Process and system for preparing auxiliary cementing material by calcining granular coal gangue coupled with cement clinker sintering system

Abstract

The invention discloses a process and system for preparing an auxiliary cementing material by calcining granular coal gangue coupled with a cement clinker sintering system, and the process comprises the following steps: treating large undisturbed coal gangue to obtain granular coal gangue, and quantitatively analyzing minerals in the granular coal gangue; feeding the granular coal gangue raw material into an activating calcining kiln for activating and calcining; then feeding into a grate cooler for cooling to obtain calcined activated coal gangue; wherein an activation calcination heat source comes from high-temperature section hot air of a grate cooler and hot air at an outlet of a C4 preheater, the proportion of the high-temperature section hot air, the hot air at the outlet of the C4 preheater and combustion-supporting air is controlled, and temperature and oxygen concentration adjustment at the activation calcination stage is achieved. According to the invention, the system for preparing the auxiliary cementing material by calcining the coal gangue is coupled with the original cement clinker sintering system, so that the on-line doping of the auxiliary cementing material in the cement clinker is realized, and meanwhile, the carbon emission is reduced.

Description

Technical Field

[0001] This invention belongs to the field of preparing auxiliary cementitious materials from calcined coal gangue, and particularly relates to a process and system for preparing auxiliary cementitious materials from calcined granular coal gangue coupled with a cement clinker calcination system. Background Technology

[0002] As of 2024, my country's accumulated coal gangue stockpiles exceeded 7 billion tons, with an annual increase of approximately 700-800 million tons, accounting for 10-15% of raw coal production. Long-term stockpiling not only occupies vast amounts of land but also easily leads to spontaneous combustion, releasing harmful gases (such as SO2 and CO), leaching and polluting groundwater, posing a serious threat to the ecological environment. Currently, coal gangue utilization is mainly limited to low-value-added uses such as underground backfilling and land reclamation. Coal gangue contains various minerals including kaolinite, quartz, mica, and calcite. Kaolinite, after activation and calcination, exhibits volcanic ash activity and can be used as a metakaolin-based auxiliary cementitious material added to cement clinker, with an addition ratio reaching 10-30%. However, the decarbonization and color control of coal gangue as an auxiliary cementitious material require addressing these issues. The presence of organic carbon leads to an increase in the amount of concrete water-reducing agents used, and the valence state of Fe affects the color of the auxiliary cementitious material and the cement itself. Therefore, the preparation of auxiliary cementitious materials from calcined coal gangue often suffers from problems such as insufficient calcination, difficulty in color control, and high energy consumption leading to poor product economics.

[0003] Chinese Patent Publication No. CN114524631A discloses a kaolin suspension calcination system based on the modification of a cement clinker calcination system. This technology employs suspension calcination and is primarily suitable for powdered raw materials. Suspension calcination of coal gangue often requires preheating. Because coal gangue itself contains some calorific value, it easily leads to scale buildup and blockage in the preheater, affecting the normal operation of the cement calcination system. Furthermore, the residence time in the suspension calcination process is only a few seconds, often resulting in a low decarburization rate. Chinese Patent Publication No. CN114620958A discloses a process and system for co-activating coal gangue using hot air from a cement kiln. This system uses coal gangue powder as raw material, and through suspension calcination, decomposes kaolinite in the coal gangue powder to form metakaolinite. Then, through uniform activation in a packed state, the activity of the metakaolinite is further enhanced. Finally, it is cooled to form the product. This suspension calcination system is limited by the calorific value of coal gangue, and the packed state calcination method results in uneven heat distribution during calcination, easily leading to surface over-burning and internal under-burning, affecting product activity. Furthermore, this system involves many connected devices, making it complex and requiring significant initial investment. Chinese Patent Publication No. CN118442813A discloses a method and system for coupling coal gangue calcination with cement production. This system mainly targets the calcination of powdered coal gangue. Besides being limited by the calorific value of coal gangue, it requires a separate powder cooling system and does not consider the color of the calcined coal gangue, which can easily affect the color of the finished cement product. Chinese Patent Publication No. CN116462431A discloses a thermal activation calcination process for coal gangue based on a cement calcination system. This process is suitable for the renovation and reuse of existing cement production systems, but it cannot achieve simultaneous calcination of coal gangue and cement production. Furthermore, it does not consider the influence of the valence state of Fe on the color of auxiliary cementitious materials. Chinese Patent Publication No. CN112923719A discloses a system and method for calcining coal gangue using a rotary kiln. When calcined coal gangue is used as an auxiliary cementitious material, it does not consider the color control of the coal gangue.

[0004] In summary, the existing technology has at least the following problems: (1) In the existing suspension calcination technology, when high-calorific-value coal gangue is used to prepare the mixed material, the high calorific value of the coal gangue (>200 kcal / kg) can cause excessively high local temperatures in the preheater system, leading to melting of low-melting-point minerals and liquid-phase adhesion, resulting in thickened crust and obstructed airflow. Therefore, high-calorific-value coal gangue easily causes crusting and blockage in the preheater of the existing suspension calcination process, preventing the system from operating normally. The suspension calcination process of coal gangue has certain limitations on the calorific value of the raw materials.

[0005] (2) In the existing technology, the suspension calcination technology for coal gangue containing calorific value basically adopts the method of 2-3 stage preheating + decomposition furnace to avoid the problem of crusting and blockage. Compared with the existing 5-6 stage preheating + decomposition furnace, this technology has a high preheater outlet temperature and high system heat consumption. The preheater outlet exhaust gas temperature rises from about 260℃ to about 500℃. The exhaust gas temperature is too high, and cold air needs to be mixed in in order to meet the temperature requirements for waste heat power generation.

[0006] (3) Most existing technologies involve calcining powdered coal gangue materials. Therefore, coal gangue requires pretreatment such as grinding. In addition to the need to add relevant grinding equipment, the grinding process increases power consumption, making the production cost of coal gangue auxiliary cementitious materials higher than that of fly ash or slag. Furthermore, after the existing coal gangue suspension calcination is used to prepare auxiliary cementitious materials, they are stored separately. When preparing cement, it is necessary to add a mixing system with powdered materials such as clinker and gypsum. Compared with the common grinding process, this method increases the consumption of manpower and material resources, weakening its market competitiveness.

