Top-loading dynamic calcining kiln process system
The top-loading dynamic calcination kiln process system solves the problems of uneven activity and high cost in magnesite production, and realizes efficient and stable magnesite calcination and solid waste resource utilization, meeting the requirements of large-scale production.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2026-02-05
- Publication Date
- 2026-03-27
AI Technical Summary
Existing magnesite production processes suffer from uneven activity, non-uniformity, and high costs, especially during static and dynamic calcination, which leads to decreased product quality and persistently high production costs.
The system adopts a top-mounted dynamic calcining kiln process system, which includes a vertical calcining kiln body with a preheating and dehydration zone, a calcination zone, and a cooling zone. It uses an internal heating combustion unit and DCS intelligent control to ensure that the temperature and pressure inside the kiln are kept constant at 900℃±50℃, thus solving the problems of particle size fluctuation and material inhomogeneity.
It achieves uniform calcination of magnesite raw materials, avoiding phenomena such as under-calcination, scorching, and over-calcination, meeting the needs of large-scale production with an annual output of 100,000 tons, achieving 100% solid waste disposal rate, zero emissions throughout the entire process, and reducing production costs.
Smart Images
Figure CN121739728A_ABST
Abstract
Description
Technical Field
[0001] This invention belongs to the field of kiln calcination technology, and particularly relates to a top-loading dynamic calcination kiln process system. Background Technology
[0002] In recent years, China's magnesium industry has focused on new materials technology research and development, with magnesium chemicals, magnesium building materials, magnesium salts, and magnesium metals as its main research directions. In particular, there is a significant gap between China and foreign countries in the development of specialty active magnesium oxide, such as magnesium flame retardants (magnesium whiskers), magnesium chemicals, magnesium salts, magnesium alloys and their deep processing, and organic magnesium compounds for magnesium supplementation in health products. There are also high-value-added reagent-grade, pharmaceutical-grade, and food-grade magnesium products. Common specialty active magnesium oxide series include: 1) High-grade magnesium oxide is mainly used in the electronics industry, defense and aerospace industries; 2) Pharmaceutical-grade magnesium oxide is mainly used in the pharmaceutical industry; 3) Industrial-grade magnesium oxide is mainly used in industries such as ceramics, rubber, and tires; 4) Reagent-grade magnesium oxide is mainly used in analysis.
[0003] Currently, my country uses vertical kilns, rotary kilns, and tunnel kilns to produce light-calcined magnesite. With the development and upgrading of enterprises and the optimization of production processes, new furnace types such as multi-layer furnaces, fluidized bed furnaces, and suspension furnaces have emerged to facilitate the transformation of magnesite powder production into light-calcined magnesite. However, current magnesite production processes have some drawbacks. These mainly manifest in uneven and uncontrollable activity, regardless of whether static or dynamic calcination is used to prepare magnesite oxide. This restricts product quality, lowers product grade, and keeps production costs high.
[0004] Magnesite light-calcining kilns mainly include the following types: Multi-layer furnace (multi-hearth furnace): A vertical shaft drives the rake arm to rotate, and the material falls layer by layer along a spiral path within the multi-layer furnace chamber, with direct fuel combustion for heating. Advantages include good heat exchange conditions and uniform product quality; disadvantages include high dust content in the flue gas and complex equipment structure. Fluidized bed furnace: Based on fluidization technology, airflow lifts ore particles to form a fluidized bed, achieving rapid heating. A flash fluidized bed light-calcining furnace requires only 3 seconds for a single process, increasing efficiency hundreds of times compared to traditional methods, and is suitable for materials with a particle size of 3-10 mm. Suspension furnace: A three-stage cyclone preheating system suspends and heats the material, improving heat utilization efficiency. Integrated process kilns: Such as conveyor bed reactors combining two-stage fluidized bed gasification and flash light-calcination, allowing for continuous operation and fully enclosed operation, solving dust pollution problems, with energy consumption below 180 kg standard coal / ton of product and low pollutant emissions.
[0005] For manufacturers producing light magnesium oxide, the challenge lies in the structural transformation and optimization of old equipment. The equipment must incorporate technological innovation to achieve a systematic production objective that reduces costs, ensures stable operation, is environmentally friendly and energy-saving, and meets the requirements for promoting high-quality development in the magnesium oxide industry. Summary of the Invention
[0006] The purpose of this invention is to provide a top-loading dynamic calcining kiln process system that overcomes the shortcomings of existing technologies. For magnesite ore or solid waste particles smaller than 20mm, the system operates a calcination process under different temperatures and pressures within the top-loading dynamic calcining kiln. The kiln body is designed to operate at a constant temperature of 900℃±50℃, solving the problems of particle size fluctuation and material inhomogeneity in calcined magnesite raw materials. It also avoids the phenomena of material swelling, under-firing, and over-firing during the calcination process of magnesite ore, thus meeting the large-scale production target of 100,000 tons per year.
