Coal gangue activating and calcining process and system cooperatively coupled with cement kiln system

Abstract

The invention relates to the technical field of coal gangue activation and calcination, in particular to a coal gangue activation and calcination process and system cooperatively coupled with a cement kiln system, and the coal gangue activation and calcination system cooperatively coupled with the cement kiln system comprises a calcining furnace system, an auxiliary tertiary air pipe and an auxiliary residual air pipe, the auxiliary residual air pipe is connected with the cooling machine and the calcining furnace, the two ends of the auxiliary tertiary air pipe are connected with the tertiary air pipe and the calcining furnace, and the two ends of the tertiary air pipe are connected with the decomposing furnace and the kiln head of the sintering system. The invention provides a coal gangue activating and calcining process and system cooperatively coupled with a cement kiln system.

Description

Technical Field

[0001] The present invention relates to the technical field of activated calcination of coal gangue, and in particular to a coal gangue activated calcination process and system synergistically coupled with a cement kiln system. Background Art

[0002] In 2021, my country's coal production was 4 billion tons. During coal mining and coal preparation plant operations, a large amount of coal gangue (accounting for about 15% of coal production) will be generated. Coal gangue is usually discharged to the ground as solid waste, occupying valuable land resources, and causing underground seepage, spontaneous combustion and other phenomena, which have an adverse impact on the environment. According to incomplete statistics, coal gangue accounts for about 20% of the country's industrial solid waste. At present, the cumulative amount of coal gangue stockpiled in my country exceeds 6 billion tons. A lot of exploration and practice have been carried out at home and abroad on the comprehensive utilization of coal gangue, forming a comprehensive treatment and utilization system for power generation, paving, production of building materials, production of chemical raw materials, agricultural applications and underground filling. However, the comprehensive utilization rate of coal gangue is less than 30%.

[0003] In the field of building materials, extensive research has been conducted on the application of coal gangue, for example, in the production of machine-made sand and gravel aggregates or in calcining it with limestone as a cementitious material. However, the disposal volume and effectiveness of its use have been limited. Calcination activation technology, where heat generated by fuel combustion is transferred to the gangue, decomposing the kaolinite (typically 40-60%) contained in it into metakaolinite, is a viable technology for large-scale resource utilization of coal gangue.

[0004] Kaolinite (Al2O3·2SiO2·2H2O, AS2H2) dehydrates at appropriate temperatures to form metakaolinite (Al2O3·2SiO2, AS2). Kaolinite has a layered silicate structure, with layers held together by van der Waals bonds, where OH- ions are firmly bound. When heated in air, kaolinite undergoes several structural changes. At approximately 300°C, dehydration destroys the layered structure, forming a transitional phase with poor crystallinity—metakaolinite. Due to its irregular molecular arrangement and thermodynamically metastable state, metakaolinite exhibits gelling properties when properly stimulated. It reacts with Ca(OH)2(CH4) and water to form a hydration product similar to cement. This characteristic can be exploited when used as a cement admixture, where it reacts with CH4 produced during cement hydration, improving certain cement properties. Since the preparation cost of metakaolin is lower than that of cement clinker, and CO2 emissions during its preparation are also lower than those during clinker preparation, the use of metakaolin as a substitute for clinker in these industries is particularly attractive given the ongoing efforts to reduce carbon emissions in the construction concrete and cement industries. Furthermore, metakaolin exhibits physical properties such as low density, large specific surface area, and high oil absorption. Besides being used as a concrete and cement additive, it can also replace pigments, plastic and rubber fillers, adsorbents, and 4A molecular sieves. It can be used as a raw material or filler in industries such as ceramics, papermaking, rubber, coatings, and petrochemicals. This wide range of applications gives it high economic added value. Given this background, the preparation of metakaolin by calcining activated coal gangue offers promising application prospects and high economic added value.

[0005] Existing gangue calcination and activation technologies can be divided into two categories based on the dispersion state of the gangue material in the hot gas flow: bulk activation calcination and suspended activation calcination. Bulk activation calcination generally uses granular or lumpy gangue in a piled state in the calcination kiln. Due to the large particle size and low thermal conductivity of the gangue, the contact area between the material and the hot gas flow is small, resulting in low heat exchange efficiency. Furthermore, the large temperature difference between the inside and outside of the gangue block can lead to overburning on the outside and underburning on the inside, seriously affecting product quality and activity. Considering that kaolinite, the main active component in gangue, can produce highly active metakaolinite after dehydroxylation at appropriate temperatures, this reaction is endothermic. When the temperature rises to around 300°C, kaolinite begins to decompose into metakaolinite and generate water vapor. The decomposition rate accelerates as the temperature rises, and decomposition is essentially complete above 800°C. The decomposition reaction rate of gangue is primarily affected by factors such as calcination temperature and particle size. Studies have found that larger gangue particle size reduces the heat transfer efficiency between materials, resulting in a slower dehydroxylation reaction. Therefore, grinding gangue into a powder and calcining it in a suspended state can effectively increase the rate of the dehydroxylation reaction. This involves utilizing a suspended preheating decomposition technique to preheat and decompose the powdered gangue in a suspended state. Existing research indicates that grinding gangue into a powder and calcining it in a suspended state can effectively prevent the phenomenon of overburning the exterior and underburning the interior of the finished calcined gangue product.

