Direct bath smelting process with high-speed quenching of molten material in high-temperature off-gas

Abstract

An improved direct smelting system and process using a smelting reduction vessel (SRV) and optionally a cyclone converter (CCF). The improved system and process utilize a high-speed quenching system in which a high-temperature process off-gas containing molten material is quenched and cooled from over 1400°C (2552°F) to below 600°C (1112°F) with a flight time of less than 1 second. Quenching is performed using water injection and vaporization to cool, stress, and break the solid slag into slag pieces small enough to be removed from the quenching system. The improved system eliminates plant utilization problems related to (i) deposit formation in the off-gas train when the high-temperature process off-gas is cooled in a conventional (low-speed) manner to enable steam generation for power generation or other heat recovery purposes, and (ii) trigger mechanisms that cause slag foaming events propagating through the off-gas train within the SRV.

Description

[Technical Field]

[0001] Claim of priority under Section 119 of the U.S. Patent Act This patent application claims priority to U.S. Provisional Patent Application No. 63 / 447,268, filed on 21 February 2023, entitled “Direct Bath Smelting Process with Fast Quench of Molten Material in Hot Offgas,” which has been assigned to the assignee of this patent application and is expressly incorporated herein by reference.

[0002] The present invention relates to a process and apparatus for directly smelting metal-containing materials. [Background technology]

[0003] Two known processes that directly smelt metal-containing materials, primarily using a molten bath as the smelting medium, are generally called HIsmelt and HIsarna. [Overview of the Initiative]

[0004] This disclosure relates to improved direct smelting processes. In particular, this disclosure relates to mitigating or eliminating plant uptime issues associated with deposit formation in the off-gastrain of conventional HIsmelt or HIsarna processes when process off-gas is cooled in a conventional manner (e.g., a slow process) for the purpose of generating steam (e.g., steam at a certain pressure) for use in power generation or other heat recovery purposes.

[0005] The direct smelting system and process utilizes a smelting reduction vessel (SRV) (i.e., the HIsmelt process) optionally connected to a cyclone converter (CCF) (i.e., the HIsarna process, consisting of SRV and CCF). This system further utilizes an off-gas duct (also known as a dogleg duct) from the SRV (or CCF, if present), which is operated in such a manner that it maintains a hot molten material on its inner surface in direct contact with the hot process off-gas within the off-gas duct. This molten material is primarily a molten slag whose composition may approximate that of the SRV slag (e.g., around 5% FeO) if a CCF is not present, or, if a CCF is present, a slag containing a high percentage of molten and partially reduced iron ore (e.g., around 55% FeO). A high-speed quenching system includes a coolant nozzle system (also known as a quench nozzle system or nozzle system) at the end of the off-gas duct, which uses one or more nozzles (typically multiple nozzles) to spray a coolant (e.g., water or other coolant) to cool the hot process off-gas and solidify the molten material in the process off-gas. Before spraying liquid water, the gas temperature of the process off-gas is above 1400°C, typically 1600–2000°C (above 2552°F, typically 2912–3632°F). The water from the spray nozzles vaporizes rapidly, resulting in a drop in gas temperature to below 600°C (1112°F) within an average flight time of 1 second for the gas particles.

[0006] The high-speed quenching system may further utilize an outlet rim at the outlet of the high-temperature off-gas duct before adding a spray of water from the nozzle system. An outlet rim, which may have a water-cooled smooth-faced copper ring, can help break up solid slag (also known as "frozen slag," etc.) from the walls of the off-gas duct. The quench chamber into which water flows from the nozzle system may be larger in diameter than the high-temperature off-gas duct itself, and a set of inwardly directed (e.g., extending radially inward) water spray nozzles may be positioned immediately downstream of the outlet rim (e.g., copper rim).

[0007] There are two different ways to configure the quench chamber of a quench system: (1) dry bottom and (2) wet bottom. In the dry bottom configuration, the total amount of water added is just enough (if completely evaporated) to cool the process gas to a typical 200-300°C (392-572°F), not falling below approximately 150°C (302°F). In this embodiment, the quenched molten material, at this point in the form of broken solid slag fragments, is removed dry from a collection hopper at the base of the quench chamber. Precise control of the water injection is required to maintain the bottom of the quench chamber above approximately 150°C (302°F). In this dry bottom embodiment, the total amount of sprayed water is typically 1000 Nm of high-temperature process off-gas. 3 It is approximately 1.0 to 1.5 tons per hour.

[0008] In the wet-bottom embodiment, the bottom of the quench chamber functions with either a pool or channel of liquid water into which frozen slag fragments (hereinafter also referred to herein as "solid slag fragments" or "broken slag fragments") fall. From here, the solid slag fragments are removed continuously or in batch mode by hydraulic transport underwater. In this wet-bottom embodiment, the total amount of water added is typically 1000 Nm³ of high-temperature process off-gas. 3 It's about 3 to 5 tons per hour.

[0009] One embodiment of the present invention is a direct smelting method for producing molten metal and slag in a direct smelting system. The direct smelting system comprises a smelting reduction vessel (SRV) containing a bath of molten metal and slag. Carbonaceous material is introduced, and metal-containing ore is introduced into the slag from above or supplied by gravity. The metal-containing ore is smelted to produce carbon-containing molten metal and molten slag, and oxygen-containing gas is introduced into the upper space of the SRV to partially burn the gas from the bath and provide process heat to the SRV. The direct smelting system further comprises a quench system operably connected to the SRV. The quench system comprises a dogleg duct and a quench nozzle system operably connected to the dogleg duct. The direct smelting method comprises receiving process-off gas from the SRV into the dogleg duct, the process-off gas containing the taken-in molten slag. The method further comprises guiding the process-off gas from the dogleg duct to the quench nozzle system. To form solid slag, the process-off gas is rapidly cooled to below 600°C using a quench nozzle system, and this solid slag is then crushed into solid slag pieces for extraction.

[0010] According to further embodiments of the present invention, the direct smelting system further comprises a cyclone converter (CCF) connected to the SRV. The CCF receives process-off gas from the SRV, and metal-containing ore, a portion of oxygen-containing gas, and flux material are fed into the CCF. The metal-containing ore is mostly melted and partially pre-reduced before entering the SRV. Receiving process-off gas in the dock leg duct includes receiving process-off gas from the CCF.

