METHOD AND APPARATUS FOR CO-INJECTING CARBON-BASED PARTICULATE AND OXYGEN-BASED GAS STREAMS INTO A LIQUID BATH

Description

RELATED APPLICATIONS

This application claims the benefit of priority to U.S. Provisional Application Ser. No. 63/736,655, filed on Dec. 20, 2024, which is incorporated herein by reference in its entirety for all purposes.

FIELD OF THE INVENTION

The present invention generally relates to using a relatively higher pressure motive gas to accelerate a relatively lower pressure fluidized particulate stream to supersonic velocities followed by the injection of the fluidized particulate stream with the gas at supersonic velocities into a liquid bath. More particularly, the present invention relates to co-injecting carbon-based particulates and an oxygen-containing gas into a metal bath within a steelmaking furnace utilizing an injector apparatus.

BACKGROUND OF THE INVENTION

Oxygen gas is typically injected through a dedicated lance into a furnace, such as an electric arc furnace, during a steelmaking process whereby oxygen gas oxidizes impurities in the steel which then move upwards into the slag layer (FIG. 6b) covering the liquid pool (e.g., molten metal or steel bath). Because the oxygen also undesirably oxidizes iron, a separate lance for carbon-based particulates, as also shown in FIG. 6b, is utilized to introduce carbon, which acts as a reductant, into the slag to reform iron from iron oxide, thereby maintaining steel product yield. For this reason, carbon and oxygen lances are utilized in a side-by-side arrangement above the liquid pool to ensure oxidation of the impurities and the recovery of iron. The lances can also be introduced into the furnace through a so-called slag door but are typically mounted in the furnace wall and spaced above the liquid pool.

It is desirable to maximize the amount of oxygen that penetrates into the liquid pool to help stir the steel bath and carry out the metallurgical reactions. It is also desirable to have all of the carbon particulate impinge at or near the liquid pool/slag interface at the location of the oxygen injection to carry out the metallurgical reactions. In this regard, the lances should be preferably in close proximity to the surface of the liquid pool. However, such arrangement is not viable because the close proximity of the tip of the lances to the liquid pool surface will result in significant damage and plugging to the lances as a result of splashing of the liquid pool onto the lances. The corrosive nature of the liquid pool can rapidly deteriorate the lance equipment.

To overcome corrosion and plugging of the oxygen lances, the oxygen lances are located farther away from the liquid pool and a converging-diverging nozzle is incorporated into the oxygen lances to accelerate the oxygen, supplied at high pressure, to supersonic velocities, thereby imparting sufficient momentum to the oxygen to enable it to travel the necessary farther distance at supersonic velocity towards the liquid pool from an outlet of the corresponding lances. Further, the supersonic flow of oxygen is commonly surrounded by a shroud of subsonic fuel and oxygen. This oxy-fuel shroud has the effect of maintaining the oxygen gas as a coherent jet (defined hereinbelow) and thereby extends the coherent jet a considerable distance compared to an unshrouded jet. This allows the oxygen lances to be placed a sufficient distance from the molten pool.

To be transported, carbon-based particulates must be fluidized into a gas stream, typically air, and blown into the furnace. Similar to oxygen, the lance for feeding the carbon-based particulates is situated a sufficient distance away from the liquid pool, as shown in FIG. 6b. However, there are operational challenges with successful injection of the carbon-based particulates. For example, the carbon-based particulate stream is abrasive and therefore cannot be accelerated to the same momentum as the oxygen without causing issues of wear to the transport piping and the carbon lance. Additionally, a majority of the carbon-based particulates exiting the injector typically do not have sufficient momentum to completely reach the liquid pool/slag interface. Consequently, a significant portion of the carbon-based particulates can be undesirably lost to the furnace system exhaust port, which is typically located in the roof of the furnace. Inefficient carbon injection requires a greater amount of carbon be used to ensure that an adequate amount reaches the steel bath to minimize over-oxidation of the steel bath. Furthermore, carbon-based particulate that is not effectively reacted within the slag (because of failure of the carbon-based particulate to reach the slag) will instead burn in the off-gas fume system, generating heat which in turn requires cooling. If there is not sufficient cooling capacity, the excessive heat load to the off-gas system limits productivity.

In view of these drawbacks, there is an unmet need for optimized introduction of carbon-based particulates and oxygen-based gas streams into a liquid pool, such as molten metal, in a manner where substantially all of such carbon-based particulate and oxygen-based gas streams enter the slag, liquid pool and/or slag/pool interface.

SUMMARY OF THE INVENTION

The invention may include any of the following aspects in various combinations and may also include any other aspect of the present invention described below in the written description.

Other aspects, features and embodiments of the disclosure will be more fully apparent from the ensuing description and appended claims.

Generally speaking, the present invention, in one aspect, provides a method and apparatus of introducing a carbon-based particulate stream into a liquid bath (e.g., a bath of a metallurgical liquid) that involves directing the carbon-based particulate stream into an oxygen-containing gas to form a multi-phase solids/gas jet stream. The multi-phase solids/gas jet stream has a supersonic velocity and is surrounded by an oxy-fuel shrouded gas. The oxy-fuel shrouded gas stream comprises a burning fuel that is only created at the outlet of the injector apparatus. The oxy-fuel shrouded gas stream has a subsonic velocity. The apparatus and method according to the present invention enables the multi-phase solids and gas jet stream to be maintained at supersonic velocity and exhibit sufficiently high momentum such that substantially all of the carbon-based particulates and the oxygen-containing gas penetrate a predetermined depth into the slag, slag pool interface and/or liquid bath to participate in the required metallurgical reactions and further where the co-injection of the multi-phase solids and gas jet stream occurs in close proximity to each other at substantially the same predetermined depth.

In a first aspect, a method of injecting a method of generating a supersonic jet of a fluidized carbon-based particulate stream in a motive oxygen-containing gas stream delivered as a combined coherent supersonic jet stream into a liquid pool contained in a furnace, comprising: introducing the fluidized carbon-based particulate stream through a first inner channel of an injector; introducing the motive oxygen-containing gas stream through a second inner channel of said injector, wherein said second inner channel comprises a converging/diverging geometry; directing the flow of the motive oxygen-containing gas stream through a converging section of the converging/diverging geometry to compress the flow of the motive oxygen-containing gas stream to a corresponding critical pressure; partially expanding the flow of the motive oxygen-containing motive gas stream through a diverging section of the converging/diverging geometry to a pressure substantially equal to a pressure of the fluidized carbon-based stream pressure entering the mixing section, wherein the motive oxygen-containing gas is accelerated to a supersonic velocity upon flowing through the diverging section and entering into a mixing section; introducing the fluidized carbon-based particulate stream into the mixing section, where the fluidized carbon-based particulate stream mixes with the motive oxygen-containing gas stream; flowing the motive oxygen-containing gas stream with the fluidized carbon-based particulate steam to produce a combined jet stream having a supersonic velocity designated as a supersonic fluidized carbon jet; expanding the supersonic fluidized carbon jet to atmospheric pressure and ejecting the supersonic fluidized carbon jet from an outlet of the injector; surrounding the supersonic fluidized carbon jet with an oxy-fuel shroud created at the outlet of the injector, said oxy-fuel shroud flowing at a subsonic velocity to produce the combined coherent supersonic jet stream; and flowing the combined coherent supersonic jet stream from the outlet of the injector to the liquid pool.

