A process and system for decarburization and modification of coal gangue by cyclone calcination

Abstract

This invention discloses a process and system for decarbonization and modification of coal gangue by cyclone calcination, belonging to the field of comprehensive utilization technology of coal gangue. The system includes a quantitative feeding unit, a drying unit, a dried material recovery unit, a preheating unit, a hot air furnace, a cyclone calcination unit, a high-temperature calcined material recovery unit, an insulated silo, and a cooling unit. The process steps are as follows: the system's negative pressure equipment is started, the hot air furnace provides heat, quantitative feeding is followed by flash drying, the dried material is recovered, waste heat flue gas is used to preheat the material and remove surface organic carbon, and then the material is sent to the cyclone calcination unit to control the calcination temperature and time, thereby oxidizing and decarbonizing, decomposing and modifying the material, and controlling the aluminum-silicon ratio. Subsequently, the high-temperature material is recovered and sent to the insulated silo to regulate the crystal transformation and improve SiO2 activity. This invention adopts a gas-solid direct contact cyclone calcination process, which has low energy consumption, uniform material heating, no agglomeration, stable product quality, and a short process flow, high efficiency, and strong raw material adaptability.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of comprehensive utilization technology of coal gangue or kaolin, specifically to a process and system for decarbonization modification of coal gangue by cyclone calcination. Background Technology

[0002] Coal-series kaolin, also known as coal gangue, is a solid waste discharged during coal mining and washing processes. Due to its low utilization rate, coal gangue accumulates in large quantities, occupying a significant amount of land resources.

[0003] Decarbonization of coal gangue mainly involves wet decarbonization and calcination decarbonization. Wet decarbonization requires crushing / grinding, grading, sorting, gravity separation, and chemical bleaching, which is a complex process with incomplete decarbonization, poor decarbonization effect, substandard product quality, and high energy consumption. Calcination decarbonization mainly uses block and granular coal gangue. In traditional vertical kiln and rotary kiln processes that primarily use block and granular coal gangue for calcination, the main heat exchange method is surface heat exchange of the coal gangue in its stacked state, which has very low heat transfer efficiency and generally requires supplementary combustion. Vertical kilns that primarily use block or pellet calcination cannot meet environmental protection and energy consumption requirements due to their small capacity. At the same time, small and medium-sized circulating fluidized bed power generation processes that primarily use granular coal gangue cannot meet current industrial requirements due to high power consumption and small scale.

[0004] In existing coal gangue calcination and activation modification technologies, coal gangue materials can be divided into two main categories based on their dispersion state in the hot air stream: traditional packed-state activation calcination and suspended-state activation calcination. Currently, the commercially available suspended-state calcination technology for coal gangue involves preheating followed by calcination with hot air in a decomposition furnace. Because coal gangue requires very high calorific value and stability, suspended-state calcination generally only utilizes low-calorific-value (<600 kcal / kg) coal gangue. If high-calorific-value coal gangue is used, deflagration can occur in the preheater due to volatile organic compounds and organic carbon, leading to preheater scaling, blockage, and even burn-through. If organic carbon in the coal gangue deflagration occurs in the calcination furnace, it can cause excessively high local temperatures in the furnace. Because existing suspension calcination systems can only calcine low-calorific-value coal gangue with a calorific value of 0–600 kcal / kg, they have poor adaptability to coal gangue and are difficult to control process parameters.

[0005] When coal gangue is calcined at 200–1500℃, the product undergoes a series of transformations as the temperature increases: "removal of moisture / volatile matter → combustion of organic matter → decomposition of mineral phases → synthesis of new phases → melting and sintering". Its properties gradually change from loose and porous to dense and stable. Specifically: at 200–300℃, dehydration / mild volatile matter removal occurs, with the main product being dehydrated coal gangue; at 300–400℃, volatile matter removal occurs, resulting in semi-coke coal gangue; at 400–500℃, initial combustion of organic matter occurs, producing carbonized coal gangue; at 500–600℃, complete combustion of organic matter occurs, producing carbon-free coal gangue; at 600–700℃, initial decomposition of clay minerals occurs, producing metakaolinized coal gangue; at 700–800℃, complete decomposition of kaolinite occurs, producing an amorphous aluminosilicate mixture; and at 800–900℃, initial crystallization occurs. The composition is mullite precursor; at 900–1000℃, mullite is formed in the early stage, and the product is calcined coal gangue with low mullite content; at 1000–1100℃, mullite is formed in large quantities, and the product is coal gangue with high mullite content; at 1100–1200℃, cristobalite is stabilized, and the product is a mullite-cristobalite multiphase material; at 1200–1300℃, sintering and densification occur, and the product is a densified mullite-based material; at 1300–1400℃, partial melting occurs, and the product is a semi-molten coal gangue sintered body; at 1400–1500℃, complete melting / vitrification occurs, and the product is a coal gangue melt / vitrified body.

[0006] The rotary kiln calcination process for coal gangue presents the following problems: high energy consumption; large temperature gradient within the kiln, significant differences in material residence time, and uneven heating of the material, easily leading to calcination defects such as under-burning, over-burning, under-burning, agglomeration, and poor modification; unstable particle size / whiteness / dispersion and decreased coloring power; long process flow, numerous steps, large footprint, low degree of continuity, long production cycle, and low efficiency; limited particle size or specific gravity of the material, low density of ultrafine powder, and poor flowability. Under the slow rotation of the kiln body, the material is stirred by its own gravity, resulting in uneven heating and easily leading to under-burning, over-burning, under-burning, and agglomeration. At the same time, the recovery of high-temperature ultrafine powder is difficult and the process is complex.

[0007] In granular decarburization technology, the main process involves crushing coal gangue to a certain particle size and then calcining it in a roasting machine for decarburization. Because the material is granular, a high calcination temperature is required to achieve decarburization. However, excessively high calcination temperatures lead to sintering of the material, resulting in incomplete decarburization of the granules within the sintered blocks, leading to high carbon content and the potential for black core material, thus reducing cement quality. Simultaneously, the loss on ignition is also relatively high during calcination at these excessively high temperatures, reducing utilization rate. Summary of the Invention

[0008] To address these issues, this invention provides a cyclone calcination decarbonization modification process and system for coal gangue to solve problems such as "high energy consumption, uneven heating, easy agglomeration, and difficulty in quality control when calcining coal gangue in rotary kilns," "prone to under-burning, over-burning, under-burning, agglomeration, and poor modification," "long process, numerous steps, large footprint, low degree of continuity, long production cycle, and low efficiency," "limited particle size or specific gravity of materials, low density and poor flowability of ultrafine powders, with materials relying on gravity for stirring under the slow rotation of the kiln body, resulting in uneven heating," and "difficulty in recovering high-temperature ultrafine powders and complex processes." This process and system can also be used for the calcination modification of kaolin.

