A device and method for preventing low-temperature drying and hardening of titanium concentrate rotary kiln

Abstract

The application discloses a device for preventing titanium concentrate rotary kiln low-temperature drying and caking, comprising: a shell with a sintering cavity; a flue gas cover and a furnace gas cover arranged at the feeding end of the shell; a discharge cover arranged at the discharging end of the shell; a main flue gas pipe arranged in the sintering cavity; a return gas pipe between the main flue gas pipe and the inner wall of the shell; a blowing pipe between the return gas pipe and the inner wall of the shell in the radial direction, the blowing pipe being provided with a nozzle, the blowing pipe being connected with a rotary joint arranged near the discharge cover, the rotary joint being further connected with a flue gas branch pipe arranged outside the shell, and the flue gas branch pipe receiving at least part of the flue gas discharged from the rotary kiln through the return gas pipe and the flue gas cover after indirect heat exchange with the titanium concentrate in the sintering cavity. The application also provides a method using the device. The device and the method utilize part of the flue gas discharged from the rotary kiln as blowing gas, realize efficient utilization of resources on the basis of solving the problem of titanium concentrate caking, and have the advantages of high efficiency, low cost and the like.

Description

Technical Field

[0001] This invention belongs to the field of titanium concentrate production and processing technology, and specifically relates to a device and method for preventing titanium concentrate from caking during low-temperature drying in a rotary kiln. Background Technology

[0002] Titanium concentrate is the main raw material for the production of titanium dioxide, high-titanium slag, and synthetic rutile. It is primarily obtained from ilmenite or titanomagnetite. The titanium grade in the raw ore is usually low, requiring enrichment through gravity separation, magnetic separation, and flotation. Since the titanium concentrate after beneficiation contains approximately 10% moisture, failure to pre-treat it with dewatering will result in low energy utilization, high economic costs, and large emissions in subsequent processes, placing significant pressure on downstream operations. Therefore, dewatering and drying of the flotation titanium concentrate is necessary.

[0003] The common drying method for titanium concentrate is rotary kiln drying. Rotary kiln drying involves contacting the water-containing titanium concentrate with high-temperature flue gas. In this method, the flotation titanium concentrate enters the kiln from one end, is heated and dried during its movement within the kiln, and finally exits from the discharge port at the bottom of the other end of the kiln. There are two methods for drying titanium concentrate: direct drying and indirect drying. Because titanium concentrate has a fine particle size and a wide particle size distribution (more than 75% of particles are below 200 mesh (0.074 mm)); high moisture content, it is prone to agglomeration; and its specific gravity is high, reaching a true specific gravity of 4.30 t / m³. 3 Due to its poor fluidity, direct drying of titanium concentrate results in significant losses and a poor production environment. Furthermore, the high initial temperature during drying causes flotation reagents to decompose or volatilize, releasing pungent odors and polluting the environment, severely impacting people's lives. Indirect drying is a more environmentally friendly and suitable method for drying titanium concentrate. However, because titanium concentrate is dense, slides along the inner wall of the drying rotary kiln, has a fine particle size, and high moisture content, indirect drying can lead to titanium concentrate caking on the flue gas return pipe and the inner wall of the drying rotary kiln. This increases equipment load and reduces production efficiency.

[0004] Based on the above technical background, it is necessary to propose a device and method to prevent caking of titanium concentrate during low-temperature drying in a rotary kiln. Summary of the Invention

[0005] To address at least one of the existing technical problems, this invention proposes an apparatus and method for preventing caking of titanium concentrate during low-temperature drying in a rotary kiln. This apparatus and method utilize a portion of the rotary kiln's exhaust gas as injection gas, achieving efficient resource utilization while solving the titanium concentrate caking problem.