[0011] In other embodiments, the process-off gas in the dog leg duct is maintained at a gas temperature of 1400°C (2552°F) or higher before rapid cooling by the quench nozzle system.

[0012] In yet another embodiment, the average flight time of process-off gas particles in the quench nozzle system is less than 1 second.

[0013] In yet another embodiment, the quench nozzle system uses a process off gas of 1000 Nm 3 It injects 0.8 to 2.0 tons of water per hour. The final gas temperature after water vaporization is between 150°C (302°F) and 600°C (1112°F).

[0014] In other embodiments, the quench nozzle system preferably uses a process off gas of 1000 Nm 3 1.0 to 1.5 tons of water are injected per hour. The final gas temperature after water vaporization is preferably within the temperature range of 200 to 300°C (392 to 572°F), including the values ​​at both ends.

[0015] According to further embodiments of the present invention, the solid slag fragments are removed in a dry state from a collection container located at the bottom of the quench chamber.

[0016] In another embodiment, the quench nozzle system uses a process off gas of 1000 Nm 3 Two to six tons of water are injected per hour, and the final gas temperature is approximately equal to the local water saturation temperature at the process pressure at that point.

[0017] In yet another embodiment, the quench nozzle system is preferably a process off gas of 1000 Nm 3 It sprays 3 to 5 tons of water per hour.

[0018] In yet another embodiment, liquid water is present at the bottom of the quench chamber, and the solid slag fragments are removed from the collection container of the quench chamber in a wet state.

[0019] In other embodiments, the quench system further comprises an outlet rim upstream of the quench nozzle system. The outlet rim helps to break up the solid slag into solid slag pieces.

[0020] Another embodiment of the present invention is a direct smelting system for producing molten metal and slag. The direct smelting system comprises a smelting reduction vessel (SRV). The SRV is configured to contain a bath of molten metal and slag. The SRV receives a carbonaceous material and metal-containing ore that is added to the slag or supplied by gravity from above. The metal-containing ore is smelted in the bath to produce carbon-containing molten metal and molten slag, and an oxygen-containing gas is introduced into the upper space to partially burn the gases from the bath and provide heat to the SRV. The direct smelting system further comprises a quench system operably connected to the SRV. The quench system comprises a dogleg duct and a quench nozzle system operably connected to the dogleg duct. Process-off gases from the SRV containing the taken-in molten slag pass through the dogleg duct to the quench nozzle system. The process-off gas is rapidly cooled to a temperature of 600°C (1112°F) or less by a quench nozzle system to form solid slag, which is then crushed into solid slag pieces for extraction.

[0021] According to further embodiments, the direct smelting system further comprises a cyclone converter (CCF) connected to the SRV. The CCF receives process-off gas from the SRV, and metal-containing ore, a portion of oxygen-containing gas, and flux material are fed into the CCF. The metal-containing ore is mostly melted and partially pre-reduced before entering the SRV. A dogleg duct receives process-off gas from the CCF.

[0022] In other embodiments, the process-off gas in the dog leg duct is maintained at a gas temperature of 1400°C (2552°F) or higher before rapid cooling by the quench nozzle system.

[0023] In yet another embodiment, the average flight time of process gas particles in the quench nozzle system is less than 1 second.

[0024] In still other embodiments, most of the cooling of the process gas in the quench system is performed by the quench nozzle system, and the portion of the cooling performed by duct cooling is less.

[0025] In other embodiments, the quench nozzle system injects 0.8 to 2.0 tons of water per 1000 Nm 3 / h of process off-gas. The final gas temperature after the vaporization of the water is 150 °C (302 °F) or higher and 600 °C (1112 °F) or lower.

[0026] According to still further embodiments, the solid slag pieces are taken out in a dry state from a collection container at the bottom of the quench chamber.

[0027] In other embodiments, the quench nozzle system injects 2 to 6 tons of water per 1000 Nm 3 / h of process off-gas. The final gas temperature is approximately equal to the local water saturation temperature at the process pressure at that time.

[0028] In yet still other embodiments, liquid water is present at the bottom of the quench chamber, and the solid slag pieces are taken out in a wet state from the collection container of the quench chamber.

[0029] In still other embodiments, the quench system further includes an outlet rim upstream of the quench nozzle system. The outlet rim helps to crush the solid slag into solid slag pieces.

[0030] Another embodiment of the present invention is a method for forming pig iron using a quench system operably connected to a smelting reduction vessel (SRV). The quench system comprises a dogleg duct and a quench nozzle system operably connected to the dogleg duct. The method comprises forming molten metal in the SRV. The method further comprises receiving process-off gas from the SRV into the dogleg duct. The process-off gas contains the taken-in molten slag. The method further comprises guiding the process-off gas from the dogleg duct to the quench nozzle system. Furthermore, in order to form solid slag, the process-off gas is quenched to a temperature of 600°C or less using the quench nozzle system. The method further comprises crushing the solid slag into solid slag pieces for extraction, extracting molten metal from the SRV, and forming pig iron from the molten metal.

[0031] Another embodiment of the present invention is a quench system used with a molten reduction vessel (SRV) for generating molten metal and slag. The quench system comprises a dogleg duct and a quench nozzle system operably connected to the dogleg duct. Process-off gas from the SRV contains the taken-in molten slag and passes through the dogleg duct to the quench nozzle system. The process-off gas is rapidly cooled by the quench nozzle system to a temperature below 600°C (1112°F) to form solid slag, which is then crushed into solid slag pieces for removal.

[0032] To achieve the aforementioned and related objectives, one or more embodiments of the present invention are described in full below and feature, in particular, those indicated in the claims. The following description and accompanying drawings illustrate specific exemplary features of one or more embodiments. However, these features represent only a small number of the various ways in which the principles of various embodiments may be employed, and this description is intended to include all such embodiments and their equivalents.

