Solids injection lance

Abstract

A method for injecting a solid feed material through a solids injection lance includes creating flow conditions in an injection passageway of the lance so that at least a part of the feed material flowing along the passageway forms a buffer zone between a wall of a tube that defines the passageway and feed material flowing along a central section of the passageway.

Claims

1. A method for injecting solid metalliferous material and solid carbonaceous material that includes injecting a solid metalliferous material via a metalliferous material inlet into a passageway extending from a rearward end to a forward end of a lance and creating a flow of metalliferous material along the lance, and injecting solid carbonaceous material in a direction that is transverse to a direction of movement of the metalliferous material via a carbonaceous material inlet into the passageway downstream of the metalliferous material inlet to the passageway so that at least a part of the carbonaceous material forms a buffer zone between a wall of a tube that defines the passageway and the metalliferous material flowing along the passageway.

2. A solids injection lance that includes a tube that defines a passageway for solid metalliferous material and solid carbonaceous material to be injected through the tube and has a rear inlet for solid metalliferous material at a rear end, a separate tube wall inlet arranged transversely to the rear inlet, for solid carbonaceous material injection in a direction that is transverse to a direction of movement of the solid metalliferous material injected at the rear inlet, in a wall of the tube downstream of the rear inlet, and an outlet for discharging solid feed material at a forward end, and wherein at least a part of the carbonaceous material forms a buffer zone between a wall of a tube that defines the passageway and metalliferous material flowing along the passageway.

3. The lance defined in claim 2 includes more than one tube wall inlet downstream of the rear inlet, in the wall of the tube.

4. The lance defined in claim 3 wherein the tube wall inlets in the wall of the tube are selected at locations around and/or along the length of the wall of the tube to promote the formation of the buffer zone.

5. The lance defined in claim 3 wherein the plurality of the tube wall inlets is spaced around the circumference of the wall of the tube.

6. The lance defined in claim 2 wherein the solids injection tube includes a venturi in a rearward section of the tube for accelerating solid metalliferous material and solid carbonaceous material flowing through the venturi, with the venturi including a section that tapers inwardly from a wider rear end to a narrower forward end.

7. The lance defined in claim 6 wherein the tapered section of the venturi is downstream of the rear inlet at the rear end and downstream of the tube wall inlet at the wall of the tube so that in use the buffer zone extends at least partly along the length of the tapered section.

8. The method defined in claim 1 wherein the carbonaceous material is at ambient temperature and the metalliferous material is pre-heated.

9. The method defined in claim 1 wherein the carbonaceous material and the metalliferous material are at ambient temperature.

10. The method defined in claim 1 includes forming the buffer zone so that the buffer zone extends at least partly along the length of a tapered section of a venturi in a section of the tube that accelerates solid metalliferous material and solid carbonaceous material flowing in the passageway.

11. The method defined in claim 1 includes forming the buffer zone so that the buffer zone extends along the whole of the length of a tapered section of a venturi.

12. The method defined in claim 8 includes forming the buffer zone so that the buffer zone extends along the whole of the length of a tapered section of a venturi and forwardly of the tapered section.

13. The method defined in claim 1 includes establishing a flow of feed material in the form of metalliferous material along the passageway and supplying a flow of other feed material into the passageway in a direction that is transverse to the direction of movement of the metalliferous material along the passageway whereby the flow of metalliferous material diverts the flow of the other feed material into the passageway to form the buffer zone.

14. The method defined in claim 13 wherein the other feed material is a carbonaceous material only, a metalliferous material only, or a mixture that includes carbonaceous material and metalliferous material.

15. The method of claim 13 wherein the supplying a flow of another feed material into the passageway in a direction that is perpendicular to the direction of movement of the metalliferous material along the passageway.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention is described further by way of example only with reference to the accompanying drawings, of which:

(2) FIG. 1 is a vertical cross-section through a direct smelting vessel that forms part of an embodiment of a direct smelting plant in accordance with the present invention; and

(3) FIG. 2 is a schematic view that illustrates the above-mentioned embodiment of the direct smelting plant;

(4) FIG. 3 is a diagrammatic partly cross-sectional view of an upper section of an embodiment of a solids injection lance shown in FIGS. 1 and 2 with temperature contours for the hot ore and ambient temperature coal/lime injected via the lance; and

(5) FIG. 4 is the diagrammatic partly cross-sectional view shown in FIG. 3 with coal tracks illustrating the flow of coal through the lance.