In a second aspect, an injector apparatus adapted to produce a supersonic jet of a fluidized carbon-based particulate stream in a motive gas stream delivered as a combined coherent supersonic stream into a liquid pool, comprising: a first inner channel of an injector, said first inner channel extending substantially along a central axis of the injector, said first channel configured to receive a carbon-based particulate stream flowing therethrough; a second inner channel of said injector, wherein said second inner channel is outwardly spaced apart from the first inner channel, and further wherein said second inner channel comprises a converging/diverging geometry, said second inner channel configured to receive the motive gas stream at subsonic velocity and accelerate said motive gas stream into a supersonic velocity stream flowing through the second inner channel; a first outer passageway spaced apart from the central axis of the injector, said first outer passageway spaced apart from the central axis a distance greater than that of the second inner channel, said first outer passageway configured to receive a fuel; and a second outer passageway spaced apart from the central axis of the injector, said second outer passageway spaced apart from the central axis a distance greater than or equal to that of the second inner channel, said second outer passageway configured to receive an oxygen gas stream; wherein each of said first outer passageway and second outer passageway remain separate and distinct from an inlet of the injector apparatus to an outlet of the injector apparatus, thereby preventing intermixing of the fuel and the oxygen gas stream, respectively.

In a third aspect, a method of co-injecting an motive gas stream and a particulate or gas stream into a liquid pool, comprising: introducing the motive gas stream through a first inner channel of an injector at a first supply pressure; introducing the particulate or gas stream through a second inner channel of said injector at a second supply pressure less than the first supply pressure of the motive gas stream; accelerating the motive gas stream through a converging/diverging geometry to create a partially expanded, supersonic flow of the motive gas stream; directing the partially expanded, supersonic flow of the motive gas stream into a mixing section located at a predefined axial location of the injector; directing the particulate or gas stream into the mixing section; mixing the partially expanded, supersonic flow of the motive gas stream with the particulate or gas stream under conditions where the partially expanded, supersonic flow of the motive gas stream is at a pressure substantially equal to the first pressure of the particulate or gas stream, and lower than a critical pressure corresponding to the motive gas but greater than a downstream exit pressure at the outlet of the injector; producing a supersonic fluidized jet stream; withdrawing the supersonic fluidized jet stream from an outlet of the injector; forming an oxy-fuel shroud at an outlet of the injector apparatus; surrounding the supersonic velocity fluidized jet stream with the oxy-fuel shroud to form a combined coherent supersonic velocity jet stream; and directing the combined coherent supersonic velocity jet stream from the outlet of the injector to a surface of the liquid pool.

In a fourth aspect, an injector apparatus adapted to produce a combined coherent supersonic jet stream, comprising: a first inner channel of an injector, said first inner channel extending substantially along a central axis of the injector, said first channel configured to receive a reducing solids stream at a supply pressure; a second inner channel of said injector, wherein said second inner channel is radially and outwardly spaced apart from the first inner channel, and further wherein said second inner channel comprises a converging/diverging geometry, said second inner channel configured to receive an oxidizing gas stream at a higher supply pressure than the supply pressure of the reducing solids stream and accelerate said oxidizing gas stream into a supersonic velocity stream by restricting the flow of the gas stream to a choking point and then expanding the oxidizing gas stream through a diverging section of the converging/diverging geometry in the second inner channel; a first outer passageway spaced apart from the central axis of the injector, said first outer passageway spaced apart from the central axis a distance greater than that of the second inner channel spaced apart from the central axis, said first outer passageway configured to receive a fuel; and a second outer passageway spaced apart from the central axis of the injector, said second outer passageway spaced apart from the central axis a distance greater than that of the second inner channel spaced apart from the central axis, said second outer passageway configured to receive an oxygen gas stream; wherein each of said first outer passageway and second outer passageway remain separate and distinct from an inlet of the injector apparatus to an outlet of the injector apparatus, thereby preventing intermixing of the fuel and the oxygen gas stream configured to flow therewithin, respectively.

In a fifth aspect, a method of generating a supersonic jet of a fluidized carbon-based particulate stream in an oxygen-containing gas stream delivered as a combined coherent supersonic jet stream into a liquid pool contained in a furnace, comprising: accelerating an oxygen-containing gas stream through a diverging section of the converging/diverging geometry of an injector to create a flow of supersonic velocity of the oxygen-containing gas stream; entraining the flow of the oxygen-containing gas with a stream of fluidized carbon-based particulates to produce a combined jet stream having a supersonic velocity designated as a supersonic fluidized carbon jet; expanding the supersonic fluidized carbon jet to atmospheric pressure and ejecting the supersonic fluidized carbon jet from an outlet of the injector; surrounding the supersonic fluidized carbon jet with an oxy-fuel shroud created at the outlet of the injector to produce the combined coherent supersonic jet stream; and flowing the combined coherent supersonic jet stream from the outlet of the injector to the liquid pool.

BRIEF DESCRIPTION OF THE DRAWINGS

The objectives and advantages of the invention will be better understood from the following detailed description of the preferred embodiments thereof in connection with the accompanying figures wherein like numbers denote same features throughout and wherein:

FIG. 1a shows a representative cross-sectional schematic of an injector apparatus utilized in the co-injection method of the present invention having a specific geometry for its converging/diverging nozzle geometry;

FIG. 1b shows an enlarged section of FIG. 1a along the converging/diverging nozzle geometry;

FIG. 1c shows an end view of the injector apparatus of FIG. 1a having an inner ring of holes for the shroud fuel to flow therein and an outer ring of holes for the shroud oxygen to flow therein, wherein the inner ring of holes extend along a first radius that is smaller than the outer ring of holes that extend along a second radius;

FIG. 2a shows another representative cross-sectional schematic of an injector apparatus having a specific geometry for its converging/diverging nozzle geometry in accordance with the principles of the present invention;

FIG. 2b shows an enlarged section of FIG. 2a along the converging/diverging nozzle geometry;

