Lance for blowing solid material into a container

Abstract

A lance for injecting a solid material into a vessel, such as a direct melting vessel for producing molten iron, the lance comprising a core tube assembly including a flow path for solid material, the core tube assembly having an inlet for receiving solid material at the rear end and an outlet for discharging material at the front end, the core tube assembly comprising: two or more than two axially aligned sections welded together at adjacent ends of the sections, an outer tube made of stainless steel and an inner tube made of white cast iron, which are connected to each other, wherein the bond between the outer tube and the inner tube is a metallurgical bond over substantially the entire surface of the interface between the outer tube and the inner tube.

Description

Field of the invention

[0001] The present invention relates to a lance for injecting solid material into a vessel, such as a direct melting vessel for producing molten iron, a direct melting process for producing molten metal from a metalliferous feed material, a core tube assembly for a lance for injecting solid material into a vessel, and a method for manufacturing the core tube assembly. background

[0002] A known direct melting process, which is mainly based on a melt bath as the reaction medium and is generally referred to as the HIsmelt process, is described in the name of the applicant in International Application PCT / AU96 / 00197 (WO 96 / 31627).

[0003] The HIsmelt process, as described in this International Application in connection with the production of molten iron, includes the following: (a) creating a bath of molten iron and molten slag in a vessel; (b) Blowing into the bath of: (i) a metal-containing material, typically iron oxides; and (ii) a solid carbonaceous material, typically coal, which acts as a reducing agent of the iron oxides and as an energy source, and (c) Melting the metal-containing material in the molten bath to form iron.

[0004] The term “melting” should be understood here as thermal processing, whereby chemical reactions take place that reduce metal oxides to produce molten metal.

[0005] The HIsmelt process also includes the post-combustion of reaction gases such as CO and H 2released from the bath in the space above the bath with oxygen-containing gas and transferring the heat generated by the afterburning to the bath, thus contributing to the thermal energy required for melting the metal-containing materials.

[0006] The HIsmelt process also includes the formation of a transition zone above the nominally quiescent surface of the bath in which there is a beneficial mass of rising and subsequently descending drops or splashes or streams of molten metal and / or molten slag, providing an effective medium for transferring the thermal energy generated by the afterburning of the reaction gases above the bath to the bath.

[0007] In the HIsmelt process, the metalliferous material and solid carbonaceous material are injected into the molten bath through a series of lances / nozzles inclined to the vertical so that they extend downward and inward through the side wall of the melting vessel and into a lower region of the vessel to introduce at least a portion of the solid material into the metal layer at the bottom of the vessel. To promote the afterburning of the reaction gases in the upper part of the vessel, hot blast, which may be oxygen-enriched, is injected into an upper region of the vessel through a downwardly extending hot blast injection lance. Exhaust gases resulting from the afterburning of the reaction gases in the vessel are discharged from the upper part of the vessel through an exhaust pipe.The vessel encloses refractory-lined, water-cooled plates in the side wall and vault of the vessel, and water circulates steadily through the plates in a continuous circuit.

[0008] The HIsmelt process allows for the production of large quantities of molten iron by directly melting metal-containing material. To achieve such production standards, large quantities of both metal-containing material and carbon-containing material must be added to the vessel.

[0009] An example of a solids injection lance design for use in a direct melt vessel can be found in U.S. Patent 6,398,842 (assigned to the assignee herein). This type of lance can be used to inject solid particulate material, such as metalliferous material or carbonaceous material, into the direct melt vessel. In this design, the solid particulate material is passed through a central core tube that is rigidly inserted within an outer annular cooling jacket. An internal forced cooling system with cooling water is provided within the outer annular cooling jacket to enable the lance to operate successfully when exposed to the high temperatures encountered inside a direct melt vessel, which can exceed 1400°C.

[0010] Metalliferous material and carbonaceous material can be particularly abrasive. When the direct smelter is used to produce molten iron, the metalliferous material typically includes iron ore fines. It is desirable that the components of the direct smelter be able to withstand the influence of these abrasive materials throughout a smelting campaign, which may last 12 months or more.