[0006] According to the present invention, a device for preventing caking of titanium concentrate during low-temperature drying in a rotary kiln is provided, comprising:

[0007] A shell with a sintering cavity;

[0008] A flue gas hood and a furnace gas hood are installed at the feed end of the housing;

[0009] A discharge hood is provided at the discharge end of the housing;

[0010] The main flue gas pipe is installed inside the sintering chamber;

[0011] A return gas pipe located radially between the main flue gas pipe and the inner wall of the housing;

[0012] A blowpipe is located radially between the return gas pipe and the inner wall of the shell. The blowpipe is equipped with a nozzle and is connected to a rotary joint located near the discharge hood so that the blowpipe rotates with the shell. The rotary joint is also connected to a flue gas branch pipe located outside the shell. The flue gas branch pipe receives at least a portion of the flue gas discharged from the rotary kiln through the return gas pipe and the flue gas hood after indirect heat exchange with the titanium concentrate in the sintering chamber.

[0013] According to one embodiment of the present invention, the blowpipe extends from the flue gas hood to the discharge hood.

[0014] According to one embodiment of the present invention, the blowpipe includes a plurality of blowpipes uniformly arranged circumferentially along the housing.

[0015] According to one embodiment of the present invention, each of the blowpipes includes a plurality of sets of nozzles spaced apart along the axial direction of the blowpipe, and each set of nozzles includes a plurality of nozzles uniformly arranged circumferentially along the blowpipe.

[0016] According to one embodiment of the present invention, the nozzle is a trumpet shape that gradually expands from the inside to the outside in the radial direction, and the aspect ratio of the nozzle is between 2 and 6.

[0017] According to one embodiment of the present invention, the nozzle includes two sets of sidewalls that are opposite to each other and connected to each other, wherein one set of sidewalls is perpendicular to the axis of the blowpipe, and the other set of sidewalls is arranged symmetrically with an included angle of 30 to 40° between them.

[0018] According to one embodiment of the present invention, the nozzles of different blowpipes are staggered in the axial direction.

[0019] According to one embodiment of the present invention, the arrangement spacing between adjacent nozzles gradually increases in the direction from the flue hood to the discharge hood.

[0020] According to one embodiment of the present invention, each group of nozzles includes at least three nozzles, wherein at least one nozzle has its outlet direction facing the inner wall of the housing, and at least two of the nozzles are facing the return air pipe.

[0021] The present invention also provides a method for low-temperature drying of titanium concentrate using the above-mentioned equipment, comprising the following steps:

[0022] The flue gas generated from the combustion of coal gas enters the rotary kiln shell through the main flue gas pipe, so that the flue gas and titanium concentrate can exchange heat indirectly.

[0023] After heat exchange, the flue gas is discharged from the rotary kiln shell through the return gas pipe and the flue gas hood. The flue gas is treated and at least a portion of the treated flue gas is guided to the flue gas branch pipe. The flue gas then enters the injection pipe through the flue gas branch pipe and the rotary joint, and is then sprayed out by the nozzle. This blows away the loose titanium concentrate particles that were initially adhered to the inner wall of the rotary kiln shell and the return gas pipe into the rotary kiln.

[0024] The flue gas that enters the rotary kiln through the nozzle is discharged from the rotary kiln shell along with the furnace gas through the furnace gas hood.

[0025] The pressure of the flue gas entering the rotary joint through the flue gas branch pipe is controlled at 0.12-0.20 MPa, the temperature of the rotary kiln sintering chamber is controlled at 90-120℃, the pressure inside the sintering chamber is controlled at 120Pa-200Pa, and the furnace gas temperature is between 70℃ and 90℃.

[0026] By adopting the above technical solutions, the present invention has at least one of the following beneficial effects compared with the prior art:

[0027] (1) The equipment of the present invention is designed with flue gas branch pipe and rotary joint, and uses part of the flue gas discharged from the rotary kiln as injection gas, which not only solves the problem of titanium concentrate caking, but also realizes the efficient utilization of resources.

