Method for recovering aluminum and scandium

Abstract

The present application provides a method for recovering aluminum and scandium. The method comprises the following steps: providing iron-aluminum residue generated in a leaching process for lateritic nickel ore; performing alkaline leaching, involving subjecting the iron-aluminum residue to atmospheric or pressure leaching by using an alkaline leaching agent, followed by separation and washing, so as to obtain scandium-containing residue, an aluminum-containing first filtrate and an aluminum-containing first washing liquid; and preparing an aluminum product. In the present application, a nickel-cobalt hydroxide product is produced from lateritic nickel ore by means of a hydrometallurgical process, and the iron-aluminum residue, as a raw material, is subjected to leaching using an alkaline leaching agent, solid-liquid separation, and washing. The leaching residue is washed to obtain scandium-containing residue, which can be used as a high-quality scandium smelting raw material; and the aluminum-containing first filtrate and aluminum-containing first washing liquid are treated by using the procedure of the Bayer process to obtain an aluminum hydroxide or aluminum oxide product. The present application achieves resource recovery and utilization of associated valuable metals, i.e., aluminum and scandium, without affecting the production of a major valuable metal product in a hydrometallurgical process of lateritic nickel ore.

Description

Process for recycling aluminum and scandium

[0001] This application claims priority to the Chinese patent application filed with the China Patent Office on July 6, 2023, with application number 202310830430.5 and invention name “Process for Recycling Aluminum and Scandium”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application belongs to the technical field of hydrometallurgy, and more specifically, relates to a process for recovering aluminum and scandium. Background Art

[0003] For some time, the processing of laterite nickel ore was limited to extracting nickel and cobalt from it, using hydrometallurgical technology to produce nickel and cobalt hydroxide, ignoring the small amounts of other valuable metal elements contained in the laterite nickel ore, such as aluminum and scandium. The aluminum content in the raw ore used to produce nickel and cobalt hydroxide through high-pressure acid leaching of laterite nickel ore is generally 2% to 6%. After leaching, some of the aluminum enters the leaching residue, while the remaining part enters the leachate and is precipitated into the ferroaluminum slag during the iron and aluminum removal stage. The scandium content in laterite nickel ore is generally 30g / t to 100g / t. More than 90% of the scandium is leached and gradually precipitated during subsequent production processes, with the majority entering the iron and aluminum removal slag and nickel and cobalt hydroxide products.

[0004] Existing technologies for recovering scandium from laterite nickel ore produce large slag volumes, resulting in high transportation and production costs. Furthermore, they fail to effectively recover the valuable aluminum present in the laterite nickel ore. Consequently, the ferroaluminum slag is often discarded as waste, preventing the effective recovery and utilization of the aluminum and scandium valuable metals in the laterite nickel ore, resulting in a significant waste of resources. Technical issues

[0005] The purpose of the embodiments of the present application is to provide a process for recovering aluminum and scandium, so as to solve the technical problem in the prior art that valuable metals such as aluminum and scandium in laterite nickel ore cannot be fully recovered and utilized. Technical Solutions

[0006] To achieve the above-mentioned purpose, the technical solution adopted in this application is to provide a process for recycling aluminum and scandium, comprising the following steps:

[0007] Provide the iron-aluminum slag produced in the laterite nickel ore leaching process;

[0008] Alkaline leaching: using an alkaline leaching agent to leach, separate and wash the iron-aluminum slag at normal pressure or pressure to obtain a scandium-containing slag and a first filtrate and a first washing liquid containing aluminum;

[0009] Preparation of aluminum products: The first filtrate and the first washing liquid are treated through the Bayer process to obtain aluminum hydroxide or aluminum oxide products.

[0010] In one embodiment, the alkaline leaching agent includes a combination of one or more of sodium hydroxide, sodium carbonate, potassium hydroxide, and potassium carbonate;

[0011] And / or, the leaching temperature in the alkaline leaching step is 25° C. to 280° C., and the reaction time is 10 min to 6 h.

