Belt type roasting granular coal gangue calcining process and system coupled with cement clinker firing system

Abstract

The invention discloses a belt-type roasting granular coal gangue calcining process and system coupled with a cement clinker firing system, and the process comprises the following steps: treating large undisturbed coal gangue to obtain granular coal gangue, and carrying out quantitative analysis on minerals in the granular coal gangue; feeding the granular coal gangue raw material into a belt type roasting machine, and sequentially preheating, drying, activating, calcining and regulating and controlling the color; then feeding into a cooling machine of a system for preparing the auxiliary cementing material by calcining the coal gangue, and cooling to obtain calcined activated coal gangue; wherein a preheating and drying heat source comes from hot air of a cooling machine; an activating and calcining heat source comes from high-temperature section hot air of a grate cooler in a cement clinker sintering system, the proportion of the high-temperature section hot air to combustion-supporting air is controlled, and temperature and oxygen concentration adjustment in the activating and calcining stage is achieved; and the color regulation heat source is hot air from an outlet of the C4 preheater. 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 technical field of auxiliary cementitious materials preparation from calcined coal gangue, and particularly relates to a belt-type roasting process and system for calcining 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, it further enhances the activity of the metakaolinite through uniform activation in a packed state, and finally cools 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 quality. 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. In addition, it does not consider the influence of the valence state of Fe on the color of auxiliary cementitious materials.

[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 belt-type calcination process and system for granular coal gangue coupled with a 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 during calcination. O2 concentration is adjusted during the activation calcination and color control processes by regulating the hot air flow and combustion air volume of the cement clinker calcination system. The high-temperature flue gas after activation calcination and color control enters the decomposition furnace of the cement clinker calcination system, while the flue gas after preheating and drying the granular coal gangue enters the low-temperature section of the grate cooler in the cement clinker calcination system. The color-controlled coal gangue granules are cooled in the cooler of the coal gangue calcination system for preparing auxiliary cementitious materials, and then co-ground with cement 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 belt-type calcination process for 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 a belt roaster for sequential preheating and drying, activation calcination, and color control. Preheating and drying removes physically adsorbed water from the coal gangue. Activation calcination causes volatile matter to be released, organic carbon components to begin combustion, chemical structural water to be removed, and the mineral structure of the coal gangue undergoes transformation, converting kaolinite into active metakaolinite. Color control reduces the Fe content in the coal gangue. 3+ Reduced to Fe 2+ ; Color-controlled coal gangue granules are fed into a cooler in a coal gangue calcination auxiliary cementitious material preparation system to obtain calcined activated coal gangue. The heat source for preheating and drying comes from the hot air after the cooling machine cools the calcined and activated coal gangue; the heat source for activation and calcination comes from the high-temperature section of the grate cooler in the cement clinker calcination system. During the activation and calcination stage, the temperature and oxygen concentration are adjusted by controlling the ratio of the high-temperature section hot air and combustion air in the grate cooler; the heat source for color control comes from the hot air at the outlet of the C4 preheater in the cement clinker calcination system. The preheated and dried hot air enters the grate cooler of the cement clinker calcination system to cool and reduce the temperature of the cement clinker; the high-temperature flue gas after activation calcination and color control enters the decomposition furnace of the cement clinker calcination system for combustion support.

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

[0012] Preferably, the belt roaster is internally divided into a preheating and drying zone, a high-oxygen activation and calcination zone, and a low-oxygen color control zone, which are connected in sequence. These zones are used to preheat and dry the coal gangue, activate and calcinate it, and control its color, respectively. Each zone has at least one level of conveyor belt. Each zone has a material distribution device and an exhaust fan at the top and an air intake homogenization device at the bottom. A flap valve is provided between two interconnected zones.

[0013] Preferably, when the loss on ignition of the raw coal gangue is >20%, the rotation speed of the conveyor belt in the high-oxygen activation and calcination zone of the belt roaster is adjusted so that the activation and calcination time is 90~120min; when the loss on ignition of the raw coal gangue is <20%, the rotation speed of the conveyor belt in the high-oxygen activation and calcination zone of the belt roaster is adjusted so that the activation and calcination time is 60~90min.

[0014] Preferably, when the Fe content in the raw coal gangue is >3%, the rotation speed of the conveyor belt in the low-oxygen color control zone of the belt roaster is adjusted so that the color control time is 60~90min; when the Fe content in the raw coal gangue is <3%, the rotation speed of the conveyor belt in the low-oxygen color control zone of the belt roaster is adjusted so that the color control time is 30~60min.

[0015] Preferably, in the auxiliary cementitious material preparation system for coal gangue calcination, the hot air temperature after the calcined coal gangue is cooled by the cooler is 200~400℃, the temperature of the preheated and dried coal gangue is 200~300℃, and the moisture content is <2%.

[0016] Preferably, the hot air temperature in 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 excess air coefficient in the activation and calcination process is 1~1.5, and the activation and calcination time is 60~120min.

