Method for reducing nickel and cobalt content in tailings in laterite-nickel ore hydrometallurgy

Abstract

The invention relates to a method for reducing the content of nickel and cobalt in tailings in laterite-nickel ore hydrometallurgy, which comprises the following steps of: sequentially carrying out circulating leaching treatment and pre-neutralization treatment on leached slurry obtained in laterite-nickel ore hydrometallurgy to obtain pre-neutralized slurry, then carrying out multi-stage CCD (Charge Coupled Device) washing, and carrying out drying to obtain the nickel and cobalt content in the tailings in the laterite-nickel ore hydrometallurgy. And the obtained CCD overflow liquid is sequentially subjected to first-stage iron and aluminum removal and second-stage iron and aluminum removal, first-stage iron and aluminum removal underflow is recycled to a multi-stage CCD washing procedure and is subjected to collaborative sedimentation with the pre-neutralized slurry, and obtained CCD underflow is sequentially subjected to tailing neutralization and filter pressing treatment and then is discharged. According to the method disclosed by the invention, the one-stage iron-removed aluminum underflow is directly reused in the multi-stage CCD washing procedure, and water is added for dilution, so that iron-aluminum slag in the original one-stage iron-removed aluminum underflow and tailings in the pre-neutralized slurry are subjected to collaborative sedimentation, not only is the filter pressing-washing circulation treatment of the one-stage iron-removed aluminum underflow in the prior art omitted, but also two slag materials are effectively washed, and the cost is reduced. And the content of nickel and cobalt in the final tailings is reduced.

Description

Technical Field

[0001] The invention relates to the field of laterite nickel ore hydrometallurgy, and in particular to a method for reducing the nickel and cobalt contents in tailings by laterite nickel ore hydrometallurgy. Background Art

[0002] Nickel laterite is a type of ore rich in nickel and cobalt that is formed primarily in warm and humid climates when ultramafic rocks are weathered and leached at or near the surface to form nickel-rich laterite layers. The mining and processing of nickel laterite is critical to the global supply of nickel, especially for its growing use in the stainless steel and battery manufacturing industries.

[0003] Hydrometallurgy is a technology for extracting metals from ores, especially for processing ores with high water content and loose structure such as laterite nickel ore. The method mainly dissolves the metals in the ore into a solution through a series of chemical reactions, and then recovers the metals from the solution through steps such as precipitation, extraction or ion exchange. When processing laterite nickel ore, hydrometallurgical technology mainly includes processes such as high pressure acid leaching (HPAL), atmospheric acid leaching (ATM) and atmospheric sulfuric acid leaching (LSX).

[0004] Since laterite nickel ore not only contains rich nickel and cobalt, but also contains other impurities such as iron, aluminum, chromium, etc., impurity removal is a crucial processing step in the existing laterite nickel ore hydrometallurgical process, which directly affects the subsequent metal recovery efficiency and product quality. Furthermore, in the process of removing iron and aluminum, the iron and aluminum in the bottom flow often exist in the leachate in the form of colloids, which makes them difficult to separate by simple filtering methods. The current treatment method is to discharge it in the form of slag phase after multi-stage washing and pressure filtration. Due to the presence of iron-aluminum slag colloids, the above process is prone to blockage, and the treatment process is time-consuming and labor-intensive. It is urgent to propose a new process method to solve the above problems. Summary of the invention

[0005] In view of the problems existing in the prior art, the present invention provides a method for reducing the nickel and cobalt contents in tailings by hydrometallurgical processing of laterite nickel ore, in which a first-stage iron and aluminum removal underflow is directly reused in a multi-stage CCD washing process and diluted with water, so that the iron and aluminum slag in the original first-stage iron and aluminum removal underflow and the tailings in the pre-neutralized slurry are synergistically settled, which not only eliminates the filter press-washing cycle treatment of the first-stage iron and aluminum removal underflow in the prior art, but also effectively washes the two slag materials, thereby reducing the nickel and cobalt contents in the final tailings.

