Patent Publication Number: US-8114337-B2

Title: Lance extraction

Description:
TECHNICAL FIELD 
     The present invention relates to the removal and replacement of solids injection lances from metallurgical vessels. The lances may be used for injecting gaseous and/or solids materials into the metallurgical vessels. In one particular application such lances may be used for injecting metallurgical feed material into the molten bath of a smelting vessel for producing molten metal, for example by a direct smelting process. 
     A known direct smelting process, which relies on a molten metal layer 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 comprises: 
     (a) forming a bath of molten iron and slag in a vessel; 
     (b) injecting into the bath; 
     
         
         
           
             (i) a metalliferous feed material, typically metal oxides; and 
             (ii) a solid carbonaceous material, typically coal, which acts as a reductant of the metal oxides and a source of energy; and
 
(c) smelting metalliferous feed material to metal 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 liquid metal. 
     The HIsmelt process also comprises 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 comprises forming a transition zone above the nominal quiescent surface of the bath in which there is a favourable 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 metal layer 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 the lower region of the vessel so as to deliver the solid material into the metal layer in the bottom of the vessel. The lances must withstand operating temperatures of the order of 1400° C. within the smelting vessel. The lances must accordingly have an internal forced cooling system to operate successfully in this harsh environment and must be capable of withstanding substantial local temperature variations. 
     U.S. Pat. No. 6,398,842 discloses one form of lance which is able to operate effectively under these conditions. In that construction the solid particulate material is passed through a central core tube which is fitted closely within an outer annular cooling jacket, the forward end of the core tube extending through and beyond the forward end of the cooling jacket into the metallurgical vessel. Australian Patent Application 2004906032 provides a modification in which the central core tube and the outer annular water jacket are held in spaced apart relationship and in which a purge gas can be passed between them. This construction better accommodates differential expansion movements between the central tube and the outer jacket and also prevents the front end of the lance from becoming clogged with slag. 
     The metallurgical vessel for performing the HIsmelt process presents unique problems in that the process operates continuously, and the vessel must be closed up as a pressure vessel for long periods, typically of the order of a year or more and then must be quickly relined in a short period of time as described in U.S. Pat. No. 6,565,798 in the name of the applicant. 
     Before refurbishment of the vessel can proceed it is necessary to extract all of the solids injection lances from the vessel and remove them to a safe location. Moreover, individual lances may need to be withdrawn for repair and/or replacement between major refurbishments of the vessel. The present invention provides a procedure for removing and replacing the solids lances while maintaining a temporary cooling water supply to the lances during this procedure, this enabling the lances to be withdrawn and replaced while the smelting vessel remains in a hot condition. 
     DISCLOSURE OF THE INVENTION 
     According to the invention there is provided a method of removing from a metallurgical vessel an internally water cooled injection lance to which gaseous and/or solids material is supplied through an injection supply line to an outer end of the lance and to which cooling water is normally supplied from a cooling water circuit through a water supply line connected between the cooling water circuit and the lance and returned to the cooling water circuit via a return line connected between the lance and the cooling water circuit, comprising the steps of: 
     connecting a first flexible hose between a pair of water supply line connection locations spaced along the water supply line and establishing a flow of cooling water through that hose to the lance which bypasses a segment of the water supply line between said water supply line connection locations, 
     connecting a second flexible hose between return line connection locations spaced along the return line to establish a return flow of water from the lance which bypasses a segment of the return line between the return line connection locations, 
     isolating at least a part of each of said segments of the delivery line and the return line from both the cooling water circuit and the lance, 
     disconnecting at least a portion of the isolated parts of the water supply line and the return line, 
     disconnecting at least a portion of the injection supply line, and 
     removing the lance from the vessel while maintaining the flow of cooling water through the lance via the flexible hoses. 
     Preferably at least a portion of the segments disconnected from the water supply and return lines are removed. 
     Preferably at least a portion of the injection supply line is removed and more preferably the delivery end of that line is disconnected and removed from the lance. 
     The lance may be a solids injection lance in which case the injection supply line may be a solids conveyor. 