[0017] Preferably, the hot air temperature at the outlet of the C4 preheater in the cement clinker calcination system is 700~800℃, and the oxygen concentration is 2~3%; the excess air coefficient in the color control process is 0.5~1.0, and the color control time is controlled at 30~90min.

[0018] Preferably, the activity of calcined activated coal gangue is 95-115% after 28 days. Calcined activated coal gangue is directly added to cement clinker as an auxiliary cementitious material 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.

[0019] In a further preferred embodiment, when calcined and activated coal gangue is directly incorporated into cement clinker as an auxiliary cementitious material, the amount incorporated is determined based on the kaolinite content in the raw coal gangue: when the kaolinite content in the raw coal gangue is <20%, the feed amount of raw coal gangue in the belt roaster is 10% of the cement clinker; when the kaolinite content in the raw coal gangue is 20-40%, the feed amount of raw coal gangue in the belt roaster is 20% of the cement clinker; and when the kaolinite content in the raw coal gangue is >40%, the feed amount of raw coal gangue in the belt roaster is 30% of the cement clinker.

[0020] A belt-type calcining system for granular coal gangue coupled 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, a belt roaster, a combustion fan, a cooler, and a cold air fan. The discharge end of the coal gangue crushing system is connected to the feed end of the belt roaster, the discharge end of the belt roaster is connected to the cooler, and the discharge end of the cooler is connected to a cement mill. The air inlet of the cooler is connected to the cold air fan, the air outlet of the cooler is connected to the air inlet of the preheating and drying zone of the belt roaster, and the outlet duct of the preheating and drying zone of the belt roaster is connected to the low-temperature air section of the grate cooler. The air inlet of the high-oxygen activation calcination zone is connected to the high-temperature air section of the grate cooler and the combustion blower. The air inlet of the low-oxygen color control zone of the belt roaster is connected to the outlet of the C4 preheater. The air outlets of the high-oxygen activation calcination zone and the low-oxygen color control zone of the belt roaster are both connected to the air inlet of the decomposition furnace. Valves are installed on the exhaust pipe of the C4 preheater outlet of the cement clinker calcination system, the exhaust pipe of the high-temperature air section of the grate cooler, and the air pipe connecting the combustion blower to the air inlet of the high-oxygen activation calcination zone. All valves are controlled by the gas flow regulation system.

[0021] 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.

[0022] 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. 2 Energy consumption is lower when the coal gangue is 1.5 kg / kg; 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 can easily lead 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).

[0023] 3. Compared with the suspension calcination process, the belt roasting process of this invention allows for longer heating time for granular coal gangue raw materials during preheating, drying, activation calcination, and color control in the belt roaster. This results in the slow release and complete combustion of organic carbon, thorough dehydroxylation of minerals such as kaolin, and high formation rates of active SiO2 and Al2O3. The calcined coal gangue does not affect the color of the cement. The belt roaster can process high-calorific-value coal gangue, solving problems such as preheater scaling and blockage caused by suspension calcination of high-calorific-value coal gangue.

[0024] 4. This invention innovatively constructs a synergistic induced draft system, drawing separate drafts from the C4 preheater and the high-temperature section of the grate cooler in the cement clinker calcination system, effectively reducing the disturbance of single-path drafts to the original system's thermal regime. By precisely controlling the excess air coefficient and calcination time in the high-oxygen activation calcination zone and the low-oxygen color control zone of the belt roaster, the activation calcination, decarbonization, and Fe production of coal gangue are achieved. 2+ / Fe 3+ The controlled conversion is achieved. Simultaneously, the flue gas after activation, calcination, and color adjustment enters the decomposition furnace for secondary calcination, realizing the complete degradation of organic substances such as VOCs and dioxins.

[0025] 5. This invention relates to a belt roaster specifically designed for granular coal gangue. The internal partitioning of the roaster allows for preheating, drying, activation calcination, and color control of the coal gangue. The belt roaster is divided into three zones: a preheating and drying zone, a high-oxygen activation calcination zone, and a low-oxygen color control zone. Material transfer within these zones is achieved through double-layer flap valves, reducing fluctuations in gaseous components. The preheating and drying zone preheats and dries the coal gangue, reducing temperature fluctuations caused by high moisture content when the material enters the calcination belt, stabilizing the calcination temperature, optimizing the calcination process, and improving product quality. The high-oxygen activation calcination zone uses a two-stage conveyor belt, extending the calcination time and material layer thickness, which is beneficial for the activation of active components in the coal gangue. The high-oxygen atmosphere enables rapid decarbonization of the coal gangue. The low-oxygen color control zone can control the Fe generated in the high-oxygen activation calcination zone. 3+ Reduced to Fe 2+ This allows for controllable color of calcined coal gangue, while a low-oxygen atmosphere can slowly remove residual carbon, improving the decarbonization rate of coal gangue and increasing the stability of cement.