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

[0007] The present invention provides a method for reducing the nickel and cobalt contents in tailings by hydrometallurgical process of laterite nickel ore, comprising the following steps:

[0008] (1) taking a leached slurry obtained by hydrometallurgy of laterite nickel ore, sequentially performing a cyclic leaching treatment and a pre-neutralization treatment to obtain a pre-neutralized slurry, and then performing a multi-stage CCD washing to obtain a CCD overflow liquid;

[0009] (2) The CCD overflow liquid is subjected to first-stage and second-stage iron and aluminum removal in sequence, and the obtained first-stage iron and aluminum removal underflow is recycled to the multi-stage CCD washing, and is synergistically settled with the pre-neutralized slurry to obtain a CCD underflow, which is then subjected to tailings neutralization and filter press treatment in sequence to discharge the tailings.

[0010] In the prior art, the underflow of a first stage of iron removal and aluminum removal is usually discharged after being circulated for multiple times in a filter press-washing manner. Since there is iron-aluminum slag colloid in the underflow of a first stage of iron removal and aluminum removal, it is easy to cause blockage during the execution of the above process, and the treatment process is time-consuming and labor-intensive. The present invention directly reuses the underflow of a first stage of iron removal and aluminum removal to the multi-stage CCD washing process, and dilutes it with water, so that the iron-aluminum slag in the original underflow of a first stage of iron removal and aluminum removal and the tailings in the pre-neutralized slurry are synergistically settled, which not only saves the filter press-washing cycle treatment of the underflow of a first stage of iron removal and aluminum removal in the prior art, but also effectively washes the two slag materials, reducing the content of nickel and cobalt in the final tailings.

[0011] It should be noted that the leaching slurry obtained by the laterite-nickel ore hydrometallurgy of the present invention is preferably a laterite-nickel ore high-pressure leaching slurry.

[0012] As a preferred technical solution of the present invention, in step (1), the process conditions of the cyclic leaching treatment are: controlling the pH to be less than 1.5.

[0013] As a preferred technical solution of the present invention, in step (1), the process conditions of the pre-neutralization treatment are: controlling pH = 1.8 to 2.2, such as 1.8, 1.9, 2.0, 2.1 or 2.2, etc. Preferably, the pre-neutralization treatment is performed by adding limestone to adjust the pH to 1.8 to 2.2.

[0014] As a preferred technical solution of the present invention, in step (1), the process conditions of the multi-stage CCD washing are: controlling pH = 2.2 to 4.7, for example, 2.2, 2.5, 2.8, 3.0, 3.3, 3.5, 3.8, 4.0, 4.3, 4.5 or 4.7.

[0015] As a preferred technical solution of the present invention, in step (2), the process conditions for the first stage of iron and aluminum removal are: controlling the pH to 3.5-3.8, such as 3.5, 3.6, 3.7 or 3.8, and the process conditions for the second stage of iron and aluminum removal are: controlling the pH to 4.8-5.0, such as 4.8, 4.9 or 5.0.

[0016] As a preferred technical solution of the present invention, the number of stages of the multi-stage CCD washing in step (1) is 2 to 6, such as 2, 3, 4, 5 or 6, the pre-neutralized slurry in step (2) enters the first stage of the multi-stage CCD washing, and the first stage of the aluminum-iron removal underflow is recycled to the i-th stage of the multi-stage CCD washing, where i ≥ 2 and is an integer. If the first stage of the aluminum-iron removal underflow is also recycled to the first stage of the multi-stage CCD washing, it will cause too much suspended matter in the first stage of the multi-stage CCD washing, seriously affecting the stable operation of the multi-stage CCD washing; further experiments have found that the earlier the stage of the aluminum-iron removal underflow is recycled, the better the washing effect, and the less the content of nickel ions and cobalt ions in the final tailings.

[0017] As a preferred technical solution of the present invention, the first stage of iron and aluminum removal bottom flow is diluted with water before reuse, and the ratio of the volume of the added water to the volume of the first stage of iron and aluminum removal bottom flow is controlled to be >1.2, such as 1.3, 1.4, 1.5 or 1.6.

[0018] As a preferred technical solution of the present invention, the concentration of the first section of iron-removal aluminum bottom flow before dilution with water is 25-30%, for example, 25%, 26%, 27%, 28%, 29% or 30%, etc., and the concentration of the first section of iron-removal aluminum bottom flow reused after dilution with water is 5-8%, for example, 5%, 5.5%, 6%, 6.5%, 7%, 7.5% or 8%, etc.

