A rotary kiln with ring formation suppression

Abstract

The utility model relates to material heat treatment technical field discloses a rotary kiln of inhibiting ring, and the rotary kiln includes feed inlet, kiln body and discharge gate, is equipped with screen system on the kiln body, the screen system includes screen grid and material leak channel, screen grid and material leak channel are all located in the kiln body of rotary kiln, screen grid communicates with rotary kiln inner chamber, material leak channel is located the just below of screen grid, and material leak channel communicates screen grid and rotary kiln outside, the utility model discloses through increasing screening device and powder and timely discharge channel in kiln body front section, realizes the fine screening to material before entering the high temperature calcination area (greater than 1000 DEG C) of rotary kiln, and the fine powder screened out is discharged from kiln body inside in time, avoids its with material entering high temperature area and causes ring problem.

Description

Technical Field

[0001] This utility model relates to the field of high-temperature roasting technology of materials, and specifically to a rotary kiln that suppresses ring formation. Background Technology

[0002] A rotary kiln is a type of thermal equipment widely used in industries such as metallurgy, building materials, and chemicals. It is mainly used for processes such as roasting, calcining, and drying of materials. Its structure includes components such as the kiln shell, kiln ring, and supporting rollers. The kiln shell is lined with refractory material, and continuous operation is achieved through rotation.

[0003] During oxidation or reduction roasting in conventional rotary kilns, material properties, high-temperature environment, and atmosphere requirements cause materials inside the kiln to adhere tightly to each other and grow continuously, forming ring-shaped deposits in the high-temperature section. When these rings reach a certain thickness, they obstruct the material flow, making it difficult for some materials to pass through the ring-forming section. Prolonged roasting in the high-temperature environment exacerbates ring growth. Furthermore, the growth of these rings reduces the actual inner diameter of the kiln, hindering airflow and causing changes in the kiln atmosphere and pressure, which can easily lead to production safety accidents such as explosions in the kiln head and tail settling chambers. Ring formation is a common and pressing technical problem that needs to be addressed during the operation of rotary kilns. Rings refer to the ring-shaped deposits formed on the inner wall of the rotary kiln. They not only reduce heat transfer efficiency but also reduce the cross-sectional area of ​​the kiln, affecting the normal flow of materials and the roasting effect. In severe cases, they can even cause kiln blockage, forcing the production line to shut down for maintenance, thereby reducing production efficiency and increasing maintenance costs.

[0004] The reasons for increased ring formation in rotary kilns are as follows: First, the calcined material itself has a low melting point, or the intermediate reactants or products formed during the calcination reaction have low melting points. The melting point of low-melting-point substances is lower than the reaction temperature, causing a large amount of liquid phase to form in the kiln. The liquid phase solidifies during the cooling process after passing through the high-temperature section, resulting in ring formation. Second, the temperature field distribution in the kiln is uneven, with local high temperatures exceeding the reaction temperature and the melting point of the material, causing an increase in the liquid phase. Third, the content of fine powder in the material is too high. Fine powder has a large specific surface area and high surface activity. During the reaction, on the one hand, it is very easy to form a micro-liquid phase, causing adhesion between powder particles. On the other hand, fine powder is relatively light and is very easy to be adsorbed on the rough surface of the kiln lining during the rotation of the rotary kiln. As the kiln rotates, the fine powder adsorbed on the surface of the kiln lining comes into contact with the high-temperature airflow in the kiln, and the temperature exceeds the reaction temperature of the material layer. In addition, the airflow atmosphere in the kiln is very different from the material layer atmosphere. For example, in a reduction kiln, the material layer has a strong reducing atmosphere, while the airflow contains a large amount of unconsumed oxygen. As the rotary kiln rotates, the fine powder adhering to the kiln wall is repeatedly reacted within the material layer and in the upper airflow atmosphere. During this repeated reaction, bonding bridges form at the contact interfaces between particles, gradually tightening under the pressure of the material layer, resulting in greater bonding strength. As the kiln rotates, new fine powder continuously re-adheres to the surface. This process repeats itself, causing the fine powder to accumulate, react, and compress, forming growing rings on the kiln wall, which hinders smooth production. Of these three factors, the characteristics of the material itself and the control of the reaction temperature field are determined by the requirements of the roasting process. Regardless of the material or roasting process, fine powder will inevitably be generated during production. Therefore, reducing the content of fine powder during roasting, especially the content entering the high-temperature reaction zone, is crucial for suppressing ring formation.

[0005] In rotary kiln production, materials are typically pelletized or briquetted before entering the kiln for reaction. During pelletizing and briquetting, green pellets and briquettes adhere to some powder that easily detaches during operation, and powder is also generated during transport due to friction. Additionally, during drying, some low-strength green pellets and briquettes burst, releasing powder. During roasting in the rotary kiln, as the temperature rises, the bonding bridges formed between particles in the dried pellets and briquettes by organic or volatile binders disappear, reducing the strength of the pellets / briquettes. When the material reaches a higher temperature range, oxidation or reduction reactions begin, establishing new bonding bridges between particles, and the strength begins to increase. Even as the strength of the pellets / briquettes decreases to its lowest point, friction between materials as the kiln rotates also generates a large amount of powder. These powders, as the pellets / briquettes move to the high-temperature reaction zone, exacerbate the ring formation phenomenon in the rotary kiln. Therefore, reducing the powder content or removing existing powder before the roasting reaction occurs in the rotary kiln is crucial for suppressing ring formation within the kiln.

[0006] The research team of this application previously proposed a lump ore pretreatment system and method based on an inner-tank rotary kiln, publication number CN 115164540 A. A nested drying and screening device (6) is installed inside the rotary kiln to screen the material. During the industrial operation of the system, it was found that although the system screened the material, the fine particles obtained after screening still existed inside the rotary kiln. After passing through the high-temperature roasting section of the rotary kiln, the fine particles still formed rings in the interlayer, affecting the normal operation of the rotary kiln. Furthermore, gas in the system easily leaked from the fine particle discharge port, making it difficult to control the atmosphere inside the rotary kiln and affecting the processing effect of the rotary kiln on the material. CN105674730B discloses an integrated iron ore sintering and screening machine, whose structure consists of a rotary kiln and a double-layer rotary screen. Large sintered iron ore blocks on the inner rotary screen are broken up by a pneumatic or electric beater, and unqualified small iron ore blocks are transported away by a screw conveyor. Although this solution achieves the function of material screening, it is mainly aimed at the processing of materials after sintering, rather than the processing of fine powders during the roasting process.