[0033] The present invention will be further illustrated with reference to the attached drawings below. [Brief explanation of the drawing]

[0034] [Figure 1] This is a diagram of a direct smelting process utilizing an SRV, CCF, and a fast quench system according to an embodiment of the present disclosure. [Figure 2] This is a 2D cross-sectional view of a quench nozzle system, with further details regarding the configuration of the quench nozzle system according to embodiments of the present disclosure. [Figure 3] This is a 3D cross-sectional view of a quench nozzle system, with further details regarding the configuration of the quench nozzle system according to embodiments of the present disclosure. [Figure 4] This diagram shows the process flow of a direct smelting process using a high-speed quench system according to an embodiment of the present disclosure. [Modes for carrying out the invention]

[0035] Embodiments of the present invention will be described more fully here with reference to the accompanying drawings, but these drawings show only some embodiments of the present invention, not all embodiments. In practice, the present invention can be carried out in many different forms and should not be construed as being limited to the embodiments described herein, rather these embodiments are provided to satisfy the legal requirements to which this disclosure applies.

[0036] The term "smelting" is understood herein to mean a thermochemical process in which a chemical reaction occurs that reduces a metal oxide to produce a carbon-containing molten metal. These smelting reactions occur only when (i) high temperature, (ii) a sufficiently low oxygen potential, and (iii) are highly endothermic, requiring a large heat supply to maintain constant process conditions.

[0037] The two processes that directly smelt metal-containing materials, primarily using a molten bath as the smelting medium, are generally called the HIsmelt process and the HIsarna process. The HIsmelt process utilizes SRV101, while the HIsarna process utilizes SRV101 in conjunction with CCF102. The quenching system 200 described herein is primarily for the HIsarna process, but can also be applied to the HIsmelt process.

[0038] The HIsmelt process relates to the direct smelting of metal-containing materials in the form of iron and its oxides (which may be unreduced, partially reduced, or already largely pre-reduced) to produce molten carbon-containing iron. This process involves forming a bath of molten iron and slag in a vessel (e.g., an SRV). Solid carbonaceous material (e.g., coal) is introduced into the bath. The metal-containing material may be introduced into the bath and / or supplied into the slag layer by dropping the material from above. The solid carbonaceous material acts as a reducing agent for the iron oxide and as an energy source for forming the molten metal bath in the SRV.

[0039] The HIsmelt process also involves post-combusting the reaction gases, such as CO and H2, released from the bath in a space above the bath where the gas is generally continuous (e.g., called the upper space), using an oxygen-containing gas, typically high-temperature oxygen-enriched air or technically pure, low-temperature oxygen. The heat generated by the post-combustion reaction is transferred back to the bath to provide the thermal energy necessary for heating and smelting the metal-containing material.

[0040] The HIsmelt process also involves the formation of a transition zone above the theoretical stationary surface of the bath. Within this zone, there is a large volume of rising and falling droplets and splashes, or flows of molten metal and / or slag, which act as an effective medium for transferring a significant portion of the thermal energy generated above the bath by the post-combustion reaction gases. This plume transfers heat from its source (e.g., a relatively high oxygen potential) to the bath where it is used for smelting (e.g., a relatively low oxygen potential). Thus, the plume effectively functions as a heat pump.

[0041] In the HIsmelt process, solid carbonaceous materials and optionally metal-containing materials are introduced into the molten bath through several solids input lances. These lances may be inclined with respect to the vertical so as to extend downward and inward through the side walls of the vessel into the lower region in order to deliver at least a portion of the solids into the molten metal layer at the bottom of the vessel. To promote afterburning of reaction gases in the upper portion of the vessel, a blast of low-temperature oxygen, or possibly oxygen-enriched high-temperature air, is introduced into the upper region of the vessel through one or more downward-extending gas input lances. Process off-gas (also known as off-gas) resulting from afterburning of reaction gases in the vessel is removed from the upper region of the vessel through an off-gas duct. The vessel also includes water-cooled panels covered with slag on the side walls and roof of the vessel, through which water circulates in a closed cooling circuit.

[0042] The molten metal product is removed from the Smelting Reduction Vessel (SRV) 101 via a pre-furnace. The pre-furnace is a siphon-type overflow device connected to the metal bath in the SRV 101 via an opening near the bottom of the bath ("pre-furnace connection"). The pre-furnace allows for the continuous extraction of molten metal from the SRV 101 during operation, while maintaining the metal level in the SRV 101 at a level that allows for safe operation (e.g., keeping the bulk metal sufficiently away from the water-cooling element). The molten metal may be used as a solid product (e.g., pig iron) for further processing, or in molten form for further processing, such as direct or indirect use in a different type of furnace (e.g., an oxygen furnace, an electric arc furnace). Thus, the products generated from SRV (e.g., solid metal or molten metal) (whether or not CCF as described later is used) can be cast into steel products (e.g., sheets, plates, bars, billets, etc.) and / or formed into final products manufactured from these steel products (e.g., beams, decking materials, structural steel, electrical steel, etc.).

[0043] The HIsarna process, as far as SRV101 is concerned, has the same or similar physical components and layout as the HIsmelt process and operates in the same or similar manner. The main difference between the two is that in the HIsarna process, the incoming metal-containing feed (usually iron ore) is not added to or dropped directly into the bath, but is heated, partially pre-reduced, and mostly melted in a smelting cyclone converter (CCF) 102, which is directly connected to the upper gas outlet of SRV101. Droplets of mostly molten and partially reduced iron ore fall from the CCF 102 into the SRV slag, from where the final smelting proceeds. Primarily, carbon-rich metals react with FeO in the slag to produce further carbon-containing iron metals. The carbonaceous material is still added to the bath as described above to carbonize the metal and produce splashes, fountain plumes, and mixing within SRV101.

[0044] In both the HIsmelt and HIsarna processes, the high-temperature process off-gas (either directly from SRV101 or from CCF102) is removed from the process via a steam-cooled (or water-cooled) off-gas duct. In the case of HIsarna, additional oxygen may be introduced into this duct for the complete combustion of residual fuel gases (e.g., mainly CO and H2).

