Lipidolite lithium extraction pyrogenic process section waste heat recovery system

Abstract

The invention discloses a lepidolite lithium extraction pyrogenic process section waste heat recovery system which is characterized in that a feeding assembly is connected with a feeding port of a preheating kiln; a discharge port of the preheating kiln is connected with a feed port of the roasting kiln; the air blower is arranged at the position close to a discharging port of the roasting kiln, so that high-temperature smoke in the roasting kiln sequentially passes through a feeding port of the roasting kiln and a discharging port of the preheating kiln in the direction opposite to the material moving direction to enter the preheating kiln. A discharge port of the roasting kiln is connected with a feed port of the cooling kiln; the air cooler is arranged at a position near a feeding hole of the cooling kiln; the exhaust assembly is connected with a part near a discharge port of the cooling kiln and a part near a discharge port of the preheating kiln and is used for conveying hot air in the cooling kiln into the preheating kiln; and the waste heat recovery device is used for recovering residual waste heat in the preheating kiln. According to the invention, the waste heat of the pyrogenic process section in the process of extracting lithium from lepidolite can be comprehensively, efficiently and economically recovered, and the preheating effect of the material can be effectively enhanced.

Description

Technical Field

[0001] The invention relates to the technical field of waste heat recovery, and in particular to a waste heat recovery system for a lithium extraction pyrometallurgical process from lepidolite. Background Art

[0002] Lithium extraction from lithium mica often uses sulfate roasting. In the pyrometallurgical section, the lithium mica concentrate is preheated in a preheating kiln, then enters a roasting kiln for high-temperature calcination, and then cools in a cooling kiln to form lithium-containing clinker. In this process, the temperature of the high-temperature flue gas in the roasting kiln and the lithium-containing clinker in the cooling kiln can reach 900-1000°C. However, in the current process practice, there are some problems with the recovery of waste heat in the pyrometallurgical section of lithium extraction from lithium mica. Either only the waste heat of the roasting kiln is recycled, or only the waste heat of the cooling kiln is recycled. The waste heat recovery source is single. Since the waste heat of the high-temperature flue gas of the roasting kiln and the waste heat of the clinker of the cooling kiln are not effectively utilized at the same time, the waste heat resources of the pyrometallurgical section are wasted. In addition, there are still some waste heat recovery technologies in the pyrometallurgical section of lithium extraction from lithium mica that have high costs. Summary of the invention

[0003] The present invention aims to solve at least one of the technical problems existing in the prior art. To this end, one purpose of the present invention is to provide a waste heat recovery system for the pyrometallurgical stage of lithium extraction from lepidolite, which can comprehensively, efficiently and economically recover the waste heat of the pyrometallurgical stage in the process of lithium extraction from lepidolite, and can effectively enhance the preheating effect of the material.

[0004] The waste heat recovery system for lithium extraction from lepidolite by pyrometallurgy according to an embodiment of the present invention comprises a feed assembly, a preheating kiln, a roasting kiln, a cooling kiln, a blower, a cooler, an exhaust assembly and a waste heat recovery device;

[0005] Wherein, the feed assembly is connected to the feed port of the preheating kiln and is used to transport materials to the preheating kiln;

[0006] The discharge port of the preheating kiln is connected to the feed port of the roasting kiln so that the material in the preheating kiln enters the roasting kiln;

[0007] The blower is arranged near the discharge port of the roasting kiln and is used to blow air into the roasting kiln, so that the high-temperature flue gas in the roasting kiln passes through the feed port of the roasting kiln and the discharge port of the preheating kiln in the reverse direction of the material movement and enters the preheating kiln in sequence;

[0008] The discharge port of the roasting kiln is connected to the feed port of the cooling kiln so that the material in the roasting kiln enters the cooling kiln;

[0009] The cooling fan is arranged near the feeding port of the cooling kiln and is used to blow cold air into the cooling kiln;

[0010] The exhaust assembly is connected to a portion near the discharge port of the cooling kiln and a portion near the discharge port of the preheating kiln, and is used to transport the hot air in the cooling kiln to the preheating kiln;

[0011] The waste heat recovery device is used to recover the remaining waste heat in the preheating kiln.