[0012] In one embodiment, providing the iron-aluminum slag produced in the laterite nickel ore leaching process specifically comprises the following steps:

[0013] Acid leaching: Acid leaching is performed on the laterite nickel ore to obtain leached slurry;

[0014] Pre-neutralization: pre-neutralizing the leached slurry to obtain a neutralized slurry;

[0015] CCD countercurrent washing: performing CCD countercurrent washing on the neutralized slurry to obtain CCD underflow slurry and CCD overflow liquid;

[0016] One-stage iron and aluminum removal: the CCD overflow liquid is subjected to a one-stage iron and aluminum removal treatment to obtain a one-stage iron and aluminum removal slurry, and the one-stage iron and aluminum removal slurry is subjected to a thickening treatment to obtain a one-stage iron and aluminum removal overflow liquid and a one-stage iron and aluminum removal underflow slurry;

[0017] Filter pressing and washing: the iron-aluminum removal bottom flow slurry of the first stage is subjected to filter pressing and washing to obtain iron-aluminum slag.

[0018] In one embodiment, the filter pressing and washing step further produces a second filtrate and a second washing liquid;

[0019] The process also includes the following steps:

[0020] Mixing the first stage iron and aluminum removal overflow liquid, the second filtrate and the second washing liquid to obtain a mixed liquid;

[0021] The mixed solution is sequentially subjected to the steps of two-stage iron and aluminum removal and thickening, one-stage nickel and cobalt precipitation and thickening, two-stage nickel and cobalt precipitation and thickening, and product filter pressing to obtain nickel cobalt hydroxide product.

[0022] In one embodiment, the washing water used in the filter pressing and washing step is new water produced or overflow liquid obtained after two-stage nickel and cobalt precipitation and thickening steps.

[0023] In one embodiment, the acid leaching step specifically includes: pressurized acid leaching or atmospheric pressure acid leaching of the laterite nickel ore to obtain the leached slurry.

[0024] In one embodiment, the following steps are also included:

[0025] Tailings neutralization: the CCD underflow slurry is mixed with the overflow liquid of the second stage nickel and cobalt precipitation, and then subjected to tailings neutralization, thickening and filter pressing treatment to obtain tailings filter cake and wastewater.

[0026] In one embodiment, the reaction time of the pre-neutralization step is between 1 h and 8 h, and the reaction temperature is between 50° C. and 95° C.;

[0027] And / or, the pre-neutralization step controls the endpoint pH value to be between 1.8 and 3.0.

[0028] In one embodiment, the reaction time of the iron and aluminum removal step is between 1 hour and 8 hours, and the reaction temperature is between 30° C. and 90° C.;

[0029] And / or, the end point pH value of the iron and aluminum removal step is controlled to be between 3.2 and 4.2.

[0030] In one embodiment, a combination of one or more of a sodium neutralizer, a calcium neutralizer, and a magnesium neutralizer is used in the pre-neutralization step and the first iron and aluminum removal step.

[0031] In one embodiment, the sodium neutralizing agent includes a combination of one or more of sodium hydroxide, sodium carbonate, and sodium bicarbonate;

[0032] And / or, the calcareous neutralizer includes one or more of calcium carbonate, calcium oxide, calcium hydroxide, and limestone ore;

[0033] And / or, the magnesium neutralizer includes a combination of one or more of magnesium carbonate, magnesium oxide, magnesium hydroxide, and magnesite. Beneficial effects

[0034] The beneficial effects of this application include: producing nickel-cobalt hydroxide products by applying a hydrometallurgical process to laterite nickel ore, using the ferroaluminum slag therein as raw material, leaching, solid-liquid separation, and washing the ferroaluminum slag with an alkaline leaching agent, and obtaining scandium-containing slag after washing, thereby achieving scandium enrichment in the ferroaluminum slag. The scandium slag obtained in this application is of high grade and can be used as a high-quality scandium smelting raw material; and obtaining aluminum hydroxide or aluminum oxide products after the aluminum-containing first filtrate and first washing liquid are treated through the Bayer process. This application achieves the resource recovery and utilization of the associated valuable metals aluminum and scandium without affecting the production of the main valuable metal product (nickel-cobalt hydroxide) in the laterite nickel ore hydrometallurgical process. BRIEF DESCRIPTION OF THE DRAWINGS

[0035] In order to more clearly illustrate the technical solutions in the embodiments of the present application, the following briefly introduces the drawings required for use in the embodiments or descriptions of the prior art. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0036] FIG1 is a schematic flow chart of a process method according to an embodiment of the present application;

[0037] FIG2 is a schematic flow chart of step S1;

[0038] FIG3 is a schematic diagram of a complete process of the process method according to an embodiment of the present application;

[0039] FIG4 is a schematic diagram of a process for preparing nickel cobalt hydroxide according to an embodiment of the present application. Modes for Carrying Out the Invention

[0040] In order to make the technical problems, technical solutions and beneficial effects to be solved by this application more clearly understood, the present application is further described in detail below in conjunction with the embodiments. It should be understood that the specific embodiments described herein are only used to explain this application and are not intended to limit this application.

