A gradient continuous leaching method for laterite nickel ore

Abstract

The present invention provides a gradient continuous leaching method for laterite nickel ore, comprising the following steps: along the material transmission direction of the laterite nickel ore, the laterite nickel ore passes through a fusion leaching zone, a stability leaching zone, and an adjustment leaching zone in sequence for continuous leaching; acid is added to both the fusion leaching zone and the stability leaching zone; the temperature of the fusion leaching zone is T1 and the reaction time is t1, the temperature of the stability leaching zone is T2 and the reaction time is t2, and the temperature of the adjustment leaching zone is T3 and the reaction time is t3; wherein T2>T3≥T1, and t2>t3>t1. The present invention performs zoning treatment on the high-pressure acid leaching process, improves the one-time leaching efficiency, slows down scaling, thereby achieving the goal of suppressing further leaching of Fe and Al while reducing scaling in the reactor, and can fully utilize the acid and waste residue to achieve efficient leaching of nickel, cobalt and manganese, and the waste heat generated after the slurry is discharged from the adjustment leaching zone can be recycled.

Description

Technical Field

[0001] The invention relates to the technical field of metallurgy, and in particular to a gradient continuous leaching method for laterite nickel ore. Background Art

[0002] Nickel, a key metal with excellent mechanical strength, ductility, and chemical stability, is an indispensable raw material for stainless steel, catalysts, and new energy batteries, playing a crucial role in industrial production. Existing research shows that global nickel reserves are approximately 95 million tons, with a high concentration of resources. Laterite nickel deposits are primarily distributed in the tropical and subtropical regions of the Pacific Rim within 30° north and south latitude.

[0003] The wet process is capable of processing complex, low-grade nickel ores, with low energy consumption, low costs, and minimal pollution. In recent years, with the growing demand for nickel in stainless steel and new energy applications, the wet process for extracting nickel from laterite nickel ore has gained increasing application. Depending on the pressure used during the leaching process, the wet process can be categorized as atmospheric leaching or pressure leaching. Depending on the leaching medium, it can be further divided into ammonia leaching and acid leaching. Currently, the majority of international laterite nickel ore development projects utilize the wet process of pressure acid leaching.

[0004] Pressure acid leaching (PAL) is a highly selective process for extracting the valuable metal elements nickel and cobalt from laterite nickel ore under high-temperature and high-pressure conditions. While PAL offers the advantage of higher nickel and cobalt leaching rates compared to other wet processes, these rates still require further improvement. Furthermore, PAL presents challenges such as difficulty in disposing of leached residue, rapid accumulation of leached residue stockpiles, and the tendency for autoclave scaling. Summary of the Invention

[0005] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a gradient continuous leaching method for laterite nickel ore, so as to suppress the leaching of impurities such as iron and aluminum and improve the leaching rate of nickel, cobalt and manganese, and realize the partitioned precipitation of aluminum precipitate slag and iron precipitate slag while effectively solving or alleviating the problem of scaling in the reactor.

[0006] To achieve this object, the present invention adopts the following technical solutions:

[0007] The present invention provides a gradient continuous leaching method for laterite nickel ore, comprising the following steps: along the material transmission direction of the laterite nickel ore, the laterite nickel ore sequentially passes through a fusion leaching zone, a stability leaching zone and an adjustment leaching zone for continuous leaching; acid solution is added to both the fusion leaching zone and the stability leaching zone; the temperature of the fusion leaching zone is T1 and the reaction time is t1, the temperature of the stability leaching zone is T2 and the reaction time is t2, and the temperature of the adjustment leaching zone is T3 and the reaction time is t3; wherein, T2>T3≥T1, and t2>t3>t1.

[0008] The present invention innovatively divides the high-pressure leaching process into three leaching zones, namely the fusion leaching zone, the stability leaching zone and the adjustment leaching zone. Along the material transmission direction, the temperature gradually rises and maintains a high temperature in the stability leaching zone, and then reduces the temperature in the adjustment leaching zone; wherein, the fusion leaching zone realizes full mixing of materials, reduces mutations, and slows down scaling; the stability leaching zone realizes stable and efficient leaching of laterite nickel ore; the adjustment leaching zone performs buffering leaching, reduces the load of the discharge on the downstream device, improves the one-time leaching efficiency, and slows down scaling, thereby achieving the goal of reducing the scaling of the high-pressure reactor while inhibiting the further leaching of Fe and Al, and making full use of the acid solution and waste residue to achieve efficient leaching of nickel, cobalt and manganese. Specifically, compared with other elements, Fe in the material can be leached faster. The present invention sets a fusion leaching zone and adjusts its temperature conditions so that the leached Fe ions are more easily hydrolyzed in the fusion leaching zone; Fe is preferentially hydrolyzed in the low temperature environment of the fusion leaching zone and forms iron-containing precipitate slag, and the iron content in the iron-containing precipitate slag is high. In the high-temperature stability leaching zone, Al hydrolysis is the primary process. Lowering the temperature in the adjustable leaching zone inhibits further Al hydrolysis, reducing the load on downstream equipment and improving one-shot leaching efficiency. By controlling the reaction temperature and time, the simultaneous hydrolysis and mixed deposition of Fe and Al in the reactor are effectively avoided, effectively alleviating scaling within the reactor. The hydrolysis of Fe and Al releases some acid.