[0009] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0010] The first aspect of the present invention provides a coal gangue cyclone calcination decarbonization modification system, comprising a quantitative feeding unit, a drying unit, a dried material recovery unit, a preheating unit, a hot air furnace, a cyclone calcination unit, a high-temperature calcination material recovery unit, and an insulated silo;

[0011] The outlet of the quantitative feeding unit is connected to the inlet of the drying unit, and is used to: feed powdered materials into the drying unit;

[0012] The air inlet of the drying unit is connected to the air outlet of the preheating unit, and the air outlet is connected to the air inlet of the dried material recovery unit. It is used to receive the material output from the quantitative feeding unit and the hot air discharged from the preheating unit, and the material and hot air are directly mixed for flash drying.

[0013] The air outlet of the dry material recovery unit is connected to a negative pressure device, and the discharge outlet is connected to a dry material conveying pipeline, which is used to: draw the gas-powder mixture discharged by the drying unit under negative pressure and collect the dry material in the gas-powder mixture.

[0014] The feed inlet of the preheating unit is connected to the hot air outlet of the high-temperature calcined material recovery unit through a waste heat flue gas reuse pipeline, and the middle section of the waste heat flue gas reuse pipeline is connected to the dry material conveying pipeline. This pipeline is used to: receive the hot air discharged from the high-temperature calcined material recovery unit, and pneumatically introduce the dry material discharged from the recovery unit under the action of the hot air, so that the material is directly heated by the hot air and the free organic carbon on the surface of the material is removed.

[0015] The air outlet of the hot air furnace is connected to the flue gas inlet of the swirl calcination unit to provide high-temperature flue gas;

[0016] The feed inlet of the cyclone calcination unit is connected to the discharge outlet of the preheating unit, and is used to: receive the dried preheated material discharged from the preheating unit and the hot air generated by the hot air furnace, mix the received dried preheated material with the hot air, and make the dried preheated material flow forward with the hot air, control the calcination temperature and time, oxidize and decarbonize the dried preheated material, decompose and modify it, effectively remove the remaining free carbon, impurities carbon and encapsulated carbon, control the degree of kaolin decomposition, and control the aluminum-silicon ratio;

[0017] The air inlet of the high-temperature calcining material recovery unit is connected to the flue gas outlet of the cyclone calcining unit, and is used to: recover the material in the high-temperature flue gas discharged from the cyclone calcining unit;

[0018] The inlet of the insulated silo is connected to the outlet of the high-temperature calcined material recovery unit, and is used to: control the insulation temperature and time, adjust the SiO2 crystal form transformation during recrystallization, and improve the SiO2 activity index.

[0019] Furthermore, the coal gangue cyclone calcination decarbonization modification system also includes a cooling unit and a cooling silo;

[0020] The cooling unit's air outlet is connected to a negative pressure device, and its air inlet is connected to a calcined material conveying pipeline. One end of the calcined material conveying pipeline forms an open end for air to enter. The end of the calcined material conveying pipeline near the open end is connected to the discharge port of the insulated silo. This is used to: draw the high-temperature material discharged from the insulated silo under negative pressure, allowing the material to mix directly with the air and thus cool the material.

[0021] The inlet of the cooling silo is connected to the outlet of the cooling unit, and is used to store the cooled finished material.

[0022] Furthermore, the quantitative feeding unit includes a metering conveyor belt and a servo screw feeder; one end of the metering conveyor belt is connected to the raw material silo, and the other end is connected to the feed inlet of the servo screw feeder; the discharge outlet of the servo screw feeder is connected to the feed inlet of the drying unit.

[0023] Furthermore, the drying unit includes a flash dryer, the outlet of the servo screw feeder is connected to the inlet of the flash dryer, and the air inlet of the flash dryer is connected to the air outlet of the preheating unit.

[0024] The dried material recovery unit includes a drying cyclone separator and a drying bag filter. The air inlet of the drying cyclone separator is connected to the air outlet of the flash dryer, and the air outlet of the drying cyclone separator is connected to the air inlet of the drying bag filter. The air outlet of the drying bag filter is connected to a first induced draft fan, and the air outlet of the first induced draft fan is connected to a tail gas treatment device. The discharge ports of the drying cyclone separator and the drying bag filter are respectively connected to the dried material conveying pipeline. One or more drying cyclone separators are provided as needed.

[0025] Furthermore, the preheating unit includes a preheating cyclone separator. The inlet of the preheating cyclone separator is connected to the hot air outlet of the high-temperature calcined material recovery unit through a waste heat flue gas reuse pipeline. The outlet of the preheating cyclone separator is connected to the inlet of the cyclone calcination unit. The outlet of the preheating cyclone separator is connected to the inlet of the flash dryer. One or more preheating cyclone separators are provided as needed.

[0026] Furthermore, the cyclone calcination unit includes a cyclone calcination furnace and a decarbonizing agent supply device. The feed inlet of the cyclone calcination furnace is connected to the discharge outlet of the preheated cyclone separator, the flue gas inlet of the cyclone calcination furnace is connected to the air outlet of the hot air furnace, the flue gas outlet of the cyclone calcination furnace is connected to the air inlet of the high-temperature calcined material recovery unit, and the decarbonizing agent outlet of the decarbonizing agent supply device is connected to the decarbonizing agent addition port of the cyclone calcination furnace.

[0027] Furthermore, the high-temperature calcination material recovery unit includes a high-temperature cyclone separator and a diffusion heat exchange cyclone separator. The inlet of the high-temperature cyclone separator is connected to the flue gas outlet of the cyclone calciner, and the outlet of the high-temperature cyclone separator is connected to the inlet of the diffusion heat exchange cyclone separator. The outlet of the diffusion heat exchange cyclone separator is connected to the waste heat flue gas reuse pipeline. One or more of the high-temperature cyclone separator and / or diffusion heat exchange cyclone separator are provided as needed.

[0028] An insulation jacket is provided outside the insulation silo. A blower is connected to the bottom air inlet of the insulation jacket. A heat exchange jacket is provided outside the diffusion heat exchange cyclone separator. The bottom air inlet of the heat exchange jacket is connected to the top air outlet of the insulation jacket. The top air outlet of the heat exchange jacket is connected to the combustion air inlet of the burner of the hot air furnace.

[0029] Furthermore, the cooling unit includes a cooling cyclone separator and a cooling bag filter. The air inlet of the cooling cyclone separator is connected to the calcined material conveying pipeline, and the air outlet of the cooling cyclone separator is connected to the air inlet of the cooling bag filter. The air outlet of the cooling bag filter is connected to a second induced draft fan, and the air outlet of the second induced draft fan is connected to the waste heat utilization unit or the combustion air inlet of the burner. One or more cooling cyclone separators are provided as needed.

[0030] A second aspect of the present invention provides a process for decarbonizing and modifying coal gangue by cyclone calcination, which employs the coal gangue cyclone calcination and decarbonization modification system provided in this aspect of the present invention, and includes the following steps:

[0031] Start the first induced draft fan to create a negative pressure environment in the drying bag dust collector, drying cyclone separator, flash dryer, and preheating cyclone separator;

[0032] Start the hot air furnace and supply high-temperature flue gas to the cyclone calciner, preheating cyclone separator and flash dryer in sequence;

[0033] Start the metering conveyor belt and servo screw feeder to accurately and quantitatively feed materials to the flash dryer under the control of the intelligent control unit;

[0034] Powdered materials enter the flash dryer for flash drying, coming into direct contact with high-temperature flue gas, causing the materials to heat up rapidly, dehydrate, and dry.