[0011] US 6,245,285 B1 discloses a lance having a hollow tubular member forming a central flow path along the entire length of the lance between the inlet end and the outlet end. The inner tube is made of a ceramic material, and the outer tube is made of stainless steel.

[0012] US 4,239,194 A concerns a tuyere designed to blow refining fluid through the bottom of steelworks converters.

[0013] GB 2 028 987 A relates to a lance tube suitable for refining metal by injecting gas into the molten metal, which is coated to a thickness of 2 to 15 mm with a material heat-resistant up to a temperature of more than 1800°K.

[0014] The present invention provides an effective and reliable solids injection lance for injecting metalliferous material and / or carbonaceous material into a direct melting vessel. Brief description of the invention

[0015] The present invention provides a lance for injecting a solid material into a vessel, such as a direct melting vessel for producing molten iron, according to claim 1.

[0016] The design of the lance's core barrel assembly, comprising an outer stainless steel tube and an inner white cast iron tube, optimizes the quite different requirements of the core barrel assembly, particularly in cases where the lance is relatively long (i.e., at least 4 m) and is used to inject hot (i.e., greater than 600°C) abrasive materials. Furthermore, joining the inner and outer tubes together is particularly advantageous in cases where the core barrel assembly comprises two or more axially aligned sections that need to be welded together. By way of illustration, it is often the case that wear-resistant materials, such as white ferrochrome cast iron, are difficult to weld reliably, and consequently there is a real risk that welds joining adjacent sections of a wear-resistant material may fail prematurely, ultimately leading to lance failure.Joining the inner and outer tubes together offers one way to avoid this problem. Furthermore, when a core barrel assembly comprises multiple sections, the outer tube offers a way to minimize any risks of lance failure even in situations where the inner tube is made up of segments rather than a single continuous tube, since construction materials suitable for use in the outer tube can typically be welded together with very good weld integrity.The bond between the outer tube and the inner tube also extends at least substantially over the entire surface of the interface between the outer tube and the inner tube, thereby providing resistance to shear forces to which such tubes are subjected and which arise from the pneumatic transport of the materials through the flow path of the core tube assembly into the vessel.

[0017] The outer tube is made of stainless steel.

[0018] The outer tube is preferably at least 3 mm thick.

[0019] The thickness of the outer tube is preferably in the range of 3 to 15 mm and more preferably in the range of 3 to 10 mm.

[0020] The inner tube is made of white cast iron, preferably white ferrochrome cast iron.

[0021] The white cast iron or white ferrochrome cast iron is preferably at least 3 mm thick and more preferably at least 5 mm thick.

[0022] The white cast iron or white ferrochrome cast iron preferably has a thickness in the range of 3 to 40 mm, more preferably 3 to 25 mm.

[0023] The bond between the outer tube and the inner tube extends at least substantially over the entire surface of the interface between the outer tube and the inner tube.

[0024] The bond between the outer tube and the inner tube is a metallurgical bond.

[0025] The metallurgical bond is preferably created by casting the inner tube onto the inside of the outer tube.

[0026] The core tube assembly may comprise a single outer tube and a single inner tube.

[0027] According to the invention, the core tube assembly comprises two or more than two axially aligned sections which are welded together at adjacent ends of the sections.

[0028] The core tube arrangement is preferably at least 4 m long.

[0029] Preferably, the core tube arrangement has a minimum internal diameter of 80 mm.

[0030] Preferably, the core tube assembly has a minimum outer diameter of 120 mm.

[0031] The lance is preferably a lance for blowing in solids.

[0032] The lance is preferably a lance for blowing in solids for abrasive material.

[0033] The lance preferably further comprises an annular water cooling jacket extending over a substantial portion of the core tube assembly.

[0034] The cooling jacket preferably has an inner diameter that is larger than the outer diameter of the core tube assembly so that there is a substantially annular space between the core tube assembly and the cooling jacket.

[0035] The present invention further provides a direct melting plant comprising a direct melting vessel having at least one lance as described above.

[0036] The present invention further provides a direct melting process for producing a molten metal from a metal-containing feed material, which comprises injecting a solid feed material, such as the metal-containing feed material, into a direct melting vessel through at least one lance as described above.

