Chemical looping gasification-based red mud reduction-magnetic separation recovery device and process

Abstract

A chemical looping gasification-based red mud reduction-magnetic separation recovery device and process. The device comprises a chemical looping gasification device, a red mud feeder, a bag dust collector, and a magnetic separator. The chemical looping gasification device comprises an air reactor, a first cyclone separator, a fuel reactor, a solid fuel feeder, and a second cyclone separator. The upper portion of the air reactor is connected to a feed port of the first cyclone separator; a discharge outlet of the first cyclone separator is connected to the upper portion of the combustion reactor; the upper portion of the fuel reactor is connected to a feed port of the second cyclone separator; the top portion of the second cyclone separator is connected to the bag dust collector by means of a fuel reactor tail flue; the magnetic separator is connected to an ash discharge port of the bag dust collector; the red mud feeder is connected to the bottom of the fuel reactor. In the present application, chemical looping gasification and red mud reduction roasting-magnetic separation are combined to achieve iron element recovery and oxygen carrier substitution.

Description

A red mud reduction magnetic separation recovery device and process based on chemical looping gasification Technical Field

[0001] This article relates to the fields of chemical looping gasification and industrial solid waste resource utilization. The invention is a technology for iron metal recovery and reuse that utilizes a high-temperature gas-based reducing agent in a fuel reactor of chemical looping gasification to in-situ reduce and roast weakly magnetic hematite in Bayer process red mud with high iron content, obtaining strongly magnetic magnetite or elemental iron, and then using a weak magnetic separation process to recover magnetic iron minerals from the red mud. Background Technology

[0002] Red mud is an alkaline solid waste emitted during the industrial refining of alumina. In 2023, my country's red mud emissions exceeded 100 million tons. The main processes for producing alumina are the sintering method and the Bayer process, with the Bayer process currently accounting for 90% of global production due to its low energy consumption. The alkalinity of red mud, exceeding 1 billion tons, poses a significant environmental hazard. However, the resource utilization rate of red mud is less than 10% of the emissions, primarily focusing on the preparation of building materials, environmental remediation, and the recovery of valuable metal resources. Since the bauxite raw material for the Bayer process contains iron, it also contains more than 30% hematite. Recovering the iron from this red mud is an effective method for reducing and recycling industrial solid waste.

[0003] Methods for recovering iron from red mud can be categorized into physical iron separation, including direct magnetic separation and gravity separation, and chemical iron extraction, including acid leaching and reduction roasting magnetic separation. Direct magnetic separation requires high-strength equipment with strong magnetic fields; gravity separation is negatively impacted by the agglomeration and coating of fine red mud powder, resulting in low iron separation efficiency. In acid leaching, the alkaline components of the red mud consume excessive amounts of acid, generating large quantities of waste liquid and residue, making it unsuitable for large-scale industrial production. Reduction roasting magnetic separation uses a reducing agent to reduce weakly magnetic hematite to strongly magnetic magnetite or elemental iron during roasting, followed by weak magnetic separation to recover the magnetic iron minerals. Reducing agents can be classified as solid carbonaceous reducing agents, gas-based reducing agents, and biomass reducing agents. However, solid-state reduction requires excessively high temperatures, leading to uneconomical energy costs; gas-state reduction has lower temperatures, while biomass gasification further reduces raw material costs.

[0004] Chemical looping combustion and gasification is an emerging environmentally friendly energy technology. It utilizes metal oxides as oxygen carriers, separating the oxidation-reduction processes of fuel and air into two separate reactors. The oxygen carrier is oxidized in the air reactor, carrying lattice oxygen, and reduced in the fuel reactor, releasing lattice oxygen. This cycle allows for continuous operation of chemical looping combustion or gasification. Separating air and fuel results in almost no nitrogen in the combustion flue gas or gasification products, significantly increasing the concentration of carbon dioxide and combustible gases, which is beneficial for efficient carbon capture and subsequent Fischer-Tropsch synthesis of syngas. In chemical looping gasification, the fuel reactor operates in a high-temperature reducing atmosphere, suitable for gas-based reduction roasting and magnetic separation to recover iron from red mud. Furthermore, the high hematite content of red mud can also act as a partial oxygen carrier, being reduced to magnetite or elemental iron after a small number of cycles. The reduced, fine-particle red mud is recovered from the fly ash separated from the fuel reactor flue gas or syngas.