[0035] The dried material flows to the dried material recovery unit, where it is recovered by the drying cyclone separator and the drying bag dust collector.

[0036] The recovered dried material flows to the preheating cyclone separator, where it comes into direct contact with the high-temperature flue gas. The dried material exchanges heat with the high-temperature flue gas, its temperature rises, and free organic carbon on the surface of the material is removed.

[0037] The dried and preheated material flows to the cyclone calciner, where it undergoes cyclone calcination. The material flows forward with the hot air, and the calcination temperature and time are controlled by the intelligent control unit to oxidize and decarbonize the material, decompose and modify it, control the degree of kaolin decomposition, and control the aluminum-silicon ratio. The decarbonizing agent supply device supplies oxygen to the cyclone calciner as needed under the control of the intelligent control unit, adjusts the oxygen environment, and effectively removes the remaining free carbon, impurities, and encapsulated carbon.

[0038] The high-temperature material after calcination flows to the high-temperature calcined material recovery unit, where it is effectively recovered by a high-temperature cyclone separator and a diffusion heat exchange cyclone separator. The recovered material is then sent to an insulated silo.

[0039] The modification temperature and time are set as needed. The recovered calcined material is modified in the heat-insulated silo. The heat-insulation temperature and time are controlled to adjust the SiO2 crystal form transformation during recrystallization and improve the SiO2 activity index.

[0040] The second induced draft fan is started, and the modified material in the insulated silo flows to the cooling unit through pneumatic conveying. The material is cooled and recovered by the cooling cyclone separator and the cooling bag filter. The cooled and recovered material enters the cooling silo.

[0041] Furthermore, the coal gangue cyclone calcination decarburization modification process also includes the following steps:

[0042] Start the blower to blow cooling air into the insulation jacket outside the insulation silo, adjust the temperature of the insulation silo, and cool the high-temperature calcined material inside the insulation silo to the temperature range required for modification. After the standard is met, the insulation silo is kept warm, and the temperature no longer decreases or can only decrease slowly.

[0043] The cooling air flowing in the insulation interlayer is initially heated;

[0044] The pre-heated cooling air enters the heat exchange jacket outside the diffusion heat exchange cyclone separator and exchanges heat with the high-temperature flue gas in the inner cylinder of the diffusion heat exchange cyclone separator, and the cooling air is further heated.

[0045] The cooled air, which is further heated, is supplied to the burner as combustion gas; at the same time, the air with residual heat discharged from the second induced draft fan is supplied to the burner as combustion gas.

[0046] The embodiments of the present invention have the following advantages:

[0047] 1. Significantly reduces energy consumption and has extremely high thermal economy.

[0048] This invention abandons the inefficient heat transfer mode of traditional rotary kilns that rely on kiln wall radiation and material accumulation surface heat exchange. By employing flash drying with direct gas-solid mixing, pneumatic preheating, and swirling calcination technology, the material remains in a highly dispersed fluidized state throughout the drying, preheating, and swirling calcination units, directly contacting the hot air, resulting in an order-of-magnitude improvement in heat and mass transfer efficiency. Simultaneously, the system utilizes a heat exchange jacket in the diffusion heat exchange cyclone separator, an insulation jacket in the insulated silo, and a tiered recovery design for the exhaust air from the cooling unit, reusing waste heat from each stage for preheating combustion air and drying materials. For medium- to high-calorific-value coal gangue, the system can significantly reduce or even completely stop fuel supply to the hot blast stove after startup, achieving self-sustaining combustion. This completely solves the problem of "high energy consumption in rotary kiln calcination of coal gangue" in the background technology, with overall thermal efficiency far exceeding that of traditional processes.

[0049] 2. Solves the problems of clumping and uneven heating, resulting in uniform and stable product quality.

[0050] In this invention, the material flows forward with the high-temperature flue gas in the swirl calcination unit. The particles are effectively entrained by the airflow and are in a separated, swirling state, eliminating the conditions for adhesion and sintering caused by gravity accumulation and tumbling found in rotary kilns. Even ultrafine powders will not agglomerate. Simultaneously, the strong turbulent diffusion effect of the swirl flow field ensures that each material particle can contact the hot air uniformly and quickly, resulting in a uniform calcination temperature field and precisely controllable material residence time (typically only 1-2 minutes). This fundamentally eliminates the calcination defects such as "under-burning, over-burning, under-burning, agglomeration, and poor modification" caused by large temperature gradients and significant differences in material residence time in traditional rotary kiln processes. Furthermore, the preheating unit utilizes waste heat flue gas to remove free organic carbon from the material surface in advance, effectively preventing deflagration of high-calorific-value materials in the swirl calcination unit and avoiding localized overheating. This further ensures the stability and uniformity of product particle size, whiteness, dispersibility, and activity indicators.

[0051] 3. Shortened process, high production efficiency, and strong adaptability to raw materials.

[0052] This invention highly integrates multiple processes, including quantitative feeding, flash drying, dried material recovery, waste heat preheating, cyclone calcination, high-temperature material recovery, heat preservation modification, and rapid cooling, into a single continuous production line. The material takes only 1-2 minutes from inlet to outlet, while traditional rotary kiln processes typically require several hours. This not only significantly shortens the production cycle and improves the degree of continuous operation, but also allows for a compact equipment layout through modular design, significantly reducing the footprint and overcoming the drawbacks of the prior art, such as "long process, numerous steps, large footprint, long production cycle, and low efficiency." More importantly, this invention employs pneumatic conveying and cyclone technology, which has no stringent requirements on material particle size and can handle 0-3mm and even ultrafine powders. This completely overcomes the limitation of rotary kilns in handling ultrafine powders due to their poor flowability. Furthermore, by controlling the calcination temperature and oxidizing atmosphere, it can be applied to both low-calorific-value (<600kcal / kg) and high-calorific-value coal gangue, demonstrating a far greater adaptability to raw materials than existing suspension calcination processes.

[0053] 4. Adjusting the calcination temperature window and holding period to achieve targeted modification of the product.

[0054] This invention enables precise control of the calcination temperature within any range of 500℃ to 1300℃, and allows for flexible adjustment of the oxidation atmosphere. By setting the temperature and residence time of the swirl calcination unit through an intelligent control unit, the decomposition degree of kaolinite, the removal efficiency of free and encapsulated carbon, and the aluminum-silicon ratio can be precisely controlled. Furthermore, by independently controlling the insulation temperature and time through the insulation silo, the crystal transformation path of SiO2 can be directionally adjusted (e.g., promoting the retention of highly active amorphous SiO2 or its transformation to a specific active crystal form in the 700-850℃ range), thereby significantly improving the activity index of the product. This dual-stage precise control mechanism of "calcination + insulation" allows for customized production based on downstream application needs (such as cementitious materials, rubber fillers, catalyst supports, etc.), solving the problems of poor modification and difficulty in controlling activity in traditional processes.

