Apparatus and method for preventing clumping during indirect drying of titanium concentrate

Abstract

The application discloses a device for preventing titanium concentrate from being agglomerated in an indirect drying process, comprising: a shell with a sintering cavity; a flue gas cover and a furnace gas cover arranged at a feeding end of the shell; a discharging cover arranged at a 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 an inner wall of the shell; and a blowing pipe between the return gas pipe and the main flue gas pipe in a radial direction. The blowing pipe is provided with a nozzle, the blowing pipe is connected with a gas inlet main pipe fixedly arranged at the center of the discharging cover and does not rotate with the shell, and the gas inlet main pipe is further connected with a flue gas branch pipe arranged outside the shell, the flue gas branch pipe receives at least part of flue gas discharged from a rotary kiln through the return gas pipe and the flue gas cover after the flue gas is indirectly exchanged with the titanium concentrate in the sintering cavity. The application further 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 agglomeration of the titanium concentrate, and have the advantages of high efficiency, low cost and the like.

Description

Technical Field

[0001] The invention belongs to the technical field of titanium concentrate production and processing, and in particular relates to a device and a method for preventing titanium concentrate from hardening during indirect drying. Background Art

[0002] Titanium concentrate production is based on tailings from iron-containing composite iron ores, which are then enriched after beneficiation. Titanium concentrate enrichment methods are primarily categorized into dry and wet processes. Dry processes include electric furnace smelting, plasma smelting, selective chlorination, and other thermal reduction methods. Wet processes include partial reduction-hydrochloric acid leaching, partial reduction-sulfuric acid leaching, reduction corrosion, and full reduction-hydrochloric acid leaching. Both dry and wet methods involve high-temperature processing of titanium concentrate. However, after flotation, titanium concentrate typically contains 8-12% moisture. Directly subjecting this water-containing titanium concentrate to high-temperature processes will negatively impact the redox roasting efficiency and energy consumption. Therefore, drying and dehydrating the water-containing titanium concentrate before feeding it into the furnace is essential.

[0003] The commonly used drying method for titanium concentrate is to use rotary kiln drying. Rotary kiln drying is to dry the water-containing titanium concentrate by contacting it with high-temperature flue gas. In this drying method, the flotation titanium concentrate enters the kiln from one end of the rotary kiln, is heated and dried during the movement in the kiln, and is finally discharged from the lower discharge port at the other end of the kiln body. There are two drying methods for titanium concentrate: direct drying and indirect drying. Since the titanium concentrate has fine particle size and a wide particle size distribution range, particles below 200 mesh (0.074mm) account for more than 75%; the material has high moisture content and is easy to agglomerate; the specific gravity is high, and the true specific gravity reaches 4.30t / m 3 Due to its poor fluidity and other characteristics, direct drying of titanium concentrate results in significant losses and a poor production environment. Furthermore, due to the high initial temperature during the drying process, flotation agents are easily decomposed or volatilized, emitting a pungent odor, polluting the environment and seriously affecting people's lives. Indirect drying is more environmentally friendly and appropriate for drying titanium concentrate. However, due to the high specific gravity of titanium concentrate, it slides along the inner wall of the drying rotary kiln after entering it, resulting in fine particle size and high moisture content. Indirect drying can cause the titanium concentrate to cling to the flue gas return duct and the inner wall of the drying rotary kiln, increasing equipment load and reducing production efficiency.

[0004] Based on the above technical background, it is necessary to propose a device and method for preventing titanium concentrate from compacting during the indirect drying process. Summary of the Invention

[0005] To address at least one of the existing technical problems, the present invention provides an apparatus and method for preventing compaction during the indirect drying of titanium concentrate. This apparatus and method utilizes a portion of the exhaust gas from the rotary kiln as injection gas, effectively resolving the problem of titanium concentrate compaction while also achieving efficient resource utilization.