     Alternatively, the lance may be for the purpose of injecting gaseous material into the vessel in which case the injection supply line may be a gas supply duct. 
     There may be ancillary water flow connections to the lance and/or the delivery end of the injection supply line and in this case the method may include the step of disconnecting one or more of those connections to permit withdrawal of the lance. In particular there may be connections for flow of cooling water to a lance mounting flange by which the lance is mounted on the vessel and this may be disconnected prior to withdrawal of the lance. 
     Alternatively, ancillary water flow connections extend between main sections of the water supply and return lines and form at least one sub-circuit for supply of cooling water to cooling circuits of the lance. Said sub-circuit may form a sub-assembly connected to the lance and is preferably a self-supporting sub-assembly. The main sections of the water supply and return lines may locate isolation valves which in use operate to isolate the at least one sub-circuit from the supply and return lines. The supply and return lines and the at least one sub-circuit may be adapted to receive and locate hoses on either side of the isolation valves whereby in use temporary cooling water by-passes the isolation valves and is supplied to the at least one sub-circuit. 
     There may also be a water flow connection for supply of water to a flange connecting the delivery end of the injection supply line to the upper end of the lance which may also need to be disconnected prior to withdrawal of the lance. 
     There may also be a purge gas connector for admission of purge gas into the lance for flow between a central core tube and an annular cooling jacket of the lance. In this case the purge gas connector may also need to be disconnected prior to removal of the lance. 
     The invention also includes replacing the lance by the steps of establishing a flow of cooling water to the replacement lance through said flexible hoses, inserting the lance into the vessel, reinstalling the isolated parts of the supply line and the return line and de-isolating those parts to establish a flow of cooling water through those parts of the supply and return lines, and disconnecting the flexible hoses. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In order that the invention may be more fully explained, an embodiment will be described in some detail with reference to the accompanying drawings in which: 
         FIG. 1  is a vertical cross section through a metallurgical vessel incorporating solids injection lances; 
         FIG. 2  is a longitudinal cross-section through one of the solids injection lances for injecting coal into the vessel; 
         FIG. 3  is a cross-section through a rear part of the lance shown in  FIG. 2 ; 
         FIG. 4  is a longitudinal cross-section through a lance for injecting hot ore material into the vessel; 
         FIG. 5  is a cross-section through a rear part of the lance shown in  FIG. 5 ; 
         FIG. 6  diagrammatically illustrates relevant components of the coal and hot-ore injection lances and the cooling water connections for those lances; 
         FIG. 7  illustrates the physical layout of the cooling water connections for one of the hot ore injection lances; 
         FIG. 8   a  illustrates a lance installed on a smelt reduction vessel and connected to a solids conveyor, temporary cooling water being supplied to the lance by a flexible hose; 
         FIG. 8   b  illustrates the lance of  FIG. 8   a  with the solids conveyor disconnected from the lance; and 
         FIG. 8   c  illustrates the lance of  FIG. 8   b  removed from the vessel whilst maintaining the supply of temporary cooling water. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       FIG. 1  illustrates a direct smelting vessel suitable for operation by the HIsmelt process as described in International Patent Application PCT/AU96/00197. 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 includes an upper barrel section  15  and a lower barrel section  16 ; a roof  17 ; an outlet  18  for off-gases; a forehearth  19  for discharging molten metal continuously; and a tap-hole  21  for discharging molten slag. The vessel is located on a strong foundation so as to be firmly fixed in position during operation of the HIsmelt process. The roof of the vessel is thus in a fixed location when the process is operational. 
     In use, the vessel 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. 
     The vessel is fitted with a downwardly extending hot air injection lance  26  for delivering a hot air blast into an upper region of the vessel and a series of solids injection lances  27  extending downwardly and inwardly through the side walls  14  and into the slag layer  23  for injecting iron ore, solid carbonaceous material, and fluxes entrained in an oxygen deficient carrier gas into the metal layer  22 . The position of the lances  27  is selected 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 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. 