[0037] An example of a metalliferous feed material is iron ore, particularly iron ore fines.

[0038] In the case of prior injection of iron, the process preferably comprises injection of the iron ore at a temperature of at least 600°C.

[0039] The present invention further provides a core tube assembly for a lance for injecting a solid material into a vessel, the core tube assembly comprising a flow path for solid material, the core tube assembly having an inlet and an outlet, the core tube assembly comprising an outer tube of a structural material and an inner tube of a wear-resistant material joined together.

[0040] The present invention further provides a method for manufacturing the core tube assembly described above, comprising the following steps: (a) centrifugal casting of the outer tube from stainless steel; and (b) centrifugal casting of the inner tube of white cast iron onto the inside of the outer tube and (c) metallurgically joining the tubes together over substantially the entire surface of the interface between the outer tube and the inner tube. Short descriptions of the drawings

[0041] By way of example only, the present invention will be further described with reference to the accompanying drawings, in which: Fig. 1 a vertical cross-section through a direct melting vessel enclosing several lances for blowing in solids; Fig. 2 a partial longitudinal section of a conventional solids injection lance for injecting ore into the Fig. 1 vessel shown; Fig. 3 shows a cross-section of a core tube arrangement according to an embodiment of a lance according to the invention for blowing in solids; and Fig. 4 is an enlarged view of the front end of the core tube assembly of Fig. 3. Detailed description

[0042] Fig. Figure 1 shows a direct melting vessel 11 particularly suitable for carrying out the HIsmelt process as described in International Patent Application PCT / AU96 / 00197. The following description is in the context of the melting of iron ore fines to produce molten iron according to the HIsmelt process. It is to be understood that the present invention can be applied to the melting of any metal-containing material, including ores, partially reduced ores, and metal-containing waste streams. It is also to be understood that the ores may be in the form of iron ore fines. It is also to be understood that the present invention is not limited to the production of iron and extends to the melting of other metals (including alloys).

[0043] The vessel 11 comprises a hearth including a base 12 and sides 13 of refractory bricks, side walls 14 forming a generally cylindrical vessel extending upwardly from the sides 13 of the hearth, and a vault 17. Water-cooled plates (not shown) are provided to transfer heat from the side walls 14 and also from the vault 17. The vessel 11 is further equipped with a forehearth 19 through which molten metal is continuously discharged during the melting process and a taphole 21 through which molten slag is periodically discharged during the melting process. The vault 17 is equipped with an outlet 18 through which process exhaust gases are discharged.

[0044] When using vessel 11 to melt iron ore fines to produce molten iron according to the HIsmelt process, vessel 11 contains a molten iron and slag pool including a layer 22 of molten metal and a layer 23 of molten slag on top of metal layer 22. The position of the nominally quiescent surface of metal layer 22 is indicated by arrow 24. The position of the nominally quiescent surface of slag layer 23 is indicated by arrow 25. The term "quiescent surface" is intended to mean the surface when no gas or solids are injected into vessel 11.

[0045] The vessel 11 is equipped with solids injection lances 27 that extend downwardly and inwardly through openings (not shown) in the side walls 14 of the vessel and into the slag layer 23. In use, iron ore fines and / or solid carbonaceous material (such as coal or coke breeze) and flux are entrained in a suitable carrier gas (such as an oxygen-deficient carrier gas, typically nitrogen) and injected into the metal layer 22 through outlet ends 28 of the lances 27.

[0046] The outlet ends 28 of the lances 27 are located above the surface of the metal layer 22 during the process. This position of the lances 27 reduces the risk of damage from contact with molten metal and also allows the lances to be cooled by internal forced cooling with water without there being a significant risk of water coming into contact with the molten metal in the vessel 11.

[0047] The vessel 11 also includes a gas injection lance 26 for supplying hot blast to an upper portion of the vessel 11. The lance 26 extends downward through the dome 17 of the vessel 11 into the upper portion of the vessel 11. In use, the lance 26 receives an oxygen-enriched hot air stream through a hot gas supply tube (not shown) extending from a hot gas supply station (also not shown).