FIG. 3a shows another representative cross-sectional schematic of an injector apparatus having a specific geometry for its converging/diverging nozzle geometry in accordance with the principles of the present invention;

FIG. 3b shows another representative cross-sectional schematic of an injector apparatus having a specific geometry for its converging/diverging nozzle geometry in accordance with the principles of the present invention;

FIG. 4 shows an end view of an alternative design for an injector apparatus with an inner slot for fuel and an outer ring of holes for oxygen that from the oxy-fuel shroud in accordance with the principles of the present invention;

FIG. 5 shows an injector apparatus mounted to a furnace sidewall in usage as part of an electric arc furnace (EAF) process, in accordance with the principles of the present invention, whereby a combined coherent supersonic jet stream of carbon particulates and oxygen-containing gas is directed to a liquid molten pool;

FIG. 6a shows usage of the injector apparatus of the present invention to inject a combined coherent supersonic jet stream of carbon particulates with an oxygen-containing motive gas stream in accordance with the methods of the present invention; and

FIG. 6b shows usage of a conventional injector apparatus to inject a fluidized supersonic stream of carbon particulates and a conventional injector apparatus to separately inject oxygen in accordance with conventional techniques.

DETAILED DESCRIPTION OF THE INVENTION

The relationship and functioning of the various elements of the embodiments are better understood by the following detailed description. The detailed description contemplates the features, aspects and embodiments in various permutations and combinations, as being within the scope of the disclosure. The disclosure may therefore be specified as comprising consisting or consisting essentially of any of such combinations and permutations of these specific features, aspects and embodiments, or a selected one or ones thereof.

Where a range of values describes a parameter, all sub-ranges, point values and endpoints within that range or defining a range are explicitly disclosed therein. All physical property, dimension, and ratio ranges and sub-ranges (including point values and endpoints) between range end points for those physical properties, dimensions, and ratios are considered explicitly disclosed therein.

The drawings are for the purpose of illustrating the invention and are not intended to be drawn to scale. The embodiments are described with reference to the drawings in which similar elements are referred to by like numerals. Certain features may be intentionally omitted in each of the drawings to better illustrate various aspects of the operation of the injector assembly, in accordance with the principles of the present invention. The embodiments are described by way of example only, and the invention is not limited to the embodiments illustrated in the drawings.

As used herein and throughout, the term “coherent” or “coherency” means a stream that can substantially maintain 90% or greater of its original velocity, diameter, concentration and momentum for distances of at least 20-70 nozzle diameters, as measured from the nozzle diameter of the injector outlet.

“Combined coherency” as used herein and throughout refers to a coherency of two or more streams, and by preferred non-limiting example, includes a first stream of fluidized carbon-based particulates intermixed with a second stream of an oxygen-containing motive gas stream.

As used herein and throughout, “nozzle diameter” means the equivalent diameter at the outlet of the injector nozzle.

As used herein and throughout, the term “liquid pool”, “liquid bath”, “bath” “molten bath”, “molten metal bath” and “steel bath” shall be used interchangeably and have the same meaning.

As used herein and throughout, the term “oxy-fuel shroud” means a combusting stream that is at least partially surrounding a supersonic gas jet, such as a multi-phase solids/gas stream comprising carbon-based particulates and an oxygen-containing gas. “Oxy-fuel shroud” and “oxy-fuel flame shroud” may be used interchangeably herein and throughout and are intended to have the same meaning.

As used herein and throughout, the term “multi-phase solids/gas stream” means a combined stream of fluidized solids intermixed or entrained within a gas stream.

As used herein and throughout, the term “supersonic velocity” is intended to refer to a stream whose velocity is greater than the local speed of sound and determined as having a Mach number greater than one.

“Critical pressure” as used herein and throughout refers to the downstream pressure at which choked flow occurs.

“Fuel” as used herein and throughout refers to any carbonaceous or non-carbonaceous fuel in either a liquid or gaseous phase.

“Supersonic flow” and “supersonic” as used herein and throughout may be used interchangeably and are intended to have the same meaning of a stream having supersonic velocity.

The present invention has emerged as a result of the failure of conventional lances to effectively accelerate solids and deliver them a distance from the wall of a furnace to a liquid pool, with sufficient momentum to traverse the distance without dispersing, thereby enabling the solids to impinge and/or penetrate into the liquid pool contained within the furnace during applications, such as a steelmaking operation. The present invention in one aspect offers a solution for accelerating particulates such as carbon-based particulates and injecting the particulates into the slag, molten liquid and/or slag-molten liquid interface layer, such as are present in steel furnaces, including electric arc furnaces. Solids such as carbonaceous (i.e., carbon-based particulates) materials can be effectively injected into the slag, molten liquid and/or slag-molten liquid interface with the method and apparatus of the present invention.

The present invention, in one aspect, is directed to a method for introducing carbon-based particulates with oxygen-containing gas to produce a combined coherent supersonic jet stream, and an injector apparatus for carrying out the method. The present invention can maintain the coherency of the combined supersonic jet stream for a sufficient distance, which is measured from the exit of the injector nozzle. As will be discussed herein below, in a preferred embodiment, an oxy-fuel shroud is created at the outlet of the injector apparatus and thereafter utilized to maintain the coherency of the combined supersonic jet stream.

As will be discussed, the present invention, in one aspect, is directed to an injector apparatus 10 that is mounted on a wall of a furnace 50 (as exemplary shown in FIG. 5) that is configured to generate a supersonic jet of fluidized carbon-based particulates in an oxygen-containing gas for delivery into a liquid pool, slag layer or slag-liquid pool interface. The process involves mixing a stream of fluidized carbon-based particulates 20 into an oxygen-containing motive gas stream 30 and accelerating the resultant stream to produce a supersonic fluidized carbon jet 31 that is directed from the outlet 13 of the injector apparatus 10 as a combined coherent supersonic jet stream 22 towards and into a liquid pool 40, slag layer 39 or slag-liquid pool interface 41 (FIG. 6a).

