A high-efficiency and energy-saving calcining system for kaolin

Abstract

The present invention discloses a high-efficiency and energy-saving calcining system for kaolin, which includes a calcining rotary kiln, a combustion chamber, a raw material bin, a wall cooler and a storage bin; a kiln cover is provided on the outer wall of the wall cooler along the length direction of the wall cooler, an air outlet is provided on the side wall of the kiln cover, the air outlet is connected to the air inlet of the induced draft fan through a pipeline, and the air outlet of the induced draft fan is respectively connected to the primary air inlet and the secondary air inlet of the burner through pipelines. Beneficial effects: The system disclosed in the present invention realizes the recovery of heat energy, reduces the use of gas fuel by the burner, saves the production cost of the enterprise, realizes energy conservation and consumption reduction, avoids excessive mullite impurities in the kaolin finished product, and after screening, the amount of sieve residue is reduced, which increases the output of the kaolin finished product, thereby improving the economic benefits of the enterprise, effectively improving the decarbonization efficiency, and improving the product quality.

Description

Technical field:

[0001] The patent of this invention belongs to the technical field of kaolin calcination, and specifically relates to a high-efficiency and energy-saving calcination system for kaolin. Background technology:

[0002] The finished kaolin is an ultra-white and ultra-fine powder, which is mainly used in papermaking, ceramics, medicine, ink and coating, etc., and has a wide range of uses. At present, the finished kaolin is obtained by calcining the crushed coal gangue through a calcining rotary kiln at 950-1100℃, dehydroxylating and decarbonizing to whiten it. The finished kaolin after high-temperature calcination needs to be cooled and sent to the silo through a pipeline; the kiln head of the calcining rotary kiln is connected to the combustion chamber through the kiln head cover, and the burner at the head of the combustion chamber sprays flames to form high-temperature air in the combustion chamber to enter the calcining rotary kiln to calcine the crushed coal gangue; the crushed coal gangue enters the kiln from the kiln tail of the calcining rotary kiln, and gradually moves toward the kiln head as the kiln rotates, and at the same time completes heat exchange with the hot air flow in the kiln and the inner wall of the kiln. After a certain residence time, the calcination, dehydroxylating and decarbonizing whitening processes are completed to form a kaolin product, which is finally discharged from the discharge port at the bottom of the kiln head cover.

[0003] However, the above calcination method has the following problems: 1. The outer flame temperature of the flame ejected from the burner is as high as 1700℃, which can easily pass through the combustion chamber and directly contact the kaolin in the kiln head cover, not only forming a large amount of impurities, but also producing a large amount of screen residue after screening, reducing the output of kaolin finished products; it will also destroy the crystal structure of the kaolin finished products themselves, reduce their quality, and affect the economic benefits of the enterprise; 2. The connection between the calcination rotary kiln and the kiln head cover is prone to heat loss, which increases the use of gas fuel by the burner, resulting in an increase in the production cost of the enterprise; 3. The kaolin finished products after high-temperature calcination need to be cooled. The cooling method is that the kaolin finished products after high-temperature calcination are sent to the wall cooler to cool the outer wall of the wall cooler through natural wind. At present, the kaolin finished products carried by enterprises after calcination are The heat is not recovered, which is not conducive to the energy conservation and consumption reduction of the enterprise and affects the economic benefits of the enterprise; 4. The inner wall of the existing calcining rotary kiln is provided with straight plate-shaped refractory bricks, which have low bearing capacity, are easy to break, and have a short service life. Moreover, during the operation of the calcining rotary kiln, the lifting range of the refractory bricks is smaller than one-fourth of the kiln body of the calcining rotary kiln, and the material spreading range is small and the height is low, resulting in the relative concentration of raw materials in the kiln body, poor contact with the secondary air, low decarbonization efficiency, and poor product quality; in order to ensure product quality, the current measures taken are to reduce the amount of raw material input or increase the temperature, and the reduction in the amount of raw material input directly leads to a decrease in output; and increasing the temperature not only leads to high energy consumption, but also the concentration of raw materials will make it difficult to diffuse the heat generated by the decarbonization reaction, resulting in high local temperature, which directly destroys the crystal structure of the product and leads to a decrease in product quality. Summary of the invention:

[0004] The object of the present invention is to provide a high-efficiency and energy-saving calcining system for kaolin which is energy-efficient and improves product quality.