[0019] As a preferred technical solution of the present invention, in step (2), the specific step of neutralizing the tailings includes: adding lime milk to make the system pH = 6.8 to 7.2, such as 6.8, 6.9, 7.0, 7.1 or 7.2.

[0020] As a preferred technical solution of the present invention, it also includes:

[0021] In step (2), the second stage of deironing aluminum obtains a second stage of deironing aluminum underflow and a second stage of deironing aluminum overflow. The second stage of deironing aluminum underflow is reused and subjected to cyclic leaching treatment again, and the second stage of deironing aluminum overflow is subjected to MHP sedimentation treatment.

[0022] Compared with the prior art solutions, the present invention has at least the following beneficial effects:

[0023] The invention provides a method for reducing the nickel and cobalt contents in tailings by hydrometallurgical treatment of laterite nickel ore, wherein a first-stage iron and aluminum removal underflow is directly recycled to a multi-stage CCD washing process and diluted with water, so that the iron and aluminum slag in the original first-stage iron and aluminum removal underflow and the tailings in the pre-neutralized slurry are synergistically settled, which not only eliminates the filter pressing-washing cycle treatment of the first-stage iron and aluminum removal underflow in the prior art, but also effectively washes the two slag materials, thereby reducing the nickel and cobalt contents in the final tailings. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1It is a schematic flow chart of a method for reducing the nickel and cobalt contents in tailings by hydrometallurgy of laterite nickel ore in one embodiment of the present invention.

[0025] Figure 2 It is a schematic diagram of a process of recycling a first stage of iron and aluminum removal bottom flow to a multi-stage CCD washing in one embodiment of the present invention. DETAILED DESCRIPTION

[0026] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0027] One embodiment of the present invention provides a method for reducing the nickel and cobalt content in tailings by hydrometallurgy of laterite nickel ore, such as Figure 1 As shown, the following steps are included:

[0028] (1) taking a laterite nickel ore high pressure leaching slurry, sequentially performing a cyclic leaching treatment and a pre-neutralization treatment to obtain a pre-neutralized slurry, and then performing a multi-stage CCD washing to obtain a CCD overflow liquid;

[0029] Wherein, in step (1), the process conditions of the cyclic leaching treatment are: controlling pH < 1.5; the process conditions of the pre-neutralization treatment are: controlling pH = 1.8 to 2.2; the process conditions of the multi-stage CCD washing are: controlling pH = 2.2 to 4.7;

[0030] (2) the CCD overflow liquid is subjected to first-stage and second-stage iron and aluminum removal in sequence, the obtained first-stage iron and aluminum removal underflow is recycled to the multi-stage CCD washing, and is synergistically settled with the pre-neutralized slurry to obtain a CCD underflow, and the CCD underflow is sequentially subjected to tailings neutralization and filter press treatment to discharge the tailings;

[0031] (3) The second stage of iron removal and aluminum removal obtains a second stage of iron removal and aluminum removal underflow and a second stage of iron removal and aluminum removal overflow, the second stage of iron removal and aluminum removal underflow is reused and subjected to a cyclic leaching treatment again, and the second stage of iron removal and aluminum removal overflow is subjected to MHP treatment;

[0032] Wherein, in step (2), the process conditions for the first stage of iron and aluminum removal are: controlling the pH to be 3.5-3.8, and the process conditions for the second stage of iron and aluminum removal are: controlling the pH to be 4.8-5.0.