[0028] (2) The equipment of the present invention comprehensively optimizes the position, orientation, quantity, arrangement and shape of the blow pipe and the nozzle, and realizes effective removal of the material adhering to the inner wall of the rotary kiln and the return gas pipe wall within the entire range;

[0029] (3) The method of the present invention comprehensively controls the pressure, temperature and blowing gas pressure in the furnace, so that the adhering titanium concentrate is in a dry and loose state, which is easy to remove by blowing, thereby better ensuring the blowing removal effect. Attached Figure Description

[0030] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0031] Figure 1 A schematic diagram of the overall structure of the device for preventing caking of titanium concentrate during low-temperature drying in a rotary kiln according to an embodiment of the present invention.

[0032] Figure 2 for Figure 1 A schematic diagram of the radial section of the equipment used to prevent caking of titanium concentrate during low-temperature drying in a rotary kiln.

[0033] Figure 3 This is an enlarged view of the blowpipe and a set of nozzles according to an embodiment of the present invention.

[0034] List of reference numerals in the attached diagram:

[0035] 1. Flue gas branch pipe; 2. Rotary joint; 3. Main inlet pipe; 4. Discharge hood; 5. Pulse jet pipe; 6. Return gas pipe; 7. Flue gas hood; 8. Furnace gas hood; 9. Main flue gas pipe; 10. Rotary kiln steel shell; 11. Nozzle. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention.

[0037] This invention provides a device for preventing caking of titanium concentrate during low-temperature drying in a rotary kiln. For example... Figure 1 As shown, the equipment generally includes a shell 10 with a sintering chamber, a flue gas hood 7 and a furnace gas hood 8 disposed at the feed end of the shell, a discharge hood 4 disposed at the discharge end of the shell, a main flue gas pipe 9 disposed in the sintering chamber, a return gas pipe 6 located radially between the main flue gas pipe 9 and the inner wall of the shell 10, and a blower pipe 5 located radially between the return gas pipe 6 and the inner wall of the shell 10.

[0038] The blowpipe 5 is equipped with a nozzle 11, and the blowpipe 5 is connected to a rotary joint 2 located near the discharge hood 4 so that the blowpipe 5 rotates together with the shell 10. The rotary joint 2 is also connected to a flue gas branch pipe 1 located outside the shell. The flue gas branch pipe 1 receives at least a portion of the flue gas discharged from the rotary kiln through the return gas pipe 6 and the flue gas hood 7 after indirect heat exchange with the titanium concentrate in the sintering chamber.

[0039] Specifically, the shell 10 of the rotary kiln can be made of steel and is cylindrical. Multiple blowpipes 5 can be evenly arranged along the circumference of the shell 10. Depending on the diameter of the shell 10, the number of blowpipes 5 can be set to 3 to 6. Figure 1-2 In the illustrated embodiment, the number of blowpipes 5 is three. For example... Figure 2 As shown, the three blow pipes 5 are evenly distributed in the circumferential direction and are located in the radial direction between their respective return pipes 6 and the inner wall of the housing 10.

[0040] The blowpipe 5 extends from the flue gas hood 7 to the discharge hood 4. One end of each blowpipe 5 is fixedly connected to the rotary kiln sidewall at the flue gas hood 7, and the other end is connected to the main inlet pipe 3. The main inlet pipe 3 is located near the discharge hood 4 and gathers multiple blowpipes 5 together. The other end of the main inlet pipe 3 is connected to the rotary joint 2. The rotary joint 2 is fixed at the center of the discharge hood 4 at the kiln tail, and its other end is connected to the flue gas branch pipe 1. The flue gas branch pipe 1 can be connected to the exhaust pipe of the flue gas treatment system. For example, the flue gas that enters the rotary kiln through the main flue gas pipe 9 and indirectly exchanges heat with the titanium concentrate is discharged from the rotary kiln through the return gas pipe 6 and the flue gas hood 7. After entering the flue gas dust removal system and the flue gas induced draft fan, part of the flue gas enters the chimney for discharge, and part of the flue gas flows to the flue gas branch pipe 1 as the blowpipe gas. By using part of the rotary kiln's exhaust gas as the blowpipe gas, the problem of titanium concentrate caking is solved, and the efficient utilization of resources is also achieved.

