A method and system for producing alumina using aluminum-rich coal gangue

Abstract

The application discloses a method and system for producing alumina by using aluminum-rich coal gangue, and belongs to the field of secondary resource quality utilization and non-ferrous metallurgy. The method comprises the following steps: crushing and screening aluminum-rich coal gangue raw materials to obtain aluminum-rich coal gangue powder; pyrolyzing the aluminum-rich coal gangue powder under the carrying of hot air to obtain pyrolysis materials; performing first separation on the pyrolysis materials to obtain a high-temperature oil-gas mixture and a solid product; performing an activation reaction on the solid product under the carrying of carrying gas to obtain calcined aluminum-rich coal gangue; performing second separation on the calcined aluminum-rich coal gangue to obtain reaction tail gas and high-temperature active silicon-aluminum oxide; performing heat exchange and cooling on the high-temperature active silicon-aluminum oxide to obtain cooled active silicon-aluminum oxide; performing pre-desiliconization treatment on the cooled active silicon-aluminum oxide to obtain a treated product; and extracting aluminum from the treated product to obtain alumina. The method has the advantages of simple process, low energy consumption, reasonable utilization of energy, high extraction rate, reduced cost, and large-scale industrial application.

Description

Technical Field

[0001] This application relates to the fields of secondary resource utilization and non-ferrous metal metallurgy, and in particular to a method and system for producing alumina from aluminum-rich coal gangue. Background Technology

[0002] Coal gangue is a solid waste generated during coal mining, washing, and processing. Large-scale accumulation of coal gangue not only occupies land but also pollutes the environment. Currently, to make full use of coal gangue, it is mainly used in the production of building materials (such as bricks and cement) or for power generation. However, using coal gangue in building material production only utilizes it at a low added value, especially wasting valuable elements such as aluminum in aluminum-rich coal gangue. Using coal gangue for power generation presents problems such as low combustion efficiency and difficulty in controlling pollutant emissions.

[0003] Alumina is a key raw material in the aluminum industry, widely used in electrolytic aluminum production, ceramics, refractory materials, and other sectors. Currently, alumina production mainly relies on bauxite resources. Finding new sources of raw materials for alumina production and developing efficient, economical, and environmentally friendly production technologies are urgently needed.

[0004] Because aluminum-rich coal gangue contains abundant aluminum, methods for extracting aluminum from it are becoming increasingly widespread. However, existing coal gangue aluminum extraction processes face problems such as complex processes, high energy consumption, low extraction rates, high costs, and difficulty in large-scale industrial application, which limit the resource utilization of coal gangue in the aluminum industry. Summary of the Invention

[0005] This application provides a method and system for producing alumina from aluminum-rich coal gangue, which can solve the problems of complex processes, high energy consumption, low extraction rate, high cost, and difficulty in large-scale industrial application of existing coal gangue aluminum extraction processes.

[0006] To achieve the above objectives, the technical solution of this invention is as follows:

[0007] In a first aspect, embodiments of the present invention provide a method for producing alumina using aluminum-rich coal gangue, comprising:

[0008] Aluminum-rich coal gangue raw material is crushed and screened to obtain aluminum-rich coal gangue powder.

[0009] The aluminum-rich coal gangue powder is pyrolyzed under the influence of hot air to obtain pyrolysis material;

[0010] The pyrolysis material is first separated to obtain a high-temperature oil-gas mixture and solid products, wherein the high-temperature oil-gas mixture includes high-temperature coal gas and high-temperature tar.

[0011] The solid product undergoes an activation reaction under the carrying gas to obtain calcined aluminum-rich coal gangue;

[0012] The calcined aluminum-rich coal gangue is subjected to secondary separation to obtain reaction tail gas and high-temperature active silicon-aluminum oxide.

[0013] The high-temperature active silicon-aluminum oxide is cooled by heat exchange to obtain a cooled active silicon-aluminum oxide.

[0014] The cooled active silicon-aluminum oxide is subjected to pre-desiliconization treatment to obtain the treated product;

[0015] The treated product is subjected to aluminum extraction to obtain alumina.

