System for improving ore pulp concentration in laterite-nickel ore high-pressure acid leaching process

Abstract

A system for improving pulp concentration in a laterite-nickel ore high-pressure acid leaching process comprises a thickener, an underflow discharge port of the thickener is divided into two paths, one path is sequentially connected in series with a pulp mixing tank, a high-pressure acid leaching feed tank, a low-temperature preheater, a medium-temperature preheater, a high-temperature preheater and a high-pressure kettle, and the other path is connected in series with a high-pressure kettle. A steam exhaust outlet of the low-temperature preheater, a steam exhaust outlet of the medium-temperature preheater and a steam exhaust outlet of the high-temperature preheater are respectively connected to the inside of the size mixing tank through steam exhaust pipelines; the other path is sequentially connected in series with the underflow buffer tank and the filter press; a discharge port of the filter press is connected with a filter cake bin, a vibrating funnel, a disc feeder and a constant feeder are sequentially arranged below the filter cake bin, and the constant feeder is connected to a high-pressure acid leaching feeding groove through a belt conveyor; and the inner cavity of the size mixing tank is externally connected with an in-plant steam pipe network. Through the combination of filter pressing concentration and steam exhaust preheating, the flowability of the ore pulp is improved while the concentration of the ore pulp is improved, so that the productivity is improved, energy conservation and consumption reduction are realized, and the method has remarkable advantages in the aspects of energy conservation, emission reduction and investment conservation.

Description

Technical Field

[0001] This invention belongs to the field of non-ferrous metal metallurgy technology, and relates to the smelting technology of laterite nickel ore, specifically to a system for increasing the slurry concentration in the high-pressure acid leaching process of laterite nickel ore. Background Technology

[0002] Laterite nickel ore is an important raw material for extracting nickel and cobalt, and its smelting processes mainly include pyrometallurgical and hydrometallurgical methods. In the hydrometallurgical process, high-pressure acid leaching has become the mainstream due to its strong adaptability to low-grade ores. In the traditional high-pressure acid leaching process, the slurry is concentrated to about 38% concentration by a thickener, then heated in a three-stage preheater, and finally sent to a pressure vessel for reaction.

[0003] However, when the concentration of laterite nickel ore slurry exceeds 38%, its yield stress and stiffness coefficient increase significantly, its fluidity deteriorates, and it becomes difficult to transport. Therefore, the slurry concentration is limited in traditional processes, which restricts the improvement of overall production capacity. In addition, preheater exhaust steam (low temperature, medium temperature, high temperature) is usually directly discharged to the tail gas scrubbing system, resulting in heat energy waste. The tail gas treatment system is large-scale and requires high investment. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this invention proposes a system for increasing slurry concentration in the high-pressure acid leaching process of laterite nickel ore, in order to solve the technical problem of how to increase slurry concentration without affecting conveying performance and to recover and utilize the heat from preheater exhaust steam.

[0005] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A system for increasing slurry concentration in the high-pressure acid leaching process of laterite nickel ore includes a thickener. The underflow outlet of the thickener is divided into two paths. One path connects in series a slurry conditioning tank, a high-pressure acid leaching feed tank, a low-temperature preheater, a medium-temperature preheater, a high-temperature preheater, and a high-pressure autoclave. The exhaust outlets of the low-temperature preheater, the medium-temperature preheater, and the high-temperature preheater are connected to the inside of the slurry conditioning tank via exhaust pipes. The other path connects in series a bottomflow buffer tank and a filter press. The outlet of the filter press is connected to a filter cake silo. Below the filter cake silo are arranged in series a vibrating funnel, a disc feeder, and a quantitative feeder. The quantitative feeder is connected to the high-pressure acid leaching feed tank via a belt conveyor. The inner cavity of the slurry conditioning tank is connected to the plant's steam network.

[0006] Preferably, the exhaust pipes of the medium-temperature preheater and the high-temperature preheater are respectively equipped with a first pressure reducing valve and a second pressure reducing valve.

[0007] Preferably, a first gate valve and a second gate valve are respectively installed on the exhaust pipes of the medium-temperature preheater and the high-temperature preheater, and the first gate valve and the second gate valve are respectively located before / after the first pressure reducing valve and the second pressure reducing valve.

[0008] Preferably, the outlet of the high-temperature preheater is connected to the autoclave via a high-temperature diaphragm pump.

