Comprehensive recycling method for laterite nickel ore hydrometallurgical slag

Abstract

A comprehensive recycling method for laterite nickel ore hydrometallurgical slag. The method is mainly to perform operations such as acid leaching, alkali leaching, and calcining on laterite nickel ore hydrometallurgical slag, and in the process of recovering iron concentrates and / or iron phosphate products, sodium silicate, calcium sulfate, magnesium oxide, and aluminum oxide products can also be recovered, so that comprehensive recycling of the laterite nickel ore hydrometallurgical slag is achieved to the maximum extent, thereby achieving comprehensive development and utilization of laterite nickel ore resources; and the method results no three-waste emissions, the process is green and environment-friendly, and the method is simple and feasible, and is conducive to popularization and application.

Description

A comprehensive recycling method for laterite nickel ore hydrometallurgical slag Technical Field

[0001] The present application relates to the field of mineral metallurgy technology, specifically to the field of nickel hydrometallurgy technology, and in particular to a comprehensive recycling and utilization method of laterite nickel ore hydrometallurgy slag. Background Art

[0002] Nickel sulfide and nickel oxide deposits are the world's major nickel deposits. Nickel oxide deposits account for 70% of all terrestrial nickel reserves. Nickel oxide deposits are called laterite nickel ore because the ore's surface appears red due to iron oxidation. Based on their chemical composition, laterite nickel ore is divided into magnesia-silico-type and limonitic-type. Magnesia-silico-type laterite nickel ore has high nickel, silicon, and magnesium contents and low iron and cobalt contents, and is primarily produced through pyrometallurgical processes to produce ferronickel or nickel pig iron. Limonitic-type laterite nickel ore, on the other hand, has high iron and cobalt contents and low nickel and magnesium contents, and is primarily produced through hydrometallurgical processes to produce nickel-cobalt sulfide or nickel-cobalt hydroxide intermediates. However, limonitic-type laterite nickel ore accounts for 70% of all nickel reserves, leading to its development and utilization. Acid leaching and hydrometallurgical treatment of limonitic-type laterite nickel ore produces significant amounts of metallurgical slag, which contains nearly 50% iron, primarily in the form of hematite. The grade of such slag iron does not meet the metallurgical raw material standards of steel mills, and conventional processing methods make it difficult to utilize it as a resource.

[0003] The metallurgical slag produced by acid-leaching hydrometallurgical treatment of limonitic laterite nickel ore is currently primarily stored in dams or discharged into the deep sea, wasting resources and potentially polluting the environment. While some research has addressed the difficulty of treating and recycling hydrometallurgical slag from laterite nickel ore, these methods often employ limited recovery methods with limited success.

[0004] For example, CN109467101A discloses a process for preparing an aluminum-silicon solution by dissolving laterite-nickel ore smelting slag. The process involves alkali melting the laterite-nickel ore slag, ultrasonically enhancing the water leaching process, and adding Al(OH)3 as an aluminum source to adjust the silicon-aluminum molar ratio. This produces a crude aluminum-silicon solution mixed with water and slag. After filtration and liquid-solid separation, an aluminum-silicon solution with a specific molar ratio and a solid filter residue are obtained. However, this technical solution does not recover iron resources.

[0005] CN108910909A discloses a method for producing ZSM-5 molecular sieves from laterite nickel ore smelting waste. Based on the laterite nickel ore smelting waste, the ZSM-5 molecular sieve is produced through crushing and screening, alkali boiling extraction, centrifugal separation, hydrothermal crystallization, centrifugal washing, powder drying, demolding and roasting. Compared with the existing technology, the above technical solution uses alkali boiling extraction for nickel ore smelting waste, achieving effective extraction of Si-Al, avoiding multiple impurity removal steps, and significantly simplifying the process. However, the above technical solution does not recover iron resources.

[0006] CN114774685A discloses a method for treating limonitic laterite-nickel ore hydrometallurgical slag, wherein the limonitic laterite-nickel ore hydrometallurgical slag is dried, crushed, moist-grinded, and pelletized. The slag is then magnetized and roasted in a rotary kiln using high-volatile lignite as a reducing agent and a source of heating fuel. The discharged roasted ore is then subjected to wet weak magnetic separation after indirect air cooling. The iron concentrate after magnetic separation can be used as a sintering ironmaking raw material, thereby achieving resource utilization of a large amount of limonitic laterite-nickel ore hydrometallurgical slag and reducing the storage and discharge costs of the metallurgical slag and the impact on the environment. Although the above technical solution recovers iron resources, it does not recover resources such as silicon, aluminum, calcium, and magnesium, and does not achieve comprehensive recycling of the laterite-nickel ore hydrometallurgical slag.

[0007] Therefore, it is of great significance to develop a comprehensive recycling method for laterite nickel ore hydrometallurgical slag.

[0008] Summary of the Invention

[0009] The following is a summary of the subject matter described in detail herein. This summary is not intended to limit the scope of the claims.

[0010] In view of the problems existing in the prior art, the present application provides a comprehensive recycling and utilization method for laterite nickel ore hydrometallurgical slag. The comprehensive recycling and utilization method mainly performs acid leaching, alkali leaching, calcination and other operations on the laterite nickel ore hydrometallurgical slag. In the process of recovering iron concentrate and / or ferric phosphate products, sodium silicate, calcium sulfate, magnesium oxide and aluminum oxide products can also be recovered, thereby maximizing the comprehensive recycling and utilization of laterite nickel ore hydrometallurgical slag, thereby realizing the comprehensive development and utilization of laterite nickel ore resources; the comprehensive recycling and utilization method described in the present application does not discharge three wastes during the process, the process is green and environmentally friendly, the method is simple and feasible, and is conducive to promotion and application.