[0055] 5. Integrated dry decarbonization and modification

[0056] This invention employs a completely dry process, which, compared to wet decarbonization, eliminates the need for complex steps such as crushing, grinding, classification, gravity separation, and chemical bleaching, resulting in no wastewater discharge and significantly simplifying the process. The system utilizes a multi-stage cyclone separation combined with baghouse dust collection in both the dry material recovery unit and the high-temperature calcination material recovery unit, achieving efficient recovery of ultrafine powder. The exhaust gas is treated to meet emission standards or further utilized for waste heat recovery. Simultaneously, the cyclone calcination unit can be equipped with a decarbonization and denitrification agent supply device to achieve in-situ decarbonization and denitrification, effectively controlling sulfur oxide and nitrogen oxide emissions. The entire system achieves comprehensive environmental benefits—energy saving, consumption reduction, and emission reduction—while simultaneously carrying out decarbonization and modification.

[0057] In summary, this invention provides a cyclone calcination decarburization and modification system and process for coal gangue. Centered on direct gas-solid contact cyclone calcination, it comprehensively solves a series of technical problems in the prior art, including high energy consumption, uneven heating, easy agglomeration, difficult quality control, long process, low efficiency, poor material adaptability, and difficulty in recovering high-temperature ultrafine powder, through multi-stage waste heat recovery, precise temperature window control (primarily for oxidative decarburization, decomposition modification, control of aluminum-silicon ratio, and regulation of crystal transformation), and modular continuous operation. This system offers significant advantages in terms of advancement, economy, and environmental protection. Attached Figure Description

[0058] Figure 1 This is a schematic diagram of a coal gangue cyclone calcination decarbonization modification system provided in an embodiment of the present invention.

[0059] In the diagram: 1. Metering conveyor belt; 2. Servo screw feeder; 3. Flash dryer; 4. Drying cyclone separator; 5. Drying bag filter; 6. First induced draft fan; 7. Preheating cyclone separator; 8. Hot air furnace; 9. Cyclone calcining furnace; 10. Decarbonizing agent supply device; 11. High-temperature cyclone separator; 12. Diffusion heat exchange cyclone separator; 13. Insulated silo; 14. Blower; 15. Cooling cyclone separator; 16. Cooling bag filter; 17. Second induced draft fan; 18. Cooling silo. Detailed Implementation

[0060] The following specific embodiments illustrate the implementation of the present invention. Those skilled in the art can easily understand other advantages and effects of the present invention from the content disclosed in this specification. 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.

[0061] like Figure 1 As shown, this embodiment provides a coal gangue cyclone calcination decarbonization modification system, including: a quantitative feeding unit, a drying unit, a dried material recovery unit, a preheating unit, a hot air furnace 8, a cyclone calcination unit, a high-temperature calcination material recovery unit, an insulated silo 13, a cooling unit, and a cooling silo 18.

[0062] The outlet of the quantitative feeding unit is connected to the inlet of the drying unit, and is used to accurately and stably feed powdered materials (e.g., coal gangue powder that has been crushed and ground to 0-3mm) into the drying unit.

[0063] The quantitative feeding unit includes a metering conveyor belt 1 and a servo screw feeder 2. One end of the metering conveyor belt 1 is connected to the raw material silo, and the other end is connected to the inlet of the servo screw feeder 2; the outlet of the servo screw feeder 2 is connected to the inlet of the drying unit. This combination achieves precise metering and forced feeding of ultrafine powder, overcoming the problem of unstable feeding caused by poor powder flowability.

[0064] The air inlet of the drying unit is connected to the air outlet of the preheating unit, and the air outlet is connected to the air inlet of the dried material recovery unit. The drying unit is used to receive the material output from the quantitative feeding unit and the hot air (usually 200-400℃) discharged from the preheating unit, and to perform efficient "flash drying" by direct gas-solid mixing to quickly remove free moisture from the material.

[0065] The outlet of the dry material recovery unit is connected to a negative pressure device (such as an induced draft fan), and the outlet is connected to a dry material conveying pipeline. This unit uses negative pressure to attract the gas-powder mixture discharged from the drying unit, and efficiently collects the dry material in the gas-powder mixture through cyclone separation, bag filter dust collection, and other methods. At the same time, the exhaust gas discharged from the negative pressure device enters the exhaust gas treatment unit, and the dust-containing exhaust gas is treated to meet the emission standards.

[0066] The drying unit includes a flash dryer 3. The outlet of the servo screw feeder 2 is connected to the inlet of the flash dryer 3, and the air inlet of the flash dryer 3 is connected to the outlet of the preheating unit. The dried material recovery unit includes a drying cyclone separator 4 and a drying bag filter 5, which are connected sequentially after the flash dryer 3 and powered by a first induced draft fan 6. The drying cyclone separator 4 can be configured as a single stage or multiple stages in series as needed to achieve more efficient material recovery. The air-powder mixture after flash drying first passes through the drying cyclone separator 4 to recover most of the coarse particles, and then passes through the drying bag filter 5 for fine dust removal, ensuring that the exhaust gas meets the standards while achieving efficient recovery of the dried material. The recovered material is sent to the preheating unit through the dried material conveying pipeline.

[0067] The feed inlet of the preheating unit is connected to the hot air outlet of the high-temperature calcined material recovery unit via a waste heat flue gas reuse pipeline, and the middle section of the waste heat flue gas reuse pipeline is connected to the dried material conveying pipeline. This structure allows the preheating unit to receive the (500-800℃) hot air discharged from the high-temperature calcined material recovery unit, and under the power of this hot air, the dried material discharged from the dried material recovery unit is introduced into the pipeline via pneumatic conveying. During the conveying process, the dried material is directly mixed with the hot air and rapidly heated to approximately 400-700℃. Within this temperature range, free organic carbon on the material surface is effectively removed, avoiding local overheating or material caking and blockage caused by concentrated deflagration of organic carbon in the subsequent high-temperature calcination stage.

[0068] The outlet of the hot blast stove 8 is connected to the flue gas inlet of the swirl calcination unit, providing high-temperature flue gas for the core calcination stage of the entire system (the temperature can be precisely controlled between 500℃ and 1300℃ according to process requirements). The fuel for the hot blast stove 8 can be coal gas, natural gas, or a mixture of various gases.

[0069] The feed inlet of the swirl calcination unit is connected to the discharge outlet of the preheating unit to receive the preheated material and the high-temperature flue gas generated by the hot blast stove 8. Inside the unit, the material flows in a swirling, forward-flowing state with the high-temperature flue gas, maximizing the contact and heat exchange between the gas and solid phases. By precisely adjusting the residence time of the material (usually only 1-2 minutes) and the calcination temperature through an intelligent control unit (intelligent control unit), this unit can accurately control the degree of kaolinite decomposition, effectively remove residual free carbon, impurities, and lattice carbon encapsulated within the material particles, and regulate the aluminum-silicon ratio of the product. For high-calorific-value coal gangue, its swirling characteristics can quickly disperse the heat generated by local deflagration, achieving system temperature homogenization and preventing overburning.