[0045] In conventional off-gas ducts, the initial portion of this high-temperature off-gas duct is generally called a "dogleg," and the flow direction of the high-temperature process off-gas ascending from the SRV101 or CCF102 is forcibly changed twice: (i) from vertical (e.g., from the SRV101 and / or CCF102) to nearly horizontal (e.g., within the dogleg), and (ii) from nearly horizontal (e.g., within the dogleg) back to vertical. Within this off-gas duct, the adhesion of solid slag to the walls is actively promoted by mechanical means, such as the provision of slag adhesion studs or similar devices. The purpose of the mechanical means is to promote the formation of a frozen slag layer (also known as a solid slag layer) on the duct wall adjacent to cooling pipes (e.g., pipes containing saturated steam / water or cooling water) which typically surround or form within the outer wall of the duct. This frozen layer will grow (or regrow) on the wall cooled by the pipe to a "natural" thickness, typically 20–30 mm (0.79–1.18 inches). At this point, the cooling (by conduction through the 20–30 mm frozen slag) balances, to varying degrees, with the heat supply from the hot process-off gas, slowing down the growth of further solid layers. A small semi-solid layer will then form on top of the frozen slag layer, with the slag remaining in a molten state. In this situation, the actual liquid is called "molten slag," but even this may sometimes contain iron ore that is mostly molten and partially reduced.

[0046] The purpose of the dogleg process is to intentionally maintain the inner surface of the molten slag. That is, the liquid carried by the main off-gas flow (for example, by residual vortices and changes in flow direction within the duct, as described herein) can escape capture by being "thrown" onto the wall and / or frozen slag adhering to the wall. This escaped liquid slag can then, under gravity, flow back into the SRV with the escaping high-temperature process off-gas. The gas velocity within the dogleg is (designed) insufficient to force the liquid slag in the wall layer to flow in the same direction as the process off-gas. Instead, under gravity, the liquid slag can flow back into CCF102 and / or SRV101, returning into them, in the direction of the process off-gas flow. This concept has been extensively tested and has been shown to work reliably.

[0047] In conventional HIsmelt and HIsarna plant designs, the hot gas exiting the dogleg enters a further cooling duct, commonly referred to as a "hood," which is a large, inverted "U" shaped structure. This hood comprises an ascending duct (or upleg), a large 180-degree bend at the top (usually containing one or more pressure relief valves), and a descending duct (or downleg). The legs of the hood are typically several tens of meters long. The duct walls within the hood are also typically constructed from cooling pipes (e.g., steam pipes), but there are no mechanical means for slag adhesion within the hood (e.g., studs or similar devices), and the inside of the walls is smooth. Therefore, solid slag is not encouraged to adhere to the walls of the hood. The purpose of the process in the hood is to cool the hot process-off gas in the upleg to a temperature lower than the temperature at which any liquid material can still exist (e.g., typically 900–1000°C, 1652–1832°F). In one specification of the hood design, a sheet of slag solidifies on a smooth inner wall surface (cooled by cooling tubes such as steam pipes), increases in size, and eventually becomes unstable and detaches (e.g., naturally due to weight). The fallen solid sheet then enters the top of the dog leg (e.g., from an upleg), where it is heated and melted (over time by process-off gas, liquid slag on the wall, etc.) and then returns as a liquid into the CCF102 and / or SRV101. In another specification of the hood design, a cryogenic gas (e.g., a recycle gas) is added to an annular ring at the base of the upleg to cool the process-off gas and solids more rapidly while keeping molten droplets away from the upleg wall.

[0048] Conventional hood designs further involve extracting off-gas from the hood's down legs, removing dust with a conventional dust cyclone, and finally recovering heat from it in a steam boiler. Molten slag deposits are well managed by this strategy. Unfortunately, there is a second (lower temperature) deposit formation mechanism that causes problems and complicates the process in this type of slag deposit system. A sticky phase containing alkali sulfates or similar substances can form at temperatures above approximately 600°C (1112°F) (e.g., slowly over time). These sticky substances act as a kind of glue phase, and any solid particles that happen to be present (e.g., as dust) can become building blocks of the low-temperature deposit (e.g., solid dust particles act like aggregate particles in cement). This type of low-temperature deposit accumulates and densifies over time, and in some cases, significantly impairs heat transfer in the hood's down legs. This type of deposit growth is generally considered to be unidirectional, meaning, for example, that fouling gradually occurs on the duct wall over time and that "natural" self-cleaning mechanisms do not function.

[0049] A significant impact of these low-temperature deposits is that they tend to accumulate, particularly on the superheater tubes of conventional steam boilers. This can significantly impair boiler performance over time. Superheater tubes have the highest metal wall temperatures in the heat recovery system (e.g., typically around 400–550°C, 752–1022°F), making them more susceptible to this type of fouling. In practical terms, this can reduce the operational efficiency of the steam boiler, and if there is only one such boiler, it will reduce the operational efficiency of the entire steel plant. One option to maintain plant operational efficiency is to use two boiler systems and operate them alternately, but this increases plant costs and is considered a particularly expensive solution.

[0050] A second problem specific to HIsarna is rapid foaming. This occurs when a sufficiently large chunk of iron oxide-rich solid material falls into the SRV101. A sudden, violent reaction takes place between this chunk and the carbon-containing molten metal in the bath. As a result, a foamy slag (similar to the foam in a carbonated beverage, for example) rapidly develops, which can pass through the off-gastrain completely in seconds. Such behavior has been recorded on multiple occasions at the HIsarna pilot plant in Ijmuiden, Netherlands. The chunks of solid material are thought to be triggered by the collapse of iron oxide-rich solid deposits from a location such as the hood wall (most likely the base of or near the riser's upleg). It is thought that such chunks can return through the dogleg, retaining enough solid material to cause rapid foaming, and then fall into the SRV101 (via CCF102, if used).

[0051] The impact of high-speed foaming on off-gas boilers can be dramatic. When this occurs and the foamy slag completely passes through to the boiler, the boiler itself becomes almost instantly clogged with a type of low-density slag sometimes called "pumice" slag. The practical implications, particularly the offline time required to manually clean the clogged boiler to restart the process, are serious and costly (e.g., due to plant downtime).