[0011] To achieve this goal, this application adopts the following technical solutions:

[0012] The purpose of this application is to provide a comprehensive recycling method for laterite nickel ore hydrometallurgical slag, which comprises the following steps:

[0013] (1) uniformly mixing laterite nickel ore hydrometallurgical slag with a first leaching agent and an oxidant to perform a first selective leaching, and obtaining a first leaching residue and a first leachate through a first solid-liquid separation;

[0014] (2) uniformly mixing the first leaching residue of step (1) with a second leaching agent to perform a second selective leaching, and obtaining a calcium sulfate product and a sodium silicate solution through a second solid-liquid separation;

[0015] (3) uniformly mixing the first leachate obtained in step (1) with a third leachant to perform a third selective leaching, and obtaining a metal hydroxide and a third leachate through a third solid-liquid separation;

[0016] (4) uniformly mixing the metal hydroxide of step (3) with a fourth leaching agent to perform a fourth selective leaching, and obtaining iron magnesium hydroxide and a sodium aluminate solution through a fourth solid-liquid separation, wherein the sodium aluminate solution is used to recover aluminum;

[0017] (5) uniformly mixing the iron-magnesium hydroxide of step (4) with a fifth leaching agent to perform a fifth selective leaching, and obtaining magnesium hydroxide leaching residue and an iron-containing leachate through a fifth solid-liquid separation; cooling the iron-containing leachate and diluting it with water to obtain an iron hydroxide precipitate;

[0018] (6) calcining the magnesium hydroxide leaching residue in step (5) to obtain a magnesium oxide product;

[0019] (7) subjecting the ferric hydroxide precipitate of step (5) to a second calcination to obtain ferric oxide, and then recovering the elemental iron product, and / or subjecting the ferric hydroxide precipitate of step (5) to acid leaching to obtain an iron-containing acid leaching solution, and then recovering the ferric phosphate product;

[0020] There is no order between step (2) and step (3), and there is no order between step (6) and step (7).

[0021] In the comprehensive recycling method described in the present application, Fe, Mg, Al, and P can be introduced into the first leachate by performing a first selective leaching on the laterite nickel ore hydrometallurgical slag, and the first leaching residue is calcium sulfate and silicon dioxide. The first leaching residue is subjected to a second selective leaching to obtain a calcium sulfate product and a sodium silicate solution. The first leachate containing sulfate and phosphoric acid is subjected to a third selective leaching to obtain metal hydroxides and a third leachate. The third leachate is a solution mainly containing sodium sulfate and sodium phosphate, which can be discharged after simple treatment, and the metal hydroxides are mainly Fe, M, and P. g, Al hydroxide, after the fourth selective leaching, can obtain iron magnesium hydroxide and sodium aluminate solution, realize Al leaching and separation from the metal hydroxide, the sodium aluminate solution can be used to recover aluminum oxide, and the iron magnesium hydroxide can be subjected to the fifth selective leaching to obtain magnesium hydroxide leaching residue and iron-containing leachate, realize the separation of Fe and Mg, the magnesium hydroxide leaching residue is subjected to the first calcination to obtain a magnesium oxide product, and the iron-containing leachate is cooled and diluted with water to obtain an iron hydroxide precipitate, which is subjected to the second calcination, and the obtained iron oxide is used to recover the elemental iron product and / or for recovering the iron phosphate product.

[0022] The comprehensive recycling and utilization method described in the present application mainly performs acid leaching, alkali leaching, calcination and other operations on the laterite nickel ore hydrometallurgical slag. In the process of recovering iron concentrate and / or ferric phosphate products, sodium silicate, calcium sulfate, magnesium oxide and aluminum oxide products can also be recovered, thereby maximizing the comprehensive recycling and utilization of the laterite nickel ore hydrometallurgical slag, thereby realizing the comprehensive development and utilization of laterite nickel ore resources; the comprehensive recycling and utilization method described in the present application does not discharge three wastes during the process, the process is green and environmentally friendly, the method is simple and feasible, and is conducive to promotion and application.

[0023] As an optional technical solution of the present application, the laterite nickel ore hydrometallurgical slag in step (1) is the metallurgical slag after high-pressure acid leaching of laterite nickel ore.

[0024] In one embodiment, the laterite-nickel ore hydrometallurgical slag in step (1) is limonitic laterite-nickel ore hydrometallurgical slag, that is, the limonitic laterite-nickel ore hydrometallurgical slag is the metallurgical slag obtained by smelting limonitic laterite-nickel ore through high-pressure acid leaching with sulfuric acid.

[0025] In one embodiment, the dry basis composition of the laterite nickel ore hydrometallurgical slag in step (1) satisfies the following: TFe 46-58wt%, SiO2 1.4-10.4wt%, MgO 1.2-11.2wt%, Al2O3 5.9-10.9wt%, and CaO 1.1-9.5wt%.

[0026] It is worth noting that TFe in laterite nickel ore hydrometallurgical slag refers to the total iron oxide content, that is, all contents including FeO, Fe2O3, and Fe3O4. Moreover, those skilled in the art are well aware that the sum of the dry basis composition measured in laterite nickel ore hydrometallurgical slag is not 100%, as this is the normal loss rate caused by instrument detection and is a normal situation caused by unified processing.

[0027] As an optional technical solution of the present application, before the first selective leaching in step (1), the laterite nickel ore hydrometallurgical slag is pretreated.

[0028] In one embodiment, the pretreatment includes drying, crushing and grinding performed in sequence to obtain laterite nickel ore hydrometallurgical fine powder slag.

