An externally heated rotary kiln for acidification and roasting of spodumene

Abstract

The present invention discloses an externally heated rotary furnace for the acidification and roasting of spodumene. The furnace body is supported by rollers I and II on a supporting device, and the furnace body is driven to rotate by gear meshing transmission on a transmission device. The feeding device and the discharging device are respectively arranged at the front and rear ends of the cylinder, and a crushing spiral and / or a free spiral that can move freely along the inner cavity is built into the furnace body. An air inlet and an air outlet are provided on the jacket device. The feeding device adopts a double-helix mixing blade structure or a single-helix continuous blade structure. A dust cleaning spiral is provided at both ends of the furnace body at the feeding and discharging devices. The externally heated rotary furnace heats the material in a continuous and indirect manner, and the heat-carrying gas does not directly contact the spodumene mixed acid material, thereby reducing the acid-containing flue gas treatment process. The purity of the acid clinker produced by the spodumene acidification and roasting reaction is improved, and multiple air inlets and outlets effectively avoid insufficient reaction due to too low temperature. The crushing spiral and / or free spiral built into the furnace body can prevent the material from forming a wall inside the furnace body, thereby preventing the heat transfer efficiency from being reduced due to the wall forming and causing insufficient reaction.

Description

Technical Field

[0001] The invention relates to an externally heated rotary kiln for acidification and roasting of spodumene, in particular to an externally heated rotary kiln for the production process of preparing spodumene acid clinker by mixing spodumene with sulfuric acid for heating and acidification reaction. Background Art

[0002] Since the discovery of spodumene, lithium, as a rare metal element, has played a crucial role in modern construction, with widespread applications in glass, ceramics, petroleum, chemicals, metallurgy, synthetic rubber, light metal welding, lubricants, nuclear power generation, high-energy batteries, air conditioning and refrigeration equipment, and military supplies. With the development of new energy technologies, demand for lithium batteries has rapidly increased, and so has the demand for lithium salts. With the rising demand for high-nickel ternary lithium batteries and materials, the demand for spodumene, the raw material used to prepare lithium salts, has become even stronger.

[0003] The existing method for extracting lithium from spodumene is mainly the sulfuric acid method, and the core process step of this method is the process of acidification and roasting to prepare spodumene acid clinker. The equipment used for the existing acidification and roasting to prepare spodumene acid clinker mainly includes two production methods: internal heating type and external heating type rotary furnace. The working principle of the internal heating type rotary furnace is to reduce the gas generated after the combustion of the fuel to the temperature required by the process through air distribution and then directly pass it into the rotary furnace body. The high-temperature gas directly contacts the material in the furnace body, realizing the high-temperature acidification and roasting process of spodumene. The working principle of the external heating type rotary furnace is to force the gas generated after the combustion of the fuel to exchange heat with the outer wall of the furnace body, and heat the material in the furnace body through heat transfer outside the furnace body to realize the process of preparing acid clinker.

[0004] During the production process of existing internally heated rotary kilns for acid roasting spodumene, the heat-carrying gas directly contacts the spodumene mixed acid feed, generating a large amount of acidic gas. This exhaust gas is large in volume and difficult to purify. Furthermore, a large amount of powdered raw material is carried away with the exhaust gas, resulting in significant raw material loss. Internally heated reaction temperatures are difficult to control. Excessively high reaction temperatures lead to a significant amount of sulfuric acid vaporization and decomposition during the reaction, increasing sulfuric acid consumption. Direct contact of the heat-carrying gas with the feed introduces impurities into the feed, reducing product purity.

[0005] The existing externally heated rotary furnace for acidification and roasting of spodumene has only a material turning and lifting plate inside the furnace body, which cannot solve the problem that the material absorbs heat and becomes sticky during the heating process, and is easily adhered to the inner wall of the furnace body. This eventually leads to poor heat transfer in the furnace body, causing material blockage in the furnace body, which causes inconvenience to continuous production. Summary of the Invention

[0006] The purpose of the present invention is to provide an externally heated rotary kiln for the acidification and roasting of spodumene. The externally heated rotary kiln heats the material in a continuous and indirect manner, the heat-carrying gas does not directly contact the spodumene mixed acid material, the tail gas does not contain acid gas, and the acid-containing flue gas treatment process is reduced; the externally heated indirect heating method isolates the material reaction from the outside world, improves the purity of the acid clinker produced by the spodumene acidification and roasting reaction, and reduces the workload of subsequent purification. The externally heated jacket can be provided with multiple air inlets and outlets, and reasonable air distribution can be carried out according to the temperature required for the material reaction, so that the temperature of the material reaction is more reasonable, and effectively avoids insufficient reaction due to too low temperature; excessively high temperature causes sulfuric acid to vaporize and decompose, reducing the amount of sulfuric acid used and reducing production costs. Providing a free spiral in the furnace body can prevent the material from forming a wall in the furnace body, and prevent the heat transfer efficiency caused by the wall from being reduced and causing insufficient reaction.