[0009] Preferably, a first slurry pump is connected between the underflow outlet of the thickener and the inlet of the slurry conditioning tank; a second slurry pump is connected between the outlet of the slurry conditioning tank and the inlet of the high-pressure acid leaching feed tank; a third slurry pump is connected between the outlet of the high-pressure acid leaching feed tank and the inlet of the low-temperature preheater; a fourth slurry pump is connected between the outlet of the low-temperature preheater and the inlet of the medium-temperature preheater; a fifth slurry pump is connected between the outlet of the medium-temperature preheater and the inlet of the high-temperature preheater; a sixth slurry pump is connected between the thickener and the underflow buffer tank; and a seventh slurry pump is connected between the underflow buffer tank and the filter press.

[0010] Preferably, two fourth slurry pumps are connected in series between the outlet of the low-temperature preheater and the inlet of the medium-temperature preheater.

[0011] Preferably, three fifth slurry pumps are connected in series between the outlet of the medium-temperature preheater and the inlet of the high-temperature preheater.

[0012] Preferably, the outside of the slurry preparation tank and the high-pressure acid leaching feed tank is equipped with heat insulation facilities.

[0013] Preferably, a third pressure reducing valve, a third gate valve (17-3), and an electric regulating valve are connected between the slurry mixing tank and the plant's steam pipeline network.

[0014] Preferably, the mixing tank is equipped with a temperature detection mechanism, which is interlocked with the electric regulating valve.

[0015] Compared with the prior art, the present invention has the following beneficial technical effects: (1) The system proposed in this invention for increasing the slurry concentration in the high-pressure acid leaching process of laterite nickel ore improves the fluidity of the slurry by combining pressure filtration concentration with exhaust steam preheating, thereby increasing production capacity and achieving energy saving and consumption reduction.

[0016] (2) By using a filter press, some of the slurry is further concentrated to a high-concentration filter cake of about 60%, and then mixed with conventional concentration slurry in a slurry mixing tank to increase the overall slurry concentration to 40% to 45%, thereby increasing the valuable metal content per unit volume of slurry and improving the system's processing capacity.

[0017] (3) The system proposed in this invention for increasing the slurry concentration in the high-pressure acid leaching process of laterite nickel ore directly heats the slurry by introducing the exhaust steam from the low-temperature, medium-temperature and high-temperature preheaters into the slurry conditioning tank. This not only recovers the waste heat, but also significantly reduces the viscosity and stiffness of the high-concentration slurry by raising the temperature, thus improving its fluidity and enabling it to still meet the transportation requirements after the concentration is increased.

[0018] (4) The system proposed in this invention for increasing the slurry concentration in the high-pressure acid leaching process of laterite nickel ore reduces the amount of steam entering the tail gas scrubbing system, reduces the scale and investment of the tail gas treatment system, and achieves multiple effects of energy saving, emission reduction and cost reduction. Attached Figure Description

[0019] Figure 1 This is a schematic diagram of the process flow of the system of the present invention.

[0020] The meanings of the labels in the diagram are as follows: 1-Thickener, 2-Bottom flow buffer tank, 3-Slurry conditioning tank, 4-High pressure acid leaching feed tank, 5-Low temperature preheater, 6-Medium temperature preheater, 7-High temperature preheater, 8-Filter press, 9-Filter cake silo, 10-Vibrating funnel, 11-Disc feeder, 12-Quantitative feeder, 13-Belt conveyor, 14-1-First slurry pump, 14-2-Second slurry pump, 14-3-Third slurry pump, 14-4-Fourth slurry pump, 14-5-Fifth slurry pump, 14-6-Sixth slurry pump, 15-High temperature diaphragm pump, 16-1-First pressure reducing valve, 16-2-Second pressure reducing valve, 16-3-Third pressure reducing valve, 17-1-First gate valve, 17-2-Second gate valve, 17-3-Third gate valve, 18-Electric regulating valve, 19-High pressure vessel, 20-In-plant steam network.

[0021] The specific content of the present invention will be further explained in detail below with reference to the embodiments. Detailed Implementation

[0022] It should be noted that, unless otherwise specified, all the equipment and materials used in this invention are those known in the prior art.

[0023] The principle of this invention is that as the temperature of laterite nickel ore slurry increases, the viscosity of the slurry gradually decreases, the interaction between particles weakens, the stiffness coefficient decreases, and the slurry fluidity increases. Therefore, the slurry concentration can be increased within a certain range, and the slurry can be heated to 40℃~80℃, so that the rheological properties of the high-temperature, high-concentration slurry are comparable to those of the room-temperature, 38% concentration slurry, thus meeting the transportation requirements.