DESCRIPTION OF EMBODIMENT

(6) FIG. 1 shows a direct smelting vessel 11 that is suitable particularly for carrying out the HIsmelt process as described by way of example in International patent application PCT/AU96/00197 (WO 1996/031627) in the name of the applicant.

(7) The following description is in the context of smelting iron ore fines to produce molten iron in accordance with the HIsmelt process.

(8) It will be appreciated that the present invention is applicable to smelting any metalliferous material, including ores, partly reduced ores, and metal-containing waste streams via any suitable molten bath-based direct smelting process and is not confined to the HIsmelt process. It will also be appreciated that the ores can be in the form of iron ore fines.

(9) The following description focuses on co-injection of metalliferous material and carbonaceous material via a solids injection lance, but as will be appreciated from the above, the invention is not limited to co-injection of these materials and also extends to injection of metalliferous material without carbonaceous material.

(10) The following description focuses on co-injection of metalliferous material and carbonaceous material to minimise abrasive wear and thermal shock of a solids injection lance. However, as will be appreciated from the above, the invention is not so limited and extends to situations where minimising abrasive wear is a major consideration compared to minimising thermal shock, and vice versa.

(11) The vessel 11 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 a roof 17. Water-cooled panels (not shown) are provided for transferring heat from the side walls 14 and the roof 17. The vessel 11 is further provided with a forehearth 19, through which molten metal is continuously discharged during smelting, and a tap-hole 21, through which molten slag is periodically discharged during smelting. The roof 17 is provided with an outlet 18 through which process off gases are discharged.

(12) In use of the vessel 11 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 position of the nominal quiescent surface of the metal layer 22 is indicated by arrow 24. The position of the nominal quiescent surface of the slag layer 23 is indicated by arrow 25. The term quiescent surface is understood to mean the surface when there is no injection of gas and solids into the vessel 11.

(13) The vessel 11 is provided 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. The solids injection lances 27 are described in more detail in relation to FIGS. 3 and 4. Two solids injection lances 27 are shown in FIG. 1. However, it can be appreciated that the vessel 11 may have any suitable number of such lances 27. In use, heated iron ore fines and ambient temperature coal (and fluxes, typically lime) are entrained in a suitable carrier gas (such as an oxygen-deficient carrier gas, typically nitrogen) and are separately supplied to the lances 27 and co-injected through outlet ends 28 of the lances 27 into the molten bath and preferably into metal layer 22. The following description is in the context that the carrier gas for the iron ore fines and coal is nitrogen.

(14) The outlet ends 28 of the solids injection lances 27 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, as described further below, without significant risk of water coming into contact with the molten metal in the vessel 11.

(15) The vessel 11 also has a gas injection lance 26 for delivering a hot air blast into an upper region of the vessel 11. The lance 26 extends downwardly through the roof 17 of the vessel 11 into the upper region of the vessel 11. In use, the lance 26 receives an oxygen-enriched hot air flow through a hot gas delivery duct (not shown), which extends from a hot gas supply station (also not shown).

(16) FIG. 2 shows schematically one embodiment of a direct smelting plant in accordance with the invention insofar as the plant is concerned with supplying heated iron ore fines and ambient temperature coal to one solids injection lance 27.

(17) The plant includes the direct smelting vessel 11 shown in FIG. 1.

(18) The plant also includes a pre-treatment unit 34 in the form of a pre-heater for heating iron ore fines, typically to a temperature of at least 600 C. The pre-heater may be any suitable type of pre-heater.

(19) The plant also includes an ore delivery system for supplying iron ore fines to the lances 27.

(20) The ore delivery system includes (a) an ore storage/dispensing unit 32 for storing and dispensing heated iron ore fines and (b) an ore supply line 36 for supplying heated ore from the ore storage/dispensing unit 32 to the lances 27.

