An alumina leaching device

Abstract

This utility model discloses an alumina leaching device, characterized in that: the raw ore slurry, after passing through a first heat exchanger, sequentially enters a second, third, fourth, and fifth heat exchanger, and then enters a heat-insulating retention tank. The heat-insulating retention tank is connected to a flash evaporator. The leached slurry from the flash evaporator is connected to a second heat exchanger, and then enters a dilution tank. The dilution tank is connected to a post-leaching tank via a first pump. This utility model, through optimized thermal energy design, reduces redundant flash evaporation and auxiliary processes in traditional processes, lowers equipment investment costs and operational complexity, and provides a device for optimizing the thermal energy utilization of the leaching system, while simultaneously achieving the goals of simplifying the leaching process and saving investment. Combining the leaching heat balance and the water distillation benefits from flash cooling, it ensures that the ore slurry achieves the best leaching effect and optimal economic benefits in the leaching system.

Description

Technical Field

[0001] This utility model relates to an alumina leaching device, belonging to the field of alumina production technology. Background Technology

[0002] my country's main aluminum ore resource is monohydrate gibbsite-type bauxite. For this type of aluminum ore, the primary technology used is "full-pipeline leaching technology," while other technologies such as "pipeline preheating-pressure cooker heating leaching technology," dual-flow leaching technology, and two-stage leaching technology are also being applied.

[0003] In traditional alumina leaching processes, different leaching temperature regimes are implemented based on the type of ore, and corresponding flash stages are set. The heat generated by the secondary flash steam is fully utilized to preheat the slurry, thereby achieving the recovery and utilization of leaching heat.

[0004] Specifically, the traditional leaching process is as follows: Desilication slurry at 90-98℃ first enters the leaching system, undergoes staged preheating with flash secondary steam, and finally is heated to the leaching temperature using fresh steam or molten salt. After heating, the slurry needs to be held at this temperature for a period of time before undergoing staged flash evaporation. Due to the boiling point rise of the leached slurry, the final flash evaporation outlet temperature is 110-120℃, corresponding to a low saturated steam pressure (below atmospheric pressure), requiring a vacuum system to maintain a negative pressure environment for flash evaporation. The flash-evaporated material enters a dilution tank, where the primary washing liquid and material are mixed to form a slurry of the appropriate concentration, which is then pumped to the next process for red mud slurry treatment. The secondary steam condensate generated after secondary steam heat exchange also needs to be flash-evaporated staged to utilize this heat. The secondary steam obtained from flash evaporation is incorporated into the pressure-matched flash stages and used to preheat the slurry. It is worth noting that the temperature of the condensate from the final flash secondary steam is usually above 100°C; however, this heat is difficult to reuse in the leaching system. The heat from the condensate generated after the fresh steam heats the slurry through the heat exchanger is also not fully utilized in the leaching system.

[0005] Chinese patent CN201110434055.X discloses an alumina leaching device and method capable of achieving both high and low temperature leaching, belonging to the field of alumina production technology. The multi-stage shell-and-tube preheater, insulated tank group, and multi-stage flash evaporator are all divided into a front group and a rear group. The material outlet of the front group shell-and-tube preheater is connected to the rear group insulated tank; the front group insulated tank is connected to the first flash evaporator of the rear group. The method is as follows: for high-temperature leaching, the entire device is used; for low-temperature leaching, the front group shell-and-tube preheater, the rear group insulated tank, and the front group flash evaporator are used as the first leaching device, and the rear group shell-and-tube preheater, the front group insulated tank, and the rear group flash evaporator are used as the second leaching device; the two devices are used for low-temperature leaching respectively. The device and method of this invention can change the leaching process according to the changes in ore, realizing the conversion from a high-temperature leaching process to a low-temperature leaching process. This method merely describes an alumina leaching device and method capable of switching between high and low temperature leaching modes, but it does not optimize the utilization of heat energy during the leaching process. Its technical focus is limited to the switching function between high and low leaching temperatures. It does not address the coordinated control of the leaching system's thermal balance, nor does it utilize byproducts of the flash evaporation process (such as secondary steam condensate) for heat energy recovery, resulting in high energy consumption and a lengthy and complex process flow. There is no innovative optimization of the utilization of leaching heat energy. It still involves staged flash evaporation until it can no longer be performed. Because the leaching slurry exhibits a boiling point elevation, the final flash evaporation outlet temperature is between 110 and 120°C, corresponding to a low saturated steam pressure (below atmospheric pressure), necessitating a vacuum system to maintain a negative pressure environment for flash evaporation. Summary of the Invention