[0026] 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. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the calcination system provided in an embodiment of the present invention; Figure 2 This is a schematic diagram of the belt roaster provided in an embodiment of the present invention.

[0028] In the diagram: 10. Coal gangue calcination system for preparing auxiliary cementitious materials; 101. Coal gangue crushing system; 102. Coal gangue silo; 103. Belt roaster; 1031. Preheating and drying zone; 1032. High-oxygen activation calcination zone; 1033. Low-oxygen color control zone; 1034. Flip valve; 104. Cooler; 105. Air cooler; 106. 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.

[0029] Please see Figure 1 The present invention provides a belt-type roasting coal gangue calcination process coupled to a cement clinker calcination system, comprising the following steps: First, the large pieces of raw coal gangue are crushed, screened, and homogenized to obtain granular coal gangue, which is then loaded into coal gangue silo 102 for later use. At the same time, quantitative analysis of minerals in the granular coal gangue is performed, including analysis of kaolinite mineral, Fe content, and loss on ignition.

[0030] Then, the granular coal gangue raw material is fed into the belt roaster 103 by a quantitative feeding device for preheating and drying, activation calcination, and color control in sequence. Preheating and drying removes physically adsorbed water from the coal gangue; activation calcination causes volatile matter to be released from the coal gangue, organic carbon components to begin combustion, chemical structural water to be removed, and the mineral structure of the coal gangue to undergo transcrystalline transformation, converting kaolinite into active metakaolinite; color control reduces Fe content in the coal gangue. 3+ Reduced to Fe 2+ ; The heat source for preheating and drying comes from the hot air cooled by the cooler 104 in the coal gangue calcination auxiliary cementitious material preparation system 10 after calcining and activating the coal gangue; the heat source for activation and calcination comes from the high-temperature section hot air cooled by the grate cooler 204 in the cement clinker calcination system 20. During the activation and calcination stage, the temperature and oxygen concentration are adjusted by controlling the ratio of high-temperature section hot air and combustion air in the grate cooler 204; the heat source for color control comes from the hot air at the outlet of the C4 preheater in the cement clinker calcination system 20. The preheated and dried hot air enters the grate cooler 204 of the cement clinker calcination system 20 to cool and reduce the temperature of the cement clinker; the high-temperature flue gas after activation calcination and color control enters the decomposition furnace of the cement clinker calcination system 20 for combustion support.

[0031] Specifically, the granular raw coal gangue in the coal gangue silo 102102 is fed into the belt roaster 103 by a quantitative feeding device for preheating, drying, activation calcination and color control.

[0032] The granular coal gangue raw material first enters the preheating and drying zone 1031 of the belt roaster 103 for physical adsorption and water removal.

[0033] After preheating and drying, the coal gangue enters the high-oxygen activation calcination zone 1032 of the belt roaster 103 for high-oxygen activation calcination, which causes the volatile matter in the coal gangue to be released, the organic carbon components to start burning, the chemical structural water to be removed, and the mineral structure of the coal gangue to undergo crystallization, and kaolinite to be transformed into active metakaolinite. The specific reaction is shown in the following formula. Al2O3·2SiO2·2H2O→Al2O3·2SiO2+2H2O After activation and calcination, the coal gangue enters the low-oxygen color control zone 1033 of the belt roaster 103 for low-oxygen color control, thereby reducing the Fe content in the coal gangue. 3+ Reduced to Fe 2+ The specific reaction is shown in the following formula: Fe₂O₃ + CO → 2FeO + CO₂ The hot air for preheating and drying granular coal gangue comes from the hot air cooled by the cooler 104 in the coal gangue calcination auxiliary cementitious material preparation system 10 after calcination. The high-temperature hot air in the high-oxygen activation calcination zone 1032 comes from the high-temperature section of the cement clinker after cooling by the grate cooler 204 in the cement clinker calcination system 20. The oxygen concentration and temperature in the high-oxygen activation calcination zone 1032 are regulated by introducing combustion air. The optimal calcination temperature for different types of coal gangue to prepare auxiliary cementitious materials varies, generally controlled between 700 and 900℃. When the temperature of the tertiary air (i.e., the hot air in the high-temperature section of the grate cooler 204) is too high, the introduction of combustion air can both reduce the temperature of the tertiary air, preventing excessive temperature from causing kaolinite mullitization, and increase the oxygen concentration to achieve rapid decarbonization under high oxygen conditions. When the coal gangue is high-calorific-value coal gangue, its own calorific value can sustain combustion. In this case, it is necessary to reduce the tertiary air and increase the proportion of combustion air. Adjusting the ratio of combustion air to tertiary air can also adapt to the calcination of coal gangue with different calorific values. The high-temperature hot air in the low-oxygen color control zone 1033 comes from the hot air outlet of the C4 preheater in the cement clinker calcination system 20.