[0005] Invention patent CN118127314A (Invention title: A method for extracting metallic iron from high-iron red mud through efficient reduction in an electric furnace) discloses a method where red mud is mixed with coal, pelletized, dried, and then added to a 1600°C electric furnace containing molten scrap steel. The iron in the red mud is directly reduced and introduced into the molten steel, while the remaining slag phase is separated through melting. However, this invention has excessively high reduction temperatures and energy consumption, and requires additional coal and carbon injection to maintain a reducing atmosphere, resulting in high overall costs and hindering large-scale industrial application. Summary of the Invention

[0006] The following is an overview of the subject matter described in detail herein. This overview is not intended to limit the scope of the claims.

[0007] To address the issues of raw material, equipment, and energy costs associated with the use of an additional gasifier to prepare gaseous reducing agents and the high-temperature reduction furnace required in the red mud reduction roasting and magnetic separation iron recovery process, this application utilizes a chemical looping gasification (CLP) process fuel reactor that simultaneously possesses the advantages of high temperature and reducible syngas feedstock. Combining the high hematite content of Bayer process red mud, which can be used as an oxygen carrier, and the small particle size of red mud powder, high-iron Bayer process red mud powder is used as part of the oxygen carrier in the CLP process. This powder is fed into the fuel reactor for in-situ high-temperature reduction to obtain magnetite or elemental iron. After a brief cycle, the reduced red mud is discharged as fly ash with the flue gas, and then subjected to weak magnetic separation to recover iron from the red mud. This application organically combines two environmentally friendly processes: chemical looping gasification and red mud reduction roasting and magnetic separation, achieving low-energy, low-cost recovery of iron from red mud and a low-cost replacement of the oxygen carrier in chemical looping gasification.

[0008] The first aspect of this application provides a red mud reduction and magnetic separation recovery device based on chemical looping gasification, comprising: a chemical looping gasification device, a red mud feeder, a bag filter, and a magnetic separator; the chemical looping gasification device comprises: an air reactor, a first cyclone separator, a fuel reactor, a solid fuel feeder, and a second cyclone separator;

[0009] The upper part of the air reactor is connected to the inlet of the first cyclone separator, the outlet of the first cyclone separator is connected to the upper part of the combustion reactor, the upper part of the fuel reactor is connected to the inlet of the second cyclone separator, the top of the second cyclone separator is connected to the bag filter through the tail flue of the fuel reactor, and the magnetic separator is connected to the ash discharge port of the bag filter; the red mud feeder is connected to the bottom of the fuel reactor, and the solid fuel feeder is connected to the bottom of the fuel reactor and is located above the solid fuel feeder.

[0010] In one exemplary embodiment, the chemical looping gasification apparatus further includes: a first feeder, a second feeder, a third feeder, and an oxygen carrier feeder; wherein the oxygen carrier feeder is connected to the bottom of the air reactor, the first feeder is connected to the middle of the fuel reactor and the bottom of the air reactor; the discharge port leg of the first cyclone separator is connected to the upper part of the fuel reactor through the second feeder; and the discharge port leg of the second cyclone separator is connected to the bottom of the fuel reactor through the third feeder.

[0011] In one exemplary embodiment, the upper part of the air reactor is connected to one end of the top air reactor horizontal flue via an air reactor riser pipe, and the other end of the air reactor horizontal flue is connected to the feed inlet of the first cyclone separator.

[0012] In one exemplary embodiment, the upper part of the fuel reactor is connected to one end of the top fuel reactor horizontal flue via a fuel reactor riser pipe, and the other end of the fuel reactor horizontal flue is connected to the feed inlet of the second cyclone separator.

