A method for gradient continuous leaching of laterite nickel ore

Abstract

The invention belongs to the field of metallurgy technology and discloses a method for gradient continuous leaching of laterite nickel ore, which comprises the following steps: along the material conveying direction, the high pressure acid leaching process is sequentially divided into a mixed leaching zone, a stable leaching zone and an adjustment leaching zone. The high leaching efficiency of nickel, cobalt and manganese in the laterite nickel ore is achieved by controlling the temperature, pressure, reaction time and acid addition flow rate of each zone. The present invention innovatively performs zoning processing on the high pressure acid leaching process, wherein the mixed leaching zone achieves full mixing of materials, reduces sudden changes, and slows down scaling; The stable leaching zone achieves stable and efficient leaching of laterite nickel ore; the adjustment leaching zone performs buffering leaching to reduce the load of the discharge on the downstream device, improve the one-time leaching efficiency, slow down scaling, and reduce the probability of Al hydrolysis, thereby achieving the reduction of scaling of the autoclave while inhibiting further leaching of Fe and Al, and making full use of acid and residue to achieve efficient leaching of nickel, cobalt and manganese. Furthermore, the waste heat generated after the slurry is discharged from the adjustment leaching zone can be recycled.

Description

[0001] Description

[0002] A METHOD FOR GRADIENT CONTINUOUS LEACHING OF LATERITE NICKEL ORE Field Of The Disclosure

[0003] The present invention belongs to the field o f metallurgy technology, and speci fically relates to a method for gradient continuous leaching of laterite nickel ore .

[0004] Background

[0005] Nickel , as an important strategic metal , has good mechanical strength, ductility and chemical stability . It is an indispensable raw material in the fields of stainless steel , catalysts and new energy batteries , and plays an important role in the development of the national economy . Existing research shows that the global nickel resource reserves are about 95 million tons , and the resource concentration is high . Among them, laterite nickel ore is mainly distributed in the tropical and subtropical regions of the Paci fic Rim within 30 ° north and south latitude .

[0006] The hydrometallurgical process has the characteristics of being able to process complex low-grade nickel ores , and has low energy consumption, low cost and low pollution . In recent years , with the growing demand for nickel in stainless steel and new energy materials , the hydrometallurgical nickel extraction process from laterite nickel ore has been more widely used . According to the di fferent pressures during the leaching process , the hydrometallurgical nickel extraction process from laterite nickel ore can be divided into atmospheric pressure leaching and high pressure leaching, and according to the di f ferent leaching media, it can be divided into ammonia leaching and acid leaching . At present , most of the laterite nickel ore proj ects carried out in the world use the hydrometallurgical process of high pressure acid leaching .

[0007] High-pressure acid leaching is a process for extracting valuable metal elements nickel and cobalt from laterite nickel ore with high selectivity under high temperature and pressure conditions . Compared with other hydrometallurgical processes , high-pressure acid leaching has the advantage of high nickel and cobalt recovery rates , but the nickel and cobalt recovery rates still need to be further improved . There are also problems such as the di f ficulty in treatment of leaching residue , the rapid increase in the stack amount of leaching residue and the easy scaling of the autoclave .

[0008] Summary

[0009] In view of this , the present invention aims to develop a method for gradient continuous leaching of laterite nickel ore to achieve the purpose of inhibiting the leaching of impurities such as iron and aluminum and improving the recovery rate of nickel , cobalt and manganese , while ef fectively solving or alleviating the scaling problem of the autoclave .

[0010] In order to achieve the above-mentioned purpose , the technical solution of the present invention is speci fically as follows :

[0011] A method for gradient continuous leaching of laterite nickel ore , comprising the following steps :

[0012] Along the material conveying direction, the high pressure acid leaching process is sequentially divided into a mixed leaching zone , a stable leaching zone and an adj ustment leaching zone , and acid is added to both the mixed leaching zone and the stable leaching zone . The temperature of the mixed leaching zone is T1 and the duration is tl , the temperature of the stable leaching zone is T2 and the duration is t2 , the temperature of the adj ustment leaching zone is T3 and the duration is t3 ; Speci fically, the temperature and duration of each zone meet the following conditions at the same time :

[0013] Temperature , T2>T3>T1 ;

[0014] Duration, t2>t3>tl .

[0015] Preferably, in the above method, the acid is speci fically sul furic acid .

[0016] Preferably, in the above method, the amount of acid added to the stable leaching zone is less than or equal to the amount of acid added to the mixed leaching zone ; more preferably, in the mixed leaching zone , the amount of acid added is 200-300 kg / 1 dry ore ; in the stable leaching zone , the amount of acid added is 50- 100 kg / t dry ore . Preferably, in the above method, the temperature of the mixed leaching zone is 180~210 ° C, the temperature of the stable leaching zone is 240~260 ° C, and the temperature of the adj ustment leaching zone is 210~230 ° C ; further, the duration tl of the mixed leaching zone is 10~ 15 min, the duration t2 of the stable leaching zone is 25~40 min, and the duration t3 of the adj ustment leaching zone is 15~25 min .