[0007] (4) Coal gangue typically contains 10-30% carbon, some of which exists in the form of volatile organic carbon (such as aromatics and aliphatic hydrocarbons). If there is insufficient oxygen (O2 < 2%) or the residence time is too short during suspension calcination, carbon particles are easily not fully burned, forming VOCs and causing emissions to exceed standards. In particular, residual carbon will have a significant negative impact on the compatibility of cement and concrete with water-reducing agents, and residual carbon will also pollute the color of the concrete surface.

[0008] In addition, the current coal gangue stockpile is large, occupies a large area, faces the problem of lack of plant sites for stockpiling, and has low added value in the utilization of existing coal gangue. How to utilize the stockpile of coal gangue in large quantities to produce high-performance, low-cost green auxiliary cementitious materials is an important issue. Summary of the Invention

[0009] To address the problems existing in the prior art, this invention provides a process and system for preparing auxiliary cementitious materials from calcined granular coal gangue using a coupled cement clinker calcination system. This invention couples the coal gangue calcination system for preparing auxiliary cementitious materials with the existing cement clinker calcination system. It utilizes the hot air from the cement clinker calcination system and the calorific value of the coal gangue itself as heat sources to ignite and activate the granular coal gangue material during calcination. By adjusting the ratio of hot air and combustion air in the cement clinker calcination system, the O2 concentration during the activation and calcination of the granular coal gangue is regulated, thereby controlling the color of the calcined coal gangue. The flue gas from the coal gangue calcination system enters the decomposition furnace of the cement clinker calcination system. The calcined coal gangue granules are cooled along with the cement clinker in the grate cooler of the cement clinker calcination system before being ground in a cement mill, achieving online addition of auxiliary cementitious materials to the cement clinker. This invention uses calcined granular coal gangue to prepare auxiliary cementitious materials, reducing the need for cement companies to purchase auxiliary cementitious materials, creating economic benefits for enterprises, and reducing carbon emissions at the same time.

[0010] This invention is implemented as follows: a process for preparing auxiliary cementitious materials from calcined granular coal gangue coupled with a cement clinker calcination system, comprising the following steps: Large chunks of raw coal gangue are crushed, screened, and homogenized to obtain granular coal gangue. Quantitative analysis of minerals in the granular coal gangue is then performed. Granular coal gangue raw material is fed into an activated calcining kiln for activation and calcination. During this process, physically adsorbed water is removed from the coal gangue, volatile matter is released and burned, organic carbon components begin to burn, chemical structural water is removed, the mineral structure of the coal gangue undergoes transcrystalline transformation, kaolinite is transformed into active metakaolinite, and the Fe in the coal gangue... 3+ Reduced to Fe 2+ ; The heat source for activation calcination is selected from the high-temperature section hot air of the grate cooler and the hot air at the outlet of the C4 preheater in the cement clinker calcination system. The activation calcination process is achieved by controlling the ratio of the high-temperature section hot air of the grate cooler, the hot air at the outlet of the C4 preheater, and the combustion air to regulate the temperature and oxygen concentration of the activation calcination process. The activated and calcined high-temperature flue gas enters the decomposition furnace of the cement clinker calcination system for combustion support. After activation and calcination, the coal gangue particles are fed into a grate cooler for cooling to obtain calcined and activated coal gangue.

[0011] Preferably, the particle size of the granular coal gangue is 1~20mm.

[0012] Preferably, the interior of the activated calcining kiln consists of a kiln tail feeding zone, a middle calcining zone, and a kiln head discharging zone, arranged sequentially from the kiln tail to the kiln head. The interior of the activated calcining kiln located in both the kiln head discharging zone and the kiln tail feeding zone is provided with spiral protrusions distributed along the axial direction, so that the kiln tail of the activated calcining kiln can be fed uniformly and the kiln head can be discharged uniformly.

[0013] More preferably, the lengths of the spiral protrusions distributed axially in the kiln head discharge zone and the kiln tail feed zone of the activated calcining kiln are 1 / 4 to 1 / 6 of the length of the activated calcining kiln, respectively.

[0014] In a further preferred embodiment, the activated calcining kiln located in the central calcination zone is equipped with multiple L-shaped lifting plates evenly distributed along the circumference. Each L-shaped lifting plate is arranged along the axial direction, so that the coal gangue is lifted to a certain height by the L-shaped lifting plate as the kiln rotates and then falls.

[0015] More preferably, the length of the L-shaped lifting plates installed along the axial direction in the central calcination zone of the activated calcining kiln is the same as the length of the central calcination zone.

[0016] More preferably, the number of L-shaped lifting plates evenly distributed along the circumference in the central calcination zone of the activated calcining kiln is 6 to 12.

[0017] In a further preferred embodiment, the kiln tail feeding zone, the middle calcination zone, and the kiln head discharging zone of the activation calcination kiln rotate independently, and the rotation speed of different parts is controlled to adjust the feeding speed, activation calcination time, and discharging speed.

[0018] Preferably, the temperature during the activation and calcination process is controlled at 700~900℃, the O2 concentration is 2~8%, the activation and calcination time is controlled at 60~120min, and the kiln speed is 1~3r / min.

[0019] Further preferred, when the Fe content in the raw coal gangue is >3%, the O2 concentration during the coal gangue calcination process is maintained at 2-3% by adjusting the ratio of hot air in the high-temperature section of the grate cooler, hot air at the outlet of the C4 preheater, and combustion air, and the calcination time is 90-120 minutes, to achieve slow decarbonization under low oxygen conditions; when the Fe content in the raw coal gangue is <3%, the O2 concentration during the coal gangue calcination process is maintained at 3-8% by adjusting the ratio of hot air in the high-temperature section of the grate cooler, hot air at the outlet of the C4 preheater, and combustion air, and the calcination time is 60-90 minutes, to achieve rapid decarbonization under high oxygen conditions.

[0020] Preferably, the hot air temperature of the high-temperature section of the grate cooler in the cement clinker calcination system is 600~1000℃, and the oxygen concentration is 3~8%; the hot air temperature at the outlet of the C4 preheater is 700~800℃, and the oxygen concentration is 2~3%; the oxygen concentration of the combustion air is about 21%.

[0021] Preferably, calcined activated coal gangue is directly added to cement clinker as an auxiliary cementitious material. The calcined activated coal gangue is evenly spread on top of the cement clinker and enters the cement mill together with the cement clinker for homogenization and grinding. The amount of calcined activated coal gangue added is 10-30% of the amount of raw coal gangue fed into the cement clinker.