Referring to FIG. 1a, the fluidized carbon-based particulate stream 20 is preferably pneumatically conveyed with air into the inlet 14 of injector apparatus 10. Preferably, the injector apparatus 10 is mounted on the wall of the furnace 50 above the bath, such as a steelmaking furnace (e.g., as shown by representative FIG. 5). The injector apparatus 10 is spaced apart a certain vertical distance from the surface of the slag and underlying molten bath. The injector apparatus 10 has a first inner channel 70 preferably extending along a central axis of the apparatus 10. The first inner channel 70 receives the fluidized carbon-based particulate stream 20, which is fed to inlet 14. The first inner channel 70 extends from the inlet 14 to an outlet that terminates inside the injector apparatus 10, upstream of a mixing section 15. The injector apparatus 10 further includes a second inner channel 71 that is outwardly and radially spaced apart from a central axis of the first inner channel 70. The second inner channel 71 can be arranged co-axial to the first inner channel 70. The second inner channel 71 serves to receive an oxygen-containing motive gas stream 30 at the inlet 14 of the injector 10. The oxygen-containing motive gas stream 30 is fed into inlet 14 of second inner channel 71 at a higher pressure relative to the supply pressure of the fluidized carbon-based particulate stream 20 and becomes accelerated by expansion across a converging/diverging 16 geometry to a supersonic velocity. The oxygen-containing motive gas stream 30 serves as the motive stream to entrain, mix and accelerate the fluidized, carbon-based particulate stream 20 to a supersonic velocity. The second inner channel 71 includes the converging/diverging nozzle element 16. The converging geometry of the converging/diverging geometry 16 leads to a restriction which serves to choke the pressurized oxygen-containing motive gas stream 30 to its critical pressure. Downstream of the choke point, the diverging geometry of the converging/diverging geometry 16 is characterized by an expansion geometry designed to expand the oxygen-containing motive gas stream 30 stream and thereby accelerate it to supersonic velocity. The diverging geometry of converging/diverging geometry 16 has edges that are substantially straight (as more clearly seen in FIG. 1b).

FIG. 1b shows an enlarged section of FIG. 1a along the converging/diverging geometry. FIG. 1b shows that the diverging geometry of the converging/diverging geometry 16 has two straight surfaces where the arrows represent the flow profile of the oxygen-containing motive gas stream 30 flowing therethrough. One of the surfaces is slanted downwards to enhance mixing and to expand the oxygen-containing motive gas stream 30. The cross-sectional area increases in the diverging section. The converging/diverging nozzle element 16 is placed as far as possible towards the outlet 13 of the injector apparatus 10 to avoid creation of supersonic flow of the fluidized, carbon-based particulate stream 20 through the injector apparatus 10. Premature acceleration of the fluidized, carbon-based particulate stream 20 through the injector apparatus 10 has the potential to cause wear of the injector apparatus 10 and loss of momentum of the fluidized, carbon-based particulate stream 20 before it exits the outlet 13 of the injector apparatus 10.

Referring to FIG. 1a, after the oxygen-containing motive gas stream 30 has exited the diverging section of the converging/diverging geometry 16 as a supersonic velocity stream, it enters the “mixing section” 15 to mix with fluidized carbon-containing particulate stream 20, with both streams 20 and 30 at substantially the same pressure. The oxygen containing motive gas stream 30 is partially expanded into the “mixing section” 15 to such pressure which is substantially equal to the pressure of the fluidized carbon containing particulate stream 20 at the location where said stream 20 exits the first inner channel 70 and enters the mixing section 15; but greater than the ambient pressure at the outlet 13 of the injector apparatus 10. In a preferred embodiment, the substantially matched pressures of streams 20 and 30 range between 5 psi(g) and 20 psi(g). By having the pressure of the oxygen-containing motive gas stream 30 in mixing section 15 substantially match the pressure of the incoming fluidized carbon-containing particulate stream 20, the risk of any backflow of the oxygen-containing motive gas stream 30 into the carbon passageway (i.e., first inner channel 70) is minimized or eliminated.

The relatively slower (i.e., flowing at subsonic velocity) fluidized carbon-containing particulate stream 20 is mixed with the supersonic velocity oxygen-containing motive gas stream 30 in the mixing section 15, and, subsequently, the fluidized carbon-containing particulate stream 20 is accelerated to supersonic velocity as it flows, with oxygen-containing motive gas stream 30, through the “Straightening/acceleration section”17. In this manner, the fluidized carbon-containing particulate stream 20 is accelerated to a supersonic fluidized carbon jet 31 as it flows through the Straightening/acceleration section 17 and then exits the outlet 13 of the injector apparatus 10. The pressure of the supersonic fluidized carbon jet 31 inside the Straightening/acceleration section 17 is reduced to match the ambient pressure at the outlet 13 of the injector apparatus 10. Subsequent formation of the oxy-fuel shroud 21 (the details of which will be explained hereinbelow) at the outlet 13 of the injector apparatus 10 creates a combined coherent supersonic jet stream 22 that is directed towards the liquid pool 40, slag layer 39 and/or slag-liquid pool interface 41 (FIGS. 5 and 6a).

The injector apparatus 10 further includes a first outer passageway 73 for receiving an oxygen gas stream 74 (designated as “shroud oxygen” in FIG. 1a). FIG. 1a shows first outer passageway 73 is radially spaced apart from the central axis of the injector apparatus 10 a distance greater than a distance the second inner channel 71 is spaced apart from the central axis. It should be understood that in an alternative design, the first outer passageway 73 can be spaced apart the same distance as that of the second inner channel 71. The first outer passageway 73 serves to receive oxygen that is used to create an oxy-fuel shroud 21 at the outlet 13 of the injector apparatus 10 by combusting with shroud fuel 75 exiting outlet of the second outer passageway 72 (described hereinbelow). The oxy-fuel shroud 21 surrounds the inner positioned supersonic fluidized carbon jet 31. The first outer passageway 73, in one embodiment, extends substantially parallel to the central axis and along the entire axial length of the injector apparatus 10.

Second outer passageway 72 is also provided for receiving a fuel gas stream 75 (designated as “Shroud Fuel” in FIG. 1a). The second outer passageway 72 is radially spaced apart from the central axis. The second outer passageway 72 and first outer passageway 73 are shown spaced apart in FIG. 1a. The second outer passageway 72 is shown to extend substantially parallel to the central axis and along the entire axial length of the injector apparatus 10.

FIG. 1c shows an end view of the outlet 13 of the injector apparatus 10 of FIG. 1a. There are multiple outlet ports 91 to feed shroud fuel 75 and multiple outlet ports 92 to feed shroud oxygen 74. It should be understood that outlet ports 91 extend into the injector 10 as second outer passageways 72 (FIG. 1a), and outlet ports 92 extend into the injector 10 as first outer passageways 73 (FIG. 1a). FIG. 1c shows that the multiple ports 91 for shroud fuel 75 extend along a first radius to form a first inner ring-like structure, where the first radius is the radial distance from each of the ports 91 to the central axis of the injector 10. The multiple ports 92 for shroud oxygen 74 extend along a second radius to form a second outer ring-like structure, where the second radius is the radial distance from each of the ports 92 to the central axis of the injector 10. The second radius is greater than the first radius. The multiple outlet ports 91 extend along the first radius to form an inner ring-like structure, whereby multiple outlet ports are shown equally spaced along the first radius. The multiple outlet ports 92 extend along the second radius to form an outer ring-like structure, whereby multiple outlet ports 92 are shown equally spaced along the second radius. Such spatial arrangement can provide more uniform combustion of the shroud oxygen gas 74 with the fuel 75 at the outlet 13 of the injector apparatus 10 to effectively form the oxyfuel shroud 21. While not shown, it should be understood the multiple outlet ports 92 for the shroud fuel 75 can alternate with the multiple inlet ports 91 for the shroud oxygen 74 where both ports 91 and ports 92 are spaced apart from the central axis by the same radius to form a single ring-like structure. It should be understood any number and size of inlet ports 91 and 92 sufficient to implement the methods of the present invention can be utilized.

