Downstream multi-stage heating acidification roasting kiln system

Abstract

The invention discloses a down-flow type multistage heating acidification roasting kiln system which comprises a rotary kiln body, a plurality of sets of lifting plates are arranged on the inner wall of the rotary kiln body in the circumferential direction, a flue gas flow guide interlayer is formed between the lifting plates and the inner wall of the rotary kiln body, and an air inlet main pipe is arranged in the center of the rotary kiln body in the axial direction. The front end of the air inlet main pipe is located at the feeding end of the rotary kiln body and connected with a smoke outlet of the hot air system, the rear end of the air inlet main pipe is closed, multiple sets of air inlet branch pipes are arranged between the lifting plate and the air inlet main pipe at intervals in the length direction of the air inlet main pipe, and each set of air inlet branch pipes are evenly distributed in the circumferential direction of the air inlet main pipe. The air inlet main pipe is communicated with the flue gas diversion interlayer through an air inlet branch pipe; and an air return cover is arranged at the discharge end of the rotary kiln body. The roasting kiln system adopts hot air and material down-flow multi-stage heat exchange, can reduce the discharging temperature, reduce the energy consumption, reduce the volatilization of concentrated sulfuric acid, prolong the high-temperature section time of the material and improve the conversion rate of the material.

Description

Technical Field

[0001] The invention relates to an acidification roasting kiln, in particular to a downstream multi-stage heating acidification roasting kiln system. Background Art

[0002] After mixing with acid, spodumene fine roasted material undergoes acidification and roasting at 250-330°C. After cooling, it enters the downstream stage to produce lithium carbonate. Currently, acidification and roasting equipment primarily utilizes two methods: external heating and countercurrent heat exchange with a lifting plate. External heating requires significant investment, while the countercurrent heat exchange with the lifting plate utilizes countercurrent heat exchange between hot air and the material. Once the material enters the acidification kiln, it heats up slowly, with the high-temperature section primarily concentrated at the kiln's discharge end. This results in high discharge temperatures, short high-temperature reaction times, and relatively high energy consumption under the same conditions. Simply switching from a countercurrent heat exchange with a lifting plate to a downstream type can lead to increased volatilization of concentrated sulfuric acid due to excessively high temperatures at the feed end. Summary of the Invention

[0003] Purpose of the Invention: This invention provides a co-current, multi-stage, acidification and roasting kiln system that utilizes co-current heat exchange between hot air and the material, thereby lowering discharge temperature, reducing energy consumption, and extending the high-temperature reaction time of the material under the same conditions. Furthermore, this step-by-step heating method avoids the problem of excessively high temperatures at the feed end, which can lead to increased volatilization of concentrated sulfuric acid.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions: A downstream multi-stage heating acidification roasting kiln system includes a rotary kiln body and a hot air system. The rotary kiln body is provided with a feed end and a discharge end, and is characterized in that: a plurality of groups of lifting plates are provided along the circumferential direction of the inner wall of the rotary kiln body, a smoke guide barrier is formed between the lifting plates and the inner wall of the rotary kiln body, an air inlet main pipe is provided axially at the center of the rotary kiln body, the front end of the air inlet main pipe is located at the feed end of the rotary kiln body and connected to the smoke outlet of the hot air system, the rear end of the air inlet main pipe is closed and located in the middle of the rotary kiln body, an air inlet branch pipe is provided between the lifting plates and the air inlet main pipe, a plurality of groups of air inlet branch pipes are arranged at intervals along the length direction of the air inlet main pipe, each group of air inlet branch pipes is evenly distributed along the circumference of the air inlet main pipe, the air inlet main pipe is connected to the smoke guide barrier through the air inlet branch pipe, a return air hood is provided at the discharge end of the rotary kiln body, and the return air hood is connected to the smoke guide barrier.

[0005] Furthermore, the air inlet main pipe is divided into a plurality of air inlet main pipe sections along the length direction, each air inlet main pipe section corresponds to a group of air inlet branch pipes, and the diameter of each air inlet main pipe section gradually decreases from front to back.

[0006] Furthermore, each group of air inlet branch pipes is located at the rear end of the corresponding air inlet main pipe segment.

[0007] Furthermore, the return air hood is connected to the air inlet of the circulation fan through a return air duct, and the air outlet of the circulation fan is respectively connected to the air inlet and the external exhaust chimney of the hot air system.

[0008] Furthermore, an exhaust regulating valve is provided between the air outlet of the circulating fan and the external exhaust chimney.

[0009] Furthermore, a thermal insulation layer is provided on the outside of the rotary kiln body.