(21) The ore storage/dispensing unit 32 is constructed to store and dispense heated iron ore fines entrained in nitrogen carrier gas. The ore storage/dispensing unit 32 can be in the form of a plurality of bins that allow heated iron ore fines to be transferred from standard atmospheric conditions to an environment of pressurized carrier gas. However, for the purposes of the present invention, the ore storage/dispensing unit 32 can be considered as a single unit.

(22) In use, iron ore fines are fed to the pre-heater 34 from a stockpile (not shown) and the pre-heater heats the fines. The pre-heater 34 is arranged to heat the fines such that the fines are at a temperature of at least 500 C. and typically of the order of 600 C. to 700 C. at the point of injection into the vessel 11. Off gases can be supplied from the outlet 18 to the pre-heater 34, such that heat can be transferred from the off gases to the iron ore fines. The pre-heater 34 is arranged to supply the heated iron ore fines to the ore storage/dispensing unit 32.

(23) The ore supply line 36 for transporting heated iron ore fines from the storage/dispensing unit 32 to the lance 27 includes (a) a first section 48 that carries the fines to a location proximate the vessel 11, (b) an upwardly extending section 42 which conveys the fines from a position that is approximately level with the base 12 of the vessel 11 to at least the height of the lance 27, and (c) a downwardly extending section 46 which connects the line to an ore inlet in the lance 27. The section 46 is formed to be co-axial with the lance 27 when in an operating position as shown in FIG. 2. The ore inlet in the lance 27 and the overall construction of the lance 27 is described in more detail in relation to FIGS. 3 and 4.

(24) The plant also includes a coal delivery system for supplying coal to the lances 27.

(25) The coal delivery system includes (a) a coal storage/dispensing unit 38 which receives coal from a stockpile (not shown) and stores and dispenses the coal under ambient temperature and (b) a supply line 40 for transporting coal from the coal storage/dispensing unit 38.

(26) In use, coal at ambient temperature is discharged from the coal dispensing assembly 38 entrained in nitrogen carrier gas and transferred via the coal supply line 40 to the lance 27.

(27) The coal storage/dispensing unit 38 can be in the form of a plurality of bins that allow coal to be transferred from standard atmospheric conditions to an environment of a pressurized nitrogen carrier gas. However, for the purposes of the present invention, the coal dispensing assembly 38 can be considered to be a single unit.

(28) The coal supply line 40 is connected to a coal inlet in the lance 27. The coal inlet in the lance 27 and the overall construction of the lance 27 is described in more detail in relation to FIGS. 3 and 4. Typically, the coal delivery system supplies coal and flux material, such as lime.

(29) FIG. 3 is a diagrammatic partly cross-sectional view of an upper section of the solids injection lance 27 shown in FIGS. 1 and 2 with temperature contours for the hot iron ore fines and ambient temperature coal (and lime) injected via the lance 27.

(30) FIG. 4 is the diagrammatic partly cross-sectional view shown in FIG. 3 with coal tracks illustrating the flow of coal through the lance 27.

(31) With reference to FIGS. 3 and 4, the lance 27 includes a tube 60 that defines a passageway 62 for solid feed material to be injected through the tube 60 and to exit the lance 27 via the outlet end 28 of the lance shown in FIGS. 1 and 2.

(32) The tube 60 has a venturi generally identified by the numeral 52 at an upper end section of the tube 60 for accelerating solid feed material flowing through the venturi. The venturi 52 includes a wider rear end section 56, a narrower forward end section of the venturi 58, and a section 54 that tapers inwardly from the wider section 56 to the narrower section 58.

(33) The remainder of the tube 60 extending from the venturi 52 to the forward end 28 of the lance 27 has a uniform cross-section.