[0041] In this application, the term "and / or" describes the relationship between associated objects, indicating that three possible relationships exist. For example, A and / or B can represent: A exists alone, A and B exist simultaneously, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0042] In this application, "at least one" means one or more, "more than one" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items.

[0043] It should be understood that in the various embodiments of the present application, the size of the serial numbers of the above-mentioned processes does not mean the order of execution. Some or all of the steps can be executed in parallel or sequentially. The execution order of each process should be determined by its function and internal logic, and should not constitute any limitation on the implementation process of the embodiments of the present application.

[0044] The terms used in the embodiments of the present application are for the purpose of describing specific embodiments only and are not intended to limit the present application. The singular forms "a", "an", "the" and "the" used in the embodiments of the present application and the appended claims are also intended to include plural forms unless the context clearly indicates otherwise.

[0045] The weights of the relevant components mentioned in the examples of this application may not only refer to the specific content of each component, but also represent the weight ratio between the components. Therefore, as long as the content of the relevant components is proportionally enlarged or reduced according to the examples of this application, it is within the scope disclosed in the examples of this application. Specifically, the mass described in the examples of this application may be a mass unit known in the chemical industry, such as μg, mg, g, kg, etc.

[0046] The terms "first" and "second" are used solely for descriptive purposes to distinguish objects, such as substances, from one another and should not be understood to indicate or imply relative importance or to implicitly specify the quantity of the technical features being referred to. For example, without departing from the scope of the embodiments of this application, a first XX may also be referred to as a second XX, and similarly, a second XX may also be referred to as a first XX. Thus, features defined as "first" or "second" may explicitly or implicitly include one or more of such features.

[0047] The application provides a process for recovering aluminum and scandium from the hydrometallurgical process of laterite nickel ore, as shown in Figures 1 and 2, comprising the following steps:

[0048] S1 provides the iron-aluminum slag produced in the laterite nickel ore leaching process;

[0049] S2 alkaline leaching: using an alkaline leaching agent to leach, separate and wash the iron-aluminum slag at normal pressure or pressure to obtain a scandium-containing slag and a first filtrate and a first washing liquid containing aluminum;

[0050] S3 aluminum product preparation: The first filtrate and the first washing liquid are treated by the Bayer process to obtain aluminum hydroxide or aluminum oxide products.

[0051] The process for recovering aluminum and scandium provided in the embodiments of the present application involves alkaline leaching, separation, and washing of the ferroaluminum slag obtained from the laterite nickel ore leaching process to produce a scandium-containing slag and an aluminum-containing first filtrate and first wash liquor. The alkaline leaching step separates the aluminum and scandium. Further treatment of the first filtrate and first wash liquor through the Bayer process yields aluminum hydroxide or alumina products. The scandium-containing slag is of high grade and can be directly used as a high-quality scandium smelting raw material. This application achieves resource recovery and utilization of the associated valuable metals aluminum and scandium without affecting the production of the primary valuable metal product (nickel and cobalt hydroxide) in the laterite nickel ore hydrometallurgy process. Furthermore, the preparation method of the present application is simple, making it conducive to industrial utilization.

[0052] In one embodiment, the alkaline leaching agent includes a combination of one or more of sodium hydroxide, sodium carbonate, potassium hydroxide, and potassium carbonate. Specifically, the present application uses sodium hydroxide to leach the ferroaluminum slag, which has a strong enough alkalinity to separate the aluminum therein and obtain the scandium-containing slag.

[0053] In one embodiment, the leaching temperature in the alkaline leaching step is 25° C. to 280° C., specifically 25° C., 50° C., 75° C., 100° C., 125° C., 150° C., 175° C., 200° C., 225° C., 250° C., 270° C., 280° C., etc., and the reaction time is 10 min to 6 h, specifically 10 min, 20 min, 30 min, 40 min, 50 min, 60 min, 1.2 h, 1.5 h, 2.7 h, 3 h, 3.2 h, 3.5 h, 3.8 h, 4 h, 4.2 h, 4.5 h, 4.6 h, 4.8 h, 5 h, 5.2 h, 5.5 h, 5.8 h, 6 h, etc. Under these conditions, a higher-grade scandium-containing slag can be obtained.