     Lances  27  may be of two kinds, a first of which is employed to inject hot ore material and the other of which is employed to inject carbonaceous material such as coal. There may for example be eight solids injection lances  27  spaced circumferentially around the vessel and consisting of a series of four hot ore injection lances and four coal injection lances spaced between the hot ore injection lances. All of the lances may fit within outer housings of a common construction but the two kinds of lance have differing interior construction tubes because of the vastly different temperature of the hot ore and the coal being injected. The lances receive the solids materials from a series of solids conveyors, which typically are pneumatic conveyors and which typically have spools  30  connected to the outer ends of the lances. The spools of the hot ore conveyors may be water cooled and supplied with cooling water in the manner described below. 
     The construction of an injection lance for carbonaceous material, identified as  27   a , is illustrated in  FIGS. 2 to 3 . As shown in these figures lance  27   a  comprises a central core tube  31  through which to deliver the solids material and an annular cooling jacket  32  surrounding the central core tube  31  throughout a substantial part of its length. Central core tube  31  is formed of low carbon steel tubing  33  throughout most of its length but its forward end is fitted with a replaceable extension or nozzle tube  34  which projects as a nozzles from the forward end of the cooling jacket  32 . 
     Central core tube  31  is internally lined through to the forward end part  34  with a ceramic lining  37  formed by a series of cast ceramic tubes. The rear end of the central core tube  31  is connected through a coupling  38  to a coal delivery system through which particulate coal is delivered in a pressurised fluidising gas carrier, for example nitrogen. 
     Annular cooling jacket  32  comprises a long hollow annular structure  41  comprised of outer and inner tubes  42 ,  43  interconnected by a front end connector piece  44  and an elongate tubular structure  45  which is disposed within the hollow annular structure  41  so as to divide the interior of structure  41  into an inner elongate annular water flow passage  46  and an outer elongate annular water flow passage  47 . Elongate tubular structure  45  is formed by a long carbon steel tube  48  welded to a machined carbon steel forward end piece  49  which fits within the forward end connector  44  of the hollow tubular structure  41  to form an annular end flow passage  51  which interconnects the forward ends of the inner and outer water flow passages  46 ,  47 . The rear end of annular cooling jacket  32  is provided with a water inlet  52  through which a flow of cooling water can be directed into the inner annular water flow passage  46  and a water outlet  53  from which water is extracted from the outer annular passage  47  at the rear end of the lance. Accordingly in use of the lance cooling water flows forwardly down the lance through the inner annular water flow passage  46  then outwardly and back around the forward annular end passage  51  into the outer annular passage  47  through which it flows backwardly along the lance and out through outlet  53 . This ensures that the coolest water is in heat transfer relationship with the incoming solids material and enables effective cooling of both the solids material being injected through the central core of the lance as well as effective cooling on the forward end and outer surfaces of the lance. 
     The outer surfaces of the tube  42  are machined with a regular pattern of rectangular projecting bosses  54  each having an undercut or dove tail cross section so that the bosses are of outwardly diverging formation and serve as keying formations for solidification of slag on the outer surfaces of the lance. Solidification of slag onto the lance assists in minimising the temperature in the metal components of the lance. It has been found in use that slag freezing on the forward or tip end of the lance serves as a base for formation of an extended pipe of solid material serving as an extension of the lance which further protects exposure of the metal components of the lance to the severe operating conditions within the vessel. 
     The lance is mounted in the wall of the vessel  11  via a mounting structure  61  comprising a tubular part  60  extended about the cooling jacket and having a double walled construction so as to enclose an annular space  70  between these walls. The tubular part  60  fits within a tubular lance mounting bracket  62  welded to the shell of vessel  11  so as to project upwardly and outwardly from the vessel and provided at its upper end with an end flange  63 . Lance mounting structure  61  is connected to the rear end of the outer tube  42  of annular cooling jacket  32  via an annular ring  64  and it also includes an annular mounting flange  65  which can be clamped to the flange  63  at the end of mounting tube  62  via clamping bolts  66 . A split spacer ring  67  is fitted between the flanges  63 ,  65  to hold them apart when the clamping bolts  66  are tightened. The arrangement is such that the forward part of the outer sleeve  60  of structure  61  extend through to the inside of the vessel wall. 