[0006] The problem this invention aims to solve is to provide an alumina leaching device that optimizes the alumina leaching process from the perspective of a dynamic cost-benefit model, reduces the production cost of alumina, and contributes to the efficient utilization of resources and sustainable development.

[0007] The technical solution of this utility model is as follows: An alumina leaching device, in which the raw ore slurry enters the second, third, fourth and fifth heat exchangers in sequence after passing through the first heat exchanger, and then enters the heat preservation and retention tank. The heat preservation and retention tank is connected to the flash evaporator. The leached slurry from the flash evaporator is connected to the second heat exchanger and then enters the dilution tank. The dilution tank is connected to the post-leaching tank through the first pump.

[0008] New steam enters the fifth heat exchanger, and the condensate from the new steam generated after heat exchange enters the fourth heat exchanger and the first heat exchanger in sequence. The condensate from the new steam coming out of the first heat exchanger enters the first condensate. The secondary steam generated by the flash evaporator is connected to the third heat exchanger, and the condensate from the secondary steam generated by the third heat exchanger is connected to the first heat exchanger. The condensate from the secondary steam coming out of the first heat exchanger enters the second condensate.

[0009] There are two first heat exchangers, which are respectively connected to the first condenser and the second condenser.

[0010] The first condenser is connected to the third pump.

[0011] The second condenser is connected to the fourth pump.

[0012] The flash evaporator uses 4-8 stages of flash evaporation.

[0013] When the ore contains 80% or more monohydrate diatomite, the flash evaporator uses 4-5 stages of flash evaporation.

[0014] The secondary steam from the dilution tank is connected to a water cooler, which is connected to an expansion tank, which is connected to a fifth pump.

[0015] This invention optimizes the heat exchange system. The flash evaporation system retains the heat exchange mode where secondary steam heat transfer intensity is dominant, allowing the heat exchange equipment area to be controlled within a small range. Simultaneously, a certain amount of steam is retained to ensure smooth addition of subsequent red mud washing water, reducing red mud alkali loss. The leaching slurry, initially at 260-280℃, is cooled to 150-160℃ through 4-8 stages of flash evaporation, and then replaced with a non-phase-change liquid-liquid staged heat exchange method. This eliminates the need for flash evaporators, condensate flash evaporation systems, and vacuum systems required for further flash evaporation from 150-160℃, as well as the related piping and accessories connecting these devices and systems, reducing equipment power consumption and corresponding investment and maintenance costs. In the liquid-liquid staged heat exchange method, the hot-side slurry precipitates slowly under a relatively gentle temperature drop, resulting in a relatively slow scaling rate. As long as the flow rate is controlled to avoid low-velocity regions (<0.5m / s), slurry deposition is not easily achieved. Simultaneously, the slurry flow rate exerts shear force. When the flow rate is ≥1.2m / s, the rate of scarring slows down relatively.

[0016] Instead of flash evaporating the leaching slurry to 150-160℃, a liquid-liquid phase-change-free stepwise heat exchange method is used, which simplifies the leaching process and saves investment. Combining the leaching heat balance and the water distillation benefits from flash cooling, the slurry achieves optimal leaching effect and the best economic benefits in the leaching system.