[0010] Compared with the traditional acidification kiln system, the above system has the following significant advantages: 1. The material is heated in a downstream manner. The temperature rises quickly after entering the acidification kiln. Under the same conditions, the high-temperature reaction time is longer, which improves the material conversion rate. 2. The high-temperature flue gas enters the interlayer in several steps through the coordination of the air inlet main pipe and the air inlet branch pipe, thus avoiding the situation where part of the raw materials are vaporized due to excessive local temperature; 3. The overall cost is lower than that of the outer cover type, and the discharge temperature is lower than that of the countercurrent acidification kiln. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 This is a schematic diagram of the structure of a downstream multi-stage heating acidification roasting kiln system.

[0012] Figure 2 It is a schematic diagram of the cross section of the rotary kiln body.

[0013] Figure 3 This is a schematic diagram of the air inlet branch pipe layout.

[0014] In the figure: 1-rotary kiln body; 2-lifting plate; 3-air inlet branch pipe; 3-1-air inlet branch pipe 1; 3-2-air inlet branch pipe 2; 3-3-air inlet branch pipe 3; 4-hot air system; 5-air inlet main pipe; 5-1-air inlet main pipe section 1; 5-2-air inlet main pipe section 2; 5-3-air inlet main pipe section 3; 6-return air hood; 7-return air duct; 8-circulating fan; 9-exhaust regulating valve; 10-exhaust chimney; 11-feed end; 12-discharge end; 13-rotation drive device; 14-smoke guide layer. DETAILED DESCRIPTION

[0015] The present invention will be further explained below with reference to the accompanying drawings.

[0016] like Figure 1As shown, a downstream multi-stage heating acidification roasting kiln system of the present invention includes a rotary kiln body 1 and a hot air system 4. The rotary kiln body 1 serves as a carrier for acidification and roasting of materials. The hot air system 4 includes a hot air furnace for introducing high-temperature flue gas into the rotary kiln body 1 to achieve a high-temperature acidification environment inside the rotary kiln body 1. The rotary kiln body 1 is provided with a feed end 11 and a discharge end 12. The spodumene fine roasted material is mixed with acid and fed into the rotary kiln body 1 through the feed end 11 to exchange heat with the high-temperature flue gas for acidification and roasting, and then discharged through the discharge end 12. The outer side of the rotary kiln body 1 is connected to a rotary drive device 13 for driving the rotary kiln body 1 to rotate, thereby driving the rotary kiln body 1 to continuously carry out the process.

[0017] like Figure 1 and 2 As shown, a thermal insulation layer is provided on the exterior of the rotary kiln body 1. Several groups of lifting plates 2 are circumferentially arranged on the inner wall of the rotary kiln body 1, forming a flue gas diversion barrier 14 between the lifting plates 2 and the inner wall of the rotary kiln body 1. An air inlet main pipe 5 is axially arranged in the center of the rotary kiln body 1. The front end of the air inlet main pipe 5 is located at the feed end 11 of the rotary kiln body 1 and is sealed to the flue gas outlet of the hot air system 4 via fish scales. The rear end of the air inlet main pipe 1 is closed and located in the middle of the rotary kiln body 1. Air inlet branch pipes 3 are provided between the lifting plates 2 and the air inlet main pipe 5. Several groups of air inlet branch pipes 3 are arranged at intervals along the length of the air inlet main pipe, and each group of air inlet branch pipes 3 is evenly distributed along the circumference of the air inlet main pipe 5. The air inlet main pipe 5 is connected to the flue gas diversion barrier 14 through the air inlet branch pipes 3. A return air hood 6 is provided at the discharge end 12 of the rotary kiln body 1, and the return air hood 6 is connected to the flue gas diversion barrier 14.

[0018] To more quickly distribute the high-temperature flue gas generated by the hot air system 4 to each set of air inlet branch pipes 3, the main air inlet pipe is divided into several sections along its length, with each section corresponding to a set of air inlet branch pipes. The diameter of each section gradually decreases from front to back. Furthermore, each set of air inlet branch pipes is located at the rear end of its corresponding main air inlet pipe section.