[0016] In conjunction with the first aspect, in one possible implementation, the pyrolysis feed is first separated to obtain a high-temperature oil-gas mixture and solid products. The high-temperature oil-gas mixture, after comprising high-temperature coal gas and high-temperature tar, further includes:

[0017] The hot air and the low-temperature oil-gas mixture are obtained by exchanging heat with the cold air through the high-temperature oil-gas mixture.

[0018] The low-temperature oil-gas mixture is separated three times to obtain room-temperature tar and room-temperature coal gas.

[0019] In conjunction with the first aspect, in one possible implementation, the aluminum-rich coal gangue powder is pyrolyzed under the influence of hot air to obtain pyrolysis material, further comprising:

[0020] The heat source is supplemented by pyrolysis using the ambient temperature coal gas.

[0021] In conjunction with the first aspect, in one possible implementation, the solid product undergoes an activation reaction under the carrying capacity of a carrier gas to obtain calcined aluminum-rich coal gangue, further comprising:

[0022] The activation reaction is supplemented with heat source through the ambient temperature coal gas.

[0023] In conjunction with the first aspect, in one possible implementation, after separating the low-temperature oil-gas mixture three times to obtain room-temperature tar and room-temperature coal gas, the method further includes:

[0024] The ambient temperature gas is used for waste heat power generation.

[0025] In conjunction with the first aspect, in one possible implementation, after the calcined alumina-rich coal gangue undergoes secondary separation to obtain reaction tail gas and high-temperature active silica-alumina oxide, the process includes:

[0026] The reaction tail gas is dedusted to obtain high-temperature flue gas;

[0027] The high-temperature flue gas is used for waste heat power generation.

[0028] In conjunction with the first aspect, in one possible implementation, the high-temperature active silicon-aluminum oxide is subjected to heat exchange cooling to obtain a cooled active silicon-aluminum oxide, comprising:

[0029] The high-temperature active silicon-aluminum oxide is cooled by heat exchange with cold air to obtain cooled active silicon-aluminum oxide and a second hot air.

[0030] The second hot air is used to activate the reaction, and / or the second hot air is used to preheat the aluminum-rich coal gangue powder.

[0031] In conjunction with the first aspect, in one possible implementation, the oxygen concentration of the pyrolysis is less than 5%, and the temperature is 300°C to 800°C.

[0032] In conjunction with the first aspect, in one possible implementation, the aluminum content of the aluminum-rich coal gangue raw material is greater than or equal to 40%, and the particle size range of the aluminum-rich coal gangue powder is 0 mm to 3 mm.

[0033] Secondly, another embodiment of the present invention provides a system for producing alumina from aluminum-rich coal gangue, including a pretreatment mechanism, a pyrolysis mechanism, a first separation mechanism, a thermal activation mechanism, a second separation mechanism, a heat exchange mechanism, a desilication mechanism, and an aluminum extraction mechanism;

[0034] The pretreatment unit is used to crush and screen the aluminum-rich coal gangue raw material to obtain aluminum-rich coal gangue powder.

[0035] The pyrolysis mechanism is connected to the pretreatment mechanism. The aluminum-rich coal gangue powder output by the pretreatment mechanism is carried by hot air and input into the pyrolysis mechanism for pyrolysis to obtain pyrolysis material.

[0036] The first separation mechanism is connected to the pyrolysis mechanism. The pyrolysis material output by the pyrolysis mechanism is input into the first separation mechanism for initial separation to obtain a high-temperature oil-gas mixture and solid products. The oil-gas mixture includes high-temperature coal gas and high-temperature tar.

[0037] The thermal activation mechanism is connected to the first separation mechanism. The solid product output from the first separation mechanism is carried by a carrying gas and input into the thermal activation mechanism to undergo an activation reaction to obtain calcined aluminum-rich coal gangue.

[0038] The second separation mechanism is connected to the thermal activation mechanism. The calcined aluminum-rich coal gangue output by the thermal activation mechanism is input into the second separation mechanism for secondary separation to obtain reaction tail gas and high-temperature active silicon-aluminum oxide.

