An apparatus for calcining coal gangue and a method of using the same

Abstract

This invention discloses an apparatus and method for calcining coal gangue, relating to the fields of heat treatment and equipment. The apparatus includes: a preheater and a waste heat boiler connected in parallel to a calcining furnace. The furnace chamber is divided into an oxidation zone and a reduction zone, both equipped with fuel nozzles. The oxidation zone and reduction zone are connected by a constriction, with the reduction zone located downstream of the gas flow. The calcining furnace is connected to the preheater and the waste heat boiler via a separator. A cooler is connected to the material outlet of the calcining furnace, and the cooler is connected to a finished product collection system. This invention can simultaneously convert low-quality fuel, including coal gangue, into coal gas and electricity during the process of calcining coal gangue to manufacture inorganic materials. This solves the problem of high ash content in low-quality fuel, expands its application range, reduces carbon dioxide emissions, and achieves comprehensive utilization of solid waste; it also improves the efficiency of waste heat power generation.

Description

Technical Field

[0001] This invention relates to the field of heat treatment and equipment, and in particular to an apparatus for calcining coal gangue and its method of use. Background Technology

[0002] Coal gangue is a solid waste generated during coal mining and washing. It is a co-existing mineral in coal-bearing sedimentary strata, including coal-series kaolinite. The main phases of coal-series kaolinite are kaolinite and quartz, with kaolinite content typically around 70%. It can be used to produce kaolinite products, especially high-quality calcined kaolinite. Due to its unique physical and chemical properties, kaolinite has a wide range of applications in many fields, mainly in ceramics, papermaking, coatings, rubber, plastics, refractory materials, daily chemicals, agricultural materials, fiberglass, catalysts, and pharmaceuticals.

[0003] Coal gangue has long been stockpiled as a bulk industrial solid waste, occupying land and polluting the environment. Converting coal gangue into high-quality kaolin products can not only solve the environmental problems caused by coal gangue, but also meet the market demand for kaolin, creating good environmental and economic benefits.

[0004] Chinese Patent CN 121016692 A discloses a magnetic coal-based kaolin hydrogel adsorbent material, its preparation method, and its application, relating to the field of coal gangue resource utilization technology, specifically to a magnetic coal-based kaolin hydrogel adsorbent material, its preparation method, and its application. The preparation method of this material specifically includes the following steps: ultrafine grinding of coal gangue ore, sieving and classifying to obtain coal-based kaolin material; further magnetic separation to obtain iron-rich tailings of coal-based kaolin; further magnetized roasting in a reducing atmosphere to obtain magnetic coal-based kaolin; compounding the magnetic coal-based kaolin with sodium alginate and chitosan using a gel coating method, cross-linking with calcium chloride solution, and freeze-drying to obtain the magnetic coal-based kaolin hydrogel material.

[0005] In implementing the embodiments of the present invention, the inventors discovered that the prior art has at least the following drawbacks:

[0006] In the industrial production of kaolin, purchased natural gas is usually used as fuel, which is expensive; moreover, flue gas is generated during the calcination process, and the high moisture content of the flue gas results in low efficiency of waste heat utilization (energy conversion); all of the above lead to excessively high production costs.

[0007] The inventors believe that, ultimately, coal gangue has a high lime content and low calorific value, making it a low-quality fuel that is difficult to utilize widely and has a low utilization rate, resulting in resource waste. Therefore, there is an urgent need to provide a device and method for calcining coal gangue that can solve the problem of the difficulty in widely utilizing coal gangue, expand the application scope of coal gangue, turn waste into treasure, and improve resource utilization efficiency. Summary of the Invention

[0008] To overcome the deficiencies of the prior art, the present invention provides an apparatus for calcining coal gangue and a method for using it. Specifically, the objective of the present invention is achieved through the following technical solution:

[0009] The first objective of this invention is to provide an apparatus for calcining coal gangue, comprising:

[0010] Preheater, waste heat boiler and calciner;

[0011] The feed inlet of the preheater is connected to a metering mechanism, which is connected to the feed pipe of the preheater via an airlock feeder;

[0012] The preheater is connected in parallel with the waste heat boiler, and the waste heat boiler is equipped with a heat exchanger, which is connected to a steam turbine generator set through a steam pipeline.

[0013] The calcining furnace is provided with an air inlet at the bottom and an air outlet at the top; the furnace chamber of the calcining furnace includes an oxidation zone and a reduction zone, both of which are equipped with fuel nozzles, and the oxidation zone and the reduction zone are connected by a narrowing, at which the cross-sectional area of ​​the furnace chamber becomes smaller;

[0014] The oxidation zone and reduction zone are divided by narrowing the opening, and the oxidation zone and reduction zone are physically isolated from each other, so that the furnace atmosphere does not interfere with each other, which is conducive to the stable operation of the system.

[0015] The reduction zone is located downstream of the oxidation zone along the airflow direction; a separator is connected to the end of the reduction zone; the calcining furnace is connected to the preheater and the waste heat boiler through the separator; the discharge port of the separator serves as the material outlet of the calcining furnace and is connected to the cooler; the finished product collection system is connected through the cooler.

[0016] By using this device, coal gas and steam can be produced simultaneously from coal gangue during the calcination of coal gangue to manufacture inorganic materials, thus realizing the comprehensive utilization of solid waste; moreover, when the steam is used for power generation, the efficiency of waste heat power generation is improved.

[0017] Furthermore, the preheater consists of at least two stages connected in series. This multi-stage series heat exchange improves heat exchange efficiency.

[0018] Furthermore, the preheater is a cyclone preheater; the preheater includes at least a first suspension preheater and a second suspension preheater, the first suspension preheater and the second suspension preheater being connected in series via connecting pipes.

[0019] The cyclone preheater, also known as a cyclone separator, is covered with insulation material. The insulation material is used to keep the temperature up and reduce heat loss. The technology is simple, mature and reliable.

[0020] Furthermore, the finished product collection system includes a collection cylinder and a dust collector connected to the collection cylinder; the dust collector is connected to a finished product conveyor and an induced draft fan.

[0021] By pre-separating some materials using the collection cylinder, the load on the dust collector is reduced, which is beneficial for the long-term operation of the equipment.

[0022] A second objective of this invention is to provide a method of using the apparatus for calcining coal gangue as described in any of the foregoing technical solutions, comprising the following steps:

[0023] S1: Grind the raw materials into fine powder, wherein the raw materials include coal gangue;

[0024] S2: The fine powder is preheated by the preheater 1 and then fed into the oxidation zone and reduction zone of the calcining furnace 3 respectively. After calcination, hot gas and slag are generated.

[0025] S3: The hot gas is conditioned into coal gas, including: supplementing the oxidation zone with high-quality fuel, the high-quality fuel including the self-produced coal gas, and ensuring sufficient oxygen supply; generating high-temperature flue gas, when the high-temperature flue gas passes through the reduction zone, feeding the reduction zone with an excess of carbon-containing fuel, so that CO2 in the flue gas combines with carbonaceous matter to generate CO, and generating the CO-rich hot gas as coal gas.