[0054] In one embodiment, as shown in Figures 1 and 3, the S2 alkaline leaching step also includes a thickening operation, that is, a thickening washing operation is performed after the alkaline leaching and before the filter press washing. The overflow liquid enters the Bayer process aluminum extraction process, and the underflow enters the filter press washing process. The resulting filter residue is a scandium-containing residue, and the resulting first filtrate and first washing liquid enter the Bayer process aluminum extraction process together with the overflow liquid to prepare aluminum hydroxide or alumina products.

[0055] In one embodiment, as shown in FIG2 , the step S1 of providing the iron-aluminum slag produced in the laterite nickel ore leaching process specifically includes the following steps:

[0056] S11 acid leaching: acid leaching the laterite nickel ore to obtain ore pulp;

[0057] S12 pre-neutralization: pre-neutralizing the slurry to obtain a neutralized slurry;

[0058] S13 CCD countercurrent washing: performing CCD countercurrent washing on the neutralized slurry to obtain CCD underflow slurry and CCD overflow liquid;

[0059] S14: One-stage iron and aluminum removal: The CCD overflow liquid is subjected to a one-stage iron and aluminum removal treatment to obtain a one-stage iron and aluminum removal slurry, and the one-stage iron and aluminum removal slurry is subjected to a thickening treatment to obtain a one-stage iron and aluminum removal overflow liquid and a one-stage iron and aluminum removal underflow slurry;

[0060] S15 filter press washing: filter press washing the first stage of iron and aluminum removal underflow slurry to obtain iron and aluminum slag;

[0061] First, the laterite nickel ore is leached by acid leaching to obtain slurry; then the slurry is pre-neutralized to obtain neutralized slurry, and then subjected to CCD countercurrent washing, a stage of iron and aluminum removal, and filter press washing steps. Finally, ferroaluminum slag is obtained. Similar to the wet smelting process, aluminum and scandium can be enriched in the ferroaluminum slag without affecting the preparation of aluminum products, facilitating subsequent recycling.

[0062] In one embodiment, as shown in FIG3 and FIG4 , a second filtrate and a second washing liquid are also obtained in the filter pressing and washing step S15;

[0063] The above process also includes the following steps:

[0064] Mixing the first stage iron and aluminum removal overflow liquid, the second filtrate and the second washing liquid to obtain a mixed liquid;

[0065] The mixed liquor is sequentially subjected to a second stage of iron and aluminum removal and thickening, a first stage of nickel and cobalt precipitation and thickening, a second stage of nickel and cobalt precipitation and thickening, and a product filter press to obtain a nickel and cobalt hydroxide product. This achieves the recovery and utilization of aluminum and scandium without affecting the hydrometallurgical smelting process for extracting the main product, nickel and cobalt hydroxide, from the laterite nickel ore.

[0066] In one embodiment, the washing water used in the filter press washing step S14 is new production water or overflow liquid after the second stage nickel and cobalt precipitation and thickening step. It should be noted that new production water is the production water used in industrial production, while the thickened overflow liquid is the overflow liquid after the thickening washing operation. The advantage of using new production water is that it can avoid the introduction of new impurities and wash out the solution attached to the filter residue. The advantage of using the overflow liquid after the second stage nickel and cobalt precipitation and thickening process is that it can save water.

[0067] In one embodiment, as shown in Figures 1 and 3, the SO3 aluminum product is prepared by subjecting the first filtrate and the first washing liquid to the Bayer process to produce aluminum hydroxide or aluminum oxide products. The Bayer process for aluminum extraction is a widely used industrial chemical process for producing aluminum oxide from bauxite. This process will not be described in detail in this application. In this way, aluminum hydroxide or aluminum oxide products can be produced without affecting the production of nickel and cobalt hydroxide from laterite nickel ore, thereby achieving the recovery and utilization of the valuable metallic aluminum in the laterite nickel ore.