[0024] Following the above technical solutions, specific embodiments of the present invention are given below. It should be noted that the present invention is not limited to the following specific embodiments, and all equivalent modifications made based on the technical solutions of this application fall within the protection scope of the present invention.

[0025] Example: like Figure 1As shown, this embodiment discloses a system for increasing slurry concentration in the high-pressure acid leaching process of laterite nickel ore. The system includes a thickener 1, whose underflow outlet is divided into two paths. One path connects in series with a slurry conditioning tank 3, a high-pressure acid leaching feed tank 4, a low-temperature preheater 5, a medium-temperature preheater 6, a high-temperature preheater 7, and a high-pressure autoclave 19. The exhaust outlets of the low-temperature preheater 5, the medium-temperature preheater 6, and the high-temperature preheater 7 are connected to the interior of the slurry conditioning tank 3 via exhaust pipes. The other path connects in series with an underflow buffer tank 2 and a filter press 8. The outlet of the filter press 8 is connected to a filter cake silo 9. Below the filter cake silo 9 are a vibrating funnel 10, a disc feeder 11, and a quantitative feeder 12. The quantitative feeder 12 is connected to the high-pressure acid leaching feed tank 4 via a belt conveyor 13. The inner cavity of the slurry conditioning tank 3 is connected to the plant's steam network 20. Its function is to define the core components and connections of the slurry concentration enhancement system, serving as a fundamental constraint on the overall system architecture. Specifically, it can be broken down into three main functional modules: First, the main slurry conveying module, where the thickener's underflow outlet splits into two paths. One path forms the main flow of "slurry conditioning tank → high-pressure acid leaching feed tank → three-stage preheater → autoclave," ensuring the slurry undergoes thickening and preheating in the process sequence before entering the reaction stage. Second, the slurry concentration enhancement module, where the other path, through a link of "underflow buffer tank → filter press → filter cake silo → series feeding and weighing equipment → belt conveyor," filters a portion of the 38% concentration slurry to a 60% concentration filter cake, which is then conveyed to the high-pressure acid leaching feed tank for mixing with the main slurry. Third, the heat recovery and temperature assurance module, which specifies that the exhaust pipes of the three-stage preheater are all connected to the slurry conditioning tank to achieve the recovery and utilization of exhaust heat energy. Simultaneously, the slurry conditioning tank is connected to the plant's steam network as a supplementary means of temperature regulation. This breakthrough directly addresses three major shortcomings of existing technologies. First, by increasing the slurry concentration to 60% using a filter press and then mixing it with a 38% concentration slurry to adjust it to 40-45%, combined with subsequent preheater exhaust steam heating to improve slurry rheology, it overcomes the traditional 38% concentration limit, increasing the unit's capacity by approximately 10% and achieving increased production and efficiency. Second, by introducing the exhaust steam from the three-stage preheater, which was originally directly discharged into the tail gas scrubbing system, into the slurry conditioning tank to heat the slurry, it completely recovers the exhaust heat energy at different temperature levels (105℃, 165℃, 215℃), avoiding energy waste. Third, because the exhaust steam is no longer discharged into the tail gas scrubbing system, the scale of the original tail gas scrubbing unit can be significantly reduced or even eliminated, significantly saving on equipment and civil engineering investment. Furthermore, the design of connecting to the plant's internal steam pipeline network ensures stable slurry temperature and improves process adaptability.

[0026] In this embodiment, the exhaust pipes of the medium-temperature preheater 6 and the high-temperature preheater 7 are respectively equipped with a first pressure-reducing valve 16-1 and a second pressure-reducing valve 16-2. The exhaust pressure of the medium-temperature preheater 6 is 590 kPa(g), the exhaust pressure of the high-temperature preheater 7 is 1.9 MPa(g), and the exhaust pressure of the low-temperature preheater 5 is 15 kPa(g). By using the pressure-reducing valves, the exhaust pressures of the medium-temperature and high-temperature preheaters can be uniformly reduced to 15 kPa(g), ensuring that the three types of exhaust steam are introduced into the slurry mixing tank at appropriate pressures. This avoids the impact and turbulence problems caused by directly introducing exhaust steam of different pressure levels into the slurry mixing tank, ensuring the stability of the slurry mixing in the slurry mixing tank. At the same time, the exhaust steam after unifying the pressure can contact the slurry for heat exchange more evenly, improve the heat recovery efficiency, ensure that the slurry temperature rises stably to 40~80℃, further ensuring the rheological properties of the high-concentration slurry and providing stable conditions for subsequent transportation.

