A multi-stage combined leaching method for ultra-low grade laterite nickel ore

Abstract

The invention provides a multi-stage combined leaching method for ultra-low grade laterite nickel ore, including: firstly, the raw laterite nickel ore slurry is treated by high pressure acid leaching to obtain the high pressure leaching tailings containing iron, aluminum and magnesium and the high pressure leaching solution containing nickel, cobalt and manganese. The mass percentage of nickel in the raw laterite nickel ore is less than 1.0%; Secondly, the high pressure leaching solution, laterite nickel ore slurry and acid solution were mixed to obtain the mixed solution, and the mixed solution was subjected to multi-stage atmospheric pressure leaching treatment, after concentration treatment, the final concentrated atmospheric pressure leaching solution and the final concentrated atmospheric pressure leaching slurry with the same concentration as the raw laterite nickel ore slurry. Finally, the final concentrated atmospheric pressure leaching solution and high pressure leaching tail residue were successively recycled leaching, multi-stage pre-neutralization, counter-current decantation washing, Fe / Al / Cr removal and MHP precipitation to obtain nickel and cobalt hydroxide products. the invention can effectively restrain the scaling rate of conventional high pressure acid leaching treatment and prolong the production cycle.

Description

[0001] Description

[0002] A MULTI-STAGE COMBINED LEACHING METHOD FOR ULTRA-LOW GRADE

[0003] LATERITE NICKEL ORE

[0004] Technical Field

[0005] The invention relates to the field of metallurgical technology, in particular to a multi-stage combined leaching method of ultralow grade laterite nickel ore .

[0006] Background

[0007] With the booming development of the world ' s new energy automobile industry and the gradual depletion of high-quality nickel and cobalt resources , the industry ' s demand for Ni , Co and Mn metals in the new energy ternary materials is increasing day by day . So , the development of laterite nickel ore with large reserves but ultra-low nickel grade has gradually become a hot spot in the industry . The hydrometallurgy route of sul furic acid leaching under high temperature and high pressure is one of the mainstream smelting processes of ultra-low grade laterite nickel ore at present .

[0008] However, in the process of high pressure and high temperature leaching, due to the hydrolysis precipitation of Fe3+and Al3+metal ions , the precipitation of low solubility substances such as CaSCh and the precipitation of solid phase impurities such as SiCh in ores , scale will be formed in the wall of the high pressure reaction kettle , the foliar of the stirring oar, the inner wall of the discharge pipeline of the reaction kettle and the valve . It causes a series of problems unfavorable to production, such as blockage of discharge pipe and valve , increase of pressure drop and decrease of reactor volume . At present , the main way to deal with scaling in actual production is to regularly stop and clean the scale of the autoclave , but frequent start and stop wi ll reduce the production ef ficiency and lead to the fluctuation of the production process index . Therefore , in the process of high pressure leaching of laterite nickel ore , how to ef fectively reduce the scale rate of high pressure reaction kettle and prolong the production time is an urgent technical problem to be solved by personnel in this field .

[0009] Summary

[0010] In view of the technical problems existing in the background technology, this application provides a multi-stage combined leaching method of ultra-low grade laterite nickel ore , aiming to solve the technical problem that the production ef ficiency of nickel hydroxide and cobalt products is too low due to the rapid scaling rate of the high pressure reactor in the process of high- pressure acid leaching of the existing ultra-low grade laterite nickel ore .

[0011] The invention relates to a multi-stage combined leaching method for ultra-low grade laterite nickel ore , which is characteri zed in that :

[0012] S 10 , the raw laterite nickel ore slurry is treated by high pressure acid leaching to obtain the high pressure leaching tailings containing iron, aluminum and magnesium and the high pressure leaching solution containing nickel , cobalt and manganese The mass percentage of nickel in the raw laterite nickel ore is less than 1 . 0% .

[0013] S20 , the high pressure leaching solution, laterite nickel ore slurry and acid solution were mixed to obtain the mixed solution, and the mixed solution was subj ected to multi-stage atmospheric pressure leaching treatment , after concentration treatment , the final concentrated atmospheric pressure leaching solution and the final concentrated atmospheric pressure leaching slurry with the same concentration as the raw laterite nickel ore slurry .

[0014] S30 , the final concentrated atmospheric pressure leaching solution and high pressure leaching tail residue were successively recycled leaching, multi-stage pre-neutrali zation, countercurrent decantation washing, Fe / Al / Cr removal and MHP precipitation to obtain nickel and cobalt hydroxide products .

[0015] Among them, after the completion of the S20 step, it also includes : returning the final concentrated atmospheric leaching slurry to the S10 step for the high pressure acid leaching treatment .

[0016] Preferably, in step S10, the solid concentration of the raw slurry of laterite nickel ore is 30~ 40%, and the slurry capacity ratio is 100~200m3 / ton of metal nickel.

[0017] Preferably, in step S10, the process conditions of high pressure acid leaching treatment are: temperature 220~260°C, pressure 2.0~ 6. OMPa .

[0018] Preferably, in step S20, the mass ratio of the high-pressure leaching solution, the raw slurry of the laterite nickel ore and the acid solution is 1: ( 0.8~1 ) : (1~2) ; the acid solution includes sulfuric acid or hydrogen chloride.

[0019] Preferably, in step S20, the temperature of the multi-stage atmospheric pressure leaching treatment is 60~90°C.

[0020] Preferably, in step S20, the thickener is used to concentrate the mixed liquid after the multi-stage atmospheric leaching treatment to obtain the final concentrated atmospheric leaching liquid and the final concentrated atmospheric leaching slurry.

[0021] Preferably, in step S20, the multi-stage atmospheric leaching treatment has an atmospheric leaching order of 2~10.

[0022] Preferably, in step S30, during the cyclic leaching and multistage pre-neutralization treatment: the control temperature of the cyclic leaching is 70~90°C; The pH of multi-stage preneutralization is 0.8~2, and the neutralizing agent of multi-stage preneutralization is any one or more alkaline mixtures of lime milk, limestone, sodium hydroxide, and magnesium hydroxide.

[0023] Preferably, in step S30, the washing sequence of the countercurrent washing treatment is 3~9; The process conditions for removing iron, aluminum and chromium are as follows: the number of process stages is 2~7, the control temperature is 55~90°C, and the pH value is 2.5~5.5.

[0024] Preferably, in the nickel and cobalt hydroxide product of S30 step, the mass percentage of nickel is 30~ 40%, and the mass percentage of cobalt is 3.0~ 6.0%.

[0025] The beneficial effects of the invention are as follows: Different from the situation of the prior technology, this application combines the high pressure leaching solution obtained from the raw laterite nickel ore slurry through the high pressure acid leaching treatment , the raw laterite nickel ore slurry and the acid solution for multi-stage atmospheric pressure leaching treatment , which can avoid the scale of the high pressure leaching solution due to excessive accumulation in the high pressure reaction kettle during the high pressure acid leaching treatment . At the same time , because the reaction conditions of multi-stage atmospheric leaching treatment are more mild than that of high pressure acid leaching treatment , it can ef fectively inhibit the scale formation rate of high pressure leaching solution, thus extending the processing time of acid leaching treatment , and finally improving the production ef ficiency of nickel and cobalt hydroxide products and reducing the production cost of nickel and cobalt hydroxide products .