(34) The tube 60 has an inlet 64 for heated iron ore fines at a rear end of the tube 60 and a pair of diametrically-opposed separate inlets 66 for coal in the tube 60 downstream of the ore inlet 64. The coal inlets 66 are formed in the wider section 56 of the venturi 52. The ore inlet 64 and the coal inlets 66 are arranged to create flow conditions in the passageway 62 so that in use at least a part of the coal supplied into the passageway 62 via the coal inlets 66 forms a buffer zone 70 between the tube wall and the iron ore fines flowing in a central section of the passageway 62. Coal is less abrasive than iron ore fines and therefore the buffer zone 70 reduces abrasive wear of the material that forms the wall of the tube 60. In addition, in situations where the iron ore fines are hot and the coal is at an ambient temperature, as is the case in the described embodiment, the buffer zone 70 minimises thermal shock that could reduce the effective life of the tube wall.

(35) There may be any suitable number and arrangement of coal inlets 66. The coal inlets 66 may be at the same position along the length of the tube 60 and/or at spaced intervals along the length of the tube 60.

(36) The locations and numbers of the coal inlets 66 are selected in relation to the ore inlet 64 and the injection parameters (volumetric flow rates, injection velocities, particle size distributions, etc) for the coal and the iron ore fines such that the flow of iron ore fines in the passageway 62 divert the transverse, typically perpendicular flow of coal into the passageway 62 via the coal inlets 66 such that the direction of flow of sufficient of the injected coal is diverted to form the buffer zone 70.

(37) The tapered section 54 of the venturi 52 is a region of high abrasive wear due to acceleration of feed materials in the tapered section and it is therefore highly advantageous for the buffer zone 70 to extend at least partly along, and preferably all of the way along, the length of the tapered section 54 to reduce abrasive wear in the tapered section 54.

(38) Basically, the method may include selecting the operating conditions, such as the injection flow rates and injection velocities to form the buffer zone 70 so that it extends along the required length of the tube to shield sections of the tube that are susceptible to high abrasive wear and thermal shock.

(39) FIGS. 3 and 4 include temperature contours that illustrate the temperature in the lance 27 in the described embodiment where there is injection of hot iron ore fines and ambient temperature coal. It is evident that the temperature in the buffer zone 70 is considerably lower than in the central section of the passageway 62.

(40) FIG. 4 also includes tracks that illustrate the paths of movement of coal in the passageway 62. In particular, the Figure illustrates how the forward flow of iron ore fines in the passageway 62 diverts the flow of coal in the passageway under the particular injection conditions for the Figure.

(41) The advantages provided by the buffer zone 70 reduce the current requirements for high wear resistant and thermal shock resistant materials for the tube wall, which tend to be a limited range of expensive materials, and opens up the possibility of using a wider range of less expensive materials.

(42) It is noted that from a practical perspective the buffer zone 70 may not be a continuous zone and may not be a uniform thickness and there may be iron ore fines in the zone. However, even in this situation, from a comparative viewpoint, the buffer zone 70 as described in relation to FIGS. 3 and 4 will reduce the abrasive wear and thermal shock issues compared to situations in which there is no buffer zone and a mixture of iron ore fines and coal is flowing along the passageway 62.

(43) It is also noted that ultimately there will be mixing of the materials in the buffer zone 70 and a central section of the passageway 62 as the materials flow along the passageway 62 so that there is a uniform mixture of iron ore fines and coal flowing along the passageway 62.

(44) Many modifications may be made to the embodiment of the solids injection lance of the present invention described in relation to the Figures without departing from the spirit and scope of the invention.

(45) By way of example, whilst the embodiment of the solids injection lance is described in the context of the HIsmelt direct smelting process, it can readily be appreciated that the present invention is not so limited and extends to any molten bath-based smelting process.

(46) By way of example, whilst the embodiment of the solids injection lance is described in the context of smelting iron ore, it can readily be appreciated that the present invention is not limited to this material and extends to any suitable metalliferous material.

(47) By way of example, whilst the embodiment of the solids injection lance is described in the context of injecting solid feed materials in the form or iron ore and carbonaceous material, it can readily be appreciated that the present invention is not so limited and extends to injecting any suitable feed material.

(48) In the claims which follow and in the preceding description of the invention, except where the context requires otherwise due to express language or necessary implication, the word comprise or variations such as comprises or comprising is used in an inclusive sense, i.e. to specify the presence of the stated features but not to preclude the presence or addition of further features in various embodiments of the invention.