[0052] Embodiments of the present disclosure attempt to address the problems identified above by avoiding (i) the possibility of forming cryogenic deposits and (ii) the possibility of forming large FeO-rich lumps that could fall back into the SRV and cause problems of rapid foaming. Embodiments of the present disclosure are designed to remove hot gases from SRV101 and / or CCF102 by utilizing a down-row configuration in which an improved duct system having (e.g., primarily or exclusively) the inner surface of the molten slag is used, and then a nozzle system having water jet spray nozzles is used to "snap freeze" the hot process-off gases and molten slag (e.g., 1400°C, 2552°F or higher) to below 600°C (1112°F) with an average flight time of gas particles of less than 1 second. By using this nozzle system, the possibility of such deposit formation is largely avoided by passing through the temperature window in which cryogenic deposits can form in the shortest possible time. By not using any type of hood upleg that could potentially accumulate frozen FeO-rich slag material, the possibility of causing rapid foaming events within the SRV101 is also virtually eliminated.

[0053] In this strategy of snap-freezing process-off gases, heat recovery from process-off gases may no longer be possible. In most embodiments of the HIsarna process (or HIsmelt process), stable and reliable metal production and high plant uptime are more important than the economic value associated with heat recovery and power generation. For example, capital cost savings (by not having a boiler) offset the operating cost penalty (associated with, for example, the lack of power generation from process-off gases), leading to a substantially constant intra-project rate of return. However, these calculations do not adequately capture the full impact of the plant being out of operation. Therefore, the main advantage of embodiments of this disclosure is the elimination of “cash burn” associated with potential production interruptions (caused, for example, by boiler deposit formation and / or SRV foaming).

[0054] The quenching concept described herein is commonly referred to as "high-speed quenching." Designing a suitable high-speed quenching system 200 requires certain special considerations. For example, the system's dogleg 104 (e.g., where slag wall adhesion is promoted and there is hot molten slag on the inner surface) is largely the same as in a conventional design, except that the final outlet of the dogleg 104 is directed downward. A pressure relief valve can be placed on or near the final portion of this modified dogleg 104.

[0055] Another consideration for the high-speed quench system 200 is that the rim 203 at the outlet of the descending dogleg must be configured so that the molten slag of the wall, which will form a solid ring around the wall that will grow downward (for example, forming a kind of solid "pipe"), does not adhere to the wall at the final portion of the outlet of the descending dogleg duct. This is because the water spray is intended to break down the quench-frozen slag into manageable small solid slag pieces when it hits the hot "pipe" a short distance beyond the end of the dogleg outlet. It is advantageous in this respect that the hot, molten "pipe" is already loose at the final portion of its molten descending stroke (for example, not adhering to the wall of the outlet of the descending dogleg duct). The dogleg outlet typically features a smooth, water-cooled copper rim 203 that is integral with the downward-facing end of the dogleg duct outlet. The high-pressure droplet spray nozzles of the nozzle system (directed radially inward) are positioned a short distance downstream from the outlet rim 203. Strong cooling occurs when the water comes into contact with the hot process-off gas and slag, causing a large amount of water to vaporize.

[0056] Depending on the total number of nozzles required and the operating mode of the quench chamber (e.g., wet bottom vs. dry bottom), one or more additional secondary water spray nozzles may be placed further downstream.

[0057] A further embodiment of the high-speed quench system 200 may require a quench chamber 108 to provide a certain gas residence time to allow for sufficient vaporization of the water droplets. Exactly how much time this is will be a complex function of fluid dynamics and the water droplet size of the spray nozzle. A gas residence time of about 2 - 5 seconds is likely to be required, but the gas residence time may be within this range, outside this range, or overlap with this range (e.g., less than 2 seconds, or up to 6, 7, 8, 9, 10 seconds, etc.).

[0058] In addition, in a dry-bottom embodiment, the high-speed quench system 200 may require precise control of the amount of water injected at any given time. That is, the temperature at the gas outlet (after vaporization of the water) must be maintained above about 150 °C (302 °F), and for this reason the plant control system needs to calculate the real-time system thermodynamics well enough to regulate the water injection rate without creating any liquid pools within the system. This requires a process model that is accurate and detailed enough to predict how much water is needed (within an acceptable control margin). The water injection rate for dry-bottom operation is typically in the range of 1.0 - 1.5 tons per 1000 Nm 3 / h of the hot process off-gas.

[0059] In a wet-bottom embodiment, excess water is intentionally injected. A liquid pool (or waterway) is formed at the bottom of the quench chamber 108. The gas exits the vessel at or near its dew point (about 110 - 120 °C, 230 - 248 °F). The advantage of this specification under normal operating conditions is that any surge or splash of molten slag flowing out of the dogleg 104 and resisting quenching will ultimately enter the pool of water, where it will ultimately be quenched anyway. However, there is some uncertainty regarding plant safety in this regard. If a high-speed foaming event occurs in the SRV101 (for any reason, whether described in this specification or not), there is a possibility that the highly foaming but molten slag will encounter the pool of liquid water. The resulting contact between liquid water and this type of highly foaming molten slag can cause a steam explosion.

[0060] Thus, in some embodiments, a dry-bottom configuration may be preferred. However, when the interaction between foamy slag and liquid water is ultimately deemed safe, and / or when the formation or propagation of foamy slag is prevented, a wet-bottom high-speed quench system is likely preferred because the operation and control of water spray from a nozzle system is inherently easier.

[0061] Referring to the figures, Figure 1 shows a direct smelting process using SRV101, CCF102, and a high-speed quench system 200. Furthermore, Figure 4 shows a high-level process flow of the direct smelting and high-speed quench processes described herein. As shown in block 410 of Figures 1 and 4, the high-temperature CCF process off-gas (or process off-gas of SRV101 in the HIsmelt system) moves into the off-gas duct, particularly the dog leg duct 104. In some embodiments, supplemental oxygen 103 is introduced as shown to ensure complete combustion of residual carbon monoxide and hydrogen in the process off-gas. The gas temperature at the outlet of the dogleg duct 104 is above 1400°C (2552°F), typically between 1600 and 2000°C (2912-3632°F), and the dogleg duct 104 itself may be constructed from steam pipes that maintain the metal temperature of the metal walls within the range of 150 to 300°C (302 to 572°F). The inner surface of the walls of the dogleg duct 104 is equipped with slag studs (or similar or other mechanical devices) to ensure that the frozen slag layer is adjacent to the wall with the metal pipes. An FeO-rich frozen slag layer approximately 20-30 mm (0.787-1.181 inches) thick is maintained on the wall surface, and on the inner surface of the frozen slag layer in contact with the high-temperature process-off gas, the slag is hot and substantially liquid.