[0005] The technical solution of the present invention discloses a high-efficiency and energy-saving calcining system for kaolin, which comprises a calcining rotary kiln, a combustion chamber, a raw material bin, a wall cooler and a storage bin; the air inlet of the calcining rotary kiln head is connected to the air outlet at one end of the combustion chamber, and a burner is arranged at the other end of the combustion chamber; the feed inlet at the kiln tail of the calcining rotary kiln is connected to the discharge port of the raw material bin through a screw conveyor; the discharge port at the calcining rotary kiln head is connected to the feed inlet of the wall cooler, and the discharge port of the wall cooler is connected to the feed inlet of the storage bin; a kiln cover is provided on the outer wall of the wall cooler along the length direction of the wall cooler, and an air outlet is opened on the side wall of the kiln cover, the air outlet is connected to the air inlet of the induced draft fan through a pipeline, and the air outlet of the induced draft fan is respectively connected to the primary air inlet and the secondary air inlet of the burner through pipelines.

[0006] Furthermore, the kiln cover is an arc-shaped structure matching the outer shape of the wall cooler, and the opening of the kiln cover is arranged downward.

[0007] Furthermore, it also includes a fire baffle wall; the fire baffle wall is fixedly arranged in the combustion chamber; and a plurality of ventilation holes are opened on the fire baffle wall.

[0008] Furthermore, the distance between the fire retaining wall and the kiln head cover of the calcining rotary kiln is 1.5-2m, and the fire retaining wall is made of refractory bricks.

[0009] Furthermore, the calcining rotary kiln includes a kiln head hood and a kiln body; the kiln head hood is arranged at the head of the kiln body, and a discharge port is arranged at the bottom of the kiln head hood; the end of the kiln head hood away from the kiln body is fixedly connected to the combustion chamber, and a manhole is opened on the side wall of the kiln head hood below the combustion chamber; an insulation hood is arranged at the end of the combustion chamber fixedly connected to the kiln head hood; one end of the insulation hood is fixed to the end edge of the combustion chamber, and the other end of the insulation hood passes through the kiln head hood and is placed in the kiln body.

[0010] Furthermore, the center of the heat-insulating hood and the center of the combustion chamber are located on the same straight line, and the opening side of the heat-insulating hood corresponds to the discharge port on the kiln head hood. A C-shaped baffle plate is fixed to the bottom edge of the opening side of the heat-insulating hood, and the side edge of the baffle plate is fixed to the inner wall of the kiln head hood. The heat-insulating hood is made of refractory material.

[0011] Furthermore, a plurality of rows of material lifters arranged along the circumference of the kiln body are fixedly arranged in the kiln body. During the rotation of the kiln body, the material lifters located in the upper semicircle of the kiln body are in a continuous material lifting state. Each row of the material lifters is composed of a plurality of "L"-shaped material lifting bricks arranged side by side; the connection between the long side segment and the short side segment of the material lifting brick is rounded; the side of the material lifting brick opposite to the rounded corner is inclined; the material lifting brick is made of phosphate refractory material.

[0012] Furthermore, fixing grooves are correspondingly opened on the two opposite sides of one end of the long side segment away from the short side segment, and "U"-shaped fixing steel bars are clamped in the fixing grooves, and both ends of the fixing steel bars are fixed to the inner wall of the kiln body; limiting grooves are correspondingly opened on the other two opposite sides of the long side segment, and the limiting grooves are located between the fixing grooves and the short side segment. A thermal insulation layer is coated and fixed on the inner wall of the kiln body, and the connection between the thermal insulation layer and the long side segment is clamped in the limiting groove.