[0012] According to the waste heat recovery system for the pyrometallurgical stage of lithium extraction from lepidolite according to the embodiment of the present invention, a blower is arranged at a position near the discharge port of the roasting kiln, so that the high-temperature flue gas in the roasting kiln flows from the position near the discharge port of the roasting kiln to the position near the feed port of the preheating kiln in the opposite direction of the material movement, so that the high-temperature flue gas fully and efficiently preheats the material before entering the roasting kiln, and at the same time, an exhaust component is arranged between the position near the discharge port of the cooling kiln and the position near the discharge port of the preheating kiln, so that the hot air near the discharge port in the cooling kiln passes through the exhaust component from the position near the discharge port of the cooling kiln to the position near the feed port of the preheating kiln in the opposite direction of the material movement. Directional flow allows the hot air to fully and efficiently preheat the materials before entering the roasting kiln. Therefore, the materials before entering the roasting kiln are preheated by using the waste heat of the high-temperature flue gas from the roasting kiln and the waste heat of the hot air from the cooling kiln at the same time, which greatly enhances the material preheating effect. In addition, the residual heat of the high-temperature flue gas from the roasting kiln and the residual heat of the hot air from the cooling kiln near the feed inlet of the preheating kiln can be recovered and processed by the waste heat recovery device, thereby fully and comprehensively realizing the waste heat recovery, greatly reducing energy consumption, avoiding the waste of waste heat resources, building an efficient and circular heat energy recovery system, and reducing production costs.

[0013] In summary, the waste heat recovery system for the pyrometallurgical stage of lithium extraction from lepidolite in the embodiment of the present invention can comprehensively, efficiently and economically recover the waste heat of the pyrometallurgical stage in the process of lithium extraction from lepidolite, and can effectively enhance the preheating effect of the material.

[0014] In some embodiments, the preheating kiln, the roasting kiln and the cooling kiln are arranged in descending order.

[0015] In some embodiments, a first material discharge chute is further included, wherein the upper end of the first material discharge chute is connected to the discharge port of the preheating kiln, and the lower end of the first material discharge chute is connected to the feed port of the roasting kiln.

[0016] In some embodiments, a perforated screen structure is provided in the first feed chute.

[0017] In some embodiments, a second feeding chute is further included, wherein the upper end of the second feeding chute is connected to the discharge port of the roasting kiln, and the lower end of the second feeding chute is connected to the feed port of the cooling kiln.

[0018] In some embodiments, the second feed chute is S-shaped.

[0019] In some embodiments, a plurality of guide plates are provided on the inner wall surface of the second material discharge chute.

[0020] In some embodiments, the exterior of the first material discharge chute and the exterior of the second material discharge chute are both provided with heat-insulating components.

[0021] In some embodiments, the exhaust assembly includes an exhaust duct and a first induced draft fan, the two ends of the exhaust duct are respectively connected to a portion near the discharge port of the cooling kiln and a portion near the discharge port of the preheating kiln, and the first induced draft fan is arranged in the exhaust duct.

[0022] In some embodiments, a heat preservation pipe is provided on the outside of the exhaust duct.

[0023] In some embodiments, the inner wall of the preheating kiln and the inner wall of the cooling kiln are both provided with lifting plates.

[0024] In some embodiments, it also includes a second induced draft fan and a cyclone separator, wherein the air inlet of the second induced draft fan is connected to a portion near the feed inlet of the preheating kiln, the air outlet of the second induced draft fan is connected to the air inlet of the cyclone separator, the waste heat recovery device is connected to the air outlet of the cyclone separator, and a filter is provided in the waste heat recovery device.

[0025] In some embodiments, the feed assembly includes a raw material bin and a conveyor, and the raw material bin is connected to the feed port of the preheating kiln through the conveyor.