[0013] In one exemplary embodiment, the chemical looping gasification apparatus further includes a compressor connected to the bag filter for compressing the high-concentration carbon dioxide and syngas generated during the gasification process.

[0014] In one exemplary embodiment, the ash discharge port is located at the lower part of the bag filter, and the compressor is connected to the gas outlet at the upper part of the bag filter.

[0015] In one exemplary embodiment, the top of the first cyclone separator is further provided with a first gas outlet, which is connected to the tail flue of the air reactor for discharging nitrogen generated in the air reactor.

[0016] In one exemplary embodiment, the top of the second cyclone separator is further provided with a second gas outlet, which is connected to the bag filter through the tail flue of the fuel reactor.

[0017] In one exemplary embodiment, the air reactor is a rapid bed, and an air inlet is provided at the bottom of the air reactor for introducing air as fluidizing air.

[0018] In one exemplary embodiment, the fuel reactor is a turbulent bed, and the bottom of the fuel reactor is provided with inlets for water vapor and recirculated flue gas, which are used to introduce water vapor and recirculated flue gas as fluidizing air.

[0019] In one exemplary embodiment, the bottom of the first return feeder, the second return feeder and the third return feeder are respectively provided with steam inlets for introducing steam from an external steam boiler as fluidizing air.

[0020] In one exemplary embodiment, both the solid fuel feeder and the red mud feeder are screw feeders.

[0021] In one exemplary embodiment, the magnetic separator is a weak magnetic separator.

[0022] The second aspect of this application provides a red mud reduction and magnetic separation recovery process based on chemical looping gasification, which is implemented using the aforementioned red mud reduction and magnetic separation recovery device based on chemical looping gasification, and includes the following steps:

[0023] S1. Pretreatment of red mud raw materials;

[0024] S2. Chemical looping gasification produces syngas;

[0025] S3. Red mud input and reduction;

[0026] S4. Separation of reduced red mud; and

[0027] S5. Magnetic separation to recover iron.

[0028] In one exemplary embodiment, the pretreatment of the red mud raw material in step S1 includes: selecting red mud raw material with a ferric oxide content of 30% or more, drying (e.g., air-drying or sun-drying) and crushing the red mud raw material to obtain red mud powder. The red mud raw material originates from solid waste discharged during the Bayer process for alumina refining. Because Bayer process red mud is discharged in slurry form, the original red mud deposited after treatment and used for damming has a high water content and is in the form of mud lumps.

[0029] In one exemplary embodiment, in step S1, the particle size of the red mud powder is 5-50 μm.

[0030] In an exemplary embodiment, step S2, chemical looping gasification to generate syngas, includes: starting and operating the chemical looping gasification device (e.g., through steps such as ignition, heating, introducing oxygen carrier, and switching flue gas circulation) to a self-heating and stable stage, and adjusting the equivalence ratio of air to solid fuel and the oxygen carrier circulation volume to obtain nitrogen-free, highly combustible, and high-carbon dioxide syngas.

[0031] In one exemplary embodiment, the oxygen carrier has a particle size of 150-350 μm.

[0032] In one exemplary embodiment, in step S2, the solid fuel is coal or biomass.

[0033] In one exemplary embodiment, in step S2, the bottom temperature of the fuel reactor is 850-950°C, and the operating pressure of the fuel reactor is 0.1-1 MPa.

[0034] In one exemplary embodiment, in step S2, the operating temperature of the air reactor is 900°C-1100°C.

[0035] In an exemplary embodiment, step S3, the input and reduction of red mud, includes: inputting the red mud powder prepared in step S1 into the bottom of the high-temperature fuel reactor of the chemical loop gasification device; the red mud powder undergoes a redox reaction with the syngas generated by the solid fuel gasification; and the hematite in the red mud is reduced. Specifically:

[0036] After the chemical looping gasification device in step S2 has been operating stably and continuously, the red mud powder prepared in step S1 is fed into the high-temperature fuel reactor. The red mud powder undergoes a redox reaction with the syngas (such as carbon monoxide and hydrogen) generated by the solid fuel gasification. The hematite in the red mud is reduced to magnetic magnetite or even elemental iron. At the same time, the red mud powder also provides lattice oxygen in the hematite, which can replace part of the oxygen carrier or participate in a small amount of chemical looping.