[0026] Brief Description Of The Drawings

[0027] In order to more clearly explain the technical solution of this application, the attached drawings used in the invention will be briefly introduced below . Obviously, the attached drawings described below are only some implementation methods of the invention . For ordinary technicians in this field, other attached drawings can be obtained according to these attached drawings without paying creative labor .

[0028] Fig . 1 shows the flow diagram of multi-stage combined leaching method of ultra-low grade laterite nickel ore provided in the application example ;

[0029] Fig . 2 shows the speci fic process diagram of the multi-stage combined leaching method of ultra-low grade laterite nickel ore provided in Example 1 of the invention .

[0030] Detailed Description Of Preferred Examples

[0031] A detailed description of the Example of the technical scheme of the application will be given below in combination with the attached drawings . The following Example is only used to more clearly explain the technical scheme of the application, so it is only used as an example , and cannot be used to limit the scope of protection of the invention .

[0032] Unless otherwise defined, all technical and scienti fic terms used herein have the same meanings as those generally understood by a skilled person in the technical field belonging to the invention; The terms used herein are only for the purpose of describing speci fic Examples and are not intended to limit the invention; The terms " including" and "having" and any variation thereof in the speci fication and claims of the invention and the above illustrated drawings are intended to cover non-exclusive inclusion .

[0033] In the description of the Examples of the invention, the technical terms " first" and " second" are only used to distinguish di f ferent obj ects and cannot be understood as indicating or implying relative importance or implicitly indicating the number, speci fic order or primary and secondary relationship of the indicated technical features . In the description of Examples of the invention, the meaning of "multi-stage" is more than two stage , unless otherwise expressly and speci fically quali fied .

[0034] A reference to "Example" in this article means that a particular feature , structure or feature described in combination with the Example may be included in at least one Example of the invention . The occurrence of the phrase in various places in the speci fication does not necessarily mean the same Example, nor is it an independent or alternative Example mutually exclusive with other Examples . It is understood explicitly and implicitly by those skilled in the technology that the Examples described herein may be combined with other Examples .

[0035] In the description of the Example of the invention, the term " and / or" is merely an association relation describing the associated obj ect , indicating that three relations can exist , such as A and / or B, and can represent the three cases : the existence of A alone , the existence of A and B simultaneously, and the existence of B alone . In addition, the character " / " in this paper generally indicates that the related obj ect is a kind of "or" relationship .

[0036] In order to solve the technical problem that the production ef ficiency of nickel hydroxide and cobalt products is too low due to the rapid scale formation rate of the high pressure reaction reactor in the process of high pressure acid leaching of the existing ultra-low grade nickel laterite , the invention provides a multi-stage combined leaching method of ultra-low grade nickel laterite , in which the reaction conditions of the above method are milder than those of the conventional high pressure acid leaching treatment . It can ef fectively inhibit the scaling rate of high pressure leaching solution, so as to delay the processing time of high pressure acid leaching treatment , and finally improve the production ef ficiency of nickel and cobalt hydroxide products and reduce the production cost of nickel and cobalt hydroxide products .

[0037] Please refer to Fig . 1 , which shows the flow diagram of multistage combined leaching method of ultra- low grade laterite nickel ore provided by the Example o f the invention . Among them, the above method includes the following steps :

[0038] S 10 , the raw slurry of laterite nickel ore was subj ected to high-pressure acid leaching treatment , and the high-pressure leaching tailings containing Fe , Al and Mg and the high-pressure leaching solution containing Ni , Co and Mn were obtained . The mass percentage of nickel in the raw laterite nickel ore was less than 1 . 0% .

[0039] Speci fically, steps S 10 also include :

[0040] Firstly, natural laterite nickel ore raw materials are provided, and ultra-low grade laterite nickel ore is obtained after beneficiation and grinding, and the mass percentage of nickel in ultra-low grade laterite nickel ore is less than 1 . 0% ; among them, the speci fic steps for gravity separation and magnetic separation .

[0041] After that , ultra-low grade laterite nickel ore was mixed with water to prepare laterite nickel ore raw slurry . The solid concentration of laterite nickel ore raw slurry was 30~ 40% , the slurry capacity ratio was 100~200m3 / ton of metal nickel , and the mass percentage of nickel in laterite nickel ore raw was less than 1 . 0% . Such concentration selection is considered to ensure suf ficient solid content to maintain the ef ficiency of subsequent reaction and treatment , as well as to ensure suitable fluidity and operability of the slurry .

[0042] Finally, the raw slurry of laterite nickel ore was treated by high pressure acid leaching, and the high pressure leaching residue containing Fe , Al and Mg and the high pressure leaching solution containing Ni, Co and Mn were obtained. Among them, the process of high pressure acid leaching of laterite nickel ore slurry includes:

[0043] (1) The raw slurry of laterite nickel ore was treated by high pressure acid leaching, and the leaching slurry was obtained by multi-stage flash evaporation heat exchange; Among them, the process conditions of high pressure acid leaching treatment are: temperature 220~260°C, pressure 2.0~ 6. OMPa, acid consumption 15-25 tons / ton of nickel.

[0044] Specifically, multi-stage flash evaporation heat exchange can achieve more efficient heat transfer, quickly improve the raw slurry temperature, meet the subsequent process requirements, at the same time, can fully recover and utilize the waste heat in the system, reduce the overall energy consumption, improve energy utilization efficiency.

[0045] (2) Solid-liquid separation of the leaching slurry was carried out to obtain the high pressure leaching tail residue containing iron, aluminum and magnesium and the high pressure leaching solution containing nickel, cobalt and manganese. Among them, after the high pressure acid leaching treatment, the Ni content, Co content and Mn content of the high pressure leaching tailings containing iron, aluminum and magnesium are less than 0.05%, 0.005% and 0.05% respectively.

[0046] Specifically, reducing agents and leaching promoters are also added in the process of high-pressure acid leaching, including lignite, ferrous sulfate, sodium sulfite, sodium bisulfite, etc., and the leaching promoters are any one or more of sodium sulfate and copper sulfate.

[0047] On the one hand, the addition of reducing agent can inhibit the transition of divalent manganese ion to high-valence state, which is conducive to the subsequent extraction of manganese. On the other hand, it is conducive to the subsequent multi-stage neutralization process, which is conducive to the transformation of hexavalent chromium into trivalent chromium, which is convenient for the removal of chromium. The introduction of leaching promoter can promote the leaching of nickel, cobalt and manganese .

[0048] S20, the high pressure leaching solution, laterite nickel ore raw slurry and acid solution are mixed to obtain the mixed solution, and the mixed solution is subj ected to multi-stage atmospheric pressure leaching treatment , after concentration treatment to obtain the final concentrated atmospheric pressure leaching solution and the final concentrated atmospheric pressure leaching slurry, the slurry concentration of the final concentrated atmospheric pressure leaching slurry is the same as that of the raw laterite nickel ore slurry .

[0049] Speci fically, steps S20 also include :

[0050] Firstly, the high pressure leaching solution, laterite nickel ore slurry and acid solution were mixed to obtain the mixed solution, and the mixed solution was processed by multi-stage atmospheric pressure leaching to obtain the mixed solution . Among them, the high pressure leaching solution, laterite nickel ore slurry and acid solution are mixed in a speci fic proportion, which is to adj ust the composition and conditions , so as to facilitate the subsequent multi-stage atmospheric leaching treatment .