[0039] The heat exchange mechanism is connected to the second separation mechanism, and the high-temperature active silicon-aluminum oxide output from the second separation mechanism is input to the heat exchange mechanism for heat exchange and cooling to obtain cooled active silicon-aluminum oxide.

[0040] The desiliconization mechanism is connected to the heat exchange mechanism, and the cooled active silicon-aluminum oxide output from the heat exchange mechanism is input to the desiliconization mechanism for pre-desiliconization treatment to obtain the treated product.

[0041] The aluminum extraction mechanism is connected to the desilication mechanism, and the processed product output by the desilication mechanism is input into the aluminum extraction mechanism to extract aluminum and obtain alumina.

[0042] One or more technical solutions provided in the embodiments of the present invention have at least the following technical effects or advantages:

[0043] The method for producing alumina from aluminum-rich coal gangue provided in this invention employs an integrated pyrolysis-thermal activation-aluminum extraction process. During pyrolysis and thermal activation, the aluminosilicate structure in the aluminum-rich coal gangue powder undergoes preliminary decomposition, providing favorable conditions for subsequent desilication and aluminum extraction. Furthermore, it allows for the recovery and utilization of generated energy products such as coal gas and tar. This effectively extracts aluminum from the aluminum-rich coal gangue, achieving efficient resource utilization and high-value utilization of coal gangue resources, increasing resource added value, providing a new raw material source for the aluminum industry, and alleviating the shortage of bauxite resources. In addition, the method of this application is simple, energy-efficient, and rationally utilizes energy, achieving a high extraction rate and reducing costs, making it suitable for large-scale industrial application. Attached Figure Description

[0044] To more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments of the present invention will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0045] Figure 1 A schematic diagram of a system for producing alumina from aluminum-rich coal gangue provided in this application embodiment. Figure 1 ;

[0046] Figure 2 A schematic diagram of a system for producing alumina from aluminum-rich coal gangue provided in this application embodiment. Figure 2 .

[0047] Icons: 1-Pyrolysis mechanism; 2-First separation mechanism; 3-First heat exchange mechanism; 4-Oil washing mechanism; 5-Thermal activation mechanism; 6-Second separation mechanism; 7-Dust removal mechanism; 8-Second heat exchange mechanism; 9-Pretreatment mechanism; 10-Desiliconization mechanism; 11-Aluminum extraction mechanism; 12-Power generation mechanism. Detailed Implementation

[0048] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0049] In the description of the embodiments of the present invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the embodiments of the present invention and for 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. Therefore, they should not be construed as limitations on the present invention. The terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of the present invention according to the specific circumstances.

[0050] This invention provides a method for producing alumina using aluminum-rich coal gangue, comprising steps 1 to 8, where the numbers following the steps do not indicate the order of execution.

[0051] Step 1: Crush and screen the aluminum-rich coal gangue raw material to obtain aluminum-rich coal gangue powder.

[0052] Optionally, the aluminum content of the aluminum-rich coal gangue raw material is greater than or equal to 40%, and the particle size range of the aluminum-rich coal gangue powder is 0mm to 3mm, to ensure that the subsequent pyrolysis reaction can proceed fully and the pyrolysis effect is good.

[0053] Step 2: Pyrolyze the aluminum-rich coal gangue powder under the influence of hot air to obtain pyrolysis material.

[0054] Optionally, the oxygen concentration during pyrolysis is less than 5%, and the temperature is 300℃ to 800℃ (typical but not limiting temperatures such as 300℃, 350℃, 400℃, 450℃, 500℃, 550℃, 600℃, 650℃, 700℃, 750℃, and 800℃) to achieve better pyrolysis results.

[0055] During the pyrolysis reaction, the aluminum-rich coal gangue powder undergoes complex physicochemical changes, producing coal gas, tar, and solid products. Among these, the gaseous products such as coal gas, the solid products, and the liquid products such as tar are separated together in subsequent steps.

[0056] Step 3: The pyrolysis material (at a temperature of 300℃~600℃) is first separated to obtain a high-temperature oil-gas mixture and solid products. The high-temperature oil-gas mixture includes high-temperature coal gas and high-temperature tar.