[0022] In a further preferred embodiment, when calcined and activated coal gangue is directly incorporated into cement clinker as an auxiliary cementitious material, the amount added is determined based on the kaolinite content in the raw coal gangue: when the kaolinite content in the raw coal gangue is <20%, the amount of raw coal gangue fed is 10% of the amount of cement clinker; when the kaolinite content in the raw coal gangue is 20-40%, the amount of raw coal gangue fed is 20% of the amount of cement clinker; and when the kaolinite content in the raw coal gangue is >40%, the amount of raw coal gangue fed is 30% of the amount of cement clinker.

[0023] A system for preparing auxiliary cementitious materials by calcining granular coal gangue in conjunction with a cement clinker calcination system includes: an existing cement clinker calcination system and a coal gangue calcination system for preparing auxiliary cementitious materials; the existing cement clinker calcination system includes a preheater, a decomposition furnace, a rotary kiln, and a grate cooler connected in sequence. The coal gangue calcination system for preparing auxiliary cementitious materials includes: a coal gangue crushing system, an activation calcination kiln, and a combustion fan; the discharge end of the coal gangue crushing system is connected to the kiln tail of the activation calcination kiln, and the kiln head of the activation calcination kiln is connected to a grate cooler; the air inlet of the kiln head of the activation calcination kiln is connected to the high-temperature air section of the grate cooler, the C4 preheater outlet, and the combustion fan, respectively, and the air outlet of the kiln tail of the activation calcination kiln is connected to the air inlet of the decomposition furnace; valves are installed on the induced draft pipe at the C4 preheater outlet of the cement clinker calcination system, the induced draft pipe at the high-temperature air section of the grate cooler, and the air duct connecting the combustion fan to the middle calcination zone, and all valves are controlled by a gas flow regulation system.

[0024] The advantages and positive effects of this invention are: 1. The heat source of the coal gangue calcination auxiliary cementitious material preparation system of the present invention comes from the cement clinker calcination system, and the calcined coal gangue returns to the cement clinker calcination system, realizing the coupling of the coal gangue calcination auxiliary cementitious material preparation system and the cement clinker calcination system, which can eliminate the generation of secondary pollution and eliminate the need to build a new environmental protection system.

[0025] 2. This invention uses granular coal gangue as raw material. Compared with powdered coal gangue, it reduces the grinding process in the raw material pretreatment and solves the problems of over-burning or under-burning of powdered materials during suspension calcination. The granular coal gangue has a more porous structure after calcination (due to the uniform release of thermal stress), and subsequent grinding to the fineness of cementitious materials (e.g., specific surface area > 400 m²) is possible. 2Energy consumption is lower when the coal gangue is 100% per kilogram; the internal pores and gaps between particles of granular coal gangue are more conducive to uniform heat conduction, avoiding the problem of large density differences in coal gangue powder, which easily leads to local agglomeration or deposition and poor calcination uniformity; granular coal gangue reduces the dust content in flue gas, reduces the load on the dust removal system, reduces airflow disturbance in the calcination furnace, makes the calcination temperature field more stable, and is conducive to the uniform transformation of mineral phases (such as the dehydroxylation of kaolinite to form metakaolinite).

[0026] 3. Compared with the suspension calcination process, the activated calcination kiln calcination process of the present invention allows the granular material to roll with the kiln body in the activated calcination kiln, resulting in a longer heating time (60~120min). This allows organic carbon to be slowly released and completely burned, and the dehydroxylation reaction of minerals such as kaolinite to be more complete, resulting in a higher generation rate of active SiO2 and Al2O3. The rotary kiln can process and calcine high-calorific-value coal gangue, solving the problems of preheater scaling and blockage caused by suspension calcination of high-calorific-value coal gangue.

[0027] 4. This invention innovatively constructs a synergistic induced draft system, which separately draws air from the C4 preheater and the high-temperature section of the grate cooler in the cement clinker calcination system. This effectively reduces the disturbance of single-path induced draft to the original system's thermal regime. Simultaneously, by adjusting the ratio of hot air from the high-temperature section of the grate cooler to the hot air from the C4 preheater outlet and the combustion air, the activation and calcination of coal gangue is achieved. Through precise control of the O2 concentration and calcination time in the activation and calcination kiln, efficient decarbonization and Fe2+ reduction of the coal gangue are realized. 2+ / Fe 3+ The controlled conversion is achieved. At the same time, the activated flue gas after calcination enters the decomposition furnace for secondary calcination, realizing the complete degradation of organic substances such as VOCs and dioxins.

[0028] 5. The activated calcining kiln of this invention is a rotary kiln specifically for granular coal gangue, ensuring uniform feeding and discharging of coal gangue; the coal gangue is lifted to a certain height by the L-shaped baffles as the kiln rotates, improving heat exchange efficiency and solving the problem of incomplete combustion of internal materials caused by the sliding of granular materials along the kiln wall during calcination; the L-shaped baffles can maximize the amount of material lifted compared to ordinary straight baffles and arc-shaped baffles; the activated calcining kiln rotates in three zones, making the feeding speed, calcination time, and discharge speed controllable.

[0029] 6. This invention largely utilizes existing equipment in cement clinker calcination systems. Compared to suspension calcination processes, it requires less new equipment, is simpler, requires less investment, and is easier to promote. Simultaneously, it can utilize coal gangue on a large scale, converting it into auxiliary cementing materials, significantly increasing the added value of coal gangue, and effectively solving the long-standing problem of large-scale coal gangue stockpiling and land occupation, resulting in significant economic and social benefits.

[0030] 7. This invention couples a coal gangue calcination auxiliary cementitious material system with a cement clinker calcination system. The heat source of the cement clinker calcination system is used to calcine the coal gangue. The hot air from the activated calcined coal gangue is returned to the decomposition furnace for combustion support. This achieves the simultaneous reduction of heat consumption in the cement clinker calcination system and the preparation of low-carbon auxiliary cementitious materials from coal gangue, thus solving the VOCs emission problem during the coal gangue calcination process. Therefore, this system has significant social and environmental benefits. Attached Figure Description

[0031] Figure 1 This is a schematic diagram of the calcination system provided in an embodiment of the present invention; Figure 2 This is a longitudinal cross-sectional view of the activation calcination kiln provided in an embodiment of the present invention; Figure 3 This is a cross-sectional view of the activated calcining kiln in the middle calcining zone provided in an embodiment of the present invention; Figure 4 This is a cross-sectional view of the activated calcining kiln at the kiln tail feeding zone or the kiln head discharging zone provided in the embodiments of the present invention.