[0068] The acid leaching step S11 specifically includes acid leaching the laterite nickel ore to obtain a slurry. In one embodiment, the laterite nickel ore is pressure-leached using sulfuric acid. In other embodiments, the laterite nickel ore may be treated using an atmospheric pressure acid leaching process or a combined atmospheric pressure-pressure acid leaching process.

[0069] In one embodiment, the laterite nickel ore is limonite-type laterite nickel ore, eluvial-type laterite nickel ore, or a mixture of the two minerals.

[0070] In step S12, pre-neutralization is performed on the leached slurry to obtain a neutralized slurry, with the endpoint pH value controlled to be between 1.8 and 3.0, specifically, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, etc. In one embodiment, limestone is used to neutralize excess sulfuric acid from the acid leaching step S01, with the endpoint pH value controlled to be between 1.8 and 3.0, specifically, 1.8, 2.0, 2.2, 2.4, 2.6, 2.8, 3.0, etc. In other embodiments, a combination of one or more sodium neutralizers, calcium neutralizers, and magnesium neutralizers may also be used.

[0071] In one embodiment, the reaction time of the pre-neutralization in step S12 is 1 h to 8 h, specifically 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, etc., and the reaction temperature is 50°C to 95°C, specifically 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, 95°C, etc.; under these conditions, the sulfuric acid and the neutralizer can fully react to neutralize the excess sulfuric acid.

[0072] In one embodiment, the CCD countercurrent washing step specifically includes: performing CCD washing on the neutralized slurry, with the number of washing stages being 2 to 6 (specifically, 2, 3, 4, 5, or 6), and a washing ratio being 2 to 4 (specifically, 2, 2.2, 2.4, 2.6, 2.8, 3.0, 3.2, 3.4, 3.6, 3.8, 4.0, etc.). The underflow after the CCD washing is neutralized with lime milk and then discharged.

[0073] In step S14, the CCD overflow liquid undergoes a first-stage iron and aluminum removal process, controlling the endpoint pH value to between 3.2 and 4.2 (e.g., 3.3, 3.5, 3.7, 3.9, 4.0, 4.1, 4.2, etc.) to obtain a first-stage iron and aluminum removal slurry. The first-stage iron and aluminum removal slurry undergoes a thickening process to obtain a first-stage iron and aluminum removal overflow liquid and a first-stage iron and aluminum removal underflow slurry. Specifically, a first-stage iron and aluminum removal reaction is performed using a neutralizer to adjust the pH value, controlling the endpoint pH value to between 3.2 and 4.2 (e.g., 3.3, 3.5, 3.7, 3.9, 4.0, 4.1, 4.2, etc.), followed by a thickening process. The iron and aluminum in the slurry are removed to obtain a nickel-cobalt-containing solution, facilitating the subsequent production of nickel-cobalt hydroxide products.

[0074] In one embodiment, the reaction time for removing iron and aluminum in step S14 is 1 h to 8 h (specifically 1 h, 2 h, 3 h, 4 h, 5 h, 6 h, 7 h, 8 h, etc.), and the reaction temperature is 30°C to 90°C (30°C, 35°C, 40°C, 45°C, 50°C, 55°C, 60°C, 65°C, 70°C, 75°C, 80°C, 85°C, 90°C, etc.); under these conditions, iron and aluminum can be removed to a large extent.

[0075] In one embodiment, a thickening step is also included before the S15 filter press washing step, that is, the slurry after the first stage of iron and aluminum removal is thickened and washed, the overflow liquid enters the second stage of iron and aluminum removal process, the bottom flow enters the filter press washing, and the resulting filter residue enters the alkaline leaching process to extract aluminum and scandium, and the resulting second filtrate and second washing liquid enter the second stage of iron and aluminum removal process together with the overflow liquid.

[0076] In one embodiment, as shown in FIG1 and FIG4 , the following steps are further included:

[0077] Tailings neutralization: After the CCD underflow slurry is mixed with the overflow liquid of the second stage nickel and cobalt precipitation, the tailings are neutralized, thickened and filtered to obtain tailings filter cake and wastewater.

[0078] In one embodiment, a combination of one or more sodium neutralizers, calcium neutralizers, and magnesium neutralizers is used in the pre-neutralization step and the first iron and aluminum removal step to adjust the pH value for pre-neutralization and iron and aluminum removal reactions.

