Abstract:
A solids feed means for a direct smelting plant is disclosed. The solids feed means includes 2 or more pairs of lances for injecting solid feed materials for a direct smelting process into a direct smelting vessel. The solids feed means also includes a main supply line and a pair of branch lines for supplying solid feed material to the lances of each pair of lances with the branch lines interconnecting the main supply line and the lances of the pair of lances. The lances are arranged around the vessel in pairs of diametrically opposed lances. At least one pair of lances is provided for injecting metalliferous feed material (such as iron-containing materials, particularly iron ore fines) and at least one of the other pairs of lances is provided for injecting solid carbonaceous material (such as coal) and optionally fluxes. The pairs of lances are arranged around the vessel so that adjacent lances are lances that are provided to inject different materials.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
   This application is a continuation of application Ser. No. 10/821,947 filed Apr. 12, 2004 now abandoned. 

   TECHNICAL FIELD 
   The present invention relates to a direct smelting plant and process for producing molten metal from a metalliferous feed material such as ores, partly reduced ores and metal-containing waste streams. 
   A known direct smelting process, which relies principally on a molten bath as a reaction medium, and is generally referred to as the HIsmelt process, is described in International Application PCT/AU96/00197 (WO 96/31627) in the name of the applicant. 
   The HIsmelt process as described in the International application in the context of producing molten iron includes:
         (a) forming a bath of molten iron and slag in a vessel;   (b) injecting into the bath:
           (i) a metalliferous feed material, typically iron oxides; and   (ii) a solid carbonaceous material, typically coal, which acts as a reductant of the iron oxides and a source of energy; and   
           (c) smelting metalliferous feed material to iron in the metal layer.       

   The term “smelting” is herein understood to mean thermal processing wherein chemical reactions that reduce metal oxides take place to produce molten metal. 
   The HIsmelt process also includes post-combusting reaction gases, such as CO and H 2  released from the bath, in the space above the bath with oxygen-containing gas and transferring the heat generated by the post-combustion to the bath to contribute to the thermal energy required to smelt the metalliferous feed materials. 
   The HIsmelt process also includes forming a transition zone above the nominal quiescent surface of the bath in which there is a favorable mass of ascending and thereafter descending droplets or splashes or streams of molten metal and/or slag which provide an effective medium to transfer to the bath the thermal energy generated by post-combusting reaction gases above the bath. 
   In the HIsmelt process the metalliferous feed material and solid carbonaceous material is injected into the molten bath through a number of lances/tuyeres which are inclined to the vertical so as to extend downwardly and inwardly through the side wall of the smelting vessel and into a lower region of the vessel so as to deliver at least part of the solids material into the metal layer in the bottom of the vessel. To promote the post-combustion of reaction gases in the upper part of the vessel, a blast of hot air, which may be oxygen enriched, is injected into an upper region of the vessel through a downwardly extending hot air injection lance. Offgases resulting from the post-combustion of reaction gases in the vessel are taken away from the upper part of the vessel through an offgas duct. The vessel includes refractory-lined water cooled panels in the side wall and the roof of the vessel, and water is circulated continuously through the panels in a continuous circuit. 
   The HIsmelt process enables large quantities of molten metal, such as molten iron, to be produced by direct smelting in a single compact vessel. 
   However, in order to achieve this it is necessary to supply large quantities of solid feed materials, such as iron-containing feed materials, carbonaceous material, and fluxes, to the solids injection lances. 
   The supply of solid feed materials must continue throughout a smelting campaign, which desirably is at least 12 months. 
   Moreover, it must be possible to vary the supply of solid feed materials during the course of a smelting campaign to accommodate different operating conditions, including unexpected perturbations in the process, at different stages of a smelting campaign. 
   The present invention provides an effective and reliable process and plant for supplying solid feed materials to solids injection lances during a HIsmelt smelting campaign. 
   DISCLOSURE OF THE INVENTION 
   The present invention provides a solids feed means for a direct smelting plant. 