[0062] The off-gas duct 104 (e.g., a dogleg duct) can be intentionally altered in flow direction at its end before being connected to the quench nozzle system 106. For example, the end of the dogleg 104 can change the direction of the process off-gas (e.g., at the downleg of the dogleg duct before the process off-gas is delivered to the quench nozzle system 106) from nearly horizontal to vertical, back to nearly horizontal, and back to nearly horizontal. For example, as shown in Figure 1, the end of the dogleg 104 may include an inverted U-shaped dogleg end 120 having an upleg duct portion 122, an upper duct portion 124, and a downleg duct portion 126. This dog leg end 120 differs from the hood described herein in that the legs 122, 124, and 126 are much shorter than the portion in the hood (e.g., 1, 2, 3, 4, 5, 7, 8, 9, and 10 meters in length, etc.) and include mechanical devices (e.g., studs) that facilitate slag adhesion within the dog leg end 120. For example, mechanical devices (e.g., studs) may be included between the down leg duct 126 and the nozzle system 106.

[0063] This configuration can be used to capture as much of the liquid taken in from CCF102 (or SRV101 in the HIsmelt process) onto the wall as possible. Furthermore, since the innermost slag layer in the dog leg duct 104 is substantially liquid, this slag layer can flow back into SRV101 (through CCF102 in the HIsarna process) from the up leg section 122 and / or upper section 124 (backflowing into the main off-gas flow) under gravity.

[0064] A pressure relief valve 105 is located at the top of the last bend in the dog leg (for example, at the upper portion 124 of the dog leg end 120). The pressure relief valve 105 may be necessary to ensure safety in the event of slag ejection or other sudden pressure increases in the system.

[0065] The final bend in duct 104 (whether or not, for example, the inverted U-shaped dogleg end 120 is utilized) directs the process-off gas downward into the nozzle system 106 of the high-speed quench system 200. Water is injected into the process-off gas flow via the high-speed quench nozzle system 106, as shown in block 420 of Figure 4, which will be explained in more detail with reference to Figures 2 and 3. The purpose of the process is to cool the hot process-off gas from above 1400°C (2552°F) to below 600°C (1112°F) during an average flight time of gas particles of less than 1 second, thereby freezing, stressing, and breaking the initially molten slag flowing downward along the hot wall of the dogleg outlet. The initial water injection via the first spray nozzle of the spray system 106 occurs a short distance below the bottom of the dogleg outlet, and further secondary water spray nozzles 107 can be used below the first spray nozzle.

[0066] As shown by block 430 in Figure 4 and described in further detail with respect to Figures 2 and 3, the rapid quenching, nozzle spraying, thermal stressing, and / or outlet rim 203 of the high-speed quench system 200 help to solidify the molten slag in the process off-gas and / or on the walls of the off-gas duct into fragmented solid slag pieces.

[0067] The high-temperature process-off gas, dust, and slag will rapidly mix with water spray droplets injected into the quench chamber 108. The water will vaporize, and the process-off gas will be cooled to a temperature below 600°C (1112°F). Depending on the system configuration, the final gas outlet temperature can be 200–300°C (392–572°F) for the dry-bottom option, or 110–120°C (230–248°F) for the wet-bottom option.

[0068] As shown in block 440 of Figure 4, when the wet bottom system is used as described above herein, an excess of water is used without restraint, and the final gas mixture approaches water saturation. The liquid water will be present in the collection channel 109, from which it will take in the broken solid slag fragments and flow into a suitable solid sedimentation water treatment system.

[0069] As shown in block 450 of Figure 4, when a dry-bottom system is used, the solids are collected in a dry state at 200-300°C (392-572°F) and removed from the collection hopper via the lock container system 110. As mentioned earlier, in the case of a dry-bottom system, meticulous attention to detail will be required to avoid water condensation. In particular, thermal tracking may be necessary in this part of the system to constantly maintain an appropriate internal surface temperature (approximately 150°C, 302°F or higher).

[0070] Warm process-off gas containing dust from the quench chamber 108 is passed to the wet dust collector 112. A pressure relief valve 111 may be located above the wet gas bend, as shown, to provide an additional safety outlet in case of pressure rise or SRV slag foaming.

[0071] The warm gas containing dust is regulated by an additional water spray in the dust collector 112 and then passes through a conical valve 113, which creates fine water droplets (for efficient dust capture and removal). The pressure drop across the conical valve is typically 0.2–0.5 bar, and the position of the conical valve is used to regulate the pressure in the SRV (typically operating at a gauge of 0.5–0.8 bar). From this point, the purified gas 114 moves to further gas processing steps downstream.

[0072] Figure 2 shows further details of the quench system 200, including the high-speed quench nozzle system 106, as described and illustrated in relation to Figure 1. A flowing high-temperature process-off gas 201, typically at a temperature of 1600–2000°C (2912–3632°F), contains droplets of molten slag and a descending wall film of liquid slag 202 (also known as a "pipe" of solid slag). The wall of the dogleg outlet duct 104 is terminated by a smooth, water-cooled copper rim 203. The molten slag flows downward over the surface of the cool copper rim 203, but the adhesion between the solid slag portion of the frozen layer and the water-cooled copper rim 203 is weak or nonexistent. This deprives the "pipe" of solid slag of some mechanical strength, making it more susceptible to shattering when quenched and cooled by the nozzle system 106.

[0073] Water 204 (or other coolant) is sprayed through the spray nozzles of the nozzle system 106 to generate a spray plume 205. This spray plume, in conjunction with the application of thermal stress, results in the rapid solidification and cooling of the slag, thereby breaking the solid slag into sufficiently small (typically less than 100 mm in diameter or 3.94 inches in diameter) slag pieces 206, which can then be controlled and removed by appropriate downstream equipment as described herein.