[0033] In step (2), the underflow from the first stage of iron and aluminum removal is recycled to the multi-stage CCD washing. Figure 2An embodiment is shown, including the following contents: the number of stages of the multi-stage CCD washing in step (1) is 6, the pre-neutralized slurry in step (2) enters the first stage of the multi-stage CCD washing, and the one-stage iron removal aluminum underflow is recycled to the second stage of the multi-stage CCD washing; the one-stage iron removal aluminum underflow is diluted with water in the second stage of the multi-stage CCD washing, and the ratio of the volume of the added water to the volume of the one-stage iron removal aluminum underflow is controlled to be greater than 1.2; more specifically, the overflow liquid of the next-stage CCD washing is used as added water to dilute the one-stage iron removal aluminum underflow, and is settled in the previous-stage CCD washing section; for example, the overflow liquid of the third-stage CCD washing can be recycled and used as added water to dilute the one-stage iron removal aluminum underflow, and is introduced into the second-stage CCD washing section for sedimentation; in other embodiments, similar overflow recycling methods or other water adding methods can also be adopted, which are not limited here. In this process, the concentration of a section of de-ironing and aluminum underflow before dilution with water is 25-30%. If the concentration of a section of de-ironing and aluminum underflow is too high, it is difficult to transport and may easily cause pipeline blockage. At the same time, the ratio of the volume of added water to the volume of a section of de-ironing and aluminum underflow also needs to be controlled. The concentration of a section of de-ironing and aluminum underflow reused after dilution with water is 5-8%. If the volume of added water is too small, it is difficult to fully dilute the section of de-ironing and aluminum underflow, which may also cause the mixed solution concentration to be too high and difficult to settle in the secondary CCD washing section.

[0034] In step (3), the second-stage aluminum deironing is performed to obtain the second-stage aluminum deironing underflow and the second-stage aluminum deironing overflow. The second-stage aluminum deironing underflow is recycled to the circulating leaching process, and the residual temperature and residual acid of the high-pressure acid leaching slurry and the recirculating second-stage aluminum deironing underflow are used for circulating leaching. The metal elements such as Ni and Co remaining in the second-stage aluminum deironing underflow re-enter the reaction system, thereby improving the subsequent extraction rate of the metal elements such as Ni and Co.

[0035] To better illustrate the present invention and facilitate understanding of the technical solution of the present invention, typical but non-limiting embodiments of the present invention are as follows:

[0036] The mass percentage of each element in the laterite nickel ore used in the following embodiments and comparative examples is shown in Table 1 below. The ore is prepared into a slurry and then subjected to high-pressure acid leaching to obtain a laterite nickel ore high-pressure acid leaching slurry; wherein the conditions of the high-pressure acid leaching are: 250° C., a pressure of 4.5 MPa, and an acid consumption of 25 tons / ton of nickel; and the multi-stage CCD washing process specifically includes 6 stages of countercurrent washing.

[0037] Table 1 Composition of laterite nickel ore

[0038]

[0039] Example 1

[0040] A method for reducing the nickel and cobalt content in tailings by hydrometallurgical processing of laterite nickel ore comprises the following steps:

[0041] (1) A high-pressure leaching slurry of laterite nickel ore is sequentially subjected to a circulating leaching treatment and a pre-neutralization treatment to obtain a pre-neutralized slurry, wherein the circulating leaching treatment controls the pH value to be less than 1.5, and the pre-neutralization treatment controls the pH value to be 1.8 to 2.2; then a 6-stage CCD washing is performed to obtain a CCD overflow liquid; wherein the pH value of the first-stage CCD washing section of the multi-stage CCD washing is controlled to be 2.2 to 2.5, and the pH value of the sixth-stage CCD washing section is controlled to be 4.5 to 4.7.

[0042] (2) The CCD overflow is subjected to a first-stage iron and aluminum removal treatment (controlling pH=3.5-3.8) and a second-stage iron and aluminum removal treatment (controlling pH=4.8-5.0) in sequence, wherein the concentration of the first-stage iron and aluminum removal underflow is 29%; the third-stage CCD washing overflow liquid is reused as water to dilute the first-stage iron and aluminum removal underflow, and then reused to the second-stage CCD washing section, and synergistically precipitated with the pre-neutralized slurry, the volume ratio of the added water to the volume of the first-stage iron and aluminum removal underflow is 1.3, and the concentration of the first-stage iron and aluminum removal underflow reused after dilution with water meets 5-8%; after synergistic sedimentation, the CCD underflow is derived from the sixth-stage CCD washing section, and the CCD underflow is subjected to tailings neutralization treatment (adjusting pH=7 by adding lime milk), and then subjected to filter press treatment, and finally the tailings are discharged.