[0026] Additional aspects and advantages of the present invention will be given in part in the following description and in part will be obvious from the following description, or will be learned through practice of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] The above and / or additional aspects and advantages of the present invention will become apparent and easily understood from the description of the embodiments in conjunction with the following drawings, in which:

[0028] Figure 1 It is a schematic diagram of the waste heat recovery system of the lithium extraction pyrometallurgy stage of lepidolite of the present invention;

[0029] Figure 2 It is a schematic diagram of the internal structure of the first feeding chute of the waste heat recovery system for extracting lithium from lepidolite by pyrometallurgy of the present invention;

[0030] Figure 3 This is a schematic diagram of the internal structure of the second feed chute of the waste heat recovery system for extracting lithium from lepidolite by pyrometallurgy according to the present invention.

[0031] Reference numerals:

[0032] Waste heat recovery system 1000 for lithium extraction from lithium mica by pyrometallurgy; feed assembly 1; raw material bin 101; conveyor 102; preheating kiln 2; roasting kiln 3; cooling kiln 4; blower 5; air cooler 6; exhaust assembly 7; exhaust duct 701; first induced draft fan 702; waste heat recovery device 8; first feed chute 9; perforated screen structure 901; second feed chute 10; guide plate 1001; second induced draft fan 11; cyclone separator 12. DETAILED DESCRIPTION

[0033] Embodiments of the present invention are described in detail below, examples of which are shown in the accompanying drawings, wherein the same or similar reference numerals throughout represent the same or similar elements or elements having the same or similar functions. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, and cannot be understood as limiting the present invention.

[0034] Combine the following Figures 1 to 3 The waste heat recovery system 1000 for extracting lithium from lepidolite by pyrometallurgy according to an embodiment of the present invention is described.

[0035] like Figures 1 to 3 As shown, the waste heat recovery system 1000 for extracting lithium from lithium mica by pyrolysis according to an embodiment of the present invention includes a feeding component 1, a preheating kiln 2, a roasting kiln 3, a cooling kiln 4, a blower 5, a cooler 6, an exhaust component 7 and a waste heat recovery device 8.

[0036] The feed assembly 1 is connected to the feed port of the preheating kiln 2 and is used to convey materials to the preheating kiln 2 so that the materials are preheated in the preheating kiln 2. Here, the materials conveyed by the feed assembly 1 can be understood as lepidolite raw materials.

[0037] The discharge port of the preheating kiln 2 is connected to the feed port of the roasting kiln 3, so that the material in the preheating kiln 2 enters the roasting kiln 3. After the material is preheated in the preheating kiln 2, it passes through the discharge port of the preheating kiln 2 and the feed port of the roasting kiln 3 in sequence and enters the roasting kiln 3 for high-temperature calcination. At the same time, high-temperature flue gas is generated in the roasting kiln 3.

[0038] The blower 5 is arranged near the discharge port of the roasting kiln 3, and is used to blow air into the roasting kiln 3, so that the high-temperature flue gas in the roasting kiln 3 passes through the feed port of the roasting kiln 3 and the discharge port of the preheating kiln 2 in the reverse direction of the material movement direction and enters the preheating kiln 2. Since the material moves in the roasting kiln 3 from the feed port of the roasting kiln 3 to the discharge port of the roasting kiln 3, when the blower 5 is not provided, the high-temperature flue gas will flow with the movement of the material. Therefore, by arranging the blower 5 near the discharge port of the roasting kiln 3, the high-temperature flue gas in the roasting kiln 3 is reversed in the direction of the material movement, and the high-temperature flue gas passes through the feed port of the roasting kiln 3 and the discharge port of the preheating kiln 2 in turn and enters the preheating kiln 2, and flows in the preheating kiln 2 in the reverse direction of the material movement direction toward the feed port of the preheating kiln 2, and the high-temperature flue gas can preheat the material in the preheating kiln 2 and in the path from the roasting kiln 3 to the preheating kiln 2. That is to say, the material before entering the roasting kiln 3 is preheated by utilizing the waste heat of the high-temperature flue gas from the roasting kiln 3 .