[0013] Furthermore, it also includes a plurality of fish scales and snap rings; one end of the fish scale is fixed on the kiln head cover, the other end of the fish scale is in contact with the outer wall of the kiln body, and the snap ring is sleeved on the outer periphery of the fish scale.

[0014] Furthermore, it also includes a cylindrical cold air hood; one end of the cold air hood is fixedly arranged on the outside of the head of the kiln body through an annular fixing plate; a gap is formed between the inner wall of the cold air hood and the outer wall of the kiln body; the other end of the fish scale is in contact with the outer wall of the cold air hood, and an annular guide plate is fixedly arranged on the other end of the cold air hood, the annular guide plate is trumpet-shaped, and the small-diameter end of the annular guide plate is fixed on the cold air hood.

[0015] Advantages of the present invention:

[0016] 1. In the system disclosed in the present invention, a kiln hood is installed outside the wall cooler, and then the hot air in the kiln hood is extracted by an induced draft fan, thereby increasing the amount of natural wind introduced, thereby effectively realizing the cooling of the kaolin finished product in the wall cooler. At the same time, the induced draft fan transports the hot air as primary air and secondary air to the burner, realizing the recovery of heat energy, reducing the use of fuel by the burner, and saving the production cost of the enterprise.

[0017] 2. In the system disclosed in the present invention, an arc-shaped heat-insulating cover is arranged at one end of the combustion chamber fixedly connected to the kiln head cover, and the other end of the heat-insulating cover passes through the kiln head cover and is placed in the kiln body. The hot air flow directly enters the kiln body along the heat-insulating cover, thereby preventing heat from being lost from the fish scales and the cold air cover on the outside of the heat-insulating cover, thereby playing a heat-insulating role, thereby avoiding heat waste, reducing the use of fuel by the burner, saving the production cost of the enterprise, and achieving energy saving and consumption reduction.

[0018] 3. In the system disclosed in the present invention, a fire baffle is set in the combustion chamber. The hot air flow enters the calcining rotary kiln through the vents on the fire baffle, which effectively blocks the direct contact between the flame and the kaolin. This not only reduces the content of impurities in the kaolin product, but also reduces the amount of screen residue after screening, thereby increasing the output of the kaolin product; it also improves the integrity of the crystal structure of the kaolin product, thereby improving the quality of the kaolin product and the economic benefits of the enterprise.

[0019] 4. In the system disclosed in the present invention, a material lifter is arranged in the kiln body. During the rotation of the kiln body, the material lifter lifts and lifts the raw materials in the kiln body, so that the raw materials are scattered in the kiln body. Not only the lifting range is large, but also the scattering height of the raw materials is greatly improved; the contact area with the secondary air in the kiln body is increased, so that the raw materials are fully in contact with the secondary air, the calcination efficiency is greatly improved, the raw materials are decarbonized more fully, and the decarbonization efficiency is effectively improved, that is, the whiteness of the kaolin product is improved, and the product quality is improved.

[0020] 5. The decarbonization reaction occurring in the system disclosed in the present invention is an exothermic reaction. After the raw materials are spread out by the material lifter, the contact area between the raw materials and the secondary air in the kiln body is increased, so that the heat released by the decarbonization reaction can be taken away by the secondary air, thereby avoiding excessively high local temperature of the raw materials and destroying the crystal structure, thereby ensuring product quality and output. Description of the drawings:

[0021] Figure 1 It is a schematic diagram of the overall structure of an embodiment of the present invention.

[0022] Figure 2 for Figure 1 Schematic diagram of the cross section of the AA section.

[0023] Figure 3 for Figure 1 A partial enlarged schematic diagram of part B.

[0024] Figure 4 for Figure 1 Schematic cross-section of the CC section.

[0025] Figure 5 It is a schematic diagram of the structure of the lifting brick.

[0026] Figure 6 for Figure 1 Schematic cross-section of the DD section.