[0017] Taking the design of a 1 million-ton-scale leaching process for a certain project as an example, compared with the traditional alumina leaching process, the comprehensive benefits of this utility model are as follows:

[0018] Reduce the number of equipment: 3 flash evaporators, 3 secondary steam condensate tanks, 1 low-temperature water cooler, 2 low-temperature return water pumps and 1 vacuum pump.

[0019] Reduce related pipes, fittings (valves), pipe supports, etc. by approximately 10-15%;

[0020] Reduce factory floor space by approximately 5-8%;

[0021] Reduce heat loss during the process;

[0022] Reduce energy waste. The liquid-liquid staged heat exchange method, with its counter-current stepped temperature drop design, can reduce the waste of effective energy (energy) and achieve the same efficiency as the full flash evaporation staged heat recovery.

[0023] The process is simplified. By eliminating the final flash evaporation stages and vacuum system, the process flow is simplified and the operational complexity is reduced.

[0024] Liquid-liquid staged heat exchange eliminates the need for frequent adjustments to the vacuum pressure system, improving operational flexibility. However, the vacuum system is sensitive, and negative pressure environments are susceptible to leaks, requiring high-precision monitoring and frequent maintenance.

[0025] By quantifying the total life-cycle cost (including investment, energy consumption, maintenance, environmental protection, etc.) through a dynamic cost-benefit model and selecting the optimal dissolution temperature parameter range in combination with specific process parameters, this utility model is an innovative process route with high cost performance.

[0026] This invention, through optimized thermal energy design, reduces redundant flash evaporation and auxiliary processes in traditional technologies, thereby lowering equipment investment costs and operational complexity. It provides a method for optimizing the thermal energy utilization of the leaching system, while simultaneously simplifying the leaching process and saving investment. By combining leaching heat balance with the water distillation benefits from flash cooling, it ensures that the slurry achieves optimal leaching performance and the best economic benefits in the leaching system. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of the structure of this utility model.

[0028] Reference numerals in the attached drawings: 1-First heat exchanger, 2-Second heat exchanger, 3-Third heat exchanger, 4-Fourth heat exchanger, 5-Fifth heat exchanger, 6-Insulation and retention tank, 7-Flash evaporator, 8-Dilution tank, 9-First pump, 10-Post-dissolution tank, 11-Second pump, 12-First condenser, 13-Third pump, 14-Second condenser, 15-Fourth pump, 16-Water cooler, 17-Expansion tank, 18-Fifth pump. Detailed Implementation

[0029] The present invention will now be described in detail with reference to the accompanying drawings. Example

[0030] An alumina leaching device is provided in which the raw ore slurry passes through a first heat exchanger 1, then sequentially enters a second heat exchanger 2, a third heat exchanger 3, a fourth heat exchanger 4, and a fifth heat exchanger 5, and then enters a heat preservation and retention tank 6. The heat preservation and retention tank 6 is connected to a flash evaporator 7. The leached slurry from the flash evaporator 7 is connected to the second heat exchanger 2, and then enters a dilution tank 8. The dilution tank 8 is connected to a post-leaching tank 10 via a first pump 9.

[0031] The leached slurry can be further desiliconized in the post-leaching tank 10. The post-leaching tank 10 is connected to the second pump 11, and the slurry after deep desiliconization is transported to the next process - red mud slurry treatment via the second pump 11.

[0032] New steam enters the fifth heat exchanger 5, and the condensate from the new steam generated after heat exchange enters the fourth heat exchanger 4 and the first heat exchanger 1 in sequence. The condensate from the new steam coming out of the first heat exchanger 1 enters the first condensate 12. The secondary steam generated by the flash evaporator 7 is connected to the third heat exchanger 3, and the condensate from the secondary steam generated by the third heat exchanger 3 is connected to the first heat exchanger 1. The condensate from the secondary steam coming out of the first heat exchanger 1 enters the second condensate 14.