[0057] Step 4: The solid product undergoes an activation reaction under the carrying gas to obtain calcined aluminum-rich coal gangue.

[0058] like Figure 1 and Figure 2 As shown, the carrying gas can be hot air obtained by heat exchange in the first heat exchange mechanism 3, or it can be room temperature coal gas output by the oil washing mechanism 4.

[0059] Step 5: The calcined aluminum-rich coal gangue is subjected to secondary separation to obtain reaction tail gas and high-temperature active silicon-aluminum oxide.

[0060] Step 6: Cool the high-temperature active silicon-aluminum oxide by heat exchange to obtain cooled active silicon-aluminum oxide.

[0061] Step 7: The cooled active silicon aluminum oxide is pre-desiliconized to obtain the processed product, thereby selectively removing some silicon elements to improve the efficiency and product quality of subsequent aluminum extraction.

[0062] Step 8: Extract aluminum from the treated product to obtain alumina. Specifically, the treated product is subjected to a series of processes including leaching, separation, crystallization, and calcination using the Bayer process to extract aluminum and obtain alumina.

[0063] After pre-desiliconization treatment, the processed product is finally obtained by Bayer process to obtain high-quality alumina products. The product quality meets the relevant national standards and industry specifications and can be widely used in many fields such as electrolytic aluminum production, ceramics, and refractory materials.

[0064] The method for producing alumina from aluminum-rich coal gangue provided in this invention employs an integrated pyrolysis-thermal activation-aluminum extraction process. During pyrolysis and thermal activation, the aluminosilicate structure in the aluminum-rich coal gangue powder undergoes preliminary decomposition, providing favorable conditions for subsequent desilication and aluminum extraction. Furthermore, it allows for the recovery and utilization of generated energy products such as coal gas and tar. This effectively extracts aluminum from the aluminum-rich coal gangue, achieving efficient resource utilization and high-value utilization of coal gangue resources, increasing resource added value, providing a new raw material source for the aluminum industry, and alleviating the shortage of bauxite resources. In addition, the method of this application is simple, energy-efficient, and rationally utilizes energy, achieving a high extraction rate and reducing costs, making it suitable for large-scale industrial application.

[0065] Further, step 3: the pyrolysis feed is first separated to obtain a high-temperature oil-gas mixture and solid products. The high-temperature oil-gas mixture includes high-temperature coal gas and high-temperature tar, and also includes:

[0066] Step A: A hot air and a low-temperature oil-gas mixture are obtained by exchanging heat with cold air through a high-temperature oil-gas mixture. This achieves both cooling of the high-temperature oil-gas mixture and warming of the cold air using the heat energy of the high-temperature oil-gas mixture, thus making efficient use of thermal energy. This heat exchange is indirect, such as in a shell-and-tube heat exchanger. Figure 1 and Figure 2 As shown, the hot air carries aluminum-rich coal gangue powder for pyrolysis, or, as... Figure 1 As shown, hot air carries solid products to carry out an activation reaction, thereby realizing the recovery and utilization of energy.

[0067] Step B: The low-temperature oil-gas mixture is separated three times to obtain room-temperature tar and room-temperature coal gas.

[0068] Furthermore, step B, after separating the low-temperature oil-gas mixture three times to obtain room-temperature tar and room-temperature coal gas, also includes using the room-temperature coal gas for waste heat power generation. This not only saves energy and makes rational use of resources, but also ensures that the coal gas does not pollute the environment.

[0069] Optionally, step 2: pyrolyze the aluminum-rich coal gangue powder under the influence of hot air to obtain pyrolysis material, and also includes: supplementing the heat source of pyrolysis with ambient temperature coal gas, thereby making reasonable use of coal gas.

[0070] Optionally, step 4, in which the solid product undergoes an activation reaction under the carrying gas to obtain calcined aluminum-rich coal gangue, also includes supplementing the heat source for the activation reaction with ambient temperature coal gas, thereby making rational use of the coal gas.