[0027] Figure 7 are SEM images of kaolin finished products, where (a) is the SEM image of kaolin sample a, and (b) is the SEM image of kaolin sample b.

[0028] Figure 8This is a card for testing the hiding power of kaolin, where (a) is sample A and (b) is sample B.

[0029] Calcination rotary kiln 1, kiln head cover 101, manhole 1011, kiln body 102, fish scale 103, clamping ring 104, cold air cover 105, material lifter 106, material lift brick 107, long side section 1071, short side section 1072, fixing groove 1073, limiting groove 1074, fixing steel bar 108, thermal insulation layer 109, annular fixing plate 110, annular guide plate 111, combustion chamber 2, raw material bin 3, wall cooler 4, storage bin 5, fire baffle wall 6, vent 61, burner 7, screw conveyor 8, kiln cover 9, air outlet 91, induced draft fan 10, thermal insulation cover 11, material baffle plate 12. Specific implementation method:

[0030] The present invention will be further described in detail below through embodiments in conjunction with the accompanying drawings.

[0031] like Figure 1-6 As shown, a high-efficiency and energy-saving calcining system for kaolin comprises a calcining rotary kiln 1, a combustion chamber 2, a raw material bin 3, a wall cooler 4, a storage bin 5 and a fire baffle 6; the air inlet at the kiln head of the calcining rotary kiln 1 is connected to the air outlet at one end of the combustion chamber 2, and a burner 7 is arranged at the other end of the combustion chamber 2; the feed inlet at the kiln tail of the calcining rotary kiln 1 is connected to the discharge port of the raw material bin 3 through a screw conveyor 8; the discharge port at the kiln head of the calcining rotary kiln 1 is connected to the feed inlet of the wall cooler 4 The discharge port of the wall cooler 4 is connected with the feed port of the storage bin 5; a kiln hood 9 is provided on the outer wall of the wall cooler 4 along the length direction of the wall cooler 4, and an air outlet 91 is opened on the side wall of the kiln hood 9, and the air outlet 91 is connected with the air inlet of the induced draft fan 10 through a pipeline, and the air outlet 91 of the induced draft fan 10 is respectively connected with the primary air inlet and the secondary air inlet of the burner 7 through pipelines. The kiln hood 9 is an arc structure matching the appearance of the wall cooler 4, and the opening of the kiln hood 9 is arranged downward.

[0032] A fire retaining wall 6 is fixedly arranged in the combustion chamber 2; a plurality of ventilation holes 61 are opened on the fire retaining wall 6, and the distance between the fire retaining wall 6 and the kiln head cover 101 is 1.5-2m. The fire retaining wall 6 is made of refractory bricks.

[0033] The calcining rotary kiln 1 comprises a kiln head cover 101, a kiln body 102, fish scales 103, a clamping ring 104 and a cold air cover 105; the kiln head cover 101 is arranged at the head of the kiln body 102, and a discharge port is arranged at the bottom of the kiln head cover 101; one end of the kiln head cover 101 away from the kiln body 102 is fixedly connected to the combustion chamber 2, and a manhole 1011 is arranged on the side wall of the kiln head cover 101 below the combustion chamber 2 for convenient maintenance; a heat preservation cover 11 is arranged at one end of the combustion chamber 2 fixedly connected to the kiln head cover 101; one end of the heat preservation cover 11 is fixed to the end edge of the combustion chamber 2, and the other end of the heat preservation cover 11 passes through the kiln head cover 101 and is placed in the kiln body 102, and the heat preservation cover 11 The center of the circle is located on the same straight line as the center of the combustion chamber 2, and the opening side of the heat preservation cover 11 corresponds to the discharge port on the kiln head cover 101, and a C-shaped baffle plate 12 is fixed to the bottom edge of the opening side of the heat preservation cover 11, and the side of the baffle plate 12 is fixed to the inner wall of the kiln head cover 101. The heat preservation cover 11 is made of refractory material, and the hot air flow directly enters the kiln body 102 along the heat preservation cover 11 to avoid heat loss from the fish scales 103 and the cold air cover 105 on the outside of the heat preservation cover 11, thereby playing a heat preservation role, thereby avoiding heat waste, reducing the use of gas fuel by the burner 7, saving the production cost of the enterprise, and achieving energy saving and consumption reduction.