[0007] To achieve the above objectives, the present invention provides the following technical solution: A top-mounted dynamic calcining kiln process system includes a calcining kiln with a vertical structure. The kiln body contains a calcining zone, and a pusher is located at the bottom outlet. A feed inlet is located at the top of the kiln body, connected to a storage silo above it. An electric valve is installed on the feed inlet. Below the feed inlet is a material distributor, which leads downwards to a preheating and dehydration zone, a calcining zone, and a cooling zone. Multiple sets of internally heated combustion units are arranged side-by-side within the calcining zone. Each internally heated combustion unit contains two or more combustion chambers. Below each combustion chamber is a horizontal double-channel fire channel, and above the horizontal fire channel is a flue gas chamber. The side wall of the flue gas chamber has an outlet at a downward 25° angle. The flue gas vent array has an angle; the top of the internally heated combustion unit is provided with a long pointed ridge with an included angle of 60° at the top; the top of the material distributor is connected to the waste heat exchanger, bag filter and chimney in sequence through the dust collection pipe; the combustion air exchanges heat with the flue gas in the waste heat exchanger and then enters the horizontal double flue in parallel with the natural gas pipeline; the flue gas chamber forms a dynamic thermal balance at a temperature of 900℃±50℃ and a pressure of 1500Pa; the amount of natural gas and combustion air in the horizontal double flue in each layer of the combustion chamber is controlled by DCS intelligent control, and the control interface displays parameters such as kiln temperature, pressure, natural gas flow rate, raw ore feed rate and magnesium oxide output rate.
[0008] Furthermore, the internal heating combustion unit, which is closely connected to the side wall of the kiln, is a half-structure, forming a longitudinal calcination channel with the adjacent internal heating combustion unit.
[0009] Furthermore, a partition wall is provided in the center of the kiln body, and the partition wall is built and connected to the top of an internal heating combustion unit, with the top of the partition wall connected to the top plate of the kiln body.
[0010] Furthermore, the width of the longitudinal calcination channel is 560-580mm, and the longitudinal length is 810-830mm.
[0011] Furthermore, the sidewall of the kiln body consists of a high-alumina brick layer, a clay brick layer, and a steel structure outer cover from the inside out, with the thickness ratio of the high-alumina brick layer to the clay brick layer being 1:1; an I-beam bracket is provided between the calcination zone and the cooling zone, and a protective steel plate is provided on the surface of the I-beam bracket.
[0012] Furthermore, the material diverter is a heat-resistant steel plate structure, with longitudinal right-angled steel plates and multiple transverse right-angled steel plates vertically intersecting and connecting to form a connecting space below the right-angled steel plates. At least one intersection has an opening for connecting to the exhaust pipe, which extends through the side wall of the kiln and connects to the dust collection pipe.
[0013] Furthermore, the horizontal double-section fire channel is constructed of irregularly shaped high-alumina bricks and clay bricks, with the irregularly shaped high-alumina bricks on the inside and the clay bricks on the outside, with a total thickness of 560-580mm.
[0014] Furthermore, the flue gas holes are φ50-80 in size and arranged in 5 rows vertically and 20 groups horizontally.
[0015] Furthermore, the cooling chamber includes an upper rectangular chamber and a bottom conical chamber. Cold air inlets perpendicular to the cone are arranged on both sides of the conical chamber, and hot air outlets are provided on the rectangular chamber. After calcination, magnesium oxide dynamically falls into the cooling chamber. Room temperature air is introduced through the cold air inlets to exchange heat with magnesium oxide twice. When the temperature reaches ≤80°C, it is pushed out by the pusher.