[0039] The discharge port of the roasting kiln 3 is connected to the feed port of the cooling kiln 4, so that the material in the roasting kiln 3 enters the cooling kiln 4. After the preheated material is subjected to high-temperature calcination in the roasting kiln 3, it passes through the discharge port of the roasting kiln 3 and the feed port of the cooling kiln 4 in sequence and enters the cooling kiln 4 for cooling, and the cooled material is the required cooled clinker.

[0040] The air cooler 6 is arranged near the feed inlet of the cooling kiln 4, and is used to blow cold air into the cooling kiln 4. Since the moving direction of the material in the cooling kiln 4 is from the feed inlet of the cooling kiln 4 to the discharge port of the cooling kiln 4, by arranging the air cooler 6 near the feed inlet of the cooling kiln 4, the cold air is blown into the cooling kiln 4, so that the cold air flows from the feed inlet of the cooling kiln 4 to the discharge port of the cooling kiln 4 along with the material, and the cold air exchanges heat with the high-temperature material after calcination, so that the material is efficiently and fully cooled to obtain the desired clinker, which is discharged from the discharge port of the cooling kiln 4 (see Figure 1 At the same time, the wind flowing to the vicinity of the discharge port of the cooling kiln 4 is hot wind, and the temperature of the wind flowing to the vicinity of the discharge port of the cooling kiln 4 is higher than the temperature of the wind at other parts of the cooling kiln 4.

[0041] The exhaust assembly 7 is connected to the part near the discharge port of the cooling kiln 4 and the part near the discharge port of the preheating kiln 2, and is used to transport the hot air in the cooling kiln 4 to the preheating kiln 2. Since the temperature of the air flowing to the part near the discharge port of the cooling kiln 4 is higher than the temperature of the air in other parts of the cooling kiln 4, it is hot air. Therefore, by connecting the exhaust assembly 7 to the part near the discharge port of the cooling kiln 4 and the part near the discharge port of the preheating kiln 2, the hot air in the part near the discharge port of the cooling kiln 4 can be transported from the part near the discharge port of the preheating kiln 2 to the preheating kiln 2, and the hot air flows in the direction of the feed port of the preheating kiln 2 in the opposite direction of the movement of the material, so as to preheat the material in the preheating kiln 2. That is to say, the material before entering the roasting kiln 3 is preheated not only by the waste heat of the high-temperature flue gas from the roasting kiln 3, but also by the waste heat of the hot air from the cooling kiln 4 (that is, the waste heat of the clinker in the cooling kiln).

[0042] The waste heat recovery device 8 is used to recover the remaining waste heat in the preheating kiln 2. The residual heat of the high-temperature flue gas from the roasting kiln 3 and the residual heat of the hot air from the cooling kiln 4 at the location near the discharge port of the preheating kiln 2 can be recovered and processed by the waste heat recovery device 8, thereby fully realizing the waste heat recovery of the pyrometallurgical stage. Optionally, the waste heat recovery device 8 can be a conventional waste heat recovery device or other waste heat recovery devices.

[0043] According to the waste heat recovery system 1000 for the lithium extraction pyrometallurgical stage of lithium mica of the embodiment of the present invention, a blower 5 is arranged at a position near the discharge port of the roasting kiln 3, so that the high-temperature flue gas in the roasting kiln 3 flows in the opposite direction of the material movement from the position near the discharge port of the roasting kiln 3 to the position near the feed port of the preheating kiln 2, so that the high-temperature flue gas fully and efficiently preheats the material before entering the roasting kiln 3, and at the same time, an exhaust component 7 is arranged between the position near the discharge port of the cooling kiln 4 and the position near the discharge port of the preheating kiln 2, so that the hot air near the discharge port of the cooling kiln 4 passes through the exhaust component 7 from the position near the discharge port of the cooling kiln 4 to the position near the feed port of the preheating kiln 2 in the opposite direction. The material flows in the moving direction so that the hot air can fully and efficiently preheat the material before entering the roasting kiln 3. Therefore, the material before entering the roasting kiln 3 is preheated by using the waste heat of the high-temperature flue gas from the roasting kiln 3 and the waste heat of the hot air from the cooling kiln 4 at the same time, which greatly enhances the material preheating effect. In addition, the residual heat of the high-temperature flue gas from the roasting kiln 3 and the residual heat of the hot air from the cooling kiln 4 near the feed port of the preheating kiln 2 can be recovered and processed by the waste heat recovery device 8, thereby fully and comprehensively realizing the waste heat recovery, greatly reducing energy consumption, avoiding the waste of waste heat resources, constructing an efficient and circular heat energy recovery system, and reducing production costs.