[0034] Several rows of material lifters 106 arranged along the circumference of the kiln body 102 are fixedly arranged in the kiln body 102. During the rotation of the kiln body 102, the material lifters 106 located in the upper semicircle of the kiln body 102 are in a continuous material lifting state. Each row of material lifters 106 is composed of several "L"-shaped material lifting bricks 107 arranged side by side. The connection between the long side segment 1071 and the short side segment 1072 of the material lifting brick 107 is rounded, which improves the strength of the connection between the long side segment 1071 and the short side segment 1072, and the rounded corner can greatly reduce stress concentration, is not easy to break, and improves the service life of the material lifting brick 107. The side of the material lifting brick 107 opposite to the rounded corner is inclined to reduce the dead weight of the material lifting brick 107. The material lifting brick 107 is made of phosphate refractory material, and the long side segment 1071 is away from the short side. Fixed grooves 1073 are correspondingly opened on the opposite sides of one end of the segment 1072, and a "U"-shaped fixed steel bar 108 is clamped in the fixed groove 1073, and both ends of the fixed steel bar 108 are fixed to the inner wall of the kiln body 102; limiting grooves 1074 are correspondingly opened on the other opposite sides of the long side segment 1071, and the limiting groove 1074 is located between the fixing groove 1073 and the short side segment 1072. A thermal insulation layer 109 is coated and fixed on the inner wall of the kiln body 102, and the connection between the thermal insulation layer 109 and the long side segment 1071 is clamped in the limiting groove 1074 to strengthen the connection between the thermal insulation layer 109 and the lifting brick 107. When the fixed steel bar 108 breaks, the thermal insulation layer 109 clamped in the limiting groove 1074 can play a role in fixing the lifting brick 107.

[0035] One end of the cold air hood 105 is fixed to the outside of the head of the kiln body 102 through an annular fixing plate 110; a gap is formed between the inner wall of the cold air hood 105 and the outer wall of the kiln body 102; one end of the fish scale 103 is fixed to the kiln head hood 101, and the other end of the fish scale 103 is in contact with the outer wall of the cold air hood 105. A retaining ring 104 is sleeved on the outer periphery of the fish scale 103, and an annular guide plate 111 is fixedly provided at the other end of the cold air hood 105. The annular guide plate 111 is trumpet-shaped, and the small-diameter end of the annular guide plate 111 is fixed to the cold air hood 105.

[0036] Working principle:

[0037] The coal gangue crushed particles in the raw material bin 3 are conveyed by the screw conveyor 8 to the calcining rotary kiln 1 at a temperature of 950-1090°C for calcination, and the kiln body 102 rotates at the same time. During the rotation of the kiln body 102, the lifting bricks 107 constituting the lifting device 106 lift the raw materials in the kiln body 102 to the upper half of the kiln body 102, and then lift the materials so that the raw materials are scattered in the kiln body 102, which not only has a large lifting range, but also greatly improves the scattering height of the raw materials; increases the contact area with the secondary air in the kiln body 102, makes the raw materials fully contact with the secondary air, greatly improves the calcination efficiency, makes the raw materials decarbonized more fully, effectively improves the decarbonization efficiency, that is, improves the whiteness of the kaolin finished product, and improves the product quality.

[0038] During calcination in the kiln body 102, the gangue undergoes a decarbonization reaction to form kaolin, wherein the decarbonization reaction is an exothermic reaction. After the raw materials are spread out by the material lifter 106, the contact area between the raw materials and the secondary air in the kiln body 102 is increased, so that the heat released by the decarbonization reaction can be taken away by the secondary air, thereby avoiding excessive local temperature of the raw materials and destroying the crystal structure, thereby ensuring product quality and output.