[0074] The amount of water 204 added from the first spray nozzle of the nozzle system 106 may be less than the total amount needed to achieve the desired final temperature. In this case, additional water 207 can be added in one or more secondary downstream nozzles 107 to generate one or more spray plumes 208. It should be understood that the majority of the cooling of the process off gas in the quench system 200 occurs through the quench nozzle system 106. The cooling provided by duct cooling (e.g., steam pipes) may be a smaller portion of the cooling of the process off gas, or may be negligible.

[0075] Figure 3 is a three-dimensional view of the high-speed quench system 200, including the nozzle system 106. The dogleg outlet terminates with a water-cooled copper rim 301 (shown as 203 in Figure 2). The spray water 302 shown in Figure 3 generates a relatively flat spray plume 303 directed radially (inward). The water injection may be augmented by gas injection to obtain an appropriate balance between inward momentum, droplet size, and gas intake.

[0076] It should be understood that the nozzle spray pattern of the nozzle system 106 shown in Figure 2 is generally inward and directed at a downward angle in the same direction as the process-off gas flow. However, in other embodiments, the nozzle spray pattern of the nozzle system 106 shown in Figure 3 is generally inward and horizontal with respect to the process-off gas flow. Furthermore, the radial spray pattern of the nozzle can also be directed directly, or at least partially, upward with respect to the process-off gas flow at the dog leg duct outlet, although this direction may be unfavorable for solid slag formation.

[0077] It should be further understood that, in some embodiments, in addition to or instead of the rim 203 described herein, which can be used to help break up the "pipes" of solid slag into solid pieces, other means of crushing, such as the mechanical action of a member (e.g., a rod, block, part of the rim, etc.) that can be actuated to move in and out of the duct outlet and / or quench chamber 108, can be utilized to help crush the solid slag into solid slag pieces.

[0078] As previously stated, the use of the invention described herein may render the ability to recover heat from process-off gases impossible. However, in some embodiments of the invention, heat recovery may still be possible by using a configuration including a dry-bottom embodiment and operating the system so that the temperature at the outlet of chamber 108 is intentionally maintained at the upper end of the temperature range (e.g., 500–600°C, i.e., 932–1112°F). Under such conditions, tube fouling proceeds slowly and / or is well manageable in a practical sense, and heat recovery may become possible again. If so, installing a heat recovery tube for steam generation between chamber 108 and wet dust collector 112 could be considered a legitimate variation that fits perfectly within the scope of the invention.

[0079] To supplement this disclosure, this application further incorporates, by reference, the entirety of the following references. 1. U.S. Patent No. 6989042, "Direct Smelting Process and Apparatus," priority date April 17, 2000. 2. U.S. Patent No. 8,221,675, "Direct Smelting Vessel and Cooler Therefor," priority date May 18, 2006. 3. U.S. Patent No. 9175907, "Direct Smelting Process and Apparatus," priority date February 9, 2010. 4. Australian Patent No. 2011301784 (WO2012 / 034184), "Direct Smelting Process," priority date September 15, 2011. 5. U.S. Patent No. 9,359,656, “Direct Smelting Process,” priority date February 9, 2012. 6. PCT / AU2012 / 000293 (WO2012 / 126055), "Direct Smelting Process for High Sulphur Feed," Priority Date: March 21, 2012 7.PCT / AU2012 / 001486 (WO2013 / 082658), "Starting a Smelting Process", priority date 6 December 2011 8.PCT / AU2012 / 001481(WO2013 / 082653), "Starting a Smelting Process", priority date 6 December 2011 9.PCT / AU2012 / 001487(WO2013 / 082659), "Starting a Smelting Process", priority date 6 December 2011 10.CT / AU2014 / 001098(WO2015 / 081376), "Smelting Process and Apparatus", priority date December 4, 2014 11. PCT / AU2014 / 001146 (WO2015 / 089563), "Smelting Process and Apparatus," Priority Date: December 19, 2014

[0080] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as those generally understood by those skilled in the art to which the present invention pertains. It will be further understood that terms used herein should be interpreted in a way that is consistent with their meaning in the context of this specification and the related art, and should not be interpreted in an idealized or overly formal sense unless expressly defined herein. The use of certain technical terms herein is merely for convenience and should not be interpreted as limiting the invention. For example, words such as “up,” “down,” “left,” “right,” “horizontal,” “vertical,” “upward,” and “downward” merely describe the configurations shown in the drawings. The components referred to may be oriented in a different direction than those shown in the drawings, and therefore, unless otherwise specified, technical terms should be understood to encompass such variations.

[0081] When an element is described as being “connected,” “linked,” or “operably linked” to another element, it should be understood that these elements may be formed as a single entity with each other, or they may be formed separately and then combined into one. Furthermore, “connected,” “linked,” or “operably linked” may mean that the element is directly connected, linked, or operablely linked to the other element, or there may be intervening elements between them. Moreover, “connected,” “linked,” or “operably linked” may mean that these elements are detachable from each other, or they may mean that they are permanently linked together as one.

[0082] This specification describes specific embodiments of the present invention. Those skilled in the art will likely recognize many modifications and other embodiments of the present invention described herein, having the advantages of the teachings presented in the preceding description and accompanying drawings. Therefore, it should be understood that the present invention is not limited to the specific embodiments disclosed, and that modifications, other embodiments, and combinations of embodiments are intended to be included within the scope of the appended claims. Certain terms are used herein, but these are used only in a general and descriptive sense and are not intended to be limiting.

Claims

1. A direct smelting method for producing molten metal and slag within a direct smelting system, wherein the direct smelting system is (i) A smelting reduction vessel (SRV) for housing the bath of molten metal and slag, wherein carbonaceous material is introduced, metal-containing ore is introduced into the slag or supplied from above by gravity, the metal-containing ore is smelted to produce carbon-containing molten metal and molten slag, and oxygen-containing gas is introduced into the upper space of the SRV to partially burn the gas derived from the bath and supply SRV process heat, (ii) A quench system operably connected to the SRV, the quench system comprising a dog leg duct and a quench nozzle system operably connected to the dog leg duct, Equipped with, The aforementioned direct smelting method is The process off gas is received from the SRV into the dog leg duct, and the process off gas contains the taken-in molten slag. The process off gas is guided from the dog leg duct to the quench nozzle system, To form a solid slag, the process off gas is rapidly cooled to a temperature of 600°C or less using the quench nozzle system. The aforementioned solid slag is crushed to produce solid slag pieces for extraction, Direct smelting methods, including those mentioned above.