[0071] Further, step 5: after secondary separation of the calcined alumina-rich coal gangue to obtain reaction tail gas and high-temperature active silicon-aluminum oxide, includes:

[0072] Step M: The reaction tail gas is dedusted to obtain high-temperature flue gas. The reaction tail gas contains a small amount of dust and unreacted gaseous components. Deded dust from the reaction tail gas yields high-temperature flue gas.

[0073] Step N: Use the high-temperature flue gas for waste heat power generation, thereby making reasonable use of the heat in the high-temperature flue gas.

[0074] Optionally, step 6: Cooling the high-temperature active silicon-aluminum oxide through heat exchange to obtain cooled active silicon-aluminum oxide, including:

[0075] Step X: The high-temperature active silicon-aluminum oxide is cooled by heat exchange with cold air to obtain cooled active silicon-aluminum oxide and a second batch of hot air. The heat from the high-temperature active silicon-aluminum oxide is recovered through heat exchange with cold air.

[0076] Step Y: Use the second hot air to activate the reaction, and / or use the second hot air to preheat the aluminum-rich coal gangue powder, thereby rationally recovering and utilizing heat.

[0077] The method for producing alumina from aluminum-rich coal gangue provided in this invention fully recovers and utilizes the heat from the high-temperature oil-gas mixture and high-temperature active silica-alumina oxides throughout the production process. The recycling of hot air provides some heat for pyrolysis and thermodynamic activation reactions, reducing the input of external energy. Simultaneously, excess coal gas is used for waste heat power generation, and the heat recovered by the multi-stage cooling system is also rationally utilized, further improving energy efficiency and significantly reducing the energy consumption of the entire production process.

[0078] The coal gas and reaction tail gas generated by pyrolysis were properly treated. The coal gas was used for waste heat power generation, reducing waste gas emissions. After dust removal treatment, the content of dust and other pollutants in the reaction tail gas met environmental protection standards. The high-temperature flue gas was used for waste heat power generation, realizing the harmless and resource utilization of the tail gas and achieving environmental friendliness.

[0079] This invention provides an innovative method for producing alumina from aluminum-rich coal gangue. Through a series of process steps, including pyrolysis, thermal activation, and aluminum extraction of aluminum-rich coal gangue powder, the method achieves efficient extraction of aluminum, increases the added value of resources, and solves the environmental pollution problem caused by coal gangue. This method not only helps alleviate the pressure of bauxite resource shortage and promotes the sustainable development of the aluminum industry, but also opens up new avenues for the resource utilization of aluminum-rich coal gangue, achieving a win-win situation for both the economy and the environment.

[0080] Another embodiment of the present invention provides a system for producing alumina from aluminum-rich coal gangue, including a pretreatment unit 9, a pyrolysis unit 1, a first separation unit 2, a thermal activation unit 5, a second separation unit 6, a second heat exchange unit 8, a desiliconization unit 10, and an aluminum extraction unit 11.

[0081] The pretreatment unit 9 is used to crush and screen the aluminum-rich coal gangue raw material to obtain aluminum-rich coal gangue powder.

[0082] The pyrolysis unit 1 is connected to the pretreatment unit 9. The aluminum-rich coal gangue powder output from the pretreatment unit 9 is fed into the pyrolysis unit 1 at a stable and controllable feed rate under the influence of hot air for pyrolysis to obtain pyrolysis material. The pyrolysis unit 1 can be a pyrolysis furnace, equipped with heating elements and a precise temperature control system. Under strictly controlled atmospheric conditions with an oxygen content below 5%, the pyrolysis temperature is precisely regulated within the range of 300℃ to 800℃. During the pyrolysis process, high-precision temperature sensors, pressure sensors, and other monitoring equipment are installed inside the pyrolysis furnace to monitor and provide feedback on various key parameters in real time, ensuring the reaction remains at its optimal state. The coal gas produced by pyrolysis is discharged through a dedicated pipeline and enters the subsequent first separation unit 2.

[0083] The first separation unit 2 is connected to the pyrolysis unit 1. The pyrolysis material output from the pyrolysis unit 1 is rapidly fed into the first separation unit 2 through a high-temperature resistant and well-insulated pipeline for the first separation to obtain a high-temperature oil-gas mixture and solid products. The oil-gas mixture includes high-temperature coal gas and high-temperature tar.