[0039] After calcination in the kiln body 102, the material flows out from the discharge port of the kiln head cover 101 into the wall cooler 4, and the induced draft fan 10 extracts hot air in the kiln cover 9 with a temperature of 50-300°C, thereby increasing the amount of natural wind introduced, thereby effectively cooling the kaolin product in the wall cooler 4, and the cooled material is sent to the storage bin 5; the hot air extracted by the induced draft fan 10 is transported to the burner 7 as primary air and secondary air, thereby realizing the recovery of heat energy, reducing the use of gas fuel by the burner 7, and saving the production cost of the enterprise. The use of hot air as the primary air as the combustion-supporting gas is beneficial to the combustion of the fuel gas, and the secondary air is used to transport the hot air flow, adjust the temperature and atmosphere in the kiln body 102, and effectively improve the decarbonization efficiency.

[0040] The flame after combustion is blocked by the fire baffle wall 6, avoiding direct contact between the flame and kaolin, which not only reduces the content of impurities in the kaolin product, but also reduces the amount of screen residue after screening, thereby increasing the output of the kaolin product; it also improves the integrity of the crystal structure of the kaolin product, thereby improving the quality of the kaolin product and the economic benefits of the enterprise.

[0041] Comparative Example 1: The crushed coal gangue enters the calcining rotary kiln from the kiln tail of the calcining rotary kiln whose inner wall is provided with straight plate-shaped lifting refractory bricks. The burner at the head of the combustion chamber sprays flames to form high-temperature air in the combustion chamber and enters the calcining rotary kiln to calcine the crushed coal gangue; the crushed coal gangue gradually moves toward the kiln head as the kiln rotates, and at the same time completes heat exchange with the hot air flow in the kiln and the inner wall of the kiln. After a certain residence time, the calcination, dehydroxylation and decarbonization and whitening processes are completed to form kaolin finished products, which are finally discharged from the discharge port at the bottom of the kiln head cover. The discharged kaolin finished products enter the wall cooler for natural cooling, and are sent to the silo through a pipeline after cooling.

[0042] The fuel gas used in the fuel burners in Example 1 and Comparative Example 1 is prepared by a coal-to-gas process. To produce 1 ton of kaolin using Comparative Example 1, 0.28-0.3 tons of coal are required, while to produce 1 ton of kaolin using Example 1, only 0.19-0.23 tons of coal are required, which significantly reduces coal consumption and saves the company's production costs.

[0043] When 1 ton of kaolin is produced by comparative example 1, about 0.5 kg of sieve residue is generated; when 1 ton of kaolin is produced by example 1, only about 0.1 kg of sieve residue is generated; the production of kaolin by the system of example 1 of the present invention significantly reduces the content of impurities in the kaolin product, and the amount of sieve residue is reduced after screening.

[0044] experiment:

[0045] The kaolin produced in Comparative Example 1 was selected as sample a and the kaolin produced in Example 1 was selected as sample b.

[0046] 1. Surface morphology observation

[0047] The surface morphology of sample a and sample b was observed by scanning electron microscope. The specific results are shown in Figure 7 ,from Figure 7 As can be seen from (a), the crystal structure of the kaolin produced in Comparative Example 1 is granular and agglomerated together; Figure 7 As can be seen from (b), the crystal structure of the kaolin produced in Example 1 is lamellar, which is more complete than the crystal structure of the kaolin produced in Comparative Example 1.

[0048] 2. Kaolin hiding power test

[0049] (1) 1.8 g of cellulose was added to 136 g of distilled water and stirred evenly, then 0.8 g of pH regulator was added and stirred evenly, then 3.6 g of organic dispersant (SN5040), 4.0 g of inorganic dispersant (20% sodium hexametaphosphate), 6.9 g of ethylene glycol, 4.8 g of film-forming aid, and 0.2 g of defoamer were added in sequence, then stirred for 10 minutes at a speed of 1000 rpm, then 125 g of kaolin sample a was added, stirred for 10 minutes at a speed of 3000 rpm, and finally 69.9 g of styrene-acrylic emulsion and 1.0 g of defoamer were added and stirred for 3 minutes to obtain sample A.

