Process for producing carburized molten metal in smelting plant and plant for carrying out said process

Abstract

The invention relates to a process for producing carburized molten metal in a smelting plant suitable for further processing and to a plant for carrying out said process.

Description

Technical Field

[0001] The present invention relates to a process for producing carburized molten metal in a smelting apparatus and to apparatus for performing said process. Background Technology

[0002] The known process for smelting metallic materials is referred to below as the "HIsarna" process. ® The process (a registered trademark of Tata Steel) is specifically associated with the production of molten iron from iron ore or another iron-containing material. The term "smelting" is understood herein to mean hot working in which a chemical reaction occurs to reduce metal oxides to produce molten metal.

[0003] The process is carried out in a smelting apparatus comprising (a) a smelting vessel including a solids injection lance and an oxygen-containing gas injection lance and adapted to contain a bath of molten metal and slag, and (b) a smelting cyclone for pretreating the metal-containing feed, the smelting cyclone defining a cyclone chamber and including tuyeres for injecting the solids feed and oxygen-containing gas into the cyclone chamber, and located above and in direct communication with the smelting vessel. The HIsarna process and apparatus are described in international application PCT / AU99 / 00884 (WO 00 / 022176) filed in the name of the applicant, and are incorporated herein by reference.

[0004] The term "melting cyclone" is understood herein to refer to a vessel that typically defines a vertical cylindrical chamber and includes tuyeres for injecting solid feed and oxygen-containing gas into the chamber, and is configured such that the feed supplied to the chamber moves in a path around the vertical central axis of the chamber, and can withstand high operating temperatures sufficient to at least partially melt the metallic feed. A tuyer is a pipe, nozzle, or conduit through which gas is blown from the outside into a furnace, hearth, or vessel. A well-known example is a tuyer in a blast furnace hearth that supplies hot blast to the blast furnace.

[0005] The melting vessel includes a refractory lining section in the lower furnace and water-cooled panels in the side walls and top of the vessel, with cooling water continuously circulating through the panels in a closed loop.

[0006] The smelting vessel also includes a front furnace connected to the smelting chamber via a connection that allows continuous flow of metal products from the vessel. The front furnace acts as a siphon seal for molten metal filling, naturally "overflowing" excess molten metal from the smelting vessel as it is produced. This allows the molten metal level in the smelting chamber of the smelting vessel to be known and controlled within tight tolerances—essential for equipment safety.

[0007] In one form of the HIsarna process, a carbonaceous feedstock (typically coal) and an optional flux (typically calcined limestone) are injected into a molten bath in a melting vessel. The carbonaceous material is provided as a reducing agent and energy source. A metallic feedstock, such as iron ore, optionally blended with the flux, is injected into a melting cyclone where it is heated and partially melted and partially reduced. The molten, partially reduced metallic material flows downwards from the melting cyclone into the molten bath in the melting vessel.

[0008] The thermally reacting gases (typically CO, CO2, H2, and H2O) generated in the molten bath are partially combusted by oxygen-containing gases (typically technical-grade oxygen) in the upper part of the melting vessel. The heat generated by the post-combustion is transferred to molten droplets in the upper section, which fall back into the molten bath to maintain the bath temperature.

[0009] Hot, partially combusted reaction gases flow upward from the melting vessel and into the bottom of the melting cyclone. Oxygen-containing gas (typically technical-grade oxygen) is injected into the melting cyclone via tuyeres arranged to create a swirling pattern in the horizontal plane (i.e., around the vertical central axis of the melting cyclone chamber). This injection of oxygen-containing gas causes further combustion of the gases in the melting vessel, resulting in very hot (cyclonic) flames. A fraction of the metal-containing feed is pneumatically injected into these flames via tuyeres in the melting cyclone, resulting in rapid heating and partial melting, accompanied by partial reduction. The reduction is due to both the thermal decomposition of the metal oxides in the metal-containing feed (e.g., the hematite portion in the case of an iron-containing feed) and the reduction effect of CO / H2 from the reaction gases in the melting vessel. The hot, partially molten metal-containing feed is thrown outward against the walls of the melting cyclone by the swirling action and, as described above, flows downward into the melting vessel below for melting. The process gas, commonly referred to as "exhaust gas," is generated by further post-combustion of the reaction gas in the molten cyclone separator and is guided away from the upper region of the molten cyclone separator through an exhaust gas duct.