2. The direct smelting system further comprises a cyclone converter (CCF) connected to the SRV, the CCF receiving the process-off gas from the SRV, the metal-containing ore, a portion of the oxygen-containing gas, and flux material being fed into the CCF, the metal-containing ore being mostly melted and partially pre-reduced before entering the SRV, The method according to claim 1, wherein receiving the process off gas in the dog leg duct includes receiving the process off gas from the CCF.

3. The method according to claim 1, wherein the process off gas in the dog leg duct is maintained at a gas temperature of 1400°C (2552°F) or higher before the rapid cooling by the quench nozzle system.

4. The method according to claim 1, wherein the average flight time of process-off gas particles in the quench nozzle system is 1 second or less.

5. The quench nozzle system uses the process off gas 1000 Nm ３ The method according to claim 1, wherein 0.8 to 2.0 tons of water are injected per hour, and the final gas temperature after the water vaporization is 150°C (302°F) or higher and 600°C (1112°F) or lower.

6. The quench nozzle system preferably uses a process off gas of 1000 Nm ３ The method according to claim 5, wherein 1.0 to 1.5 tons of water are injected per hour, and the final gas temperature after the vaporization of the water is preferably within the temperature range of 200 to 300°C (392 to 572°F), including the values ​​at both ends.

7. The method according to claim 5, wherein the solid slag pieces are removed in a dry state from a collection container located at the bottom of the quench chamber.

8. The quench nozzle system uses the process off gas 1000 Nm ３ The method according to claim 1, wherein 2 to 6 tons of water are injected per hour, and the final gas temperature is approximately equal to the local water saturation temperature at the process pressure at that point.

9. The quench nozzle system preferably uses a process off gas of 1000 Nm ３ The method according to claim 8, wherein 3 to 5 tons of water are sprayed per hour.

10. The method according to claim 8, wherein liquid water is present at the bottom of the quench chamber and the solid slag fragments are removed from the collection container of the quench chamber in a wet state.

11. The method according to claim 1, wherein the quench system further comprises an outlet rim upstream of the quench nozzle system, the outlet rim assisting in crushing the solid slag into solid slag pieces.

12. A direct smelting system for producing molten metal and slag, (i) A smelting reduction vessel (SRV) comprising a bath containing the molten metal and the slag, receiving carbonaceous material and metal-containing ore supplied to the slag by gravity from above or through input, smelting the metal-containing ore in the bath to produce carbon-containing molten metal and molten slag, receiving oxygen-containing gas introduced into the upper space to partially burn the gas originating from the bath and supply heat to the SRV, (ii) A quench system operably connected to the SRV, the quench system comprising a dog leg duct and a quench nozzle system operably connected to the dog leg duct, wherein process off gas from the SRV containing the taken-in molten slag passes through the dog leg duct to the quench nozzle system, the process off gas is rapidly cooled by the quench nozzle system to a temperature of 600°C (1112°F) or less to form solid slag, and the solid slag is crushed into solid slag pieces for removal, A direct smelting system equipped with [the necessary components].

13. The direct smelting system further comprises a cyclone converter (CCF) connected to the SRV, the CCF receiving the process-off gas from the SRV, the metal-containing ore, a portion of the oxygen-containing gas, and flux material being fed into the CCF, the metal-containing ore being mostly melted and partially pre-reduced before entering the SRV, The system according to claim 12, wherein the dog leg duct receives the process off gas from the CCF.

14. The system according to claim 12, wherein the process off gas in the dog leg duct is maintained at a gas temperature of 1400°C (2552°F) or higher before the rapid cooling by the quench nozzle system.

15. The system according to claim 12, wherein the average flight time of process gas particles in the quench nozzle system is 1 second or less.

16. The system according to claim 12, wherein the majority of the cooling of the process gas in the quench system is performed by the quench nozzle system, and less of the cooling is performed by duct cooling.

17. The quench nozzle system uses the process off gas 1000 Nm ３ The system according to claim 12, wherein 0.8 to 2.0 tons of water are injected per hour, and the final gas temperature after water vaporization is between 150°C (302°F) and 600°C (1112°F).

18. The system according to claim 17, wherein the solid slag fragments are removed in a dry state from a collection container located at the bottom of the quench chamber.

19. The quench nozzle system uses the process off gas 1000 Nm ３ The system according to claim 12, wherein 2 to 6 tons of water are injected per hour, and the final gas temperature is approximately equal to the local water saturation temperature at the process pressure at that time.

20. The system according to claim 19, wherein liquid water is present at the bottom of the quench chamber, and the solid slag fragments are removed from the collection container of the quench chamber in a wet state.

21. The system according to claim 12, wherein the quench system further comprises an outlet rim upstream of the quench nozzle system, the outlet rim assisting in crushing the solid slag into solid slag pieces.

22. A method for forming pig iron using a quench system operably connected to a smelting reduction vessel (SRV), wherein the quench system comprises a dog leg duct and a quench nozzle system operably connected to the dog leg duct, and the method is Forming molten metal in the aforementioned SRV, The process off gas is received from the SRV into the dog leg duct, and the process off gas contains the taken-in molten slag. The process off gas is guided from the dog leg duct to the quench nozzle system, To form a solid slag, the process off gas is rapidly cooled to a temperature of 600°C or less using the quench nozzle system. The aforementioned solid slag is crushed to produce solid slag pieces for extraction, The process of extracting the molten metal from the SRV, Forming pig iron from the molten metal, Methods that include...

23. A quench system used in conjunction with a molten reduction vessel (SRV) for producing molten metal and slag, wherein the quench system is: Dog leg ducts and The system comprises a quench nozzle system operably connected to the dog leg duct, A quench system in which process-off gas from the SRV containing the taken-in molten slag passes through the dog leg duct to the quench nozzle system, the process-off gas is rapidly cooled by the quench nozzle system to a temperature of 600°C (1112°F) or less to form solid slag, and the solid slag is crushed into solid slag pieces for removal.

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