[0016] Compared with the prior art, the beneficial effects of the present invention are: This invention targets small particles of magnesite ore or solid waste smaller than 20mm, and describes a calcination process at different temperatures and pressures within a top-loading dynamic calcining kiln. The kiln body is designed to operate at a constant temperature of 900℃±50℃, solving the problems of particle size fluctuation and material inhomogeneity in calcined magnesite raw materials. It avoids the phenomena of material swelling, under-burning, and over-burning during the calcination process of magnesite ore. The internally heated combustion unit can both release and store heat, keeping the calcination temperature constant and solving the problems of activity and calcination performance. The double-horizontal flue internal heating top-loading dynamic calcining kiln process technology of the present invention solves the problem of calcining magnesite raw materials with different contents of light magnesium oxide products from small particle solid waste materials with a diameter of less than 20mm. It provides an effective solution for industrial raw ore and solid waste resource utilization, plays a positive role in improving the current situation of magnesite development in my country, and ultimately achieves a 100% solid waste disposal rate and achieves "zero" emissions of waste gas and wastewater throughout the entire process. The entire process of this invention adopts DCS intelligent control, and the on-site operation is postless. The parameters such as heating temperature, material movement speed and material temperature fluctuation can be flexibly adjusted to meet the large-scale production target of 100,000 tons per year. The entire calcining kiln and its auxiliary facilities have the advantages of simple structure, stable effect, safety and reliability, energy saving and low investment. Attached Figure Description
[0017] Figure 1 This is a schematic diagram of the structure of an embodiment of the present invention; Figure 2 This is a schematic diagram of the double-fire channel structure in an embodiment of the present invention; Figure 3 This is a schematic diagram of the furnace body structure in the calcination zone of an embodiment of the present invention; Figure 4 This is a schematic diagram of the rectangular chamber wall structure of the cooling zone in an embodiment of the present invention; Figure 5 This is a schematic diagram of the conical chamber wall structure in the cooling zone of this invention. Figure 6 This is a schematic diagram of the splitter structure in an embodiment of the present invention; Among them, 1-kiln body, 2-calcination zone, 3-preheating and dehydration zone, 4-cooling zone, 5-storage silo, 6-electric valve, 7-material distributor, 8-internal heating combustion unit, 9-combustion chamber, 10-horizontal double flue, 11-flue gas chamber, 12-flue gas vent, 13-ridge, 14-longitudinal calcination channel, 15-partition wall, 16-high alumina brick layer, 17-clay brick layer, 18-steel structure outer cover, 1 9-I-beam bracket, 20-protective steel plate, 21-longitudinal right-angle steel plate, 22-transverse right-angle steel plate, 23-exhaust pipe, 24-dust collection pipe, 25-irregular high-alumina brick, 26-clay brick, 27-rectangular silo, 28-conical silo, 29-blower, 30-waste heat exchanger, 31-bag filter, 32-chimney, 33-pusher, 34-cold air inlet, 35-hot air outlet. Detailed Implementation
[0018] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments.
[0019] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.
[0020] The components of the embodiments of the invention described and shown in the accompanying drawings can typically be arranged and designed in a variety of different configurations. Therefore, the following detailed description of the embodiments of the invention provided in the drawings is not intended to limit the scope of the claimed invention, but merely to illustrate selected embodiments of the invention.
[0021] See Figure 1-6 This is a schematic diagram of an embodiment of a top-mounted dynamic calcining kiln process system according to the present invention. It includes a calcining kiln, with a vertical kiln body 1 containing a calcining zone 2. A pusher 33 is located at the bottom outlet. A feed inlet is located at the top of the kiln body 1, connected to a storage silo 5 above the feed inlet. An electric valve 6 is located on the feed inlet. A material distributor 7 is located below the feed inlet, leading to a preheating and dehydration zone 3, a calcining zone 2, and a cooling zone 4. Multiple sets of internally heated combustion units 8 are arranged side-by-side within the calcining zone 2. Each internally heated combustion unit 8 contains two or more layers of combustion chambers 9. Below each combustion chamber 9 is a horizontal double-channel fire channel 10, and above the horizontal fire channel 10 is a flue gas chamber 11. An array of flue gas holes 12 with a downward 25° angle at the outlet is opened on the side wall of the flue gas chamber 11. The top of the internally heated combustion unit 8 has a continuous pointed ridge 13 with a 60° angle at the top. The top of the material distributor 7 is connected to the waste heat exchanger 30, bag filter 31, and chimney 32 in sequence via the dust collection pipe 24. Driven by the blower 29, the combustion air exchanges heat with the flue gas in the waste heat exchanger 30 and then enters the horizontal double-channel combustion chamber 10 in parallel with the natural gas pipeline. A dynamic thermal equilibrium is formed within the flue gas chamber 11 at a temperature of 900℃±50℃ and a pressure of 1500Pa. The usage of natural gas and combustion air in the horizontal channel 10 of each combustion chamber 9 is controlled intelligently by a DCS system. The control interface displays parameters such as kiln temperature, pressure, natural gas flow rate, raw ore feed rate, and magnesium oxide discharge rate.