[0029] As an optional technical solution of the present application, the first leaching agent in step (1) is a sulfuric acid solution, which can be a sulfuric acid solution with a concentration of 100-200 g / L, such as a sulfuric acid solution with a concentration of 100 g / L, a sulfuric acid solution with a concentration of 110 g / L, a sulfuric acid solution with a concentration of 120 g / L, a sulfuric acid solution with a concentration of 140 g / L, a sulfuric acid solution with a concentration of 150 g / L, a sulfuric acid solution with a concentration of 180 g / L or a sulfuric acid solution with a concentration of 200 g / L, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0030] In one embodiment, the oxidant in step (1) is hydrogen peroxide, which can be selected from hydrogen peroxide with a concentration of 20-100 g / L, such as 20 g / L hydrogen peroxide, 30 g / L hydrogen peroxide, 40 g / L hydrogen peroxide, 50 g / L hydrogen peroxide, 60 g / L hydrogen peroxide, 70 g / L hydrogen peroxide, 80 g / L hydrogen peroxide, 90 g / L hydrogen peroxide or 100 g / L hydrogen peroxide, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0031] In one embodiment, the volume ratio of the first leaching agent to the oxidant in step (1) is 0.9-1.1, for example, 0.9, 0.95, 1, 1.05 or 1.1, etc., but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0032] In one embodiment, the solid-liquid ratio of the first selective leaching in step (1) is 1 g: (0.5-2.0) mL, for example, 1 g: 0.5 mL, 1 g: 0.7 mL, 1 g: 0.8 mL, 1 g: 1.0 mL, 1 g: 1.1 mL, 1 g: 1.3 mL, 1 g: 1.5 mL, 1 g: 1.8 mL or 1 g: 2.0 mL, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0033] It is worth noting that the solid-liquid ratio of the first selective leaching in step (1) of the present application refers to the ratio of the laterite nickel ore hydrometallurgical slag to the sum of the sulfuric acid solution and the hydrogen peroxide liquid.

[0034] In one embodiment, the temperature of the first selective leaching in step (1) is 100-300°C, for example, 100°C, 130°C, 150°C, 180°C, 200°C, 230°C, 250°C, 280°C or 300°C, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0035] In one embodiment, the holding time of the first selective leaching in step (1) is 0.5-4 h, for example, 0.5 h, 0.8 h, 1 h, 1.3 h, 1.5 h, 1.8 h, 2 h, 2.3 h, 2.5 h, 2.8 h, 3 h, 3.3 h, 3.5 h, 3.8 h or 4 h, but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0036] In one embodiment, the stirring rate of the first selective leaching in step (1) is 100-300 rpm, for example, 100 rpm, 120 rpm, 140 rpm, 150 rpm, 180 rpm, 200 rpm, 230 rpm, 250 rpm, 270 rpm, 280 rpm or 300 rpm, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0037] As an optional technical solution of the present application, the second leaching agent in step (2) is a sodium hydroxide solution, which can be a sodium hydroxide solution with a concentration of 100-200 g / L, such as 100 g / L sodium hydroxide solution, 110 g / L sodium hydroxide solution, 120 g / L sodium hydroxide solution, 130 g / L sodium hydroxide solution, 150 g / L sodium hydroxide solution, 160 g / L sodium hydroxide solution, 180 g / L sodium hydroxide solution or 200 g / L sodium hydroxide solution, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are equally applicable.

[0038] In one embodiment, the solid-liquid ratio of the second selective leaching in step (2) is 1g:(0.9-1.9)mL, for example, 1g:0.9mL, 1g:1mL, 1g:1.1mL, 1g:1.2mL, 1g:1.3mL, 1g:1.4mL, 1g:1.5mL, 1g:1.6mL, 1g:1.7mL, 1g:1.8mL or 1g:1.9mL, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0039] In one embodiment, the temperature of the second selective leaching in step (2) is 70-150°C, for example, 70°C, 80°C, 90°C, 100°C, 110°C, 120°C, 130°C, 140°C or 150°C, but is not limited to the listed values. Other values ​​not listed within the above numerical range are also applicable.

[0040] In one embodiment, the holding time of the second selective leaching in step (2) is 0.5-2h, for example, 0.5h, 0.7h, 0.8h, 1h, 1.1h, 1.3h, 1.5h, 1.7h, 1.8h or 2h, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0041] In one embodiment, the stirring rate of the second selective leaching in step (2) is 150-350 rpm, for example, 150 rpm, 160 rpm, 180 rpm, 200 rpm, 210 rpm, 230 rpm, 250 rpm, 270 rpm, 280 rpm, 300 rpm, 310 rpm, 330 rpm or 350 rpm, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0042] As an optional technical solution of the present application, the third leaching agent in step (3) is a sodium hydroxide solution, which can be a sodium hydroxide solution with a concentration of 100-200 g / L, such as 100 g / L sodium hydroxide solution, 110 g / L sodium hydroxide solution, 120 g / L sodium hydroxide solution, 130 g / L sodium hydroxide solution, 150 g / L sodium hydroxide solution, 160 g / L sodium hydroxide solution, 180 g / L sodium hydroxide solution or 200 g / L sodium hydroxide solution, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are equally applicable.

[0043] In one embodiment, the volume ratio of the third selective leaching in step (3) is 1 ml: (0.5-1.5) mL, for example, 1 ml: 0.5 mL, 1 ml: 0.6 mL, 1 ml: 0.7 mL, 1 ml: 0.8 mL, 1 ml: 0.9 mL, 1 ml: 1.0 mL, 1 ml: 1.1 mL, 1 ml: 1.2 mL, 1 ml: 1.3 mL, 1 ml: 1.4 mL or 1 ml: 1.5 mL, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0044] In one embodiment, the temperature of the third selective leaching in step (3) is 80-150°C, for example, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C or 150°C, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0045] In one embodiment, the holding time of the third selective leaching in step (3) is 0.5-2h, for example, 0.5h, 0.7h, 0.8h, 1h, 1.1h, 1.3h, 1.5h, 1.7h, 1.8h or 2h, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0046] In one embodiment, the stirring rate of the third selective leaching in step (3) is 150-350 rpm, for example, 150 rpm, 160 rpm, 180 rpm, 200 rpm, 210 rpm, 230 rpm, 250 rpm, 270 rpm, 280 rpm, 300 rpm, 310 rpm, 330 rpm or 350 rpm, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0047] As an optional technical solution of the present application, the fourth leaching agent in step (4) is a sodium hydroxide solution, which can be a sodium hydroxide solution with a concentration of 100-200 g / L, such as 100 g / L sodium hydroxide solution, 110 g / L sodium hydroxide solution, 120 g / L sodium hydroxide solution, 130 g / L sodium hydroxide solution, 150 g / L sodium hydroxide solution, 160 g / L sodium hydroxide solution, 180 g / L sodium hydroxide solution or 200 g / L sodium hydroxide solution, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are equally applicable.