[0084] The tar is efficiently collected using a specially designed tar collection device (such as a tar tank) for subsequent professional oil washing treatment. The generated coke powder is discharged through a specialized discharge device (such as a star-shaped discharger) and stored as a high-quality heat source for the thermal activation mechanism 5.

[0085] The thermal activation mechanism 5 is connected to the first separation mechanism 2. The solid product output from the first separation mechanism 2 is carried by the carrying gas and fed into the thermal activation mechanism 5 at a stable conveying rate to carry out the activation reaction and obtain calcined aluminum-rich coal gangue.

[0086] like Figure 1 and Figure 2 As shown, the carrier gas can be hot air output from the first heat exchange mechanism 3, or ambient temperature coal gas output from the oil washing mechanism 4. The thermal activation mechanism 5 can be a rotary kiln, a conveying bed, or a fluidized bed, selected according to actual needs. The activation reaction temperature range is 700℃~1200℃. During the activation reaction, the minerals in the solid product undergo further decomposition and oxidation reactions to obtain calcined aluminum-rich coal gangue.

[0087] During the activation process, the thermal activation mechanism 5 is equipped with advanced temperature monitoring, gas flow rate monitoring, and material fluidization state monitoring equipment to monitor the reaction process in real time, ensuring that the material can be uniformly heated and fully reacted in the thermal activation mechanism 5, thereby achieving efficient decomposition and oxidative transformation of minerals.

[0088] The second separation unit 6 is connected to the thermal activation unit 5. The calcined aluminum-rich coal gangue output from the thermal activation unit 5 is input to the second separation unit 6 for secondary separation to obtain reaction tail gas and high-temperature active silicon-aluminum oxide.

[0089] The second heat exchange mechanism 8 is connected to the second separation mechanism 6. The high-temperature active silicon-aluminum oxide output from the second separation mechanism 6 is input to the second heat exchange mechanism 8 for heat exchange and cooling to obtain cooled active silicon-aluminum oxide.

[0090] The second heat exchange unit 8 uses cold air to cool the high-temperature active silicon-aluminum oxide, resulting in cooled active silicon-aluminum oxide and a second hot air. The second hot air is used for activation reactions, and / or for preheating aluminum-rich coal gangue powder, achieving comprehensive energy utilization.

[0091] The second heat exchange mechanism 8 is one or more combinations of a cyclone cooler and a rotary cooler, and the final temperature of the cooled active silicon aluminum oxide is 25℃~300℃.

[0092] The desiliconization mechanism 10 is connected to the second heat exchange mechanism 8. The cooled active silicon-aluminum oxide output from the second heat exchange mechanism 8 is input to the desiliconization mechanism 10 for pre-desiliconization treatment to obtain the processed product.

[0093] The aluminum extraction mechanism 11 is connected to the desiliconization mechanism 10. The processed product output from the desiliconization mechanism 10 is input into the aluminum extraction mechanism 11 to extract aluminum and obtain alumina.

[0094] The system for producing alumina from aluminum-rich coal gangue provided in this application embodiment further includes a heat exchange mechanism and an oil washing mechanism 4. The heat exchange mechanism is connected to the first separation mechanism 2. The high-temperature oil-gas mixture output from the first separation mechanism 2 is rapidly output to the first heat exchange mechanism 3 through a high-temperature resistant and well-insulated pipe to exchange heat with the cold air to obtain a hot air and a low-temperature oil-gas mixture.

[0095] The oil washing unit 4 is connected to the first heat exchange unit 3. The low-temperature oil-gas mixture output from the first heat exchange unit 3 is rapidly fed into the oil washing unit 4 through a high-temperature resistant and well-insulated pipeline for three-stage separation to obtain room-temperature tar and room-temperature coal gas. After being processed by the oil washing unit 4, the low-temperature oil-gas mixture can recover organic chemical raw materials such as benzene and naphthalene. The room-temperature tar is transported to the oil washing unit 4 at a stable flow rate through a dedicated pipeline for further processing to recover its high-value organic components.