[0034] The hot air from the belt roaster 103, after preheating and drying the granular coal gangue, enters the grate cooler 204 of the cement clinker calcination system 20 to continue cooling the cement clinker; the high-temperature flue gas from the belt roaster 103, after activating and calcining the coal gangue and adjusting its color, enters the decomposition furnace of the cement clinker calcination system 20 for combustion.

[0035] Finally, the color-adjusted coal gangue particles are fed into cooler 104 for cooling to obtain calcined and activated coal gangue.

[0036] 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.

[0037] In a preferred embodiment, the belt roaster 103 in the coal gangue calcination auxiliary cementitious material preparation system 10 is a special roaster for calcining granular coal gangue. The belt roaster 103 is internally divided into a preheating and drying zone 1031, a high-oxygen activation calcination zone 1032, and a low-oxygen color control zone 1033 connected in sequence. Each of the preheating and drying zone 1031, the high-oxygen activation calcination zone 1032, and the low-oxygen color control zone 1033 has at least one track. Each zone has a material distribution device and an exhaust fan at the top and an air intake homogenization device at the bottom. A flap valve 1034 is provided between two connected zones.

[0038] In this embodiment, the preheating drying zone 1031 and the low-oxygen color control zone 1033 are equipped with a single-stage track, and the high-oxygen activation calcination zone 1032 is equipped with a two-stage track. The material distribution device is used to ensure that the material on the track is evenly spread, the air induced device is used to ensure that the upper hot air in the corresponding zone can be evenly discharged, the air inlet homogenization device is used to ensure that the hot air entering the corresponding zone can be evenly entered, and the flap valves 1034 are all double-layer flap valves.

[0039] The granular coal gangue is produced inside the belt roaster 103 in the following way, combined with... Figure 2 As shown: Granular coal gangue raw material is evenly spread onto the corresponding conveyor belt from the upper distribution device of the preheating and drying zone 1031. The hot air from the cooler 104 of the coal gangue calcination auxiliary cementitious material preparation system 10, which cools the calcined coal gangue, enters the preheating and drying zone 1031 from the air inlet homogenization device at the bottom of the belt roaster 103. The preheated and dried hot air then enters the grate cooler 204 from the upper exhaust device of the preheating and drying zone 1031 to cool the cement clinker. The preheated and dried coal gangue enters the high-oxygen activation calcination zone 1032 through a double-layer flap valve and is evenly spread onto the conveyor belt by the distribution device. The high-oxygen activation calcination zone 1032 uses a two-stage conveyor belt; the calcined coal gangue falls onto the second-stage conveyor belt from the first-stage conveyor belt. The high-temperature section of the grate cooler 204 sends hot air from the high-oxygen activation calcination zone 1032... The air intake homogenizing device at the bottom of 032 enters the high-oxygen activation calcination zone 1032. The hot air after activation and calcination is introduced into the decomposition furnace from the induced draft device at the top of the high-oxygen activation calcination zone 1032. The activated and calcined coal gangue on the secondary track enters the low-oxygen color control zone 1033 through the double-layer flap valve. It is evenly spread on the corresponding track by the material distribution device. The hot air from the outlet of C4 preheater enters the low-oxygen color control zone 1033 from the air intake homogenizing device at the bottom of the low-oxygen color control zone 1033. The hot air after low-oxygen color control is introduced into the decomposition furnace from the induced draft device at the top of the low-oxygen color control zone 1033. The coal gangue after low-oxygen color control enters the cooler 104 for cooling and temperature reduction to obtain calcined and activated coal gangue. The calcined and activated coal gangue enters the cement mill along with the cement clinker.

[0040] In a preferred embodiment, the hot air temperature of the calcined coal gangue after cooling the coal gangue in the cooling machine 104 of the coal gangue calcination preparation auxiliary cementitious material system is 200~400℃, the temperature of the preheated and dried coal gangue is 200~300℃, and the moisture content is <2%.

[0041] In a preferred embodiment, the hot air temperature in the high-temperature section of the cement clinker calcination system 20 after the grate cooler 204 cools the cement clinker is 600~1000℃, and the oxygen concentration is 3~8%. The excess air coefficient of the high-oxygen activation calcination zone 1032 is 1~1.5. The oxygen concentration and temperature of the high-oxygen activation calcination zone 1032 are regulated during the activation calcination stage by introducing combustion air. When the calcination temperature is too high, adjusting the combustion air can increase the heat carried away by the flue gas, reduce the calcination temperature of the coal gangue, avoid the mullitization of metakaolinite, and simultaneously increase the oxygen concentration to ensure the decarburization effect. When the calcination temperature is too low, adjusting the combustion air reduces the heat carried away by the flue gas, ensuring that the activation calcination of kaolinite produces metakaolinite, prolonging the calcination time, and achieving slow decarburization under low oxygen conditions.