In an alternative embodiment, the inlet for the first outer passageway 73 and/or the inlets for the second outer passageway 72 can be comprised of ports to form a ring of holes and/or a slotted geometry to improve efficacy of the oxy-fuel shroud 21. The slotted geometry can be straight or swirled. By way of non-limiting example, FIG. 4 shows an injector apparatus 100 having multiple outlet ports 92 to form an outer ring-like structure for the shroud oxygen 74 and an inner slot-like structure for the fuel shroud 75. The shroud oxygen 74 is fed into the series of outlet ports 92 and the fuel shroud 75 is fed into the inner slot 93, which is shown to circumferentially extend in a continuous manner along the inlet of injector 10. The corresponding second outer passageway 72 for inner slot 93 can have a swirl-like or straight geometry, while the corresponding first outer passageway 73 for the oxygen shroud 74 remains as a substantially straight passageway as shown in FIG. 1a. The supersonic fluidized carbon jet 31 flows through the center of injector 10.

The outlet 13 of the injector apparatus 10 is operably connected to an optional recirculating device 82 that creates a recirculation of the shroud oxygen 74 and shroud fuel 75 that can enable enhanced mixing and combustion to form oxy-fuel shroud 21 (FIGS. 1a, 2a and 3a). The recirculation device 82 is structurally configured to anchor the oxy-fuel shroud 21 and promote stabilization of the oxy-fuel shroud 21.

FIG. 5 shows one embodiment where the injector apparatus 10 is connected to a furnace 50. The injector apparatus 10 is angled downwards towards the liquid bath 40 at approximately 45 degrees relative to a horizontal traversing the wall of the furnace 50. The exact angled orientation of the injector apparatus 10 will depend on a combination of factors, including the geometry of the furnace 50; avoidance of impingement of the supersonic fluidized carbon jet 31 with the electrodes of furnace 50; avoidance of impingement of the supersonic fluidized carbon jet 30 with the wall and shelf of the furnace 50; and the reduction, minimization, or elimination of splashing of the liquid bath 40, interface 41 and/or slag 39 onto one or more surfaces of the injector apparatus 10 created upon the oxygen-containing motive gas 10 and the fluidized carbon-based particulate stream 20 (i.e., the combined coherent supersonic jet stream 22) being directed and penetrating into the liquid bath 40, interface 41 and/or slag 39.

Having described the structural features of the injector apparatus 10, an exemplary method of operating the injector apparatus 10 will now be described. In a preferred embodiment, the injector apparatus 10 is utilized to inject a fluidized carbon-based particulate stream 20, with an oxygen-containing gas 30, to create a combined coherent supersonic jet 22 into a molten metallic bath 40, slag layer 30 and/or bath-slag interface 41 as part of a metallurgical process, such as an electric arc furnace (EAF) process. Generally speaking, an EAF process can be employed to melt metal such as steel for subsequent refinement. The EAF typically has one electrode, in the case of the DC furnace, or three electrodes, in the case of an AC furnace, which pass through the furnace roof and are centrally arranged within the furnace to provide electrical energy to heat and melt the metal. The global usage of EAFs is increasing as more scrap metal is required to be recycled. In a typical EAF process, oxygen is typically injected to oxidize impurities in the steel molten bath 40 which report to the slag layer 39 floating on the surface of the molten steel bath 40 (FIG. 6a). The slag layer 39 is subsequently removed to improve the purity and quality of the steel. During the refining phase of the process, the slag layer 39 is utilized to insulate the molten steel bath 40 so as to control the electric arc, minimize heat losses from the molten steel bath 40, and to protect the molten steel bath 40 bath from hydrogen and/or nitrogen pick up from the atmosphere in the freeboard of the furnace 50. During the process, the iron is also undesirably oxidized through the use of oxygen, and, hence, needs to be chemically reverted back to metallic iron by undergoing a reduction reaction by the addition of carbon, which acts as a reductant. The co-injection of the carbon-containing particulates and the oxygen-containing gas can occur more efficiently and with better control and precision within substantially the same local vicinity of the liquid pool than previously possible by using separate carbon lances and oxygen lances. Hence, as will be described herein, the present invention offers an efficient process for carrying out both of these complimentary metallurgical reactions simultaneously, thereby allowing iron to be preserved while impurities are oxidized and thereafter removed.

Referring to FIG. 1a, carbon-based particulates 20 are pneumatically fed with air at inlet 14 of injector apparatus 10 into a dedicated first inner channel 70 to form a fluidized carbon-based particulate stream 20. The injector apparatus 10 is mounted to a wall of a furnace 50 (e.g., EAF) as shown in FIG. 5. The injector 10 is shown oriented at approximately 45 degrees relative to a horizontal traversing the wall of the furnace 50. For purposes of simplicity, the structural details of the furnace 50 have been omitted from FIG. 5 to better illustrate the method of operation in accordance with the principles of the present invention. The first inner channel 70 extends along a central axis of the injector apparatus 10. The fluidized carbon-based particulate stream 20 flows at subsonic velocities through the first inner channel 70 without intermixing with the shroud fuel 75 or shroud oxygen 74 that form the oxy-fuel shroud 21. The fluidized carbon-based particulate stream 20 then enters an inlet to the mixing section 15.

