladle to be crane lifted out of the vacuum treatment station  126 . 
         [0107]    When the pigs in pyramid mold  207  solidify they will be crane lifted to transfer car  209  where they will be returned via scrap rail system  13  to the scrap house  12 . 
         [0108]    After ingot  205  has solidified in ingot mold  196 , the ingot and its mold are transferred by crane to mold stripping area  204  where the mold and ingot are separated as seen best in  FIG. 15 . The hot top portion of the ingot remains on the ingot if the ingot is slated for conventional processing. The ingot is then loaded onto transfer car  209  and sent to the forging area where it will go initially to an annealing furnace. 
         [0109]    If the ingot in the mold stripping station  204  is intended for vacuum arc remelt treatment, it is processed as follows. 
         [0110]    From the stripping station  204  the ingot is crane lifted as seen in  FIG. 2C  to a cooling and sawing station  221  where the ingot is cooled to room temperature and the hot top cut off. Thereafter the surface of the ingot is formed into a near constant diameter at forming station  222  by grinding or machining to form, in effect, a vacuum arc remelt electrode. 
         [0111]    An attachment stub  210  is welded to the smooth cutoff end of the VAR electrode  211 . A copper crucible  212  will be then placed into the water jacket tank portion  218  of the VAR unit. The exposed end of stub shaft  210  is clamped to the lower end of the VAR ram  213  by a conductive coupling. The VAR ram is connected to a DC power source  214 . The ram slides in a vacuum tight opening in the cover  215  of the VAR unit. After the cover  215  seals via seal  216  to tank portion  218  of the VAR unit, DC current will be conducted through the ram  213  and stub shaft  210  to strike an arc  217  to the bottom of the VAR crucible  212 . The DC arc will melt the end of the VAR electrode  211  and the resultant molten metal forms a pool  219  in the copper crucible  212 . The molten pool  219  is rapidly solidified from the bottom up as cooling water  220  surrounding the copper crucible  218  conveys away heat from the molten pool of steel  219  in crucible  218 . The melting process will continue until the VAR electrode  211  is completely consumed and a new VAR ingot has been created. 
         [0112]    After the VAR electrode  211  had been fully melted, the DC current is terminated, the vacuum is terminated, and the cover  215  removed to expose a finished VAR ingot  223 , shown partially completed in  FIG. 2C . The attachment stub  210  is then uncoupled from the ram  213  and re-machined for use in a future VAR cycle. The bottom of the crucible will be unbolted from the crucible sides and the crucible is crane lifted off the VAR ingot  223 . The completed VAR ingot is placed on transfer car  209  which will then move the ingot to the forging department. 
         [0113]    A typical cycle time for a heat size of approximately 75 tons commencing with swinging the arc furnace cover  35  to a first charge position through completion of remelt of the recharge scrap, completion of tapping and return of the arc furnace to level position ready for swinging the furnace to a first charge position, will be about 1 hour and 45 minutes as follows. 
         [0114]    It will be assumed that the tapping ladle has been preheated to approximately 2000° F. by preheat lance  76  prior to tapping and each charging bucket  20 ,  21  will be loaded with approximately 41½ tons of solid scrap. 
         [0000]    
       
         
               
               
             
               
               
               
             
           
               
                   
                   
               
               
                   
                 Approximate 
               
               
                   
                 Time 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 1. 
                 Swing arc furnace cover from level 
                  1 minute 
               
               
                   
                 position to charge position. 
               
               
                 2. 
                 Charge the arc furnace with scrap charge 
                  5 minutes 
               
               
                   
                 No. 1 while adding approximately 1½ 
               
               
                   
                 tons lime. 
               
               
                 3. 
                 Swing arc furnace cover to melt position 
                  1 minute 
               
               
                   
                 with off take from arc furnace cover 
               
               
                   
                 aligned with stationary off take system. 
               
               
                 4. 
                 Run arcs to melt charge from the first 
                 45 minutes 
               
               
                   
                 bucket; turn off arcs. 
               
               
                 5. 
                 Swing arc furnace cover to charge 
                  1 minute 
               
               
                   
                 position. 
               
               
                 6. 
                 Recharge arc furnace with scrap charge 
                  5 minutes 
               
               
                   
                 No. 2 while adding approximately 1½ 
               
               
                   
                 tons lime. 
               
               
                 7. 
                 Swing arc furnace to melt position with 
                  1 minute 
               
               
                   
                 off take system aligned. 
               
               
                 8. 
                 Melt recharge scrap. 
                 45 minutes 
               
               
                 9. 
                 Tap approximately 75 tons into tapping 
                  5 minutes 
               
               
                   
                 ladle at a temperature of approximately 
               
               
                   
                 3050° F. leaving a heel of about 5-7 tons. 
               
               
                 10. 
                 Return arc furnace and its cover to level 
                  1 minute 
               
               
                   
                 position. 
               
               
                   
               
             
          
         
       
     
         [0115]    Down stream processing of the melt from level, covered condition through crane lift from the vacuum treatment station will require less than about 1 hour and 45 minutes so there will be no possibility of back up due to slowness of downstream operations. For example, the time in the LMF will be only about 35 minutes, or less, and the time at the vacuum treatment station will be only about 30 minutes. 
         [0116]    The cycle time may approach or even slightly exceed two hours if 90 tons are to be teemed. The cycle time will however be less than directly proportional to the size of the heat due to arc furnace electrodes of up to 16 inches diameter and 75 to 90 MVA current. It will also be understood that the composition of the steel to be produced—from low alloy to high chromium stainless—will have insignificant impact on the cycle time. 
         [0117]    Although a preferred embodiment of the invention has been disclosed, it will be apparent that the scope of the invention is not confined to the foregoing description, but rather only to the scope of the hereafter appended claims when interpreted in light of the relevant prior art.

Technology Classification (CPC): 8