[0027] In this embodiment, a first gate valve 17-1 and a second gate valve 17-2 are respectively installed on the exhaust pipes of the medium-temperature preheater 6 and the high-temperature preheater 7. The first gate valve 17-1 and the second gate valve 17-2 are located before and after the first pressure reducing valve 16-1 and the second pressure reducing valve 16-2, respectively, to realize the on / off control of the exhaust pipes. The design of the front and rear double gate valves can form a safe isolation zone. This improves the system's operational safety and process adjustment flexibility. During equipment maintenance (such as pressure reducing valve maintenance), the gate valves before and after the pressure reducing valve can be closed to isolate the exhaust pipes and prevent high-temperature and high-pressure exhaust steam leakage. During normal production, the exhaust steam flow can be adjusted by the gate valves, and the amount of steam introduced into the slurry tank can be precisely controlled in conjunction with the pressure reducing valves to ensure the accuracy of slurry temperature regulation and further optimize the heat recovery effect.

[0028] In this embodiment, the outlet of the high-temperature preheater 7 is connected to the autoclave 19 via a high-temperature diaphragm pump 15. After being heated by the three-stage preheater, the slurry reaches a temperature of approximately 200°C. The autoclave 19 provides a high-pressure reaction environment, and the high-temperature diaphragm pump is capable of conveying slurry under high-temperature and high-pressure conditions. This solves the problem of stable slurry delivery under high-temperature and high-pressure conditions. Traditional conveying equipment is difficult to adapt to the high-pressure conveying requirements of slurry at around 200°C. The high-temperature diaphragm pump ensures that the preheated slurry can be stably and efficiently delivered into the autoclave, guaranteeing the continuous and stable operation of the high-pressure acid leaching reaction and avoiding production capacity fluctuations caused by conveying failures.

[0029] In this embodiment, a first slurry pump 14-1 is connected between the underflow outlet of the thickener 1 and the inlet of the slurry conditioning tank 3; a second slurry pump 14-2 is connected between the outlet of the slurry conditioning tank 3 and the inlet of the high-pressure acid leaching feed tank 4; a third slurry pump 14-3 is connected between the outlet of the high-pressure acid leaching feed tank 4 and the inlet of the low-temperature preheater 5; a fourth slurry pump 14-4 is connected between the outlet of the low-temperature preheater 5 and the inlet of the medium-temperature preheater 6; a fifth slurry pump 14-5 is connected between the outlet of the medium-temperature preheater 6 and the inlet of the high-temperature preheater 7; a sixth slurry pump 14-6 is connected between the thickener 1 and the underflow buffer tank 2; and a seventh slurry pump 14-7 is connected between the underflow buffer tank 2 and the filter press 8. The slurry transport chain has been refined, specifying that slurry pumps are installed at each core equipment node. This includes the first slurry pump from the thickener to the mixing tank, the second slurry pump from the mixing tank to the high-pressure acid leaching feed tank, and seven slurry pumps in total between the subsequent preheaters, from the thickener to the underflow buffer tank, and from the underflow buffer tank to the filter press. Addressing the high viscosity and poor fluidity of laterite nickel ore slurry, the comprehensive installation of slurry pumps provides ample power for slurry transport, ensuring smooth slurry flow at each stage and preventing pipeline blockages caused by slurry stagnation. Simultaneously, the independent slurry pumps at each node allow for precise adjustment of transport pressure and flow rate based on slurry concentration and temperature differences at each stage, improving the overall system's operational stability and controllability, and ensuring the smooth implementation of core processes such as thickening and preheating.

[0030] In this embodiment, two fourth slurry pumps 14-4 are connected in series between the outlet of the low-temperature preheater 5 and the inlet of the medium-temperature preheater 6, and three fifth slurry pumps 14-5 are connected in series between the outlet of the medium-temperature preheater 6 and the inlet of the high-temperature preheater 7.

[0031] In this embodiment, the slurry preparation tank 3 and the high-pressure acid leaching feed tank 4 are equipped with external heat insulation facilities. These facilities can take the form of external heat insulation material, steam insulation, or electric heat tracing. This reduces heat loss from the slurry within the slurry preparation tank and the feed tank. The slurry in the slurry preparation tank is heated to 40-80°C by exhaust steam from the preheater. The slurry in the feed tank needs to maintain a certain temperature before entering the subsequent preheating stage. The heat insulation facilities ensure stable slurry temperature, preventing temperature fluctuations due to heat loss, thus protecting the rheological properties of the high-concentration slurry. Simultaneously, reducing heat loss decreases the frequency of supplemental steam usage, further improving energy efficiency and reducing production energy consumption.