[0006] Coal gangue contains a certain amount of kaolinite, which can be used as a raw material for the preparation of metakaolin. Theoretically, metakaolin can be prepared on a large scale through calcination and activation. However, coal gangue often contains more combustible substances, which will release a certain amount of heat at high temperatures. When coal gangue is used as a raw material for the preparation of metakaolin, the coal gangue will burn and release heat in the preheater system, which will cause problems such as crusting and blockage in the preheater system. Summary of the Invention

[0007] The purpose of this application is to solve the technical problems in the prior art and to provide a coal gangue activation calcination process and system that is synergistically coupled with a cement kiln system.

[0008] The technical solutions adopted by the embodiments of the present application to solve the technical problems existing in the known technologies are: A gangue activation and calcination system synergistically coupled with a cement kiln system, comprising a calcining furnace system, an auxiliary tertiary air duct and an auxiliary residual air duct, wherein the auxiliary residual air duct is connected to a cooler and a calcining furnace, the two ends of the auxiliary tertiary air duct are connected to the tertiary air duct and the calcining furnace, and the two ends of the tertiary air duct are connected to a decomposition furnace and a kiln head of a firing system.

[0009] The embodiments of the present application may also adopt the following technical solutions: In the above-mentioned gangue activation calcination system coupled with the cement kiln system, further, the gangue activation calcination system coupled with the cement kiln system also includes a suspension preheating system, and the suspension preheating system includes one to two-stage cyclone preheaters. The feeding point of the gangue is arranged at the air inlet pipe of the uppermost cyclone preheater, the air outlet pipe of the uppermost cyclone preheater is connected to the flue gas waste heat utilization system, and the discharge pipe of the lowermost cyclone preheater is connected to the calcining furnace.

[0010] In the above-mentioned gangue activation calcination system coupled with the cement kiln system, further, the gangue activation calcination system coupled with the cement kiln system also includes a suspended cooling system, and the suspended cooling system includes a first cooling system and a second cooling system; the first cooling system includes a first-stage cyclone cooler, the air inlet pipe of the cyclone cooler of the first cooling system is connected to the calcining furnace, the air outlet pipe of the cyclone cooler of the first cooling system is connected to the suspended preheating system of the existing firing system, and the discharge pipe of the cyclone cooler of the first cooling system is connected to the air inlet pipe of the uppermost cyclone cooler of the second cooling system; the second cooling system includes two to three-stage cyclone coolers, the air inlet pipe of the lowermost cyclone cooler of the second cooling system is connected to the cooling air, and the discharge pipe of the lowermost cyclone cooler of the second cooling system is connected to the finished zipper machine.

[0011] In the above-mentioned gangue activation calcination system coupled with the cement kiln system, further, the air outlet pipe of the cyclone cooler of the first cooling system is connected to the air outlet pipe of the lowest stage cyclone preheater of the suspension preheating system of the existing firing system.

[0012] In the above-mentioned gangue activation calcination system coupled with the cement kiln system, further, the existing firing system includes a suspension preheating system, a decomposition furnace, a rotary kiln and a cooler connected in sequence, and the outlet pipe of the top-level cyclone preheater of the suspension preheating system of the existing firing system is connected to the waste heat boiler, and the outlet of the waste heat boiler is connected to the raw mill through a high-temperature fan.

[0013] A gangue activation calcination process synergistically coupled with a cement kiln system, the gangue activation calcination process synergistically coupled with a cement kiln system comprising the following steps: Step 1: Extract part of the high-temperature tertiary air and medium-temperature residual air from the existing firing system into the calcining furnace.

[0014] In the above-mentioned coal gangue activation calcination process coupled with the cement kiln system, further, the temperature of the high-temperature tertiary air is 850~1050℃, the temperature of the medium-temperature residual air is 250~350℃, the volume ratio of the high-temperature tertiary air and the medium-temperature residual air entering the calciner is 1:1~1:3, constituting mixed combustion air, and the temperature of the mixed combustion air entering the calciner is 600~800℃.

