An oxygen pressure leaching method and equipment

Abstract

This invention discloses an oxygen pressure leaching method and apparatus. The oxygen pressure leaching method includes at least one stage of oxygen pressure leaching process. This stage includes grinding underflow pretreatment, a first-stage oxygen pressure leaching treatment, a first-stage slurry heat exchange and depressurization, a first-stage slurry gas separation, and a first-stage slurry separation to obtain a first-stage concentrated supernatant and a first-stage concentrated underflow. Compared to existing processes, the method of this invention can effectively reduce oxygen and steam consumption. Using a single-stage oxygen pressure leaching process can reduce steam consumption by 70-100%, and using a two-stage oxygen pressure leaching process can reduce oxygen consumption by 27.5-36% and steam consumption by 58-100%.

Description

Technical Field

[0001] This invention relates to the field of heavy metal ore processing technology, and in particular to an oxygen pressure leaching method and equipment. Background Technology

[0002] Green metallurgy refers to maximizing resource and energy utilization efficiency and environmental benefits in the metallurgical process of complex materials. It is a metal smelting mode that comprehensively considers resource and energy consumption and environmental impact. It aims to minimize energy consumption, maximize resource utilization efficiency, and minimize negative environmental impact throughout the entire life cycle of metal products, while promoting the coordinated optimization and harmonious development of enterprise economic benefits, environmental benefits, and social benefits.

[0003] Since the industrialization of pressure leaching technology for zinc concentrate in the 1980s, true hydrometallurgical zinc refining has been achieved. As a crucial step in hydrometallurgical zinc production, the leaching process directly determines the main technical and economic indicators of zinc smelting. Pressure leaching technology boasts lower total investment, less environmental pollution, recovery of sulfur in elemental form, high zinc recovery rate, and strong adaptability to mineral raw materials—advantages unmatched by traditional processes. Its reaction process is as follows:

[0004] ZnS + H₂SO₄ = ZnSO₄ + H₂S + Q

[0005] H₂S + 0.5O₂ = S 0 +H2O+Q

[0006] However, the current oxygen pressure acid leaching process for zinc concentrate has some shortcomings:

[0007] 1. The large amount of water vapor and oxygen emitted into the atmosphere through the exhaust gas separator causes not only a waste of resources but also problems such as the formation of white smoke in winter, freezing of nearby ground, and a poor working environment.

[0008] 2. High steam and oxygen consumption per ton of ore. Summary of the Invention

[0009] The purpose of this invention is to address the problem of high oxygen and steam consumption in existing technologies by providing an oxygen pressure acid leaching method.

[0010] Another object of the present invention is to provide an apparatus based on the oxygen pressure leaching process.

[0011] The technical solution adopted to achieve the purpose of this invention is:

[0012] An oxygen pressure leaching method includes at least one oxygen pressure leaching process, wherein the first oxygen pressure leaching process includes grinding underflow pretreatment, first oxygen pressure leaching treatment, first slurry heat exchange and depressurization, first slurry gas separation, and first slurry separation to obtain a thick supernatant and a thick underflow.

[0013] In the above technical solution, the grinding underflow pretreatment includes contact countercurrent heat exchange, pressurization and primary preheating and secondary preheating.

[0014] In the above technical solution, the oxygen pressure leaching method further includes a two-stage oxygen pressure leaching process, which includes acid pretreatment, mixing and heat exchange of a first-stage thick underflow with acid, second-stage oxygen pressure leaching treatment, second-stage slurry heat exchange and depressurization, second-stage slurry gas separation, and second-stage slurry separation to obtain second-stage supernatant and second-stage underflow.

[0015] In the above technical solution, the two-stage supernatant and the grinding underflow are subjected to a single-stage oxygen pressure leaching treatment.

[0016] In the above technical solution, the exhaust gas from the two-stage oxygen pressure leaching process is applied to the first-stage oxygen pressure leaching process.

[0017] In the above technical solution, the first slurry obtained by the first oxygen pressure leaching treatment undergoes inter-wall heat exchange with the grinding underflow, and the second slurry obtained by the second oxygen pressure leaching treatment undergoes inter-wall heat exchange with the first thickened underflow.

[0018] In the above technical solution, the grinding underflow exchanges heat with the exhaust gas from the first stage of oxygen pressure leaching, and the acid solution exchanges heat with the exhaust gas from the second stage of oxygen pressure leaching.