[0041] like Figure 1 As shown, each blowpipe 5 includes multiple sets of nozzles spaced apart along the axial direction of the blowpipe 5, and each set of nozzles includes multiple nozzles 11 evenly arranged circumferentially along the blowpipe 5 (see reference). Figure 3 The number of nozzle groups is determined based on the length of the blowpipe 5 and the number of return air pipes 6. A blowpipe is arranged with an arc length of 2.5–3.1 m, radii of the center of the blowpipe and the center of the rotary kiln. For example, if the distance between the blowpipe and the centerline of the rotary kiln is 2.8 m, then 3–4 blowpipes are arranged. The rules for determining the number of nozzles per blowpipe along its length are as follows: For areas with severe adhesion (e.g., caking material thickness greater than 3 mm), the center-to-center distance between two adjacent nozzles is 1.1–1.3 times the nozzle length; for areas with moderate adhesion (e.g., caking material thickness between 1 and 3 mm), the center-to-center distance between two adjacent nozzles is 1.3–1.8 times the nozzle length; for areas with slight adhesion (e.g., caking material thickness less than 1 mm), the center-to-center distance between two adjacent nozzles is 1.8–2.6 times the nozzle length. The nozzle arrangement rules in the circumferential direction of the blowpipes are as follows: Based on the number of return gas pipes, except for the nozzles used to purge the furnace wall, each of the remaining nozzles purges 2 to 3 return gas pipes. Furthermore, there is a boundary between the nozzles of each blowpipe and the extended areas of the nozzles of other blowpipes along the circumference of the rotary kiln cross-section. The nozzles 11 of different blowpipes 5 are staggered axially. In the direction from the flue gas hood 7 to the discharge hood 4, the spacing between adjacent nozzles 11 gradually increases to ensure a larger blowing range and a more thorough cleaning effect.

[0042] In some embodiments, each group of nozzles may include at least three nozzles, wherein at least one nozzle has its air outlet direction facing the inner wall of the housing 10 to clean material adhering to the inner wall of the housing 10, and at least two nozzles are facing the return air pipe 6 to clean material adhering to the outside of the return air pipe 6. Figure 3In the illustrated embodiment, each group of nozzles includes three nozzles 11. One of the three nozzles 11 has its outlet direction facing the inner wall of the housing 10, while the other two nozzles face the return air pipe 6.

[0043] like Figure 3 As shown, the nozzle 11 is a trumpet shape that gradually expands radially from the inside out. The nozzle can be elongated, with an aspect ratio between 2 and 6. The nozzle 11 includes two sets of sidewalls that are opposite to each other and connected to each other. The first set of sidewalls is perpendicular to the axis of the blowpipe 5, and the second set of sidewalls is symmetrically arranged with an angle of 30 to 40° between them. That is, when the two centerlines (radial direction) of the first set of sidewalls are connected together, the plane formed is the plane of symmetry of the second set of sidewalls. The angle between each of the second set of sidewalls and this plane of symmetry is 15 to 20°. Setting the nozzle 11 in this shape can expand the cleaning range.

[0044] The present invention also provides a method for low-temperature drying of titanium concentrate using the above-mentioned equipment, the method comprising:

[0045] The flue gas generated from the combustion of coal gas enters the rotary kiln shell through the main flue gas pipe, so that the flue gas and titanium concentrate can exchange heat indirectly.

[0046] After heat exchange, the flue gas is discharged from the rotary kiln shell through the return gas pipe and the flue gas hood. The flue gas is treated and at least a portion of the treated flue gas is guided to the flue gas branch pipe. The flue gas enters the injection pipe through the flue gas branch pipe and the rotary joint, and then is sprayed out by the nozzle. This blows away the loose titanium concentrate particles that were initially adhered to the inner wall of the rotary kiln shell and the return gas pipe into the rotary kiln.