     The tubular part  60  of mounting structure  61  is water cooled, cooling water being supplied to the interior space  70  through a water inlet  68  and return through a water outlet  69  at the rear end of the mounting sleeve. The interior space  70  may be partitioned to provide an extended cooling water flow passage within it. 
     A tubular housing  54  extending rearwardly from the mounting ring  64  of mounting structure  61  houses the rear end of the intermediate tube  48  of jacket  32  and the rear end of the core tube  31  of the lance. Housing  54  carries the cooling water inlet  52  and outlet  53  for the passage of cooling water to and from the lance cooling jacket  32 . A flexible annular connecting structure  55  connects the rear end of the intermediate tube  48  of the water jacket with the housing tube  54  so as to separate the inward and outward water flow passages within the housing and to also permit relative longitudinal movement between the inner and outer tubes and the intermediate tube of the water jacket due to differential thermal expansion and contraction in the components of the lance. 
     The rear end of tubular housing  54  provides a mounting for the rear end of the inner tube  43  of the annular cooling jacket. 
     Core tube  31  is held in spaced apart relationship within annular cooling jacket  32  by a series of spacer collars  56  projecting outwardly from the central core tube at longitudinally spaced locations along the core tube to engage the inner periphery of the inner tube of the annular cooling jacket so as to form an annular gas flow passage  57  between the central core tube and the annular cooling jacket. A purge gas inlet  58  is provided at the rear end of the lance for admission of a purge gas such as nitrogen to be admitted into the gas flow passage  57  to flow forwardly through the lance between the core tube and the annular cooling jacket to exit the lance at the forward end of the cooling jacket. 
     The central core tube is fitted with a bulbous projection  59  in the region of the forward end of the cooling jacket to provide a controlled nozzle opening between the core tube and the water jacket to control the purge gas flow rate. The spacer collars  56  are formed so as to leave circumferentially spaced gaps between the outer peripheries and the inner periphery of the cooling jacket to allow for free flow of purge gas through the annular purge gas flow passage  57 . One of the end collars  56  is located closely adjacent the bulbous projection  86  so as to provide accurate location of that projection within the forward end of the outer cooling jacket so as to create the controlled annular gap for the purge gas exit nozzle. The flow of purge gas is maintained to ensure that slag can not penetrate the forward end of the nozzle between the core tube and the outer water jacket. If slag were to penetrate the lance in this region it would immediately freeze because of the water cooled outer jacket and the cold purge gas. 
     During operation of the lances slag will accumulate on the outer surfaces of the lance and the inner surface of the vessel. On shutdown the slag will solidify tending to bond the lance to the vessel. However with the illustrated mounting arrangement this bond can readily be broken to facilitate withdrawal of the lance. This can be achieved by loosening the mounting bolts  67  sufficiently to enable withdrawal of the split spacer ring  66 . This then permits limited inward movement of the lance mounting sleeve within the mounting tube  62  so that the forward end of the mounting sleeve is moved inwardly from the wall of the vessel to break any slag accretions. This then allows the lance along with the slag that has solidified on the outer tube  42  to be readily withdrawn through the enlarged opening provided for the tubular mounting  60 . 
     The hot ore injection lances may be of generally similar construction to the coal injection lances. However, as shown in  FIGS. 4 and 5 , the hot ore lance  27   b  has an inner core tube formed as a thick walled spun cast tube  31   b  with no liner. The tube  31   b  must be made in sections which are joined by split joining sleeves  88 . Adjacent tubes can be aligned and connected through the joining sleeves by stitch welding. The forward end of the core tube  31   b  is provided with a projection  59   b  to set the size of the purge gas outlet nozzle. Because of the thicker core nozzle tube in the hot ore injection lance this projection is much smaller than the more bulbous projection of the coal delivery lance. 