[0007] Therefore, regarding the current problems in rotary kilns, there is a lack of effective technical solutions for effectively reducing the content of fine powder during the roasting process, especially the content of fine powder entering the high-temperature reaction zone, in order to inhibit the ring formation phenomenon in the rotary kiln from the source. Most existing screening devices are located outside the rotary kiln or are used to process already roasted materials, and cannot remove fine powder in real time during the roasting process. There is an urgent need for a new type of rotary kiln system with a reasonable structural design, high screening efficiency, and the ability to effectively reduce the accumulation of fine particles inside the rotary kiln, and improve the thermal efficiency and operational stability of the kiln. Utility Model Content

[0008] To address the aforementioned issues, this application aims to resolve the ring formation problem in rotary kilns during the roasting process. The main causes are the low melting point of the material itself, uneven temperature distribution within the kiln, and excessively high content of fine powder in the material. In particular, it is necessary to solve how to reduce the content of fine powder during the roasting process, especially the content of fine powder entering the high-temperature reaction zone, in order to suppress the ring formation phenomenon in rotary kilns.

[0009] This application proposes an improved rotary kiln material handling system. By adding a pre-screening device and a powder collection structure at the front end of the kiln, it achieves fine screening of materials before they enter the high-temperature roasting zone, and promptly discharges the screened fine powder into the kiln, preventing it from forming rings when it enters the high-temperature zone. Simultaneously, the device, through an optimized sealing structure design, effectively prevents gas leakage, ensures a stable kiln atmosphere, and improves overall process stability and production efficiency. This invention, by adding a pre-screening device at the front end of the rotary kiln, allows materials to undergo preliminary screening before entering the high-temperature reaction zone, effectively reducing the amount of fine powder entering the high-temperature zone and lowering the risk of powder agglomeration and ring formation at high temperatures. Furthermore, the optimized powder collection structure allows for rapid discharge of the screened fine powder outside the kiln, preventing secondary adhesion and ring formation caused by its circulation within the kiln. In addition, a highly efficient sealing structure at the connection between the screening device and the kiln significantly reduces gas leakage from the fine particle discharge port, thereby ensuring stable thermal conditions within the kiln and improving material roasting quality and production continuity.

[0010] According to the first embodiment of this utility model, a rotary kiln for suppressing ring formation is provided.

[0011] A rotary kiln for suppressing ring formation includes a feed inlet, a kiln body, and a discharge outlet. A screen system is installed on the kiln body. The screen system includes screen grids and a material discharge channel. Both the screen grids and the material discharge channel are located within the kiln body. The screen grids communicate with the inner cavity of the rotary kiln. The material discharge channel is located directly below the screen grids and connects the screen grids to the outside of the rotary kiln.

[0012] In this invention, the material discharge channel penetrates the kiln body of the rotary kiln. A sieve is positioned on the side of the material discharge channel closest to the inner cavity of the rotary kiln. The upper surface of the sieve is flush with the inner surface of the rotary kiln lining. The other end of the material discharge channel communicates with the outside of the rotary kiln.

[0013] Preferably, a double-layer discharge valve is installed in the material discharge channel.

[0014] Preferably, the double-layer discharge valve is a double-layer interlocking conical discharge valve. The double-layer interlocking conical discharge valve includes two conical discharge valves: an inner conical discharge valve and an outer conical discharge valve. The inner conical discharge valve includes an inner fixed half-conical valve and an inner movable half-conical valve. Rotating the inner movable half-conical valve causes it to overlap with or form a conical shape with the inner fixed half-conical valve. The outer conical discharge valve includes an outer fixed half-conical valve and an outer movable half-conical valve. Rotating the outer movable half-conical valve causes it to overlap with or form a conical shape with the outer fixed half-conical valve. The inner fixed half-conical valve is located inside the outer movable half-conical valve, and the inner movable half-conical valve is also located inside the outer fixed half-conical valve. The inner and outer movable half-conical valves are connected by a rotating shaft, which drives both valves to rotate simultaneously.

[0015] Preferably, the rotary kiln also includes a drive unit, which is connected to the rotating shaft and drives the rotating shaft to rotate, thereby causing the inner movable semi-cone valve and the outer movable semi-cone valve to rotate simultaneously.

[0016] Preferably, the rotary kiln is also equipped with a sealing ring on its outer side. The sealing ring is located around the outer perimeter of the rotary kiln. A material discharge channel is located at the bottom of the sealing ring. An ash discharge valve is installed inside the material discharge channel.

[0017] Preferably, the material discharge channel is equipped with two or more layers of ash discharge valves.

[0018] Preferably, the rotary kiln also includes a lever connected to the rotating shaft. A lever baffle is provided on the outside of the rotary kiln. As the rotary kiln rotates, the lever baffle intermittently contacts the lever, causing the lever to move and driving the rotating shaft to rotate.

[0019] Preferably, the lever baffle is disposed on the sealing ring.

[0020] In this invention, the screen system is located in the upstream and / or midstream section of the rotary kiln body.

[0021] Preferably, the screen system is set in the 0-2 / 3 length region of the rotary kiln body near the feed inlet.

[0022] Preferably, the material discharge channel is a circular channel. The unfolded surface of the sieve grid is circular, square, or polygonal. The sieve grid covers directly above the material discharge channel.

[0023] Preferably, the rotary kiln is equipped with n independent screen systems, which are evenly distributed around the kiln body.

[0024] Preferably, n is 2-100, more preferably 3-80, and even more preferably 4-60.

[0025] Preferably, n independent screen systems are arranged in one or more rings around the kiln body of the rotary kiln.

[0026] Preferably, n independent screen systems are arranged in multiple rings and are evenly and staggered around the kiln body of the rotary kiln.

[0027] Preferably, the rotary kiln also includes a lifting plate. The lifting plate is located upstream of the screen system.

[0028] According to the second embodiment of this utility model, a method for roasting using a rotary kiln with ring-suppressing technology as described in the first embodiment is provided.

[0029] A method for firing using the aforementioned ring-suppressing rotary kiln, the method comprising the following steps:

[0030] S1. The material to be processed is conveyed from the rotary kiln feed port to the rotary kiln.

[0031] S2. As the rotary kiln rotates, the material passes through the rotary kiln's screen system. The screens separate the material to be processed, and the fine particles below the screens are discharged through the material discharge channel. The coarse particles continue to pass through the high-temperature section of the rotary kiln for roasting treatment, and then are discharged from the rotary kiln's discharge port.

[0032] Preferably, the method further includes the following steps:

[0033] S01. The material to be processed is pelletized or granulated before being conveyed to the rotary kiln.

[0034] Preferably, the fine particulate material is discharged from the material leakage channel and returned to step S01.

[0035] In this invention, the overall structure of the rotary kiln includes a feed inlet, a kiln body, and a discharge outlet. The feed inlet is located at one end of the rotary kiln and is used to transport the material to be processed into the interior of the rotary kiln. The kiln body is the main part of the rotary kiln, is cylindrical, and can rotate around its axis. The discharge outlet is located at the other end of the rotary kiln and is used to discharge the processed material from the rotary kiln.