   In one aspect of the invention the solids feed means includes 2 or more pairs of lances for injecting solid feed materials for a direct smelting process into a direct smelting vessel (such as a fixed vertically extending cylindrical vessel). The solids feed means also includes a main supply line and a pair of branch lines for supplying solid feed material to the lances of each pair of lances with the branch lines interconnecting the main supply line and the lances of the pair of lances. The lances are arranged around the vessel in pairs of diametrically opposed lances. At least one pair of lances is provided for injecting metalliferous feed material (such as iron-containing materials, particularly iron ore fines) and at least one of the other pairs of lances is provided for injecting solid carbonaceous material (such as coal) and optionally fluxes. The pairs of lances are arranged around the vessel so that adjacent lances are lances that are provided to inject different materials. 
   In another aspect of the invention the solids feed means includes solids injection lances arranged around and extending into the vessel and supply lines for supplying solid feed material to the lances. At least one lance is provided for injecting metalliferous feed material and at least one of the other lances is provided for injecting solid carbonaceous material. A lance supply line for at least one lance includes an upwardly extending section, and an inwardly and downwardly extending section that extends from an upper end of the upwardly extending section and is connected to an inlet of the lance and is coaxial with the lance. 
   According to a first aspect of the present invention there is provided a direct smelting plant for producing molten metal from a metalliferous feed material including: 
   (a) a fixed smelting vessel to hold a molten bath of metal and slag and a gas space above the bath; 
   (b) a solids feed means to supply solid feed material into the vessel, the solids feed means including two or more pairs of solids injection lances arranged around and extending into the vessel, and a main supply line and a pair of branch lines for supplying solid feed material to the lances of each pair of lances with the branch lines interconnecting the main supply line and the lances of the pair of lances, and with the lances of each pair of lances being diametrically opposed to each other, and with at least one pair of lances being provided for injecting metalliferous feed material and at least one of the other pairs of lances being provided for injecting solid carbonaceous material, and with the pairs of lances being arranged around the vessel so that adjacent lances are lances that are provided to inject different materials; 
   (c) a gas injection means extending downwardly into the vessel to inject an oxygen-containing gas into the gas space and/or the bath in the vessel; 
   (d) a gas delivery duct means extending from a gas supply location away from the vessel to a delivery location above the vessel for delivering the oxygen-containing gas into the gas injection means; 
   (e) an offgas duct means for facilitating flow of offgas from the vessel away from the vessel; 
   (f) a metal tapping means for tapping molten metal from the bath and transporting that molten metal away from the vessel; and 
   (g) a slag tapping means for tapping slag from the bath and transporting that slag away from the vessel. 
   Preferably the solids injection lances are arranged to extend downwardly and inwardly into the vessel through openings in a side wall of the vessel. 
   Preferably the lance openings in the side wall of the vessel are located at the same height of the vessel and are spaced at equal distances around the circumference of the vessel. 
   Preferably the branch lines of each pair of solids injection lances are substantially the same length. 
   Preferably the branch line for each lance includes an upwardly extending section, and an inwardly and downwardly extending section that extends from an upper end of the upwardly extending section and is connected to an inlet of the lance and is coaxial with the lance. 
   Preferably the upwardly extending section and the inwardly and downwardly extending section describe an acute angle. 
   Preferably the solids feed means is adapted to supply one or more of (a) pre-heated metalliferous feed material, (b) metalliferous feed material at ambient temperature, and (c) a blend of pre-heated and ambient temperature metalliferous feed material to the metalliferous feed material lances. 
   Preferably the solids feed means includes a hot metalliferous feed material injection system for supplying pre-heated metalliferous feed material to the main supply line or lines for the metalliferous feed material lances. 
   Preferably the hot metalliferous feed material injection system includes a hot metalliferous feed material transfer means that includes the main supply line or lines and a supply of a carrier gas, such as an inert gas, for transporting the hot metalliferous feed material from a pre-heater and/or pre-reduction unit to the metalliferous feed material lances. 
   Preferably the metalliferous feed material is iron ore fines. 
   Preferably the hot metalliferous feed material injection system is operable to pre-heat the iron ore fines so that the iron ore fines for injection into the vessel at a temperature in the range of 650-700° C., more preferably of the order of 680° C. 
   Preferably the plant further includes at least two work platforms for supporting plant operators at different heights of the vessel above ground level. 
   Preferably the metal tapping means and the slag tapping means are located so as to be accessible by plant operators on one of the platforms (hereinafter referred to as the “cast house platform”). 
   Preferably the solids injection lances are located so as to be accessible by workman on at least one other platform (hereinafter referred to as the “lance platform”) that is above the cast house platform. 