[0042] In a preferred embodiment, the hot air temperature at the outlet of the C4 preheater in the cement clinker calcination system 20 is 700~800℃, and the oxygen concentration is 2~3%; the excess air coefficient in the low-oxygen color control zone 1033 is 0.5~1.0.

[0043] As a preferred embodiment, when the loss on ignition of the raw coal gangue is >20%, the rotation speed of the conveyor belt in the high-oxygen activation calcination zone 1032 of the belt roaster 103 is adjusted so that the activation calcination time is 90~120min; when the loss on ignition of the raw coal gangue is <20%, the rotation speed of the conveyor belt in the high-oxygen activation calcination zone 1032 of the belt roaster 103 is adjusted so that the activation calcination time is 60~90min.

[0044] As a preferred embodiment, when the Fe content in the raw coal gangue is >3%, the rotation speed of the conveyor belt in the low-oxygen color control zone 1033 of the belt roaster 103 is adjusted so that the color control time is 60~90min; when the Fe content in the raw coal gangue is <3%, the rotation speed of the conveyor belt in the low-oxygen color control zone 1033 of the belt roaster 103 is adjusted so that the color control time is 30~60min.

[0045] As a preferred embodiment, calcined activated coal gangue is directly added to cement clinker as an auxiliary cementitious material 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; the activity of calcined activated coal gangue is 95-115% after 28 days. In a preferred embodiment, 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 feed amount of raw coal gangue in the belt roaster 103 is 10% of the cement clinker weight. When the kaolinite content in the raw coal gangue is 20-40%, the feed amount of raw coal gangue in the belt roaster 103 is 20% of the cement clinker weight. When the kaolinite content in the raw coal gangue is >40%, the feed amount of raw coal gangue in the belt roaster 103 is 30% of the cement clinker weight.

[0046] In this invention, granular coal gangue raw material first enters the preheating and drying zone 1031 for physical adsorption and water removal. The temperature of the preheated and dried coal gangue is 200~300℃, and the moisture content is <2%. The preheated and dried coal gangue then enters the high-oxygen activation calcination zone 1032 for high-oxygen activation calcination. The temperature in this zone is generally 700~900℃, the oxygen concentration is 3~8%, the excess air coefficient is 1~1.5, and the activation calcination time is 60~120 minutes. Volatile matter is released from the gangue, organic carbon components begin to burn, chemical structural water is removed, and the mineral structure of the gangue undergoes transcrystalline transformation, with kaolinite being converted into active metakaolinite. The activated and calcined gangue then enters the low-oxygen color control zone 1033 of the belt roaster 103. In this zone, the temperature is 700-800℃, the oxygen concentration is 2-3%, the excess air coefficient is 0.5-1.0, and the color control time is controlled at 30-90 minutes. The Fe in the gangue...3+ Reduced to Fe 2+ .

[0047] After color adjustment, the coal gangue is sent to the cooler 104 for cooling, and then enters the cement mill along with the cement clinker for homogenization and grinding. The hot air from the preheated and dried coal gangue by the belt calciner 103 enters the grate cooler 204 of the cement clinker calcination system 20 to continue cooling the cement clinker. The high-temperature flue gas from the activated calcination and color adjustment of the coal gangue enters the decomposition furnace of the cement clinker calcination system 20 for combustion.

[0048] A belt-type calcining system for granular coal gangue coupled with a cement clinker calcination system 20 includes: the original cement clinker calcination system 20 and a coal gangue calcination system for preparing auxiliary cementitious materials 10.

[0049] The existing cement clinker calcination system 20 is a dry-process cement clinker calcination system 20, mainly comprising, in sequence, a raw meal silo, a preheater 201, a decomposition furnace 202, a rotary kiln 203, a grate cooler 204, a clinker silo, and other main equipment such as a dust collector and a cement mill. The production process is as follows: after gas-solid heat exchange in the preheater, the cement raw meal enters the decomposition furnace 202 for calcination and decomposition, and then 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 in the decomposition furnace 202 for combustion support.

[0050] The auxiliary cementitious material preparation system 10 for coal gangue calcination mainly includes: a coal gangue crushing system 101, a coal gangue silo 102, a feeding device, a gas flow regulation system, a belt roaster 103, a combustion fan 106, a cooler 104, a cold air fan 105, and a material conveying system; the discharge end of the coal gangue crushing system 101 is connected to the coal gangue silo 102, and the discharge end of the coal gangue silo 102 is connected to the feeding device. The device is connected to the feed end of the belt calciner 103, and the discharge end of the belt calciner 103 is connected to the cooler 104. The discharge end of the cooler 104 is connected to the cement mill via a material conveying system. The air inlet of the cooler 104 is connected to the air cooler 105, and the air outlet of the cooler 104 is connected to the air inlet of the preheating and drying zone 1031 of the belt calciner 103. The outlet duct of the belt calciner 103 is connected to the low-temperature air section of the grate cooler 204 of the cement clinker calcination system 20. The air inlet of the high-oxygen activation calcination zone 1032 of the belt calciner 103 is connected to the high-temperature air section of the grate cooler 204 and the combustion fan 106 of the cement clinker calcination system 20. The air inlet of the low-oxygen color control zone 1033 of the belt calciner 103 is connected to the outlet of the C4 preheater of the cement clinker calcination system 20. The air outlets of the high-oxygen activation calcination zone 1032 and the low-oxygen color control zone 1033 of the calcining machine 103 are both connected to the air inlet of the decomposition furnace 202. Valves are installed on the exhaust pipe of the C4 preheater outlet of the cement clinker calcination system 20, the exhaust pipe of the high-temperature section of the grate cooler 204, and the air pipe of the combustion fan 106 connected to the air inlet of the high-oxygen activation calcination zone 1032. All valves are controlled by the gas flow regulation system.