An oxygen-containing motive gas stream 30 is introduced at inlet 14 of the injector apparatus 10 into a dedicated second inner channel 71 spaced apart radially outward from the first inner channel 70. The oxygen-containing motive gas stream 30 is introduced at a relatively higher pressure than the supply pressure of the fluidized carbon-based particulate stream 20. In one example, the oxygen-containing motive gas stream 30 is supplied to the inlet 14 of the injector 10 of first inner channel 71 at a pressure greater than about 100 psig while the fluidized carbon-based particulate stream 20 is fed at about 15 psig. The oxygen-containing motive gas stream 30 flows through the second inner channel 71 and then into a constriction or throat of the converging/diverging geometry 16, where its flow becomes compressed and choked. Downstream of the throat, the choked and compressed oxygen-containing motive gas stream 30 is partially expanded through a diverging section (shown in enlarged view in FIG. 1b) of converging/diverging geometry 16. The gas expansion causes the oxygen-containing motive gas stream 30 to accelerate from a subsonic stream to a supersonic velocity jet stream. The partial expansion of stream 30 as it flows through diverging section is controlled to achieve a pressure that matches the pressure of the fluidized carbon-based particulate stream 20 exiting the outlet of first inner channel 70.

The supersonic flow of oxygen-containing motive gas stream 30 exits the diverging section of converging/diverging geometry 16 and then flows into the mixing section 15 of injector 10. The supersonic flow of oxygen-containing motive gas stream 30 entrains and intermixes with the relatively lower velocity fluidized carbon-based particulate stream 20 that separately enters mixing section 15 from the outlet of the first inner channel 70. The supersonic oxygen-containing motive gas stream 30 accelerates the fluidized carbon-based particulate stream 20 through the mixing section 15 and then through a straightening/acceleration section 17 so that the streams 30 and 20 are combined to produce a resultant supersonic fluidized carbon-based particulate jet 31. The resultant supersonic fluidized carbon-based particulate jet 31 exits the outlet 13 of the injector apparatus 10.

An oxy-fuel shroud 21 is formed at the outlet of the injector apparatus 10 which surrounds the supersonic fluidized carbon-based particulate jet 31 to impart the desired coherency to the supersonic fluidized carbon jet 31. The supersonic fluidized carbon-based particulate jet 31 is directed towards liquid pool 40 as a combined coherent supersonic jet 22 that is representatively shown in FIG. 5.

The system and methods of the present invention are specifically carried out such that formation of the oxy-fuel shroud 21 does not occur within the injector apparatus 10. Rather, formation can only occur at the outlet 13 of the injector apparatus 10, starting within an optional recirculation zone and device 82, as shown in FIG. 1a. In this regard, a carbonaceous fuel 75 or shroud fuel (e.g., natural gas) flows through the multiple shroud fuel ports 91 (shown in FIG. 1c) and then the carbonaceous fuel 75 flows through corresponding second outer passageways 72 of the injector apparatus 10. Preferably, the flow of the carbonaceous fuel 75 is uniformly distributed around the outlet ports 91 the outlet 13 of injector 10. As shown in FIG. 1c, which is an end view of FIG. 1a and showing the outlet face of the injector apparatus 10, the carbonaceous fuel 75 flows and is distributed through multiple ports 91, each of which is located a predetermined radial distance from the central axis of the injector 10 and that collectively form an inner concentric ring which is located radially outward of the outlet for the oxygen-containing motive gas stream 30 and the outlet for the fluidized carbon-based particulate stream 20. The carbonaceous fuel 75 is preferably evenly distributed through the multiple outlet ports 91. Prior to exiting through ports 91, the carbonaceous fuel 75 subsequently flows at a designated subsonic velocity through second outer passageways 72. The carbonaceous fuel 75 flows through the second outer passageways 72 without intermixing with inner oxygen-containing motive gas stream 30 and the fluidized carbon-based particulate stream 20 that also are flowing through the injector apparatus 10 through their respective channels 71 and 70.

Additionally, FIG. 1c shows shroud oxygen 74 flows into multiple outlet ports 92, each of which is located at a predetermined radial distance from the central axis of injector, where the predetermined radial distance of each of the multiple outlet ports 92 is greater than that of the multiple outlet ports 91. The multiple outlet ports 92 collectively form an outer concentric ring. The shroud oxygen 74 is preferably uniformly distributed through the multiple outlet ports 92. Prior to exiting through ports 92, the shroud oxygen 74 flows at a designated subsonic velocity through corresponding second outer passageways 73 of the injector apparatus 10. The shroud oxygen 74 flows through second outer passageways 73 without intermixing with inner oxygen-containing motive gas stream 30 and the fluidized carbon-based particulate stream 20 both of which flow through the injector apparatus 10. FIG. 1c shows that the dedicated multiple outlet ports 91 for carbonaceous fuel 75 and dedicated multiple outlet ports 92 for shroud oxygen gas 74 are arranged in an alternating manner along an inner ring and outer ring, respectively, to ensure that upon exiting the injector apparatus 10, optimized mixing and combustion of the multiple carbonaceous fuel streams 75 with the multiple shroud oxygen gas streams 74 can occur.

Referring to FIG. 1a, the oxygen streams 74 emerge from the outlet 13 of the injector 10 on the outside relative to the fuel streams 75 to enable the fuel stream 75 to react with the shroud oxygen 74 on the exterior to optimize the formation of an oxy-fuel flame shroud 21.

In this manner, the oxy-fuel shroud 21 is intentionally not formed until both the aggregate of the multiple distributed carbonaceous fuel streams 75 and the multiple distributed shroud oxygen gas streams 74 emerge from the outlet 13 of the injector apparatus 10, thereby avoiding internal mixing of the shroud fuel 75 with the shroud oxygen 74 and potential formation of combustive mixture and/or reaction within the injector 10 which can cause overheating of the injector 10. Furthermore, the shroud oxygen 74 and shroud fuel 75 can mix to form a shroud mixture within an optional recirculation zone and device 82 that is created by a cylindrical volume connected to the exit of the injector apparatus 10. Without being bound by any theory, the shroud mixture may be further stabilized, thereby resulting in a longer coherency of the combined coherent supersonic jet 22 than possible with a partially reacted shroud ring of combusting gases exiting an injector that does not have a recirculation zone and device 82.

In another arrangement, the exit ports for the shroud oxygen 74 and shroud fuel 75 can be manifolded and distributed so that the shroud oxygen 74 and shroud fuel 75 emerge along the same radial location.

The carbonaceous fuel 75 and shroud oxygen 74 streams are in close proximity to each other by virtue of the alternating arrangement of inlet ports 91 and 92 corresponding to dedicated passageways 72, 73 for the carbonaceous fuel 75 and shroud oxygen 74, respectively, as discussed hereinabove and shown in FIG. 1c. The close spatial arrangement of the streams 74 and 75 facilitates sufficient mixing and combustion of the carbonaceous fuel 75 to form the oxy-fuel shroud 21 at the outlet 13 of the injector apparatus 10 and within the interior volume of the EAF as both streams 74 and 75 exit the outlet 13 of the injector 10. The oxy-fuel shroud 21 is formed and then surrounds the supersonic fluidized carbon jet 31. The oxy-fuel shroud 21 has a velocity less than that of the combined coherent supersonic jet stream 22.