   The metal tapping means and the slag tapping means may be the same unit. 
   The metal tapping means and the slag tapping means may also be different units with a separate metal tap hole and a separate slag tap hole located at different heights of the vessel. 
   In situations in which the metal tapping means and the slag tapping means are different units, preferably the metal tapping means includes a metal flow forehearth projecting outwardly from the vessel for tapping molten metal continuously from the vessel. 
   With this arrangement, preferably the metal tapping means includes a metal tapping launder for receiving molten metal from the forehearth. 
   In addition, with this arrangement, preferably the slag tapping means includes a slag tapping launder for receiving molten slag from the bath. 
   Preferably the vessel is disposed about a central upright. 
   Preferably the vessel is a vertical cylindrical vessel and the plurality of solids injection lances are spaced circumferentially around the vessel. 
   Preferably the side wall of the vessel includes water-cooled panels. 
   Preferably the vessel includes a roof and the roof includes water-cooled panels. 
   Preferably the oxygen-containing gas is air or oxygen-enriched air. 
   According to the first aspect of the present invention there is also provided a direct smelting process that includes injecting solids feed materials into a direct smelting vessel containing a molten bath of metal and slag through 2 or more pairs of solids injection lances arranged around and extending into the vessel, and a main supply line and a pair of branch lines for supplying solid feed material to the lances of each pair of lances with the branch lines interconnecting the main supply line and the lances of the pair of lances, and with the lances of each pair of lances being diametrically opposed to each other, and with at least one pair of lances injecting metalliferous feed material and at least one of the other pairs of lances injecting solid carbonaceous material and optionally fluxes, and with adjacent lances injecting different materials. 
   According to another aspect of the present invention there is provided a direct smelting plant for producing molten metal from a metalliferous feed material including: 
   (a) a fixed smelting vessel to hold a molten bath of metal and slag and a gas space above the bath; 
   (b) a solids feed means to supply solid feed material into the vessel, the solids feed means including solids injection lances arranged around and extending into the vessel, and supply lines for supplying solid feed material to the lances, and with at least one lance being provided for injecting metalliferous feed material and at least one of the other lances being provided for injecting solid carbonaceous material, and the lance supply line for at least one lance including an upwardly extending section, and an inwardly and downwardly extending section that extends from an upper end of the upwardly extending section and is connected to an inlet of the lance and is coaxial with the lance. 
   (c) a gas injection means extending downwardly into the vessel to inject an oxygen-containing gas into the gas space and/or the bath in the vessel; 
   (d) a gas delivery duct means extending from a gas supply location away from the vessel to a delivery location above the vessel for delivering the oxygen-containing gas into the gas injection means; 
   (e) an offgas duct means for facilitating flow of offgas from the vessel away from the vessel; 
   (f) a metal tapping means for tapping molten metal from the bath and transporting that molten metal away from the vessel; and 
   (g) a slag tapping means for tapping slag from the bath and transporting that slag away from the vessel. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention is described in more detail hereinafter with reference to the accompanying drawings, of which: 
       FIG. 1  is a vertical cross-section through a direct smelting vessel that forms part of one embodiment of a direct smelting plant in accordance with the present invention; 
       FIG. 2  is a side elevation of the vessel and the arrangement of platforms around the vessel and the equipment on the platforms that form a major part of the embodiment of the direct smelting plant; 
       FIG. 2   a  is an enlarged side elevation of the solids injection lance and hot ore supply lines indicated by the arrow “A” in  FIG. 2 ; 
       FIG. 3  is a side elevation of a lower part of the vessel and the arrangement of platforms around the vessel and the equipment on the platforms that form a major part of the embodiment of the direct smelting plant viewed from a location that is 90° from the location from which the vessel is viewed from in  FIG. 2 ; 
       FIG. 4  illustrates the layout of the cast house platform of the embodiment of the direct smelting plant; 
       FIG. 5  illustrates the layout of the end tap platform of the embodiment of the direct smelting plant; 
       FIG. 6  is a computer-generated top plan view of the embodiment of the direct smelting plant which illustrates the cast house platform and equipment on that platform and a section through the vessel at that height of the vessel and equipment above that platform and with equipment above that platform removed to clarify the view of the plant; and 
       FIG. 7  is a diagrammatic plan of the arrangement of solids injection lances around the vessel the supply lines for the lances. 