[0017] Preferably, in the above method, manganese-containing ore is added to the adj ustment leaching zone , which may be at least one of manganese slag, magnesian laterite nickel ore and low-aluminum laterite nickel ore . In some speci fic embodiments of the present invention, the manganese slag is the slag obtained by concentrating and filtering the lean liquid generated after precipitating nickel , cobalt and manganese with alkali solution in the acid leaching process of laterite nickel ore .

[0018] Preferably, in the above method, the mixed leaching zone is the front compartment of the autoclave, the stable leaching zone is the middle compartment of the autoclave , and the adj ustment leaching zone is the rear compartment of the autoclave .

[0019] More preferably, in the above method, the pressure of the autoclave is 2~ 6. 5 MPa; in the speci f ic implementation process , the temperature and pressuri zation of each area of the autoclave are increased by introducing high-temperature steam to achieve suf ficient mixing between the hot high-temperature steam and the cold leaching slurry, and the pressure of the high-pressure reactor is positively correlated with the temperature of the area where it is located . The pressure can be set based on the temperature of each compartment of the autoclave set above , and no speci fic limitation is made here .

[0020] More preferably, in the above process , the material i s discharged from the adj ustment leaching zone and then cooled to below 100 ° C by flash evaporation and the waste heat generated after the slurry is discharged from the adj ustment leaching zone can be recycled .

[0021] Compared with the prior art , the beneficial ef fects of the present invention are :

[0022] ( 1 ) The present invention innovatively divides the high-pressure leaching process into three leaching zones , namely, a mixed leaching zone , a stable leaching zone and an adj ustment leaching zone . Along the material conveying direction, the temperature gradually rises and is maintained at a high temperature in the stable leaching zone , and then the temperature is lowered in the adj ustment leaching zone . The present invention can selectively control the leaching and hydrolysis process of each element in di f ferent leaching zones by limiting the reaction temperature and duration of each zone .

[0023] ( 2 ) Compared with other elements , Fe in the slurry can be leached out faster . The present invention sets a mixed leaching zone and adj usts its temperature conditions so that the leached Fe ions are more easily hydrolyzed in the mixed leaching zone ; Fe is preferentially hydrolyzed in the low temperature environment of the mixed leaching zone to form a precipitate , which has a high iron content and is convenient for further utili zation .

[0024] ( 3 ) In the stable leaching zone with higher temperature , Al hydrolysis is the main process , while in the adj ustable leaching zone , lowering the temperature can inhibit the continued hydrolysis of Al , reduce the load of the discharge on the downstream device , and improve the one-time leaching ef ficiency . By controlling the reaction temperature and duration, the problem of Fe and Al being simultaneously hydrolyzed and mixed and deposited in the autoclave can be ef fectively avoided, ef fectively alleviating the scaling problem in the autoclave .

[0025] ( 4 ) Due to the hydrolysis of Fe and Al , some acid will be released; according to the acid content and temperature conditions of the adj ustment leaching zone , the present invention finds that adding an appropriate amount of manganese-containing ore in the adj ustable leaching zone can, on the one hand, make full use of the released acid for leaching, and on the other hand, further increase the content of valuable metal elements ( especially Mn) in the leachate to achieve re-enrichment ; When the Mn slag obtained by precipitating Ni , Co and Mn with alkaline solution is used in manganese-containing ore , not only the Mn leaching rate is ef fectively improved, but also the reuse of waste materials is reali zed .

[0026] Brief Description Of The Drawings

[0027] FIG . l is a process flow chart of a method for gradient continuous leaching of laterite nickel ore provided by the present invention .

[0028] Detailed Description Of Preferred Embodiments

[0029] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art to which the present invention belongs . The term " include" and any variation thereof in the claims and detailed descriptions of the present invention are intended to cover non-exclusive inclusions .

[0030] For laterite nickel ore , the traditional high-pressure acid leaching process is to acid-leach the slurry under fixed temperature conditions , and usually use slurry pretreatment ( such as mixing sodium sul fate and / or potassium sul fate into the slurry) , adj usting the acid concentration and adding additives ( such as Mg (NOs ) 2 ) to inhibit Fe and Al leaching and achieve selective leaching of nickel and cobalt . To address this problem, the present invention innovatively performs zoning treatment on the high-pressure leaching process , which can reduce the scaling of the high-pressure reactor while inhibiting the leaching of Fe and Al , and can make full use of acid and residue ( or low-grade laterite nickel ore ) to achieve ef ficient leaching of nickel , cobalt and manganese .