[0022] The internally heated combustion unit 8, which is tightly connected to the side wall of the kiln body 1, is a half-structure, forming a longitudinal calcination channel 14 with the adjacent internally heated combustion unit 8. The longitudinal calcination channel 14 has a width of 580 mm and a longitudinal length of 3500 mm. The principle of adapting the size of the longitudinal calcination channel 14 to the size of the material being processed is that gas can be injected into the middle of the calcination channel.
[0023] A partition wall 15 is centrally located in the kiln body 1. The partition wall 15 is constructed and connected to the top of an internally heated combustion unit 8, and the top of the partition wall 15 is connected to the top plate of the kiln body 1. The function of the partition wall 15 is to divide the calcination chamber into different parts. The partition wall can serve as a support and can also calcine different types of magnesite, with two grades and particle sizes of magnesite not interfering with each other.
[0024] The side wall of the kiln body 1 consists of a high-alumina brick layer 16, a clay brick layer 17, and a steel structure outer cover 18 from the inside out. The thickness ratio of the high-alumina brick layer 16 to the clay brick layer 17 is 1:1. An I-beam bracket 19 is provided between the calcination zone 2 and the cooling zone 4. A protective steel plate 20 is provided on the surface of the discharge port of the I-beam bracket 19.
[0025] The material diverter 7 is a heat-resistant steel plate structure. The longitudinal right-angle steel plate 21 and multiple transverse right-angle steel plates 22 are vertically connected, forming a connecting space below the right-angle steel plates. The exhaust pipe 23 is connected to the longitudinal right-angle steel plate 21. The exhaust pipe 23 is connected to the flue outside the kiln through the dust collection pipe 24 to reduce the concentration of dust inside the kiln.
[0026] The horizontal double-unit flue 10 is constructed of irregularly shaped high-alumina bricks 25 and clay bricks 26, with the high-alumina bricks 25 on the inner side and the clay bricks 26 on the outer side, for a total thickness of 580 mm. The flue gas vents 12 have a size of φ50-80, arranged in 5 rows vertically and 20 groups horizontally. The function of the flue gas vents 12 is to ensure the uniform entry of high-temperature flue gas into the calcination chamber.
[0027] Cooling zone 4 includes an upper rectangular chamber 27 and a bottom conical chamber 28. Multiple cold air inlets 34 are arranged on both sides of the conical chamber 28, and multiple hot air outlets 35 are provided on the rectangular chamber 27. After calcination, magnesium oxide dynamically moves downward and falls into the cooling chamber. The cold air inlets introduce room temperature air to exchange heat with magnesium oxide twice. When the temperature reaches ≤80℃, it is pushed out by the pusher.
[0028] In the operation of this embodiment of the invention, the raw materials are stored in silos and transported to the storage silo 5 by a mechanized automatic loading trolley. The raw materials are magnesite or small particle solid waste with a particle size of less than 20mm. They are automatically opened by an electric valve 6 and enter the kiln body 1. After passing through a material distributor 7, the raw materials are evenly dropped into the preheating and dehydration zone 3 in the kiln body. The external and internal water are removed by hot waste gas. The raw material temperature is between 300℃ and 360℃ before it is dynamically moved down to the calcination zone 2.
[0029] After the dynamic thermal equilibrium of magnesite calcined to 900℃±50℃ is reached, the reaction MgCO3→MgO+CO2↑ occurs, and magnesite (MgCO3) decomposes into magnesium oxide and carbon dioxide gas↑ upon calcination.
[0030] The biggest advantage of this invention's system is its ability to process magnesite or small-particle solid waste with a particle size of less than 20mm. This raw material cannot be processed by conventional vertical kilns, rotary kilns, multi-layer furnaces, or suspension furnaces. This is because vertical kilns, rotary kilns, and multi-layer furnaces can only process large particles larger than 50mm, while suspension furnaces can only process small particles smaller than 1mm. The core factor is the air permeability of vertical kilns and multi-layer furnaces. If the particles are too small, they will not be properly calcined due to insufficient air permeability. Rotary kilns have long calcination times, poor uniformity, and low yields. Suspension furnaces rely on gas blowing, so the particle size cannot be too large, otherwise, they cannot be suspended.