[0007] To achieve the above objectives, the embodiments of the present invention adopt the following technical solutions:

[0008] According to an embodiment provided by the present invention, the present invention provides an externally heated rotary furnace for acidification and roasting of spodumene, comprising a furnace body, a supporting device, a roller, a large gear ring, a jacket device, a sealing device, a transmission device, a feeding device and a discharging device, wherein the furnace body is supported by rollers I and II on the supporting device, and the furnace body is driven to rotate by gear meshing transmission on the transmission device; the feeding device and the discharging device are respectively arranged at the head and tail of the cylinder, and a crushing spiral and / or a free spiral that moves freely along the inner cavity is built into the furnace body; an air inlet and outlet are provided on the jacket device; the feeding device adopts a double-helix mixing blade structure or a single-helix continuous blade structure, a cleaning spiral II is provided at the head of the furnace body at the feeding device, and a cleaning spiral I is provided at the tail of the furnace body at the discharging device.

[0009] Regarding the above technical solution, the present invention has a further preferred solution.

[0010] Preferably, the feeding device includes a feeding conveyor, a feeding box and a sealing device. The feeding conveyor adopts a double-helix mixing blade structure, including a shell, two spiral shafts distributed along the length direction of the cylinder connected by a driving device and a coupling inside the shell, and blades are distributed on the spiral shafts, and the blades are staggered at angles of 90° and / or 180°.

[0011] Preferably, the feed conveyor adopts a single spiral continuous blade structure.

[0012] Preferably, the feed conveyor is replaced by a feed chute, and the feed chute is connected to the feed box.

[0013] Preferably, the two screw shafts rotate in opposite directions, one rotating in a forward direction and the other rotating in a reverse direction.

[0014] Preferably, the crushing spiral that moves freely along the inner cavity of the furnace body is arranged at the end of the furnace feeding device, and the free spiral that moves freely along the inner cavity of the furnace body is arranged at the middle section of the furnace body.

[0015] Preferably, the crushing spiral is a shaftless spiral structure, with a number of parallel pull rods distributed along the circumference of the spiral blades, and the pull rods are fixedly connected to the spiral blades; the outer diameter of the crushing spiral is 0.2 to 0.9 times the inner diameter of the furnace body.

[0016] Preferably, the free spiral is a shaft spiral structure, with spiral blades distributed along the length of the spiral shaft, and the spiral shaft and the spiral blades are fixedly connected; the outer diameter of the free spiral is 0.1 to 0.5 times the inner diameter of the furnace body.

[0017] Preferably, a plurality of wireless temperature sensors are provided on the furnace body, and the wireless temperature sensors are connected to the central control room via a wireless temperature receiver outside the furnace body, and feed back temperature information to the central control room.

[0018] Preferably, the inner cavity of the furnace body is provided with shoveling plates radially distributed along the inner wall of the furnace body, and the shoveling plates are distributed at the rear end of the furnace body.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1) The rotary kiln feeding conveyor adopts a double-helix mixing blade structure, which can fully mix the materials while conveying them into the furnace body, so as to make the reaction more complete.

[0021] 2) The rotary kiln adopts external indirect heating, and the heat-carrying gas does not directly contact the spodumene mixed acid material. The tail gas does not contain acid gas, which reduces the acid-containing flue gas treatment process; the external indirect heating method isolates the material reaction from the outside world, improves the purity of the acid clinker produced by the spodumene acidification roasting reaction, and reduces the workload of subsequent purification.

[0022] 3) The crushing spiral and / or free spiral move freely in the furnace body, which can prevent the materials from sticking to the wall and stir the materials to make the materials more evenly mixed and the reaction more complete.

[0023] 4) The shovel board distributed at the rear of the furnace body can reduce the wear of the material on the inner wall of the furnace body, increase the service life of the equipment, reduce costs and increase economic benefits.

[0024] 5) The dust cleaning spirals at both ends of the furnace body can push the dust deposited between the inlet and outlet boxes and the furnace body into the inlet and outlet boxes to avoid affecting the sealing of the sealing device when too much dust accumulates. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings, in which:

[0026] Figure 1 This is a schematic structural diagram of an externally heated rotary kiln for acidification and roasting of spodumene according to the present invention;

[0027] Figure 2 It is a structural diagram of the feed conveyor;

[0028] Figure 3 It is a schematic diagram of the cylinder device structure.