[0051] Preferably, the mass ratio of high pressure leaching solution, laterite nickel ore slurry and acid solution is 1 : ( 0 . 8— 1 ) : ( 1— 2 ) ; The above mass ratio ensures that the relative content of each component is in the appropriate range , which can not only ensure the full progress of the reaction, but also achieve the economic rationality of the process .

[0052] Preferably, acidic solutions include sul furic acid or hydrogen chloride ; They are common strong acids and can ef fectively promote the related reactions . Sul furic acid has a wide range of applications and better reaction performance , and hydrogen chloride may also have speci fic advantages in some cases .

[0053] Preferably, the process conditions of each stage of multi-stage atmospheric leaching treatment are as follows : temperature 60~ 90°C, pressure 0~ 0 . 1MPa ; This temperature range is relatively mild, helping to control the reaction rate and selectivity, while also reducing equipment requirements and operating costs . The pressure is close to normal pressure , which simpli fies the process operation and equipment requirements .

[0054] Preferably, the atmospheric leaching order of multi-stage atmospheric leaching treatment is 2~ 10 . This reflects the design idea of gradually completing the leaching process through multiple stages . Multi-stage treatment can improve the ef fect and ef ficiency of leaching, make the reaction more full and thorough, and also facilitate the fine control and optimi zation of the reaction at di f ferent stages . By increasing the number of stages , the leaching degree can be gradually increased, the recovery rate of valuable metals can be increased, and the residue of impurities can be reduced . This multi-stage design provides greater flexibility and control to accommodate di f ferent ore characteristics and product requirements .

[0055] After that , the thickener is used to concentrate the mixed liquid after multi-stage atmospheric leaching treatment , and the final concentrated atmospheric leaching liquid and the final concentrated atmospheric leaching slurry are obtained . The solid concentration of the final concentrated atmospheric leaching slurry is the same as that of the raw laterite nickel ore slurry . Through the action of thickener, the slurry concentration of the final concentrated atmospheric leaching slurry can be the same as that of the raw slurry of laterite nickel ore , so that the final concentrated atmospheric leaching slurry can meet the slurry conditions of high pressure acid leaching treatment and facilitate recycling .

[0056] Speci fically, the final concentrated atmospheric leaching slurry obtained by multi-stage atmospheric leaching treatment can leach a part of iron, aluminum and magnesium . On the one hand, some Fe3+and Al3+metal ions hydrolyze and precipitate in the process of multi-stage atmospheric leaching, which causes scaling on the inner wall of the atmospheric reactor . On the other hand, another part of Fe3+and Al3+metal ions were dissolved in the final concentrated atmospheric leaching solution .

[0057] Finally, the final concentrated atmospheric leaching slurry can be returned to S 10 step to be mixed with laterite nickel ore slurry for high pressure acid leaching treatment because it meets the slurry conditions of high pressure acid leaching treatment . This recycling method helps to maintain the balance of materials in the system, so that the whole process can run continuously and stably, and reduce the process fluctuation and potential problems caused by material imbalance .

[0058] In this step, the reasons why the multi-stage atmospheric leaching treatment can inhibit scaling are as follows : 1 ) Mild reaction conditions : The reaction conditions under atmospheric pressure are relatively mild, without the drastic physical and chemical changes under high pressure environment , and some reactions and precipitation formation processes that are easy to cause scaling will slow down or not occur easily .

[0059] 2 ) Di f ference in ionic solubility : under normal pressure and low temperature , the solubil ity of some substances is relatively large , which is not easy to reach saturation and precipitate to form scale layer . However, high pressure and high temperature may change the solubility and promote the formation of scale .

[0060] 3 ) Fluid dynamics : the flow state of fluid under atmospheric pressure is relatively stable , unlike complex flow changes that may occur under high pressure , which reduces the possibility of material deposition and scaling caused by local flow anomalies .

[0061] 4 ) Reaction rate : A lower reaction rate allows more time for some potential scaling components to remain dissolved or be evenly dispersed, rather than rapid precipitation and accumulation .

[0062] 5 ) Impurity behavior : The reaction and trans formation behavior of impurities under atmospheric pressure is di f ferent from that under high pressure , and some impurity reaction pathways that may lead to scaling are inhibited or changed .

[0063] 6 ) Di f ficulty of process control : atmospheric process is relatively easier to control , and the parameter fluctuation is small , thus reducing the risk of scaling caused by process instability and process parameter disturbance .

[0064] S30 , the final concentrated atmospheric pressure leaching solution and high pressure leaching tail residue were successively recycled leaching, multi-stage pre-neutrali zation, countercurrent decantation washing, Fe / Al / Cr removal and MHP precipitation to obtain nickel and cobalt hydroxide products .

[0065] Speci fically, steps S30 also include :

[0066] Firstly, the final concentrated atmospheric leaching solution was mixed with the high pressure leaching residue and then cyclically leaching and multi-stage neutrali zation were carried out successively to obtain neutrali zation slurry . In this step, the process conditions of cyclic leaching are as follows : control the temperature of 70~ 90°C, reduce the concentration of residual acid from 30~50g / L to less than 5g / L ; The process conditions of multi-stage pre-neutrali zation treatment were as follows : pH was controlled at 0 . 8~2 by adding neutrali zing agent ; The neutrali zer is any one or more alkaline mixtures of lime milk, l imestone , sodium hydroxide and magnesium hydroxide .

[0067] Secondly, the neutrali zing s lurry obtained by cyclic leaching and multi-stage pre-neutrali zation treatment was subj ected to counter-current decantation washing to obtain the final liquid phase and slag phase , and the washing sequence of counter-current decantation washing treatment was 3- 9 . In this step, the ratio of washing water to slag phase in counter-current washing decantation treatment is ( 1-7 ) : 1 , the Ni content of the terminal liquid phase is less than O . lg / L, and the nickel content of the slag phase after neutrali zation is less than 0 . 06% ; In the process of multi-stage pre-neutrali zation treatment , an appropriate amount of neutrali zing agent is added to make the slag phase in a neutral state . After the neutrali zation treatment , the slag phase is separated by solid and liquid in the thickener to obtain the tail residue . The pH of the tail residue is 6 ~ 9 , and the tail residue mainly contains iron, and then the iron metal is recovered by reduction resting and magnetic separation . The tail residue after iron metal recovery has reached the direct discharge standard and can be directly discharged, which is in line with the production expectation of green environmental protection .