[0026] S4: After the coal gas is drawn from the reduction zone, part of it is recycled back to the calcining furnace 3, and part of it is used as fuel for kilns; the kiln is a rotary kiln, a vertical kiln, or a tunnel kiln; using coal gas after coal gangue can eliminate the impact of fuel ash on product quality, so its application range is wider.

[0027] S5: The hot gas is separated into gas and solid phases using the separator 31. After preliminary purification by the separator 31, the hot gas is divided into two paths, which enter the preheater 1 and the waste heat boiler 2 respectively. Among them, a portion of the hot gas is extracted into the preheater 1 at a ratio of 10-30% for preheating or drying coal gangue powder, and the remaining portion of the hot gas is introduced into the waste heat boiler 2 to generate steam for power generation, or the steam is used to directly drive the equipment.

[0028] S6: The raw materials are calcined in the calcining furnace 3 to obtain slag, which is then separated from the gas flow by the separator 31.

[0029] S7: The slag is cooled by the cooler 4, and the cooled slag is collected by the finished product collection system 5 to obtain the finished product; wherein, the hot air obtained during the cooling process is drawn into the calcining furnace 3 as combustion air.

[0030] Room temperature material comes into contact with high temperature airflow in the preheater 1 and its connecting pipes, completing the heat exchange process. The material temperature rises, loses moisture, and becomes dry. After collection, it enters the calcining furnace 3. Therefore, preheating can evaporate the moisture in the raw material in advance, increasing its initial energy, optimizing calcination conditions, and reducing heat consumption. Moreover, the vaporized moisture is carried away by the airflow and escapes the device, no longer passing through the waste heat boiler 2, further reducing the moisture content of the gas used in the waste heat boiler 2. The remaining hot gas is introduced into the waste heat boiler, where the waste heat boiler collects the heat stored in the hot gas. The heat is utilized in various ways, including generating steam for power generation or directly driving a motor. The hot gas has a high temperature and contains little water vapor, resulting in dryness and high quality, thus improving the energy conversion efficiency of waste heat power generation. The raw materials are calcined in the furnace to obtain slag, which is then separated from the airflow by the separator. Depending on the type and proportion of the coal gangue powder and the calcination temperature, the slag can be a mixed material or cement clinker. When the coal gangue is coal-based kaolin, the calcination product is a kaolin product. The hot air is high-temperature and oxygen-rich, which can further reduce heat consumption.

[0031] Furthermore, a coil is provided in the separator, and the coil is used in combination with the heat exchanger. The coil is a wound tube heat exchanger. The wound tube can be wound as a single strand, or two or more strands can be welded together and wound together. The coil 311 has a compact structure and a large heat transfer area per unit volume. The hot air obtained from cooling the product and / or the heat extracted from the calcination zone can be used as waste heat in advance to achieve further energy savings.

[0032] And / or, a dual-drive steam-electric system is adopted, in which the steam turbine and the electric motor jointly drive the main fan. This dual-drive system includes a waste heat boiler, a dual-drive steam turbine unit, and a circulating water system. Through the heat exchanger, 0.75 MPa(g), 300 ℃ superheated steam produced by the waste heat boiler enters the turbine inlet. The exhaust steam, after performing work, is condensed into water by the condenser. The turbine condensate is pumped to the deaerator for deoxygenation, and then pumped to the waste heat boiler to supply water, forming a steam-rankenstein thermodynamic cycle system. The unit layout is: main fan + electric motor + variable speed clutch + steam turbine; further improving energy conversion efficiency.

[0033] Furthermore, during the calcination process, the outlet temperature of the reduction zone is controlled at 700-800℃; and the ratio of CO2 partial pressure to CO partial pressure is less than 0.5, which is conducive to the reduction of iron.

[0034] A CO detector is installed at the gas outlet of the reduction zone or the separator, and the supply of raw materials and fuels in the reduction zone is adjusted according to the CO content detection results; this facilitates operation.

[0035] The material is cooled sequentially through a water cooling stage and an air cooling stage. The water cooling stage is completed by setting up a water cooling jacket, and the air cooling stage is completed by the cooler.

[0036] The gas is used to reduce iron oxides and prevent iron oxidation. In the water cooling stage, the slag is rapidly cooled to below 570°C by a water bath, which forces any residual ferrous oxide in the slag to decompose and generate magnetite and metallic iron. At the same time, an iron removal machine is set on the finished product conveying route. The iron removal machine is a dry magnetic separator used to remove magnetic substances from the product.

[0037] The separator is a cyclone separator, and the water-cooled jacket is a hollow container surrounding the separator's conical hopper. During the water-cooling stage, the discharge cone portion of the separator is embedded in the water-cooled jacket, which is connected to inlet and outlet water pipes for cooling water flow. A material temperature-cooling water flow control loop is also included, adjusting the cooling water flow rate to cool the material to below 570°C. The cooling water and material do not directly contact each other; heat exchange occurs through the partition wall, and the vaporized steam serves as makeup water for the waste heat boiler. This solution further conserves thermal energy resources; it further utilizes a reducing atmosphere and employs rapid cooling in the initial stage of product cooling, combined with magnetic separation, to thoroughly remove iron elements from the slag, improving product whiteness and quality—achieving multiple benefits.

[0038] Furthermore, in the air-cooling stage, a suspension or fluidized bed cooler is used to cool the finished product; the cooler is a suspension or fluidized bed cooler, and the cooler includes: a first cooling cylinder, a second cooling cylinder, a first fluidized bed and a second fluidized bed; the first cooling cylinder is connected to the second cooling cylinder, the second cooling cylinder is connected to the first fluidized bed, the first fluidized bed is connected to the first cooling cylinder, and the first cooling cylinder is also connected to the second fluidized bed;

[0039] During normal operation, high-temperature material discharged from the separator is first fed into the rising pipe of the first cooling cylinder, where it comes into contact with air for heat exchange. The material cools down and is carried to the second cooling cylinder. The air is heated and then drawn into the calcining furnace as combustion air. After being separated in the second cooling cylinder, the material is fed into the first fluidized bed. The first fluidized bed draws in fresh, cold air from the environment and uses a fluidizing fan to blow the material, further cooling it. The material is then drawn into the first cooling cylinder with the airflow. After being collected in the first cooling cylinder, the material falls into the second fluidized bed for final cooling. Finally, the material is conveyed via pneumatic conveying through ducts to the finished product collection system.

[0040] The pneumatic conveying air, after having some particles removed by the collecting cylinder, is further filtered and purified by the dust collector before being drawn out and discharged by the induced draft fan; alternatively, a portion is used as hot air for combustion assistance or raw material drying. The dust collector includes a bag filter or an electrostatic precipitator, and the collected material is the finished product, which is transported to the finished product warehouse by a finished product conveyor. By utilizing this solution, the amount of cold air intake can be adjusted in a timely manner according to production conditions to prevent waste; the load on the system fan can be reduced, and production costs can be lowered.