[0009] It is worth noting that the present invention can not only reduce scaling, but also realize regional enrichment of iron slag and aluminum slag, wherein the precipitated slag with high iron content is mainly in the fusion leaching zone, and the precipitated slag containing aluminum is mainly in the stability leaching zone. When the machine is shut down for descaling, the iron-containing precipitated slag and the aluminum-containing precipitated slag can be directly removed separately and the iron and aluminum resources can be recovered separately. The difficulty of subsequent recycling and processing is low, and resource utilization can be better realized.

[0010] Furthermore, the reaction time needs to be matched with the temperature so that the leaching effect of each area can be more accurately controlled and scaling of the reactor can be avoided.

[0011] The reaction time in the present invention is essentially the residence time.

[0012] Preferably, the acid solution is sulfuric acid.

[0013] Preferably, the amount of acid added to the stability leaching zone is less than or equal to the amount of acid added to the fusion leaching zone.

[0014] Preferably, the amount of acid added to the stability leaching zone is 100-200 kg / t dry ore less than the amount of acid added to the fusion leaching zone, for example, it can be 100 kg / t dry ore, 112 kg / t dry ore, 123 kg / t dry ore, 134 kg / t dry ore, 145 kg / t dry ore, 156 kg / t dry ore, 167 kg / t dry ore, 178 kg / t dry ore, 189 kg / t dry ore or 200 kg / t dry ore, etc., but is not limited to the listed values, and other values ​​not listed within this range are also applicable.

[0015] The present invention preferably controls the relationship between the amount of acid added in the stability leaching zone and the amount of acid added in the fusion leaching zone within the above range, which can better achieve only iron hydrolysis and precipitation in the fusion leaching zone, while increasing and decreasing the amount of addition in the stability leaching zone can better achieve efficient leaching of nickel, cobalt and manganese.

[0016] Preferably, in the fusion leaching zone, the amount of acid added is 200-300 kg / t dry ore, for example, it can be 200 kg / t dry ore, 212 kg / t dry ore, 223 kg / t dry ore, 234 kg / t dry ore, 245 kg / t dry ore, 256 kg / t dry ore, 267 kg / t dry ore, 278 kg / t dry ore, 289 kg / t dry ore or 300 kg / t dry ore, etc., but is not limited to the listed values, and other values ​​not listed within the range are also applicable.

[0017] Preferably, in the stability leaching zone, the amount of acid added is 50-100 kg / t dry ore, for example, 50 kg / t dry ore, 56 kg / t dry ore, 62 kg / t dry ore, 67 kg / t dry ore, 73 kg / t dry ore, 78 kg / t dry ore, 84 kg / t dry ore, 89 kg / t dry ore, 95 kg / t dry ore or 100 kg / t dry ore, etc., but is not limited to the listed values, and other values ​​not listed within this range are also applicable.

[0018] Preferably, the temperature difference between the temperature T2 of the stability leaching zone and the temperature T3 of the adjustment leaching zone is 10 to 50°C, for example, it can be 10°C, 15°C, 19°C, 24°C, 28°C, 33°C, 37°C, 42°C, 46°C or 50°C, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0019] Preferably, the temperature difference between the temperature T3 of the adjustable leaching zone and the temperature T1 of the fusion leaching zone is 0 to 40°C, for example, it can be 0°C, 5°C, 9°C, 14°C, 18°C, 23°C, 27°C, 32°C, 36°C or 40°C, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0020] Preferably, the temperature T1 of the fusion leaching zone is 180-210°C, for example, it can be 180°C, 184°C, 187°C, 190°C, 194°C, 197°C, 200°C, 204°C, 207°C or 210°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0021] In the present invention, the temperature T1 of the fusion leaching zone is preferably controlled within the above range, which can match the reaction time t1, thereby better reducing scaling and increasing the leaching rate of nickel, cobalt and manganese while inhibiting the leaching of Al and Mn.