[0068] After that , the final stage liquid phase after multi -stage counter-current decantation washing was subj ected to multi-stage iron, aluminum and chromium removal , thickening and separation under the condition of adding neutrali zer and precipitation promoter . In this step, the multi-stage iron, aluminum and chromium removal is composed of the first stage of iron, aluminum and chromium removal and the second and above stage of iron, aluminum and chromium removal . The liquid phase after the former stage of iron, aluminum and chromium removal is treated in the second stage of iron, aluminum and chromium removal , the slag phase after the first stage of iron, aluminum and chromium removal is returned and subj ected to multi-stage counter-current decantation washing again, and the slag phase after the second and above stage of iron, aluminum and chromium removal is reused and recycled for cyclic leaching and multi-stage neutrali zation treatment again . Among them, the process conditions of multi-stage iron, aluminum and chromium removal are as follows: the number of stages is 2~7, the control temperature is 55~90°C, and the pH is 2.5~5.5; The neutralizer is a mixture of any one or more of lime milk, limestone, sodium hydroxide, magnesium ore and magnesium hydroxide: the precipitation promoter is a mixture of any one or more of organic polymers and inorganic polymers, such as polyacrylamide, polyaluminum chloride, etc., which is not limited here.

[0069] In a specific Example, the process conditions for removing iron, aluminum and chromium are as follows: adding neutralizer, filling compressed air, controlling pH of 2.5~4.0, temperature of 70~90°C, reaction time of l~2h; Among them, after the first stage of iron, there is also a considerable part of nickel-cobalt-manganese in the slurry after thickening. It is beneficial to make full use of nickel-cobalt-manganese in the slurry by returning a section of the slurry after removing iron, aluminum and chromium for multistage counter-current decantation washing. In the process of removing iron, aluminum and chromium, it can remove iron, aluminum and chromium at the same time.

[0070] In a specific Example, the process conditions for the removal of iron, aluminum and chromium from the second stage and above are as follows: the pH is controlled at 4.0~5.5, the temperature is 55~80°C, and the reaction time is 2~10h. In the process of iron, aluminum and chromium removal at the second stage and above, the remaining iron, aluminum and chromium in the liquid phase can be further removed synchronously, which improves the removal efficiency of impurity metal elements, so as to ensure that purest nickel, cobalt and manganese products can be extracted later. The purpose of the slag phase of the second and above stages of iron, aluminum and chromium removal and recycling leaching and multistage neutralization treatment is that a certain amount of nickel, cobalt and manganese elements will still remain in the slag phase after the second and above stages of iron, aluminum and chromium removal, and the reuse can extract more nickel, cobalt and manganese as much as possible. At the same time, due to the large difference in pH value between the second stage and above iron, aluminum and chromium removal and the cyclic leaching-multi-stage pre-neutralization treatment, the reuse of slag phase from the second stage and above iron, aluminum and chromium removal can reduce the amount of neutralizing agent used in the cyclic leaching-first neutralization treatment to a certain extent, so as to achieve the purpose of cost saving.

[0071] Finally, the liquid phase of the tail section after multi-stage removal of iron, aluminum and chromium was precipitated by MHP to obtain nickel and cobalt hydroxide products. Among them, the mass percentage of nickel and cobalt hydroxide products is 30~ 40%, and the mass percentage of cobalt is 3.0~ 6.0%.

[0072] Specifically, the above precipitation MHP treatment is a multistage nickel-cobalt synthesis process, which consists of one stage of nickel-cobalt synthesis, two or more stages of nickel-cobalt synthesis, and the liquid phase after the former stage of nickelcobalt synthesis carries out the latter stage of nickel-cobalt synthesis. The liquid phase of the tail stage of multi-stage removal of iron, aluminum and chromium is processed by one-stage synthesis of nickel and cobalt, and the nickel and cobalt hydroxide products are obtained after one-stage synthesis of nickel and cobalt. The nickel and cobalt hydroxide products synthesized in the tail stage of multi-stage synthesis of nickel and cobalt are returned and recycled leaching and multi-stage neutralization treatment again, so that the small amount of nickel and cobalt remaining in the slag phase after multi-stage precipitation of nickel and cobalt can be extracted again in the technological process. The extraction rate of nickel and cobalt was improved. At the same time, the tail-stage liquid phase of multi-stage nickel and cobalt synthesis is discharged after wastewater treatment.

[0073] In a specific Example, the process conditions for the synthesis of nickel and cobalt are as follows: adding a neutralizing agent, controlling the pH value of 6.5~7.4, the temperature of 50~70°C, and the reaction time of 5~7h.

[0074] In a specific Example, the process conditions for the synthesis of nickel and cobalt at the second stage and above are as follows: the pH value is controlled at 7.5~10.0, the temperature is 40~90°C, and the reaction time is 0.5~1.5h.

[0075] The effect of the aforementioned multi-stage combined leaching method of ultra-low grade laterite nickel ore is described in the following example. Example 1 :

[0076] Please refer to Figure 2, which shows the specific process diagram of the multi-stage combined leaching method of ultra-low grade laterite nickel ore provided in Example 1 of the invention; among them, the above methods specifically include:

[0077] (1) A limonite laterite nickel ore is selected as the Example object. After determination (the following is the mass percentage) , the content of nickel in the ore is 0.4%, cobalt is 0.15%, Cr2Os is 3.78%, AI2O3 is 10.86%, SiC>2 is 25.42%, Fe is 30.54%, Mg is 5.23%; The results show that the sample is a typical ultra-low grade laterite nickel ore of limonite type. Laterite nickel ore raw slurry was prepared by mixing ultra-low grade laterite nickel ore with water, and the laterite nickel ore raw slurry was concentrated to 35% concentration.

[0078] (2) The mass ratio of laterite nickel ore slurry to lignite was 10001:1, and the lignite powder was added into the high pressure reactor together with sodium sulfate leaching accelerator. The leaching reaction was carried out under the high pressure leaching condition of temperature 255°C, pressure 4. OMPa and acid consumption of 20 tons / ton of nickel, and the high pressure leaching tailings containing iron, aluminum and magnesium and the high pressure leaching solution containing nickel, cobalt and manganese were obtained.

[0079] (3) Mix the high-pressure leaching liquid, the raw lateritic nickel ore slurry, and the acidic solution at a mass ratio of 1:1: 1.5 to obtain a mixed solution, and then transfer the mixed solution to an atmospheric pressure reactor for multi-stage atmospheric pressure leaching treatment; the process conditions for each stage of the multi-stage atmospheric pressure leaching treatment are: a temperature of 80°C, a pressure of O.IMpa, and the number of atmospheric pressure leaching stages is 5.

[0080] (4) A thickener is used to thicken the mixture obtained after multi-stage atmospheric pressure leaching treatment, resulting in the final stage concentrated atmospheric pressure leachate and the final stage concentrated atmospheric pressure leach residue. The concentration of the final stage concentrated atmospheric pressure leach residue slurry is 35%. The final stage concentrated atmospheric pressure leach residue is returned to step (2) to mix with the raw lateritic nickel ore slurry for high-pressure acid leaching treatment.

[0081] (5) After mixing the final stage concentrated atmospheric pressure leachate with the high-pressure leaching residue, it is subjected to cyclic leaching and multi-stage neutralization. Subsequently, a multi-stage counter-current washing process is adopted, with the washing stages being 6 levels and the ratio of wash water to residue being 5:1. After solid-liquid separation by a thickener, an appropriate amount of lime milk neutralizing agent is added to the residue to maintain the residue at a neutral pH of 6.8. Then, metallic iron is recovered and the tailings are discharged .