[0036] The sieve is installed inside the rotary kiln and communicates with the kiln's inner cavity. The sieve's structure is mesh-like, allowing materials meeting specific particle size requirements to pass through while blocking larger particles or agglomerated materials. The mesh size is designed according to the characteristics of the material being processed, ensuring effective separation of materials that may form agglomerates. The sieve rotates with the rotary kiln; during rotation, the material continuously contacts the sieve, allowing finer materials to pass through.

[0037] The material discharge channel is located directly below the screen, forming a closed channel structure connecting the screen and the outside of the rotary kiln. After passing through the screen, the material falls into the discharge channel and is guided to the outside of the rotary kiln. The design of the material discharge channel ensures that the material can be discharged from the inside of the rotary kiln in a timely and smooth manner, preventing accumulation and ring formation within the kiln.

[0038] During rotary kiln operation, material enters the kiln body through the feed inlet. As the kiln rotates, the material moves within and undergoes heat treatment. Throughout this process, the screen system continuously operates, separating any material that may form rings through the screen grids. This separated material is then discharged from the rotary kiln through the material discharge channel, effectively suppressing ring formation. Finally, the processed material is discharged from the discharge port.

[0039] The rotary kiln for suppressing ring formation provided by this utility model, through the setting of the screen system, can continuously separate materials that may form rings during the heat treatment of materials and discharge them from the kiln body in a timely manner, fundamentally solving the problem of ring formation during the operation of the rotary kiln, and improving production efficiency and equipment service life.

[0040] In this invention, when the rotary kiln is in operation, the material inside the kiln rotates with the kiln body and moves towards the discharge port. During this process, when the material passes through the screen, material that meets the screen aperture requirements will fall through the screen into the material discharge channel below and be discharged outside the kiln. Larger materials will continue to move inside the kiln and be further processed. The screen system effectively separates materials prone to clumping from the kiln, preventing them from forming rings inside.

[0041] In this invention, a double-layer discharge valve is installed within the material discharge channel, which is another important innovation of this rotary kiln. The double-layer discharge valve can control the material discharge rate, preventing excessively rapid material discharge that could lead to production instability. Simultaneously, the double-layer discharge valve design also prevents high-temperature gas inside the rotary kiln from leaking out through the material discharge channel, ensuring production safety and thermal energy utilization efficiency. The double-layer discharge valve design not only controls the material discharge rate but also prevents high-temperature gas leakage. When the upper valve is open, the lower valve is closed; when the lower valve is open, the upper valve is closed. This alternating operation ensures smooth material discharge while preventing high-temperature gas leakage.

[0042] Furthermore, this utility model provides a double-layer interlocking conical discharge valve with a special structure. The double-layer interlocking conical discharge valve includes two conical discharge valves: an inner conical discharge valve and an outer conical discharge valve. The inner conical discharge valve includes an inner fixed half-conical valve and an inner movable half-conical valve. Rotating the inner movable half-conical valve causes it to overlap with or form a conical shape with the inner fixed half-conical valve. The outer conical discharge valve includes an outer fixed half-conical valve and an outer movable half-conical valve. Rotating the outer movable half-conical valve causes it to overlap with or form a conical shape with the outer fixed half-conical valve. The inner fixed half-conical valve is located inside the outer movable half-conical valve, and vice versa. The inner and outer movable half-conical valves are connected by a rotating shaft, which drives both valves to rotate simultaneously. Through the above structural design, the double-layer interlocking conical discharge valve not only achieves efficient material discharge but also further improves sealing performance, preventing the escape of high-temperature gas from the kiln during the discharge process, thus enhancing thermal energy utilization and production safety. This discharge valve features a compact design and flexible operation. Furthermore, the synchronous drive of the inner and outer movable semi-conical valves via a rotating shaft ensures coordinated operation of the two valve layers, preventing leakage risks caused by misoperation.

[0043] The working principle of the double-layer interlocking conical discharge valve is based on the linkage mechanism of the inner and outer valves. When material enters the inner conical discharge valve, the inner movable half-cone valve and the inner fixed half-cone valve rotate to form a material passage, and the material then enters the outer conical discharge valve. At this time, the outer movable half-cone valve and the outer fixed half-cone valve are in the closed state to prevent high-temperature gas backflow. When discharge is required, the rotating shaft drives the outer movable half-cone valve to align with the outer fixed half-cone valve, opening the outer passage, while the inner movable half-cone valve automatically closes, thus ensuring that high-temperature gas does not leak. This cycle repeats, achieving continuous and stable material discharge while effectively preventing gas leakage.

[0044] In this invention, the double-layer interlocking conical discharge valve can independently control the opening and closing of the inner and outer conical discharge valves via a drive device. The drive device includes a motor, a reducer, and a transmission shaft. The transmission shaft is connected to a rotating shaft, and the motor drives the reducer to rotate the transmission shaft, thereby achieving synchronous rotation of the rotating shaft. The motor can be a variable frequency motor, and the motor speed can be adjusted via the frequency converter to achieve precise control of the opening and closing angles of the inner and outer movable half-cone valves. Furthermore, the drive device is also equipped with a PLC control system, which can set the valve opening and closing sequence according to the needs of the production process, thereby achieving automated material discharge operation, improving production efficiency, and reducing the degree of manual intervention.

[0045] Furthermore, the double-layer interlocking conical discharge valve can also be opened and closed using a purely mechanical device. The rotary kiln also includes a lever connected to the rotating shaft. A lever baffle is located on the outside of the rotary kiln. As the rotary kiln rotates, the lever baffle intermittently contacts the lever, causing the lever to vibrate and driving the rotating shaft to rotate. When the rotary kiln rotates to a set angle, the lever baffle contacts the lever and pushes it to rotate, thereby driving the rotating shaft and the connected inner and outer movable semi-cone valves to move synchronously. The orderly opening and closing of the inner and outer valves can be achieved by setting the relative position between the lever baffle and the lever. This mechanical linkage method requires no external power source; valve operation is completed by the rotation of the kiln itself. It has a simple structure, is easy to maintain, and ensures precise matching with the kiln's operating cycle, improving system stability and reliability. The lever rotates with the kiln, while the lever baffle is fixed at a specific position on the kiln and does not rotate with the kiln, thus achieving relative movement between the lever and the lever baffle. The lever is connected to the rotating shaft on the double-layer interlocking conical discharge valve. When the lever rotates with the kiln body to the position where it contacts the lever baffle, the baffle exerts a thrust on the lever, driving the rotating shaft to rotate, thereby actuating the inner and outer movable semi-cone valves. This mechanical linkage structure not only saves energy but also responds quickly, making it suitable for continuous production environments with precise requirements for discharge cycles. By adjusting the relative position of the lever baffle and the lever, the valve opening and closing times can be flexibly set to adapt to different production process requirements. Simultaneously, this structure avoids potential fault points in the electrical control system, improving the overall stability and safety of the equipment.