[0079] In one embodiment, the sodium neutralizing agent includes a combination of one or more of sodium hydroxide, sodium carbonate, and sodium bicarbonate;

[0080] The calcium neutralizer includes one or more combinations of calcium carbonate, calcium oxide, calcium hydroxide, and limestone ore;

[0081] The magnesium neutralizer includes one or more combinations of magnesium carbonate, magnesium oxide, magnesium hydroxide, and magnesite.

[0082] The following describes the details in conjunction with specific embodiments.

[0083] Example 1

[0084] The slurry from pressure acid leaching of laterite nickel ore is pre-neutralized with limestone at 80°C, an endpoint pH of 2.0, and a reaction time of 4 hours. The pre-neutralized, neutralized slurry is then washed countercurrently with a CCD. The overflow then undergoes a primary iron and aluminum removal process using limestone as the neutralizer, an endpoint pH of 4.0, and a reaction time of 3 hours. This primary iron and aluminum removal process produces an ferroaluminum slag, which is then washed and leached at atmospheric pressure with sodium hydroxide at 95°C for 1 hour. After leaching, the solid-liquid separation and washing are performed to produce a first filtrate containing aluminum, a first wash solution, and a slag containing scandium.

[0085] After the above process, the mixed solution of the first filtrate and the first washing solution and the scandium-containing slag were detected and analyzed by an ICP (Inductively Coupled Plasma) emission spectrometer using a standard curve method to obtain the following:

[0086] The aluminum content in the mixed solution of the first filtrate and the first washing solution was 9.8 g / L, and the scandium content in the scandium-containing slag was 0.28%.

[0087] Example 2

[0088] The slurry from pressure acid leaching of laterite nickel ore is pre-neutralized with limestone at 80°C, an endpoint pH of 2.2, and a reaction time of 3 hours. The pre-neutralized slurry is then washed countercurrently with a CCD filter. The overflow then undergoes a primary iron and aluminum removal process using sodium carbonate as the neutralizer, an endpoint pH of 3.8, and a reaction time of 3 hours. This primary iron and aluminum removal process produces an ferroaluminum slag, which is then washed and leached at atmospheric pressure with sodium hydroxide at 80°C for 2 hours. After leaching, the solid-liquid separation and washing are performed to produce a first filtrate containing aluminum, a first washing solution, and a slag containing scandium.

[0089] After the above process, the mixed solution of the first filtrate and the first washing solution and the scandium-containing slag were detected and analyzed by ICP emission spectrometer using the standard curve method to obtain:

[0090] The aluminum content in the mixed solution of the first filtrate and the first washing solution was 16.5 g / L, and the scandium content in the scandium-containing slag was 0.42%.

[0091] Example 3

[0092] The slurry from pressure acid leaching of laterite nickel ore is pre-neutralized with limestone at 80°C, an endpoint pH of 2.5, and a reaction time of 5 hours. The pre-neutralized, neutralized slurry is then washed countercurrently with a CCD. The overflow then undergoes a primary iron and aluminum removal process using magnesium oxide as the neutralizer, with an endpoint pH of 4.2 and a reaction time of 3 hours. This primary iron and aluminum removal process produces an ferroaluminum slag, which is then washed and leached at atmospheric pressure with sodium hydroxide at 60°C for 3 hours. After leaching, the solid-liquid separation and washing are performed to produce a first filtrate containing aluminum, a first wash solution, and a slag containing scandium.

[0093] After the above process, the mixed solution of the first filtrate and the first washing solution and the scandium-containing slag were detected and analyzed by ICP emission spectrometer using the standard curve method to obtain:

[0094] The aluminum content in the mixed solution of the first filtrate and the first washing solution was 13.1 g / L, and the scandium content in the scandium-containing slag was 0.54%.

[0095] The process of this application can effectively recover aluminum and scandium from ferroaluminum slag. The recovered aluminum can be directly used to produce aluminum hydroxide or alumina products through the Bayer process. The enriched scandium is of high grade and can be used as a raw material for deep processing into scandium products. This achieves the recovery of aluminum and scandium from the laterite nickel ore hydrometallurgical process without affecting the production of the main product, nickel cobalt hydroxide. It effectively utilizes the production waste ferroaluminum slag, thereby achieving efficient resource utilization and bringing certain economic benefits.

[0096] In the above embodiments, the description of each embodiment has its own focus. For parts that are not described or recorded in detail in a certain embodiment, reference can be made to the relevant description of other embodiments.