[0051] 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 conveyed to the coal gangue silo 102102. After exiting the coal gangue silo 102102, the coal gangue is fed from the feed end of the belt roaster 103 through the feeding device and then preheated, dried, activated, calcined and colored. The colored coal gangue is conveyed to the cooler 104 through the material conveying system for cooling. The calcined and activated coal gangue obtained after cooling is used as an auxiliary cementing material and sent to the cement mill for grinding along with the cement clinker.

[0052] The hot air of the belt roaster 103 of the present invention is taken from the hot air after the cooling machine 104 in the coal gangue calcination and preparation of auxiliary cementitious materials system 10 cools the calcined and activated coal gangue, the hot air in the high-temperature section of the grate cooler 204 in the cement clinker calcination system 20 after cooling the cement clinker, and the hot air at the outlet of the C4 preheater. The hot air taken from the outlet of the C4 preheater of the cement clinker calcination system 20 and the high-temperature section of the grate cooler 204 enter the belt roaster 103 from the air inlets of the two lower areas of the belt roaster 103, respectively. The hot air exiting the belt roaster 103 is returned to the decomposition furnace 202 for combustion support. In the auxiliary cementitious material preparation system 10, the hot air from the calcined and activated coal gangue, sent by the cold air blower 105 into the cooler 104, preheats and dries the coal gangue. In the cement clinker calcination system 20, the high-temperature, high-oxygen hot air from the grate cooler 204 after cooling the cement clinker, combined with the combustion air from the combustion fan 106, achieves high-oxygen decarbonization and activation of the coal gangue. The low-oxygen hot air from the C4 preheater outlet in the cement clinker calcination system 20 controls the color of the activated and calcined coal gangue. The hot air from the belt roaster 103, after preheating and drying the coal gangue, enters the grate cooler 204 of the cement clinker calcination system 20 to cool the cement clinker. The flue gas from the belt roaster 103, after activation, calcination, and color control of the coal gangue, enters the decomposition furnace 202 of the cement calcination system for combustion.

[0053] To better understand the above embodiments of the present invention, the present invention will be further described in detail below.

[0054] Example 1 Please see Figure 1 Example 1 of the present invention provides a belt-type calcination process for granular coal gangue coupled with a cement clinker calcination system 20, 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 102102 for later use. Simultaneously, samples of the granular coal gangue are analyzed, revealing a kaolinite content of 18%, an Fe content of 3.8%, and a loss on ignition of 15%.

[0055] The amount of granular coal gangue raw meal fed is 10% of the amount of cement clinker.

[0056] The raw coal gangue in the coal gangue silo 102102 is fed into the belt roaster 103 by a quantitative feeding device for preheating, drying, activation calcination, and color control. The raw coal gangue first enters the preheating and drying zone 1031 for physical adsorption and water removal. The temperature of the preheated and dried coal gangue is 200~300℃, and the moisture content is <2%. After preheating and drying, the coal gangue enters the high-oxygen activation calcination zone 1032 for activation calcination. Volatile matter is released from the coal gangue, organic carbon components begin to burn, chemical structural water is removed, and the mineral structure of the coal gangue undergoes transformation, with kaolinite transforming into active metakaolinite. The calcination temperature in this zone is 700~900℃, the oxygen concentration is 3~8%, the excess air coefficient is 1~1.5, and the activation calcination time is 60~90 minutes. After activation calcination, the coal gangue enters the low-oxygen color control zone 1033 for color control. The Fe in the coal gangue... 3+ Reduced to Fe 2+ The temperature in this area is 700~800℃, the oxygen concentration is 2~3%, the excess air coefficient is 0.5~1.0, and the color adjustment time is controlled at 60~90 minutes.

[0057] Color-adjusted coal gangue was fed into cooler 104 for cooling, resulting in calcined and activated coal gangue. This activated coal gangue was then used as an auxiliary cementitious material and fed into a cement mill along with cement clinker for homogenization and grinding. The cement before and after incorporating the calcined and 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.