[0006] According to the present invention, there is provided an apparatus for preventing caking during indirect drying of titanium concentrate, comprising:

[0007] a housing having a sintered cavity;

[0008] A fume hood and a furnace gas hood are provided at the feed end of the shell;

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

[0010] A main flue gas pipe arranged in the sintering chamber;

[0011] a return air duct located radially between the main flue gas duct and the inner wall of the shell;

[0012] The blowing pipe is located radially between the return air pipe and the main flue gas pipe, and is provided with a nozzle. The blowing pipe is connected to the air intake main pipe fixedly installed in the center of the discharge hood and does not rotate with the shell. The air intake main pipe is also connected to the flue gas branch pipe arranged outside the shell. The flue gas branch pipe receives at least a part of the flue gas discharged from the rotary kiln through the return air 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 blowing pipe extends from the furnace gas hood to the discharge hood.

[0014] According to one embodiment of the present invention, the blowing pipes include at least three blowing pipes evenly arranged along the circumference of the shell.

[0015] According to one embodiment of the present invention, each blowing pipe includes a plurality of nozzles, and the axial positions of the nozzles on all the blowing pipes are different.

[0016] According to one embodiment of the present invention, the nozzle is trumpet-shaped and 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.

[0017] According to one embodiment of the present invention, the nozzle includes two sets of side walls that are opposite to each other and connected to each other, wherein one set of side walls is perpendicular to the axis of the blowing pipe, and the other set of side walls has an angle of 30 to 40 degrees with each other and is symmetrically arranged.

[0018] According to one embodiment of the present invention, the number of the blowing pipes is three, wherein the multiple nozzles of the first blowing pipe are arranged at the front section near the furnace gas hood, the multiple nozzles of the second blowing pipe are arranged near the middle section between the furnace gas hood and the discharge hood, and the multiple nozzles of the third blowing pipe are arranged on the tail section near the discharge hood.

[0019] According to one embodiment of the present invention, the arrangement intervals between adjacent nozzles gradually increase in the direction from the furnace gas hood to the discharge hood.

[0020] According to one embodiment of the present invention, the gas outlet directions of all nozzles are radially outward and not vertically upward.

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

[0022] The flue gas generated by burning coal gas enters the rotary kiln shell through the main flue gas pipe to indirectly exchange heat with the titanium concentrate;

[0023] The flue gas after heat exchange is discharged from the rotary kiln shell through the return air pipe and the flue gas hood, and the flue gas is treated. At least a part of the treated flue gas is guided to the flue gas branch pipe, so that the flue gas enters the injection pipe after passing through the flue gas branch pipe and the air intake main pipe, and is then sprayed out from the nozzle;

[0024] The rotary kiln shell is rotated while the injection pipe is kept stationary. The rotation of the shell causes the injection gas to sweep the entire circumference of the shell and the return pipe, blowing away the loose titanium concentrate particles initially adhered to the inner wall of the rotary kiln shell and the return pipe into the rotary kiln.

[0025] The flue gas entering the rotary kiln through the nozzle is discharged out of the rotary kiln shell together with the furnace gas through the furnace gas hood;

[0026] The pressure of the flue gas entering the air inlet main pipe is controlled between 0.18 and 0.25 MPa, the temperature of the injected flue gas is controlled between 90 and 120°C, the pressure in the sintering chamber is controlled between -120Pa and -200Pa, and the furnace gas temperature is controlled between 75°C and 105°C.

[0027] Due to the adoption of the above technical solution, the present invention has at least one of the following beneficial effects compared with the prior art:

[0028] (1) The equipment of the present invention is designed with a flue gas branch pipe, which utilizes part of the flue gas discharged from the rotary kiln as the injection gas, thereby solving the problem of titanium concentrate compaction and achieving efficient resource utilization;

[0029] (2) The equipment of the present invention is designed so that the blowpipe does not rotate with the rotary kiln shell, that is, the shell can rotate relative to the blowpipe. Therefore, only a small number of nozzles need to be provided on the blowpipe to achieve cleaning of the entire circumference of the shell;