[0031] As shown in FIG . l , the method of the present invention includes the following steps :

[0032] Along the material conveying direction, the high-pressure acid leaching process is divided into a mixed leaching zone , a stable leaching zone and an adj ustment leaching zone in sequence ;

[0033] Acid is added to both the mixed leaching zone and the stable leaching zone , and preferably, the amount of acid added to the stable leaching zone is less than or equal to the amount of acid added to the mixed leaching zone ;

[0034] The mixed leaching zone is the front compartment of the autoclave , the temperature of this zone is Tl , and the duration is tl ; the stable leaching zone is speci fically the middle compartment of the autoclave , the temperature of this zone is T2 , and the duration is t2 ; the adj ustment leaching zone is the rear compartment of the autoclave , the temperature of this zone is T3 , and the duration is t3 ; wherein the temperature and duration of each zone meet the following conditions at the same time : T2>T3>T1 and t2>t3>tl ;

[0035] After the slurry leaves the adj ustment leaching zone and is cooled to below 100 ° C, it can enter the subsequent process according to the overall process flow .

[0036] In the actual production process , the autoclave is divided into several relatively independent reaction compartments in the hori zontal direction, each compartment has a stirring device , and there is a vertical partition between adj acent compartments , and the partition has through holes for slurry overflow and diversion . It can be understood that the autoclave used in the present invention has at least three compartments , and the number of compartments can be set according to actual needs , which is not limited here .

[0037] The technical solution of the present invention will be described clearly and completely below in conj unction with specific embodiments It should be understood that the embodiments described herein are only used to illustrate and explain the present invention and are not used to limit the present invention .

[0038] The mass content of each element in the laterite nickel ore used in the following embodiments and comparative examples is shown in Table 1 below :

[0039] Table 1 Composition of laterite nickel ore

[0040] The autoclave used in the following embodiments and comparative examples is equipped with 7 relatively independent compartments in the hori zontal direction, which are recorded as compartments 1 to 7 ; among them, the mixed leaching area is chambers 1 to 2 , the stable leaching area is compartments 3 to 5 , and the adj ustment leaching area is compartments 6 to 7 .

[0041] I f no speci fic techniques or conditions are speci fied in the following embodiments , the procedures are carried out in accordance with the techniques or conditions described in the literature in the field or in accordance with the instructions ; i f no manufacturer is speci fied for the reagents or instruments used, they are all conventional products that can be obtained commercially.

[0042] Example 1

[0043] A method for gradient continuous leaching of laterite nickel ore comprises the following steps:

[0044] ( 1 ) The temperature of the mixed leaching zone is controlled within 180-190°C, and the duration of the mixed leaching zone is 12 min, and the amount of sulfuric acid added to the mixed leaching zone is 200kg / t dry ore.

[0045] (2) The temperature of the stable leaching zone is controlled within 250-255°C, the duration is 30min, and the amount of sulfuric acid added is 80kg / t dry ore.

[0046] (3) The temperature of the adjustment leaching zone is controlled within 225-230°C, the duration is 15min; manganese slag is added, and the mass ratio of its addition amount to sulfuric acid is 1:60.

[0047] (4) After being discharged from the adjustment leaching zone and cooled to below 100°C, it enters the subsequent process.

[0048] Example 2

[0049] Different from Embodiment 1, the temperature and duration of each zone in the gradient continuous leaching process of laterite nickel ore provided in this embodiment are different, as follows:

[0050] The temperature of the mixed leaching zone is controlled within 200~210°C, and the duration of the mixed leaching zone is 15min;

[0051] The temperature of the stable leaching zone is controlled within 255~260°C, and the duration is 25min;

[0052] The temperature of the adjustment leaching zone is controlled within 215~220°C, and the duration is 20 min.

[0053] Example 3

[0054] Different from Embodiment 1, the temperature and duration of each zone in the gradient continuous leaching process of laterite nickel ore provided in this embodiment are different, as follows:

[0055] The temperature of the mixed leaching zone is controlled within 190~200°C, and the duration of the mixed leaching zone is 10 min;

[0056] The temperature of the stable leaching zone is controlled within 240~250°C, and the duration is 40 min;

[0057] The temperature of the adjustment leaching zone is controlled within 220~225°C, and the duration is 25min. Comparative Example 1

[0058] Different from Embodiment 1, in the high-pressure acid leaching process for laterite nickel ore provided in this example, no manganese slag is added in Step 3, and the rest is the same as in Embodiment 1.

[0059] Comparative Example 2

[0060] Different from Example 1, in the high-pressure acid leaching process for laterite nickel ore provided in this example, the reaction temperatures of the fusion leaching zone, the stability leaching zone and the adjustment leaching zone are consistent, that is, they are all controlled within 225-230°C.