[0029] The reference numerals in the figure are as follows: 1. feed conveyor; 2. feed box; 3. sealing device; 4. rolling ring I; 5. jacket device; 6. air outlet; 7. furnace body; 8. rolling ring II; 9. large gear ring; 10. discharge box; 11. discharge port; 12. transmission device; 13. blocking roller device; 14. air inlet; 15. supporting roller device; 16. driving device; 17. coupling; 18. screw shaft; 19. paddle; 20. shell; 21. crushing spiral; 22. free spiral; 23. copying plate; 24. cleaning spiral I; 25. temperature measuring device; 26. cleaning spiral II. DETAILED DESCRIPTION

[0030] The present invention will be described in detail below with reference to the accompanying drawings and specific embodiments.

[0031] like Figure 1 As shown, the externally heated rotary furnace for acidification and roasting of spodumene comprises a furnace body 7, a supporting device, a roller ring, a large gear ring 9, a jacket device 5, a sealing device 3, a transmission device 12, a feeding device and a discharging device; roller ring I4 and roller ring II8 are provided on the furnace body 7, which are supported by a stop roller device 13 and a support roller device 15 respectively; the large gear ring 9 is provided on the furnace body 7 near the stop roller device 13, and drives the furnace body 7 to rotate continuously on the supported stop roller device 13 and the support roller device 15 by meshing with the small gear on the transmission device 12; the main motor in the transmission device 12 adopts a variable frequency speed regulation motor, which can adapt to the requirements for the speed of the furnace body 7 under different working conditions. The feeding device at the front end of the furnace body 7 comprises a feed conveyor 1 and a feed box 2, with a sealing device 3 provided between the feed box 2 and the furnace body 7. A discharge box 10 is located at the rear end of the furnace body 7 and is provided with a discharge port 11, through which the material is discharged and enters the next process. The furnace body 7 is provided with multiple wireless temperature sensors 25 for measuring the material temperature. The wireless temperature sensors 25 accurately measure the material temperature and feed it back to the central control room via a wireless temperature receiver on the outside of the furnace body 7. Based on this feedback and the material sampling and testing results, the hot air volume passing through the jacket device 5 is promptly adjusted to ensure that the material reacts fully at a reasonable reaction temperature. A sealing device 3 is provided between the discharge box 10 and the furnace body 7. The sealing device 3 has excellent sealing properties and can effectively prevent acid mist and dust from overflowing from the furnace body 7 and polluting the environment. It also reduces the consumption of sulfuric acid and saves production costs.

[0032] The jacket device 5 mounted on the furnace body 7 can be equipped with one or more air inlets 14 and one or more air outlets 6. Heat-carrying gas enters the hot air channel formed by the jacket device 5, the furnace body 7, and the sealing device 3 through the air inlets 14, indirectly heating the material. The jacket device 5 employs an internal insulation structure, making installation and maintenance simple and convenient. The sealing devices 3 at both ends of the jacket device 5 effectively prevent hot air from escaping, reducing heat loss.

[0033] like Figure 2 As shown, in order to ensure that the spodumene acid mixture is evenly mixed and quickly enters the furnace body 7, a feed conveyor 1 is provided at the front end of the furnace body 7. Its structure can be a double-helix mixing blade structure or a single-helix continuous blade structure. The feed conveyor 1 with a double-helix mixing blade structure includes a housing 20. Inside the housing 20, a driving device 16 and a coupling 17 are connected to two screw shafts 18 distributed along the length of the cylinder. Paddles 19 are distributed on the screw shafts 18. During operation, the driving device 16 drives the screw shafts 18 to rotate through the coupling 17. One of the double helices rotates in the forward direction and the other rotates in the reverse direction. The paddles 19 on the screw shafts 18 can fully stir the materials to make the materials more evenly mixed and the reaction more complete, while at the same time conveying the materials into the furnace body 7.

[0034] The feeding method of the feeding conveyor 1 can be changed to a feeding chute method, the feeding chute is connected to the feeding box, the outlet of the feeding chute extends into the interior of the furnace body 7, and the material enters the interior of the furnace body 7 through the chute.

[0035] like Figure 3 , a crushing spiral 21 and / or a free spiral 22 that can move freely along the inner cavity of the inner furnace body 7 are provided in the furnace body 7. The crushing spiral 21 is provided at the feeding device end of the furnace body 7, and the free spiral 22 is provided in the middle section of the furnace body 7. In one embodiment, the crushing spiral 21 is a shaftless spiral structure, with a number of parallel pull rods distributed along the circumference of the spiral blades, and the pull rods are fixedly connected to the spiral blades; the outer diameter of the crushing spiral 21 is 0.2 to 0.9 times the inner diameter of the furnace body 7. In another embodiment, the free spiral 22 is a shafted spiral structure, with spiral blades distributed along the length direction of the spiral shaft; the outer diameter of the free spiral 22 is 0.1 to 0.5 times the inner diameter of the furnace body 7. The crushing spiral 21 and the free spiral 22 can be provided separately or simultaneously. Their function is to crush agglomerated materials, make the mixing more complete, prevent the materials from sticking to the wall, and also have the function of stirring the materials.