[0043] (3) After the second stage iron removal and aluminum treatment, the second stage iron removal and aluminum underflow and the second stage iron removal and aluminum overflow are obtained. The second stage iron removal and aluminum underflow are reused and the cyclic leaching process is carried out again. The residual temperature and residual acid of the high-pressure acid leaching slurry and the refluxed second stage iron removal and aluminum underflow are used for cyclic leaching. The second stage iron removal and aluminum overflow are treated with MHP.

[0044] Example 2

[0045] A method for reducing the nickel and cobalt content in tailings by hydrometallurgical processing of laterite nickel ore comprises the following steps:

[0046] (1) taking a laterite nickel ore high-pressure leaching slurry and sequentially performing a cyclic leaching treatment and a pre-neutralization treatment to obtain a pre-neutralized slurry, wherein the cyclic leaching treatment controls the pH value to be less than 1.5, and the pre-neutralization treatment controls the pH value to be 1.8 to 2.2; then performing a 6-stage CCD washing to obtain a CCD overflow liquid, wherein the first-stage CCD washing section of the multi-stage CCD washing controls the pH value to be 2.2 to 2.5, and the sixth-stage CCD washing section controls the pH value to be 4.5 to 4.7;

[0047] (2) The CCD overflow is subjected to a first-stage iron and aluminum removal treatment (controlling pH=3.5-3.8) and a second-stage iron and aluminum removal treatment (controlling pH=4.8-5.0) in sequence, wherein the concentration of the first-stage iron and aluminum removal underflow is 29%; the fourth-stage CCD washing overflow liquid is reused as water to dilute the first-stage iron and aluminum removal underflow, and then reused to the third-stage CCD washing section and synergistically precipitated with the pre-neutralized slurry, the volume ratio of the added water to the volume of the first-stage iron and aluminum removal underflow is 1.3, and the concentration of the first-stage iron and aluminum removal underflow reused after dilution with water meets 5-8%; after synergistic sedimentation, the CCD underflow is derived from the sixth-stage CCD washing section, and the CCD underflow is subjected to tailings neutralization treatment (adjusting pH=7 by adding lime milk), and then subjected to filter press treatment, and finally the tailings are discharged.

[0048] (3) After the second stage iron removal and aluminum treatment, the second stage iron removal and aluminum underflow and the second stage iron removal and aluminum overflow are obtained. The second stage iron removal and aluminum underflow are reused and the cyclic leaching process is carried out again. The residual temperature and residual acid of the high-pressure acid leaching slurry and the refluxed second stage iron removal and aluminum underflow are used for cyclic leaching. The second stage iron removal and aluminum overflow are treated with MHP.

[0049] Example 3

[0050] A method for reducing the nickel and cobalt content in tailings by hydrometallurgical processing of laterite nickel ore comprises the following steps:

[0051] (1) taking a laterite nickel ore high-pressure leaching slurry and sequentially performing a cyclic leaching treatment and a pre-neutralization treatment to obtain a pre-neutralized slurry, wherein the cyclic leaching treatment controls the pH value to be less than 1.5, and the pre-neutralization treatment controls the pH value to be 1.8 to 2.2; then performing a 6-stage CCD washing to obtain a CCD overflow liquid, wherein the first-stage CCD washing section of the multi-stage CCD washing controls the pH value to be 2.2 to 2.5, and the sixth-stage CCD washing section controls the pH value to be 4.5 to 4.7;

[0052] (2) The CCD overflow is sequentially subjected to a first-stage deironing and aluminum removal treatment (controlling pH=3.5-3.8) and a second-stage deironing and aluminum removal treatment (controlling pH=4.8-5.0), wherein the concentration of the first-stage deironing and aluminum underflow is 29%; the fifth-stage CCD washing overflow liquid is reused as water to dilute the first-stage deironing and aluminum underflow, and then reused to the fourth-stage CCD washing section and synergistically precipitated with the pre-neutralized slurry, the volume ratio of the added water to the first-stage deironing and aluminum underflow is 1.3, and the concentration of the first-stage deironing and aluminum underflow reused after dilution with water meets 5-8%; after synergistic sedimentation, the CCD underflow is derived from the sixth-stage CCD washing section, and the CCD underflow is subjected to tailings neutralization treatment (adjusting pH=7 by adding lime milk), and then subjected to filter press treatment, and finally the tailings are discharged.