[0019] In another aspect, the present invention provides an apparatus for use in the oxygen pressure leaching method, comprising at least a stage of reactor exhaust condenser, a stage of oxygen pressure reactor, a stage of primary preheater, a stage of secondary preheater, a stage of gas separator, and a stage of thickening tank;

[0020] Along the material flow direction, the raw material feed pipe is connected to the raw material inlet of the first-stage reactor exhaust condenser, the material outlet of the first-stage reactor exhaust condenser is connected to the material inlet of the first-stage primary preheater, the material outlet of the first-stage primary preheater is connected to the material inlet of the first-stage secondary preheater, the material outlet of the first-stage secondary preheater is connected to the material inlet of the first-stage oxygen pressure vessel, and the exhaust port of the first-stage oxygen pressure vessel is connected to the exhaust inlet of the first-stage reactor exhaust condenser. The material outlet of the first-stage oxygen pressure vessel, the material inlet of the first-stage secondary preheater, the material outlet of the first-stage secondary preheater, the first-stage gas separator, and the first-stage thickener are connected in sequence.

[0021] In the above technical solution, the equipment also includes a two-stage exhaust condenser, a two-stage oxygen pressure vessel, a two-stage primary preheater, a two-stage secondary preheater, a two-stage gas distributor, and a two-stage thickening tank.

[0022] The acid feed pipe is connected to the acid inlet of the second-stage reactor exhaust condenser. The acid outlet of the second-stage reactor exhaust condenser is connected to the raw material inlet of the second-stage primary preheater. The material outlet of the second-stage primary preheater is connected to the material inlet of the second-stage secondary preheater. The concentrated liquid outlet of the first-stage thickener is connected to the material inlet of the second-stage secondary preheater. The material outlet of the second-stage secondary preheater is connected to the material inlet of the second-stage oxygen pressure vessel. The exhaust port of the second-stage oxygen pressure vessel is connected to the exhaust inlet of the second-stage reactor exhaust condenser. The material outlet of the second-stage oxygen pressure vessel, the material inlet of the second-stage secondary preheater, the material outlet of the second-stage secondary preheater, the second-stage gas separator, and the second-stage thickener are connected in sequence.

[0023] In the above technical solution, the exhaust port of the two-stage reactor exhaust condenser is connected to the air inlet of the first-stage oxygen pressure vessel or to any compartment of the first-stage oxygen pressure vessel.

[0024] Compared with the prior art, the beneficial effects of the present invention are:

[0025] 1. The main feed of the first-stage oxygen autoclave and the main feed of the second-stage oxygen autoclave exchange heat with the slurry discharged from this autoclave through the wall to recover the heat of the discharged slurry and effectively reduce the temperature of the discharged slurry to below 100℃.

[0026] 2. The exhaust gas from the second-stage oxygen pressure vessel is introduced into the first-stage oxygen pressure vessel, thereby recovering and utilizing the steam and oxygen contained therein.

[0027] 3. The grinding underflow directly contacts the exhaust gas from the first-stage oxygen autoclave for heat exchange, effectively reducing the exhaust gas temperature of the first-stage oxygen autoclave.

[0028] 4. The waste electrolyte directly contacts the exhaust gas from the second-stage oxygen autoclave for heat exchange, effectively reducing the moisture content of the exhaust gas from the second-stage oxygen autoclave.

[0029] 5. Make full use of the heat generated by the leaching reaction itself to raise the temperature of the system.

[0030] 6. Compared with existing processes, the method of the present invention can effectively reduce the consumption of oxygen and steam. When using a single-stage oxygen pressure leaching process, the steam consumption can be reduced by 70% to 100%. When using a two-stage oxygen pressure leaching process, the oxygen consumption can be reduced by 27.5-36% and the steam consumption by 58% to 100%. Attached Figure Description

[0031] Figure 1 The diagram shown is a process flow chart of the oxygen pressure leaching method of the present invention.

[0032] Figure 2 The diagram shown is an equipment diagram of a single oxygen pressure leaching process according to the present invention.

[0033] Figure 3The diagram shown is of the equipment for the two-stage oxygen pressure leaching process of the present invention.

[0034] Figure 4 The diagram shows the equipment for an existing oxygen pressure leaching process.