[0036] The shoveling plate 23 is distributed at the rear end of the furnace body 7 and radially distributed along the inner wall of the furnace cavity, which can reduce the wear of the furnace body 7 by the material and increase the service life of the equipment.

[0037] At the inlet and outlet ends of the furnace body, cleaning spirals II 26 and I 24 are provided, which can push the dust deposited between the inlet and outlet boxes and the furnace body 7 into the inlet and outlet boxes to avoid dust accumulation.

[0038] It should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein with equivalents.

[0039] Any modifications, equivalent substitutions, improvements, etc. made within the spirit, principles and purpose of the present invention and within the scope of knowledge possessed by ordinary technicians in this field should be included in the scope of protection of the present invention.

Claims

1. An externally heated rotary kiln for acidification and roasting of spodumene, comprising a furnace body (7), a supporting device, a roller ring, a large gear ring (9), a jacket device (5), a sealing device (3), a transmission device (12), a feeding device and a discharging device, wherein the furnace body (7) is supported by roller rings I and II (4, 8) on the supporting device, and the transmission device (12) drives the furnace body (7) to rotate through gear meshing transmission; the feeding device and the discharging device are respectively arranged at the head and tail of the furnace body (7); the jacket device (5) is provided with an air inlet and an air outlet (14, 6); and the characteristics are as follows: A crushing spiral (21) and a free spiral (22) are built into the furnace body (7) and are free to move along the inner cavity; the feeding device adopts a double-spiral mixing blade structure or a single-spiral continuous blade structure; a ash cleaning spiral II (26) is provided at the head of the furnace body of the feeding device; and a ash cleaning spiral I (24) is provided at the tail of the furnace body of the discharging device; A crushing spiral (21) that moves freely along the inner cavity of the furnace body (7) is provided at the feeding device end of the furnace body (7), and a free spiral (22) that moves freely along the inner cavity of the furnace body (7) is provided at the middle section of the furnace body (7); The crushing spiral (21) is a shaftless spiral blade structure, with a plurality of parallel pull rods distributed along the circumference of the spiral blade, and the pull rods are fixedly connected to the spiral blade; the outer diameter of the crushing spiral (21) is 0.2 to 0.9 times the inner diameter of the furnace body (7); The free spiral (22) is a spiral structure with an axis, and spiral blades are distributed along the length direction of the spiral axis, and the spiral axis and the spiral blades are fixedly connected; the outer diameter of the free spiral (22) is 0.1 to 0.5 times the inner diameter of the furnace body (7); A feeding conveyor (1) is provided at the front end of the furnace body (7), and its structure is a double-helix mixing blade structure; one rotates in the forward direction and the other rotates in the reverse direction.

2. A kind of externally heated rotary kiln for acidification roasting of spodumene according to claim 1, characterized in that, The feeding device comprises a feeding conveyor (1), a feeding box (2) and a sealing device (3). The feeding conveyor (1) adopts a double-helix mixing blade structure, comprising a shell (20), a driving device (16) and a coupling (17) connected to a spiral shaft (18) distributed along the length direction of the cylinder in the shell (20), and blades (19) distributed on the spiral shaft (18). The blades (19) are staggered at angles of 90° and / or 180°.

3. A kind of externally heated rotary kiln for acidification and roasting of spodumene according to claim 2, characterized in that, The feed conveyor (1) adopts a single spiral continuous blade structure instead of a double spiral mixing blade structure.

4. A kind of externally heated rotary kiln for acidification and roasting of spodumene according to claim 2, characterized in that, The feed conveyor (1) is replaced by a feed chute, and the feed chute is connected to the feed box (2).

5. A kind of externally heated rotary kiln for acidification roasting of spodumene according to claim 1, characterized in that, A plurality of wireless temperature sensors (25) are provided on the furnace body (7), and the wireless temperature sensors (25) are connected to the central control room via wireless temperature receivers outside the furnace body.

6. A kind of externally heated rotary kiln for acidification roasting of spodumene according to claim 1, characterized in that, The inner cavity of the furnace body (7) is provided with a scavenging plate (23) distributed radially along the inner wall of the furnace body, and the scavenging plate (23) is distributed at the rear end of the furnace body (7).

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