[0044] In summary, the waste heat recovery system 1000 for the pyrometallurgical stage of lithium extraction from lepidolite according to the embodiment of the present invention can comprehensively, efficiently and economically recover the waste heat of the pyrometallurgical stage during the lithium extraction process from lepidolite.

[0045] In some embodiments, the heights of the preheating kiln 2, roasting kiln 3 and cooling kiln 4 are arranged from high to low in sequence. In this way, it is beneficial for the materials in the preheating kiln 2 to automatically enter the roasting kiln 3 by their own gravity, and for the materials in the roasting kiln 3 to automatically enter the cooling kiln 4 by their own gravity.

[0046] Optionally, the arrangement position of the feeding assembly 1 is higher than the arrangement position of the preheating kiln 2, so that the material can enter the preheating kiln 2 by its own gravity. The arrangement position of the feeding assembly 1 may also be not higher than the arrangement position of the preheating kiln 2, and the feeding assembly 1 can transport the material to the feed port of the preheating kiln 2 by power.

[0047] In some embodiments, a first feeding chute 9 is further included, the upper end of the first feeding chute 9 is connected to the discharge port of the preheating kiln 2, and the lower end of the first feeding chute 9 is connected to the feed port of the roasting kiln 3. In this way, the material in the preheating kiln 2 falls from the discharge port of the preheating kiln 2 along the first feeding chute 9 under the action of its own gravity and enters the roasting kiln 3 from the feed port of the roasting kiln 3. At the same time, the high-temperature flue gas in the roasting kiln 3 enters the first feeding chute 9 from the inlet of the roasting kiln 3 and rises along the first feeding chute 9, and then enters the preheating kiln 2 from the discharge port of the preheating kiln 2. Therefore, in the first feeding chute 9, the high-temperature flue gas exchanges heat with the material, preheats the material before entering the roasting kiln 3, and enhances the preheating effect of the material. It should be noted that the first feeding chute 9 can be arranged vertically or inclined.

[0048] In some embodiments, Figure 2 As shown, a perforated screen structure 901 is provided in the first material discharge chute 9, so that the material is evenly scattered in the first material discharge chute 9, increasing the contact area between the high-temperature flue gas of the roasting kiln 3 and the material. In addition, the residence time of the material can be increased, so that the high-temperature flue gas and the material are in contact for a longer time, and the heat exchange preheating effect is more significant.

[0049] Preferably, the perforated screen structure 901 can be provided with multiple layers so that the material can be scattered more evenly in the first discharge chute 9, thereby increasing the contact area between the high-temperature flue gas of the roasting kiln 3 and the material. In addition, the residence time of the material can be further increased, so that the high-temperature flue gas and the material are in contact for a longer time, and the heat exchange preheating effect is more significant.

[0050] In some embodiments, a second material chute 10 is further included, the upper end of which is connected to the discharge port of the roasting kiln 3, and the lower end of which is connected to the feed port of the cooling kiln 4. In this way, the material in the roasting kiln 3 falls from the discharge port of the roasting kiln 3 along the second material chute 10 under the action of its own gravity and enters the cooling kiln 4 from the feed port of the cooling kiln 4, exchanging heat with the cold air blown in by the cooling fan 6.

[0051] In some embodiments, the second feeding chute 10 is S-shaped. The S-shaped second feeding chute 10 can impact and break the clinker agglomerates that have been calcined at high temperature for multiple times, which is beneficial to increase the heat exchange area of ​​the subsequent cooling link and improve the heat exchange efficiency.