[0030] (3) The injection pipe is set between the main flue gas pipe and the return gas pipe, and a small number of nozzles can be used to clean the inner wall of the shell and the return gas pipe at the same time;

[0031] (4) The method of the present invention comprehensively controls the pressure, temperature and injection gas pressure in the furnace, so that the adhered titanium concentrate is in a dry and loose state and is easy to be sprayed off, thereby better ensuring the spraying and cleaning effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0032] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0033] Figure 1 Schematic diagram of the overall structure of an apparatus for preventing compaction during indirect drying of titanium concentrate according to an embodiment of the present invention;

[0034] Figure 2 for Figure 1 A schematic radial cross-sectional view of an apparatus for preventing caking during indirect drying of titanium concentrate is shown;

[0035] Figure 3 FIG. 1 is an enlarged view of a blowpipe and a set of nozzles according to an embodiment of the present invention.

[0036] List of reference numerals:

[0037] 1 Main flue gas pipe; 2 Injection pipe; 3 Furnace gas hood; 4 Flue gas hood; 5 Return gas pipe; 6 Flue gas branch pipe; 7 Inlet main pipe; 8 Discharge hood; 9 Nozzle; 10 Shell. DETAILED DESCRIPTION

[0038] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention.

[0039] The present invention provides a device for preventing caking during the indirect drying process of titanium concentrate. Figure 1 As shown, the device generally comprises a shell 10 having a sintering chamber, a fume hood 4 and a furnace gas hood 3 arranged at the feed end of the shell, a discharge hood 8 arranged at the discharge end of the shell, a main fume pipe 1 arranged in the sintering chamber and near the central axis, a return air pipe 5 radially located between the main fume pipe 1 and the inner wall of the shell 10, and a blowing pipe 2 radially located between the return air pipe 5 and the main fume pipe 1 (refer to FIG. Figure 2 ).

[0040] The blowpipe 2 is equipped with a nozzle 9 and is connected to an air intake main 7 fixedly mounted at the center of the discharge hood 4. The blowpipe 2 does not rotate with the housing 10. The air intake main 7 is also connected to a flue gas branch 6 located outside the housing 10. The flue gas branch 6 receives at least a portion of the flue gas discharged from the rotary kiln through the return air duct 5 and the flue gas hood 4 after indirect heat exchange with the titanium concentrate in the sintering chamber.

[0041] Specifically, the shell 10 of the rotary kiln can be made of a steel shell, which is cylindrical. At least three blowing pipes 2 can be arranged evenly along the circumference of the shell. The number of the blowing pipes 2 is determined according to the length of the rotary kiln 10. Figure 1-2 In the embodiment shown, the number of the blowing pipes 2 is three. Figure 2 As shown, the three injection pipes 2 are evenly distributed in the circumferential direction and are located between the return air pipe 5 and the main flue gas pipe 1 in the radial direction.

[0042] The injection pipe 2 extends from the furnace gas hood 3 to the discharge hood 8. One end of each injection pipe 2 is fixedly connected to the furnace gas hood 3, and the other end is connected to the air intake main pipe 7. The air intake main pipe 7 is located near the discharge hood 8 and brings together multiple injection pipes 2. The air intake main pipe 7 is fixed at the center of the discharge hood 8 at the end of the kiln and the other end is connected to the flue gas branch pipe 6. The flue gas branch pipe 6 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 1 and indirectly exchanges heat with the titanium concentrate is discharged from the rotary kiln through the return air pipe 5 and the flue gas hood 4, and then enters 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 6 as injection gas. By utilizing part of the exhaust gas from the rotary kiln as injection gas, efficient resource utilization is achieved on the basis of solving the problem of titanium concentrate compaction.