[0037] In an exemplary embodiment, step S4, the separation of reduced red mud, includes: the reduced red mud powder being separated from the oxygen carrier by the second cyclone separator of the chemical loop gasification device, and then being captured by a bag filter; specifically:

[0038] Since the red mud powder is reduced to magnetite, the particle size of the red mud powder is much smaller than that of the oxygen carrier (such as ilmenite). The reduced red mud powder, along with the fluidized flue gas, is separated from the oxygen carrier by the second cyclone separator and enters the bag filter to be captured. In this process, the alkaline red mud powder can also absorb and remove acidic gases such as sulfur dioxide from the flue gas.

[0039] In an exemplary embodiment, step S4 further includes: some of the larger particles in the reduced red mud powder are introduced into the air reactor along with the oxygen carrier to participate in the chemical chain cycle;

[0040] Optionally, the red mud powder participating in the chemical cycle accounts for approximately 10% of the total red mud powder.

[0041] In one exemplary embodiment, step S5, magnetic separation for iron recovery, includes: transporting the red mud powder captured by the bag filter (e.g., via belt conveyor) into the magnetic separator for separation and recovery. The magnetic iron-containing components are separated from the tailings, which can be used to manufacture building materials or improve soil conditions.

[0042] In one exemplary embodiment, the iron recovery rate of the red mud reduction magnetic separation recovery process based on chemical looping gasification exceeds 80%.

[0043] Compared with existing technologies, the process designed in this application has the following main technical advantages:

[0044] (1) Low energy consumption cost. There is no need to build a separate gasifier and high-temperature reduction furnace, and no need to provide additional solid or gaseous reducing agents. The high temperature and reducing atmosphere of the chemical loop gasification device are directly utilized in situ, saving equipment and fuel expenses and realizing economical reduction roasting of red mud.

[0045] (2) Realize the resource utilization of red mud. Through reduction roasting and magnetic separation, the hematite in the red mud is reduced to magnetite or even elemental iron and then separated and recovered. The tailings of the magnetic separation can be used to prepare building materials and improve soil, etc., realizing the high-value-added, reduced-volume, harmless, and resource-based reuse of red mud, which is environmentally friendly.

[0046] (3) Convenient input and output. Red mud powder can be continuously fed into the fuel reactor. Due to its small particle size, it can easily enter the flue gas and become fly ash without mixing with the original oxygen carrier. After being separated by cyclone separator and bag filter dust collector, the fly ash quickly enters the weak magnetic separation to recover iron.

[0047] (4) Reduce the amount of oxygen carrier. The hematite in red mud provides some lattice oxygen, which reduces the need for oxygen carrier to transport lattice oxygen, reduces the amount of oxygen carrier circulation in chemical looping gasification, saves oxygen carrier costs, and does not affect the continuous and stable operation of chemical looping gasification.

[0048] In summary, this chemical looping gasification reduction process for red mud has the advantages of low energy consumption and cost, realization of red mud resource utilization, convenient input and output, and reduced oxygen carrier usage. These advantages make this invention have a wide range of industrial applications in the application scenarios of iron recovery from red mud.

[0049] This invention integrates chemical looping gasification and red mud reduction. Utilizing high temperature and syngas, it enables in-situ reduction of red mud during chemical looping gasification, followed by magnetic separation to recover iron. This invention reduces the energy consumption cost of reduction roasting, reduces the volume of industrial solid waste red mud for harmless and resource-efficient utilization, and achieves convenient discharge of red mud after continuous feeding and reduction reaction, followed by weak magnetic separation for iron recovery. It also saves on oxygen carrier costs without affecting the stable operation of chemical looping gasification. The in-situ reduction of red mud followed by magnetic separation for iron recovery during chemical looping gasification can be scaled up for large-scale industrial production.