[0015] In the above-mentioned coal gangue activation calcination process synergistically coupled with the cement kiln system, further, the coal gangue activation calcination process synergistically coupled with the cement kiln system includes the following steps: after the flue gas leaving the calcining furnace is subjected to gas-solid separation, the flue gas enters the suspension preheating system of the existing firing system to preheat the raw material to achieve heat recovery and utilization.

[0016] In the above-mentioned gangue activation calcination process synergistically coupled with the cement kiln system, further, the gangue activation calcination process synergistically coupled with the cement kiln system includes the following steps: the medium-temperature air exiting the suspension cooling system is preheated on the gangue, and the temperature of the medium-temperature air entering the suspension preheating system is 300~450℃, which is lower than the stable ignition temperature of the combustible materials in the gangue.

[0017] In the above-mentioned gangue activation calcination process synergistically coupled with the cement kiln system, further, the calcination temperature in the calcination furnace is 650-1000°C; The residence time of the gas in the calcining furnace is 2 to 10 seconds; The coal gangue has a calorific value of 300-700 kcal / kg.

[0018] One or more technical solutions provided in the embodiments of this application have at least the following beneficial effects: 1. This invention fully considers the characteristics of existing cement clinker production processes and gangue activation calcination. The newly installed gangue suspension activation calcination system is fully synergistically coupled with the existing cement kiln system. This invention considers extracting a portion of the high-temperature tertiary air and medium-temperature residual air from the existing cement kiln system to feed the newly added calciner system. This portion of high-temperature tertiary air and medium-temperature residual air serves as a heat source for the decomposition of kaolinite in the gangue and as combustion air for the combustion of combustibles in the gangue.

[0019] The flue gas generated by the decomposition of kaolinite in the gangue and the combustion of fuel in the calciner system is separated into gas and solids by the cyclone separator at the calciner system outlet. The flue gas then enters the outlet pipe of the lowest-stage cyclone separator in the existing firing system, thereby maximizing the recovery of the flue gas's heat enthalpy. The raw meal fed into the suspension preheating system then undergoes multiple preheating and gas-solid separations before finally exiting the outlet of the highest-stage cyclone preheater in the existing firing system.

[0020] In summary, the present invention fully utilizes part of the high-temperature tertiary air and medium-temperature residual air of the cement clinker production line in the calciner system to enter the calciner system for combustion assistance and stable combustion. The high-temperature flue gas generated by the calciner system can preheat the low-temperature raw material of the existing cement clinker production line. While fully recovering and utilizing heat, it can reduce the energy consumption of the existing firing system. At the same time, the flue gas with fully recovered heat can also utilize the waste gas treatment system of the existing cement clinker production line.

[0021] 2. This invention takes into account that the extraction of high-temperature tertiary air will affect the stable operation of the existing firing system to a certain extent, while the thermal enthalpy of the medium-temperature residual air is insufficient to ensure the stable operation of the calciner system. Therefore, the present invention rationally designs the volume of the extracted high-temperature tertiary air and the medium-temperature residual air, namely, a volume ratio of 1:1-1:3. This ensures that the temperature of the mixed combustion-supporting air entering the calciner system is within the optimal temperature range of 600-800°C (this temperature range is the optimal temperature range for the complete combustion of combustibles in coal gangue). This minimizes the impact on the existing firing system while ensuring the stable operation of the calciner system. At this point, the volume of high-temperature tertiary air extracted by the calciner system can be controlled at a relatively low value.

[0022] 3. The present invention develops a suspension cooling / preheating combination system, which has both material cooling and preheating functions. Among them, the suspension cooling / preheating combination system includes a suspension preheating system and a suspension cooling system. The two lowest cyclone separators of the suspension cooling system are the second cooling system of the suspension cooling system, which are used to fully cool the high-temperature gangue material separated by the first cooling system of the suspension cooling system to a suitable temperature (60~150℃ according to actual production). The medium-temperature air exiting the suspension cooling system enters the suspension preheating system to preheat the gangue raw materials fed into the suspension preheating + cooling combination system and then enter the calcining furnace system. Since the temperature of the medium-temperature air is lower than the initial temperature of stable combustion of combustibles in the gangue, it can achieve full heat recovery and utilization while avoiding premature combustion of the gangue material in the suspension preheating system, which may cause system crusting and blockage.

[0023] 4. Currently, existing technologies fail to consider the production reality of raw materials containing combustibles. This results in the gangue material burning and releasing a large amount of heat during the suspension preheating process, leading to crusting and blockage in the preheater system, thus affecting the stable operation of the system. The present invention sequentially arranges the suspension preheating system and the suspension cooling system from top to bottom. The two systems are relatively independent and have clear functional positioning.