[0048] Fig. Figure 2 shows the general structure of a known conventional lance 27 for injecting solids, which is disclosed in the above-mentioned US patent 6,398,842 (assigned to the present assignee).

[0049] As in Fig. 2, the lance 27 comprises a core tube assembly 31 in the form of a tube which forms a flow path for solid material in the form of iron ore fines and / or carbonaceous material entrained in a suitable carrier gas to flow from an inlet end to a forward end 62 of the lance 27.

[0050] The lance 27 also includes an annular cooling jacket 32 ​​surrounding the core tube assembly 31 and extending over a substantial portion of the length of the core tube assembly 31.

[0051] The annular cooling jacket 32 ​​of the known lance 27 is in the form of a long, hollow annular structure 41 having outer and inner tubes 42, 43 connected by a front-end connector 44. An elongated tubular structure 45 is located within the hollow annular structure 41, dividing the interior of the structure 41 into an elongated inner annular water flow path 46 and an elongated outer annular water flow path 47.

[0052] The rear end (not shown) of the annular cooling jacket 32 ​​of the known lance 27 is provided with a water inlet (also not shown) through which a flow of cooling water can be directed into the inner annular water flow path 46, and a water outlet (also not shown) from which water is transported out of the outer annular flow path 47 at the rear end of the lance 27. Thus, when the lance 27 is in use, cooling water flows forward along the lance, downward through the inner annular water flow path 46, radially outward through the connector 44, and then back through the outer annular flow path 47 along the lance 27. Consequently, the cooling water provides effective cooling of the lance 27 when it is exposed to the heat generated in the melting vessel 11 during use.

[0053] The Fig. 3 and Fig. 4 show a main part of a lance 27 for blowing solids according to an embodiment of the present invention. The Fig. 3 and Fig. 4 comprises a core tube assembly 50. Although only partially shown in the figures, the solids injection lance 27 also comprises an annular cooling jacket. Fig. Figure 3 shows only a portion of the connector 44 for the forward ends of the annular cooling jacket to illustrate the outlet end of the core tube assembly 50.

[0054] The Fig. 3 and Fig. The core tube assembly 50 shown in Figure 4 includes a flange 52 provided at the rear end (indicated by arrow R) of the core tube assembly 50. The flange 52 facilitates the connection of the core tube assembly 50 to other components of the solids injection lance 27 (not shown).

[0055] The core barrel assembly 50 includes three core barrel sections 54a, 54b, and 54c arranged end-to-end and welded together. The core barrel section 54a is located at the rear end of the core barrel assembly 50 and receives solid material. The core barrel section 54c is located at the front end of the core barrel assembly 50 and delivers solid material to the vessel. The core barrel section 54b is located between the core barrel sections 54a and 54c.

[0056] Each core tube section 54a, 54b, 54c includes an outer tube section 56 made of a structural material, such as stainless steel, and an inner tube section 72 made of a wear-resistant material, such as white ferrochrome cast iron. The inner and outer tube sections 56, 72 are metallurgically bonded together. Typically, the metallurgical bond extends over the entire surface of the interface between the tube sections. The adjacent ends of the outer tube sections 56 of the core tube sections 54a, 54b, 54c are welded together.

[0057] The outer tube sections 56 determine the structural requirements of the core barrel assembly 50. The inner tube sections 72 determine the wear resistance requirements of the core barrel assembly 50. Each tube section 56, 72 is designed to optimize the structural and wear resistance requirements. The metallurgical bond facilitates joining the core barrel sections 54a, 54b, 54c together to form the core barrel assembly 50.

[0058] Each core tube section 54a, 54b, 54c can be conventionally manufactured by centrifugal casting of the tubes according to the following steps: (a) centrifugal casting of the outer tube from stainless steel; and (b) centrifugal casting of the inner tube made of white ferrochrome cast iron onto the inside of the outer tube and (c) metallurgical joining of the tubes together.