[0061] Comparative Example 3

[0062] Different from Embodiment 1, in the high-pressure acid leaching process for laterite nickel ore provided in this example, the adjustment leaching zone in step (3) is not subjected to cooling treatment, that is, its temperature is the same as the temperature of the stable leaching zone, and the rest is consistent with Embodiment 1.

[0063] Comparative Example 4

[0064] Different from Embodiment 1, in the high-pressure acid leaching process for laterite nickel ore provided in this example, the temperature of the mixed leaching zone is adjusted and controlled within 230~235°C, and the rest is consistent with Embodiment 1.

[0065] The recovery rates of Fe, Al, Ni, Co and Mn and the discharge pH values in Embodiments 1-3 and Comparative Examples 1-2 were respectively tested, and the results are shown in Table 2.

[0066] Table 2 Recovery rates of each element

[0067] It can be seen from Table 2 that: relative to the embodiments, in Comparative Example 1, under the condition that the manganese slag is not recycled in the adj ustment leaching zone , the pH of the slurry out of the autoclave is reduced, and the recovery rates of Ni , Co and Mn are slightly reduced, especially Mn; while in Comparative Example 2 , after lowering the temperature of the stable leaching zone , the recovery rates of Ni , Co and Mn metals are reduced, and the recovery rate of Al is relatively high .

[0068] Using the process conditions in Example 1 and Comparative Examples 2-4 respectively, the autoclave was shut down after continuous operation for 30 days to investigate the scaling condition on the inner wall of the autoclave . The results are shown in Table 3 .

[0069] Table 3 Analysis of scales of the autoclave under various conditions

[0070] In summary, the method of the present invention can ef fectively inhibit the leaching of Fe and Al , and since Fe and Al are hydrolyzed in di f ferent stability leaching zones to avoid scaling, the resulting precipitated slag is convenient for further utili zation; in addition, the recovery rate of Ni and Co is further improved, especially Mn . Due to the reaction system of acid and manganese slag in the adj ustment leaching area, the recovery rate of manganese has been signi ficantly improved .

[0071] It should be noted that the above embodiments are only part of the embodiments of the present invention rather than all the embodiments , and are only used to illustrate the technical scheme of the present invention rather than to limit it ; based on the embodiments in the present invention, all other embodiments obtained by those of ordinary skill in the art without creative labor are within the scope of protection of the present invention .

Claims

What Is Claimed Is1. A method for gradient continuous leaching of laterite nickel ore, characterized in that it comprises the following steps:Along the material conveying direction, the high pressure acid leaching process is sequentially divided into a mixed leaching zone, a stable leaching zone and an adjustment leaching zone, and acid is added to both the mixed leaching zone and the stable leaching zone;The temperature of the mixed leaching zone is T1 and the duration is tl, the temperature of the stable leaching zone is T2 and the duration is t2, the temperature of the adjustment leaching zone is T3 and the duration is t3; wherein, T2>T3>T1, and t2>t3>tl.

2. The method for gradient continuous leaching of laterite nickel ore according to claim 1, characterized in that the amount of acid added to the stable leaching zone is less than or equal to the amount of acid added to the mixed leaching zone.

3. The method for gradient continuous leaching of laterite nickel ore according to claim 2, characterized in that the acid is sulfuric acid.

4. The method for gradient continuous leaching of laterite nickel ore according to claim 3 is characterized in that, in the mixed leaching zone, the amount of acid added is 200-300 kg / 1 dry ore; in the stable leaching zone, the amount of acid added is 50-100 kg / t dry ore.

5. The method for gradient continuous leaching of laterite nickel ore according to claim 1, characterized in that the temperature of the mixed leaching zone is 180~210°C, the temperature of the stable leaching zone is 240~260°C, and the temperature of the adjustment leaching zone is 210~230°C.

6. The method for gradient continuous leaching of laterite nickel ore according to claim 4, characterized in that the tl is 10 to 15 min, the t2 is 25 to 40 min, and the t3 is 15 to 25 min.

7. The method for gradient continuous leaching of laterite nickel ore according to claim 1 is characterized in that the adjustment leaching zone is supplemented with ore, and the ore is specifically at least one of manganese slag, magnesian laterite nickel ore and low-aluminum laterite nickel ore.

8. The method for gradient continuous leaching of laterite nickel ore according to claim 1, characterized in that the mixed leaching zone is the front compartment of the autoclave the stability leaching zone is the middle compartment of the autoclave, and the adjustment leaching zone is the rear compartment of the autoclave.

9. The method for gradient continuous leaching of laterite nickel ore according to claim 8, characterized in that the pressure in the autoclave is 2~6.5 MPa.

10. The method for gradient continuous leaching of laterite nickel ore according to claim 8 is characterized in that it also includes the following steps: after the material is discharged from the adjustment leaching zone, it is flash-evaporated and cooled to below 100°C.

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