[0052] In some embodiments, a plurality of guide plates 1001 are provided on the inner wall surface of the second material discharge chute 10. The plurality of guide plates 1001 can utilize the gravity of the material itself to repeatedly break up the molten agglomerated material, thereby achieving the purpose of breaking up and increasing the cooling effect of the material in the cooling kiln 4.

[0053] Preferably, a plurality of guide plates 1001 are distributed on opposite sides of the inner wall of the second material discharge chute 10 , and the molten agglomerated material can be repeatedly crushed by the gravity of the material itself to achieve the crushing purpose and increase the cooling effect of the material in the cooling kiln 4 .

[0054] In some embodiments, the outside of the first feeding chute 9 and the outside of the second feeding chute 10 are both provided with insulation components (not shown in the figure). The insulation components on the outside of the first feeding chute 9 can significantly reduce the waste heat loss of the high-temperature flue gas, and the insulation components on the outside of the second feeding chute 10 are used to keep the high-temperature material warm, avoid preheating losses, and facilitate waste heat collection.

[0055] In some embodiments, the exhaust assembly 7 includes an exhaust duct 701 and a first induced draft fan 702. The two ends of the exhaust duct 701 are respectively connected to the portion near the discharge port of the cooling kiln 4 and the portion near the discharge port of the preheating kiln 2. The first induced draft fan 702 is arranged in the exhaust duct 701. The first induced draft fan 702 mainly provides power, and can introduce the hot air at the portion near the discharge port of the cooling kiln 4 into the exhaust duct 701, so that the hot air enters the preheating kiln 2 from the portion near the discharge port of the preheating kiln 2 along the exhaust duct 701.

[0056] In some embodiments, an insulation pipe (not shown in the figure) is provided on the outside of the exhaust duct 701 , and the insulation pipe can significantly reduce the waste heat loss of the hot air when the hot air passes through the exhaust duct 701 .

[0057] In some embodiments, the inner wall of the preheating kiln 2 and the inner wall of the cooling kiln 4 are both provided with lifting plates (not shown in the figure). The lifting plates in the preheating kiln 2 can increase the material dispersion area, which is beneficial to improving the material preheating effect; the lifting plates in the cooling kiln 4 can increase the material dispersion area, which is beneficial to improving the material heat exchange effect.

[0058] In some embodiments, a second induced draft fan 11 and a cyclone separator 12 are also included, the air inlet of the second induced draft fan 11 is connected to the part near the feed inlet of the preheating kiln 2, the air outlet of the second induced draft fan 11 is connected to the air inlet of the cyclone separator 12, the waste heat recovery device 8 is connected to the air outlet of the cyclone separator 12, and a filter is provided in the waste heat recovery device 8. Among them, the second induced draft fan 11 mainly provides power, and the high-temperature flue gas and hot air near the feed inlet of the preheating kiln 2 are first introduced into the cyclone separator 12 for dust removal, and the high-temperature flue gas and hot air after dust removal enter the waste heat recovery device 8 for residual waste heat recovery and utilization. Since a filter is provided in the waste heat recovery device 8, dust can be further filtered.

[0059] In some embodiments, the feed assembly 1 includes a raw material bin 101 and a conveyor 102, wherein the raw material bin 101 is connected to the feed port of the preheating kiln 2 via the conveyor 102. The raw material bin 101 is used to store the lepidolite material to be preheated, and the conveyor 102 is used to transport the material discharged from the raw material bin 101 to the feed port of the roasting kiln 3. Optionally, the conveyor 102 may be a belt conveyor 102.

[0060] Although the embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the claims and their equivalents.