[0059] As stated above, the lance 27 comprises for injecting solids as used in the Fig. 3 and Fig. 4, also includes an annular cooling jacket surrounding the core barrel assembly 50 and extending over a substantial portion of the length of the core barrel assembly 50. The annular cooling jacket is shown in the Fig. 3 and Fig. 4 not shown, except for the connecting piece 44.

[0060] The annular cooling jacket 32 ​​has the same basic structure as the annular cooling jacket 32 ​​of a known lance, as shown in Fig. 2 is shown.

[0061] It is important to note that there is a small annular gap (not shown), typically 2 to 4 mm, between the inner wall of the annular cooling jacket and the outer wall of the core tube assembly 50 to allow relative movement between these components and to allow a purge gas to be supplied along their length.

[0062] It is preferred that the core tube sections 54a, 54b, 54c be arranged so that the hollow cores 55 are aligned. Any deviation in the alignment of the core tubes 54a, 54b, 54c may result in increased wear occurring at the interface between adjacent core tube sections 54a, 54b, 54c, which significantly reduces the useful life of the core tube assembly 50.

[0063] Furthermore, it is preferred that the core tube sections 54 be straight so that the hollow cores 55 are also straight. Any curvature in the internal material flow path of the core tube assembly 50 may result in increased localized wear on a portion of one or more of the core tube sections 54a, 54b, 54c. This wear, in turn, will significantly reduce the useful life of the core tube assembly 50.

[0064] Modifications to the embodiments described above may be made within the scope of the patent claims.

Claims

[1] A lance for injecting a solid material into a vessel, such as a direct melting vessel for producing molten iron, the lance comprising a core tube assembly including a flow path for solid material, the core tube assembly having an inlet for receiving solid material at the rear end and an outlet for discharging material at the front end, the core tube assembly comprising: two or more than two axially aligned sections welded together at adjacent ends of the sections, an outer tube made of stainless steel and an inner tube made of white cast iron, which are connected to each other, wherein the bond between the outer tube and the inner tube is a metallurgical bond over substantially the entire surface of the interface between the outer tube and the inner tube. [2] A lance according to claim 1, wherein the outer tube is at least 3 mm thick. [3] Lance according to claim 2, wherein the thickness of the outer tube is in the range of 3 to 15 mm. [4] A lance according to any one of the preceding claims, wherein the inner tube is made of white ferrochrome cast iron. [5] A lance according to any one of the preceding claims, wherein the white cast iron or white ferrochrome cast iron is at least 3 mm thick. [6] A lance according to claim 5, wherein the white cast iron or white ferrochrome cast iron has a thickness in the range of 3 to 40 mm. [7] A lance according to any one of the preceding claims, wherein the metallurgical bond is created by casting the inner tube onto the inside of the outer tube. [8] Lance according to one of the preceding claims, wherein the core tube assembly is at least 4 m long. [9] Lance according to one of the preceding claims, wherein the core tube assembly has a minimum internal diameter of 80 mm. [10] Lance according to one of the preceding claims, wherein the core tube assembly has a minimum outer diameter of 120 mm. [11] A lance according to any preceding claim, further comprising an annular water cooling jacket extending over a substantial portion of the core tube assembly. [12] A lance according to claim 11, wherein the cooling jacket has an inner diameter which is larger than the outer diameter of the core tube assembly so that a substantially annular space is provided between the core tube and the cooling jacket. [13] Direct melting plant comprising a direct melting vessel having at least one lance according to one of the preceding claims. [14] A direct melting process for producing molten metal from a metal-containing feed material, comprising injecting a solid feed material, such as the metal-containing feed material, into a direct melting vessel via at least one lance according to any one of claims 1 to 12. [15] A core tube assembly for a lance for injecting a solid material into a vessel, the core tube assembly comprising a flow path for solid material, the core tube assembly having an inlet and an outlet, the core tube assembly being configured as defined in any one of claims 1 to 12. [16] A method of manufacturing the core tube assembly according to claim 15, comprising the following steps: (a) centrifugal casting of the outer tube from stainless steel; and (b) centrifugal casting of the inner tube of white cast iron onto the inside of the outer tube and (c) metallurgically joining the tubes together over substantially the entire surface of the interface between the outer tube and the inner tube.

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