[0032] In the diagram: 10. Coal gangue calcination system for preparing auxiliary cementitious materials; 101. Coal gangue crushing system; 102. Coal gangue silo; 103. Activated calcining kiln; 1031. Kiln tail feeding zone; 1032. Middle calcining zone; 1033. Kiln head discharging zone; 1034. L-shaped lifting plate; 1035. Spiral raised structure; 104. Combustion fan; 20. Cement clinker calcination system; 201. Preheater; 202. Decomposition furnace; 203. Rotary kiln; 204. Grate cooler. Detailed Implementation The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The described embodiments are only a part of the embodiments of the present invention.

[0033] Please see Figure 1 The present invention provides a process for preparing auxiliary cementitious materials from calcined granular coal gangue coupled with a cement clinker calcination system, comprising the following steps: First, the large, unprocessed coal gangue is crushed, screened, and homogenized to obtain granular coal gangue, which is then loaded into coal gangue silo 102 for later use. Simultaneously, samples are taken to quantitatively analyze the kaolinite mineral and Fe content in the granular coal gangue.

[0034] Then, the granular raw coal gangue from the coal gangue silo 102 is fed into the activation calcination kiln 103 by a quantitative feeding device for activation calcination. The calcination temperature is 700~900℃, the O2 concentration during the calcination process is 2~8%, and the activation calcination time is controlled at 60~120min. During this process, the physically adsorbed water in the coal gangue is removed, volatile matter is released and burned, the organic carbon components in the coal gangue begin to burn, the chemical structural water in the coal gangue is removed, the coal gangue undergoes crystallization, kaolinite is transformed into active metakaolinite, and the Fe in the coal gangue... 3+ Reduced to Fe 2+ ; The heat source for activation calcination is selected from the hot air in the high-temperature section of the grate cooler 204 and the hot air at the outlet of the C4 preheater in the cement clinker calcination system 20. The activation calcination process is achieved by controlling the ratio of the hot air in the high-temperature section of the grate cooler 204, the hot air at the outlet of the C4 preheater, and the combustion air, thereby regulating the temperature and oxygen concentration of the activation calcination process.

[0035] Specifically, the granular raw coal gangue in the coal gangue silo 102 is fed into the activation and calcination kiln 103 by a quantitative feeding device for activation and calcination.

[0036] Granular coal gangue raw material enters the central calcination zone 1032 of the activation calcination kiln 103 for activation calcination. This process removes physically adsorbed water from the coal gangue, causes volatile matter to be released and combusted, initiates the combustion of organic carbon components in the coal gangue, removes chemically structural water from the coal gangue, and causes the coal gangue to undergo crystallization. Kaolinite is transformed into active metakaolinite, and the Fe in the coal gangue... 3+ Reduced to Fe 2+ The specific reaction is shown in the following formula: Al2O3·2SiO2·2H2O→Al2O3·2SiO2+2H2O Fe₂O₃ + CO → 2FeO + CO₂ The heat source for the central calcination zone 1032 is selected from the high-temperature section hot air after the cement clinker is cooled by the grate cooler 204 in the cement clinker calcination system 20, and the hot air from the outlet of the C4 preheater. The temperature and oxygen concentration during the coal gangue calcination process are ensured by adjusting the ratio of the high-temperature section hot air from the grate cooler 204, the hot air from the outlet of the C4 preheater, and the combustion air.

[0037] The high-temperature flue gas from the activated calcining kiln 103, after activating and calcining the coal gangue particles, enters the decomposition furnace 202 of the cement clinker calcination system 20 for combustion support, which can decompose the VOCs generated during the coal gangue calcination process at high temperature.

[0038] Finally, the activated and calcined coal gangue particles are fed into the grate cooler 204 of the cement clinker calcination system 20 for cooling, resulting in calcined and activated coal gangue.

[0039] As a preferred embodiment, the particle size of granular coal gangue is 1~20mm. The internal pores and gaps between particles are more conducive to uniform heat conduction, avoiding the problem that the large density difference of coal gangue powder can easily lead to local agglomeration or deposition and poor calcination uniformity.

[0040] In a preferred embodiment, the activation calcination kiln 103 in the coal gangue calcination auxiliary cementitious material system is a rotary kiln specifically for coal gangue, such as... Figures 2-4 As shown, the interior of the activated calcining kiln 103 of the present invention consists of a kiln tail feeding zone 1031, a middle calcining zone 1032, and a kiln head discharging zone 1033, arranged sequentially from the kiln tail to the kiln head. Both the kiln head discharging zone 1033 and the kiln tail feeding zone 1031 of the activated calcining kiln 103 are provided with spiral protrusions 1035 distributed along the axial direction, which adds a buffer for the kiln tail feeding and the kiln head discharging of the activated calcining kiln 103, and can ensure that the raw coal gangue enters the calcining zone evenly and the calcined coal gangue is discharged evenly into the grate cooler 204 of the cement clinker calcination system 20.

[0041] The activated calcining kiln 103 located in the central calcination zone 1032 is equipped with multiple L-shaped lifting plates 1034 evenly distributed along the circumference. Each L-shaped lifting plate 1034 is arranged along the axial direction. As the kiln rotates, the coal gangue is lifted to a certain height by the L-shaped lifting plate 1034 and then falls, which improves the heat exchange efficiency and solves the problem of incomplete combustion of internal materials caused by the sliding of granular materials along the kiln wall during the calcination process.

[0042] When the loss on ignition of the material is greater than 20%, the carbon content is high, requiring an extended decarburization time. Alternatively, if the Fe content in the coal gangue is high, slow decarburization under low oxygen conditions is necessary. This can be addressed by reducing the rotation speed of the activation calcining kiln 103 and extending the length of the middle calcining zone 1032. The kiln tail feed zone 1031 ensures the stability of the material entering the middle calcining zone 1032, while the kiln head discharge zone 1033 ensures the stability of the material entering the grate cooler 204 after calcination, guaranteeing uniform cooling and maintaining the stability of the amount incorporated into the cement.

[0043] In specific implementation, the lengths of the spiral protrusions 1035 distributed axially in the kiln head discharge zone 1033 and the kiln tail feed zone 1031 of the activated calcining kiln 103 are 1 / 4 to 1 / 6 of the length of the activated calcining kiln 103, respectively. The spiral protrusions 1035 can prevent uneven particle size from causing material to accumulate in the kiln.