[0082] (6) The liquid phase obtained from multi-stage counter-current washing is further processed for iron, aluminum, and chromium removal. The process conditions for this iron, aluminum, and chromium removal are: the temperature is controlled at 85°C, the pH is maintained at 3.0, and the reaction time is 1 hour. After the first stage of iron, aluminum, and chromium removal, the residue slurry after thickening is reused for continuous multistage counter-current washing. The liquid phase after the first stage of iron, aluminum, and chromium removal undergoes a second stage of iron, aluminum, and chromium removal. The process conditions for the second stage of iron, aluminum, and chromium removal are: the temperature is controlled at 79°C, the pH is adjusted to 4.8, and the reaction time is 3 hours. After the second stage of iron, aluminum, and chromium removal, the residue is reused for cyclic leaching and neutralization.

[0083] (7) Neutralizing agents are added to the tail liquid phase after the second stage of iron, aluminum, and chromium removal to carry out the first stage of synthetic nickel-cobalt. After the first stage of synthetic nickel-cobalt, nickel-cobalt hydroxide products are obtained. The process conditions for the first stage of synthetic nickel-cobalt are: a pH value of 7.0, a reaction temperature of 66°C, and a reaction time of 3 hours. The process conditions for the second stage of synthetic nickel-cobalt are: control the pH value to 8.0, and a reaction temperature of 50°C. Among them, the obtained nickel-cobalt hydroxide product contains: a mass percentage of nickel of 31.13%, and a mass percentage of cobalt of 3.51%.

[0084] Example 2 :

[0085] Example 2 of the invention provides a multi-stage combined leaching method for ultra-low grade laterite nickel ore, which specifically comprises:

[0086] (1) A limonite laterite nickel ore is selected as the Example object. After determination (the following is the mass percentage) , the content of nickel in the ore is 0.6%, cobalt is 0.25%, Cr2Os is 2.48%, AI2O3 is 9.45%, SiO2 is 18.67%, Fe is 35.14%, Mg is 8.38%; The results show that the sample is a typical ultra-low grade laterite nickel ore of limonite type. Laterite nickel ore raw slurry was prepared by mixing ultra-low grade laterite nickel ore with water, and the laterite nickel ore raw slurry was concentrated to 35% concentration.

[0087] (2) The mass ratio of laterite nickel ore slurry to lignite was 1000:1, and the lignite powder was added into the high pressure reactor together with sodium sulfate leaching accelerator. The leaching reaction was carried out under the high pressure leaching condition of temperature 255°C, pressure 4. OMPa and acid consumption of 20 tons / ton of nickel, and the high pressure leaching tailings containing iron, aluminum and magnesium and the high pressure leaching solution containing nickel, cobalt and manganese were obtained.

[0088] (3) Mix the high-pressure leaching liquid, the raw lateritic nickel ore slurry, and the acidic solution at a mass ratio of 1:1: 1.5 to obtain a mixed solution, and then transfer the mixed solution to an atmospheric pressure reactor for multi-stage atmospheric pressure leaching treatment; the process conditions for each stage of the multi-stage atmospheric pressure leaching treatment are: a temperature of 80°C, a pressure of O.IMpa, and the number of atmospheric pressure leaching stages is 5.

[0089] (4) A thickener is used to thicken the mixture obtained after multi-stage atmospheric pressure leaching treatment, resulting in the final stage concentrated atmospheric pressure leachate and the final stage concentrated atmospheric pressure leach residue. The concentration of the final stage concentrated atmospheric pressure leach residue slurry is 35%. The final stage concentrated atmospheric pressure leach residue is returned to step (2) to mix with the raw lateritic nickel ore slurry for high-pressure acid leaching treatment.

[0090] (5) After mixing the final stage concentrated atmospheric pressure leachate with the high-pressure leaching residue, it is subjected to cyclic leaching and multi-stage neutralization. Subsequently, a multi-stage counter-current washing process is adopted, with the washing stages being 6 levels and the ratio of wash water to residue being 5:1. After solid-liquid separation by a thickener, an appropriate amount of lime milk neutralizing agent is added to the residue to maintain the residue at a neutral pH of 6.8. Then, metallic iron is recovered and the tailings are discharged .

[0091] (6) The liquid phase obtained from multi-stage counter-current washing is further processed for iron, aluminum, and chromium removal. The process conditions for this iron, aluminum, and chromium removal are: the temperature is controlled at 85°C, the pH is maintained at 3.0, and the reaction time is 1 hour. After the first stage of iron, aluminum, and chromium removal, the residue slurry after thickening is reused for continuous multistage counter-current washing. The liquid phase after the first stage of iron, aluminum, and chromium removal undergoes a second stage of iron, aluminum, and chromium removal. The process conditions for the second stage of iron, aluminum, and chromium removal are: the temperature is controlled at 79°C, the pH is adjusted to 4.8, and the reaction time is 3 hours. After the second stage of iron, aluminum, and chromium removal, the residue is reused for cyclic leaching and neutralization.

[0092] (7) Neutralizing agents are added to the tail liquid phase after the second stage of iron, aluminum, and chromium removal to carry out the first stage of synthetic nickel-cobalt. After the first stage of synthetic nickel-cobalt, nickel-cobalt hydroxide products are obtained. The process conditions for the first stage of synthetic nickel-cobalt are: a pH value of 7.0, a reaction temperature of 66°C, and a reaction time of 3 hours. The process conditions for the second stage of synthetic nickel-cobalt are: control the pH value to 8.0, and a reaction temperature of 50°C. Among them, the obtained nickel-cobalt hydroxide product contains: a mass percentage of nickel of 35.23%, and a mass percentage of cobalt of 4.89%.

[0093] Example 3:

[0094] Example 3 of the invention provides a multi-stage combined leaching method for ultra-low grade laterite nickel ore, which specifically comprises:

[0095] (1) A limonite laterite nickel ore is selected as the Example object. After determination (the following is the mass percentage) , the content of nickel in the ore is 0.8%, cobalt is 0.45%, Cr2Os is 4.12%, MnO is 1.58%, AI2O3 is 9.81%, SiO2 is 12.18%, Fe is 33.27%, Mg is 6.25%; The results show that the sample is a typical ultralow grade laterite nickel ore of limonite type. Laterite nickel ore raw slurry was prepared by mixing ultra-low grade laterite nickel ore with water, and the laterite nickel ore raw slurry was concentrated to 35% concentration.

[0096] (2) The mass ratio of laterite nickel ore slurry to lignite was 1000:1, and the lignite powder was added into the high pressure reactor together with sodium sulfate leaching accelerator. The leaching reaction was carried out under the high pressure leaching condition of temperature 255°C, pressure 4. OMPa and acid consumption of 20 tons / ton of nickel, and the high pressure leaching tailings containing iron, aluminum and magnesium and the high pressure leaching solution containing nickel, cobalt and manganese were obtained.

[0097] (3) Mix the high-pressure leaching liquid, the raw lateritic nickel ore slurry, and the acidic solution at a mass ratio of 1:1: 1.5 to obtain a mixed solution, and then transfer the mixed solution to an atmospheric pressure reactor for multi-stage atmospheric pressure leaching treatment; the process conditions for each stage of the multi-stage atmospheric pressure leaching treatment are: a temperature of 80°C, a pressure of O.IMpa, and the number of atmospheric pressure leaching stages is 5.