[0035] In the diagram: 1-First stage exhaust condenser, 2-First stage oxygen pressure vessel, 3-First stage primary preheater, 4-First stage secondary preheater, 5-First stage gas distributor, 6-First stage thickener, 7-Second stage exhaust condenser, 8-Second stage oxygen pressure vessel, 9-Second stage primary preheater, 10-Second stage secondary preheater, 11-Second stage gas distributor. Detailed Implementation

[0036] The present invention will be further described in detail below with reference to specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

[0037] Example 1

[0038] An oxygen pressure leaching method is disclosed, applicable to the extraction of heavy metals such as zinc, copper, and nickel / cobalt metallurgy. The method includes one to four stages of oxygen pressure leaching; this embodiment employs a two-stage oxygen pressure leaching process (including a single-stage and a two-stage process). Figure 1 As shown, the oxygen pressure leaching process includes grinding underflow pretreatment, a first-stage oxygen pressure leaching treatment, a first-stage slurry heat exchange and depressurization, a first-stage slurry gas separation, and a first-stage slurry separation to obtain a first-stage concentrated supernatant and a first-stage concentrated underflow. Specifically, the grinding underflow pretreatment includes contact countercurrent heat exchange, pressurization, and primary and secondary preheating.

[0039] The two-stage oxygen pressure leaching includes acid pretreatment, mixing and heat exchange of the first-stage thickened underflow with the acid, second-stage oxygen pressure leaching treatment, second-stage slurry heat exchange and depressurization, second-stage slurry gas separation, and second-stage slurry separation to obtain second-stage supernatant and second-stage underflow. The second-stage supernatant and the grinding underflow are subjected to a first-stage oxygen pressure leaching treatment together.

[0040] To reduce oxygen consumption in the oxygen pressure leaching process, the exhaust gas from the second-stage oxygen pressure leaching treatment is applied to the first-stage oxygen pressure leaching treatment.

[0041] To reduce heat consumption in the oxygen pressure leaching process, the first-stage slurry obtained from the first-stage oxygen pressure leaching process undergoes inter-wall heat exchange with the grinding underflow, and the second-stage slurry obtained from the second-stage oxygen pressure leaching process undergoes inter-wall heat exchange with the first-stage thickening underflow. The grinding underflow exchanges heat with the exhaust gas from the first-stage oxygen pressure leaching process, and the acid solution exchanges heat with the exhaust gas from the second-stage oxygen pressure leaching process.

[0042] When the oxygen pressure leaching method adopts a single-stage oxygen pressure leaching process, it can save 70% to 100% of process steam. When the two-stage oxygen pressure leaching process is adopted, it can save 58% to 100% of process steam and 27.5% to 35% of process oxygen.

[0043] Example 2

[0044] Based on Example 1, an apparatus for use in oxygen pressure leaching processes, such as... Figure 2 As shown, it includes a first-stage exhaust condenser 1, a first-stage oxygen pressure vessel 2, a first-stage preheater 3, a second-stage preheater 4, a first-stage gas distributor 5, and a first-stage thickener 6;

[0045] Along the material flow direction, the raw material feed pipe is connected to the raw material inlet of the first-stage reactor exhaust condenser 1, the material outlet of the first-stage reactor exhaust condenser 1 is connected to the material inlet of the first-stage preheater 3, the material outlet of the first-stage preheater 3 is connected to the material inlet of the first-stage secondary preheater 4, the material outlet of the first-stage secondary preheater 4 is connected to the material inlet of the first-stage oxygen pressure vessel 2, and the exhaust port of the first-stage oxygen pressure vessel 2 is connected to the exhaust inlet of the first-stage reactor exhaust condenser 1. The material outlet of the first-stage oxygen pressure vessel 2, the material inlet of the first-stage secondary preheater 4, the material outlet of the first-stage secondary preheater 4, the first-stage gas separator 5, and the first-stage thickening tank 6 are connected in sequence.

[0046] In operation, the grinding underflow first exchanges heat with the exhaust gas from the first-stage reactor exhaust condenser 1 and the first-stage oxygen pressure vessel 2. The first-stage reactor exhaust condenser 1 has a heat exchange section; the grinding underflow and the exhaust gas from the first-stage oxygen pressure vessel 2 enter the spaces above and below the heat exchange section of the first-stage reactor exhaust condenser 1, respectively, and undergo direct contact counter-current heat exchange within the heat exchange section. The non-condensable gases in the exhaust gas from the first-stage oxygen pressure vessel 2 are cooled to approximately 35°C and discharged from the top of the first-stage reactor exhaust condenser 1, venting at a high point locally. The grinding underflow is heated and also mixes with the condensate from the exhaust gas from the first-stage oxygen pressure vessel 2, falling into the bottom buffer of the first-stage reactor exhaust condenser 1. At this point, the temperature of the grinding underflow is approximately 43.3°C.