[0044] The length of the L-shaped lifting plates 1034 installed along the axial direction in the central calcination zone 1032 of the activated calcining kiln 103 is consistent with the length of the central calcination zone 1032, which fully ensures the uniform calcination of the material after the coal gangue enters the central calcination zone 1032.

[0045] The activated calcining kiln 103 has 6 to 12 L-shaped lifting plates 1034 evenly distributed along the circumference in the central calcination zone 1032. These L-shaped lifting plates 1034 lift and scatter the coal gangue from the kiln bottom, breaking the material's "wall-sliding" state and forming a uniform material curtain. This material curtain increases the contact area between the material and the hot airflow, allowing heat to be quickly transferred to the material's interior, reducing localized overheating or under-calcination. The blocking effect of the L-shaped lifting plates 1034 slows down the axial movement speed of the material within the kiln, ensuring sufficient time for the coal gangue to complete calcination reactions such as dehydration, decarbonization, and mineral phase transformation. This prevents insufficient calcination due to excessively high flow rates, improving the performance stability of auxiliary cementitious materials; inhibiting material agglomeration and wall adhesion, reducing the risk of ring formation within the kiln, and ensuring the continuous and stable operation of the activated calcining kiln 103; and reducing downtime losses due to material return and ring cleaning, indirectly increasing equipment capacity.

[0046] The longer and larger the diameter of the calcining kiln 103, the more L-shaped lifting plates 1034 need to be installed to cover the entire cross-section and prevent local materials from being unable to be thrown; the faster the rotation speed, the faster the axial movement speed of the material, and the more L-shaped lifting plates 1034 need to be installed to extend the residence time; when the rotation speed is slow, the number of L-shaped lifting plates 1034 can be appropriately reduced to avoid material accumulation; the smaller the particle size of the coal gangue, the easier it is to agglomerate, and more L-shaped lifting plates 1034 are needed to enhance the dispersion effect; when high temperature and long-term reaction are required (such as when the mineral phase transformation is complete), more L-shaped lifting plates 1034 need to be installed to extend the residence time.

[0047] In a preferred embodiment, the kiln tail feeding zone 1031, the middle calcination zone 1032, and the kiln head discharging zone 1033 of the activated calcining kiln 103 can be rotated independently. By controlling the rotation speed of different parts, the feeding speed, activation calcination time, and discharging speed can be adjusted to meet the online addition of different proportions of calcined activated coal gangue in cement clinker.

[0048] As a preferred embodiment, the temperature during the activation and calcination process of coal gangue is controlled at 700~900℃, the O2 concentration is 2~8%, the calcination time is controlled at 60~120min, and the kiln speed is 1~3r / min.

[0049] Specifically, the heat sources for the activation and calcination of coal gangue are selected from the high-temperature section hot air after the cement clinker is cooled by the grate cooler 204 in the cement clinker calcination system 20, and the hot air from the outlet of the C4 preheater. The high-temperature section hot air temperature of the grate cooler 204 in the cement clinker calcination system 20 is 600~1000℃, and the oxygen concentration is 3~8%; the hot air temperature at the outlet of the C4 preheater is 700~800℃, and the oxygen concentration is 2~3%; the oxygen concentration of the combustion air is approximately 21%. The activation and calcination process of coal gangue achieves appropriate temperature and oxygen concentration regulation by reasonably controlling the proportions of the above three sets of air, ultimately realizing decarbonization and color control of coal gangue during calcination.

[0050] When the Fe content in the raw coal gangue is >3%, the O2 concentration during the calcination process is maintained at 2-3% by adjusting the ratio of hot air in the high-temperature section of the grate cooler 204, hot air at the outlet of the C4 preheater, and combustion air, and the calcination time is 90-120 minutes, thus achieving slow decarbonization under low oxygen conditions. When the Fe content in the raw coal gangue is <3%, the O2 concentration during the calcination process is maintained at 3-8% by adjusting the ratio of hot air in the high-temperature section of the grate cooler 204, hot air at the outlet of the C4 preheater, and combustion air, and the calcination time is 60-90 minutes, thus achieving rapid decarbonization under high oxygen conditions.

[0051] In a preferred embodiment, calcined and activated coal gangue is directly incorporated into cement clinker as an auxiliary cementitious material. The calcined and activated coal gangue is evenly spread on top of the cement clinker and enters the cement mill together with the cement clinker for homogenization and grinding. Tests show that the activity of the activated and calcined coal gangue is 95-115% after 28 days. The amount of calcined and activated coal gangue incorporated is 10-30% of the raw coal gangue feed weight as cement clinker.

[0052] Specifically, when calcined and activated coal gangue is directly added to cement clinker as an auxiliary cementitious material, the amount added is based on the kaolinite content in the raw coal gangue. That is, the amount of coal gangue fed is determined based on the quantitative analysis results of kaolinite in the raw coal gangue. When the kaolinite content in the raw coal gangue is <20%, the amount of raw coal gangue fed is 10% of the amount of cement clinker; when the kaolinite content in the raw coal gangue is 20-40%, the amount of raw coal gangue fed is 20% of the amount of cement clinker; and when the kaolinite content in the raw coal gangue is >40%, the amount of raw coal gangue fed is 30% of the amount of cement clinker.

[0053] A system for preparing auxiliary cementitious materials by calcining granular coal gangue coupled with a cement clinker calcination system includes: an existing cement clinker calcination system 20 and a coal gangue calcination system for preparing auxiliary cementitious materials 10.

[0054] The existing cement clinker calcination system 20 is a dry-process cement clinker calcination system, mainly consisting of a raw meal silo, preheater 201, decomposition furnace 202, rotary kiln 203, grate cooler 204, clinker silo, and other main equipment such as a dust collector and cement mill, connected in sequence. The production process is as follows: Cement raw meal undergoes gas-solid heat exchange in the preheater 201 and then enters the decomposition furnace 202 for calcination and decomposition. Subsequently, it enters the rotary kiln 203 through the kiln tail flue for sintering to generate high-temperature clinker. The high-temperature clinker is cooled by the grate cooler 204 to obtain cement clinker. The high-temperature air after cooling the high-temperature clinker is used as secondary air in the rotary kiln 203 for combustion support and as tertiary air through the tertiary air duct in the decomposition furnace 202 for combustion support.