[0050] Other features and advantages of this application will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the application. Other advantages of this application can be realized and obtained by means of the embodiments described in the description and the accompanying drawings. Attached Figure Description

[0051] The accompanying drawings are used to provide an understanding of the technical solutions of this application and constitute a part of the specification. They are used together with the embodiments of this application to explain the technical solutions of this application and do not constitute a limitation on the technical solutions of this application.

[0052] Figure 1 is a schematic diagram of a red mud reduction magnetic separation recovery device based on chemical looping gasification. Detailed Implementation

[0053] This application describes several embodiments, but these descriptions are exemplary and not limiting, and it will be apparent to those skilled in the art that many more embodiments and implementations are possible within the scope of the embodiments described herein. Although many possible combinations of features are shown in the drawings and discussed in the detailed description, many other combinations of the disclosed features are also possible. Unless specifically limited, any feature or element of any embodiment may be used in combination with, or may replace, any feature or element of any other embodiment.

[0054] This application includes and contemplates combinations of features and elements known to those skilled in the art. The embodiments, features, and elements disclosed in this application can also be combined with any conventional features or elements to form unique inventive solutions. Any feature or element of any embodiment can also be combined with features or elements from other inventive solutions to form another unique inventive solution. Therefore, it should be understood that any feature shown and / or discussed in this application can be implemented individually or in any suitable combination. Therefore, the embodiments are not limited except by the limitations imposed by the appended claims and their equivalents. Furthermore, various modifications and changes can be made within the scope of the appended claims.

[0055] Furthermore, in describing representative embodiments, the specification may have presented methods and / or processes as a specific sequence of steps. However, the method or process should not be limited to the specific order of steps described herein, to the extent that it does not depend on such a specific order. As will be understood by those skilled in the art, other sequences of steps are also possible. Therefore, the specific order of steps set forth in the specification should not be construed as a limitation of the claims. Moreover, the claims concerning the method and / or process should not be limited to the steps performed in the written order, and those skilled in the art will readily understand that these orders can be varied and still remain within the spirit and scope of the embodiments of this application.

[0056] Example 1.

[0057] As shown in Figure 1, a red mud reduction and magnetic separation recovery device based on chemical looping gasification includes: a chemical looping gasification device, a red mud feeder X503, a bag filter S803, and a magnetic separator S804, wherein:

[0058] The chemical looping gasification device includes: an air reactor R101, a fuel reactor R102, an air reactor riser R104, a fuel reactor riser R103, a first cyclone separator V201, a second cyclone separator V202, a first return feeder X250, a second return feeder X201, a third return feeder X202, an air reactor tail flue S801, a fuel reactor tail flue S802, a compressor S805, an oxygen carrier feeder X501, and a solid fuel feeder X502.

[0059] The first return feeder X250 connects the middle of the fuel reactor R102 and the bottom of the air reactor R101; the upper part of the air reactor R101 is connected to one end of the top air reactor horizontal flue via the air reactor riser pipe R104, and the other end of the air reactor horizontal flue is connected to the inlet of the first cyclone separator V201; the discharge leg of the first cyclone separator V201 is connected to the upper part of the fuel reactor R102 via the second return feeder X201; the upper part of the fuel reactor R102 is connected to one end of the top fuel reactor horizontal flue via the fuel reactor riser pipe R103, and the other end of the fuel reactor horizontal flue is connected to the second cyclone separator V201. The feed inlet of the second cyclone separator V202 is connected to the bottom of the fuel reactor R102 via the third return feeder X202; the oxygen carrier feeder X501 is connected to the bottom of the air reactor R101; the solid fuel feeder X502 is connected to the bottom of the fuel reactor R102; the top of the first cyclone separator V201 is provided with a first gas outlet, which is connected to the tail flue S801 of the air reactor for discharging nitrogen generated by the air reactor; the top of the second cyclone separator V202 is provided with a second gas outlet, which is connected to the bag filter S803 via the tail flue S802 of the fuel reactor.

[0060] The bag filter S803 is located at the end of the tail flue S802 of the fuel reactor, and the magnetic separator S804 is connected to the ash discharge port of the bag filter S803; the red mud feeder X503 is connected to the bottom of the fuel reactor R102 and is located above the solid fuel feeder X502; the magnetic separator S804 is a weak magnetic separator.