[0046] In a preferred embodiment of this invention, a sealing ring is also provided on the outer side of the rotary kiln. The sealing ring is concentrically positioned with the rotary kiln and fixed at a corresponding location on the outside of the kiln, serving to seal and protect the connection between the double-layer interlocking conical discharge valve and the kiln body. The sealing ring is made of wear-resistant and high-temperature-resistant material, effectively preventing dust leakage and the entry of external air into the kiln, thereby maintaining a stable atmosphere inside the kiln and improving the safety and environmental performance of the equipment.

[0047] In this invention, the screen system is located in the upstream and / or midstream section of the rotary kiln. The screen system screens the material before it enters the high-temperature section of the rotary kiln, removing dust and small particles and discharging them promptly outside the kiln. This prevents dust from melting and forming rings in the high-temperature environment. The screen system consists of multiple screen units evenly distributed along the circumference of the kiln body, and each unit can be independently disassembled and replaced for easy maintenance and cleaning. The screen aperture is rationally selected based on the material characteristics to ensure effective removal of fine powder without affecting material flow. The screen system rotates synchronously with the kiln body, utilizing centrifugal force to enhance the screening effect and further improve screening efficiency.

[0048] In a second embodiment of this utility model, a rotary kiln firing method is provided, comprising the following steps:

[0049] Step 1: Material Conveying

[0050] The material to be processed is conveyed from the rotary kiln inlet into the kiln. This material can be ore, ceramic raw materials, cement clinker, solid waste, or other materials requiring high-temperature roasting. Material conveying can be accomplished using equipment such as screw conveyors, belt conveyors, or vibrating feeders, ensuring that the material enters the rotary kiln uniformly and stably. The conveying rate can be adjusted according to the rotary kiln's processing capacity and the material characteristics, generally controlled between 5 and 20 tons per hour.

[0051] Step 2: Rotary kiln rotates

[0052] The rotary kiln rotates at a speed of 2-5 revolutions per minute, causing the material to move slowly along the axial direction within the kiln. The tilt angle of the rotary kiln is 3-5 degrees, ensuring that the material can flow naturally under the influence of gravity. The rotation of the rotary kiln causes the material to tumble continuously, increasing the contact area between the material and the heat source and improving heat transfer efficiency.

[0053] Step 3: Material screening

[0054] As the rotary kiln rotates, the material passes through a screen system installed inside the kiln. The screen system consists of multiple sieves that separate the material. The mesh size of the sieves ranges from 1 to 5 millimeters and can be adjusted according to material characteristics and process requirements. The sieves are made of high-temperature resistant alloy material and can operate stably for extended periods at temperatures of 1000-1500℃. The sieves are located in the middle section of the rotary kiln, where the material has undergone preliminary preheating but has not yet been fully roasted.

[0055] Step 4: Fine particles are discharged

[0056] Fine particles below the sieve are discharged through the material discharge channel. This channel, located directly below the sieve, has a diameter of 50-100 mm and its inner wall is lined with a wear-resistant material to prevent abrasion. Since the fine particles are typically smaller than the sieve mesh size, they have already met the process requirements and do not require further roasting; direct discharge saves energy and improves production efficiency. After discharge, the fine particles enter a cooling system for further cooling.

[0057] Step 5: Coarse Particle Roasting

[0058] Coarse particles that fail to pass through the sieve continue to be roasted in the high-temperature section of the rotary kiln. The temperature in the high-temperature section is controlled between 900-1400℃, and can be adjusted according to the roasting requirements of different materials. The roasting time is 30-90 minutes. Under the action of high temperature, the coarse particles undergo physicochemical reactions to achieve the desired roasting effect. Natural gas, pulverized coal, or other fuels are used as heat sources in the high-temperature section, providing stable heat through burners.

[0059] Step Six: Discharge of Finished Product

[0060] The fully roasted coarse particles are discharged from the discharge port of the rotary kiln. The discharge port is located at the end of the rotary kiln, and the temperature of the discharged material is typically 600-800℃. The discharged material enters a cooler for cooling, and the temperature of the cooled material drops to below 100℃, facilitating subsequent processing and storage.

[0061] Specifically, the process for metallurgy using the rotary kiln system provided by this utility model is as follows:

[0062] (1) The raw materials are first thoroughly mixed with the binder and water: The raw materials include concentrates or fines of various metal ores, coal powder, coal ash, metallurgical dust, metallurgical sludge, etc.; the binder can be selected from organic binders such as humic acid, sodium humate, polyvinyl alcohol, waste molasses, coal tar, methylene cellulose, sodium methylene cellulose, starch, etc., and / or one or more of the following five-level binders: bentonite, sodium silicate, hydrated lime, quicklime, cement, and metallic iron powder. The role of the binder is to provide the cold strength and part of the thermal strength of the lumps, and the binder ratio is 0% to 20%.

[0063] (2) The mixed material is pelletized or briquetted. If briquetting is used, the briquettes are spherical or blocky. The particle size range of raw pellets / briquettes is 3-80mm. After screening, raw pellets / briquettes that do not meet the particle size range are returned to the mixing process.

[0064] (3) After screening, the green pellets / lumps that meet the particle size requirements enter the drying process. The drying process can be carried out by means of chain grate machine, steel mesh belt machine, etc., and the drying medium can be hot air, microwave, etc.

[0065] (4) After drying, the pellets / lumps are screened and then fed into the kiln. For example, the screened particle size is 3mm. Particles smaller than 3mm are returned to the mixing process, while those larger than 3mm are fed into the rotary kiln. Screening equipment for feeding into the kiln can include drum screens, vibrating screens, roller screens, etc.

[0066] (5) After screening, the dried pellets / lumps enter the rotary kiln from the kiln tail. As the kiln rotates, they tumble towards the kiln head and continuously heat up. Before new bonding bridges are established between the particles inside the pellets / lumps, the dried pellets / lumps rub against each other, generating powder. When the material temperature reaches 500-600℃, the rotary kiln is equipped with staggered strip-shaped screens, with a screen width of, for example, 3mm. After passing through the screens, the larger pellets / lumps continue to move towards the high-temperature section at the kiln head, while the fine powder passes through the powder drop material leakage channel and is discharged outside the kiln body after passing through a double-layer discharge valve. In this process, the timely separation of fine powder effectively avoids softening and agglomeration caused by prolonged residence time in the high-temperature area, thereby further reducing the risk of ring formation. At the same time, the screen structure is reasonably designed to adapt to the screening requirements of materials with different particle sizes, ensuring stable screening efficiency. After the powder is removed by sieving, the pellets / lumps continue to run towards the kiln head and heat up. The strength of the pellets gradually increases. When they reach the high-temperature reaction section, the amount of powder produced is very small, which effectively suppresses the ring formation phenomenon in the rotary kiln.