[0041] Furthermore, the fluidizing fan of the first fluidized bed draws in combustion gas, including the coal gas, which is then mixed with the fresh cold air. The fluidizing fan of the first fluidized bed uses an explosion-proof motor, a reinforced shaft sealing system to prevent leakage, and is equipped with a safety valve to avoid overpressure risks. During the product cooling process, the sensible heat of the product is used to heat the mixed gas, increasing the initial energy; this improves combustion efficiency and saves thermal energy.

[0042] Compared with the prior art, the beneficial technical effects of this invention are reflected in:

[0043] (1) Achieving comprehensive utilization of coal gangue and self-produced coal gas. This invention sets up an oxidation zone and a reduction zone within the calcining furnace 3, connected by a constricted opening. Excess air is introduced into the oxidation zone to ensure complete combustion of carbonaceous matter in the coal gangue, providing a high-temperature environment. Excess carbon-containing fuel (including coal gangue powder) is added to the reduction zone, utilizing the endothermic reaction between CO2 in the high-temperature flue gas and carbon (CO2 + C → 2CO) to generate coal gas with CO as its main component. Part of this coal gas is recycled back to the oxidation zone as high-quality fuel, and part is output as a product. Thus, coal gangue, a low-quality fuel (high ash content, low calorific value), is converted into high-quality coal gas, overcoming the problem of ash affecting product quality when coal gangue is directly burned, while simultaneously reducing CO2 emissions.

[0044] (2) Improving waste heat power generation efficiency. This invention connects the preheater 1 and the waste heat boiler 2 in parallel. The high-temperature coal gas drawn from the calciner 3 is purified by the separator 31 and then divided into two paths: one path enters the preheater 1 to preheat / dry the coal gangue raw material (during this process, the moisture contained in the raw material and the water vapor generated from the dehydroxylation of the coal gangue escape from the system and do not enter the waste heat boiler); the other path directly enters the waste heat boiler 2. The gas entering the waste heat boiler 2 is high-temperature, dry coal gas. Compared with the existing technology that uses flue gas with high moisture content for waste heat recovery, the heat source gas provided by this invention is drier, has a lower dew point temperature, and a higher working fluid temperature. According to the Carnot efficiency formula η = 1 - T c / T h This can effectively improve the energy conversion efficiency of waste heat power generation. Attached Figure Description

[0045] Figure 1 This is a flowchart of Embodiment 1 of the present invention;

[0046] Figure 2 This is a layout diagram of the waste heat boiler in Embodiment 2 of the present invention;

[0047] Figure 3 This is a layout diagram of the cooler in Embodiment 3 of the present invention.

[0048] In the picture:

[0049] In the diagram, the dashed lines with arrows indicate the direction of gas flow, and the solid lines with arrows indicate the direction of powder material flow.

[0050] 1-Preheater; 11-First suspension preheater; 12-Second suspension preheater;

[0051] 2- Waste heat boiler; 21- Heat exchanger; 22- Steam turbine generator set;

[0052] 3-Calcination furnace; 31-Separator; 311-Coil; 312-Water-cooled jacket;

[0053] 4-Cooler; 41-First cooling cylinder; 42-Second cooling cylinder; 43-First fluidized bed; 44-Second fluidized bed;

[0054] 5-Finished product collection system; 51-Collection cylinder; 52-Dust collector; 53-Finished product conveyor; 54-Exhaust fan. Detailed Implementation

[0055] To enable those skilled in the art to better understand the present invention, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are merely some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort should fall within the scope of protection of the present invention. It should be noted that the present invention can be implemented in many different ways as defined and covered by the claims. Where there is no conflict, the embodiments and features in the embodiments of this application can be combined with each other.

[0056] Compared with existing technologies, the present invention has a simple structure, reasonable design, and convenient implementation. In the embodiments of the present invention, a variety of optional implementation methods are provided, which can be selected according to actual needs. Regardless of which method is adopted, the existing technology is no longer used for calcining coal gangue, and the problems in the existing technology can be solved and the corresponding effects can be achieved. The following embodiments can be applied to calcining coal gangue to obtain kaolin products, or to calcining coal gangue to obtain cement clinker, and / or to waste heat power generation.

[0057] The specific embodiments of the present invention will now be described in detail with reference to the accompanying drawings.

[0058] Example 1

[0059] This embodiment discloses an apparatus for calcining coal gangue. The apparatus is equipped with a preheater 1, a waste heat boiler 2, a calcining furnace 3, and a metering mechanism. The metering mechanism can be a speed-regulating belt scale, and the metering mechanism is connected to the feed pipe of the preheater 1 through an airlock feeder.

[0060] See Figure 1 Specifically, the device includes a preheater 1 connected in parallel with a waste heat boiler 2, which reduces the overall resistance of the system; and a calcining furnace 3.

[0061] The calcining furnace 3 described in this application is a decomposition furnace, which is a container that provides a site for decomposition reactions. To date, decomposition furnaces have been used in the decomposition of carbonates, the calcination of metal hydroxides, the pyrolysis of hydroxyl chlorides and basic carbonates. In the building materials industry, a decomposition furnace is a thermal device that provides a site for fuel combustion, heat exchange and decomposition reactions. According to different working principles, it can be divided into various types such as swirl type, jet type, turbulent type, vortex combustion type and boiling type. In the production process, preheated raw materials (raw meal) and an appropriate amount of hot gas are simultaneously fed into the decomposition furnace. The raw meal is in a suspended or boiling state in the furnace. The fuel generates heat through flameless combustion, and the raw meal absorbs the heat and heats up, completing the decomposition process at high temperature.

[0062] Inside the calcining furnace 3, the fuel burns and releases heat. The material absorbs the heat and decomposes, and is calcined to produce anhydrous minerals. The calcining furnace 3 typically uses solid powder fuels such as coal powder as fuel, including low-quality fuels such as coal gangue, and can also use gaseous or liquid fuels.

[0063] In this embodiment, the furnace body of the calcining furnace 3 is formed by steel plates forming an outer shell, lined with refractory material, with an air inlet at the bottom and an air outlet at the top. The furnace chamber of the calcining furnace 3 is divided into an oxidation zone and a reduction zone, both of which are equipped with fuel nozzles. The oxidation zone and the reduction zone are connected by a constriction, with the reduction zone located downstream of the airflow. At the constriction, the cross-sectional area of ​​the furnace chamber decreases to generate a "jetting" effect. The "jetting" effect refers to the suspension and movement of materials caused by the blowing of gas. When the airflow passes through the constriction, the flow velocity increases due to the smaller cross-section, causing the material to boil, thus enhancing calcination and improving calcination efficiency.

[0064] The reduction zone is connected to a separator 31; the preheater 1 and the waste heat boiler 2 are connected through the separator 31; the material outlet of the calcining furnace 3 is connected to a cooler 4, and the material outlet includes the discharge port of the separator 31. In other words, the separator 31 is used to separate the calcined gas-solid mixture, and the separated gases enter the preheater 1 and the waste heat boiler 2 respectively; the discharge port of the separator 31 serves as the material outlet of the calcining furnace 3 and is connected to the cooler 4.