[0010] Conventional pig iron has a high carbon content, typically around 3.8-4.7% by weight. The presence of carbon in the molten metal lowers its liquidus temperature. This carbon is important for further processing in the LD steelmaking process (also known as basic oxygen steelmaking (BOS)). The LD vessel (converter) is charged with molten metal from the ironmaking steps, along with steel or iron scrap (typically around 15-30%). The molten scrap is generated during the oxidation process, and the heat required to refine the resulting melt into steel is generated. A water-cooled lance with nozzles is then lowered into the vessel, blowing oxygen onto the melt, thereby oxidizing the carbon dissolved in the melt and raising the average temperature of the melt to approximately 1700°C. Thus, oxygen blowing causes the scrap to melt and mixes the melt through blowing and the formation of CO bubbles, reducing the carbon content of the melt and aiding in the removal of unwanted chemical elements such as nitrogen, silicon, and phosphorus.

[0011] The problem with many alternatives for producing steel with a reduced carbon footprint is that the hot metal (molten metal) produced by these alternatives tends to have a lower carbon content than pig iron produced in conventional coke and coal-based blast furnace processes. Direct reduced iron (DRI) is produced by directly reducing iron ore agglomerates (primarily hematite, Fe₂O₃) in the form of lumps, pellets, or fine powder to iron using a reducing gas. Conventional DRI products based on coal or natural gas still have a fairly high carbon level of 1.5% to 4% by weight. However, DRI processes using hydrogen as a reducing gas produce iron with a considerably lower carbon content.

[0012] Therefore, if molten metal from alternative ironmaking processes (such as hydrogen-based DRI) is used as input to the LD process, the carbon content of the molten metal needs to be increased.

[0013] Purpose of the invention

[0014] One object of the present invention is to provide a method for increasing the carbon content of molten metal in an alternative ironmaking process.

[0015] Another objective is to provide a method for producing carburized molten metal from various types of metal-containing feedstocks.

[0016] Another objective is to provide a method for increasing the carbon content of molten iron to a level comparable to that of pig iron from a blast furnace. Summary of the Invention

[0017] A first aspect of the invention is embodied in a process for producing carburized molten metal (15) in a smelting apparatus (1), said apparatus comprising a smelting vessel (2) adapted to contain a bath of molten metal (6) and a slag layer (7), and said process comprising the following steps:

[0018] i. A molten metal bath (6) and a slag layer (7) are provided in the smelting vessel (2).

[0019] ii. Inject pure oxygen (8) above the slag layer (7) in the smelting vessel (2), inject a first stream (11) of solid metal feed into the molten metal (6) or slag layer (7) in the smelting vessel (2), and inject solid carbonaceous compound (10) and / or carbonaceous gas (9) into or above the molten metal (6) or slag layer (7) in the smelting vessel (2) for heating and melting the solid metal feed (11), for reducing any metal oxide compounds present in the solid metal feed (11), and for carburizing the molten metal (6) in the smelting vessel (2) to the desired carbon content to produce carburized molten metal (15).

[0020] iii. The hot and (optionally partially) combustible reducing process gas (14) comprising CO2, CO, H2O and H2 compounds is discharged upward from the melting vessel (2);

[0021] iv. Discharge the carburized molten metal (6) with the desired carbon content from the smelting vessel (2), preferably in a continuous manner;

[0022] v. Discharge the slag (7) from the smelting vessel (2), preferably separating it from the carburized molten metal, preferably in a continuous manner.

[0023] Preferred embodiments are provided by dependent claims 2 to 14.

[0024] The advantage of this invention's process lies in its ability to produce carburized molten metal from various types of solid metal-containing feedstock (MFM). MFM can be provided in various forms, such as pellets, lumps, or smaller agglomerates. MFM needs to have a certain mass because it must be able to penetrate the slag layer floating on top of the molten metal in the melting vessel. On the other hand, if the MFM is too large or too heavy, it will take a long time to melt, and the melt may cool too much. If the MFM is propelled into the vessel through a solid injection lance or tuyer, the size of the MFM can be smaller than when it is provided in the form of lumps or larger agglomerates capable of rapidly penetrating the slag layer under the influence of gravity. With suitable tuyeres, the MFM can even be in powder form.