[0033] There are two first heat exchangers 1, and the two first heat exchangers 1 are respectively connected to the first condenser 12 and the second condenser 14. Figure 1 The upper heat exchanger 1 in the diagram uses the condensate from the flash secondary steam as the heat medium to provide heat, while the lower heat exchanger 1 uses the condensate from the fresh steam as the heat medium to provide heat.

[0034] The first condenser 12 is connected to the third pump 13. The second condenser 14 is connected to the fourth pump 15. The secondary steam condensate and the fresh steam condensate are delivered to the required processes, such as hot water tanks or red mud slurry treatment processes.

[0035] Flash evaporator 7 uses 4-8 stages of flash evaporation.

[0036] When the ore contains 80% or more monohydrate diatomite, the flash evaporator 7 uses 4-5 stages of flash evaporation.

[0037] The secondary steam from the dilution tank 8 is connected to the water cooler 16, the water cooler 16 is connected to the expansion tank 17, and the expansion tank 17 is connected to the fifth pump 18, which delivers the hot water from the expansion tank 17 to the required process.

[0038] A leaching method using an alumina leaching device includes the following steps:

[0039] 1. Raw ore slurry preheating: The raw ore slurry with an initial temperature of 75-85℃ is transported to the first heat exchanger 1 of the leaching system, and exchanged with the secondary steam condensate of the leaching system and the fresh steam condensate with a temperature of 160-180℃ in sequence, so that the raw ore slurry is heated to 90-98℃ and then enters the pre-desiliconization process.

[0040] 2. Multi-stage heating of desilication slurry:

[0041] a. Initial heating: The slurry with a temperature of 90-98℃ after desilication is transported to the second heat exchanger 2, where it undergoes liquid-liquid heat exchange without phase change with the leaching slurry that has been cooled to 150-160℃ by 4-8 stages of flash evaporation, and the temperature is raised to 120-130℃.

[0042] b. Secondary heating: Utilize the secondary steam generated when the slurry is flashed from 260-280℃ to 150-160℃, and use the third heat exchanger 3 to heat the slurry through a vapor-liquid phase change to raise the temperature to 210-220℃.

[0043] c. Three heating steps: Fresh steam at 290℃ is used to heat the slurry through the fourth heat exchanger 4, further raising the temperature to 225-235℃;

[0044] d. Heating at dissolution temperature: The slurry is heated to 260-280°C using fresh steam at 290°C through the fifth heat exchanger 5;

[0045] 3. Heat preservation and residence leaching: The slurry with a leaching temperature of 260-280℃ is kept in the heat preservation residence device 6 for 30-90 minutes for heat preservation and residence leaching;

[0046] 4. Treatment of leaching slurry:

[0047] a. Cool the leaching slurry at 260-280℃ to 150-160℃ using 4-8 stages of flash evaporation;

[0048] b. The leaching slurry at 150-160℃ is returned to the second heat exchanger 2 to exchange heat with the desiliconized slurry. After cooling to 113-119℃, it enters the dilution tank 8 and is then transported to the leaching tank 10 by the first pump 9 for further deep desiliconization. After that, it is transported to the next process by the second pump 11.

[0049] 5. Condensate recovery:

[0050] a. The secondary steam generated by flash evaporation in step 4.a is transported to the third heat exchanger 3. After the secondary steam completes the heat exchange, it is condensed to produce secondary steam condensate, which is returned to the first heat exchanger 1 to exchange heat with the raw ore slurry that has just entered the system. The secondary steam condensate, which has been cooled to 95-105℃ by heat exchange, is transported to the red mud slurry treatment process by the fourth pump 15.

[0051] b. The fresh steam condensate, cooled to 160-180℃ after one heat exchange in step 2.c, is returned to the first heat exchanger 1 as a heat source for further heat exchange. The raw ore slurry, which was heated in step 5.a, is further heated to a temperature of 92-98℃ before proceeding to the pre-desiliconization process for desiliconization. The fresh steam condensate, cooled after heat exchange, is then pumped by the third pump 13 to the process that requires this portion of fresh steam condensate.