[0065] This embodiment also discloses the method of using the device: The raw material (coal gangue) is ground into fine powder, with the fineness controlled to ≤1% residue on a 325-mesh sieve and ≤0.5% moisture content. Using fine powder improves combustion speed and efficiency. The fine powder is preheated by the preheater 1 and then fed into the oxidation and reduction zones respectively. Preheating increases the initial energy of the fuel. After calcination, hot gas is generated. This hot gas is conditioned into coal gas. A blower draws the coal gas from the reduction zone, with part of it recycled to the calcining furnace 3 and part used as fuel for a kiln, which can be a rotary kiln, vertical kiln, or tunnel kiln. Thus, using coal gangue to produce coal gas eliminates the impact of fuel ash on product quality, thereby broadening its application range.

[0066] The conditioning method includes: fuel is fed into the oxidation zone and the reduction zone separately through two channels. In the oxidation zone, high-quality fuel (including self-produced coal gas) is added according to the production situation, and sufficient oxygen supply is ensured, so the combustion is complete and the furnace temperature is high. When the high-temperature flue gas rises through the reduction zone, an excess of carbon-containing fuel (including preheated coal gangue powder) is fed. CO2 in the flue gas combines with carbonaceous matter to generate CO, and the combustion environment is then transformed into reducing conditions. The generated hot gas is rich in carbon monoxide and can be used as coal gas. Furthermore, the hot gas is separated into gas and solid phases using the separator 31. After preliminary purification, the hot gas is divided into two paths, which then enter the preheater 1 and the waste heat boiler 2 respectively. The heat stored in the portion of the hot gas entering the waste heat boiler 2 is collected by the waste heat boiler 2 to generate steam for power generation or to directly drive the motor of the equipment. This portion of the hot gas is high temperature and dry, so the waste heat utilization efficiency is high. The portion of the hot gas entering the preheater 1 is used to preheat the raw materials and fuels, improve their initial energy, optimize calcination conditions, and reduce heat consumption. However, the moisture content increases significantly after heat exchange, so it is no longer used for waste heat power generation.

[0067] In this embodiment, a flow meter and an electric regulating valve are installed on the pipeline to form an automatic regulating loop. As needed, the hot gas is extracted at a ratio of 10-30% using the automatic regulating loop for preheating / drying coal gangue powder, thus evaporating the moisture in the raw material in advance. That is, the room temperature material and the high temperature airflow come into contact in the preheater 1 and its connecting pipeline to complete the heat exchange process. After the material temperature rises and loses moisture, it is dried and collected before entering the calcining furnace 3. The moisture is vaporized and carried by the airflow, escaping from the preheater 1 and no longer passing through the waste heat boiler 2. Therefore, the moisture content of the gas used by the waste heat boiler 2 can be further reduced, and the gas source quality can be improved.

[0068] The raw materials are calcined in the calcining furnace 3 to obtain slag. The slag is separated from the airflow by the separator 31, which is a cyclone separator. Depending on the type and proportion of the coal gangue powder, the slag is either a mixed material or cement clinker. When the coal gangue is coal-based kaolin, the calcination product is a kaolin product. When cement clinker is required, limestone needs to be added to the coal gangue powder in advance.

[0069] The cooler 4 is a suspension or fluidized bed cooler. The cooler 4 is used to cool the slag. Hot air is obtained from the cooling process. The hot air is rich in oxygen and is drawn into the calcining furnace 3 as combustion air, which further reduces heat consumption. After cooling, the slag is collected by the finished product collection system 5 to obtain the finished product.

[0070] In summary, by applying this embodiment, low-quality fuel (coal gangue) can be simultaneously converted into coal gas and electricity during the calcination of coal gangue, expanding its application scope, solving the problem of high ash content in low-quality fuel, overcoming the defect that excessive ash content of coal gangue as fuel affects product quality, reducing carbon dioxide emissions, realizing the comprehensive utilization of solid waste, and improving the efficiency of waste heat power generation.

[0071] Example 2

[0072] See Figure 2 Based on Example 1, the preheater 1 is a multi-stage cyclone preheater connected in series; the preheater 1 is a cyclone preheater, also known as a cyclone separator, with its outer surface covered with insulation material. Normal temperature material and high temperature airflow exchange heat through contact in the preheater, thus increasing the material temperature and discharging the airflow after its temperature decreases.

[0073] In this embodiment, the preheater 1 includes a first suspension preheater 11 and a second suspension preheater 12, which are connected in series via connecting pipes; the waste heat boiler 2 includes a heat exchanger 21, which is connected to a steam turbine generator set 22 via a steam pipe.

[0074] Furthermore, in this embodiment, a coil 311 is provided in the separator 31. The coil 311 is a spiral wound heat exchanger. The spiral wound tube can be wound as a single tube or as two or more tubes welded together and then wound together. The coil 311 has a compact structure and a large heat transfer area per unit volume. For example, for heat transfer tubes with a diameter of 8-12mm, the heat transfer area per cubic meter of volume can reach 100-170 square meters.

[0075] Existing technologies for waste heat utilization often have unsatisfactory heat exchange conditions, resulting in reduced thermal efficiency. For example, in related technologies, waste gas after preheating materials is often used for waste heat power generation, where the gas has a high moisture content and a low temperature. Unlike related technologies, this embodiment utilizes the hot air obtained from cooling the product and / or the hot air extracted from the calcining furnace 3 in advance for waste heat utilization. The hot air is high in temperature and dry. The utilization methods include generating steam for power generation or using steam to directly drive a fan motor.

[0076] According to the Carnot efficiency formula, η = 1 - T c / T h , among which, T c Th represents the absolute temperature of the low-temperature end (ambient) of the Carnot engine, and Th represents the absolute temperature of the working fluid (gas) at the high-temperature end of the Carnot engine. According to this formula, the larger the absolute temperature Th of the working fluid at the high-temperature end, the greater the maximum heat-work conversion efficiency of the Carnot engine. That is, the higher the working fluid temperature, the higher the thermal efficiency. In this embodiment, the gas is dry and the temperature is high, which is beneficial for use.

[0077] The traditional waste heat boiler + steam turbine generator set model, where steam drives the turbine to generate electricity (thermal energy → mechanical energy → electrical energy), has low energy conversion efficiency and relatively high investment costs. In the transportation sector, steam power was once widely used in steam trains and steamships to propel them. Currently, in industrial production, steam power can directly drive various mechanical equipment, such as generators, pumps, and compressors, providing power support for industrial production. Direct drive eliminates the need for power generation, which is obviously more efficient. Therefore, in a further embodiment, a steam-electric dual-drive system is used to drive the main fan, where the turbine and electric motor jointly drive the main fan. The steam-electric dual-drive system includes a waste heat boiler, a turbine unit, an electric motor, and a circulating water system. The heat exchanger of the waste heat boiler generates superheated steam at 0.75 MPa (g) and 300°C. This steam enters the turbine to perform work. The exhaust steam, after performing work, is condensed into water by a condenser, and then returned to the waste heat boiler via a condensate pump, deaerator, and feedwater pump, forming a Rankine cycle thermal system. The unit is arranged as follows: main fan + motor + speed change clutch + steam turbine.