Claims

1. A waste heat recovery system for lithium extraction from lepidolite by pyrometallurgy, characterized in that: It includes a feed assembly, a preheating kiln, a roasting kiln, a cooling kiln, a blower, a cooler, an exhaust assembly and a waste heat recovery device; Wherein, the feed assembly is connected to the feed port of the preheating kiln and is used to transport materials to the preheating kiln; The discharge port of the preheating kiln is connected to the feed port of the roasting kiln so that the material in the preheating kiln enters the roasting kiln; The blower is arranged near the discharge port of the roasting kiln and is used to blow air into the roasting kiln, so that the high-temperature flue gas in the roasting kiln passes through the feed port of the roasting kiln and the discharge port of the preheating kiln in the reverse direction of the material movement and enters the preheating kiln in sequence; The discharge port of the roasting kiln is connected to the feed port of the cooling kiln so that the material in the roasting kiln enters the cooling kiln; The cooling air blower is arranged near the feeding port of the cooling kiln and is used to blow cold air into the cooling kiln; The exhaust assembly is connected to a portion near the discharge port of the cooling kiln and a portion near the discharge port of the preheating kiln, and is used to transport the hot air in the cooling kiln to the preheating kiln; The waste heat recovery device is used to recover the remaining waste heat in the preheating kiln.

2. The waste heat recovery system for extracting lithium from lepidolite by pyrometallurgy according to claim 1, characterized in that: The preheating kiln, the roasting kiln and the cooling kiln are arranged in descending order of height.

3. The waste heat recovery system for extracting lithium from lepidolite by pyrometallurgy according to claim 2, characterized in that: It also includes a first material discharge chute, the upper end of which is connected to the discharge port of the preheating kiln, and the lower end of which is connected to the feed port of the roasting kiln.

4. The waste heat recovery system for extracting lithium from lepidolite by pyrometallurgy according to claim 3, characterized in that: A perforated screen structure is provided in the first feed chute.

5. The waste heat recovery system for extracting lithium from lepidolite by pyrometallurgy according to claim 3, characterized in that: It also includes a second material discharge chute, the upper end of which is connected to the discharge port of the roasting kiln, and the lower end of which is connected to the feed port of the cooling kiln.

6. The waste heat recovery system for extracting lithium from lepidolite by pyrometallurgy according to claim 5, characterized in that: The second feed chute is S-shaped.

7. The waste heat recovery system for extracting lithium from lepidolite by pyrometallurgy according to claim 5, characterized in that: A plurality of guide plates are arranged on the inner wall surface of the second material discharge chute.

8. The waste heat recovery system for extracting lithium from lepidolite by pyrometallurgy according to claim 5, characterized in that: The exterior of the first material discharge chute and the exterior of the second material discharge chute are both provided with heat-insulating components.

9. The waste heat recovery system for extracting lithium from lepidolite by pyrometallurgy according to any one of claims 1 to 8, characterized in that: The exhaust assembly includes an exhaust duct and a first induced draft fan. Both ends of the exhaust duct are respectively connected to a portion near the discharge port of the cooling kiln and a portion near the discharge port of the preheating kiln. The first induced draft fan is arranged in the exhaust duct.

10. The waste heat recovery system for extracting lithium from lepidolite by pyrometallurgy according to claim 9, characterized in that: A heat preservation pipe is arranged outside the exhaust pipe.

11. The waste heat recovery system for extracting lithium from lepidolite by pyrometallurgy according to any one of claims 1 to 8, characterized in that: The inner wall of the preheating kiln and the inner wall of the cooling kiln are both provided with lifting plates.

12. The waste heat recovery system for extracting lithium from lepidolite by pyrometallurgy according to any one of claims 1 to 8, characterized in that: It also includes a second induced draft fan and a cyclone separator, wherein the air inlet of the second induced draft fan is connected to a portion near the feed inlet of the preheating kiln, the air outlet of the second induced draft fan is connected to the air inlet of the cyclone separator, the waste heat recovery device is connected to the air outlet of the cyclone separator, and a filter is provided in the waste heat recovery device.

13. The waste heat recovery system for extracting lithium from lepidolite by pyrometallurgy according to any one of claims 1 to 8, characterized in that: The feed assembly comprises a raw material bin and a conveyor, and the raw material bin is connected to the feed port of the preheating kiln through the conveyor.

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