[0070] The air inlet of the high-temperature calcination material recovery unit is connected to the flue gas outlet of the cyclone calcination unit, and is used to recover the calcined material entrained in the high-temperature flue gas. This unit typically uses equipment such as a high-temperature cyclone separator 11 to achieve efficient gas-solid separation.

[0071] The preheating unit includes a preheating cyclone separator 7, whose inlet is connected to the hot air outlet of the high-temperature calcined material recovery unit via a pipeline, its outlet is connected to the inlet of the cyclone calcination unit, and its outlet is connected to the inlet of the flash dryer 3. The preheating cyclone separator 7 can be configured as a single stage or multiple stages in series as needed to achieve more efficient stepped preheating.

[0072] The cyclone calcination unit includes a cyclone calcination furnace 9 and a decarbonizing agent supply device 10. The decarbonizing agent outlet of the decarbonizing agent supply device 10 is connected to the decarbonizing agent addition port of the cyclone calcination furnace 9. Under the control of the intelligent control unit, oxygen or decarbonizing agent (oxidant) can be added to the furnace to precisely regulate the oxidizing atmosphere environment inside the furnace, which is crucial for treating high-calorific-value coal gangue and thoroughly oxidizing the carbon coating. Optionally, the cyclone calcination unit can be equipped with a decarbonizing and denitrification agent supply device to achieve in-situ decarbonization and denitrification, effectively controlling the emission of sulfur oxides and nitrogen oxides.

[0073] The high-temperature calcination material recovery unit includes a high-temperature cyclone separator 11 and a diffusion heat exchange cyclone separator 12. The high-temperature cyclone separator 11 first recovers a large amount of high-temperature material, and the dust-laden hot gas it discharges enters the diffusion heat exchange cyclone separator 12. The diffusion heat exchange cyclone separator 12 not only further recovers ultrafine powder, but also has a heat exchange jacket on its outer shell. The insulated silo 13 also has an insulated jacket on its outer shell. A blower 14 introduces cold air into the bottom of the jacket of the insulated silo 13. This cold air is preheated by exchanging heat with the material inside the insulated silo 13, and then enters the heat exchange jacket of the diffusion heat exchange cyclone separator 12, where it exchanges heat again with the high-temperature flue gas inside, is heated to an even higher temperature, and is finally sent as combustion air to the burner of the hot blast stove 8. This design recovers the system's waste heat in stages, significantly reducing the fuel consumption of the hot blast stove 8, and can even achieve self-sustaining combustion of high-calorific-value coal gangue.

[0074] The inlet of the insulated silo 13 is connected to the outlet of the high-temperature calcined material recovery unit for receiving and storing high-temperature materials. The key function of the insulated silo 13 is to provide a controllable temperature and time window (e.g., insulation within the 700-850℃ range) to regulate the SiO2 crystal transformation process during recrystallization in the product (e.g., the transformation of amorphous SiO2 to specific crystal forms such as cristobalite and phosphogypsum), thereby significantly improving the activity index of SiO2 in the final product and meeting the specific activity requirements of different downstream applications (e.g., cement admixtures, rubber fillers). It should be noted that the insulated silo has the function of maintaining a stable temperature within a certain range. It can be equipped with a cooling or heating module and a temperature sensor. The intelligent control unit controls the operation of the cooling or heating module based on the temperature sensor information.

[0075] The cooling unit's outlet is connected to a negative pressure device, and its inlet is connected to a calcined material conveying pipeline. One end of the calcined material conveying pipeline forms an open end for air intake, and the section of the pipeline near the open end is connected to the discharge port of the insulated silo 13. When the negative pressure device is working, a large amount of cold air is drawn in from the open end, and it mixes violently with the high-temperature material (typically 400-800℃) discharged from the insulated silo 13 in the pipeline, achieving direct gas-solid contact rapid cooling. This method can cool the material to below 100℃ in a very short time, effectively preventing the unfavorable excessive crystal growth and sintering at high temperatures, and ensuring the product's dispersibility and reactivity. The cooled material is finally collected by the cooling unit (such as the cooling cyclone separator 15 and the cooling bag filter 16) and sent to the cooling silo 18 for storage.

[0076] The cooling unit includes a cooling cyclone separator 15 and a cooling bag filter 16, operating under negative pressure via a second induced draft fan 17. High-temperature material discharged from the insulated silo 13 is directly mixed and cooled with cold air in the pipeline, then sequentially recovered through the cooling cyclone separator 15 and the cooling bag filter 16 before finally being sent to the cooling silo 18. The cooling cyclone separator 15 can be configured as a single-stage or multi-stage series connection as needed to achieve more efficient material cooling and recovery. The air discharged from the second induced draft fan 17, carrying waste heat, can also be directed to the burner of the hot blast stove 8 as combustion air, or sent to other waste heat utilization units, maximizing heat utilization.

[0077] This invention also provides a process for decarbonizing and modifying coal gangue by cyclone calcination, using the system described in any of the above embodiments, and includes the following steps:

[0078] Step S1: Start-up and negative pressure creation. Start the first induced draft fan 6 to create a negative pressure environment inside the drying bag dust collector 5, the drying cyclone separator 4, the flash dryer 3, and the preheating cyclone separator 7.

[0079] Step S2: Heating. Start the hot air furnace 8 and supply high-temperature flue gas sequentially to the cyclone calciner 9, the preheating cyclone separator 7, and the flash dryer 3.

[0080] Step S3: Quantitative feeding and flash drying. Start the metering conveyor belt 1 and servo screw feeder 2 to precisely and quantitatively feed coal gangue powder into the flash dryer 3 under the control of the intelligent control unit. After the powder enters the flash dryer 3, it comes into direct contact with the high-temperature flue gas (about 200-400℃) from the preheating unit, and the dehydration and drying are completed instantly.

[0081] Step S4: Dry material recovery. The dried gas-powder mixture flows to the dry material recovery unit, where gas-solid separation is completed by the drying cyclone separator 4 and the drying bag filter 5, and the dried material is recovered.

[0082] Step S5: Preheating and surface carbon removal. The recovered dried material is carried into the dried material conveying pipeline by a negative pressure airflow and mixed with the waste heat flue gas (about 500-800°C) from the high-temperature calcined material recovery unit. During the process of conveying to the preheating cyclone separator 7, it is preheated to about 400-700°C, and the free organic carbon on the surface of the material is effectively removed at this stage.