[0048] In one embodiment, the solid-liquid ratio of the fourth selective leaching in step (4) is 1 g: (1-3) mL, for example, 1 g: 1 mL, 1 g: 1.3 mL, 1 g: 1.5 mL, 1 g: 1.8 mL, 1 g: 2 mL, 1 g: 2.3 mL, 1 g: 2.5 mL, 1 g: 2.8 mL or 1 g: 3 mL, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0049] In one embodiment, the temperature of the fourth selective leaching in step (4) is 80-160°C, for example, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C or 160°C, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0050] In one embodiment, the holding time of the fourth selective leaching in step (4) is 0.5-2h, for example, 0.5h, 0.7h, 0.8h, 1h, 1.1h, 1.3h, 1.5h, 1.7h, 1.8h or 2h, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0051] In one embodiment, the stirring rate of the fourth selective leaching in step (4) is 150-350 rpm, for example, 150 rpm, 160 rpm, 180 rpm, 200 rpm, 210 rpm, 230 rpm, 250 rpm, 270 rpm, 280 rpm, 300 rpm, 310 rpm, 330 rpm or 350 rpm, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0052] As an optional technical solution of the present application, the fifth leaching agent in step (5) is a hot sodium hydroxide solution, which can be a sodium hydroxide solution with a concentration of 200-400 g / L, such as 200 g / L, 202 g / L, 240 g / L, 260 g / L, 280 g / L, 300 g / L, 320 g / L, 340 g / L, 360 g / L, 380 g / L or 400 g / L, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0053] It is worth noting that the fifth leaching agent in step (5) of the present application is a hot sodium hydroxide solution, and the temperature of the corresponding sodium hydroxide solution is 80-160°C, that is, consistent with the temperature of the fifth selective leaching.

[0054] In one embodiment, the solid-liquid ratio of the fifth selective leaching in step (5) is 1 g:(1-3) mL, for example, 1 g:1 mL, 1 g:1.3 mL, 1 g:1.5 mL, 1 g:1.8 mL, 1 g:2 mL, 1 g:2.3 mL, 1 g:2.5 mL, 1 g:2.8 mL or 1 g:3 mL, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0055] In one embodiment, the temperature of the fifth selective leaching in step (5) is 80-160°C, for example, 80°C, 85°C, 90°C, 95°C, 100°C, 105°C, 110°C, 115°C, 120°C, 125°C, 130°C, 135°C, 140°C, 145°C, 150°C, 155°C or 160°C, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0056] In one embodiment, the holding time of the fifth selective leaching in step (5) is 0.5-2h, for example, 0.5h, 0.7h, 0.8h, 1h, 1.1h, 1.3h, 1.5h, 1.7h, 1.8h or 2h, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0057] In one embodiment, the stirring rate of the fifth selective leaching in step (5) is 150-350 rpm, for example, 150 rpm, 160 rpm, 180 rpm, 200 rpm, 210 rpm, 230 rpm, 250 rpm, 270 rpm, 280 rpm, 300 rpm, 310 rpm, 330 rpm or 350 rpm, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0058] As an optional technical solution of the present application, the temperature of the first calcination in step (6) is 350-600°C, for example, 350°C, 380°C, 400°C, 430°C, 450°C, 480°C, 500°C, 530°C, 550°C, 580°C or 600°C, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0059] In one embodiment, the temperature of the second calcination in step (7) is 500-800°C, for example, 500°C, 530°C, 550°C, 580°C, 600°C, 620°C, 650°C, 670°C, 700°C, 730°C, 750°C, 780°C or 800°C, etc., but is not limited to the listed values, and other values ​​not listed within the above numerical range are also applicable.

[0060] As an optional technical solution of the present application, the method for using the sodium aluminate solution in step (4) to recover aluminum includes: adding Al(OH)3 seed crystals to the sodium aluminate solution, filtering after precipitating Al(OH)3 crystals to obtain a metallurgical grade Al(OH)3 product, and then calcining it to obtain an Al2O3 product.

[0061] It is worth noting that the above method of recovering Al2O3 products using sodium metaaluminate solution is a conventional method and will not be described in detail here.

[0062] In one embodiment, the method for recovering an elemental iron product from the iron oxide obtained in step (7) comprises: reducing the obtained iron oxide under a reducing atmosphere to obtain an elemental iron product, which is generally in the form of iron concentrate.

[0063] In one embodiment, the reducing atmosphere is H2 and / or CO.

[0064] It is worth noting that the above-mentioned method of reducing iron oxide to obtain an elemental iron product under a reducing atmosphere is a conventional method and will not be described in detail here.

[0065] In one embodiment, the acid solution used for acid leaching in step (7) is a hydrochloric acid solution.

[0066] In one embodiment, the step (7) of recovering the ferric phosphate product comprises: adding phosphoric acid and ammonia water to the iron-containing acid leaching solution for co-precipitation to obtain the ferric phosphate product.

[0067] It is worth noting that in the above-mentioned co-precipitation process using phosphoric acid and ammonia water, NH3·H2O and H3PO4 react to generate (NH4)3PO4 and H2O, and (NH4)3PO4 reacts with FeCl3 to generate FePO4 precipitate and obtain NH4Cl solution.