[0050] (2) 1.8 g of cellulose was added to 136 g of distilled water and stirred evenly, and then 0.8 g of pH regulator was added and stirred evenly, and then 3.6 g of organic dispersant (SN5040), 4.0 g of inorganic dispersant (20% sodium hexametaphosphate), 6.9 g of ethylene glycol, 4.8 g of film-forming aid, and 0.2 g of defoaming agent were added in sequence, and then stirred for 10 minutes at a rotation speed of 1000 rpm, and then 125 g of kaolin sample b was added, and stirred for 10 minutes at a rotation speed of 3000 rpm, and finally 69.9 g of styrene-acrylic emulsion and 1.0 g of defoaming agent were added and stirred for 3 minutes to obtain sample B.

[0051] Drop sample A and sample B on the blackboard of the card respectively, then scrape the two drops of solution from the blackboard to the whiteboard, and then dry them. Finally, use WSB-3A intelligent digital whiteness meter to test the whiteness of sample A and sample B. The test results are detailed in Figure 8 .

[0052] from Figure 8 It can be seen that sample B at the blackboard is whiter than sample A; after detection by WSB-3A intelligent digital whiteness meter, the whiteness of sample A at the blackboard is 74.3%, and the whiteness at the whiteboard is 86.6%, so the covering rate is 74.3 / 86.6×100%=85.8%; the whiteness of sample B at the blackboard is 79%, and the whiteness at the whiteboard is 87.6%, so the covering rate is 79 / 87.6×100%=90.2%, and the covering rate of sample B differs by 4.4% from that of sample A. Therefore, it is proved that the kaolin finished product prepared in Example 1 of the present invention has a more complete crystal structure and better covering power than the kaolin finished product prepared in Comparative Example 1.

[0053] 3. Whiteness test of kaolin finished products

[0054] Kaolin sample a and kaolin sample b were respectively pressed into round cake-shaped samples with a diameter of 4 cm and a thickness of 1 cm, and then the whiteness was tested using a WSB-3A intelligent digital whiteness meter; the test results showed that the whiteness of the kaolin product prepared in Example 1 of the present invention was 94.3%, while the whiteness of the kaolin product prepared in Comparative Example 1 was only 93.9%. Therefore, the system of Example 1 of the present invention can fully calcine the coal gangue, make its decarbonization more complete, and effectively improve the decarbonization efficiency, that is, improve the whiteness of the kaolin product, thereby improving the product quality.

[0055] 4. Determination of kaolin particle size distribution

[0056] After weighing 0.2g of kaolin sample a and kaolin sample b respectively, they were put into 500ml beakers respectively, and then diluted to 40 with 2% dispersant water respectively, and dispersed in an ultrasonic disperser for 3 minutes, and then prepared into a suspension with a concentration between 1700-1800 with 2% sodium hexametaphosphate, and finally detected by BT-1500 centrifugal sedimentation particle size distribution instrument; test results: in the kaolin finished product prepared in Example 1 of the present invention, particles with a particle size of less than 2 microns accounted for 83.8% of the total particles, while in the kaolin finished product prepared in Comparative Example 1, particles with a particle size of less than 2 microns accounted for 81.3% of the total particles. Therefore, the system of Example 1 of the present invention is used to prepare the kaolin finished product, which protects its crystal structure integrity and reduces the loss of kaolin finished products with a particle size of less than 2 microns.