[0067] As a preferred embodiment, this utility model employs a double-layer conical discharge valve. The upper and lower cone valves of the double-layer conical discharge valve open in a staggered manner by rotating the kiln body and moving the lever, ensuring that the gas inside the kiln does not leak while the powder is discharged. The powder enters the ash collection hopper and is discharged through the double-layer ash discharge valve, again ensuring that the gas inside the kiln does not leak. The discharged powder is returned to the mixing process and reused for pelletizing.

[0068] Further optimization involves a complete sealing ring surrounding the kiln body, which seals the kiln body through the dynamic and static joint surfaces to prevent external air from leaking into the kiln.

[0069] In this invention, the powder is separated from the dried pellets / clumps by screening before entering the kiln, and a screening mechanism is installed inside the kiln to reduce the powder content in the high-temperature section and inhibit ring formation. The kiln screening device has the following structure: For example, the kiln has four interlaced screens, which are distributed alternately and surround the kiln to ensure thorough powder screening. To ensure no gas leakage inside the kiln, a double-layer interlocked conical discharge valve and a double-layer ash discharge valve in the discharge channel are opened sequentially to ensure powder discharge and kiln gas sealing. After being screened, the powder enters the material discharge channel, which is equipped with a double-layer interlocked conical discharge valve. As the kiln rotates, the double-layer interlocked conical discharge valve is twisted by the lever baffle on the sealing ring, causing the upper and lower discharge valves to open and close alternately. For example, during the kiln's rotation, the double-layer interlocking conical discharge valve lever is activated by the lever baffle, causing the rotating shaft to rotate. The outer conical discharge valve closes, while the inner and outer conical discharge valves open simultaneously. At this time, the sieve enters the material zone, and the powder passes through the sieve into the material discharge channel, passing through the inner and outer conical discharge valves, where it is blocked by the outer conical discharge valve. When the rotation reaches another lever baffle, the rotating shaft rotates again, closing the inner and outer conical discharge valves and opening the outer conical discharge valve, allowing the powder to be discharged from the outer conical discharge valve. Then, the double-layer ash discharge valves in the discharge channel are opened and closed sequentially to discharge the powder. This ingenious design not only ensures continuous powder discharge but also prevents the leakage of high-temperature gases from the kiln, thus improving the overall safety and environmental friendliness of production. Furthermore, the discharged powder, after being collected by the collecting device, can be directly returned to the mixing process, achieving resource recycling and reducing raw material waste. The organic combination of the screening and discharge mechanisms effectively reduces the risk of ring formation within the kiln, improving kiln operational stability and production efficiency.

[0070] In this invention, one sieve 101 corresponds to one material discharge channel 102. The sieves and material discharge channels are vertically distributed to ensure that the powder falls quickly into the channel under gravity. A double-layer interlocking conical discharge valve 2 is located at the end of the material discharge channel. Its upper and lower discharge valves are alternately opened and closed via a mechanical linkage device, ensuring continuous powder discharge while maintaining a sealed environment inside the kiln. The outer and inner discharge valves of the double-layer interlocking conical discharge valve are synchronized with the kiln rotation mechanism, periodically switching states as the kiln rotates. For example, when the kiln rotates to a specific angle, the linkage mechanism triggers the outer discharge valve to close and the inner discharge valve to open, allowing the powder to temporarily enter between the two valves. When the kiln continues to rotate to the next set angle, the inner discharge valve closes and the outer discharge valve opens, discharging the temporarily stored powder into the discharge channel. This structure effectively prevents gas leakage by precisely controlling the discharge rhythm, improving the operational stability and environmental performance inside the kiln. Furthermore, a double-layer ash discharge valve 301 is installed in the discharge channel 3. The upper and lower ash discharge valves are controlled by pneumatic or hydraulic drive devices to achieve sequential opening and closing, ensuring the airtightness of the gas inside the kiln during the discharge process. The double-layer interlocking conical discharge valve 2 rotates with the kiln body, maintaining a relatively stationary state relative to the kiln body, thereby avoiding sealing failure caused by relative movement. The double-layer ash discharge valve is installed on the sealing ring, and the double-layer ash discharge valve and the sealing ring remain stationary relative to the kiln body, further ensuring the stability of the sealing environment inside the kiln. The sealing ring and the kiln body are connected by a dynamic-static combination component, such as a bearing, to achieve dynamic sealing when the kiln body rotates. Through the design of the dynamic-static combination component, both the flexibility of the kiln body rotation and the stability of the sealing ring are ensured, thereby achieving efficient dynamic sealing. At the same time, this structure effectively isolates the high-temperature gas inside the kiln from the external environment, reducing heat loss and environmental pollution. The overall design is compact and reliable in operation, not only improving the safety of the kiln system but also significantly reducing maintenance frequency and costs. In addition,

[0071] In this invention, the length of the rotary kiln is 10-50 meters, preferably 12-40 meters, and more preferably 15-30 meters. The inner diameter of the kiln body is 1-6 meters, preferably 1.5-5 meters, and more preferably 2-4 meters. The tilt angle of the rotary kiln is 2-20°, preferably 3-15°, and more preferably 4-10°. The rotational speed of the rotary kiln is 0.5-5 revolutions per minute, preferably 1-3 revolutions per minute, and more preferably 1.5-2.5 revolutions per minute. A refractory material layer with a thickness of 50-300 mm is provided inside the kiln body, preferably 100-250 mm, and more preferably 150-200 mm. The screening mechanism is installed in the middle-front section inside the kiln body, after the drying and preheating area, to avoid the influence of high temperature on the screening effect. The screen grid is made of high-temperature resistant alloy material, which has good wear resistance and deformation resistance, ensuring long-term stable screening efficiency. The material discharge channel is located below the screening mechanism and symmetrically distributed with respect to the center of rotation of the kiln body to facilitate uniform powder discharge. The aperture of the sieve is selected according to the powder particle size distribution, generally 2-20 mm, preferably 2.5-15 mm, and more preferably 3-10 mm, to ensure screening accuracy and permeability. The inner diameter of the material discharge channel 102 is 50-300 mm, preferably 80-250 mm, and more preferably 100-200 mm, to ensure smooth powder discharge and reduce the impact of airflow disturbance. A guide plate is provided at the connection between the material discharge channel and the screening mechanism to prevent material blockage and improve channel flow efficiency; the connection between the material discharge channel and the screening mechanism is generally conical. The conical structure can effectively disperse material flow stress, reduce the risk of blockage, and promote uniform powder flow into the material discharge channel. The cone angle of the conical material discharge channel is 30°-60°, preferably 40°-50°, and more preferably 45°, to ensure smooth material flow and prevent accumulation.