[0024] The air temperature exiting the first cooling system is lower than the ignition temperature of the combustibles in the gangue (this ignition temperature varies depending on the type of gangue raw material and needs to be determined based on tests of the combustion characteristics of the gangue raw material), thereby ensuring that the ignition point of the combustibles in the gangue will not be reached during the process of preheating the gangue powder with this air. The fully preheated gangue enters the calciner in a short period of time. The combustion, heat release, and decomposition of the gangue occur within the calciner system. This prevents the gangue from burning and releasing heat within the preheater system, which would increase the flue gas temperature at the preheater outlet and thus the heat consumption of the system. It also prevents the gangue from burning and releasing heat within the preheater system, which could cause crusting and blockage in the preheater system and affect the stable operation of the system.

[0025] 5. The present invention utilizes a rationally designed suspension calcining system, ensuring its adaptability to gangue feedstocks with varying calorific values. Specifically, the present invention is most suitable for gangue with low to medium calorific values ​​(assuming a natural calorific value of 300-700 kcal / kg). When the gangue composition and natural calorific value satisfy a specific mathematical relationship, the inherent heat content of the gangue can meet the calorific requirements for kaolinite decomposition. In this case, the present invention's calciner system eliminates the need for additional fuel, enabling resourceful utilization of the gangue while also eliminating the need for an additional fuel supply.

[0026] 6. The present invention produces highly active calcined gangue with lower energy consumption and higher efficiency, and avoids the problem that the combustibles in the gangue release a large amount of heat in the preheater, causing the system to be crusted and blocked, and resulting in the production line being unable to operate stably. It is conducive to the large-scale production and wide application of calcined gangue and calcined gangue-limestone composite cement. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The following will further describe the technical solutions of the embodiments of the present application in conjunction with the accompanying drawings. However, it should be understood that these drawings are designed for illustrative purposes only and are not intended to limit the scope of the present application. In addition, unless otherwise specified, these drawings are intended only to conceptually illustrate the structures described herein and are not necessarily drawn to scale.

[0028] Figure 1 It is a process flow chart of an embodiment of the present invention. DETAILED DESCRIPTION

[0029] The suspension cooling / preheating combined system includes a suspension preheating system and a suspension cooling system. The suspension preheating system includes a cyclone preheater, a high-efficiency material spreading device and connecting pipes, etc. The suspension cooling system includes a cyclone cooler, a high-efficiency material spreading device and connecting pipes, etc.

[0030] The calciner system includes a high-efficiency material spreading device, hot air inlet ducts, and flue gas outlet ducts. Multiple temperature measurement points are layered along the height of the calciner to monitor the temperature distribution within the calciner in real time. By adjusting the amount of material fed into the calciner system, the temperature distribution within the calciner is controlled within a reasonable range. This reasonable temperature distribution within the calciner ensures the complete combustion of combustibles in the gangue and the complete decomposition of kaolinite, while also ensuring that the gangue is not overburned and that the activity of the finished kaolinite meets subsequent production requirements.

[0031] In terms of material flow in this embodiment: Gangue raw material containing kaolinite and a certain calorific value first enters a drying and crushing machine, where it is dried and crushed to produce gangue powder particles that meet production needs. These particles are then fed through a feeding device and into the suspension preheating system of the combined suspension cooling / preheating system. The gangue powder undergoes preheating and gas-solid separation in a cyclone preheater. After heat exchange and gas-solid separation, the raw meal enters the calcining furnace system through the discharge pipe of the cyclone preheater in the suspension preheating system.

[0032] The heat released by the combustion of the coal gangue in the calciner system and the heat carried by the hot air entering the calciner system are used to decompose the kaolinite in the coal gangue. The decomposed hot materials leave the calciner system and then enter the second cooling system of the suspension cooling system after gas-solid separation with the hot flue gas in the first cooling system of the suspension cooling system.

[0033] The hot material is rapidly cooled and undergoes gas-solid separation in the suspension cooling system. After rapid cooling, the material leaves the discharge pipe of the lowest-level cyclone cooler in the suspension cooling system and falls into the finished zipper machine, ultimately obtaining a finished product that meets the requirements.

[0034] In this embodiment, according to the gas flow direction: In this embodiment, there are three gas sources. In terms of gas flow direction, there are: The first-line normal temperature air enters the cyclone cooler of the second cooling system, and then cools the materials entering the suspension cooling / preheating combined system. The air that has completed the heat exchange leaves from the outlet of the top-level cyclone cooler of the second cooling system, and then enters the cyclone preheater of the suspension preheating system to preheat and separate the fed coal gangue powder particles into gas and solids, and finally leaves from the outlet of the top-level cyclone preheater of the suspension preheating system. The waste heat of this air is then recovered and utilized, and finally discharged into the atmosphere after flue gas treatment.