   

   DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
   The direct smelting plant shown in the Figures includes a direct smelting vessel that is suitable particularly for operation by the HIsmelt process as described in International patent application PCT/AU96/00197. The following description is in the context of smelting iron ore fines to produce molten iron in accordance with the HIsmelt process. 
   With reference initially to  FIG. 1 , the metallurgical vessel is denoted generally as  11  and has a hearth that includes a base  12  and sides  13  formed from refractory bricks, side walls  14  which form a generally cylindrical barrel extending upwardly from the sides  13  of the hearth and which include an upper barrel section and a lower barrel section supporting water-cooled panels (not shown), a roof  17  supporting water-cooled panels (not shown), an outlet  18  for offgases, a forehearth  19  for discharging molten metal continuously, and a tap-hole  21  for discharging molten slag during smelting. 
   In use of the vessel to smelt iron ore fines to produce molten iron in accordance with the HIsmelt process, the vessel  11  contains a molten bath of iron and slag which includes a layer  22  of molten metal and a layer  23  of molten slag on the metal layer  22 . The arrow marked by the numeral  24  indicates the position of the nominal quiescent surface of the metal layer  22  and the arrow marked by the numeral  25  indicates the position of the nominal quiescent surface of the slag layer  23 . The term “quiescent surface” is understood to mean the surface when there is no injection of gas and solids into the vessel. 
   As can best be seen in  FIGS. 2 and 3 , the vessel includes a series of platforms  79 ,  81 ,  83 ,  85  at different heights of the vessel above ground level  87 . The platforms enable installation and operation of vessel and other plant equipment described hereinafter around the compact vessel  11  in a way which separates the various operational functions of the equipment so as to minimize interference between the various operations and, accordingly, maximize operational safety. The heights of the platforms  79 ,  81 ,  83 ,  85  are selected to enable workman on the platforms to have convenient access to the plant equipment. In addition, the “footprints” of the platforms  79 ,  81 ,  83 ,  85  are selected to permit overhead crane access to selected areas of lower platforms and to provide overhead protection for work areas of the lower platforms. 
   As is discussed in further detail hereinafter, the platforms  79 ,  81  are solids injection lance platforms, the platform  83  is a cast house platform, and the platform  85  is an end tap platform. 
   As can best be seen in  FIG. 5 , the vessel  11  includes 2 access doors  39  in the sides  13  of the hearth for allowing access to the interior of the vessel  11  for re-lining or other maintenance work in the interior of the vessel. The access doors  39  are in the form of steel plates that are welded to the sides  13 . When access to the interior of the vessel is required, the plates are cut away from the side walls and replacement plates are welded in position after the work in the vessel has been completed. The access doors  39  are at the same height of the vessel  11 . The access doors  39  are spaced at least 90° apart around the circumference of the vessel. This spacing makes it possible for refractory wall demolition equipment to extend through the doors into the vessel and demolish a substantial part of the refractories of a refractory-lined side wall while the vessel is hot. The access doors  39  are sufficiently large to allow bob-cat  139  or similar equipment access to the interior of the vessel. 
   As can best be seen in  FIG. 1 , the vessel  11  is fitted with a gas injection lance  26  for delivering a hot air blast into an upper region of the vessel. The lance  26  extends downwardly through the roof  17  of the vessel  11  into the upper region of the vessel. In use, the lance  26  receives an oxygen-enriched hot air flow through a hot gas delivery duct  31  ( FIGS. 2 and 6 ) which extends from a hot gas supply station (not shown) located some distance away from the reduction vessel  11 . The hot gas supply station includes a series of hot gas stoves (not shown) and an oxygen plant (not shown) to enable an oxygen enriched air stream to be passed through the hot gas stoves and into the hot gas delivery duct  31  which extends to a connection with the gas injection lance  26  at a location above the vessel  11 . Alternatively oxygen may be added to the air stream after the air stream has been heated by the stoves. 
   With reference to the Figures generally, the vessel  11  is also fitted with 8 solids injection lances  27  extending downwardly and inwardly through openings (not shown) in the side walls  14  of the vessel and into the slag layer  23  for injecting iron ore fines, solid carbonaceous material, and fluxes entrained in an oxygen-deficient carrier gas into the metal layer  22 . 