[0078] In addition, for the calcination of coal-based kaolin, kaolin series products often have whiteness requirements; existing technologies often use water spraying for bleaching, which not only wastes water resources, but also increases the moisture content in the exhaust gas, worsening the conditions for waste heat power generation.

[0079] This embodiment is particularly applicable to the calcination of coal-based kaolin (also known as coal gangue-based kaolinite) to obtain a series of calcined kaolin products (the main mineral component is mullite). In addition to the beneficial effects of Embodiment 1, this embodiment achieves iron removal and whitening through a combination of reducing atmosphere control and rapid cooling: utilizing a reducing atmosphere and rapid cooling in the initial stage of product cooling, coupled with magnetic separation, effectively removes iron elements from the slag, improving product whiteness and quality.

[0080] Principle of reducing atmosphere control

[0081] This embodiment ensures that the reduction zone is essentially oxygen-free by controlling the excessive addition of carbon source. The principle is as follows:

[0082] In the previous oxidation zone, oxygen was nearly depleted during fuel combustion, resulting in a high carbon dioxide concentration at the inlet of the reduction zone. When an excessive amount of carbon source is added to the reduction zone, carbon dioxide preferentially reacts with carbon to form carbon monoxide: CO2 + C → 2CO. This is a spontaneous endothermic reaction. As long as carbon is present, carbon dioxide will continue to be consumed, causing a decrease in carbon dioxide concentration. This decrease in carbon dioxide concentration, in turn, promotes the active participation of the remaining oxygen in the reduction zone in the fuel combustion reaction: C + O2 → CO2. This is an exothermic reaction, which ends before the aforementioned endothermic reaction is completed, meaning the exothermic reaction ends prematurely. The reason is that oxygen is the most reactive, causing it to be used up first. Once the oxygen is gone, the exothermic reaction has to end, leaving only the endothermic reaction continuing in the reduction zone, causing the CO concentration to continue to rise. CO is a raw material for metal reduction. Therefore, in the reduction zone of this invention, as long as an excessive amount of carbon source is maintained, there is no possibility of oxygen present, i.e., a reducing atmosphere is formed. Even without considering reaction kinetics, from the perspective of reaction equilibrium alone, the carbon source required for an exothermic reaction is the standard amount of carbon. Any amount exceeding the standard amount is considered an excess. Excess carbon source has no oxygen available and can only react with CO2 to produce CO, which is the endothermic reaction mentioned above. Therefore, the more excess carbon source there is, the higher the CO concentration and the stronger the reducing atmosphere.

[0083] The dehydroxylation process of kaolin in coal gangue is divided into two parts. The first part is the decomposition of surface hydroxyl groups, which occurs from 470℃ to 540℃. Within this temperature range, the kaolin structure is not significantly damaged. The second part is the decomposition of inner hydroxyl groups, which occurs when the temperature exceeds 540℃, forming metakaolin.

[0084] In this embodiment, the decomposition of the two parts causes some moisture to be removed first in the preheater 1. This moisture is all crystal water. After removal, it will vaporize along with the free water in the material and escape from the preheater 1 without entering the air inlet pipe of the waste heat boiler 2. Therefore, the air source of the waste heat boiler 2 is dry. Drying leads to a lower dew point temperature, which is beneficial for use. For example, if the air source humidity reaches saturation, obviously, in order to prevent condensation in the equipment, enthalpy below 100°C is almost unusable.

[0085] Generally speaking, for pure kaolin, the spinel-mullite crystalline phase forms in the range of 900℃-1100℃, at which point the kaolin is completely decomposed. The activation of kaolin is essentially the process of dehydroxylation into metakaolin. The dehydroxylation process is affected by the crystallinity of kaolin. Kaolin with higher crystallinity is more easily destroyed. Different thermal activation conditions will have a significant impact on the thermal activation process and results of kaolinite.

[0086] At temperatures above 1100℃, a stable mullite (3Al2O3•2SiO2) phase is formed through an exothermic reaction, and amorphous SiO2 begins to crystallize. During this stage, alkaline oxides react with SiO2 at 1100℃ and fill the pores of Si-O.

[0087] At 1200-1400℃: 3(Al2O3•SiO2) (mullite-like) → 3Al2O3•2SiO2 (mullite) + SiO2 (cristobalite)

[0088] At 1400-1550℃: SiO2 (cristobalite) → SiO2 (amorphous state)

[0089] After being calcined at 1400-1550℃, the mullite crystal phase remains unchanged, while the cristobalite crystals disappear and are evenly distributed in the glass, eventually forming a single mullite crystal product.

[0090] Furthermore, this embodiment explores the influence of calcination temperature on the chemical composition of Tongxin coal gangue through experiments. The laboratory results show that the chemical composition of coal gangue samples of different grades changes with temperature in a consistent manner. As the calcination temperature increases, the SiO2 content in the coal gangue gradually increases, while the Al2O3 content gradually decreases. At 1200℃, the SiO2 content of high-grade coal gangue reaches 52.1%, an increase of 15.31% compared to the original sample, while Al2O3 decreases to 45.9%, a decrease of 14.38% compared to the original sample. The SiO2 content of medium-grade coal gangue reaches 52.5%, an increase of 15.71% compared to the original sample, while Al2O3 decreases to 44.4%, a decrease of 15.88% compared to the original sample. This is mainly due to the transformation of kaolinite in the coal gangue into aluminosilicate spinel and amorphous silica at high temperatures. The contents of Fe2O3, CaO, K2O and TiO2 in the remaining components all increased. Among them, the Fe2O3 content of high-grade coal gangue increased to 0.39% at 1200℃, and the Fe2O3 content of medium-grade coal gangue increased to 0.54%. The other components changed little.

[0091] Overall, the calcination whiteness of coal gangue of different grades increases with increasing temperature. The calcination whiteness of high-grade coal gangue at 1200℃ increases by 29 compared to 850℃, and the calcination whiteness of medium-grade coal gangue at 1200℃ increases by 25.9 compared to 850℃. At the same time, the calcination whiteness of high-grade coal gangue is higher than that of medium-grade coal gangue at all calcination temperatures.

[0092] Furthermore, in this embodiment, the outlet temperature of the reduction zone is controlled at 700-800℃ during the calcination process; and the ratio of CO2 to CO partial pressure is less than 0.5. In this embodiment, a CO detector is installed at the gas outlet of the reduction zone or the separator 31, and the supply of raw materials to the reduction zone is adjusted according to the CO content detection results. In conventional production, a lower CO content is better, indicating more complete combustion; however, in this invention, a higher CO content is more conducive to the reduction of iron, therefore the control logic is the opposite of the conventional approach.