[0025] The process according to the invention requires the presence of a melting vessel in which a suitable slag layer and a bath of molten metal already exist. These can be supplied from an auxiliary process (e.g., the HIsarna process) and transferred to the melting vessel, or they can be the result of pre-melting and slag-forming activities within the melting vessel itself. In this case, available auxiliary equipment may be required to perform these pre-melting and slag-forming activities.

[0026] In the process according to the invention, a carbonaceous material (MFM) on one side and a carbonaceous compound (CCC) or carbonaceous gas (CCG), or both, on the other side are introduced into a melting vessel. The CCC preferably enters the slag layer, and the CCG preferably remains above the slag layer. Pure oxygen is provided above the slag layer in the melting vessel. The mixture of pure oxygen and carbonaceous gas will reduce any remaining metal oxides present in the MMF under the conditions in the vessel, and will also carburize the molten metal, resulting in molten metal with a higher carbon content. The slag contains small solid carbon particles (originating from any CCC injected into the slag layer). FeO and other oxides react with carbon to form CO gas. Any excess carbon reacts with oxygen to form CO2 and CO. The hot CO2 and CO gases transfer their heat to the slag. Oxygen is also used to burn any volatiles (e.g., from the CCC) and reducing gases in the melting vessel to generate the heat required for the reduction and melting processes. Pure oxygen is not desired to reach the liquid metal because contact between oxygen and the molten metal will decrease rather than increase the carbon content of the molten metal. In this embodiment, the melting vessel serves as both a melting and reduction vessel. When the residence time in the container is long, the carbon content of the molten metal can be increased accordingly until the desired level is reached. After the desired carbon content is achieved in the molten metal, the process is controlled to balance the feed rate with the amount of slag and carburized molten metal discharged from the container. This allows for a continuous process.

[0027] In this process, the oxygen supplied to the melting vessel and melting cyclone (if present) is injected in the form of substantially pure oxygen. The term "pure oxygen" is used here as understood in the steelmaking field. This pure oxygen has an oxygen content greater than 90% by volume, preferably greater than 95% by volume, more preferably greater than 99% by volume. The pure oxygen supplied to the melting vessel and melting cyclone (if present) can be at a low temperature, for example, below 100°C. This is possible because, unlike prior art processes using oxygen-enriched air, the volume of pure oxygen entering this process is much smaller than that of prior art enriched air containing a large amount of nitrogen. Pure oxygen is preferably supplied via one or more spray guns. Furthermore, the higher the purity of the oxygen supplied to the melting vessel and melting cyclone (if present), the lower the chance of nitrogen oxide formation and the lower the thermal impact of the airflow on the process. Any ccg supplied to this process can also be provided via one or more spray guns or via tuyeres.

[0028] The apparatus for supplying solid carbonaceous compound (10) preferably includes one or more of the following:

[0029] (i) At least one spray gun for pneumatically conveying solid carbon compounds in a finely divided form;

[0030] (ii) At least one side vent of a smelting vessel for pneumatically conveying solid carbon compounds in finer forms;

[0031] (iii) At least one device for causing solid carbon compounds to fall into a slag layer by gravity.

[0032] Solid MFM can be provided in a similar manner via a solid injection gun, through an air vent, or simply by dropping it into the slag layer.

[0033] In a preferred embodiment, the first stream of solid metal feed mainly consists of solid iron feed (ffm), and the molten metal bath mainly consists of molten iron. Preferably, the first stream consists of ffm, and the molten metal bath consists of molten iron.