     In a further modification, the hot ore injection lance is provided with a water cooled flange  89  to stop overheating of the housing tube  51   b . This flange is sandwiched between the water cooled end flange of the lance housing and the flange on the end of the ore injection system which may also be water cooled. 
     The inner core tube of the hot ore injection lance is held in spaced apart relationship within the cooling jacket by a series of spacer collars projecting outwardly from the central core tube in the same fashion as in the coal lance construction. As in the coal lance, the space between the inner core tube and the water jacket provides an annular passage for flow of purge gas which exits the lace at the forward end of the cooling jacket. 
     The outer mountings for the two kinds of injection lance are identical so that both kinds of injection lances can be inserted into a common design housing. 
     The solids injection lances  27   a  and  27   b  can be removed and replaced while maintaining a temporary cooling water supply to the lances during this procedure. In essence the procedure requires that the lance be isolated from a main cooling water supply circuit. The isolation points are bypassed by flexible hoses that maintain the supply of cooling water to the lance. Once the isolation points are bypassed a part of the cooling water supply line is disconnected and/or removed. This breaks the physical connection between the lance and the cooling water supply circuit and allows the lance to be removed. The flexible hoses remain in place during extraction of the lance so as to maintain cooling water supply through this procedure. It is therefore possible to remove and replace a lance whilst the vessel contains molten material. 
     As shown in  FIG. 6  the cooling water inlets  52  and outlets  53  for the lances  27   a  and  27   b  are connected to a main cooling water circuit via supply lines  71  and return lines  72 . The supply lines  71  are provided with spaced pairs of connectors  80  and by pass valves  73  and return lines  72  are provided with similar pairs of spaced connectors  81  and bypass valves  74 . A flexible hose  75  can be connected between the pair of connectors  80  and another flexible hose  76  connected between the pair of connectors  81  to establish supply and return flows of cooling water which bypass segments of the main supply and return lines between the connectors  80  and  81 . Between the pair of connectors  80  the supply line  71  includes a flexible coupling  77  disposed between a pair of isolation valves  78 . Similarly return line  72  includes a flexible coupling  79  disposed between a pair of isolation valves  82 . 
     The water cooled mounting sleeves  70  for the lances  27   a ,  27   b  are provided with cooling water through ancillary supply and return lines  83 ,  84 . Further ancillary supply and return lines  85 ,  85   a    86  and  86   a  provide for flow of cooling water through the spool  30  of the hot ore delivery conveyer and through flanges connecting that spool to the rear end of lance  27   b . Auxiliary lines  86 ,  86   a  incorporate two cooling water isolation valves  87 . 
     The ancillary supply and return lines extend between sections of the primary supply and return lines and form one or more sub-circuit for supply of cooling water to individual cooling circuits or water cooled elements within the lance as indicated by the pipework shown in dotted outline in  FIG. 7 . The sub-circuits form at least one sub-assembly of ancillary water flow connections extending from the lance. The sub-circuits may be self-supporting. The sub-circuits are isolated by operation of isolation valves  78  &amp;  82  on the main supply and return lines and are adapted to receive cooling water from hoses  75 ,  76  connected to by-pass valves  73 ,  74 . By forming at least one sub-assembly the sub-circuits can be retained on the lance as the lance is installed or extracted from the vessel. This enables the supply of cooling water to be maintained to the lance during installation or removal. 
     When removing one of the lances  27   a  or  27   b  the flexible hoses are connected between the connectors  73  and a flow of cooling water for the lance is established through the temporary hoses to bypass the segments of the supply and return lines  71 ,  72  which incorporate the flexible couplings  77  and  79 . The isolation valves  78 ,  82  can then be actuated to isolate these parts of the supply and return lines which can then be removed to allow withdrawal of the lance. 