[0022] Preferably, the temperature T2 of the stability leaching zone is 240-260°C, for example, it can be 240°C, 243°C, 245°C, 247°C, 249°C, 252°C, 254°C, 256°C, 258°C or 260°C, but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0023] Preferably, the temperature T3 of the adjustable leaching zone is 190-230°C, for example, it can be 190°C, 195°C, 200°C, 205°C, 210°C, 213°C, 215°C, 217°C, 219°C, 222°C, 224°C, 226°C, 228°C or 230°C, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0024] The present invention preferably controls the temperature ranges of the fusion leaching zone, the stability leaching zone and the adjustment leaching zone within the above ranges, which can better avoid scaling of the reactor while improving the leaching rate of nickel, cobalt and manganese.

[0025] Preferably, the time difference between t2 and t3 is 10 to 15 minutes, for example, it can be 10 minutes, 10.6 minutes, 11.2 minutes, 11.7 minutes, 12.3 minutes, 12.8 minutes, 13.4 minutes, 13.9 minutes, 14.5 minutes or 15 minutes, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0026] Preferably, the time difference between t3 and t1 is 5 to 10 minutes, for example, it can be 5 minutes, 5.6 minutes, 6.2 minutes, 6.7 minutes, 7.3 minutes, 7.8 minutes, 8.4 minutes, 8.9 minutes, 9.5 minutes or 10 minutes, but is not limited to the listed values. Other values ​​not listed in this range are also applicable.

[0027] Preferably, the t1 is 10 to 15 min, for example, it can be 10 min, 10.6 min, 11.2 min, 11.7 min, 12.3 min, 12.8 min, 13.4 min, 13.9 min, 14.5 min or 15 min, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0028] The present invention preferably controls the reaction time t1 of the fusion leaching zone within the above range, which can better control the leaching effect of nickel, cobalt and manganese in the fusion leaching zone and effectively inhibit the leaching of Al and Fe, thereby better reducing scaling in the fusion leaching zone and the stability leaching zone.

[0029] Preferably, the t2 is 25 to 40 min, for example, it can be 25 min, 27 min, 29 min, 30 min, 32 min, 34 min, 35 min, 37 min, 39 min or 40 min, but is not limited to the listed values. Other values ​​not listed within the range are also applicable.

[0030] Preferably, the t3 is 15 to 25 min, for example, it can be 15 min, 17 min, 18 min, 19 min, 20 min, 21 min, 22 min, 23 min, 24 min or 25 min, but is not limited to the listed values, and other unlisted values ​​within the range are also applicable.

[0031] Preferably, supplementary ore is added to the adjustable leaching zone, and preferably the supplementary ore is a manganese-containing ore.

[0032] According to the acid content and temperature conditions of the adjustable leaching zone, the present invention finds that adding an appropriate amount of manganese-containing ore to the adjustable leaching zone can, on the one hand, fully utilize the released acid for leaching, and on the other hand, further increase the content of valuable metal elements (especially manganese) in the leachate, thereby achieving re-enrichment. When the manganese-containing ore is used to precipitate nickel, cobalt and manganese with alkaline solution to obtain manganese slag, not only the manganese leaching rate is effectively improved, but also the reuse of waste materials is achieved.

[0033] Preferably, the supplementary ore comprises any one or a combination of at least two of manganese slag, magnesian laterite nickel ore, or low-aluminum laterite nickel ore, wherein typical but non-limiting combinations include a combination of manganese slag and magnesian laterite nickel ore, a combination of low-aluminum laterite nickel ore and magnesian laterite nickel ore, and a combination of manganese slag and low-aluminum laterite nickel ore. The manganese slag may be slag obtained by concentrating and filtering the barren liquid produced after precipitating nickel, cobalt, and manganese in alkaline solution during the acid leaching process of laterite nickel ore.

[0034] Preferably, the amount of the supplementary ore added is 1.0 to 2.0 wt% of the total amount of acid added to the adjustment leaching zone and the fusion inlet and outlet zone, for example, it can be 1.0 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%, 1.6 wt%, 1.7 wt%, 1.8 wt%, 1.9 wt% or 2.0 wt%, etc., but is not limited to the listed values, and other unlisted values ​​within this range are also applicable.

[0035] Preferably, the continuous leaching is carried out in a reactor.

[0036] The fusion leaching zone is the front chamber of the reactor, the stability leaching zone is the middle chamber of the reactor, and the adjustment leaching zone is the rear chamber of the reactor.

[0037] Preferably, the continuous leaching pressure is 2.0 to 6.5 MPa, for example, it can be 2 MPa, 2.5 MPa, 3 MPa, 3.5 MPa, 4 MPa, 4.5 MPa, 5 MPa, 5.5 MPa, 6 MPa or 6.5 MPa, but is not limited to the listed values. Other values ​​not listed within this range are also applicable.

[0038] Preferably, the reactor is heated and pressurized by introducing high-temperature steam.