[0055] The coal gangue calcination auxiliary cementitious material preparation system 10 mainly includes: a coal gangue crushing system 101, a coal gangue silo 102, a feeding device, a gas flow regulation system, an activation calcination kiln 103, a combustion fan 104, and a material conveying system. The discharge end of the coal gangue crushing system 101 is connected to the coal gangue silo 102. The discharge end of the coal gangue silo 102 is connected to the kiln tail inlet of the activation calcination kiln 103 through the feeding device. The kiln head outlet of the activation calcination kiln 103 is connected to a grate cooler 204. The discharge end of the grate cooler 204 is connected to a cement mill. The kiln head air inlet of the activated calcining kiln 103 is connected to the high-temperature air section of the grate cooler 204, the C4 preheater outlet, and the combustion blower 104, respectively. The kiln tail air outlet of the activated calcining kiln 103 is connected to the air inlet of the decomposition furnace 202. Valves are installed on the induced draft pipe of the C4 preheater outlet of the cement clinker calcining system 20, the induced draft pipe of the high-temperature air section of the grate cooler 204, and the air pipe of the combustion blower 104 connected to the kiln head of the activated calcining kiln 103. All valves are controlled by the gas flow regulation system.

[0056] The main production process is as follows: large pieces of raw coal gangue are crushed to 1~20mm by the coal gangue crushing system 101 and then transported to the coal gangue silo 102. The raw coal gangue after exiting the coal gangue silo 102 enters the kiln from the kiln tail of the activation calcination kiln 103 for activation calcination. The activated and calcined coal gangue is transported to the grate cooler 204 of the cement clinker calcination system 20 by the material conveying system and cooled with the clinker. The calcined and activated coal gangue obtained after cooling is used as an auxiliary cementing material and sent to the mill for homogenization and grinding with the cement clinker.

[0057] The hot air for the coal gangue calcination auxiliary cementitious material preparation system 10 is taken from the C4 preheater outlet and the high-temperature air section of the grate cooler 204 of the cement clinker calcination system 20. The combustion air for the coal gangue calcination auxiliary cementitious material preparation system 10 is taken from the self-combustion blower 104. The combustion hot air and combustion air enter the kiln from the kiln head of the activated calcination kiln 103, and the hot air from the kiln tail returns to the decomposition furnace 202 of the cement calcination system for combustion.

[0058] To better understand the above embodiments of the present invention, the present invention will be further described in detail below.

[0059] Example 1 Please see Figure 1 The present invention provides a process for preparing auxiliary cementitious materials from calcined coal gangue coupled to a cement clinker calcination system, comprising the following steps: First, the large, unprocessed coal gangue is crushed, screened, and homogenized to obtain 1-20mm granular coal gangue, which is then loaded into coal gangue silo 102 for later use. Simultaneously, samples are taken to quantitatively analyze the kaolinite mineral and Fe content in the granular coal gangue. The kaolinite content is 18%, and the Fe content is 3.8%.

[0060] The amount of granular coal gangue raw meal fed is 10% of the cement clinker production.

[0061] The raw coal gangue in the coal gangue silo 102 is fed into the activation calcination kiln 103 by a quantitative feeding device for activation calcination. The calcination temperature is 700~900℃, the O2 concentration during the calcination process is 2~3%, and the calcination time is controlled at 90~120 minutes. During this process, physically adsorbed water is removed from the coal gangue, volatile matter is released and combusted, the organic carbon components in the coal gangue begin to burn, the chemical structural water in the coal gangue is removed, the coal gangue undergoes crystallization, kaolinite is transformed into active metakaolinite, and the Fe in the coal gangue... 3+ Reduced to Fe 2+ .

[0062] The hot air for coal gangue activation and calcination is selected from the high-temperature section of the grate cooler 204 in the cement clinker calcination system 20 and the hot air from the outlet of the C4 preheater. The high-temperature section of the grate cooler 204 in the cement clinker calcination system 20 has a temperature of 600~1000℃ and an oxygen concentration of 3~8%. The hot air from the outlet of the C4 preheater has a temperature of 700~800℃ and an oxygen concentration of 2~3%. The oxygen concentration of the combustion air is about 21%. By reasonably controlling the proportion of the above three sets of air, the appropriate temperature and oxygen concentration of the coal gangue activation and calcination process can be adjusted, and the decarbonization and color control of the coal gangue calcination can be achieved.

[0063] The activated and calcined coal gangue particles are fed into a grate cooler 204 and evenly spread on top of the cement clinker. After cooling, the calcined and activated coal gangue is obtained. It is then used as an auxiliary cementitious material and fed into a cement mill along with the cement clinker for homogenization and grinding. The activity of the calcined coal gangue after 28 days was measured to be 100-105%.

[0064] The high-temperature flue gas from the calcination of coal gangue granules in the activated calcining kiln 103 enters the decomposition furnace 202 of the cement clinker calcination system 20, which can decompose the VOCs generated during the calcination of coal gangue at high temperature.

[0065] The cement before and after incorporation of calcined activated coal gangue was tested, as shown in Table 1 below: Table 1. Compressive strength data of cement specimens at different ages before and after incorporation of calcined activated coal gangue.

[0066] Example 2 Please see Figure 1 The present invention provides a process for preparing auxiliary cementitious materials from calcined coal gangue coupled to a cement clinker calcination system, comprising the following steps: First, the large, unprocessed coal gangue is crushed, screened, and homogenized to obtain 1-20mm granular coal gangue, which is then loaded into coal gangue silo 102 for later use. Simultaneously, samples are taken for quantitative analysis of the kaolinite mineral and Fe content in the granular coal gangue. The kaolinite content is 38%, and the Fe content is 2%.

[0067] The amount of granular coal gangue raw meal fed is 20% of the cement clinker production.

[0068] The raw coal gangue in the coal gangue silo 102 is fed into the activation calcination kiln 103 by a quantitative feeding device for activation calcination. The calcination temperature is 700~900℃, the O2 concentration during the calcination process is 3~5%, and the calcination time is controlled at 70~80 minutes. During this process, physically adsorbed water is removed from the coal gangue, volatile matter is released and combusted, the organic carbon components in the coal gangue begin to burn, the chemical structural water in the coal gangue is removed, the coal gangue undergoes crystallization, kaolinite is transformed into active metakaolinite, and the Fe in the coal gangue... 3+ Reduced to Fe 2+ .