[0035] The second route is a tertiary air duct connected to the calciner system via an auxiliary tertiary air duct. A valve is installed on the connecting pipe, and the valve opening is adjusted to control the tertiary air volume entering the calciner system. A portion of the high-temperature tertiary air from the existing firing system enters the calciner system through the auxiliary tertiary air duct as combustion air and an external heat source for the calciner system. This promotes the complete combustion of combustibles such as fixed carbon contained in the coal gangue and the complete decomposition of minerals such as kaolinite contained in the coal gangue within the calciner system.

[0036] The third route connects to the calciner system via an auxiliary residual air duct. A valve is installed on the connecting duct to regulate the amount of residual air entering the calciner system by adjusting the valve opening. A portion of the residual air from the existing firing system enters the calciner system as combustion air and an external heat source, promoting the complete combustion of combustibles such as fixed carbon contained in the gangue and the complete decomposition of minerals such as kaolinite contained in the gangue within the calciner system.

[0037] The flue gas generated by the calcining furnace system passes through the first cooling system of the suspension cooling system at the outlet of the calcining furnace system for gas-solid separation, and then enters the flue gas outlet pipe of the lowest-level cyclone separator of the suspension preheating system of the existing firing system. Subsequently, the raw material powder fed into the existing firing system is preheated and subjected to gas-solid separation multiple times, and finally leaves from the air outlet of the highest-level cyclone preheater of the suspension preheating system of the existing firing system.

[0038] The principle of the present invention is: Considering that gangue often contains a large amount of combustible materials and releases a certain amount of heat at high temperatures, when gangue is used as a raw material for the preparation of metakaolinite, the gangue will burn and release heat in the preheater system, which will lead to problems such as crusting and blockage in the preheater system. In order to ensure the stable operation of the suspension calcination system and controllable product quality, it is necessary to control the combustion and heat release process of the combustible materials in the gangue to occur within the calciner system. According to experimental research, the combustion temperature range of the combustible materials in gangue is generally 350~600℃, and the intense combustion temperature range is generally 450~550℃. Therefore, it is necessary to reasonably design the number of preheater stages, feeding points and flue gas temperature of the suspension preheating system so that all the gangue in the above combustion temperature range, especially the intense combustion temperature range, is located in the calciner.

[0039] Specifically, first, the air temperature of the preheated gangue needs to be reasonably controlled; second, by reasonably designing the number of preheater stages and raw material feeding points, the preheated gangue can enter the calciner in a shorter time, while reducing the heat consumption of the system and avoiding combustion and heat release in the preheater.

[0040] On the other hand, the high-temperature tertiary air (which can be considered as high-temperature air, with a temperature generally of 850~1050℃) and residual air (which can be considered as medium-low temperature air, with a temperature generally of 250~350℃) of the existing cement clinker production line firing system carry a large amount of thermal enthalpy, and the O2 contained in the tertiary air and residual air can be used when the combustibles in the coal gangue are burned; in addition, the high-temperature flue gas generated by the full combustion of combustibles such as fixed carbon contained in the coal gangue and the full decomposition of minerals such as kaolinite contained in the coal gangue in the calciner system carries a large amount of heat and can be used to preheat the raw materials of the existing firing system, thereby reducing the energy consumption of the existing firing system.

[0041] This embodiment fully synergistically couples the gangue activation and calcination system with the existing cement kiln system, utilizing a portion of the high-temperature tertiary air and residual air from the existing cement clinker production line firing system as a heat source for the decomposition of kaolinite in the gangue and as combustion air for the combustion of combustibles in the gangue. The high-temperature flue gas generated by the calciner system is then fed into the existing firing system for heat recovery. Furthermore, this application rationally designs the suspension cooling system so that the flue gas temperature exiting the suspension cooling system and entering the suspension preheating system is lower than the intense combustion temperature range, thus preventing the gangue raw material from burning and releasing heat within the cyclone separator, which can cause system scaling and blockage.

[0042] In order to better understand the above technical solution, the above technical solution will be described in detail below with reference to the accompanying drawings and specific implementation methods.

[0043] Example 1 In this embodiment, gangue raw material containing kaolinite and a certain calorific value first enters a drying and crushing machine, where it is dried and crushed to produce gangue powder particles that meet production requirements. These particles are then fed into a suspension preheating system via a feeding device and a feeding point. The suspension preheating system comprises a cyclone preheater, a high-efficiency spreading device, and connecting pipes. The gangue powder particles undergo preheating and gas-solid separation in the cyclone preheater. After heat exchange and gas-solid separation, the raw meal powder enters the calcining furnace system through the discharge pipe of the cyclone preheater in the suspension preheating system.