[0072] Compared with the prior art, the technical solution provided by this utility model has the following beneficial technical effects:

[0073] 1. By setting up a screening mechanism inside the kiln, powder in the high-temperature section can be effectively separated, thereby reducing the accumulation of powder in the high-temperature section, avoiding the occurrence of ring formation, and improving the stability and thermal efficiency of kiln operation.

[0074] 2. The design of the double-layer interlocking conical discharge valve not only achieves efficient powder discharge, but also effectively prevents gas leakage inside the kiln, improving the system's sealing and safety.

[0075] 3. The double-layer ash discharge valve installed in the discharge channel further ensures the sealing effect of the system, avoids the problem of gas backflow or dust overflow during the unloading process, and ensures the environmental protection and operational safety of the production process.

[0076] 4. The coordinated design of the screening and unloading mechanism significantly shortens the residence time of powder in the kiln, reduces the probability of material adhesion in the kiln, and further inhibits the formation of rings. Attached Figure Description

[0077] Figure 1 This is a schematic diagram of a screen system installed on the kiln body of a rotary kiln to suppress ring formation, according to the present invention.

[0078] Figure 2 This is a cross-sectional view of a rotary kiln for suppressing ring formation according to the present invention, perpendicular to the length of the rotary kiln.

[0079] Figure 3 This is a schematic diagram of the structure of a double-layer interlocked conical discharge valve for suppressing ring formation on a rotary kiln, with the inner conical discharge valve in the open state.

[0080] Figure 4 This is a schematic diagram of the structure of a double-layer interlocked conical discharge valve for suppressing ring formation on a rotary kiln, with the outer conical discharge valve in the open state, according to the present invention.

[0081] Figure 5 This is a schematic diagram of a rotary kiln screen system for suppressing ring formation according to the present invention.

[0082] Figure 6 This is a schematic diagram of a rotary kiln with a sealing ring for suppressing ring formation according to the present invention.

[0083] Figure label:

[0084] 1: Screening system; 101: Screen grid; 102: Material discharge channel; 2: Double-layer interlocking cone discharge valve; 201: Inner cone discharge valve; 202: Outer cone discharge valve; 20101: Inner fixed half-cone valve; 20102: Inner movable half-cone valve; 20201: Outer fixed half-cone valve; 20202: Outer movable half-cone valve; 104: Rotating shaft; 3: Sealing ring; 301: Material discharge channel; 302: Ash discharge valve; 4: Lever; 5: Lever baffle; 6: Lifting plate. Detailed Implementation

[0085] The technical solution of this utility model is illustrated below. The scope of protection of this utility model includes, but is not limited to, the following embodiments.

[0086] A rotary kiln for suppressing ring formation includes a feed inlet, a kiln body, and a discharge outlet. A screen system 1 is provided on the kiln body. The screen system 1 includes a screen grid 101 and a material discharge channel 102. Both the screen grid 101 and the material discharge channel 102 are located within the kiln body. The screen grid 101 communicates with the inner cavity of the rotary kiln. The material discharge channel 102 is located directly below the screen grid 101 and connects the screen grid 101 to the outside of the rotary kiln.

[0087] In this invention, the material discharge channel 102 penetrates the kiln body of the rotary kiln. A sieve 101 is positioned on the side of the material discharge channel 102 closest to the inner cavity of the rotary kiln. The upper surface of the sieve 101 is flush with the inner surface of the rotary kiln lining. The other end of the material discharge channel 102 communicates with the outside of the rotary kiln.

[0088] Preferably, a double-layer unloading valve is provided in the material discharge channel 102.

[0089] Preferably, the double-layer discharge valve is a double-layer interlocking conical discharge valve 2. The double-layer interlocking conical discharge valve 2 includes two conical discharge valves: an inner conical discharge valve 201 and an outer conical discharge valve 202. The inner conical discharge valve 201 includes an inner fixed half-conical valve 20101 and an inner movable half-conical valve 20102. Rotating the inner movable half-conical valve 20102 causes it to overlap with or form a conical shape with the inner fixed half-conical valve 20101. The outer conical discharge valve 202 includes an outer fixed half-conical valve 20201 and an outer movable half-conical valve 20202. Rotating the outer movable half-conical valve 20202 causes it to overlap with or form a conical shape with the outer fixed half-conical valve 20201. The inner fixed semi-cone valve 20101 is located inside the outer movable semi-cone valve 20202, and the inner movable semi-cone valve 20102 is located inside the outer fixed semi-cone valve 20201. The inner movable semi-cone valve 20102 and the outer movable semi-cone valve 20202 are connected by a rotating shaft 104, which drives both the inner movable semi-cone valve 20102 and the outer movable semi-cone valve 20202 to rotate simultaneously.

[0090] Preferably, the rotary kiln also includes a drive device, which is connected to the rotating shaft 104 and drives the rotating shaft 104 to rotate, thereby causing the inner movable semi-cone valve 20102 and the outer movable semi-cone valve 20202 to rotate simultaneously.

[0091] Preferably, the rotary kiln is also provided with a sealing ring 3 on its outer side. The sealing ring 3 is arranged around the outer perimeter of the rotary kiln. A material discharge channel 301 is provided at the bottom of the sealing ring 3. An ash discharge valve 302 is provided inside the material discharge channel 301.

[0092] Preferably, the material discharge channel 301 is equipped with two or more layers of ash discharge valves 302.

[0093] Preferably, the rotary kiln also includes a lever 4 connected to the rotating shaft 104. A lever baffle 5 is provided on the outside of the rotary kiln. As the rotary kiln rotates, the lever baffle 5 intermittently contacts the lever 4, causing the lever 4 to move and driving the rotating shaft 104 to rotate.

[0094] Preferably, the lever baffle 5 is disposed on the sealing ring 3.

[0095] In this invention, the screen system 1 is located in the upstream and / or midstream section of the rotary kiln body.

[0096] Preferably, the screen system 1 is set in the 0-2 / 3 length region of the rotary kiln body near the feed inlet.

[0097] Preferably, the material discharge channel 102 is a circular channel. The unfolded surface of the sieve grid 101 is circular, square, or polygonal. The sieve grid 101 covers the material discharge channel 102 directly above it.

[0098] Preferably, the rotary kiln is equipped with n independent screen systems 1, which are evenly distributed around the kiln body.

[0099] Preferably, n is 2-100, more preferably 3-80, and even more preferably 4-60.

[0100] Preferably, n independent screen systems are arranged in one or more rings around the kiln body of the rotary kiln.

[0101] Preferably, n independent screen systems are arranged in multiple rings and are evenly distributed around the kiln body of the rotary kiln in a staggered manner.

[0102] Preferably, the rotary kiln also includes a lifting plate 6. The lifting plate 6 is located upstream of the screen system 1.