[0053] (3) After the second stage iron removal and aluminum treatment, the second stage iron removal and aluminum underflow and the second stage iron removal and aluminum overflow are obtained. The second stage iron removal and aluminum underflow are reused and the cyclic leaching process is carried out again. The residual temperature and residual acid of the high-pressure acid leaching slurry and the refluxed second stage iron removal and aluminum underflow are used for cyclic leaching. The second stage iron removal and aluminum overflow are treated with MHP.

[0054] Example 4

[0055] A method for reducing the nickel and cobalt content in tailings by hydrometallurgical processing of laterite nickel ore comprises the following steps:

[0056] (1) A high-pressure leaching slurry of laterite nickel ore is sequentially subjected to a circulating leaching treatment and a pre-neutralization treatment to obtain a pre-neutralized slurry, wherein the circulating leaching treatment controls the pH value to be less than 1.5, and the pre-neutralization treatment controls the pH value to be 1.8 to 2.2; then a 6-stage CCD washing is performed to obtain a CCD overflow liquid; wherein the pH value of the first-stage CCD washing section of the multi-stage CCD washing is controlled to be 2.2 to 2.5, and the pH value of the sixth-stage CCD washing section is controlled to be 4.5 to 4.7.

[0057] (2) The CCD overflow is subjected to a first-stage iron and aluminum removal treatment (controlling pH=3.5-3.8) and a second-stage iron and aluminum removal treatment (controlling pH=4.8-5.0) in sequence, wherein the concentration of the first-stage iron and aluminum removal underflow is 29%; the secondary CCD washing overflow liquid is reused as water to dilute the first-stage iron and aluminum removal underflow, and then reused to the first-stage CCD washing section and synergistically precipitated with the pre-neutralized slurry, the volume ratio of the added water to the volume of the first-stage iron and aluminum removal underflow is 1.3, and the concentration of the first-stage iron and aluminum removal underflow reused after dilution with water meets 5-8%; after synergistic sedimentation, the CCD underflow is derived from the sixth-stage CCD washing section, and the CCD underflow is subjected to tailings neutralization treatment (adjusting pH=7 by adding lime milk), and then subjected to filter press treatment, and finally the tailings are discharged.

[0058] (3) After the second stage iron removal and aluminum treatment, the second stage iron removal and aluminum underflow and the second stage iron removal and aluminum overflow are obtained. The second stage iron removal and aluminum underflow are reused and the cyclic leaching process is carried out again. The residual temperature and residual acid of the high-pressure acid leaching slurry and the refluxed second stage iron removal and aluminum underflow are used for cyclic leaching. The second stage iron removal and aluminum overflow are treated with MHP.

[0059] Example 5

[0060] A method for reducing the nickel and cobalt content in tailings by hydrometallurgical processing of laterite nickel ore comprises the following steps:

[0061] (1) A high-pressure leaching slurry of laterite nickel ore is sequentially subjected to a circulating leaching treatment and a pre-neutralization treatment to obtain a pre-neutralized slurry, wherein the circulating leaching treatment controls the pH value to be less than 1.5, and the pre-neutralization treatment controls the pH value to be 1.8 to 2.2; then a 6-stage CCD washing is performed to obtain a CCD overflow liquid; wherein the pH value of the first-stage CCD washing section of the multi-stage CCD washing is controlled to be 2.2 to 2.5, and the pH value of the sixth-stage CCD washing section is controlled to be 4.5 to 4.7.

[0062] (2) The CCD overflow is subjected to a first-stage iron and aluminum removal treatment (controlling pH=3.5-3.8) and a second-stage iron and aluminum removal treatment (controlling pH=4.8-5.0) in sequence, wherein the concentration of the first-stage iron and aluminum removal underflow is 29%; it is directly reused in the second-stage CCD washing section without dilution with water; after coordinated sedimentation, the CCD underflow is derived from the sixth-stage CCD washing section to obtain the CCD underflow, which is subjected to tailings neutralization treatment (adjusting pH=7 by adding lime milk) and then subjected to filter press treatment, and finally the tailings are discharged.