[0043] The blowpipe 2 is designed not to rotate with the rotary kiln shell 10, that is, the shell 10 can rotate relative to the blowpipe 2. Therefore, only a small number of nozzles 9 need to be installed on the blowpipe 2 to achieve cleaning of the entire circumference of the shell. In addition, the blowpipe 2 is installed between the main flue gas pipe 1 and the return gas pipe 5, so a small number of nozzles 9 can be used to simultaneously clean the inner wall of the shell 10 and the return gas pipe 5.

[0044] like Figure 1 As shown, each blow pipe 2 includes a plurality of nozzles 9, and the axial positions of the nozzles 9 on all blow pipes 2 are different. That is, the axial positions of the nozzles 9 of different blow pipes 2 are staggered from each other. The number of nozzles is determined according to the degree of bonding and the size of the nozzles. For areas with severe bonding (for example, the thickness of the board material is greater than 3mm), the center distance between two adjacent nozzles is 1.1 to 1.3 times the length of the nozzle; for areas with more severe bonding (for example, the thickness of the board material is 1 to 3mm), the center distance between two adjacent nozzles is 1.3 to 1.8 times the length of the nozzle; for areas with slight bonding (for example, the thickness of the board material is less than 1mm), the center distance between two adjacent nozzles is 1.8 to 2.6 times the length of the nozzle. Figure 1In the illustrated embodiment, there are three blowpipes 2. The multiple nozzles 9 of the first blowpipe 2 are arranged at the front section of the blowpipe near the furnace gas hood 3. The multiple nozzles 9 of the second blowpipe 2 are arranged near the middle section of the blowpipe between the furnace gas hood 3 and the discharge hood 8. The multiple nozzles 9 of the third blowpipe 2 are arranged at the rear section of the blowpipe near the discharge hood 8. The spacing between adjacent nozzles 9 gradually increases from the furnace gas hood 3 to the discharge hood 4.

[0045] In some embodiments, as Figure 3 As shown, nozzle 9 is trumpet-shaped, gradually expanding radially from the inside out, with an aspect ratio between 2 and 6. Nozzle 9 comprises two sets of opposing, interconnected sidewalls. The first set of sidewalls is perpendicular to the axis of the blowpipe 2, while the second set of sidewalls are symmetrically arranged at an angle of 30 to 40 degrees. In other words, when the two centerlines (radial direction) of the first set of sidewalls are connected together, the resulting plane becomes the plane of symmetry for the second set of sidewalls. Each of the second set of sidewalls forms an angle of 15 to 20 degrees with this plane of symmetry. This configuration of nozzle 9 expands the cleaning range.

[0046] In some embodiments, in order to prevent agglomerated titanium concentrate from entering the blowing pipe 2 and causing blockage, the gas outlet directions of all nozzles 9 are directed radially outward and not vertically upward.

[0047] The present invention also provides a method for indirectly drying titanium concentrate using the above-mentioned device, the method comprising:

[0048] The flue gas generated by burning coal gas enters the rotary kiln shell through the main flue gas pipe to indirectly exchange heat with the titanium concentrate;

[0049] The flue gas after heat exchange is discharged from the rotary kiln shell through the return air pipe and the flue gas hood, and the flue gas is treated. At least a part of the treated flue gas is guided to the flue gas branch pipe, so that the flue gas enters the injection pipe after passing through the flue gas branch pipe and the air intake main pipe, and is then sprayed out from the nozzle;

[0050] The rotary kiln shell is rotated while the injection pipe is kept stationary. The rotation of the shell causes the injection gas to sweep the entire circumference of the shell and the return pipe, blowing away the loose titanium concentrate particles initially adhered to the inner wall of the rotary kiln shell and the return pipe into the rotary kiln.

[0051] The flue gas entering the rotary kiln through the nozzle is discharged out of the rotary kiln shell together with the furnace gas through the furnace gas hood;

[0052] The pressure of the flue gas entering the air inlet main pipe is controlled between 0.18 and 0.25 MPa, the temperature of the injected flue gas is controlled between 90 and 120°C, the pressure in the sintering chamber is controlled between -120Pa and -200Pa, and the furnace gas temperature is controlled between 75°C and 105°C.