[0047] Then, the grinding underflow from the bottom of the column in the first-stage condenser 1 is first pressurized by the feed pump to approximately 0.9 MPa(G) to overcome flow resistance and meet the feed pressure requirements of the first-stage oxygen pressure vessel 2; then it enters the first-stage preheater 3, where heat exchange occurs between the indirect walls, utilizing the heat from the slurry discharged from the first-stage oxygen pressure vessel 2 to raise the temperature to approximately 85°C. It then enters the second-stage preheater 4, where heat exchange occurs between the indirect walls, raising the temperature to approximately 130°C; finally, it enters the first-stage oxygen pressure vessel 2, where it continues to be heated to 155°C using the heat of the leaching reaction.

[0048] At this time, the exhaust gas from the first-stage oxygen pressure vessel 2 goes to the first-stage vessel exhaust condenser 1. The slurry discharged from the first-stage oxygen pressure vessel 2 firstly passes sequentially through the first-stage secondary preheater 4 and the first-stage primary preheater 3 to recover the heat contained therein, with the temperature decreasing from approximately 155°C to 99.6°C and 90.6°C respectively; then it passes through a valve to reduce the pressure from approximately 0.9 MPa(G) to approximately 0.12 MPa(G).

[0049] After depressurization, the material enters the first-stage gas separator 5. Since the depressurization is performed below 100°C, only a small amount of dissolved non-condensable gases are released. These non-condensable gases are separated by the first-stage gas separator 5; they can be directly vented at a high point in place, or a small heat exchanger can be used to condense the moisture and cool the non-condensable gases before venting them at a high point in place. The slurry processed by the first-stage gas separator 5 is then transported to the first-stage thickening tank 6 by a first-stage slurry discharge pump.

[0050] The first thickening tank 6 separates the feed into supernatant and underflow by gravity settling; the first thickened supernatant is sent out of the boundary area to the downstream unit. The discharge temperature of the first thickened supernatant and the first thickened underflow is approximately 75°C.

[0051] In this embodiment, with a zinc ore feed rate of 20 t / h, the process steam usage during plant start-up is 11.9 t / h. In contrast, with the existing process, the same feed rate requires 42.6 t / h of process steam. This represents a 72% saving in process steam compared to the existing technology. Once the first-stage oxygen pressure vessel 2 is running stably, no further addition of fresh steam is needed, resulting in a 100% steam saving.

[0052] Example 3

[0053] Based on Example 2, such as Figure 3 As shown, the equipment also includes a two-stage autoclave exhaust condenser 7, a two-stage oxygen pressure vessel 8, a two-stage primary preheater 9, a two-stage secondary preheater 10, a two-stage gas distributor 11, and a two-stage thickening tank 12.

[0054] The acid feed pipe is connected to the acid inlet of the second-stage reactor exhaust condenser 7. The acid outlet of the second-stage reactor exhaust condenser 7 is connected to the raw material inlet of the second-stage primary preheater 9. The material outlet of the second-stage primary preheater 9 is connected to the material inlet of the second-stage secondary preheater 10. The concentrated liquid outlet of the first-stage thickener 6 is connected to the material inlet of the second-stage secondary preheater 10. The material outlet of the second-stage secondary preheater 10 is connected to the material inlet of the second-stage oxygen pressure vessel 8. The exhaust port of the second-stage oxygen pressure vessel 8 is connected to the exhaust inlet of the second-stage reactor exhaust condenser 7. The material outlet of the second-stage oxygen pressure vessel 8, the material inlet of the second-stage secondary preheater 10, the material outlet of the second-stage secondary preheater 10, the second-stage gas separator 11, and the second-stage thickener 12 are connected in sequence.

[0055] In operation, the acid solution (waste electrolyte is used in this embodiment) from the second-stage acid supply tank outside the boundary area is first pressurized to approximately 1.3 MPa (G) by a waste electrolyte booster pump, and then enters the second-stage reactor exhaust condenser 7 to exchange heat with the exhaust gas from the second-stage oxygen pressure reactor 8. The second-stage reactor exhaust condenser 7 is equipped with a heat exchange section; the waste electrolyte and the exhaust gas from the second-stage oxygen pressure reactor 8 enter the spaces above and below the heat exchange section of the second-stage reactor exhaust condenser 7, respectively, and undergo direct contact countercurrent heat exchange in the heat exchange section. The non-condensable gases in the exhaust gas from the second-stage oxygen pressure reactor 8 are cooled to approximately 35°C and discharged from the top of the second-stage reactor exhaust condenser 7, heading to the first-stage oxygen pressure acid leaching process and merging into the oxygen inlet pipe of that process. The waste electrolyte is heated and also mixed with the condensate from the exhaust gas of the second-stage oxygen pressure reactor 8, falling into the bottom buffer of the second-stage reactor exhaust condenser 7. At this time, the temperature of the waste electrolyte is approximately 30.5°C. At this time, the oxygen required for the first stage oxygen pressure leaching process includes process oxygen and exhaust gas from the second stage oxygen pressure vessel 8; the process oxygen is divided into several streams, which enter each reaction chamber of the first stage oxygen pressure vessel 2 respectively; the exhaust gas from the second stage oxygen pressure vessel 8 does not need to be split, and enters a reaction chamber of the first stage oxygen pressure vessel 2 as a whole.