     A typical lance withdrawal sequence of operations may be as follows:
         Cease supply of solids to vessel   Cease operation of the hot air blast   Drain slag   Open pressure valves in off-gas hood to establish negative pressure in vessel (this is to prevent an updraft of hot air and potentially hazardous gases escaping from the vessel via the lance support nozzle  62  once the lance is removed)   Connect the flexible hoses  75 ,  76  so as to bypass cooling water isolation valves  78 ,  82  in the supply and return lines  71 ,  72  and open the bypass valves  73 ,  74  to establish water flow (this preferably includes bleeding of the hoses to prevent air bubbles forming in the water circuit)   Close isolation valves  78 ,  82     Remove the isolated sections of the cooling water supply and return lines (flexible couplings  77 ,  79 )   Isolate and disconnect nitrogen supply to lance (typically for nitrogen purge)   Isolate cooling water to flange of hot ore conveying spool  30  if removing a hot ore lance  27   b  (cold lance  27   a  does not have a water cooled flange on its spool)   Disconnect the spool  30  (delivery end) of the solids conveyor and possibly other upstream components of the solids conveyor   Break the split lance mounting ring and remove lance, and place a blanking plate on open flange       

     Reducing the slag level in the vessel, for example by performing a slag drain, prior to the coupling of the by-pass hoses to the lance reduces the heat load on the lance arsing from contact with molten slag. This is advantageous where the by-pass hoses supply cooling water at a reduced rate compared to the permanent cooling water circuit. 
     To subsequently replace the lance, the lance or its substitute is connected to the temporary hoses  75 ,  76  to establish a flow of cooling water through the cooling jacket of the lance and the lance is inserted into the vessel. Nitrogen purge is established through the lance. The flexible couplings  77 ,  79  are then reinstalled, the isolation valves  78 ,  82  are opened and the by-pass valves  73 ,  74  are closed to establish a cooling water flow to the lance through the main supply and return lines  71 ,  72  and so enable the flexible hoses to be removed. The ancillary water flow connections are also re-established at this time and the solids conveyor re-connected so as to enable smelting operations to proceed. 
     Referring now to  FIGS. 8   a ,  8   b  &amp;  8   c  there is provided a pictorial representation of a smelt reduction vessel and a lance extending through an aperture in the vessel shell  17  and supported by lance mounting tube  62 . A lance extraction and insertion hoist  90  extends upwardly and away from the vessel. 
     In  FIG. 8   a  a solids conveyor  91 , typically a pneumatic conveyor, connects to the end of the lance extending from the vessel. The conveyor extends upwardly and away from the vessel, parallel with the hoist. A segment  91   a  of the solids conveyor has been disconnected and is being removed. 
     In  FIG. 8   b  a sufficient length of the solids conveyor has been disconnected from the lance to enable the lance to be extracted from the vessel. In the present embodiment the spool  30  of the solids conveyor has been removed, though other sections of the solids conveyor may be disconnect or removed in order to enable the spool and lance to be removed as a unit. 
     In  FIGS. 8   a ,  8   b  and  8   c  the arrangement of one of the cooling water supply/return lines  71 ,  72  for the lance and one of the flexible hoses  75 ,  76  for the temporary flow of cooling water is shown pictorially. It will be appreciated that the arrangement is duplicated to provide both the supply and return flows in the manner illustrated in  FIG. 6 . Details of the physical layout of the supply and return lines  71 ,  72  and the connections of the flexible hoses  75 ,  76  are shown in  FIG. 7 . 
     In  FIG. 8   c , the lance has been extracted from the vessel by operation of the hoist. Further details on the hoist are provided in the applicants co-pending Australian patent specification AU2004904199 which is incorporated herein by reference. The hoses  75 ,  76  are of sufficient length that the lance can be extracted from the vessel by traversing the length of the hoist. In this way the lance can be extracted from the vessel by isolating and disconnecting a portion of the cooling water supply and return lines whilst maintaining a temporary supply of cooling water to the lance via a temporary hoses. 
     Although the illustrated lances are solids injection lances, the invention is not limited in application to such lances. The method could also be applied to the extraction and replacement of water cooled lances used for injecting gaseous material or a mixture of gas and solids into a metallurgical vessel, for example on injection of additives into slag within the vessel or the injection of air oxygen to promote a combustion process.