[0061] The chemical loop gasification device also includes a compressor S805, which is connected to the bag filter S803 and is used to compress the high-concentration carbon dioxide and syngas generated during the gasification process. Specifically, the ash discharge port is located at the lower part of the bag filter S803, and the compressor S805 is connected to the gas outlet at the upper part of the bag filter S803.

[0062] The air reactor R101 is a rapid bed, and an air inlet is provided at the bottom of the air reactor R101 for introducing air as fluidizing air; the fuel reactor R102 is a turbulent bed, and an inlet for water vapor and recirculated flue gas is provided at the bottom of the fuel reactor R102 for introducing water vapor and recirculated flue gas as fluidizing air; water vapor is introduced at the bottom of the first return feeder X250, the second return feeder X201, and the third return feeder X202 as fluidizing air.

[0063] Both the solid fuel feeder X502 and the red mud feeder X503 are screw feeders.

[0064] Example 2.

[0065] A red mud reduction and magnetic separation recovery process based on chemical looping gasification using the apparatus described in Example 1 includes the following steps:

[0066] S1. Pretreatment of red mud raw materials;

[0067] Red mud raw materials with a ferric oxide content of over 30% are selected and dried (e.g., air-dried or sun-dried) and crushed into small particles to obtain red mud powder. The red mud raw materials originate from solid waste discharged during the Bayer process for alumina refining. Because Bayer process red mud is discharged in slurry form, the original red mud used for damming and accumulation after treatment has a high water content and is in the form of mud lumps; the particle size of the red mud is 5-50 μm.

[0068] S2. Chemical looping gasification produces syngas.

[0069] The chemical loop gasification device is started up and, after steps such as ignition, heating, introduction of oxygen carrier, and switching of flue gas circulation, enters a self-heating and stable stage. The equivalence ratio of air to solid fuel and the circulation volume of oxygen carrier are adjusted to obtain nitrogen-free, highly combustible, and high-carbon dioxide syngas. The oxygen carrier has a particle size of 150-350 μm. The solid fuel is coal or biomass.

[0070] S3 Red Mud Input and Reduction

[0071] The dried and crushed red mud powder from step S1 is fed into the bottom of fuel reactor R102 via red mud feeder X503. In the high-temperature fuel reactor R102, the hematite component in the red mud powder undergoes an oxidation-reduction reaction with the syngas generated from the gasification of solid fuel. The hematite in the red mud powder is reduced to magnetic magnetite or even elemental iron. At the same time, the red mud powder also provides lattice oxygen, which can replace part of the oxygen carrier or participate in a small amount of chemical looping.

[0072] Separation of S4 reduced red mud

[0073] The reduced red mud powder is separated from the oxygen carrier by the second cyclone separator V202 of the chemical loop gasification device and then captured by the bag filter S803; specifically:

[0074] Because the red mud powder, after being reduced to magnetite, has a smaller particle size than the oxygen carrier, it easily enters the flue gas of the fuel reactor R102. There, it separates from the oxygen carrier in the second cyclone separator V202 and is captured in the bag filter S803. Some of the larger red mud powder particles enter the air reactor R101 with the oxygen carrier, undergoing a small amount of chemical looping. During this process, the alkaline red mud powder can also absorb and remove acidic gases such as sulfur dioxide from the flue gas; this portion of red mud powder participating in the chemical looping accounts for approximately 10% of the total.

[0075] S5 magnetic separation recovers iron.

[0076] The red mud powder captured by the bag filter S803 (e.g., via belt conveyor) is transported into the magnetic separator S804 for separation and recovery. The magnetic iron-containing components are separated from the tailings, which can be used to manufacture building materials or improve soil. In this process, the iron recovery rate exceeds 80%.

[0077] Example 3.