[0044] The calcining furnace system includes a high-efficiency material spreading device, a hot air inlet pipe, and a flue gas outlet pipe, etc. Multiple temperature measuring points are layered in the height direction of the calcining furnace to monitor the temperature distribution in the calcining furnace in real time. The temperature distribution in the calcining furnace is controlled within a reasonable range by adjusting the amount of material fed into the calcining furnace system. Reasonable temperature distribution in the calcining furnace can ensure the complete combustion of combustible materials in the gangue and the complete decomposition of kaolinite, while ensuring that the gangue is not overburned and the activity of the finished kaolinite meets the requirements of subsequent production. The heat released by the combustion of the gangue in the calcining furnace system and the heat carried by the hot air entering the calcining furnace system are used to decompose the kaolinite in the gangue. The decomposed hot material leaves the calcining furnace system and then enters the second cooling system of the suspension cooling system after gas-solid separation with the hot flue gas in the first cooling system of the suspension cooling system.

[0045] After the hot material is rapidly cooled and gas-solid separated in the cyclone cooler of the second cooling system of the suspension cooling system, it leaves the discharge pipe of the lowest-level cyclone cooler and falls into the finished product zipper machine, finally obtaining a finished product that meets the requirements.

[0046] In this embodiment, room temperature air enters the cyclone cooler of the second cooling system, and then cools the material. The air that has completed the heat exchange leaves from the outlet of the uppermost cyclone cooler of the second cooling system, and then enters the cyclone preheater of the suspension preheating system to preheat and perform gas-solid separation on the fed coal gangue powder particles, and finally leaves from the outlet of the uppermost cyclone preheater of the suspension preheating system. The waste heat of this air is then recovered and utilized, and finally discharged into the atmosphere after flue gas treatment.

[0047] Part of the high-temperature tertiary air from the existing firing system enters the calciner system through the auxiliary tertiary air duct as combustion-supporting air and external heat source of the calciner system, promoting the complete combustion of combustibles such as fixed carbon contained in the coal gangue and the complete decomposition of minerals such as kaolinite contained in the coal gangue in the calciner system.

[0048] Part of the waste air from the existing firing system enters the calciner system as combustion-supporting air and external heat source of the calciner system, promoting the complete combustion of combustibles such as fixed carbon contained in the gangue and the complete decomposition of minerals such as kaolinite contained in the gangue in the calciner system.

[0049] The flue gas generated enters the flue gas outlet pipe of the lowest-level cyclone separator of the existing firing system after gas-solid separation in the first cooling system of the suspension cooling system at the outlet of the calcining furnace system. Subsequently, the raw material powder fed into the existing firing system is preheated and gas-solid separated multiple times, and finally leaves from the air outlet of the highest-level cyclone preheater of the suspension preheating system of the existing firing system.

[0050] This embodiment combines the composition of coal gangue (mainly kaolinite content) and its own calorific value. The calciner system of this embodiment adopts a reasonable design to achieve stable system operation without the need for external fuel supply. The system heat demand can be met by relying solely on the calorific value of the coal gangue.

[0051] Example 2 On the basis of Example 1, in order to avoid the combustion and heat release of coal gangue in the preheater system, the preferred number of stages of the cyclone preheater of the suspension preheating system is one to two; The preferred number of stages of the cyclone cooler of the second cooling system of the suspension cooling system is two to three; The calcination temperature in the calcination furnace system is preferably 650-1000°C; The residence time of the gas in the calcining furnace system is preferably 2 to 10 seconds; The calorific value of the coal gangue is preferably 300-700 kcal / kg; The inlet air temperature of the suspension preheating system is preferably 300-400°C.

[0052] As the instruction manual Figure 1As shown, the calciner system includes a high-efficiency material spreading device, hot air inlet ducting, and flue gas outlet ducting. The suspended preheating system includes the first cyclone preheater (CC1), a high-efficiency material spreading device, and connecting ducting. The suspended cooling system includes the first cooling system and the second cooling system. The first cooling system includes the second cyclone cooler (CC2), a high-efficiency material spreading device, and connecting ducting. The second cyclone cooler performs both gas-solid separation and primary cooling. The second cooling system includes the third cyclone cooler (CC3) and the fourth cyclone cooler (CC4), a high-efficiency material spreading device, and connecting ducting. The high-temperature material undergoes a small amount of cooling in the second cyclone cooler (CC2), with the main cooling process occurring in the third cyclone cooler (CC3) and the fourth cyclone cooler (CC4).

[0053] The most suitable raw material for this embodiment is coal gangue with low to medium calorific values ​​(the inherent calorific value of coal gangue is considered to be 300-700 kcal / kg). When the coal gangue composition (primarily the kaolinite content) and its inherent calorific value meet a certain mathematical relationship, the heat contained in the coal gangue can meet the heat requirement for kaolinite decomposition in the coal gangue, and the calciner system of this embodiment does not require additional fuel.