[0053] The flue gas pressure entering the main intake pipe 7 is controlled between 0.18 and 0.25 MPa to ensure that loose titanium concentrate particles initially adhering to the inner wall of the rotary kiln shell 10 and the return air pipe 5 are dispersed. The injected flue gas temperature is controlled between 90 and 120°C to prevent moisture in the furnace gas from recondensing and causing titanium concentrate agglomeration. Furthermore, comprehensive control of the furnace pressure, temperature, and injected gas pressure keeps the adhered titanium concentrate dry and loose, making it easier to remove by spraying, thereby ensuring a more effective spraying and removal process.

[0054] Using this method, flue gas generated by coal combustion enters the rotary kiln through the main flue gas pipe 1 for indirect heat exchange with the titanium concentrate. After heat exchange, the flue gas is discharged from the rotary kiln through the return gas pipe 5 and the flue gas hood 4. After passing through the flue gas dust removal system and the flue gas induced draft fan, part of the flue gas is discharged into the chimney, while part of the flue gas passes through the flue gas branch pipe 6 and the main air intake pipe 7 and enters the injection pipe 2. Then, it enters the rotary kiln through the nozzle 9 to remove loose titanium concentrate particles adhering to the inner wall of the rotary kiln shell 10 and the return gas pipe 5. Under the action of the furnace gas induced draft fan, the flue gas entering the rotary kiln is transported along with the furnace gas through the furnace gas hood 2, the furnace gas dust removal system, and the furnace gas induced draft fan into the chimney for emptying, thus achieving partial flue gas recycling to solve the problem of titanium concentrate compaction.

[0055] The following is a specific experimental example of the device for preventing caking during the indirect drying process of titanium concentrate according to the present invention. Unless otherwise specified, the raw materials and consumables used in the following examples can be obtained through conventional commercial means.

[0056] For the parts involving numerical ranges, those skilled in the art can select any value within the numerical range defined by the present invention according to actual needs, and are not limited to the numerical values ​​listed in the specific embodiments.

[0057] Experimental Example 1

[0058] A blowpipe with four nozzles was installed in a 500 kg / h rotary kiln in the laboratory. The blowpipe was welded to the kiln head and tail. The nozzles were 80 mm long, 15 mm wide, and had a 15° chamfer. Adjacent nozzles were spaced 500 mm apart.

[0059] Air is heated to 95°C to replace flue gas, and the hot air pressure is controlled at 0.25 MPa. The moisture content of the titanium concentrate entering the kiln is 11.5% to 12%. After 72 hours of operation, the inner wall of the rotary kiln is smooth and free of compaction. During operation, the titanium concentrate particles are dispersed and filled within the rotary kiln, allowing them to slide along the inner wall without adhering, thereby increasing the radiation area.

[0060] Experimental Example 2

[0061] A test was conducted using three injection pipes installed in a 230,000 ton / year titanium concentrate drying rotary kiln. Each pipe had five nozzles: one had all nozzles located in the front section, one had all nozzles located in the middle section, and another had all nozzles located in the rear section. Each nozzle was 100 mm long and 20 mm wide, with a 20° chamfer. Flue gas at 110°C and a pressure of 0.2 MPa was introduced into the rotary kiln through flue gas branch pipe 6. After four months of operation, no calcification of the titanium concentrate was observed in the return gas pipe or on the inner wall of the rotary kiln. Energy consumption per ton of ore was calculated during the test period, and gas consumption per ton of dry titanium concentrate decreased by 2.62%.