[0063] (3) After the second stage iron removal and aluminum treatment, the second stage iron removal and aluminum underflow and the second stage iron removal and aluminum overflow are obtained. The second stage iron removal and aluminum underflow are reused and the cyclic leaching process is carried out again. The residual temperature and residual acid of the high-pressure acid leaching slurry and the refluxed second stage iron removal and aluminum underflow are used for cyclic leaching. The second stage iron removal and aluminum overflow are treated with MHP.

[0064] Comparative Example 1

[0065] A laterite nickel ore hydrometallurgical method comprises the following steps:

[0066] (1) A high-pressure leaching slurry of laterite nickel ore is sequentially subjected to a circulating leaching treatment and a pre-neutralization treatment to obtain a pre-neutralized slurry, wherein the circulating leaching treatment controls the pH value to be less than 1.5, and the pre-neutralization treatment controls the pH value to be 1.8 to 2.2; then a 6-stage CCD washing is performed to obtain a CCD overflow liquid; wherein the pH value of the first-stage CCD washing section of the multi-stage CCD washing is controlled to be 2.2 to 2.5, and the pH value of the sixth-stage CCD washing section is controlled to be 4.5 to 4.7.

[0067] (2) The CCD overflow is sequentially subjected to a first-stage iron and aluminum removal treatment (controlling pH=3.5-3.8) and a second-stage iron and aluminum removal treatment (controlling pH=4.8-5.0); the first-stage iron and aluminum removal underflow is directly discharged and washed separately without being reused; the pre-neutralized slurry directly enters the first-stage CCD washing section of the multi-stage CCD washing, and the CCD underflow is obtained by being discharged from the sixth-stage CCD washing section. After the CCD underflow is subjected to tailings neutralization treatment (adjusting pH=7 by adding lime milk), it is subjected to filter pressing treatment. The filter residue obtained by the filter pressing is mixed with the tailings after washing with the first-stage iron and aluminum removal underflow, and then discharged as the final tailings.

[0068] (3) After the second stage iron removal and aluminum treatment, the second stage iron removal and aluminum underflow and the second stage iron removal and aluminum overflow are obtained. The second stage iron removal and aluminum underflow are reused and the cyclic leaching process is carried out again. The residual temperature and residual acid of the high-pressure acid leaching slurry and the refluxed second stage iron removal and aluminum underflow are used for cyclic leaching. The second stage iron removal and aluminum overflow are treated with MHP.

[0069] The nickel and cobalt contents in the tailings obtained by the filter press treatment in step (2) in the above-mentioned embodiment and comparative example were tested, and the test results are shown in Table 2.

[0070] Table 2 Statistics of nickel and cobalt contents in tailings obtained from Examples 1 to 5 and Comparative Example 1

[0071]

[0072]

[0073] Note: “ / ” indicates no relevant operation is performed; “ND” indicates that measurement cannot be performed.

[0074] From the statistical results of Table 2, it can be seen that in Examples 1 to 3, the aforementioned method is adopted to synergistically settle the iron-aluminum slag in the first stage of the iron-aluminum removal bottom flow and the tailings in the pre-neutralized slurry, and the nickel-cobalt content in the discharged tailings is significantly reduced; at the same time, in the process of recycling a section of the iron-aluminum-containing bottom flow for multi-stage CCD washing treatment, the earlier the stage to which the bottom flow is recycled, the better the washing effect, and the less the content of nickel ions and cobalt ions in the resulting tailings. In Example 4, due to the direct recycling of the diluted section of the iron-aluminum removal bottom flow to the first-stage CCD washing section, there are too many floating objects in the first-stage CCD washing section, which seriously affects the stability of the multi-stage CCD washing, causing the entire process to be forced to stop. In Example 5, due to the direct recycling of a section of the iron-aluminum removal bottom flow with a concentration of 29% to the second-stage CCD washing section without dilution with water, the recycling pipeline is blocked, which affects the stability of the multi-stage CCD washing, causing the entire process to be forced to stop.