[0054] Working process: Gangue raw material containing kaolinite and a certain calorific value first enters the drying and crushing machine, where it is dried and crushed to produce gangue powder particles that meet production needs. The gangue powder particles are then fed through a feeding device and fed into the air inlet pipe of the first cyclone preheater (CC1) of the suspension preheating system. Within the cyclone preheater, the gangue powder particles undergo preheating and gas-solid separation. After heat exchange and gas-solid separation, the gangue raw meal enters the calcining furnace system through the discharge pipe of the first cyclone preheater (CC1) of the suspension preheating system.

[0055] Multiple temperature measuring points are set in layers in the height direction of the calcining furnace to monitor the temperature distribution in the calcining furnace in real time. The temperature distribution in the calcining furnace is controlled within a reasonable range by adjusting the amount of material fed into the calcining furnace system. Reasonable temperature distribution in the calcining furnace can ensure the full combustion of combustibles in the coal gangue and the full decomposition of kaolinite, while ensuring that the coal gangue is not overburned and the activity of the finished kaolinite meets the subsequent production requirements.

[0056] The heat released by the combustion of the gangue within the calciner system and the heat carried by the hot air entering the calciner system decompose the kaolinite in the gangue. The decomposed hot material leaves the calciner system and, after gas-solid separation with the hot flue gas in the second cyclone cooler (CC2), enters the air inlet duct of the third cyclone cooler (CC3) of the suspension cooling system. After rapid cooling and gas-solid separation in the suspension cooling system's cyclones, the hot material exits the discharge pipe of the fourth cyclone cooler (CC4) of the suspension cooling system and falls into the finished zipper machine, ultimately producing the desired finished product.

[0057] Normal temperature air enters the fourth cyclone cooler (CC4) of the suspension cooling system, and then cools the materials entering the suspension cooling system. The air that has completed the heat exchange leaves from the outlet of the third cyclone cooler (CC3) of the suspension cooling system, and then enters the first cyclone preheater (CC1) of the suspension preheating system to preheat and separate the fed coal gangue powder particles into gas and solids. Finally, it leaves from the outlet of the first cyclone preheater (CC1) of the suspension preheating system. The air is then recycled for waste heat and finally discharged into the atmosphere after flue gas treatment.

[0058] Part of the high-temperature tertiary air from the existing firing system enters the calciner system through the auxiliary tertiary air duct as combustion-supporting air and external heat source of the calciner system, promoting the complete combustion of combustibles such as fixed carbon contained in the coal gangue and the complete decomposition of minerals such as kaolinite contained in the coal gangue in the calciner system.

[0059] Part of the waste air from the existing firing system enters the calciner system as combustion-supporting air and external heat source of the calciner system, promoting the complete combustion of combustibles such as fixed carbon contained in the gangue and the complete decomposition of minerals such as kaolinite contained in the gangue in the calciner system.

[0060] The generated flue gas undergoes gas-solid separation in the cyclone separator at the calciner system's outlet and then enters the flue gas outlet duct of the lowest-stage cyclone separator in the existing firing system. It then undergoes multiple rounds of preheating and gas-solid separation on the raw meal fed into the existing firing system before ultimately exiting the outlet of the highest-stage cyclone preheater in the existing firing system's suspension preheating system. This maximizes the recovery and utilization of heat carried by the flue gas. Furthermore, depending on the actual conditions of the existing firing system, the flue gas generated by the calciner system can also enter the flue gas outlet ducts of the cyclone separators at other stages of the existing firing system.

[0061] The technical solutions in the above embodiments of the present application have at least the following technical effects or advantages: This embodiment takes into account the actual needs of processing coal gangue containing combustible substances and controlling the activity of coal gangue activated calcination products, fully considers the actual characteristics of combustible substances in coal gangue, produces highly active kaolinite products, and at the same time solves the problems of crusting and blockage of the preheater system caused by combustion heat release during coal gangue preheating, complex production process flow of the coal gangue suspension calcination production system, high system energy consumption and easy overburning of products. In addition, through the reasonable design of the coal gangue activation calcination process and system, it is possible to achieve the addition of a new suspension calcination system without the need for additional supplementary combustion (after the new suspension calcination system is stably operated) while effectively reducing the energy consumption of the existing cement kiln system.

[0062] This embodiment takes into account that after the high-temperature tertiary air is extracted, the stable operation of the existing firing system will be affected to a certain extent, and the thermal enthalpy of the medium-temperature residual air is difficult to ensure the stable operation of the calciner system. By reasonably designing the extracted high-temperature tertiary air volume and medium-temperature residual air volume, it is ensured that the temperature of the mixed combustion air entering the calciner system is in a reasonable temperature range of 600~800℃ (this temperature range is the optimal temperature range for the full combustion of combustibles in coal gangue), minimizing the impact on the existing firing system as much as possible while ensuring the stable operation of the calciner system (at this time, the high-temperature tertiary air volume extracted by the calciner system can be controlled at a lower value).