[0098] (4) A thickener is used to thicken the mixture obtained after multi-stage atmospheric pressure leaching treatment, resulting in the final stage concentrated atmospheric pressure leachate and the final stage concentrated atmospheric pressure leach residue. The concentration of the final stage concentrated atmospheric pressure leach residue slurry is 35%. The final stage concentrated atmospheric pressure leach residue is returned to step (2) to mix with the raw lateritic nickel ore slurry for high-pressure acid leaching treatment.

[0099] (5) After mixing the final stage concentrated atmospheric pressure leachate with the high-pressure leaching residue, it is subjected to cyclic leaching and multi-stage neutralization. Subsequently, a multi-stage counter-current washing process is adopted, with the washing stages being 6 levels and the ratio of wash water to residue being 5:1. After solid-liquid separation by a thickener, an appropriate amount of lime milk neutralizing agent is added to the residue to maintain the residue at a neutral pH of 6.8. Then, metallic iron is recovered and the tailings are discharged .

[0100] (6) The liquid phase obtained from multi-stage counter-current washing is further processed for iron, aluminum, and chromium removal. The process conditions for this iron, aluminum, and chromium removal are: the temperature is controlled at 85°C, the pH is maintained at 3.0, and the reaction time is 1 hour. After the first stage of iron, aluminum, and chromium removal, the residue slurry after thickening is reused for continuous multistage counter-current washing. The liquid phase after the first stage of iron, aluminum, and chromium removal undergoes a second stage of iron, aluminum, and chromium removal. The process conditions for the second stage of iron, aluminum, and chromium removal are: the temperature is controlled at 79°C, the pH is adjusted to 4.8, and the reaction time is 3 hours. After the second stage of iron, aluminum, and chromium removal, the residue is reused for cyclic leaching and neutralization.

[0101] (7) Neutralizing agents are added to the tail liquid phase after the second stage of iron, aluminum, and chromium removal to carry out the first stage of synthetic nickel-cobalt. After the first stage of synthetic nickel-cobalt, nickel-cobalt hydroxide products are obtained. The process conditions for the first stage of synthetic nickel-cobalt are: a pH value of 7.0, a reaction temperature of 66°C, and a reaction time of 3 hours. The process conditions for the second stage of synthetic nickel-cobalt are: control the pH value to 8.0, and a reaction temperature of 50°C. Among them, the obtained nickel-cobalt hydroxide product contains: a mass percentage of nickel of 38.63%, and a mass percentage of cobalt of 5.25%.

[0102] Example 4 :

[0103] Example 4 of the invention provides a multi-stage combined leaching method for ultra-low grade laterite nickel ore, which specifically comprises:

[0104] (1) A limonite laterite nickel ore is selected as the Example object. After determination (the following is the mass percentage) , the content of nickel in the ore is 0.4%, cobalt is 0.15%, Cr2Os is 3.78%, MnO is 2.13%, AI2O3 is 10.86%, SiO2 is 25.42%, Fe is 30.54%, Mg is 5.23%; The results show that the sample is a typical ultra-low grade laterite nickel ore of limonite type. Laterite nickel ore raw slurry was prepared by mixing ultra-low grade laterite nickel ore with water, and the laterite nickel ore raw slurry was concentrated to 35% concentration.

[0105] (2) The mass ratio of laterite nickel ore slurry to lignite was 1000:1, and the lignite powder was added into the high pressure reactor together with sodium sulfate leaching accelerator. The leaching reaction was carried out under the high pressure leaching condition of temperature 255°C, pressure 4. OMPa and acid consumption of 20 tons / ton of nickel, and the high pressure leaching tailings containing iron, aluminum and magnesium and the high pressure leaching solution containing nickel, cobalt and manganese were obtained.

[0106] (3) Mix the high-pressure leaching liquid, the raw lateritic nickel ore slurry, and the acidic solution at a mass ratio of 1:1: 1.5 to obtain a mixed solution, and then transfer the mixed solution to an atmospheric pressure reactor for multi-stage atmospheric pressure leaching treatment; the process conditions for each stage of the multi-stage atmospheric pressure leaching treatment are: a temperature of 80°C, a pressure of O.IMpa, and the number of atmospheric pressure leaching stages is 8.

[0107] (4) A thickener is used to thicken the mixture obtained after multi-stage atmospheric pressure leaching treatment, resulting in the final stage concentrated atmospheric pressure leachate and the final stage concentrated atmospheric pressure leach residue. The concentration of the final stage concentrated atmospheric pressure leach residue slurry is 35%. The final stage concentrated atmospheric pressure leach residue is returned to step (2) to mix with the raw lateritic nickel ore slurry for high-pressure acid leaching treatment.

[0108] (5) After mixing the final stage concentrated atmospheric pressure leachate with the high-pressure leaching residue, it is subjected to cyclic leaching and multi-stage neutralization. Subsequently, a multi-stage counter-current washing process is adopted, with the washing stages being 6 levels and the ratio of wash water to residue being 5:1. After solid-liquid separation by a thickener, an appropriate amount of lime milk neutralizing agent is added to the residue to maintain the residue at a neutral pH of 6.8. Then, metallic iron is recovered and the tailings are discharged .

[0109] (6) The liquid phase obtained from multi-stage counter-current washing is further processed for iron, aluminum, and chromium removal. The process conditions for this iron, aluminum, and chromium removal are: the temperature is controlled at 85°C, the pH is maintained at 3.0, and the reaction time is 1 hour. After the first stage of iron, aluminum, and chromium removal, the residue slurry after thickening is reused for continuous multistage counter-current washing. The liquid phase after the first stage of iron, aluminum, and chromium removal undergoes a second stage of iron, aluminum, and chromium removal. The process conditions for the second stage of iron, aluminum, and chromium removal are: the temperature is controlled at 79°C, the pH is adjusted to 4.8, and the reaction time is 3 hours. After the second stage of iron, aluminum, and chromium removal, the residue is reused for cyclic leaching and neutralization.

[0110] (7) Neutralizing agents are added to the tail liquid phase after the second stage of iron, aluminum, and chromium removal to carry out the first stage of synthetic nickel-cobalt. After the first stage of synthetic nickel-cobalt, nickel-cobalt hydroxide products are obtained. The process conditions for the first stage of synthetic nickel-cobalt are: a pH value of 7.0, a reaction temperature of 66°C, and a reaction time of 3 hours. The process conditions for the second stage of synthetic nickel-cobalt are: control the pH value to 8.0, and a reaction temperature of 50°C. Among them, the obtained nickel-cobalt hydroxide product contains: a mass percentage of nickel of 32.83%, and a mass percentage of cobalt of 4.78%.

[0111] Example 5:

[0112] Example 5 of the invention provides a multi-stage combined leaching method for ultra-low grade laterite nickel ore, which specifically comprises:

[0113] (1) A limonite laterite nickel ore is selected as the Example object. After determination (the following is the mass percentage) , the content of nickel in the ore is 0.4%, cobalt is 0.15%, Cr2Os is 3.78%, MnO is 2.13%, AI2O3 is 10.86%, SiO2 is 25.42%, Fe is 30.54%, Mg is 5.23%; The results show that the sample is a typical ultra-low grade laterite nickel ore of limonite type. Laterite nickel ore raw slurry was prepared by mixing ultra-low grade laterite nickel ore with water, and the laterite nickel ore raw slurry was concentrated to 35% concentration.