[0093] The reason for this is that the color of iron is related to its valence state, which in turn affects the whiteness of the product. The generation of a reducing atmosphere can lead to the conversion of ferric iron to ferrous iron / metallic iron. The reduction sequence of iron is: ferric oxide → ferrous oxide → metallic iron. Among them, ferrous oxide (FeO) is unstable at room temperature and is prone to decomposition or oxidation. Specifically, ferrous oxide is thermodynamically unstable at temperatures below about 570°C and will decompose into iron and magnetite (4FeO → Fe + Fe3O4). Ferrous oxide and ferric oxide are not magnetic, while magnetite and metallic iron are magnetic. Using this principle in conjunction with magnetic separation, iron can be removed, increasing the whiteness of the product.

[0094] The critical temperature of 570℃ is directly related to the stability of ferrous oxide. Below 570℃, the decomposition reaction of ferrous oxide is dominant, while above 570℃, ferrous oxide can only exist stably within a specific oxygen partial pressure range. Therefore, 570℃ is regarded as a key turning point in the stability of ferrous oxide.

[0095] In this embodiment, the material is cooled in two stages: water cooling and air cooling. The water cooling stage is completed by the water cooling jacket 312, and the air cooling stage is completed by the cooler 4.

[0096] Specifically, the discharge cone portion of the separator 31 is embedded in the water-cooled sheath 312. The separator 31 is a cyclone separator, which is a dry gas-solid separation device that uses the centrifugal force generated when the gas-solid mixture rotates at high speed to separate dust particles from the airflow. When the dust-laden airflow enters the cyclone separator at a speed of 12-30 m / s, the airflow changes from linear motion to circular motion. Under the action of centrifugal force, the particles are thrown towards the wall of the separator. Once the particles collide with the wall, they lose kinetic energy and are only governed by gravity, sliding down the wall. Accordingly, the water-cooled sheath 312 is designed in this embodiment. The water-cooled sheath 312 is a hollow container that surrounds the cone of the separator 31 and is connected to inlet and outlet water pipes for cooling water circulation. The collected material first slides down the inner wall of the cone of the separator 31. The heat contained in the material is first transferred to the inner wall of the cone and cooled. The heat of the inner wall of the cone is then carried away by the cooling water.

[0097] Furthermore, this embodiment includes an electric flow valve on the cooling water pipeline for regulating the flow rate of the cooling water; and a temperature measuring device for real-time acquisition of material temperature changes; the electric flow valve and the temperature measuring device are connected to form a control system, which has a material temperature-flow control loop to control the material temperature to a set value by automatically adjusting the flow rate; specifically, for the electric flow valve, the valve opening represents the flow rate, and temperature-flow control can be converted into temperature-valve opening control; the electric flow regulating valve adopts a self-feedback system, and its working principle is to acquire the real-time changes in the flow rate of the regulated medium (cooling water) through a flow meter, convert it into a standard DC 4-20mA control signal through an intelligent PID controller to control the valve opening, realize automatic PID regulation and control, change the flow rate of the regulated medium (cooling water), and keep the controlled process parameter (temperature) at a given value; similar in function to the electric flow valve (electric regulating valve) is the self-operated regulating valve, which will not be described in detail here.

[0098] Therefore, by adjusting the flow rate of the cooling water, the material can be rapidly cooled to below 570°C. Combined with a reducing atmosphere, this prevents the oxidation of iron. Furthermore, the cooling water and material do not directly contact each other; heat exchange occurs through the indirect heat exchange mechanism, and the vaporized steam serves as makeup water for the waste heat boiler, further conserving thermal energy. In other words, this embodiment utilizes cooling water as makeup water, satisfying the needs of waste heat power generation while simultaneously achieving rapid cooling, creating conditions for improving product whiteness—a multi-benefit approach with synergistic effects.

[0099] The purpose of rapid cooling is to prevent the high-temperature slag from contacting oxygen, and the faster the cooling rate, the better. If the cooling rate is not fast enough, for example, below 50°C / min, a powder material temperature measuring instrument (including thermocouple) can be installed at the discharge port of the separator 31 and linked with the discharge device (including electric flap airlock discharge valve). By converting the collected temperature signal into a control signal for the discharge switch (flap), the slag is set to not be discharged unless the slag temperature is lower than 570°C. In this way, combined with the oxygen-free atmosphere in the reduction zone, the high-temperature slag can be effectively prevented from contacting oxygen.

[0100] In short, this embodiment controls the fuel feeding to create a reducing atmosphere in the later stages of calcination, generating coal gas. This coal gas is then used to reduce iron oxides (ferric oxide, magnetite, and ferrous oxide), preventing iron oxidation. Furthermore, rapid cooling of the slag to below 570°C via a water bath forces any remaining ferrous oxide in the slag to decompose, generating magnetite and metallic iron. Combined with magnetic separation to remove iron, this effectively removes iron from the kaolin product, increasing its whiteness. Conversely, if the slag is not cooled quickly, any remaining ferrous oxide / metallic iron may come into contact with oxygen during the subsequent cooling process. At temperatures above 570°C, this iron will be re-oxidized to ferric oxide. Since ferric oxide is non-magnetic, magnetic separation cannot completely remove the iron.

[0101] In other words, this application achieves this by: (1) generating a reducing atmosphere to promote the reduction of iron oxides, so that the slag product of the separator 31 does not contain the original ferric oxide; (2) generating a reducing atmosphere + rapid cooling to prevent the oxidation of iron, so that the slag product of the separator 31 does not contain secondary ferric oxide. The two work together and are indispensable, so that the iron in the slag product of the separator 31 can only exist in the form of magnetite and / or metallic iron, all of which are magnetic, and finally the iron can be completely removed by magnetic separation. Among them, regarding magnetic separation, this embodiment sets an iron removal machine on the finished product conveying route. The iron removal machine is a dry magnetic separator used to remove magnetic substances from the product.

[0102] As mentioned above, this embodiment no longer uses water spraying, but instead uses "isolation immersion," that is, the use of the water-cooled jacket 312, which can also be called "water bath." This overcomes the shortcomings of the prior art and achieves the beneficial effects of saving water resources and improving waste heat power generation efficiency. In other words, this embodiment, by using a protective atmosphere (reducing atmosphere) + "water bath" when cooling slag, can ensure that the slag does not come into contact with oxygen when the temperature is above 570°C; in other words, when the temperature drops below 570°C, it is not a problem for the slag to come into contact with oxygen, which is also beneficial to the air-cooling design of the product. However, the prior art uses water spraying for cooling, which can objectively achieve rapid cooling, but the open water spraying environment and poor atmosphere control cannot strictly guarantee the condition that "the slag does not come into contact with oxygen when the temperature is above 570°C." This will cause some iron elements to oxidize and exist in the form of ferric oxide. Ferric oxide is not magnetic, therefore, the prior art cannot completely remove iron elements through magnetic separation. In addition, water vapor generated after spraying water enters the exhaust gas, resulting in a high moisture content in the exhaust gas. As a result, the residual heat contained in the exhaust gas is difficult to utilize, and the effect of this embodiment cannot be achieved.