[0083] Step S6: Cyclone Calcination. The preheated material enters the cyclone calciner 9 and mixes with the high-temperature flue gas (adjustable to 500-1300℃) generated by the hot blast stove 8 for cyclone calcination. Under the control of the intelligent control unit, the calcination temperature (e.g., controlled within the activity peak range of 700-850℃ or a higher decarburization whiteness range) and residence time are precisely adjusted to enable the material to complete physicochemical transformations such as oxidation decarburization and kaolinite decomposition. At the same time, the decarburizing agent supply device 10 can replenish oxygen into the furnace as needed to ensure that the coated carbon and lattice carbon are completely oxidized.

[0084] Step S7: High-Temperature Material Recovery and Insulation Modification. The high-temperature material after calcination enters the high-temperature calcination material recovery unit along with the flue gas, and is recovered through a high-temperature cyclone separator 11 and a diffusion heat exchange cyclone separator 12. The recovered high-temperature material (approximately 600-1000℃) is then sent to an insulated silo 13. Under the control of the intelligent control unit, the crystal transformation of SiO2 in the product is precisely controlled by adjusting the insulation temperature (e.g., 700-850℃) and insulation time of the insulated silo 13 (e.g., promoting the transformation of amorphous silicon to a specific active crystal form), ultimately obtaining a highly active modified product.

[0085] Step S8: Cooling and Finished Product Collection. The second induced draft fan 17 is started, and the high-temperature modified material in the insulated silo 13 enters the calcined material conveying pipeline through the discharge port, where it is directly mixed and cooled with the cold air drawn in from the open end. The cooled gas-solid mixture is recovered through the cooling cyclone separator 15 and the cooling bag filter 16, and the final finished product enters the cooling silo 18.

[0086] All of the above steps are completed under the control of the intelligent control unit, with a high degree of automation.

[0087] The optimization and control mechanism of process parameters are explained as follows:

[0088] The core of this process lies in the precise coupled control of the "temperature window" and "reaction time," which will be explained below in conjunction with the thermal evolution mechanism of coal gangue:

[0089] 400–600℃ (Preheating and Drying Material Recovery Section): This stage primarily involves the dehydroxylation reaction of kaolinite, resulting in a more porous structure, increased specific surface area, and increased SiO2 activity, preparing for subsequent deeper reactions. Simultaneously, removing surface organic carbon at this stage avoids the risk of subsequent deflagration.

[0090] 600–850℃ (core range of the swirl calcination section): Kaolinite completely decomposes into amorphous metakaolinite, SiO2 largely transforms into an amorphous / highly active state, the silicon-oxygen network depolymerizes, the number of active sites increases dramatically, and the reactivity reaches its peak. For applications requiring high activity (such as cement admixtures), process parameters will be precisely anchored within this range.

[0091] 850–1100℃ (high temperature range of the swirl calcination section): Amorphous silicon-aluminum begins to recrystallize into mullite and cristobalite, and the activity of SiO2 gradually decreases ("overheating deactivation"), but the physical properties of the product, such as whiteness and hardness, are improved. The process can be selected to calcine within this range according to the actual product requirements.

[0092] Flexible control of the insulated silo 13: After calcination, the material enters the insulated silo 13, which is not a simple cooling process, but a "crystal cultivation" process. By controlling the insulation temperature and duration, the growth of specific SiO2 crystal forms (such as cristobalite precursors) that contribute more to activity can be selectively promoted, thereby achieving a secondary enhancement of activity.

[0093] The cyclone calcination decarburization modification process and system for coal gangue provided by this invention effectively solves a series of technical problems mentioned in the background art, such as "high energy consumption, uneven heating, easy agglomeration, difficult quality control, long process, low efficiency, and limited material particle size" in rotary kiln calcination of coal gangue, through ingenious structural design and process coupling. Specifically, the solutions are as follows:

[0094] 1. Solving the problems of "high energy consumption" and "uneven heating": This system adopts flash drying and cyclone calcination technology of "direct gas-solid mixing," which differs from the inefficient mode of rotary kilns that rely on radiation heat transfer from the kiln wall and heat exchange on the surface of material accumulation. The material is in a highly dispersed fluidized state in both the drying and cyclone calcination units, directly contacting the hot air. The heat and mass transfer area increases geometrically, resulting in extremely high heat exchange efficiency and significantly reducing the heat consumption per unit product. Simultaneously, the strong turbulence and rotating flow field within the cyclone calcination unit ensures that every material particle is heated uniformly and rapidly, completely eliminating the problems of large temperature gradients and uneven heating caused by material accumulation and slow tumbling in rotary kilns. This fundamentally avoids calcination defects such as "under-burning," "over-burning," and "under-burning."

[0095] 2. Solving the problems of "easy agglomeration" and "difficult quality control": In the cyclone calcination unit, the material flows with high-speed hot air, and the particles are separated by the airflow, existing in a swirling and floating state. This eliminates the conditions in rotary kilns where materials accumulate and tumble due to gravity, causing them to stick together and sinter into large lumps. Even when processing ultrafine powders, agglomeration and clumping will not occur. Simultaneously, because the calcination temperature and time can be precisely controlled (adjusted by the intelligent control unit), and the temperature field is uniform, the product particle size is uniform, whiteness and dispersibility are stable, and quality is completely controllable. The system removes surface organic carbon in advance through the preheating unit, avoiding localized overheating caused by deflagration of high-calorific-value materials in the calcination furnace, further ensuring the uniformity of product quality.

[0096] 3. Solving the problems of "long process and low efficiency" and "limited material particle size": This system highly integrates multiple processes such as drying, preheating, calcination, modification, and cooling into a continuous production line. Material takes only 1-2 minutes from feeding to discharging, while traditional rotary kiln processes require several hours or even longer. This not only significantly shortens the production cycle and improves production efficiency, but also allows for a compact equipment layout due to the modular structure, significantly reducing the footprint of the project. Furthermore, due to the use of pneumatic conveying and cyclone flow technology, the system has extremely low requirements for material particle size (0-3mm), and can even handle ultrafine powders, completely overcoming the bottleneck of rotary kilns in handling ultrafine powders due to poor material flowability, greatly expanding the adaptability of raw materials.

[0097] 4. By setting up a cooling unit and a cooling silo, direct mixing and rapid cooling of high-temperature modified materials with cold air is achieved. This cooling method is extremely efficient, capable of instantly reducing the material temperature to a safe range, effectively "freezing" the ideal crystal form and active state obtained at high temperatures (such as amorphous SiO2), preventing excessive crystallization and activity reduction caused by slow cooling, and ensuring the final quality of the product.

[0098] 5. The quantitative feeding unit adopts a metering conveyor belt and a servo screw feeder. The combination of the two realizes accurate metering and forced and stable feeding of ultrafine powder with poor flowability, ensuring the stability of system operation and the consistency of final product quality, and solving the process control problem caused by feeding fluctuations.

[0099] 6. The drying unit adopts a flash dryer, combined with a two-stage recovery unit consisting of a cyclone separator and a bag filter, achieving efficient and low-emission recovery of the dried fine powder. Flash drying is particularly suitable for paste-like or ultrafine wet materials, with high drying intensity; while the two-stage recovery structure ensures the cleanliness of the exhaust gas emissions, resulting in significant environmental benefits.