[0039] The present invention can heat and pressurize various areas of the reactor by introducing high-temperature steam, thereby achieving hot and cold fusion between the high-temperature steam and the leaching slurry and sufficient mixing. The pressure of the high-pressure reactor is positively correlated with the temperature of the area in which it is located. The pressure can be set based on the temperature adaptability of each area of ​​the high-pressure reactor set above, and no specific limitation is made here.

[0040] Preferably, the process further comprises the following steps: cooling the leached material discharged from the adjustable leaching zone by flash evaporation, and the waste heat generated after the slurry is discharged from the adjustable leaching zone can be recycled.

[0041] The final temperature of the flash cooling is ≤100°C, for example, it can be 100°C, 99°C, 98°C, 90°C, 80°C, 70°C or 60°C.

[0042] Compared with the prior art, the present invention has at least the following beneficial effects:

[0043] (1) The gradient continuous leaching method of laterite nickel ore provided by the present invention can control the hydrolysis and leaching of different elements in different zones, thereby avoiding scaling of the reactor. Under preferred conditions, no scaling occurs in the adjustment leaching zone after 30 days of continuous operation, while only trace scaling occurs in the fusion leaching zone and the stability leaching zone. In addition, the fusion leaching zone produces iron slag, and the stability leaching zone produces aluminum and vanadium, both of which can be subsequently utilized as resources.

[0044] (2) The gradient continuous leaching method for laterite nickel ore provided by the present invention significantly improves the leaching rate of nickel, cobalt and manganese by performing high-pressure acid leaching in different zones. Under preferred conditions, the leaching rate of Ni is above 95%, the leaching rate of Co is above 98%, and the leaching rate of Mn is above 90%. The pH value of the discharge is above 1.4, and the acid concentration in the discharge is low. In addition, the gradient continuous leaching method of the present invention can reduce the leaching rate of Fe and Al in the leachate. Under preferred conditions, the leaching rate of Fe is within 2%, and the leaching rate of Al is within 26%.

[0045] (3) The gradient continuous leaching method of laterite nickel ore provided by the present invention preferably supplements the ore in the adjustable leaching zone, which can make full use of the acid produced by the hydrolysis of iron and aluminum, increase the content of valuable metals in the leachate, and achieve secondary enrichment. Moreover, when the manganese-containing ore is used to precipitate nickel, cobalt and manganese with alkaline solution to obtain the manganese slag, not only the manganese leaching rate is effectively improved, but also the waste material can be reused. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 The present invention provides a process flow chart of a gradient continuous leaching method for laterite nickel ore. DETAILED DESCRIPTION

[0047] For the convenience of understanding the present invention, the present invention is given below with examples. It should be understood by those skilled in the art that the examples are only for the purpose of helping to understand the present invention and should not be regarded as specific limitations of the present invention.

[0048] Traditional high-pressure acid leaching processes for laterite nickel ore involve acid leaching at a fixed temperature, typically using material pretreatment (such as mixing sodium sulfate and / or potassium sulfate into the material), adjusting the acid concentration, and adding additives (such as Mg(NO3)2) to suppress Fe and Al leaching and achieve selective leaching of nickel and cobalt. To address this issue, the present invention innovatively partitions the high-pressure leaching process, suppressing Fe and Al leaching while reducing scaling in the autoclave. It also fully utilizes the acid and waste residue (or low-grade laterite nickel ore) to achieve efficient leaching of nickel, cobalt, and manganese.

[0049] In order to achieve the above technical effects, the present invention adopts the following technical solutions:

[0050] like Figure 1 As shown, the gradient continuous leaching method of laterite nickel ore provided by the present invention comprises the following steps:

[0051] Along the material transmission direction of the laterite nickel ore, the laterite nickel ore passes through the fusion leaching zone, the stability leaching zone and the adjustment leaching zone in sequence for continuous leaching;

[0052] Acid is added to both the fusion leaching zone and the stability leaching zone, and preferably, the amount of acid added to the stability leaching zone is less than or equal to the amount of acid added to the fusion leaching zone;

[0053] The fusion leaching zone is the front chamber of the autoclave, the temperature of this zone is T1, and the reaction time is t1; the stability leaching zone is specifically the middle chamber of the autoclave, the temperature of this zone is T2, and the reaction time is t2; the adjustment leaching zone is the rear chamber of the autoclave, the temperature of this zone is T3, and the reaction time is t3; wherein, the temperature and reaction time of each zone simultaneously satisfy the relationship of T2>T3≥T1 and t2>t3>t1;

[0054] After the leached material discharged from the adjustable leaching area is cooled to below 100°C by flash evaporation, it can enter the subsequent stage according to the overall process flow.

[0055] During actual production, the autoclave is equipped with several relatively independent reaction chambers in a horizontal sequence. Each chamber is equipped with a stirring device. Adjacent chambers are separated by vertical partitions with through-holes for slurry overflow and diversion. It is understood that the autoclave used in the present invention has at least three chambers. The specific number of reaction chambers can be set according to actual needs and is not limited here.