[0056] The waste electrolyte from the bottom of the second-stage reactor exhaust condenser 7 is transported by a waste electrolyte section transfer pump; it first enters the second-stage primary preheater 9, where heat exchange occurs between the indirect walls, utilizing the heat from the slurry discharged from the second-stage oxygen pressure vessel 8 to raise its temperature to approximately 70°C; then it merges with the first-stage thickened underflow at 75°C, forming a confluent liquid at approximately 71.5°C. The confluent liquid enters the second-stage secondary preheater 10, where heat exchange occurs between the indirect walls, again utilizing the heat from the slurry discharged from the second-stage oxygen pressure vessel 8 to raise its temperature to approximately 130°C; then it enters the second-stage oxygen pressure vessel 8, where it is raised to 165°C by its own leaching reaction heat.

[0057] With the waste electrolyte and a first-stage concentrated underflow preheated to 130°C, the second-stage oxygen pressure vessel 8 no longer requires heating steam during normal operation. The oxygen required for the second-stage oxygen pressure leaching process includes only process oxygen; the process oxygen is divided into several streams, which enter the respective reaction chambers of the second-stage oxygen pressure vessel 8.

[0058] The exhaust gas from the second-stage oxygen pressure vessel 8 goes to the second-stage vessel exhaust condenser 7. The slurry discharged from the second-stage oxygen pressure vessel 8 passes through the second-stage secondary preheater 10 and the second-stage primary preheater 9 in sequence to recover the heat contained therein, and the temperature is reduced from about 165°C to 107.5°C and 80.5°C in sequence; then it is depressurized from about 1.3 MPa(G) to about 0.12 MPa(G) through a valve.

[0059] After depressurization, the material enters the second-stage gas separator 11. Since the depressurization is performed below 100°C, only a small amount of dissolved non-condensable gas is released. This non-condensable gas is separated by the second-stage gas separator 11; it can be directly vented at a high point on-site, or a small heat exchanger can be used to condense the contained moisture and cool the non-condensable gas before venting at a high point on-site. The slurry processed by the second-stage gas separator 11 is then transported to the second-stage thickening tank 12 by the second-stage reactor discharge pump.

[0060] The two-stage thickening tank 12 separates the feed into supernatant and underflow by gravity settling; the supernatant from the second stage goes to the first-stage oxygen pressure leaching system; the underflow from the second stage is sent out of the boundary area to the waste slag treatment unit. The discharge temperature of the supernatant and the underflow from the second stage is approximately 75°C.

[0061] Based on this, the grinding underflow after primary preheating in the first stage of the oxygen pressure leaching process is combined with the second stage supernatant at 70°C. After mixing, the temperature is approximately 73.4°C, and then it enters the first stage secondary preheater 4. Similarly, it utilizes the heat from the first stage kettle discharge to raise the temperature to approximately 130°C through inter-wall heat exchange; then it enters the first stage oxygen pressure kettle 2.

[0062] Specifically, in this embodiment, with a zinc ore feed rate of 20 t / h, the total process oxygen consumption is 4.77 t / h, and the start-up process steam consumption is 17.19 t / h. However, using... Figure 4 The existing process has the same feed rate, using 7.45 t / h of process oxygen and 41.37 t / h of process steam. Compared with the existing technology, it can save 35% of process oxygen and 58% of process steam. Once the first-stage oxygen pressure vessel 2 and the second-stage oxygen pressure vessel 8 are running stably, there is no need to add fresh steam, saving 100% of steam.