[0057] The above are preferred embodiments of the present invention. For ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A high-efficiency and energy-saving calcining system for kaolin, characterized in that: It includes a calcining rotary kiln, a combustion chamber, a raw material bin, a wall cooler, a storage bin and a fire retaining wall; The air inlet of the kiln head of the calcining rotary kiln is connected to the air outlet at one end of the combustion chamber, and a burner is arranged at the other end of the combustion chamber; the feed inlet of the kiln tail of the calcining rotary kiln is connected to the discharge port of the raw material bin through a screw conveyor; the discharge port of the kiln head of the calcining rotary kiln is connected to the feed inlet of the wall cooler, and the discharge port of the wall cooler is connected to the feed inlet of the storage bin; A kiln cover is provided on the outer wall of the wall cooler along the length direction of the wall cooler, an air outlet is provided on the side wall of the kiln cover, the air outlet is connected with the air inlet of the induced draft fan through a pipeline, and the air outlet of the induced draft fan is respectively connected with the primary air inlet and the secondary air inlet of the burner through pipelines; The calcining rotary kiln comprises a kiln head cover and a kiln body; the kiln head cover is arranged at the head of the kiln body, and a discharge port is arranged at the bottom of the kiln head cover; one end of the kiln head cover away from the kiln body is fixedly connected to the combustion chamber, and a manhole is arranged on the side wall of the kiln head cover below the combustion chamber; a heat preservation cover is arranged at one end of the combustion chamber fixedly connected to the kiln head cover; one end of the heat preservation cover is fixed to the end edge of the combustion chamber, and the other end of the heat preservation cover passes through the kiln head cover and is placed in the kiln body; The fire baffle is fixedly arranged in the combustion chamber; a plurality of ventilation holes are opened on the fire baffle; Several rows of material lifters are fixedly arranged in the kiln body and arranged along the circumference of the kiln body. Each row of material lifters is composed of several "L"-shaped material lifter bricks arranged side by side. The connection between the long side segment and the short side segment of the material lifter brick is rounded. The side of the material lifter brick opposite to the rounded corner is inclined. The center of the heat preservation cover and the center of the combustion chamber are located on the same straight line, and the opening side of the heat preservation cover corresponds to the discharge port on the kiln head cover, a C-shaped baffle plate is fixed to the bottom edge of the opening side of the heat preservation cover, and the side edge of the baffle plate is fixed to the inner wall of the kiln head cover, and the heat preservation cover is made of refractory material; Fixed grooves are correspondingly provided on the two opposite sides of one end of the long side segment away from the short side segment, and "U"-shaped fixed steel bars are clamped in the fixed grooves, and both ends of the fixed steel bars are fixed to the inner wall of the kiln body; limiting grooves are correspondingly provided on the other two opposite sides of the long side segment, and the limiting grooves are located between the fixing grooves and the short side segment, and a thermal insulation layer is coated and fixed on the inner wall of the kiln body, and the connection between the thermal insulation layer and the long side segment is clamped in the limiting groove.

2. The high-efficiency and energy-saving calcining system for kaolin according to claim 1, characterized in that: The kiln cover is an arc-shaped structure matching the outer shape of the wall cooler, and the opening of the kiln cover is arranged downward.

3. The high-efficiency and energy-saving calcining system for kaolin according to claim 1, characterized in that: The distance between the fire retaining wall and the kiln head cover of the calcining rotary kiln is 1.5-2m, and the fire retaining wall is made of refractory bricks.

4. The high-efficiency and energy-saving calcining system for kaolin according to claim 1, characterized in that: It also includes a plurality of fish scales and snap rings; one end of the fish scale is fixed on the kiln head cover, the other end of the fish scale is in contact with the outer wall of the kiln body, and the snap ring is sleeved on the outer periphery of the fish scale.

5. The high-efficiency and energy-saving calcining system for kaolin according to claim 4, characterized in that: It also includes a cylindrical cold air hood; one end of the cold air hood is fixedly arranged on the outside of the head of the kiln body through an annular fixing plate; a gap is formed between the inner wall of the cold air hood and the outer wall of the kiln body; the other end of the fish scale is in contact with the outer wall of the cold air hood, and an annular guide plate is fixedly arranged on the other end of the cold air hood, the annular guide plate is trumpet-shaped, and the small-diameter end of the annular guide plate is fixed on the cold air hood.

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