[0056] It is worth noting that the present invention preferably controls the reaction time of different areas by controlling the flow rate between the fusion leaching zone, the stability leaching zone and the adjustment leaching zone.

[0057] The technical solution of the present invention will be clearly and completely described below in conjunction 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 intended to limit the present invention.

[0058] The mass percentages of various elements in the laterite nickel ore used in the following examples and comparative examples are shown in Table 1 below, in wt%.

[0059] Table 1

[0060] Ni Co Mn Fe Al <![CDATA[SiO2]]> 1.19 0.108 0.725 41.27 4.15 11.25

[0061] For the convenience of the experiment, the high-pressure reactor used in the following examples and comparative examples is provided with 7 relatively independent reaction chambers in the horizontal direction, which are respectively recorded as chambers 1 to 7; among them, the fusion leaching zone is chambers 1 to 2, the stability leaching zone is chambers 3 to 5, and the adjustment leaching zone is chambers 6 to 7.

[0062] If no specific techniques or conditions are specified in the following examples, the procedures were carried out in accordance with the techniques or conditions described in the literature in the field or in accordance with the product instructions; if no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased commercially.

[0063] Example 1

[0064] A gradient continuous leaching method for laterite nickel ore, comprising the following steps:

[0065] The crushed laterite nickel ore is added to a high-pressure reactor with an overall pressure of 4.5 MPa. The ore first enters the fusion leaching zone, and the temperature T1 of the fusion leaching zone is controlled within 200-210° C. The reaction time t1 of the fusion leaching zone is 12 minutes, and the amount of sulfuric acid (concentration of 98.5 wt%) added to the fusion leaching zone is 230 kg / t dry ore.

[0066] The material is discharged from the fusion leaching zone into the stability leaching zone, the temperature T2 of the stability leaching zone is controlled within 250-255°C, the reaction time t2 is 30min, and the amount of sulfuric acid (concentration is 98.5wt%) added is 80kg / t dry ore.

[0067] The material discharged from the stability leaching zone enters the adjustable leaching zone, the temperature T3 of the adjustable leaching zone is controlled to 225-230°C, and the reaction time t3 is 20 min; and manganese slag (manganese content is 1.5wt%) is added to the adjustable leaching zone, and the mass ratio of the amount of manganese slag added to the total amount of sulfuric acid added above (i.e., the total amount of sulfuric acid added to the fusion leaching zone and the stability leaching zone) is 1:60.

[0068] The leached material discharged from the adjustable leaching zone is cooled to below 100°C by flash evaporation and enters the subsequent stage.

[0069] Example 2

[0070] A gradient continuous leaching method for laterite nickel ore, comprising the following steps:

[0071] The crushed laterite nickel ore is added to a high-pressure reactor with an overall pressure of 2.0 MPa. The ore first enters the fusion leaching zone, and the temperature T1 of the fusion leaching zone is controlled within 170-180°C. The reaction time t1 of the fusion leaching zone is 15 minutes, and the amount of sulfuric acid (concentration of 98.5 wt%) added to the fusion leaching zone is 300 kg / t dry ore.

[0072] The material is discharged from the fusion leaching zone into the stability leaching zone, the temperature T2 of the stability leaching zone is controlled within 205-210°C, the reaction time t2 is 25min, and the amount of sulfuric acid (concentration is 98.5wt%) added is 100kg / t dry ore.

[0073] The material discharged from the stability leaching zone enters the adjustable leaching zone, the temperature T3 of the adjustable leaching zone is controlled to 190-195°C, and the reaction time t3 is 20min; and manganese slag (manganese content is 1.0wt%) is added to the adjustable leaching zone, and the mass ratio of the added amount of manganese slag to the total amount of sulfuric acid added above (i.e., the total amount of sulfuric acid added to the fusion leaching zone and the stability leaching zone) is 1:50.

[0074] The leached material discharged from the adjustable leaching zone is cooled to below 100°C by flash evaporation and enters the subsequent stage.

[0075] Example 3

[0076] A gradient continuous leaching method for laterite nickel ore, comprising the following steps:

[0077] The crushed laterite nickel ore is added to a high-pressure reactor with an overall pressure of 6.5 MPa. The ore first enters the fusion leaching zone, and the temperature T1 of the fusion leaching zone is controlled within 220-225° C. The reaction time t1 of the fusion leaching zone is 10 min, and the amount of sulfuric acid (concentration of 98.5 wt%) added to the fusion leaching zone is 200 kg / t dry ore.