   The lance openings in the side walls  14  of the vessel are located at the same height of the vessel  11  and are spaced at equal distances around the circumference of the vessel. The lances  27  are formed and are located in the lance openings so that their outlet ends  28  are above the surface of the metal layer  22  during operation of the process. This position of the lances  27  reduces the risk of damage through contact with molten metal and also makes it possible to cool the lances by forced internal water cooling without significant risk of water coming into contact with the molten metal in the vessel. 
   The lances  27  are in 2 groups of 4 lances, with the lances  27  in one group receiving hot iron ore fines supplied via a hot ore injection system and the lances  27  in the other group receiving coal and flux via a carbonaceous material/flux injection system during a smelting operation. The lances  27  in the 2 groups are arranged alternately around the circumference of the vessel. 
   The hot ore injection system includes a pre-heater (not shown) for heating the iron ore fines and a hot ore transfer system that includes a series of supply lines and a supply of carrier gas for transporting the hot ore fines in the supply lines and injecting the hot ore fines at a temperature of the order of 680° C. into the vessel. The general arrangement of the lances  27  and the supply lines immediately upstream of the lances  27  is shown diagrammatically in  FIG. 7 . 
   With reference to the Figures generally, the hot ore injection system includes a main hot ore supply line  75  ( FIGS. 2 to 5 ) and 2 branch lines  76  ( FIGS. 2 to 4 ) that are connected to diametrically opposed lances  27  and are arranged to supply hot ore to these lances  27  during a smelting operation. The hot ore injection system also includes another main hot ore supply line  33  ( FIGS. 2 and 5 ) and 2 branch lines  34  ( FIGS. 2 to 5 ) that are connected to the other pair of diametrically opposed lances  27  and are arranged to supply hot ore to these lances  27 . 
   As can be seen in  FIGS. 2 to 5 , the main supply line  75  runs on or close to ground level from a remote location (not shown) away from the vessel and under the end tap platform  85  to a location  75   a  in  FIGS. 2 and 3  and then vertically upwardly from this location through or adjacent the end tap platform  85  and the cast house platform  83  to a location  75   b  in  FIGS. 2 to 4  above the cast house platform  83 . The branch lines  76  initially extend horizontally in opposite directions from the main line  75  at the location  75   b  and then vertically upwardly at locations  76   a  ( FIGS. 2 and 3 ) to locations  76   b  ( FIGS. 2 to 4 ) and then inwardly and downwardly in short straight sections  76   c  to the inlets of lances  27 . 
   As can also be seen in  FIGS. 2 and 3 , the main supply line  33  runs on or close to ground level from a remote location (not shown) away from the vessel to a location  33   a  in  FIG. 5  and the line branches into the branch lines  34  at this location. These branch lines define a V-shape. The branch lines  34  extend on or close to ground level under the end tap platform  85  to locations  34   a  ( FIGS. 2 and 3 ) and then vertically upwardly from these locations through or adjacent the end tap platform  85  and the cast house platform  83  to the locations  34   b  ( FIG. 2 ) and then inwardly and downwardly in short straight sections  34   c  ( FIG. 2 , only one shown) to the inlets of lances  27 . 
   The above-described arrangement of the pairs of main and branch lines avoids interference between the lines in the confined space around the vessel. 
   The carbonaceous material/flux injection system includes similar main supply lines  39 ,  91  and branch supply lines  40 ,  92 , respectively for diametrically opposed pairs of the lances  27 . 
   The lances  27  are arranged to be removable from the vessel  11 . 
   The offgas outlet  18  of the vessel  11  is connected to an offgas duct  32  (shown in  FIGS. 2 ,  6  and  7 ) which transports the offgas away from the vessel  11  to a treatment station (not shown) where it is cleaned and passed through heat exchangers for preheating the materials fed to the vessel  11 . The HIsmelt process preferably operates with air or oxygen-enriched air and therefore generates substantial volumes of offgas and requires a relatively large diameter offgas duct  32 . As can best be seen in  FIG. 2 , the offgas duct includes a gently inclined first section  32   a  extending from the offgas outlet  18  of the vessel  11  and a vertically extending second section  32   b  that extends from the first section  32   a.    
   The hot gas delivery duct  31  and the offgas duct  32  extend away from the upper part of the vessel  11  to remote locations (not shown) and therefore occupy space in that region of the vessel and therefore have an impact on the positioning of plant equipment such as overhead cranes or other mobile handling equipment that is required for maintenance of the vessel and a cooling water circuit for the water-cooled panels in the side walls  14  and the roof  17  of the vessel  11 . 