[0103] Moreover, overcoming the shortcomings of existing technologies cannot be solved simply by generating a reducing atmosphere. For example, coal gangue has a low calorific value and is not easy to burn, making it a low-quality fuel. In this embodiment, coal gangue is the main fuel. Under these conditions, the temperature must be raised in the oxidation zone of the calcining furnace 3 before an excess of carbonaceous fuel is added to the reduction zone to create a reducing atmosphere and generate coal gas. This coal gas is then partially reused in the oxidation zone. Only in this way can the temperature be raised and safe production achieved. In other words, the above-mentioned beneficial effects can only be obtained through the combination of various methods, none of which can be omitted.

[0104] Furthermore, in related technologies, coal gangue syngas refers to the conversion of coal gangue into combustible gas with hydrogen (H2) and carbon monoxide (CO) as its main components through gasification technology, achieving solid waste resource utilization and clean energy production. The production of coal gangue syngas typically employs high-temperature gasification technology. The process involves: crushing coal gangue and mixing it with biomass (such as pine sawdust and straw) in a specific ratio, followed by a synergistic catalytic reaction in a gasifier (temperatures can reach 1200℃) to generate hydrogen-rich syngas (mainly composed of H2, CO, and CH4). However, the introduction of biomass leads to a higher ash content in the slag, which is detrimental to improving product whiteness. Moreover, the hydrogen-rich syngas, upon combustion, produces water, resulting in excessive moisture in the flue gas and a high humidity content, which is unfavorable for waste heat power generation. Therefore, the application of related technologies in this field cannot achieve the aforementioned beneficial effects.

[0105] Example 3

[0106] See Figure 3 Based on Example 1 or Example 2, this example uses a suspension / fluidized cooler to cool the finished product during the air-cooling stage.

[0107] In a traditional gas bed, when gas flows upward through a uniform solid particle bed at a low velocity, the gas only passes through the voids between the stationary solid particles, and the height of the solid particle bed remains essentially constant; such a bed is called a fixed bed. As the gas velocity increases, the solid particle bed begins to loosen, the relative positions of the solid particles adjust within a certain range, and the bed height increases slightly. With further increases in gas velocity, fluidization and pneumatic transport are imminent. Suspension, on the other hand, utilizes gas (most commonly air) power to suspend and transport solid particles within a closed pipe; this suspension is essentially a form of pneumatic transport.

[0108] In this embodiment, the cooler 4 includes: a first cooling cylinder 41, a second cooling cylinder 42, a first fluidized bed 43, and a second fluidized bed 44. The first cooling cylinder 41 is connected to the second cooling cylinder 42, the second cooling cylinder 42 is connected to the first fluidized bed 43, the first fluidized bed 43 is connected to the first cooling cylinder 41, and the first cooling cylinder 41 is also connected to the second fluidized bed 44.

[0109] During normal operation, the high-temperature material discharged from the separator 31 is first fed into the rising pipe of the first cooling cylinder 41, where it comes into contact with air for heat exchange. The material is cooled and carried to the second cooling cylinder 42, where the air is heated and drawn into the calcining furnace 3 for use as combustion air. The material is then separated by the second cooling cylinder 42 and fed into the first fluidized bed 43. The first fluidized bed 43 draws in fresh, cold air from the environment and blows the material with the help of a fluidizing fan. After further cooling, the material is drawn into the first cooling cylinder 41 with the airflow. After being collected by the first cooling cylinder 41, the material falls into the second fluidized bed 44 for final cooling. Then, it is conveyed by pneumatic conveying through a duct to the finished product collection system 5.

[0110] Furthermore, the fluidizing fan in the first fluidized bed 43 draws in combustible gas (including coal gas) and mixes it with the fresh, cold air. In this way, during the product cooling process, the sensible heat of the product is used to heat the mixed gas, increasing the initial energy and improving combustion efficiency while saving thermal energy. However, the fan needs to be specifically designed for the characteristics of combustible gases, such as using an explosion-proof motor, a reinforced shaft sealing system to prevent leakage, and a safety valve to avoid the risk of overpressure.

[0111] In this embodiment, the finished product collection system 5 includes a collection cylinder 51 and a dust collector 52 connected thereto; and the dust collector 52 is connected to a finished product conveyor 53 and an induced draft fan 54.

[0112] The dust concentration of the air used for pneumatic conveying is quite high. In this embodiment, a collection cylinder 51 is used for pretreatment. The collection cylinder 51 is a cyclone dust collector that can collect larger particles. Then, after further filtration and purification by the dust collector 52, the air is drawn out and discharged by the induced draft fan 54. Alternatively, part of it can be used as hot air for combustion or drying of raw materials and fuels, further saving thermal energy. The dust collector 52 includes a bag dust collector or an electrostatic precipitator. The collected material is the finished product, which is transported to the finished product warehouse by the finished product conveyor 53.

[0113] By utilizing this embodiment, the amount of cold air intake can be adjusted according to production conditions to prevent waste and reduce the load on the system fan.

[0114] The above description is only a preferred embodiment of the present invention. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

[0115] It should be particularly noted that the various embodiments listed in this specification and accompanying drawings are intended to illustrate the technical solutions and advantages of the present invention, and not to limit the scope of protection of the present invention. Without departing from the core ideas and technical effects of the present invention, those skilled in the art can make any form of improvement, substitution, combination, or modification to the structural arrangement, process parameters, material selection, control logic, etc., of the described embodiments; any obvious changes based on the same concept should be considered equivalent solutions of the present invention and should be included within the scope of protection defined by the claims of the present invention. The actual scope of protection of the present invention is determined by the appended claims and should be correctly understood in conjunction with the specification and accompanying drawings.

Claims

1. An apparatus for calcining coal gangue, characterized in that, include: Preheater (1), waste heat boiler (2) and calciner (3); The feed inlet of the preheater (1) is connected to a metering mechanism, which is connected to the feed pipe of the preheater (1) via an airlock feeder. The preheater (1) is connected in parallel with the waste heat boiler (2), and the waste heat boiler (2) is equipped with a heat exchanger (21). The heat exchanger (21) is connected to the steam turbine generator set (22) through a steam pipe. The calcining furnace (3) has an air inlet at the bottom and an air outlet at the top; the furnace chamber of the calcining furnace (3) includes an oxidation zone and a reduction zone, both of which are equipped with fuel nozzles. The oxidation zone and the reduction zone are connected by a narrowing, at which the cross-sectional area of ​​the furnace chamber decreases; the reduction zone is located downstream of the oxidation zone along the airflow direction; a separator (31) is connected to the end of the reduction zone; the calcining furnace (3) is connected to the preheater (1) and the waste heat boiler (2) through the separator (31); the discharge port of the separator (31) serves as the material outlet of the calcining furnace (3) and is connected to the cooler (4); the finished product collection system (5) is connected through the cooler (4). The separator (31) is a cyclone separator, and the water-cooled jacket (312) is a hollow container that surrounds the cone of the separator (31). The water-cooled jacket (312) is connected to the inlet and outlet water pipes, through which cooling water flows. In the water-cooling stage, the slag is cooled to below 570°C by water bath, which forces the residual ferrous oxide in the slag to decompose and generate iron(II,III) oxide and metallic iron. The cooling water and the material do not come into direct contact. Through heat exchange between the partition walls, the vaporized water is used as makeup water for the waste heat boiler (2).