[0068] It is worth noting that the above-mentioned method of sequentially acid leaching and co-precipitation using iron oxide is a conventional method and will not be described in detail here.

[0069] Unless otherwise specified, the solutions described in this application refer to aqueous solutions, for example, a sulfuric acid solution refers to an aqueous sulfuric acid solution.

[0070] Compared with the existing technical solutions, this application has at least the following beneficial effects:

[0071] (1) The comprehensive recycling and utilization method described in this application mainly performs acid leaching, alkali leaching, calcination and other operations on the laterite nickel ore hydrometallurgical slag. In the process of recovering iron concentrate and / or ferric phosphate products, sodium silicate, calcium sulfate, magnesium oxide and aluminum oxide products can also be recovered, thereby maximizing the comprehensive recycling and utilization of the laterite nickel ore hydrometallurgical slag, thereby realizing the comprehensive development and utilization of laterite nickel ore resources;

[0072] (2) The comprehensive recycling and utilization method described in this application does not discharge three wastes during the process, the process is green and environmentally friendly, the method is simple and feasible, and is conducive to promotion and application.

[0073] Still other aspects will become apparent upon reading and understanding the accompanying drawings and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0074] The accompanying drawings are used to provide a further understanding of the technical solution of this article and constitute a part of the specification. Together with the embodiments of this application, they are used to explain the technical solution of this article and do not constitute a limitation on the technical solution of this article.

[0075] FIG1 is a process flow chart of the comprehensive recycling method of laterite nickel ore hydrometallurgical slag described in the present application. DETAILED DESCRIPTION

[0076] The technical solution of the present application will be further explained below with reference to the accompanying drawings and through specific implementation methods.

[0077] To better illustrate the present application and facilitate understanding of the technical solution of the present application, typical but non-limiting embodiments of the present application are as follows:

[0078] The present application provides a comprehensive recycling method for laterite nickel ore hydrometallurgical slag, the process flow chart of which is shown in FIG1 . The comprehensive recycling method comprises the following steps:

[0079] (1) mixing laterite nickel ore hydrometallurgical slag with a first leaching agent and an oxidant to perform a first selective leaching, and obtaining a first leaching residue (mainly containing CaSO4+SiO2) and a first leachate through a first solid-liquid separation;

[0080] (2) uniformly mixing the first leaching residue (mainly containing CaSO4+SiO2) of step (1) with a second leaching agent to perform a second selective leaching, and obtaining a calcium sulfate product and a sodium silicate solution through a second solid-liquid separation;

[0081] (3) uniformly mixing the first leachate obtained in step (1) with a third leachant to perform a third selective leaching, and obtaining a metal hydroxide and a third leachate through a third solid-liquid separation;

[0082] (4) uniformly mixing the metal hydroxide of step (3) with a fourth leaching agent to perform a fourth selective leaching, and obtaining iron magnesium hydroxide and a sodium aluminate solution through a fourth solid-liquid separation, wherein the sodium aluminate solution is used to recover aluminum; wherein the method for using the sodium aluminate solution to recover aluminum comprises: adding Al(OH)3 seed crystals to the sodium aluminate solution, precipitating Al(OH)3 crystals, filtering to obtain a metallurgical grade Al(OH)3 product, and then calcining to obtain an Al2O3 product;

[0083] (5) uniformly mixing the iron-magnesium hydroxide of step (4) with a fifth leaching agent to perform a fifth selective leaching, and obtaining magnesium hydroxide leaching residue and an iron-containing leachate through a fifth solid-liquid separation; cooling the iron-containing leachate and diluting it with water to obtain an iron hydroxide precipitate;

[0084] (6) calcining the magnesium hydroxide leaching residue in step (5) to obtain a magnesium oxide product;

[0085] (7) subjecting the iron hydroxide precipitate of step (5) to a second calcination to obtain iron oxide, and then calcining it under a reducing atmosphere of H2 and CO to obtain an elemental iron product, mainly iron concentrate;

[0086] and / or, acid leaching the iron hydroxide precipitate in step (5) with a hydrochloric acid solution to obtain an acid leaching solution containing FeCl3, and adding phosphoric acid and ammonia water for co-precipitation to obtain an iron phosphate product;

[0087] There is no order between step (2) and step (3), and there is no order between step (6) and step (7).

[0088] Example 1

[0089] This embodiment provides a comprehensive recycling method for laterite nickel ore hydrometallurgical slag, which comprises the following steps:

[0090] (1) drying, crushing and grinding the laterite nickel ore hydrometallurgical slag in sequence, and uniformly mixing the obtained laterite nickel ore hydrometallurgical fine powder slag with a sulfuric acid solution with a concentration of 100 g / L and a hydrogen peroxide solution with a concentration of 20 g / L to perform a first selective leaching, with a solid-liquid ratio of 1 g:0.5 mL, a temperature of 100 ° C, a holding time of 0.5 h, a stirring speed of 100 rpm, and obtaining a first leaching residue and a first leachate through a first solid-liquid separation;

[0091] The laterite nickel ore hydrometallurgical slag is a limonitic laterite nickel ore hydrometallurgical slag, and its dry basis composition satisfies the following: TFe 46-58wt%, SiO2 1.4-10.4wt%, MgO 1.2-11.2wt%, Al2O3 5.9-10.9wt%, and CaO 1.1-9.5wt%;

[0092] (2) the first leaching residue of step (1) was mixed evenly with a sodium hydroxide solution having a concentration of 100 g / L to perform a second selective leaching at a solid-liquid ratio of 1 g:0.9 mL, a temperature of 70° C., a holding time of 0.5 h, and a stirring rate of 150 rpm, and a calcium sulfate product and a sodium silicate solution were obtained by the second solid-liquid separation;