[0100] 7. The preheating unit adopts a preheating cyclone separator, which has a simple structure and combines gas-solid separation and preheating functions into one. The waste heat flue gas discharged from the high-temperature calcination material recovery unit is used to directly preheat the material, which not only recovers low-grade waste heat, but also removes organic carbon from the surface of the material in advance, creating conditions for safe and precise calcination in the future.

[0101] 8. The cyclone calcination unit is equipped with a decarburizing agent supply device, which allows the system to flexibly adjust the oxidizing atmosphere and sulfide environment inside the furnace. This is of great significance for processing high-sulfur coal gangue, achieving deep decarburization (especially encapsulated carbon and lattice carbon), and achieving in-situ decarburization, further expanding the system's raw material processing range and environmental friendliness.

[0102] 9. By setting up a high-temperature cyclone separator and a diffusion heat exchange cyclone separator, efficient recovery of high-temperature ultrafine powder is achieved. More importantly, through the design of the insulation jacket and heat exchange jacket, the heat dissipation of the insulated silo and the waste heat of the diffusion heat exchange cyclone separator are recovered in stages for preheating the combustion air, which greatly improves the thermal economy of the system and makes it possible to use the material's own calorific value for self-sustaining combustion, thereby significantly reducing or even completely replacing external fuel consumption.

[0103] 10. The cooling unit also adopts a two-stage structure of cyclone + bag filter, which realizes efficient recovery of the cooled product and clean emission of exhaust gas. At the same time, the air with a large amount of waste heat generated during the cooling process is introduced back into the burner for combustion, realizing the complete utilization of heat and maximizing the overall thermal efficiency of the system.

[0104] 11. Based on the aforementioned system, through specific steps and parameter design, particularly by precisely matching the temperature and function of each stage—preheating, calcination, heat preservation, and cooling—to the phase evolution of coal gangue at different temperature ranges (e.g., activation at 400-600℃, high activity at 600-850℃, and controllable crystal transformation at 700-850℃), and by cascading and recycling the waste heat from each stage (insulation jacket, heat exchange jacket, and cooling exhaust), this process not only possesses all the advantages of the system structure but also achieves precise temperature control, directional modification, and maximized energy utilization at the operational level. It is an advanced manufacturing method that is highly efficient, energy-saving, intelligent, and clean.

[0105] In summary, this invention fundamentally overturns the traditional stacked calcination mode by constructing a process and system for direct gas-solid contact, efficient heat and mass transfer, and continuous swirling calcination, achieving the goals of low energy consumption, no agglomeration, uniform quality, short process, and strong raw material adaptability.

[0106] Furthermore, this process utilizes a diffusion heat exchange cyclone separator and a sandwich design with insulated silos to recover waste heat from high temperatures (>800℃) to medium and low temperatures (<200℃) in stages. This heat is then used in stages to preheat the combustion air and dry the materials, significantly improving the system's thermal efficiency. For high-calorific-value coal gangue (>600kcal / kg), the system can even achieve self-sustaining combustion by shutting down the hot air furnace or supplementing only a small amount of fuel after startup, completely solving the problem of high energy consumption in traditional processes.

[0107] Although the present invention has been described in detail above with general descriptions and specific embodiments, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, all such modifications or improvements made without departing from the spirit of the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A coal gangue cyclone calcination decarburization and modification system, characterized in that, It includes a quantitative feeding unit, a drying unit, a dried material recovery unit, a preheating unit, a hot air furnace, a cyclone calcination unit, a high-temperature calcined material recovery unit, and an insulated silo; The outlet of the quantitative feeding unit is connected to the inlet of the drying unit, and is used to: feed powdered materials into the drying unit; The air inlet of the drying unit is connected to the air outlet of the preheating unit, and the air outlet is connected to the air inlet of the dried material recovery unit. It is used to receive the material output from the quantitative feeding unit and the hot air discharged from the preheating unit, and the material and hot air are directly mixed for flash drying. The air outlet of the dry material recovery unit is connected to a negative pressure device, and the discharge outlet is connected to a dry material conveying pipeline, which is used to: draw the gas-powder mixture discharged by the drying unit under negative pressure and collect the dry material in the gas-powder mixture. The feed inlet of the preheating unit is connected to the hot air outlet of the high-temperature calcined material recovery unit through a waste heat flue gas reuse pipeline, and the middle section of the waste heat flue gas reuse pipeline is connected to the dry material conveying pipeline. This pipeline is used to: receive the hot air discharged from the high-temperature calcined material recovery unit, and pneumatically introduce the dry material discharged from the recovery unit under the action of the hot air, so that the material is directly heated by the hot air and the free organic carbon on the surface of the material is removed. The air outlet of the hot air furnace is connected to the flue gas inlet of the swirl calcination unit to provide high-temperature flue gas; The feed inlet of the cyclone calcination unit is connected to the discharge outlet of the preheating unit, and is used to: receive the dried preheated material discharged from the preheating unit and the hot air generated by the hot air furnace, mix the received dried preheated material with the hot air, and make the dried preheated material flow forward with the hot air, control the calcination temperature and time, oxidize and decarbonize the dried preheated material, decompose and modify it, effectively remove the remaining free carbon, impurities carbon and encapsulated carbon, control the degree of kaolin decomposition, and control the aluminum-silicon ratio; The air inlet of the high-temperature calcining material recovery unit is connected to the flue gas outlet of the cyclone calcining unit, and is used to: recover the material in the high-temperature flue gas discharged from the cyclone calcining unit; The inlet of the insulated silo is connected to the outlet of the high-temperature calcined material recovery unit, and is used to: control the insulation temperature and time, adjust the SiO2 crystal form transformation during recrystallization, and improve the SiO2 activity index.

2. The coal gangue cyclone calcination decarbonization modification system as described in claim 1, characterized in that, It also includes a cooling unit and a cooling silo (18); The air outlet of the cooling unit is connected to a negative pressure device, and the air inlet is connected to a calcined material conveying pipeline. One end of the calcined material conveying pipeline forms an open end for air to enter. The pipe end of the calcined material conveying pipeline near the open end is connected to the discharge port of the heat-insulating silo (13) for: negative pressure to attract the high-temperature material discharged from the heat-insulating silo (13), and the material is directly mixed with air to cool the material. The inlet of the cooling silo (18) is connected to the outlet of the cooling unit and is used to store the cooled finished material.

3. The coal gangue cyclone calcination decarbonization modification system as described in claim 2, characterized in that, The quantitative feeding unit includes a metering conveyor belt (1) and a servo screw feeder (2); one end of the metering conveyor belt (1) is connected to the raw material warehouse, and the other end is connected to the feed inlet of the servo screw feeder (2); the discharge port of the servo screw feeder (2) is connected to the feed inlet of the drying unit.