[0058] Example 2 Please see Figure 1 Example 2 of the present invention provides a belt-type calcination process for granular coal gangue coupled to a cement clinker calcination system 20, 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 102102 for later use. Simultaneously, samples of the granular coal gangue are analyzed, revealing a kaolinite content of 38%, an Fe content of 2.0%, and a loss on ignition of 25.0%.

[0059] The amount of granular coal gangue raw meal fed is 20% of the amount of cement clinker.

[0060] The raw coal gangue in the coal gangue silo 102102 is fed into the belt roaster 103 by a quantitative feeding device for preheating, drying, activation calcination and color control. The raw coal gangue first enters the preheating and drying zone 1031 for physical adsorption and water removal. After preheating and drying, the coal gangue reaches a temperature of 200-300℃ and a moisture content of <2%. The preheated and dried coal gangue then enters the high-oxygen activation calcination zone 1032 for activation calcination. During this process, volatile matter is released, organic carbon components begin to burn, chemical structural water is removed, and the mineral structure of the coal gangue undergoes transformation, with kaolinite being converted into active metakaolinite. The calcination temperature in this zone is 700-900℃, the oxygen concentration is 3-8%, the excess air coefficient is 1-1.5, and the activation calcination time is 90-120 minutes. After activation and calcination, the coal gangue enters the low-oxygen color control zone 1033 of the belt roaster 103. The Fe in the coal gangue... 3+ Reduced to Fe 2+ The temperature in this area is 700~800℃, the oxygen concentration is 2~3%, the excess air coefficient is 0.5~1.0, and the color adjustment time is controlled at 30~60 minutes.

[0061] Color-adjusted coal gangue was fed into cooler 104 for cooling, resulting in calcined and activated coal gangue. This activated coal gangue was then used as an auxiliary cementitious material and fed into a cement mill along with cement clinker for homogenization and grinding. The cement before and after incorporating the calcined and 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.

[0062] Example 3 Please see Figure 1 Example 3 of the present invention provides a belt-type calcination process for granular coal gangue coupled with a cement clinker calcination system 20, 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 102102 for later use. Simultaneously, samples of the granular coal gangue are analyzed, revealing a kaolinite content of 48%, an Fe content of 1.0%, and a loss on ignition of 16.0%.

[0063] The amount of granular coal gangue raw meal fed is 30% of the amount of cement clinker.

[0064] The raw coal gangue in the coal gangue silo 102102 is fed into the belt roaster 103 by a quantitative feeding device for preheating, drying, activation calcination and color control. Coal gangue first enters the preheating and drying zone 1031 for physical adsorption and water removal. The temperature of the preheated and dried coal gangue is 200-300℃, and the moisture content is <2%. After preheating and drying, the coal gangue enters the high-oxygen activation calcination zone 1032 for activation calcination. Volatile matter is released from the coal gangue, organic carbon components begin to burn, chemical structural water is removed, and the mineral structure of the coal gangue undergoes transformation, with kaolinite being converted into active metakaolinite. The calcination temperature in this zone is 700-900℃, the oxygen concentration is 3-8%, the excess air coefficient is 1-1.5, and the activation calcination time is 60-90 minutes. After activation calcination, the coal gangue enters the low-oxygen color control zone 1033 of the belt roaster 103. The Fe in the coal gangue... 3+ Reduced to Fe 2+ The temperature in this area is 700~800℃, the oxygen concentration is 2~3%, the excess air coefficient is 0.5~1.0, and the color adjustment time is controlled at 30~60 minutes.

[0065] Color-adjusted coal gangue was fed into cooler 104 for cooling, resulting in calcined and activated coal gangue. This activated coal gangue was then used as an auxiliary cementitious material and fed into a cement mill along with cement clinker for homogenization and grinding. The cement before and after incorporating the calcined and 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.

[0066] In summary, this invention couples the cement clinker calcination system 20 with the 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 20, 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. This invention also enables 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.

[0067] 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 belt-type calcination process for 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. The granular coal gangue raw material is sent into a belt roaster to sequentially perform preheating and drying, activation calcination and color regulation; wherein, the preheating and drying is to remove the physical adsorption water in the coal gangue; the activation calcination is to make the volatile in the coal gangue be analyzed out, the organic carbon component start to burn, the chemical structure water be removed, the mineral structure of the coal gangue be transformed, and the kaolinite be converted into the activated metakaolin; the color regulation is to make the Fe 3+ in the coal gangue be reduced into Fe 2+ ; Color-controlled coal gangue granules are fed into a cooler in a coal gangue calcination auxiliary cementitious material preparation system to obtain calcined activated coal gangue. The heat source for preheating and drying comes from the hot air after the cooling machine cools the calcined and activated coal gangue; the heat source for activation and calcination comes from the high-temperature section of the grate cooler in the cement clinker calcination system. During the activation and calcination stage, the temperature and oxygen concentration are adjusted by controlling the ratio of the high-temperature section hot air and combustion air in the grate cooler; the heat source for color control comes from the hot air at the outlet of the C4 preheater in the cement clinker calcination system. The preheated and dried hot air enters the grate cooler of the cement clinker calcination system to cool and reduce the temperature of the cement clinker; the high-temperature flue gas after activation calcination and color control enters the decomposition furnace of the cement clinker calcination system for combustion support.