[0052] 6. Secondary steam recovery in dilution tank: The slurry after dissolution at a temperature of 113-119℃ in step 4.b is directly fed into dilution tank 8. The secondary steam generated by the slurry in dilution tank 8 enters water cooler 16 and then directly enters expansion tank 17. It is then transported to the process that requires this part of hot water by the fifth pump 18. Example

[0053] An alumina leaching device comprises a raw ore slurry that passes through a first heat exchanger 1, then sequentially enters a second heat exchanger 2, a third heat exchanger 3, a fourth heat exchanger 4, and a fifth heat exchanger 5, before entering a heat-insulating retention tank 6. The heat-insulating retention tank 6 is connected to a flash evaporator 7. The leached slurry exiting the flash evaporator 7 is connected to the second heat exchanger 2, and then enters a dilution tank 8. The dilution tank 8 is connected to a post-leaching tank 10 via a first pump 9. Fresh steam enters the fifth heat exchanger 5, and the condensate from this fresh steam sequentially enters the fourth heat exchanger 4 and the first heat exchanger 1. The condensate from the fresh steam exiting the first heat exchanger 1 enters a first condensate tank 12. Secondary steam generated by the flash evaporator 7 is connected to the third heat exchanger 3, and the condensate from the secondary steam generated by the third heat exchanger 3 is connected to the first heat exchanger 1. The condensate from the secondary steam exiting the first heat exchanger 1 enters a second condensate tank 14.

[0054] Flash evaporator 7 uses 7-8 stages of flash evaporation. Example

[0055] An alumina leaching device is provided in which the raw ore slurry passes through a first heat exchanger 1, then sequentially enters a second heat exchanger 2, a third heat exchanger 3, a fourth heat exchanger 4, and a fifth heat exchanger 5, and then enters a heat preservation and retention tank 6. The heat preservation and retention tank 6 is connected to a flash evaporator 7. The leached slurry from the flash evaporator 7 is connected to the second heat exchanger 2, and then enters a dilution tank 8. The dilution tank 8 is connected to a post-leaching tank 10 via a first pump 9.

[0056] New steam enters the fifth heat exchanger 5, and the condensate from the new steam generated after heat exchange enters the fourth heat exchanger 4 and the first heat exchanger 1 in sequence. The condensate from the new steam coming out of the first heat exchanger 1 enters the first condensate 12. The secondary steam generated by the flash evaporator 7 is connected to the third heat exchanger 3, and the condensate from the secondary steam generated by the third heat exchanger 3 is connected to the first heat exchanger 1. The condensate from the secondary steam coming out of the first heat exchanger 1 enters the second condensate 14.

[0057] There are two first heat exchangers 1, and the two first heat exchangers 1 are respectively connected to the first condenser 12 and the second condenser 14. Figure 1 The upper heat exchanger 1 in the diagram uses the condensate from the flash secondary steam as the heat medium to provide heat, while the lower heat exchanger 1 uses the condensate from the fresh steam as the heat medium to provide heat.

[0058] The first condenser 12 is connected to the third pump 13. The second condenser 14 is connected to the fourth pump 15. The secondary steam condensate and the fresh steam condensate are delivered to the required processes, such as hot water tanks or red mud slurry treatment processes.

[0059] Flash evaporator 7 uses 4-8 stages of flash evaporation.

[0060] The leaching method used includes the following steps:

[0061] 1. Raw ore slurry preheating: The raw ore slurry with an initial temperature of 80℃ is transported to the first heat exchanger 1 of the leaching system, and exchanged with the secondary steam condensate and the fresh steam condensate with a temperature of 170℃ in sequence, so that the raw ore slurry is heated to 95℃ and then enters the pre-desiliconization process.

[0062] 2. Multi-stage heating of desilication slurry:

[0063] a. Initial heating: The slurry with a temperature of 95°C after desilication is transported to the second heat exchanger 2, where it undergoes liquid-liquid phase-change-free heat exchange with the leaching slurry that has been cooled to 155°C by 8-stage flash evaporation, and the temperature is raised to 125°C.