[0078] The material is discharged from the fusion leaching zone into the stability leaching zone, the temperature T2 of the stability leaching zone is controlled within 260-270°C, the reaction time t2 is 40 minutes, and the amount of sulfuric acid (concentration is 98.5wt%) added is 50kg / t dry ore.

[0079] The material discharged from the stability leaching zone enters the adjustable leaching zone, the temperature T3 of the adjustable leaching zone is controlled to 220-225°C, and the reaction time t3 is 25 min; and manganese slag (manganese content is 2.0wt%) is added to the adjustable leaching zone, and the mass ratio of the amount of manganese slag added to the total amount of sulfuric acid added above (i.e., the total amount of sulfuric acid added to the fusion leaching zone and the stability leaching zone) is 1:70.

[0080] The leached material discharged from the adjustable leaching zone is cooled to below 100°C by flash evaporation and enters the subsequent stage.

[0081] Example 4

[0082] This embodiment provides a gradient continuous leaching method for laterite nickel ore. Except that no manganese slag is added in step (3), the rest of the method is the same as that of Example 1, and will not be repeated here.

[0083] Example 5

[0084] This embodiment provides a gradient continuous leaching method for laterite nickel ore. Except that the reaction time t1 in the fusion leaching zone is 17 min and still satisfies t2>t3>t1, the rest of the method is the same as that in Example 1 and will not be repeated here.

[0085] Example 6

[0086] This embodiment provides a gradient continuous leaching method for laterite nickel ore. The method is the same as that in Example 1, except that the reaction time t1 in the fusion leaching zone is 5 min and still satisfies t2>t3>t1, and thus will not be described in detail.

[0087] Example 7

[0088] This embodiment provides a gradient continuous leaching method for laterite nickel ore. Except that the temperature T1 of the fusion leaching zone is controlled within 160-170° C. and still satisfies T2>T3≥T1, the rest of the method is the same as that of Example 1 and will not be repeated here.

[0089] Example 8

[0090] This embodiment provides a gradient continuous leaching method for laterite nickel ore. Except that the temperature T1 of the fusion leaching zone is controlled at 225-230° C. and still satisfies T2>T3≥T1, the rest of the method is the same as that of Example 1 and will not be repeated here.

[0091] Example 9

[0092] This embodiment provides a gradient continuous leaching method for laterite nickel ore. The method is the same as that in Example 1 except that the amount of sulfuric acid added in the stability leaching zone is 150 kg / t dry ore, and the details are not repeated here.

[0093] Example 10

[0094] This embodiment provides a gradient continuous leaching method for laterite nickel ore. The method is the same as that in Example 1 except that the amount of sulfuric acid added in the stability leaching zone is 10 kg / t dry ore, and the details are not repeated here.

[0095] Comparative Example 1

[0096] This comparative example provides a gradient continuous leaching method for laterite nickel ore. The method is the same as Example 1 except that the reaction temperatures of the fusion leaching zone, the stability leaching zone, and the adjustment leaching zone are all controlled within a range of 225-230°C. The rest is not repeated here.

[0097] Comparative Example 2

[0098] This comparative example provides a gradient continuous leaching method for laterite nickel ore. The method is the same as Example 1 except that the reaction temperatures of the stability leaching zone and the adjustment leaching zone are both controlled to be consistent, both at 250-255°C, and the rest are not repeated here.

[0099] Comparative Example 3

[0100] This comparative example provides a gradient continuous leaching method for laterite nickel ore. The method is the same as Example 1 except that the temperature of the fusion leaching zone is adjusted to be within 231-235°C, that is, T1 is greater than T3, and the rest is not repeated here.

[0101] Comparative Example 4

[0102] This comparative example provides a gradient continuous leaching method for laterite nickel ore. Except that the reaction times t1, t2 and t3 are all 15.5 min (equally divided according to the total reaction time of Example 1), the rest of the method is the same as Example 1, and will not be repeated here.

[0103] Comparative Example 5

[0104] This comparative example provides a gradient continuous leaching method for laterite nickel ore. The method is the same as Example 1 except that sulfuric acid is no longer added to the stability leaching zone and all sulfuric acid is added to the fusion leaching zone. The details are not repeated here.

[0105] The leaching rates (in %) of Fe, Al, Ni, Co and Mn and the discharge pH values ​​in Examples 1-10 and Comparative Examples 1-5 were respectively measured. The results are shown in Table 2.