[0032] In this embodiment, a third pressure reducing valve 16-3, a third gate valve 17-3, and an electric regulating valve 18 are connected between the slurry conditioning tank 3 and the plant's steam pipeline network 20, forming a complete supplementary steam regulation link. This improves the accuracy and safety of supplementary steam regulation. The third pressure reducing valve can reduce the high-pressure steam in the plant's steam pipeline network to a pressure level suitable for the slurry conditioning tank, avoiding the impact caused by direct introduction of high-pressure steam; the third gate valve realizes the on / off control of the supplementary steam link, facilitating operation and maintenance; the electric regulating valve can accurately regulate the steam flow rate, ensuring that when the heat from the preheater exhaust is insufficient, heat can be supplemented in a timely and accurate manner, ensuring that the slurry temperature remains stable at 40~80℃.

[0033] In this embodiment, the slurry mixing tank 3 is equipped with a temperature detection mechanism, which is interlocked with the electric regulating valve 18. This means the temperature detection mechanism collects slurry temperature data in real time. When the temperature is lower than the set value, it automatically triggers the electric regulating valve to open or increase its opening to supplement steam; when the temperature reaches the set value, it automatically closes or decreases its opening. This achieves automated and precise control of the slurry temperature. Compared to manual adjustment, the interlocked control has a faster response speed and can promptly address heat fluctuations, preventing the slurry temperature from becoming too high or too low. Simultaneously, automated control reduces manual intervention, lowers operational errors, and improves process stability. Furthermore, precise temperature control ensures the rheological stability of high-concentration slurry, further guaranteeing conveying efficiency and production capacity stability, while avoiding energy waste due to excessive steam supplementation, thus improving the overall economic efficiency of the process. The temperature detection mechanism in this embodiment is existing equipment and will not be described in detail here.

[0034] The temperature detection mechanism in this embodiment can be any commonly used existing temperature sensor.

[0035] Based on the system of this embodiment, combined with the appendix Figure 1 A specific method for preheating the slurry in the pressurized acid leaching process of laterite nickel ore is disclosed: In the slurry thickening section of the pressurized acid leaching process for laterite nickel ore, a portion of the underflow (38% concentration) from the thickener is pumped to the slurry conditioning tank, and another portion is pumped to the thickener underflow buffer tank for buffering before being pumped to the filter press. After filtration, the filter cake concentration is ~60%. It is buffered in the filter cake silo and weighed by the discharge and weighing equipment (vibrating funnel + disc feeder + quantitative feeder) below the silo. Then, it is sent to the high-pressure acid leaching feed tank via belt conveyor. In the slurry conditioning tank, it is mixed with the 38% thickener underflow to adjust the slurry concentration to 40-45%. Meanwhile, the exhaust steam from the low-temperature preheater (temperature 105℃, pressure 15kPa(g)) is piped into the slurry in the mixing tank; the exhaust steam from the medium-temperature preheater (temperature 165℃, pressure 590kPa(g)) is depressurized (down to 15kPa(g)) by a pressure reducing valve before being sent to the mixing tank; the exhaust steam from the high-temperature preheater (temperature 215℃, pressure 1.9MPa(g)) is depressurized (down to 15kPa(g)) by a pressure reducing valve before being sent to the mixing tank. The exhaust steam from the low-temperature, medium-temperature, and high-temperature preheaters heats the slurry in the mixing tank to 40~80℃, pumps it to the high-pressure acid leaching feed tank for buffering, and then pumps it into the low-temperature preheater to complete subsequent operations. To facilitate production adjustments and ensure the temperature of the preheated slurry, steam pipes and valve assemblies from the plant's pipeline network are installed in the mixing tank as supplementary heat.

[0036] The preferred embodiments of this disclosure have been described in detail above with reference to the accompanying drawings. However, this disclosure is not limited to the specific details of the above embodiments. Within the scope of the technical concept of this disclosure, various simple modifications can be made to the technical solutions of this disclosure, and these simple modifications all fall within the protection scope of this disclosure.

[0037] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, this disclosure will not describe the various possible combinations separately.

[0038] Furthermore, the various implementation methods disclosed in this solution can be combined in any way, as long as they do not violate the spirit of this disclosure, they should also be regarded as the content invented by this disclosure.