[0034] In one embodiment, ffm includes one or more of the following forms optionally combined with iron oxides or iron ore: direct reduced iron (DRI), hot-pressed iron (HBI), cold-pressed iron (CBI), solidified pig iron, and iron-containing scrap. ffm may also include recyclables from iron and steel production, such as iron-containing dust, steel rolls, steelmaking slag (e.g., EAF or BOS slag), and slag. Preferably, ffm includes fully reduced direct reduced iron, hot-pressed iron, cold-pressed iron, solidified pig iron, and iron-containing scrap, and does not contain iron ore or unreduced iron oxides, with the sole exception of surface rust. The latter has the advantage of a minimal proportion of unreduced material, allowing the process to operate efficiently as a melting vessel for iron (as molten metal) and then carburizing it to the desired level. Therefore, fully reduced direct reduced iron means direct reduced iron that does not contain iron ore or unreduced iron oxides, with the sole exception of surface rust.

[0035] In the absence of iron oxides or iron ore in the solid ffm, reduction in the smelting vessel is unnecessary. This makes the process easier to control, and the metallurgical process in this case is limited to molten solid ffm and carburized molten iron. The amount of oxides introduced by surface rust (e.g., on scrap) is negligible.

[0036] In a particular embodiment, the smelting apparatus further includes a smelting cyclone located above and openly connected to the smelting vessel. This embodiment allows for the generation of a combination of (partially) reduced, hot, partially molten metal-containing feedstock, which flows downward into the lower smelting vessel for melting. This further reduces the metal in the smelting vessel, and the resulting iron combines with the molten iron already present in the vessel.

[0037] The process provides a preferred embodiment in which the smelting apparatus (1) further includes a smelting cyclone (3) located above the smelting vessel (2) and openly connected to the smelting vessel (2) to form a single reactor therewith, and wherein the process further includes the following steps:

[0038] i. A hot and (optionally partially) combustible reducing process gas (14) generated by one or more of the following is directed upward from the smelting vessel (2) through the smelting cyclone (3):

[0039] a. Heating and melting solid metal-containing feed (11), and

[0040] b. Reduce any metal oxide compounds present in the solid metal-containing feed (11), and

[0041] c. Carburize the molten metal (6) in the melting vessel (2) to the required carbon content, and

[0042] d. Release of volatiles from the injected carbon-containing gas, and

[0043] e. Residual reducing components from excessively injected carbon-containing gas;

[0044] ii. A second stream (11') of metal-containing feed is introduced into the smelting cyclone (3), and the second stream (11') of metal-containing feed in the smelting cyclone is partially reduced by means of hot and (at least partially) combustible reducing process gas (14) originating from the smelting vessel (2).

[0045] iii. Post-combustion of the hot and (at least partially) combustible reducing process gas (14) in the melt cyclone (3) is achieved by supplying oxygen to the melt cyclone, such that the second stream (11') containing the metal feed is at least partially melted and at least partially reduced in the melt cyclone (3);

[0046] iv. Discharge the exhaust gas (17) upward from the smelting cyclone (3);

[0047] v. Allowing the second stream (11') of the metal-containing feed, which is at least partially melted and at least partially reduced, to enter the smelting vessel (2) from the melting cyclone (3);

[0048] vi. The final reduction and melting of the first and second streams (11, 11') of the partially reduced metal feed are achieved by injecting oxygen (8) and injecting solid carbonaceous compound (10) and / or carbonaceous gas (9), and the molten metal is carburized to the desired carbon content to produce carburized molten metal (15).

[0049] This preferred embodiment results in an optimal balance and utilization of various gas and material flows. The process is highly flexible. This embodiment allows the process to be started in a cyclone using only iron ore in a conventional HIsarna mode, and once the conventional HIsarna process is up and running, the addition of solid MFM according to the invention can begin. The ratio between the production of new molten metal from the ore and the addition of the solid metal to be molten can vary over time, making the process flexible.

[0050] In one embodiment, the second stream (11') of solid metal feed comprises up to 50% by weight of fresh iron ore. In the context of this invention, fresh iron ore means iron ore added to the process for the first time.

[0051] In one embodiment, the second stream (11') of solid metal feed comprises up to 10% by weight of fresh iron ore.

[0052] In one embodiment, the second stream (11') containing metallic material does not include fresh iron ore.

[0053] In one embodiment, the required carbon content of the carburizing molten metal is at least 3% by weight. This amount of carbon is considered sufficient for further processing in a conventional steelmaking facility. A preferred carbon content is at least 3.3% by weight, more preferably 3.5% by weight, and even more preferably 3.8% by weight. Even more preferred is a carbon content of at least 4.0% by weight or even 4.5% by weight.