[0078] In Example 2, the chemical looping gasification process in step S2 to generate syngas includes the following steps:

[0079] S21 Pyrolysis-Reduction Reaction: Crushed solid fuel particles are fed into fuel reactor R102 via solid fuel feeder X502, where they are thoroughly mixed with the high-temperature oxygen-carrying bed material. The solid fuel particles are rapidly heated by the oxygen-carrying body, resulting in a rapid pyrolysis reaction that releases volatiles. The bottom temperature of fuel reactor R102 is 850-950℃, and the operating pressure of fuel reactor R102 is 0.1-1MPa. The heat required for solid fuel pyrolysis is provided by the oxygen-carrying body, which also acts as an oxidant. Some of the coke or semi-coke generated by the pyrolysis reaction then undergoes an oxidation reaction with the lattice oxygen released by the oxygen-carrying body to produce syngas. During this process, the oxygen-carrying body is reduced to a reduced state. Some of the coke or semi-coke reacts with the gasifying agent water vapor to generate syngas. The syngas generated by the reaction, some unburned carbonaceous fuel, ash, the reduced red mud powder from Example 2, and a small amount of oxygen-carrying body are transported through the fuel reactor riser R10. 3. The gas enters the second cyclone separator V202 for gas-solid separation. Unburned carbon and oxygen-carrying particles, due to their larger particle size, are separated and fall into the third return feeder X202, and are then sent back to the fuel reactor R102 for further conversion. The reduced red mud powder and ash from Example 2, due to their smaller particle size, are discharged with the flue gas. The flue gas exchanges heat with the circulating water around the fuel reactor R102 through the flue heating surface in the tail flue S802. The steam boiler and the first return feeder X25 0. The second return feeder X201, the third return feeder X202 and the fuel reactor R102 are connected to provide steam as fluidizing air to the first return feeder X250, the second return feeder X201, the third return feeder X202 and the fuel reactor R102; then the flue gas undergoes gas component and solid separation (including reduced red mud) in the bag filter S803, the solids are conveyed to the magnetic separator S804, and the gas is upgraded by the compressor S805 to obtain syngas product;

[0080] S22 Oxidation Reaction: The reduced oxygen carrier enters the first return feeder X250 through the overflow pipe and is then sent to the air reactor R101 to contact with air. The reduced oxygen carrier undergoes an oxidation reaction, releasing a large amount of heat, and becomes an oxidized oxygen carrier. At the same time, the particles themselves heat up, heating the air reactor R101. At this time, the operating temperature of the air reactor R101 is 900℃-1100℃. The oxidized oxygen carrier is blown to the top of the air reactor R101 and then enters the first cyclone separator V201 for gas-solid separation. The gas component is mainly high-concentration nitrogen. The oxidized oxygen carrier falls into the second return feeder X201 and is then sent to the fuel reactor R102, thus completing the oxidation-reduction cycle reaction of the oxygen carrier.

[0081] In the description of this application, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top", "bottom", "inner", "outer", "clockwise", "counterclockwise", "axial", "radial", "circumferential", etc., indicating the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, are only for the convenience of describing this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this application.

[0082] Furthermore, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first," "second," etc., may explicitly or implicitly include at least one of those features.

[0083] In the description of this application, "multiple" means at least two, such as two, three, etc., unless otherwise expressly and specifically limited.

[0084] In this application, unless otherwise expressly specified and limited, the terms "installation," "connection," "joining," "fixing," etc., should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can be the internal communication of two components or the interaction between two components, unless otherwise expressly limited. Those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0085] In this application, unless otherwise expressly specified and limited, "above" or "below" the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0086] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0087] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A red mud reduction and magnetic separation recovery device based on chemical looping gasification, characterized in that, include: The system includes a chemical loop gasification unit, a red mud feeder, a bag filter, and a magnetic separator; the chemical loop gasification unit comprises: an air reactor, a first cyclone separator, a fuel reactor, a solid fuel feeder, and a second cyclone separator. The upper part of the air reactor is connected to the inlet of the first cyclone separator, the outlet of the first cyclone separator is connected to the upper part of the combustion reactor, the upper part of the fuel reactor is connected to the inlet of the second cyclone separator, the top of the second cyclone separator is connected to the bag filter through the tail flue of the fuel reactor, and the magnetic separator is connected to the ash discharge port of the bag filter; the red mud feeder is connected to the bottom of the fuel reactor, and the solid fuel feeder is connected to the bottom of the fuel reactor and is located above the solid fuel feeder.