[0063] In summary, the present invention provides a gangue activation calcination process and system that are synergistically coupled with a cement kiln system.

[0064] The above embodiments describe the present invention in detail, but the contents described are only preferred embodiments of the present invention and should not be considered to limit the scope of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the scope of the patent coverage of the present invention.

Claims

1. A gangue activation and calcination system synergistically coupled with a cement kiln system, characterized by: The gangue activation calcination system coupled with the cement kiln system includes a calcining furnace system, an auxiliary tertiary air duct and an auxiliary residual air duct. The auxiliary residual air duct is connected to the cooler and the calcining furnace. The two ends of the auxiliary tertiary air duct are connected to the tertiary air duct and the calcining furnace. The two ends of the tertiary air duct are connected to the decomposition furnace and the kiln head of the firing system.

2. The gangue activation and calcination system coupled with a cement kiln system according to claim 1, characterized in that: The gangue activation and calcination system coupled with the cement kiln system also includes a suspension preheating system, which includes one to two-stage cyclone preheaters. The feeding point of the gangue is arranged at the air inlet pipe of the uppermost cyclone preheater. The air outlet pipe of the uppermost cyclone preheater is connected to the flue gas waste heat utilization system, and the discharge pipe of the lowermost cyclone preheater is connected to the calcining furnace.

3. The gangue activation and calcination system coupled with a cement kiln system according to claim 1, characterized in that: The gangue activation and calcination system coupled with the cement kiln system also includes a suspended cooling system, which includes a first cooling system and a second cooling system; the first cooling system includes a first-stage cyclone cooler, the air inlet pipe of the cyclone cooler of the first cooling system is connected to the calcining furnace, the air outlet pipe of the cyclone cooler of the first cooling system is connected to the suspended preheating system of the existing firing system, and the discharge pipe of the cyclone cooler of the first cooling system is connected to the air inlet pipe of the uppermost cyclone cooler of the second cooling system; the second cooling system includes two to three-stage cyclone coolers, the air inlet pipe of the lowermost cyclone cooler of the second cooling system is connected to the cooling air, and the discharge pipe of the lowermost cyclone cooler of the second cooling system is connected to the finished zipper machine.

4. The gangue activation and calcination system coupled with a cement kiln system according to claim 3, characterized in that: The air outlet pipe of the cyclone cooler of the first cooling system is connected to the air outlet pipe of the lowest stage cyclone preheater of the suspension preheating system of the existing firing system.

5. The gangue activation and calcination system synergistically coupled with a cement kiln system according to claim 1, characterized in that: The existing firing system includes a suspension preheating system, a decomposition furnace, a rotary kiln and a cooler connected in sequence. The outlet pipe of the uppermost cyclone preheater of the suspension preheating system of the existing firing system is connected to the waste heat boiler, and the outlet of the waste heat boiler is connected to the raw mill through a high-temperature fan.

6. A gangue activation calcination process synergistically coupled with a cement kiln system, characterized by: The gangue activation calcination process synergistically coupled with the cement kiln system comprises the following steps: Step 1: Extract part of the high-temperature tertiary air and medium-temperature residual air from the existing firing system into the calcining furnace.

7. The gangue activation calcination process coupled with a cement kiln system according to claim 6, characterized in that: The temperature of the high-temperature tertiary air is 850~1050℃, the temperature of the medium-temperature residual air is 250~350℃, and the volume ratio of the high-temperature tertiary air and the medium-temperature residual air entering the calcining furnace is 1:1~1:3, constituting mixed combustion air. The temperature of the mixed combustion air entering the calcining furnace is 600~800℃.

8. The gangue activation calcination process synergistically coupled with a cement kiln system according to claim 6, characterized in that: The gangue activation calcination process synergistically coupled with the cement kiln system comprises the following steps: after gas-solid separation of the flue gas from the calciner, the flue gas enters the suspension preheating system of the existing firing system to preheat the raw material and realize heat recovery and utilization.

9. The gangue activation calcination process synergistically coupled with a cement kiln system according to claim 6, characterized in that: The gangue activation calcination process synergistically coupled with the cement kiln system includes the following steps: the medium-temperature air exiting the suspension cooling system is used to preheat the gangue, and the temperature of the medium-temperature air entering the suspension preheating system is 300-450°C, which is lower than the stable ignition temperature of the combustibles in the gangue.

10. The gangue activation calcination process synergistically coupled with a cement kiln system according to claim 6, characterized in that: The calcination temperature in the calcination furnace is 650-1000°C; The residence time of the gas in the calcining furnace is 2 to 10 seconds; The coal gangue has a calorific value of 300-700 kcal / kg.

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