[0054] In one embodiment, the carburized molten metal is further processed in an electric arc furnace. Such furnaces are typically used for molten scrap. A problem with molten scrap is the difficulty in removing unwanted elements. The effects of these unwanted elements can be mitigated by diluting the resulting melt using very clean scrap (i.e., very high iron content and very low amounts of undesirable alloying elements). However, clean scrap is expensive, and the process according to the invention can supply clean molten metal, such as molten iron, so the effects of undesirable elements can be mitigated economically by diluting the resulting molten iron, since it is not necessary to obtain expensive clean scrap.

[0055] In one embodiment, the carburized molten metal is further processed in a reducing electric arc furnace, and then further refined into steel in conventional steelmaking equipment.

[0056] In one embodiment, the carburized molten metal is further processed in conventional steelmaking equipment, such as LD equipment or equipment based on the Kroc Maximilian Schutz oxygen blowing process (KOBM).

[0057] In one embodiment, the second stream (2) of solid metal-containing feed also includes return materials from steel production, such as metal-containing dust, steel rolls, steelmaking slag (from BOS and / or EAF steelmaking) and sludge.

[0058] In one embodiment, the carbonaceous compound includes coal, charcoal, coke, graphite, or biomass, or a return from steel production, such as carbonaceous dust.

[0059] In one embodiment, the second stream (2) of solid metal feed comprises iron ore.

[0060] If present, the melting cyclone 1 and the smelting container 2 form a single unit, meaning they are directly connected through an opening through which both the molten iron ore and the process gas pass, without any connecting piping system, because the melting cyclone 1 is placed directly on top of the smelting container 2.

[0061] According to the second aspect, the invention is also embodied in the use of the method for producing carburizing molten metal having a carbon content of at least 3.0% by weight, preferably wherein the carburizing molten metal is carburizing molten iron.

[0062] According to a third aspect, the invention is also embodied in the apparatus for performing the process according to the invention as described in claim 15.

[0063] Example

[0064] The invention will be explained by the following non-limiting examples.

[0065] Example 1

[0066] A smelting vessel is used, in which almost all or all of the iron-containing feed is directly introduced. This method of operation may be relevant when the iron-containing feed consists primarily of metallic iron such as DRI. In this case, the smelting vessel will generate a limited amount of process gas. The carburized molten iron is suitable for further processing in a BOS unit. The carburized molten iron contains a sufficient amount of carbon to allow for further processing in a BOS unit, KOBM unit, or EAF. The exhaust gas is a reducing process gas.

[0067] Example 2

[0068] HIsarna ®The furnace comprises a melting cyclone 3 and a melting vessel 2. The melting cyclone provides fine iron ore and fine fresh flux (such as lime, limestone, dolomite). Additional flux is provided using fine-grained (e.g., ground) steelmaking slag (such as LD slag). The melt flows into the melting vessel, where coal and / or carbonaceous gases and burnt lime are injected. Oxygen is provided in the melting cyclone 3 and melting vessel 2 to meet the energy requirements of the HIsarna furnace. Also fed into the furnace is a feed rich in metallic iron, such as DRI. Especially for DRI, the introduction into the HIsarna melting vessel has the advantage of making slag-forming impurities in the DRI part of the HIsarna slag. Under the conditions in the vessel, the mixture of oxygen and coal and / or carbonaceous gases reduces any remaining metal oxides present in the metallic feed and carburizes the molten metal, resulting in molten metal with a high carbon content. The carburized molten iron contains a sufficient amount of carbon to allow for further processing in the BOS equipment. Exhaust gas (OG) can be captured. Attached Figure Description

[0069] The invention is further described by way of example with reference to the accompanying and non-limiting figures, wherein:

[0070] Figure 1 This is a schematic diagram illustrating an embodiment of the invention according to claim 1.

[0071] Figure 2 Illustrative embodiments according to claims 5 and 6 are shown.

[0072] Figure 3 An illustrative embodiment according to claim 16 is shown.