[0047] The flue gas that enters the rotary kiln through the nozzle is discharged from the rotary kiln shell along with the furnace gas through the furnace gas hood.

[0048] The pressure of the flue gas entering the rotary joint through the flue gas branch pipe is controlled at 0.12-0.20 MPa, the temperature of the rotary kiln sintering chamber is controlled at 90-120℃, the pressure inside the sintering chamber is controlled at 120Pa-200Pa, and the furnace gas temperature is between 70℃ and 90℃.

[0049] In some embodiments, the gas pressure entering the main inlet pipe 3 is controlled between 0.12 and 0.20 MPa to ensure that the loose titanium concentrate particles initially adhering to the inner wall of the rotary kiln and the return gas pipe 6 can be dispersed. The temperature of the rotary kiln sintering chamber is controlled between 90 and 120°C to prevent moisture in the furnace gas from condensing again and causing the titanium concentrate to agglomerate. The pressure inside the rotary kiln is controlled between 120 Pa and 200 Pa, and the furnace gas temperature is between 70°C and 90°C, so that the titanium concentrate particles inside the furnace are in a state that is easy to blow away.

[0050] Using the above method, the flue gas generated from the combustion of coal gas enters the rotary kiln through the main flue gas pipe 9 and indirectly exchanges heat with the titanium concentrate. After heat exchange, the flue gas passes through the return gas pipe 6, the flue gas hood 7, the flue gas dust removal system, and the flue gas induced draft fan. Part of the flue gas enters the chimney for discharge, while the other part passes through the flue gas branch pipe 1, the rotary joint 2, the main inlet pipe 3, and then enters the injection pipe 5, and then enters the rotary kiln through the nozzle 11. The flue gas entering the rotary kiln is then carried by the furnace gas induced draft fan through the furnace gas hood 8, the furnace gas dust removal system, and the furnace gas induced draft fan before entering the chimney for exhaust, thus utilizing part of the flue gas to solve the problem of titanium concentrate caking.

[0051] The following are specific experimental examples of equipment for preventing caking of titanium concentrate during low-temperature drying in a rotary kiln according to the present invention. Unless otherwise stated, the raw materials, consumables, etc. used in the following examples can be obtained through conventional commercial means.

[0052] For the part involving numerical range, those skilled in the art can choose any value in the numerical range defined by the present invention according to actual needs, and are not limited to the values ​​listed in the specific embodiments.

[0053] Experimental Example 1

[0054] A blowpipe with five nozzles is installed inside a 500 kg / h rotary kiln in the laboratory. The blowpipe is welded to the kiln head and tail. The nozzles are 80 mm long and 15 mm wide, with a 15° chamfer. The spacing between adjacent nozzles is 500 mm.

[0055] Air was heated to 95°C to replace the flue gas, and the hot air pressure was controlled at 0.20 MPa. The moisture content of the titanium concentrate entering the kiln was 11.5%–12%. After 108 hours of operation, the area near the inner wall of the rotary kiln directly opposite the nozzle was smooth, while the remaining areas were covered with titanium concentrate with a thickness of 1–3 mm.

[0056] Experimental Example 2

[0057] Three injection pipes were installed in a 230,000-ton / year titanium concentrate drying rotary kiln for testing. Each injection pipe had five nozzles, with the nozzle positions staggered from each other. The nozzles were 100mm long and 20mm wide, with a 20° chamfer. Flue gas at 95℃ and 0.15MPa was introduced into the rotary kiln through flue gas branch pipe 1. After two months of operation, no titanium concentrate caking was observed on the inner wall of the rotary kiln or on the surface of the four nearby return gas pipes.

[0058] The above embodiments merely illustrate implementation methods of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this patent should be determined by the appended claims.