2. The belt-type roasting granular coal gangue calcination process of the 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 belt-type roasting granular coal gangue calcination process of the coupled cement clinker calcination system according to claim 1, characterized in that, The belt roaster is internally divided into a preheating and drying zone, a high-oxygen activation and calcination zone, and a low-oxygen color control zone, which are connected in sequence. These zones are used to preheat and dry the coal gangue, activate and calcinate it, and control its color, respectively. Each zone has at least one level of conveyor belt. Each zone has a material distribution device and an exhaust fan at the top and an air intake homogenization device at the bottom. A flap valve is provided between two interconnected zones.

4. The belt-type roasting granular coal gangue calcination process of the coupled cement clinker calcination system according to claim 3, characterized in that, When the loss on ignition of raw coal gangue is >20%, adjust the speed of the conveyor belt in the high-oxygen activation calcination zone of the belt roaster to make the activation calcination time 90~120min; when the loss on ignition of raw coal gangue is <20%, adjust the speed of the conveyor belt in the high-oxygen activation calcination zone of the belt roaster to make the activation calcination time 60~90min.

5. The belt-type roasting granular coal gangue calcination process of the coupled cement clinker calcination system according to claim 3, characterized in that, When the Fe content in the raw coal gangue is >3%, adjust the speed of the conveyor belt in the low-oxygen color control zone of the belt roaster to make the color control time 60~90min; when the Fe content in the raw coal gangue is <3%, adjust the speed of the conveyor belt in the low-oxygen color control zone of the belt roaster to make the color control time 30~60min.

6. The belt-type roasting granular coal gangue calcination process of the coupled cement clinker calcination system according to claim 1, characterized in that, In the auxiliary cementitious material preparation system for coal gangue calcination, the hot air temperature after the calcined coal gangue is cooled by the cooler is 200~400℃, the temperature of the preheated and dried coal gangue is 200~300℃, and the moisture content is <2%.

7. The belt-type roasting granular coal gangue calcination process of the coupled cement clinker calcination system according to claim 1, characterized in that, In the cement clinker calcination system, the high-temperature section of the grate cooler has a hot air temperature of 600~1000℃ and an oxygen concentration of 3~8%; the excess air coefficient in the activation and calcination process is 1~1.5, and the activation and calcination time is 60~120min.

8. The belt-type roasting granular coal gangue calcination process of the coupled cement clinker calcination system according to claim 1, characterized in that, In the cement clinker calcination system, the hot air temperature at the outlet of the C4 preheater is 700~800℃, and the oxygen concentration is 2~3%; the excess air coefficient in the color control process is 0.5~1.0, and the color control time is controlled at 30~90min.

9. The belt-type roasting granular coal gangue calcination process of the coupled cement clinker calcination system according to claim 1, characterized in that, The activity of calcined and activated coal gangue is 95-115% after 28 days. Calcined and activated coal gangue is directly added to cement clinker as an auxiliary cementitious material 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.

10. The belt-type roasting granular coal gangue calcination process of the coupled cement clinker calcination system according to claim 9, 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 feed amount of raw coal gangue in the belt roaster is 10% of the cement clinker weight; when the kaolinite content in the raw coal gangue is 20-40%, the feed amount of raw coal gangue in the belt roaster is 20% of the cement clinker weight; when the kaolinite content in the raw coal gangue is >40%, the feed amount of raw coal gangue in the belt roaster is 30% of the cement clinker weight.

11. A belt-type calcining system for granular coal gangue coupled to a cement clinker calcination system, used to implement the calcination process described in any one of claims 1-10, 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, a belt roaster, a combustion fan, a cooler, and a cold air blower; The discharge end of the coal gangue crushing system is connected to the feed end of the belt roaster. The discharge end of the belt roaster is connected to a cooler, and the discharge end of the cooler is connected to a cement mill. The air inlet of the cooler is connected to a cold air fan, and the air outlet of the cooler is connected to the air inlet of the preheating and drying zone of the belt roaster. The outlet duct of the preheating and drying zone of the belt roaster is connected to the low-temperature air section of the grate cooler. The air inlet of the high-oxygen activation calcination zone of the belt roaster is connected to the high-temperature air section of the grate cooler and the auxiliary air section. The air inlet of the low-oxygen color control zone of the belt calciner is connected to the C4 preheater outlet, and the air outlets of the high-oxygen activation calcination zone and the low-oxygen color control zone of the belt calciner are 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 section of the grate cooler, and the duct connecting the combustion blower to the air inlet of the high-oxygen activation calcination zone. All valves are controlled by the gas flow regulation system.

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