[0093] (3) The first leachate of step (1) was mixed evenly with a sodium hydroxide solution having a concentration of 100 g / L to perform a third selective leaching at a volume ratio of 1 mL:0.5 mL, a temperature of 80° C., a holding time of 0.5 h, and a stirring rate of 150 rpm, and a third solid-liquid separation was performed to obtain a metal hydroxide and a third leachate;

[0094] (4) The metal hydroxide of step (3) is mixed uniformly with a sodium hydroxide solution having a concentration of 100 g / L, and subjected to a fourth selective leaching, with a solid-liquid ratio of 1 g:1 mL, a temperature of 80° C., a holding time of 0.5 h, and a stirring rate of 150 rpm, to obtain iron magnesium hydroxide and a sodium aluminate solution through the fourth solid-liquid separation; Al(OH)3 seed crystals are added to the sodium aluminate solution, and Al(OH)3 crystals are precipitated and filtered to obtain a metallurgical grade Al(OH)3 product, which is then calcined to obtain an Al2O3 product;

[0095] (5) The iron-magnesium hydroxide of step (4) is uniformly mixed with a fifth leaching agent (hot sodium hydroxide solution) to perform a fifth selective leaching, with a solid-liquid ratio of 1 g:1 mL, a temperature of 80° C., a holding time of 0.5 h, and a stirring rate of 150 rpm, and the fifth solid-liquid separation is performed to obtain magnesium hydroxide leaching residue and an iron-containing leachate; the iron-containing leachate is cooled and diluted with water to obtain an iron hydroxide precipitate;

[0096] (6) calcining the magnesium hydroxide leaching residue in step (5) at 350° C. to obtain a magnesium oxide product;

[0097] (7) calcining the iron hydroxide precipitate in step (5) at 500° C. for a second time, and reducing the obtained iron oxide in a CO reducing atmosphere to obtain an elemental iron product;

[0098] There is no order between step (2) and step (3), and there is no order between step (6) and step (7).

[0099] Example 2

[0100] This embodiment provides a comprehensive recycling method for laterite nickel ore hydrometallurgical slag, which comprises the following steps:

[0101] (1) drying, crushing and grinding laterite nickel ore hydrometallurgical slag in sequence, and uniformly mixing the obtained laterite nickel ore hydrometallurgical fine powder slag with a sulfuric acid solution with a concentration of 150 g / L and a hydrogen peroxide solution with a concentration of 50 g / L to perform a first selective leaching, with a solid-liquid ratio of 1 g:1.0 mL, a temperature of 200 ° C, a holding time of 2 h, a stirring speed of 200 rpm, and obtaining a first leaching residue and a first leachate through a first solid-liquid separation;

[0102] The laterite nickel ore hydrometallurgical slag is a limonitic laterite nickel ore hydrometallurgical slag, and the dry basis composition satisfies the following: TFe 46-58wt%, SiO2 1.4-5.4wt%, MgO 1.2-5.2wt%, Al2O3 5.9-9.9wt%, and CaO 1.1-4.1wt%;

[0103] (2) the first leaching residue of step (1) was mixed evenly with a sodium hydroxide solution having a concentration of 150 g / L to perform a second selective leaching at a solid-liquid ratio of 1 g:1.3 mL, a temperature of 110° C., a holding time of 1 h, and a stirring rate of 250 rpm, and a calcium sulfate product and a sodium silicate solution were obtained by the second solid-liquid separation;

[0104] (3) The first leachate of step (1) was mixed evenly with a sodium hydroxide solution having a concentration of 150 g / L to perform a third selective leaching at a volume ratio of 1 mL:1 mL, a temperature of 110° C., a holding time of 1 h, and a stirring rate of 250 rpm, and a third solid-liquid separation was performed to obtain a metal hydroxide and a third leachate;

[0105] (4) The metal hydroxide of step (3) is mixed uniformly with a sodium hydroxide solution having a concentration of 150 g / L to perform a fourth selective leaching, with a solid-liquid ratio of 1 g:2 mL, a temperature of 120° C., a holding time of 1 h, and a stirring rate of 250 rpm, to obtain ferromagnesium hydroxide and a sodium aluminate solution through the fourth solid-liquid separation; Al(OH)3 seed crystals are added to the sodium aluminate solution, Al(OH)3 crystals are precipitated, and then filtered to obtain a metallurgical grade Al(OH)3 product, which is then calcined to obtain an Al2O3 product;

[0106] (5) The iron-magnesium hydroxide of step (4) is uniformly mixed with a fifth leaching agent (hot sodium hydroxide solution) to perform a fifth selective leaching, with a solid-liquid ratio of 1 g:2 mL, a temperature of 120° C., a holding time of 1 h, and a stirring rate of 250 rpm, and the fifth solid-liquid separation is performed to obtain magnesium hydroxide leaching residue and an iron-containing leachate; the iron-containing leachate is cooled and diluted with water to obtain an iron hydroxide precipitate;

[0107] (6) calcining the magnesium hydroxide leaching residue in step (5) at 450° C. to obtain a magnesium oxide product;

[0108] (7) calcining the iron hydroxide precipitate in step (5) at 650° C. for a second time, and reducing the obtained iron oxide in a CO reducing atmosphere to obtain an elemental iron product;

[0109] There is no order between step (2) and step (3), and there is no order between step (6) and step (7).