[0069] The hot air for coal gangue activation and calcination is selected from the high-temperature section of the grate cooler 204 in the cement clinker calcination system 20 and the hot air from the outlet of the C4 preheater. The high-temperature section of the grate cooler 204 in the cement clinker calcination system 20 has a temperature of 600~1000℃ and an oxygen concentration of 3~8%. The hot air from the outlet of the C4 preheater has a temperature of 700~800℃ and an oxygen concentration of 2~3%. The oxygen concentration of the combustion air is about 21%. By reasonably controlling the proportion of the above three sets of air, the appropriate temperature and oxygen concentration of the coal gangue activation and calcination process can be adjusted, and the decarbonization and color control of the coal gangue calcination can be achieved.

[0070] The activated and calcined coal gangue particles are fed into a grate cooler 204 and evenly spread on top of the cement clinker. After cooling, the calcined and activated coal gangue is obtained. It is then used as an auxiliary cementitious material and fed into a cement mill along with the cement clinker for homogenization and grinding. It has been determined that the activity of the calcined coal gangue is 100-105% after 28 days.

[0071] The high-temperature flue gas from the calcination of coal gangue granules in the activated calcining kiln 103 enters the decomposition furnace 202 of the cement clinker calcination system 20, which can decompose the VOCs generated during the calcination of coal gangue at high temperature.

[0072] The cement before and after incorporation of calcined activated coal gangue was tested, as shown in Table 2 below: Table 2. Compressive strength data of cement specimens at different ages before and after incorporation of calcined activated coal gangue.

[0073] Example 3 Please see Figure 1The present invention provides a process for preparing auxiliary cementitious materials from calcined coal gangue coupled to a cement clinker calcination system, comprising the following steps: First, the large, unprocessed coal gangue is crushed, screened, and homogenized to obtain 1-20mm granular coal gangue, which is then loaded into coal gangue silo 102 for later use. Simultaneously, samples are taken for quantitative analysis of the kaolinite mineral and Fe content in the granular coal gangue. The kaolinite content is 48%, and the Fe content is 1%.

[0074] The amount of granular coal gangue raw meal fed is 30% of the cement clinker production.

[0075] The raw coal gangue in the coal gangue silo 102 is fed into the activation calcination kiln 103 by a quantitative feeding device for activation calcination. The calcination temperature is 700~900℃, the O2 concentration during the calcination process is 5~8%, and the calcination time is controlled at 60~70 minutes. During this process, physically adsorbed water is removed from the coal gangue, volatile matter is released and combusted, the organic carbon components in the coal gangue begin to burn, the chemical structural water in the coal gangue is removed, the coal gangue undergoes crystallization, kaolinite is transformed into active metakaolinite, and the Fe in the coal gangue... 3+ Reduced to Fe 2+ .

[0076] The hot air for coal gangue activation and calcination is selected from the high-temperature section of the grate cooler 204 in the cement clinker calcination system 20 and the hot air from the outlet of the C4 preheater. The high-temperature section of the grate cooler 204 in the cement clinker calcination system 20 has a temperature of 600~1000℃ and an oxygen concentration of 3~8%. The hot air from the outlet of the C4 preheater has a temperature of 700~800℃ and an oxygen concentration of 2~3%. The oxygen concentration of the combustion air is about 21%. By reasonably controlling the proportion of the above three sets of air, the appropriate temperature and oxygen concentration of the coal gangue activation and calcination process can be adjusted, and the decarbonization and color control of the coal gangue calcination can be achieved.

[0077] The activated and calcined coal gangue particles are fed into a grate cooler 204 and evenly spread on top of the cement clinker. After cooling, the calcined and activated coal gangue is obtained. It is then used as an auxiliary cementitious material and fed into a cement mill along with the cement clinker for homogenization and grinding. The activity of the calcined coal gangue after 28 days was measured to be 100-105%.

[0078] The high-temperature flue gas from the calcination of coal gangue granules in the activated calcining kiln 103 enters the decomposition furnace 202 of the cement clinker calcination system 20, which can decompose the VOCs generated during the calcination of coal gangue at high temperature.

[0079] The cement before and after incorporation of calcined activated coal gangue was tested, as shown in Table 3 below: Table 3. Compressive strength data of cement specimens at different ages before and after incorporation of calcined activated coal gangue.

[0080] In summary, this invention couples a cement clinker calcination system with a coal gangue calcination system, providing a novel process for preparing highly active auxiliary cementitious materials from coal gangue calcination. The proportion of auxiliary cementitious materials incorporated into cement is determined by the kaolinite content, enabling the online addition of auxiliary cementitious materials to cement. This process is applicable to coal gangue with varying kaolinite contents without affecting cement performance. The hot air from the coal gangue calcination system is returned to the cement clinker calcination system, achieving high-temperature calcination of volatile substances such as VOCs, avoiding the environmental and safety issues associated with direct entry into the exhaust gas treatment system. Furthermore, this invention allows for color control of the auxiliary cementitious materials prepared from high-iron-content coal gangue after calcination, reducing the impact of the auxiliary cementitious materials on cement color after incorporation.

[0081] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A process for preparing auxiliary cementitious materials from calcined granular coal gangue coupled with a cement clinker calcination system, characterized in that, Includes the following steps: Large chunks of raw coal gangue are crushed, screened, and homogenized to obtain granular coal gangue. Quantitative analysis of minerals in the granular coal gangue is then performed. Granular coal gangue raw material is fed into an activated calcining kiln for activation and calcination. During this process, physically adsorbed water is removed from the coal gangue, volatile matter is released and burned, organic carbon components begin to burn, chemical structural water is removed, the mineral structure of the coal gangue undergoes transcrystalline transformation, kaolinite is transformed into active metakaolinite, and the Fe in the coal gangue... 3+ Reduced to Fe 2+ ; The heat source for activation calcination is selected from the high-temperature section hot air of the grate cooler and the hot air at the outlet of the C4 preheater in the cement clinker calcination system. The activation calcination process is achieved by controlling the ratio of the high-temperature section hot air of the grate cooler, the hot air at the outlet of the C4 preheater, and the combustion air to regulate the temperature and oxygen concentration of the activation calcination process. The activated and calcined high-temperature flue gas enters the decomposition furnace of the cement clinker calcination system for combustion support. After activation and calcination, the coal gangue particles are fed into a grate cooler for cooling to obtain calcined and activated coal gangue.