[0063] In this embodiment, with a zinc ore feed rate of 100 t / h, a total of 27 t / h of process oxygen and 81.34 t / h of process steam are used for start-up. However, using... Figure 4 The existing process equipment shown has the same feed rate, using 37.26 t / h of process oxygen and 206 t / h of process steam. Compared with the existing technology, it can save 27.5% of process oxygen and 60% of process steam. Once the first-stage oxygen pressure vessel 2 and the second-stage oxygen pressure vessel 8 are running stably, there is no need to add fresh steam, saving 100% of steam.

[0064] The above description is only a preferred embodiment of the present invention. It should be noted that, for those skilled in the art, several improvements and modifications can be made without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. An oxygen pressure leaching process characterised in that, The system includes at least one stage of oxygen pressure leaching, which comprises grinding underflow pretreatment, a first stage of oxygen pressure leaching treatment, a first stage of slurry heat exchange and depressurization, a first stage of slurry gas separation, and a first stage of slurry separation to obtain a first stage of concentrated supernatant and a first stage of concentrated underflow. The grinding underflow pretreatment includes contact countercurrent heat exchange, pressurization, and primary and secondary preheating. The system also includes a two-stage oxygen pressure leaching process, which comprises acid pretreatment, mixing and heat exchange of a first stage of concentrated underflow with acid, a second stage of oxygen pressure leaching treatment, a second stage of slurry heat exchange and depressurization, a second stage of slurry gas separation, and a second stage of slurry separation to obtain two stages of supernatant and two stages of underflow. The first slurry obtained from the first stage of oxygen pressure leaching treatment exchanges heat with the grinding underflow through the inter-wall heat exchanger; the second slurry obtained from the second stage of oxygen pressure leaching treatment exchanges heat with the first stage of thickened underflow through the inter-wall heat exchanger; the grinding underflow exchanges heat with the exhaust gas from the first stage of oxygen pressure leaching treatment through contact; and the acid solution exchanges heat with the exhaust gas from the second stage of oxygen pressure leaching treatment through contact.

2. The pressure leaching process for oxygen according to claim 1, characterized in that, The supernatant from the second stage and the grinding underflow are subjected to a single oxygen pressure leaching process.

3. The oxygen pressure leaching method as described in claim 1, characterized in that, The exhaust gas from the two-stage oxygen pressure leaching process is used in the first-stage oxygen pressure leaching process.

4. An apparatus for use in the oxygen pressure leaching method as described in any one of claims 1-3, characterized in that, It includes at least a stage of condenser exhaust, a stage of oxygen pressure vessel, a stage of primary preheater, a stage of secondary preheater, a stage of gas distributor, and a stage of thickener. Along the material flow direction, the raw material feed pipe is connected to the raw material inlet of the stage of condenser exhaust, the material outlet of the stage of condenser exhaust is connected to the material inlet of the stage of primary preheater, the material outlet of the stage of primary preheater is connected to the material inlet of the stage of secondary preheater, the material outlet of the stage of secondary preheater is connected to the material inlet of the stage of oxygen pressure vessel, the exhaust port of the stage of oxygen pressure vessel is connected to the exhaust inlet of the stage of condenser exhaust, and the material outlet of the stage of oxygen pressure vessel, the material inlet of the stage of secondary preheater, the material outlet of the stage of secondary preheater, the stage of gas distributor, and the stage of thickener are connected in sequence.

5. The device as described in claim 4, characterized in that, It also includes a two-stage reactor exhaust condenser, a two-stage oxygen pressure vessel, a two-stage primary preheater, a two-stage secondary preheater, a two-stage gas separator, and a two-stage thickening tank; the acid feed pipe is connected to the acid inlet of the two-stage reactor exhaust condenser, the acid outlet of the two-stage reactor exhaust condenser is connected to the material inlet of the two-stage primary preheater, the material outlet of the two-stage primary preheater is connected to the material inlet of the two-stage secondary preheater, the concentrated liquid outlet of the primary thickening tank is connected to the material inlet of the two-stage secondary preheater, the material outlet of the two-stage secondary preheater is connected to the material inlet of the two-stage oxygen pressure vessel, the exhaust port of the two-stage oxygen pressure vessel is connected to the exhaust inlet of the two-stage reactor exhaust condenser, and the material outlet of the two-stage oxygen pressure vessel, the material inlet of the two-stage secondary preheater, the material outlet of the two-stage secondary preheater, the two-stage gas separator, and the two-stage thickening tank are connected in sequence.

6. The device as described in claim 5, characterized in that, The exhaust port of the second-stage reactor exhaust condenser is connected to the air inlet of the first-stage oxygen pressure vessel or to any compartment of the first-stage oxygen pressure vessel.

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