Claims

1. A system for increasing slurry concentration in high-pressure acid leaching of laterite nickel ore, characterized in that, The thickener (1) is divided into two paths at its underflow outlet. One path is connected in series with the slurry tank (3), the high-pressure acid leaching feed tank (4), the low-temperature preheater (5), the medium-temperature preheater (6), the high-temperature preheater (7), and the pressure vessel (19). The exhaust outlets of the low-temperature preheater (5), the medium-temperature preheater (6), and the high-temperature preheater (7) are connected to the inside of the slurry tank (3) through exhaust pipes. The other path is connected in series with the underflow buffer tank (2) and the filter press (8). The outlet of the filter press (8) is connected to the filter cake hopper (9). Below the filter cake hopper (9) are arranged a vibrating funnel (10), a disc feeder (11) and a quantitative feeder (12). The quantitative feeder (12) is connected to the high-pressure acid leaching feed tank (4) via a belt conveyor (13). The inner cavity of the slurry mixing tank (3) is connected to the plant's steam pipeline network (20).

2. The system for increasing slurry concentration in the high-pressure acid leaching process of laterite nickel ore as described in claim 1, characterized in that, The exhaust pipes of the medium-temperature preheater (6) and the high-temperature preheater (7) are respectively equipped with a first pressure reducing valve (16-1) and a second pressure reducing valve (16-2).

3. The system for increasing slurry concentration in the high-pressure acid leaching process of laterite nickel ore as described in claim 2, characterized in that, A first gate valve (17-1) and a second gate valve (17-2) are respectively installed on the exhaust pipes of the medium-temperature preheater (6) and the high-temperature preheater (7). The first gate valve (17-1) and the second gate valve (17-2) are located before / after the first pressure reducing valve (16-1) and the second pressure reducing valve (16-2), respectively.

4. The system for increasing slurry concentration in the high-pressure acid leaching process of laterite nickel ore as described in claim 1, characterized in that, The outlet of the high-temperature preheater (7) is connected to the autoclave (19) via a high-temperature diaphragm pump (15).

5. The system for increasing slurry concentration in high-pressure acid leaching of laterite nickel ore as described in claim 1, characterized in that, A first slurry pump (14-1) is connected between the underflow outlet of the thickener (1) and the inlet of the slurry conditioning tank (3). A second slurry pump (14-2) is connected between the outlet of the slurry conditioning tank (3) and the inlet of the high-pressure acid leaching feed tank (4). A third slurry pump (14-3) is connected between the outlet of the high-pressure acid leaching feed tank (4) and the inlet of the low-temperature preheater (5). A fourth slurry pump (14-4) is connected between the outlet of the low-temperature preheater (5) and the inlet of the medium-temperature preheater (6). A fifth slurry pump (14-5) is connected between the outlet of the medium-temperature preheater (6) and the inlet of the high-temperature preheater (7). A sixth slurry pump (14-6) is connected between the thickener (1) and the underflow buffer tank (2). A seventh slurry pump (14-7) is connected between the underflow buffer tank (2) and the filter press (8).

6. The system for increasing slurry concentration in the high-pressure acid leaching process of laterite nickel ore as described in claim 5, characterized in that, Two fourth slurry pumps (14-4) are connected in series between the outlet of the low-temperature preheater (5) and the inlet of the medium-temperature preheater (6).

7. The system for increasing slurry concentration in the high-pressure acid leaching process of laterite nickel ore as described in claim 5, characterized in that, Three fifth slurry pumps (14-5) are connected in series between the outlet of the medium-temperature preheater (6) and the inlet of the high-temperature preheater (7).

8. The system for increasing slurry concentration in the high-pressure acid leaching process of laterite nickel ore as described in claim 1, characterized in that, The outside of the slurry preparation tank (3) and the high-pressure acid leaching feeding tank (4) is equipped with heat preservation facilities.

9. The system for increasing slurry concentration in high-pressure acid leaching of laterite nickel ore as described in any one of claims 1-8, characterized in that, A third pressure reducing valve (16-3), a third gate valve (17-3), and an electric regulating valve (18) are connected between the slurry tank (3) and the plant steam pipeline (20).

10. The system for increasing slurry concentration in high-pressure acid leaching of laterite nickel ore as described in claim 9, characterized in that, The slurry tank (3) is equipped with a temperature detection mechanism, which is interlocked with the electric regulating valve (18).

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