Claims

1. A device for preventing caking of titanium concentrate during low-temperature drying in a rotary kiln, characterized in that, Include: A shell with a sintering cavity; A flue gas hood and a furnace gas hood are installed at the feed end of the housing; A discharge hood is provided at the discharge end of the housing; The main flue gas pipe is installed inside the sintering chamber; A return gas pipe located radially between the main flue gas pipe and the inner wall of the housing; A blowpipe is located radially between the return gas pipe and the inner wall of the shell. The blowpipe is equipped with a nozzle and is connected to a rotary joint located near the discharge hood so that the blowpipe rotates with the shell. This blows loose titanium concentrate particles initially adhered to the inner wall of the rotary kiln shell and the return gas pipe into the rotary kiln. The rotary joint is also connected to a flue gas branch pipe located outside the shell. The flue gas branch pipe receives at least a portion of the flue gas discharged from the rotary kiln through the return gas pipe and the flue gas hood after indirect heat exchange with the titanium concentrate in the sintering chamber. In the direction from the flue hood to the discharge hood, the spacing between adjacent nozzles gradually increases.

2. The equipment for preventing caking of titanium concentrate during low-temperature drying in a rotary kiln according to claim 1, characterized in that, The blowpipe extends from the flue gas hood to the discharge hood.

3. The equipment for preventing caking of titanium concentrate during low-temperature drying in a rotary kiln according to claim 1, characterized in that, The blowpipe includes a plurality of blowpipes evenly arranged circumferentially along the housing.

4. The equipment for preventing caking of titanium concentrate during low-temperature drying in a rotary kiln according to claim 1, characterized in that, Each of the jet pipes includes multiple sets of nozzles spaced apart along the axial direction of the jet pipe, and each set of nozzles includes multiple nozzles evenly arranged circumferentially along the jet pipe.

5. The equipment for preventing caking of titanium concentrate during low-temperature drying in a rotary kiln according to claim 1, characterized in that, The nozzle is a trumpet shape that gradually expands from the inside to the outside in the radial direction, and the length-to-width ratio of the nozzle is between 2 and 6.

6. The equipment for preventing caking of titanium concentrate during low-temperature drying in a rotary kiln according to claim 5, characterized in that, The nozzle includes two sets of sidewalls that are opposite to each other and connected to each other. One set of sidewalls is perpendicular to the axis of the blow pipe, and the other set of sidewalls is arranged symmetrically with an angle of 30 to 40° between them.

7. The equipment for preventing caking of titanium concentrate during low-temperature drying in a rotary kiln according to claim 4, characterized in that, The nozzles of different jet pipes are staggered in the axial direction.

8. The equipment for preventing caking of titanium concentrate during low-temperature drying in a rotary kiln according to claim 4, characterized in that, Each set of nozzles includes at least three nozzles, wherein at least one nozzle has its outlet direction facing the inner wall of the housing, and at least two of the nozzles are facing the return air pipe.

9. A method for low-temperature drying of titanium concentrate using the equipment as described in any one of claims 1-8, characterized in that, Includes the following steps: The flue gas generated from the combustion of coal gas enters the rotary kiln shell through the main flue gas pipe, so that the flue gas and titanium concentrate can exchange heat indirectly. After heat exchange, the flue gas is discharged from the rotary kiln shell through the return gas pipe and the flue gas hood. The flue gas is treated and at least a portion of the treated flue gas is guided to the flue gas branch pipe. The flue gas then enters the injection pipe through the flue gas branch pipe and the rotary joint, and is then sprayed out by the nozzle. This blows away the loose titanium concentrate particles that were initially adhered to the inner wall of the rotary kiln shell and the return gas pipe into the rotary kiln. The flue gas that enters the rotary kiln through the nozzle is discharged from the rotary kiln shell along with the furnace gas through the furnace gas hood. The pressure of the flue gas entering the rotary joint through the flue gas branch pipe is controlled at 0.12~0.20MPa, the temperature of the rotary kiln sintering chamber is controlled at 90~120℃, the pressure inside the sintering chamber is controlled at 120Pa~200Pa, and the furnace gas temperature is between 70℃~90℃.

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