[0114] (2) The mass ratio of laterite nickel ore slurry to lignite was 1000:1, and the lignite powder was added into the high pressure reactor together with sodium sulfate leaching accelerator. The leaching reaction was carried out under the high pressure leaching condition of temperature 255°C, pressure 4. OMPa and acid consumption of 20 tons / ton of nickel, and the high pressure leaching tailings containing iron, aluminum and magnesium and the high pressure leaching solution containing nickel, cobalt and manganese were obtained.

[0115] (3) Mix the high-pressure leaching liquid, the raw lateritic nickel ore slurry, and the acidic solution at a mass ratio of 1:1: 1.5 to obtain a mixed solution, and then transfer the mixed solution to an atmospheric pressure reactor for multi-stage atmospheric pressure leaching treatment; the process conditions for each stage of the multi-stage atmospheric pressure leaching treatment are: a temperature of 90°C, a pressure of O.IMpa, and the number of atmospheric pressure leaching stages is 5.

[0116] (4) A thickener is used to thicken the mixture obtained after multi-stage atmospheric pressure leaching treatment, resulting in the final stage concentrated atmospheric pressure leachate and the final stage concentrated atmospheric pressure leach residue. The concentration of the final stage concentrated atmospheric pressure leach residue slurry is 35%. The final stage concentrated atmospheric pressure leach residue is returned to step (2) to mix with the raw lateritic nickel ore slurry for high-pressure acid leaching treatment.

[0117] (5) After mixing the final stage concentrated atmospheric pressure leachate with the high-pressure leaching residue, it is subjected to cyclic leaching and multi-stage neutralization. Subsequently, a multi-stage counter-current washing process is adopted, with the washing stages being 6 levels and the ratio of wash water to residue being 5:1. After solid-liquid separation by a thickener, an appropriate amount of lime milk neutralizing agent is added to the residue to maintain the residue at a neutral pH of 6.8. Then, metallic iron is recovered and the tailings are discharged .

[0118] (6) The liquid phase obtained from multi-stage counter-current washing is further processed for iron, aluminum, and chromium removal. The process conditions for this iron, aluminum, and chromium removal are: the temperature is controlled at 85°C, the pH is maintained at 3.0, and the reaction time is 1 hour. After the first stage of iron, aluminum, and chromium removal, the residue slurry after thickening is reused for continuous multistage counter-current washing. The liquid phase after the first stage of iron, aluminum, and chromium removal undergoes a second stage of iron, aluminum, and chromium removal. The process conditions for the second stage of iron, aluminum, and chromium removal are: the temperature is controlled at 79°C, the pH is adjusted to 4.8, and the reaction time is 3 hours. After the second stage of iron, aluminum, and chromium removal, the residue is reused for cyclic leaching and neutralization.

[0119] (7) Neutralizing agents are added to the tail liquid phase after the second stage of iron, aluminum, and chromium removal to carry out the first stage of synthetic nickel-cobalt. After the first stage of synthetic nickel-cobalt, nickel-cobalt hydroxide products are obtained. The process conditions for the first stage of synthetic nickel-cobalt are: a pH value of 7.0, a reaction temperature of 66°C, and a reaction time of 3 hours. The process conditions for the second stage of synthetic nickel-cobalt are: control the pH value to 8.0, and a reaction temperature of 50°C. Among them, the obtained nickel-cobalt hydroxide product contains: a mass percentage of nickel of 32.51%, and a mass percentage of cobalt of 4.23%.

[0120] Comparative Example 1

[0121] Comparative Example 1, a multi-stage combined leaching method for ultra-low grade laterite nickel ore is provided, which specifically includes:

[0122] (1) A limonite laterite nickel ore is selected as the Example object. After determination (the following is the mass percentage) , the content of nickel in the ore is 0.4%, cobalt is 0.15%, Cr2Os is 3.78%, MnO is 2.13%, AI2O3 is 10.86%, SiO2 is 25.42%, Fe is 30.54%, Mg is 5.23%; The results show that the sample is a typical ultra-low grade laterite nickel ore of limonite type. Laterite nickel ore raw slurry was prepared by mixing ultra-low grade laterite nickel ore with water, and the laterite nickel ore raw slurry was concentrated to 35% concentration.

[0123] (2) The mass ratio of laterite nickel ore slurry to lignite was 1000:1, and the lignite powder was added into the high pressure reactor together with sodium sulfate leaching accelerator. The leaching reaction was carried out under the high pressure leaching condition of temperature 255°C, pressure 4. OMPa and acid consumption of 20 tons / ton of nickel, and the high pressure leaching tailings containing iron, aluminum and magnesium and the high pressure leaching solution containing nickel, cobalt and manganese were obtained.

[0124] (3) The high-pressure leaching slurry was recycled and neutralized by multi-stage, and then the multi-stage countercurrent washing process was adopted, the washing stage was 6, and the ratio of washing water to slag phase was 5:1. After solidliquid separation by thickener, an appropriate amount of lime milk neutralizing agent was added to the slag phase to make the slag phase in a neutral state of pH 6.8, and then the metal iron was recovered and the tail slag was discharged.

[0125] (4) The liquid phase obtained by multi-stage counter-current washing was continued to remove iron, aluminum and chromium for one stage. The process conditions for removing iron, aluminum and chromium for one stage were as follows: the control temperature was 85°C, the pH was 3.0, and the reaction time was Ih. The slag phase after removing iron, aluminum and chromium is reused for continuous multi-stage countercurrent washing again. The liquid phase after the first stage of iron, aluminum and chromium removal was carried out for the second stage of iron, aluminum and chromium removal. The process conditions for the second stage of iron, aluminum and chromium removal were as follows: the control temperature was 79°C, the pH was 4.8, and the reaction time was 3h. The slag phase after the second stage of iron, aluminum and chromium removal was reused for cyclic leaching and neutralization again .

[0126] (5) Neutralizing agents are added to the tail liquid phase after the second stage of iron, aluminum, and chromium removal to carry out the first stage of synthetic nickel-cobalt. After the first stage of synthetic nickel-cobalt, nickel-cobalt hydroxide products are obtained. The process conditions for the first stage of synthetic nickel-cobalt are: a pH value of 7.0, a reaction temperature of 66°C, and a reaction time of 3 hours. The process conditions for the second stage of synthetic nickel-cobalt are: control the pH value to 8.0, and a reaction temperature of 50°C. Among them, the obtained nickel-cobalt hydroxide product contains: a mass percentage of nickel of 30.1%, and a mass percentage of cobalt of 2.85%.

[0127] Specifically, the final concentrated atmospheric pressure leaching slurry of Example 1-5 is converted according to dry ore, and the mass percentage of iron, aluminum, magnesium, nickel, cobalt and manganese in dry ore is counted, and Table 1 is obtained:

[0128] Table 1 Test results of the percentage of metal mass in the atmospheric leaching slurry of the final concentrated stage of

[0129] Examples 1-5

[0130] Speci fically, as can be seen from Table 1 : In Example 1 to 5 , the final stage concentrated atmospheric pressure leaching slurry has lower iron, aluminum, and magnesium content compared to its respective original lateritic nickel ore slurry . This proves that the multi-stage atmospheric pressure leaching process can leach more of the above metals to remove part of the iron, aluminum, and magnesium .