[0103] Example 1

[0104] like Figure 1 As shown, a rotary kiln for suppressing ring formation includes a feed inlet, a kiln body, and a discharge outlet. A screen system 1 is provided on the kiln body. The screen system 1 includes a screen grid 101 and a material discharge channel 102. Both the screen grid 101 and the material discharge channel 102 are located within the kiln body. The screen grid 101 communicates with the inner cavity of the rotary kiln. The material discharge channel 102 is located directly below the screen grid 101 and connects the screen grid 101 to the outside of the rotary kiln.

[0105] Example 2

[0106] The embodiment 1 is repeated, except that the material discharge channel 102 penetrates the kiln body of the rotary kiln. A sieve 101 is positioned on the side of the material discharge channel 102 near the inner cavity of the rotary kiln. The upper surface of the sieve 101 is flush with the inner surface of the rotary kiln lining. The other end of the material discharge channel 102 communicates with the outside of the rotary kiln.

[0107] Example 3

[0108] Repeat Example 2, as follows Figure 2 As shown, a double-layer unloading valve is provided in the material leakage channel 102.

[0109] Example 4

[0110] Repeat Example 3, as follows Figure 3-4 As shown, the double-layer discharge valve is a double-layer interlocking conical discharge valve 2. The double-layer interlocking conical discharge valve 2 includes two conical discharge valves: an inner conical discharge valve 201 and an outer conical discharge valve 202. The inner conical discharge valve 201 includes an inner fixed half-conical valve 20101 and an inner movable half-conical valve 20102. Rotating the inner movable half-conical valve 20102 causes it to overlap with or form a conical shape with the inner fixed half-conical valve 20101. The outer conical discharge valve 202 includes an outer fixed half-conical valve 20201 and an outer movable half-conical valve 20202. Rotating the outer movable half-conical valve 20202 causes it to overlap with or form a conical shape with the outer fixed half-conical valve 20201. The inner fixed semi-cone valve 20101 is located inside the outer movable semi-cone valve 20202, and the inner movable semi-cone valve 20102 is located inside the outer fixed semi-cone valve 20201. The inner movable semi-cone valve 20102 and the outer movable semi-cone valve 20202 are connected by a rotating shaft 104, which drives both the inner movable semi-cone valve 20102 and the outer movable semi-cone valve 20202 to rotate simultaneously.

[0111] Example 5

[0112] Repeat Example 4, except that the rotary kiln also includes a drive device, which is connected to the rotating shaft 104 and drives the rotating shaft 104 to rotate, thereby causing the inner movable semi-cone valve 20102 and the outer movable semi-cone valve 20202 to rotate simultaneously.

[0113] Example 6

[0114] Repeat Example 4, as follows Figure 6 As shown, the rotary kiln is further equipped with a sealing ring 3 on its outer side. The sealing ring 3 is located around the outer perimeter of the rotary kiln. A material discharge channel 301 is located at the bottom of the sealing ring 3. An ash discharge valve 302 is located inside the material discharge channel 301.

[0115] Example 7

[0116] The same as Example 6 is repeated, except that two layers of ash discharge valves 302 are provided in the material discharge channel 301.

[0117] Example 8

[0118] The embodiment 4 is repeated, except that the rotary kiln also includes a lever 4, which is connected to the rotating shaft 104. A lever baffle 5 is provided on the outside of the rotary kiln. As the rotary kiln rotates, the lever baffle 5 intermittently contacts the lever 4, causing the lever 4 to move and driving the rotating shaft 104 to rotate.

[0119] Example 9

[0120] The embodiment 7 is repeated, except that the rotary kiln also includes a lever 4, which is connected to the rotating shaft 104. A lever baffle 5 is provided on the outside of the rotary kiln. As the rotary kiln rotates, the lever baffle 5 intermittently contacts the lever 4, causing the lever 4 to move and driving the rotating shaft 104 to rotate. The lever baffle 5 is mounted on the sealing ring 3.

[0121] Example 10

[0122] Repeat Example 2, except that the screen system 1 is set in the area from the feed inlet to 1 / 2 of the front section of the rotary kiln body.

[0123] Example 11

[0124] Repeat Example 9, except that the screen system 1 is set in the area of ​​the front section of the rotary kiln body near the feed inlet, which is 1 / 3 to 1 / 2 of the way in.

[0125] Example 12

[0126] Example 9 is repeated, except that the screen system 1 is set in the area of ​​the front section of the rotary kiln body near the feed inlet, which is 1 / 3 to 2 / 3 of the way in.

[0127] Example 13

[0128] The same method is used in Example 11, except that the material discharge channel 102 is a circular channel. The unfolded surface of the sieve 101 is square. The sieve 101 covers the material discharge channel 102 directly above it.

[0129] Example 14

[0130] Repeat Example 13, as follows Figure 5 As shown, the rotary kiln is equipped with four independent screen systems 1, which are evenly distributed around the kiln body.

[0131] Example 15

[0132] Example 13 is repeated, except that the rotary kiln is equipped with 10 independent screen systems 1, which are evenly distributed around the kiln body.

[0133] Example 16

[0134] Example 13 is repeated, except that four independent screen systems are arranged in two rings and are evenly and alternately arranged around the kiln body of the rotary kiln.

[0135] Example 17

[0136] Repeat Example 16, as follows Figure 5 As shown, the rotary kiln also includes a lifting plate 6. The lifting plate 6 is located upstream of the screen system 1.

[0137] Example 18

[0138] A method for firing using the rotary kiln for suppressing ring formation as described in Example 17, the method comprising the following steps:

[0139] S1. The material to be processed is conveyed from the rotary kiln feed port to the rotary kiln.

[0140] S2. The rotary kiln rotates, and the material passes through the rotary kiln's screen system 1. The screen 101 screens the material to be processed. The fine particles below the screen 101 are then discharged from the material discharge channel 102. The coarse particles continue to pass through the high-temperature section of the rotary kiln for roasting treatment, and then are discharged from the rotary kiln's discharge port.

[0141] Example 19

[0142] Repeat Example 18, except that the method further includes the following steps:

[0143] S01. The material to be processed is pelletized or granulated before being conveyed to the rotary kiln.

[0144] Example 20

[0145] Repeat Example 18, except that fine particulate material is discharged from material leakage channel 102 and returned to step S01.

[0146] Application Example 1

[0147] 1. Material preparation:

[0148] Iron-containing raw materials include 30% blast furnace bag ash, 20% converter ash, 10% electric furnace ash, 15% copper smelting slag, 15% nickel smelting slag, and 10% red mud.

[0149] 2. Mixing: Mix 1000 kg of iron-containing raw materials, 50 kg of hydrated lime, and 50 kg of water using a high-power mixer, and then pelletize using a granulator to obtain pellets with a particle size of 5-12 mm.