4. The coal gangue cyclone calcination decarbonization modification system as described in claim 3, characterized in that, The drying unit includes a flash dryer (3), the outlet of the servo screw feeder (2) is connected to the inlet of the flash dryer (3), and the air inlet of the flash dryer (3) is connected to the air outlet of the preheating unit. The dry material recovery unit includes a dry cyclone separator (4) and a dry bag filter (5). The air inlet of the dry cyclone separator (4) is connected to the air outlet of the flash dryer (3), and the air outlet of the dry cyclone separator (4) is connected to the air inlet of the dry bag filter (5). The air outlet of the dry bag filter (5) is connected to a first induced draft fan (6), and the air outlet of the first induced draft fan (6) is connected to a tail gas treatment device. The discharge ports of the dry cyclone separator (4) and the dry bag filter (5) are respectively connected to the dry material conveying pipeline. One or more dry cyclone separators (4) are provided as needed.

5. The coal gangue cyclone calcination decarbonization modification system as described in claim 4, characterized in that, The preheating unit includes a preheating cyclone separator (7). The inlet of the preheating cyclone separator (7) is connected to the hot air outlet of the high-temperature calcined material recovery unit through a waste heat flue gas reuse pipeline. The outlet of the preheating cyclone separator (7) is connected to the inlet of the cyclone calcination unit. The outlet of the preheating cyclone separator (7) is connected to the inlet of the flash dryer (3). One or more preheating cyclone separators (7) are provided as needed.

6. The coal gangue cyclone calcination decarbonization modification system as described in claim 5, characterized in that, The cyclone calcination unit includes a cyclone calcination furnace (9) and a decarbonizing agent supply device (10). The feed inlet of the cyclone calcination furnace (9) is connected to the discharge outlet of the preheating cyclone separator (7). The flue gas inlet of the cyclone calcination furnace (9) is connected to the air outlet of the hot air furnace (8). The flue gas outlet of the cyclone calcination furnace (9) is connected to the air inlet of the high-temperature calcined material recovery unit. The decarbonizing agent outlet of the decarbonizing agent supply device (10) is connected to the decarbonizing agent addition port of the cyclone calcination furnace (9).

7. The coal gangue cyclone calcination decarbonization modification system as described in claim 6, characterized in that, The high-temperature calcination material recovery unit includes a high-temperature cyclone separator (11) and a diffusion heat exchange cyclone separator (12). The air inlet of the high-temperature cyclone separator (11) is connected to the flue gas outlet of the cyclone calciner (9), and the air outlet of the high-temperature cyclone separator (11) is connected to the air inlet of the diffusion heat exchange cyclone separator (12). The air outlet of the diffusion heat exchange cyclone separator (12) is connected to the waste heat flue gas reuse pipeline. One or more of the high-temperature cyclone separator (11) and / or diffusion heat exchange cyclone separator (12) are provided as needed. The insulation silo (13) is provided with an insulation jacket, and the bottom air inlet of the insulation jacket is connected to a blower (14). The diffusion heat exchange cyclone separator (12) is provided with a heat exchange jacket, the bottom air inlet of the heat exchange jacket is connected to the top air outlet of the insulation jacket, and the top air outlet of the heat exchange jacket is connected to the combustion air inlet of the burner of the hot air furnace (8).

8. The coal gangue cyclone calcination decarbonization modification system as described in claim 7, characterized in that, The cooling unit includes a cooling cyclone separator (15) and a cooling bag filter (16). The air inlet of the cooling cyclone separator (15) is connected to the calcined material conveying pipeline, and the air outlet of the cooling cyclone separator (15) is connected to the air inlet of the cooling bag filter (16). The air outlet of the cooling bag filter (16) is connected to a second induced draft fan (17), and the air outlet of the second induced draft fan (17) is connected to the waste heat utilization unit or the combustion air inlet of the burner. One or more cooling cyclone separators (15) are provided as needed.

9. A process for decarburization and modification of coal gangue by cyclone calcination, characterized in that, The coal gangue cyclone calcination decarbonization modification system according to any one of claims 1-8 includes the following steps: Start the first induced draft fan (6) to create a negative pressure environment in the drying bag dust collector (5), the drying cyclone separator (4), the flash dryer (3), and the preheating cyclone separator (7); Start the hot air furnace (8) and supply high-temperature flue gas to the cyclone calciner (9), the preheating cyclone separator (7), and the flash dryer (3) in succession; Start the metering conveyor belt (1) and servo screw feeder (2) to accurately and quantitatively feed materials to the flash dryer (3) under the control of the intelligent control unit; Powdered materials enter the flash dryer (3) for flash drying, and come into direct contact with high-temperature flue gas, causing the material to heat up rapidly, dehydrate and dry. The dried material flows to the dried material recovery unit and is recovered by the drying cyclone separator (4) and the drying bag dust collector (5); The recovered dried material flows to the preheating cyclone separator (7) and comes into direct contact with the high-temperature flue gas. The dried material exchanges heat with the high-temperature flue gas, increases its temperature, and removes the free organic carbon on the surface of the material. The dried and preheated material flows to the cyclone calciner (9) and is calcined in the furnace. The dried and preheated material flows in the forward direction with the hot air. Under the control of the intelligent control unit, the calcination temperature and time are controlled to oxidize and decarbonize the dried and preheated material, decompose and modify it, control the degree of kaolin decomposition, and control the aluminum-silicon ratio. The decarbonizing agent supply device (10) supplies oxygen to the cyclone calciner (9) as needed under the control of the intelligent control unit, adjusts the oxygen environment, and effectively removes the remaining free carbon, mixed carbon and encapsulated carbon. The high-temperature material after calcination flows to the high-temperature calcined material recovery unit, and is effectively recovered by the high-temperature cyclone separator (11) and the diffusion heat exchange cyclone separator (12). The recovered material is sent to the heat-insulated silo (13). The modification temperature and time are set as needed. The recovered calcined material is modified in the heat-insulating silo (13). The heat-insulating temperature and time are controlled to adjust the SiO2 crystal form transformation during recrystallization and improve the SiO2 activity index. The second induced draft fan (17) is started, and the modified material in the heat-insulated silo (13) is conveyed by pneumatic conveying to the cooling unit. It is cooled and recovered by the cooling cyclone separator (15) and the cooling bag dust collector (16). The cooled and recovered material enters the cooling silo (18).

10. The coal gangue cyclone calcination decarburization modification process as described in claim 9, characterized in that, It also includes the following steps: Start the blower (14) to blow cooling air into the insulation jacket outside the insulation silo (13) to adjust the temperature of the insulation silo (13) so that the high temperature calcined material in the insulation silo (13) is cooled down to the temperature range required for modification. After the standard is met, the insulation silo (13) is kept warm and the temperature no longer decreases or can only decrease slowly. The cooling air flowing in the insulation interlayer is initially heated; The preheated cooling air enters the heat exchange jacket outside the diffusion heat exchange cyclone separator (12) and exchanges heat with the high-temperature flue gas in the inner cylinder of the diffusion heat exchange cyclone separator (12), and the cooling air is further heated. The further heated cooling air is supplied to the burner as combustion gas; at the same time, the air with residual heat discharged by the second induced draft fan (17) is supplied to the burner as combustion gas.

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