[0097] The above-described embodiments are only used to illustrate the technical solutions of the present application, rather than to limit them. Although the present application has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. These modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present application, and should all be included in the scope of protection of the present application.

Claims

1. A process for recovering aluminum and scandium, characterized in that: The steps include: Provide the iron-aluminum slag produced in the laterite nickel ore leaching process; Alkaline leaching: using an alkaline leaching agent to leach, separate and wash the iron-aluminum slag at normal pressure or pressure to obtain a scandium-containing slag and a first filtrate and a first washing liquid containing aluminum; Preparation of aluminum products: The first filtrate and the first washing liquid are treated by the Bayer process to obtain aluminum hydroxide or aluminum oxide products.

2. The process according to claim 1, characterized in that: The alkaline leaching agent includes a combination of one or more of sodium hydroxide, sodium carbonate, potassium hydroxide and potassium carbonate; and / or The leaching temperature in the alkaline leaching step is 25° C. to 280° C., and the reaction time is 10 min to 6 h.

3. The process according to claim 1, characterized in that: Providing the iron-aluminum slag produced in the laterite nickel ore leaching process specifically includes the following steps: Acid leaching: Acid leaching is performed on the laterite nickel ore to obtain leached slurry; Pre-neutralization: pre-neutralizing the leached slurry to obtain a neutralized slurry; CCD countercurrent washing: performing CCD countercurrent washing on the neutralized slurry to obtain CCD underflow slurry and CCD overflow liquid; One-stage iron and aluminum removal: the CCD overflow liquid is subjected to one-stage iron and aluminum removal treatment to obtain one-stage iron and aluminum removal slurry, and the one-stage iron and aluminum removal slurry is subjected to thickening treatment to obtain one-stage iron and aluminum removal overflow liquid and one-stage iron and aluminum removal underflow slurry; Filter pressing and washing: the iron-aluminum removal underflow slurry of the first stage is subjected to filter pressing and washing to obtain iron-aluminum slag.

4. The process according to claim 3, characterized in that: The filter pressing and washing step also produces a second filtrate and a second washing liquid; The process also includes the following steps: The first stage iron and aluminum removal overflow liquid, the second filtrate and the second washing liquid are mixed to obtain a mixed liquid; The mixed solution is sequentially subjected to two-stage iron and aluminum removal and thickening, one-stage nickel and cobalt precipitation and thickening, two-stage nickel and cobalt precipitation and thickening, and product filter pressing steps to obtain a nickel and cobalt hydroxide product; and / or The washing water used in the filter pressing and washing step is new water produced or overflow liquid obtained after two-stage nickel and cobalt precipitation and thickening steps.

5. The process according to claim 3, characterized in that: The acid leaching step specifically includes: pressurized acid leaching or normal pressure acid leaching of the laterite nickel ore to obtain the leached slurry.

6. The process according to claim 3, characterized in that: The following steps are also included: Tailings neutralization: After the CCD underflow slurry is mixed with the overflow liquid of the second stage nickel and cobalt precipitation, tailings neutralization, thickening and filter pressing are performed to obtain tailings filter cake and wastewater.

7. The process according to claim 3, characterized in that: The reaction time of the pre-neutralization step is between 1h and 8h, and the reaction temperature is between 50°C and 95°C; And / or, the pre-neutralization step controls the endpoint pH value to be between 1.8 and 3.

0.

8. The process according to claim 3, characterized in that: The reaction time of the first iron and aluminum removal step is between 1h and 8h, and the reaction temperature is between 30°C and 90°C; And / or, the end point pH value of the iron and aluminum removal step is controlled to be between 3.2 and 4.

2.

9. The process according to any one of claims 3 to 7, characterized in that: In the pre-neutralization step and the first iron and aluminum removal step, a combination of one or more of a sodium neutralizer, a calcium neutralizer, and a magnesium neutralizer is used.

10. The process according to claim 9, characterized in that: The sodium neutralizing agent includes a combination of one or more of sodium hydroxide, sodium carbonate, and sodium bicarbonate; And / or, the calcium neutralizing agent includes one or more combinations of calcium carbonate, calcium oxide, calcium hydroxide, and limestone ore; And / or, the magnesium neutralizer includes a combination of one or more of magnesium carbonate, magnesium oxide, magnesium hydroxide, and magnesite.

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