[0075] The present invention illustrates the detailed structural features of the present invention through the above embodiments, but the present invention is not limited to the above detailed structural features, that is, it does not mean that the present invention must rely on the above detailed structural features to be implemented. Those skilled in the art should understand that any improvement of the present invention, equivalent replacement of the components selected by the present invention, addition of auxiliary components, selection of specific methods, etc., all fall within the protection scope and disclosure scope of the present invention.

[0076] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, a variety of simple modifications can be made to the technical solution of the present invention, and these simple modifications all belong to the protection scope of the present invention.

[0077] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any suitable manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0078] In addition, various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for reducing the nickel and cobalt content in tailings by hydrometallurgical processing of laterite nickel ore, characterized in that: The steps include: (1) taking a leached slurry obtained by hydrometallurgy of laterite nickel ore, sequentially performing a cyclic leaching treatment and a pre-neutralization treatment to obtain a pre-neutralized slurry, and then performing a multi-stage CCD washing to obtain a CCD overflow liquid; (2) The CCD overflow liquid is subjected to first-stage and second-stage iron and aluminum removal in sequence, and the obtained first-stage iron and aluminum removal underflow is recycled to the multi-stage CCD washing, and is synergistically settled with the pre-neutralized slurry to obtain a CCD underflow, which is then subjected to tailings neutralization and filter press treatment in sequence to discharge the tailings.

2. The method for reducing the nickel and cobalt content in tailings by hydrometallurgical processing of laterite nickel ore according to claim 1, characterized in that: In step (1), the process conditions of the cyclic leaching treatment are: controlling the pH value to be less than 1.

5.

3. The method for reducing the nickel and cobalt content in tailings by hydrometallurgical processing of laterite nickel ore according to claim 1, characterized in that: In step (1), the process conditions of the pre-neutralization treatment are: controlling pH=1.8-2.

2.

4. The method for reducing the nickel and cobalt content in tailings by hydrometallurgical processing of laterite nickel ore according to claim 1, characterized in that: In step (1), the process conditions of the multi-stage CCD washing are: controlling pH=2.2-4.

7.

5. The method for reducing the nickel and cobalt content in tailings by hydrometallurgical processing of laterite nickel ore according to claim 1, characterized in that: In step (2), the process conditions for the first stage of iron and aluminum removal are: controlling the pH to be 3.5-3.8, and the process conditions for the second stage of iron and aluminum removal are: controlling the pH to be 4.8-5.

0.

6. The method for reducing the nickel and cobalt content in tailings by hydrometallurgical processing of laterite nickel ore according to claim 1, characterized in that: The number of stages of the multi-stage CCD washing in step (1) is 2 to 6, the pre-neutralized slurry in step (2) enters the first stage of the multi-stage CCD washing, and the underflow of the first stage of iron and aluminum removal is recycled to the i-th stage of the multi-stage CCD washing, where i≥2 and is an integer.

7. The method for reducing the nickel and cobalt content in tailings by hydrometallurgical processing of laterite nickel ore according to claim 6, characterized in that: The first stage of iron and aluminum removal bottom flow is diluted with water before reuse, and the ratio of the volume of the added water to the volume of the first stage of iron and aluminum removal bottom flow is controlled to be greater than 1.

2.

8. The method for reducing the nickel and cobalt content in tailings by hydrometallurgical processing of laterite nickel ore according to claim 7, characterized in that: The concentration of the first stage of de-ironization and aluminum bottom flow before dilution with water is 25-30%, and the concentration of the first stage of de-ironization and aluminum bottom flow after dilution with water for reuse is 5-8%.

9. The method for reducing the nickel and cobalt content in tailings by hydrometallurgical processing of laterite nickel ore according to claim 1, characterized in that: In step (2), the specific step of neutralizing the tailings includes: adding lime milk to make the system pH = 6.8-7.

2.

10. The method for reducing the nickel and cobalt content in tailings by hydrometallurgy of laterite nickel ore according to claim 1, characterized in that: Also includes: In step (2), the second stage of deironing aluminum obtains a second stage of deironing aluminum underflow and a second stage of deironing aluminum overflow. The second stage of deironing aluminum underflow is reused and subjected to cyclic leaching treatment again, and the second stage of deironing aluminum overflow is subjected to MHP sedimentation treatment.

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