[0062] The above embodiments merely illustrate the implementation methods of the present invention. 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 a person skilled in the art would be able to make various modifications and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A device for preventing caking of titanium concentrate during indirect drying, characterized in that: Include: a housing having a sintered cavity; A fume hood and a furnace gas hood are provided at the feed end of the shell; A discharge cover provided at the discharge end of the housing; A main flue gas pipe arranged in the sintering chamber; a return air duct located radially between the main flue gas duct and the inner wall of the shell; A blow pipe is radially located between the return air pipe and the main flue gas pipe. The blow pipe is provided with a nozzle. The blow pipe is connected to an air intake main pipe fixedly installed at the center of the discharge hood and does not rotate with the shell to remove titanium concentrate particles adhering to the inner wall of the rotary kiln shell and the return air pipe. The air intake main pipe is also connected to a flue gas branch pipe arranged 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 air pipe and the flue gas hood after indirect heat exchange with the titanium concentrate in the sintering chamber; The blowing pipe extends from the furnace gas hood to the discharge hood. In the direction from the furnace gas hood to the discharge hood, the arrangement spacing between adjacent nozzles gradually increases. For areas with severe bonding of plate materials with a thickness of more than 3mm, the center distance between two adjacent nozzles is 1.1 to 1.3 times the nozzle length. For areas with severe bonding of plate materials with a thickness of 1 to 3mm, the center distance between two adjacent nozzles is 1.3 to 1.8 times the nozzle length. For areas with slight bonding of plate materials with a thickness of less than 1mm, the center distance between two adjacent nozzles is 1.8 to 2.6 times the nozzle length.

2. The device for preventing caking during indirect drying of titanium concentrate according to claim 1, characterized in that: The blowing pipes include at least three blowing pipes evenly arranged along the circumference of the shell.

3. The device for preventing compaction during indirect drying of titanium concentrate according to claim 1, characterized in that: Each blowing pipe includes a plurality of nozzles, and the axial positions of the nozzles on all the blowing pipes are different.

4. The device for preventing compaction during indirect drying of titanium concentrate according to claim 1, characterized in that: The nozzle is trumpet-shaped and 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.

5. The device for preventing compaction during indirect drying of titanium concentrate according to claim 4, characterized in that: The nozzle includes two sets of side walls that are opposite to each other and connected to each other, wherein one set of side walls is perpendicular to the axis of the blowing pipe, and the other set of side walls has an angle of 30-40 degrees between each other and is symmetrically arranged.

6. The device for preventing caking during indirect drying of titanium concentrate according to claim 2, characterized in that: There are three blowing pipes, wherein the multiple nozzles of the first blowing pipe are arranged at the front section near the furnace gas hood, the multiple nozzles of the second blowing pipe are arranged near the middle section between the furnace gas hood and the discharge hood, and the multiple nozzles of the third blowing pipe are arranged at the tail section near the discharge hood.

7. The device for preventing caking during indirect drying of titanium concentrate according to claim 6, characterized in that: The gas outlet directions of all nozzles are radially outward and not vertically upward.

8. A method for indirectly drying titanium concentrate, characterized in that: The method uses the apparatus according to any one of claims 1 to 7 and comprises the following steps: The flue gas generated by burning coal gas enters the rotary kiln shell through the main flue gas pipe to indirectly exchange heat with the titanium concentrate; The flue gas after heat exchange is discharged from the rotary kiln shell through the return air pipe and the flue gas hood, and the flue gas is treated. At least a part of the treated flue gas is guided to the flue gas branch pipe, so that the flue gas enters the injection pipe after passing through the flue gas branch pipe and the air intake main pipe, and is then sprayed out from the nozzle; The rotary kiln shell is rotated while the injection pipe is kept stationary. The rotation of the shell causes the injection gas to sweep the entire circumference of the shell and the return pipe, blowing away the loose titanium concentrate particles initially adhered to the inner wall of the rotary kiln shell and the return pipe into the rotary kiln. The flue gas entering the rotary kiln through the nozzle is discharged out of the rotary kiln shell together with the furnace gas through the furnace gas hood; The pressure of the flue gas entering the air inlet main pipe is controlled between 0.18~0.25MPa, the temperature of the injected flue gas is controlled between 90~120℃, the pressure in the sintering chamber is controlled between -120Pa~-200Pa, and the furnace gas temperature is between 75℃~105℃.

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