Referring to FIG. 6a, the oxy-fuel shroud 21 sufficiently surrounds the combined coherent supersonic jet stream 22 and preserves the coherency of the combined coherent supersonic jet stream 22 allowing it to pass from the outlet 13 of the injector apparatus 10 towards the liquid pool 40, slag layer 39 or slag-liquid pool interface 41. In particular, the coherency is preserved, whereby the original velocity, diameter, momentum and gas concentration of the combined coherent supersonic jet stream 22 remains substantially unaltered for distances of at least about 30 nozzle diameters, and preferably between approximately 30 to 70 nozzle diameters, as measured from the nozzle outlet 13 of the injector 10. The conditions in the atmosphere of the EAF 50 and liquid pool 40 do not disrupt the coherency of the combined coherent supersonic jet stream 22. In this manner, the coherency of the combined coherent supersonic jet stream 22 is maintained.

Still referring to FIG. 6a, the combined coherent supersonic jet stream 22 is directed from the outlet 13 of the injector 10 towards the liquid pool 40, slag layer 39 or slag-liquid pool interface 41. The tip of the injector apparatus 10 can be spaced apart from the liquid pool 40 a sufficient distance to considerably reduce, minimize or entirely avoid splashing of the slag 39 and liquid pool 40 upwards onto surfaces of the opposite walls of the furnace 50 while still allowing substantially all of the carbon-based particulates (i.e., stream 20) and oxygen-containing motive gas stream 30 to be directed into the slag 39 and liquid pool 40 at controlled locations therein to carry out the required metallurgical reactions. In one example, the tip of the injector apparatus 10 is spaced away from the surface of the liquid pool at least 30 diameters of the injector exit diameter and up to about 70 diameters of the injector exit diameter, whereby substantially all of the carbon-based particulates 20 and oxygen-containing gas 30 fed to injector 10 are directed to the liquid pool 40, slag layer 39 or slag-liquid pool interface 4.

FIG. 6a shows that the combined coherent supersonic jet stream 22 impacts the surfaces of the slag 39, interface 41 and/or the liquid pool 40 as a combined coherent stream before undergoing jet decay or jet spreading. The oxy-fuel shroud 21 preserves the coherency of the combined coherent supersonic jet stream 22 and as a result enables both the oxygen-containing motive gas stream 30 and the fluidized carbon-based particulate stream 20 to reach and penetrate the slag 39, slag/metal interface 41 and/or liquid pool 40. The metallic impurities are oxidized by the oxygen-containing motive gas stream 30 while iron oxide in the steel is reduced back to elemental iron by the fluidized carbon-based particulate stream 20. The methods of the present invention are notably in contrast to conventional methods. In this regard, FIG. 6b shows separate injectors arranged side-by-side for directing separate jet streams of carbon and oxygen to the liquid pool. FIG. 6b shows the carbon has a tendency to be partially dispersed before reaching the bath/slag interface (designated as “carbon losses”). Such conventional carbon injectors have insufficient efficacy or momentum and thus rapidly deteriorate leading to substantial drop-off in their respective velocities as the carbon stream flows towards the liquid pool. For example, the coherencies of the carbon injector can be substantially diminished within about 3 to about 4 nozzle diameters, as measured from the nozzle diameter of the injector outlet, thereby resulting in potentially 50% of the initial amount of carbon fed to the injector being lost to the fume system.

It should be understood that the present invention can allow the carbon-based particulates and oxygen-containing gas to penetrate any depth with control and precision into the slag and liquid pool whereby the carbon-based particulates and oxygen-containing gas can participate in the complimentary metallurgical reactions in substantially the same local vicinity. The depth into the liquid pool that the carbon-based particulates and oxygen penetrate can be controlled at least in part by varying the velocity of the oxy-fuel shroud and/or the or the velocity of the oxygen gas that combusts with the carbonaceous fuel.

The combined coherent supersonic jet stream 22 is not adversely impacted by the operating conditions of the furnace 50 and the liquid bath 40 as combined coherent supersonic jet stream 22 is directed towards the liquid pool 40, slag layer 39 or slag-liquid pool interface 41 as a result of the coherency of stream 22 that is maintained by the oxy-fuel shroud 21 extending substantially continuously therearound. In particular, the concentration, velocity, momentum and diameter of the combined coherent supersonic jet stream 22 is substantially preserved relative to its values of concentration, velocity, momentum and diameter at the outlet of the injector 10. In one non-limiting example, the coherency of the combined coherent supersonic jet stream 22 remains intact for a distance measured from an exit nozzle of injector 10 to a surface of the liquid pool (L) equal to at least about L/D=50, which is significantly longer than conventional carbon-based jet streams being injected into the liquid pool using a conventional injector (FIG. 6b), which generally has a L/D of about 3 to 4.

Modifications are contemplated to the present invention without departing from the scope therein. For example, the diverging geometry of the converging/diverging geometry 16 can include functionally equivalent devices configured to reduce the incidence of shock waves by expanding the oxygen-containing motive gas stream 30 over an optimized geometry on one or more surfaces. The diverging geometry can be characterized as an expansion fan, whereby the pressurized oxygen-containing motive gas stream 30 is accelerated around a corner or curve. One example is a so-called aerospike geometry where the oxygen-containing motive gas stream 30 is expanded around an expansion corner that is rotated away from the central axis of the converging/diverging geometry 16. In another example, an expansion-deflection nozzle can be utilized where the oxygen-containing motive gas stream 30 is expanded around an expansion corner such that the expansion is rotated towards the center-line of the converging/diverging geometry 16. FIGS. 2b and 3b show one of the surfaces along the expansion section of converging/diverging geometry 16 that is curved to create an expansion fan. Alternatively, both surfaces can be curved. The curving of the expansion surfaces allows the flow profile as shown by the flow arrows of the expanding oxygen-containing motive gas stream 30 to be angularly rotated (counterclockwise as shown in FIG. 2b or clockwise as in FIG. 3b) to create a resultant flow that enhances mixing. The so-called “expansion corner(s)” can be sharp (as labelled and shown in FIGS. 2b and 3b) or can be configured as rounded to avoid turbulence of the gas flows. Other suitable injector nozzle structural designs with a converging/diverging structural element can be utilized that is capable of creating a supersonic flow of oxygen-containing gas upon gas expansion in one of the passageways of the injector apparatus 10.