[0064] b. Secondary heating: The secondary steam generated when the 275℃ leaching slurry flashes to 155℃ is used to heat the slurry through the third heat exchanger 3 via a vapor-liquid phase change, raising the temperature to 215℃.

[0065] c. Three heating steps: Fresh steam at 290℃ is used to condense the slurry through the fourth heat exchanger 4, further heating it to 230℃;

[0066] d. Heating at dissolution temperature: The slurry is heated to 275°C using fresh steam at 290°C through the fifth heat exchanger 5;

[0067] 3. Heat preservation and residence leaching: The slurry with a leaching temperature of 275℃ is kept in the heat preservation residence device 6 for 60 minutes for heat preservation and residence leaching.

[0068] 4. Treatment of leaching slurry:

[0069] a. Cool the leaching slurry at 275℃ to 155℃ using an 8-stage flash evaporation process;

[0070] b. The 155°C leaching slurry is returned to the second heat exchanger 2 to exchange heat with the desiliconized slurry. After cooling to 118°C, it enters the dilution tank 8 and is then transported to the leaching tank 10 by the first pump 9 for further deep desiliconization. After that, it is transported to the next process by the second pump 11.

[0071] 5. Condensate recovery:

[0072] a. The secondary steam generated by flash evaporation in step 4.a is transported to the third heat exchanger 3. After the secondary steam completes the heat exchange, it is condensed to produce secondary steam condensate, which is returned to the first heat exchanger 1 to exchange heat with the raw ore slurry that has just entered the system. The secondary steam condensate, which has been cooled to 100°C by heat exchange, is transported to the red mud slurry treatment process by pump 15.

[0073] b. The fresh steam condensate cooled to 170°C after one heat exchange in step 2.c is returned to the first heat exchanger 1 as a heat source to continue heat exchange. The raw ore slurry that was heat exchanged in step 5.a is further heat-exchanged and heated up until the raw ore slurry reaches 95°C and then goes to the pre-desiliconization process for desiliconization. The fresh steam condensate cooled after heat exchange is transported to the process that needs this part of the fresh steam condensate by the third pump 13.

[0074] 6. Secondary steam recovery in dilution tank: The slurry after dissolution at 118°C in step 4.b is directly fed into dilution tank 8. The secondary steam generated by the slurry in dilution tank 8 enters water cooler 16 and then directly enters expansion tank 17. It is then transported to the process that requires this part of hot water by the fifth pump 18.

[0075] In step 2, the slurry flow rate in the liquid-liquid non-phase change heat exchange is ≥1.2m / s, and the scaling rate is relatively slowed down.

[0076] Alumina ores are generally classified into boehmite, diaspore, and gibbsite. This invention mainly targets bauxite ore containing boehmite and diaspore. The proportion of diaspore affects the process primarily in terms of economy and equipment requirements. A higher proportion diaspore necessitates and enhances the economic viability of high-temperature leaching. Domestically, diaspore-type bauxite is predominant; therefore, the leaching temperature is controlled at 265-275℃, and the final temperature of multi-stage heating is also at the leaching temperature of 265-275℃. However, the leaching temperature of boehmite is lower than that of diaspore. To further reduce energy consumption, when the boehmite content in the ore is greater than or equal to 80%, the leaching temperature of the slurry is reduced to 200-240℃. In step 4.a, the temperature is flashed from the leaching temperature to 150-160℃, employing 4-5 stages of flash evaporation.