[0131] Furthermore , by comparing Example 4 with Example 1 , it can be seen that in the multi-stage atmospheric pressure leaching process : the higher the number of atmospheric pressure leaching stages , the better the leaching ef fect of iron, aluminum, and magnesium metals , and the lower the content of iron, aluminum, and magnesium in the final stage concentrated atmospheric pressure leaching slurry .

[0132] Furthermore , by comparing Example 5 with Example 1 , it can be seen that in the multi-stage atmospheric pressure leaching process : the higher the atmospheric pressure leaching temperature , the better the leaching ef fect of iron, aluminum, and magnesium metals , and the lower the content of iron, aluminum, and magnesium in the final stage concentrated atmospheric pressure leaching slurry .

[0133] Additionally, in step ( 2 ) , the scale inhibitor ef fect of Example 1 and comparative example 1 was compared . As described earlier, both Example 1 and comparative example 1 were operated for 60 days according to the process steps recorded, and the di f ference in pressure between the inner cavity of the high- pressure reactor and the inlet of the flash evaporation tank ( referred to as the pressure di f ference ) was tested . The speci fic statistical results are shown in Table 2 . Since the smaller the change in pressure di f ference during the continuous operation of the high-pressure reactor, the less scale is formed inside the cavity, the data in Table 2 shows that the combined process of high-pressure acid leaching and multi-stage atmospheric pressure leaching has better scale inhibition ef fect compared to the conventional high-pressure acid leaching process .

[0134] Table 2

[0135] The present invention can ef fectively reduce the scale formation on the inner walls of the high-pressure reactor and discharge pipes during the high-pressure acid leaching of ultralow grade lateritic nickel ore , achieving the purpose of extending the operation cycle of the lateritic nickel ore high-pressure acid leaching system and reducing the production reduction caused by scale removal ; moreover, it has good scale inhibition effect , is safe and environmentally friendly, and is simple to operate , convenient to use , and has a low cost .

[0136] Di f ferent from the existing technology, the Example o f the present invention mixes the high-pressure leaching liquid obtained after the high-pressure acid leaching treatment of the lateritic nickel ore raw slurry, the lateritic nickel ore raw slurry, and the acidic solution, and then carries out multi-stage atmospheric pressure leaching treatment . This can avoid the scale formation in the high-pressure reactor due to excessive accumulation during the high-pressure acid leaching treatment of the high-pressure leaching liquid . At the same time , because the reaction conditions of the multi-stage atmospheric pressure leaching treatment are milder compared with the high-pressure acid leaching treatment , it can ef fectively inhibit the scale formation rate of the high- pressure leaching liquid, thereby extending the processing time of the high-pressure acid leaching treatment , and ultimately improving the production ef ficiency of the nickel-cobalt hydroxide product and reducing the production cost of the nickel-cobalt hydroxide product .

[0137] It should be noted that the present invention is not limited to the above Example . The above Example is merely an example , and any Example that has the same construction and plays the same ef fect within the technical scheme of the present invention is included in the technical scope of the present invention . In addition, within the scope that does not depart from the essence of the present invention, various modi fications that can be thought of by those skilled in the art , and other methods constructed by combining some of the components in the Example are also included in the scope of the present invention .

Claims

What Is Claimed Is1 . The invention relates to a multi-stage combined leaching method for ultra-low grade laterite nickel ore , which is characteri zed in that .S 10 , the raw laterite nickel ore slurry is treated by high pressure acid leaching to obtain the high pressure leaching tailings containing iron, aluminum and magnesium and the high pressure leaching solution containing nickel , cobalt and manganese . The mass percentage of nickel in the raw laterite nickel ore is less than 1 . 0% .S20 , the high pressure leaching solution, laterite nickel ore slurry and acid solution were mixed to obtain the mixed solution, and the mixed solution was subj ected to multi-stage atmospheric pressure leaching treatment , after concentration treatment , the final concentrated atmospheric pressure leaching solution and the final concentrated atmospheric pressure leaching slurry with the same concentration as the raw laterite nickel ore slurry .S30 , the final concentrated atmospheric pressure leaching solution and high pressure leaching tail residue were successively recycled leaching, multi-stage pre-neutrali zation, counter-current decantation washing, Fe / Al / Cr removal and MHP precipitation to obtain nickel and cobalt hydroxide products . Among them, after the completion of the S20 step, it also includes : returning the final concentrated atmospheric leaching slurry to the S 10 step for the high pressure acid leaching treatment .2 . According to Claim 1 , the multi-stage combined leaching method of ultra-low grade laterite nickel ore is characteri zed in that in the S 10 step, the solid concentration of the raw slurry of the laterite nickel ore is 30~ 40% , and the slurry capacity ratio is 100~200m3 / ton metal nickel .3 . According to claim 1 , the multi-stage combined leaching method of ultra-low grade laterite nickel ore is characteri zed in that in the S 10 step, the technological conditions of thehigh-pressure acid leaching treatment are: temperature 220~260°C, pressure 2.0~ 6. OMPa .

4. According to claim 1, the multi-stage combined leaching method of ultra-low grade laterite nickel ore is characterized in that in the S20 step, the mass ratio of the high-pressure leaching solution, the raw slurry of the laterite nickel ore and the acid solution is 1: (0.8—1) : (1— 2) ; The acid solution includes sulfuric acid or hydrogen chloride.

5. According to claim 1, the multi-stage combined leaching method of ultra-low grade laterite nickel ore is characterized in that the temperature of the multi-stage atmospheric pressure leaching treatment in the S20 step is 60~90°C.

6. According to Claim 1, the multi-stage combined leaching method of ultra-low grade laterite nickel ore is characterized in that in the S20 step, the thickener is used to concentrate the mixed liquid after the multi-stage atmospheric leaching treatment to obtain the final concentrated atmospheric leaching liquid and the final concentrated atmospheric leaching slurry.

7. According to claim 1, the multi-stage combined leaching method of ultra-low grade laterite nickel ore is characterized in that in the S20 step, the multi-stage atmospheric leaching treatment has an atmospheric leaching order of 2~10.

8. According to claim 1, the multi-stage combined leaching method of ultra-low grade laterite nickel ore is characterized by the cyclic leaching and multi-stage pre-neutralization treatment of the S30 step: the control temperature of the cyclic leaching is 70~90°C; The pH of multi-stage pre-neutralization is 0.8~2, and the neutralizing agent of multi-stage preneutralization is any one or more alkaline mixtures of lime milk, limestone, sodium hydroxide, and magnesium hydroxide.

9. According to claim 1, the multi-stage combined leaching method of ultra-low grade laterite nickel ore is characterizedin that in the S30 step, the washing sequence of the countercurrent washing treatment is 3~9; The process conditions for removing iron, aluminum and chromium are as follows: the number of process stages is 2~7, the control temperature is 55~90°C, and the pH value is 2.5~5.5.

10. According to claim 1, the multistage combined leaching method of ultra-low grade laterite nickel ore is characterized in that the mass percentage of nickel and cobalt hydroxide in the nickel and cobalt hydroxide product in the S30 step is 30~ 40% and 3.0~ 6.0%.

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