2. The apparatus according to claim 1, characterized in that, The chemical loop gasification device further includes: a first return feeder, a second return feeder, a third return feeder, and an oxygen carrier feeder; The oxygen carrier feeder is connected to the bottom of the air reactor, and the first return feeder is connected to the middle of the fuel reactor and the bottom of the air reactor. The discharge leg of the first cyclone separator is connected to the upper part of the fuel reactor through the second return feeder. The discharge leg of the second cyclone separator is connected to the bottom of the fuel reactor through the third return feeder.

3. The apparatus according to claim 2, characterized in that, The upper part of the air reactor is connected to one end of the top air reactor horizontal flue via an air reactor riser pipe, and the other end of the air reactor horizontal flue is connected to the feed inlet of the first cyclone separator; the upper part of the fuel reactor is connected to one end of the top fuel reactor horizontal flue via a fuel reactor riser pipe, and the other end of the fuel reactor horizontal flue is connected to the feed inlet of the second cyclone separator.

4. The apparatus according to claim 2 or 3, characterized in that, The chemical loop gasification device also includes a compressor, which is connected to the bag filter. Optionally, the ash discharge port is located at the lower part of the bag filter, and the compressor is connected to the gas outlet at the upper part of the bag filter.

5. The apparatus according to claim 2 or 3, characterized in that, The top of the first cyclone separator is also provided with a first gas outlet, which is connected to the tail flue of the air reactor. The top of the second cyclone separator is also provided with a second gas outlet, which is connected to the bag filter through the tail flue of the fuel reactor.

6. The apparatus according to claim 2 or 3, characterized in that, The air reactor is a rapid bed, and an air inlet is provided at the bottom of the air reactor for introducing air as fluidizing air; and / or The fuel reactor is a turbulent bed, and its bottom is provided with inlets for steam and recirculated flue gas, used to introduce steam and recirculated flue gas as fluidizing air; and / or The bottom of the first return feeder, the second return feeder and the third return feeder are respectively provided with steam inlets for introducing steam from an external steam boiler as fluidizing air.

7. The apparatus according to claim 2 or 3, characterized in that, Both the solid fuel feeder and the red mud feeder are screw feeders; and / or The magnetic separator is a weak magnetic separator.

8. A red mud reduction and magnetic separation recovery process based on chemical looping gasification, characterized in that, This is achieved using the red mud reduction and magnetic separation recovery device based on chemical looping gasification as described in any one of claims 1 to 7, comprising the following steps: S1. Pretreatment of red mud raw materials; Red mud raw material with a ferric oxide content of more than 30% was selected, and the red mud raw material was dried and crushed to obtain red mud powder; S2. Chemical looping gasification produces syngas; The chemical looping gasification unit is started and operated to the self-heating and stable stage. The equivalence ratio of air to solid fuel and the oxygen carrier circulation volume are adjusted to obtain nitrogen-free, highly combustible, and high-carbon dioxide syngas. S3. Red mud input and reduction; Red mud powder prepared in step S1 is fed into the bottom of the high-temperature fuel reactor of the chemical loop gasification device. The red mud powder undergoes an oxidation-reduction reaction with the syngas generated by the solid fuel gasification, and the hematite in the red mud is reduced. S4. Separation of reduced red mud; The reduced red mud powder is separated from the oxygen carrier by the second cyclone separator of the chemical loop gasification device and then captured by the bag filter. S5. Magnetic separation for iron recovery The red mud powder captured by the bag filter is transported into the magnetic separator for separation and recovery.

9. The process according to claim 8, characterized in that, In step S1, the particle size of the red mud powder is 5-50 μm.

10. The process according to claim 8 or 9, characterized in that, The oxygen carrier has a particle size of 150-350 μm; and / or In step S2, the solid fuel is coal or biomass.

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