[0110] Example 3

[0111] This embodiment provides a comprehensive recycling method for laterite nickel ore hydrometallurgical slag, which comprises the following steps:

[0112] (1) drying, crushing and grinding the laterite nickel ore hydrometallurgical slag in sequence, and uniformly mixing the obtained laterite nickel ore hydrometallurgical fine powder slag with a sulfuric acid solution with a concentration of 200 g / L and a hydrogen peroxide solution with a concentration of 100 g / L to perform a first selective leaching, with a solid-liquid ratio of 1 g:2.0 mL, a temperature of 300 ° C, a holding time of 4 h, a stirring speed of 300 rpm, and obtaining a first leaching residue and a first leachate through a first solid-liquid separation;

[0113] The laterite nickel ore hydrometallurgical slag is a limonitic laterite nickel ore hydrometallurgical slag, and the dry basis composition satisfies the following: TFe 46-58wt%, SiO2 1.4-5.4wt%, MgO 1.2-5.2wt%, Al2O3 5.9-9.9wt%, and CaO 1.1-4.1wt%;

[0114] (2) the first leaching residue of step (1) was mixed evenly with a sodium hydroxide solution having a concentration of 200 g / L to perform a second selective leaching at a solid-liquid ratio of 1 g:1.9 mL, a temperature of 150° C., a holding time of 2 h, and a stirring rate of 350 rpm, and a calcium sulfate product and a sodium silicate solution were obtained through a second solid-liquid separation;

[0115] (3) The first leachate of step (1) was mixed evenly with a sodium hydroxide solution having a concentration of 200 g / L to perform a third selective leaching at a volume ratio of 1 mL:1.5 mL, a temperature of 150° C., a holding time of 2 h, and a stirring rate of 350 rpm, and a third solid-liquid separation was performed to obtain a metal hydroxide and a third leachate;

[0116] (4) The metal hydroxide of step (3) is mixed uniformly with a sodium hydroxide solution having a concentration of 200 g / L, and subjected to a fourth selective leaching, with a solid-liquid ratio of 1 g:3 mL, a temperature of 160° C., a holding time of 2 h, and a stirring rate of 350 rpm, to obtain iron magnesium hydroxide and a sodium aluminate solution through the fourth solid-liquid separation; Al(OH)3 seed crystals are added to the sodium aluminate solution, and Al(OH)3 crystals are precipitated and filtered to obtain a metallurgical grade Al(OH)3 product, which is then calcined to obtain an Al2O3 product;

[0117] (5) The iron-magnesium hydroxide of step (4) is uniformly mixed with a fifth leaching agent (hot sodium hydroxide solution) to perform a fifth selective leaching, with a solid-liquid ratio of 1 g:3 mL, a temperature of 160° C., a holding time of 2 h, and a stirring rate of 350 rpm, and the fifth solid-liquid separation is performed to obtain magnesium hydroxide leaching residue and an iron-containing leachate; the iron-containing leachate is cooled and diluted with water to obtain an iron hydroxide precipitate;

[0118] (6) calcining the magnesium hydroxide leaching residue in step (5) at 550° C. to obtain a magnesium oxide product;

[0119] (7) calcining the ferric hydroxide precipitate in step (5) at 800° C. for a second time, leaching the obtained ferric oxide with a hydrochloric acid solution to obtain a ferric chloride solution, adding phosphoric acid and ammonia water as precipitants to co-precipitate, and obtaining an ferric phosphate product;

[0120] There is no order between step (2) and step (3), and there is no order between step (6) and step (7).

[0121] The iron recovery rate of the comprehensive recycling method described in the above embodiment was measured, and the specific measurement results are shown in Table 1.

[0122] Table 1

[0123] In summary, the comprehensive recycling and utilization method described in the present application mainly performs acid leaching, alkali leaching, calcination and other operations on the laterite nickel ore hydrometallurgical slag. In the process of recovering iron concentrate and / or ferric phosphate products, sodium silicate, calcium sulfate, magnesium oxide and aluminum oxide products can also be recovered, thereby maximizing the comprehensive recycling and utilization of the laterite nickel ore hydrometallurgical slag, thereby realizing the comprehensive development and utilization of laterite nickel ore resources; the comprehensive recycling and utilization method described in the present application has no three wastes discharged during the process, the process is green and environmentally friendly, the method is simple and feasible, and is conducive to promotion and application.

[0124] The present application uses the above-mentioned embodiments to illustrate the detailed structural features of the present application. However, the present application is not limited to the above-mentioned detailed structural features, that is, it does not mean that the present application must rely on the above-mentioned detailed structural features to be implemented. Those skilled in the art should understand that any improvements to the present application, equivalent replacements of selected components of the present application, addition of auxiliary components, selection of specific methods, etc., all fall within the scope of protection and disclosure of the present application.

[0125] The preferred embodiments of the present application are described in detail above. However, the present application is not limited to the specific details of the above embodiments. Within the technical concept of the present application, various simple modifications can be made to the technical solution of the present application, and these simple modifications all fall within the scope of protection of the present application.

[0126] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner unless there is any contradiction. In order to avoid unnecessary repetition, this application will not further describe various possible combinations.

[0127] In addition, the various implementation methods of the present application may be arbitrarily combined, and as long as they do not violate the concept of the present application, they should also be regarded as the contents disclosed in the present application.

Claims

1. A comprehensive recycling method for laterite nickel ore hydrometallurgical slag, comprising the following steps: (1) Mix the laterite nickel ore hydrometallurgical slag evenly with a first leaching agent and an oxidant for first selective leaching, and obtain a first leaching residue and a first leaching solution through first solid-liquid separation; (2) Mix the first leaching residue obtained in step (1) evenly with a second leaching agent for second selective leaching, and obtain a calcium sulfate product and a sodium silicate solution through second solid-liquid separation; (3) Mix the first leaching solution obtained in step (1) evenly with a third leaching agent for third selective leaching, and obtain metal hydroxides and a third leaching solution through third solid-liquid separation; (4) Mix the metal hydroxides obtained in step (3) evenly with a fourth leaching agent for fourth selective leaching, and obtain iron and magnesium hydroxides and a sodium metaaluminate solution through fourth solid-liquid separation, and the sodium metaaluminate solution is used for aluminum recovery; (5) Mix the iron and magnesium hydroxides obtained in step (4) evenly with a fifth leaching agent for fifth selective leaching, and obtain a magnesium hydroxide leaching residue and an iron-containing leaching solution through fifth solid-liquid separation; dilute the iron-containing leaching solution by cooling and adding water to obtain iron hydroxide precipitation; (6) Conduct first calcination on the magnesium hydroxide leaching residue obtained in step (5) to obtain a magnesium oxide product; (7) Conduct second calcination on the iron hydroxide precipitation obtained in step (5) to obtain iron oxide, and then recover a metallic iron product, and / or acid-leach the iron hydroxide precipitation obtained in step (5) to obtain an iron-containing acid leaching solution, and then recover a ferric phosphate product; Wherein, There is no sequential order between step (2) and step (3), and there is no sequential order between step (6) and step (7).