2. The process for preparing auxiliary cementitious materials from calcined granular coal gangue in a coupled cement clinker calcination system according to claim 1, characterized in that, The particle size of the granular coal gangue is 1~20mm.

3. The process for preparing auxiliary cementitious materials from calcined granular coal gangue in a coupled cement clinker calcination system according to claim 1, characterized in that, The interior of the activated calcining kiln consists of a kiln tail feeding zone, a middle calcining zone, and a kiln head discharging zone, arranged sequentially from the kiln tail to the kiln head. The interior of the activated calcining kiln located in both the kiln head discharging zone and the kiln tail feeding zone is equipped with spiral protrusions distributed along the axial direction, so that the kiln tail of the activated calcining kiln can be fed evenly and the kiln head can be discharged evenly.

4. The process for preparing auxiliary cementitious materials from calcined granular coal gangue in a coupled cement clinker calcination system according to claim 3, characterized in that, The lengths of the spiral protrusions distributed axially in the kiln head discharge zone and the kiln tail feed zone of the activated calcining kiln are 1 / 4 to 1 / 6 of the length of the activated calcining kiln, respectively.

5. The process for preparing auxiliary cementitious materials from calcined granular coal gangue in a coupled cement clinker calcination system according to claim 3, characterized in that, The activated calcining kiln located in the central calcination zone is equipped with multiple L-shaped lifting plates evenly distributed along the circumference. Each L-shaped lifting plate is arranged axially, so that the coal gangue is lifted to a certain height by the L-shaped lifting plate as the kiln rotates and then falls.

6. The process for preparing auxiliary cementitious materials from calcined granular coal gangue in a coupled cement clinker calcination system according to claim 5, characterized in that, The length of the L-shaped lifting plates installed along the axial direction in the central calcination zone of the activated calcining kiln is the same as the length of the central calcination zone.

7. The process for preparing auxiliary cementitious materials from calcined granular coal gangue in a coupled cement clinker calcination system according to claim 5, characterized in that, The number of L-shaped lifting plates evenly distributed along the circumference in the central calcination zone of the activated calcining kiln is 6 to 12.

8. The process for preparing auxiliary cementitious materials from calcined granular coal gangue in a coupled cement clinker calcination system according to claim 1, characterized in that, The kiln tail feeding zone, the middle calcination zone, and the kiln head discharging zone of the activated calcining kiln rotate independently, and the rotation speed of different parts is controlled to adjust the feeding speed, activation and calcination time, and discharging speed.

9. The process for preparing auxiliary cementitious materials from calcined granular coal gangue in a coupled cement clinker calcination system according to claim 1, characterized in that, The temperature during the activation and calcination process is controlled at 700~900℃, the O2 concentration is 2~8%, the activation and calcination time is controlled at 60~120min, and the kiln speed is 1~3r / min.

10. The process for preparing auxiliary cementitious materials from calcined granular coal gangue in a coupled cement clinker calcination system according to claim 9, characterized in that, When the Fe content in the raw coal gangue is >3%, the O2 concentration during the calcination process is maintained at 2-3% by adjusting the ratio of hot air in the high-temperature section of the grate cooler, hot air at the outlet of the C4 preheater, and combustion air, and the calcination time is 90-120 minutes, thus achieving slow decarbonization under low oxygen conditions. When the Fe content in the raw coal gangue is <3%, the O2 concentration during the calcination process is maintained at 3-8% by adjusting the ratio of hot air in the high-temperature section of the grate cooler, hot air at the outlet of the C4 preheater, and combustion air, and the calcination time is 60-90 minutes, thus achieving rapid decarbonization under high oxygen conditions.

11. The process for preparing auxiliary cementitious materials from calcined granular coal gangue in a coupled cement clinker calcination system according to claim 1, characterized in that, In the cement clinker calcination system, the hot air temperature in the high-temperature section of the grate cooler is 600~1000℃, and the oxygen concentration is 3~8%; the hot air temperature at the outlet of the C4 preheater is 700~800℃, and the oxygen concentration is 2~3%; the oxygen concentration of the combustion air is about 21%.

12. The process for preparing auxiliary cementitious materials from calcined granular coal gangue in a coupled cement clinker calcination system according to claim 1, characterized in that, Calcined and activated coal gangue is directly added to cement clinker as an auxiliary cementitious material. The calcined and activated coal gangue is evenly spread on top of the cement clinker and enters the cement mill together with the cement clinker for homogenization and grinding. The amount of calcined and activated coal gangue added is 10-30% of the amount of raw coal gangue fed into the cement clinker.

13. The process for preparing auxiliary cementitious materials from calcined granular coal gangue in a coupled cement clinker calcination system according to claim 12, characterized in that, When calcined and activated coal gangue is directly added to cement clinker as an auxiliary cementitious material, the amount added is determined based on the kaolinite content in the raw coal gangue: when the kaolinite content in the raw coal gangue is <20%, the amount of raw coal gangue fed is 10% of the amount of cement clinker; when the kaolinite content in the raw coal gangue is 20-40%, the amount of raw coal gangue fed is 20% of the amount of cement clinker; and when the kaolinite content in the raw coal gangue is >40%, the amount of raw coal gangue fed is 30% of the amount of cement clinker.

14. A system for preparing auxiliary cementitious materials by calcining granular coal gangue in a coupled cement clinker calcination system, used to implement the calcination process according to any one of claims 1-13, characterized in that, include: The original cement clinker calcination system and coal gangue calcination system for preparing auxiliary cementitious materials; The original cement clinker calcination system included a preheater, a decomposition furnace, a rotary kiln, and a grate cooler connected in sequence; The coal gangue calcination system for preparing auxiliary cementitious materials includes: a coal gangue crushing system, an activated calcination kiln, and a combustion-supporting blower; The discharge end of the coal gangue crushing system is connected to the kiln tail of the activated calcining kiln, and the kiln head of the activated calcining kiln is connected to the grate cooler. The air inlet of the kiln head of the activated calcining kiln is connected to the high-temperature air section of the grate cooler, the outlet of the C4 preheater, and the combustion air fan, respectively. The air outlet of the kiln tail of the activated calcining kiln is connected to the air inlet of the decomposition furnace. Valves are installed on the air duct at the outlet of the C4 preheater of the cement clinker calcining system, the air duct at the high-temperature air section of the grate cooler, and the air duct connecting the combustion air fan to the middle calcination zone. All valves are controlled by a gas flow regulation system.

Images