[0077] When the ore is mainly composed of gibbsite monohydrate, the slurry in step 4.a is flashed from a leaching temperature of 260-280℃ to 150-160℃, using 7-8 stages of flashing, which is a more reasonable design. Example

[0078] A leaching system used in an alumina leaching apparatus comprises a raw ore slurry that, after passing through a first heat exchanger 1, sequentially enters a second heat exchanger 2, a third heat exchanger 3, a fourth heat exchanger 4, and a fifth heat exchanger 5, then enters a heat-insulating retention tank 6. The heat-insulating retention tank 6 is connected to a flash evaporator 7. The leached slurry exiting the flash evaporator 7 is connected to the second heat exchanger 2, and then enters a dilution tank 8. The dilution tank 8 is connected to a post-leaching tank 10 via a first pump 9. Fresh steam enters the fifth heat exchanger 5, and the condensate from the fresh steam generated after heat exchange sequentially enters the fourth heat exchanger 4 and the first heat exchanger 1. The condensate from the fresh steam exiting the first heat exchanger 1 enters a first condensate tank 12. The secondary steam generated by the flash evaporator 7 is connected to the third heat exchanger 3, and the condensate from the secondary steam generated by the third heat exchanger 3 is connected to the first heat exchanger 1. The condensate from the secondary steam exiting the first heat exchanger 1 enters a second condensate tank 14.

[0079] The leached slurry can be further desilicated in the post-leaching tank 10. After that, it is transported to the next process - red mud slurry treatment by the second pump 11.

[0080] As shown in the figure, there are two heat exchangers 1. The upper heat exchanger 1 uses the condensate from the flash-generated secondary steam as the heat medium to provide heat, while the lower heat exchanger 1 uses the condensate from the fresh steam as the heat medium to provide heat. The two heat exchangers 1 are connected to the first condensate 12 and the second condensate 14, respectively.

[0081] The first condenser 12 and the second condenser 14 respectively transport the secondary steam condensate and the fresh steam condensate to the required processes, such as the hot water tank or the red mud slurry treatment process, through the third pump 13 and the fourth pump 15.

[0082] The secondary steam from the dilution tank 8 is connected to the water cooler 16, which is connected to the expansion tank 17. The expansion tank 17 then delivers hot water to the required process via the fifth pump 18.

[0083] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this utility model, and not to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. An alumina leaching device, characterized in that: After passing through the first heat exchanger (1), the raw ore slurry enters the second heat exchanger (2), the third heat exchanger (3), the fourth heat exchanger (4) and the fifth heat exchanger (5) in sequence, and then enters the heat preservation holder (6). The heat preservation holder (6) is connected to the flash evaporator (7). The leached slurry from the flash evaporator (7) is connected to the second heat exchanger (2) and then enters the dilution tank (8). The dilution tank (8) is connected to the post-leaching tank (10) through the first pump (9).

2. The alumina leaching device according to claim 1, characterized in that: New steam enters the fifth heat exchanger (5), and the new steam condensate generated after heat exchange enters the fourth heat exchanger (4) and the first heat exchanger (1) in sequence. The new steam condensate from the first heat exchanger (1) enters the first condenser (12). The secondary steam generated by the flash evaporator (7) is connected to the third heat exchanger (3), and the secondary steam condensate generated by the third heat exchanger (3) is connected to the first heat exchanger (1). The secondary steam condensate from the first heat exchanger (1) enters the second condenser (14).

3. The alumina leaching device according to claim 1, characterized in that: There are two first heat exchangers (1), and the two first heat exchangers (1) are respectively connected to the first condenser (12) and the second condenser (14).

4. The alumina leaching device according to claim 3, characterized in that: The first condenser (12) is connected to the third pump (13).

5. The alumina leaching device according to claim 3, characterized in that: The second condenser (14) is connected to the fourth pump (15).

6. The alumina leaching device according to claim 1, characterized in that: The flash evaporator (7) adopts 4-8 stage flash evaporation.

7. The alumina leaching device according to claim 1, characterized in that: When the ore contains more than or equal to 80% monohydrate diatomite, the flash evaporator (7) adopts a 4-5 stage flash evaporation.

8. The alumina leaching device according to claim 1, characterized in that: The secondary steam of the dilution tank (8) is connected to the water cooler (16), the water cooler (16) is connected to the expansion tank (17), and the expansion tank (17) is connected to the fifth pump (18).

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