2. The comprehensive recycling method according to claim 1, Wherein, The laterite nickel ore hydrometallurgical slag in step (1) is the metallurgical slag after high-pressure acid leaching of laterite nickel ore; Optionally, the laterite nickel ore hydrometallurgical slag in step (1) is the laterite nickel ore hydrometallurgical slag of limonite type; Optionally, the dry basis composition of the laterite nickel ore hydrometallurgy slag described in step (1) satisfies: TFe 46-58 wt%, SiO 2 1.4-10.4 wt%, MgO 1.2-11.2 wt%, Al 2 O 3 5.9-10.9 wt%, CaO 1.1-9.5 wt%.

3. The comprehensive recycling method according to claim 1 or 2, Wherein, Before the first selective leaching in step (1), pretreatment is performed on the laterite nickel ore hydrometallurgical slag; Optionally, the pretreatment includes drying, crushing and grinding in sequence.

4. The comprehensive recycling method according to any one of claims 1-3, Wherein, The first leaching agent in step (1) is a sulfuric acid solution, preferably a sulfuric acid solution with a concentration of 100-200 g / L; Optionally, the oxidant in step (1) is hydrogen peroxide, and further optionally hydrogen peroxide with a concentration of 20-100 g / L; Optionally, the volume ratio of the first leaching agent to the oxidant in step (1) is 0.9-1.1; Optionally, the solid-liquid ratio of the first selective leaching in step (1) is 1 g:(0.5-2.0) mL; Optionally, the temperature of the first selective leaching in step (1) is 100-300 °C; Optionally, the heat preservation time of the first selective leaching in step (1) is 0.5-4 h; Optionally, the stirring rate of the first selective leaching in step (1) is 100-300 rpm.

5. The comprehensive recycling method according to any one of claims 1-4, Among them, in step (2), the second leaching agent is a sodium hydroxide solution, and further preferably a sodium hydroxide solution with a concentration of 100-200 g / L; Optionally, the solid-liquid ratio of the second selective leaching in step (2) is 1 g:(0.9-1.9) mL; Optionally, the temperature of the second selective leaching in step (2) is 70-150 °C; Optionally, the heat preservation time of the second selective leaching in step (2) is 0.5-2 h; Optionally, the stirring rate of the second selective leaching in step (2) is 150-350 rpm.

6. The comprehensive recycling method according to any one of claims 1-5, wherein, in step (3), the third leaching agent is a sodium hydroxide solution, and further preferably a sodium hydroxide solution with a concentration of 100-200 g / L; Optionally, the volume ratio of the third selective leaching in step (3) is 1 ml:(0.5-1.5) mL; Optionally, the temperature of the third selective leaching in step (3) is 80-150 °C; Optionally, the heat preservation time of the third selective leaching in step (3) is 0.5-2 h; Optionally, the stirring rate of the third selective leaching in step (3) is 150-350 rpm.

7. The comprehensive recycling method according to any one of claims 1-6, wherein, in step (4), the fourth leaching agent is a sodium hydroxide solution, and further preferably a sodium hydroxide solution with a concentration of 100-200 g / L; Optionally, the solid-liquid ratio of the fourth selective leaching in step (4) is 1 g:(1-3) mL; Optionally, the temperature of the fourth selective leaching in step (4) is 80-160 °C; Optionally, the heat preservation time of the fourth selective leaching in step (4) is 0.5-2 h; Optionally, the stirring rate of the fourth selective leaching in step (4) is 150-350 rpm.

8. The comprehensive recycling method according to any one of claims 1-7, wherein, in step (5), the fifth leaching agent is a hot sodium hydroxide solution, and further preferably a sodium hydroxide solution with a concentration of 200-400 g / L; Optionally, the solid-liquid ratio of the fifth selective leaching in step (5) is 1 g:(1-3) mL; Optionally, the temperature of the fifth selective leaching in step (5) is 80-160 °C; Optionally, the heat preservation time of the fifth selective leaching in step (5) is 0.5-2 h; Optionally, the stirring rate of the fifth selective leaching in step (5) is 150-350 rpm.

9. The comprehensive recycling method according to any one of claims 1-8, wherein, the temperature of the first calcination in step (6) is 350-600 °C; Optionally, the temperature of the second calcination in step (7) is 500-800 °C.

10. The comprehensive recycling method according to any one of claims 1-9, wherein, The method for recycling aluminum using the sodium aluminate solution described in step (4) includes: adding Al(OH) 3 seed crystals to the sodium aluminate solution, precipitating Al(OH) 3 crystals, filtering to obtain a metallurgical grade Al(OH) 3 product, and then calcining it to produce an Al 2 O 3 product; Optionally, the method for using the obtained iron oxide to recover the elemental iron product in step (7) includes: reducing the obtained iron oxide in a reducing atmosphere to obtain the elemental iron product; Optionally, the reducing atmosphere is H 2 and / or CO; Optionally, the acid solution used in the acid leaching in step (7) is a hydrochloric acid solution; Optionally, the recycled iron phosphate product in step (7) includes: adding the iron-containing acid leaching solution to phosphoric acid and ammonia water for coprecipitation to obtain an iron phosphate product.

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