[0031] This invention can also be extended to carbonate and silicate minerals, processing them according to particle size gradients. It can address the calcination of lightweight magnesia products with different particle sizes, such as magnesite below 20mm, 20-50mm, 50-100mm, and 100-150mm, and can achieve calcination processes under different temperatures and pressures. With the kiln dimensions remaining constant, when the particle size of different raw materials changes, the DCS intelligent control system regulates the flow rate, time, and pressure of the heated flue gas (i.e., the exhaust gas from natural gas combustion) to maintain a stable constant temperature of 900℃±50℃ within the flue gas chamber 11.
[0032] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.
Claims
1. A top-loading dynamic calcining kiln process system, comprising a calcining kiln, the kiln body being a vertical structure, a calcining zone being provided inside the kiln body, and a pusher being provided at the bottom outlet, characterized in that, The top of the kiln body is provided with a feed inlet, which is connected to the storage silo above the feed inlet. An electric valve is provided on the feed inlet. Below the feed inlet of the calcining kiln is a material diverter, which leads downward to a preheating and dehydration zone, a calcining zone, and a cooling zone. Multiple sets of internal heating combustion units are arranged side by side in the calcining zone. Each internal heating combustion unit has two or more layers of combustion chambers. Below each combustion chamber is a horizontal double-channel fire channel, and above the horizontal fire channel is a flue gas chamber. The side wall of the flue gas chamber has an array of flue gas holes with an downward 25° angle at the outlet. The top of the internally heated combustion unit is provided with a long, pointed ridge with an included angle of 60° at the top. The top of the material distributor is connected to the waste heat exchanger, bag filter, and chimney in sequence via a dust collection pipe. After exchanging heat with the flue gas in the waste heat exchanger, the combustion air enters the horizontal double-burner flue in parallel with the natural gas pipeline. A dynamic thermal balance is formed in the flue gas chamber at a temperature of 900℃±50℃ and a pressure of 1500Pa. The amount of natural gas and combustion air used in the horizontal double-burner flue in each layer of the combustion chamber is controlled by DCS intelligent control. The control interface displays parameters such as kiln temperature, pressure, natural gas flow rate, raw ore feed rate, and magnesium oxide discharge rate.
2. The top-loading dynamic calcining kiln process system according to claim 1, characterized in that, The internally heated combustion unit, which is closely connected to the side wall of the kiln, is a half-structure, forming a longitudinal calcination channel with the adjacent internally heated combustion unit.
3. The top-loading dynamic calcining kiln process system according to claim 1, characterized in that, The kiln body is provided with a partition wall in the center. The partition wall is built and connected to the top of an internal heating combustion unit, and the top of the partition wall is connected to the top plate of the kiln body.
4. The top-loading dynamic calcining kiln process system according to claim 1, characterized in that, The width of the longitudinal calcination channel is 560-580mm, and the longitudinal length is 810-830mm.
5. The top-loading dynamic calcining kiln process system according to claim 1, characterized in that, The sidewall of the kiln body consists of a high-alumina brick layer, a clay brick layer, and a steel structure outer cover from the inside out. The thickness ratio of the high-alumina brick layer to the clay brick layer is 1:
1. An I-beam bracket is provided between the calcination zone and the cooling zone, and a protective steel plate is provided on the surface of the I-beam bracket.
6. The top-loading dynamic calcining kiln process system according to claim 1, characterized in that, The material diverter is a heat-resistant steel plate structure, with longitudinal right-angled steel plates and multiple transverse right-angled steel plates vertically intersecting and connecting to form a connecting space below the right-angled steel plates. At least one intersection has an opening to connect to the exhaust pipe, which extends from the side wall of the kiln and connects to the dust collection pipe.
7. The top-loading dynamic calcining kiln process system according to claim 1, characterized in that, The horizontal double-linked fire channel is constructed of irregularly shaped high-alumina bricks and clay bricks, with the irregularly shaped high-alumina bricks on the inside and the clay bricks on the outside, with a total thickness of 560-580mm.
8. The top-loading dynamic calcining kiln process system according to claim 1, characterized in that, The flue gas vents are φ50-80 in size and are arranged in 5 rows vertically and 20 groups horizontally.
9. The top-loading dynamic calcining kiln process system according to claim 1, characterized in that, The cooling chamber includes an upper rectangular chamber and a lower conical chamber. Cold air inlets perpendicular to the cone are arranged on both sides of the conical chamber, and hot air outlets are provided on the rectangular chamber. After calcination, magnesium oxide dynamically falls into the cooling chamber. Room temperature air is introduced through the cold air inlets to exchange heat with the magnesium oxide twice. When the temperature reaches ≤80℃, it is pushed out by the pusher.