While the carbonaceous fuel may comprise any suitable fuel, and most preferably comprises natural gas, it should be understood that in other embodiments, the fuel may not utilize a carbonaceous fuel. In particular, by way of example, the non-carbonaceous fuel may include hydrogen or ammonia. It should also be understood that the fuel can be liquid or gaseous. Still further, while the process has been described utilizing a single injector apparatus, it should be further understood that multiple injector apparatuses may be used to practice the present invention. The multiple injectors may be arranged on the sidewalls of the EAF along its circumference with the exact number of injectors depending on numerous factors, including, but not limited to, the required injection rate of the carbon-containing particulates, the size of the furnace and furnace productivity in terms of the rate of steel produced.

Furthermore, while the preferred embodiment has disclosed the carbon-based particulate stream flowing through a first inner passageway that is substantially extending along a central axis, other flow arrangements between the oxygen-containing gas stream and the carbon-based particulate stream can be used to create a resultant multi-phase solids/gas jet stream that is supersonic at the outlet of the injector apparatus. For example, the first inner channel for the carbon-based particulates can be spaced apart from the central axis while the oxygen-containing gas flows within a second inner channel that is located along the central axis and thus situated inwards relative to the carbon-based particulate stream.

While in a preferred embodiment, the multi-phase solids/gas jet stream is a supersonic fluidized carbon jet stream 31 that travels towards the liquid pool 40, slag layer 39 or slag-liquid pool interface 41 as a combined coherent jet stream 22 within oxy-fuel shroud 21 (FIG. 6a) and is composed substantially of carbon particulates and oxygen-containing motive gas, it should be understood that the multi-phase solids/gas jet stream can be a combined coherent stream 22 that may also contain other gases, liquids, and/or particulates without departing from the scope of the present invention. For example, CO2 as the motive stream and liquid organic material can be utilized to form a combined coherent stream 22 that is directed towards a molten bath. Additionally, the multi-phase solids/gas jet stream can be composed entirely of a single phase having an oxidizing stream and a reducing stream, both of which are in the same phase, and whereby the reducing stream is entrained and mixes with the oxidizing stream at the outlet of the injector apparatus.

Carbon-based particulates can be any carbon-based material, including, but not limited to, petroleum coke, charcoal, plastics, rubber, and biomass. Additionally, any suitable reducing stream can be utilized besides carbon-based particulates. In one example, natural gas is utilized as the reducing stream instead of carbon-based particulates.

While an oxygen-containing gas such as oxygen gas is preferably used as the motive gas in the present invention, any suitable carrying gas can be utilized besides an oxygen-containing gas, including, any of, or mixture of nitrogen, argon, carbon dioxide, and the like.

The present invention offers numerous benefits. For example, the versatility of the injector apparatus allows it to be operated in several modes. In one mode, the injector apparatus 10 may be operated solely as a supersonic oxygen injector without requiring the flow of carbon-based particulates. In another mode, the injector apparatus 10 can be operated in a burner mode for heating and melting scrap material where an oxy-fuel flame is used to heat and melt the scrap before a refining phase. When the injector apparatus operates in burner mode, the fuel stream is burned by just enough oxygen split between the inner “motive” jet and the outer shroud oxygen. Burner mode is used during melting to heat and melt scrap in the furnace. In a third mode, a supersonic mixture of oxygen and carbon particulates are accelerated through the injector for the purpose of generating a foaming slag. The ability for the injector apparatus 10 to be operated as a multipurpose device offers an efficient solution through a single port into the furnace resulting in less maintenance compared to other multi-port injection technologies that exist prior to emergence of the present invention. When the injector operates in injector mode (either only oxygen or oxygen/carbon, the motive oxygen stream significantly exceeds the amount of oxygen required (e.g., by a factor of ten times) to burn the shroud fuel. The injector mode is used during refining applications.

It should also be appreciated that the present invention allows the effective addition of additives or reagents in solid phase through a first passageway (along the central axis) of the injector apparatus and thereby eliminates the need to employ conventional processes and equipment for particulate solid injection into iron or steel, such as lances, which can wear out and are expensive. The single injector also requires less port holes to be created in the furnace sidewalls, thereby reducing furnace maintenance.

Another benefit the present invention offers is greater carbon-based particulate yield as a result of reducing, minimizing or eliminating the loss of carbon-based particulates that are fed into the injector apparatus 10. Due to the greater momentum imparted to the fluidized carbon jet by the motive gas, more of the carbon-based particulates can be transported to the bath/slag interface 41 (FIG. 6a) in comparison to conventional methods that use a separate carbon and oxygen lance without a flame envelope shroud on the carbon lance (FIG. 6b). In one example, the present invention allows more than 50-60 wt % of the carbon, preferably 60-70 wt % and more preferably 80 wt % or greater of the carbon feedstock to be transferred to the bath/slag interface. Additionally, finer carbon (which is relatively inexpensive compared to pulverized coal), including, but not limited to, petroleum coke, can be used in the present invention as a result of the coherency of the multi-phase solids/gas jet stream being maintained from the outlet of the injector into the liquid pool. On the contrary, prior to the present invention, finer carbon particulates typically do not have sufficient momentum and hence can be undesirably discharged through the exhaust vacuum system of the furnace, as representatively shown in FIG. 6b. Hence, a substantial portion of the carbon particulates introduced into the furnace cannot participate in the desired metallurgical reactions during an EAF process.

Additionally, in the present invention, the oxy-fuel shroud surrounding the supersonic fluidized carbon jet stream maintains sufficient coherency so as to prohibit unwanted dispersion of the carbon-based particulates and oxygen-containing gas contained therein. This is in contrast to injection of carbon-based particulates and oxygen-containing gas without a shroud, which results in dispersion occurring a relatively short distance from the outlet of their respective lances, which can be 3-4 nozzle diameters of the lance tip.

Still further, the present invention allows the carbon-based particulates and the oxygen-containing gas to be injected into the liquid pool, slag layer or slag-liquid pool interface in substantially the same local vicinity. As a result, the iron product that is undesirably oxidized to iron oxide by the oxygen-containing gas can be converted back to iron product by the carbon-based particulates being injected in substantially the same local vicinity as the oxygen-containing gas, thereby reducing the iron oxide to iron, which results in increased product yield during the EAF process.

Still further, the reliance on the injector to create a supersonic velocity jet stream into which the carbon-based particulates mix and entrain therein eliminates the need for the user site to incur additional capital expenditure for a dedicated, high pressurized carrier gas system for carbon injection.

While it has been shown and described what is considered to be certain embodiments of the invention and the benefits realized from the present invention, it will, of course, be understood that various modifications and changes in form or detail can readily be made without departing from the spirit and scope of the invention. It is, therefore, intended that this invention is not limited to the exact form and detail herein shown and described, nor to anything less than the whole of the invention herein disclosed and hereinafter claimed.