[0073] Figure 4 An illustrative embodiment of Example 1 is shown.

[0074] Figure 5 An illustrative embodiment of Example 2 is shown. Detailed Implementation

[0075] Figure 1A smelting apparatus (1) is shown, comprising a smelting vessel (2) with a more or less open top. A hood (not shown) may be provided to form a flue above the vessel to receive gases generated in the smelting vessel, and the hood may be provided with a duct through which a spray gun (12) can be introduced into the vessel. The spray gun (12) is shown for supplying oxygen (8) or CCG (9). Additional spray guns for CCC (10) and MFM (11) are shown at different heights in the sidewall of the smelting vessel. These spray guns are positioned such that they propel the compound from outside the slag into the slag (upper setting) or directly into the slag (lower setting). Only one of each is drawn in this 2D representation, but multiple of each may be present, preferably more or less evenly distributed along the perimeter of the smelting vessel, which is typically circular or oval to avoid sharp corners. However, less preferably, the smelting vessel may also be rectangular or polygonal with five or more faces. An optional vent (13) is shown to inject CCC (10) and MFM (11) directly into the slag layer. The carburized molten metal (15) can be vented via the vent and slag (16). Very hot, combustible, and reducing process gases (RPG, 14) escape through openings in the container and can be collected and directed away by the exhaust hood.

[0076] Figure 2 A smelting apparatus (1) is shown, comprising a smelting vessel (2) with a smelting cyclone (3) mounted on top of the vessel. In this smelting cyclone, very hot RPG (14) released in the smelting vessel is used to at least partially reduce a second stream (11') of mfm. An additional oxygen supply (8') is used to burn the RPG (14) to at least partially melt and at least partially reduce the mfm (11') in the smelting cyclone 5. The resulting exhaust gas (OG, 17) is discharged upwards and can be collected and directed away by an exhaust hood (not shown). The at least partially melted and at least partially reduced mfm (11') falls into the smelting vessel (2), where it can be disposed of as described above. Figure 1 The further restoration is described.

[0077] Figure 3A melting cyclone (3) is shown, into which a second stream (11') of mfm is supplied via a carrier gas. Simultaneously, substantially pure oxygen (8) is supplied to the melting cyclone (3). A smelting vessel (2) is directly below and openly connected to the melting cyclone. The mfm is pre-reduced in the melting cyclone and melted by a reducing process gas (14) originating from the smelting vessel (2). In this process gas, it is held in oxygen in the melting cyclone (3) and then combusted. The pre-reduced and melted mfm drips down the wall of the melting cyclone (3) at a temperature preferably 1400-1600°C, directly into the smelting vessel (2). During operation, a bath of molten metal (6) exists in the smelting vessel (2), with a slag layer (7) on its top. Essentially pure oxygen (8) and carbon-containing gas (9) can be supplied to the smelting vessel (2) via lances, and solid carbon compounds can be supplied via one or more lances (10, not shown) or by means of one or more tuyeres (17, not shown). The pre-reduced iron ore is ultimately reduced by carbon compounds supplied directly to the slag layer (7), thereby forming a process gas comprising CO2 and CO, which may also contain H2O and H2 derived from hydrogen derived from the carbon compounds. Along with the oxygen supplied to the smelting vessel (2), the process gas is post-combusted in the smelting vessel, thereby generating heat. The resulting process gas (14, not shown) flows directly into the melting cyclone (3), where it is further post-combusted as described above, and exits the melting cyclone. The process exhaust gas (17) exits the melting cyclone at a temperature of approximately 1200-1800°C. The sensible heat contained in the exhaust gas (17) can be converted into steam in the boiler (19), which can be used to generate electricity. After the boiler (19), the process gas still contains chemical energy, which can also be used to generate electricity. The exhaust gas can be dusted in a Venturi scrubber (20) after the boiler and can be further treated.

[0078] Figure 4 A schematic layout of the production facility starting with DRI production is shown. The DRI is then supplied to the facility as described in Example 1 (i.e., without the cyclone section). The resulting carburized molten metal is then supplied to the BOS converter or EAF for steelmaking, or first to the EAF and then to the BOS converter for steelmaking.