[0096] The system for producing alumina from aluminum-rich coal gangue provided in this application embodiment further includes: a power generation unit 12. The power generation unit 12 is connected to the oil washing unit 4. The ambient temperature coal gas output from the oil washing unit 4 is input to the power generation unit 12 for waste heat power generation, thereby making full use of thermal energy.

[0097] Optional, such as Figure 1 and Figure 2 As shown, the oil washing mechanism 4 is connected to the pyrolysis mechanism 1. The ambient temperature gas output from the oil washing mechanism 4 is input to the pyrolysis mechanism 1 to supplement the heat source for pyrolysis.

[0098] Optional, such as Figure 1 As shown, the oil washing mechanism 4 is connected to the thermal activation mechanism 5. The ambient temperature gas output from the oil washing mechanism 4 is input to the thermal activation mechanism 5 to supplement the heat source for the activation reaction.

[0099] Furthermore, the system for producing alumina from aluminum-rich coal gangue provided in this application embodiment also includes: a dust removal mechanism 7.

[0100] The dust removal mechanism 7 is connected to the second separation mechanism 6. The reaction tail gas (temperature 700℃~1000℃) output from the second separation mechanism 6 is rapidly input into the dust removal mechanism 7 through a high-temperature resistant pipe for dust removal to obtain high-temperature flue gas.

[0101] The power generation unit 12 is connected to the dust removal unit 7. The high-temperature flue gas output from the dust removal unit 7 is input to the power generation unit 12 for waste heat power generation.

[0102] The dust removal mechanism 7 is one or more combinations of a high-efficiency cyclone dust collector and an interceptor dust collector.

[0103] The system for producing alumina from aluminum-rich coal gangue provided in this invention can realize an integrated process of pyrolysis-thermal activation-aluminum extraction. During pyrolysis and thermal activation, the aluminosilicate structure in the aluminum-rich coal gangue powder undergoes preliminary decomposition, which not only provides favorable conditions for subsequent desilication and aluminum extraction but also allows for the recovery and utilization of energy products such as coal gas and tar. This effectively extracts aluminum from the aluminum-rich coal gangue, achieving efficient resource utilization and high-value utilization of coal gangue resources, increasing resource added value, providing a new raw material source for the aluminum industry, and alleviating the shortage of bauxite resources. Furthermore, the method of this application is simple, energy-efficient, and rationally utilizes energy, achieving a high extraction rate and reducing costs, making it suitable for large-scale industrial application.

[0104] Throughout the production process, the heat from the high-temperature oil-gas mixture and high-temperature active silicon-aluminum oxides is fully recovered and utilized. The recirculation of hot air provides some heat for pyrolysis and thermal activation reactions, reducing the input of external energy. Simultaneously, excess gas is used for waste heat power generation, and the heat recovered by the multi-stage cooling system is also rationally utilized, further improving energy efficiency and significantly reducing energy consumption throughout the entire production process.

[0105] The various embodiments in this specification are described in a progressive manner. For the same or similar parts between the various embodiments, please refer to each other. Each embodiment focuses on describing the differences from other embodiments.

[0106] The above embodiments are only used to illustrate the technical solutions of this application, and are not intended to limit this application. Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of this application.

Claims

1. A method for producing alumina using aluminum-rich coal gangue, characterized in that, include: Aluminum-rich coal gangue raw material is crushed and screened to obtain aluminum-rich coal gangue powder. The aluminum-rich coal gangue powder is pyrolyzed under the influence of hot air to obtain pyrolysis material, and room temperature coal gas is used to supplement the heat source for pyrolysis. The pyrolysis material is first separated to obtain a high-temperature oil-gas mixture and solid products, wherein the high-temperature oil-gas mixture includes high-temperature coal gas and high-temperature tar. The hot air and the low-temperature oil-gas mixture are obtained by exchanging heat with cold air through the high-temperature oil-gas mixture; the low-temperature oil-gas mixture is then separated three times to obtain room-temperature tar and room-temperature coal gas. The solid product undergoes an activation reaction under the carrying gas to obtain calcined aluminum-rich coal gangue; The calcined aluminum-rich coal gangue is subjected to secondary separation to obtain reaction tail gas and high-temperature active silicon-aluminum oxide. The high-temperature active silicon-aluminum oxide is cooled by heat exchange in a second heat exchange mechanism using cold air to obtain cooled active silicon-aluminum oxide at a temperature of 25℃ to 300℃ and second hot air; the second heat exchange mechanism is one or more combinations of a cyclone cooler and a rotary cooler. The second hot air is used to activate the reaction, and / or the second hot air is used to preheat the aluminum-rich coal gangue powder; The cooled active silicon-aluminum oxide is subjected to pre-desiliconization treatment to obtain the treated product; The treated product is subjected to aluminum extraction to obtain alumina.