   As is indicated above, the side walls  14  and the roof  17  of the vessel  11  support water-cooled panels (not shown) and the plant includes a cooling water circuit. The cooling water circuit supplies water to and removes heated water from the water-cooled panels and thereafter extracts heat from the heated water before returning the water to the water-cooled panels. 
   In a smelting operation in accordance with the HIsmelt process, ore fines and a suitable carrier gas and coal and a suitable carrier gas are injected into the molten bath through the lances  27 . The momentum of the solid materials and the carrier gases causes the solid materials to penetrate the metal layer  15 . The coal is devolatilised and thereby produces gas in the metal layer  15 . Carbon partially dissolves in the metal and partially remains as solid carbon. The ore fines are smelted to metal and the smelting reaction generates carbon monoxide. The gases transported into the metal layer and generated by devolatilisation and smelting reactions produce significant buoyancy uplift of molten metal, solid carbon and slag (drawn into the metal layer as a consequence of solid/gas/injection) from the metal layer  15  which generates upward movement of splashes, droplets and streams of molten metal and slag, and these splashes, droplets and streams entrain slag as they move through the slag layer. The buoyancy uplift of molten metal, solid carbon and slag causes substantial agitation of the slag layer  16 , with the result that the slag layer expands in volume. In addition, the upward movement of splashes, droplets and streams of molten metal and slag—caused by buoyancy uplift of molten metal, solid carbon and slag—extend into the space above the molten bath and forms a transition zone. Injection of the oxygen-containing gas via the lance  26  post-combusts reaction gases, such as carbon monoxide and hydrogen, in the upper part of the vessel. Offgases resulting from the post-combustion of reaction gases in the vessel are taken away from the upper part of the vessel through the offgas duct  32 . 
   Hot metal produced during a smelting operation is discharged from the vessel  11  through a metal tapping system that includes the forehearth  19  and a hot metal launder  41  connected to the forehearth. The outlet end of the hot metal launder  41  is positioned above a hot metal ladle station (not shown) so as to supply molten metal downwardly to ladles located at the station. 
   The plant includes an end metal tapping system for tapping molten metal from the vessel  11  at the end of a smelting operation out of the lower part of the vessel and transporting that molten metal away from the vessel  11 . The end metal tapping system includes a metal end tap hole  63  in the vessel and a launder  38  for transferring molten metal discharged from the vessel  11  via the tap hole to a containment metal pit  91  at ground level. Ideally this pit  91  is covered (not shown) from the elements to prevent direct contact between hot metal in the pit and water. The end metal tapping system also includes a metal tap hole  43  in the forehearth  19  and a launder  40  for transferring molten metal discharged from the forehearth  19  via the tap hole to the main hot metal launder  38 . An end tap drill  59  is also provided to open the tap holes  63 ,  43  to release metal from the vessel and the forehearth. 
   The plant includes a slag tapping system for tapping molten slag from the vessel  11  periodically from the lower part of the vessel and transporting that slag away from the vessel  11  during a smelting operation. The slag tapping system includes a slag notch  21  in the vessel  11  and a launder  44  with 2 end branches  80 ,  82  for transferring molten slag discharged from the vessel  11  via the slag notch  21  downwardly from the height of the cast house platform  83  into separate slag containment pits  93 ,  95  at ground level  87 . Two pits are provided so that one pit can be out of service and allowed to cool down prior to the slag being removed while the other pit is in service and receiving molten slag. A slag notch plug and pricker machine  61  is provided to open and seal the slag notch  21  to release slag from the vessel  11 . 
   The plant includes a slag tapping system for draining slag from the vessel  11  at the end of a smelting operation. The slag end tapping system includes a slag tap hole  46  in the vessel  11  and a main launder  70  and a branch launder  72  for transferring molten material discharged from the vessel  11  via the slag tap hole  46  to the containment pit  93 . A branch launder  95  connects the slag launder  70  to the hot metal launder  38 . The branch launder  95  is used to transfer molten metal that usually flows from the vessel when the tap hole  46  is first opened to the metal containment pit  91 . Prior to an end tap, the branch launder  72  is blocked so that molten material can only flow to the metal containment pit  91  via the branch launder  95 . Towards the end of the metal flow, the branch launder  95  is blocked and the branch launder  72  is unblocked so that flow of molten material is diverted to the slag pit  93 . A slag drain drill  68  is provided for opening the tap hole  46  to release slag from the vessel. A mud gun  66  is provided to close an open tap hole  46 . 