[0079] Figure 5 A schematic layout of the production facility starting with DRI production is shown. The DRI is then supplied to a facility as described in Example 2 (i.e., with a cyclone section). The resulting carburized molten metal is then supplied to the BOS converter or EAF for steelmaking, or first to the EAF and then to the BOS converter for steelmaking.

[0080] Important abbreviations used:

[0081] BOS: Basic Oxygen Steelmaking (also known as LD process (Linz-Donawitz)).

[0082] ccc: solid carbon-containing compound

[0083] ccg: Carbon-containing gas

[0084] DRI: Direct Reduced Iron

[0085] EAF: Electric Arc Furnace

[0086] ffm: Solid iron-containing feed

[0087] KOBM: Klöckner Oxygen Blowing Maximilianshuette

[0088] MFM: Solid metal-containing feed

[0089] RPG: Reduction process gas

[0090] REF: Reduction Arc Furnace

[0091] List of reference numerals in the attached diagram:

[0092] 1. Smelting equipment

[0093] 2. Melting container

[0094] 3. Smelting Cyclone

[0095] 4. DRI production equipment

[0096] 5. Steelmaking equipment

[0097] 6. Molten metal bath

[0098] 7. Slag layer

[0099] 8. Oxygen (8': Second flow of oxygen)

[0100] 9. Carbon-containing gases

[0101] 10. Solid carbon-containing compounds (10'. Second stream of solid carbon-containing compounds)

[0102] 11. Solid feed containing metal (11'. Second stream of feed containing metal)

[0103] 12. Spray gun

[0104] 13. Opportunity

[0105] 14. and reducing process gases

[0106] 15. A device for discharging molten carburized metal.

[0107] 16. A device for discharging slag.

[0108] 17. Process waste gas

[0109] 18. Discharge device for discharging process waste gas (18)

[0110] 19. Boiler

[0111] 20. Dust removal device

Claims

1. A process for producing carburized molten metal (15) in a smelting plant (1) comprising a smelting vessel (2) adapted to contain a bath of molten metal (6) and a slag layer (7), and the process comprising the steps of: vi. providing a bath of molten metal (6) and a slag layer (7) in the smelting vessel (2), characterized in that vii. injecting pure oxygen gas (8) above the slag layer (7) in the smelting vessel (2), injecting a first stream of solid metalliferous feed material (11) into the molten metal (6) or slag layer (7) in the smelting vessel (2), and injecting solid carbon-containing compounds (10) and / or carbon-containing gas (9) into or above the molten metal (6) or slag layer (7) in the smelting vessel (2) for heating and melting the solid metalliferous feed material (11), for reducing any metal oxide compounds present in the solid metalliferous feed material (11), and for carburizing the molten metal (6) in the smelting vessel (2) to a desired carbon content to produce carburized molten metal (15); viii. discharging hot and (optionally partially) combustible reducing process gas (14) comprising CO2, CO, H2O and H2 compounds from the smelting vessel (2) upwards; ix. discharging carburized molten metal (6) having the desired carbon content from the smelting vessel (2), preferably in a continuous manner; x. discharging molten slag (7) from the smelting vessel (2), preferably separate from the carburized molten metal, preferably in a continuous manner.

2. The process according to claim 1, wherein the first stream of solid metalliferous feed material (11) consists essentially of solid iron-containing feed material, and wherein the carburized molten metal (15) comprises or consists essentially of molten iron.

3. The process according to claim 2, wherein the solid iron-containing feed material (11) comprises one or more of direct reduced iron, hot briquetted iron, cold briquetted iron, solidified pig iron, iron-containing scrap, optionally in combination with iron oxides or iron ore.

4. The process according to claim 2 or 3, wherein the solid feed material iron- containing material (11) consists essentially of one or more of direct fully reduced iron, hot briquetted iron, cold briquetted iron, solidified pig iron, iron-containing scrap.

5. The process according to any one of claims 1 to 4, wherein the smelting plant (1) further comprises a smelting cyclone (3) located above the smelting vessel (2) in open connection therewith so as to form a single reactor therewith.