2. The apparatus for calcining coal gangue according to claim 1, characterized in that: The preheater (1) consists of at least two preheaters connected in series.

3. The apparatus for calcining coal gangue according to claim 2, characterized in that: The preheater (1) is a cyclone preheater; the preheater (1) includes at least a first cyclone separator (11) and a second cyclone separator (12), and the first cyclone separator (11) and the second cyclone separator (12) are connected in series via connecting pipes.

4. The apparatus for calcining coal gangue according to claim 1, characterized in that: The finished product collection system (5) includes a collection cylinder (51) and a dust collector (52) connected to the collection cylinder (51); the dust collector (52) is connected to a finished product conveyor (53) and an induced draft fan (54).

5. The method of using the apparatus for calcining coal gangue according to claim 4, characterized in that, Includes the following steps: S1: Grind the raw materials into fine powder, wherein the raw materials include coal gangue; S2: The fine powder is preheated by the preheater (1) and then fed into the oxidation zone and reduction zone of the calcining furnace (3) respectively. After calcination, hot gas and slag are generated. S3: The hot gas is conditioned into coal gas, including: supplementing the oxidation zone with high-quality fuel, the high-quality fuel including the self-produced coal gas, and ensuring sufficient oxygen supply; generating high-temperature flue gas, when the high-temperature flue gas passes through the reduction zone, feeding the reduction zone with an excess of carbon-containing fuel, so that CO2 in the flue gas combines with carbonaceous matter to generate CO, and generating the CO-rich hot gas as coal gas. S4: After the gas is drawn out from the reduction zone, part of it is reused in the calcining furnace (3), and part of it is used as fuel for the kiln. S5: The hot gas is separated into gas and solid by the separator (31). The hot gas, after being pre-purified by the separator (31), is divided into two paths and enters the preheater (1) and the waste heat boiler (2) respectively. Among them, a portion of the hot gas is extracted into the preheater (1) at a ratio of 10-30% for preheating or drying coal gangue powder, and the remaining portion of the hot gas is introduced into the waste heat boiler (2) to generate steam for power generation, or the steam is used to directly drive the equipment. S6: The raw materials are calcined in the calcining furnace (3) to obtain slag, and the slag is separated from the gas flow by the separator (31); S7: The slag is cooled by the cooler (4), and the slag is collected by the finished product collection system (5) after cooling to obtain the finished product; wherein, the hot air obtained during the cooling process is drawn into the calcining furnace (3) as combustion air.

6. The method of using the apparatus for calcining coal gangue according to claim 5, characterized in that: A coil (311) is provided in the separator (31), and the coil (311) is used in combination with the heat exchanger (21). The coil (311) is a wound tube heat exchanger. And / or, a steam-electric dual-drive system is adopted, that is, the steam turbine and the electric motor jointly drive the main fan to run. The steam-electric dual-drive system includes a waste heat boiler (2), a steam-electric dual-drive turbine unit and a circulating water system. Through the heat exchanger (21), the 0.75 MPa(g) 300 ℃ superheated steam produced by the waste heat boiler (2) enters the steam inlet of the steam turbine. The exhaust steam after doing work is condensed into water through the condenser. The steam turbine condensate is sent to the deaerator for deoxygenation by the condensate pump, and then supplied to the waste heat boiler (2) by the feed water pump to form a steam Rankine thermal cycle system.

7. The method of using the apparatus for calcining coal gangue according to claim 5, characterized in that: During the calcination process, the outlet temperature of the reduction zone is controlled at 700-800℃; and the ratio of CO2 partial pressure to CO partial pressure is less than 0.

5. A CO detector is provided at the gas outlet of the reduction zone or the separator (31) to adjust the supply of raw materials and fuels in the reduction zone according to the CO content detection results. The material is cooled sequentially through a water cooling stage and an air cooling stage. The water cooling stage is completed by setting a water cooling jacket (312), and the air cooling stage is completed by the cooler (4). The gas is used to reduce iron oxides and prevent iron oxidation. In the water cooling stage, the slag is rapidly cooled to below 570°C by a water bath, which forces any residual ferrous oxide in the slag to decompose and generate magnetite and metallic iron. At the same time, an iron removal machine is set on the finished product conveying route. The iron removal machine is a dry magnetic separator used to remove magnetic substances from the product. The separator (31) is a cyclone separator, and the water-cooled jacket (312) is a hollow container that surrounds the cone of the separator (31). During the water-cooling stage, the discharge cone of the separator (31) is buried in the water-cooled jacket (312). The water-cooled jacket (312) is connected to the inlet and outlet water pipes to allow cooling water to flow. In addition, a material temperature-cooling water flow control loop is set up. By adjusting the flow rate of the cooling water, the material is cooled to below 570°C. The cooling water and the material do not come into direct contact. Through heat exchange between the partition walls, the vaporized water vapor is used as makeup water for the waste heat boiler (2).

8. The method of using the apparatus for calcining coal gangue according to claim 7, characterized in that: In the air-cooling stage, a suspension or fluidized bed cooler is used to cool the finished product; the cooler (4) is a suspension or fluidized bed cooler, and the cooler (4) includes: a first cooling cylinder (41), a second cooling cylinder (42), a first fluidized bed (43), and a second fluidized bed (44); the first cooling cylinder (41) is connected to the second cooling cylinder (42), the second cooling cylinder (42) is connected to the first fluidized bed (43), the first fluidized bed (43) is connected to the first cooling cylinder (41), and the first cooling cylinder (41) is also connected to the second fluidized bed (44); During normal operation, high-temperature material is discharged from the separator (31) and first fed into the rising pipe of the first cooling cylinder (41) to exchange heat with air. The material is cooled down and carried to the second cooling cylinder (42). The air is heated and then drawn into the calcining furnace (3) as combustion air. After being separated by the second cooling cylinder (42), the material is fed into the first fluidized bed (43). The first fluidized bed (43) draws in fresh cold air from the environment and blows the material with the help of the fluidizing fan of the first fluidized bed (43). After being further cooled, the material is drawn into the first cooling cylinder (41) with the air. After being collected by the first cooling cylinder (41), the material falls into the second fluidized bed (44) for final cooling. Then, the material is transported to the finished product collection system (5) through the air duct by pneumatic conveying. The pneumatic conveying air is first removed by the collection cylinder (51) to remove some of the particles, and then further filtered and purified by the dust collector (52), and is then drawn out and discharged by the induced draft fan (54); or, part of it is used as hot air for combustion or drying of raw materials; the dust collector (52) includes a bag dust collector or an electrostatic precipitator, and the collected material is the finished product, which is transported to the finished product warehouse by the finished product conveyor (53).

9. The method of using the apparatus for calcining coal gangue according to claim 8, characterized in that: The first fluidized bed (43) uses a fluidizing fan to draw in gas, which includes the coal gas, and mixes it with the fresh cold air. The first fluidized bed (43) uses an explosion-proof motor, a reinforced shaft sealing system to prevent leakage, and is equipped with a safety valve to avoid overpressure risks.

Images