2. The method for producing alumina from aluminum-rich coal gangue according to claim 1, characterized in that, The solid product undergoes an activation reaction under the carrying gas to obtain calcined aluminum-rich coal gangue, which further includes: The activation reaction is supplemented with heat source through the ambient temperature coal gas.

3. The method for producing alumina from aluminum-rich coal gangue according to claim 1 or 2, characterized in that, After separating the low-temperature oil-gas mixture three times to obtain room-temperature tar and room-temperature coal gas, the process further includes: The ambient temperature gas is used for waste heat power generation.

4. The method for producing alumina from aluminum-rich coal gangue according to claim 1, characterized in that, After secondary separation of the calcined alumina-rich coal gangue to obtain reaction tail gas and high-temperature active silicon-aluminum oxide, the process includes: The reaction tail gas is dedusted to obtain high-temperature flue gas; The high-temperature flue gas is used for waste heat power generation.

5. The method for producing alumina from aluminum-rich coal gangue according to claim 1, characterized in that, The oxygen concentration during pyrolysis is less than 5%, and the temperature is 300℃~800℃.

6. The method for producing alumina from aluminum-rich coal gangue according to claim 1, characterized in that, The aluminum content of the aluminum-rich coal gangue raw material is greater than or equal to 40%, and the particle size range of the aluminum-rich coal gangue powder is 0 mm to 3 mm.

7. A system for producing alumina from aluminum-rich coal gangue, characterized in that, It includes a pretreatment mechanism, a pyrolysis mechanism, a first separation mechanism, a thermal activation mechanism, a second separation mechanism, a heat exchange mechanism, a desilication mechanism, and an aluminum extraction mechanism; The pretreatment unit is used to crush and screen the aluminum-rich coal gangue raw material to obtain aluminum-rich coal gangue powder. The pyrolysis mechanism is connected to the pretreatment mechanism. The aluminum-rich coal gangue powder output by the pretreatment mechanism is carried by hot air and input into the pyrolysis mechanism for pyrolysis to obtain pyrolysis material. The first separation mechanism is connected to the pyrolysis mechanism. The pyrolysis material output by the pyrolysis mechanism is input into the first separation mechanism for initial separation to obtain a high-temperature oil-gas mixture and solid products. The oil-gas mixture includes high-temperature coal gas and high-temperature tar. The thermal activation mechanism is connected to the first separation mechanism. The solid product output from the first separation mechanism is carried by a carrying gas and input into the thermal activation mechanism to undergo an activation reaction to obtain calcined aluminum-rich coal gangue. The second separation mechanism is connected to the thermal activation mechanism. The calcined aluminum-rich coal gangue output by the thermal activation mechanism is input into the second separation mechanism for secondary separation to obtain reaction tail gas and high-temperature active silicon-aluminum oxide. The heat exchange mechanism is connected to the second separation mechanism, and the high-temperature active silicon-aluminum oxide output from the second separation mechanism is input to the heat exchange mechanism for heat exchange and cooling to obtain cooled active silicon-aluminum oxide. The desiliconization mechanism is connected to the heat exchange mechanism, and the cooled active silicon-aluminum oxide output from the heat exchange mechanism is input to the desiliconization mechanism for pre-desiliconization treatment to obtain the treated product. The aluminum extraction mechanism is connected to the desilication mechanism, and the processed product output by the desilication mechanism is input into the aluminum extraction mechanism to extract aluminum and obtain alumina.

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