[0019] like Figure 1 and 3As shown, in this embodiment, twelve groups of lifting plates are arranged along the circumferential direction of the inner wall of the rotary kiln body 1, and three groups of air inlet branch pipes 3 are arranged at intervals along the length direction of the air inlet main pipe 5, namely, air inlet branch pipe 1 3-1, air inlet branch pipe 2 3-2, and air inlet branch pipe 3 3-3. The number of air inlet branch pipes 3 in each group is the same as the number of the two groups of lifting plates, that is, 12, and the three groups have a total of thirty-six. Twelve groups of lifting plates are arranged along the circumferential direction of the inner wall of the rotary kiln body 1, and each group of lifting plates 2 corresponds to three air inlet branch pipes 3. Accordingly, the air inlet main pipe 5 is divided into three air inlet main section along the length direction. , respectively, they are the air inlet main section 1 5-1 corresponding to the air inlet branch pipe 1 3-1, the air inlet main section 2 5-2 corresponding to the air inlet branch pipe 2 3-2, and the air inlet main section 3 5-3 corresponding to the air inlet branch pipe 3-3. The diameters of the air inlet main section 1 5-1, the air inlet main section 2 5-2, and the air inlet main section 3 5-3 gradually decrease. The air inlet branch pipe 1 3-1, the air inlet branch pipe 2 3-2, and the air inlet branch pipe 3 3-3 are located at the rear ends of the air inlet main section 1 5-1, the air inlet main section 2 5-2, and the air inlet main section 3 5-3, respectively.

[0020] like Figure 1 As shown, to facilitate the recycling of flue gas, the return air hood 6 is connected to the air inlet of the circulation fan 8 through the return air duct 7. The air outlet of the circulation fan 8 is respectively connected to the air inlet of the hot air system 4 and the external exhaust chimney 10. An exhaust regulating valve 9 is provided between the air outlet of the circulation fan 8 and the external exhaust chimney 10.

[0021] When the downstream multi-stage heating acidification roasting kiln system is working, the high-temperature flue gas generated by the hot air system 4 passes through the air inlet main pipe 5 and then enters the flue gas guide partition 14 through each group of air inlet branch pipes 3 to heat the lifting plate. After the material enters the rotary kiln body 1 from the feed end 11, it is heated by heat exchange with the lifting plate. After reaching the reaction temperature and reaction time, it is discharged from the discharge end. Since the flue gas in the area near the air inlet branch pipe 3 in the flue gas guide partition 14 always maintains a higher temperature, the material temperature increases faster and the high-temperature reaction time is longer under the same conditions. The flue gas after heat exchange returns to the hot air system for heating again through the return air hood 6 and the circulating fan 8. During the circulation process, the hot air system needs to discharge a portion of the flue gas to maintain the pressure balance of the system. The amount of exhaust flue gas is controlled by the exhaust regulating valve 9 and discharged from the system through the exhaust chimney 10.

[0022] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. A downstream multi-stage heating acidification roasting kiln system, comprising a rotary kiln body and a hot air system, wherein the rotary kiln body is provided with a feed end and a discharge end, and is characterized in that: The inner wall of the rotary kiln body is provided with several groups of lifting plates along the circumferential direction, and a smoke guide barrier is formed between the lifting plates and the inner wall of the rotary kiln body. An air inlet pipe is provided in the center of the rotary kiln body along the axial direction. The front end of the air inlet pipe is located at the feeding end of the rotary kiln body and is connected to the smoke outlet of the hot air system. The rear end of the air inlet pipe is closed and located in the middle of the rotary kiln body. An air inlet branch pipe is provided between the lifting plates and the air inlet pipe. Several groups of air inlet branch pipes are arranged at intervals along the length direction of the air inlet pipe. Each group of air inlet branch pipes is evenly distributed along the circumference of the air inlet pipe. The air inlet pipe is connected to the smoke guide barrier through the air inlet branch pipe. A return air hood is provided at the discharge end of the rotary kiln body, and the return air hood is connected to the smoke guide barrier.

2. The downstream multi-stage heating acidification roasting kiln system according to claim 1, characterized in that: The air inlet main pipe is divided into a plurality of air inlet main pipe sections along the length direction, each air inlet main pipe section corresponds to a group of air inlet branch pipes, and the diameter of each air inlet main pipe section gradually decreases from front to back.

3. The downstream multi-stage heating acidification roasting kiln system according to claim 2, characterized in that: Each group of air inlet branch pipes is located at the rear end of the corresponding air inlet main pipe segment.

4. The downstream multi-stage heating acidification roasting kiln system according to claim 1, characterized in that: The return air hood is connected to the air inlet of the circulation fan through the return air duct, and the air outlet of the circulation fan is respectively connected to the air inlet of the hot air system and the external exhaust chimney.

5. The downstream multi-stage heating acidification roasting kiln system according to claim 4, characterized in that: An exhaust regulating valve is provided between the air outlet of the circulating fan and the external exhaust chimney.

6. The downstream multi-stage heating acidification roasting kiln system according to claim 1, characterized in that: A heat-insulating layer is provided on the outside of the rotary kiln body.

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