[0106] Table 1

[0107] Ni Co Mn Fe Al Discharge pH Example 1 96.4 98.8 90.3 1.95 25.8 1.4 Example 2 95.5 98.1 90.5 1.84 24.7 1.4 Example 3 95.4 98.0 90.1 1.55 23.5 1.5 Example 4 95.4 95.9 88.5 2.08 28.6 0.7 Example 5 96.0 98.5 90.2 2.87 35.4 1.1 Example 6 95.4 98.2 90.0 2.89 34.8 1.1 Example 7 94.6 95.2 89.2 2.01 26.8 1.2 Example 8 96.3 98.8 92.3 1.58 26.4 1.4 Example 9 97.8 99.5 93.4 4.05 42.1 0.5 Example 10 94.3 88.6 89.5 1.79 24.3 1.5 Comparative Example 1 90.1 90.2 83.6 4.02 49.3 0.9 Comparative Example 2 95.5 97.5 90.0 1.95 26.8 1.1 Comparative Example 3 95.4 97.2 90.1 3.52 36.7 0.8 Comparative Example 4 94.2 96.8 89.5 2.45 34.6 0.8 Comparative Example 5 95.6 97.2 89.3 1.96 28.7 1.0

[0108] Using the process conditions of Example 1, Examples 4-10, and Comparative Examples 1-5, the autoclave was shut down after 30 days of continuous operation to investigate the scaling condition on the inner wall of the autoclave. The results are shown in Table 3. If scaling is distributed on the stirring blades, it will cause stirring shaking, which has a significant impact on production.

[0109] Table 3

[0110]

[0111]

[0112] As shown in Tables 2-3, the gradient continuous leaching method for laterite nickel ore provided in Examples 1-3 can achieve efficient leaching of nickel, cobalt, and manganese, and has a high discharge pH. The leaching rate of Ni is above 95%, the leaching rate of Co is above 98%, and the leaching rate of Mn is above 90%, and the discharge pH is above 1.4. Furthermore, in Examples 1-3, scaling is minimal after 30 days of continuous operation. Furthermore, the gradient continuous leaching method of the present invention can reduce the leaching rate of Fe and Al in the leachate, with the leaching rate of Fe being within 2% and the leaching rate of Al being within 26%.

[0113] Compared with Example 1, in Example 4, under the condition that the manganese slag was not recycled in the adjustable leaching zone, the pH of the slurry out of the autoclave was reduced, and the leaching rates of Ni, Co and Mn were slightly reduced, especially Mn. This shows that the present invention preferably adds manganese slag in the adjustable leaching zone, which can further utilize the acid generated by the hydrolysis of Fe and Al to make the pH of the final discharge material above 1.0.

[0114] Compared with Example 1, the reaction time t1 in Example 5 is relatively long, and the reaction time t1 in Example 6 is relatively short, which ultimately leads to increased iron and aluminum leaching in Example 5, and iron slag and aluminum slag appear simultaneously in the scaling in the fusion leaching zone, and the subsequent secondary utilization of the iron slag and aluminum slag is relatively complicated; while in Example 6, the nickel and cobalt leaching rate is reduced, and the scaling generated in the stability leaching zone contains iron slag and aluminum slag at the same time, and the subsequent secondary utilization is relatively complicated. This shows that the present invention preferably controls the reaction time t1 within a reasonable range, which can significantly improve the leaching effect and avoid scaling at the same time, and is more conducive to the secondary utilization of the structure.

[0115] Compared with Example 1, the temperature T1 of the fusion leaching zone in Example 7 is relatively low, and the temperature T1 of the fusion leaching zone in Example 8 is relatively high, which ultimately leads to a decrease in the nickel and cobalt leaching rate in Example 7. Although the leaching rate can be maintained in Example 8, the leaching temperature is high, the energy consumption is high, and scaling is more likely to occur at high temperatures. This shows that the present invention preferably controls the temperature T1 of the fusion leaching zone within a reasonable range, which can significantly improve the leaching effect and avoid scaling at the same time.

[0116] A comprehensive comparison of Example 1 and Examples 9 to 10 shows that the amount of sulfuric acid added to the stability leaching zone has a great influence on the scaling phenomenon in the stability leaching zone and the leaching efficiency of nickel, cobalt and manganese. The present invention preferably controls the amount of sulfuric acid added to the stability leaching zone within a reasonable range, which can better improve the leaching effect and effectively reduce scaling.

[0117] By comparing Example 1 with Comparative Examples 1 to 3, it can be seen that when the leaching temperature does not satisfy T2>T3≥T1, a large amount of scaling is very likely to occur in the reactor, and the leaching rates of nickel, cobalt and manganese in Comparative Examples 1 to 5 are all reduced. The reaction temperatures of the fusion leaching zone, the stability leaching zone and the adjustment leaching zone in Comparative Example 1 are consistent, resulting in a significant increase in the leaching rates of Fe and Al; the temperature of the fusion leaching zone in Comparative Example 3 is adjusted and controlled within 231-235°C, that is, T1 is greater than T3, which ultimately leads to a significant increase in the leaching rates of Fe and Al, bringing difficulties to the subsequent impurity removal of the nickel, cobalt and manganese solution; this shows that the present invention can effectively inhibit the leaching of Fe and Al by controlling the temperature relationship of the fusion leaching zone, the stability leaching zone and the adjustment leaching zone within a reasonable range, thereby avoiding the generation of a large amount of scaling, which is of great significance for industrial production.