6. The process according to claim 5, wherein the process further comprises the following further steps: vii. directing hot and (optionally partially) combustible reducing process gas (14) generated by one or more of: f. heating and melting the solid metalliferous feed material (11), and g. reducing any metal oxide compounds present in the solid metalliferous feed material (11), and through the smelting cyclone (3) out of the smelting vessel (2). h. carburizing the molten metal (6) in the smelting vessel (2) to a desired carbon content, and i. releasing volatiles from the injected carbon-containing gas, and j. residual reducing components from the excess injected carbon-containing gas; viii. introducing a second stream of metal-containing feed material (11') into the smelting cyclone (3) and partially reducing the second stream of metal-containing feed material (11') in the smelting cyclone by means of hot and (at least partially) combustible reducing process gas (14) originating from the smelting vessel (2); ix. effecting post-combustion of the hot and (at least partially) combustible reducing process gas (14) in the smelting cyclone (3) by supplying oxygen to the smelting cyclone, such that the second stream of metal-containing feed material (11') is at least partially molten and at least partially reduced in the smelting cyclone (3); x. discharging off-gas (17) upwardly from the smelting cyclone (3); xi. allowing the at least partially molten and at least partially reduced second stream of metal-containing feed material (11') to pass downwardly from the smelting cyclone (3) into the smelting vessel (2); xii. effecting final reduction and melting of the partially reduced first and second streams of metal-containing feed material (11, 11') by means of injected oxygen (8) and injected solid carbon-containing compounds (10) and / or carbon-containing gas (9), and effecting carburization of the molten metal to a desired carbon content to produce carburized molten metal (15).

7. The process according to any one of claims 1 to 6, wherein the desired carbon content of the carburized molten metal (15) is at least 3.0 wt.%.

8. The process according to any one of claims 1 to 7, wherein the carburized molten metal (15) is further processed in an electric arc furnace.

9. The process according to any one of claims 1 to 8, wherein the carburized molten metal (15) is further processed in a reducing electric arc furnace.

10. The process according to any one of claims 1 to 9, wherein the carburized molten metal (15) is further processed in a conventional steelmaking plant such as an LD plant or a KOBM.

11. The process according to any one of claims 6 to 10, wherein the second stream of solid metal-containing feed material (11') further comprises returns from steel production such as metal-containing dust, rolled steel skin, steelmaking slag and sludge.

12. The process according to any one of claims 6 to 11, wherein the carbon-containing compounds (10, 10') comprise coal, charcoal, coke, graphite or biomass, or returns from steel production such as carbon-containing dust.

13. The process according to any one of claims 6 to 12, wherein the second stream of solid metal-containing feed material (11') comprises iron ore.

14. The process according to claim 10, wherein the carburized molten metal (15) is processed into steel.

15. Use of the process according to any one of claims 1 to 13 for producing a carburized molten metal (15) having a carbon content of at least 3.0 wt.%, preferably wherein the carburized molten metal is carburized molten iron (15).

16. Plant (1) for the production of carburized molten iron (15) according to the process of any one of claims 4 to 13, comprising a. a melting vessel (2); b. supply means for supplying coal (10) into or above the molten metal (6) or into the slag layer (7) in the melting vessel (2) above the iron melt bath (6) or into the molten metal (6) in the operation of the plant; c. supply means (8) for supplying pure oxygen into the melting vessel (2), d. discharge means for discharging the carburized molten iron (15) and the molten slag (16) from the melting vessel (2), e. a melting cyclone (3) located above the melting vessel (2) and open connected with the melting vessel to form a single reactor therewith, such that combustible reducing process gas can enter directly from the melting vessel (2) into the melting cyclone (3) in operation and such that at least partially molten pre-reduced iron ore can enter directly from the melting cyclone into the melting vessel (2); f. supply means for supplying iron ore into the melting cyclone (3), g. supply means for supplying oxygen into the melting cyclone (3), h. discharge means (18) for discharging process off-gas (17) from the melting cyclone (3), i. optionally, a steam generating boiler (19) in the discharge means for generating steam from the sensible heat contained in the process off-gas (17), j. optionally, dust removal means (20) downstream of the optional steam generating boiler (19) for dust removal of the process off-gas (17). ​ ​ ​ ​ ​ ​ ​ ​ ​ ​

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