   As is indicated above, the vessel includes a series of platforms  79 ,  81 ,  83 ,  85  at different heights of the vessel above ground level  87 . The platforms enable installation and operation of vessel and other plant equipment. 
   The lowest platform, the end tap platform  85 , is positioned in relation to the vessel  11  at a height that is selected so that workman on the platform can have convenient access to the end metal tapping system (metal end tap hole  63 , launder  38 , metal tap hole  43 , launder  40 , and end tap drill  59 ), the slag end tapping system (slag tap hole  46 , launder  70 , branch launder  95 , slag drain drill  68 , mud gun  66 ), and the access doors  39 . Equipment such as the metal end tap drill, slag drain drill  68 , and mud gun  66  are mounted directly on the platform. The platform also includes 2 overhead crane access areas  55  that are essentially clear spaces on and from which equipment and materials can be lifted, for example to facilitate re-lining the interior of the vessel  11 . 
   The next highest platform, the cast house platform  83 , is positioned in relation to the vessel  11  at a height that is selected so that workman on the platform can have convenient access to the metal tapping system (forehearth  19  and hot metal launder  41 ) and the slag tapping system (slag notch  21 , launder  44 , and slag notch plug and pricker machine  61 ). The footprint of the platform  83  is selectively formed so that the platform does not extend into the space above the overhead access areas  55  of the end tap platform  85  so that there is clear overhead crane access to these areas  55 . The footprint of the platform  83  is also selectively formed so that the platform extends above the work areas in the immediate vicinity of the end metal and slag tapping systems and the access doors  39  on the end tap platform  85  to provide overhead protection for workman in these areas. 
   The next highest platforms, the lance platforms  79 ,  81 , are positioned in relation to the vessel  11  at heights that are selected so that workman on the platforms can have convenient access to the lances  27 . 
   The footprint of the platform  81  is shown in  FIG. 3 . The footprint of the platform  81  is selectively formed so that the platform does not extend into the space above the overhead access areas  55  of the end tap platform  85  so that there is clear overhead crane access to these areas  55 . The footprint is also selectively formed so that the platform extends above the work areas in the immediate vicinity of the metal and slag tapping systems to provide overhead protection for workman working in these areas. 
   In addition to the above-described plant equipment being arranged on a series of platforms  79 ,  81 ,  83 ,  85 , the equipment is also arranged on the platforms within a series of circumferentially and vertically extending zones that further enable installation and operation of all the above-described equipment around the compact vessel  11  in a way which separates the various operational functions of the equipment so as to minimize interference between the various operations and, accordingly, maximizing operational safety. 
   Specifically, the layout of the installation is divided into the following 3 functional zones that extend vertically and are spaced circumferentially around the vessel  11  and radiate outwardly of the central upright axis of the vessel. 
   Zone 1: General Access and Services 
   This zone, which extends approximately 180° around the circumference of the vessel  11  contains:
         The footprints of the overhead hot gas delivery duct  31  and the offgas duct  32 .   The access doors  39  in the vessel  11 .       

   Zone 2: Metal Tapping 
   This zone contains:—
         The metal tapping system (forehearth  19  and hot metal launder  41 ).   The end metal tapping system (metal end tap hole  63 , launder  38 , metal tap hole  43 , launder  40 , and end tap drill).       

   Zone 3: Slag Tapping 
   This zone contains:—
         The slag tapping system (slag notch  21 , launder  44 , and slag notch plug and pricker machine  61 ).   The slag end tapping system (slag tap hole  46 , launder  70 , branch launder  95 , slag drain drill  68 , and mud gun  66 ).       

   The plant also includes the zones, ie the space, above the above-described overhead crane access areas  55  that enable materials and equipment to be lifted onto and removed from the end tap platform. The overhead access is particularly important for efficient lifting of materials and equipment required for re-lining or other maintenance work on the interior of the vessel. 
   Many modifications may be made to the embodiment of the present invention described above without departing from the spirit and scope of the invention.