[0150] 3. Screening: Pass the pellets through a 3mm sieve;

[0151] 4. Drying: Dry the material on the sieve at 200℃ for 0.3 hours;

[0152] 5. Sieving: Pass the dried pellets through a 3mm sieve;

[0153] 6. Calcination: Calcination is carried out using a conventional rotary kiln (which, compared to this application, does not contain a screening system), the rotary kiln disclosed in CN115164540 A, and the rotary kiln described in Example 17 of this application.

[0154] The calcination process conditions are as follows: the material heating rate in the rotary kiln is 10℃ / min, the temperature in the high-temperature section is 1100℃, and the residence time of the material in the high-temperature section is 60min.

[0155] The powder content, pellet strength, and metallization rate of the material discharged from the rotary kiln discharge port were measured, and the results are as follows:

[0156]

[0157] In this invention, the strength test of the calcined pellets is conducted according to GB / T 14201-1993. The metallization rate test of the calcined pellets is conducted according to GB / T 24235-2009.

[0158] After running the process of the example embodiment for 720 hours, the ring formation in each rotary kiln was checked. Each rotary kiln was then shut down, and the material with rings formed inside each kiln was removed and weighed. The results are as follows:

[0159]

[0160] Comparative data shows that using the rotary kiln described in Embodiment 17 of this application for roasting not only significantly reduces the powder content in the reduction roasting products and improves the compressive strength and metallization rate of the roasted pellets, but also effectively reduces the occurrence of ring formation within the kiln. The weight of the ring-formed material is significantly lower than that of conventional rotary kilns and the rotary kiln disclosed in CN 115164540 A, indicating that this utility model has a significant advantage in suppressing ring formation. Simultaneously, the rotary kiln has a reasonable structural design, and the screening system can efficiently separate fine particulate materials, avoiding their accumulation within the kiln and the risk of ring formation, thus improving the overall stability and economy of the process. Furthermore, the fine particulate materials separated by the screening system can be recycled.

Claims

1. A rotary kiln for suppressing ring formation, characterized in that: The rotary kiln includes a feed inlet, a kiln body, and a discharge outlet; a screen system (1) is provided on the kiln body; the screen system (1) includes a screen grid (101) and a material discharge channel (102); both the screen grid (101) and the material discharge channel (102) are located inside the rotary kiln; the screen grid (101) is connected to the inner cavity of the rotary kiln; the material discharge channel (102) is located directly below the screen grid (101) and connects the screen grid (101) to the outside of the rotary kiln.

2. The rotary kiln according to claim 1, characterized in that: The material discharge channel (102) runs through the kiln body of the rotary kiln. The screen (101) is set on the side of the material discharge channel (102) close to the inner cavity of the rotary kiln. The upper surface of the screen (101) is flush with the inner surface of the rotary kiln lining. The other end of the material discharge channel (102) is connected to the outside of the rotary kiln.

3. The rotary kiln according to claim 1, characterized in that: The material discharge channel (102) is equipped with a double-layer discharge valve.

4. The rotary kiln according to claim 3, characterized in that: The double-layer discharge valve is a double-layer interlocked conical discharge valve (2); the double-layer interlocked conical discharge valve (2) includes two conical discharge valves, namely an inner conical discharge valve (201) and an outer conical discharge valve (202); the inner conical discharge valve (201) includes an inner fixed half-conical valve (20101) and an inner movable half-conical valve (20102); when the inner movable half-conical valve (20102) is rotated, the inner movable half-conical valve (20102) overlaps with the inner fixed half-conical valve (20101) or forms a conical shape with the inner fixed half-conical valve (20101); the outer conical discharge valve (202) includes an outer fixed half-conical valve (20201) and an outer movable half-conical valve (20 ... 2) Rotate the outer movable half-cone valve (20202). The outer movable half-cone valve (20202) overlaps with the outer fixed half-cone valve (20201) or forms a cone shape with the outer fixed half-cone valve (20201). The inner fixed half-cone valve (20101) is located inside the outer movable half-cone valve (20202), and the inner movable half-cone valve (20102) is located inside the outer fixed half-cone valve (20201). The inner movable half-cone valve (20102) and the outer movable half-cone valve (20202) are connected by a rotating shaft (104). The rotating shaft (104) drives the inner movable half-cone valve (20102) and the outer movable half-cone valve (20202) to rotate simultaneously.

5. The rotary kiln according to claim 4, characterized in that: The rotary kiln also includes a drive unit, which is connected to the rotating shaft (104) and drives the rotating shaft (104) to rotate, thereby causing the inner movable semi-cone valve (20102) and the outer movable semi-cone valve (20202) to rotate simultaneously.

6. The rotary kiln according to claim 1, characterized in that: The rotary kiln is also provided with a sealing ring (3) on the outside; the sealing ring (3) is set around the outside of the rotary kiln; the bottom of the sealing ring (3) is provided with a material discharge channel (301); the material discharge channel (301) is provided with an ash discharge valve (302).

7. The rotary kiln according to claim 6, characterized in that: The material discharge channel (301) is equipped with two or more layers of ash discharge valves (302).

8. The rotary kiln according to claim 3, characterized in that: The rotary kiln also includes a lever (4), which is connected to the rotating shaft (104); a lever baffle (5) is provided on the outside of the rotary kiln; when the rotary kiln rotates, the lever baffle (5) intermittently contacts the lever (4), and the lever (4) is oscillated by the lever baffle (5), which drives the rotating shaft (104) to rotate.

9. The rotary kiln according to claim 8, characterized in that: The lever baffle (5) is mounted on the sealing ring (3).

10. The rotary kiln according to claim 1, characterized in that: The screen system (1) is located in the upstream and / or midstream section of the rotary kiln body.

11. The rotary kiln according to claim 10, characterized in that: The screen system (1) is set in the 0-2 / 3 length area of ​​the rotary kiln body near the feed inlet.

12. The rotary kiln according to any one of claims 1-11, characterized in that: The material leakage channel (102) is a circular hole channel; the sieve grid (101) has a circular, square or polygonal unfolded surface; the sieve grid (101) covers the material leakage channel (102) directly above it.

13. The rotary kiln according to any one of claims 1-11, characterized in that: The rotary kiln is equipped with n independent screen systems (1), and the n independent screen systems (1) are evenly distributed around the kiln body.

14. The rotary kiln according to claim 13, characterized in that: n is 2-100.

15. The rotary kiln according to claim 14, characterized in that: n is 3-80.

16. The rotary kiln according to claim 15, characterized in that: n is 4-60.

17. The rotary kiln according to claim 13, characterized in that: n independent screen systems (1) are arranged in one or more rings around the kiln body of the rotary kiln.

18. The rotary kiln according to claim 17, characterized in that: n independent screen systems (1) are arranged in multiple rings and are evenly and interlaced around the kiln body of the rotary kiln.

19. The rotary kiln according to any one of claims 1-11, characterized in that: The rotary kiln also includes a lifting plate (6); the lifting plate (6) is located upstream of the screen system (1).

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