[0118] By comparing Example 1 and Comparative Example 4, it can be seen that the residence reaction time in each zone in Comparative Example 4 is the same, resulting in a large amount of scaling in the fusion leaching zone, and the leaching rate of Fe and Al is significantly increased, which brings difficulties to the subsequent impurity removal of the nickel-cobalt-manganese solution. This shows that the temperature zones in the present invention need to match the residence reaction time in order to improve the leaching efficiency and reduce scaling.

[0119] Comparing Example 1 and Comparative Example 5, it can be seen that in Comparative Example 5, all sulfuric acid is added only in the fusion leaching zone, which easily leads to a large amount of scaling in both the fusion leaching zone and the stability leaching zone.

[0120] In summary, the method of the present invention can effectively inhibit the leaching of Fe and Al, and since Fe and Al are hydrolyzed in leaching zones with different stability, scaling is avoided, and the Fe-containing precipitate slag and Al-containing precipitate slag obtained respectively are convenient for further utilization; in addition, the leaching rate of nickel and cobalt is further improved, especially manganese. Thanks to the reaction system of the acid solution and manganese slag in the adjustable leaching zone, the leaching rate of manganese is significantly improved.

[0121] The present invention uses the above-described embodiments to illustrate the detailed features of the present invention. However, the present invention is not limited to the above-described detailed features, which does not mean that the present invention must rely on the above-described detailed features to be implemented. Those skilled in the art should understand that any improvements to the present invention, equivalent replacements for the selected technical features of the present invention, additions to auxiliary technical features, and selections of specific methods, etc., fall within the scope of protection and disclosure of the present invention.

Claims

1. A gradient continuous leaching method for laterite nickel ore, characterized in that: The following steps are involved: Along the material transmission direction of the laterite nickel ore, the laterite nickel ore passes through the fusion leaching zone, the stability leaching zone and the adjustment leaching zone in sequence for continuous leaching; acid solution is added to the fusion leaching zone and the stability leaching zone; The temperature of the fusion leaching zone is T1 and the reaction time is t1, the temperature of the stability leaching zone is T2 and the reaction time is t2, and the temperature of the adjustment leaching zone is T3 and the reaction time is t3; wherein T2>T3≥T1, and t2>t3>t1; The amount of acid added to the stability leaching zone is 100-200 kg / t dry ore less than that to the fusion leaching zone; The temperature difference between the temperature T2 of the stability leaching zone and the temperature T3 of the adjustment leaching zone is 10-50°C; The temperature difference between the temperature T3 of the adjustable leaching zone and the temperature T1 of the fusion leaching zone is 0-40°C; The temperature T1 of the fusion leaching zone is 170-240°C; The time difference between t2 and t3 is 10-15 minutes; The time difference between t3 and t1 is 5 to 10 minutes; The t1 is 10-15 min.

2. The gradient continuous leaching method of laterite nickel ore according to claim 1, wherein The acid solution is sulfuric acid.

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

4. The gradient continuous leaching method of laterite nickel ore according to claim 1, characterized in that: The temperature T2 of the stability leaching zone is 205-270°C; The temperature T3 of the adjustable leaching zone is 190-230°C.

5. The gradient continuous leaching method of laterite nickel ore according to claim 4, characterized in that: The t2 is 25~40min.

6. The gradient continuous leaching method of laterite nickel ore according to claim 1, characterized in that: The t3 is 15 to 25 minutes.

7. The gradient continuous leaching method of laterite nickel ore according to claim 1, characterized in that: Adding supplementary mineral material to the adjustable leaching zone; The supplementary ore comprises any one of manganese slag, magnesian laterite nickel ore or low-aluminum laterite nickel ore, or a combination of at least two thereof; The amount of the supplementary ore added is 1.0-2.0 wt % of the total amount of acid added to the adjustment leaching zone and the fusion leaching zone.

8. The gradient continuous leaching method of laterite nickel ore according to claim 1, characterized in that: The continuous leaching is carried out in a reactor; The fusion leaching zone is the front chamber of the reactor, the stability leaching zone is the middle chamber of the reactor, and the adjustment leaching zone is the rear chamber of the reactor.

9. The gradient continuous leaching method of laterite nickel ore according to claim 8, characterized in that: The continuous leaching pressure is 2.0-6.5 MPa.

10. The gradient continuous leaching method of laterite nickel ore according to claim 8, characterized in that: The following steps are also included: The leached material discharged from the adjustable leaching zone is cooled by flash evaporation; The final temperature of the flash cooling is ≤100°C.

Images